dgsm Proxy Cache design WIP

Change-Id: Ifa322e84fadd3b04943c8c7024c0e2de4935bed0

.gitignore

@@ -36,6 +36,7 @@ src/osmo-hlr
 src/osmo-hlr-db-tool
 src/osmo-euse-demo
 src/gsupclient/gsup-test-client
+src/mslookup/osmo-mslookup-client
 
 tests/atconfig
 tests/testsuite
@@ -51,6 +52,10 @@ tests/gsup/gsup_test
 tests/db/db_test
 tests/hlr_vty_test.db*
 tests/db_upgrade/*.dump
+tests/mslookup/mdns_test
+tests/mslookup/mslookup_client_mdns_test
+tests/mslookup/mslookup_client_test
+tests/mslookup/mslookup_test
 
 # manuals
 doc/manuals/*.html

Makefile.am

@@ -17,7 +17,8 @@ AM_DISTCHECK_CONFIGURE_FLAGS = \
 	--with-systemdsystemunitdir=$$dc_install_base/$(systemdsystemunitdir)
 
 pkgconfigdir = $(libdir)/pkgconfig
-pkgconfig_DATA = libosmo-gsup-client.pc
+pkgconfig_DATA = libosmo-gsup-client.pc \
+		 libosmo-mslookup.pc
 
 @RELMAKE@
 

configure.ac

@@ -25,6 +25,11 @@ AC_PROG_MKDIR_P
 AC_PROG_CC
 AC_PROG_INSTALL
 
+dnl patching ${archive_cmds} to affect generation of file "libtool" to fix linking with clang 
+AS_CASE(["$LD"],[*clang*],
+  [AS_CASE(["${host_os}"],
+     [*linux*],[archive_cmds='$CC -shared $pic_flag $libobjs $deplibs $compiler_flags $wl-soname $wl$soname -o $lib'])])
+
 dnl check for pkg-config (explained in detail in libosmocore/configure.ac)
 AC_PATH_PROG(PKG_CONFIG_INSTALLED, pkg-config, no)
 if test "x$PKG_CONFIG_INSTALLED" = "xno"; then
@@ -34,10 +39,10 @@ PKG_PROG_PKG_CONFIG([0.20])
 
 PKG_CHECK_MODULES(TALLOC, [talloc >= 2.0.1])
 
-PKG_CHECK_MODULES(LIBOSMOCORE, libosmocore >= 1.2.0)
-PKG_CHECK_MODULES(LIBOSMOGSM, libosmogsm >= 1.2.0)
-PKG_CHECK_MODULES(LIBOSMOVTY, libosmovty >= 1.2.0)
-PKG_CHECK_MODULES(LIBOSMOCTRL, libosmoctrl >= 1.2.0)
+PKG_CHECK_MODULES(LIBOSMOCORE, libosmocore >= 1.3.0)
+PKG_CHECK_MODULES(LIBOSMOGSM, libosmogsm >= 1.3.0)
+PKG_CHECK_MODULES(LIBOSMOVTY, libosmovty >= 1.3.0)
+PKG_CHECK_MODULES(LIBOSMOCTRL, libosmoctrl >= 1.3.0)
 PKG_CHECK_MODULES(LIBOSMOABIS, libosmoabis >= 0.6.0)
 
 PKG_CHECK_MODULES(SQLITE3, sqlite3)
@@ -107,6 +112,15 @@ AC_MSG_CHECKING([whether to enable VTY/CTRL tests])
 AC_MSG_RESULT([$enable_ext_tests])
 AM_CONDITIONAL(ENABLE_EXT_TESTS, test "x$enable_ext_tests" = "xyes")
 
+# mslookup_client_mdns_test (OS#4385: does not work everywhere)
+AC_ARG_ENABLE([mslookup_client_mdns_test],
+		AC_HELP_STRING([--enable-mslookup-client-mdns-test],
+				[Include the mslookup_client_mdns_test in make check [default=no]]),
+		[enable_mslookup_client_mdns_test="$enableval"],[enable_mslookup_client_mdns_test="no"])
+AC_MSG_CHECKING([whether to enable mslookup_client_mdns_test])
+AC_MSG_RESULT([$enable_mslookup_client_mdns_test])
+AM_CONDITIONAL(ENABLE_MSLOOKUP_CLIENT_MDNS_TEST, test "x$enable_mslookup_client_mdns_test" = "xyes")
+
 # Generate manuals
 AC_ARG_ENABLE(manuals,
 	[AS_HELP_STRING(
@@ -172,20 +186,27 @@ AC_OUTPUT(
 	Makefile
 	doc/Makefile
 	doc/examples/Makefile
+	doc/sequence_charts/Makefile
 	src/Makefile
 	src/gsupclient/Makefile
+	src/mslookup/Makefile
 	include/Makefile
 	include/osmocom/Makefile
 	include/osmocom/hlr/Makefile
+	include/osmocom/mslookup/Makefile
 	libosmo-gsup-client.pc
+	libosmo-mslookup.pc
 	sql/Makefile
 	doc/manuals/Makefile
 	contrib/Makefile
 	contrib/systemd/Makefile
+	contrib/dgsm/Makefile
 	tests/Makefile
 	tests/auc/Makefile
 	tests/auc/gen_ts_55_205_test_sets/Makefile
 	tests/gsup_server/Makefile
+	tests/gsup/Makefile
 	tests/db/Makefile
 	tests/db_upgrade/Makefile
+	tests/mslookup/Makefile
 	)

contrib/Makefile.am

@@ -1 +1,4 @@
-SUBDIRS = systemd
+SUBDIRS = \
+	systemd \
+	dgsm \
+	$(NULL)

contrib/dgsm/Makefile.am

@@ -0,0 +1,6 @@
+EXTRA_DIST = \
+	esme_dgsm.py \
+	freeswitch_dialplan_dgsm.py \
+	osmo-mslookup-pipe.py \
+	osmo-mslookup-socket.py \
+	$(NULL)

contrib/dgsm/esme_dgsm.py

@@ -0,0 +1,184 @@
+#!/usr/bin/env python3
+"""
+SPDX-License-Identifier: MIT
+Copyright 2019 sysmocom s.f.m.c GmbH <info@sysmocom.de>
+
+WARNING: this is just a proof-of-concept implementation, it blocks for every
+received SMPP request and is not suitable for servicing more than one request
+at a time.
+
+Based on esme.py from RCCN (license changed with permission from author):
+https://github.com/Rhizomatica/rccn/blob/master/rccn/esme.py
+Copyright 2017 keith <keith@rhizomatica.org>
+
+Forward SMS to the receiver's SMSC, as determined with mslookup.
+Requires smpplip (pip3 install --user smpplib) and osmo-mslookup-client.
+
+Example SMPP configuration for osmo-msc.cfg:
+smpp
+ local-tcp-ip 127.0.0.1 2775
+ policy closed
+ smpp-first
+# outgoing to esme_dgsm.py
+ esme OSMPP
+  no alert-notifications
+  password foo
+  default-route
+# incoming from esme_dgsm.py
+ esme ISMPP
+  no alert-notifications
+  password foo
+"""
+import argparse
+import json
+import logging
+import smpplib
+import subprocess
+import time
+
+
+def can_handle_pdu(pdu):
+    if not isinstance(pdu, smpplib.command.DeliverSM):
+        logging.info('PDU is not a DeliverSM, ignoring')
+        return False
+
+    if int(pdu.dest_addr_ton) == smpplib.consts.SMPP_TON_INTL:
+        logging.info("Unable to handle SMS for %s: SMPP_TON_INTL" %
+                     (pdu.destination_addr))
+        return False
+
+    return True
+
+
+def query_mslookup(service_type, id, id_type='msisdn'):
+    query_str = '%s.%s.%s' % (service_type, id, id_type)
+    logging.info('mslookup: ' + query_str)
+
+    result_line = subprocess.check_output(['osmo-mslookup-client', query_str,
+                                           '-f', 'json'])
+    if isinstance(result_line, bytes):
+        result_line = result_line.decode('ascii')
+
+    logging.info('mslookup result: ' + result_line.rstrip())
+    return json.loads(result_line)
+
+
+def tx_sms(dst_host, dst_port, source, destination, registered_delivery,
+           unicode_text):
+    smpp_client = smpplib.client.Client(dst_host, dst_port, 90)
+    smpp_client.connect()
+    smpp_client.bind_transceiver(system_id=args.dst_id, password=args.dst_pass)
+    logging.info('Connected to destination SMSC (%s@%s:%s)' % (args.dst_id,
+                 dst_host, dst_port))
+
+    pdu = smpp_client.send_message(
+        source_addr_ton=smpplib.consts.SMPP_TON_ALNUM,
+        source_addr_npi=smpplib.consts.SMPP_NPI_UNK,
+        source_addr=source.decode(),
+        dest_addr_ton=smpplib.consts.SMPP_TON_SBSCR,
+        dest_addr_npi=smpplib.consts.SMPP_NPI_ISDN,
+        destination_addr=destination.decode(),
+        short_message=unicode_text,
+        registered_delivery=registered_delivery,
+    )
+
+    smpp_client.unbind()
+    smpp_client.disconnect()
+    del pdu
+    del smpp_client
+
+
+def rx_deliver_sm(pdu):
+    if not can_handle_pdu(pdu):
+        return smpplib.consts.SMPP_ESME_RSYSERR
+
+    msisdn = pdu.destination_addr.decode()
+    logging.info("Incoming SMS for: " + msisdn)
+
+    if args.sleep:
+        logging.info("Sleeping for %i seconds" % (args.sleep))
+        time.sleep(args.sleep)
+        logging.info("Sleep done")
+
+    if args.always_fail is not None:
+        return args.always_fail
+
+    result = query_mslookup("smpp.sms", msisdn)
+    if 'v4' not in result or not result['v4']:
+        logging.info('No IPv4 result from mslookup! This example only'
+                     ' makes use of IPv4, dropping.')
+        return smpplib.consts.SMPP_ESME_RSYSERR
+
+    dst_host, dst_port = result['v4']
+    tx_sms(dst_host, dst_port, pdu.source_addr,
+           pdu.destination_addr, int(pdu.registered_delivery),
+           pdu.short_message)
+
+    return smpplib.consts.SMPP_ESME_ROK
+
+
+def smpp_bind():
+    client = smpplib.client.Client(args.src_host, args.src_port, 90)
+    client.set_message_received_handler(rx_deliver_sm)
+    client.connect()
+    client.bind_transceiver(system_id=args.src_id, password=args.src_pass)
+    logging.info('Connected to source SMSC (%s@%s:%s)' % (args.src_id,
+                 args.src_host, args.src_port))
+    logging.info('Waiting for SMS...')
+    client.listen()
+
+
+def main():
+    global args
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--src-host', default='127.0.0.1',
+                        help='source SMSC (OsmoMSC) host (default: 127.0.0.1)')
+    parser.add_argument('--src-port', default=2775, type=int,
+                        help='source SMSC (OsmoMSC) port (default: 2775)')
+    parser.add_argument('--src-id', default='OSMPP',
+                        help='source system id, as configured in osmo-msc.cfg'
+                             ' (default: OSMPP)')
+    parser.add_argument('--src-pass', default='foo',
+                        help='source system password, as configured in'
+                             ' osmo-msc.cfg (default: foo)')
+    parser.add_argument('--dst-id', default='ISMPP',
+                        help='destination system id, as configured in'
+                             ' osmo-msc.cfg (default: ISMPP)')
+    parser.add_argument('--dst-pass', default='foo',
+                        help='destination system password, as configured in'
+                             ' osmo-msc.cfg (default: foo)')
+    parser.add_argument('--sleep', default=0, type=float,
+                        help='sleep time in seconds before forwarding an SMS,'
+                             ' to test multithreading (default: 0)')
+    parser.add_argument('--always-fail', default=None, metavar='SMPP_ESME_ERRCODE',
+                        help='test delivery failure: always return an error code on Deliver-SM,'
+                        ' pass an smpplib error code name like RDELIVERYFAILURE (see smpplib/consts.py),'
+                        ' or an SMPP error code in hex digits')
+    args = parser.parse_args()
+
+    logging.basicConfig(level=logging.INFO, format='[%(asctime)s]'
+                        ' (%(threadName)s) %(message)s', datefmt="%H:%M:%S")
+
+    if args.always_fail:
+        resolved = None
+        name = 'SMPP_ESME_' + args.always_fail
+        if hasattr(smpplib.consts, name):
+            resolved = getattr(smpplib.consts, name)
+        if resolved is None:
+            try:
+                resolved = int(args.always_fail, 16)
+            except ValueError:
+                resolved = None
+        if resolved is None:
+            print('Invalid argument for --always-fail: %r' % args.always_fail)
+            exit(1)
+        args.always_fail = resolved
+        logging.info('--always-fail: returning error code %s to all Deliver-SM' % hex(args.always_fail))
+
+    smpp_bind()
+
+
+if __name__ == "__main__":
+    main()
+
+# vim: expandtab tabstop=4 shiftwidth=4

contrib/dgsm/freeswitch_dialplan_dgsm.py

@@ -0,0 +1,77 @@
+#!/usr/bin/env python3
+"""
+SPDX-License-Identifier: MIT
+Copyright 2019 sysmocom s.f.m.c GmbH <info@sysmocom.de>
+
+This is a freeswitch dialplan implementation, see:
+https://freeswitch.org/confluence/display/FREESWITCH/mod_python
+
+Find the right SIP server with mslookup (depending on the destination number)
+and bridge calls accordingly.
+"""
+import json
+import subprocess
+
+
+def query_mslookup(service_type, id, id_type='msisdn'):
+    query_str = '%s.%s.%s' % (service_type, id, id_type)
+    print('[dialplan-dgsm] mslookup: ' + query_str)
+
+    result_line = subprocess.check_output([
+        'osmo-mslookup-client', query_str, '-f', 'json'])
+    if isinstance(result_line, bytes):
+        result_line = result_line.decode('ascii')
+
+    print('[dialplan-dgsm] mslookup result: ' + result_line)
+    return json.loads(result_line)
+
+
+def handler(session, args):
+    """ Handle calls: bridge to the SIP server found with mslookup. """
+    print('[dialplan-dgsm] call handler')
+    msisdn = session.getVariable('destination_number')
+
+    # Run osmo-mslookup-client binary. We have also tried to directly call the
+    # C functions with ctypes but this has lead to hard-to-debug segfaults.
+    try:
+        result = query_mslookup("sip.voice", msisdn)
+
+        # This example only makes use of IPv4
+        if not result['v4']:
+            print('[dialplan-dgsm] no IPv4 result from mslookup')
+            session.hangup('UNALLOCATED_NUMBER')
+            return
+
+        sip_ip, sip_port = result['v4']
+        dial_str = 'sofia/internal/sip:{}@{}:{}'.format(
+            msisdn, sip_ip, sip_port)
+        print('[dialplan-dgsm] dial_str: ' + str(dial_str))
+
+        session.execute('bridge', dial_str)
+    except:
+        print('[dialplan-dgsm]: exception during call handler')
+        session.hangup('UNALLOCATED_NUMBER')
+
+
+def fsapi(session, stream, env, args):
+    """ Freeswitch refuses to load the module without this. """
+    stream.write(env.serialize())
+
+
+def main():
+    import argparse
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument('id', type=int)
+    parser.add_argument('-i', '--id-type', default='msisdn',
+                        help='default: "msisdn"')
+    parser.add_argument('-s', '--service', default='sip.voice',
+                        help='default: "sip.voice"')
+    args = parser.parse_args()
+
+    result = query_mslookup(args.service, args.id, args.id_type)
+    print(json.dumps(result))
+
+
+if __name__ == '__main__':
+    main()

contrib/dgsm/osmo-mslookup-pipe.py

@@ -0,0 +1,24 @@
+#!/usr/bin/env python3
+# vim: shiftwidth=4 tabstop=4 expandtab
+import subprocess
+import json
+
+def query_mslookup(query_str):
+    result = {'result': 'not-found'}
+    proc = subprocess.Popen(('osmo-mslookup-client', '-f', 'json', query_str),
+		            stdout=subprocess.PIPE)
+    for line in iter(proc.stdout.readline,''):
+        if not line:
+            break
+        response = json.loads(line)
+        if response.get('result') == 'result':
+                result = response
+        print('Response: %r' % response)
+    return result
+
+if __name__ == '__main__':
+    import sys
+    query_str = '1000-5000@sip.voice.12345.msisdn'
+    if len(sys.argv) > 1:
+        query_str = sys.argv[1]
+    print('Final result: %r' % query_mslookup(query_str))

contrib/dgsm/osmo-mslookup-socket.py

@@ -0,0 +1,35 @@
+#!/usr/bin/env python3
+# vim: shiftwidth=4 tabstop=4 expandtab
+import socket
+import time
+
+MSLOOKUP_SOCKET_PATH = '/tmp/mslookup'
+
+def query_mslookup_socket(query_str, socket_path=MSLOOKUP_SOCKET_PATH):
+    mslookup_socket = socket.socket(socket.AF_UNIX, socket.SOCK_SEQPACKET)
+    mslookup_socket.setblocking(True)
+    mslookup_socket.connect(socket_path)
+    result = {'result': 'not-found'}
+    column_names = mslookup_socket.recv(1024).decode('ascii')
+    if not column_names:
+        return result
+    column_names = column_names.split('\t')
+    mslookup_socket.sendall(query_str.encode('ascii'))
+    while True:
+        csv = mslookup_socket.recv(1024).decode('ascii')
+        if not csv:
+            break
+        response = dict(zip(column_names, csv.split('\t')))
+        if response.get('result') == 'result':
+            result = response
+        print('Response: %r' % response)
+    return result
+
+if __name__ == '__main__':
+    import sys
+    print(
+        '\nPlease run separately: osmo-mslookup-client --socket /tmp/mslookup -d\n')
+    query_str = '1000-5000@sip.voice.12345.msisdn'
+    if len(sys.argv) > 1:
+        query_str = sys.argv[1]
+    print('Final result: %r' % query_mslookup_socket(query_str))

contrib/jenkins.sh

@@ -49,7 +49,12 @@ set -x
 
 cd "$base"
 autoreconf --install --force
-./configure --enable-sanitize --enable-external-tests --enable-werror $CONFIG
+./configure \
+	--enable-sanitize \
+	--enable-external-tests \
+	--enable-mslookup-client-mdns-test \
+	--enable-werror \
+	$CONFIG
 $MAKE $PARALLEL_MAKE
 $MAKE check || cat-testlogs.sh
 DISTCHECK_CONFIGURE_FLAGS="$CONFIG" $MAKE distcheck || cat-testlogs.sh

debian/changelog

@@ -1,3 +1,45 @@
+osmo-hlr (1.2.0) unstable; urgency=medium
+
+  [ Ruben Undheim ]
+  * Fix test for return codes on mipsel and alpha archs
+
+  [ Thorsten Alteholz ]
+  * fix spelling errors detected by lintian
+
+  [ Pau Espin Pedrol ]
+  * tests: Fix db_test err file to expect error code name instead of value
+
+  [ Oliver Smith ]
+  * tests/test_nodes.vty: check less libosmocore cmds
+  * tests/db_upgrade: disable for old sqlite versions
+  * gitignore: add tests/db_upgrade/*.dump
+  * gsup_client.h: fix license header: GPLv2+
+  * tests/auc: change back to python3
+
+  [ Neels Hofmeyr ]
+  * fix double free in osmo_gsup_client_enc_send()
+  * db upgrade to v2: log version 2, not 1
+  * fix upgrade to version 2: imei column default value
+  * add --db-check option
+  * hlr.sql: move comment
+  * add db_upgrade test
+  * hlr db schema 3: hlr_number -> msc_number
+  * db.c: code dup: add db_run_statements() for arrays of statements
+  * move headers to include/osmocom/hlr
+  * fix upgrade test in presence of ~/.sqliterc
+  * db upgrade: remove some code dup
+  * add osmo_gsup_msgb_alloc()
+  * Makefile convenience: add VTY_TEST var to run only one test
+  * remove gsup_test
+  * test_nodes.vty: tweak: add some '?' checks
+  * db v4: add column last_lu_seen_ps
+
+  [ Harald Welte ]
+  * AUC: Add support for setting the AMF separation bit to '1' for EUTRAN
+  * hlr: exit(2) on unsupported positional arguments on command line
+
+ -- Pau Espin Pedrol <pespin@sysmocom.de>  Fri, 03 Jan 2020 12:37:35 +0100
+
 osmo-hlr (1.1.0) unstable; urgency=medium
 
   [ Oliver Smith ]

debian/control

@@ -59,6 +59,28 @@ Description: Development headers of Osmocom GSUP client library
   .
   This package contains the development headers.
 
+Package: libosmo-mslookup0
+Section: libs
+Architecture: any
+Multi-Arch: same
+Depends: ${shlibs:Depends},
+         ${misc:Depends}
+Pre-Depends: ${misc:Pre-Depends}
+Description: Osmocom MS lookup library
+  This shared library contains routines for looking up mobile subscribers.
+
+Package: libosmo-mslookup-dev
+Architecture: any
+Multi-Arch: same
+Depends: ${misc:Depends},
+	 libosmo-mslookup0 (= ${binary:Version}),
+	 libosmocore-dev
+Pre-Depends: ${misc:Pre-Depends}
+Description: Development headers of Osmocom MS lookup library
+  This shared library contains routines for looking up mobile subscribers.
+  .
+  This package contains the development headers.
+
 Package: osmo-hlr-doc
 Architecture: all
 Section: doc

debian/libosmo-mslookup-dev.install

@@ -0,0 +1,5 @@
+usr/include/osmocom/mslookup
+usr/lib/*/libosmo-mslookup*.a
+usr/lib/*/libosmo-mslookup*.so
+usr/lib/*/libosmo-mslookup*.la
+usr/lib/*/pkgconfig/libosmo-mslookup.pc

debian/libosmo-mslookup0.install

@@ -0,0 +1 @@
+usr/lib/*/libosmo-mslookup*.so.*

doc/Makefile.am

@@ -1,4 +1,5 @@
 SUBDIRS = \
 	examples \
 	manuals \
+       sequence_charts \
 	$(NULL)

doc/examples/osmo-hlr-dgsm.cfg

@@ -0,0 +1,22 @@
+# OsmoHLR example configuration for Distributed GSM (mslookup)
+hlr
+ gsup
+  # For D-GSM roaming, osmo-hlr's GSUP must listen on a public IP:
+  bind ip 10.9.8.7
+  # Each HLR should identify with a distinct name
+  ipa-name hlr-23
+mslookup
+ # Bind mslookup mDNS server and client on default multicast address and port:
+ # 239.192.23.42 port 4266
+ mdns bind
+ # Tell the mslookup server in osmo-hlr which IP+ports to return when a
+ # remote voice call or SMS wants to deliver to a local subscriber:
+ server
+  # local osmo-sip-connector SIP port
+  service sip.voice at 10.9.8.7 5060
+  # local osmo-msc SMPP port
+  service smpp.sms at 10.9.8.7 2775
+  # experimental: SMS-over-GSUP: this HLR's GSUP port
+  service gsup.sms at 10.9.8.7 4222
+  # only required if different from above 'gsup'/'bind ip':
+  #service gsup.hlr at 10.9.8.7 4222

doc/manuals/Makefile.am

@@ -4,13 +4,18 @@ EXTRA_DIST = example_subscriber_add_update_delete.vty \
     osmohlr-usermanual.adoc \
     osmohlr-usermanual-docinfo.xml \
     osmohlr-vty-reference.xml \
+    chapters/proxy_cache_attach.msc \
+    chapters/proxy_cache_more_tuples.msc \
+    chapters/proxy_cache_periodic_lu.msc \
+    chapters/proxy_cache_tuple_cache_dry.msc \
+    chapters/proxy_cache_umts_aka_resync.msc \
     regen_doc.sh \
     chapters \
     vty
 
 if BUILD_MANUALS
   ASCIIDOC = osmohlr-usermanual.adoc
-  ASCIIDOC_DEPS = $(srcdir)/chapters/*.adoc $(srcdir)/*.vty $(srcdir)/*.ctrl
+  ASCIIDOC_DEPS = $(srcdir)/chapters/*.adoc $(srcdir)/*.vty $(srcdir)/*.ctrl $(srcdir)/chapters/*.msc
   include $(OSMO_GSM_MANUALS_DIR)/build/Makefile.asciidoc.inc
 
   VTY_REFERENCE = osmohlr-vty-reference.xml

doc/manuals/chapters/Makefile

@@ -0,0 +1,20 @@
+all: \
+	proxy_cache_attach.msc \
+	proxy_cache_more_tuples.msc \
+	proxy_cache_tuple_cache_dry.msc \
+	proxy_cache_periodic_lu.msc \
+	proxy_cache_umts_aka_resync.msc \
+	$(NULL)
+
+png: \
+	proxy_cache.png \
+	proxy_cache_unused.png \
+	lu_attach_and_periodic.png \
+	$(NULL)
+
+%.png: %.msc
+	mscgen -T png -o $@ $<
+
+%.msc: %.ladder
+	@which ladder_to_msc.py || (echo 'PLEASE POINT YOUR $$PATH AT libosmocore/contrib/ladder_to_msc.py' && false)
+	ladder_to_msc.py -i $< -o $@

doc/manuals/chapters/dgsm.adoc

@@ -0,0 +1,491 @@
+== Distributed GSM / Multicast MS Lookup
+
+Distributed GSM (D-GSM) allows independent mobile core network stacks to provide voice, SMS and Roaming services to each
+other, without the need for centralised entities or administration authority, and in a way that is resilient against
+unstable network links between sites.
+
+D-GSM aims at communal networks, where several independent sites, let's call them villages, each have a full mobile core
+network infrastructure. It elegantly provides ad-hoc service for subscribers moving across villages, and allows villages
+to dynamically join or leave the cooperative network without the need for configuration changes at other sites.
+
+A challenge for linking separate sites is to find the current location of a subscriber. Typically, in mobile networks, a
+centralized entity keeps track of where to Page for subscribers. Running several fully independent sites with unreliable
+links between them makes it hard to provide such centralisation.
+
+D-GSM finds subscribers by mslookup, a service provided by OsmoHLR, typically using multicast DNS queries.  This allows
+routing Location Updating requests, calls, and SMS to the right site without administrative delay nor the need for a
+reliable link to a central database.
+
+D-GSM is highly resilient against single sites or links becoming temporarily unavailable. Service between still
+reachable sites simply continues; Service to a disconnected site resumes as soon as it becomes reachable again.
+
+This brings an entirely new paradigm to mobile core network infrastructure: as sites become reachable on the IP network
+and join the common IP multicast group, services between them become available immediately. Basically, the only premise
+is that IP routing and multicast works across sites, and that each site uses unique IPA names in the GSUP config.
+
+This chapter describes how D-GSM and mslookup work, and how to configure sites to use D-GSM, using Osmocom core network
+infrastructure.
+
+=== Finding Subscribers: mslookup Clients
+
+There are two fundamentally distinct subscriber lookups provided by the mslookup service.
+
+==== Find the Current Location of an MSISDN
+
+[[fig_dgsm_connect]]
+.mslookup for connecting subscribers: Alice is visiting village C; a phone call gets routed directly to her current location independently from her resident village infrastructure
+[graphviz]
+----
+digraph G {
+rankdir=LR
+
+subgraph cluster_village_b {
+	label="Village B"
+	ms_bob [label="Bob\n(from village B)",shape=box]
+	pbx_b [label="SIP B"]
+}
+
+subgraph cluster_village_c {
+	label="Village C"
+	ms_alice [label="Alice\n(from village A)",shape=box]
+	msc_c [label="MSC C"]
+	hlr_c [label="HLR C"]
+	sip_c [label="SIP C"]
+}
+
+ms_alice -> msc_c [style=dashed,arrowhead=none]
+msc_c -> hlr_c [label="attached",style=dashed,arrowhead=none]
+ms_bob -> pbx_b [label="call Alice"]
+pbx_b -> hlr_c [label="mslookup by MSISDN",style=dotted,dir=both]
+pbx_b -> sip_c -> msc_c -> ms_alice [label="call"]
+}
+----
+
+For example, if a subscriber is currently visiting another village, establish a phone call / send SMS towards that
+village.
+
+- To deliver a phone call, a SIP agent integrates an mslookup client to request the SIP service of an MSISDN's current
+  location (example: <<dgsm_conf_dialplan>>). It receives an IP address and port to send the SIP Invite to.
+
+- To deliver an SMS, an ESME integrates an mslookup client to request the SMPP service of an MSISDN's current location
+  (example: <<dgsm_conf_esme_smpp>>).
+
+The current location of a subscriber may change at any time, and, when moving across locations, a subscriber may
+suddenly lose reception to the previous location without explicitly detaching. Hence an mslookup request for the current
+location of an MSISDN may get numerous responses. To find the currently valid location, mslookup includes the age of the
+subscriber record, i.e. how long ago the subscriber was last reached. The one response with the youngest age reflects
+the current location.
+
+In order to evaluate several responses, mslookup always waits for a fixed amount of time (1 second), and then evaluates
+the available responses.
+
+Services are not limited to SIP and SMPP, arbitrarily named services can be added to the mslookup configuration.
+
+.Message sequence for locating an MSISDN to deliver a voice call
+["mscgen"]
+----
+msc {
+  hscale="2";
+  moms[label="MS,BSS\nvillage A"],momsc[label="MSC,MGW\nvillage A"],mosipcon[label="osmo-sip-connector\nvillage A"],mopbx[label="PBX\nvillage A"],mthlr[label="OsmoHLR\nvillage B"],mtsipcon[label="osmo-sip-connector\nvillage B"],mtmsc[label="MGW,MSC\nvillage B"],mtms[label="RAN,MS\nvillage B"];
+
+  moms =>> momsc [label="CC Setup"];
+  momsc =>> mosipcon [label="MNCC_SETUP_IND"];
+  mosipcon =>> mopbx [label="SIP INVITE"];
+  mopbx rbox mopbx [label="dialplan: launch mslookup by MSISDN"];
+  --- [label="multicast-DNS query to all connected sites"];
+  ...;
+  mopbx <<= mthlr [label="mDNS response\n(age)"];
+  mopbx rbox mopbx [label="wait ~ 1s for more mDNS responses"];
+  ...;
+  mopbx =>> mtsipcon [label="SIP INVITE (MT)"];
+  mtmsc <<= mtsipcon [label="MNCC_SETUP_REQ"];
+  mtms <<= mtmsc [label="Paging (CC)"];
+  moms rbox mtms [label="voice call commences"];
+
+}
+----
+
+==== Find the Home HLR for an IMSI
+
+[[fig_dgsm_roaming]]
+.mslookup for Roaming: Alice visits village B; she can attach to the local mobile network, which proxies HLR administration to her home village.
+[graphviz]
+----
+digraph G {
+rankdir=LR
+
+subgraph cluster_village_b {
+	label="Village B"
+
+	ms_alice [label="Alice\n(from village A)",shape=box]
+	msc_b [label="MSC B"]
+	hlr_b [label="HLR B"]
+}
+
+subgraph cluster_village_a {
+	label="Village A"
+	hlr_alice [label="Alice's home HLR"]
+}
+
+ms_alice -> msc_b -> hlr_b [label="Location\nUpdating"]
+hlr_b -> hlr_alice [label="mslookup by IMSI",style=dotted,dir=both]
+hlr_b -> hlr_alice [label="GSUP proxy forwarding"]
+}
+----
+
+For example, when attaching to a local network, a local resident gets serviced directly by the local village's HLR,
+while a visitor from another village gets serviced by the remote village's HLR (Roaming).
+
+A home HLR typically stays the same for a given IMSI. If the home site is reachable, there should be exactly one
+response to an mslookup request asking for it. The age of such a home-HLR response is always sent as zero.
+
+If a response's age is zero, mslookup does not wait for further responses and immediately uses the result.
+
+If there were more than one HLR accepting service for an IMSI, the one with the shortest response latency is used.
+
+=== mslookup Configuration
+
+OsmoHLR the main mslookup agent. It provides the responses for both current location services as well as for locating
+the fixed home-HLR. But naturally, depending on the mslookup request's purpose, different OsmoHLR instances will respond
+for a given subscriber.
+
+- When querying the home HLR, it is always the (typically single) home HLR instance that sends the mslookup response. As
+  soon as it finds the queried IMSI in the local HLR database, an OsmoHLR will respond to home-HLR requests.
+  In <<fig_dgsm_roaming>>, Alice's home HLR responds to the Roaming request ("where is the home HLR?").
+
+- When querying the location of an MSISDN, it is always the HLR proxy nearest to the servicing MSC that sends the
+  mslookup response. Even though the home HLR keeps the Location Updating record also for Roaming cases, it will only
+  respond to an mslookup service request if the subscriber has attached at a directly connected MSC. If attached at a
+  remote MSC, that MSC's remote HLR will be the GSUP proxy for the home HLR, and the remote HLR is responsible for
+  responding to service requests.
+  In <<fig_dgsm_roaming>>, HLR B is the nearest proxy and will answer all service requests ("where is this MSISDN?").
+  Alice's home HLR will not answer service requests, because it detects that the servicing MSC is connected via another
+  HLR proxy.
+
+[[dgsm_example_config]]
+==== Example
+
+Here is an osmo-hlr.cfg mslookup configuration example for one site, which is explained in subsequent chapters.
+
+ hlr
+  gsup
+   bind ip 10.9.8.7
+   ipa-name hlr-23
+ mslookup
+  mdns bind
+  server
+   service sip.voice at 10.9.8.7 5060
+   service smpp.sms at 10.9.8.7 2775
+
+OsmoHLR has both an mslookup server and a client.
+
+- The server responds to incoming service and home-HLR requests, when the local HLR is responsible.
+- The client is used as GSUP proxy to a remote home HLR (found by mslookup upon a locally unknown IMSI).
+- The client may also be used for forwarding SMS-over-GSUP.
+
+The mslookup service can be implemented by various methods.
+At the time of writing, the only method implemented is mDNS.
+
+==== mDNS
+
+The stock mslookup method is mDNS, multicast DNS. It consists of standard DNS encoding according to <<ietf-rfc1035>> and
+<<ietf-rfc3596>>, but sent and received on IP multicast. In the response, standard A and AAAA records return the
+service's IP address, while additional TXT records provide the service's port number and the MS attach age.
+
+TIP: To watch D-GSM mDNS conversations in wireshark, select "udp.port == 4266" (the default mslookup mDNS port
+number), right click on the packet to "Decode as...", and select "DNS".
+
+In OsmoHLR, the mDNS server and client are typically both enabled at the same time:
+
+ mslookup
+  mdns bind
+
+Server and client can also be enabled/disabled individually:
+
+ mslookup
+  server
+   mdns bind
+  client
+   mdns bind
+
+These examples use the default mslookup multicast IP address and port. It is possible to configure custom IP address and
+port, but beware that the IP address must be from a multicast range, see <<ietf-rfc5771>>:
+
+ mslookup
+  mdns bind 239.192.23.42 4266
+
+Domain names generated from mslookup queries (e.g. "sip.voice.123.msisdn") should not collide with IANA permitted
+domains. Therefore we add the "mdns.osmocom.org" suffix. It can be overridden as follows:
+
+ mslookup
+  mdns domain-suffix mdns.osmocom.org
+
+==== Server: Site Services
+
+The mslookup server requires a list of service addresses provided at the local site, in order to respond to service
+requests matching locally attached subscribers.
+
+ mslookup
+  server
+   service sip.voice at 10.9.8.7 5060
+   service smpp.sms at 10.9.8.7 2775
+
+In this example:
+
+- "10.9.8.7 5060" are the IP address and port on which the local site's osmo-sip-connector is bound to receive SIP
+  Invite requests.
+- "10.9.8.7 2775" are the local site's OsmoMSC SMPP bind address and port.
+
+Obviously, these IP addresses must be routable back to this site from all other sites. Using link-local or "ANY"
+addresses, like 127.0.0.1 or 0.0.0.0, will not work here. Instead, each service config requires a public IP address that
+all remote requestors are able to reach (not necessarily on the host that osmo-hlr is running on).
+
+If a site has more than one MSC, services can also be configured for each MSC individually, keyed by the IPA unit name
+that each MSC sends on the GSUP link:
+
+ mslookup
+  server
+   msc ipa-name msc-262-42-0
+    service sip.voice at 10.11.12.13 5060
+    service smpp.sms at 10.11.12.13 2775
+   msc ipa-name msc-901-70-0
+    service sip.voice at 10.9.8.7 5060
+    service smpp.sms at 10.9.8.7 2775
+
+Here, "msc-262-42-0" is the IPA name of a local OsmoMSC instance. To configure an OsmoMSC's IPA name on the GSUP link,
+see osmo-msc.cfg, setting `hlr` / `ipa-name`.
+
+For mslookup service responses, only Location Updatings in the Circuit Switched domain are relevant. OsmoHLR does manage
+IMSIs attaching in the Packet Switched domain (via an SGSN) similarly to Circuit Switched (via an MSC), but mslookup
+completely ignores the Packet Switched attach status.
+
+==== Server: Own GSUP Address
+
+When responding to home-HLR requests, OsmoHLR implicitly by default responds with its locally configured GSUP bind
+address (setting `hlr` / `gsup` / `bind ip`). If required, an explicit local GSUP address and port can be configured,
+for example:
+
+ hlr
+  gsup
+   bind ip 0.0.0.0
+   ipa-name hlr-23
+ mslookup
+  server
+   # osmo-hlr's own GSUP address to send in mslookup responses:
+   service gsup.hlr at 10.9.8.7 4222
+
+The gsup.hlr service can only be configured globally (because requests come from arbitrary mDNS clients, before a
+Location Updating has associated the IMSI with the requesting MSC).
+
+==== Client IPA Naming
+
+For reliable GSUP proxy routing to a remote HLR (Roaming), it is important that each GSUP client, i.e. each HLR, MSC and
+SGSN instance, has a unique IPA name.
+
+Example for configuring an OsmoHLR instance's IPA name:
+
+ hlr
+  gsup
+   ipa-name hlr-23
+
+Here, "hlr-23" is the unique identification of this OsmoHLR instance across all potentially connected D-GSM sites.
+
+Furthermore, each MSC and SGSN must have a uniquely distinct IPA name across all sites (here "msc-262-42-0" and
+"msc-901-70-0" are used as example IPA names for local MSCs).
+
+When this OsmoHLR connects to a remote HLR, be it for GSUP proxying or SMS-over-GSUP, it communicates its own IPA name
+(on GSUP link-up) as well as the IPA name of the requesting client MSC/SGSN (as Source Name in each message) to the
+remote OsmoHLR GSUP server. These names are used to route GSUP responses back to the respective requesting peer.
+
+If two MSCs were accidentally configured with identical names, a problem will occur as soon as both MSCs attempt to
+attach to the same OsmoHLR (either directly or via GSUP proxying). The MSC that shows up first will work normally, but
+any duplicate that shows up later will be rejected, since a route for its name already exists.
+
+=== Queries
+
+In URL notation, typical mslookup queries look like:
+
+ gsup.hlr.123456789.imsi
+ sip.voice.123.msisdn
+ smpp.sms.123.msisdn
+
+A query consists of
+
+- a service name ("gsup.hlr"),
+- an id ("123456789"),
+- the id type ("imsi").
+
+The calling client also defines a timeout to wait for responses.
+
+The mslookup ID types are fixed, while service names can be chosen arbitrarily.
+
+.mslookup ID types, no other ID types are understood by mslookup
+[options="header",width="100%",cols="20%,80%"]
+|===
+|ID Type|Description
+|imsi|An IMSI as existing in an OsmoHLR subscriber database
+|msisdn|A phone number as configured in an OsmoHLR subscriber database
+|===
+
+.mslookup service name conventions, arbitrary service names can be added as required
+[options="header",width="100%",cols="20%,20%,60%"]
+|===
+|Service Name|Protocol|Description
+|gsup.hlr | GSUP | Home HLR's GSUP server, to handle Location Updating related procedures
+|sip.voice | SIP | OsmoSIPConnector, to receive a SIP Invite (MT side of a call)
+|smpp.sms | SMPP | Destination OsmoMSC (or other SMPP server) to deliver an SMS to the recipient
+|gsup.sms | GSUP | GSUP peer to deliver an SMS to the recipient using SMS-over-GSUP
+|===
+
+Arbitrarily named services can be added to the mslookup configuration and queried by mslookup clients; as soon as a
+service name is present in osmo-hlr.cfg, it can be queried from any mslookup client.
+
+Service names should consist of a protocol name (like "sip", "gsup", "english") and an intended action/entity (like
+"voice", "hlr", "greeting").
+
+=== Service Client Implementation
+
+In principle, arbitrary services could query target addresses via mslookup, leaving it up to any and all kinds of
+clients to find their respective destination addresses. But of course, mslookup was designed with specific services in
+mind, namely:
+
+- SIP call agents and
+- SMS delivery (an ESME or SMSC)
+
+The following chapters describe examples of setting up a working distributed core network providing SIP voice calls and
+SMS forwarding across sites.
+
+==== mslookup Library
+
+The OsmoHLR provides an mslookup client C library, libosmo-mslookup. Service lookups can be integrated directly
+in client programs using this library. However, its mDNS implementation requires the libosmocore select() loop, which
+can be challenging to integrate in practice. An alternative solution is the osmo-mslookup-client tool.
+
+[[dgsm_osmo_mslookup_client]]
+==== osmo-mslookup-client
+
+The mslookup C library is available, but often, a simpler approach for client implementations is desirable:
+
+- When querying for a service address, the client is typically interested in the single final best result (youngest age
+  / first responding home HLR).
+- Voice call and SMS clients typically would block until an mslookup result is known. For example, the FreeSwitch
+  dialplan integration expects a result synchronously, i.e. without waiting for mslookup responses via a select() loop.
+- Integrating the libosmocore select() loop required for mDNS can break the already existing socket handling in the
+  client program.
+
+The osmo-mslookup-client cmdline tool provides a trivial way to synchronously acquire the single result for an mslookup
+request. The service client can invoke an osmo-mslookup-client process per request and read the result from stdout.
+
+Each invocation obviously spawns a separate process and opens a multicast socket for mDNS. For better scalability,
+osmo-mslookup-client can also be run as a daemon, providing results via a unix domain socket. Using synchronous write()
+and recv() allows blocking until a result is received without interfering with the client program's select() setup.
+
+By itself, osmo-mslookup-client is also helpful as a diagnostic tool:
+
+----
+$ osmo-mslookup-client sip.voice.1001.msisdn
+sip.voice.1001.msisdn	ok	10.9.8.7	5060
+
+$ osmo-mslookup-client gsup.hlr.901700000014701.imsi
+gsup.hlr.901700000014701.imsi	ok	10.9.8.7	4222
+
+$ osmo-mslookup-client gsup.hlr.111111.imsi
+gsup.hlr.111111.imsi	not-found
+
+$ osmo-mslookup-client gsup.hlr.1001.msisdn sip.voice.1001.msisdn smpp.sms.1001.msisdn foo.1001.msisdn
+gsup.hlr.1001.msisdn	ok	10.9.8.7	4222
+foo.1001.msisdn	not-found
+smpp.sms.1001.msisdn	ok	10.9.8.7	2775
+sip.voice.1001.msisdn	ok	10.9.8.7	5060
+
+$ osmo-mslookup-client --csv-headers gsup.hlr.901700000014701.imsi
+QUERY	RESULT	V4_IP	V4_PORT	V6_IP	V6_PORT
+gsup.hlr.901700000014701.imsi	ok	10.9.8.7	4222
+
+$ osmo-mslookup-client -f json gsup.hlr.901700000014701.imsi
+{"query": "gsup.hlr.901700000014701.imsi", "result": "ok", "v4": ["10.9.8.7", "4222"]}
+----
+
+For full help including example client invocations in Python, see the output of:
+
+ osmo-mslookup-client -h
+
+==== SIP Service Client
+
+[[dgsm_conf_dialplan]]
+===== FreeSwitch dialplan.py
+
+The FreeSWITCH PBX software <<freeswitch_pbx>> offers a Python integration to determine a SIP call recipient by a custom
+dialplan implementation. An example dialplan implementation for FreeSWITCH that uses D-GSM mslookup is provided in the
+osmo-hlr source tree under `contrib`, called `freeswitch_dialplan_dgsm.py`.
+
+To integrate it with your FREESWITCH setup, add a new `extension` block to your `dialplan/public.xml`:
+
+----
+    <extension name="outbound">
+      <condition field="destination_number" expression=".*">
+	<action application="set" data="hangup_after_bridge=true"/>
+	<action application="set" data="session_in_hangup_hook=true"/>
+	<action application="set" data="ringback=%(2000, 4000, 440.0, 480.0)"/>
+	<action application="python" data="freeswitch_dialplan_dgsm"/>
+      </condition>
+    </extension>
+----
+
+Make sure that the dir containing `freeswitch_dialplan_dgsm.py` is in your `PYTHONPATH` environment variable, and start
+the server:
+
+----
+$ export PYTHONPATH="$PYTHONPATH:/home/user/code/osmo-hlr/contrib/dgsm"
+$ freeswitch -nf -nonat -nonatmap -nocal -nort -c
+----
+
+==== SMS Service Client
+
+[[dgsm_conf_esme_smpp]]
+===== SMS via SMPP Port
+
+An example ESME using D-GSM mslookup, `esme_dgsm.py`, is provided in the osmo-hlr source tree under `contrib`. It
+attaches to OsmoMSC's SMPP port to send SMS to recipients determined by mslookup.
+
+OsmoMSC should be configured as "smpp-first", so that all SMS routing is determined by mslookup. If configured without
+smpp-first, OsmoMSC may try to deliver an SMS locally, even though the recipient has recently moved to a different site.
+
+An example OsmoMSC configuration to work with esme_dgsm.py:
+
+----
+smpp
+ local-tcp-ip 127.0.0.1 2775
+ system-id test-msc
+ policy closed
+ smpp-first
+ # outgoing to esme_dgsm.py
+ esme OSMPP
+  no alert-notifications
+  password foo
+  default-route
+ # incoming from esme_dgsm.py
+ esme ISMPP
+  no alert-notifications
+  password foo
+----
+
+Launch esme_dgsm.py alongside OsmoMSC:
+
+----
+./esme_dgsm.py --src-host 127.0.0.1
+----
+
+esme_dgsm.py will be notified via SMPP for each SMS to be delivered, and will forward them either to a remote
+recipient, or back to the same OsmoMSC, depending on the mslookup result. If the MSISDN is not reachable (or
+esme_dgsm.py can't handle the message for other reasons), it returns the RSYSERR code back to OsmoMSC.
+
+Note that the esme_dgsm.py is a proof of concept and should not be used in production. It has several limitations, such
+as not supporting multipart SMS messages.
+
+===== SMS-Over-GSUP
+
+The GSUP protocol defines SMS delivery messages. When OsmoMSC is configured to deliver SMS via GSUP, MO SMS are directly
+forwarded to the HLR, which will determine where to forward the SMS-over-GSUP messages using its mslookup client.
+
+FIXME implement this

doc/manuals/chapters/proxy_cache.adoc

@@ -0,0 +1,333 @@
+== Distributed GSM / GSUP Proxy Cache: Remedy Temporary Link Failure to Home HLR
+
+The aim of the Proxy Cache is to still provide service to roaming subscribers even if the GSUP link to the home HLR is
+temporarily down or unresponsive.
+
+If a subscriber from a remote site is currently roaming at this local site, and the link to the subscriber's home HLR
+has succeeded before, the GSUP proxy cache can try to bridge the time of temporary link failure to that home HLR.
+
+Tasks to take over from an unreachable home HLR:
+
+- Cache and send auth tuples on Send Auth Info Request.
+- Acknowledge periodic Location Updating.
+- ...?
+
+=== Design Considerations
+
+==== Authentication
+
+The most critical role of the home HLR is providing the Authentication and Key Agreement (AKA) tuples. If the home HLR
+is not reachable, the lack of fresh authentication challenges would normally cause the subscriber to be rejected. To
+avoid that, a proxying HLR needs to be able to provide AKA tuples on behalf of the home HLR.
+
+In short, the strategy of the D-GSM proxy cache is:
+
+- Try to keep a certain number of unused full UMTS AKA tuples in the proxy cache at all times.
+- When the MSC requests more tuples, dispense some from the cache, and fill it back up later on, as soon as a good link
+  is available.
+- When the tuple cache in the proxy HLR runs dry, 3G RAN becomes unusable. But 2G RAN may fall back to GSM AKA, if the
+  proxy HLR configuration permits it: resend previously used GSM AKA auth tuples to the MSC, omitting UMTS AKA items
+  from the Send Auth Info Result, to force the MSC to send a GSM AKA challenge on 2G.
+
+The remaining part of this section provides detailed reasoning for this strategy.
+
+The aim is to attach a subscriber without immediate access to the authentication key data.
+
+Completely switching off authentication would be an option on GERAN (2G), but this would mean complete lack of
+encryption on the air interface, and is not recommended. On 3G and later, authentication is always mandatory.
+
+The key data is known only to the USIM and the home HLR. The HLR generates distinct authentication tuples, each
+containing a cryptographic challenge (RAND, AUTN) and its expected response (SRES, XRES). The MSC consumes one tuple
+per authentication: it sends the challenge to the subscriber, and compares the response received.
+
+The proxy could generate fresh tuples if the cryptographic key data (Ki,K,OP/OPC) from the home HLR was shared with the
+proxy HLR. Distributed GSM does not do this, because:
+
+- The key data is cryptographically very valuable. If it were leaked, any and all authentication challenges would be
+  fully compromised.
+
+- In D-GSM, each home site shall retain exclusive authority over the user data. It should not be necessary to share the
+  secret keys with any remote site.
+
+So, how about resending already used auth tuples to the MSC when no fresh ones are available? Resending identical
+authentication challenges makes the system vulnerable to relatively trivial replay-attacks, but this may be an
+acceptable fallback in situations of failing links, if it means being able to provide reliable roaming.
+
+But, even if a proxying HLR is willing to compromise cryptographic security to improve service, this can only work with
+GSM AKA:
+
+- In GSM AKA (so-called 2G auth), tuples may be re-used any amount of times without a strict need to generate more
+  authentication challenges. The SIM will merely calculate the (same) SRES response again, and authentication will
+  succeed. It is bad security to do so, but it is a choice the core network is free to make.
+
+- UMTS AKA (Milenage or so-called 3G auth, but also used on 2G GERAN) adds mutual authentication, i.e. the core network
+  must prove that it is authentic. Specifically to thwart replay-attacks that would spoof a core network, UMTS AKA
+  contains an ongoing sequence number (SQN) that is woven into the authentication challenge. An SQN may skip forward by
+  a certain number of counts, but it can never move backwards. If a USIM detects a stale SQN, it will request an
+  authentication re-synchronisation (by passing AUTS in an Authentication Failure message), after which a freshly
+  generated UMTS AKA challenge is strictly required -- not possible with an unresponsive home HLR.
+
+Post-R99 (1999) 2G GERAN networks are capable of UMTS AKA, so, not only 3G, but also the vast majority of 2G networks
+today use UMTS AKA -- and so does Osmocom, typically. Hence it is desirable to fully support UMTS AKA in D-GSM.
+
+[options="header"]
+|===
+| RAN | authentication is... 2+| available AKA types
+| GERAN (2G) | optional | GSM AKA | UMTS AKA
+| UTRAN (3G) | mandatory | - | UMTS AKA
+|===
+
+UMTS AKA will not allow re-sending previously used authentication tuples. But a UMTS capable SIM will fall back to GSM
+AKA if the network sent only a GSM AKA challenge. If the proxy HLR sends only GSM AKA tuples, then the MSC will request
+GSM authentication, and re-sending old tuples is again possible. However, a USIM will only fall back to GSM AKA if the
+phone is attaching on a 2G network. For 3G RAN and later, UMTS AKA is mandatory. So, as soon as a site uses 3G or newer
+RAN technology, there is simply no way to resend previously used authentication tuples.
+
+The only way to have unused UMTS AKA tuples in the proxy HLR is to already have them stored from an earlier time. The
+idea is to request more auth tuples in advance whenever the link is available, and cache them in the proxy. When the MSC
+uses up some tuples from the proxy HLR, the proxy cache can fill up again in its own time, by requesting more tuples
+from the home HLR at a time of good link. Then, the next time the subscriber needs immediate action, it does not matter
+whether the home HLR is directly reachable or not.
+
+In an aside, since OsmoMSC already caches a number of authentication tuples, one option would be to implement this in
+OsmoMSC, and not in the proxy HLR: the MSC could request new tuples long before its tuple cache runs dry. However, the
+OsmoMSC VLR state is volatile, and a power cycle of the system would lose the tuple cache; if the home HLR is
+unreachable at the same time of the power cycle, roaming service would be interrupted. The proxy cache in the HLR is
+persistent, so roaming can continue immediately after a power cycle, even if the home HLR link is down.
+
+==== Location Updating
+
+Any attached subscriber periodically repeats a Location Updating procedure, typically every 15 minutes. If a home HLR is
+unreachable at the time of the periodic Location Updating, a roaming subscriber would assume that it is detached from
+the network, even though the local site it is roaming at is still fully operational.
+
+The aim of D-GSM is to keep subscribers attached even if the remote home HLR is temporarily unreachable. The simplest
+way to achieve that is by directly responding with a Update Location Result to the MSC.
+
+In addition to accepting an Update Location, a proxy HLR should also start an Insert Subscriber Data procedure, as a
+home HLR would do. For a periodic Location Updating, the MSC should already know all of the information that an Insert
+Subscriber Data would convey (i.e. the MSISDN), and there would be no strict need to resend this data. But if a
+subscriber quickly detaches and re-attaches (e.g. the device rebooted), the MSC has discarded the subscriber info from
+the VLR, and hence the proxy HLR should also always perform an Insert Subscriber Data. (On the GSUP wire, a periodic LU
+is indistinguishable from an IMSI-Attach LU.)
+
+Furthermore, the longer the proxy HLR's cache keeps a roaming subscriber's data after an IMSI Detach, the longer it is
+possible for the subscriber to immediately re-attach despite the home HLR being temporarily unreachable.
+
+If a subscriber has carried out a GSUP Update Location with the proxy HLR while the home HLR was unreachable, it is not
+strictly necessary to repeat that Update Location message to the home HLR later. The home HLR does keep a timestamped
+record of an Update Location from a proxy HLR if seen, but that has no visible effect on serving the subscriber:
+
+- If the home HLR still thinks that the subscriber is currently attached at the home site, it will respond to mslookup
+  requests. But the actual site the subscriber is roaming at will have a younger age, and its mslookup responses will
+  win.
+
+- If the home HLR has no record of the subscriber being attached recently, or has a record of being attached at another
+  remote site, it does not respond to mslookup requests for that subscriber. If it records the new proxy LU, it still
+  does not respond to mslookup requests since the subscriber is attached remotely, i.e. there is no difference.
+
+It is thinkable to always handle an Update Location in the proxy HLR, and never even attempt to involve the home HLR in
+case the proxy cache already has data for a given subscriber, but then the proxy HLR would never notice a changed MSISDN
+or authorization status for this subscriber. It is best practice to involve the home HLR whenever possible.
+
+==== IMSI Detach
+
+If a GSUP client reports a detaching IMSI when the home HLR is not reachable, simply respond with an ack.
+
+It is not required to signal the home HLR with a detach once the link is back up. A home HLR anyway flags a remotely
+roaming subscriber as attached-at-a-proxy, and there is literally no difference between telling a home HLR about a
+detach or not.
+
+(TODO: is there even a GSUP message that a VLR should send on IMSI Detach? see OS#4374)
+
+[[proxy_cache_umts_aka_resync]]
+==== UMTS AKA Resync
+
+When the SQN between USIM and AUC (subscriber and home HLR) have diverged, the Send Authentication Info Request from the
+MSC contains an AUTS IE. This means that a resynchronization between USIM and AUC (the home HLR) is necessary. All of
+the UMTS AKA tuples in the proxy cache are now unusable, and the home HLR must respond with fresh tuples after doing a
+resync. This also means that either the home HLR must be reachable immediately, or GSM AKA fallback must be allowed for
+the subscriber to remain in roaming service.
+
+In short:
+
+- A UMTS AKA resync is handled similarly to the attaching of a so far unknown subscriber.
+- With the exception that previous GSM AKA tuples may be available to try a fallback to re-using older tuples.
+
+Needless to say that avoiding the need for UMTS AKA resynchronization is an important aspect of D-GSM's resilience
+against unreliable links.
+
+In UMTS AKA, there is not one single SQN, but there are a number SQN slots, called IND slots or IND buckets. The IND
+bitlen configured on the USIM determines the amount of slots available. The IND bitlen is usually 5, i.e. 2^5^ = 32
+slots. Monotonously rising SQN are only strictly enforced within each slot, so that each site should maintain a
+different IND slot. OsmoHLR determines distinct IND slots based on the IPA unit name. As soon as more than 16 sites
+(with an MSC and SGSN each) are maintained, IND slots may be shared between distinct sites, and administrative care
+should be taken to choose wisely which sites share the same slots: those that least share a common user group.
+
+On 2G RAN, it may be possible to fall back to GSM AKA after a UMTS AKA resync request.
+TODO: test this
+
+Either way, the AUTS that was received from the MSC definitely needs to find its way to the home HLR, and, ideally, the
+immediately returned auth tuples from the home HLR should be used to attach the subscriber.
+
+=== CS and PS
+
+Each subscriber may have multiple HLR subscriptions from distinct CN Domain VLRs at any time: Circuit Switched (MSC) and
+Packet Switched (SGSN) attach separately and perform Update Location Requests that are completely orthogonal, as far as
+the HLR is concerned.
+
+Particularly the UMTS AKA tuples, which use distinct IND slots per VLR, need to be cached separately per CN Domain.
+
+Hence it is not enough to maintain one cache per subscriber. A separate auth tuple cache and Mobility Management state
+has to be kept for each VLR that is requesting roaming service for a given subscriber.
+
+=== Intercepting GSUP Conversations
+
+Taking over GSUP conversations in the proxy HLR is not as trivial as it may sound. Here are potential problems and how
+to fix them.
+
+[[proxy_cache_gsup_mm_messages]]
+==== Which GSUP Conversations to Intercept
+
+For the purpose of providing highly available roaming despite unreliable links to the home HLR, it suffices to intercept
+Mobility Management (MM) related GSUP messages, only:
+
+- Send Auth Info Request / Result
+- Update Location Request / Result
+- Insert Subscriber Data Request / Result
+- PurgeMS Request / Result (?)
+
+An interesting feature would be to also intercept specific USSD requests, like returning the own MSISDN or IMSI more
+reliably, or handling services that only make sense when served by the local site. At the time of writing, this is seen
+as a future extension of D-GSM and not considered for implementation.
+
+==== Determining Whether a Home HLR is Responsive
+
+Normally, all GSUP messages are merely routed via the proxy HLR and are handled by the home HLR. The idea is that the
+proxy HLR jumps in and saves a GSUP conversation when the home HLR is not answering properly.
+
+The simplest method to decide whether a home HLR is currently connected would be to look at the GSUP client state.
+However, a local flag that indicates an established GSUP connection does not necessarily mean a reliable link.
+There are keep-alive messages on the GSUP/IPA link, and a lost connection should reflect in the client state, so that a
+lost GSUP link definitely indicates an unresponsive home HLR. But for various reasons (e.g. packet loss), the link might
+look intact, but still a given GSUP message fails to get a response from the home HLR.
+
+A more resilient method to decide whether a home HLR is responsive is to keep track of every MM related GSUP
+conversation for each subscriber, and to jump in and take over the GSUP conversation as soon as the response is taking
+too long to arrive. However, choosing an inadequate timeout period would either mean responding after the MSC has
+already timed out (too slow), or completely cutting off all responses from a high-latency home HLR (too fast).
+
+Also, if the proxy HLR has already responded to the MSC, but a slow home HLR's response arrives shortly after,
+forwarding this late message to the MSC on top of the earlier response to the same request would confuse the GSUP
+conversation.
+
+So, the proxy HLR just jumping into the GSUP conversation when a specific delay has passed is fairly complex and error
+prone. A better idea is to always intercept MM related GSUP conversations:
+
+[[proxy_cache_gsup_conversations]]
+==== Solution: Distinct GSUP Conversations
+
+A solution that avoids all of the above problems is to *always* take over *all* MM related conversations (see
+<<proxy_cache_gsup_mm_messages>>), as soon as the proxy has sufficient data to service them by itself; at the same time,
+the proxy HLR should also relay the same requests to the home HLR, and acknowledge its responses, after the fact.
+
+If the proxy cache already has a complete record of a subscriber, the proxy HLR can always directly accept an Update
+Location Request, including an Insert Subscriber Data. A prompt response ensures that the MSC does not timeout its GSUP
+request, and reduces waiting time for the subscriber.
+
+To ensure that the proxy HLR's data on the subscriber doesn't become stale and diverge from the home HLR, the proxy
+asynchronously also forwards an Update Location Request to the home HLR. In most normal cases, there will be no
+surprises, and the home HLR will continue with an Insert Subscriber Data Request containing already known data, and an
+Update Location Result accepting the LU.
+
+If the home HLR does not respond, the proxy HLR ignores that fact -- the home HLR is not reachable, and the aim is to
+continue to service the subscriber for the time being.
+
+But, should the home HLR's Insert Subscriber Data Request send different data than the proxy cache sees on record, the
+proxy HLR can trigger another Insert Subscriber Data Request to the MSC, to correct the stale data sent before.
+
+Similarly, if the home HLR rejects the Update Location Request completely, the proxy HLR can tell the MSC to detach the
+subscriber with a Cancel Location Request message, as soon as it notices the rejection.
+
+Note that a UMTS AKA resynchronization request invalidates the entire auth tuple cache and needs to either be sent to
+the home HLR immediately, if available, or the AUTS from the USIM must later reach the home HLR to obtain fresh UMTS AKA
+tuples for the cache. See <<proxy_cache_umts_aka_resync>>.
+
+=== Message Sequences
+
+==== Normal Roaming Attach
+
+On first attaching via a proxy HLR, when there is no proxy state for the subscriber yet, the home HLR must be reachable.
+
+The normal procedure takes place without modification, except that he proxy HLR keeps a copy of the first auth tuples it
+forwards from the home HLR back to the MSC (marked as used) (1). This is to have auth tuples available for resending
+already used tuples in a fallback to GSM AKA, in case this is enabled in the proxy HLR config.
+
+After the Location Updating has completed successfully, the proxy HLR fills up its auth tuple cache by additional Send
+Auth Info Requests (2). As soon as unused auth tuples become available, the proxy HLR can discard already used tuples
+from (1).
+
+.Normal attaching of a subscriber that is roaming here
+["mscgen"]
+----
+include::proxy_cache_attach.msc[]
+----
+
+==== MSC Requests More Auth Tuples
+
+As soon as the MSC has run out of fresh auth tuples, it will ask the HLR proxy for more. Without proxy caching, this
+request would be directly forwarded to the home HLR. Instead, the proxy HLR finds unused auth tuples in the cache and
+directly sends those (3). Even if there is a reliable link, the home HLR is not contacted at this point.
+
+Directly after completing the Send Auth Info Result, the proxy HLR finds that less tuples than requested by the D-GSM
+configuration are cached, and asks the home HLR for more tuples, to fill up the cache (4). If there currently is no
+reliable link, this will fail, and the proxy HLR will retry periodically (5) / upon GSUP reconnect.
+
+.When the MSC has used up all of its auth tuples, but the proxy HLR still has unused auth tuples in the cache
+["mscgen"]
+----
+include::proxy_cache_more_tuples.msc[]
+----
+
+==== Running Out of Auth Tuples
+
+When all fresh tuples from the proxy HLR have been used up, and the home HLR remains unreachable, the proxy HLR normally
+fails and rejects the subscriber (default configuration).
+
+If explicitly enabled in the configuration, the proxy HLR will attempt to fall back to GSM AKA and resend already spent
+tuples, deliberately omitting UMTS AKA parts (6).
+
+Note that an attempt to refill the tuple cache in the proxy HLR always happens asynchronously. If there are no tuples,
+that means the link to the home HLR is currently broken, and there is no point in trying to contact it now. Tuples will
+be obtained as soon as the link is established again.
+
+.When the MSC has used up all of its auth tuples and the proxy HLR tuple cache is dry
+["mscgen"]
+----
+include::proxy_cache_tuple_cache_dry.msc[]
+----
+
+==== Periodic Location Updating
+
+Each subscriber performs periodic Location Updating to ensure that it is not implicitly detached from the network. When
+the proxy HLR already has a proxy cache for this subscriber, all information to complete the periodic Location Updating
+is already known in the proxy HLR. If the link to the home HLR is unresponsive, the proxy HLR mimicks the Insert
+Subscriber Data Request that the home HLR would normally send, using the cached MSISDN, and then sends the Update
+Location Result. The subscriber remains attached without a responsive link to the home HLR being required.
+
+.Periodic Location Updating when the MSC still has unused auth tuples
+["mscgen"]
+----
+include::proxy_cache_periodic_lu.msc[]
+----
+
+==== UMTS AKA Resync
+
+The AUTS from a UMTS AKA resync needs to reach the home HLR sooner or later, and a resync renders all UMTS AKA tuples in
+the cache stale.
+
+.Cached tuples become unusable from a UMTS AKA resynchronisation request from the USIM.
+["mscgen"]
+----
+include::proxy_cache_umts_aka_resync.msc[]
+----

doc/manuals/chapters/proxy_cache_attach.ladder

@@ -0,0 +1,39 @@
+{hscale=2}
+ms = MS,BSS
+msc = MSC
+hlr = HLR proxy
+home = Home HLR
+
+ms -> msc	Location Updating Request (IMSI Attach)
+msc -> hlr	Send Auth Info Request
+hlr <> hlr	No proxy cache data available for this subscriber
+hlr () home	mslookup finds the home HLR
+hlr -> home	Send Auth Info Request
+hlr <- home	Send Auth Info Result
+		with 5 auth tuples
+hlr () .	(1) Keep a copy of the auth tuples
+msc <- hlr	Send Auth Info Result
+msc () .	MSC stores 5 auth tuples,
+		uses the first one now,
+		and keeps the rest for later requests
+ms () msc	Authentication
+msc -> hlr	Update Location Request
+hlr -> home	Update Location Request
+hlr <- home	Insert Subscriber Data Request
+		(with subscriber's MSISDN)
+hlr () .	proxy HLR caches the MSISDN
+msc <- hlr	Insert Subscriber Data Request
+msc -> hlr	Insert Subscriber Data Result
+hlr -> home	Insert Subscriber Data Result
+hlr <- home	Update Location Result
+msc <- hlr	Update Location Result
+ms <- msc	Location Updating Accept
+hlr <> .	After successful Update Location, check the cache
+hlr () .	(2) Ask for more auth tuples to cache
+		(amount of tuples configurable)
+hlr -> home	Send Auth Info Request
+hlr <- home	Send Auth Info Result
+hlr () .	store 5 more tuples
+hlr -> home	Send Auth Info Request
+hlr <- home	Send Auth Info Result
+hlr () .	store yet 5 more tuples

doc/manuals/chapters/proxy_cache_attach.msc

@@ -0,0 +1,33 @@
+msc {
+  hscale="2";
+  ms[label="MS,BSS"],__msc[label="MSC"],hlr[label="HLR proxy"],home[label="Home HLR"];
+
+  ms => __msc [label="Location Updating Request (IMSI Attach)"];
+  __msc => hlr [label="Send Auth Info Request"];
+  hlr abox hlr [label="No proxy cache data available for this subscriber"];
+  hlr rbox home [label="mslookup finds the home HLR"];
+  hlr => home [label="Send Auth Info Request"];
+  hlr <= home [label="Send Auth Info Result\nwith 5 auth tuples"];
+  hlr rbox hlr [label="(1) Keep a copy of the auth tuples"];
+  __msc <= hlr [label="Send Auth Info Result"];
+  __msc rbox __msc [label="MSC stores 5 auth tuples,\nuses the first one now,\nand keeps the rest for later requests"];
+  ms rbox __msc [label="Authentication"];
+  __msc => hlr [label="Update Location Request"];
+  hlr => home [label="Update Location Request"];
+  hlr <= home [label="Insert Subscriber Data Request\n(with subscriber's MSISDN)"];
+  hlr rbox hlr [label="proxy HLR caches the MSISDN"];
+  __msc <= hlr [label="Insert Subscriber Data Request"];
+  __msc => hlr [label="Insert Subscriber Data Result"];
+  hlr => home [label="Insert Subscriber Data Result"];
+  hlr <= home [label="Update Location Result"];
+  __msc <= hlr [label="Update Location Result"];
+  ms <= __msc [label="Location Updating Accept"];
+  hlr abox hlr [label="After successful Update Location, check the cache"];
+  hlr rbox hlr [label="(2) Ask for more auth tuples to cache\n(amount of tuples configurable)"];
+  hlr => home [label="Send Auth Info Request"];
+  hlr <= home [label="Send Auth Info Result"];
+  hlr rbox hlr [label="store 5 more tuples"];
+  hlr => home [label="Send Auth Info Request"];
+  hlr <= home [label="Send Auth Info Result"];
+  hlr rbox hlr [label="store yet 5 more tuples"];
+}

doc/manuals/chapters/proxy_cache_more_tuples.ladder

@@ -0,0 +1,31 @@
+{hscale=2}
+ms = MS,BSS
+msc = MSC
+hlr = HLR proxy
+home = Home HLR
+
+ms -> msc	CM Service Request / Paging Response
+msc -> hlr	Send Auth Info Request
+hlr () .	Use already set up proxy path
+hlr <> .	there still are unsent auth tuples
+		in the cache
+hlr () .	(3) Send cached, fresh tuples
+msc <- hlr	Send Auth Info Result
+		containing auth tuples
+		from the proxy cache
+ms () msc	Authentication
+ms () msc	Continue the CM Service / Paging action
+hlr <> .	Note that there are no/few unused tuples in the cache, fill up again
+hlr () .	(4) Ask for more auth tuples to cache
+hlr -> home	Send Auth Info Request
+---		If the home HLR link is not working
+hlr <> .	no link
+		or
+		response timeout
+hlr () .	(5) Set up a timer to retry SAI
+		(a few minutes?)
+hlr <> .	Timer triggers
+hlr -> home	Send Auth Info Request
+---		If the home HLR link is functional
+hlr <- home	Send Auth Info Result
+hlr () .	store 5 more tuples

doc/manuals/chapters/proxy_cache_more_tuples.msc

@@ -0,0 +1,24 @@
+msc {
+  hscale="2";
+  ms[label="MS,BSS"],__msc[label="MSC"],hlr[label="HLR proxy"],home[label="Home HLR"];
+
+  ms => __msc [label="CM Service Request / Paging Response"];
+  __msc => hlr [label="Send Auth Info Request"];
+  hlr rbox hlr [label="Use already set up proxy path"];
+  hlr abox hlr [label="there still are unsent auth tuples\nin the cache"];
+  hlr rbox hlr [label="(3) Send cached, fresh tuples"];
+  __msc <= hlr [label="Send Auth Info Result\ncontaining auth tuples\nfrom the proxy cache"];
+  ms rbox __msc [label="Authentication"];
+  ms rbox __msc [label="Continue the CM Service / Paging action"];
+  hlr abox hlr [label="Note that there are no/few unused tuples in the cache, fill up again"];
+  hlr rbox hlr [label="(4) Ask for more auth tuples to cache"];
+  hlr => home [label="Send Auth Info Request"];
+  --- [label="If the home HLR link is not working"];
+  hlr abox hlr [label="no link\nor\nresponse timeout"];
+  hlr rbox hlr [label="(5) Set up a timer to retry SAI\n(a few minutes?)"];
+  hlr abox hlr [label="Timer triggers"];
+  hlr => home [label="Send Auth Info Request"];
+  --- [label="If the home HLR link is functional"];
+  hlr <= home [label="Send Auth Info Result"];
+  hlr rbox hlr [label="store 5 more tuples"];
+}

doc/manuals/chapters/proxy_cache_periodic_lu.ladder

@@ -0,0 +1,47 @@
+{hscale=2}
+ms = MS,BSS
+msc = MSC
+hlr = HLR proxy
+home = Home HLR
+
+ms -> msc	Location Updating Request (Periodic)
+ms () msc	Authentication,
+		using the next of 5 auth tuples the MSC has stored
+msc -> hlr	Update Location Request
+hlr () .	Use already set up proxy path
+hlr <> .	(8) proxy cache already has all information to answer
+msc <- hlr	Insert Subscriber Data Request
+msc -> hlr	Insert Subscriber Data Result
+msc <- hlr	Update Location Result
+ms <- msc	Location Updating Accept
+hlr () .	(9) Verify Update Location with home HLR
+|||
+---		if the home HLR has no changes and accepts
+hlr -> home	Update Location Request
+hlr <- home	Insert Subscriber Data Request
+hlr -> home	Insert Subscriber Data Result
+hlr <> .	Notice identical MSISDN
+hlr <- home	Update Location Result
+|||
+---		if the home HLR is unreachable
+hlr -> home	Update Location Request
+hlr <> .	no link
+		or
+		response timeout
+hlr () .	Don't care, carry on
+|||
+---		if the home HLR has a modified MSISDN, and accepts
+hlr -> home	Update Location Request
+hlr <- home	Insert Subscriber Data Request
+hlr -> home	Insert Subscriber Data Result
+hlr <> .	Notice changed MSISDN
+msc <- hlr	Insert Subscriber Data Request
+msc -> hlr	Insert Subscriber Data Result
+hlr <- home	Update Location Result
+|||
+---		if the home HLR rejects
+hlr -> home	Update Location Request
+hlr <- home	Update Location Error
+msc <- hlr	Cancel Location Request
+msc -> hlr	Cancel Location Result
+hlr () .	Clear subscriber cache

doc/manuals/chapters/proxy_cache_periodic_lu.msc

@@ -0,0 +1,43 @@
+msc {
+  hscale="2";
+  ms[label="MS,BSS"],__msc[label="MSC"],hlr[label="HLR proxy"],home[label="Home HLR"];
+
+  ms => __msc [label="Location Updating Request (Periodic)"];
+  ms rbox __msc [label="Authentication,\nusing the next of 5 auth tuples the MSC has stored"];
+  __msc => hlr [label="Update Location Request"];
+  hlr rbox hlr [label="Use already set up proxy path"];
+  hlr abox hlr [label="(8) proxy cache already has all information to answer"];
+  __msc <= hlr [label="Insert Subscriber Data Request"];
+  __msc => hlr [label="Insert Subscriber Data Result"];
+  __msc <= hlr [label="Update Location Result"];
+  ms <= __msc [label="Location Updating Accept"];
+  hlr rbox hlr [label="(9) Verify Update Location with home HLR"];
+  |||;
+  --- [label="if the home HLR has no changes and accepts"];
+  hlr => home [label="Update Location Request"];
+  hlr <= home [label="Insert Subscriber Data Request"];
+  hlr => home [label="Insert Subscriber Data Result"];
+  hlr abox hlr [label="Notice identical MSISDN"];
+  hlr <= home [label="Update Location Result"];
+  |||;
+  --- [label="if the home HLR is unreachable"];
+  hlr => home [label="Update Location Request"];
+  hlr abox hlr [label="no link\nor\nresponse timeout"];
+  hlr rbox hlr [label="Don't care, carry on"];
+  |||;
+  --- [label="if the home HLR has a modified MSISDN, and accepts"];
+  hlr => home [label="Update Location Request"];
+  hlr <= home [label="Insert Subscriber Data Request"];
+  hlr => home [label="Insert Subscriber Data Result"];
+  hlr abox hlr [label="Notice changed MSISDN"];
+  __msc <= hlr [label="Insert Subscriber Data Request"];
+  __msc => hlr [label="Insert Subscriber Data Result"];
+  hlr <= home [label="Update Location Result"];
+  |||;
+  --- [label="if the home HLR rejects"];
+  hlr => home [label="Update Location Request"];
+  hlr <= home [label="Update Location Error"];
+  __msc <= hlr [label="Cancel Location Request"];
+  __msc => hlr [label="Cancel Location Result"];
+  hlr rbox hlr [label="Clear subscriber cache"];
+}

doc/manuals/chapters/proxy_cache_tuple_cache_dry.ladder

@@ -0,0 +1,21 @@
+{hscale=2}
+ms = MS,BSS
+msc = MSC
+hlr = HLR proxy
+home = Home HLR
+
+ms -> msc	CM Service Request / Paging Response
+msc -> hlr	Send Auth Info Request
+hlr () .	Use already set up proxy path
+hlr <> .	All cached auth tuples have been sent to the MSC before
+---		If no GSM AKA fallback is allowed
+msc <- hlr	Send Auth Info Error
+ms () msc	Detach
+---		If GSM AKA fallback is allowed
+hlr () .	(6) Resend only GSM AKA tuples, already sent earlier
+msc <- hlr	Send Auth Info Result
+		containing GSM AKA auth tuples
+		from the proxy cache
+ms () msc	2G: Authentication
+		3G: Detach
+ms () msc	Continue the CM Service / Paging action

doc/manuals/chapters/proxy_cache_tuple_cache_dry.msc

@@ -0,0 +1,17 @@
+msc {
+  hscale="2";
+  ms[label="MS,BSS"],__msc[label="MSC"],hlr[label="HLR proxy"],home[label="Home HLR"];
+
+  ms => __msc [label="CM Service Request / Paging Response"];
+  __msc => hlr [label="Send Auth Info Request"];
+  hlr rbox hlr [label="Use already set up proxy path"];
+  hlr abox hlr [label="All cached auth tuples have been sent to the MSC before"];
+  --- [label="If no GSM AKA fallback is allowed"];
+  __msc <= hlr [label="Send Auth Info Error"];
+  ms rbox __msc [label="Detach"];
+  --- [label="If GSM AKA fallback is allowed"];
+  hlr rbox hlr [label="(6) Resend only GSM AKA tuples, already sent earlier"];
+  __msc <= hlr [label="Send Auth Info Result\ncontaining GSM AKA auth tuples\nfrom the proxy cache"];
+  ms rbox __msc [label="2G: Authentication\n3G: Detach"];
+  ms rbox __msc [label="Continue the CM Service / Paging action"];
+}

doc/manuals/chapters/proxy_cache_umts_aka_resync.ladder

@@ -0,0 +1,55 @@
+{hscale=2}
+ms = MS,BSS
+msc = MSC
+hlr = HLR proxy
+home = Home HLR
+
+ms -> msc	CM Service Request / Paging Response
+msc -> hlr	Send Auth Info Request
+hlr <> .	there still are unsent auth tuples
+		in the cache
+hlr () .	Send cached, fresh tuples
+msc <- hlr	Send Auth Info Result
+		containing auth tuples
+		from the proxy cache
+ms <- msc	Authentication Request
+ms -> msc	USIM requests UMTS AKA resync
+		Auth Failure with AUTS
+msc -> hlr	Send Auth Info Request
+		containing AUTS IE
+hlr () .	Mark all UMTS AKA tuples as stale
+---		If the home HLR responds in time
+hlr -> home	Send Auth Info Request
+hlr <- home	Send Auth Info Result
+		with 5 auth tuples
+hlr () .	clear tuple cache, store new tuples
+msc <- hlr	Send Auth Info Result
+ms () msc	Authentication
+hlr () .	fill up the tuple cache as necessary
+hlr -> home	Send Auth Info Request
+hlr <- home	Send Auth Info Result
+...
+---		If the home HLR is unreachable
+hlr -> home	Send Auth Info Request
+hlr <> .	no link
+		or
+		response timeout
+hlr () .	Store the AUTS received earlier,
+		and set up a timer to retry SAI
+		(a few minutes?)
+---		If no GSM AKA fallback is allowed
+msc <- hlr	Send Auth Info Error
+ms () msc	Detach
+---		If GSM AKA fallback is allowed
+hlr () .	Resend only GSM AKA tuples, already sent earlier
+msc <- hlr	Send Auth Info Result
+		containing GSM AKA auth tuples
+		from the proxy cache
+ms () msc	2G: Authentication
+		3G: Detach
+---
+hlr <> .	AUTS timer triggers
+hlr -> home	Send Auth Info Request
+hlr <- home	Send Auth Info Result
+hlr () .	clear tuple cache, store new tuples
+hlr () .	continue to fill up the cache as necessary

doc/manuals/chapters/proxy_cache_umts_aka_resync.msc

@@ -0,0 +1,41 @@
+msc {
+  hscale="2";
+  ms[label="MS,BSS"],__msc[label="MSC"],hlr[label="HLR proxy"],home[label="Home HLR"];
+
+  ms => __msc [label="CM Service Request / Paging Response"];
+  __msc => hlr [label="Send Auth Info Request"];
+  hlr abox hlr [label="there still are unsent auth tuples\nin the cache"];
+  hlr rbox hlr [label="Send cached, fresh tuples"];
+  __msc <= hlr [label="Send Auth Info Result\ncontaining auth tuples\nfrom the proxy cache"];
+  ms <= __msc [label="Authentication Request"];
+  ms => __msc [label="USIM requests UMTS AKA resync\nAuth Failure with AUTS"];
+  __msc => hlr [label="Send Auth Info Request\ncontaining AUTS IE"];
+  hlr rbox hlr [label="Mark all UMTS AKA tuples as stale"];
+  --- [label="If the home HLR responds in time"];
+  hlr => home [label="Send Auth Info Request"];
+  hlr <= home [label="Send Auth Info Result\nwith 5 auth tuples"];
+  hlr rbox hlr [label="clear tuple cache, store new tuples"];
+  __msc <= hlr [label="Send Auth Info Result"];
+  ms rbox __msc [label="Authentication"];
+  hlr rbox hlr [label="fill up the tuple cache as necessary"];
+  hlr => home [label="Send Auth Info Request"];
+  hlr <= home [label="Send Auth Info Result"];
+  ...;
+  --- [label="If the home HLR is unreachable"];
+  hlr => home [label="Send Auth Info Request"];
+  hlr abox hlr [label="no link\nor\nresponse timeout"];
+  hlr rbox hlr [label="Store the AUTS received earlier,\nand set up a timer to retry SAI\n(a few minutes?)"];
+  --- [label="If no GSM AKA fallback is allowed"];
+  __msc <= hlr [label="Send Auth Info Error"];
+  ms rbox __msc [label="Detach"];
+  --- [label="If GSM AKA fallback is allowed"];
+  hlr rbox hlr [label="Resend only GSM AKA tuples, already sent earlier"];
+  __msc <= hlr [label="Send Auth Info Result\ncontaining GSM AKA auth tuples\nfrom the proxy cache"];
+  ms rbox __msc [label="2G: Authentication\n3G: Detach"];
+  ---;
+  hlr abox hlr [label="AUTS timer triggers"];
+  hlr => home [label="Send Auth Info Request"];
+  hlr <= home [label="Send Auth Info Result"];
+  hlr rbox hlr [label="clear tuple cache, store new tuples"];
+  hlr rbox hlr [label="continue to fill up the cache as necessary"];
+}

doc/manuals/osmohlr-usermanual.adoc

@@ -24,6 +24,10 @@ include::{srcdir}/chapters/control.adoc[]
 
 include::./common/chapters/control_if.adoc[]
 
+include::{srcdir}/chapters/dgsm.adoc[]
+
+include::{srcdir}/chapters/proxy_cache.adoc[]
+
 include::./common/chapters/gsup.adoc[]
 
 include::./common/chapters/port_numbers.adoc[]

doc/sequence_charts/Makefile.am

@@ -0,0 +1,39 @@
+all:
+	echo "built only on manual invocation, needs mscgen and dot (graphviz) programs: invoke 'make charts'"
+
+charts: msc dot
+
+EXTRA_DIST = \
+	proxy_cache.dot \
+	proxy_cache__mm_fsm.dot \
+	proxy_cache__to_home_hlr_fsm.dot \
+	$(NULL)
+
+CLEANFILES = \
+	proxy_cache.png \
+	proxy_cache__mm_fsm.png \
+	proxy_cache__to_home_hlr_fsm.png \
+	$(NULL)
+
+msc: \
+	$(NULL)
+
+dot: \
+	$(builddir)/proxy_cache.png \
+	$(builddir)/proxy_cache__mm_fsm.png \
+	$(builddir)/proxy_cache__to_home_hlr_fsm.png \
+	$(NULL)
+
+$(builddir)/%.png: %.msc
+	mscgen -T png -o $@ $<
+
+$(builddir)/%.msc: $(srcdir)/%.ladder
+	@which ladder_to_msc.py || (echo 'PLEASE POINT YOUR $$PATH AT libosmocore/contrib/ladder_to_msc.py' && false)
+	ladder_to_msc.py -i $< -o $@
+
+$(builddir)/%.png: $(srcdir)/%.dot
+	dot -Tpng $< > $@
+
+.PHONY: poll
+poll:
+	while true; do $(MAKE) msc dot; sleep 1; done

doc/sequence_charts/proxy_cache.dot

@@ -0,0 +1,19 @@
+digraph G {
+rankdir=LR
+labelloc=t;
+
+	msc [label="MS/BSS/MSC"]
+	subgraph cluster_proxy {
+		label="HLR Proxy"
+		proxy_mm [label="Proxy Mobility Management FSM",shape=box3d]
+		proxy_home [label="Proxy to Home HLR FSM",shape=box3d]
+		proxy [label="GSUP Proxy"]
+		proxy_mm -> proxy_home [constraint=false,dir=both,label="(FSM events)"]
+	}
+	hlr [label="Home HLR"]
+
+	msc -> proxy_mm [dir=both,label="MM related GSUP\n (immediate response\n if possible)"]
+	proxy_home -> hlr [dir=both,label="MM related GSUP\n (delayed)"]
+
+	msc -> proxy -> hlr [dir=both,label="non-MM GSUP",style=dashed]
+}

doc/sequence_charts/proxy_cache__mm_fsm.dot

@@ -0,0 +1,78 @@
+digraph G {
+rankdir=TB
+labelloc=t; label="HLR Proxy MM FSM"
+
+	top,top2,top3[shape=invtriangle,label="(1)"]
+
+	top -> READY
+
+	new [label="proxy_cache_subscr_new()\n/ proxy_cache_subscr_from_db()",shape=box]
+	READY [style=bold]
+	HIBERNATE [shape=note,label="Hibernate\n (keep in DB)"]
+	CLEAR [shape=box,label="Clear DB entry\n (discard completely)"]
+	WAIT_AUTH_TUPLES [style=bold]
+	WAIT_SUBSCR_DATA [style=bold]
+	WAIT_GSUP_ISD_RESULT [style=bold]
+
+	home_fsm [label="Proxy to Home HLR FSM",shape=box3d]
+	{rank=same;READY,home_fsm}
+
+
+	new -> {READY,home_fsm}
+
+	READY -> {event_lu_req,event_auth_info_req} [arrowhead=none]
+
+	event_auth_info_req [shape=rarrow,label="Rx GSUP\nSend Auth Info Request\nfrom MSC"]
+	event_auth_info_req -> junction_send_auth_info_req
+	junction_send_auth_info_req [shape=diamond,label="Unused\nauth tuples\navailable?"]
+	junction_send_auth_info_req -> action_send_auth_info [label="yes"]
+	junction_send_auth_info_req -> emit_need_tuples [label="no"]
+	emit_need_tuples [shape=lpromoter,label="emit\n HOME_EV_CHECK_TUPLES\n to Home FSM"]
+	emit_need_tuples->WAIT_AUTH_TUPLES
+	WAIT_AUTH_TUPLES -> rx_ev_rx_auth_tuples [arrowhead=none]
+	rx_ev_rx_auth_tuples [shape=rpromoter,label="receive\n MM_EV_RX_AUTH_TUPLES"]
+	rx_ev_rx_auth_tuples -> action_send_auth_info
+	action_send_auth_info [shape=larrow,label="Tx GSUP\nSend Auth Info Result\nwith fresh auth tuples\n to MSC"]
+	action_send_auth_info -> emit_check_tuples
+	emit_check_tuples [shape=lpromoter,label="emit\n HOME_EV_CHECK_TUPLES\n to Home FSM"]
+	emit_check_tuples -> top2
+	WAIT_AUTH_TUPLES -> junction_check_auth_fallback [label="Timeout",style=dashed]
+	junction_check_auth_fallback -> action_do_auth_fallback [label="yes",style=dashed]
+	action_do_auth_fallback [shape=larrow,label="Tx GSUP\nSend Auth Info Result\nwith recycled auth tuple\n(GSM AKA only)"]
+	junction_check_auth_fallback [shape=diamond,label="Re-usable\nauth tuples\navailable?"]
+	junction_check_auth_fallback -> action_fail_auth [label="no",style=dashed]
+	action_fail_auth [shape=larrow,label="Tx GSUP\nSend Auth Info Error\npending re-connection to\nthe home HLR"]
+	{action_do_auth_fallback,action_fail_auth} -> top2 [style=dashed]
+
+	event_lu_req [shape=rarrow,label="Rx GSUP\nUpdate Location Request\nfrom MSC"]
+	event_lu_req -> emit_lu_req
+	emit_lu_req [shape=lpromoter,label="emit\n HOME_EV_CONFIRM_LU"];
+	emit_lu_req -> junction_check_subscriber_data
+	junction_check_subscriber_data [shape=diamond,label="Subscriber\nData\nknown?"]
+	junction_check_subscriber_data -> WAIT_SUBSCR_DATA [label=no]
+	WAIT_SUBSCR_DATA -> rx_ev_subscr_data [arrowhead=none]
+	rx_ev_subscr_data [shape=rpromoter,label="receive\n MM_EV_RX_SUBSCR_DATA"];
+	rx_ev_subscr_data -> action_subscr_data_req
+	junction_check_subscriber_data -> action_subscr_data_req [label="yes"]
+	action_subscr_data_req [shape=larrow,label="Tx GSUP\n Insert Subscriber Data\n Request to MSC"]
+	action_subscr_data_req -> WAIT_GSUP_ISD_RESULT
+	WAIT_GSUP_ISD_RESULT -> tx_gsup_isd_res [arrowhead=none]
+	tx_gsup_isd_res [shape=rarrow,label="Rx GSUP\n Insert Subscriber Data Result\nfrom MSC"]
+	tx_gsup_isd_res -> top3
+
+	{WAIT_GSUP_ISD_RESULT,WAIT_SUBSCR_DATA} -> action_lu_reject [label="Timeout",style=dashed]
+	action_lu_reject [shape=larrow,label="Tx GSUP\nUpdate Location Error\nto MSC\npending reconnect of home HLR"]
+	action_lu_reject -> top3 [style=dashed]
+
+	READY -> HIBERNATE [label="Timeout"]
+	READY -> rx_ev_subscr_invalid [arrowhead=none]
+	rx_ev_subscr_invalid[shape=rpromoter,label="receive\n MM_EV_SUBSCR_INVALID"]
+	rx_ev_subscr_invalid -> tx_purge_req
+	tx_purge_req [shape=larrow,label="Tx GSUP\nPurge MS Request"]
+	tx_purge_req -> note_purge [style=dotted]
+	note_purge [shape=note,label="Don't care about\nPurge MS Result"]
+	tx_purge_req -> CLEAR
+	{CLEAR,HIBERNATE} -> TERM
+	TERM[shape=octagon][style=bold]
+
+}

doc/sequence_charts/proxy_cache__to_home_hlr_fsm.dot

@@ -0,0 +1,97 @@
+digraph G {
+rankdir=TB
+labelloc=t; label="HLR Proxy to Home HLR FSM"
+
+	top,to_top1,to_top2,to_top3,to_top4,to_top5[shape=invtriangle,label="(A)"]
+	top->junction_resolve_home_hlr
+
+	at_clear,to_clear1,to_clear2 [shape=invtriangle,label="(X)"]
+
+	mm_fsm [shape=box3d,label="Proxy MM FSM"]
+	mm_fsm -> junction_resolve_home_hlr [style=invisible,arrowhead=none]
+
+	WAIT_HOME_HLR_RESOLVED [style=bold]
+	WAIT_UPDATE_LOCATION_RESULT [style=bold]
+	WAIT_SEND_AUTH_INFO_RESULT [style=bold]
+	IDLE [style=bold]
+	CLEAR [style=bold]
+
+	new [label="proxy_cache_subscr_new()\n/ proxy_cache_subscr_from_db()",shape=box]
+	{
+		rank=same;
+		junction_resolve_home_hlr [shape=diamond,label="Home HLR\n known?"]
+		junction_confirm_home_hlr [shape=diamond,label="mslookup\n for home HLR\n very old?"]
+		junction_update_location [shape=diamond,label="Did MM FSM emit another\n HOME_EV_CONFIRM_LU?"]
+		junction_auth_info [shape=diamond,label="Auth tuple\ncache full of\nfresh tuples?"]
+	}
+
+	new -> {junction_resolve_home_hlr, mm_fsm}
+
+	junction_resolve_home_hlr -> junction_confirm_home_hlr [label="known"]
+	junction_resolve_home_hlr -> action_mslookup [label="wat"]
+	action_mslookup [shape=larrow,label="start mslookup"]
+	action_mslookup -> WAIT_HOME_HLR_RESOLVED
+	WAIT_HOME_HLR_RESOLVED -> rx_mslookup_res [arrowhead=none]
+	rx_mslookup_res [shape=rarrow,label="home HLR\n resolved"]
+	rx_mslookup_res -> to_top1
+	WAIT_HOME_HLR_RESOLVED -> CLEAR [style=dashed,label=Timeout]
+
+	junction_update_location -> action_lu_req [label="need data\n/\nneed to confirm LU"]
+	action_lu_req [shape=larrow,label="Tx GSUP Update Location Req\nto home HLR"]
+	action_lu_req -> WAIT_UPDATE_LOCATION_RESULT
+	WAIT_UPDATE_LOCATION_RESULT->rx_isd [arrowhead=none]
+	rx_isd [shape=rarrow,label="Rx GSUP\n Insert Subscriber\n Data Request\nfrom home HLR"]
+	rx_isd -> emit_rx_subscr_data
+	emit_rx_subscr_data [shape=lpromoter,label="emit\n MM_EV_RX_SUBSCR_DATA"]
+	emit_rx_subscr_data->action_tx_isd_res
+	action_tx_isd_res -> WAIT_UPDATE_LOCATION_RESULT
+	action_tx_isd_res [shape=larrow,label="Tx GSUP Insert Subscriber Data Result\nto home HLR"]
+	WAIT_UPDATE_LOCATION_RESULT -> rx_lu_res [arrowhead=none]
+	rx_lu_res [shape=rarrow,label="Rx GSUP Update\n Location Result\nfrom home HLR"]
+	rx_lu_res -> to_top2
+	junction_update_location -> junction_auth_info [label="data known,\nLU confirmed"]
+	WAIT_UPDATE_LOCATION_RESULT->junction_lu_failed [label="Timeout   "]
+	junction_lu_failed [shape=diamond,label="has home HLR\never confirmed\na LU before?"];
+	junction_lu_failed -> to_clear2 [label="never\nconfirmed",style=dashed]
+	junction_lu_failed -> note_lu_failed [label="has\nconfirmed\nbefore"]
+	note_lu_failed [shape=note,label="Home HLR is\ntemporarily unreachable,\n just carry on."]
+	note_lu_failed -> to_top3
+
+	junction_confirm_home_hlr -> action_mslookup_confirm [label="very old"]
+	junction_confirm_home_hlr -> junction_update_location [label="fair enough"]
+	action_mslookup_confirm [shape=larrow,label="start mslookup"]
+	note_mslookup_confirm [shape=note,label="Result evaluated in IDLE state.\nIf no mslookup result comes\n back, the home HLR is\ntemporarily unreachable:\ncontinue anyway.\nThis is sanity checking for\na *modified* home HLR"]
+	action_mslookup_confirm -> note_mslookup_confirm [arrowhead=none,style=dotted]
+	action_mslookup_confirm -> junction_update_location
+
+	junction_auth_info -> action_sai_req [label="need more tuples"]
+	junction_auth_info -> set_idle_timeout [label="cache is fresh"]
+	action_sai_req [shape=larrow,label="Tx GSUP\n Send Auth Info Request\n to home HLR"]
+	action_sai_req -> WAIT_SEND_AUTH_INFO_RESULT
+	WAIT_SEND_AUTH_INFO_RESULT->rx_sai_res[arrowhead=none]
+	rx_sai_res[shape=rarrow,label="Rx GSUP\n Send Auth Info\n Result\nfrom home HLR"]
+	rx_sai_res -> emit_rx_tuples
+	emit_rx_tuples [shape=lpromoter,label="emit\n MM_EV_RX_AUTH_TUPLES"]
+	emit_rx_tuples -> to_top4
+	WAIT_SEND_AUTH_INFO_RESULT->set_idle_timeout[label="Timeout",style=dashed]
+	set_idle_timeout [shape=diamond,label="Select IDLE\n timeout:\nmin(\nretry tuples,\n confirm mslookup)"]
+	set_idle_timeout -> IDLE
+
+	IDLE -> rx_mslookup_confirm_res [arrowhead=none]
+	rx_mslookup_confirm_res [shape=rarrow,label="Rx mslookup result"]
+	rx_mslookup_confirm_res -> junction_compare_home_hlr
+	junction_compare_home_hlr [shape=diamond,label="mslookup result\n matches home HLR\n on record?"]
+	junction_compare_home_hlr -> set_idle_timeout [label="matches"]
+	junction_compare_home_hlr -> to_clear1 [label="mismatch",style=dashed]
+
+	IDLE -> to_top5 [label="Timeout"]
+	IDLE -> {rx_ev_check_tuples,rx_ev_confirm_lu} [arrowhead=none]
+	rx_ev_check_tuples [shape=rpromoter,label="receive\n HOME_EV_CHECK_TUPLES"]
+	rx_ev_confirm_lu [shape=rpromoter,label="receive\n HOME_EV_CONFIRM_LU"]
+	{rx_ev_check_tuples,rx_ev_confirm_lu} -> to_top5
+
+	at_clear -> CLEAR
+	CLEAR -> emit_subscr_invalid -> TERM
+	emit_subscr_invalid [shape=lpromoter,label="emit\n MM_EV_SUBSCR_INVALID"]
+	TERM[shape=octagon][style=bold]
+}

include/Makefile.am

@@ -1,3 +1,13 @@
 SUBDIRS = osmocom
 
-nobase_include_HEADERS = osmocom/gsupclient/gsup_client.h
+nobase_include_HEADERS = \
+	osmocom/gsupclient/gsup_peer_id.h \
+	osmocom/gsupclient/gsup_client.h \
+	osmocom/gsupclient/gsup_req.h \
+	osmocom/mslookup/mdns.h \
+	osmocom/mslookup/mdns_sock.h \
+	osmocom/mslookup/mslookup_client_fake.h \
+	osmocom/mslookup/mslookup_client.h \
+	osmocom/mslookup/mslookup_client_mdns.h \
+	osmocom/mslookup/mslookup.h \
+	$(NULL)

include/osmocom/Makefile.am

@@ -1,3 +1,4 @@
 SUBDIRS = \
 	hlr \
+	mslookup \
 	$(NULL)

include/osmocom/gsupclient/gsup_client.h

@@ -38,6 +38,8 @@ struct osmo_gsup_client;
 /* Expects message in msg->l2h */
 typedef int (*osmo_gsup_client_read_cb_t)(struct osmo_gsup_client *gsupc, struct msgb *msg);
 
+typedef bool (*osmo_gsup_client_up_down_cb_t)(struct osmo_gsup_client *gsupc, bool up);
+
 struct osmo_gsup_client {
 	const char *unit_name; /* same as ipa_dev->unit_name, for backwards compat */
 
@@ -53,8 +55,31 @@ struct osmo_gsup_client {
 	int got_ipa_pong;
 
 	struct ipaccess_unit *ipa_dev; /* identification information sent to IPA server */
+
+	osmo_gsup_client_up_down_cb_t up_down_cb;
 };
 
+struct osmo_gsup_client_config {
+	/*! IP access unit which contains client identification information; must be allocated in talloc_ctx as well to
+	 * ensure it lives throughout the lifetime of the connection. */
+	struct ipaccess_unit *ipa_dev;
+	/*! GSUP server IP address to connect to. */
+	const char *ip_addr;
+	/*! GSUP server TCP port to connect to. */
+	unsigned int tcp_port;
+	/*! OPA client configuration, or NULL. */
+	struct osmo_oap_client_config *oapc_config;
+	/*! callback for reading from the GSUP connection. */
+	osmo_gsup_client_read_cb_t read_cb;
+	/*! Invoked when the GSUP link is ready for communication, and when the link drops. */
+	osmo_gsup_client_up_down_cb_t up_down_cb;
+	/*! User data stored in the returned gsupc->data, as context for the callbacks. */
+	void *data;
+	/*! Marker for future extension, always pass this as false. */
+	bool more;
+};
+struct osmo_gsup_client *osmo_gsup_client_create3(void *talloc_ctx, struct osmo_gsup_client_config *config);
+
 struct osmo_gsup_client *osmo_gsup_client_create2(void *talloc_ctx,
 						  struct ipaccess_unit *ipa_dev,
 						  const char *ip_addr,

include/osmocom/gsupclient/gsup_peer_id.h

@@ -0,0 +1,66 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+#include <unistd.h>
+#include <stdint.h>
+#include <osmocom/core/utils.h>
+
+/*! IPA Name: Arbitrary length blob, not necessarily zero-terminated.
+ * In osmo-hlr, struct hlr_subscriber is mostly used as static reference and cannot serve as talloc context, which is
+ * why this is also implemented as a fixed-maximum-size buffer instead of a talloc'd arbitrary sized buffer.
+ * NOTE: The length of val may be extended in the future if it becomes necessary.
+ * At the time of writing, this holds IPA unit name strings of very limited length.
+ */
+struct osmo_ipa_name {
+	size_t len;
+	uint8_t val[128];
+};
+
+bool osmo_ipa_name_is_empty(struct osmo_ipa_name *ipa_name);
+int osmo_ipa_name_set(struct osmo_ipa_name *ipa_name, const uint8_t *val, size_t len);
+int osmo_ipa_name_set_str(struct osmo_ipa_name *ipa_name, const char *str_fmt, ...);
+int osmo_ipa_name_cmp(const struct osmo_ipa_name *a, const struct osmo_ipa_name *b);
+const char *osmo_ipa_name_to_str_c(void *ctx, const struct osmo_ipa_name *ipa_name);
+const char *osmo_ipa_name_to_str(const struct osmo_ipa_name *ipa_name);
+
+enum osmo_gsup_peer_id_type {
+	OSMO_GSUP_PEER_ID_EMPTY=0,
+	OSMO_GSUP_PEER_ID_IPA_NAME,
+	/* OSMO_GSUP_PEER_ID_GLOBAL_TITLE, <-- currently not implemented, but likely future possibility */
+};
+
+extern const struct value_string osmo_gsup_peer_id_type_names[];
+static inline const char *osmo_gsup_peer_id_type_name(enum osmo_gsup_peer_id_type val)
+{ return get_value_string(osmo_gsup_peer_id_type_names, val); }
+
+struct osmo_gsup_peer_id {
+	enum osmo_gsup_peer_id_type type;
+	union {
+		struct osmo_ipa_name ipa_name;
+	};
+};
+
+bool osmo_gsup_peer_id_is_empty(struct osmo_gsup_peer_id *gsup_peer_id);
+int osmo_gsup_peer_id_set(struct osmo_gsup_peer_id *gsup_peer_id, enum osmo_gsup_peer_id_type type,
+			  const uint8_t *val, size_t len);
+int osmo_gsup_peer_id_set_str(struct osmo_gsup_peer_id *gsup_peer_id, enum osmo_gsup_peer_id_type type,
+			      const char *str_fmt, ...);
+int osmo_gsup_peer_id_cmp(const struct osmo_gsup_peer_id *a, const struct osmo_gsup_peer_id *b);
+const char *osmo_gsup_peer_id_to_str(const struct osmo_gsup_peer_id *gsup_peer_id);
+const char *osmo_gsup_peer_id_to_str_c(void *ctx, const struct osmo_gsup_peer_id *gsup_peer_id);

include/osmocom/gsupclient/gsup_req.h

@@ -0,0 +1,115 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <osmocom/gsm/gsup.h>
+#include <osmocom/gsupclient/gsup_peer_id.h>
+
+struct osmo_gsup_req;
+
+#define LOG_GSUP_REQ_CAT_SRC(req, subsys, level, file, line, fmt, args...) \
+	LOGPSRC(subsys, level, file, line, "GSUP %u: %s: IMSI-%s %s: " fmt, \
+		(req) ? (req)->nr : 0, \
+		(req) ? osmo_gsup_peer_id_to_str(&(req)->source_name) : "NULL", \
+		(req) ? (req)->gsup.imsi : "NULL", \
+		(req) ? osmo_gsup_message_type_name((req)->gsup.message_type) : "NULL", \
+		##args)
+#define LOG_GSUP_REQ_CAT(req, subsys, level, fmt, args...) \
+	LOG_GSUP_REQ_CAT_SRC(req, subsys, level, __FILE__, __LINE__, fmt, ##args)
+
+#define LOG_GSUP_REQ_SRC(req, level, file, line, fmt, args...) \
+	LOG_GSUP_REQ_CAT_SRC(req, DLGSUP, level, file, line, fmt, ##args)
+
+#define LOG_GSUP_REQ(req, level, fmt, args...) \
+	LOG_GSUP_REQ_SRC(req, level, __FILE__, __LINE__, fmt, ##args)
+
+typedef void (*osmo_gsup_req_send_response_t)(struct osmo_gsup_req *req, struct osmo_gsup_message *response);
+
+/* Keep track of an incoming request, to route back a response when it is ready.
+ * Particularly, a GSUP response to a request must contain various bits of information that need to be copied from the
+ * request for proxy/routing to work and for session states to remain valid. That is the main reason why (almost) all
+ * GSUP request/response should go through an osmo_gsup_req, even if it is handled synchronously.
+ */
+struct osmo_gsup_req {
+	/* The incoming GSUP message in decoded form. */
+	const struct osmo_gsup_message gsup;
+
+	/* Decoding result code. If decoding failed, this will be != 0. */
+	int decode_rc;
+
+	/* The ultimate source of this message: the source_name form the GSUP message, or, if not present, then the
+	 * immediate GSUP peer. GSUP messages going via a proxy reflect the initial source in the source_name.
+	 * This source_name is implicitly added to the routes for the conn the message was received on. */
+	struct osmo_gsup_peer_id source_name;
+
+	/* If the source_name is not an immediate GSUP peer, this is set to the closest intermediate peer between here
+	 * and source_name. */
+	struct osmo_gsup_peer_id via_proxy;
+
+	/* Identify this request by number, for logging. */
+	unsigned int nr;
+
+	/* osmo_gsup_req can be used by both gsup_server and gsup_client. The individual method of actually sending a
+	 * GSUP message is provided by this callback. */
+	osmo_gsup_req_send_response_t send_response_cb;
+
+	/* User supplied data pointer, may be used to provide context to send_response_cb(). */
+	void *cb_data;
+
+	/* List entry that can be used to keep a list of osmo_gsup_req instances; not used directly by osmo_gsup_req.c,
+	 * it is up to using implementations to keep a list. If this is non-NULL, osmo_gsup_req_free() calls
+	 * llist_del() on this. */
+	struct llist_head entry;
+
+	/* A decoded GSUP message still points into the received msgb. For a decoded osmo_gsup_message to remain valid,
+	 * we also need to keep the msgb. */
+	struct msgb *msg;
+};
+
+struct osmo_gsup_req *osmo_gsup_req_new(void *ctx, const struct osmo_gsup_peer_id *from_peer, struct msgb *msg,
+					osmo_gsup_req_send_response_t send_response_cb, void *cb_data,
+					struct llist_head *add_to_list);
+void osmo_gsup_req_free(struct osmo_gsup_req *req);
+
+/*! Call _osmo_gsup_req_respond() to convey the sender's source file and line in the logs. */
+#define osmo_gsup_req_respond(REQ, RESPONSE, ERROR, FINAL_RESPONSE) \
+	_osmo_gsup_req_respond(REQ, RESPONSE, ERROR, FINAL_RESPONSE, __FILE__, __LINE__)
+int _osmo_gsup_req_respond(struct osmo_gsup_req *req, struct osmo_gsup_message *response,
+			   bool error, bool final_response, const char *file, int line);
+
+/*! Call _osmo_gsup_req_respond_msgt() to convey the sender's source file and line in the logs. */
+#define osmo_gsup_req_respond_msgt(REQ, MESSAGE_TYPE, FINAL_RESPONSE) \
+	_osmo_gsup_req_respond_msgt(REQ, MESSAGE_TYPE, FINAL_RESPONSE, __FILE__, __LINE__)
+int _osmo_gsup_req_respond_msgt(struct osmo_gsup_req *req, enum osmo_gsup_message_type message_type,
+				bool final_response, const char *file, int line);
+
+/*! Log an error message, and call _osmo_gsup_req_respond() to convey the sender's source file and line in the logs. */
+#define osmo_gsup_req_respond_err(REQ, CAUSE, FMT, args...) do { \
+		LOG_GSUP_REQ(REQ, LOGL_ERROR, "%s: " FMT "\n", \
+			     get_value_string(gsm48_gmm_cause_names, CAUSE), ##args); \
+		_osmo_gsup_req_respond_err(REQ, CAUSE, __FILE__, __LINE__); \
+	} while(0)
+void _osmo_gsup_req_respond_err(struct osmo_gsup_req *req, enum gsm48_gmm_cause cause,
+				const char *file, int line);
+
+int osmo_gsup_make_response(struct osmo_gsup_message *reply,
+			    const struct osmo_gsup_message *rx, bool error, bool final_response);
+
+size_t osmo_gsup_message_to_str_buf(char *buf, size_t bufsize, const struct osmo_gsup_message *msg);
+char *osmo_gsup_message_to_str_c(void *ctx, const struct osmo_gsup_message *msg);

include/osmocom/hlr/Makefile.am

@@ -2,6 +2,7 @@ noinst_HEADERS = \
 	auc.h \
 	ctrl.h \
 	db.h \
+	dgsm.h \
 	gsup_router.h \
 	gsup_server.h \
 	hlr.h \
@@ -9,6 +10,13 @@ noinst_HEADERS = \
 	hlr_vty.h \
 	hlr_vty_subscr.h \
 	logging.h \
-	luop.h \
+	lu_fsm.h \
+	mslookup_server.h \
+	mslookup_server_mdns.h \
+	proxy.h \
+	proxy_mm.h \
+	proxy_db.h \
 	rand.h \
+	remote_hlr.h \
+	timestamp.h \
 	$(NULL)

include/osmocom/hlr/db.h

@@ -3,6 +3,9 @@
 #include <stdbool.h>
 #include <sqlite3.h>
 
+#include <osmocom/gsupclient/gsup_peer_id.h>
+#include <osmocom/gsm/gsup.h>
+
 struct hlr;
 
 enum stmt_idx {
@@ -31,6 +34,9 @@ enum stmt_idx {
 	DB_STMT_SET_LAST_LU_SEEN_PS,
 	DB_STMT_EXISTS_BY_IMSI,
 	DB_STMT_EXISTS_BY_MSISDN,
+	DB_STMT_IND_ADD,
+	DB_STMT_IND_SELECT,
+	DB_STMT_IND_DEL,
 	_NUM_DB_STMT
 };
 
@@ -49,6 +55,7 @@ void db_remove_reset(sqlite3_stmt *stmt);
 bool db_bind_text(sqlite3_stmt *stmt, const char *param_name, const char *text);
 bool db_bind_int(sqlite3_stmt *stmt, const char *param_name, int nr);
 bool db_bind_int64(sqlite3_stmt *stmt, const char *param_name, int64_t nr);
+bool db_bind_null(sqlite3_stmt *stmt, const char *param_name);
 void db_close(struct db_context *dbc);
 struct db_context *db_open(void *ctx, const char *fname, bool enable_sqlite3_logging, bool allow_upgrades);
 
@@ -97,6 +104,9 @@ struct hlr_subscriber {
 	bool		ms_purged_ps;
 	time_t		last_lu_seen;
 	time_t		last_lu_seen_ps;
+	/* talloc'd IPA unit name */
+	struct osmo_ipa_name	vlr_via_proxy;
+	struct osmo_ipa_name	sgsn_via_proxy;
 };
 
 /* A format string for use with strptime(3). This format string is
@@ -151,12 +161,14 @@ int db_subscr_get_by_id(struct db_context *dbc, int64_t id,
 int db_subscr_get_by_imei(struct db_context *dbc, const char *imei, struct hlr_subscriber *subscr);
 int db_subscr_nam(struct db_context *dbc, const char *imsi, bool nam_val, bool is_ps);
 int db_subscr_lu(struct db_context *dbc, int64_t subscr_id,
-		 const char *vlr_or_sgsn_number, bool is_ps);
+		 const struct osmo_ipa_name *vlr_name, bool is_ps,
+		 const struct osmo_ipa_name *via_proxy);
 
 int db_subscr_purge(struct db_context *dbc, const char *by_imsi,
 		    bool purge_val, bool is_ps);
 
-int hlr_subscr_nam(struct hlr *hlr, struct hlr_subscriber *subscr, bool nam_val, bool is_ps);
+int db_ind(struct db_context *dbc, const struct osmo_gsup_peer_id *vlr, unsigned int *ind);
+int db_ind_del(struct db_context *dbc, const struct osmo_gsup_peer_id *vlr);
 
 /*! Call sqlite3_column_text() and copy result to a char[].
  * \param[out] buf  A char[] used as sizeof() arg(!) and osmo_strlcpy() target.
@@ -168,3 +180,14 @@ int hlr_subscr_nam(struct hlr *hlr, struct hlr_subscriber *subscr, bool nam_val,
 		const char *_txt = (const char *) sqlite3_column_text(stmt, idx); \
 		osmo_strlcpy(buf, _txt, sizeof(buf)); \
 	} while (0)
+
+/*! Call sqlite3_column_text() and copy result to a struct osmo_ipa_name.
+ * \param[out] ipa_name  A struct osmo_ipa_name* to write to.
+ * \param[in] stmt  An sqlite3_stmt*.
+ * \param[in] idx  Index in stmt's returned columns.
+ */
+#define copy_sqlite3_text_to_ipa_name(ipa_name, stmt, idx) \
+	do { \
+		const char *_txt = (const char *) sqlite3_column_text(stmt, idx); \
+		osmo_ipa_name_set_str(ipa_name, _txt); \
+	} while (0)

include/osmocom/hlr/dgsm.h

@@ -0,0 +1,46 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#pragma once
+
+#include <osmocom/mslookup/mslookup.h>
+#include <osmocom/hlr/gsup_server.h>
+#include <osmocom/hlr/logging.h>
+#include <osmocom/gsupclient/gsup_peer_id.h>
+#include <osmocom/gsupclient/gsup_req.h>
+
+#define LOG_DGSM(imsi, level, fmt, args...) \
+	LOGP(DDGSM, level, "(IMSI-%s) " fmt, imsi, ##args)
+
+struct vty;
+struct remote_hlr;
+struct hlr_subscriber;
+
+extern void *dgsm_ctx;
+
+void dgsm_init(void *ctx);
+void dgsm_start(void *ctx);
+void dgsm_stop();
+
+bool dgsm_check_forward_gsup_msg(struct osmo_gsup_req *req);
+
+void dgsm_vty_init();
+void dgsm_mdns_client_config_apply(void);
+
+bool hlr_subscr_lu_age(const struct hlr_subscriber *subscr, uint32_t *age_p);

include/osmocom/hlr/gsup_router.h

@@ -3,6 +3,8 @@
 #include <stdint.h>
 #include <osmocom/hlr/gsup_server.h>
 
+struct osmo_ipa_name;
+
 struct gsup_route {
 	struct llist_head list;
 
@@ -12,10 +14,12 @@ struct gsup_route {
 
 struct osmo_gsup_conn *gsup_route_find(struct osmo_gsup_server *gs,
 					const uint8_t *addr, size_t addrlen);
+struct osmo_gsup_conn *gsup_route_find_by_ipa_name(struct osmo_gsup_server *gs, const struct osmo_ipa_name *ipa_name);
 
 struct gsup_route *gsup_route_find_by_conn(const struct osmo_gsup_conn *conn);
 
 /* add a new route for the given address to the given conn */
+int gsup_route_add_ipa_name(struct osmo_gsup_conn *conn, const struct osmo_ipa_name *ipa_name);
 int gsup_route_add(struct osmo_gsup_conn *conn, const uint8_t *addr, size_t addrlen);
 
 /* delete all routes for the given connection */
@@ -24,3 +28,6 @@ int gsup_route_del_conn(struct osmo_gsup_conn *conn);
 int osmo_gsup_addr_send(struct osmo_gsup_server *gs,
 			const uint8_t *addr, size_t addrlen,
 			struct msgb *msg);
+int osmo_gsup_send_to_ipa_name(struct osmo_gsup_server *gs, const struct osmo_ipa_name *ipa_name, struct msgb *msg);
+int osmo_gsup_enc_send_to_ipa_name(struct osmo_gsup_server *gs, const struct osmo_ipa_name *ipa_name,
+			  const struct osmo_gsup_message *gsup);

include/osmocom/hlr/gsup_server.h

@@ -5,6 +5,8 @@
 #include <osmocom/abis/ipa.h>
 #include <osmocom/abis/ipaccess.h>
 #include <osmocom/gsm/gsup.h>
+#include <osmocom/gsupclient/gsup_peer_id.h>
+#include <osmocom/gsupclient/gsup_req.h>
 
 #ifndef OSMO_GSUP_MAX_CALLED_PARTY_BCD_LEN
 #define OSMO_GSUP_MAX_CALLED_PARTY_BCD_LEN	43 /* TS 24.008 10.5.4.7 */
@@ -22,12 +24,12 @@ struct osmo_gsup_server {
 	/* list of osmo_gsup_conn */
 	struct llist_head clients;
 
-	/* lu_operations list */
-	struct llist_head *luop;
-
 	struct ipa_server_link *link;
 	osmo_gsup_read_cb_t read_cb;
 	struct llist_head routes;
+
+	/* Proxy requests from this server's clients to remote GSUP servers. */
+	struct proxy *proxy;
 };
 
 
@@ -45,10 +47,15 @@ struct osmo_gsup_conn {
 	/* Set when Location Update is received: */
 	bool supports_cs; /* client supports OSMO_GSUP_CN_DOMAIN_CS */
 	bool supports_ps; /* client supports OSMO_GSUP_CN_DOMAIN_PS */
+
+	/* The IPA unit name received on this link. Routes with more unit names serviced by this link may exist in
+	 * osmo_gsup_server->routes, but this is the name the immediate peer identified as in the IPA handshake. */
+	struct osmo_ipa_name peer_name;
 };
 
 struct msgb *osmo_gsup_msgb_alloc(const char *label);
 
+struct osmo_gsup_req *osmo_gsup_conn_rx(struct osmo_gsup_conn *conn, struct msgb *msg);
 int osmo_gsup_conn_send(struct osmo_gsup_conn *conn, struct msgb *msg);
 int osmo_gsup_conn_ccm_get(const struct osmo_gsup_conn *clnt, uint8_t **addr,
 			   uint8_t tag);
@@ -57,7 +64,6 @@ struct osmo_gsup_server *osmo_gsup_server_create(void *ctx,
 						 const char *ip_addr,
 						 uint16_t tcp_port,
 						 osmo_gsup_read_cb_t read_cb,
-						 struct llist_head *lu_op_lst,
 						 void *priv);
 
 void osmo_gsup_server_destroy(struct osmo_gsup_server *gsups);
@@ -68,3 +74,5 @@ int osmo_gsup_create_insert_subscriber_data_msg(struct osmo_gsup_message *gsup,
 					    uint8_t *msisdn_enc, size_t msisdn_enc_size,
 				            uint8_t *apn_buf, size_t apn_buf_size,
 					    enum osmo_gsup_cn_domain cn_domain);
+int osmo_gsup_forward_to_local_peer(struct osmo_gsup_server *server, const struct osmo_gsup_peer_id *to_peer,
+				    struct osmo_gsup_req *req, struct osmo_gsup_message *modified_gsup);

include/osmocom/hlr/hlr.h

@@ -24,10 +24,19 @@
 
 #include <stdbool.h>
 #include <osmocom/core/linuxlist.h>
+#include <osmocom/gsm/ipa.h>
+#include <osmocom/core/tdef.h>
+#include <osmocom/core/sockaddr_str.h>
+
+#include <osmocom/hlr/dgsm.h>
 
 #define HLR_DEFAULT_DB_FILE_PATH "hlr.db"
 
 struct hlr_euse;
+struct osmo_gsup_conn;
+enum osmo_gsup_message_type;
+
+extern struct osmo_tdef g_hlr_tdefs[];
 
 struct hlr {
 	/* GSUP server pointer */
@@ -43,10 +52,10 @@ struct hlr {
 
 	/* Local bind addr */
 	char *gsup_bind_addr;
+	struct ipaccess_unit gsup_unit_name;
 
 	struct llist_head euse_list;
 	struct hlr_euse *euse_default;
-	struct llist_head iuse_list;
 
 	/* NCSS (call independent) session guard timeout value */
 	int ncss_guard_timeout;
@@ -61,6 +70,47 @@ struct hlr {
 	/* Bitmask of DB_SUBSCR_FLAG_* */
 	uint8_t subscr_create_on_demand_flags;
 	unsigned int subscr_create_on_demand_rand_msisdn_len;
+
+	struct {
+		bool allow_startup;
+		struct {
+			/* Whether the mslookup server should be active in general (all lookup methods) */
+			bool enable;
+			uint32_t local_attach_max_age;
+			struct llist_head local_site_services;
+			struct {
+				/* Whether the mDNS method of the mslookup server should be active. */
+				bool enable;
+				/* The mDNS bind address and domain suffix as set by the VTY, not necessarily in use. */
+				struct osmo_sockaddr_str bind_addr;
+				char *domain_suffix;
+				struct osmo_mslookup_server_mdns *running;
+			} mdns;
+		} server;
+
+		/* The mslookup client in osmo-hlr is used to find out which remote HLRs service a locally unknown IMSI.
+		 * (It may also be used to resolve recipients for SMS-over-GSUP in the future.) */
+		struct {
+			/* Whether to proxy/forward to remote HLRs */
+			bool enable;
+
+			/* If this is set, all GSUP for unknown IMSIs is forwarded directly to this GSUP address,
+			 * unconditionally. */
+			struct osmo_sockaddr_str gsup_gateway_proxy;
+
+			/* mslookup client request handling */
+			unsigned int result_timeout_milliseconds;
+
+			struct osmo_mslookup_client *client;
+			struct {
+				/* Whether to use mDNS for IMSI MS Lookup */
+				bool enable;
+				struct osmo_sockaddr_str query_addr;
+				char *domain_suffix;
+				struct osmo_mslookup_client_method *running;
+			} mdns;
+		} client;
+	} mslookup;
 };
 
 extern struct hlr *g_hlr;
@@ -68,3 +118,4 @@ extern struct hlr *g_hlr;
 struct hlr_subscriber;
 
 void osmo_hlr_subscriber_update_notify(struct hlr_subscriber *subscr);
+int hlr_subscr_nam(struct hlr *hlr, struct hlr_subscriber *subscr, bool nam_val, bool is_ps);

include/osmocom/hlr/hlr_ussd.h

@@ -46,8 +46,8 @@ struct hlr_ussd_route *ussd_route_prefix_alloc_ext(struct hlr *hlr, const char *
 						   struct hlr_euse *euse);
 void ussd_route_del(struct hlr_ussd_route *rt);
 
-int rx_proc_ss_req(struct osmo_gsup_conn *conn, const struct osmo_gsup_message *gsup);
-int rx_proc_ss_error(struct osmo_gsup_conn *conn, const struct osmo_gsup_message *gsup);
+void rx_proc_ss_req(struct osmo_gsup_req *req);
+void rx_proc_ss_error(struct osmo_gsup_req *req);
 
 struct ss_session;
 struct ss_request;
@@ -56,6 +56,5 @@ struct ss_request;
 struct hlr_iuse {
 	const char *name;
 	/* call-back to be called for any incoming USSD messages for this IUSE */
-	int (*handle_ussd)(struct osmo_gsup_conn *conn, struct ss_session *ss,
-			   const struct osmo_gsup_message *gsup, const struct ss_request *req);
+	int (*handle_ussd)(struct ss_session *ss, const struct osmo_gsup_message *gsup, const struct ss_request *req);
 };

include/osmocom/hlr/hlr_vty.h

@@ -31,8 +31,13 @@ enum hlr_vty_node {
 	HLR_NODE = _LAST_OSMOVTY_NODE + 1,
 	GSUP_NODE,
 	EUSE_NODE,
+	MSLOOKUP_NODE,
+	MSLOOKUP_SERVER_NODE,
+	MSLOOKUP_SERVER_MSC_NODE,
+	MSLOOKUP_CLIENT_NODE,
 };
 
 int hlr_vty_is_config_node(struct vty *vty, int node);
 int hlr_vty_go_parent(struct vty *vty);
 void hlr_vty_init(void);
+void dgsm_vty_init(void);

include/osmocom/hlr/logging.h

@@ -8,6 +8,9 @@ enum {
 	DGSUP,
 	DAUC,
 	DSS,
+	DMSLOOKUP,
+	DLU,
+	DDGSM,
 };
 
 extern const struct log_info hlr_log_info;

include/osmocom/hlr/lu_fsm.h

@@ -0,0 +1,22 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#pragma once
+
+void lu_rx_gsup(struct osmo_gsup_req *req);

include/osmocom/hlr/luop.h

@@ -1,81 +0,0 @@
-/* OsmoHLR TX/RX lu operations */
-
-/* (C) 2017 sysmocom s.f.m.c. GmbH <info@sysmocom.de>
- * All Rights Reserved
- *
- * Author: Harald Welte <laforge@gnumonks.org>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License as published by
- * the Free Software Foundation; either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Affero General Public License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- */
-
-#pragma once
-
-#include <stdbool.h>
-
-#include <osmocom/core/timer.h>
-#include <osmocom/gsm/gsup.h>
-
-#include <osmocom/hlr/db.h>
-#include <osmocom/hlr/gsup_server.h>
-
-#define CANCEL_TIMEOUT_SECS	30
-#define ISD_TIMEOUT_SECS	30
-
-enum lu_state {
-	LU_S_NULL,
-	LU_S_LU_RECEIVED,
-	LU_S_CANCEL_SENT,
-	LU_S_CANCEL_ACK_RECEIVED,
-	LU_S_ISD_SENT,
-	LU_S_ISD_ACK_RECEIVED,
-	LU_S_COMPLETE,
-};
-
-extern const struct value_string lu_state_names[];
-
-struct lu_operation {
-	/*! entry in global list of location update operations */
-	struct llist_head list;
-	/*! to which gsup_server do we belong */
-	struct osmo_gsup_server *gsup_server;
-	/*! state of the location update */
-	enum lu_state state;
-	/*! CS (false) or PS (true) Location Update? */
-	bool is_ps;
-	/*! currently running timer */
-	struct osmo_timer_list timer;
-
-	/*! subscriber related to this operation */
-	struct hlr_subscriber subscr;
-	/*! peer VLR/SGSN starting the request */
-	uint8_t *peer;
-};
-
-
-struct lu_operation *lu_op_alloc(struct osmo_gsup_server *srv);
-struct lu_operation *lu_op_alloc_conn(struct osmo_gsup_conn *conn);
-void lu_op_statechg(struct lu_operation *luop, enum lu_state new_state);
-bool lu_op_fill_subscr(struct lu_operation *luop, struct db_context *dbc,
-		       const char *imsi);
-struct lu_operation *lu_op_by_imsi(const char *imsi,
-				   const struct llist_head *lst);
-
-void lu_op_tx_error(struct lu_operation *luop, enum gsm48_gmm_cause cause);
-void lu_op_tx_ack(struct lu_operation *luop);
-void lu_op_tx_cancel_old(struct lu_operation *luop);
-void lu_op_tx_insert_subscr_data(struct lu_operation *luop);
-void lu_op_tx_del_subscr_data(struct lu_operation *luop);
-
-void lu_op_free(struct lu_operation *luop);

include/osmocom/hlr/mslookup_server.h

@@ -0,0 +1,72 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#pragma once
+
+#include <osmocom/gsupclient/gsup_peer_id.h>
+#include <osmocom/mslookup/mslookup.h>
+
+struct osmo_mslookup_query;
+struct osmo_mslookup_result;
+
+/*! mslookup service name used for roaming/proxying between osmo-hlr instances. */
+#define OSMO_MSLOOKUP_SERVICE_HLR_GSUP "gsup.hlr"
+
+/*! What addresses to return to mslookup queries when a subscriber is attached at the local site.
+ * Mapping of service name to IP address and port. This corresponds to the VTY config for
+ * 'mslookup' / 'server' [/ 'msc MSC-1-2-3'] / 'service sip.voice at 1.2.3.4 1234'.
+ */
+struct mslookup_service_host {
+	struct llist_head entry;
+	char service[OSMO_MSLOOKUP_SERVICE_MAXLEN+1];
+	struct osmo_sockaddr_str host_v4;
+	struct osmo_sockaddr_str host_v6;
+};
+
+/*! Sets of mslookup_service_host per connected MSC.
+ * When there are more than one MSC connected to this osmo-hlr, this allows keeping separate sets of service addresses
+ * for each MSC. The entry with mslookup_server_msc_wildcard as MSC name is used for all MSCs (if no match for that
+ * particular MSC is found). This corresponds to the VTY config for
+ * 'mslookup' / 'server' / 'msc MSC-1-2-3'.
+ */
+struct mslookup_server_msc_cfg {
+	struct llist_head entry;
+	struct osmo_ipa_name name;
+	struct llist_head service_hosts;
+};
+
+struct mslookup_service_host *mslookup_server_service_get(const struct osmo_ipa_name *msc_name, const char *service);
+
+struct mslookup_service_host *mslookup_server_msc_service_get(struct mslookup_server_msc_cfg *msc, const char *service,
+							      bool create);
+int mslookup_server_msc_service_set(struct mslookup_server_msc_cfg *msc, const char *service,
+				    const struct osmo_sockaddr_str *addr);
+int mslookup_server_msc_service_del(struct mslookup_server_msc_cfg *msc, const char *service,
+				    const struct osmo_sockaddr_str *addr);
+
+extern const struct osmo_ipa_name mslookup_server_msc_wildcard;
+struct mslookup_server_msc_cfg *mslookup_server_msc_get(const struct osmo_ipa_name *msc_name, bool create);
+
+const struct mslookup_service_host *mslookup_server_get_local_gsup_addr();
+void mslookup_server_rx(const struct osmo_mslookup_query *query,
+			     struct osmo_mslookup_result *result);
+
+bool subscriber_has_done_lu_here(const struct osmo_mslookup_query *query,
+				 uint32_t *lu_age_p, struct osmo_ipa_name *local_msc_name,
+				 char *ret_imsi, size_t ret_imsi_len);

include/osmocom/hlr/mslookup_server_mdns.h

@@ -0,0 +1,36 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <osmocom/core/sockaddr_str.h>
+#include <osmocom/mslookup/mdns_sock.h>
+
+struct osmo_mslookup_server_mdns {
+	struct osmo_mslookup_server *mslookup;
+	struct osmo_sockaddr_str bind_addr;
+	char *domain_suffix;
+	struct osmo_mdns_sock *sock;
+};
+
+struct osmo_mslookup_server_mdns *osmo_mslookup_server_mdns_start(void *ctx, const struct osmo_sockaddr_str *bind_addr,
+								  const char *domain_suffix);
+void osmo_mslookup_server_mdns_stop(struct osmo_mslookup_server_mdns *server);
+void mslookup_server_mdns_config_apply();

include/osmocom/hlr/proxy.h

@@ -0,0 +1,100 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#pragma once
+
+#include <time.h>
+#include <osmocom/core/sockaddr_str.h>
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/core/timer.h>
+#include <osmocom/gsm/protocol/gsm_23_003.h>
+#include <osmocom/gsm/gsup.h>
+#include <osmocom/gsupclient/gsup_peer_id.h>
+#include <osmocom/hlr/timestamp.h>
+
+struct osmo_gsup_req;
+struct remote_hlr;
+
+struct proxy {
+	struct llist_head subscr_list;
+	struct llist_head pending_gsup_reqs;
+
+	/* When messages arrive back from a remote HLR that this is the proxy for, reach the VLR to forward the response
+	 * to via this osmo_gsup_server. */
+	struct osmo_gsup_server *gsup_server_to_vlr;
+
+	/* How long to keep proxy entries without a refresh, in seconds. */
+	uint32_t fresh_time;
+
+	/* How often to garbage collect the proxy cache, period in seconds.
+	 * To change this and take effect immediately, rather use proxy_set_gc_period(). */
+	uint32_t gc_period;
+
+	struct osmo_timer_list gc_timer;
+};
+
+struct proxy_subscr_domain_state {
+	struct osmo_ipa_name vlr_name;
+	timestamp_t last_lu;
+
+	/* The name from which an Update Location Request was received. Copied to vlr_name as soon as the LU is
+	 * completed successfully. */
+	struct osmo_ipa_name vlr_name_preliminary;
+
+	/* Set if this is a middle proxy, i.e. a proxy behind another proxy.
+	 * That is mostly to know whether the MS is attached at a local MSC/SGSN or further away.
+	 * It could be a boolean, but store the full name for logging. Set only at successful LU acceptance. */
+	struct osmo_ipa_name vlr_via_proxy;
+};
+
+struct proxy_subscr {
+	char imsi[GSM23003_IMSI_MAX_DIGITS+1];
+	char msisdn[GSM23003_MSISDN_MAX_DIGITS+1];
+	struct osmo_sockaddr_str remote_hlr_addr;
+	struct proxy_subscr_domain_state cs, ps;
+	struct osmo_fsm_inst *mm_fi;
+	struct osmo_fsm_inst *to_home_fi;
+};
+
+void proxy_init(struct osmo_gsup_server *gsup_server_to_vlr);
+void proxy_del(struct proxy *proxy);
+void proxy_set_gc_period(struct proxy *proxy, uint32_t gc_period);
+
+/* The API to access / modify proxy entries keeps the implementation opaque, to make sure that we can easily move proxy
+ * storage to SQLite db. */
+int proxy_subscr_get_by_imsi(struct proxy_subscr *dst, struct proxy *proxy, const char *imsi);
+int proxy_subscr_get_by_msisdn(struct proxy_subscr *dst, struct proxy *proxy, const char *msisdn);
+void proxy_subscrs_get_by_remote_hlr(struct proxy *proxy, const struct osmo_sockaddr_str *remote_hlr_addr,
+				     bool (*yield)(struct proxy *proxy, const struct proxy_subscr *subscr, void *data),
+				     void *data);
+int proxy_subscr_create_or_update(struct proxy *proxy, const struct proxy_subscr *proxy_subscr);
+int proxy_subscr_del(struct proxy *proxy, const char *imsi);
+
+int proxy_subscr_forward_to_remote_hlr(struct proxy *proxy, const struct proxy_subscr *proxy_subscr,
+				       struct osmo_gsup_req *req);
+void proxy_subscr_forward_to_remote_hlr_resolved(struct proxy *proxy, const struct proxy_subscr *proxy_subscr,
+						 struct remote_hlr *remote_hlr, struct osmo_gsup_req *req);
+
+int proxy_subscr_forward_to_vlr(struct proxy *proxy, const struct proxy_subscr *proxy_subscr,
+				const struct osmo_gsup_message *gsup, struct remote_hlr *from_remote_hlr);
+
+void proxy_subscr_remote_hlr_resolved(struct proxy *proxy, const struct proxy_subscr *proxy_subscr,
+				      const struct osmo_sockaddr_str *remote_hlr_addr);
+void proxy_subscr_remote_hlr_up(struct proxy *proxy, const struct proxy_subscr *proxy_subscr,
+				struct remote_hlr *remote_hlr);

include/osmocom/hlr/proxy_broken_link_cache.h

@@ -0,0 +1,37 @@
+/* Copyright 2020 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * Author: Neels Hofmeyr <neels@hofmeyr.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+/* If a subscriber from a remote site has successfully attached at this local site, and the link to the subscriber's
+ * home HLR has succeeded, this will try to bridge the time of temporary link failure to that home HLR.
+ * Tasks to take over from the unreachable home HLR:
+ * - Resend known auth tuples on OSMO_GSUP_MSGT_SEND_AUTH_INFO_REQUEST.
+ * - ...?
+ *
+ *
+ */
+
+/* Data stored per subscriber */
+struct proxy_broken_link_cache {
+	struct osmo_auth_vector auth_vectors[OSMO_GSUP_MAX_NUM_AUTH_INFO];
+	size_t num_auth_vectors;
+
+	timestamp_t last_update;
+};

include/osmocom/hlr/proxy_mm.h

@@ -0,0 +1,54 @@
+#pragma once
+
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/hlr/proxy.h>
+
+enum proxy_mm_fsm_event {
+	PROXY_MM_EV_SUBSCR_INVALID,
+	PROXY_MM_EV_RX_GSUP_LU,
+	PROXY_MM_EV_RX_GSUP_SAI,
+	PROXY_MM_EV_RX_SUBSCR_DATA,
+	PROXY_MM_EV_RX_GSUP_ISD_RESULT,
+	PROXY_MM_EV_RX_AUTH_TUPLES,
+};
+
+enum proxy_to_home_fsm_event {
+	PROXY_TO_HOME_EV_HOME_HLR_RESOLVED,
+	PROXY_TO_HOME_EV_RX_INSERT_SUBSCRIBER_DATA_REQ,
+	PROXY_TO_HOME_EV_RX_UPDATE_LOCATION_RESULT,
+	PROXY_TO_HOME_EV_RX_SEND_AUTH_INFO_RESULT,
+	PROXY_TO_HOME_EV_CHECK_TUPLES,
+	PROXY_TO_HOME_EV_CONFIRM_LU,
+};
+
+extern struct llist_head proxy_mm_list;
+
+struct proxy_mm_auth_cache {
+	struct llist_head entry;
+	uint64_t db_id;
+	struct osmo_auth_vector	auth_vectors[OSMO_GSUP_MAX_NUM_AUTH_INFO];
+	size_t num_auth_vectors;
+	unsigned int sent_to_vlr_count;
+};
+
+struct proxy_mm {
+	struct llist_head entry;
+	struct osmo_gsup_peer_id vlr_name;
+	char imsi[GSM23003_IMSI_MAX_DIGITS+1];
+	bool is_ps;
+	struct osmo_fsm_inst *mm_fi;
+	struct osmo_fsm_inst *to_home_fi;
+	struct llist_head auth_cache;
+};
+
+struct proxy_mm *proxy_mm_alloc(const struct osmo_gsup_peer_id *vlr_name,
+				bool is_ps,
+				const char *imsi);
+
+void proxy_mm_add_auth_vectors(struct proxy_mm *proxy_mm,
+			       const struct osmo_auth_vector *auth_vectors, size_t num_auth_vectors);
+struct proxy_mm_auth_cache *proxy_mm_get_auth_vectors(struct proxy_mm *proxy_mm);
+void proxy_mm_use_auth_vectors(struct proxy_mm *proxy_mm, struct proxy_mm_auth_cache *ac);
+void proxy_mm_discard_auth_vectors(struct proxy_mm *proxy_mm, struct proxy_mm_auth_cache *ac);
+
+bool proxy_mm_subscriber_data_known(const struct proxy_mm *proxy_mm);

include/osmocom/hlr/remote_hlr.h

@@ -0,0 +1,59 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/core/sockaddr_str.h>
+
+struct osmo_gsup_client;
+struct osmo_gsup_message;
+struct osmo_gsup_req;
+struct msgb;
+
+#define LOG_REMOTE_HLR(remote_hlr, level, fmt, args...) \
+	LOGP(DDGSM, level, "(Proxy HLR-" OSMO_SOCKADDR_STR_FMT ") " fmt, \
+	     OSMO_SOCKADDR_STR_FMT_ARGS((remote_hlr) ? &(remote_hlr)->addr : NULL), ##args)
+
+#define LOG_REMOTE_HLR_MSG(remote_hlr, gsup_msg, level, fmt, args...) \
+	LOG_REMOTE_HLR(remote_hlr, level, "%s: " fmt, osmo_gsup_message_type_name((gsup_msg)->message_type), ##args)
+
+/* GSUP client link for proxying to a remote HLR. */
+struct remote_hlr {
+	struct llist_head entry;
+	struct osmo_sockaddr_str addr;
+	struct osmo_gsup_client *gsupc;
+	struct llist_head pending_up_callbacks;
+};
+
+/*! Receive a remote_hlr address when connecting succeeded, or remote_hlr == NULL on error.
+ * \param addr  GSUP IP address and port for which the connection was requested.
+ * \param remote_hlr  The connected remote_hlr ready for sending, or NULL if connecting failed.
+ * \param data  Same a passed to remote_hlr_get_or_connect(). */
+typedef void (*remote_hlr_connect_result_cb_t)(const struct osmo_sockaddr_str *addr, struct remote_hlr *remote_hlr, void *data);
+
+struct remote_hlr *remote_hlr_get_or_connect(const struct osmo_sockaddr_str *addr, bool connect,
+					     remote_hlr_connect_result_cb_t connect_result_cb, void *data);
+void remote_hlr_destroy(struct remote_hlr *remote_hlr);
+int remote_hlr_msgb_send(struct remote_hlr *remote_hlr, struct msgb *msg);
+void remote_hlr_gsup_forward_to_remote_hlr(struct remote_hlr *remote_hlr, struct osmo_gsup_req *req,
+					   struct osmo_gsup_message *modified_gsup);
+
+bool remote_hlr_is_up(struct remote_hlr *remote_hlr);

include/osmocom/hlr/timestamp.h

@@ -0,0 +1,28 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#pragma once
+
+#include <sys/time.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+typedef time_t timestamp_t;
+void timestamp_update(timestamp_t *timestamp);
+bool timestamp_age(const timestamp_t *timestamp, uint32_t *age);

include/osmocom/mslookup/Makefile.am

@@ -0,0 +1,6 @@
+# most headers here are installed, see /include/Makefile.am
+
+noinst_HEADERS = \
+	mdns_msg.h \
+	mdns_rfc.h \
+	$(NULL)

include/osmocom/mslookup/mdns.h

@@ -0,0 +1,39 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*! \file mdns.h */
+
+#pragma once
+
+#include <osmocom/core/msgb.h>
+#include <osmocom/mslookup/mslookup.h>
+
+#define OSMO_MDNS_DOMAIN_SUFFIX_DEFAULT "mdns.osmocom.org"
+
+struct msgb *osmo_mdns_query_encode(void *ctx, uint16_t packet_id, const struct osmo_mslookup_query *query,
+				    const char *domain_suffix);
+
+struct osmo_mslookup_query *osmo_mdns_query_decode(void *ctx, const uint8_t *data, size_t data_len,
+						   uint16_t *packet_id, const char *domain_suffix);
+
+struct msgb *osmo_mdns_result_encode(void *ctx, uint16_t packet_id, const struct osmo_mslookup_query *query,
+				     const struct osmo_mslookup_result *result, const char *domain_suffix);
+
+int osmo_mdns_result_decode(void *ctx, const uint8_t *data, size_t data_len, uint16_t *packet_id,
+			    struct osmo_mslookup_query *query, struct osmo_mslookup_result *result,
+			    const char *domain_suffix);

include/osmocom/mslookup/mdns_msg.h

@@ -0,0 +1,54 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <stdint.h>
+#include "mdns_rfc.h"
+
+struct osmo_mdns_record {
+	struct llist_head list;
+	enum osmo_mdns_rfc_record_type type;
+	uint16_t length;
+	uint8_t *data;
+};
+
+struct osmo_mdns_msg_request {
+	uint16_t id;
+	char *domain;
+	enum osmo_mdns_rfc_record_type type;
+};
+
+struct osmo_mdns_msg_answer {
+	uint16_t id;
+	char *domain;
+	/*! list of osmo_mdns_record. */
+	struct llist_head records;
+};
+
+int osmo_mdns_msg_request_encode(void *ctx, struct msgb *msg, const struct osmo_mdns_msg_request *req);
+struct osmo_mdns_msg_request *osmo_mdns_msg_request_decode(void *ctx, const uint8_t *data, size_t data_len);
+
+void osmo_mdns_msg_answer_init(struct osmo_mdns_msg_answer *answer);
+int osmo_mdns_msg_answer_encode(void *ctx, struct msgb *msg, const struct osmo_mdns_msg_answer *ans);
+struct osmo_mdns_msg_answer *osmo_mdns_msg_answer_decode(void *ctx, const uint8_t *data, size_t data_len);
+int osmo_mdns_result_from_answer(struct osmo_mslookup_result *result, const struct osmo_mdns_msg_answer *ans);
+
+struct osmo_mdns_record *osmo_mdns_record_txt_keyval_encode(void *ctx, const char *key, const char *value_fmt, ...);
+int osmo_mdns_record_txt_keyval_decode(const struct osmo_mdns_record *rec,
+				       char *key_buf, size_t key_size, char *value_buf, size_t value_size);

include/osmocom/mslookup/mdns_rfc.h

@@ -0,0 +1,113 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/endian.h>
+#include <osmocom/mslookup/mdns.h>
+
+/* RFC 1035 2.3.4 */
+#define OSMO_MDNS_RFC_MAX_NAME_LEN 255
+
+/* RFC 1035 3.3 <character-string> */
+#define OSMO_MDNS_RFC_MAX_CHARACTER_STRING_LEN 256
+
+enum osmo_mdns_rfc_record_type {
+	OSMO_MDNS_RFC_RECORD_TYPE_UNKNOWN = 0,
+
+	/* RFC 1035 3.2.2 */
+	OSMO_MDNS_RFC_RECORD_TYPE_A = 1, /* IPv4 address */
+	OSMO_MDNS_RFC_RECORD_TYPE_TXT = 16, /* Text strings */
+
+	/* RFC 3596 2.1 */
+	OSMO_MDNS_RFC_RECORD_TYPE_AAAA = 28, /* IPv6 address */
+
+	/* RFC 1035 3.2.3 */
+	OSMO_MDNS_RFC_RECORD_TYPE_ALL = 255, /* Request only: ask for all */
+};
+
+enum osmo_mdns_rfc_class {
+	OSMO_MDNS_RFC_CLASS_UNKNOWN = 0,
+
+	/* RFC 1035 3.2.4 */
+	OSMO_MDNS_RFC_CLASS_IN = 1, /* Internet and IP networks */
+
+	/* RFC 1035 3.2.5 */
+	OSMO_MDNS_RFC_CLASS_ALL = 255, /* Request only: ask for all */
+};
+
+/* RFC 1035 4.1.1 */
+struct osmo_mdns_rfc_header {
+#if OSMO_IS_LITTLE_ENDIAN
+	uint16_t id;
+	uint8_t rd:1,
+		tc:1,
+		aa:1,
+		opcode:4,
+		qr:1; /* QR (0: query, 1: response) */
+	uint8_t rcode:4,
+		z:3,
+		ra:1;
+	uint16_t qdcount; /* Number of questions */
+	uint16_t ancount; /* Number of answers */
+	uint16_t nscount; /* Number of authority records */
+	uint16_t arcount; /* Number of additional records */
+#elif OSMO_IS_BIG_ENDIAN
+/* auto-generated from the little endian part above (libosmocore/contrib/struct_endianess.py) */
+	uint16_t id;
+	uint8_t qr:1, opcode:4, aa:1, tc:1, rd:1;
+	uint8_t ra:1, z:3, rcode:4;
+	uint16_t qdcount;
+	uint16_t ancount;
+	uint16_t nscount;
+	uint16_t arcount;
+#endif
+} __attribute__ ((packed));
+
+/* RFC 1035 4.1.2 */
+struct osmo_mdns_rfc_question {
+	char *domain; /* Domain to be encoded as qname (e.g. "gsup.hlr.1234567.imsi") */
+	enum osmo_mdns_rfc_record_type qtype;
+	enum osmo_mdns_rfc_class qclass;
+};
+
+/* RFC 1035 4.1.3 */
+struct osmo_mdns_rfc_record {
+	char *domain; /* Domain to be encoded as name (e.g. "gsup.hlr.1234567.imsi") */
+	enum osmo_mdns_rfc_record_type type;
+	enum osmo_mdns_rfc_class class;
+	uint32_t ttl;
+	uint16_t rdlength;
+	uint8_t *rdata;
+};
+
+char *osmo_mdns_rfc_qname_encode(void *ctx, const char *domain);
+char *osmo_mdns_rfc_qname_decode(void *ctx, const char *qname, size_t qname_len);
+
+void osmo_mdns_rfc_header_encode(struct msgb *msg, const struct osmo_mdns_rfc_header *hdr);
+int osmo_mdns_rfc_header_decode(const uint8_t *data, size_t data_len, struct osmo_mdns_rfc_header *hdr);
+
+int osmo_mdns_rfc_question_encode(void *ctx, struct msgb *msg, const struct osmo_mdns_rfc_question *qst);
+struct osmo_mdns_rfc_question *osmo_mdns_rfc_question_decode(void *ctx, const uint8_t *data, size_t data_len);
+
+int osmo_mdns_rfc_record_encode(void *ctx, struct msgb *msg, const struct osmo_mdns_rfc_record *rec);
+struct osmo_mdns_rfc_record *osmo_mdns_rfc_record_decode(void *ctx, const uint8_t *data, size_t data_len,
+							 size_t *record_len);

include/osmocom/mslookup/mdns_sock.h

@@ -0,0 +1,33 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+#include <netdb.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/select.h>
+
+struct osmo_mdns_sock {
+	struct osmo_fd osmo_fd;
+	struct addrinfo *ai;
+};
+
+struct osmo_mdns_sock *osmo_mdns_sock_init(void *ctx, const char *ip, unsigned int port,
+					   int (*cb)(struct osmo_fd *fd, unsigned int what),
+					   void *data, unsigned int priv_nr);
+int osmo_mdns_sock_send(const struct osmo_mdns_sock *mdns_sock, struct msgb *msg);
+void osmo_mdns_sock_cleanup(struct osmo_mdns_sock *mdns_sock);

include/osmocom/mslookup/mslookup.h

@@ -0,0 +1,121 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*! \defgroup mslookup Distributed GSM: finding subscribers
+ *  @{
+ * \file mslookup.h
+ */
+
+#pragma once
+
+#include <osmocom/core/utils.h>
+#include <osmocom/core/sockaddr_str.h>
+#include <osmocom/gsm/protocol/gsm_23_003.h>
+
+#define OSMO_MSLOOKUP_SERVICE_MAXLEN 64
+
+bool osmo_mslookup_service_valid(const char *service);
+
+enum osmo_mslookup_id_type {
+	OSMO_MSLOOKUP_ID_NONE = 0,
+	OSMO_MSLOOKUP_ID_IMSI,
+	OSMO_MSLOOKUP_ID_MSISDN,
+};
+
+extern const struct value_string osmo_mslookup_id_type_names[];
+static inline const char *osmo_mslookup_id_type_name(enum osmo_mslookup_id_type val)
+{ return get_value_string(osmo_mslookup_id_type_names, val); }
+
+struct osmo_mslookup_id {
+	enum osmo_mslookup_id_type type;
+	union {
+		char imsi[GSM23003_IMSI_MAX_DIGITS+1];
+		char msisdn[GSM23003_MSISDN_MAX_DIGITS+1];
+	};
+};
+
+int osmo_mslookup_id_cmp(const struct osmo_mslookup_id *a, const struct osmo_mslookup_id *b);
+bool osmo_mslookup_id_valid(const struct osmo_mslookup_id *id);
+
+enum osmo_mslookup_result_code {
+	OSMO_MSLOOKUP_RC_NONE = 0,
+	/*! An intermediate valid result. The request is still open for more results. */
+	OSMO_MSLOOKUP_RC_RESULT,
+	/*! Returned when the final request timeout has elapsed without results. */
+	OSMO_MSLOOKUP_RC_NOT_FOUND,
+};
+
+extern const struct value_string osmo_mslookup_result_code_names[];
+static inline const char *osmo_mslookup_result_code_name(enum osmo_mslookup_result_code val)
+{ return get_value_string(osmo_mslookup_result_code_names, val); }
+
+/*! Information to request from a lookup. */
+struct osmo_mslookup_query {
+	/*! Which service to request, by freely invented names. For service name conventions (for voice, SMS, HLR,...),
+	 * refer to the OsmoHLR user's manual http://ftp.osmocom.org/docs/latest/osmohlr-usermanual.pdf */
+	char service[OSMO_MSLOOKUP_SERVICE_MAXLEN + 1];
+	/*! IMSI or MSISDN to look up. */
+	struct osmo_mslookup_id id;
+
+	/*! Caller provided private data, if desired. */
+	void *priv;
+};
+
+/*! Result data as passed back to a lookup client that invoked an osmo_mslookup_client_request. */
+struct osmo_mslookup_result {
+	/*! Outcome of the request. */
+	enum osmo_mslookup_result_code rc;
+
+	/*! IP address and port to reach the given service via IPv4, if any. */
+	struct osmo_sockaddr_str host_v4;
+
+	/*! IP address and port to reach the given service via IPv6, if any. */
+	struct osmo_sockaddr_str host_v6;
+
+	/*! How long ago the service last verified presence of the subscriber, in seconds, or zero if the presence is
+	 * invariable (like the home HLR record for an IMSI).
+	 * If a subscriber has recently moved to a different location, we get multiple replies and want to choose the
+	 * most recent one. If this were a timestamp, firstly the time zones would need to be taken care of.
+	 * Even if we choose UTC, a service provider with an inaccurate date/time would end up affecting the result.
+	 * The least susceptible to configuration errors or difference in local and remote clock is a value that
+	 * indicates the actual age of the record in seconds. The time that the lookup query took to be answered should
+	 * be neglectable here, since we would typically wait one second (or very few seconds) for lookup replies,
+	 * while typical Location Updating periods are in the range of 15 minutes. */
+	uint32_t age;
+
+	/*! Whether this is the last result returned for this request. */
+	bool last;
+};
+
+int osmo_mslookup_query_init_from_domain_str(struct osmo_mslookup_query *q, const char *domain);
+
+size_t osmo_mslookup_id_name_buf(char *buf, size_t buflen, const struct osmo_mslookup_id *id);
+char *osmo_mslookup_id_name_c(void *ctx, const struct osmo_mslookup_id *id);
+char *osmo_mslookup_id_name_b(char *buf, size_t buflen, const struct osmo_mslookup_id *id);
+
+size_t osmo_mslookup_result_to_str_buf(char *buf, size_t buflen,
+				     const struct osmo_mslookup_query *query,
+				     const struct osmo_mslookup_result *result);
+char *osmo_mslookup_result_name_c(void *ctx,
+				  const struct osmo_mslookup_query *query,
+				  const struct osmo_mslookup_result *result);
+char *osmo_mslookup_result_name_b(char *buf, size_t buflen,
+				  const struct osmo_mslookup_query *query,
+				  const struct osmo_mslookup_result *result);
+
+/*! @} */

include/osmocom/mslookup/mslookup_client.h

@@ -0,0 +1,132 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/core/timer.h>
+#include <osmocom/core/sockaddr_str.h>
+#include <osmocom/mslookup/mslookup.h>
+
+struct osmo_mslookup_client;
+struct osmo_mslookup_result;
+
+typedef void (*osmo_mslookup_cb_t)(struct osmo_mslookup_client *client,
+				   uint32_t request_handle,
+				   const struct osmo_mslookup_query *query,
+				   const struct osmo_mslookup_result *result);
+
+/*! This handling information is passed along with a lookup request.
+ * It tells the osmo_mslookup_client layer how to handle responses received from various mslookup methods (at the time
+ * of writing only mDNS exists as a method, but the intention is to easily allow adding other methods in the future).
+ * This query handling info is not seen by the individual method implementations, to clarify that it is the
+ * osmo_mslookup_client layer that takes care of these details. */
+struct osmo_mslookup_query_handling {
+	/*! Wait at least this long before returning any results.
+	 *
+	 * If nonzero, result_cb will be called as soon as this delay has elapsed, either with the so far youngest age
+	 * result, or with a "not found yet" result. After this delay has elapsed, receiving results will continue
+	 * until result_timeout_milliseconds has elapsed.
+	 *
+	 * If zero, responses are fed to the result_cb right from the start, every time a younger aged result than
+	 * before comes in.
+	 *
+	 * If a result with age == 0 is received, min_wait_milliseconds is ignored, the result is returned immediately
+	 * and listening for responses ends.
+	 *
+	 * Rationale: If a subscriber has recently moved between sites, multiple results will arrive, and the youngest
+	 * age wins. It can make sense to wait a minimum time for responses before determining the winning result.
+	 *
+	 * However, if no result or no valid result has arrived within a short period, the subscriber may be at a site
+	 * that is far away or that is currently experiencing high latency. It is thus a good safety net to still
+	 * receive results for an extended period of time.
+	 *
+	 * For some services, it is possible to establish links to every received result, and whichever link succeeds
+	 * will be used (for example for SIP calls: first to pick up the call gets connected, the others are dropped
+	 * silently).
+	 */
+	uint32_t min_wait_milliseconds;
+
+	/*! Total time in milliseconds to listen for lookup responses.
+	 *
+	 * When this timeout elapses, osmo_mslookup_client_request_cancel() is called implicitly; Manually invoking
+	 * osmo_mslookup_client_request_cancel() after result_timeout_milliseconds has elapsed is not necessary, but is
+	 * still safe to do anyway.
+	 *
+	 * If zero, min_wait_milliseconds is also used as result_timeout_milliseconds; if that is also zero, a default
+	 * timeout value is used.
+	 *
+	 * If result_timeout_milliseconds <= min_wait_milliseconds, then min_wait_milliseconds is used as
+	 * result_timeout_milliseconds, i.e. the timeout triggers as soon as min_wait_milliseconds hits.
+	 *
+	 * osmo_mslookup_client_request_cancel() can be called any time to end the request.
+	 */
+	uint32_t result_timeout_milliseconds;
+
+	/*! Invoked every time a result with a younger age than the previous result has arrived.
+	 * To stop receiving results before result_timeout_milliseconds has elapsed, call
+	 * osmo_mslookup_client_request_cancel().
+	 */
+	osmo_mslookup_cb_t result_cb;
+};
+
+uint32_t osmo_mslookup_client_request(struct osmo_mslookup_client *client,
+				      const struct osmo_mslookup_query *query,
+				      const struct osmo_mslookup_query_handling *handling);
+
+void osmo_mslookup_client_request_cancel(struct osmo_mslookup_client *client, uint32_t request_handle);
+
+struct osmo_mslookup_client *osmo_mslookup_client_new(void *ctx);
+bool osmo_mslookup_client_active(struct osmo_mslookup_client *client);
+void osmo_mslookup_client_free(struct osmo_mslookup_client *client);
+
+/*! Describe a specific mslookup client method implementation. This struct is only useful for a lookup method
+ * implementation to add itself to an osmo_mslookup_client, see for example osmo_mslookup_client_add_mdns(). */
+struct osmo_mslookup_client_method {
+	struct llist_head entry;
+
+	/*! Human readable name of this lookup method. */
+	const char *name;
+
+	/*! Private data for the lookup method implementation. */
+	void *priv;
+
+	/*! Backpointer to the client this method is added to. */
+	struct osmo_mslookup_client *client;
+
+	/*! Launch a lookup query. Called from osmo_mslookup_client_request().
+	 * The implementation returns results by calling osmo_mslookup_client_rx_result(). */
+	void (*request)(struct osmo_mslookup_client_method *method,
+			const struct osmo_mslookup_query *query,
+			uint32_t request_handle);
+	/*! End a lookup query. Called from osmo_mslookup_client_request_cancel(). It is guaranteed to be called
+	 * exactly once per above request() invocation. (The API user is required to invoke
+	 * osmo_mslookup_client_request_cancel() exactly once per osmo_mslookup_client_request().) */
+	void (*request_cleanup)(struct osmo_mslookup_client_method *method,
+				uint32_t request_handle);
+
+	/*! The mslookup_client is removing this method, clean up all open requests, lists and allocations. */
+	void (*destruct)(struct osmo_mslookup_client_method *method);
+};
+
+void osmo_mslookup_client_method_add(struct osmo_mslookup_client *client,
+				     struct osmo_mslookup_client_method *method);
+bool osmo_mslookup_client_method_del(struct osmo_mslookup_client *client,
+				     struct osmo_mslookup_client_method *method);
+void osmo_mslookup_client_rx_result(struct osmo_mslookup_client *client, uint32_t request_handle,
+				    const struct osmo_mslookup_result *result);

include/osmocom/mslookup/mslookup_client_fake.h

@@ -0,0 +1,34 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+/*! MS lookup fake API for testing purposes. */
+#include <osmocom/mslookup/mslookup_client.h>
+
+struct osmo_mslookup_fake_response {
+	struct timeval time_to_reply;
+	struct osmo_mslookup_id for_id;
+	const char *for_service;
+	struct osmo_mslookup_result result;
+	bool sent;
+};
+
+struct osmo_mslookup_client_method *osmo_mslookup_client_add_fake(struct osmo_mslookup_client *client,
+								  struct osmo_mslookup_fake_response *responses,
+								  size_t responses_len);

include/osmocom/mslookup/mslookup_client_mdns.h

@@ -0,0 +1,38 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+struct osmo_mslookup_client;
+struct osmo_mslookup_client_method;
+
+/*! MS Lookup mDNS server bind default IP. Taken from the Administratevly Scoped block, particularly the Organizational
+ * Scoped range, https://tools.ietf.org/html/rfc2365 . */
+#define OSMO_MSLOOKUP_MDNS_IP4 "239.192.23.42"
+#define OSMO_MSLOOKUP_MDNS_IP6 "ff08::23:42" // <-- TODO: sane?
+#define OSMO_MSLOOKUP_MDNS_PORT 4266
+
+struct osmo_mslookup_client_method *osmo_mslookup_client_add_mdns(struct osmo_mslookup_client *client, const char *ip,
+								  uint16_t port, int initial_packet_id,
+								  const char *domain_suffix);
+
+const struct osmo_sockaddr_str *osmo_mslookup_client_method_mdns_get_bind_addr(struct osmo_mslookup_client_method *dns_method);
+
+const char *osmo_mslookup_client_method_mdns_get_domain_suffix(struct osmo_mslookup_client_method *dns_method);

libosmo-mslookup.pc.in

@@ -0,0 +1,11 @@
+prefix=@prefix@
+exec_prefix=@exec_prefix@
+libdir=@libdir@
+includedir=@includedir@
+
+Name: Osmocom MS Lookup Library
+Description: C Utility Library
+Version: @VERSION@
+Libs: -L${libdir} @TALLOC_LIBS@ -losmogsm -losmo-mslookup -losmocore
+Cflags: -I${includedir}/
+

sql/hlr.sql

@@ -43,7 +43,12 @@ CREATE TABLE subscriber (
 	-- Timestamp of last location update seen from subscriber
 	-- The value is a string which encodes a UTC timestamp in granularity of seconds.
 	last_lu_seen TIMESTAMP default NULL,
-	last_lu_seen_ps TIMESTAMP default NULL
+	last_lu_seen_ps TIMESTAMP default NULL,
+
+	-- When a LU was received via a proxy, that proxy's hlr_number is stored here,
+	-- while vlr_number reflects the MSC on the far side of that proxy.
+	vlr_via_proxy	VARCHAR,
+	sgsn_via_proxy	VARCHAR
 );
 
 CREATE TABLE subscriber_apn (
@@ -74,8 +79,37 @@ CREATE TABLE auc_3g (
 	ind_bitlen	INTEGER NOT NULL DEFAULT 5
 );
 
+CREATE TABLE ind (
+	-- 3G auth IND pool to be used for this VLR
+	ind     INTEGER PRIMARY KEY,
+	-- VLR identification, usually the GSUP source_name
+	vlr     TEXT NOT NULL,
+	UNIQUE (vlr)
+);
+
+CREATE TABLE proxy_auth_cache {
+	id	INTEGER PRIMARY KEY,
+	vlr	TEXT NOT NULL,
+	imsi	TEXT NOT NULL,
+	sent_count INTEGER
+};
+
+CREATE TABLE proxy_auth_cache_vector {
+	-- belongs to this proxy_auth_cache entry
+	proxy_auth_cache_id INTEGER,
+	rand	VARCHAR(32),
+	autn	VARCHAR(32),
+	ck	VARCHAR(32),
+	ik	VARCHAR(32),
+	res	VARCHAR(32),
+	kc[8]	VARCHAR(16),
+	sres[4]	VARCHAR(8),
+	-- enum osmo_sub_auth_type bitmask
+	auth_types INTEGER
+};
+
 CREATE UNIQUE INDEX idx_subscr_imsi ON subscriber (imsi);
 
 -- Set HLR database schema version number
 -- Note: This constant is currently duplicated in src/db.c and must be kept in sync!
-PRAGMA user_version = 4;
+PRAGMA user_version = 6;

src/Makefile.am

@@ -1,4 +1,7 @@
-SUBDIRS = gsupclient
+SUBDIRS = \
+	gsupclient \
+	mslookup \
+	$(NULL)
 
 AM_CFLAGS = \
 	-Wall \
@@ -6,6 +9,7 @@ AM_CFLAGS = \
 	$(LIBOSMOGSM_CFLAGS) \
 	$(LIBOSMOVTY_CFLAGS) \
 	$(LIBOSMOCTRL_CFLAGS) \
+	$(LIBOSMOMSLOOKUP_CFLAGS) \
 	$(LIBOSMOABIS_CFLAGS) \
 	$(SQLITE3_CFLAGS) \
 	$(NULL)
@@ -38,7 +42,6 @@ osmo_hlr_SOURCES = \
 	auc.c \
 	ctrl.c \
 	db.c \
-	luop.c \
 	db_auc.c \
 	db_hlr.c \
 	gsup_router.c \
@@ -50,13 +53,27 @@ osmo_hlr_SOURCES = \
 	hlr_vty_subscr.c \
 	gsup_send.c \
 	hlr_ussd.c \
+	proxy.c \
+	proxy_mm.c \
+	proxy_to_home.c \
+	proxy_db.c \
+	dgsm.c \
+	remote_hlr.c \
+	lu_fsm.c \
+	timestamp.c \
+	mslookup_server.c \
+	mslookup_server_mdns.c \
+	dgsm_vty.c \
 	$(NULL)
 
 osmo_hlr_LDADD = \
+	$(top_builddir)/src/gsupclient/libosmo-gsup-client.la \
+	$(top_builddir)/src/mslookup/libosmo-mslookup.la \
 	$(LIBOSMOCORE_LIBS) \
 	$(LIBOSMOGSM_LIBS) \
 	$(LIBOSMOVTY_LIBS) \
 	$(LIBOSMOCTRL_LIBS) \
+	$(LIBOSMOMSLOOKUP_LIBS) \
 	$(LIBOSMOABIS_LIBS) \
 	$(SQLITE3_LIBS) \
 	$(NULL)
@@ -68,6 +85,7 @@ osmo_hlr_db_tool_SOURCES = \
 	logging.c \
 	rand_urandom.c \
 	dbd_decode_binary.c \
+	$(srcdir)/gsupclient/gsup_peer_id.c \
 	$(NULL)
 
 osmo_hlr_db_tool_LDADD = \

src/db.c

@@ -28,7 +28,7 @@
 #include "db_bootstrap.h"
 
 /* This constant is currently duplicated in sql/hlr.sql and must be kept in sync! */
-#define CURRENT_SCHEMA_VERSION	4
+#define CURRENT_SCHEMA_VERSION	6
 
 #define SEL_COLUMNS \
 	"id," \
@@ -46,15 +46,17 @@
 	"ms_purged_cs," \
 	"ms_purged_ps," \
 	"last_lu_seen," \
-	"last_lu_seen_ps" \
+	"last_lu_seen_ps," \
+	"vlr_via_proxy," \
+	"sgsn_via_proxy"
 
 static const char *stmt_sql[] = {
 	[DB_STMT_SEL_BY_IMSI] = "SELECT " SEL_COLUMNS " FROM subscriber WHERE imsi = ?",
 	[DB_STMT_SEL_BY_MSISDN] = "SELECT " SEL_COLUMNS " FROM subscriber WHERE msisdn = ?",
 	[DB_STMT_SEL_BY_ID] = "SELECT " SEL_COLUMNS " FROM subscriber WHERE id = ?",
 	[DB_STMT_SEL_BY_IMEI] = "SELECT " SEL_COLUMNS " FROM subscriber WHERE imei = ?",
-	[DB_STMT_UPD_VLR_BY_ID] = "UPDATE subscriber SET vlr_number = $number WHERE id = $subscriber_id",
-	[DB_STMT_UPD_SGSN_BY_ID] = "UPDATE subscriber SET sgsn_number = $number WHERE id = $subscriber_id",
+	[DB_STMT_UPD_VLR_BY_ID] = "UPDATE subscriber SET vlr_number = $number, vlr_via_proxy = $proxy WHERE id = $subscriber_id",
+	[DB_STMT_UPD_SGSN_BY_ID] = "UPDATE subscriber SET sgsn_number = $number, sgsn_via_proxy = $proxy WHERE id = $subscriber_id",
 	[DB_STMT_UPD_IMEI_BY_IMSI] = "UPDATE subscriber SET imei = $imei WHERE imsi = $imsi",
 	[DB_STMT_AUC_BY_IMSI] =
 		"SELECT id, algo_id_2g, ki, algo_id_3g, k, op, opc, sqn, ind_bitlen"
@@ -83,6 +85,9 @@ static const char *stmt_sql[] = {
 	[DB_STMT_SET_LAST_LU_SEEN_PS] = "UPDATE subscriber SET last_lu_seen_ps = datetime($val, 'unixepoch') WHERE id = $subscriber_id",
 	[DB_STMT_EXISTS_BY_IMSI] = "SELECT 1 FROM subscriber WHERE imsi = $imsi",
 	[DB_STMT_EXISTS_BY_MSISDN] = "SELECT 1 FROM subscriber WHERE msisdn = $msisdn",
+	[DB_STMT_IND_ADD] = "INSERT INTO ind (vlr) VALUES ($vlr)",
+	[DB_STMT_IND_SELECT] = "SELECT ind FROM ind WHERE vlr = $vlr",
+	[DB_STMT_IND_DEL] = "DELETE FROM ind WHERE vlr = $vlr",
 };
 
 static void sql3_error_log_cb(void *arg, int err_code, const char *msg)
@@ -183,6 +188,25 @@ bool db_bind_int64(sqlite3_stmt *stmt, const char *param_name, int64_t nr)
 	return true;
 }
 
+bool db_bind_null(sqlite3_stmt *stmt, const char *param_name)
+{
+	int rc;
+	int idx = param_name ? sqlite3_bind_parameter_index(stmt, param_name) : 1;
+	if (idx < 1) {
+		LOGP(DDB, LOGL_ERROR, "Error composing SQL, cannot bind parameter '%s'\n",
+		     param_name);
+		return false;
+	}
+	rc = sqlite3_bind_null(stmt, idx);
+	if (rc != SQLITE_OK) {
+		LOGP(DDB, LOGL_ERROR, "Error binding NULL to SQL parameter %s: %d\n",
+		     param_name ? param_name : "#1", rc);
+		db_remove_reset(stmt);
+		return false;
+	}
+	return true;
+}
+
 void db_close(struct db_context *dbc)
 {
 	unsigned int i;
@@ -441,12 +465,54 @@ static int db_upgrade_v4(struct db_context *dbc)
 	return rc;
 }
 
+static int db_upgrade_v5(struct db_context *dbc)
+{
+	int rc;
+	const char *statements[] = {
+		"ALTER TABLE subscriber ADD COLUMN vlr_via_proxy VARCHAR",
+		"ALTER TABLE subscriber ADD COLUMN sgsn_via_proxy VARCHAR",
+		"PRAGMA user_version = 5",
+	};
+
+	rc = db_run_statements(dbc, statements, ARRAY_SIZE(statements));
+	if (rc != SQLITE_DONE) {
+		LOGP(DDB, LOGL_ERROR, "Unable to update HLR database schema to version 5\n");
+		return rc;
+	}
+	return rc;
+}
+
+static int db_upgrade_v6(struct db_context *dbc)
+{
+	int rc;
+	const char *statements[] = {
+		"CREATE TABLE ind (\n"
+		"	-- 3G auth IND pool to be used for this VLR\n"
+		"	ind     INTEGER PRIMARY KEY,\n"
+		"	-- VLR identification, usually the GSUP source_name\n"
+		"	vlr     TEXT NOT NULL,\n"
+		"	UNIQUE (vlr)\n"
+		")"
+		,
+		"PRAGMA user_version = 6",
+	};
+
+	rc = db_run_statements(dbc, statements, ARRAY_SIZE(statements));
+	if (rc != SQLITE_DONE) {
+		LOGP(DDB, LOGL_ERROR, "Unable to update HLR database schema to version 6\n");
+		return rc;
+	}
+	return rc;
+}
+
 typedef int (*db_upgrade_func_t)(struct db_context *dbc);
 static db_upgrade_func_t db_upgrade_path[] = {
 	db_upgrade_v1,
 	db_upgrade_v2,
 	db_upgrade_v3,
 	db_upgrade_v4,
+	db_upgrade_v5,
+	db_upgrade_v6,
 };
 
 static int db_get_user_version(struct db_context *dbc)
@@ -535,9 +601,11 @@ struct db_context *db_open(void *ctx, const char *fname, bool enable_sqlite_logg
 
 	char *err_msg;
 	rc = sqlite3_exec(dbc->db, "PRAGMA journal_mode=WAL; PRAGMA synchonous = NORMAL;", 0, 0, &err_msg);
-	if (rc != SQLITE_OK)
+	if (rc != SQLITE_OK) {
 		LOGP(DDB, LOGL_ERROR, "Unable to set Write-Ahead Logging: %s\n",
 			err_msg);
+		sqlite3_free(err_msg);
+	}
 
 	version = db_get_user_version(dbc);
 	if (version < 0) {

src/db_auc.c

@@ -200,15 +200,16 @@ int db_get_auc(struct db_context *dbc, const char *imsi,
 	if (rc)
 		return rc;
 
+	/* modulo by the IND bitlen value range. For example, ind_bitlen == 5 would modulo 32:
+	 * 1 << 5 == 0b0100000 == 32
+	 * - 1 == 0b0011111 == bitmask of 5 lowest bits
+	 * x &= 0b0011111 == modulo 32
+	 * Why do this? osmo-hlr cannot possibly choose individual VLR INDs always matching all subscribers' IND_bitlen,
+	 * which might vary wildly. Instead, let hlr.c pass in an arbitrarily high number here, and the modulo does a
+	 * round-robin if the IND pools that this subscriber has available. */
+	auc_3g_ind &= (1U << aud3g.u.umts.ind_bitlen) - 1;
 	aud3g.u.umts.ind = auc_3g_ind;
-	if (aud3g.type == OSMO_AUTH_TYPE_UMTS
-	    && aud3g.u.umts.ind >= (1U << aud3g.u.umts.ind_bitlen)) {
-		LOGAUC(imsi, LOGL_NOTICE, "3G auth: SQN's IND bitlen %u is"
-		       " too small to hold an index of %u. Truncating. This"
-		       " may cause numerous additional AUTS resyncing.\n",
-		       aud3g.u.umts.ind_bitlen, aud3g.u.umts.ind);
-		aud3g.u.umts.ind &= (1U << aud3g.u.umts.ind_bitlen) - 1;
-	}
+
 	/* the first bit (bit0) cannot be used as AMF anymore, but has been
 	 * re-appropriated as the separation bit.  See 3GPP TS 33.102 Annex H
 	 * together with 3GPP TS 33.401 / 33.402 / 33.501 */

src/db_hlr.c

@@ -28,6 +28,7 @@
 #include <time.h>
 
 #include <osmocom/core/utils.h>
+#include <osmocom/core/timer.h>
 #include <osmocom/crypt/auth.h>
 #include <osmocom/gsm/gsm23003.h>
 
@@ -36,8 +37,7 @@
 #include <osmocom/hlr/logging.h>
 #include <osmocom/hlr/hlr.h>
 #include <osmocom/hlr/db.h>
-#include <osmocom/hlr/gsup_server.h>
-#include <osmocom/hlr/luop.h>
+#include <osmocom/gsupclient/gsup_peer_id.h>
 
 #define LOGHLR(imsi, level, fmt, args ...)	LOGP(DAUC, level, "IMSI='%s': " fmt, imsi, ## args)
 
@@ -505,6 +505,8 @@ static int db_sel(struct db_context *dbc, sqlite3_stmt *stmt, struct hlr_subscri
 			   subscr->imsi, "CS");
 	parse_last_lu_seen(&subscr->last_lu_seen_ps, (const char *)sqlite3_column_text(stmt, 15),
 			   subscr->imsi, "PS");
+	copy_sqlite3_text_to_ipa_name(&subscr->vlr_via_proxy, stmt, 16);
+	copy_sqlite3_text_to_ipa_name(&subscr->sgsn_via_proxy, stmt, 17);
 
 out:
 	db_remove_reset(stmt);
@@ -566,7 +568,7 @@ int db_subscr_get_by_imsi(struct db_context *dbc, const char *imsi,
 		return -EIO;
 
 	rc = db_sel(dbc, stmt, subscr, &err);
-	if (rc)
+	if (rc && rc != -ENOENT)
 		LOGP(DAUC, LOGL_ERROR, "Cannot read subscriber from db: IMSI='%s': %s\n",
 		     imsi, err);
 	return rc;
@@ -617,7 +619,7 @@ int db_subscr_get_by_msisdn(struct db_context *dbc, const char *msisdn,
 		return -EIO;
 
 	rc = db_sel(dbc, stmt, subscr, &err);
-	if (rc)
+	if (rc && rc != -ENOENT)
 		LOGP(DAUC, LOGL_ERROR, "Cannot read subscriber from db: MSISDN='%s': %s\n",
 		     msisdn, err);
 	return rc;
@@ -641,7 +643,7 @@ int db_subscr_get_by_id(struct db_context *dbc, int64_t id,
 		return -EIO;
 
 	rc = db_sel(dbc, stmt, subscr, &err);
-	if (rc)
+	if (rc && rc != -ENOENT)
 		LOGP(DAUC, LOGL_ERROR, "Cannot read subscriber from db: ID=%" PRId64 ": %s\n",
 		     id, err);
 	return rc;
@@ -664,7 +666,7 @@ int db_subscr_get_by_imei(struct db_context *dbc, const char *imei, struct hlr_s
 		return -EIO;
 
 	rc = db_sel(dbc, stmt, subscr, &err);
-	if (rc)
+	if (rc && rc != -ENOENT)
 		LOGP(DAUC, LOGL_ERROR, "Cannot read subscriber from db: IMEI=%s: %s\n", imei, err);
 	return rc;
 }
@@ -734,7 +736,8 @@ out:
  *         -EIO on database errors.
  */
 int db_subscr_lu(struct db_context *dbc, int64_t subscr_id,
-		 const char *vlr_or_sgsn_number, bool is_ps)
+		 const struct osmo_ipa_name *vlr_name, bool is_ps,
+		 const struct osmo_ipa_name *via_proxy)
 {
 	sqlite3_stmt *stmt;
 	int rc, ret = 0;
@@ -746,9 +749,17 @@ int db_subscr_lu(struct db_context *dbc, int64_t subscr_id,
 	if (!db_bind_int64(stmt, "$subscriber_id", subscr_id))
 		return -EIO;
 
-	if (!db_bind_text(stmt, "$number", vlr_or_sgsn_number))
+	if (!db_bind_text(stmt, "$number", (char*)vlr_name->val))
 		return -EIO;
 
+	if (via_proxy && via_proxy->len) {
+		if (!db_bind_text(stmt, "$proxy", (char*)via_proxy->val))
+			return -EIO;
+	} else {
+		if (!db_bind_null(stmt, "$proxy"))
+			return -EIO;
+	}
+
 	/* execute the statement */
 	rc = sqlite3_step(stmt);
 	if (rc != SQLITE_DONE) {
@@ -874,50 +885,105 @@ out:
 	return ret;
 }
 
-/*! Update nam_cs/nam_ps in the db and trigger notifications to GSUP clients.
- * \param[in,out] hlr  Global hlr context.
- * \param[in] subscr   Subscriber from a fresh db_subscr_get_by_*() call.
- * \param[in] nam_val  True to enable CS/PS, false to disable.
- * \param[in] is_ps    True to enable/disable PS, false for CS.
- * \returns 0 on success, ENOEXEC if there is no need to change, a negative
- *          value on error.
- */
-int hlr_subscr_nam(struct hlr *hlr, struct hlr_subscriber *subscr, bool nam_val, bool is_ps)
+static int _db_ind_run(struct db_context *dbc, sqlite3_stmt *stmt, const char *vlr, bool reset)
 {
 	int rc;
-        struct lu_operation *luop;
-        struct osmo_gsup_conn *co;
-	bool is_val = is_ps? subscr->nam_ps : subscr->nam_cs;
 
-	if (is_val == nam_val) {
-		LOGHLR(subscr->imsi, LOGL_DEBUG, "Already has the requested value when asked to %s %s\n",
-		       nam_val ? "enable" : "disable", is_ps ? "PS" : "CS");
-		return ENOEXEC;
-	}
+	if (!db_bind_text(stmt, "$vlr", vlr))
+		return -EIO;
 
-	rc = db_subscr_nam(hlr->dbc, subscr->imsi, nam_val, is_ps);
-	if (rc)
-		return rc > 0? -rc : rc;
+	/* execute the statement */
+	rc = sqlite3_step(stmt);
+	if (reset)
+		db_remove_reset(stmt);
+	return rc;
+}
 
-	/* If we're disabling, send a notice out to the GSUP client that is
-	 * responsible. Otherwise no need. */
-	if (nam_val)
-		return 0;
-
-	/* FIXME: only send to single SGSN where latest update for IMSI came from */
-	llist_for_each_entry(co, &hlr->gs->clients, list) {
-		luop = lu_op_alloc_conn(co);
-		if (!luop) {
-			LOGHLR(subscr->imsi, LOGL_ERROR,
-			       "Cannot notify GSUP client, cannot allocate lu_operation,"
-			       " for %s:%u\n",
-			       co && co->conn && co->conn->server? co->conn->server->addr : "unset",
-			       co && co->conn && co->conn->server? co->conn->server->port : 0);
-			continue;
-		}
-		luop->subscr = *subscr;
-		lu_op_tx_del_subscr_data(luop);
-		lu_op_free(luop);
+static int _db_ind_add(struct db_context *dbc, const char *vlr)
+{
+	sqlite3_stmt *stmt = dbc->stmt[DB_STMT_IND_ADD];
+	if (_db_ind_run(dbc, stmt, vlr, true) != SQLITE_DONE) {
+		LOGP(DDB, LOGL_ERROR, "Cannot create IND entry for %s\n", osmo_quote_str_c(OTC_SELECT, vlr, -1));
+		return -EIO;
 	}
 	return 0;
 }
+
+static int _db_ind_del(struct db_context *dbc, const char *vlr)
+{
+	sqlite3_stmt *stmt = dbc->stmt[DB_STMT_IND_DEL];
+	_db_ind_run(dbc, stmt, vlr, true);
+	/* We don't really care about the result. If it didn't exist, then that was the goal anyway. */
+	return 0;
+}
+
+static int _db_ind_get(struct db_context *dbc, const char *vlr, unsigned int *ind)
+{
+	int ret = 0;
+	sqlite3_stmt *stmt = dbc->stmt[DB_STMT_IND_SELECT];
+	int rc = _db_ind_run(dbc, stmt, vlr, false);
+	if (rc == SQLITE_DONE) {
+		/* Does not exist yet */
+		ret = -ENOENT;
+		goto out;
+	} else if (rc != SQLITE_ROW) {
+		LOGP(DDB, LOGL_ERROR, "Error executing SQL: %d\n", rc);
+		ret = -EIO;
+		goto out;
+	}
+
+	OSMO_ASSERT(ind);
+	*ind = sqlite3_column_int64(stmt, 0);
+out:
+	db_remove_reset(stmt);
+	return ret;
+}
+
+int _db_ind(struct db_context *dbc, const struct osmo_gsup_peer_id *vlr,
+	    unsigned int *ind, bool del)
+{
+	const char *vlr_name = NULL;
+	int rc;
+
+	switch (vlr->type) {
+	case OSMO_GSUP_PEER_ID_IPA_NAME:
+		if (vlr->ipa_name.len < 2 || vlr->ipa_name.val[vlr->ipa_name.len - 1] != '\0') {
+			LOGP(DDB, LOGL_ERROR, "Expecting VLR ipa_name to be zero terminated; found %s\n",
+			     osmo_ipa_name_to_str(&vlr->ipa_name));
+			return -ENOTSUP;
+		}
+		vlr_name = (const char*)vlr->ipa_name.val;
+		break;
+	default:
+		LOGP(DDB, LOGL_ERROR, "Unsupported osmo_gsup_peer_id type: %s\n",
+		     osmo_gsup_peer_id_type_name(vlr->type));
+		return -ENOTSUP;
+	}
+
+	if (del)
+		return _db_ind_del(dbc, vlr_name);
+
+	rc = _db_ind_get(dbc, vlr_name, ind);
+	if (!rc)
+		return 0;
+
+	/* Does not exist yet, create. */
+	rc = _db_ind_add(dbc, vlr_name);
+	if (rc) {
+		LOGP(DDB, LOGL_ERROR, "Error creating IND entry for %s\n", osmo_quote_str_c(OTC_SELECT, vlr_name, -1));
+		return rc;
+	}
+
+	/* To be sure, query again from scratch. */
+	return _db_ind_get(dbc, vlr_name, ind);
+}
+
+int db_ind(struct db_context *dbc, const struct osmo_gsup_peer_id *vlr, unsigned int *ind)
+{
+	return _db_ind(dbc, vlr, ind, false);
+}
+
+int db_ind_del(struct db_context *dbc, const struct osmo_gsup_peer_id *vlr)
+{
+	return _db_ind(dbc, vlr, NULL, true);
+}

src/dgsm.c

@@ -0,0 +1,247 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <errno.h>
+#include <osmocom/core/logging.h>
+#include <osmocom/mslookup/mslookup_client.h>
+#include <osmocom/mslookup/mslookup_client_mdns.h>
+#include <osmocom/gsupclient/gsup_client.h>
+#include <osmocom/gsupclient/gsup_peer_id.h>
+#include <osmocom/hlr/logging.h>
+#include <osmocom/hlr/hlr.h>
+#include <osmocom/hlr/db.h>
+#include <osmocom/hlr/gsup_router.h>
+#include <osmocom/hlr/gsup_server.h>
+#include <osmocom/hlr/dgsm.h>
+#include <osmocom/hlr/proxy.h>
+#include <osmocom/hlr/remote_hlr.h>
+#include <osmocom/hlr/mslookup_server.h>
+#include <osmocom/hlr/mslookup_server_mdns.h>
+#include <osmocom/hlr/dgsm.h>
+
+void *dgsm_ctx = NULL;
+
+static void resolve_hlr_result_cb(struct osmo_mslookup_client *client,
+				  uint32_t request_handle,
+				  const struct osmo_mslookup_query *query,
+				  const struct osmo_mslookup_result *result)
+{
+	struct proxy *proxy = g_hlr->gs->proxy;
+	struct proxy_subscr proxy_subscr;
+	const struct osmo_sockaddr_str *remote_hlr_addr;
+
+	/* A remote HLR is answering back, indicating that it is the home HLR for a given IMSI.
+	 * There should be a mostly empty proxy entry for that IMSI.
+	 * Add the remote address data in the proxy. */
+	if (query->id.type != OSMO_MSLOOKUP_ID_IMSI) {
+		LOGP(DDGSM, LOGL_ERROR, "Expected IMSI ID type in mslookup query+result: %s\n",
+		     osmo_mslookup_result_name_c(OTC_SELECT, query, result));
+		return;
+	}
+
+	if (result->rc != OSMO_MSLOOKUP_RC_RESULT) {
+		LOG_DGSM(query->id.imsi, LOGL_ERROR, "Failed to resolve remote HLR: %s\n",
+			 osmo_mslookup_result_name_c(OTC_SELECT, query, result));
+		proxy_subscr_del(proxy, query->id.imsi);
+		return;
+	}
+
+	if (osmo_sockaddr_str_is_nonzero(&result->host_v4))
+		remote_hlr_addr = &result->host_v4;
+	else if (osmo_sockaddr_str_is_nonzero(&result->host_v6))
+		remote_hlr_addr = &result->host_v6;
+	else {
+		LOG_DGSM(query->id.imsi, LOGL_ERROR, "Invalid address for remote HLR: %s\n",
+			 osmo_mslookup_result_name_c(OTC_SELECT, query, result));
+		proxy_subscr_del(proxy, query->id.imsi);
+		return;
+	}
+
+	if (proxy_subscr_get_by_imsi(&proxy_subscr, proxy, query->id.imsi)) {
+		LOG_DGSM(query->id.imsi, LOGL_ERROR, "No proxy entry for mslookup result: %s\n",
+			 osmo_mslookup_result_name_c(OTC_SELECT, query, result));
+		return;
+	}
+
+	proxy_subscr_remote_hlr_resolved(proxy, &proxy_subscr, remote_hlr_addr);
+}
+
+/* Return true when the message has been handled by D-GSM. */
+bool dgsm_check_forward_gsup_msg(struct osmo_gsup_req *req)
+{
+	struct proxy_subscr proxy_subscr;
+	struct proxy *proxy = g_hlr->gs->proxy;
+	struct osmo_mslookup_query query;
+	struct osmo_mslookup_query_handling handling;
+	uint32_t request_handle;
+
+	/* If the IMSI is known in the local HLR, then we won't proxy. */
+	if (db_subscr_exists_by_imsi(g_hlr->dbc, req->gsup.imsi) == 0)
+		return false;
+
+	/* Are we already forwarding this IMSI to a remote HLR? */
+	if (proxy_subscr_get_by_imsi(&proxy_subscr, proxy, req->gsup.imsi) == 0) {
+		proxy_subscr_forward_to_remote_hlr(proxy, &proxy_subscr, req);
+		return true;
+	}
+
+	/* The IMSI is not known locally, so we want to proxy to a remote HLR, but no proxy entry exists yet. We need to
+	 * look up the subscriber in remote HLRs via D-GSM mslookup, forward GSUP and reply once a result is back from
+	 * there.  Defer message and kick off MS lookup. */
+
+	/* Add a proxy entry without a remote address to indicate that we are busy querying for a remote HLR. */
+	proxy_subscr = (struct proxy_subscr){};
+	OSMO_STRLCPY_ARRAY(proxy_subscr.imsi, req->gsup.imsi);
+	if (proxy_subscr_create_or_update(proxy, &proxy_subscr)) {
+		osmo_gsup_req_respond_err(req, GMM_CAUSE_NET_FAIL, "Failed to create proxy entry\n");
+		return true;
+	}
+
+	/* Is a fixed gateway proxy configured? */
+	if (osmo_sockaddr_str_is_nonzero(&g_hlr->mslookup.client.gsup_gateway_proxy)) {
+		proxy_subscr_remote_hlr_resolved(proxy, &proxy_subscr, &g_hlr->mslookup.client.gsup_gateway_proxy);
+
+		/* Proxy database modified, update info */
+		if (proxy_subscr_get_by_imsi(&proxy_subscr, proxy, req->gsup.imsi)) {
+			osmo_gsup_req_respond_err(req, GMM_CAUSE_NET_FAIL, "Internal proxy error\n");
+			return true;
+		}
+
+		proxy_subscr_forward_to_remote_hlr(proxy, &proxy_subscr, req);
+		return true;
+	}
+
+	/* Kick off an mslookup for the remote HLR?  This check could be up first on the top, but do it only now so that
+	 * if the mslookup client disconnected, we still continue to service open proxy entries. */
+	if (!osmo_mslookup_client_active(g_hlr->mslookup.client.client)) {
+		LOG_GSUP_REQ(req, LOGL_DEBUG, "mslookup client not running, cannot query remote home HLR\n");
+		return false;
+	}
+
+	/* First spool message, then kick off mslookup. If the proxy denies this message type, then don't do anything. */
+	if (proxy_subscr_forward_to_remote_hlr(proxy, &proxy_subscr, req)) {
+		/* If the proxy denied forwarding, an error response was already generated. */
+		return true;
+	}
+
+	query = (struct osmo_mslookup_query){
+		.id = {
+			.type = OSMO_MSLOOKUP_ID_IMSI,
+		},
+	};
+	OSMO_STRLCPY_ARRAY(query.id.imsi, req->gsup.imsi);
+	OSMO_STRLCPY_ARRAY(query.service, OSMO_MSLOOKUP_SERVICE_HLR_GSUP);
+	handling = (struct osmo_mslookup_query_handling){
+		.min_wait_milliseconds = g_hlr->mslookup.client.result_timeout_milliseconds,
+		.result_cb = resolve_hlr_result_cb,
+	};
+	request_handle = osmo_mslookup_client_request(g_hlr->mslookup.client.client, &query, &handling);
+	if (!request_handle) {
+		LOG_DGSM(req->gsup.imsi, LOGL_ERROR, "Error dispatching mslookup query for home HLR: %s\n",
+			 osmo_mslookup_result_name_c(OTC_SELECT, &query, NULL));
+		proxy_subscr_del(proxy, req->gsup.imsi);
+		/* mslookup seems to not be working. Try handling it locally. */
+		return false;
+	}
+
+	return true;
+}
+
+void dgsm_init(void *ctx)
+{
+	dgsm_ctx = talloc_named_const(ctx, 0, "dgsm");
+	INIT_LLIST_HEAD(&g_hlr->mslookup.server.local_site_services);
+
+	g_hlr->mslookup.server.local_attach_max_age = 60 * 60;
+
+	g_hlr->mslookup.client.result_timeout_milliseconds = 2000;
+
+	g_hlr->gsup_unit_name.unit_name = "HLR";
+	g_hlr->gsup_unit_name.serno = "unnamed-HLR";
+	g_hlr->gsup_unit_name.swversion = PACKAGE_NAME "-" PACKAGE_VERSION;
+
+	osmo_sockaddr_str_from_str(&g_hlr->mslookup.server.mdns.bind_addr,
+				   OSMO_MSLOOKUP_MDNS_IP4, OSMO_MSLOOKUP_MDNS_PORT);
+	osmo_sockaddr_str_from_str(&g_hlr->mslookup.client.mdns.query_addr,
+				   OSMO_MSLOOKUP_MDNS_IP4, OSMO_MSLOOKUP_MDNS_PORT);
+}
+
+void dgsm_start(void *ctx)
+{
+	g_hlr->mslookup.client.client = osmo_mslookup_client_new(dgsm_ctx);
+	OSMO_ASSERT(g_hlr->mslookup.client.client);
+	g_hlr->mslookup.allow_startup = true;
+	mslookup_server_mdns_config_apply();
+	dgsm_mdns_client_config_apply();
+}
+
+void dgsm_stop()
+{
+	g_hlr->mslookup.allow_startup = false;
+	mslookup_server_mdns_config_apply();
+	dgsm_mdns_client_config_apply();
+}
+
+void dgsm_mdns_client_config_apply(void)
+{
+	/* Check whether to start/stop/restart mDNS client */
+	const struct osmo_sockaddr_str *current_bind_addr;
+	const char *current_domain_suffix;
+	current_bind_addr = osmo_mslookup_client_method_mdns_get_bind_addr(g_hlr->mslookup.client.mdns.running);
+	current_domain_suffix = osmo_mslookup_client_method_mdns_get_domain_suffix(g_hlr->mslookup.client.mdns.running);
+
+	bool should_run = g_hlr->mslookup.allow_startup
+		&& g_hlr->mslookup.client.enable && g_hlr->mslookup.client.mdns.enable;
+
+	bool should_stop = g_hlr->mslookup.client.mdns.running &&
+		(!should_run
+		 || osmo_sockaddr_str_cmp(&g_hlr->mslookup.client.mdns.query_addr,
+					  current_bind_addr)
+		 || strcmp(g_hlr->mslookup.client.mdns.domain_suffix,
+			   current_domain_suffix));
+
+	if (should_stop) {
+		osmo_mslookup_client_method_del(g_hlr->mslookup.client.client, g_hlr->mslookup.client.mdns.running);
+		g_hlr->mslookup.client.mdns.running = NULL;
+		LOGP(DDGSM, LOGL_NOTICE, "Stopped mslookup mDNS client\n");
+	}
+
+	if (should_run && !g_hlr->mslookup.client.mdns.running) {
+		g_hlr->mslookup.client.mdns.running =
+			osmo_mslookup_client_add_mdns(g_hlr->mslookup.client.client,
+						      g_hlr->mslookup.client.mdns.query_addr.ip,
+						      g_hlr->mslookup.client.mdns.query_addr.port,
+						      -1,
+						      g_hlr->mslookup.client.mdns.domain_suffix);
+		if (!g_hlr->mslookup.client.mdns.running)
+			LOGP(DDGSM, LOGL_ERROR, "Failed to start mslookup mDNS client with target "
+			     OSMO_SOCKADDR_STR_FMT "\n",
+			     OSMO_SOCKADDR_STR_FMT_ARGS(&g_hlr->mslookup.client.mdns.query_addr));
+		else
+			LOGP(DDGSM, LOGL_NOTICE, "Started mslookup mDNS client, sending mDNS requests to multicast "
+			     OSMO_SOCKADDR_STR_FMT "\n",
+			     OSMO_SOCKADDR_STR_FMT_ARGS(&g_hlr->mslookup.client.mdns.query_addr));
+	}
+
+	if (g_hlr->mslookup.client.enable && osmo_sockaddr_str_is_nonzero(&g_hlr->mslookup.client.gsup_gateway_proxy))
+			LOGP(DDGSM, LOGL_NOTICE,
+			     "mslookup client: all GSUP requests for unknown IMSIs will be forwarded to"
+			     " gateway-proxy " OSMO_SOCKADDR_STR_FMT "\n",
+			     OSMO_SOCKADDR_STR_FMT_ARGS(&g_hlr->mslookup.client.gsup_gateway_proxy));
+}

src/dgsm_vty.c

@@ -0,0 +1,580 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <osmocom/vty/vty.h>
+#include <osmocom/vty/command.h>
+#include <osmocom/mslookup/mslookup_client_mdns.h>
+#include <osmocom/mslookup/mdns.h>
+#include <osmocom/hlr/hlr_vty.h>
+#include <osmocom/hlr/mslookup_server.h>
+#include <osmocom/hlr/mslookup_server_mdns.h>
+#include <osmocom/gsupclient/gsup_peer_id.h>
+
+struct cmd_node mslookup_node = {
+	MSLOOKUP_NODE,
+	"%s(config-mslookup)# ",
+	1,
+};
+
+DEFUN(cfg_mslookup,
+      cfg_mslookup_cmd,
+      "mslookup",
+      "Configure Distributed GSM mslookup")
+{
+	vty->node = MSLOOKUP_NODE;
+	return CMD_SUCCESS;
+}
+
+static int mslookup_server_mdns_bind(struct vty *vty, int argc, const char **argv)
+{
+	const char *ip_str = argc > 0? argv[0] : g_hlr->mslookup.server.mdns.bind_addr.ip;
+	const char *port_str = argc > 1? argv[1] : NULL;
+	uint16_t port_nr = port_str ? atoi(port_str) : g_hlr->mslookup.server.mdns.bind_addr.port;
+	struct osmo_sockaddr_str addr;
+	if (osmo_sockaddr_str_from_str(&addr, ip_str, port_nr)
+	    || !osmo_sockaddr_str_is_nonzero(&addr)) {
+		vty_out(vty, "%% mslookup server: Invalid mDNS bind address: %s %u%s",
+			ip_str, port_nr, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	g_hlr->mslookup.server.mdns.bind_addr = addr;
+	g_hlr->mslookup.server.mdns.enable = true;
+	g_hlr->mslookup.server.enable = true;
+	mslookup_server_mdns_config_apply();
+	return CMD_SUCCESS;
+}
+
+static int mslookup_client_mdns_to(struct vty *vty, int argc, const char **argv)
+{
+	const char *ip_str = argc > 0? argv[0] : g_hlr->mslookup.client.mdns.query_addr.ip;
+	const char *port_str = argc > 1? argv[1] : NULL;
+	uint16_t port_nr = port_str ? atoi(port_str) : g_hlr->mslookup.client.mdns.query_addr.port;
+	struct osmo_sockaddr_str addr;
+	if (osmo_sockaddr_str_from_str(&addr, ip_str, port_nr)
+	    || !osmo_sockaddr_str_is_nonzero(&addr)) {
+		vty_out(vty, "%% mslookup client: Invalid mDNS target address: %s %u%s",
+			ip_str, port_nr, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	g_hlr->mslookup.client.mdns.query_addr = addr;
+	g_hlr->mslookup.client.mdns.enable = true;
+	g_hlr->mslookup.client.enable = true;
+	dgsm_mdns_client_config_apply();
+	return CMD_SUCCESS;
+}
+
+#define MDNS_STR "Multicast DNS related configuration\n"
+#define MDNS_IP46_STR "multicast IPv4 address like " OSMO_MSLOOKUP_MDNS_IP4 \
+			" or IPv6 address like " OSMO_MSLOOKUP_MDNS_IP6 "\n"
+#define MDNS_PORT_STR "mDNS UDP Port number\n"
+#define MDNS_DOMAIN_SUFFIX_STR "mDNS domain suffix (default: " OSMO_MDNS_DOMAIN_SUFFIX_DEFAULT "). This is appended" \
+				 " and stripped from mDNS packets during encoding/decoding, so we don't collide with" \
+				 " top-level domains administrated by IANA\n"
+#define IP46_STR "IPv4 address like 1.2.3.4 or IPv6 address like a:b:c:d::1\n"
+#define PORT_STR "Service-specific port number\n"
+
+DEFUN(cfg_mslookup_mdns,
+      cfg_mslookup_mdns_cmd,
+      "mdns bind [IP] [<1-65535>]",
+      MDNS_STR
+      "Convenience shortcut: enable and configure both server and client for mDNS mslookup\n"
+      MDNS_IP46_STR MDNS_PORT_STR)
+{
+	int rc1 = mslookup_server_mdns_bind(vty, argc, argv);
+	int rc2 = mslookup_client_mdns_to(vty, argc, argv);
+	if (rc1 != CMD_SUCCESS)
+		return rc1;
+	return rc2;
+}
+
+DEFUN(cfg_mslookup_mdns_domain_suffix,
+      cfg_mslookup_mdns_domain_suffix_cmd,
+      "mdns domain-suffix DOMAIN_SUFFIX",
+      MDNS_STR MDNS_DOMAIN_SUFFIX_STR MDNS_DOMAIN_SUFFIX_STR)
+{
+	osmo_talloc_replace_string(g_hlr, &g_hlr->mslookup.server.mdns.domain_suffix, argv[0]);
+	osmo_talloc_replace_string(g_hlr, &g_hlr->mslookup.client.mdns.domain_suffix, argv[0]);
+	mslookup_server_mdns_config_apply();
+	dgsm_mdns_client_config_apply();
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_mslookup_no_mdns,
+      cfg_mslookup_no_mdns_cmd,
+      "no mdns bind",
+      NO_STR "Disable both server and client for mDNS mslookup\n")
+{
+	g_hlr->mslookup.server.mdns.enable = false;
+	g_hlr->mslookup.client.mdns.enable = false;
+	mslookup_server_mdns_config_apply();
+	dgsm_mdns_client_config_apply();
+	return CMD_SUCCESS;
+}
+
+struct cmd_node mslookup_server_node = {
+	MSLOOKUP_SERVER_NODE,
+	"%s(config-mslookup-server)# ",
+	1,
+};
+
+DEFUN(cfg_mslookup_server,
+      cfg_mslookup_server_cmd,
+      "server",
+      "Enable and configure Distributed GSM mslookup server")
+{
+	vty->node = MSLOOKUP_SERVER_NODE;
+	g_hlr->mslookup.server.enable = true;
+	mslookup_server_mdns_config_apply();
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_mslookup_no_server,
+      cfg_mslookup_no_server_cmd,
+      "no server",
+      NO_STR "Disable Distributed GSM mslookup server")
+{
+	g_hlr->mslookup.server.enable = false;
+	mslookup_server_mdns_config_apply();
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_mslookup_server_mdns_bind,
+      cfg_mslookup_server_mdns_bind_cmd,
+      "mdns bind [IP] [<1-65535>]",
+      MDNS_STR
+      "Configure where the mDNS server listens for mslookup requests\n"
+      MDNS_IP46_STR MDNS_PORT_STR)
+{
+	return mslookup_server_mdns_bind(vty, argc, argv);
+}
+
+DEFUN(cfg_mslookup_server_mdns_domain_suffix,
+      cfg_mslookup_server_mdns_domain_suffix_cmd,
+      "mdns domain-suffix DOMAIN_SUFFIX",
+      MDNS_STR
+      MDNS_DOMAIN_SUFFIX_STR
+      MDNS_DOMAIN_SUFFIX_STR)
+{
+	osmo_talloc_replace_string(g_hlr, &g_hlr->mslookup.server.mdns.domain_suffix, argv[0]);
+	mslookup_server_mdns_config_apply();
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_mslookup_server_no_mdns_bind,
+      cfg_mslookup_server_no_mdns_bind_cmd,
+      "no mdns bind",
+      NO_STR "Disable server for mDNS mslookup (do not answer remote requests)\n")
+{
+	g_hlr->mslookup.server.mdns.enable = false;
+	mslookup_server_mdns_config_apply();
+	return CMD_SUCCESS;
+}
+
+struct cmd_node mslookup_server_msc_node = {
+	MSLOOKUP_SERVER_MSC_NODE,
+	"%s(config-mslookup-server-msc)# ",
+	1,
+};
+
+DEFUN(cfg_mslookup_server_msc,
+      cfg_mslookup_server_msc_cmd,
+      "msc ipa-name .IPA_NAME",
+      "Configure services for individual local MSCs\n"
+      "Identify locally connected MSC by IPA Unit Name\n"
+      "IPA Unit Name of the local MSC to configure\n")
+{
+	struct osmo_ipa_name msc_name;
+	struct mslookup_server_msc_cfg *msc;
+	osmo_ipa_name_set_str(&msc_name, argv_concat(argv, argc, 0));
+
+	msc = mslookup_server_msc_get(&msc_name, true);
+	if (!msc) {
+		vty_out(vty, "%% Error creating MSC %s%s", osmo_ipa_name_to_str(&msc_name), VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+	vty->node = MSLOOKUP_SERVER_MSC_NODE;
+	vty->index = msc;
+	return CMD_SUCCESS;
+}
+
+#define SERVICE_NAME_STR \
+	"mslookup service name, e.g. sip.voice or smpp.sms\n"
+
+static struct mslookup_server_msc_cfg *msc_from_node(struct vty *vty)
+{
+	switch (vty->node) {
+	case MSLOOKUP_SERVER_NODE:
+		/* On the mslookup.server node, set services on the wildcard msc, without a particular name. */
+		return mslookup_server_msc_get(&mslookup_server_msc_wildcard, true);
+	case MSLOOKUP_SERVER_MSC_NODE:
+		return vty->index;
+	default:
+		return NULL;
+	}
+}
+
+DEFUN(cfg_mslookup_server_msc_service,
+      cfg_mslookup_server_msc_service_cmd,
+      "service NAME at IP <1-65535>",
+      "Configure addresses of local services, as sent in replies to remote mslookup requests.\n"
+      SERVICE_NAME_STR "at\n" IP46_STR PORT_STR)
+{
+	/* If this command is run on the 'server' node, it produces an empty unit name and serves as wildcard for all
+	 * MSCs. If on a 'server' / 'msc' node, set services only for that MSC Unit Name. */
+	struct mslookup_server_msc_cfg *msc = msc_from_node(vty);
+	const char *service = argv[0];
+	const char *ip_str = argv[1];
+	const char *port_str = argv[2];
+	struct osmo_sockaddr_str addr;
+
+	if (!msc) {
+		vty_out(vty, "%% Error: no MSC object on this node%s", VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	if (osmo_sockaddr_str_from_str(&addr, ip_str, atoi(port_str))
+	    || !osmo_sockaddr_str_is_nonzero(&addr)) {
+		vty_out(vty, "%% mslookup server: Invalid address for service %s: %s %s%s",
+			service, ip_str, port_str, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	if (mslookup_server_msc_service_set(msc, service, &addr)) {
+		vty_out(vty, "%% mslookup server: Error setting service %s to %s %s%s",
+			service, ip_str, port_str, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+	return CMD_SUCCESS;
+}
+
+#define NO_SERVICE_AND_NAME_STR NO_STR "Remove one or more service address entries\n" SERVICE_NAME_STR
+
+DEFUN(cfg_mslookup_server_msc_no_service,
+      cfg_mslookup_server_msc_no_service_cmd,
+      "no service NAME",
+      NO_SERVICE_AND_NAME_STR)
+{
+	/* If this command is run on the 'server' node, it produces an empty unit name and serves as wildcard for all
+	 * MSCs. If on a 'server' / 'msc' node, set services only for that MSC Unit Name. */
+	struct mslookup_server_msc_cfg *msc = msc_from_node(vty);
+	const char *service = argv[0];
+
+	if (!msc) {
+		vty_out(vty, "%% Error: no MSC object on this node%s", VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	if (mslookup_server_msc_service_del(msc, service, NULL) < 1) {
+		vty_out(vty, "%% mslookup server: cannot remove service '%s'%s",
+			service, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_mslookup_server_msc_no_service_addr,
+      cfg_mslookup_server_msc_no_service_addr_cmd,
+      "no service NAME at IP <1-65535>",
+      NO_SERVICE_AND_NAME_STR "at\n" IP46_STR PORT_STR)
+{
+	/* If this command is run on the 'server' node, it produces an empty unit name and serves as wildcard for all
+	 * MSCs. If on a 'server' / 'msc' node, set services only for that MSC Unit Name. */
+	struct mslookup_server_msc_cfg *msc = msc_from_node(vty);
+	const char *service = argv[0];
+	const char *ip_str = argv[1];
+	const char *port_str = argv[2];
+	struct osmo_sockaddr_str addr;
+
+	if (!msc) {
+		vty_out(vty, "%% Error: no MSC object on this node%s", VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	if (osmo_sockaddr_str_from_str(&addr, ip_str, atoi(port_str))
+	    || !osmo_sockaddr_str_is_nonzero(&addr)) {
+		vty_out(vty, "%% mslookup server: Invalid address for 'no service' %s: %s %s%s",
+			service, ip_str, port_str, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	if (mslookup_server_msc_service_del(msc, service, &addr) < 1) {
+		vty_out(vty, "%% mslookup server: cannot remove service '%s' to %s %s%s",
+			service, ip_str, port_str, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+	return CMD_SUCCESS;
+}
+
+struct cmd_node mslookup_client_node = {
+	MSLOOKUP_CLIENT_NODE,
+	"%s(config-mslookup-client)# ",
+	1,
+};
+
+DEFUN(cfg_mslookup_client,
+      cfg_mslookup_client_cmd,
+      "client",
+      "Enable and configure Distributed GSM mslookup client")
+{
+	vty->node = MSLOOKUP_CLIENT_NODE;
+	g_hlr->mslookup.client.enable = true;
+	dgsm_mdns_client_config_apply();
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_mslookup_no_client,
+      cfg_mslookup_no_client_cmd,
+      "no client",
+      NO_STR "Disable Distributed GSM mslookup client")
+{
+	g_hlr->mslookup.client.enable = false;
+	dgsm_mdns_client_config_apply();
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_mslookup_client_timeout,
+      cfg_mslookup_client_timeout_cmd,
+      "timeout <1-100000>",
+      "How long should the mslookup client wait for remote responses before evaluating received results\n"
+      "timeout in milliseconds\n")
+{
+	uint32_t val = atol(argv[0]);
+	g_hlr->mslookup.client.result_timeout_milliseconds = val;
+	return CMD_SUCCESS;
+}
+
+#define EXIT_HINT() \
+	if (vty->type != VTY_FILE) \
+		vty_out(vty, "%% 'exit' this node to apply changes%s", VTY_NEWLINE)
+
+
+DEFUN(cfg_mslookup_client_mdns_bind,
+      cfg_mslookup_client_mdns_bind_cmd,
+      "mdns bind [IP] [<1-65535>]",
+      MDNS_STR
+      "Enable mDNS client, and configure multicast address to send mDNS mslookup requests to\n"
+      MDNS_IP46_STR MDNS_PORT_STR)
+{
+	return mslookup_client_mdns_to(vty, argc, argv);
+}
+
+DEFUN(cfg_mslookup_client_mdns_domain_suffix,
+      cfg_mslookup_client_mdns_domain_suffix_cmd,
+      "mdns domain-suffix DOMAIN_SUFFIX",
+      MDNS_STR
+      MDNS_DOMAIN_SUFFIX_STR
+      MDNS_DOMAIN_SUFFIX_STR)
+{
+	osmo_talloc_replace_string(g_hlr, &g_hlr->mslookup.client.mdns.domain_suffix, argv[0]);
+	dgsm_mdns_client_config_apply();
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_mslookup_client_no_mdns_bind,
+      cfg_mslookup_client_no_mdns_bind_cmd,
+      "no mdns bind",
+      NO_STR "Disable mDNS client, do not query remote services by mDNS\n")
+{
+	g_hlr->mslookup.client.mdns.enable = false;
+	dgsm_mdns_client_config_apply();
+	return CMD_SUCCESS;
+}
+
+void config_write_msc_services(struct vty *vty, const char *indent, struct mslookup_server_msc_cfg *msc)
+{
+	struct mslookup_service_host *e;
+
+	llist_for_each_entry(e, &msc->service_hosts, entry) {
+		if (osmo_sockaddr_str_is_nonzero(&e->host_v4))
+			vty_out(vty, "%sservice %s at %s %u%s", indent, e->service, e->host_v4.ip, e->host_v4.port,
+				VTY_NEWLINE);
+		if (osmo_sockaddr_str_is_nonzero(&e->host_v6))
+			vty_out(vty, "%sservice %s at %s %u%s", indent, e->service, e->host_v6.ip, e->host_v6.port,
+				VTY_NEWLINE);
+	}
+}
+
+int config_write_mslookup(struct vty *vty)
+{
+	if (!g_hlr->mslookup.server.enable
+	    && llist_empty(&g_hlr->mslookup.server.local_site_services)
+	    && !g_hlr->mslookup.client.enable)
+		return CMD_SUCCESS;
+
+	vty_out(vty, "mslookup%s", VTY_NEWLINE);
+
+	if (g_hlr->mslookup.server.enable || !llist_empty(&g_hlr->mslookup.server.local_site_services)) {
+		struct mslookup_server_msc_cfg *msc;
+
+		vty_out(vty, " server%s", VTY_NEWLINE);
+
+		if (g_hlr->mslookup.server.mdns.enable) {
+			vty_out(vty, "  mdns bind");
+			if (osmo_sockaddr_str_is_nonzero(&g_hlr->mslookup.server.mdns.bind_addr)) {
+				vty_out(vty, " %s %u",
+					g_hlr->mslookup.server.mdns.bind_addr.ip,
+					g_hlr->mslookup.server.mdns.bind_addr.port);
+			}
+			vty_out(vty, "%s", VTY_NEWLINE);
+		}
+		if (strcmp(g_hlr->mslookup.server.mdns.domain_suffix, OSMO_MDNS_DOMAIN_SUFFIX_DEFAULT))
+			vty_out(vty, "  mdns domain-suffix %s%s",
+				g_hlr->mslookup.server.mdns.domain_suffix,
+				VTY_NEWLINE);
+
+		msc = mslookup_server_msc_get(&mslookup_server_msc_wildcard, false);
+		if (msc)
+			config_write_msc_services(vty, " ", msc);
+
+		llist_for_each_entry(msc, &g_hlr->mslookup.server.local_site_services, entry) {
+			if (!osmo_ipa_name_cmp(&mslookup_server_msc_wildcard, &msc->name))
+				continue;
+			vty_out(vty, " msc %s%s", osmo_ipa_name_to_str(&msc->name), VTY_NEWLINE);
+			config_write_msc_services(vty, "  ", msc);
+		}
+
+		/* If the server is disabled, still output the above to not lose the service config. */
+		if (!g_hlr->mslookup.server.enable)
+			vty_out(vty, " no server%s", VTY_NEWLINE);
+	}
+
+	if (g_hlr->mslookup.client.enable) {
+		vty_out(vty, " client%s", VTY_NEWLINE);
+
+		if (osmo_sockaddr_str_is_nonzero(&g_hlr->mslookup.client.gsup_gateway_proxy))
+			vty_out(vty, "  gateway-proxy %s %u%s",
+				g_hlr->mslookup.client.gsup_gateway_proxy.ip,
+				g_hlr->mslookup.client.gsup_gateway_proxy.port,
+				VTY_NEWLINE);
+
+		if (g_hlr->mslookup.client.mdns.enable
+		    && osmo_sockaddr_str_is_nonzero(&g_hlr->mslookup.client.mdns.query_addr))
+			vty_out(vty, "  mdns bind %s %u%s",
+				g_hlr->mslookup.client.mdns.query_addr.ip,
+				g_hlr->mslookup.client.mdns.query_addr.port,
+				VTY_NEWLINE);
+		if (strcmp(g_hlr->mslookup.client.mdns.domain_suffix, OSMO_MDNS_DOMAIN_SUFFIX_DEFAULT))
+			vty_out(vty, "  mdns domain-suffix %s%s",
+				g_hlr->mslookup.client.mdns.domain_suffix,
+				VTY_NEWLINE);
+	}
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_mslookup_client_gateway_proxy,
+      cfg_mslookup_client_gateway_proxy_cmd,
+      "gateway-proxy IP [<1-65535>]",
+      "Configure a fixed IP address to send all GSUP requests for unknown IMSIs to, without invoking a lookup for IMSI\n"
+      "IP address of the remote HLR\n" "GSUP port number (omit for default " OSMO_STRINGIFY_VAL(OSMO_GSUP_PORT) ")\n")
+{
+	const char *ip_str = argv[0];
+	const char *port_str = argc > 1 ? argv[1] : NULL;
+	struct osmo_sockaddr_str addr;
+
+	if (osmo_sockaddr_str_from_str(&addr, ip_str, port_str ? atoi(port_str) : OSMO_GSUP_PORT)
+	    || !osmo_sockaddr_str_is_nonzero(&addr)) {
+		vty_out(vty, "%% mslookup client: Invalid address for gateway-proxy: %s %s%s",
+			ip_str, port_str ? : "", VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	g_hlr->mslookup.client.gsup_gateway_proxy = addr;
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_mslookup_client_no_gateway_proxy,
+      cfg_mslookup_client_no_gateway_proxy_cmd,
+      "no gateway-proxy",
+      NO_STR "Disable gateway proxy for GSUP with unknown IMSIs\n")
+{
+	g_hlr->mslookup.client.gsup_gateway_proxy = (struct osmo_sockaddr_str){};
+	return CMD_SUCCESS;
+}
+
+DEFUN(do_mslookup_show_services,
+      do_mslookup_show_services_cmd,
+      "show mslookup services",
+      SHOW_STR "Distributed GSM / mslookup related information\n"
+      "List configured service addresses as sent to remote mslookup requests\n")
+{
+	struct mslookup_server_msc_cfg *msc;
+	const struct mslookup_service_host *local_hlr = mslookup_server_get_local_gsup_addr();
+
+	vty_out(vty, "Local GSUP HLR address returned in mslookup responses for local IMSIs:");
+	if (osmo_sockaddr_str_is_nonzero(&local_hlr->host_v4))
+		vty_out(vty, " " OSMO_SOCKADDR_STR_FMT,
+			OSMO_SOCKADDR_STR_FMT_ARGS(&local_hlr->host_v4));
+	if (osmo_sockaddr_str_is_nonzero(&local_hlr->host_v6))
+		vty_out(vty, " " OSMO_SOCKADDR_STR_FMT,
+			OSMO_SOCKADDR_STR_FMT_ARGS(&local_hlr->host_v6));
+	vty_out(vty, "%s", VTY_NEWLINE);
+
+	msc = mslookup_server_msc_get(&mslookup_server_msc_wildcard, false);
+	if (msc)
+		config_write_msc_services(vty, "", msc);
+
+	llist_for_each_entry(msc, &g_hlr->mslookup.server.local_site_services, entry) {
+		if (!osmo_ipa_name_cmp(&mslookup_server_msc_wildcard, &msc->name))
+			continue;
+		vty_out(vty, "msc ipa-name %s%s", osmo_ipa_name_to_str(&msc->name), VTY_NEWLINE);
+		config_write_msc_services(vty, " ", msc);
+	}
+	return CMD_SUCCESS;
+}
+
+void dgsm_vty_init(void)
+{
+	install_element(CONFIG_NODE, &cfg_mslookup_cmd);
+
+	install_node(&mslookup_node, config_write_mslookup);
+	install_element(MSLOOKUP_NODE, &cfg_mslookup_mdns_cmd);
+	install_element(MSLOOKUP_NODE, &cfg_mslookup_mdns_domain_suffix_cmd);
+	install_element(MSLOOKUP_NODE, &cfg_mslookup_no_mdns_cmd);
+	install_element(MSLOOKUP_NODE, &cfg_mslookup_server_cmd);
+	install_element(MSLOOKUP_NODE, &cfg_mslookup_no_server_cmd);
+
+	install_node(&mslookup_server_node, NULL);
+	install_element(MSLOOKUP_SERVER_NODE, &cfg_mslookup_server_mdns_bind_cmd);
+	install_element(MSLOOKUP_SERVER_NODE, &cfg_mslookup_server_mdns_domain_suffix_cmd);
+	install_element(MSLOOKUP_SERVER_NODE, &cfg_mslookup_server_no_mdns_bind_cmd);
+	install_element(MSLOOKUP_SERVER_NODE, &cfg_mslookup_server_msc_service_cmd);
+	install_element(MSLOOKUP_SERVER_NODE, &cfg_mslookup_server_msc_no_service_cmd);
+	install_element(MSLOOKUP_SERVER_NODE, &cfg_mslookup_server_msc_no_service_addr_cmd);
+	install_element(MSLOOKUP_SERVER_NODE, &cfg_mslookup_server_msc_cmd);
+
+	install_node(&mslookup_server_msc_node, NULL);
+	install_element(MSLOOKUP_SERVER_MSC_NODE, &cfg_mslookup_server_msc_service_cmd);
+	install_element(MSLOOKUP_SERVER_MSC_NODE, &cfg_mslookup_server_msc_no_service_cmd);
+	install_element(MSLOOKUP_SERVER_MSC_NODE, &cfg_mslookup_server_msc_no_service_addr_cmd);
+
+	install_element(MSLOOKUP_NODE, &cfg_mslookup_client_cmd);
+	install_element(MSLOOKUP_NODE, &cfg_mslookup_no_client_cmd);
+	install_node(&mslookup_client_node, NULL);
+	install_element(MSLOOKUP_CLIENT_NODE, &cfg_mslookup_client_timeout_cmd);
+	install_element(MSLOOKUP_CLIENT_NODE, &cfg_mslookup_client_mdns_bind_cmd);
+	install_element(MSLOOKUP_CLIENT_NODE, &cfg_mslookup_client_mdns_domain_suffix_cmd);
+	install_element(MSLOOKUP_CLIENT_NODE, &cfg_mslookup_client_no_mdns_bind_cmd);
+	install_element(MSLOOKUP_CLIENT_NODE, &cfg_mslookup_client_gateway_proxy_cmd);
+	install_element(MSLOOKUP_CLIENT_NODE, &cfg_mslookup_client_no_gateway_proxy_cmd);
+
+	install_element_ve(&do_mslookup_show_services_cmd);
+}

src/gsup_router.c

@@ -47,6 +47,11 @@ struct osmo_gsup_conn *gsup_route_find(struct osmo_gsup_server *gs,
 	return NULL;
 }
 
+struct osmo_gsup_conn *gsup_route_find_by_ipa_name(struct osmo_gsup_server *gs, const struct osmo_ipa_name *ipa_name)
+{
+	return gsup_route_find(gs, ipa_name->val, ipa_name->len);
+}
+
 /*! Find a GSUP connection's route (to read the IPA address from the route).
  * \param[in] conn GSUP connection
  * \return GSUP route
@@ -67,10 +72,15 @@ struct gsup_route *gsup_route_find_by_conn(const struct osmo_gsup_conn *conn)
 int gsup_route_add(struct osmo_gsup_conn *conn, const uint8_t *addr, size_t addrlen)
 {
 	struct gsup_route *gr;
+	struct osmo_gsup_conn *exists_on_conn;
 
 	/* Check if we already have a route for this address */
-	if (gsup_route_find(conn->server, addr, addrlen))
-		return -EEXIST;
+	exists_on_conn = gsup_route_find(conn->server, addr, addrlen);
+	if (exists_on_conn) {
+		if (exists_on_conn != conn)
+			return -EEXIST;
+		return 0;
+	}
 
 	/* allocate new route and populate it */
 	gr = talloc_zero(conn->server, struct gsup_route);
@@ -86,6 +96,11 @@ int gsup_route_add(struct osmo_gsup_conn *conn, const uint8_t *addr, size_t addr
 	return 0;
 }
 
+int gsup_route_add_ipa_name(struct osmo_gsup_conn *conn, const struct osmo_ipa_name *ipa_name)
+{
+	return gsup_route_add(conn, ipa_name->val, ipa_name->len);
+}
+
 /* delete all routes for the given connection */
 int gsup_route_del_conn(struct osmo_gsup_conn *conn)
 {
@@ -95,7 +110,7 @@ int gsup_route_del_conn(struct osmo_gsup_conn *conn)
 	llist_for_each_entry_safe(gr, gr2, &conn->server->routes, list) {
 		if (gr->conn == conn) {
 			LOGP(DMAIN, LOGL_INFO, "Removing GSUP route for %s (GSUP disconnect)\n",
-			     gr->addr);
+			     osmo_quote_str_c(OTC_SELECT, (char*)gr->addr, talloc_total_size(gr->addr)));
 			llist_del(&gr->list);
 			talloc_free(gr);
 			num_deleted++;

src/gsup_send.c

@@ -42,7 +42,8 @@ int osmo_gsup_addr_send(struct osmo_gsup_server *gs,
 
 	conn = gsup_route_find(gs, addr, addrlen);
 	if (!conn) {
-		DEBUGP(DLGSUP, "Cannot find route for addr %s\n", osmo_quote_str((const char*)addr, addrlen));
+		LOGP(DLGSUP, LOGL_ERROR,
+		     "Cannot find route for addr %s\n", osmo_quote_str((const char*)addr, addrlen));
 		msgb_free(msg);
 		return -ENODEV;
 	}
@@ -50,3 +51,41 @@ int osmo_gsup_addr_send(struct osmo_gsup_server *gs,
 	return osmo_gsup_conn_send(conn, msg);
 }
 
+/*! Send a msgb to a given address using routing.
+ * \param[in] gs  gsup server
+ * \param[in] ipa_name  IPA unit name of the client (SGSN, MSC/VLR, proxy).
+ * \param[in] msg  message buffer
+ */
+int osmo_gsup_send_to_ipa_name(struct osmo_gsup_server *gs, const struct osmo_ipa_name *ipa_name, struct msgb *msg)
+{
+	if (ipa_name->val[ipa_name->len - 1]) {
+		/* Is not nul terminated. But for legacy reasons we (still) require that. */
+		if (ipa_name->len >= sizeof(ipa_name->val)) {
+			LOGP(DLGSUP, LOGL_ERROR, "IPA unit name is too long: %s\n",
+			     osmo_ipa_name_to_str(ipa_name));
+			return -EINVAL;
+		}
+		struct osmo_ipa_name ipa_name2 = *ipa_name;
+		ipa_name2.val[ipa_name->len] = '\0';
+		ipa_name2.len++;
+		return osmo_gsup_addr_send(gs, ipa_name2.val, ipa_name2.len, msg);
+	}
+	return osmo_gsup_addr_send(gs, ipa_name->val, ipa_name->len, msg);
+}
+
+int osmo_gsup_enc_send_to_ipa_name(struct osmo_gsup_server *gs, const struct osmo_ipa_name *ipa_name,
+			  const struct osmo_gsup_message *gsup)
+{
+	struct msgb *msg = osmo_gsup_msgb_alloc("GSUP Tx");
+	int rc;
+	rc = osmo_gsup_encode(msg, gsup);
+	if (rc) {
+		LOGP(DLGSUP, LOGL_ERROR, "IMSI-%s: Cannot encode GSUP: %s\n",
+		     gsup->imsi, osmo_gsup_message_type_name(gsup->message_type));
+		msgb_free(msg);
+		return -EINVAL;
+	}
+
+	LOGP(DLGSUP, LOGL_DEBUG, "IMSI-%s: Tx: %s\n", gsup->imsi, osmo_gsup_message_type_name(gsup->message_type));
+	return osmo_gsup_send_to_ipa_name(gs, ipa_name, msg);
+}

src/gsup_server.c

@@ -26,13 +26,18 @@
 #include <osmocom/abis/ipaccess.h>
 #include <osmocom/gsm/gsm48_ie.h>
 #include <osmocom/gsm/apn.h>
+#include <osmocom/gsm/gsm23003.h>
 
 #include <osmocom/hlr/gsup_server.h>
 #include <osmocom/hlr/gsup_router.h>
 
+#define LOG_GSUP_CONN(conn, level, fmt, args...) \
+	LOGP(DLGSUP, level, "GSUP peer %s: " fmt, \
+	     (conn) ? osmo_ipa_name_to_str(&(conn)->peer_name) : "NULL", ##args)
+
 struct msgb *osmo_gsup_msgb_alloc(const char *label)
 {
-	struct msgb *msg = msgb_alloc_headroom(1024+16, 16, label);
+	struct msgb *msg = msgb_alloc_headroom(1024+512, 512, label);
 	OSMO_ASSERT(msg);
 	return msg;
 }
@@ -57,6 +62,91 @@ int osmo_gsup_conn_send(struct osmo_gsup_conn *conn, struct msgb *msg)
 	return 0;
 }
 
+static void gsup_server_send_req_response(struct osmo_gsup_req *req, struct osmo_gsup_message *response)
+{
+	struct osmo_gsup_server *server = req->cb_data;
+	struct osmo_gsup_peer_id *routing;
+	struct osmo_gsup_conn *conn = NULL;
+	struct msgb *msg = osmo_gsup_msgb_alloc("GSUP Tx");
+	int rc;
+
+	if (response->message_type == OSMO_GSUP_MSGT_ROUTING_ERROR
+	    && !osmo_gsup_peer_id_is_empty(&req->via_proxy)) {
+		/* If a routing error occured, we need to route back via the immediate sending peer, not via the
+		 * intended final recipient -- because one source of routing errors is a duplicate name for a recipient.
+		 * If we resolve to req->source_name, we may send to a completely unrelated recipient. */
+		routing = &req->via_proxy;
+	} else {
+		routing = &req->source_name;
+	}
+	switch (routing->type) {
+	case OSMO_GSUP_PEER_ID_IPA_NAME:
+		conn = gsup_route_find_by_ipa_name(server, &routing->ipa_name);
+		break;
+	default:
+		LOG_GSUP_REQ(req, LOGL_ERROR, "GSUP peer id kind not supported: %s\n",
+			     osmo_gsup_peer_id_type_name(routing->type));
+		break;
+	}
+
+	if (!conn) {
+		LOG_GSUP_REQ(req, LOGL_ERROR, "GSUP client that sent this request not found, cannot respond\n");
+		msgb_free(msg);
+		return;
+	}
+
+	rc = osmo_gsup_encode(msg, response);
+	if (rc) {
+		LOG_GSUP_REQ(req, LOGL_ERROR, "Unable to encode: {%s}\n",
+			     osmo_gsup_message_to_str_c(OTC_SELECT, response));
+		msgb_free(msg);
+		return;
+	}
+
+	rc = osmo_gsup_conn_send(conn, msg);
+	if (rc)
+		LOG_GSUP_CONN(conn, LOGL_ERROR, "Unable to send: %s\n", osmo_gsup_message_to_str_c(OTC_SELECT, response));
+}
+
+struct osmo_gsup_req *osmo_gsup_conn_rx(struct osmo_gsup_conn *conn, struct msgb *msg)
+{
+	struct osmo_gsup_req *req;
+	struct osmo_gsup_peer_id gpi = {
+		.type = OSMO_GSUP_PEER_ID_IPA_NAME,
+		.ipa_name = conn->peer_name,
+	};
+
+	req = osmo_gsup_req_new(conn->server, &gpi, msg, gsup_server_send_req_response, conn->server, NULL);
+	if (!req)
+		return NULL;
+
+	if (!osmo_gsup_peer_id_is_empty(&req->via_proxy)) {
+		switch (req->via_proxy.type) {
+		case OSMO_GSUP_PEER_ID_IPA_NAME:
+			break;
+		default:
+			LOG_GSUP_REQ(req, LOGL_ERROR, "GSUP peer id kind not supported: %s\n",
+				     osmo_gsup_peer_id_type_name(req->source_name.type));
+			osmo_gsup_req_respond_msgt(req, OSMO_GSUP_MSGT_ROUTING_ERROR, true);
+			return NULL;
+		}
+
+		/* The source of the GSUP message is not the immediate GSUP peer, but that peer is our proxy for that
+		 * source. Add it to the routes for this conn (so we can route responses back). */
+		if (gsup_route_add_ipa_name(conn, &req->source_name.ipa_name)) {
+			LOG_GSUP_REQ(req, LOGL_ERROR,
+				     "GSUP message received from %s via peer %s, but there already exists a"
+				     " different route to this source, message is not routable\n",
+				     osmo_gsup_peer_id_to_str(&req->source_name),
+				     osmo_ipa_name_to_str(&conn->peer_name));
+			osmo_gsup_req_respond_msgt(req, OSMO_GSUP_MSGT_ROUTING_ERROR, true);
+			return NULL;
+		}
+	}
+
+	return req;
+}
+
 static int osmo_gsup_conn_oap_handle(struct osmo_gsup_conn *conn,
 				struct msgb *msg_rx)
 {
@@ -202,10 +292,18 @@ static int osmo_gsup_server_ccm_cb(struct ipa_server_conn *conn,
 		return -EINVAL;
 	}
 
-	gsup_route_add(clnt, addr, addr_len);
+	osmo_ipa_name_set(&clnt->peer_name, addr, addr_len);
+	gsup_route_add_ipa_name(clnt, &clnt->peer_name);
 	return 0;
 }
 
+static void osmo_gsup_conn_free(struct osmo_gsup_conn *conn)
+{
+	gsup_route_del_conn(conn);
+	llist_del(&conn->list);
+	talloc_free(conn);
+}
+
 static int osmo_gsup_server_closed_cb(struct ipa_server_conn *conn)
 {
 	struct osmo_gsup_conn *clnt = (struct osmo_gsup_conn *)conn->data;
@@ -213,10 +311,7 @@ static int osmo_gsup_server_closed_cb(struct ipa_server_conn *conn)
 	LOGP(DLGSUP, LOGL_INFO, "Lost GSUP client %s:%d\n",
 		conn->addr, conn->port);
 
-	gsup_route_del_conn(clnt);
-	llist_del(&clnt->list);
-	talloc_free(clnt);
-
+	osmo_gsup_conn_free(clnt);
 	return 0;
 }
 
@@ -298,8 +393,7 @@ failed:
 
 struct osmo_gsup_server *
 osmo_gsup_server_create(void *ctx, const char *ip_addr, uint16_t tcp_port,
-			osmo_gsup_read_cb_t read_cb,
-			struct llist_head *lu_op_lst, void *priv)
+			osmo_gsup_read_cb_t read_cb, void *priv)
 {
 	struct osmo_gsup_server *gsups;
 	int rc;
@@ -325,8 +419,6 @@ osmo_gsup_server_create(void *ctx, const char *ip_addr, uint16_t tcp_port,
 	if (rc < 0)
 		goto failed;
 
-	gsups->luop = lu_op_lst;
-
 	return gsups;
 
 failed:
@@ -390,8 +482,10 @@ int osmo_gsup_create_insert_subscriber_data_msg(struct osmo_gsup_message *gsup,
 	int len;
 
 	OSMO_ASSERT(gsup);
+	*gsup = (struct osmo_gsup_message){
+		.message_type = OSMO_GSUP_MSGT_INSERT_DATA_REQUEST,
+	};
 
-	gsup->message_type = OSMO_GSUP_MSGT_INSERT_DATA_REQUEST;
 	osmo_strlcpy(gsup->imsi, imsi, sizeof(gsup->imsi));
 
 	if (msisdn_enc_size < OSMO_GSUP_MAX_CALLED_PARTY_BCD_LEN)
@@ -419,3 +513,39 @@ int osmo_gsup_create_insert_subscriber_data_msg(struct osmo_gsup_message *gsup,
 
 	return 0;
 }
+
+int osmo_gsup_forward_to_local_peer(struct osmo_gsup_server *server, const struct osmo_gsup_peer_id *to_peer,
+				    struct osmo_gsup_req *req, struct osmo_gsup_message *modified_gsup)
+{
+	int rc;
+	/* To forward to a remote entity (HLR, SMSC,...), we need to indicate the original source name in the Source
+	 * Name IE to make sure the reply can be routed back. Store the sender in gsup->source_name -- the remote entity
+	 * is required to return this as gsup->destination_name so that the reply gets routed to the original sender. */
+	struct osmo_gsup_message forward = *(modified_gsup? : &req->gsup);
+
+	if (req->source_name.type != OSMO_GSUP_PEER_ID_IPA_NAME) {
+		osmo_gsup_req_respond_err(req, GMM_CAUSE_NET_FAIL, "Unsupported GSUP peer id type: %s",
+					  osmo_gsup_peer_id_type_name(req->source_name.type));
+		rc = -ENOTSUP;
+		goto routing_error;
+	}
+	forward.source_name = req->source_name.ipa_name.val;
+	forward.source_name_len = req->source_name.ipa_name.len;
+
+	if (to_peer->type != OSMO_GSUP_PEER_ID_IPA_NAME) {
+		osmo_gsup_req_respond_err(req, GMM_CAUSE_NET_FAIL, "Unsupported GSUP peer id type: %s",
+					  osmo_gsup_peer_id_type_name(to_peer->type));
+		rc = -ENOTSUP;
+		goto routing_error;
+	}
+	LOG_GSUP_REQ(req, LOGL_INFO, "Forwarding to %s\n", osmo_gsup_peer_id_to_str(to_peer));
+	rc = osmo_gsup_enc_send_to_ipa_name(server, &to_peer->ipa_name, &forward);
+	if (rc)
+		goto routing_error;
+	osmo_gsup_req_free(req);
+	return 0;
+
+routing_error:
+	osmo_gsup_req_respond_msgt(req, OSMO_GSUP_MSGT_ROUTING_ERROR, true);
+	return rc;
+}

src/gsupclient/Makefile.am

@@ -8,7 +8,11 @@ AM_CFLAGS = -Wall $(all_includes) -I$(top_srcdir)/include -I$(top_builddir)/incl
 
 lib_LTLIBRARIES = libosmo-gsup-client.la
 
-libosmo_gsup_client_la_SOURCES = gsup_client.c
+libosmo_gsup_client_la_SOURCES = \
+	gsup_peer_id.c \
+	gsup_client.c \
+	gsup_req.c \
+	$(NULL)
 
 libosmo_gsup_client_la_LDFLAGS = -version-info $(LIBVERSION) -no-undefined
 libosmo_gsup_client_la_LIBADD = $(TALLOC_LIBS) $(LIBOSMOCORE_LIBS) $(LIBOSMOABIS_LIBS)

src/gsupclient/gsup_client.c

@@ -97,6 +97,12 @@ static void connect_timer_cb(void *gsupc_)
 	if (gsupc->is_connected)
 		return;
 
+	if (gsupc->up_down_cb) {
+		/* When the up_down_cb() returns false, the user asks us not to retry connecting. */
+		if (!gsupc->up_down_cb(gsupc, false))
+			return;
+	}
+
 	gsup_client_connect(gsupc);
 }
 
@@ -139,9 +145,18 @@ static void gsup_client_updown_cb(struct ipa_client_conn *link, int up)
 			gsup_client_oap_register(gsupc);
 
 		osmo_timer_del(&gsupc->connect_timer);
+
+		if (gsupc->up_down_cb)
+			gsupc->up_down_cb(gsupc, true);
 	} else {
 		osmo_timer_del(&gsupc->ping_timer);
 
+		if (gsupc->up_down_cb) {
+			/* When the up_down_cb() returns false, the user asks us not to retry connecting. */
+			if (!gsupc->up_down_cb(gsupc, false))
+				return;
+		}
+
 		osmo_timer_schedule(&gsupc->connect_timer,
 				    OSMO_GSUP_CLIENT_RECONNECT_INTERVAL, 0);
 	}
@@ -263,42 +278,40 @@ static void start_test_procedure(struct osmo_gsup_client *gsupc)
  * Use the provided ipaccess unit as the client-side identifier; ipa_dev should
  * be allocated in talloc_ctx talloc_ctx as well.
  * \param[in] talloc_ctx talloc context.
- * \param[in] ipa_dev IP access unit which contains client identification information; must be allocated
- *                    in talloc_ctx as well to ensure it lives throughout the lifetime of the connection.
- * \param[in] ip_addr GSUP server IP address.
- * \param[in] tcp_port GSUP server TCP port.
- * \param[in] read_cb callback for reading from the GSUP connection.
- * \param[in] oapc_config OPA client configuration.
- *  \returns a GSUP client connection or NULL on failure.
+ * \param[in] config  Parameters for setting up the GSUP client.
+ * \return a GSUP client connection, or NULL on failure.
  */
-struct osmo_gsup_client *osmo_gsup_client_create2(void *talloc_ctx,
-						  struct ipaccess_unit *ipa_dev,
-						  const char *ip_addr,
-						  unsigned int tcp_port,
-						  osmo_gsup_client_read_cb_t read_cb,
-						  struct osmo_oap_client_config *oapc_config)
+struct osmo_gsup_client *osmo_gsup_client_create3(void *talloc_ctx, struct osmo_gsup_client_config *config)
 {
 	struct osmo_gsup_client *gsupc;
 	int rc;
 
+	OSMO_ASSERT(config->ipa_dev->unit_name);
+
 	gsupc = talloc_zero(talloc_ctx, struct osmo_gsup_client);
 	OSMO_ASSERT(gsupc);
-	gsupc->unit_name = (const char *)ipa_dev->unit_name; /* API backwards compat */
-	gsupc->ipa_dev = ipa_dev;
+	*gsupc = (struct osmo_gsup_client){
+		.unit_name = (const char *)config->ipa_dev->unit_name, /* API backwards compat */
+		.ipa_dev = config->ipa_dev,
+		.read_cb = config->read_cb,
+		.up_down_cb = config->up_down_cb,
+		.data = config->data,
+	};
 
 	/* a NULL oapc_config will mark oap_state disabled. */
-	rc = osmo_oap_client_init(oapc_config, &gsupc->oap_state);
+	rc = osmo_oap_client_init(config->oapc_config, &gsupc->oap_state);
 	if (rc != 0)
 		goto failed;
 
-	gsupc->link = ipa_client_conn_create(gsupc,
-					     /* no e1inp */ NULL,
-					     0,
-					     ip_addr, tcp_port,
-					     gsup_client_updown_cb,
-					     gsup_client_read_cb,
-					     /* default write_cb */ NULL,
-					     gsupc);
+	gsupc->link = ipa_client_conn_create2(gsupc,
+					      /* no e1inp */ NULL,
+					      0,
+					      /* no specific local IP:port */ NULL, 0,
+					      config->ip_addr, config->tcp_port,
+					      gsup_client_updown_cb,
+					      gsup_client_read_cb,
+					      /* default write_cb */ NULL,
+					      gsupc);
 	if (!gsupc->link)
 		goto failed;
 
@@ -308,9 +321,6 @@ struct osmo_gsup_client *osmo_gsup_client_create2(void *talloc_ctx,
 
 	if (rc < 0)
 		goto failed;
-
-	gsupc->read_cb = read_cb;
-
 	return gsupc;
 
 failed:
@@ -318,6 +328,26 @@ failed:
 	return NULL;
 }
 
+/*! Like osmo_gsup_client_create3() but without the up_down_cb and data arguments, and with the oapc_config argument in
+ * a different position.
+ */
+struct osmo_gsup_client *osmo_gsup_client_create2(void *talloc_ctx,
+						  struct ipaccess_unit *ipa_dev,
+						  const char *ip_addr,
+						  unsigned int tcp_port,
+						  osmo_gsup_client_read_cb_t read_cb,
+						  struct osmo_oap_client_config *oapc_config)
+{
+	struct osmo_gsup_client_config cfg = {
+		.ipa_dev = ipa_dev,
+		.ip_addr = ip_addr,
+		.tcp_port = tcp_port,
+		.oapc_config = oapc_config,
+		.read_cb = read_cb,
+	};
+	return osmo_gsup_client_create3(talloc_ctx, &cfg);
+}
+
 /**
  * Like osmo_gsup_client_create2() except it expects a unit name instead
  * of a full-blown ipacess_unit as the client-side identifier.

src/gsupclient/gsup_peer_id.c

@@ -0,0 +1,187 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <errno.h>
+#include <string.h>
+#include <osmocom/core/utils.h>
+#include <osmocom/gsupclient/gsup_peer_id.h>
+
+bool osmo_ipa_name_is_empty(struct osmo_ipa_name *ipa_name)
+{
+	return (!ipa_name) || (!ipa_name->len);
+}
+
+int osmo_ipa_name_set(struct osmo_ipa_name *ipa_name, const uint8_t *val, size_t len)
+{
+	if (!val || !len) {
+		*ipa_name = (struct osmo_ipa_name){};
+		return 0;
+	}
+	if (len > sizeof(ipa_name->val))
+		return -ENOSPC;
+	ipa_name->len = len;
+	memcpy(ipa_name->val, val, len);
+	return 0;
+}
+
+static int osmo_ipa_name_set_str_va(struct osmo_ipa_name *ipa_name, const char *str_fmt, va_list ap)
+{
+	if (!str_fmt)
+		return osmo_ipa_name_set(ipa_name, NULL, 0);
+	vsnprintf((char*)(ipa_name->val), sizeof(ipa_name->val), str_fmt, ap);
+	ipa_name->len = strlen((char*)(ipa_name->val))+1;
+	return 0;
+}
+
+int osmo_ipa_name_set_str(struct osmo_ipa_name *ipa_name, const char *str_fmt, ...)
+{
+	va_list ap;
+	int rc;
+	va_start(ap, str_fmt);
+	rc = osmo_ipa_name_set_str_va(ipa_name, str_fmt, ap);
+	va_end(ap);
+	return rc;
+}
+
+int osmo_ipa_name_cmp(const struct osmo_ipa_name *a, const struct osmo_ipa_name *b)
+{
+	int cmp;
+	if (a == b)
+		return 0;
+	if (!a)
+		return -1;
+	if (!b)
+		return 1;
+	if (!a->len && !b->len)
+		return 0;
+	if (!a->len && b->len)
+		return -1;
+	if (!b->len && a->len)
+		return 1;
+
+	if (a->len == b->len)
+		return memcmp(a->val, b->val, a->len);
+	else if (a->len < b->len) {
+		cmp = memcmp(a->val, b->val, a->len);
+		if (!cmp)
+			cmp = -1;
+		return cmp;
+	} else {
+		/* a->len > b->len */
+		cmp = memcmp(a->val, b->val, b->len);
+		if (!cmp)
+			cmp = 1;
+		return cmp;
+	}
+}
+
+/* Call osmo_ipa_name_to_str_c with OTC_SELECT. */
+const char *osmo_ipa_name_to_str(const struct osmo_ipa_name *ipa_name)
+{
+	return osmo_ipa_name_to_str_c(OTC_SELECT, ipa_name);
+}
+
+/* Return an unquoted string, not including the terminating zero. Used for writing VTY config. */
+const char *osmo_ipa_name_to_str_c(void *ctx, const struct osmo_ipa_name *ipa_name)
+{
+	size_t len = ipa_name->len;
+	if (!len)
+		return talloc_strdup(ctx, "");
+	if (ipa_name->val[len-1] == '\0')
+		len--;
+	return osmo_escape_str_c(ctx, (char*)ipa_name->val, len);
+}
+
+bool osmo_gsup_peer_id_is_empty(struct osmo_gsup_peer_id *gsup_peer_id)
+{
+	if (!gsup_peer_id)
+		return true;
+	switch (gsup_peer_id->type) {
+	case OSMO_GSUP_PEER_ID_EMPTY:
+		return true;
+	case OSMO_GSUP_PEER_ID_IPA_NAME:
+		return osmo_ipa_name_is_empty(&gsup_peer_id->ipa_name);
+	default:
+		return false;
+	}
+}
+int osmo_gsup_peer_id_set(struct osmo_gsup_peer_id *gsup_peer_id, enum osmo_gsup_peer_id_type type,
+			  const uint8_t *val, size_t len)
+{
+	gsup_peer_id->type = type;
+	switch (type) {
+	case OSMO_GSUP_PEER_ID_IPA_NAME:
+		return osmo_ipa_name_set(&gsup_peer_id->ipa_name, val, len);
+	default:
+		return -EINVAL;
+	}
+}
+
+int osmo_gsup_peer_id_set_str(struct osmo_gsup_peer_id *gsup_peer_id, enum osmo_gsup_peer_id_type type,
+			      const char *str_fmt, ...)
+{
+	va_list ap;
+	int rc;
+
+	*gsup_peer_id = (struct osmo_gsup_peer_id){};
+
+	switch (type) {
+	case OSMO_GSUP_PEER_ID_IPA_NAME:
+		gsup_peer_id->type = OSMO_GSUP_PEER_ID_IPA_NAME;
+		va_start(ap, str_fmt);
+		rc = osmo_ipa_name_set_str_va(&gsup_peer_id->ipa_name, str_fmt, ap);
+		va_end(ap);
+		return rc;
+	default:
+		return -EINVAL;
+	}
+}
+
+int osmo_gsup_peer_id_cmp(const struct osmo_gsup_peer_id *a, const struct osmo_gsup_peer_id *b)
+{
+	if (a->type != b->type)
+		return OSMO_CMP(a->type, b->type);
+	switch (a->type) {
+	case OSMO_GSUP_PEER_ID_IPA_NAME:
+		return osmo_ipa_name_cmp(&a->ipa_name, &b->ipa_name);
+	default:
+		return -EINVAL;
+	}
+}
+
+const struct value_string osmo_gsup_peer_id_type_names[] = {
+	{ OSMO_GSUP_PEER_ID_IPA_NAME, "IPA-name" },
+	{}
+};
+
+/* Call osmo_gsup_peer_id_to_str_c with OTC_SELECT */
+const char *osmo_gsup_peer_id_to_str(const struct osmo_gsup_peer_id *gpi)
+{
+	return osmo_gsup_peer_id_to_str_c(OTC_SELECT, gpi);
+}
+
+/* Return an unquoted string, not including the terminating zero. Used for writing VTY config. */
+const char *osmo_gsup_peer_id_to_str_c(void *ctx, const struct osmo_gsup_peer_id *gpi)
+{
+	switch (gpi->type) {
+	case OSMO_GSUP_PEER_ID_IPA_NAME:
+		return osmo_ipa_name_to_str_c(ctx, &gpi->ipa_name);
+	default:
+		return talloc_strdup(ctx, osmo_gsup_peer_id_type_name(gpi->type));
+	}
+}

src/gsupclient/gsup_req.c

@@ -0,0 +1,312 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <errno.h>
+#include <inttypes.h>
+
+#include <osmocom/core/logging.h>
+#include <osmocom/gsm/gsm23003.h>
+
+#include <osmocom/gsupclient/gsup_req.h>
+
+/*! Create a new osmo_gsup_req record, decode GSUP and add to a provided list of requests.
+ * This function takes ownership of the msgb, which will, on success, be owned by the returned osmo_gsup_req instance
+ * until osmo_gsup_req_free(). If a decoding error occurs, send an error response immediately, and return NULL.
+ *
+ * When this function returns, the original sender is found in req->source_name. If this is not the immediate peer name,
+ * then req->via_proxy is set to the immediate peer, and it is the responsibility of the caller to add req->source_name
+ * to the GSUP routes that are serviced by req->via_proxy (usually not relevant for clients with a single GSUP conn).
+ *
+ * Note: osmo_gsup_req API makes use of OTC_SELECT to allocate volatile buffers for logging. Use of
+ * osmo_select_main_ctx() is mandatory when using osmo_gsup_req.
+ *
+ * \param[in] ctx  Talloc context for allocation of the new request.
+ * \param[in] from_peer  The IPA unit name of the immediate GSUP peer from which this msgb was received.
+ * \param[in] msg  The GSUP message buffer.
+ * \param[in] send_response_cb  User specific method to send a GSUP response message, invoked upon
+ *				osmo_gsup_req_respond*() functions.
+ * \param[inout] cb_data  Context data to be used freely by the caller.
+ * \param[inout] add_to_list  List to which to append this request, or NULL for no list.
+ * \return a newly allocated osmo_gsup_req, or NULL on error.
+ */
+struct osmo_gsup_req *osmo_gsup_req_new(void *ctx, const struct osmo_gsup_peer_id *from_peer, struct msgb *msg,
+					osmo_gsup_req_send_response_t send_response_cb, void *cb_data,
+					struct llist_head *add_to_list)
+{
+	static unsigned int next_req_nr = 1;
+	struct osmo_gsup_req *req;
+	int rc;
+
+	if (!msgb_l2(msg) || !msgb_l2len(msg)) {
+		LOGP(DLGSUP, LOGL_ERROR, "Rx GSUP from %s: missing or empty L2 data\n",
+		     osmo_gsup_peer_id_to_str(from_peer));
+		msgb_free(msg);
+		return NULL;
+	}
+
+	req = talloc_zero(ctx, struct osmo_gsup_req);
+	OSMO_ASSERT(req);
+	/* Note: req->gsup is declared const, so that the incoming message cannot be modified by handlers. */
+	req->nr = next_req_nr++;
+	req->msg = msg;
+	req->send_response_cb = send_response_cb;
+	req->cb_data = cb_data;
+	if (from_peer)
+		req->source_name = *from_peer;
+	rc = osmo_gsup_decode(msgb_l2(req->msg), msgb_l2len(req->msg), (struct osmo_gsup_message*)&req->gsup);
+	if (rc < 0) {
+		LOGP(DLGSUP, LOGL_ERROR, "Rx GSUP from %s: cannot decode (rc=%d)\n", osmo_gsup_peer_id_to_str(from_peer), rc);
+		osmo_gsup_req_free(req);
+		return NULL;
+	}
+
+	LOG_GSUP_REQ(req, LOGL_DEBUG, "new request: {%s}\n", osmo_gsup_message_to_str_c(OTC_SELECT, &req->gsup));
+
+	if (req->gsup.source_name_len) {
+		if (osmo_gsup_peer_id_set(&req->source_name, OSMO_GSUP_PEER_ID_IPA_NAME,
+					  req->gsup.source_name, req->gsup.source_name_len)) {
+			LOGP(DLGSUP, LOGL_ERROR,
+			     "Rx GSUP from %s: failed to decode source_name, message is not routable\n",
+			     osmo_gsup_peer_id_to_str(from_peer));
+			osmo_gsup_req_respond_msgt(req, OSMO_GSUP_MSGT_ROUTING_ERROR, true);
+			return NULL;
+		}
+
+		/* The source of the GSUP message is not the immediate GSUP peer; the peer is our proxy for that source.
+		 */
+		if (osmo_gsup_peer_id_cmp(&req->source_name, from_peer))
+			req->via_proxy = *from_peer;
+	}
+
+	if (!osmo_imsi_str_valid(req->gsup.imsi)) {
+		osmo_gsup_req_respond_err(req, GMM_CAUSE_INV_MAND_INFO, "invalid IMSI: %s",
+					  osmo_quote_str(req->gsup.imsi, -1));
+		return NULL;
+	}
+
+	if (add_to_list)
+		llist_add_tail(&req->entry, add_to_list);
+	return req;
+}
+
+void osmo_gsup_req_free(struct osmo_gsup_req *req)
+{
+	LOG_GSUP_REQ(req, LOGL_DEBUG, "free\n");
+	if (req->msg)
+		msgb_free(req->msg);
+	if (req->entry.prev)
+		llist_del(&req->entry);
+	talloc_free(req);
+}
+
+int _osmo_gsup_req_respond(struct osmo_gsup_req *req, struct osmo_gsup_message *response,
+			   bool error, bool final_response, const char *file, int line)
+{
+	int rc;
+
+	rc = osmo_gsup_make_response(response, &req->gsup, error, final_response);
+	if (rc) {
+		LOG_GSUP_REQ_SRC(req, LOGL_ERROR, file, line, "Invalid response (rc=%d): {%s}\n",
+				 rc, osmo_gsup_message_to_str_c(OTC_SELECT, response));
+		rc = -EINVAL;
+		goto exit_cleanup;
+	}
+
+	if (!req->send_response_cb) {
+		LOG_GSUP_REQ_SRC(req, LOGL_ERROR, file, line, "No send_response_cb set, cannot send: {%s}\n",
+				 osmo_gsup_message_to_str_c(OTC_SELECT, response));
+		rc = -EINVAL;
+		goto exit_cleanup;
+	}
+
+	LOG_GSUP_REQ_SRC(req, LOGL_DEBUG, file, line, "Tx response: {%s}\n",
+			 osmo_gsup_message_to_str_c(OTC_SELECT, response));
+	req->send_response_cb(req, response);
+
+exit_cleanup:
+	if (final_response)
+		osmo_gsup_req_free(req);
+	return rc;
+}
+
+int _osmo_gsup_req_respond_msgt(struct osmo_gsup_req *req, enum osmo_gsup_message_type message_type,
+				bool final_response, const char *file, int line)
+{
+	struct osmo_gsup_message response = {
+		.message_type = message_type,
+	};
+	return _osmo_gsup_req_respond(req, &response, OSMO_GSUP_IS_MSGT_ERROR(message_type), final_response,
+				      file, line);
+}
+
+void _osmo_gsup_req_respond_err(struct osmo_gsup_req *req, enum gsm48_gmm_cause cause,
+				const char *file, int line)
+{
+	struct osmo_gsup_message response = {
+		.cause = cause,
+	};
+
+	/* No need to answer if we couldn't parse an ERROR message type, only REQUESTs need an error reply. */
+	if (!OSMO_GSUP_IS_MSGT_REQUEST(req->gsup.message_type)) {
+		osmo_gsup_req_free(req);
+		return;
+	}
+
+	osmo_gsup_req_respond(req, &response, true, true);
+}
+
+/*! This function is implicitly called by the osmo_gsup_req API, if at all possible rather use osmo_gsup_req_respond().
+ * This function is non-static mostly to allow unit testing.
+ *
+ * Set fields, if still unset, that need to be copied from a received message over to its response message, to ensure
+ * the response can be routed back to the requesting peer even via GSUP proxies.
+ *
+ * Note: after calling this function, fields in the reply may reference the same memory as rx and are not deep-copied,
+ * as is the usual way we are handling decoded GSUP messages.
+ *
+ * These fields are set in the reply message, iff they are still unset:
+ * - Set reply->message_type to the rx's matching RESULT code (or ERROR code if error == true).
+ * - IMSI,
+ * - Set reply->destination_name to rx->source_name (for proxy routing),
+ * - sm_rp_mr (for SMS),
+ * - session_id (for SS/USSD),
+ * - if rx->session_state is not NONE, set tx->session_state depending on the final_response argument:
+ *   If false, set to OSMO_GSUP_SESSION_STATE_CONTINUE, else OSMO_GSUP_SESSION_STATE_END.
+ *
+ * If values in reply are already set, they will not be overwritten. The return code is an optional way of finding out
+ * whether all values that were already set in 'reply' are indeed matching the 'rx' values that would have been set.
+ *
+ * \param[in] rx  Received GSUP message that is being replied to.
+ * \param[inout] reply  The message that should be the response to rx, either empty or with some values already set up.
+ * \return 0 if the resulting message is a valid response for rx, nonzero otherwise. A nonzero rc has no effect on the
+ *         values set in the reply message: all unset fields are first updated, and then the rc is determined.
+ *         The rc is intended to merely warn if the reply message already contained data that is incompatible with rx,
+ *         e.g. a mismatching IMSI.
+ */
+int osmo_gsup_make_response(struct osmo_gsup_message *reply,
+			    const struct osmo_gsup_message *rx, bool error, bool final_response)
+{
+	int rc = 0;
+
+	if (!reply->message_type) {
+		if (error)
+			reply->message_type = OSMO_GSUP_TO_MSGT_ERROR(rx->message_type);
+		else
+			reply->message_type = OSMO_GSUP_TO_MSGT_RESULT(rx->message_type);
+	}
+
+	if (*reply->imsi == '\0')
+		OSMO_STRLCPY_ARRAY(reply->imsi, rx->imsi);
+
+	if (reply->message_class == OSMO_GSUP_MESSAGE_CLASS_UNSET)
+		reply->message_class = rx->message_class;
+
+	if (!reply->destination_name || !reply->destination_name_len) {
+		reply->destination_name = rx->source_name;
+		reply->destination_name_len = rx->source_name_len;
+	}
+
+	/* RP-Message-Reference is mandatory for SM Service */
+	if (!reply->sm_rp_mr)
+		reply->sm_rp_mr = rx->sm_rp_mr;
+
+	/* For SS/USSD, it's important to keep both session state and ID IEs */
+	if (!reply->session_id)
+		reply->session_id = rx->session_id;
+	if (rx->session_state != OSMO_GSUP_SESSION_STATE_NONE
+	    && reply->session_state == OSMO_GSUP_SESSION_STATE_NONE) {
+		if (final_response || rx->session_state == OSMO_GSUP_SESSION_STATE_END)
+			reply->session_state = OSMO_GSUP_SESSION_STATE_END;
+		else
+			reply->session_state = OSMO_GSUP_SESSION_STATE_CONTINUE;
+	}
+
+	if (strcmp(reply->imsi, rx->imsi))
+		rc |= 1 << 0;
+	if (reply->message_class != rx->message_class)
+		rc |= 1 << 1;
+	if (rx->sm_rp_mr && (!reply->sm_rp_mr || *rx->sm_rp_mr != *reply->sm_rp_mr))
+		rc |= 1 << 2;
+	if (reply->session_id != rx->session_id)
+		rc |= 1 << 3;
+	return rc;
+}
+
+/*! Print the most important value of a GSUP message to a string buffer in human readable form.
+ * \param[out] buf  The buffer to write to.
+ * \param[out] buflen  sizeof(buf).
+ * \param[in] msg  GSUP message to print.
+ */
+size_t osmo_gsup_message_to_str_buf(char *buf, size_t buflen, const struct osmo_gsup_message *msg)
+{
+	struct osmo_strbuf sb = { .buf = buf, .len = buflen };
+	if (!msg) {
+		OSMO_STRBUF_PRINTF(sb, "NULL");
+		return sb.chars_needed;
+	}
+
+	if (msg->message_class)
+		OSMO_STRBUF_PRINTF(sb, "%s ", osmo_gsup_message_class_name(msg->message_class));
+
+	OSMO_STRBUF_PRINTF(sb, "%s:", osmo_gsup_message_type_name(msg->message_type));
+
+	OSMO_STRBUF_PRINTF(sb, " imsi=");
+	OSMO_STRBUF_APPEND(sb, osmo_quote_cstr_buf, msg->imsi, strnlen(msg->imsi, sizeof(msg->imsi)));
+
+	if (msg->cause)
+		OSMO_STRBUF_PRINTF(sb, " cause=%s", get_value_string(gsm48_gmm_cause_names, msg->cause));
+
+	switch (msg->cn_domain) {
+	case OSMO_GSUP_CN_DOMAIN_CS:
+		OSMO_STRBUF_PRINTF(sb, " cn_domain=CS");
+		break;
+	case OSMO_GSUP_CN_DOMAIN_PS:
+		OSMO_STRBUF_PRINTF(sb, " cn_domain=PS");
+		break;
+	default:
+		if (msg->cn_domain)
+			OSMO_STRBUF_PRINTF(sb, " cn_domain=?(%d)", msg->cn_domain);
+		break;
+	}
+
+	if (msg->source_name_len) {
+		OSMO_STRBUF_PRINTF(sb, " source_name=");
+		OSMO_STRBUF_APPEND(sb, osmo_quote_cstr_buf, (char*)msg->source_name, msg->source_name_len);
+	}
+
+	if (msg->destination_name_len) {
+		OSMO_STRBUF_PRINTF(sb, " destination_name=");
+		OSMO_STRBUF_APPEND(sb, osmo_quote_cstr_buf, (char*)msg->destination_name, msg->destination_name_len);
+	}
+
+	if (msg->session_id)
+		OSMO_STRBUF_PRINTF(sb, " session_id=%" PRIu32, msg->session_id);
+	if (msg->session_state)
+		OSMO_STRBUF_PRINTF(sb, " session_state=%s", osmo_gsup_session_state_name(msg->session_state));
+
+	if (msg->sm_rp_mr)
+		OSMO_STRBUF_PRINTF(sb, " sm_rp_mr=%" PRIu8, *msg->sm_rp_mr);
+
+	return sb.chars_needed;
+}
+
+/*! Same as  osmo_gsup_message_to_str_buf() but returns a talloc allocated string. */
+char *osmo_gsup_message_to_str_c(void *ctx, const struct osmo_gsup_message *msg)
+{
+	OSMO_NAME_C_IMPL(ctx, 64, "ERROR", osmo_gsup_message_to_str_buf, msg)
+}

src/hlr.c

@@ -35,8 +35,10 @@
 #include <osmocom/gsm/apn.h>
 #include <osmocom/gsm/gsm48_ie.h>
 #include <osmocom/gsm/gsm_utils.h>
-#include <osmocom/gsm/protocol/gsm_23_003.h>
+#include <osmocom/gsm/gsm23003.h>
+#include <osmocom/mslookup/mslookup_client.h>
 
+#include <osmocom/gsupclient/gsup_peer_id.h>
 #include <osmocom/hlr/db.h>
 #include <osmocom/hlr/hlr.h>
 #include <osmocom/hlr/ctrl.h>
@@ -44,14 +46,23 @@
 #include <osmocom/hlr/gsup_server.h>
 #include <osmocom/hlr/gsup_router.h>
 #include <osmocom/hlr/rand.h>
-#include <osmocom/hlr/luop.h>
 #include <osmocom/hlr/hlr_vty.h>
 #include <osmocom/hlr/hlr_ussd.h>
+#include <osmocom/hlr/dgsm.h>
+#include <osmocom/hlr/proxy.h>
+#include <osmocom/hlr/lu_fsm.h>
+#include <osmocom/mslookup/mdns.h>
 
 struct hlr *g_hlr;
 static void *hlr_ctx = NULL;
 static int quit = 0;
 
+struct osmo_tdef g_hlr_tdefs[] = {
+	/* 4222 is also the OSMO_GSUP_PORT */
+	{ .T = -4222, .default_val = 30, .desc = "GSUP Update Location timeout" },
+	{}
+};
+
 /* Trigger 'Insert Subscriber Data' messages to all connected GSUP clients.
  *
  * \param[in] subscr  A subscriber we have new data to send for.
@@ -69,6 +80,8 @@ osmo_hlr_subscriber_update_notify(struct hlr_subscriber *subscr)
 		return;
 	}
 
+	/* FIXME: send only to current vlr_number and sgsn_number */
+
 	llist_for_each_entry(co, &g_hlr->gs->clients, list) {
 		struct osmo_gsup_message gsup = { };
 		uint8_t msisdn_enc[OSMO_GSUP_MAX_CALLED_PARTY_BCD_LEN];
@@ -222,140 +235,111 @@ static int subscr_create_on_demand(const char *imsi)
 	return 0;
 }
 
+/*! Update nam_cs/nam_ps in the db and trigger notifications to GSUP clients.
+ * \param[in,out] hlr  Global hlr context.
+ * \param[in] subscr   Subscriber from a fresh db_subscr_get_by_*() call.
+ * \param[in] nam_val  True to enable CS/PS, false to disable.
+ * \param[in] is_ps    True to enable/disable PS, false for CS.
+ * \returns 0 on success, ENOEXEC if there is no need to change, a negative
+ *          value on error.
+ */
+int hlr_subscr_nam(struct hlr *hlr, struct hlr_subscriber *subscr, bool nam_val, bool is_ps)
+{
+	int rc;
+	bool is_val = is_ps? subscr->nam_ps : subscr->nam_cs;
+	struct osmo_ipa_name vlr_name;
+	struct osmo_gsup_message gsup_del_data = {
+		.message_type = OSMO_GSUP_MSGT_DELETE_DATA_REQUEST,
+	};
+	OSMO_STRLCPY_ARRAY(gsup_del_data.imsi, subscr->imsi);
+
+	if (is_val == nam_val) {
+		LOGP(DAUC, LOGL_DEBUG, "IMSI-%s: Already has the requested value when asked to %s %s\n",
+		     subscr->imsi, nam_val ? "enable" : "disable", is_ps ? "PS" : "CS");
+		return ENOEXEC;
+	}
+
+	rc = db_subscr_nam(hlr->dbc, subscr->imsi, nam_val, is_ps);
+	if (rc)
+		return rc > 0? -rc : rc;
+
+	/* If we're disabling, send a notice out to the GSUP client that is
+	 * responsible. Otherwise no need. */
+	if (nam_val)
+		return 0;
+
+	if (subscr->vlr_number && osmo_ipa_name_set_str(&vlr_name, subscr->vlr_number))
+		osmo_gsup_enc_send_to_ipa_name(g_hlr->gs, &vlr_name, &gsup_del_data);
+	if (subscr->sgsn_number && osmo_ipa_name_set_str(&vlr_name, subscr->sgsn_number))
+		osmo_gsup_enc_send_to_ipa_name(g_hlr->gs, &vlr_name, &gsup_del_data);
+	return 0;
+}
+
 /***********************************************************************
  * Send Auth Info handling
  ***********************************************************************/
 
 /* process an incoming SAI request */
-static int rx_send_auth_info(struct osmo_gsup_conn *conn,
-			     const struct osmo_gsup_message *gsup,
-			     struct db_context *dbc)
+static int rx_send_auth_info(struct osmo_gsup_req *req)
 {
-	struct osmo_gsup_message gsup_out;
-	struct msgb *msg_out;
+	struct osmo_gsup_message gsup_out = {
+		.message_type = OSMO_GSUP_MSGT_SEND_AUTH_INFO_RESULT,
+	};
 	bool separation_bit = false;
+	int num_auth_vectors = OSMO_GSUP_MAX_NUM_AUTH_INFO;
+	unsigned int auc_3g_ind;
 	int rc;
 
-	subscr_create_on_demand(gsup->imsi);
+	subscr_create_on_demand(req->gsup.imsi);
 
-	/* initialize return message structure */
-	memset(&gsup_out, 0, sizeof(gsup_out));
-	memcpy(&gsup_out.imsi, &gsup->imsi, sizeof(gsup_out.imsi));
-
-	if (gsup->current_rat_type == OSMO_RAT_EUTRAN_SGS)
+	if (req->gsup.current_rat_type == OSMO_RAT_EUTRAN_SGS)
 		separation_bit = true;
 
-	rc = db_get_auc(dbc, gsup->imsi, conn->auc_3g_ind,
+	if (req->gsup.num_auth_vectors > 0 &&
+			req->gsup.num_auth_vectors <= OSMO_GSUP_MAX_NUM_AUTH_INFO)
+		num_auth_vectors = req->gsup.num_auth_vectors;
+	rc = db_ind(g_hlr->dbc, &req->source_name, &auc_3g_ind);
+	if (rc) {
+		LOG_GSUP_REQ(req, LOGL_ERROR,
+			     "Unable to determine 3G auth IND for source %s (rc=%d),"
+			     " generating tuples with IND = 0\n",
+			     osmo_gsup_peer_id_to_str(&req->source_name), rc);
+		auc_3g_ind = 0;
+	}
+
+	rc = db_get_auc(g_hlr->dbc, req->gsup.imsi, auc_3g_ind,
 			gsup_out.auth_vectors,
-			ARRAY_SIZE(gsup_out.auth_vectors),
-			gsup->rand, gsup->auts, separation_bit);
+			num_auth_vectors,
+			req->gsup.rand, req->gsup.auts, separation_bit);
+
 	if (rc <= 0) {
-		gsup_out.message_type = OSMO_GSUP_MSGT_SEND_AUTH_INFO_ERROR;
 		switch (rc) {
 		case 0:
 			/* 0 means "0 tuples generated", which shouldn't happen.
 			 * Treat the same as "no auth data". */
 		case -ENOKEY:
-			LOGP(DAUC, LOGL_NOTICE, "%s: IMSI known, but has no auth data;"
-			     " Returning slightly inaccurate cause 'IMSI Unknown' via GSUP\n",
-			     gsup->imsi);
-			gsup_out.cause = GMM_CAUSE_IMSI_UNKNOWN;
-			break;
+			osmo_gsup_req_respond_err(req, GMM_CAUSE_IMSI_UNKNOWN,
+						  "IMSI known, but has no auth data;"
+						  " Returning slightly inaccurate cause 'IMSI Unknown' via GSUP");
+			return rc;
 		case -ENOENT:
-			LOGP(DAUC, LOGL_NOTICE, "%s: IMSI not known\n", gsup->imsi);
-			gsup_out.cause = GMM_CAUSE_IMSI_UNKNOWN;
-			break;
+			osmo_gsup_req_respond_err(req, GMM_CAUSE_IMSI_UNKNOWN, "IMSI unknown");
+			return rc;
 		default:
-			LOGP(DAUC, LOGL_ERROR, "%s: failure to look up IMSI in db\n", gsup->imsi);
-			gsup_out.cause = GMM_CAUSE_NET_FAIL;
-			break;
+			osmo_gsup_req_respond_err(req, GMM_CAUSE_NET_FAIL, "failure to look up IMSI in db");
+			return rc;
 		}
-	} else {
-		gsup_out.message_type = OSMO_GSUP_MSGT_SEND_AUTH_INFO_RESULT;
-		gsup_out.num_auth_vectors = rc;
 	}
+	gsup_out.num_auth_vectors = rc;
 
-	msg_out = osmo_gsup_msgb_alloc("GSUP AUC response");
-	osmo_gsup_encode(msg_out, &gsup_out);
-	return osmo_gsup_conn_send(conn, msg_out);
+	osmo_gsup_req_respond(req, &gsup_out, false, true);
+	return 0;
 }
 
-/***********************************************************************
- * LU Operation State / Structure
- ***********************************************************************/
-
-static LLIST_HEAD(g_lu_ops);
-
-/*! Receive Cancel Location Result from old VLR/SGSN */
-void lu_op_rx_cancel_old_ack(struct lu_operation *luop,
-			     const struct osmo_gsup_message *gsup)
+/*! Receive Update Location Request, creates new lu_operation */
+static int rx_upd_loc_req(struct osmo_gsup_conn *conn, struct osmo_gsup_req *req)
 {
-	OSMO_ASSERT(luop->state == LU_S_CANCEL_SENT);
-	/* FIXME: Check for spoofing */
-
-	osmo_timer_del(&luop->timer);
-
-	/* FIXME */
-
-	lu_op_tx_insert_subscr_data(luop);
-}
-
-/*! Receive Insert Subscriber Data Result from new VLR/SGSN */
-static void lu_op_rx_insert_subscr_data_ack(struct lu_operation *luop,
-				    const struct osmo_gsup_message *gsup)
-{
-	OSMO_ASSERT(luop->state == LU_S_ISD_SENT);
-	/* FIXME: Check for spoofing */
-
-	osmo_timer_del(&luop->timer);
-
-	/* Subscriber_Present_HLR */
-	/* CS only: Check_SS_required? -> MAP-FW-CHECK_SS_IND.req */
-
-	/* Send final ACK towards inquiring VLR/SGSN */
-	lu_op_tx_ack(luop);
-}
-
-/*! Receive GSUP message for given \ref lu_operation */
-void lu_op_rx_gsup(struct lu_operation *luop,
-		  const struct osmo_gsup_message *gsup)
-{
-	switch (gsup->message_type) {
-	case OSMO_GSUP_MSGT_INSERT_DATA_ERROR:
-		/* FIXME */
-		break;
-	case OSMO_GSUP_MSGT_INSERT_DATA_RESULT:
-		lu_op_rx_insert_subscr_data_ack(luop, gsup);
-		break;
-	case OSMO_GSUP_MSGT_LOCATION_CANCEL_ERROR:
-		/* FIXME */
-		break;
-	case OSMO_GSUP_MSGT_LOCATION_CANCEL_RESULT:
-		lu_op_rx_cancel_old_ack(luop, gsup);
-		break;
-	default:
-		LOGP(DMAIN, LOGL_ERROR, "Unhandled GSUP msg_type 0x%02x\n",
-			gsup->message_type);
-		break;
-	}
-}
-
-/*! Receive Update Location Request, creates new \ref lu_operation */
-static int rx_upd_loc_req(struct osmo_gsup_conn *conn,
-			  const struct osmo_gsup_message *gsup)
-{
-	struct hlr_subscriber *subscr;
-	struct lu_operation *luop = lu_op_alloc_conn(conn);
-	if (!luop) {
-		LOGP(DMAIN, LOGL_ERROR, "LU REQ from conn without addr?\n");
-		return -EINVAL;
-	}
-
-	subscr = &luop->subscr;
-
-	lu_op_statechg(luop, LU_S_LU_RECEIVED);
-
-	switch (gsup->cn_domain) {
+	switch (req->gsup.cn_domain) {
 	case OSMO_GSUP_CN_DOMAIN_CS:
 		conn->supports_cs = true;
 		break;
@@ -366,143 +350,64 @@ static int rx_upd_loc_req(struct osmo_gsup_conn *conn,
 		 * a request, the PS Domain is assumed." */
 	case OSMO_GSUP_CN_DOMAIN_PS:
 		conn->supports_ps = true;
-		luop->is_ps = true;
 		break;
 	}
-	llist_add(&luop->list, &g_lu_ops);
 
-	subscr_create_on_demand(gsup->imsi);
-
-	/* Roughly follwing "Process Update_Location_HLR" of TS 09.02 */
-
-	/* check if subscriber is known at all */
-	if (!lu_op_fill_subscr(luop, g_hlr->dbc, gsup->imsi)) {
-		/* Send Error back: Subscriber Unknown in HLR */
-		osmo_strlcpy(luop->subscr.imsi, gsup->imsi, sizeof(luop->subscr.imsi));
-		lu_op_tx_error(luop, GMM_CAUSE_IMSI_UNKNOWN);
-		return 0;
-	}
-
-	/* Check if subscriber is generally permitted on CS or PS
-	 * service (as requested) */
-	if (!luop->is_ps && !luop->subscr.nam_cs) {
-		lu_op_tx_error(luop, GMM_CAUSE_PLMN_NOTALLOWED);
-		return 0;
-	} else if (luop->is_ps && !luop->subscr.nam_ps) {
-		lu_op_tx_error(luop, GMM_CAUSE_GPRS_NOTALLOWED);
-		return 0;
-	}
-
-	/* TODO: Set subscriber tracing = deactive in VLR/SGSN */
-
-#if 0
-	/* Cancel in old VLR/SGSN, if new VLR/SGSN differs from old */
-	if (luop->is_ps == false &&
-	    strcmp(subscr->vlr_number, vlr_number)) {
-		lu_op_tx_cancel_old(luop);
-	} else if (luop->is_ps == true &&
-		   strcmp(subscr->sgsn_number, sgsn_number)) {
-		lu_op_tx_cancel_old(luop);
-	} else
-#endif
-
-	/* Store the VLR / SGSN number with the subscriber, so we know where it was last seen. */
-	LOGP(DAUC, LOGL_DEBUG, "IMSI='%s': storing %s = %s\n",
-	     subscr->imsi, luop->is_ps ? "SGSN number" : "VLR number",
-	     osmo_quote_str((const char*)luop->peer, -1));
-	if (db_subscr_lu(g_hlr->dbc, subscr->id, (const char *)luop->peer, luop->is_ps))
-		LOGP(DAUC, LOGL_ERROR, "IMSI='%s': Cannot update %s in the database\n",
-		     subscr->imsi, luop->is_ps ? "SGSN number" : "VLR number");
-
-	/* TODO: Subscriber allowed to roam in PLMN? */
-	/* TODO: Update RoutingInfo */
-	/* TODO: Reset Flag MS Purged (cs/ps) */
-	/* TODO: Control_Tracing_HLR / Control_Tracing_HLR_with_SGSN */
-	lu_op_tx_insert_subscr_data(luop);
+	subscr_create_on_demand(req->gsup.imsi);
 
+	lu_rx_gsup(req);
 	return 0;
 }
 
-static int rx_purge_ms_req(struct osmo_gsup_conn *conn,
-			   const struct osmo_gsup_message *gsup)
+static int rx_purge_ms_req(struct osmo_gsup_req *req)
 {
-	struct osmo_gsup_message gsup_reply = {0};
-	struct msgb *msg_out;
-	bool is_ps = false;
+	bool is_ps = (req->gsup.cn_domain != OSMO_GSUP_CN_DOMAIN_CS);
 	int rc;
 
-	LOGP(DAUC, LOGL_INFO, "%s: Purge MS (%s)\n", gsup->imsi,
-		is_ps ? "PS" : "CS");
-
-	memcpy(gsup_reply.imsi, gsup->imsi, sizeof(gsup_reply.imsi));
-
-	if (gsup->cn_domain == OSMO_GSUP_CN_DOMAIN_PS)
-		is_ps = true;
+	LOG_GSUP_REQ_CAT(req, DAUC, LOGL_INFO, "Purge MS (%s)\n", is_ps ? "PS" : "CS");
 
 	/* FIXME: check if the VLR that sends the purge is the same that
 	 * we have on record. Only update if yes */
 
 	/* Perform the actual update of the DB */
-	rc = db_subscr_purge(g_hlr->dbc, gsup->imsi, true, is_ps);
+	rc = db_subscr_purge(g_hlr->dbc, req->gsup.imsi, true, is_ps);
 
 	if (rc == 0)
-		gsup_reply.message_type = OSMO_GSUP_MSGT_PURGE_MS_RESULT;
-	else if (rc == -ENOENT) {
-		gsup_reply.message_type = OSMO_GSUP_MSGT_PURGE_MS_ERROR;
-		gsup_reply.cause = GMM_CAUSE_IMSI_UNKNOWN;
-	} else {
-		gsup_reply.message_type = OSMO_GSUP_MSGT_PURGE_MS_ERROR;
-		gsup_reply.cause = GMM_CAUSE_NET_FAIL;
-	}
-
-	msg_out = osmo_gsup_msgb_alloc("GSUP AUC response");
-	osmo_gsup_encode(msg_out, &gsup_reply);
-	return osmo_gsup_conn_send(conn, msg_out);
+		osmo_gsup_req_respond_msgt(req, OSMO_GSUP_MSGT_PURGE_MS_RESULT, true);
+	else if (rc == -ENOENT)
+		osmo_gsup_req_respond_err(req, GMM_CAUSE_IMSI_UNKNOWN, "IMSI unknown");
+	else
+		osmo_gsup_req_respond_err(req, GMM_CAUSE_NET_FAIL, "db error");
+	return rc;
 }
 
-static int gsup_send_err_reply(struct osmo_gsup_conn *conn, const char *imsi,
-				enum osmo_gsup_message_type type_in, uint8_t err_cause)
+static int rx_check_imei_req(struct osmo_gsup_req *req)
 {
-	int type_err = OSMO_GSUP_TO_MSGT_ERROR(type_in);
-	struct osmo_gsup_message gsup_reply = {0};
-	struct msgb *msg_out;
-
-	OSMO_STRLCPY_ARRAY(gsup_reply.imsi, imsi);
-	gsup_reply.message_type = type_err;
-	gsup_reply.cause = err_cause;
-	msg_out = osmo_gsup_msgb_alloc("GSUP ERR response");
-	osmo_gsup_encode(msg_out, &gsup_reply);
-	LOGP(DMAIN, LOGL_NOTICE, "Tx %s\n", osmo_gsup_message_type_name(type_err));
-	return osmo_gsup_conn_send(conn, msg_out);
-}
-
-static int rx_check_imei_req(struct osmo_gsup_conn *conn, const struct osmo_gsup_message *gsup)
-{
-	struct osmo_gsup_message gsup_reply = {0};
-	struct msgb *msg_out;
+	struct osmo_gsup_message gsup_reply;
 	char imei[GSM23003_IMEI_NUM_DIGITS_NO_CHK+1] = {0};
+	const struct osmo_gsup_message *gsup = &req->gsup;
 	int rc;
 
 	/* Require IMEI */
 	if (!gsup->imei_enc) {
-		LOGP(DMAIN, LOGL_ERROR, "%s: missing IMEI\n", gsup->imsi);
-		gsup_send_err_reply(conn, gsup->imsi, gsup->message_type, GMM_CAUSE_INV_MAND_INFO);
+		osmo_gsup_req_respond_err(req, GMM_CAUSE_INV_MAND_INFO, "missing IMEI");
 		return -1;
 	}
 
 	/* Decode IMEI (fails if IMEI is too long) */
 	rc = gsm48_decode_bcd_number2(imei, sizeof(imei), gsup->imei_enc, gsup->imei_enc_len, 0);
 	if (rc < 0) {
-		LOGP(DMAIN, LOGL_ERROR, "%s: failed to decode IMEI (rc: %i)\n", gsup->imsi, rc);
-		gsup_send_err_reply(conn, gsup->imsi, gsup->message_type, GMM_CAUSE_INV_MAND_INFO);
+		osmo_gsup_req_respond_err(req, GMM_CAUSE_INV_MAND_INFO,
+					  "failed to decode IMEI %s (rc: %d)",
+					  osmo_hexdump_c(OTC_SELECT, gsup->imei_enc, gsup->imei_enc_len),
+					  rc);
 		return -1;
 	}
 
 	/* Check if IMEI is too short */
-	if (strlen(imei) != GSM23003_IMEI_NUM_DIGITS_NO_CHK) {
-		LOGP(DMAIN, LOGL_ERROR, "%s: wrong encoded IMEI length (IMEI: '%s', %lu, %i)\n", gsup->imsi, imei,
-		     strlen(imei), GSM23003_IMEI_NUM_DIGITS_NO_CHK);
-		gsup_send_err_reply(conn, gsup->imsi, gsup->message_type, GMM_CAUSE_INV_MAND_INFO);
+	if (!osmo_imei_str_valid(imei, false)) {
+		osmo_gsup_req_respond_err(req, GMM_CAUSE_INV_MAND_INFO,
+					  "invalid IMEI: %s", osmo_quote_str_c(OTC_SELECT, imei, -1));
 		return -1;
 	}
 
@@ -512,7 +417,7 @@ static int rx_check_imei_req(struct osmo_gsup_conn *conn, const struct osmo_gsup
 	if (g_hlr->store_imei) {
 		LOGP(DAUC, LOGL_DEBUG, "IMSI='%s': storing IMEI = %s\n", gsup->imsi, imei);
 		if (db_subscr_update_imei_by_imsi(g_hlr->dbc, gsup->imsi, imei) < 0) {
-			gsup_send_err_reply(conn, gsup->imsi, gsup->message_type, GMM_CAUSE_INV_MAND_INFO);
+			osmo_gsup_req_respond_err(req, GMM_CAUSE_INV_MAND_INFO, "Failed to store IMEI in HLR db");
 			return -1;
 		}
 	} else {
@@ -520,175 +425,145 @@ static int rx_check_imei_req(struct osmo_gsup_conn *conn, const struct osmo_gsup
 		LOGP(DMAIN, LOGL_INFO, "IMSI='%s': has IMEI = %s (consider setting 'store-imei')\n", gsup->imsi, imei);
 		struct hlr_subscriber subscr;
 		if (db_subscr_get_by_imsi(g_hlr->dbc, gsup->imsi, &subscr) < 0) {
-			gsup_send_err_reply(conn, gsup->imsi, gsup->message_type, GMM_CAUSE_INV_MAND_INFO);
+			osmo_gsup_req_respond_err(req, GMM_CAUSE_INV_MAND_INFO, "IMSI unknown");
 			return -1;
 		}
 	}
 
 	/* Accept all IMEIs */
-	gsup_reply.imei_result = OSMO_GSUP_IMEI_RESULT_ACK;
-	gsup_reply.message_type = OSMO_GSUP_MSGT_CHECK_IMEI_RESULT;
-	msg_out = osmo_gsup_msgb_alloc("GSUP Check_IMEI response");
-	memcpy(gsup_reply.imsi, gsup->imsi, sizeof(gsup_reply.imsi));
-	osmo_gsup_encode(msg_out, &gsup_reply);
-	return osmo_gsup_conn_send(conn, msg_out);
+	gsup_reply = (struct osmo_gsup_message){
+		.message_type = OSMO_GSUP_MSGT_CHECK_IMEI_RESULT,
+		.imei_result = OSMO_GSUP_IMEI_RESULT_ACK,
+	};
+	return osmo_gsup_req_respond(req, &gsup_reply, false, true);
 }
 
 static char namebuf[255];
 #define LOGP_GSUP_FWD(gsup, level, fmt, args ...) \
 	LOGP(DMAIN, level, "Forward %s (class=%s, IMSI=%s, %s->%s): " fmt, \
-	     osmo_gsup_message_type_name(gsup->message_type), \
-	     osmo_gsup_message_class_name(gsup->message_class), \
-	     gsup->imsi, \
-	     osmo_quote_str((const char *)gsup->source_name, gsup->source_name_len), \
-	     osmo_quote_str_buf2(namebuf, sizeof(namebuf), (const char *)gsup->destination_name, gsup->destination_name_len), \
+	     osmo_gsup_message_type_name((gsup)->message_type), \
+	     osmo_gsup_message_class_name((gsup)->message_class), \
+	     (gsup)->imsi, \
+	     osmo_quote_str((const char *)(gsup)->source_name, (gsup)->source_name_len), \
+	     osmo_quote_str_buf2(namebuf, sizeof(namebuf), (const char *)(gsup)->destination_name, (gsup)->destination_name_len), \
 	     ## args)
 
-static int read_cb_forward(struct osmo_gsup_conn *conn, struct msgb *msg, const struct osmo_gsup_message *gsup)
+static int read_cb_forward(struct osmo_gsup_req *req)
 {
 	int ret = -EINVAL;
-	struct osmo_gsup_message *gsup_err;
-
-	/* FIXME: it would be better if the msgb never were deallocated immediately by osmo_gsup_addr_send(), which a
-	 * select-loop volatile talloc context could facilitate. Then we would still be able to access gsup-> members
-	 * (pointing into the msgb) even after sending failed, and we wouldn't need to copy this data before sending: */
-	/* Prepare error message (before IEs get deallocated) */
-	gsup_err = talloc_zero(hlr_ctx, struct osmo_gsup_message);
-	OSMO_STRLCPY_ARRAY(gsup_err->imsi, gsup->imsi);
-	gsup_err->message_class = gsup->message_class;
-	gsup_err->destination_name = talloc_memdup(gsup_err, gsup->destination_name, gsup->destination_name_len);
-	gsup_err->destination_name_len = gsup->destination_name_len;
-	gsup_err->message_type = gsup->message_type;
-	gsup_err->session_state = gsup->session_state;
-	gsup_err->session_id = gsup->session_id;
-	gsup_err->source_name = talloc_memdup(gsup_err, gsup->source_name, gsup->source_name_len);
-	gsup_err->source_name_len = gsup->source_name_len;
+	const struct osmo_gsup_message *gsup = &req->gsup;
+	struct osmo_gsup_message gsup_err;
+	struct msgb *forward_msg;
+	struct osmo_ipa_name destination_name;
 
 	/* Check for routing IEs */
-	if (!gsup->source_name || !gsup->source_name_len || !gsup->destination_name || !gsup->destination_name_len) {
-		LOGP_GSUP_FWD(gsup, LOGL_ERROR, "missing routing IEs\n");
-		goto end;
+	if (!req->gsup.source_name || !req->gsup.source_name_len
+	    || !req->gsup.destination_name || !req->gsup.destination_name_len) {
+		LOGP_GSUP_FWD(&req->gsup, LOGL_ERROR, "missing routing IEs\n");
+		goto routing_error;
 	}
 
-	/* Verify source name (e.g. "MSC-00-00-00-00-00-00") */
-	if (gsup_route_find(conn->server, gsup->source_name, gsup->source_name_len) != conn) {
-		LOGP_GSUP_FWD(gsup, LOGL_ERROR, "mismatching source name\n");
-		goto end;
+	if (osmo_ipa_name_set(&destination_name, req->gsup.destination_name, req->gsup.destination_name_len)) {
+		LOGP_GSUP_FWD(&req->gsup, LOGL_ERROR, "invalid destination name\n");
+		goto routing_error;
 	}
 
-	/* Forward message without re-encoding (so we don't remove unknown IEs) */
-	LOGP_GSUP_FWD(gsup, LOGL_INFO, "checks passed, forwarding\n");
+	LOG_GSUP_REQ(req, LOGL_INFO, "Forwarding to %s\n", osmo_ipa_name_to_str(&destination_name));
 
-	/* Remove incoming IPA header to be able to prepend an outgoing IPA header */
-	msgb_pull_to_l2(msg);
-	ret = osmo_gsup_addr_send(g_hlr->gs, gsup->destination_name, gsup->destination_name_len, msg);
-	/* AT THIS POINT, THE msg MAY BE DEALLOCATED and the data like gsup->imsi, gsup->source_name etc may all be
-	 * invalid and cause segfaults. */
-	msg = NULL;
-	gsup = NULL;
-	if (ret == -ENODEV)
-		LOGP_GSUP_FWD(gsup_err, LOGL_ERROR, "destination not connected\n");
-	else if (ret)
-		LOGP_GSUP_FWD(gsup_err, LOGL_ERROR, "unknown error %i\n", ret);
-
-end:
-	/* Send error back to source */
+	/* Forward message without re-encoding (so we don't remove unknown IEs).
+	 * Copy GSUP part to forward, removing incoming IPA header to be able to prepend an outgoing IPA header */
+	forward_msg = osmo_gsup_msgb_alloc("GSUP forward");
+	forward_msg->l2h = msgb_put(forward_msg, msgb_l2len(req->msg));
+	memcpy(forward_msg->l2h, msgb_l2(req->msg), msgb_l2len(req->msg));
+	ret = osmo_gsup_send_to_ipa_name(g_hlr->gs, &destination_name, forward_msg);
 	if (ret) {
-		struct msgb *msg_err = osmo_gsup_msgb_alloc("GSUP forward ERR response");
-		gsup_err->message_type = OSMO_GSUP_MSGT_E_ROUTING_ERROR;
-		osmo_gsup_encode(msg_err, gsup_err);
-		LOGP_GSUP_FWD(gsup_err, LOGL_NOTICE, "Tx %s\n", osmo_gsup_message_type_name(gsup_err->message_type));
-		osmo_gsup_conn_send(conn, msg_err);
+		LOGP_GSUP_FWD(gsup, LOGL_ERROR, "%s (rc=%d)\n",
+			      ret == -ENODEV ? "destination not connected" : "unknown error",
+			      ret);
+		goto routing_error;
 	}
-	talloc_free(gsup_err);
-	if (msg)
-		msgb_free(msg);
-	return ret;
+	osmo_gsup_req_free(req);
+	return 0;
+
+routing_error:
+	gsup_err = (struct osmo_gsup_message){
+		.message_type = OSMO_GSUP_MSGT_ROUTING_ERROR,
+		.source_name = gsup->destination_name,
+		.source_name_len = gsup->destination_name_len,
+	};
+	osmo_gsup_req_respond(req, &gsup_err, true, true);
+	return -1;
 }
 
 static int read_cb(struct osmo_gsup_conn *conn, struct msgb *msg)
 {
-	static struct osmo_gsup_message gsup;
-	int rc;
-
-	if (!msgb_l2(msg) || !msgb_l2len(msg)) {
-		LOGP(DMAIN, LOGL_ERROR, "missing or empty L2 data\n");
-		msgb_free(msg);
+	struct osmo_gsup_req *req = osmo_gsup_conn_rx(conn, msg);
+	if (!req)
 		return -EINVAL;
+
+	/* If the GSUP recipient is other than this HLR, forward. */
+	if (req->gsup.destination_name_len) {
+		struct osmo_ipa_name destination_name;
+		struct osmo_ipa_name my_name;
+		osmo_ipa_name_set_str(&my_name, g_hlr->gsup_unit_name.serno);
+		if (!osmo_ipa_name_set(&destination_name, req->gsup.destination_name, req->gsup.destination_name_len)
+		    && osmo_ipa_name_cmp(&destination_name, &my_name)) {
+			return read_cb_forward(req);
+		}
 	}
 
-	rc = osmo_gsup_decode(msgb_l2(msg), msgb_l2len(msg), &gsup);
-	if (rc < 0) {
-		LOGP(DMAIN, LOGL_ERROR, "error in GSUP decode: %d\n", rc);
-		msgb_free(msg);
-		return rc;
+	/* Distributed GSM: check whether to proxy for / lookup a remote HLR.
+	 * It would require less database hits to do this only if a local-only operation fails with "unknown IMSI", but
+	 * it becomes semantically easier if we do this once-off ahead of time. */
+	if (osmo_mslookup_client_active(g_hlr->mslookup.client.client)
+	    || osmo_sockaddr_str_is_nonzero(&g_hlr->mslookup.client.gsup_gateway_proxy)) {
+		if (dgsm_check_forward_gsup_msg(req))
+			return 0;
 	}
 
-	/* 3GPP TS 23.003 Section 2.2 clearly states that an IMSI with less than 5
-	 * digits is impossible.  Even 5 digits is a highly theoretical case */
-	if (strlen(gsup.imsi) < 5) { /* TODO: move this check to libosmogsm/gsup.c? */
-		LOGP(DMAIN, LOGL_ERROR, "IMSI too short: %s\n", osmo_quote_str(gsup.imsi, -1));
-		gsup_send_err_reply(conn, gsup.imsi, gsup.message_type, GMM_CAUSE_INV_MAND_INFO);
-		msgb_free(msg);
-		return -EINVAL;
-	}
-
-	if (gsup.destination_name_len)
-		return read_cb_forward(conn, msg, &gsup);
-
-	switch (gsup.message_type) {
+	/* HLR related messages that are handled at this HLR instance */
+	switch (req->gsup.message_type) {
 	/* requests sent to us */
 	case OSMO_GSUP_MSGT_SEND_AUTH_INFO_REQUEST:
-		rx_send_auth_info(conn, &gsup, g_hlr->dbc);
+		rx_send_auth_info(req);
 		break;
 	case OSMO_GSUP_MSGT_UPDATE_LOCATION_REQUEST:
-		rx_upd_loc_req(conn, &gsup);
+		rx_upd_loc_req(conn, req);
 		break;
 	case OSMO_GSUP_MSGT_PURGE_MS_REQUEST:
-		rx_purge_ms_req(conn, &gsup);
+		rx_purge_ms_req(req);
 		break;
 	/* responses to requests sent by us */
 	case OSMO_GSUP_MSGT_DELETE_DATA_ERROR:
-		LOGP(DMAIN, LOGL_ERROR, "Error while deleting subscriber data "
-		     "for IMSI %s\n", gsup.imsi);
+		LOG_GSUP_REQ(req, LOGL_ERROR, "Peer responds with: Error while deleting subscriber data\n");
+		osmo_gsup_req_free(req);
 		break;
 	case OSMO_GSUP_MSGT_DELETE_DATA_RESULT:
-		LOGP(DMAIN, LOGL_ERROR, "Deleting subscriber data for IMSI %s\n",
-		     gsup.imsi);
+		LOG_GSUP_REQ(req, LOGL_DEBUG, "Peer responds with: Subscriber data deleted\n");
+		osmo_gsup_req_free(req);
 		break;
 	case OSMO_GSUP_MSGT_PROC_SS_REQUEST:
 	case OSMO_GSUP_MSGT_PROC_SS_RESULT:
-		rx_proc_ss_req(conn, &gsup);
+		rx_proc_ss_req(req);
 		break;
 	case OSMO_GSUP_MSGT_PROC_SS_ERROR:
-		rx_proc_ss_error(conn, &gsup);
+		rx_proc_ss_error(req);
 		break;
 	case OSMO_GSUP_MSGT_INSERT_DATA_ERROR:
 	case OSMO_GSUP_MSGT_INSERT_DATA_RESULT:
 	case OSMO_GSUP_MSGT_LOCATION_CANCEL_ERROR:
 	case OSMO_GSUP_MSGT_LOCATION_CANCEL_RESULT:
-		{
-			struct lu_operation *luop = lu_op_by_imsi(gsup.imsi,
-								  &g_lu_ops);
-			if (!luop) {
-				LOGP(DMAIN, LOGL_ERROR, "GSUP message %s for "
-				     "unknown IMSI %s\n",
-				     osmo_gsup_message_type_name(gsup.message_type),
-					gsup.imsi);
-				break;
-			}
-			lu_op_rx_gsup(luop, &gsup);
-		}
+		lu_rx_gsup(req);
 		break;
 	case OSMO_GSUP_MSGT_CHECK_IMEI_REQUEST:
-		rx_check_imei_req(conn, &gsup);
+		rx_check_imei_req(req);
 		break;
 	default:
 		LOGP(DMAIN, LOGL_DEBUG, "Unhandled GSUP message type %s\n",
-		     osmo_gsup_message_type_name(gsup.message_type));
+		     osmo_gsup_message_type_name(req->gsup.message_type));
+		osmo_gsup_req_free(req);
 		break;
 	}
-	msgb_free(msg);
 	return 0;
 }
 
@@ -841,10 +716,12 @@ int main(int argc, char **argv)
 
 	g_hlr = talloc_zero(hlr_ctx, struct hlr);
 	INIT_LLIST_HEAD(&g_hlr->euse_list);
-	INIT_LLIST_HEAD(&g_hlr->iuse_list);
 	INIT_LLIST_HEAD(&g_hlr->ss_sessions);
 	INIT_LLIST_HEAD(&g_hlr->ussd_routes);
+	INIT_LLIST_HEAD(&g_hlr->mslookup.server.local_site_services);
 	g_hlr->db_file_path = talloc_strdup(g_hlr, HLR_DEFAULT_DB_FILE_PATH);
+	g_hlr->mslookup.server.mdns.domain_suffix = talloc_strdup(g_hlr, OSMO_MDNS_DOMAIN_SUFFIX_DEFAULT);
+	g_hlr->mslookup.client.mdns.domain_suffix = talloc_strdup(g_hlr, OSMO_MDNS_DOMAIN_SUFFIX_DEFAULT);
 
 	/* Init default (call independent) SS session guard timeout value */
 	g_hlr->ncss_guard_timeout = NCSS_GUARD_TIMEOUT_DEFAULT;
@@ -855,11 +732,15 @@ int main(int argc, char **argv)
 		exit(1);
 	}
 
+	/* Set up llists and objects, startup is happening from VTY commands. */
+	dgsm_init(hlr_ctx);
+
 	osmo_stats_init(hlr_ctx);
 	vty_init(&vty_info);
 	ctrl_vty_init(hlr_ctx);
 	handle_options(argc, argv);
 	hlr_vty_init();
+	dgsm_vty_init();
 
 	rc = vty_read_config_file(cmdline_opts.config_file, NULL);
 	if (rc < 0) {
@@ -904,15 +785,18 @@ int main(int argc, char **argv)
 
 
 	g_hlr->gs = osmo_gsup_server_create(hlr_ctx, g_hlr->gsup_bind_addr, OSMO_GSUP_PORT,
-					    read_cb, &g_lu_ops, g_hlr);
+					    read_cb, g_hlr);
 	if (!g_hlr->gs) {
 		LOGP(DMAIN, LOGL_FATAL, "Error starting GSUP server\n");
 		exit(1);
 	}
+	proxy_init(g_hlr->gs);
 
 	g_hlr->ctrl_bind_addr = ctrl_vty_get_bind_addr();
 	g_hlr->ctrl = hlr_controlif_setup(g_hlr);
 
+	dgsm_start(hlr_ctx);
+
 	osmo_init_ignore_signals();
 	signal(SIGINT, &signal_hdlr);
 	signal(SIGTERM, &signal_hdlr);
@@ -927,7 +811,9 @@ int main(int argc, char **argv)
 	}
 
 	while (!quit)
-		osmo_select_main(0);
+		osmo_select_main_ctx(0);
+
+	dgsm_stop();
 
 	osmo_gsup_server_destroy(g_hlr->gs);
 	db_close(g_hlr->dbc);

src/hlr_ussd.c

@@ -170,12 +170,14 @@ struct ss_session {
 	/* subscriber's vlr_number
 	 * MO USSD: originating MSC's vlr_number
 	 * MT USSD: looked up once per session and cached here */
-	uint8_t *vlr_number;
-	size_t vlr_number_len;
+	struct osmo_ipa_name vlr_name;
 
 	/* we don't keep a pointer to the osmo_gsup_{route,conn} towards the MSC/VLR here,
 	 * as this might change during inter-VLR hand-over, and we simply look-up the serving MSC/VLR
 	 * every time we receive an USSD component from the EUSE */
+
+	struct osmo_gsup_req *initial_req_from_ms;
+	struct osmo_gsup_req *initial_req_from_euse;
 };
 
 struct ss_session *ss_session_find(struct hlr *hlr, const char *imsi, uint32_t session_id)
@@ -191,6 +193,10 @@ struct ss_session *ss_session_find(struct hlr *hlr, const char *imsi, uint32_t s
 void ss_session_free(struct ss_session *ss)
 {
 	osmo_timer_del(&ss->timeout);
+	if (ss->initial_req_from_ms)
+		osmo_gsup_req_free(ss->initial_req_from_ms);
+	if (ss->initial_req_from_euse)
+		osmo_gsup_req_free(ss->initial_req_from_euse);
 	llist_del(&ss->list);
 	talloc_free(ss);
 }
@@ -230,32 +236,46 @@ struct ss_session *ss_session_alloc(struct hlr *hlr, const char *imsi, uint32_t
  ***********************************************************************/
 
 /* Resolve the target MSC by ss->imsi and send GSUP message. */
-static int ss_gsup_send(struct ss_session *ss, struct osmo_gsup_server *gs, struct msgb *msg)
+static int ss_gsup_send_to_ms(struct ss_session *ss, struct osmo_gsup_server *gs, struct osmo_gsup_message *gsup)
 {
 	struct hlr_subscriber subscr = {};
+	struct msgb *msg;
 	int rc;
 
+	if (ss->initial_req_from_ms) {
+		/* Use non-final osmo_gsup_req_respond() to not deallocate the ss->initial_req_from_ms */
+		osmo_gsup_req_respond(ss->initial_req_from_ms, gsup, false, false);
+		return 0;
+	}
+
+	msg = osmo_gsup_msgb_alloc("GSUP USSD FW");
+	rc = osmo_gsup_encode(msg, gsup);
+	if (rc) {
+		LOGPSS(ss, LOGL_ERROR, "Failed to encode GSUP message\n");
+		msgb_free(msg);
+		return rc;
+	}
+
 	/* Use vlr_number as looked up by the caller, or look up now. */
-	if (!ss->vlr_number) {
+	if (!ss->vlr_name.len) {
 		rc = db_subscr_get_by_imsi(g_hlr->dbc, ss->imsi, &subscr);
 		if (rc < 0) {
 			LOGPSS(ss, LOGL_ERROR, "Cannot find subscriber, cannot route GSUP message\n");
 			msgb_free(msg);
 			return -EINVAL;
 		}
-		ss->vlr_number = (uint8_t *)talloc_strdup(ss, subscr.vlr_number);
-		ss->vlr_number_len = strlen(subscr.vlr_number) + 1;
+		osmo_ipa_name_set_str(&ss->vlr_name, subscr.vlr_number);
 	}
 
 	/* Check for empty string (all vlr_number strings end in "\0", because otherwise gsup_route_find() fails) */
-	if (ss->vlr_number_len == 1) {
+	if (ss->vlr_name.len <= 1) {
 		LOGPSS(ss, LOGL_ERROR, "Cannot send GSUP message, no VLR number stored for subscriber\n");
 		msgb_free(msg);
 		return -EINVAL;
 	}
 
-	LOGPSS(ss, LOGL_DEBUG, "Tx SS/USSD to VLR %s\n", osmo_quote_str((char *)ss->vlr_number, ss->vlr_number_len));
-	return osmo_gsup_addr_send(gs, ss->vlr_number, ss->vlr_number_len, msg);
+	LOGPSS(ss, LOGL_DEBUG, "Tx SS/USSD to VLR %s\n", osmo_ipa_name_to_str(&ss->vlr_name));
+	return osmo_gsup_send_to_ipa_name(gs, &ss->vlr_name, msg);
 }
 
 static int ss_tx_to_ms(struct ss_session *ss, enum osmo_gsup_message_type gsup_msg_type,
@@ -263,7 +283,7 @@ static int ss_tx_to_ms(struct ss_session *ss, enum osmo_gsup_message_type gsup_m
 
 {
 	struct osmo_gsup_message resp = {0};
-	struct msgb *resp_msg;
+	int rc;
 
 	resp.message_type = gsup_msg_type;
 	OSMO_STRLCPY_ARRAY(resp.imsi, ss->imsi);
@@ -277,12 +297,10 @@ static int ss_tx_to_ms(struct ss_session *ss, enum osmo_gsup_message_type gsup_m
 		resp.ss_info_len = msgb_length(ss_msg);
 	}
 
-	resp_msg = msgb_alloc_headroom(4000, 64, __func__);
-	OSMO_ASSERT(resp_msg);
-	osmo_gsup_encode(resp_msg, &resp);
-	msgb_free(ss_msg);
+	rc = ss_gsup_send_to_ms(ss, g_hlr->gs, &resp);
 
-	return ss_gsup_send(ss, g_hlr->gs, resp_msg);
+	msgb_free(ss_msg);
+	return rc;
 }
 
 #if 0
@@ -297,7 +315,7 @@ static int ss_tx_reject(struct ss_session *ss, int invoke_id, uint8_t problem_ta
 }
 #endif
 
-static int ss_tx_error(struct ss_session *ss, uint8_t invoke_id, uint8_t error_code)
+static int ss_tx_to_ms_error(struct ss_session *ss, uint8_t invoke_id, uint8_t error_code)
 {
 	struct msgb *msg = gsm0480_gen_return_error(invoke_id, error_code);
 	LOGPSS(ss, LOGL_NOTICE, "Tx ReturnError(%u, 0x%02x)\n", invoke_id, error_code);
@@ -305,7 +323,7 @@ static int ss_tx_error(struct ss_session *ss, uint8_t invoke_id, uint8_t error_c
 	return ss_tx_to_ms(ss, OSMO_GSUP_MSGT_PROC_SS_RESULT, true, msg);
 }
 
-static int ss_tx_ussd_7bit(struct ss_session *ss, bool final, uint8_t invoke_id, const char *text)
+static int ss_tx_to_ms_ussd_7bit(struct ss_session *ss, bool final, uint8_t invoke_id, const char *text)
 {
 	struct msgb *msg = gsm0480_gen_ussd_resp_7bit(invoke_id, text);
 	LOGPSS(ss, LOGL_INFO, "Tx USSD '%s'\n", text);
@@ -319,7 +337,7 @@ static int ss_tx_ussd_7bit(struct ss_session *ss, bool final, uint8_t invoke_id,
 
 #include <osmocom/hlr/db.h>
 
-static int handle_ussd_own_msisdn(struct osmo_gsup_conn *conn, struct ss_session *ss,
+static int handle_ussd_own_msisdn(struct ss_session *ss,
 				  const struct osmo_gsup_message *gsup, const struct ss_request *req)
 {
 	struct hlr_subscriber subscr;
@@ -333,25 +351,25 @@ static int handle_ussd_own_msisdn(struct osmo_gsup_conn *conn, struct ss_session
 			snprintf(buf, sizeof(buf), "You have no MSISDN!");
 		else
 			snprintf(buf, sizeof(buf), "Your extension is %s", subscr.msisdn);
-		ss_tx_ussd_7bit(ss, true, req->invoke_id, buf);
+		ss_tx_to_ms_ussd_7bit(ss, true, req->invoke_id, buf);
 		break;
 	case -ENOENT:
-		ss_tx_error(ss, req->invoke_id, GSM0480_ERR_CODE_UNKNOWN_SUBSCRIBER);
+		ss_tx_to_ms_error(ss, req->invoke_id, GSM0480_ERR_CODE_UNKNOWN_SUBSCRIBER);
 		break;
 	case -EIO:
 	default:
-		ss_tx_error(ss, req->invoke_id, GSM0480_ERR_CODE_SYSTEM_FAILURE);
+		ss_tx_to_ms_error(ss, req->invoke_id, GSM0480_ERR_CODE_SYSTEM_FAILURE);
 		break;
 	}
 	return 0;
 }
 
-static int handle_ussd_own_imsi(struct osmo_gsup_conn *conn, struct ss_session *ss,
+static int handle_ussd_own_imsi(struct ss_session *ss,
 				const struct osmo_gsup_message *gsup, const struct ss_request *req)
 {
 	char buf[GSM0480_USSD_7BIT_STRING_LEN+1];
 	snprintf(buf, sizeof(buf), "Your IMSI is %s", ss->imsi);
-	ss_tx_ussd_7bit(ss, true, req->invoke_id, buf);
+	ss_tx_to_ms_ussd_7bit(ss, true, req->invoke_id, buf);
 	return 0;
 }
 
@@ -398,37 +416,28 @@ static bool ss_op_is_ussd(uint8_t opcode)
 }
 
 /* is this GSUP connection an EUSE (true) or not (false)? */
-static bool conn_is_euse(struct osmo_gsup_conn *conn)
+static bool peer_name_is_euse(const struct osmo_gsup_peer_id *peer_name)
 {
-	int rc;
-	uint8_t *addr;
-
-	rc = osmo_gsup_conn_ccm_get(conn, &addr, IPAC_IDTAG_SERNR);
-	if (rc <= 5)
+	if (peer_name->type != OSMO_GSUP_PEER_ID_IPA_NAME)
 		return false;
-	if (!strncmp((char *)addr, "EUSE-", 5))
-		return true;
-	else
+	if (peer_name->ipa_name.len <= 5)
 		return false;
+	return strncmp((char *)(peer_name->ipa_name.val), "EUSE-", 5) == 0;
 }
 
-static struct hlr_euse *euse_by_conn(struct osmo_gsup_conn *conn)
+static struct hlr_euse *euse_by_name(const struct osmo_gsup_peer_id *peer_name)
 {
-	int rc;
-	char *addr;
-	struct hlr *hlr = conn->server->priv;
-
-	rc = osmo_gsup_conn_ccm_get(conn, (uint8_t **) &addr, IPAC_IDTAG_SERNR);
-	if (rc <= 5)
-		return NULL;
-	if (strncmp(addr, "EUSE-", 5))
+	if (!peer_name_is_euse(peer_name))
 		return NULL;
 
-	return euse_find(hlr, addr+5);
+	/* above peer_name_is_euse() ensures this: */
+	OSMO_ASSERT(peer_name->type == OSMO_GSUP_PEER_ID_IPA_NAME);
+
+	return euse_find(g_hlr, (const char*)(peer_name->ipa_name.val)+5);
 }
 
-static int handle_ss(struct ss_session *ss, const struct osmo_gsup_message *gsup,
-			const struct ss_request *req)
+static int handle_ss(struct ss_session *ss, bool is_euse_originated, const struct osmo_gsup_message *gsup,
+		     const struct ss_request *req)
 {
 	uint8_t comp_type = gsup->ss_info[0];
 
@@ -441,17 +450,16 @@ static int handle_ss(struct ss_session *ss, const struct osmo_gsup_message *gsup
 	 * we don't handle "structured" SS requests at all.
 	 */
 	LOGPSS(ss, LOGL_NOTICE, "Structured SS requests are not supported, rejecting...\n");
-	ss_tx_error(ss, req->invoke_id, GSM0480_ERR_CODE_FACILITY_NOT_SUPPORTED);
+	ss_tx_to_ms_error(ss, req->invoke_id, GSM0480_ERR_CODE_FACILITY_NOT_SUPPORTED);
 	return -ENOTSUP;
 }
 
 /* Handle a USSD GSUP message for a given SS Session received from VLR or EUSE */
-static int handle_ussd(struct osmo_gsup_conn *conn, struct ss_session *ss,
-			const struct osmo_gsup_message *gsup, const struct ss_request *req)
+static int handle_ussd(struct ss_session *ss, bool is_euse_originated, const struct osmo_gsup_message *gsup,
+		       const struct ss_request *req)
 {
 	uint8_t comp_type = gsup->ss_info[0];
 	struct msgb *msg_out;
-	bool is_euse_originated = conn_is_euse(conn);
 
 	LOGPSS(ss, LOGL_INFO, "USSD CompType=%s, OpCode=%s '%s'\n",
 		gsm0480_comp_type_name(comp_type), gsm0480_op_code_name(req->opcode),
@@ -459,26 +467,27 @@ static int handle_ussd(struct osmo_gsup_conn *conn, struct ss_session *ss,
 
 	if ((ss->is_external && !ss->u.euse) || !ss->u.iuse) {
 		LOGPSS(ss, LOGL_NOTICE, "USSD for unknown code '%s'\n", req->ussd_text);
-		ss_tx_error(ss, req->invoke_id, GSM0480_ERR_CODE_SS_NOT_AVAILABLE);
+		ss_tx_to_ms_error(ss, req->invoke_id, GSM0480_ERR_CODE_SS_NOT_AVAILABLE);
 		return 0;
 	}
 
 	if (is_euse_originated) {
-		msg_out = osmo_gsup_msgb_alloc("GSUP USSD FW");
 		/* Received from EUSE, Forward to VLR */
-		osmo_gsup_encode(msg_out, gsup);
-		ss_gsup_send(ss, conn->server, msg_out);
+		/* Need a non-const osmo_gsup_message, because sending might modify some (routing related?) parts. */
+		struct osmo_gsup_message forward = *gsup;
+		ss_gsup_send_to_ms(ss, g_hlr->gs, &forward);
 	} else {
 		/* Received from VLR (MS) */
 		if (ss->is_external) {
 			/* Forward to EUSE */
-			char addr[128];
-			strcpy(addr, "EUSE-");
-			osmo_strlcpy(addr+5, ss->u.euse->name, sizeof(addr)-5);
-			conn = gsup_route_find(conn->server, (uint8_t *)addr, strlen(addr)+1);
+			struct osmo_ipa_name euse_name;
+			struct osmo_gsup_conn *conn;
+			osmo_ipa_name_set_str(&euse_name, "EUSE-%s", ss->u.euse->name);
+			conn = gsup_route_find_by_ipa_name(g_hlr->gs, &euse_name);
 			if (!conn) {
-				LOGPSS(ss, LOGL_ERROR, "Cannot find conn for EUSE %s\n", addr);
-				ss_tx_error(ss, req->invoke_id, GSM0480_ERR_CODE_SYSTEM_FAILURE);
+				LOGPSS(ss, LOGL_ERROR, "Cannot find conn for EUSE %s\n",
+				       osmo_ipa_name_to_str(&euse_name));
+				ss_tx_to_ms_error(ss, req->invoke_id, GSM0480_ERR_CODE_SYSTEM_FAILURE);
 			} else {
 				msg_out = osmo_gsup_msgb_alloc("GSUP USSD FW");
 				osmo_gsup_encode(msg_out, gsup);
@@ -486,7 +495,7 @@ static int handle_ussd(struct osmo_gsup_conn *conn, struct ss_session *ss,
 			}
 		} else {
 			/* Handle internally */
-			ss->u.iuse->handle_ussd(conn, ss, gsup, req);
+			ss->u.iuse->handle_ussd(ss, gsup, req);
 			/* Release session immediately */
 			ss_session_free(ss);
 		}
@@ -498,30 +507,43 @@ static int handle_ussd(struct osmo_gsup_conn *conn, struct ss_session *ss,
 
 /* this function is called for any SS_REQ/SS_RESP messages from both the MSC/VLR side as well
  * as from the EUSE side */
-int rx_proc_ss_req(struct osmo_gsup_conn *conn, const struct osmo_gsup_message *gsup)
+void rx_proc_ss_req(struct osmo_gsup_req *gsup_req)
 {
-	struct hlr *hlr = conn->server->priv;
+	struct hlr *hlr = g_hlr;
 	struct ss_session *ss;
 	struct ss_request req = {0};
-	struct gsup_route *gsup_rt;
+	const struct osmo_gsup_message *gsup = &gsup_req->gsup;
+	/* Remember whether this function should free the incoming gsup_req: if it is placed as ss->initial_req_from_*,
+	 * do not free it here. If not, free it here. */
+	struct osmo_gsup_req *free_gsup_req = gsup_req;
+	bool is_euse_originated = peer_name_is_euse(&gsup_req->source_name);
 
 	LOGP(DSS, LOGL_DEBUG, "%s/0x%08x: Process SS (%s)\n", gsup->imsi, gsup->session_id,
 		osmo_gsup_session_state_name(gsup->session_state));
 
+	if (gsup_req->source_name.type != OSMO_GSUP_PEER_ID_IPA_NAME) {
+		LOGP(DSS, LOGL_ERROR, "%s/0x%082x: Unable to process SS request: Unsupported GSUP peer id type%s\n",
+		     gsup->imsi, gsup->session_id,
+		     osmo_gsup_peer_id_type_name(gsup_req->source_name.type));
+		osmo_gsup_req_respond_err(gsup_req, GMM_CAUSE_PROTO_ERR_UNSPEC, "error processing SS request");
+		return;
+	}
+
 	/* decode and find out what kind of SS message it is */
 	if (gsup->ss_info && gsup->ss_info_len) {
 		if (gsm0480_parse_facility_ie(gsup->ss_info, gsup->ss_info_len, &req)) {
 			LOGP(DSS, LOGL_ERROR, "%s/0x%082x: Unable to parse SS request: %s\n",
 				gsup->imsi, gsup->session_id,
 				osmo_hexdump(gsup->ss_info, gsup->ss_info_len));
-			/* FIXME: Send a Reject component? */
-			goto out_err;
+			osmo_gsup_req_respond_err(gsup_req, GMM_CAUSE_INV_MAND_INFO, "error parsing SS request");
+			return;
 		}
 	} else if (gsup->session_state != OSMO_GSUP_SESSION_STATE_END) {
 		LOGP(DSS, LOGL_ERROR, "%s/0x%082x: Missing SS payload for '%s'\n",
 		     gsup->imsi, gsup->session_id,
 		     osmo_gsup_session_state_name(gsup->session_state));
-		goto out_err;
+		osmo_gsup_req_respond_err(gsup_req, GMM_CAUSE_INV_MAND_INFO, "missing SS payload");
+		return;
 	}
 
 	switch (gsup->session_state) {
@@ -530,32 +552,30 @@ int rx_proc_ss_req(struct osmo_gsup_conn *conn, const struct osmo_gsup_message *
 		if (ss_session_find(hlr, gsup->imsi, gsup->session_id)) {
 			LOGP(DSS, LOGL_ERROR, "%s/0x%08x: BEGIN with non-unique session ID!\n",
 				gsup->imsi, gsup->session_id);
-			goto out_err;
+			osmo_gsup_req_respond_err(gsup_req, GMM_CAUSE_INV_MAND_INFO, "BEGIN with non-unique session ID");
+			return;
 		}
 		ss = ss_session_alloc(hlr, gsup->imsi, gsup->session_id);
 		if (!ss) {
 			LOGP(DSS, LOGL_ERROR, "%s/0x%08x: Unable to allocate SS session\n",
 				gsup->imsi, gsup->session_id);
-			goto out_err;
+			osmo_gsup_req_respond_err(gsup_req, GMM_CAUSE_NET_FAIL, "Unable to allocate SS session");
+			return;
 		}
 		/* Get IPA name from VLR conn and save as ss->vlr_number */
-		if (!conn_is_euse(conn)) {
-			gsup_rt = gsup_route_find_by_conn(conn);
-			if (gsup_rt) {
-				ss->vlr_number = (uint8_t *)talloc_strdup(ss, (const char *)gsup_rt->addr);
-				ss->vlr_number_len = strlen((const char *)gsup_rt->addr) + 1;
-				LOGPSS(ss, LOGL_DEBUG, "Destination IPA name retrieved from GSUP route: %s\n",
-				       osmo_quote_str((const char *)ss->vlr_number, ss->vlr_number_len));
-			} else {
-				LOGPSS(ss, LOGL_NOTICE, "Could not find GSUP route, therefore can't set the destination"
-							" IPA name. We'll try to look it up later, but this should not"
-							" have happened.\n");
-			}
+		if (!is_euse_originated) {
+			ss->initial_req_from_ms = gsup_req;
+			free_gsup_req = NULL;
+			OSMO_ASSERT(gsup_req->source_name.type == OSMO_GSUP_PEER_ID_IPA_NAME); /* checked above */
+			ss->vlr_name = gsup_req->source_name.ipa_name;
+		} else {
+			ss->initial_req_from_euse = gsup_req;
+			free_gsup_req = NULL;
 		}
 		if (ss_op_is_ussd(req.opcode)) {
-			if (conn_is_euse(conn)) {
+			if (is_euse_originated) {
 				/* EUSE->VLR: MT USSD. EUSE is known ('conn'), VLR is to be resolved */
-				ss->u.euse = euse_by_conn(conn);
+				ss->u.euse = euse_by_name(&gsup_req->source_name);
 			} else {
 				/* VLR->EUSE: MO USSD. VLR is known ('conn'), EUSE is to be resolved */
 				struct hlr_ussd_route *rt;
@@ -576,10 +596,10 @@ int rx_proc_ss_req(struct osmo_gsup_conn *conn, const struct osmo_gsup_message *
 				}
 			}
 			/* dispatch unstructured SS to routing */
-			handle_ussd(conn, ss, gsup, &req);
+			handle_ussd(ss, is_euse_originated, &gsup_req->gsup, &req);
 		} else {
 			/* dispatch non-call SS to internal code */
-			handle_ss(ss, gsup, &req);
+			handle_ss(ss, is_euse_originated, &gsup_req->gsup, &req);
 		}
 		break;
 	case OSMO_GSUP_SESSION_STATE_CONTINUE:
@@ -587,7 +607,8 @@ int rx_proc_ss_req(struct osmo_gsup_conn *conn, const struct osmo_gsup_message *
 		if (!ss) {
 			LOGP(DSS, LOGL_ERROR, "%s/0x%08x: CONTINUE for unknown SS session\n",
 				gsup->imsi, gsup->session_id);
-			goto out_err;
+			osmo_gsup_req_respond_err(gsup_req, GMM_CAUSE_INV_MAND_INFO, "CONTINUE for unknown SS session");
+			return;
 		}
 
 		/* Reschedule self-destruction timer */
@@ -596,10 +617,10 @@ int rx_proc_ss_req(struct osmo_gsup_conn *conn, const struct osmo_gsup_message *
 
 		if (ss_op_is_ussd(req.opcode)) {
 			/* dispatch unstructured SS to routing */
-			handle_ussd(conn, ss, gsup, &req);
+			handle_ussd(ss, is_euse_originated, &gsup_req->gsup, &req);
 		} else {
 			/* dispatch non-call SS to internal code */
-			handle_ss(ss, gsup, &req);
+			handle_ss(ss, is_euse_originated, &gsup_req->gsup, &req);
 		}
 		break;
 	case OSMO_GSUP_SESSION_STATE_END:
@@ -607,17 +628,17 @@ int rx_proc_ss_req(struct osmo_gsup_conn *conn, const struct osmo_gsup_message *
 		if (!ss) {
 			LOGP(DSS, LOGL_ERROR, "%s/0x%08x: END for unknown SS session\n",
 				gsup->imsi, gsup->session_id);
-			goto out_err;
+			return;
 		}
 
 		/* SS payload is optional for END */
 		if (gsup->ss_info && gsup->ss_info_len) {
 			if (ss_op_is_ussd(req.opcode)) {
 				/* dispatch unstructured SS to routing */
-				handle_ussd(conn, ss, gsup, &req);
+				handle_ussd(ss, is_euse_originated, &gsup_req->gsup, &req);
 			} else {
 				/* dispatch non-call SS to internal code */
-				handle_ss(ss, gsup, &req);
+				handle_ss(ss, is_euse_originated, &gsup_req->gsup, &req);
 			}
 		}
 
@@ -626,18 +647,15 @@ int rx_proc_ss_req(struct osmo_gsup_conn *conn, const struct osmo_gsup_message *
 	default:
 		LOGP(DSS, LOGL_ERROR, "%s/0x%08x: Unknown SS State %d\n", gsup->imsi,
 			gsup->session_id, gsup->session_state);
-		goto out_err;
+		break;
 	}
 
-	return 0;
-
-out_err:
-	return 0;
+	if (free_gsup_req)
+		osmo_gsup_req_free(free_gsup_req);
 }
 
-int rx_proc_ss_error(struct osmo_gsup_conn *conn, const struct osmo_gsup_message *gsup)
+void rx_proc_ss_error(struct osmo_gsup_req *req)
 {
-	LOGP(DSS, LOGL_NOTICE, "%s/0x%08x: Process SS ERROR (%s)\n", gsup->imsi, gsup->session_id,
-		osmo_gsup_session_state_name(gsup->session_state));
-	return 0;
+	LOGP(DSS, LOGL_NOTICE, "%s/0x%08x: Process SS ERROR (%s)\n", req->gsup.imsi, req->gsup.session_id,
+		osmo_gsup_session_state_name(req->gsup.session_state));
 }

src/hlr_vty.c

@@ -146,6 +146,24 @@ DEFUN(cfg_hlr_gsup_bind_ip,
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_hlr_gsup_ipa_name,
+      cfg_hlr_gsup_ipa_name_cmd,
+      "ipa-name NAME",
+      "Set the IPA name of this HLR, for proxying to remote HLRs\n"
+      "A globally unique name for this HLR. For example: PLMN + redundancy server number: HLR-901-70-0. "
+      "This name is used for GSUP routing and must be set if multiple HLRs interconnect (e.g. mslookup "
+      "for Distributed GSM).\n")
+{
+	if (vty->type != VTY_FILE) {
+		vty_out(vty, "gsup/ipa-name: The GSUP IPA name cannot be changed at run-time; "
+			"It can only be set in the configuraton file.%s", VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	g_hlr->gsup_unit_name.serno = talloc_strdup(g_hlr, argv[0]);
+	return CMD_SUCCESS;
+}
+
 /***********************************************************************
  * USSD Entity
  ***********************************************************************/
@@ -444,6 +462,7 @@ void hlr_vty_init(void)
 	install_node(&gsup_node, config_write_hlr_gsup);
 
 	install_element(GSUP_NODE, &cfg_hlr_gsup_bind_ip_cmd);
+	install_element(GSUP_NODE, &cfg_hlr_gsup_ipa_name_cmd);
 
 	install_element(HLR_NODE, &cfg_database_cmd);
 

src/hlr_vty_subscr.c

@@ -30,30 +30,43 @@
 
 #include <osmocom/hlr/hlr.h>
 #include <osmocom/hlr/db.h>
+#include <osmocom/hlr/timestamp.h>
 
 struct vty;
 
 #define hexdump_buf(buf) osmo_hexdump_nospc((void*)buf, sizeof(buf))
 
-static char *
-get_datestr(const time_t *t, char *datebuf)
+static char *get_datestr(const time_t *t, char *buf, size_t bufsize)
 {
-	char *p, *s = ctime_r(t, datebuf);
-
-	/* Strip trailing newline. */
-	p = strchr(s, '\n');
-	if (p)
-		*p = '\0';
-	return s;
+	struct tm tm;
+	gmtime_r(t, &tm);
+	strftime(buf, bufsize, "%FT%T+00:00", &tm);
+	return buf;
 }
 
 static void dump_last_lu_seen(struct vty *vty, const char *domain_label, time_t last_lu_seen)
 {
-	char datebuf[26]; /* for ctime_r(3) */
+	uint32_t age;
+	char datebuf[32];
 	if (!last_lu_seen)
 		return;
-	vty_out(vty, "    last LU seen on %s: %s UTC%s", domain_label, get_datestr(&last_lu_seen, datebuf),
-		VTY_NEWLINE);
+	vty_out(vty, "    last LU seen on %s: %s", domain_label, get_datestr(&last_lu_seen, datebuf, sizeof(datebuf)));
+	if (!timestamp_age(&last_lu_seen, &age))
+		vty_out(vty, " (invalid timestamp)%s", VTY_NEWLINE);
+	else {
+		vty_out(vty, " (");
+#define UNIT_AGO(UNITNAME, UNITVAL) \
+		if (age >= (UNITVAL)) { \
+			vty_out(vty, "%u%s", age / (UNITVAL), UNITNAME); \
+			age = age % (UNITVAL); \
+		}
+		UNIT_AGO("d", 60*60*24);
+		UNIT_AGO("h", 60*60);
+		UNIT_AGO("m", 60);
+		UNIT_AGO("s", 1);
+		vty_out(vty, " ago)%s", VTY_NEWLINE);
+#undef UNIT_AGO
+	}
 }
 
 static void subscr_dump_full_vty(struct vty *vty, struct hlr_subscriber *subscr)

src/logging.c

@@ -25,7 +25,24 @@ const struct log_info_cat hlr_log_info_cat[] = {
 		.color = "\033[1;34m",
 		.enabled = 1, .loglevel = LOGL_NOTICE,
 	},
-
+	[DMSLOOKUP] = {
+		.name = "DMSLOOKUP",
+		.description = "Mobile Subscriber Lookup",
+		.color = "\033[1;35m",
+		.enabled = 1, .loglevel = LOGL_NOTICE,
+	},
+	[DLU] = {
+		.name = "DLU",
+		.description = "Location Updating",
+		.color = "\033[1;33m",
+		.enabled = 1, .loglevel = LOGL_NOTICE,
+	},
+	[DDGSM] = {
+		.name = "DDGSM",
+		.description = "Distributed GSM: MS lookup and proxy",
+		.color = "\033[1;35m",
+		.enabled = 1, .loglevel = LOGL_NOTICE,
+	},
 };
 
 const struct log_info hlr_log_info = {

src/lu_fsm.c

@@ -0,0 +1,320 @@
+/* Roughly following "Process Update_Location_HLR" of TS 09.02 */
+
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <osmocom/core/utils.h>
+#include <osmocom/core/tdef.h>
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/core/fsm.h>
+#include <osmocom/gsm/apn.h>
+#include <osmocom/gsm/gsm48_ie.h>
+
+#include <osmocom/gsupclient/gsup_peer_id.h>
+#include <osmocom/gsupclient/gsup_req.h>
+#include <osmocom/hlr/logging.h>
+#include <osmocom/hlr/hlr.h>
+#include <osmocom/hlr/gsup_server.h>
+
+#include <osmocom/hlr/db.h>
+
+#define LOG_LU(lu, level, fmt, args...) \
+	LOGPFSML((lu)? (lu)->fi : NULL, level, fmt, ##args)
+
+#define LOG_LU_REQ(lu, req, level, fmt, args...) \
+	LOGPFSML((lu)? (lu)->fi : NULL, level, "%s:" fmt, \
+		 osmo_gsup_message_type_name((req)->gsup.message_type), ##args)
+
+struct lu {
+	struct llist_head entry;
+	struct osmo_fsm_inst *fi;
+
+	struct osmo_gsup_req *update_location_req;
+
+	/* Subscriber state at time of initial Update Location Request */
+	struct hlr_subscriber subscr;
+	bool is_ps;
+
+	/* VLR requesting the LU. */
+	struct osmo_gsup_peer_id vlr_name;
+
+	/* If the LU request was received via a proxy and not immediately from a local VLR, this indicates the closest
+	 * peer that forwarded the GSUP message. */
+	struct osmo_gsup_peer_id via_proxy;
+};
+LLIST_HEAD(g_all_lu);
+
+enum lu_fsm_event {
+	LU_EV_RX_GSUP,
+};
+
+enum lu_fsm_state {
+	LU_ST_UNVALIDATED,
+	LU_ST_WAIT_INSERT_DATA_RESULT,
+	LU_ST_WAIT_LOCATION_CANCEL_RESULT,
+};
+
+static const struct value_string lu_fsm_event_names[] = {
+	OSMO_VALUE_STRING(LU_EV_RX_GSUP),
+	{}
+};
+
+static struct osmo_tdef_state_timeout lu_fsm_timeouts[32] = {
+	[LU_ST_WAIT_INSERT_DATA_RESULT] = { .T = -4222 },
+	[LU_ST_WAIT_LOCATION_CANCEL_RESULT] = { .T = -4222 },
+};
+
+#define lu_state_chg(lu, state) \
+	osmo_tdef_fsm_inst_state_chg((lu)->fi, state, lu_fsm_timeouts, g_hlr_tdefs, 5)
+
+static void lu_success(struct lu *lu)
+{
+	if (!lu->update_location_req)
+		LOG_LU(lu, LOGL_ERROR, "No request for this LU\n");
+	else
+		osmo_gsup_req_respond_msgt(lu->update_location_req, OSMO_GSUP_MSGT_UPDATE_LOCATION_RESULT, true);
+	lu->update_location_req = NULL;
+	osmo_fsm_inst_term(lu->fi, OSMO_FSM_TERM_REGULAR, NULL);
+}
+
+#define lu_failure(LU, CAUSE, log_msg, args...) do { \
+		if (!(LU)->update_location_req) \
+			LOG_LU(LU, LOGL_ERROR, "No request for this LU\n"); \
+		else \
+			osmo_gsup_req_respond_err((LU)->update_location_req, CAUSE, log_msg, ##args); \
+		(LU)->update_location_req = NULL; \
+		osmo_fsm_inst_term((LU)->fi, OSMO_FSM_TERM_REGULAR, NULL); \
+	} while(0)
+
+static struct osmo_fsm lu_fsm;
+
+static void lu_start(struct osmo_gsup_req *update_location_req)
+{
+	struct osmo_fsm_inst *fi;
+	struct lu *lu;
+
+	OSMO_ASSERT(update_location_req);
+	OSMO_ASSERT(update_location_req->gsup.message_type == OSMO_GSUP_MSGT_UPDATE_LOCATION_REQUEST);
+
+	fi = osmo_fsm_inst_alloc(&lu_fsm, g_hlr, NULL, LOGL_DEBUG, update_location_req->gsup.imsi);
+	OSMO_ASSERT(fi);
+
+	lu = talloc(fi, struct lu);
+	OSMO_ASSERT(lu);
+	fi->priv = lu;
+	*lu = (struct lu){
+		.fi = fi,
+		.update_location_req = update_location_req,
+		.vlr_name = update_location_req->source_name,
+		.via_proxy = update_location_req->via_proxy,
+		/* According to GSUP specs, OSMO_GSUP_CN_DOMAIN_PS is the default. */
+		.is_ps = (update_location_req->gsup.cn_domain != OSMO_GSUP_CN_DOMAIN_CS),
+	};
+	llist_add(&lu->entry, &g_all_lu);
+
+	osmo_fsm_inst_update_id_f_sanitize(fi, '_', "%s:IMSI-%s", lu->is_ps ? "PS" : "CS", update_location_req->gsup.imsi);
+
+	if (osmo_gsup_peer_id_is_empty(&lu->vlr_name)) {
+		lu_failure(lu, GMM_CAUSE_NET_FAIL, "LU without a VLR");
+		return;
+	}
+
+	if (db_subscr_get_by_imsi(g_hlr->dbc, update_location_req->gsup.imsi, &lu->subscr) < 0) {
+		lu_failure(lu, GMM_CAUSE_IMSI_UNKNOWN, "Subscriber does not exist");
+		return;
+	}
+
+	/* Check if subscriber is generally permitted on CS or PS
+	 * service (as requested) */
+	if (!lu->is_ps && !lu->subscr.nam_cs) {
+		lu_failure(lu, GMM_CAUSE_PLMN_NOTALLOWED, "nam_cs == false");
+		return;
+	}
+	if (lu->is_ps && !lu->subscr.nam_ps) {
+		lu_failure(lu, GMM_CAUSE_GPRS_NOTALLOWED, "nam_ps == false");
+		return;
+	}
+
+	/* TODO: Set subscriber tracing = deactive in VLR/SGSN */
+
+#if 0
+	/* Cancel in old VLR/SGSN, if new VLR/SGSN differs from old (FIXME: OS#4491) */
+	if (!lu->is_ps && strcmp(subscr->vlr_number, vlr_number)) {
+		lu_op_tx_cancel_old(lu);
+	} else if (lu->is_ps && strcmp(subscr->sgsn_number, sgsn_number)) {
+		lu_op_tx_cancel_old(lu);
+	}
+#endif
+
+	/* Store the VLR / SGSN number with the subscriber, so we know where it was last seen. */
+	if (!osmo_gsup_peer_id_is_empty(&lu->via_proxy)) {
+		LOG_GSUP_REQ(update_location_req, LOGL_DEBUG, "storing %s = %s, via proxy %s\n",
+			     lu->is_ps ? "SGSN number" : "VLR number",
+			     osmo_gsup_peer_id_to_str(&lu->vlr_name),
+			     osmo_gsup_peer_id_to_str(&lu->via_proxy));
+	} else {
+		LOG_GSUP_REQ(update_location_req, LOGL_DEBUG, "storing %s = %s\n",
+		     lu->is_ps ? "SGSN number" : "VLR number",
+		     osmo_gsup_peer_id_to_str(&lu->vlr_name));
+	}
+
+	if (osmo_gsup_peer_id_is_empty(&lu->vlr_name)
+	    || (lu->vlr_name.type != OSMO_GSUP_PEER_ID_IPA_NAME)) {
+		lu_failure(lu, GMM_CAUSE_PROTO_ERR_UNSPEC, "Unsupported GSUP peer id type for vlr_name: %s",
+			   osmo_gsup_peer_id_type_name(lu->vlr_name.type));
+		return;
+	}
+	if (!osmo_gsup_peer_id_is_empty(&lu->via_proxy) && (lu->via_proxy.type != OSMO_GSUP_PEER_ID_IPA_NAME)) {
+		lu_failure(lu, GMM_CAUSE_PROTO_ERR_UNSPEC, "Unsupported GSUP peer id type for via_proxy: %s",
+			   osmo_gsup_peer_id_type_name(lu->via_proxy.type));
+		return;
+	}
+	if (db_subscr_lu(g_hlr->dbc, lu->subscr.id, &lu->vlr_name.ipa_name, lu->is_ps,
+			 osmo_gsup_peer_id_is_empty(&lu->via_proxy)? NULL : &lu->via_proxy.ipa_name)) {
+		lu_failure(lu, GMM_CAUSE_NET_FAIL, "Cannot update %s in the database",
+			   lu->is_ps ? "SGSN number" : "VLR number");
+		return;
+	}
+
+	/* TODO: Subscriber allowed to roam in PLMN? */
+	/* TODO: Update RoutingInfo */
+	/* TODO: Reset Flag MS Purged (cs/ps) */
+	/* TODO: Control_Tracing_HLR / Control_Tracing_HLR_with_SGSN */
+
+	lu_state_chg(lu, LU_ST_WAIT_INSERT_DATA_RESULT);
+}
+
+void lu_rx_gsup(struct osmo_gsup_req *req)
+{
+	struct lu *lu;
+	if (req->gsup.message_type == OSMO_GSUP_MSGT_UPDATE_LOCATION_REQUEST)
+		return lu_start(req);
+
+	llist_for_each_entry(lu, &g_all_lu, entry) {
+		if (strcmp(lu->subscr.imsi, req->gsup.imsi))
+			continue;
+		if (osmo_fsm_inst_dispatch(lu->fi, LU_EV_RX_GSUP, req)) {
+			LOG_LU_REQ(lu, req, LOGL_ERROR, "Cannot receive GSUP messages in this state\n");
+			osmo_gsup_req_respond_err(req, GMM_CAUSE_MSGT_INCOMP_P_STATE,
+						  "LU does not accept GSUP rx");
+		}
+		return;
+	}
+	osmo_gsup_req_respond_err(req, GMM_CAUSE_MSGT_INCOMP_P_STATE, "No Location Updating in progress for this IMSI");
+}
+
+static int lu_fsm_timer_cb(struct osmo_fsm_inst *fi)
+{
+	struct lu *lu = fi->priv;
+	lu_failure(lu, GSM_CAUSE_NET_FAIL, "Timeout");
+	return 0;
+}
+
+static void lu_fsm_cleanup(struct osmo_fsm_inst *fi, enum osmo_fsm_term_cause cause)
+{
+	struct lu *lu = fi->priv;
+	if (lu->update_location_req)
+		osmo_gsup_req_respond_err(lu->update_location_req, GSM_CAUSE_NET_FAIL, "LU aborted");
+	lu->update_location_req = NULL;
+	llist_del(&lu->entry);
+}
+
+static void lu_fsm_wait_insert_data_result_onenter(struct osmo_fsm_inst *fi, uint32_t prev_state)
+{
+	/* Transmit Insert Data Request to the VLR */
+	struct lu *lu = fi->priv;
+	struct hlr_subscriber *subscr = &lu->subscr;
+	struct osmo_gsup_message gsup;
+	uint8_t msisdn_enc[OSMO_GSUP_MAX_CALLED_PARTY_BCD_LEN];
+	uint8_t apn[APN_MAXLEN];
+
+	if (osmo_gsup_create_insert_subscriber_data_msg(&gsup, subscr->imsi,
+							subscr->msisdn, msisdn_enc, sizeof(msisdn_enc),
+							apn, sizeof(apn),
+							lu->is_ps? OSMO_GSUP_CN_DOMAIN_PS : OSMO_GSUP_CN_DOMAIN_CS)) {
+		lu_failure(lu, GMM_CAUSE_NET_FAIL, "cannot encode Insert Subscriber Data message");
+		return;
+	}
+
+	if (osmo_gsup_req_respond(lu->update_location_req, &gsup, false, false))
+		lu_failure(lu, GMM_CAUSE_NET_FAIL, "cannot send %s", osmo_gsup_message_type_name(gsup.message_type));
+}
+
+void lu_fsm_wait_insert_data_result(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	struct lu *lu = fi->priv;
+	struct osmo_gsup_req *req;
+
+	switch (event) {
+	case LU_EV_RX_GSUP:
+		req = data;
+		break;
+	default:
+		OSMO_ASSERT(false);
+	}
+
+	switch (req->gsup.message_type) {
+	case OSMO_GSUP_MSGT_INSERT_DATA_RESULT:
+		osmo_gsup_req_free(req);
+		lu_success(lu);
+		break;
+
+	case OSMO_GSUP_MSGT_INSERT_DATA_ERROR:
+		lu_failure(lu, GMM_CAUSE_NET_FAIL, "Rx %s", osmo_gsup_message_type_name(req->gsup.message_type));
+		break;
+
+	default:
+		osmo_gsup_req_respond_err(req, GMM_CAUSE_MSGT_INCOMP_P_STATE, "unexpected message type in this state");
+		break;
+	}
+}
+
+#define S(x) (1 << (x))
+
+static const struct osmo_fsm_state lu_fsm_states[] = {
+	[LU_ST_UNVALIDATED] = {
+		.name = "UNVALIDATED",
+		.out_state_mask = 0
+			| S(LU_ST_WAIT_INSERT_DATA_RESULT)
+			,
+	},
+	[LU_ST_WAIT_INSERT_DATA_RESULT] = {
+		.name = "WAIT_INSERT_DATA_RESULT",
+		.in_event_mask = 0
+			| S(LU_EV_RX_GSUP)
+			,
+		.onenter = lu_fsm_wait_insert_data_result_onenter,
+		.action = lu_fsm_wait_insert_data_result,
+	},
+};
+
+static struct osmo_fsm lu_fsm = {
+	.name = "lu",
+	.states = lu_fsm_states,
+	.num_states = ARRAY_SIZE(lu_fsm_states),
+	.log_subsys = DLU,
+	.event_names = lu_fsm_event_names,
+	.timer_cb = lu_fsm_timer_cb,
+	.cleanup = lu_fsm_cleanup,
+};
+
+static __attribute__((constructor)) void lu_fsm_init()
+{
+	OSMO_ASSERT(osmo_fsm_register(&lu_fsm) == 0);
+}

src/luop.c

@@ -1,258 +0,0 @@
-/* OsmoHLR TX/RX lu operations */
-
-/* (C) 2017 sysmocom s.f.m.c. GmbH <info@sysmocom.de>
- * All Rights Reserved
- *
- * Author: Harald Welte <laforge@gnumonks.org>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License as published by
- * the Free Software Foundation; either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Affero General Public License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- */
-
-#include <stdbool.h>
-#include <string.h>
-#include <errno.h>
-
-#include <osmocom/core/logging.h>
-#include <osmocom/gsm/gsup.h>
-#include <osmocom/gsm/apn.h>
-
-#include <osmocom/hlr/gsup_server.h>
-#include <osmocom/hlr/gsup_router.h>
-#include <osmocom/hlr/logging.h>
-#include <osmocom/hlr/luop.h>
-
-const struct value_string lu_state_names[] = {
-	{ LU_S_NULL,			"NULL" },
-	{ LU_S_LU_RECEIVED,		"LU RECEIVED" },
-	{ LU_S_CANCEL_SENT,		"CANCEL SENT" },
-	{ LU_S_CANCEL_ACK_RECEIVED,	"CANCEL-ACK RECEIVED" },
-	{ LU_S_ISD_SENT,		"ISD SENT" },
-	{ LU_S_ISD_ACK_RECEIVED,	"ISD-ACK RECEIVED" },
-	{ LU_S_COMPLETE,		"COMPLETE" },
-	{ 0, NULL }
-};
-
-/* Transmit a given GSUP message for the given LU operation */
-static void _luop_tx_gsup(struct lu_operation *luop,
-			  const struct osmo_gsup_message *gsup)
-{
-	struct msgb *msg_out;
-
-	msg_out = osmo_gsup_msgb_alloc("GSUP LUOP");
-	osmo_gsup_encode(msg_out, gsup);
-
-	osmo_gsup_addr_send(luop->gsup_server, luop->peer,
-			    talloc_total_size(luop->peer),
-			    msg_out);
-}
-
-static inline void fill_gsup_msg(struct osmo_gsup_message *out,
-				 const struct lu_operation *lu,
-				 enum osmo_gsup_message_type mt)
-{
-	memset(out, 0, sizeof(struct osmo_gsup_message));
-	if (lu)
-		osmo_strlcpy(out->imsi, lu->subscr.imsi,
-			     GSM23003_IMSI_MAX_DIGITS + 1);
-	out->message_type = mt;
-}
-
-/* timer call-back in case LU operation doesn't receive an response */
-static void lu_op_timer_cb(void *data)
-{
-	struct lu_operation *luop = data;
-
-	DEBUGP(DMAIN, "LU OP timer expired in state %s\n",
-		get_value_string(lu_state_names, luop->state));
-
-	switch (luop->state) {
-	case LU_S_CANCEL_SENT:
-		break;
-	case LU_S_ISD_SENT:
-		break;
-	default:
-		break;
-	}
-
-	lu_op_tx_error(luop, GMM_CAUSE_NET_FAIL);
-}
-
-bool lu_op_fill_subscr(struct lu_operation *luop, struct db_context *dbc,
-		       const char *imsi)
-{
-	struct hlr_subscriber *subscr = &luop->subscr;
-
-	if (db_subscr_get_by_imsi(dbc, imsi, subscr) < 0)
-		return false;
-
-	return true;
-}
-
-struct lu_operation *lu_op_alloc(struct osmo_gsup_server *srv)
-{
-	struct lu_operation *luop;
-
-	luop = talloc_zero(srv, struct lu_operation);
-	OSMO_ASSERT(luop);
-	luop->gsup_server = srv;
-	osmo_timer_setup(&luop->timer, lu_op_timer_cb, luop);
-
-	return luop;
-}
-
-void lu_op_free(struct lu_operation *luop)
-{
-	/* Only attempt to remove when it was ever added to a list. */
-	if (luop->list.next)
-		llist_del(&luop->list);
-
-	/* Delete timer just in case it is still pending. */
-	osmo_timer_del(&luop->timer);
-
-	talloc_free(luop);
-}
-
-struct lu_operation *lu_op_alloc_conn(struct osmo_gsup_conn *conn)
-{
-	uint8_t *peer_addr;
-	struct lu_operation *luop = lu_op_alloc(conn->server);
-	int rc = osmo_gsup_conn_ccm_get(conn, &peer_addr, IPAC_IDTAG_SERNR);
-	if (rc < 0) {
-		lu_op_free(luop);
-		return NULL;
-	}
-
-	luop->peer = talloc_memdup(luop, peer_addr, rc);
-
-	return luop;
-}
-
-/* FIXME: this doesn't seem to work at all */
-struct lu_operation *lu_op_by_imsi(const char *imsi,
-				   const struct llist_head *lst)
-{
-	struct lu_operation *luop;
-
-	llist_for_each_entry(luop, lst, list) {
-		if (!strcmp(imsi, luop->subscr.imsi))
-			return luop;
-	}
-	return NULL;
-}
-
-void lu_op_statechg(struct lu_operation *luop, enum lu_state new_state)
-{
-	enum lu_state old_state = luop->state;
-
-	DEBUGP(DMAIN, "LU OP state change: %s -> ",
-		get_value_string(lu_state_names, old_state));
-	DEBUGPC(DMAIN, "%s\n",
-		get_value_string(lu_state_names, new_state));
-
-	luop->state = new_state;
-}
-
-/*! Transmit UPD_LOC_ERROR and destroy lu_operation */
-void lu_op_tx_error(struct lu_operation *luop, enum gsm48_gmm_cause cause)
-{
-	struct osmo_gsup_message gsup;
-
-	DEBUGP(DMAIN, "%s: LU OP Tx Error (cause %s)\n",
-	       luop->subscr.imsi, get_value_string(gsm48_gmm_cause_names,
-						   cause));
-
-	fill_gsup_msg(&gsup, luop, OSMO_GSUP_MSGT_UPDATE_LOCATION_ERROR);
-	gsup.cause = cause;
-
-	_luop_tx_gsup(luop, &gsup);
-
-	lu_op_free(luop);
-}
-
-/*! Transmit UPD_LOC_RESULT and destroy lu_operation */
-void lu_op_tx_ack(struct lu_operation *luop)
-{
-	struct osmo_gsup_message gsup;
-
-	fill_gsup_msg(&gsup, luop, OSMO_GSUP_MSGT_UPDATE_LOCATION_RESULT);
-	//FIXME gsup.hlr_enc;
-
-	_luop_tx_gsup(luop, &gsup);
-
-	lu_op_free(luop);
-}
-
-/*! Send Cancel Location to old VLR/SGSN */
-void lu_op_tx_cancel_old(struct lu_operation *luop)
-{
-	struct osmo_gsup_message gsup;
-
-	OSMO_ASSERT(luop->state == LU_S_LU_RECEIVED);
-
-	fill_gsup_msg(&gsup, NULL, OSMO_GSUP_MSGT_LOCATION_CANCEL_REQUEST);
-	//gsup.cause = FIXME;
-	//gsup.cancel_type = FIXME;
-
-	_luop_tx_gsup(luop, &gsup);
-
-	lu_op_statechg(luop, LU_S_CANCEL_SENT);
-	osmo_timer_schedule(&luop->timer, CANCEL_TIMEOUT_SECS, 0);
-}
-
-/*! Transmit Insert Subscriber Data to new VLR/SGSN */
-void lu_op_tx_insert_subscr_data(struct lu_operation *luop)
-{
-	struct hlr_subscriber *subscr = &luop->subscr;
-	struct osmo_gsup_message gsup = { };
-	uint8_t msisdn_enc[OSMO_GSUP_MAX_CALLED_PARTY_BCD_LEN];
-	uint8_t apn[APN_MAXLEN];
-	enum osmo_gsup_cn_domain cn_domain;
-
-	OSMO_ASSERT(luop->state == LU_S_LU_RECEIVED ||
-		    luop->state == LU_S_CANCEL_ACK_RECEIVED);
-
-	if (luop->is_ps)
-		cn_domain = OSMO_GSUP_CN_DOMAIN_PS;
-	else
-		cn_domain = OSMO_GSUP_CN_DOMAIN_CS;
-
-	if (osmo_gsup_create_insert_subscriber_data_msg(&gsup, subscr->imsi, subscr->msisdn, msisdn_enc,
-							sizeof(msisdn_enc), apn, sizeof(apn), cn_domain) != 0) {
-		LOGP(DMAIN, LOGL_ERROR,
-		       "IMSI='%s': Cannot notify GSUP client; could not create gsup message "
-		       "for %s\n", subscr->imsi, luop->peer);
-		return;
-	}
-
-	/* Send ISD to new VLR/SGSN */
-	_luop_tx_gsup(luop, &gsup);
-
-	lu_op_statechg(luop, LU_S_ISD_SENT);
-	osmo_timer_schedule(&luop->timer, ISD_TIMEOUT_SECS, 0);
-}
-
-/*! Transmit Delete Subscriber Data to new VLR/SGSN.
- * The luop is not freed. */
-void lu_op_tx_del_subscr_data(struct lu_operation *luop)
-{
-	struct osmo_gsup_message gsup;
-
-	fill_gsup_msg(&gsup, luop, OSMO_GSUP_MSGT_DELETE_DATA_REQUEST);
-
-	gsup.cn_domain = OSMO_GSUP_CN_DOMAIN_PS;
-
-	/* Send ISD to new VLR/SGSN */
-	_luop_tx_gsup(luop, &gsup);
-}

src/mslookup/Makefile.am

@@ -0,0 +1,37 @@
+# This is _NOT_ the library release version, it's an API version.
+# Please read chapter "Library interface versions" of the libtool documentation
+# before making any modifications: https://www.gnu.org/software/libtool/manual/html_node/Versioning.html
+LIBVERSION=0:0:0
+
+AM_CPPFLAGS = $(all_includes) -I$(top_srcdir)/include -I$(top_builddir)/include
+AM_CFLAGS = -fPIC -Wall $(PCSC_CFLAGS) $(TALLOC_CFLAGS) $(LIBOSMOCORE_CFLAGS)
+AM_LDFLAGS = $(COVERAGE_LDFLAGS)
+
+lib_LTLIBRARIES = libosmo-mslookup.la
+
+libosmo_mslookup_la_SOURCES = \
+	mdns.c \
+	mdns_msg.c \
+	mdns_rfc.c \
+	mdns_sock.c \
+	mslookup.c \
+	mslookup_client.c \
+	mslookup_client_fake.c \
+	mslookup_client_mdns.c \
+	$(NULL)
+
+libosmo_mslookup_la_LDFLAGS = -version-info $(LIBVERSION)
+libosmo_mslookup_la_LIBADD = \
+	$(LIBOSMOCORE_LIBS) \
+	$(LIBOSMOGSM_LIBS) \
+	$(TALLOC_LIBS) \
+	$(NULL)
+
+bin_PROGRAMS = osmo-mslookup-client
+osmo_mslookup_client_SOURCES = osmo-mslookup-client.c
+osmo_mslookup_client_LDADD = \
+	libosmo-mslookup.la \
+	$(LIBOSMOCORE_LIBS) \
+	$(TALLOC_LIBS) \
+	$(NULL)
+osmo_mslookup_client_CFLAGS = $(TALLOC_CFLAGS) $(LIBOSMOCORE_CFLAGS)

src/mslookup/mdns.c

@@ -0,0 +1,425 @@
+/* mslookup specific functions for encoding and decoding mslookup queries/results into mDNS packets, using the high
+ * level functions from mdns_msg.c and mdns_record.c to build the request/answer messages. */
+
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <osmocom/hlr/logging.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/mslookup/mslookup.h>
+#include <osmocom/mslookup/mdns_msg.h>
+#include <osmocom/mslookup/mdns_rfc.h>
+#include <errno.h>
+#include <inttypes.h>
+
+static struct msgb *osmo_mdns_msgb_alloc(const char *label)
+{
+	return msgb_alloc(1024, label);
+}
+
+/*! Combine the mslookup query service, ID and ID type into a domain string.
+ * \param[in] domain_suffix  is appended to each domain in the queries to avoid colliding with the top-level domains
+ *                           administrated by IANA. Example: "mdns.osmocom.org"
+ * \returns allocated buffer with the resulting domain (i.e. "sip.voice.123.msisdn.mdns.osmocom.org") on success,
+ * 	    NULL on failure.
+ */
+static char *domain_from_query(void *ctx, const struct osmo_mslookup_query *query, const char *domain_suffix)
+{
+	const char *id;
+
+	/* Get id from query */
+	switch (query->id.type) {
+		case OSMO_MSLOOKUP_ID_IMSI:
+			id = query->id.imsi;
+			break;
+		case OSMO_MSLOOKUP_ID_MSISDN:
+			id = query->id.msisdn;
+			break;
+		default:
+			LOGP(DMSLOOKUP, LOGL_ERROR, "can't encode mslookup query id type %i", query->id.type);
+			return NULL;
+	}
+
+	return talloc_asprintf(ctx, "%s.%s.%s.%s", query->service, id, osmo_mslookup_id_type_name(query->id.type),
+			       domain_suffix);
+}
+
+/*! Split up query service, ID and ID type from a domain string into a mslookup query.
+ * \param[in] domain  with domain_suffix, e.g. "sip.voice.123.msisdn.mdns.osmocom.org"
+ * \param[in] domain_suffix  is appended to each domain in the queries to avoid colliding with the top-level domains
+ *                           administrated by IANA. It is not part of the resulting struct osmo_mslookup_query, so we
+ *                           remove it in this function. Example: "mdns.osmocom.org"
+ */
+int query_from_domain(struct osmo_mslookup_query *query, const char *domain, const char *domain_suffix)
+{
+	int domain_len = strlen(domain) - strlen(domain_suffix) - 1;
+	char domain_buf[OSMO_MDNS_RFC_MAX_NAME_LEN];
+
+	if (domain_len <= 0 || domain_len >= sizeof(domain_buf))
+		return -EINVAL;
+
+	if (domain[domain_len] != '.' || strcmp(domain + domain_len + 1, domain_suffix) != 0)
+		return -EINVAL;
+
+	memcpy(domain_buf, domain, domain_len);
+	domain_buf[domain_len] = '\0';
+	return osmo_mslookup_query_init_from_domain_str(query, domain_buf);
+}
+
+/*! Encode a mslookup query into a mDNS packet.
+ * \param[in] domain_suffix  is appended to each domain in the queries to avoid colliding with the top-level domains
+ *                           administrated by IANA. Example: "mdns.osmocom.org"
+ * \returns msgb, or NULL on error.
+ */
+struct msgb *osmo_mdns_query_encode(void *ctx, uint16_t packet_id, const struct osmo_mslookup_query *query,
+				    const char *domain_suffix)
+{
+	struct osmo_mdns_msg_request req = {0};
+	struct msgb *msg = osmo_mdns_msgb_alloc(__func__);
+
+	req.id = packet_id;
+	req.type = OSMO_MDNS_RFC_RECORD_TYPE_ALL;
+	req.domain = domain_from_query(ctx, query, domain_suffix);
+	if (!req.domain)
+		goto error;
+	if (osmo_mdns_msg_request_encode(ctx, msg, &req))
+		goto error;
+	talloc_free(req.domain);
+	return msg;
+error:
+	msgb_free(msg);
+	talloc_free(req.domain);
+	return NULL;
+}
+
+/*! Decode a mDNS request packet into a mslookup query.
+ * \param[out] packet_id  the result must be sent with the same packet_id.
+ * \param[in] domain_suffix  is appended to each domain in the queries to avoid colliding with the top-level domains
+ *                           administrated by IANA. Example: "mdns.osmocom.org"
+ * \returns allocated mslookup query on success, NULL on error.
+ */
+struct osmo_mslookup_query *osmo_mdns_query_decode(void *ctx, const uint8_t *data, size_t data_len,
+						   uint16_t *packet_id, const char *domain_suffix)
+{
+	struct osmo_mdns_msg_request *req = NULL;
+	struct osmo_mslookup_query *query = NULL;
+
+	req = osmo_mdns_msg_request_decode(ctx, data, data_len);
+	if (!req)
+		return NULL;
+
+	query = talloc_zero(ctx, struct osmo_mslookup_query);
+	OSMO_ASSERT(query);
+	if (query_from_domain(query, req->domain, domain_suffix) < 0)
+		goto error_free;
+
+	*packet_id = req->id;
+	talloc_free(req);
+	return query;
+error_free:
+	talloc_free(req);
+	talloc_free(query);
+	return NULL;
+}
+
+/*! Parse sockaddr_str from mDNS record, so the mslookup result can be filled with it.
+ * \param[out] sockaddr_str resulting IPv4 or IPv6 sockaddr_str.
+ * \param[in] rec  single record of the abstracted list of mDNS records
+ * \returns 0 on success, -EINVAL on error.
+ */
+static int sockaddr_str_from_mdns_record(struct osmo_sockaddr_str *sockaddr_str, struct osmo_mdns_record *rec)
+{
+	switch (rec->type) {
+	case OSMO_MDNS_RFC_RECORD_TYPE_A:
+		if (rec->length != 4) {
+			LOGP(DMSLOOKUP, LOGL_ERROR, "unexpected length of A record\n");
+			return -EINVAL;
+		}
+		osmo_sockaddr_str_from_32(sockaddr_str, *(uint32_t *)rec->data, 0);
+		break;
+	case OSMO_MDNS_RFC_RECORD_TYPE_AAAA:
+		if (rec->length != 16) {
+			LOGP(DMSLOOKUP, LOGL_ERROR, "unexpected length of AAAA record\n");
+			return -EINVAL;
+		}
+		osmo_sockaddr_str_from_in6_addr(sockaddr_str, (struct in6_addr*)rec->data, 0);
+		break;
+	default:
+		LOGP(DMSLOOKUP, LOGL_ERROR, "unexpected record type\n");
+		return -EINVAL;
+	}
+	return 0;
+}
+
+/*! Encode a successful mslookup result, along with the original query and packet_id into one mDNS answer packet.
+ *
+ * The records in the packet are ordered as follows:
+ * 1) "age", ip_v4/v6, "port" (only IPv4 or IPv6 present) or
+ * 2) "age", ip_v4, "port", ip_v6, "port" (both IPv4 and v6 present).
+ * "age" and "port" are TXT records, ip_v4 is an A record, ip_v6 is an AAAA record.
+ *
+ * \param[in] packet_id  as received in osmo_mdns_query_decode().
+ * \param[in] query  the original query, so we can send the domain back in the answer (i.e. "sip.voice.1234.msisdn").
+ * \param[in] result  holds the age, IPs and ports of the queried service.
+ * \param[in] domain_suffix  is appended to each domain in the queries to avoid colliding with the top-level domains
+ *                           administrated by IANA. Example: "mdns.osmocom.org"
+ * \returns msg on success, NULL on error.
+ */
+struct msgb *osmo_mdns_result_encode(void *ctx, uint16_t packet_id, const struct osmo_mslookup_query *query,
+				     const struct osmo_mslookup_result *result, const char *domain_suffix)
+{
+	struct osmo_mdns_msg_answer ans = {};
+	struct osmo_mdns_record *rec_age = NULL;
+	struct osmo_mdns_record rec_ip_v4 = {0};
+	struct osmo_mdns_record rec_ip_v6 = {0};
+	struct osmo_mdns_record *rec_ip_v4_port = NULL;
+	struct osmo_mdns_record *rec_ip_v6_port = NULL;
+	struct in_addr rec_ip_v4_in;
+	struct in6_addr rec_ip_v6_in;
+	struct msgb *msg = osmo_mdns_msgb_alloc(__func__);
+	char buf[256];
+
+	ctx = talloc_named(ctx, 0, "osmo_mdns_result_encode");
+
+	/* Prepare answer (ans) */
+	ans.domain = domain_from_query(ctx, query, domain_suffix);
+	if (!ans.domain)
+		goto error;
+	ans.id = packet_id;
+	INIT_LLIST_HEAD(&ans.records);
+
+	/* Record for age */
+	rec_age = osmo_mdns_record_txt_keyval_encode(ctx, "age", "%"PRIu32, result->age);
+	OSMO_ASSERT(rec_age);
+	llist_add_tail(&rec_age->list, &ans.records);
+
+	/* Records for IPv4 */
+	if (osmo_sockaddr_str_is_set(&result->host_v4)) {
+		if (osmo_sockaddr_str_to_in_addr(&result->host_v4, &rec_ip_v4_in) < 0) {
+			LOGP(DMSLOOKUP, LOGL_ERROR, "failed to encode ipv4: %s\n",
+			     osmo_mslookup_result_name_b(buf, sizeof(buf), query, result));
+			goto error;
+		}
+		rec_ip_v4.type = OSMO_MDNS_RFC_RECORD_TYPE_A;
+		rec_ip_v4.data = (uint8_t *)&rec_ip_v4_in;
+		rec_ip_v4.length = sizeof(rec_ip_v4_in);
+		llist_add_tail(&rec_ip_v4.list, &ans.records);
+
+		rec_ip_v4_port = osmo_mdns_record_txt_keyval_encode(ctx, "port", "%"PRIu16, result->host_v4.port);
+		OSMO_ASSERT(rec_ip_v4_port);
+		llist_add_tail(&rec_ip_v4_port->list, &ans.records);
+	}
+
+	/* Records for IPv6 */
+	if (osmo_sockaddr_str_is_set(&result->host_v6)) {
+		if (osmo_sockaddr_str_to_in6_addr(&result->host_v6, &rec_ip_v6_in) < 0) {
+			LOGP(DMSLOOKUP, LOGL_ERROR, "failed to encode ipv6: %s\n",
+			     osmo_mslookup_result_name_b(buf, sizeof(buf), query, result));
+			goto error;
+		}
+		rec_ip_v6.type = OSMO_MDNS_RFC_RECORD_TYPE_AAAA;
+		rec_ip_v6.data = (uint8_t *)&rec_ip_v6_in;
+		rec_ip_v6.length = sizeof(rec_ip_v6_in);
+		llist_add_tail(&rec_ip_v6.list, &ans.records);
+
+		rec_ip_v6_port = osmo_mdns_record_txt_keyval_encode(ctx, "port", "%"PRIu16, result->host_v6.port);
+		OSMO_ASSERT(rec_ip_v6_port);
+		llist_add_tail(&rec_ip_v6_port->list, &ans.records);
+	}
+
+	if (osmo_mdns_msg_answer_encode(ctx, msg, &ans)) {
+		LOGP(DMSLOOKUP, LOGL_ERROR, "failed to encode mDNS answer: %s\n",
+		     osmo_mslookup_result_name_b(buf, sizeof(buf), query, result));
+		goto error;
+	}
+	talloc_free(ctx);
+	return msg;
+error:
+	msgb_free(msg);
+	talloc_free(ctx);
+	return NULL;
+}
+
+static int decode_uint32_t(const char *str, uint32_t *val)
+{
+	long long int lld;
+	char *endptr = NULL;
+	*val = 0;
+	errno = 0;
+	lld = strtoll(str, &endptr, 10);
+	if (errno || !endptr || *endptr)
+		return -EINVAL;
+	if (lld < 0 || lld > UINT32_MAX)
+		return -EINVAL;
+	*val = lld;
+	return 0;
+}
+
+static int decode_port(const char *str, uint16_t *port)
+{
+	uint32_t val;
+	if (decode_uint32_t(str, &val))
+		return -EINVAL;
+	if (val > 65535)
+		return -EINVAL;
+	*port = val;
+	return 0;
+}
+
+/*! Read expected mDNS records into mslookup result.
+ *
+ * The records in the packet must be ordered as follows:
+ * 1) "age", ip_v4/v6, "port" (only IPv4 or IPv6 present) or
+ * 2) "age", ip_v4, "port", ip_v6, "port" (both IPv4 and v6 present).
+ * "age" and "port" are TXT records, ip_v4 is an A record, ip_v6 is an AAAA record.
+ *
+ * \param[out] result  holds the age, IPs and ports of the queried service.
+ * \param[in] ans  abstracted mDNS answer with a list of resource records.
+ * \returns 0 on success, -EINVAL on error.
+ */
+int osmo_mdns_result_from_answer(struct osmo_mslookup_result *result, const struct osmo_mdns_msg_answer *ans)
+{
+	struct osmo_mdns_record *rec;
+	char txt_key[64];
+	char txt_value[64];
+	bool found_age = false;
+	bool found_ip_v4 = false;
+	bool found_ip_v6 = false;
+	struct osmo_sockaddr_str *expect_port_for = NULL;
+
+	*result = (struct osmo_mslookup_result){};
+
+	result->rc = OSMO_MSLOOKUP_RC_NONE;
+
+	llist_for_each_entry(rec, &ans->records, list) {
+		switch (rec->type) {
+			case OSMO_MDNS_RFC_RECORD_TYPE_A:
+				if (expect_port_for) {
+					LOGP(DMSLOOKUP, LOGL_ERROR,
+					     "'A' record found, but still expecting a 'port' value first\n");
+					return -EINVAL;
+				}
+				if (found_ip_v4) {
+					LOGP(DMSLOOKUP, LOGL_ERROR, "'A' record found twice in mDNS answer\n");
+					return -EINVAL;
+				}
+				found_ip_v4 = true;
+				expect_port_for = &result->host_v4;
+				if (sockaddr_str_from_mdns_record(expect_port_for, rec)) {
+					LOGP(DMSLOOKUP, LOGL_ERROR, "'A' record with invalid address data\n");
+					return -EINVAL;
+				}
+				break;
+			case OSMO_MDNS_RFC_RECORD_TYPE_AAAA:
+				if (expect_port_for) {
+					LOGP(DMSLOOKUP, LOGL_ERROR,
+					     "'AAAA' record found, but still expecting a 'port' value first\n");
+					return -EINVAL;
+				}
+				if (found_ip_v6) {
+					LOGP(DMSLOOKUP, LOGL_ERROR, "'AAAA' record found twice in mDNS answer\n");
+					return -EINVAL;
+				}
+				found_ip_v6 = true;
+				expect_port_for = &result->host_v6;
+				if (sockaddr_str_from_mdns_record(expect_port_for, rec) != 0) {
+					LOGP(DMSLOOKUP, LOGL_ERROR, "'AAAA' record with invalid address data\n");
+					return -EINVAL;
+				}
+				break;
+			case OSMO_MDNS_RFC_RECORD_TYPE_TXT:
+				if (osmo_mdns_record_txt_keyval_decode(rec, txt_key, sizeof(txt_key),
+								       txt_value, sizeof(txt_value)) != 0) {
+					LOGP(DMSLOOKUP, LOGL_ERROR, "failed to decode txt record\n");
+					return -EINVAL;
+				}
+				if (strcmp(txt_key, "age") == 0) {
+					if (found_age) {
+						LOGP(DMSLOOKUP, LOGL_ERROR, "duplicate 'TXT' record for 'age'\n");
+						return -EINVAL;
+					}
+					found_age = true;
+					if (decode_uint32_t(txt_value, &result->age)) {
+						LOGP(DMSLOOKUP, LOGL_ERROR,
+						     "'TXT' record: invalid 'age' value ('age=%s')\n", txt_value);
+						return -EINVAL;
+					}
+				} else if (strcmp(txt_key, "port") == 0) {
+					if (!expect_port_for) {
+						LOGP(DMSLOOKUP, LOGL_ERROR,
+						     "'TXT' record for 'port' without previous 'A' or 'AAAA' record\n");
+						return -EINVAL;
+					}
+					if (decode_port(txt_value, &expect_port_for->port)) {
+						LOGP(DMSLOOKUP, LOGL_ERROR,
+						     "'TXT' record: invalid 'port' value ('port=%s')\n", txt_value);
+						return -EINVAL;
+					}
+					expect_port_for = NULL;
+				} else {
+					LOGP(DMSLOOKUP, LOGL_ERROR, "unexpected key '%s' in TXT record\n", txt_key);
+					return -EINVAL;
+				}
+				break;
+			default:
+				LOGP(DMSLOOKUP, LOGL_ERROR, "unexpected record type\n");
+				return -EINVAL;
+		}
+	}
+
+	/* Check if everything was found */
+	if (!found_age || !(found_ip_v4 || found_ip_v6) || expect_port_for) {
+		LOGP(DMSLOOKUP, LOGL_ERROR, "missing resource records in mDNS answer\n");
+		return -EINVAL;
+	}
+
+	result->rc = OSMO_MSLOOKUP_RC_RESULT;
+	return 0;
+}
+
+/*! Decode a mDNS answer packet into a mslookup result, query and packet_id.
+ * \param[out] packet_id  same ID as sent in the request packet.
+ * \param[out] query  the original query (service, ID, ID type).
+ * \param[out] result  holds the age, IPs and ports of the queried service.
+ * \param[in] domain_suffix  is appended to each domain in the queries to avoid colliding with the top-level domains
+ *                           administrated by IANA. Example: "mdns.osmocom.org"
+ * \returns 0 on success, -EINVAL on error.
+ */
+int osmo_mdns_result_decode(void *ctx, const uint8_t *data, size_t data_len, uint16_t *packet_id,
+			    struct osmo_mslookup_query *query, struct osmo_mslookup_result *result,
+			    const char *domain_suffix)
+{
+	int rc = -EINVAL;
+	struct osmo_mdns_msg_answer *ans;
+	ans = osmo_mdns_msg_answer_decode(ctx, data, data_len);
+	if (!ans)
+		goto exit_free;
+
+	if (query_from_domain(query, ans->domain, domain_suffix) < 0)
+		goto exit_free;
+
+	if (osmo_mdns_result_from_answer(result, ans) < 0)
+		goto exit_free;
+
+	*packet_id = ans->id;
+	rc = 0;
+
+exit_free:
+	talloc_free(ans);
+	return rc;
+}

src/mslookup/mdns_msg.c

@@ -0,0 +1,261 @@
+/* High level mDNS encoding and decoding functions for whole messages:
+ * Request message (header, question)
+ * Answer message (header, resource record 1, ... resource record N)*/
+
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <errno.h>
+#include <string.h>
+#include <osmocom/hlr/logging.h>
+#include <osmocom/mslookup/mdns_msg.h>
+
+/*! Encode request message into one mDNS packet, consisting of the header section and one question section.
+ * \returns 0 on success, -EINVAL on error.
+ */
+int osmo_mdns_msg_request_encode(void *ctx, struct msgb *msg, const struct osmo_mdns_msg_request *req)
+{
+	struct osmo_mdns_rfc_header hdr = {0};
+	struct osmo_mdns_rfc_question qst = {0};
+
+	hdr.id = req->id;
+	hdr.qdcount = 1;
+	osmo_mdns_rfc_header_encode(msg, &hdr);
+
+	qst.domain = req->domain;
+	qst.qtype = req->type;
+	qst.qclass = OSMO_MDNS_RFC_CLASS_IN;
+	if (osmo_mdns_rfc_question_encode(ctx, msg, &qst) != 0)
+		return -EINVAL;
+
+	return 0;
+}
+
+/*! Decode request message from a mDNS packet, consisting of the header section and one question section.
+ * \returns allocated request message on success, NULL on error.
+ */
+struct osmo_mdns_msg_request *osmo_mdns_msg_request_decode(void *ctx, const uint8_t *data, size_t data_len)
+{
+	struct osmo_mdns_rfc_header hdr = {0};
+	size_t hdr_len = sizeof(struct osmo_mdns_rfc_header);
+	struct osmo_mdns_rfc_question* qst = NULL;
+	struct osmo_mdns_msg_request *ret = NULL;
+
+	if (data_len < hdr_len || osmo_mdns_rfc_header_decode(data, hdr_len, &hdr) != 0 || hdr.qr != 0)
+		return NULL;
+
+	qst = osmo_mdns_rfc_question_decode(ctx, data + hdr_len, data_len - hdr_len);
+	if (!qst)
+		return NULL;
+
+	ret = talloc_zero(ctx, struct osmo_mdns_msg_request);
+	ret->id = hdr.id;
+	ret->domain = talloc_strdup(ret, qst->domain);
+	ret->type = qst->qtype;
+
+	talloc_free(qst);
+	return ret;
+}
+
+/*! Initialize the linked list for resource records in a answer message. */
+void osmo_mdns_msg_answer_init(struct osmo_mdns_msg_answer *ans)
+{
+	*ans = (struct osmo_mdns_msg_answer){};
+	INIT_LLIST_HEAD(&ans->records);
+}
+
+/*! Encode answer message into one mDNS packet, consisting of the header section and N resource records.
+ *
+ * To keep things simple, this sends the domain with each resource record. Other DNS implementations make use of
+ * "message compression", which would send a question section with the domain before the resource records, and then
+ * point inside each resource record with an offset back to the domain in the question section (RFC 1035 4.1.4).
+ * \returns 0 on success, -EINVAL on error.
+ */
+int osmo_mdns_msg_answer_encode(void *ctx, struct msgb *msg, const struct osmo_mdns_msg_answer *ans)
+{
+	struct osmo_mdns_rfc_header hdr = {0};
+	struct osmo_mdns_record *ans_record;
+
+	hdr.id = ans->id;
+	hdr.qr = 1;
+	hdr.ancount = llist_count(&ans->records);
+	osmo_mdns_rfc_header_encode(msg, &hdr);
+
+	llist_for_each_entry(ans_record, &ans->records, list) {
+		struct osmo_mdns_rfc_record rec = {0};
+
+		rec.domain = ans->domain;
+		rec.type = ans_record->type;
+		rec.class = OSMO_MDNS_RFC_CLASS_IN;
+		rec.ttl = 0;
+		rec.rdlength = ans_record->length;
+		rec.rdata = ans_record->data;
+
+		if (osmo_mdns_rfc_record_encode(ctx, msg, &rec) != 0)
+			return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*! Decode answer message from a mDNS packet.
+ *
+ * Answer messages must consist of one header and one or more resource records. An additional question section or
+ * message compression (RFC 1035 4.1.4) are not supported.
+* \returns allocated answer message on success, NULL on error.
+ */
+struct osmo_mdns_msg_answer *osmo_mdns_msg_answer_decode(void *ctx, const uint8_t *data, size_t data_len)
+{
+	struct osmo_mdns_rfc_header hdr = {};
+	size_t hdr_len = sizeof(struct osmo_mdns_rfc_header);
+	struct osmo_mdns_msg_answer *ret = talloc_zero(ctx, struct osmo_mdns_msg_answer);
+
+	/* Parse header section */
+	if (data_len < hdr_len || osmo_mdns_rfc_header_decode(data, hdr_len, &hdr) != 0 || hdr.qr != 1)
+		goto error;
+	ret->id = hdr.id;
+	data_len -= hdr_len;
+	data += hdr_len;
+
+	/* Parse resource records */
+	INIT_LLIST_HEAD(&ret->records);
+	while (data_len) {
+		size_t record_len;
+		struct osmo_mdns_rfc_record *rec;
+		struct osmo_mdns_record* ret_record;
+
+		rec = osmo_mdns_rfc_record_decode(ret, data, data_len, &record_len);
+		if (!rec)
+			goto error;
+
+		/* Copy domain to ret */
+		if (ret->domain) {
+			if (strcmp(ret->domain, rec->domain) != 0) {
+				LOGP(DMSLOOKUP, LOGL_ERROR, "domain mismatch in resource records ('%s' vs '%s')\n",
+				     ret->domain, rec->domain);
+				goto error;
+			}
+		}
+		else
+			ret->domain = talloc_strdup(ret, rec->domain);
+
+		/* Add simplified record to ret */
+		ret_record = talloc_zero(ret, struct osmo_mdns_record);
+		ret_record->type = rec->type;
+		ret_record->length = rec->rdlength;
+		ret_record->data = talloc_memdup(ret_record, rec->rdata, rec->rdlength);
+		llist_add_tail(&ret_record->list, &ret->records);
+
+		data += record_len;
+		data_len -= record_len;
+		talloc_free(rec);
+	}
+
+	/* Verify record count */
+	if (llist_count(&ret->records) != hdr.ancount) {
+		LOGP(DMSLOOKUP, LOGL_ERROR, "amount of parsed records (%i) doesn't match count in header (%i)\n",
+		     llist_count(&ret->records), hdr.ancount);
+		goto error;
+	}
+
+	return ret;
+error:
+	talloc_free(ret);
+	return NULL;
+}
+
+/*! Get a TXT resource record, which stores a key=value string.
+ * \returns allocated resource record on success, NULL on error.
+ */
+static struct osmo_mdns_record *_osmo_mdns_record_txt_encode(void *ctx, const char *key, const char *value)
+{
+	struct osmo_mdns_record *ret = talloc_zero(ctx, struct osmo_mdns_record);
+	size_t len = strlen(key) + 1 + strlen(value);
+
+	if (len > OSMO_MDNS_RFC_MAX_CHARACTER_STRING_LEN - 1)
+		return NULL;
+
+	/* redundant len is required, see RFC 1035 3.3.14 and 3.3. */
+	ret->data = (uint8_t *)talloc_asprintf(ctx, "%c%s=%s", (char)len, key, value);
+	if (!ret->data)
+		return NULL;
+	ret->type = OSMO_MDNS_RFC_RECORD_TYPE_TXT;
+	ret->length = len + 1;
+	return ret;
+}
+
+/*! Get a TXT resource record, which stores a key=value string, but build value from a format string.
+ * \returns allocated resource record on success, NULL on error.
+ */
+struct osmo_mdns_record *osmo_mdns_record_txt_keyval_encode(void *ctx, const char *key, const char *value_fmt, ...)
+{
+	va_list ap;
+	char *value = NULL;
+	struct osmo_mdns_record *r;
+
+	if (!value_fmt)
+		return _osmo_mdns_record_txt_encode(ctx, key, "");
+
+	va_start(ap, value_fmt);
+	value = talloc_vasprintf(ctx, value_fmt, ap);
+	va_end(ap);
+	if (!value)
+		return NULL;
+	r = _osmo_mdns_record_txt_encode(ctx, key, value);
+	talloc_free(value);
+	return r;
+}
+
+/*! Decode a TXT resource record, which stores a key=value string.
+ * \returns 0 on success, -EINVAL on error.
+ */
+int osmo_mdns_record_txt_keyval_decode(const struct osmo_mdns_record *rec,
+				       char *key_buf, size_t key_size, char *value_buf, size_t value_size)
+{
+	const char *key_value;
+	const char *key_value_end;
+	const char *sep;
+	const char *value;
+
+	if (rec->type != OSMO_MDNS_RFC_RECORD_TYPE_TXT)
+		return -EINVAL;
+
+	key_value = (const char *)rec->data;
+	key_value_end = key_value + rec->length;
+
+	/* Verify and then skip the redundant string length byte */
+	if (*key_value != rec->length - 1)
+		return -EINVAL;
+	key_value++;
+
+	if (key_value >= key_value_end)
+		return -EINVAL;
+
+	/* Find equals sign */
+	sep = osmo_strnchr(key_value, key_value_end - key_value, '=');
+	if (!sep)
+		return -EINVAL;
+
+	/* Parse key */
+	osmo_print_n(key_buf, key_size, key_value, sep - key_value);
+
+	/* Parse value */
+	value = sep + 1;
+	osmo_print_n(value_buf, value_size, value, key_value_end - value);
+	return 0;
+}

src/mslookup/mdns_rfc.c

@@ -0,0 +1,270 @@
+/* Low level mDNS encoding and decoding functions of the qname IE, header/question sections and resource records,
+ * as described in these RFCs:
+ * - RFC 1035 (Domain names - implementation and specification)
+ * - RFC 3596 (DNS Extensions to Support IP Version 6) */
+
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <string.h>
+#include <ctype.h>
+#include <errno.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/bitvec.h>
+#include <osmocom/core/logging.h>
+#include <osmocom/mslookup/mdns_rfc.h>
+
+/*
+ * Encode/decode IEs
+ */
+
+/*! Encode a domain string as qname (RFC 1035 4.1.2).
+ * \param[in] domain  multiple labels separated by dots, e.g. "sip.voice.1234.msisdn".
+ * \returns allocated buffer with length-value pairs for each label (e.g. 0x03 "sip" 0x05 "voice" ...), NULL on error.
+ */
+char *osmo_mdns_rfc_qname_encode(void *ctx, const char *domain)
+{
+	char *domain_dup;
+	char *domain_iter;
+	char buf[OSMO_MDNS_RFC_MAX_NAME_LEN + 2] = ""; /* len(qname) is len(domain) +1 */
+	struct osmo_strbuf sb = { .buf = buf, .len = sizeof(buf) };
+	char *label;
+
+	if (strlen(domain) > OSMO_MDNS_RFC_MAX_NAME_LEN)
+		return NULL;
+
+	domain_iter = domain_dup = talloc_strdup(ctx, domain);
+	while ((label = strsep(&domain_iter, "."))) {
+		size_t len = strlen(label);
+
+		/* Empty domain, dot at start, two dots in a row, or ending with a dot */
+		if (!len)
+			goto error;
+
+		OSMO_STRBUF_PRINTF(sb, "%c%s", (char)len, label);
+	}
+
+	talloc_free(domain_dup);
+	return talloc_strdup(ctx, buf);
+
+error:
+	talloc_free(domain_dup);
+	return NULL;
+}
+
+/*! Decode a domain string from a qname (RFC 1035 4.1.2).
+ * \param[in] qname  buffer with length-value pairs for each label (e.g. 0x03 "sip" 0x05 "voice" ...)
+ * \param[in] qname_max_len  amount of bytes that can be read at most from the memory location that qname points to.
+ * \returns allocated buffer with domain string, multiple labels separated by dots (e.g. "sip.voice.1234.msisdn"),
+ *	    NULL on error.
+ */
+char *osmo_mdns_rfc_qname_decode(void *ctx, const char *qname, size_t qname_max_len)
+{
+	const char *next_label, *qname_end = qname + qname_max_len;
+	char buf[OSMO_MDNS_RFC_MAX_NAME_LEN + 1];
+	int i = 0;
+
+	if (qname_max_len < 1)
+		return NULL;
+
+	while (*qname) {
+		size_t len;
+
+		if (i >= qname_max_len)
+			return NULL;
+
+		len = *qname;
+		next_label = qname + len + 1;
+
+		if (next_label >= qname_end || i + len > OSMO_MDNS_RFC_MAX_NAME_LEN)
+			return NULL;
+
+		if (i) {
+			/* Two dots in a row is not allowed */
+			if (buf[i - 1] == '.')
+				return NULL;
+
+			buf[i] = '.';
+			i++;
+		}
+
+		memcpy(buf + i, qname + 1, len);
+		i += len;
+		qname = next_label;
+	}
+	buf[i] = '\0';
+
+	return talloc_strdup(ctx, buf);
+}
+
+/*
+ * Encode/decode message sections
+ */
+
+/*! Encode header section (RFC 1035 4.1.1).
+ * \param[in] msgb  mesage buffer to which the encoded data will be appended.
+ */
+void osmo_mdns_rfc_header_encode(struct msgb *msg, const struct osmo_mdns_rfc_header *hdr)
+{
+	struct osmo_mdns_rfc_header *buf = (struct osmo_mdns_rfc_header *) msgb_put(msg, sizeof(*hdr));
+	memcpy(buf, hdr, sizeof(*hdr));
+
+	osmo_store16be(buf->id, &buf->id);
+	osmo_store16be(buf->qdcount, &buf->qdcount);
+	osmo_store16be(buf->ancount, &buf->ancount);
+	osmo_store16be(buf->nscount, &buf->nscount);
+	osmo_store16be(buf->arcount, &buf->arcount);
+}
+
+/*! Decode header section (RFC 1035 4.1.1). */
+int osmo_mdns_rfc_header_decode(const uint8_t *data, size_t data_len, struct osmo_mdns_rfc_header *hdr)
+{
+	if (data_len != sizeof(*hdr))
+		return -EINVAL;
+
+	memcpy(hdr, data, data_len);
+
+	hdr->id = osmo_load16be(&hdr->id);
+	hdr->qdcount = osmo_load16be(&hdr->qdcount);
+	hdr->ancount = osmo_load16be(&hdr->ancount);
+	hdr->nscount = osmo_load16be(&hdr->nscount);
+	hdr->arcount = osmo_load16be(&hdr->arcount);
+
+	return 0;
+}
+
+/*! Encode question section (RFC 1035 4.1.2).
+ * \param[in] msgb  mesage buffer to which the encoded data will be appended.
+ */
+int osmo_mdns_rfc_question_encode(void *ctx, struct msgb *msg, const struct osmo_mdns_rfc_question *qst)
+{
+	char *qname;
+	size_t qname_len;
+	uint8_t *qname_buf;
+
+	/* qname */
+	qname = osmo_mdns_rfc_qname_encode(ctx, qst->domain);
+	if (!qname)
+		return -EINVAL;
+	qname_len = strlen(qname) + 1;
+	qname_buf = msgb_put(msg, qname_len);
+	memcpy(qname_buf, qname, qname_len);
+	talloc_free(qname);
+
+	/* qtype and qclass */
+	msgb_put_u16(msg, qst->qtype);
+	msgb_put_u16(msg, qst->qclass);
+
+	return 0;
+}
+
+/*! Decode question section (RFC 1035 4.1.2). */
+struct osmo_mdns_rfc_question *osmo_mdns_rfc_question_decode(void *ctx, const uint8_t *data, size_t data_len)
+{
+	struct osmo_mdns_rfc_question *ret;
+	size_t qname_len = data_len - 4;
+
+	if (data_len < 6)
+		return NULL;
+
+	/* qname */
+	ret = talloc_zero(ctx, struct osmo_mdns_rfc_question);
+	if (!ret)
+		return NULL;
+	ret->domain = osmo_mdns_rfc_qname_decode(ret, (const char *)data, qname_len);
+	if (!ret->domain) {
+		talloc_free(ret);
+		return NULL;
+	}
+
+	/* qtype and qclass */
+	ret->qtype = osmo_load16be(data + qname_len);
+	ret->qclass = osmo_load16be(data + qname_len + 2);
+
+	return ret;
+}
+
+/*
+ * Encode/decode resource records
+ */
+
+/*! Encode one resource record (RFC 1035 4.1.3).
+ * \param[in] msgb  mesage buffer to which the encoded data will be appended.
+ */
+int osmo_mdns_rfc_record_encode(void *ctx, struct msgb *msg, const struct osmo_mdns_rfc_record *rec)
+{
+	char *name;
+	size_t name_len;
+	uint8_t *buf;
+
+	/* name */
+	name = osmo_mdns_rfc_qname_encode(ctx, rec->domain);
+	if (!name)
+		return -EINVAL;
+	name_len = strlen(name) + 1;
+	buf = msgb_put(msg, name_len);
+	memcpy(buf, name, name_len);
+	talloc_free(name);
+
+	/* type, class, ttl, rdlength */
+	msgb_put_u16(msg, rec->type);
+	msgb_put_u16(msg, rec->class);
+	msgb_put_u32(msg, rec->ttl);
+	msgb_put_u16(msg, rec->rdlength);
+
+	/* rdata */
+	buf = msgb_put(msg, rec->rdlength);
+	memcpy(buf, rec->rdata, rec->rdlength);
+	return 0;
+}
+
+/*! Decode one resource record (RFC 1035 4.1.3). */
+struct osmo_mdns_rfc_record *osmo_mdns_rfc_record_decode(void *ctx, const uint8_t *data, size_t data_len,
+						       size_t *record_len)
+{
+	struct osmo_mdns_rfc_record *ret = talloc_zero(ctx, struct osmo_mdns_rfc_record);
+	size_t name_len;
+
+	/* name */
+	ret->domain = osmo_mdns_rfc_qname_decode(ret, (const char *)data, data_len - 10);
+	if (!ret->domain)
+		goto error;
+	name_len = strlen(ret->domain) + 2;
+	if (name_len + 10 > data_len)
+		goto error;
+
+	/* type, class, ttl, rdlength */
+	ret->type = osmo_load16be(data + name_len);
+	ret->class = osmo_load16be(data + name_len + 2);
+	ret->ttl = osmo_load32be(data + name_len + 4);
+	ret->rdlength = osmo_load16be(data + name_len + 8);
+	if (name_len + 10 + ret->rdlength > data_len)
+		goto error;
+
+	/* rdata */
+	ret->rdata = talloc_memdup(ret, data + name_len + 10, ret->rdlength);
+	if (!ret->rdata)
+		return NULL;
+
+	*record_len = name_len + 10 + ret->rdlength;
+	return ret;
+error:
+	talloc_free(ret);
+	return NULL;
+}
+

src/mslookup/mdns_sock.c

@@ -0,0 +1,146 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <netdb.h>
+#include <stdbool.h>
+#include <talloc.h>
+#include <osmocom/core/utils.h>
+#include <osmocom/core/select.h>
+#include <osmocom/hlr/logging.h>
+#include <osmocom/mslookup/mdns_sock.h>
+
+/*! Open socket to send and receive multicast data.
+ *
+ * The socket is opened with SO_REUSEADDR, so we can bind to the same IP and port multiple times. This socket receives
+ * everything sent to that multicast IP/port, including its own data data sent from osmo_mdns_sock_send(). So whenever
+ * sending something, the receive callback will be called with the same data and should discard it.
+ *
+ * \param[in] ip  multicast IPv4 or IPv6 address.
+ * \param[in] port  port number.
+ * \param[in] cb  callback for incoming data that will be passed to osmo_fd_setup (should read from osmo_fd->fd).
+ * \param[in] data  userdata passed to osmo_fd (available in cb as osmo_fd->data).
+ * \param[in] priv_nr  additional userdata integer passed to osmo_fd (available in cb as osmo_fd->priv_nr).
+ * \returns allocated osmo_mdns_sock, NULL on error.
+ */
+struct osmo_mdns_sock *osmo_mdns_sock_init(void *ctx, const char *ip, unsigned int port,
+					   int (*cb)(struct osmo_fd *fd, unsigned int what),
+					   void *data, unsigned int priv_nr)
+{
+	struct osmo_mdns_sock *ret;
+	int sock, rc;
+	struct addrinfo hints = {0};
+	struct ip_mreq multicast_req = {0};
+	in_addr_t iface = INADDR_ANY;
+	char portbuf[10];
+	int y = 1;
+
+	snprintf(portbuf, sizeof(portbuf) -1, "%u", port);
+	ret = talloc_zero(ctx, struct osmo_mdns_sock);
+	OSMO_ASSERT(ret);
+
+	/* Fill addrinfo */
+	hints.ai_family = PF_UNSPEC;
+	hints.ai_socktype = SOCK_DGRAM;
+	hints.ai_flags = (AI_PASSIVE | AI_NUMERICHOST);
+	rc = getaddrinfo(ip, portbuf, &hints, &ret->ai);
+	if (rc != 0) {
+		LOGP(DMSLOOKUP, LOGL_ERROR, "osmo_mdns_sock_init: getaddrinfo: %s\n", gai_strerror(rc));
+		ret->ai = NULL;
+		goto error;
+	}
+
+	/* Open socket */
+	sock = socket(ret->ai->ai_family, ret->ai->ai_socktype, 0);
+	if (sock == -1) {
+		LOGP(DMSLOOKUP, LOGL_ERROR, "osmo_mdns_sock_init: socket: %s\n", strerror(errno));
+		goto error;
+	}
+
+	/* Set multicast options */
+	rc = setsockopt(sock, IPPROTO_IP, IP_MULTICAST_IF, (char*)&iface, sizeof(iface));
+	if (rc == -1) {
+		LOGP(DMSLOOKUP, LOGL_ERROR, "osmo_mdns_sock_init: setsockopt: %s\n", strerror(errno));
+		goto error_sock;
+	}
+	memcpy(&multicast_req.imr_multiaddr, &((struct sockaddr_in*)(ret->ai->ai_addr))->sin_addr,
+	       sizeof(multicast_req.imr_multiaddr));
+	multicast_req.imr_interface.s_addr = htonl(INADDR_ANY);
+	rc = setsockopt(sock, IPPROTO_IP, IP_ADD_MEMBERSHIP, (char*)&multicast_req, sizeof(multicast_req));
+	if (rc == -1) {
+		LOGP(DMSLOOKUP, LOGL_ERROR, "osmo_mdns_sock_init: setsockopt: %s\n", strerror(errno));
+		goto error_sock;
+	}
+
+	/* Always allow binding the same IP and port twice. This is needed in OsmoHLR (where the code becomes cleaner by
+	 * just using a different socket for server and client code) and in the mslookup_client_mdns_test. Also for
+	 * osmo-mslookup-client if it is running multiple times in parallel (i.e. two incoming calls almost at the same
+	 * time need to be resolved with the simple dialplan example that just starts new processes). */
+	rc = setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (char *)&y, sizeof(y));
+	if (rc == -1) {
+		LOGP(DMSLOOKUP, LOGL_ERROR, "osmo_mdns_sock_init: setsockopt: %s\n", strerror(errno));
+		goto error_sock;
+	}
+
+	/* Bind and register osmo_fd callback */
+	rc = bind(sock, ret->ai->ai_addr, ret->ai->ai_addrlen);
+	if (rc == -1) {
+		LOGP(DMSLOOKUP, LOGL_ERROR, "osmo_mdns_sock_init: bind: %s\n", strerror(errno));
+		goto error_sock;
+	}
+	osmo_fd_setup(&ret->osmo_fd, sock, OSMO_FD_READ, cb, data, priv_nr);
+	if (osmo_fd_register(&ret->osmo_fd) != 0)
+		goto error_sock;
+
+	return ret;
+error_sock:
+	close(sock);
+error:
+	if (ret->ai)
+		freeaddrinfo(ret->ai);
+	talloc_free(ret);
+	return NULL;
+}
+
+/*! Send msgb over mdns_sock and consume msgb.
+ * \returns 0 on success, -1 on error.
+ */
+int osmo_mdns_sock_send(const struct osmo_mdns_sock *mdns_sock, struct msgb *msg)
+{
+	size_t len = msgb_length(msg);
+	int rc = sendto(mdns_sock->osmo_fd.fd, msgb_data(msg), len, 0, mdns_sock->ai->ai_addr,
+			mdns_sock->ai->ai_addrlen);
+	msgb_free(msg);
+	return (rc == len) ? 0 : -1;
+}
+
+/*! Tear down osmo_mdns_sock. */
+void osmo_mdns_sock_cleanup(struct osmo_mdns_sock *mdns_sock)
+{
+	osmo_fd_close(&mdns_sock->osmo_fd);
+	freeaddrinfo(mdns_sock->ai);
+	talloc_free(mdns_sock);
+}

src/mslookup/mslookup.c

@@ -0,0 +1,321 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <string.h>
+#include <errno.h>
+#include <osmocom/gsm/gsm23003.h>
+#include <osmocom/mslookup/mslookup.h>
+
+/*! \addtogroup mslookup
+ *
+ * Distributed GSM: finding subscribers
+ *
+ * There are various aspects of the D-GSM code base in osmo-hlr.git, here is an overview:
+ *
+ * mslookup is the main enabler of D-GSM, a concept for connecting services between independent core network stacks.
+ *
+ * D-GSM consists of:
+ * (1) mslookup client to find subscribers:
+ *     (a) external clients like ESME, SIP PBX, ... ask osmo-hlr to tell where to send SMS, voice calls, ...
+ *     (b) osmo-hlr's own mslookup client asks remote osmo-hlrs whether they know a given IMSI.
+ * (2) when a subscriber was found at a remote HLR, GSUP gets forwarded there:
+ *     (a) to deliver messages for the GSUP proxy, osmo-hlr manages many GSUP clients to establish links to remote HLRs.
+ *     (b) osmo-hlr has a GSUP proxy layer that caches data of IMSIs that get proxied to a remote HLR.
+ *     (c) decision making to distinguish local IMSIs from ones proxied to a remote HLR.
+ *
+ * (1) mslookup is a method of finding subscribers using (multicast) queries, by MSISDN or by IMSI.
+ * It is open to various lookup methods, the first one being multicast DNS.
+ * An mslookup client sends a request, and an mslookup server responds.
+ * The mslookup server is implemented by osmo-hlr. mslookup clients are arbitrary programs, like an ESME or a SIP PBX.
+ * Hence the mslookup client is public API, while the mslookup server is implemented "privately" in osmo-hlr.
+ *
+ * (1a) Public mslookup client: libosmo-mslookup
+ *   src/mslookup/mslookup.c               Things useful for both client and server.
+ *   src/mslookup/mslookup_client.c        The client API, which can use various lookup methods,
+ *                                         and consolidates results from various responders.
+ *   src/mslookup/mslookup_client_mdns.c   lookup method implementing multicast DNS, client side.
+ *
+ *   src/mslookup/osmo-mslookup-client.c   Utility program to ease invocation for (blocking) mslookup clients.
+ *
+ *   src/mslookup/mslookup_client_fake.c   lookup method generating fake results, for testing client implementations.
+ *
+ *   src/mslookup/mdns*.c                  implementation of DNS to be used by mslookup_client_mdns.c,
+ *                                         and the mslookup_server.c.
+ *
+ *   contrib/dgsm/esme_dgsm.py                 Example implementation for an mslookup enabled SMS handler.
+ *   contrib/dgsm/freeswitch_dialplan_dgsm.py  Example implementation for an mslookup enabled FreeSWITCH dialplan.
+ *   contrib/dgsm/osmo-mslookup-pipe.py        Example for writing a python client using the osmo-mslookup-client
+ *                                             cmdline.
+ *   contrib/dgsm/osmo-mslookup-socket.py      Example for writing a python client using the osmo-mslookup-client
+ *                                             unix domain socket.
+ *
+ * (1b) "Private" mslookup server in osmo-hlr:
+ *   src/mslookup_server.c        Respond to mslookup queries, independent from the particular lookup method.
+ *   src/mslookup_server_mdns.c   mDNS specific implementation for mslookup_server.c.
+ *   src/dgsm_vty.c               Configure services that mslookup server sends to remote requests.
+ *
+ * (2) Proxy and GSUP clients to remote HLR instances:
+ *
+ * (a) Be a GSUP client to forward to a remote HLR:
+ *  src/gsupclient/   The same API that is used by osmo-{msc,sgsn} is also used to forward GSUP to remote osmo-hlrs.
+ *  src/remote_hlr.c  Establish links to remote osmo-hlrs, where this osmo-hlr is a client (proxying e.g. for an MSC).
+ *
+ * (b) Keep track of remotely handled IMSIs:
+ *  src/proxy.c       Keep track of proxied IMSIs and cache important subscriber data.
+ *
+ * (c) Direct GSUP request to the right destination: either the local or a remote HLR:
+ *  src/dgsm.c        The glue that makes osmo-hlr distinguish between local IMSIs and those that are proxied to another
+ *                    osmo-hlr.
+ *  src/dgsm_vty.c    Config.
+ *
+ *  @{
+ * \file mslookup.c
+ */
+
+const struct value_string osmo_mslookup_id_type_names[] = {
+	{ OSMO_MSLOOKUP_ID_NONE, "none" },
+	{ OSMO_MSLOOKUP_ID_IMSI, "imsi" },
+	{ OSMO_MSLOOKUP_ID_MSISDN, "msisdn" },
+	{}
+};
+
+const struct value_string osmo_mslookup_result_code_names[] = {
+	{ OSMO_MSLOOKUP_RC_NONE, "none" },
+	{ OSMO_MSLOOKUP_RC_RESULT, "result" },
+	{ OSMO_MSLOOKUP_RC_NOT_FOUND, "not-found" },
+	{}
+};
+
+/*! Compare two struct osmo_mslookup_id.
+ * \returns   0 if a and b are equal,
+ *          < 0 if a (or the ID type / start of ID) is < b,
+ *          > 0 if a (or the ID type / start of ID) is > b.
+ */
+int osmo_mslookup_id_cmp(const struct osmo_mslookup_id *a, const struct osmo_mslookup_id *b)
+{
+	int cmp;
+	if (a == b)
+		return 0;
+	if (!a)
+		return -1;
+	if (!b)
+		return 1;
+
+	cmp = OSMO_CMP(a->type, b->type);
+	if (cmp)
+		return cmp;
+
+	switch (a->type) {
+	case OSMO_MSLOOKUP_ID_IMSI:
+		return strncmp(a->imsi, b->imsi, sizeof(a->imsi));
+	case OSMO_MSLOOKUP_ID_MSISDN:
+		return strncmp(a->msisdn, b->msisdn, sizeof(a->msisdn));
+	default:
+		return 0;
+	}
+}
+
+bool osmo_mslookup_id_valid(const struct osmo_mslookup_id *id)
+{
+	switch (id->type) {
+	case OSMO_MSLOOKUP_ID_IMSI:
+		return osmo_imsi_str_valid(id->imsi);
+	case OSMO_MSLOOKUP_ID_MSISDN:
+		return osmo_msisdn_str_valid(id->msisdn);
+	default:
+		return false;
+	}
+}
+
+bool osmo_mslookup_service_valid(const char *service)
+{
+	return strlen(service) > 0;
+}
+
+/*! Write ID and ID type to a buffer.
+ * \param[out] buf  nul-terminated {id}.{id_type} string (e.g. "1234.msisdn") or
+* 		    "?.none" if the ID type is invalid.
+ * \returns amount of bytes written to buf.
+ */
+size_t osmo_mslookup_id_name_buf(char *buf, size_t buflen, const struct osmo_mslookup_id *id)
+{
+	struct osmo_strbuf sb = { .buf = buf, .len = buflen };
+	switch (id->type) {
+	case OSMO_MSLOOKUP_ID_IMSI:
+		OSMO_STRBUF_PRINTF(sb, "%s", id->imsi);
+		break;
+	case OSMO_MSLOOKUP_ID_MSISDN:
+		OSMO_STRBUF_PRINTF(sb, "%s", id->msisdn);
+		break;
+	default:
+		OSMO_STRBUF_PRINTF(sb, "?");
+		break;
+	}
+	OSMO_STRBUF_PRINTF(sb, ".%s", osmo_mslookup_id_type_name(id->type));
+	return sb.chars_needed;
+}
+
+/*! Same as osmo_mslookup_id_name_buf(), but return a talloc allocated string of sufficient size. */
+char *osmo_mslookup_id_name_c(void *ctx, const struct osmo_mslookup_id *id)
+{
+	OSMO_NAME_C_IMPL(ctx, 64, "ERROR", osmo_mslookup_id_name_buf, id)
+}
+
+/*! Same as osmo_mslookup_id_name_buf(), but directly return the char* (for printf-like string formats). */
+char *osmo_mslookup_id_name_b(char *buf, size_t buflen, const struct osmo_mslookup_id *id)
+{
+	int rc = osmo_mslookup_id_name_buf(buf, buflen, id);
+	if (rc < 0 && buflen)
+		buf[0] = '\0';
+	return buf;
+}
+
+/*! Write mslookup result string to buffer.
+ * \param[in] query  with the service, ID and ID type to be written to buf like a domain string, or NULL to omit.
+ * \param[in] result with the result code, IPv4/v6 and age to be written to buf or NULL to omit.
+ * \param[out] buf  result as flat string, which looks like the following for a valid query and result with IPv4 and v6
+ *                  answer: "sip.voice.1234.msisdn -> ipv4: 42.42.42.42:1337 -> ipv6: [1234:5678:9ABC::]:1338 (age=1)",
+ *                  the result part can also be " -> timeout" or " -> rc=5" depending on the result code.
+ * \returns amount of bytes written to buf.
+ */
+size_t osmo_mslookup_result_to_str_buf(char *buf, size_t buflen,
+				     const struct osmo_mslookup_query *query,
+				     const struct osmo_mslookup_result *result)
+{
+	struct osmo_strbuf sb = { .buf = buf, .len = buflen };
+	if (query) {
+		OSMO_STRBUF_PRINTF(sb, "%s.", query->service);
+		OSMO_STRBUF_APPEND(sb, osmo_mslookup_id_name_buf, &query->id);
+	}
+	if (result && result->rc == OSMO_MSLOOKUP_RC_NONE)
+		result = NULL;
+	if (result) {
+		if (result->rc != OSMO_MSLOOKUP_RC_RESULT) {
+			OSMO_STRBUF_PRINTF(sb, " %s", osmo_mslookup_result_code_name(result->rc));
+		} else {
+			if (result->host_v4.ip[0]) {
+				OSMO_STRBUF_PRINTF(sb, " -> ipv4: " OSMO_SOCKADDR_STR_FMT,
+						   OSMO_SOCKADDR_STR_FMT_ARGS(&result->host_v4));
+			}
+			if (result->host_v6.ip[0]) {
+				OSMO_STRBUF_PRINTF(sb, " -> ipv6: " OSMO_SOCKADDR_STR_FMT,
+						   OSMO_SOCKADDR_STR_FMT_ARGS(&result->host_v6));
+			}
+			OSMO_STRBUF_PRINTF(sb, " (age=%u)", result->age);
+		}
+		OSMO_STRBUF_PRINTF(sb, " %s", result->last ? "(last)" : "(not-last)");
+	}
+	return sb.chars_needed;
+}
+
+/*! Same as osmo_mslookup_result_to_str_buf(), but return a talloc allocated string of sufficient size. */
+char *osmo_mslookup_result_name_c(void *ctx,
+				  const struct osmo_mslookup_query *query,
+				  const struct osmo_mslookup_result *result)
+{
+	OSMO_NAME_C_IMPL(ctx, 64, "ERROR", osmo_mslookup_result_to_str_buf, query, result)
+}
+
+/*! Same as osmo_mslookup_result_to_str_buf(), but directly return the char* (for printf-like string formats). */
+char *osmo_mslookup_result_name_b(char *buf, size_t buflen,
+				  const struct osmo_mslookup_query *query,
+				  const struct osmo_mslookup_result *result)
+{
+	int rc = osmo_mslookup_result_to_str_buf(buf, buflen, query, result);
+	if (rc < 0 && buflen)
+		buf[0] = '\0';
+	return buf;
+}
+
+/*! Copy part of a string to a buffer and nul-terminate it.
+ * \returns 0 on success, negative on error.
+ */
+static int token(char *dest, size_t dest_size, const char *start, const char *end)
+{
+	int len;
+	if (start >= end)
+		return -10;
+	len = end - start;
+	if (len >= dest_size)
+		return -11;
+	strncpy(dest, start, len);
+	dest[len] = '\0';
+	return 0;
+}
+
+/*! Parse a string like "foo.moo.goo.123456789012345.msisdn" into service="foo.moo.goo", id="123456789012345" and
+ * id_type="msisdn", placed in a struct osmo_mslookup_query.
+ * \param q  Write parsed query to this osmo_mslookup_query.
+ * \param domain  Human readable domain string like "sip.voice.12345678.msisdn".
+ * \returns 0 on success, negative on error.
+ */
+int osmo_mslookup_query_init_from_domain_str(struct osmo_mslookup_query *q, const char *domain)
+{
+	const char *last_dot;
+	const char *second_last_dot;
+	const char *id_type;
+	const char *id;
+	int rc;
+
+	*q = (struct osmo_mslookup_query){};
+
+	if (!domain)
+		return -1;
+
+	last_dot = strrchr(domain, '.');
+
+	if (!last_dot)
+		return -2;
+
+	if (last_dot <= domain)
+		return -3;
+
+	for (second_last_dot = last_dot - 1; second_last_dot > domain && *second_last_dot != '.'; second_last_dot--);
+	if (second_last_dot == domain || *second_last_dot != '.')
+		return -3;
+
+	id_type = last_dot + 1;
+	if (!*id_type)
+		return -4;
+
+	q->id.type = get_string_value(osmo_mslookup_id_type_names, id_type);
+
+	id = second_last_dot + 1;
+	switch (q->id.type) {
+	case OSMO_MSLOOKUP_ID_IMSI:
+		rc = token(q->id.imsi, sizeof(q->id.imsi), id, last_dot);
+		if (rc)
+			return rc;
+		if (!osmo_imsi_str_valid(q->id.imsi))
+			return -5;
+		break;
+	case OSMO_MSLOOKUP_ID_MSISDN:
+		rc = token(q->id.msisdn, sizeof(q->id.msisdn), id, last_dot);
+		if (rc)
+			return rc;
+		if (!osmo_msisdn_str_valid(q->id.msisdn))
+			return -6;
+		break;
+	default:
+		return -7;
+	}
+
+	return token(q->service, sizeof(q->service), domain, second_last_dot);
+}
+
+/*! @} */

src/mslookup/mslookup_client.c

@@ -0,0 +1,310 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <osmocom/hlr/logging.h>
+#include <osmocom/mslookup/mslookup_client.h>
+
+/*! Lookup client's internal data for a query. */
+struct osmo_mslookup_client {
+	struct llist_head lookup_methods;
+	struct llist_head requests;
+	uint32_t next_request_handle;
+};
+
+/*! Lookup client's internal data for a query.
+ * The request methods only get to see the query part, and result handling is done commonly for all request methods. */
+struct osmo_mslookup_client_request {
+	struct llist_head entry;
+	struct osmo_mslookup_client *client;
+	uint32_t request_handle;
+
+	struct osmo_mslookup_query query;
+	struct osmo_mslookup_query_handling handling;
+	struct osmo_timer_list timeout;
+	bool waiting_min_delay;
+
+	struct osmo_mslookup_result result;
+};
+
+static struct osmo_mslookup_client_request *get_request(struct osmo_mslookup_client *client, uint32_t request_handle)
+{
+	struct osmo_mslookup_client_request *r;
+	if (!request_handle)
+		return NULL;
+	llist_for_each_entry(r, &client->requests, entry) {
+		if (r->request_handle == request_handle)
+			return r;
+	}
+	return NULL;
+}
+
+struct osmo_mslookup_client *osmo_mslookup_client_new(void *ctx)
+{
+	struct osmo_mslookup_client *client = talloc_zero(ctx, struct osmo_mslookup_client);
+	OSMO_ASSERT(client);
+	INIT_LLIST_HEAD(&client->lookup_methods);
+	INIT_LLIST_HEAD(&client->requests);
+	return client;
+}
+
+/*! Return whether any lookup methods are available.
+ * \param[in] client  Client to query.
+ * \return true when a client is present that has at least one osmo_mslookup_client_method registered.
+ */
+bool osmo_mslookup_client_active(struct osmo_mslookup_client *client)
+{
+	if (!client)
+		return false;
+	if (llist_empty(&client->lookup_methods))
+		return false;
+	return true;
+}
+
+static void _osmo_mslookup_client_method_del(struct osmo_mslookup_client_method *method)
+{
+	if (method->destruct)
+		method->destruct(method);
+	llist_del(&method->entry);
+	talloc_free(method);
+}
+
+/*! Stop and free mslookup client and all registered lookup methods.
+ */
+void osmo_mslookup_client_free(struct osmo_mslookup_client *client)
+{
+	struct osmo_mslookup_client_method *m, *n;
+	if (!client)
+		return;
+	llist_for_each_entry_safe(m, n, &client->lookup_methods, entry) {
+		_osmo_mslookup_client_method_del(m);
+	}
+	talloc_free(client);
+}
+
+/*! Add an osmo_mslookup_client_method to service MS Lookup requests.
+ * Note, osmo_mslookup_client_method_del() will talloc_free() the method pointer, so it needs to be dynamically
+ * allocated.
+ * \param client  The osmo_mslookup_client instance to add to.
+ * \param method  A fully initialized method struct, allocated by talloc.
+ */
+void osmo_mslookup_client_method_add(struct osmo_mslookup_client *client,
+				     struct osmo_mslookup_client_method *method)
+{
+	method->client = client;
+	llist_add_tail(&method->entry, &client->lookup_methods);
+}
+
+/*! \return false if the method was not listed, true if the method was listed, removed and talloc_free()d.
+ */
+bool osmo_mslookup_client_method_del(struct osmo_mslookup_client *client,
+				     struct osmo_mslookup_client_method *method)
+{
+	struct osmo_mslookup_client_method *m;
+	llist_for_each_entry(m, &client->lookup_methods, entry) {
+		if (m == method) {
+			_osmo_mslookup_client_method_del(method);
+			return true;
+		}
+	}
+	return false;
+}
+
+static void osmo_mslookup_request_send_result(struct osmo_mslookup_client_request *r, bool finish)
+{
+	struct osmo_mslookup_client *client = r->client;
+	uint32_t request_handle = r->request_handle;
+
+	r->result.last = finish;
+	r->handling.result_cb(r->client, r->request_handle, &r->query, &r->result);
+
+	/* Make sure the request struct is discarded.
+	 * The result_cb() may already have triggered a cleanup, so query by request_handle. */
+	if (finish)
+		osmo_mslookup_client_request_cancel(client, request_handle);
+}
+
+void osmo_mslookup_client_rx_result(struct osmo_mslookup_client *client, uint32_t request_handle,
+				    const struct osmo_mslookup_result *result)
+{
+	struct osmo_mslookup_client_request *req = get_request(client, request_handle);
+
+	if (!req) {
+		LOGP(DMSLOOKUP, LOGL_ERROR,
+		     "Internal error: Got mslookup result for a request that does not exist (handle %u)\n",
+		     request_handle);
+		return;
+	}
+
+	/* Ignore incoming results that are not successful */
+	if (result->rc != OSMO_MSLOOKUP_RC_RESULT)
+		return;
+
+	/* If we already stored an earlier successful result, keep that if its age is younger. */
+	if (req->result.rc == OSMO_MSLOOKUP_RC_RESULT
+	    && result->age >= req->result.age)
+		return;
+
+	req->result = *result;
+
+	/* If age == 0, it doesn't get any better, so return the result immediately. */
+	if (req->result.age == 0) {
+		osmo_mslookup_request_send_result(req, true);
+		return;
+	}
+
+	if (req->waiting_min_delay)
+		return;
+
+	osmo_mslookup_request_send_result(req, false);
+}
+
+static void _osmo_mslookup_client_request_cleanup(struct osmo_mslookup_client_request *r)
+{
+	struct osmo_mslookup_client_method *m;
+	osmo_timer_del(&r->timeout);
+	llist_for_each_entry(m, &r->client->lookup_methods, entry) {
+		if (!m->request_cleanup)
+			continue;
+		m->request_cleanup(m, r->request_handle);
+	}
+	llist_del(&r->entry);
+	talloc_free(r);
+}
+
+static void timeout_cb(void *data);
+
+static void set_timer(struct osmo_mslookup_client_request *r, unsigned long milliseconds)
+{
+	osmo_timer_setup(&r->timeout, timeout_cb, r);
+	osmo_timer_schedule(&r->timeout, milliseconds / 1000, (milliseconds % 1000) * 1000);
+}
+
+static void timeout_cb(void *data)
+{
+	struct osmo_mslookup_client_request *r = data;
+	if (r->waiting_min_delay) {
+		/* The initial delay has passed. See if it stops here, or whether the overall timeout continues. */
+		r->waiting_min_delay = false;
+
+		if (r->handling.result_timeout_milliseconds <= r->handling.min_wait_milliseconds) {
+			/* It ends here. Return a final result. */
+			if (r->result.rc != OSMO_MSLOOKUP_RC_RESULT)
+				r->result.rc = OSMO_MSLOOKUP_RC_NOT_FOUND;
+			osmo_mslookup_request_send_result(r, true);
+			return;
+		}
+
+		/* We continue to listen for results. If one is already on record, send it now. */
+		if (r->result.rc == OSMO_MSLOOKUP_RC_RESULT)
+			osmo_mslookup_request_send_result(r, false);
+
+		set_timer(r, r->handling.result_timeout_milliseconds - r->handling.min_wait_milliseconds);
+		return;
+	}
+	/* The final timeout has passed, finish and clean up the request. */
+	switch (r->result.rc) {
+	case OSMO_MSLOOKUP_RC_RESULT:
+		/* If the rc == OSMO_MSLOOKUP_RC_RESULT, this result has already been sent.
+		 * Don't send it again, instead send an RC_NONE, last=true result. */
+		r->result.rc = OSMO_MSLOOKUP_RC_NONE;
+		break;
+	default:
+		r->result.rc = OSMO_MSLOOKUP_RC_NOT_FOUND;
+		break;
+	}
+	osmo_mslookup_request_send_result(r, true);
+}
+
+/*! Launch a subscriber lookup with the provided query.
+ * A request is cleared implicitly when the handling->result_cb is invoked; if the quer->priv pointer becomes invalid
+ * before that, a request should be canceled by calling osmo_mslookup_client_request_cancel() with the returned
+ * request_handle. A request handle of zero indicates error.
+ * \return a nonzero request_handle that allows ending the request, or 0 on invalid query data. */
+uint32_t osmo_mslookup_client_request(struct osmo_mslookup_client *client,
+				      const struct osmo_mslookup_query *query,
+				      const struct osmo_mslookup_query_handling *handling)
+{
+	struct osmo_mslookup_client_request *r;
+	struct osmo_mslookup_client_request *other;
+	struct osmo_mslookup_client_method *m;
+
+	if (!osmo_mslookup_service_valid(query->service)
+	    || !osmo_mslookup_id_valid(&query->id)) {
+		char buf[256];
+		LOGP(DMSLOOKUP, LOGL_ERROR, "Invalid query: %s\n",
+		     osmo_mslookup_result_name_b(buf, sizeof(buf), query, NULL));
+		return 0;
+	}
+
+	r = talloc_zero(client, struct osmo_mslookup_client_request);
+	OSMO_ASSERT(r);
+
+	/* A request_handle of zero means error, so make sure we don't use a zero handle. */
+	if (!client->next_request_handle)
+		client->next_request_handle++;
+	*r = (struct osmo_mslookup_client_request){
+		.client = client,
+		.query = *query,
+		.handling = *handling,
+		.request_handle = client->next_request_handle++,
+	};
+
+	if (!r->handling.result_timeout_milliseconds)
+		r->handling.result_timeout_milliseconds = r->handling.min_wait_milliseconds;
+	if (!r->handling.result_timeout_milliseconds)
+		r->handling.result_timeout_milliseconds = 1000;
+
+	/* Paranoia: make sure a request_handle exists only once, by expiring an already existing one. This is unlikely
+	 * to happen in practice: before we get near wrapping a uint32_t range, previous requests should long have
+	 * timed out or ended. */
+	llist_for_each_entry(other, &client->requests, entry) {
+		if (other->request_handle != r->request_handle)
+			continue;
+		osmo_mslookup_request_send_result(other, true);
+		/* we're sure it exists only once. */
+		break;
+	}
+
+	/* Now sure that the new request_handle does not exist a second time. */
+	llist_add_tail(&r->entry, &client->requests);
+
+	if (r->handling.min_wait_milliseconds) {
+		r->waiting_min_delay = true;
+		set_timer(r, r->handling.min_wait_milliseconds);
+	} else {
+		set_timer(r, r->handling.result_timeout_milliseconds);
+	}
+
+	/* Let the lookup implementations know */
+	llist_for_each_entry(m, &client->lookup_methods, entry) {
+		m->request(m, query, r->request_handle);
+	}
+	return r->request_handle;
+}
+
+/*! End or cancel a subscriber lookup. This *must* be invoked exactly once per osmo_mslookup_client_request() invocation,
+ * either after a lookup has concluded or to abort an ongoing lookup.
+ * \param[in] request_handle  The request_handle returned by an osmo_mslookup_client_request() invocation.
+ */
+void osmo_mslookup_client_request_cancel(struct osmo_mslookup_client *client, uint32_t request_handle)
+{
+	struct osmo_mslookup_client_request *r = get_request(client, request_handle);
+	if (!r)
+		return;
+	_osmo_mslookup_client_request_cleanup(r);
+}

src/mslookup/mslookup_client_fake.c

@@ -0,0 +1,156 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <osmocom/hlr/logging.h>
+#include <osmocom/mslookup/mslookup_client.h>
+#include <osmocom/mslookup/mslookup_client_fake.h>
+
+#include <string.h>
+
+/* Fake mslookup method */
+
+struct fake_lookup_state {
+	struct osmo_mslookup_client *client;
+	struct llist_head requests;
+	struct osmo_timer_list async_response_timer;
+	struct osmo_mslookup_fake_response *responses;
+	size_t responses_len;
+};
+
+struct fake_lookup_request {
+	struct llist_head entry;
+	uint32_t request_handle;
+	struct osmo_mslookup_query query;
+	struct timeval received_at;
+};
+
+/*! Args for osmo_timer_schedule: seconds and microseconds. */
+#define ASYNC_RESPONSE_PERIOD 0, (1e6 / 10)
+static void fake_lookup_async_response(void *state);
+
+static void fake_lookup_request(struct osmo_mslookup_client_method *method,
+				const struct osmo_mslookup_query *query,
+				uint32_t request_handle)
+{
+	struct fake_lookup_state *state = method->priv;
+	char buf[256];
+	LOGP(DMSLOOKUP, LOGL_DEBUG, "%s(%s)\n", __func__, osmo_mslookup_result_name_b(buf, sizeof(buf), query, NULL));
+
+	/* A real implementation would send packets to some remote server.
+	 * Here this is simulated: add to the list of requests, which fake_lookup_async_response() will reply upon
+	 * according to the test data listing the replies that the test wants to generate. */
+
+	struct fake_lookup_request *r = talloc_zero(method->client, struct fake_lookup_request);
+	*r = (struct fake_lookup_request){
+		.request_handle = request_handle,
+		.query = *query,
+	};
+	osmo_gettimeofday(&r->received_at, NULL);
+	llist_add_tail(&r->entry, &state->requests);
+}
+
+static void fake_lookup_request_cleanup(struct osmo_mslookup_client_method *method,
+					uint32_t request_handle)
+{
+	struct fake_lookup_state *state = method->priv;
+
+	/* Tear down any state associated with this handle. */
+	struct fake_lookup_request *r;
+	llist_for_each_entry(r, &state->requests, entry) {
+		if (r->request_handle != request_handle)
+			continue;
+		llist_del(&r->entry);
+		talloc_free(r);
+		LOGP(DMSLOOKUP, LOGL_DEBUG, "%s() ok\n", __func__);
+		return;
+	}
+	LOGP(DMSLOOKUP, LOGL_DEBUG, "%s() FAILED\n", __func__);
+}
+
+static void fake_lookup_async_response(void *data)
+{
+	struct fake_lookup_state *state = data;
+	struct fake_lookup_request *req, *n;
+	struct timeval now;
+	char str[256];
+
+	osmo_gettimeofday(&now, NULL);
+
+	llist_for_each_entry_safe(req, n, &state->requests, entry) {
+		struct osmo_mslookup_fake_response *resp;
+
+		for (resp = state->responses;
+		     (resp - state->responses) < state->responses_len;
+		     resp++) {
+			struct timeval diff;
+
+			if (resp->sent)
+				continue;
+			if (osmo_mslookup_id_cmp(&req->query.id, &resp->for_id) != 0)
+				continue;
+			if (strcmp(req->query.service, resp->for_service) != 0)
+				continue;
+
+			timersub(&now, &req->received_at, &diff);
+			if (timercmp(&diff, &resp->time_to_reply, <))
+				continue;
+
+			/* It's time to reply to this request. */
+			LOGP(DMSLOOKUP, LOGL_DEBUG, "osmo_mslookup_client_rx_result(): %s\n",
+			     osmo_mslookup_result_name_b(str, sizeof(str), &req->query, &resp->result));
+			osmo_mslookup_client_rx_result(state->client, req->request_handle, &resp->result);
+			resp->sent = true;
+
+			/* The req will have been cleaned up now, so we must not iterate over state->responses anymore
+			 * with this req. */
+			break;
+		}
+	}
+
+	osmo_timer_schedule(&state->async_response_timer, ASYNC_RESPONSE_PERIOD);
+}
+
+struct osmo_mslookup_client_method *osmo_mslookup_client_add_fake(struct osmo_mslookup_client *client,
+								  struct osmo_mslookup_fake_response *responses,
+								  size_t responses_len)
+{
+	struct osmo_mslookup_client_method *method = talloc_zero(client, struct osmo_mslookup_client_method);
+	OSMO_ASSERT(method);
+
+	struct fake_lookup_state *state = talloc_zero(method, struct fake_lookup_state);
+	OSMO_ASSERT(state);
+	*state = (struct fake_lookup_state){
+		.client = client,
+		.responses = responses,
+		.responses_len = responses_len,
+	};
+	INIT_LLIST_HEAD(&state->requests);
+
+	*method = (struct osmo_mslookup_client_method){
+		.name = "fake",
+		.priv = state,
+		.request = fake_lookup_request,
+		.request_cleanup = fake_lookup_request_cleanup,
+	};
+
+	osmo_timer_setup(&state->async_response_timer, fake_lookup_async_response, state);
+	osmo_mslookup_client_method_add(client, method);
+
+	osmo_timer_schedule(&state->async_response_timer, ASYNC_RESPONSE_PERIOD);
+	return method;
+}

src/mslookup/mslookup_client_mdns.c

@@ -0,0 +1,236 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
+#include <unistd.h>
+#include <errno.h>
+#include <osmocom/core/select.h>
+#include <osmocom/gsm/gsm_utils.h>
+#include <osmocom/hlr/logging.h>
+#include <osmocom/mslookup/mdns.h>
+#include <osmocom/mslookup/mdns_sock.h>
+#include <osmocom/mslookup/mslookup_client.h>
+#include <osmocom/mslookup/mslookup_client_mdns.h>
+
+struct osmo_mdns_method_state {
+	/* Parameters passed by _add_method_dns() */
+	struct osmo_sockaddr_str bind_addr;
+	const char *domain_suffix;
+
+	struct osmo_mdns_sock *mc;
+
+	struct osmo_mslookup_client *client;
+	struct llist_head requests;
+	uint16_t next_packet_id;
+};
+
+struct osmo_mdns_method_request {
+	struct llist_head entry;
+	uint32_t request_handle;
+	struct osmo_mslookup_query query;
+	uint16_t packet_id;
+};
+
+static int request_handle_by_query(uint32_t *request_handle, struct osmo_mdns_method_state *state,
+				   struct osmo_mslookup_query *query, uint16_t packet_id)
+{
+	struct osmo_mdns_method_request *request;
+
+	llist_for_each_entry(request, &state->requests, entry) {
+		if (strcmp(request->query.service, query->service) != 0)
+			continue;
+		if (osmo_mslookup_id_cmp(&request->query.id, &query->id) != 0)
+			continue;
+
+		/* Match! */
+		*request_handle = request->request_handle;
+		return 0;
+	}
+	return -1;
+}
+
+static int mdns_method_recv(struct osmo_fd *osmo_fd, unsigned int what)
+{
+	struct osmo_mdns_method_state *state = osmo_fd->data;
+	struct osmo_mslookup_result result;
+	struct osmo_mslookup_query query;
+	uint16_t packet_id;
+	int n;
+	uint8_t buffer[1024];
+	uint32_t request_handle = 0;
+	void *ctx = state;
+
+	n = read(osmo_fd->fd, buffer, sizeof(buffer));
+	if (n < 0) {
+		LOGP(DMSLOOKUP, LOGL_ERROR, "failed to read from socket\n");
+		return n;
+	}
+
+	if (osmo_mdns_result_decode(ctx, buffer, n, &packet_id, &query, &result, state->domain_suffix) < 0)
+		return -EINVAL;
+
+	if (request_handle_by_query(&request_handle, state, &query, packet_id) != 0)
+		return -EINVAL;
+
+	osmo_mslookup_client_rx_result(state->client, request_handle, &result);
+	return n;
+}
+
+static void mdns_method_request(struct osmo_mslookup_client_method *method, const struct osmo_mslookup_query *query,
+				uint32_t request_handle)
+{
+	char buf[256];
+	struct osmo_mdns_method_state *state = method->priv;
+	struct msgb *msg;
+	struct osmo_mdns_method_request *r = talloc_zero(method->client, struct osmo_mdns_method_request);
+
+	*r = (struct osmo_mdns_method_request){
+		.request_handle = request_handle,
+		.query = *query,
+		.packet_id = state->next_packet_id,
+	};
+	llist_add(&r->entry, &state->requests);
+	state->next_packet_id++;
+
+	msg = osmo_mdns_query_encode(method->client, r->packet_id, query, state->domain_suffix);
+	if (!msg) {
+		LOGP(DMSLOOKUP, LOGL_ERROR, "Cannot encode request: %s\n",
+		     osmo_mslookup_result_name_b(buf, sizeof(buf), query, NULL));
+		return;
+	}
+
+	/* Send over the wire */
+	LOGP(DMSLOOKUP, LOGL_DEBUG, "sending mDNS query: %s.%s\n", query->service,
+	     osmo_mslookup_id_name_b(buf, sizeof(buf), &query->id));
+	if (osmo_mdns_sock_send(state->mc, msg) == -1)
+		LOGP(DMSLOOKUP, LOGL_ERROR, "sending mDNS query failed\n");
+}
+
+static void mdns_method_request_cleanup(struct osmo_mslookup_client_method *method, uint32_t request_handle)
+{
+	struct osmo_mdns_method_state *state = method->priv;
+
+	/* Tear down any state associated with this handle. */
+	struct osmo_mdns_method_request *r;
+	llist_for_each_entry(r, &state->requests, entry) {
+		if (r->request_handle != request_handle)
+			continue;
+		llist_del(&r->entry);
+		talloc_free(r);
+		return;
+	}
+}
+
+static void mdns_method_destruct(struct osmo_mslookup_client_method *method)
+{
+	struct osmo_mdns_method_state *state = method->priv;
+	struct osmo_mdns_method_request *e, *n;
+	if (!state)
+		return;
+
+	/* Drop all DNS lookup request state. Triggering a timeout event and cleanup for mslookup client users will
+	 * happen in the mslookup_client.c, we will simply stop responding from this lookup method. */
+	llist_for_each_entry_safe(e, n, &state->requests, entry) {
+		llist_del(&e->entry);
+	}
+
+	osmo_mdns_sock_cleanup(state->mc);
+}
+
+/*! Initialize the mDNS lookup method.
+ * \param[in] client  the client to attach the method to.
+ * \param[in] ip  IPv4 or IPv6 address string.
+ * \param[in] port  The port to bind to.
+ * \param[in] initial_packet_id  Used in the first mslookup query, then increased by one in each following query. All
+ *				 servers answer to each query with the same packet ID. Set to -1 to use a random
+ *				 initial ID (recommended unless you need deterministic output). This ID is for visually
+ *				 distinguishing the packets in packet sniffers, the mslookup client uses not just the
+ *				 ID, but all query parameters (service type, ID, ID type), to determine if a reply is
+ *				 relevant.
+ * \param[in] domain_suffix  is appended to each domain in the queries to avoid colliding with the top-level domains
+ *                           administrated by IANA. Example: "mdns.osmocom.org" */
+struct osmo_mslookup_client_method *osmo_mslookup_client_add_mdns(struct osmo_mslookup_client *client, const char *ip,
+								  uint16_t port, int initial_packet_id,
+								  const char *domain_suffix)
+{
+	struct osmo_mdns_method_state *state;
+	struct osmo_mslookup_client_method *m;
+
+	m = talloc_zero(client, struct osmo_mslookup_client_method);
+	OSMO_ASSERT(m);
+
+	state = talloc_zero(m, struct osmo_mdns_method_state);
+	OSMO_ASSERT(state);
+	INIT_LLIST_HEAD(&state->requests);
+	if (osmo_sockaddr_str_from_str(&state->bind_addr, ip, port)) {
+		LOGP(DMSLOOKUP, LOGL_ERROR, "mslookup mDNS: invalid address/port: %s %u\n",
+		     ip, port);
+		goto error_cleanup;
+	}
+
+	if (initial_packet_id == -1) {
+		if (osmo_get_rand_id((uint8_t *)&state->next_packet_id, 2) < 0) {
+			LOGP(DMSLOOKUP, LOGL_ERROR, "mslookup mDNS: failed to generate random initial packet ID\n");
+			goto error_cleanup;
+		}
+	} else
+		state->next_packet_id = initial_packet_id;
+
+	state->client = client;
+	state->domain_suffix = domain_suffix;
+
+	state->mc = osmo_mdns_sock_init(state, ip, port, mdns_method_recv, state, 0);
+	if (!state->mc)
+		goto error_cleanup;
+
+	*m = (struct osmo_mslookup_client_method){
+		.name = "mDNS",
+		.priv = state,
+		.request = mdns_method_request,
+		.request_cleanup = mdns_method_request_cleanup,
+		.destruct = mdns_method_destruct,
+	};
+
+	osmo_mslookup_client_method_add(client, m);
+	return m;
+
+error_cleanup:
+	talloc_free(m);
+	return NULL;
+}
+
+const struct osmo_sockaddr_str *osmo_mslookup_client_method_mdns_get_bind_addr(struct osmo_mslookup_client_method *dns_method)
+{
+	struct osmo_mdns_method_state *state;
+	if (!dns_method || !dns_method->priv)
+		return NULL;
+	state = dns_method->priv;
+	return &state->bind_addr;
+}
+
+const char *osmo_mslookup_client_method_mdns_get_domain_suffix(struct osmo_mslookup_client_method *dns_method)
+{
+	struct osmo_mdns_method_state *state;
+	if (!dns_method || !dns_method->priv)
+		return NULL;
+	state = dns_method->priv;
+	return state->domain_suffix;
+}

src/mslookup/osmo-mslookup-client.c

@@ -0,0 +1,885 @@
+/*! \file osmo-mslookup-client.c
+ * Distributed GSM: find the location of subscribers, for example by multicast DNS,
+ * to obtain HLR, SIP or SMPP server addresses (or arbitrary service names).
+ */
+/*
+ * (C) 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ * (C) 2019 by Neels Hofmeyr <neels@hofmeyr.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <getopt.h>
+#include <errno.h>
+#include <talloc.h>
+#include <sys/un.h>
+
+#include <osmocom/core/application.h>
+#include <osmocom/core/logging.h>
+#include <osmocom/core/select.h>
+#include <osmocom/core/socket.h>
+#include <osmocom/mslookup/mslookup_client.h>
+#include <osmocom/mslookup/mslookup_client_mdns.h>
+#include <osmocom/mslookup/mdns_sock.h>
+#include <osmocom/mslookup/mdns.h>
+
+#define CSV_HEADERS "query\tresult\tlast\tage\tv4_ip\tv4_port\tv6_ip\tv6_port"
+
+static void print_version(void)
+{
+	printf("osmo-mslookup-client version %s\n", PACKAGE_VERSION);
+	printf("\n"
+	"Copyright (C) 2019 by sysmocom - s.f.m.c. GmbH\n"
+	"Copyright (C) 2019 by Neels Hofmeyr <neels@hofmeyr.de>\n"
+	"This program is free software; you can redistribute it and/or modify\n"
+	"it under the terms of the GNU General Public License as published by\n"
+	"the Free Software Foundation; either version 2 of the License, or\n"
+	"(at your option) any later version.\n"
+	"\n");
+}
+
+static void print_help()
+{
+	print_version();
+	printf(
+"Standalone mslookup client for Distributed GSM\n"
+"\n"
+"Receiving mslookup results means listening for responses on a socket. Often,\n"
+"integration (e.g. FreeSwitch dialplan.py) makes it hard to select() on a socket\n"
+"to read responses, because that interferes with the main program (e.g.\n"
+"FreeSwitch's dialplan.py seems to be integrated with an own select() main loop\n"
+"that interferes with osmo_select_main(), or an smpp.py uses\n"
+"smpplib.client.listen() as main loop, etc.).\n"
+"\n"
+"This program provides a trivial solution, by outsourcing the mslookup main loop\n"
+"to a separate process. Communication is done via cmdline arg and stdout pipe or\n"
+"a (blocking) unix domain socket, results are returned in CSV or JSON format.\n"
+"\n"
+"This can be done one-shot, i.e. exit as soon as the response has been\n"
+"determined, or in daemon form, i.e. continuously listen for requests and return\n"
+"responses.\n"
+"\n"
+"About running a local daemon: it is unintuitive to connect to a socket to solve\n"
+"a problem of reading from a socket -- it seems like just more of the same\n"
+"problem. The reasons why the daemon is in fact useful are:\n"
+"- The osmo-mslookup-client daemon will return only those results matching\n"
+"  requests issued on that socket connection.\n"
+"- A program can simply blockingly recv() from the osmo-mslookup-client socket\n"
+"  instead of needing to run osmo_select_main() so that libosmo-mslookup is able\n"
+"  to asynchronously receive responses from remote servers.\n"
+"- Only one long-lived multicast socket needs to be opened instead of a new\n"
+"  socket for each request.\n"
+"\n"
+"Output is in CSV or json, see --format. The default is tab-separated CSV\n"
+"with these columns:\n"
+CSV_HEADERS "\n"
+"\n"
+"One-shot operation example:\n"
+"$ osmo-mslookup-client 1000-@sip.voice.12345.msisdn -f json\n"
+"{\"query\": \"sip.voice.12345.msisdn\", \"result\": \"result\", \"last\": true, \"age\": 5, \"v4\": [\"1.2.3.7\", \"23\"]}\n"
+"$\n"
+"\n"
+"Daemon operation example:\n"
+"$ osmo-mslookup-client -s /tmp/mslookup -d\n"
+"(and a client program then connects to /tmp/mslookup, find an implementation\n"
+"example below)\n"
+"\n"
+"Integrating with calling programs can be done by:\n"
+"- call osmo-mslookup-client with the query string as argument.\n"
+"  It will open a multicast DNS socket, send out a query and wait for the\n"
+"  matching response. It will print the result on stdout and exit.\n"
+"  This method launches a new process for every mslookup query,\n"
+"  and creates a short-lived multicast listener for each invocation.\n"
+"  This is fine for low activity, but does not scale well.\n"
+"\n"
+"- invoke osmo-mslookup-client --socket /tmp/mslookup -d.\n"
+"  Individual queries can be sent by connecting to that unix domain socket,\n"
+"  blockingly reading the response when it arrives and disconnecting.\n"
+"  This way only one process keeps one multicast listener open.\n"
+"  Callers can connect to this socket without spawning processes.\n"
+"  This is recommended for scale.\n"
+"\n"
+"Python example clients for {CSV,JSON}x{cmdline,socket} can be found here:\n"
+"http://git.osmocom.org/osmo-hlr/tree/contrib/dgsm/osmo-mslookup-pipe.py\n"
+"http://git.osmocom.org/osmo-hlr/tree/contrib/dgsm/osmo-mslookup-socket.py\n"
+"\n"
+"\n"
+"Options:\n"
+"\n"
+"[[delay-][timeout]@]service.number.id\n"
+"	A service query string with optional individual timeout.\n"
+"	The same format is also used on a daemon socket, if any.\n"
+"	The timeout consists of the min-delay and the timeout numbers,\n"
+"	corresponding to the --min-delay and --timeout options, in milliseconds.\n"
+"	These options apply if a query string lacks own numbers.\n"
+"	Examples:\n"
+"		gsup.hlr.1234567.imsi		Use cmdline timeout settings\n"
+"		5000@gsup.hlr.1234567.imsi	Return N results for 5 seconds\n"
+"		1000-5000@sip.voice.123.msisdn	Same, but silent for first second\n"
+"		10000-@smpp.sms.567.msisdn	Return 1 result after 10 seconds\n"
+"\n"
+"--format -f csv (default)\n"
+"	Format result lines in CSV format.\n"
+"--no-csv-headers -H\n"
+"	If the format is 'csv', by default, the first output line prints the\n"
+"	CSV headers used for CSV output format. This option disables these CSV\n"
+"	headers.\n"
+"\n"
+"--format -f json\n"
+"	Format result lines in json instead of semicolon separated, like:\n"
+"	{\"query\": \"sip.voice.12345.msisdn\", \"result\": \"ok\", \"v4\": [\"10.9.8.7\", \"5060\"]}\n"
+"\n"
+"--daemon -d\n"
+"	Keep running after a request has been serviced\n"
+"\n"
+"--mdns-ip -m " OSMO_MSLOOKUP_MDNS_IP4 " -m " OSMO_MSLOOKUP_MDNS_IP6 "\n"
+"--mdns-port -M " OSMO_STRINGIFY_VAL(OSMO_MSLOOKUP_MDNS_PORT) "\n"
+"	Set multicast IP address / port to send mDNS requests and listen for\n"
+"	mDNS reponses\n"
+"--mdns-domain-suffix -D " OSMO_MDNS_DOMAIN_SUFFIX_DEFAULT "\n"
+"	Append this suffix to each mDNS query's domain to avoid colliding with the\n"
+"	top-level domains administrated by IANA.\n"
+"\n"
+"--min-delay -t 1000 (in milliseconds)\n"
+"	Set minimum delay to wait before returning any results.\n"
+"	When this timeout has elapsed, the best current result is returned,\n"
+"	if any is available.\n"
+"	Responses arriving after the min-delay has elapsed which have a younger\n"
+"	age than previous results are returned immediately.\n"
+"	Note: When a response with age of zero comes in, the result is returned\n"
+"	immediately and the request is discarded: non-daemon mode exits, daemon\n"
+"	mode ignores later results.\n"
+"\n"
+"--timeout -T 1000 (in milliseconds)\n"
+"	Set timeout after which to stop listening for responses.\n"
+"	If this is smaller than -t, the value from -t will be used for -T as well.\n"
+"	Note: When a response with age of zero comes in, the result is returned\n"
+"	immediately and the request is discarded: non-daemon mode exits, daemon\n"
+"	mode ignores later results.\n"
+"\n"
+"--socket -s /path/to/unix-domain-socket\n"
+"	Listen to requests from and write responses to a UNIX domain socket.\n"
+"\n"
+"--send -S <query> <age> <ip1> <port1> <ip2> <port2>\n"
+"	Do not query, but send an mslookup result. This is useful only for\n"
+"	testing. Examples:\n"
+"	--send foo.123.msisdn 300 23.42.17.11 1234\n"
+"	--send foo.123.msisdn 300 2323:4242:1717:1111::42 1234\n"
+"	--send foo.123.msisdn 300 23.42.17.11 1234 2323:4242:1717:1111::42 1234\n"
+"\n"
+"--quiet -q\n"
+"	Do not print errors to stderr, do not log to stderr.\n"
+"\n"
+"--help -h\n"
+"	This help\n"
+);
+}
+
+enum result_format {
+	FORMAT_CSV = 0,
+	FORMAT_JSON,
+};
+
+static struct {
+	bool daemon;
+	struct osmo_sockaddr_str mdns_addr;
+	uint32_t min_delay;
+	uint32_t timeout;
+	const char *socket_path;
+	const char *format_str;
+	const char *mdns_domain_suffix;
+	bool csv_headers;
+	bool send;
+	bool quiet;
+} cmdline_opts = {
+	.mdns_addr = { .af=AF_INET, .ip=OSMO_MSLOOKUP_MDNS_IP4, .port=OSMO_MSLOOKUP_MDNS_PORT },
+	.min_delay = 1000,
+	.timeout = 1000,
+	.csv_headers = true,
+	.mdns_domain_suffix = OSMO_MDNS_DOMAIN_SUFFIX_DEFAULT,
+};
+
+#define print_error(fmt, args...) do { \
+		if (!cmdline_opts.quiet) \
+			fprintf(stderr, fmt, ##args); \
+	} while (0)
+
+char g_buf[1024];
+
+long long int parse_int(long long int minval, long long int maxval, const char *arg, int *rc)
+{
+	long long int val;
+	char *endptr;
+	if (rc)
+		*rc = -1;
+	if (!arg)
+		return -1;
+	errno = 0;
+	val = strtoll(arg, &endptr, 10);
+	if (errno || val < minval || val > maxval || *endptr)
+		return -1;
+	if (rc)
+		*rc = 0;
+	return val;
+}
+
+int cb_doing_nothing(struct osmo_fd *fd, unsigned int what)
+{
+	return 0;
+}
+
+/* --send: Just send a response, for manual testing. */
+int do_send(int argc, char ** argv)
+{
+	/* parse args <query> <age> <v4-ip> <v4-port> <v6-ip> <v6-port> */
+#define ARG(NR) ((argc > NR)? argv[NR] : NULL)
+	const char *query_str = ARG(0);
+	const char *age_str = ARG(1);
+	const char *ip_strs[2][2] = {
+		{ ARG(2), ARG(3) },
+		{ ARG(4), ARG(5) },
+	};
+	struct osmo_mslookup_query q = {};
+	struct osmo_mslookup_result r = { .rc = OSMO_MSLOOKUP_RC_RESULT };
+	int i;
+	int rc;
+	void *ctx = talloc_named_const(NULL, 0, __func__);
+	struct osmo_mdns_sock *sock;
+
+	if (!query_str) {
+		print_error("--send needs a query string like foo.123456.imsi\n");
+		return 1;
+	}
+	if (osmo_mslookup_query_init_from_domain_str(&q, query_str)) {
+		print_error("Invalid query string '%s', need a query string like foo.123456.imsi\n",
+			    query_str);
+		return 1;
+	}
+
+	if (!age_str) {
+		print_error("--send needs an age\n");
+		return 1;
+	}
+	r.age = parse_int(0, UINT32_MAX, age_str, &rc);
+	if (rc) {
+		print_error("invalid age\n");
+		return 1;
+	}
+
+	for (i = 0; i < 2; i++) {
+		struct osmo_sockaddr_str addr;
+		uint16_t port;
+		if (!ip_strs[i][0])
+			continue;
+		port = parse_int(1, 65535, ip_strs[i][1] ? : "2342", &rc);
+		if (rc) {
+			print_error("invalid port: %s\n", ip_strs[i][1] ? : "NULL");
+			return 1;
+		}
+		if (osmo_sockaddr_str_from_str(&addr, ip_strs[i][0], port)) {
+			print_error("invalid IP addr: %s\n", ip_strs[i][0]);
+			return 1;
+		}
+		if (addr.af == AF_INET)
+			r.host_v4 = addr;
+		else
+			r.host_v6 = addr;
+	}
+
+	printf("Sending mDNS to " OSMO_SOCKADDR_STR_FMT ": %s\n", OSMO_SOCKADDR_STR_FMT_ARGS(&cmdline_opts.mdns_addr),
+	       osmo_mslookup_result_name_c(ctx, &q, &r));
+
+	rc = 1;
+	sock = osmo_mdns_sock_init(ctx, cmdline_opts.mdns_addr.ip, cmdline_opts.mdns_addr.port,
+				   cb_doing_nothing, NULL, 0);
+	if (!sock) {
+		print_error("unable to open mDNS socket\n");
+		goto exit_cleanup;
+	}
+
+	struct msgb *msg = osmo_mdns_result_encode(ctx, 0, &q, &r, cmdline_opts.mdns_domain_suffix);
+	if (!msg) {
+		print_error("unable to encode mDNS response\n");
+		goto exit_cleanup_sock;
+	}
+
+	if (osmo_mdns_sock_send(sock, msg)) {
+		print_error("unable to send mDNS message\n");
+		goto exit_cleanup_sock;
+	}
+
+	rc = 0;
+exit_cleanup_sock:
+	osmo_mdns_sock_cleanup(sock);
+exit_cleanup:
+	talloc_free(ctx);
+	return rc;
+}
+
+static struct {
+	void *ctx;
+	unsigned int requests_handled;
+	struct osmo_fd socket_ofd;
+	struct osmo_mslookup_client *mslookup_client;
+	struct llist_head queries;
+	struct llist_head socket_clients;
+	enum result_format format;
+} globals = {
+	.queries = LLIST_HEAD_INIT(globals.queries),
+	.socket_clients = LLIST_HEAD_INIT(globals.socket_clients),
+};
+
+typedef void (*formatter_t)(char *buf, size_t buflen, const char *query_str, const struct osmo_mslookup_result *r);
+
+void formatter_csv(char *buf, size_t buflen, const char *query_str, const struct osmo_mslookup_result *r)
+{
+	struct osmo_strbuf sb = { .buf=buf, .len=buflen };
+	OSMO_STRBUF_PRINTF(sb, "%s", query_str);
+
+	if (!r)
+		OSMO_STRBUF_PRINTF(sb, "\tERROR\t\t\t\t\t\t");
+	else {
+		OSMO_STRBUF_PRINTF(sb, "\t%s", osmo_mslookup_result_code_name(r->rc));
+		OSMO_STRBUF_PRINTF(sb, "\t%s", r->last ? "last" : "not-last");
+		OSMO_STRBUF_PRINTF(sb, "\t%u", r->age);
+		switch (r->rc) {
+		case OSMO_MSLOOKUP_RC_RESULT:
+			if (osmo_sockaddr_str_is_nonzero(&r->host_v4))
+				OSMO_STRBUF_PRINTF(sb, "\t%s\t%u", r->host_v4.ip, r->host_v4.port);
+			else
+				OSMO_STRBUF_PRINTF(sb, "\t\t");
+			if (osmo_sockaddr_str_is_nonzero(&r->host_v6))
+				OSMO_STRBUF_PRINTF(sb, "\t%s\t%u", r->host_v6.ip, r->host_v6.port);
+			else
+				OSMO_STRBUF_PRINTF(sb, "\t\t");
+			break;
+		default:
+			OSMO_STRBUF_PRINTF(sb, "\t\t\t\t\t");
+			break;
+		}
+	}
+}
+
+void formatter_json(char *buf, size_t buflen, const char *query_str, const struct osmo_mslookup_result *r)
+{
+	struct osmo_strbuf sb = { .buf=buf, .len=buflen };
+	OSMO_STRBUF_PRINTF(sb, "{\"query\": \"%s\"", query_str);
+
+	if (!r)
+		OSMO_STRBUF_PRINTF(sb, ", \"result\": \"ERROR\"");
+	else {
+		OSMO_STRBUF_PRINTF(sb, ", \"result\": \"%s\"", osmo_mslookup_result_code_name(r->rc));
+		OSMO_STRBUF_PRINTF(sb, ", \"last\": %s", r->last ? "true" : "false");
+		OSMO_STRBUF_PRINTF(sb, ", \"age\": %u", r->age);
+		if (r->rc == OSMO_MSLOOKUP_RC_RESULT) {
+			if (osmo_sockaddr_str_is_nonzero(&r->host_v4))
+				OSMO_STRBUF_PRINTF(sb, ", \"v4\": [\"%s\", \"%u\"]", r->host_v4.ip, r->host_v4.port);
+			if (osmo_sockaddr_str_is_nonzero(&r->host_v6))
+				OSMO_STRBUF_PRINTF(sb, ", \"v6\": [\"%s\", \"%u\"]", r->host_v6.ip, r->host_v6.port);
+		}
+	}
+	OSMO_STRBUF_PRINTF(sb, "}");
+}
+
+formatter_t formatters[] = {
+	[FORMAT_CSV] = formatter_csv,
+	[FORMAT_JSON] = formatter_json,
+};
+
+void respond_str_stdout(const char *str) {
+	fprintf(stdout, "%s\n", str);
+	fflush(stdout);
+}
+
+void start_query_str(const char *query_str);
+void start_query_strs(char **query_strs, size_t query_strs_len);
+
+struct socket_client {
+	struct llist_head entry;
+	struct osmo_fd ofd;
+	char query_str[1024];
+};
+
+static void socket_client_close(struct socket_client *c)
+{
+	struct osmo_fd *ofd = &c->ofd;
+
+	close(ofd->fd);
+	ofd->fd = -1;
+	osmo_fd_unregister(ofd);
+
+	llist_del(&c->entry);
+	talloc_free(c);
+}
+
+void socket_client_respond_result(struct socket_client *c, const char *response)
+{
+	write(c->ofd.fd, response, strlen(response));
+}
+
+static int socket_read_cb(struct osmo_fd *ofd)
+{
+	struct socket_client *c = ofd->data;
+	int rc;
+	char rxbuf[1024];
+	char *query_with_timeout;
+	char *query_str;
+	char *at;
+
+	rc = recv(ofd->fd, rxbuf, sizeof(rxbuf), 0);
+	if (rc == 0)
+		goto close;
+
+	if (rc < 0) {
+		if (errno == EAGAIN)
+			return 0;
+		goto close;
+	}
+
+	if (rc >= sizeof(c->query_str))
+		goto close;
+
+	rxbuf[rc] = '\0';
+	query_with_timeout = strtok(rxbuf, "\r\n");
+	if (!query_with_timeout) {
+		print_error("ERROR: failed to read line from socket\n");
+		goto close;
+	}
+
+	at = strchr(query_with_timeout, '@');
+	query_str = at ? at + 1 : query_with_timeout;
+
+	if (c->query_str[0]) {
+		print_error("ERROR: Only one query per client connect is allowed;"
+			    " received '%s' and '%s' on the same connection\n",
+			    c->query_str, query_str);
+		formatters[globals.format](g_buf, sizeof(g_buf), query_str, NULL);
+		socket_client_respond_result(c, g_buf);
+		return 0;
+	}
+
+	OSMO_STRLCPY_ARRAY(c->query_str, query_str);
+	start_query_str(query_with_timeout);
+	printf("query: %s\n", query_with_timeout);
+	return rc;
+
+close:
+	socket_client_close(c);
+	return -1;
+}
+
+static int socket_cb(struct osmo_fd *ofd, unsigned int flags)
+{
+	int rc = 0;
+
+	if (flags & BSC_FD_READ)
+		rc = socket_read_cb(ofd);
+	if (rc < 0)
+		return rc;
+
+	return rc;
+}
+
+int socket_accept(struct osmo_fd *ofd, unsigned int flags)
+{
+	struct socket_client *c;
+	struct sockaddr_un un_addr;
+	socklen_t len;
+	int rc;
+
+	len = sizeof(un_addr);
+	rc = accept(ofd->fd, (struct sockaddr*)&un_addr, &len);
+	if (rc < 0) {
+		print_error("Failed to accept a new connection\n");
+		return -1;
+	}
+
+	c = talloc_zero(globals.ctx, struct socket_client);
+	OSMO_ASSERT(c);
+	c->ofd.fd = rc;
+	c->ofd.when = BSC_FD_READ;
+	c->ofd.cb = socket_cb;
+	c->ofd.data = c;
+
+	if (osmo_fd_register(&c->ofd) != 0) {
+		print_error("Failed to register new connection fd\n");
+		close(c->ofd.fd);
+		c->ofd.fd = -1;
+		talloc_free(c);
+		return -1;
+	}
+
+	llist_add(&c->entry, &globals.socket_clients);
+
+	if (globals.format == FORMAT_CSV && cmdline_opts.csv_headers)
+		write(c->ofd.fd, CSV_HEADERS, strlen(CSV_HEADERS));
+
+	return 0;
+}
+
+int socket_init(const char *sock_path)
+{
+	struct osmo_fd *ofd = &globals.socket_ofd;
+	int rc;
+
+	ofd->fd = osmo_sock_unix_init(SOCK_SEQPACKET, 0, sock_path, OSMO_SOCK_F_BIND);
+	if (ofd->fd < 0) {
+		print_error("Could not create unix socket: %s: %s\n", sock_path, strerror(errno));
+		return -1;
+	}
+
+	ofd->when = BSC_FD_READ;
+	ofd->cb = socket_accept;
+
+	rc = osmo_fd_register(ofd);
+	if (rc < 0) {
+		print_error("Could not register listen fd: %d\n", rc);
+		close(ofd->fd);
+		return rc;
+	}
+	return 0;
+}
+
+void socket_close()
+{
+	struct socket_client *c, *n;
+	llist_for_each_entry_safe(c, n, &globals.socket_clients, entry)
+		socket_client_close(c);
+	if (osmo_fd_is_registered(&globals.socket_ofd)) {
+		close(globals.socket_ofd.fd);
+		globals.socket_ofd.fd = -1;
+		osmo_fd_unregister(&globals.socket_ofd);
+	}
+}
+
+struct query {
+	struct llist_head entry;
+
+	char query_str[128];
+	struct osmo_mslookup_query query;
+	uint32_t handle;
+};
+
+void respond_result(const char *query_str, const struct osmo_mslookup_result *r)
+{
+	struct socket_client *c, *n;
+	formatters[globals.format](g_buf, sizeof(g_buf), query_str, r);
+	respond_str_stdout(g_buf);
+
+	llist_for_each_entry_safe(c, n, &globals.socket_clients, entry) {
+		if (!strcmp(query_str, c->query_str)) {
+			socket_client_respond_result(c, g_buf);
+			if (r->last)
+				socket_client_close(c);
+		}
+	}
+	if (r->last)
+		globals.requests_handled++;
+}
+
+void respond_err(const char *query_str)
+{
+	respond_result(query_str, NULL);
+}
+
+struct query *query_by_handle(uint32_t request_handle)
+{
+	struct query *q;
+	llist_for_each_entry(q, &globals.queries, entry) {
+		if (request_handle == q->handle)
+			return q;
+	}
+	return NULL;
+}
+
+void mslookup_result_cb(struct osmo_mslookup_client *client,
+			uint32_t request_handle,
+			const struct osmo_mslookup_query *query,
+			const struct osmo_mslookup_result *result)
+{
+	struct query *q = query_by_handle(request_handle);
+	if (!q)
+		return;
+	respond_result(q->query_str, result);
+	if (result->last) {
+		llist_del(&q->entry);
+		talloc_free(q);
+	}
+}
+
+void start_query_str(const char *query_str)
+{
+	struct query *q;
+	const char *domain_str = query_str;
+	char *at;
+	struct osmo_mslookup_query_handling h = {
+		.min_wait_milliseconds = cmdline_opts.min_delay,
+		.result_timeout_milliseconds = cmdline_opts.timeout,
+		.result_cb = mslookup_result_cb,
+	};
+
+	at = strchr(query_str, '@');
+	if (at) {
+		int rc;
+		char timeouts[16];
+		char *dash;
+		char *timeout;
+
+		domain_str = at + 1;
+
+		h.min_wait_milliseconds = h.result_timeout_milliseconds = 0;
+
+		if (osmo_print_n(timeouts, sizeof(timeouts), query_str, at - query_str) >= sizeof(timeouts)) {
+			print_error("ERROR: timeouts part too long in query string\n");
+			respond_err(domain_str);
+			return;
+		}
+
+		dash = strchr(timeouts, '-');
+		if (dash) {
+			char min_delay[16];
+			osmo_print_n(min_delay, sizeof(min_delay), timeouts, dash - timeouts);
+			h.min_wait_milliseconds = parse_int(0, UINT32_MAX, min_delay, &rc);
+			if (rc) {
+				print_error("ERROR: invalid min-delay number: %s\n", min_delay);
+				respond_err(domain_str);
+				return;
+			}
+			timeout = dash + 1;
+		} else {
+			timeout = timeouts;
+		}
+		if (*timeout) {
+			h.result_timeout_milliseconds = parse_int(0, UINT32_MAX, timeout, &rc);
+			if (rc) {
+				print_error("ERROR: invalid timeout number: %s\n", timeout);
+				respond_err(domain_str);
+				return;
+			}
+		}
+	}
+
+	if (strlen(domain_str) >= sizeof(q->query_str)) {
+		print_error("ERROR: query string is too long: '%s'\n", domain_str);
+		respond_err(domain_str);
+		return;
+	}
+
+	q = talloc_zero(globals.ctx, struct query);
+	OSMO_ASSERT(q);
+	OSMO_STRLCPY_ARRAY(q->query_str, domain_str);
+
+	if (osmo_mslookup_query_init_from_domain_str(&q->query, q->query_str)) {
+		print_error("ERROR: cannot parse query string: '%s'\n", domain_str);
+		respond_err(domain_str);
+		talloc_free(q);
+		return;
+	}
+
+	q->handle = osmo_mslookup_client_request(globals.mslookup_client, &q->query, &h);
+	if (!q->handle) {
+		print_error("ERROR: cannot send query: '%s'\n", domain_str);
+		respond_err(domain_str);
+		talloc_free(q);
+		return;
+	}
+
+	llist_add(&q->entry, &globals.queries);
+}
+
+void start_query_strs(char **query_strs, size_t query_strs_len)
+{
+	int i;
+	for (i = 0; i < query_strs_len; i++)
+		start_query_str(query_strs[i]);
+}
+
+int main(int argc, char **argv)
+{
+	int rc = EXIT_FAILURE;
+	globals.ctx = talloc_named_const(NULL, 0, "osmo-mslookup-client");
+
+	osmo_init_logging2(globals.ctx, NULL);
+	log_set_print_filename2(osmo_stderr_target, LOG_FILENAME_BASENAME);
+	log_set_print_filename_pos(osmo_stderr_target, LOG_FILENAME_POS_LINE_END);
+	log_set_print_level(osmo_stderr_target, 1);
+	log_set_print_category(osmo_stderr_target, 1);
+	log_set_print_category_hex(osmo_stderr_target, 0);
+	log_set_print_extended_timestamp(osmo_stderr_target, 1);
+	log_set_use_color(osmo_stderr_target, 0);
+
+	while (1) {
+		int c;
+		long long int val;
+		char *endptr;
+		int option_index = 0;
+
+		static struct option long_options[] = {
+			{ "format", 1, 0, 'f' },
+			{ "no-csv-headers", 0, 0, 'H' },
+			{ "daemon", 0, 0, 'd' },
+			{ "mdns-ip", 1, 0, 'm' },
+			{ "mdns-port", 1, 0, 'M' },
+			{ "mdns-domain-suffix", 1, 0, 'D' },
+			{ "timeout", 1, 0, 'T' },
+			{ "min-delay", 1, 0, 't' },
+			{ "socket", 1, 0, 's' },
+			{ "send", 0, 0, 'S' },
+			{ "quiet", 0, 0, 'q' },
+			{ "help", 0, 0, 'h' },
+			{ "version", 0, 0, 'V' },
+			{}
+		};
+
+#define PARSE_INT(TARGET, MINVAL, MAXVAL) do { \
+		int _rc; \
+		TARGET = parse_int(MINVAL, MAXVAL, optarg, &_rc); \
+		if (_rc) { \
+			print_error("Invalid " #TARGET ": %s\n", optarg); \
+			goto program_exit; \
+		} \
+	} while (0)
+
+		c = getopt_long(argc, argv, "f:Hdm:M:D:t:T:s:SqhV", long_options, &option_index);
+
+		if (c == -1)
+			break;
+
+		switch (c) {
+		case 'f':
+			cmdline_opts.format_str = optarg;
+			break;
+		case 'H':
+			cmdline_opts.csv_headers = false;
+			break;
+		case 'd':
+			cmdline_opts.daemon = true;
+			break;
+		case 'm':
+			if (osmo_sockaddr_str_from_str(&cmdline_opts.mdns_addr, optarg, cmdline_opts.mdns_addr.port)
+			    || !osmo_sockaddr_str_is_nonzero(&cmdline_opts.mdns_addr)) {
+				print_error("Invalid mDNS IP address: %s\n", optarg);
+				goto program_exit;
+			}
+			break;
+		case 'M':
+			PARSE_INT(cmdline_opts.mdns_addr.port, 1, 65535);
+			break;
+		case 'D':
+			cmdline_opts.mdns_domain_suffix = optarg;
+			break;
+		case 't':
+			PARSE_INT(cmdline_opts.min_delay, 0, UINT32_MAX);
+			break;
+		case 'T':
+			PARSE_INT(cmdline_opts.timeout, 0, UINT32_MAX);
+			break;
+		case 's':
+			cmdline_opts.socket_path = optarg;
+			break;
+		case 'S':
+			cmdline_opts.send = true;
+			break;
+		case 'q':
+			cmdline_opts.quiet = true;
+			break;
+
+		case 'h':
+			print_help();
+			rc = 0;
+			goto program_exit;
+		case 'V':
+			print_version();
+			rc = 0;
+			goto program_exit;
+
+		default:
+			/* catch unknown options *as well as* missing arguments. */
+			print_error("Error in command line options. Exiting.\n");
+			goto program_exit;
+		}
+	}
+
+	if (cmdline_opts.send) {
+		if (cmdline_opts.daemon || cmdline_opts.format_str || cmdline_opts.socket_path) {
+			print_error("--send option cannot have any listening related args.");
+		}
+		rc = do_send(argc - optind, argv + optind);
+		goto program_exit;
+	}
+
+	if (!cmdline_opts.daemon && !(argc - optind)) {
+		print_help();
+		goto program_exit;
+	}
+
+	if (cmdline_opts.daemon && !cmdline_opts.timeout) {
+		print_error("In daemon mode, --timeout must not be zero.\n");
+		goto program_exit;
+	}
+
+	if (cmdline_opts.quiet)
+		log_target_destroy(osmo_stderr_target);
+
+	if (cmdline_opts.format_str) {
+		if (osmo_str_startswith("json", cmdline_opts.format_str))
+			globals.format = FORMAT_JSON;
+		else if (osmo_str_startswith("csv", cmdline_opts.format_str))
+			globals.format = FORMAT_CSV;
+		else {
+			print_error("Invalid format: %s\n", cmdline_opts.format_str);
+			goto program_exit;
+		}
+	}
+
+	if (globals.format == FORMAT_CSV && cmdline_opts.csv_headers)
+		respond_str_stdout(CSV_HEADERS);
+
+	globals.mslookup_client = osmo_mslookup_client_new(globals.ctx);
+	if (!globals.mslookup_client
+	    || !osmo_mslookup_client_add_mdns(globals.mslookup_client,
+					      cmdline_opts.mdns_addr.ip, cmdline_opts.mdns_addr.port,
+					      -1, cmdline_opts.mdns_domain_suffix)) {
+		print_error("Failed to start mDNS client\n");
+		goto program_exit;
+	}
+
+	if (cmdline_opts.socket_path) {
+		if (socket_init(cmdline_opts.socket_path))
+			goto program_exit;
+	}
+
+	start_query_strs(&argv[optind], argc - optind);
+
+	while (1) {
+		osmo_select_main_ctx(0);
+
+		if (!cmdline_opts.daemon
+		    && globals.requests_handled
+		    && llist_empty(&globals.queries))
+			break;
+	}
+
+	rc = 0;
+program_exit:
+	osmo_mslookup_client_free(globals.mslookup_client);
+	socket_close();
+	log_fini();
+	talloc_free(globals.ctx);
+	return rc;
+}

src/mslookup_server.c

@@ -0,0 +1,459 @@
+/* Copyright 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <string.h>
+#include <errno.h>
+#include <osmocom/core/sockaddr_str.h>
+#include <osmocom/gsm/gsup.h>
+#include <osmocom/mslookup/mslookup.h>
+#include <osmocom/hlr/logging.h>
+#include <osmocom/hlr/hlr.h>
+#include <osmocom/hlr/db.h>
+#include <osmocom/hlr/timestamp.h>
+#include <osmocom/hlr/mslookup_server.h>
+#include <osmocom/hlr/proxy.h>
+
+static const struct osmo_mslookup_result not_found = {
+		.rc = OSMO_MSLOOKUP_RC_NOT_FOUND,
+	};
+const struct osmo_ipa_name mslookup_server_msc_wildcard = {};
+
+static void set_result(struct osmo_mslookup_result *result,
+		       const struct mslookup_service_host *service_host,
+		       uint32_t age)
+{
+	if (!osmo_sockaddr_str_is_nonzero(&service_host->host_v4)
+	    && !osmo_sockaddr_str_is_nonzero(&service_host->host_v6)) {
+		*result = not_found;
+		return;
+	}
+	result->rc = OSMO_MSLOOKUP_RC_RESULT;
+	result->host_v4 = service_host->host_v4;
+	result->host_v6 = service_host->host_v6;
+	result->age = age;
+}
+
+const struct mslookup_service_host *mslookup_server_get_local_gsup_addr()
+{
+	static struct mslookup_service_host gsup_bind = {};
+	struct mslookup_service_host *host;
+
+	/* Find a HLR/GSUP service set for the server (no VLR unit name) */
+	host = mslookup_server_service_get(&mslookup_server_msc_wildcard, OSMO_MSLOOKUP_SERVICE_HLR_GSUP);
+	if (host)
+		return host;
+
+	/* Try to use the locally configured GSUP bind address */
+	osmo_sockaddr_str_from_str(&gsup_bind.host_v4, g_hlr->gsup_bind_addr, OSMO_GSUP_PORT);
+	if (gsup_bind.host_v4.af == AF_INET6) {
+		gsup_bind.host_v6 = gsup_bind.host_v4;
+		gsup_bind.host_v4 = (struct osmo_sockaddr_str){};
+	}
+	return &gsup_bind;
+}
+
+struct mslookup_server_msc_cfg *mslookup_server_msc_get(const struct osmo_ipa_name *msc_name, bool create)
+{
+	struct llist_head *c = &g_hlr->mslookup.server.local_site_services;
+	struct mslookup_server_msc_cfg *msc;
+
+	if (!msc_name)
+		return NULL;
+
+	llist_for_each_entry(msc, c, entry) {
+		if (osmo_ipa_name_cmp(&msc->name, msc_name))
+			continue;
+		return msc;
+	}
+	if (!create)
+		return NULL;
+
+	msc = talloc_zero(g_hlr, struct mslookup_server_msc_cfg);
+	OSMO_ASSERT(msc);
+	INIT_LLIST_HEAD(&msc->service_hosts);
+	msc->name = *msc_name;
+	llist_add_tail(&msc->entry, c);
+	return msc;
+}
+
+struct mslookup_service_host *mslookup_server_msc_service_get(struct mslookup_server_msc_cfg *msc, const char *service,
+							      bool create)
+{
+	struct mslookup_service_host *e;
+	if (!msc)
+		return NULL;
+
+	llist_for_each_entry(e, &msc->service_hosts, entry) {
+		if (!strcmp(e->service, service))
+			return e;
+	}
+
+	if (!create)
+		return NULL;
+
+	e = talloc_zero(msc, struct mslookup_service_host);
+	OSMO_ASSERT(e);
+	OSMO_STRLCPY_ARRAY(e->service, service);
+	llist_add_tail(&e->entry, &msc->service_hosts);
+	return e;
+}
+
+struct mslookup_service_host *mslookup_server_service_get(const struct osmo_ipa_name *msc_name, const char *service)
+{
+	struct mslookup_server_msc_cfg *msc = mslookup_server_msc_get(msc_name, false);
+	if (!msc)
+		return NULL;
+	return mslookup_server_msc_service_get(msc, service, false);
+}
+
+int mslookup_server_msc_service_set(struct mslookup_server_msc_cfg *msc, const char *service,
+				    const struct osmo_sockaddr_str *addr)
+{
+	struct mslookup_service_host *e;
+
+	if (!service || !service[0]
+	    || strlen(service) > OSMO_MSLOOKUP_SERVICE_MAXLEN)
+		return -EINVAL;
+	if (!addr || !osmo_sockaddr_str_is_nonzero(addr))
+		return -EINVAL;
+
+	e = mslookup_server_msc_service_get(msc, service, true);
+	if (!e)
+		return -EINVAL;
+
+	switch (addr->af) {
+	case AF_INET:
+		e->host_v4 = *addr;
+		break;
+	case AF_INET6:
+		e->host_v6 = *addr;
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+int mslookup_server_msc_service_del(struct mslookup_server_msc_cfg *msc, const char *service,
+				    const struct osmo_sockaddr_str *addr)
+{
+	struct mslookup_service_host *e, *n;
+	int deleted = 0;
+
+	if (!msc)
+		return -ENOENT;
+
+	llist_for_each_entry_safe(e, n, &msc->service_hosts, entry) {
+		if (service && strcmp(service, e->service))
+			continue;
+
+		if (addr) {
+			if (!osmo_sockaddr_str_cmp(addr, &e->host_v4)) {
+				e->host_v4 = (struct osmo_sockaddr_str){};
+				/* Removed one addr. If the other is still there, keep the entry. */
+				if (osmo_sockaddr_str_is_nonzero(&e->host_v6))
+					continue;
+			} else if (!osmo_sockaddr_str_cmp(addr, &e->host_v6)) {
+				e->host_v6 = (struct osmo_sockaddr_str){};
+				/* Removed one addr. If the other is still there, keep the entry. */
+				if (osmo_sockaddr_str_is_nonzero(&e->host_v4))
+					continue;
+			} else
+				/* No addr match, keep the entry. */
+				continue;
+			/* Addr matched and none is left. Delete. */
+		}
+		llist_del(&e->entry);
+		talloc_free(e);
+		deleted++;
+	}
+	return deleted;
+}
+
+/* A remote entity is asking us whether we are the home HLR of the given subscriber. */
+static void mslookup_server_rx_hlr_gsup(const struct osmo_mslookup_query *query,
+					struct osmo_mslookup_result *result)
+{
+	const struct mslookup_service_host *host;
+	int rc;
+	switch (query->id.type) {
+	case OSMO_MSLOOKUP_ID_IMSI:
+		rc = db_subscr_exists_by_imsi(g_hlr->dbc, query->id.imsi);
+		break;
+	case OSMO_MSLOOKUP_ID_MSISDN:
+		rc = db_subscr_exists_by_msisdn(g_hlr->dbc, query->id.msisdn);
+		break;
+	default:
+		LOGP(DMSLOOKUP, LOGL_ERROR, "Unknown mslookup ID type: %d\n", query->id.type);
+		*result = not_found;
+		return;
+	}
+
+	if (rc) {
+		LOGP(DMSLOOKUP, LOGL_DEBUG, "%s: does not exist in local HLR\n",
+		     osmo_mslookup_result_name_c(OTC_SELECT, query, NULL));
+		*result = not_found;
+		return;
+	}
+
+	LOGP(DMSLOOKUP, LOGL_DEBUG, "%s: found in local HLR\n",
+	     osmo_mslookup_result_name_c(OTC_SELECT, query, NULL));
+
+	host = mslookup_server_get_local_gsup_addr();
+
+	set_result(result, host, 0);
+	if (result->rc != OSMO_MSLOOKUP_RC_RESULT) {
+		LOGP(DMSLOOKUP, LOGL_ERROR,
+		     "Subscriber found, but error in service '" OSMO_MSLOOKUP_SERVICE_HLR_GSUP "' config:"
+		     " v4: " OSMO_SOCKADDR_STR_FMT "  v6: " OSMO_SOCKADDR_STR_FMT "\n",
+		     OSMO_SOCKADDR_STR_FMT_ARGS(&host->host_v4),
+		     OSMO_SOCKADDR_STR_FMT_ARGS(&host->host_v6));
+	}
+}
+
+/* Look in the local HLR record: If the subscriber is "at home" in this HLR and is also currently located at a local
+ * VLR, we will find a valid location updating with vlr_number, and no vlr_via_proxy entry. */
+static bool subscriber_has_done_lu_here_hlr(const struct osmo_mslookup_query *query,
+					    uint32_t *lu_age,
+					    struct osmo_ipa_name *local_msc_name,
+					    struct hlr_subscriber *ret_subscr)
+{
+	struct hlr_subscriber _subscr;
+	int rc;
+	uint32_t age;
+
+	struct hlr_subscriber *subscr = ret_subscr ? : &_subscr;
+
+	switch (query->id.type) {
+	case OSMO_MSLOOKUP_ID_IMSI:
+		rc = db_subscr_get_by_imsi(g_hlr->dbc, query->id.imsi, subscr);
+		break;
+	case OSMO_MSLOOKUP_ID_MSISDN:
+		rc = db_subscr_get_by_msisdn(g_hlr->dbc, query->id.msisdn, subscr);
+		break;
+	default:
+		LOGP(DMSLOOKUP, LOGL_ERROR, "Unknown mslookup ID type: %d\n", query->id.type);
+		return false;
+	}
+
+	if (rc) {
+		LOGP(DMSLOOKUP, LOGL_DEBUG, "%s: does not exist in local HLR\n",
+		     osmo_mslookup_result_name_c(OTC_SELECT, query, NULL));
+		return false;
+	}
+
+	if (!subscr->vlr_number[0]) {
+		LOGP(DMSLOOKUP, LOGL_DEBUG, "%s: not attached (vlr_number unset)\n",
+		     osmo_mslookup_result_name_c(OTC_SELECT, query, NULL));
+		return false;
+	}
+
+	if (subscr->vlr_via_proxy.len) {
+		/* The VLR is behind a proxy, the subscriber is not attached to a local VLR but a remote one. That
+		 * remote proxy should instead respond to the service lookup request. */
+		LOGP(DMSLOOKUP, LOGL_DEBUG, "%s: last attach is not at local VLR, but at VLR '%s' via proxy %s\n",
+		     osmo_mslookup_result_name_c(OTC_SELECT, query, NULL),
+		     subscr->vlr_number,
+		     osmo_ipa_name_to_str(&subscr->vlr_via_proxy));
+		return false;
+	}
+
+	if (!timestamp_age(&subscr->last_lu_seen, &age)) {
+		LOGP(DMSLOOKUP, LOGL_DEBUG, "%s: Invalid last_lu_seen timestamp for subscriber\n",
+		     osmo_mslookup_result_name_c(OTC_SELECT, query, NULL));
+		return false;
+	}
+	if (age > g_hlr->mslookup.server.local_attach_max_age) {
+		LOGP(DMSLOOKUP, LOGL_DEBUG, "%s: last attach was here, but too long ago: %us > %us\n",
+		     osmo_mslookup_result_name_c(OTC_SELECT, query, NULL),
+		     age, g_hlr->mslookup.server.local_attach_max_age);
+		return false;
+	}
+
+	*lu_age = age;
+	osmo_ipa_name_set_str(local_msc_name, subscr->vlr_number);
+	LOGP(DMSLOOKUP, LOGL_DEBUG, "%s: attached %u seconds ago at local VLR %s\n",
+	     osmo_mslookup_result_name_c(OTC_SELECT, query, NULL),
+	     age, osmo_ipa_name_to_str(local_msc_name));
+
+	return true;
+}
+
+
+/* Determine whether the subscriber with the given ID has routed a Location Updating via this HLR as first hop. Return
+ * true if it is attached at a local VLR, and we are serving as proxy for a remote home HLR.
+ */
+static bool subscriber_has_done_lu_here_proxy(const struct osmo_mslookup_query *query,
+					      uint32_t *lu_age,
+					      struct osmo_ipa_name *local_msc_name,
+					      struct proxy_subscr *ret_proxy_subscr)
+{
+	struct proxy_subscr proxy_subscr;
+	uint32_t age;
+	int rc;
+
+	/* See the local HLR record. If the subscriber is "at home" in this HLR and is also currently located here, we
+	 * will find a valid location updating and no vlr_via_proxy entry. */
+	switch (query->id.type) {
+	case OSMO_MSLOOKUP_ID_IMSI:
+		rc = proxy_subscr_get_by_imsi(&proxy_subscr, g_hlr->gs->proxy, query->id.imsi);
+		break;
+	case OSMO_MSLOOKUP_ID_MSISDN:
+		rc = proxy_subscr_get_by_msisdn(&proxy_subscr, g_hlr->gs->proxy, query->id.msisdn);
+		break;
+	default:
+		LOGP(DDGSM, LOGL_ERROR, "%s: unknown ID type\n",
+		     osmo_mslookup_result_name_c(OTC_SELECT, query, NULL));
+		return false;
+	}
+
+	if (rc) {
+		LOGP(DDGSM, LOGL_DEBUG, "%s: does not exist in GSUP proxy\n",
+		     osmo_mslookup_result_name_c(OTC_SELECT, query, NULL));
+		return false;
+	}
+
+	/* We only need to care about CS LU, since only CS services need D-GSM routing. */
+	if (!timestamp_age(&proxy_subscr.cs.last_lu, &age)
+	    || age > g_hlr->mslookup.server.local_attach_max_age) {
+		LOGP(DDGSM, LOGL_ERROR,
+		     "%s: last attach was at local VLR (proxying for remote HLR), but too long ago: %us > %us\n",
+		     osmo_mslookup_result_name_c(OTC_SELECT, query, NULL),
+		     age, g_hlr->mslookup.server.local_attach_max_age);
+		return false;
+	}
+
+	if (proxy_subscr.cs.vlr_via_proxy.len) {
+		LOGP(DDGSM, LOGL_DEBUG, "%s: last attach is not at local VLR, but at VLR '%s' via proxy '%s'\n",
+		     osmo_mslookup_result_name_c(OTC_SELECT, query, NULL),
+		     osmo_ipa_name_to_str(&proxy_subscr.cs.vlr_name),
+		     osmo_ipa_name_to_str(&proxy_subscr.cs.vlr_via_proxy));
+		return false;
+	}
+
+	*lu_age = age;
+	*local_msc_name = proxy_subscr.cs.vlr_name;
+	LOGP(DDGSM, LOGL_DEBUG, "%s: attached %u seconds ago at local VLR %s; proxying for remote HLR "
+	     OSMO_SOCKADDR_STR_FMT "\n",
+	     osmo_mslookup_result_name_c(OTC_SELECT, query, NULL),
+	     age, osmo_ipa_name_to_str(local_msc_name),
+	     OSMO_SOCKADDR_STR_FMT_ARGS(&proxy_subscr.remote_hlr_addr));
+
+	if (ret_proxy_subscr)
+		*ret_proxy_subscr = proxy_subscr;
+	return true;
+}
+
+bool subscriber_has_done_lu_here(const struct osmo_mslookup_query *query,
+				 uint32_t *lu_age_p, struct osmo_ipa_name *local_msc_name,
+				 char *ret_imsi, size_t ret_imsi_len)
+{
+	bool attached_here;
+	uint32_t lu_age = 0;
+	struct osmo_ipa_name msc_name = {};
+	bool attached_here_proxy;
+	uint32_t proxy_lu_age = 0;
+	struct osmo_ipa_name proxy_msc_name = {};
+	struct proxy_subscr proxy_subscr;
+	struct hlr_subscriber db_subscr;
+
+
+	/* First ask the local HLR db, but if the local proxy record indicates a more recent LU, use that instead.
+	 * For all usual cases, only one of these will reflect a LU, even if a subscriber had more than one home HLR:
+	 *   - if the subscriber is known here, we will never proxy.
+	 *   - if the subscriber is not known here, this local HLR db will never record a LU.
+	 * However, if a subscriber was being proxied to a remote home HLR, and if then the subscriber was also added to
+	 * the local HLR database, there might occur a situation where both reflect a LU. So, to be safe against all
+	 * situations, compare the two entries.
+	 */
+	attached_here = subscriber_has_done_lu_here_hlr(query, &lu_age, &msc_name, &db_subscr);
+	attached_here_proxy = subscriber_has_done_lu_here_proxy(query, &proxy_lu_age, &proxy_msc_name, &proxy_subscr);
+
+	/* If proxy has a younger lu, replace. */
+	if (attached_here_proxy && (!attached_here || (proxy_lu_age < lu_age))) {
+		attached_here = true;
+		lu_age = proxy_lu_age;
+		msc_name = proxy_msc_name;
+		if (ret_imsi)
+			osmo_strlcpy(ret_imsi, proxy_subscr.imsi, ret_imsi_len);
+	} else if (attached_here) {
+		if (ret_imsi)
+			osmo_strlcpy(ret_imsi, db_subscr.imsi, ret_imsi_len);
+	}
+
+	if (attached_here && !msc_name.len) {
+		LOGP(DMSLOOKUP, LOGL_ERROR, "%s: attached here, but no VLR name known\n",
+		     osmo_mslookup_result_name_c(OTC_SELECT, query, NULL));
+		return false;
+	}
+
+	if (!attached_here) {
+		/* Already logged "not attached" for both local-db and proxy attach */
+		return false;
+	}
+
+	LOGP(DMSLOOKUP, LOGL_INFO, "%s: attached here, at VLR %s\n",
+	     osmo_mslookup_result_name_c(OTC_SELECT, query, NULL),
+	     osmo_ipa_name_to_str(&msc_name));
+	*lu_age_p = lu_age;
+	*local_msc_name = msc_name;
+	return true;
+}
+
+/* A remote entity is asking us whether we are providing the given service for the given subscriber. */
+void mslookup_server_rx(const struct osmo_mslookup_query *query,
+			struct osmo_mslookup_result *result)
+{
+	const struct mslookup_service_host *service_host;
+	uint32_t age;
+	struct osmo_ipa_name msc_name;
+
+	/* A request for a home HLR: answer exactly if this is the subscriber's home HLR, i.e. the IMSI is listed in the
+	 * HLR database. */
+	if (strcmp(query->service, OSMO_MSLOOKUP_SERVICE_HLR_GSUP) == 0)
+		return mslookup_server_rx_hlr_gsup(query, result);
+
+	/* All other service types: answer when the subscriber has done a LU that is either listed in the local HLR or
+	 * in the GSUP proxy database: i.e. if the subscriber has done a Location Updating at an VLR belonging to this
+	 * HLR. Respond with whichever services are configured in the osmo-hlr.cfg. */
+	if (!subscriber_has_done_lu_here(query, &age, &msc_name, NULL, 0)) {
+		*result = not_found;
+		return;
+	}
+
+	/* We've detected a LU here. The VLR where the LU happened is stored in msc_unit_name, and the LU age is stored
+	 * in 'age'. Figure out the address configured for that VLR and service name. */
+	service_host = mslookup_server_service_get(&msc_name, query->service);
+
+	if (!service_host) {
+		/* Find such service set globally (no VLR unit name) */
+		service_host = mslookup_server_service_get(&mslookup_server_msc_wildcard, query->service);
+	}
+
+	if (!service_host) {
+		LOGP(DMSLOOKUP, LOGL_ERROR,
+		     "%s: subscriber found, but no service %s configured, cannot service lookup request\n",
+		     osmo_mslookup_result_name_c(OTC_SELECT, query, NULL),
+		     osmo_quote_str_c(OTC_SELECT, query->service, -1));
+		*result = not_found;
+		return;
+	}
+
+	set_result(result, service_host, age);
+}