Implement reserved IPv4 addresses for IMSIs

Allows maintaining, via the VTY, a list of IMSI -> IPv4
address mappings to ensure the GGSN always assigns
the same IP address to a UE identified by the IMSI.

This is NOT an implenentation of static IP address support,
it simply reserves IPs from the dynamic IP pool. No checks
are done to enure that the address indeed forms part of the
defined pool, this is left up to the operator to configure
correctly.

It may be desired to always have the same IP address assigned
after a PDP context is deleted and recreated by the device,
by toggling mobile data, or airplane mode.
This could be useful, for example, in order to avoid having to
adjust firewall or packet capture filters. One might also have
a small subset of IMSIs on a network that should have a special
set of firewall rules, for access to internal infrastructure or
traffic shaping exemptions, as some examples.

This is intented as a developer or small operator feature, but
it is not the intention here that one would go about assigning
'static' IP addresses to an entire HLR of subscribers via the
GGSN vty.

.gitignore

@@ -82,3 +82,7 @@ doc/manuals/build
 doc/manuals/vty/ggsn_vty_reference.xml
 
 contrib/osmo-ggsn.spec
+/debian/gtp-echo-responder-dbg/
+/debian/gtp-echo-responder/
+/debian/osmo-ggsn-doc/
+/utils/gtp-echo-responder

Makefile.am

@@ -1,5 +1,5 @@
 ## Process this file with automake to produce Makefile.in
-SUBDIRS = lib gtp ggsn sgsnemu doc contrib tests
+SUBDIRS = lib gtp ggsn sgsnemu doc contrib utils tests
 
 pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = libgtp.pc

README.md

@@ -20,9 +20,9 @@ GIT Repository
 
 You can clone from the official osmo-ggsn.git repository using
 
-	git clone git://git.osmocom.org/osmo-ggsn.git
+	git clone https://gitea.osmocom.org/cellular-infrastructure/osmo-ggsn
 
-There is a cgit interface at http://git.osmocom.org/osmo-ggsn/
+There is a web interface at <https://gitea.osmocom.org/cellular-infrastructure/osmo-ggsn>
 
 Documentation
 -------------

TODO-RELEASE

@@ -7,4 +7,3 @@
 # If any interfaces have been added since the last public release: c:r:a + 1.
 # If any interfaces have been removed or changed since the last public release: c:r:0.
 #library	what		description / commit summary line
-libgtp          ADD             gtp_ran_info_relay_req, gtp_set_cb_ran_info_relay_ind

configure.ac

@@ -154,9 +154,9 @@ adl_FUNC_GETOPT_LONG
 
 AM_INIT_AUTOMAKE([foreign])
 
-PKG_CHECK_MODULES(LIBOSMOCORE, libosmocore >= 1.5.0)
-PKG_CHECK_MODULES(LIBOSMOVTY, libosmovty >= 1.5.0)
-PKG_CHECK_MODULES(LIBOSMOCTRL, libosmoctrl >= 1.5.0)
+PKG_CHECK_MODULES(LIBOSMOCORE, libosmocore >= 1.8.0)
+PKG_CHECK_MODULES(LIBOSMOVTY, libosmovty >= 1.8.0)
+PKG_CHECK_MODULES(LIBOSMOCTRL, libosmoctrl >= 1.8.0)
 
 AC_ARG_ENABLE(sanitize,
 	[AS_HELP_STRING(
@@ -257,8 +257,9 @@ AC_CONFIG_FILES([Makefile
                  lib/Makefile
                  intl/Makefile
                  po/Makefile
+                 utils/Makefile
                  sgsnemu/Makefile
-    doc/manuals/Makefile
+                 doc/manuals/Makefile
                  contrib/Makefile
                  contrib/systemd/Makefile
                  contrib/osmo-ggsn.spec

contrib/osmo-ggsn.spec.in

@@ -30,9 +30,9 @@ BuildRequires:  pkgconfig >= 0.20
 BuildRequires:  systemd-rpm-macros
 %endif
 BuildRequires:  pkgconfig(libgtpnl) >= 1.2.0
-BuildRequires:  pkgconfig(libosmocore) >= 1.5.0
-BuildRequires:  pkgconfig(libosmoctrl) >= 1.5.0
-BuildRequires:  pkgconfig(libosmovty) >= 1.5.0
+BuildRequires:  pkgconfig(libosmocore) >= 1.8.0
+BuildRequires:  pkgconfig(libosmoctrl) >= 1.8.0
+BuildRequires:  pkgconfig(libosmovty) >= 1.8.0
 Obsoletes:      openggsn
 %{?systemd_requires}
 
@@ -61,6 +61,15 @@ libgtp implements the GPRS Tunneling Protocol between SGSN and GGSN.
 This subpackage contains libraries and header files for developing
 applications that want to make use of libgtp.
 
+%package -n gtp-echo-responder
+Summary:        Small program answering GTP ECHO Request with GTP ECHO Response
+License:        MIT
+Group:          System/Libraries
+
+%description -n gtp-echo-responder
+Small program answering GTP ECHO Request with GTP ECHO Response for both GTPCv1
+and GTPCv2.
+
 %prep
 %setup -q
 
@@ -122,4 +131,7 @@ make %{?_smp_mflags} check || (find . -name testsuite.log -exec cat {} +)
 %{_libdir}/libgtp.so
 %{_libdir}/pkgconfig/libgtp.pc
 
+%files -n gtp-echo-responder
+%{_bindir}/gtp-echo-responder
+
 %changelog

contrib/systemd/osmo-ggsn.service

@@ -1,10 +1,13 @@
 [Unit]
 Description=OsmoGGSN
-After=networking.service
+After=network-online.target
+Wants=network-online.target
 
 [Service]
 Type=simple
 Restart=always
+StateDirectory=osmocom
+WorkingDirectory=%S/osmocom
 ExecStart=/usr/bin/osmo-ggsn -c /etc/osmocom/osmo-ggsn.cfg
 RestartSec=2
 RestartPreventExitStatus=1

debian/changelog

@@ -1,3 +1,88 @@
+osmo-ggsn (1.10.1) unstable; urgency=medium
+
+  [ Oliver Smith ]
+  * debian/libgtp6.shlibs: new file
+
+  [ Vadim Yanitskiy ]
+  * lib/icmpv6.h: fix struct icmpv6_{radv_hdr,opt_prefix}
+  * gtp/gsn.c: fix 'No newline at end of file'
+  * gtp: use OSMO_ASSERT() in gtp_new()
+
+ -- Vadim Yanitskiy <vyanitskiy@sysmocom.de>  Mon, 27 Feb 2023 22:35:47 +0700
+
+osmo-ggsn (1.10.0) unstable; urgency=medium
+
+  [ Max ]
+  * Set working directory in systemd service file
+  * Ignore .deb build byproducts
+  * ctrl: take both address and port from vty config
+
+  [ Pau Espin Pedrol ]
+  * cosmetic: gtp: Fix typo in comment
+  * Split gsn_t related APIs out of gtp.{c,h}
+  * Use rate_ctr for gsn_t available_counters
+  * ggsn: Introduce tdef and make it configurable over VTY
+  * gtp: Introduce VTY configurable GTP timer X3
+  * Fix typos in comments and VTY descriptions
+
+  [ arehbein ]
+  * osmo-ggsn: Transition to use of 'telnet_init_default'
+
+ -- Pau Espin Pedrol <pespin@sysmocom.de>  Tue, 07 Feb 2023 14:29:48 +0100
+
+osmo-ggsn (1.9.0) unstable; urgency=medium
+
+  [ Pau Espin Pedrol ]
+  * tests: in46a_test: Make coverity happy when calling in46a_from_eua
+  * vty: Fix cmd 'no echo-interval' doing nothing
+  * libgtp: Fix ggsn crash if pdp alloc array is full (PDP_MAX)
+  * libgtp: Define retransmit QUEUE_SIZE relative to PDP_MAX (increase)
+  * gtp: Use switch statement in gtp_create_pdp_ind()
+  * gtp: Log detection of rx duplicate
+  * gtp: Small log improvements in gtp_create_pdp_ind()
+  * gtp: Specify retrans queue name & seqnum in log lines
+  * gtp: Log retrans queue register&free entries
+  * gtp: Fix typo in comment
+  * pco.h: Fix typo in reference to spec
+
+  [ Vadim Yanitskiy ]
+  * tests: use 'check_PROGRAMS' instead of 'noinst_PROGRAMS'
+
+  [ Harald Welte ]
+  * update git URLs (git -> https; gitea)
+
+ -- Pau Espin Pedrol <pespin@sysmocom.de>  Tue, 28 Jun 2022 17:48:22 +0200
+
+osmo-ggsn (1.8.0) unstable; urgency=medium
+
+  [ Oliver Smith ]
+  * doc/examples/Makefile.am: add sgsnemu.conf
+  * doc/examples/osmo-ggsn-kernel-gtp.cfg: new file
+  * doc/manuals: describe GTP-U kernel module
+  * gitignore: add ggsn_vty_reference.xml
+
+  [ Harald Welte ]
+  * Don't install osmo-ggsn-kernel-gtp.cfg to /etc/osmocom/
+  * Don't install sgsnemu.conf to /etc/osmocom/
+  * ggsn: Reject PDP CTX ACT for static IP addresses
+  * vty: Inform user that static IP addresses are not supported
+
+  [ Pau Espin Pedrol ]
+  * gtp: Update teic_confirmed only on resp success
+  * gtp: Rework parsing logic of UpdatePdpCtxResponse
+  * ggsn: Improve logging on incoming DL data packets
+  * gtp: Improve logging of failing pdp ctx resolution from TEI/TID
+  * cosmetic: gtpie.c: Fix trailing whitespace
+  * gtp: constify pointer arg
+  * gtp: Support tx/rx RAN Information Relay message
+  * ggsn: Log tun fd write errors
+  * ggsn: Fix heap-use-after-free during Recovery without associated PDP
+  * cosmetic: configure.ac: Fix tabulation in line
+  * Introduce program gtp-echo-responder
+  * gtp_echo_responder: report invalid chars present in node-feautres cmdline arg as error
+
+ -- Pau Espin Pedrol <pespin@sysmocom.de>  Tue, 16 Nov 2021 13:49:16 +0100
+
 osmo-ggsn (1.7.1) unstable; urgency=medium
 
   [ Harald Welte ]

debian/compat

@@ -1 +1 @@
-9
+10

debian/control

@@ -2,17 +2,17 @@ Source: osmo-ggsn
 Maintainer: Osmocom team <openbsc@lists.osmocom.org>
 Section: net
 Priority: optional
-Build-Depends: debhelper (>= 9),
+Build-Depends: debhelper (>= 10),
                autotools-dev,
                pkg-config,
                libdpkg-perl, git,
                dh-autoreconf,
-               libosmocore-dev (>= 1.5.0),
+               libosmocore-dev (>= 1.8.0),
                osmo-gsm-manuals-dev,
                libgtpnl-dev (>= 1.2.0)
 Standards-Version: 3.9.6
-Vcs-Browser: http://git.osmocom.org/osmo-ggsn/
-Vcs-Git: git://git.osmocom.org/osmo-ggsn
+Vcs-Browser: https://gitea.osmocom.org/cellular-infrastructure/osmo-ggsn
+Vcs-Git: https://gitea.osmocom.org/cellular-infrastructure/osmo-ggsn
 Homepage: https://projects.osmocom.org/projects/openggsn
 
 Package: osmo-ggsn
@@ -38,6 +38,12 @@ Description: library implementing the GTP protocol between SGSN and GGSN
  This library is part of OsmoGGSN and implements the GTP protocol between
  SGSN (Serving GPRS support node) and GGSN.
 
+Package: gtp-echo-responder
+Architecture: any
+Depends: ${shlibs:Depends},
+         ${misc:Depends}
+Description: Small program answering GTP ECHO Request with GTP ECHO Response
+
 Package: libgtp-dev
 Architecture: any
 Multi-Arch: same
@@ -63,6 +69,15 @@ Description: Debug symbols for OsmoGGSN
  operators as the interface between the Internet and the rest of the
  mobile network infrastructure.
 
+Package: gtp-echo-responder-dbg
+Section: debug
+Architecture: any
+Priority: extra
+Depends: ${shlibs:Depends}, ${misc:Depends}, gtp-echo-responder (= ${binary:Version})
+Multi-Arch: same
+Description: Debug symbols for gtp-echo-responder
+ Small program answering GTP ECHO Request with GTP ECHO Response.
+
 Package: libgtp-dbg
 Section: debug
 Architecture: any

debian/copyright

@@ -16,6 +16,11 @@ Files: lib/getopt.c
 Copyright: 1987-2001 Free Software Foundation, Inc.
 License: LGPL-2.1+
 
+Files: utils/gtp_echo_responder.c
+       utils/gtp_echo_responder_test.py
+Copyright: 2021 sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+License: MIT
+
 Files: debian/*
 Copyright: 2010-2017  Harald Welte <laforge@gnumonks.org>
            2016       Ruben Undheim <ruben.undheim@gmail.com>

debian/gtp-echo-responder.install

@@ -0,0 +1 @@
+/usr/bin/gtp-echo-responder

debian/libgtp6.shlibs

@@ -0,0 +1,2 @@
+# Most recent version of the package that added new symbols (OS#5318)
+libgtp 6 libgtp6 (>= 1.8.0)

doc/manuals/chapters/configuration.adoc

@@ -302,7 +302,7 @@ Name=apn0 <1>
 Address=192.168.7.1/24 <2>
 IPMasquerade=yes <3>
 ----
-<1> The netowrk device name, which must match the one in the apn0.netdev unit file above
+<1> The network device name, which must match the one in the apn0.netdev unit file above
 <2> The local IP address configured on the device
 <3> Requesting systemd to configure IP masquerading for this interface.  Depending on your needs,
     You may not want this if you have proper end-to-end routing set up, and want to have transparent

ggsn/Makefile.am

@@ -2,7 +2,7 @@ bin_PROGRAMS = osmo-ggsn
 
 AM_LDFLAGS = @EXEC_LDFLAGS@
 
-AM_CFLAGS = -O2 -D_GNU_SOURCE -fno-builtin -Wall -DSBINDIR='"$(sbindir)"' -ggdb $(LIBOSMOCORE_CFLAGS) $(LIBOSMOCTRL_CFLAGS) $(LIBOSMOVTY_CFLAGS)
+AM_CFLAGS = -D_GNU_SOURCE -fno-builtin -Wall -DSBINDIR='"$(sbindir)"' $(LIBOSMOCORE_CFLAGS) $(LIBOSMOCTRL_CFLAGS) $(LIBOSMOVTY_CFLAGS)
 
 osmo_ggsn_LDADD = @EXEC_LDADD@ -lgtp -L../gtp ../lib/libmisc.a $(LIBOSMOCORE_LIBS) $(LIBOSMOCTRL_LIBS) $(LIBOSMOVTY_LIBS)
 

ggsn/ggsn.c

@@ -40,6 +40,7 @@
 #include <arpa/inet.h>
 #include <netinet/in.h>
 #include <netinet/ip.h>
+#include <netinet/ip_icmp.h>
 #include <netinet/ip6.h>
 
 #include <osmocom/core/timer.h>
@@ -327,6 +328,74 @@ int apn_start(struct apn_ctx *apn)
 	return 0;
 }
 
+static struct imsi_map_entry *apn_imsi_map_lookup_by_imsi(const char *imsi, const struct apn_ctx_ip *ctx)
+{
+	struct imsi_map_entry *map;
+	llist_for_each_entry(map, &ctx->imsi_ip_map, list) {
+		if (!strcmp(imsi, map->imsi))
+			return map;
+	}
+	return NULL;
+}
+
+static struct imsi_map_entry *apn_imsi_map_lookup_by_ip(const struct in46_addr *addr, const struct apn_ctx_ip *ctx)
+{
+	struct imsi_map_entry *map;
+	if (!addr)
+		return NULL;
+	llist_for_each_entry(map, &ctx->imsi_ip_map, list) {
+		if (in46a_equal(addr, &map->addr))
+			return map;
+	}
+	return NULL;
+}
+
+int apn_imsi_ip_map_add(const char *imsi, const char *ip, struct apn_ctx_ip *ctx)
+{
+	struct imsi_map_entry *map;
+	struct in46_addr addr = { 0 };
+	size_t t;
+
+	if (ippool_aton(&addr, &t, ip, 0))
+		return -EINVAL;
+	if (apn_imsi_map_lookup_by_imsi(imsi, ctx) || apn_imsi_map_lookup_by_ip(&addr, ctx))
+		return -EEXIST;
+
+	map = talloc_zero(NULL, struct imsi_map_entry);
+	if (!map)
+		return -ENOMEM;
+	if (ippool_aton(&map->addr, &t, ip, 0)) {
+		talloc_free(map);
+		return -EINVAL;
+	}
+
+	osmo_strlcpy(map->imsi, imsi, sizeof(map->imsi));
+	llist_add(&map->list, &ctx->imsi_ip_map);
+
+	return 0;
+}
+
+int apn_imsi_ip_map_del(const char *imsi, const char *ip, struct apn_ctx_ip *ctx)
+{
+	struct imsi_map_entry *map;
+
+	map = apn_imsi_map_lookup_by_imsi(imsi, ctx);
+	if (!map)
+		return -ENODEV;
+
+	llist_del(&map->list);
+	talloc_free(map);
+
+	return 0;
+}
+
+static struct imsi_map_entry *imsi_has_reserved_ip(const char *imsi, struct apn_ctx_ip *ctx)
+{
+	if (llist_empty(&ctx->imsi_ip_map))
+		return NULL;
+	return apn_imsi_map_lookup_by_imsi(imsi, ctx);
+}
+
 static bool send_trap(const struct gsn_t *gsn, const struct pdp_t *pdp, const struct ippoolm_t *member, const char *var)
 {
 	char addrbuf[256];
@@ -384,7 +453,7 @@ static int delete_context(struct pdp_t *pdp)
 	return 0;
 }
 
-static bool apn_supports_ipv4(const struct apn_ctx *apn)
+bool apn_supports_ipv4(const struct apn_ctx *apn)
 {
 	if (apn->v4.cfg.static_prefix.addr.len  || apn->v4.cfg.dynamic_prefix.addr.len)
 		return true;
@@ -441,6 +510,7 @@ int create_context_ind(struct pdp_t *pdp)
 	char *apn_name;
 	struct sgsn_peer *sgsn;
 	struct pdp_priv_t *pdp_priv;
+	struct imsi_map_entry *imsi_map;
 
 	apn_name = osmo_apn_to_str(name_buf, pdp->apn_req.v, pdp->apn_req.l);
 	LOGPPDP(LOGL_DEBUG, pdp, "Processing create PDP context request for APN '%s'\n",
@@ -494,6 +564,17 @@ int create_context_ind(struct pdp_t *pdp)
 		LOGPPDP(LOGL_ERROR, pdp, "Failed to store APN '%s'\n", apn->cfg.name);
 	pdp->apn_use.l = rc;
 
+	/* Check if we have a entry in the reserved IP map for this IMSI */
+	imsi_map = imsi_has_reserved_ip(imsi_gtp2str(&pdp->imsi), &apn->v4);
+	if (imsi_map) {
+		/* Override (prefill) any requested (dynamic|static) IP
+		 * in the EUA with the one from the configuration map. */
+		addr[0].len = 4;
+		memcpy(&addr[0].v4.s_addr, &imsi_map->addr.v4, 4);
+		LOGPPDP(LOGL_INFO, pdp, "IMSI[%s] has an entry[%s] in reserved IP map\n",
+			imsi_gtp2str(&pdp->imsi), in46a_ntoa(&imsi_map->addr));
+	}
+
 	/* Allocate dynamic addresses from the pool */
 	for (i = 0; i < num_addr; i++) {
 		if (in46a_is_v4(&addr[i])) {
@@ -502,6 +583,18 @@ int create_context_ind(struct pdp_t *pdp)
 				goto err_wrong_af;
 
 			rc = ippool_newip(apn->v4.pool, &member, &addr[i], 0);
+
+			if (!imsi_map) {
+				/* This IMSI does not have a reserved IP, check that we did not assign one */
+				while (apn_imsi_map_lookup_by_ip(&member->addr, &apn->v4)) {
+					LOGPPDP(LOGL_INFO, pdp, "Returned IP[%s] is reserved, trying again.\n",
+						in46a_ntoa(&member->addr));
+					ippool_freeip(member->pool, member);
+					rc = ippool_newip(apn->v4.pool, &member, &addr[i], 0);
+				}
+
+			}
+			LOGPPDP(LOGL_INFO, pdp, "Got IP[%s] from the pool.\n", in46a_ntoa(&member->addr));
 			if (rc < 0)
 				goto err_pool_full;
 			/* copy back */
@@ -584,6 +677,64 @@ err_wrong_af:
 	return 0;
 }
 
+static uint16_t inet_checksum(void *data, int len) {
+
+	int nleft = len;
+	int sum = 0;
+	unsigned short *w = data;
+	unsigned short checksum = 0;
+
+	while (nleft > 1) {
+		sum += *w++;
+		nleft -= 2;
+	}
+	if (nleft == 1){
+		*(unsigned char *)(&checksum) = *(unsigned char *)w;
+		sum += checksum;
+	}
+
+	sum = (sum >> 16) + (sum & 0xffff);
+	sum += (sum >> 16);
+	checksum = ~sum;
+	return (checksum);
+}
+
+/* Generate and send an ICMP HOST UNREACHABLE Packet */
+static void ipv4_host_unreach(struct tun_t *tun, void *pack, unsigned len)
+{
+	char send_buf[sizeof(struct ip) + sizeof(struct icmp) + len];
+	len = len - 20;
+	struct iphdr *iph = (struct iphdr *)pack;
+
+	memset(send_buf, 0, sizeof(send_buf));
+
+	struct ip *ip = (struct ip *)send_buf;
+	struct icmp *icmp = (struct icmp *)(ip + 1);
+
+	ip->ip_v = 4;
+	ip->ip_hl = 5;
+	ip->ip_tos = 0;
+	ip->ip_len = htons(sizeof(send_buf));
+	ip->ip_id = rand();
+	ip->ip_off = 0;
+	ip->ip_ttl = 64;
+	ip->ip_sum = 0;
+	ip->ip_p = IPPROTO_ICMP;
+	ip->ip_src.s_addr = iph->daddr;
+	ip->ip_dst.s_addr = iph->saddr;
+	ip->ip_sum = inet_checksum(ip, sizeof(send_buf));
+
+	icmp->icmp_type = ICMP_DEST_UNREACH;
+	icmp->icmp_code = ICMP_HOST_UNREACH;
+	icmp->icmp_id = 0;
+	icmp->icmp_seq = 0;
+	icmp->icmp_cksum = 0;
+
+	memcpy(send_buf + sizeof(ip) + sizeof(icmp) + 12, pack, len);
+	icmp->icmp_cksum = inet_checksum(icmp, sizeof(icmp) + 12 + len);
+	tun_encaps(tun, send_buf, sizeof(send_buf));
+}
+
 /* Internet-originated IP packet, needs to be sent via GTP towards MS */
 static int cb_tun_ind(struct tun_t *tun, void *pack, unsigned len)
 {
@@ -660,6 +811,10 @@ static int cb_tun_ind(struct tun_t *tun, void *pack, unsigned len)
  		       iph->version == 4 ?
  		         inet_ntop(AF_INET, &iph->saddr, straddr[1], sizeof(straddr[1])) :
  		         inet_ntop(AF_INET6, &ip6h->ip6_src, straddr[1], sizeof(straddr[1])));
+		/* TODO: Implement ipv6 */
+		if (iph->version != 4)
+			return 0;
+		ipv4_host_unreach(tun, pack, len);
 	}
 	return 0;
 }

ggsn/ggsn.h

@@ -6,7 +6,9 @@
 #include <osmocom/core/linuxlist.h>
 #include <osmocom/core/select.h>
 #include <osmocom/core/timer.h>
+#include <osmocom/core/tdef.h>
 #include <osmocom/ctrl/control_if.h>
+#include <osmocom/gsm/protocol/gsm_23_003.h>
 
 #include "../lib/tun.h"
 #include "../lib/ippool.h"
@@ -34,6 +36,9 @@ struct apn_ctx_ip {
 
 	/* v4 address pool */
 	struct ippool_t *pool;
+	/* Static IMSI to IPv4 reserved address mappings. */
+	struct llist_head imsi_ip_map;
+
 };
 
 struct apn_name {
@@ -46,6 +51,15 @@ enum apn_gtpu_mode {
 	APN_GTPU_MODE_KERNEL_GTP,
 };
 
+/*
+ * IMSI to static IP map handling
+ */
+struct imsi_map_entry {
+	struct llist_head list;
+	char imsi[OSMO_IMSI_BUF_SIZE];
+	struct in46_addr addr;
+};
+
 struct apn_ctx {
 	/* list of APNs inside GGSN */
 	struct llist_head list;
@@ -65,9 +79,9 @@ struct apn_ctx {
 		uint32_t apn_type_mask;
 		/* GTP-U via TUN device or in Linux kernel */
 		enum apn_gtpu_mode gtpu_mode;
-		/* administratively shut-down (true) or not (false) */
+		/* administratively shut down (true) or not (false) */
 		bool shutdown;
-		/* transmit G-PDU sequeence numbers (true) or not (false) */
+		/* transmit G-PDU sequence numbers (true) or not (false) */
 		bool tx_gpdu_seq;
 	} cfg;
 
@@ -127,7 +141,7 @@ struct ggsn_ctx {
 		char *state_dir;
 		/* Time between Echo requests on each SGSN */
 		unsigned int echo_interval;
-		/* administratively shut-down (true) or not (false) */
+		/* administratively shut down (true) or not (false) */
 		bool shutdown;
 	} cfg;
 
@@ -152,6 +166,7 @@ struct apn_ctx *ggsn_find_or_create_apn(struct ggsn_ctx *ggsn, const char *name)
 /* ggsn_main.c */
 extern struct ctrl_handle *g_ctrlh;
 extern void *tall_ggsn_ctx;
+extern struct osmo_tdef_group ggsn_tdef_group[];
 
 /* ggsn.c */
 extern int ggsn_start(struct ggsn_ctx *ggsn);
@@ -159,6 +174,9 @@ extern int ggsn_stop(struct ggsn_ctx *ggsn);
 extern int apn_start(struct apn_ctx *apn);
 extern int apn_stop(struct apn_ctx *apn);
 void ggsn_close_one_pdp(struct pdp_t *pdp);
+bool apn_supports_ipv4(const struct apn_ctx *apn);
+int apn_imsi_ip_map_add(const char *imsi, const char *ip, struct apn_ctx_ip *ctx);
+int apn_imsi_ip_map_del(const char *imsi, const char *ip, struct apn_ctx_ip *ctx);
 
 #define LOGPAPN(level, apn, fmt, args...)			\
 	LOGP(DGGSN, level, "APN(%s): " fmt, (apn)->cfg.name, ## args)
@@ -167,6 +185,3 @@ void ggsn_close_one_pdp(struct pdp_t *pdp);
 	LOGP(DGGSN, level, "GGSN(%s): " fmt, (ggsn)->cfg.name, ## args)
 
 #define LOGPPDP(level, pdp, fmt, args...) LOGPDPX(DGGSN, level, pdp, fmt, ## args)
-
-#define LOGTUN(level, tun, fmt, args...) \
-	LOGP(DTUN, level, "TUN(%s): " fmt, (tun)->devname, ## args)

ggsn/ggsn_main.c

@@ -34,6 +34,7 @@
 #include <osmocom/core/stats.h>
 #include <osmocom/core/rate_ctr.h>
 #include <osmocom/core/timer.h>
+#include <osmocom/core/tdef.h>
 #include <osmocom/core/utils.h>
 #include <osmocom/ctrl/control_if.h>
 #include <osmocom/ctrl/control_cmd.h>
@@ -60,6 +61,11 @@ struct ul255_t apn;
 
 static char *config_file = "osmo-ggsn.cfg";
 
+struct osmo_tdef_group ggsn_tdef_group[] = {
+	{.name = "gtp", .tdefs = gtp_T_defs, .desc = "GTP (libgtp) timers" },
+	{ }
+};
+
 /* To exit gracefully. Used with GCC compilation flag -pg and gprof */
 static void signal_handler(int s)
 {
@@ -217,12 +223,11 @@ int main(int argc, char **argv)
 		exit(2);
 	}
 
-	rc = telnet_init_dynif(tall_ggsn_ctx, NULL, vty_get_bind_addr(), OSMO_VTY_PORT_GGSN);
+	rc = telnet_init_default(tall_ggsn_ctx, NULL, OSMO_VTY_PORT_GGSN);
 	if (rc < 0)
 		exit(1);
 
-	g_ctrlh = ctrl_interface_setup_dynip(NULL, ctrl_vty_get_bind_addr(),
-					     OSMO_CTRL_PORT_GGSN, NULL);
+	g_ctrlh = ctrl_interface_setup(NULL, OSMO_CTRL_PORT_GGSN, NULL);
 	if (!g_ctrlh) {
 		LOGP(DGGSN, LOGL_ERROR, "Failed to create CTRL interface.\n");
 		exit(1);

ggsn/ggsn_vty.c

@@ -33,6 +33,7 @@
 #include <osmocom/vty/command.h>
 #include <osmocom/vty/vty.h>
 #include <osmocom/vty/misc.h>
+#include <osmocom/vty/tdef_vty.h>
 
 #include "../gtp/gtp.h"
 #include "../gtp/pdp.h"
@@ -111,6 +112,7 @@ struct apn_ctx *ggsn_find_or_create_apn(struct ggsn_ctx *ggsn, const char *name)
 	apn->cfg.shutdown = true;
 	apn->cfg.tx_gpdu_seq = true;
 	INIT_LLIST_HEAD(&apn->cfg.name_list);
+	INIT_LLIST_HEAD(&apn->v4.imsi_ip_map);
 
 	llist_add_tail(&apn->list, &ggsn->apn_list);
 	return apn;
@@ -298,7 +300,7 @@ DEFUN(cfg_ggsn_no_default_apn, cfg_ggsn_no_default_apn_cmd,
 
 DEFUN(cfg_ggsn_shutdown, cfg_ggsn_shutdown_cmd,
 	"shutdown ggsn",
-	"Put the GGSN in administrative shut-down\n" GGSN_STR)
+	"Put the GGSN in administrative shutdown\n" GGSN_STR)
 {
 	struct ggsn_ctx *ggsn = (struct ggsn_ctx *) vty->index;
 
@@ -315,7 +317,7 @@ DEFUN(cfg_ggsn_shutdown, cfg_ggsn_shutdown_cmd,
 
 DEFUN(cfg_ggsn_no_shutdown, cfg_ggsn_no_shutdown_cmd,
 	"no shutdown ggsn",
-	NO_STR GGSN_STR "Remove the GGSN from administrative shut-down\n")
+	NO_STR GGSN_STR "Remove the GGSN from administrative shutdown\n")
 {
 	struct ggsn_ctx *ggsn = (struct ggsn_ctx *) vty->index;
 
@@ -343,7 +345,7 @@ static void show_one_sgsn(struct vty *vty, const struct sgsn_peer *sgsn, const c
 
 DEFUN(cfg_ggsn_show_sgsn, cfg_ggsn_show_sgsn_cmd,
 	"show sgsn",
-	NO_STR GGSN_STR "Remove the GGSN from administrative shut-down\n")
+	NO_STR GGSN_STR "Remove the GGSN from administrative shutdown\n")
 {
 	struct ggsn_ctx *ggsn = (struct ggsn_ctx *) vty->index;
 	struct sgsn_peer *sgsn;
@@ -389,10 +391,9 @@ DEFUN(cfg_ggsn_no_echo_interval, cfg_ggsn_no_echo_interval_cmd,
 	NO_STR "Send an echo request to this static GGSN every interval.\n")
 {
 	struct ggsn_ctx *ggsn = (struct ggsn_ctx *) vty->index;
-	int prev_interval = ggsn->cfg.echo_interval;
 	struct sgsn_peer *sgsn;
 
-	if (prev_interval == ggsn->cfg.echo_interval)
+	if (ggsn->cfg.echo_interval == 0)
 		return CMD_SUCCESS;
 
 	ggsn->cfg.echo_interval = 0;
@@ -562,6 +563,58 @@ DEFUN(cfg_apn_no_ip_ifconfig, cfg_apn_no_ip_ifconfig_cmd,
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_apn_imsi_ip_map, cfg_apn_imsi_ip_map_cmd,
+	"imsi-ip-map (add|del) IMSI [A.B.C.D]",
+	"List of IMSI to RESERVED ip4 mappings\n"
+	"Add IMSI/IP pair to mappings\n"
+	"Remove IMSI/IP pair from mappings\n"
+	"IMSI of the subscriber\n"
+	"IP for the subscriber\n")
+{
+	char imsi_sanitized[GSM23003_IMSI_MAX_DIGITS + 1];
+	const char *op = argv[0];
+	const char *imsi = imsi_sanitized;
+	size_t len = strnlen(argv[1], GSM23003_IMSI_MAX_DIGITS + 1);
+	const char *ip = argv[2];
+	int rc;
+
+	struct apn_ctx *apn = (struct apn_ctx *) vty->index;
+
+	if (!apn_supports_ipv4(apn)) {
+		vty_out(vty, "%% APN does not support ipv4 addresses%s", VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	memset(imsi_sanitized, '0', GSM23003_IMSI_MAX_DIGITS);
+	imsi_sanitized[GSM23003_IMSI_MAX_DIGITS] = '\0';
+
+	/* Sanitize IMSI */
+	if (len > GSM23003_IMSI_MAX_DIGITS) {
+		vty_out(vty, "%% IMSI (%s) too long (max %u digits) -- ignored!%s",
+			argv[1], GSM23003_IMSI_MAX_DIGITS, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	osmo_strlcpy(imsi_sanitized + GSM23003_IMSI_MAX_DIGITS - len, argv[1],
+		     sizeof(imsi_sanitized) - (GSM23003_IMSI_MAX_DIGITS - len));
+
+	if (!strcmp(op, "add")) {
+		if (!ip) {
+			vty_out(vty, "%% unable to %s IMSI without IP address%s", op, VTY_NEWLINE);
+			return CMD_WARNING;
+		}
+		rc = apn_imsi_ip_map_add(imsi, ip, &apn->v4);
+	} else {
+		rc = apn_imsi_ip_map_del(imsi, ip, &apn->v4);
+	}
+	if (rc < 0) {
+		vty_out(vty, "%% unable to %s IMSI%s", op, VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	return CMD_SUCCESS;
+}
+
 DEFUN(cfg_apn_ipv6_prefix, cfg_apn_ipv6_prefix_cmd,
 	"ipv6 prefix (static|dynamic) X:X::X:X/M",
 	IP6_STR PREFIX_STR "IPv6 Address/Prefix-Length\n")
@@ -681,7 +734,7 @@ DEFUN(cfg_apn_no_gpdu_seq, cfg_apn_no_gpdu_seq_cmd,
 
 DEFUN(cfg_apn_shutdown, cfg_apn_shutdown_cmd,
 	"shutdown",
-	"Put the APN in administrative shut-down\n")
+	"Put the APN in administrative shutdown\n")
 {
 	struct apn_ctx *apn = (struct apn_ctx *) vty->index;
 
@@ -698,7 +751,7 @@ DEFUN(cfg_apn_shutdown, cfg_apn_shutdown_cmd,
 
 DEFUN(cfg_apn_no_shutdown, cfg_apn_no_shutdown_cmd,
 	"no shutdown",
-	NO_STR "Remove the APN from administrative shut-down\n")
+	NO_STR "Remove the APN from administrative shutdown\n")
 {
 	struct apn_ctx *apn = (struct apn_ctx *) vty->index;
 
@@ -726,6 +779,7 @@ static void vty_dump_prefix(struct vty *vty, const char *pre, const struct in46_
 static void config_write_apn(struct vty *vty, struct apn_ctx *apn)
 {
 	unsigned int i;
+	struct imsi_map_entry *map;
 
 	vty_out(vty, " apn %s%s", apn->cfg.name, VTY_NEWLINE);
 	if (apn->cfg.description)
@@ -762,6 +816,9 @@ static void config_write_apn(struct vty *vty, struct apn_ctx *apn)
 	if (apn->v4.cfg.ifconfig_prefix.addr.len)
 		vty_dump_prefix(vty, "  ip ifconfig", &apn->v4.cfg.ifconfig_prefix);
 
+	llist_for_each_entry(map, &apn->v4.imsi_ip_map, list)
+		vty_out(vty, "  imsi-ip-map add %s %s%s", map->imsi, in46a_ntoa(&map->addr), VTY_NEWLINE);
+
 	/* IPv6 prefixes + DNS */
 	if (apn->v6.cfg.static_prefix.addr.len)
 		vty_dump_prefix(vty, "  ipv6 prefix static", &apn->v6.cfg.static_prefix);
@@ -796,6 +853,7 @@ static int config_write_ggsn(struct vty *vty)
 			vty_out(vty, " gtp control-ip %s%s", in46a_ntoa(&ggsn->cfg.gtpc_addr), VTY_NEWLINE);
 		if (ggsn->cfg.gtpu_addr.v4.s_addr)
 			vty_out(vty, " gtp user-ip %s%s", in46a_ntoa(&ggsn->cfg.gtpu_addr), VTY_NEWLINE);
+		osmo_tdef_vty_groups_write(vty, " ");
 		llist_for_each_entry(apn, &ggsn->apn_list, list)
 			config_write_apn(vty, apn);
 		if (ggsn->cfg.default_apn)
@@ -1114,6 +1172,8 @@ int ggsn_vty_init(void)
 	install_element(GGSN_NODE, &cfg_ggsn_echo_interval_cmd);
 	install_element(GGSN_NODE, &cfg_ggsn_no_echo_interval_cmd);
 
+	osmo_tdef_vty_groups_init(GGSN_NODE, ggsn_tdef_group);
+
 	install_node(&apn_node, NULL);
 	install_element(APN_NODE, &cfg_description_cmd);
 	install_element(APN_NODE, &cfg_no_description_cmd);
@@ -1128,6 +1188,7 @@ int ggsn_vty_init(void)
 	install_element(APN_NODE, &cfg_apn_ipdown_script_cmd);
 	install_element(APN_NODE, &cfg_apn_no_ipdown_script_cmd);
 	install_element(APN_NODE, &cfg_apn_ip_prefix_cmd);
+	install_element(APN_NODE, &cfg_apn_imsi_ip_map_cmd);
 	install_element(APN_NODE, &cfg_apn_ipv6_prefix_cmd);
 	install_element(APN_NODE, &cfg_apn_ip_dns_cmd);
 	install_element(APN_NODE, &cfg_apn_ipv6_dns_cmd);

ggsn/pco.h

@@ -4,7 +4,7 @@
 
 #include "../gtp/pdp.h"
 
-/* 3GPP TS 24.008 10.6.5.3 */
+/* 3GPP TS 24.008 10.5.6.3 */
 enum pco_protocols {
 	PCO_P_LCP		= 0xC021,
 	PCO_P_PAP		= 0xC023,

ggsn/sgsn.c

@@ -116,6 +116,7 @@ static unsigned int sgsn_peer_drop_all_pdp_except(struct sgsn_peer *sgsn, struct
 {
 	unsigned int num = 0;
 	char buf[INET_ADDRSTRLEN];
+	unsigned int count = llist_count(&sgsn->pdp_list);
 
 	inet_ntop(AF_INET, &sgsn->addr, buf, sizeof(buf));
 
@@ -125,10 +126,17 @@ static unsigned int sgsn_peer_drop_all_pdp_except(struct sgsn_peer *sgsn, struct
 			continue;
 		ggsn_close_one_pdp(pdp->lib);
 		num++;
+		if (num == count) {
+			/* Note: if except is NULL, all pdp contexts are freed and sgsn
+			 * is most probably already freed at this point.
+			 * As a result, last access to sgsn->pdp_list before exiting
+			 * loop would access already freed memory. Avoid it by exiting
+			 * the loop without the last check, and make sure sgsn is not
+			 * accessed after this loop. */
+			 break;
+		}
 	}
 
-	/* Note: if except is NULL, all pdp contexts are freed and sgsn is
-	   already freed at this point */
 	LOGP(DGGSN, LOGL_INFO, "SGSN(%s) Dropped %u PDP contexts\n", buf, num);
 
 	return num;

gtp/Makefile.am

@@ -2,14 +2,14 @@
 # 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
 # If major=current-age is increased, remember to update the dh_strip line in debian/rules!
-LIBVERSION=7:0:1
+LIBVERSION=9:0:3
 
 lib_LTLIBRARIES = libgtp.la
 
-include_HEADERS = gtp.h pdp.h gtpie.h
+include_HEADERS = gtp.h gsn.h pdp.h gtpie.h
 
-AM_CFLAGS = -O2 -fno-builtin -Wall -DSBINDIR='"$(sbindir)"' -ggdb $(LIBOSMOCORE_CFLAGS)
+AM_CFLAGS = -fno-builtin -Wall -DSBINDIR='"$(sbindir)"' $(LIBOSMOCORE_CFLAGS)
 
-libgtp_la_SOURCES = gtp.c gtp.h gtpie.c gtpie.h pdp.c pdp.h lookupa.c lookupa.h queue.c queue.h
+libgtp_la_SOURCES = gtp.c gtp.h gsn.c gsn.h gtpie.c gtpie.h pdp.c pdp.h lookupa.c lookupa.h queue.c queue.h
 libgtp_la_LDFLAGS = -version-info $(LIBVERSION) -no-undefined
 libgtp_la_LIBADD = $(LIBOSMOCORE_LIBS)

gtp/gsn.c

@@ -0,0 +1,596 @@
+/*
+ *  OsmoGGSN - Gateway GPRS Support Node
+ *  Copyright (C) 2002, 2003, 2004 Mondru AB.
+ *  Copyright (C) 2010-2011, 2016-2017 Harald Welte <laforge@gnumonks.org>
+ *  Copyright (C) 2015-2017 sysmocom - s.f.m.c. GmbH
+ *
+ *  The contents of this file may be used under the terms of the GNU
+ *  General Public License Version 2, provided that the above copyright
+ *  notice and this permission notice is included in all copies or
+ *  substantial portions of the software.
+ *
+ */
+
+/*
+ * gtp.c: Contains all GTP functionality. Should be able to handle multiple
+ * tunnels in the same program.
+ *
+ * TODO:
+ *  - Do we need to handle fragmentation?
+ */
+
+#ifdef __linux__
+#define _GNU_SOURCE 1
+#endif
+
+#include <osmocom/core/logging.h>
+#include <osmocom/core/utils.h>
+#include <osmocom/core/stats.h>
+#include <osmocom/core/rate_ctr.h>
+
+#if defined(__FreeBSD__)
+#include <sys/endian.h>
+#endif
+
+#include "../config.h"
+#ifdef HAVE_STDINT_H
+#include <stdint.h>
+#endif
+
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <sys/stat.h>
+#include <time.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+
+#include <arpa/inet.h>
+
+/* #include <stdint.h>  ISO C99 types */
+
+#include "pdp.h"
+#include "gtp.h"
+#include "gtpie.h"
+#include "queue.h"
+
+/* Error reporting functions */
+
+#define LOGP_WITH_ADDR(ss, level, addr, fmt, args...)                    \
+		LOGP(ss, level, "addr(%s:%d) " fmt,                      \
+		     inet_ntoa((addr).sin_addr), htons((addr).sin_port), \
+		     ##args);
+
+static const struct rate_ctr_desc gsn_ctr_description[] = {
+	[GSN_CTR_ERR_SOCKET] = { "err:socket", "Socket error" },
+	[GSN_CTR_ERR_READFROM] = { "err:readfrom", "readfrom() errors" },
+	[GSN_CTR_ERR_SENDTO] = { "err:sendto", "sendto() errors" },
+	[GSN_CTR_ERR_QUEUEFULL] = { "err:queuefull", "Failed to queue message because queue is full" },
+	[GSN_CTR_ERR_SEQ] = { "err:seq", "Sequence number out of range" },
+	[GSN_CTR_ERR_ADDRESS] = { "err:address", "GSN address conversion failed" },
+	[GSN_CTR_ERR_UNKNOWN_PDP] = { "err:unknown_pdp", "Failed looking up PDP context" },
+	[GSN_CTR_ERR_UNEXPECTED_CAUSE] = { "err:unexpected_cause", "Unexpected cause value received" },
+	[GSN_CTR_ERR_OUT_OF_PDP] = { "err:out_of_pdp", "Out of storage for PDP contexts" },
+	[GSN_CTR_PKT_EMPTY] = { "pkt:empty", "Empty packet received" },
+	[GSN_CTR_PKT_UNSUP] = { "pkt:unsupported", "Unsupported GTP version received" },
+	[GSN_CTR_PKT_TOOSHORT] = { "pkt:too_short", "Packet too short received" },
+	[GSN_CTR_PKT_UNKNOWN] = { "pkt:unknown", "Unknown packet type received" },
+	[GSN_CTR_PKT_UNEXPECT] = { "pkt:unexpected", "Unexpected packet type received" },
+	[GSN_CTR_PKT_DUPLICATE] = { "pkt:duplicate", "Duplicate or unsolicited packet received" },
+	[GSN_CTR_PKT_MISSING] = { "pkt:missing", "Missing IE in packet received" },
+	[GSN_CTR_PKT_INCORRECT] = { "pkt:incorrect", "Incorrect IE in packet received" },
+	[GSN_CTR_PKT_INVALID] = { "pkt:invalid", "Invalid format in packet received" },
+};
+
+static const struct rate_ctr_group_desc gsn_ctrg_desc = {
+	"gsn",
+	"GSN Statistics",
+	OSMO_STATS_CLASS_PEER,
+	ARRAY_SIZE(gsn_ctr_description),
+	gsn_ctr_description,
+};
+static unsigned int gsn_ctr_next_idx = 0;
+
+/* Global timer definitions for GTP operation, provided for convenience. To make these user configurable, it is convenient to add
+ * gtp_gsn_tdefs as one of your program's osmo_tdef_group entries and call osmo_tdef_vty_init(). */
+struct osmo_tdef gtp_T_defs[] = {
+	{ .T = GTP_GSN_TIMER_T3_RESPONSE, .default_val = 5, .unit = OSMO_TDEF_S,
+	  .desc = "Timer T3-RESPONSE holds the maximum wait time for a response of a request message"
+	},
+	{ .T = GTP_GSN_TIMER_N3_REQUESTS, .default_val = 3, .unit = OSMO_TDEF_CUSTOM,
+	  .desc = "Counter N3-REQUESTS holds the maximum number of attempts made by GTP to send a request message"
+	},
+	{ .T = GTP_GSN_TIMER_T3_HOLD_RESPONSE, .default_val = 5 * 3 /* (GTP_GSN_TIMER_T3_RESPONSE * GTP_GSN_TIMER_N3_REQUESTS) */, .unit = OSMO_TDEF_S,
+	  .desc = "Time a GTP respoonse message is kept cached to re-transmit it when a duplicate request is received. Value is generally equal to (T3-RESPONSE * N3-REQUESTS) set at the peer"
+	},
+	{}
+};
+
+
+/* API Functions */
+
+/* Deprecated, use gtp_pdp_newpdp() instead */
+int gtp_newpdp(struct gsn_t *gsn, struct pdp_t **pdp,
+	       uint64_t imsi, uint8_t nsapi)
+{
+	int rc;
+	rc = gtp_pdp_newpdp(gsn, pdp, imsi, nsapi, NULL);
+	return rc;
+}
+
+int gtp_freepdp(struct gsn_t *gsn, struct pdp_t *pdp)
+{
+	if (gsn->cb_delete_context)
+		gsn->cb_delete_context(pdp);
+	return pdp_freepdp(pdp);
+}
+
+/* Free pdp and all its secondary PDP contexts. Must be called on the primary PDP context. */
+int gtp_freepdp_teardown(struct gsn_t *gsn, struct pdp_t *pdp)
+{
+	int n;
+	struct pdp_t *secondary_pdp;
+	OSMO_ASSERT(!pdp->secondary);
+
+	for (n = 0; n < PDP_MAXNSAPI; n++) {
+		if (pdp->secondary_tei[n]) {
+			if (gtp_pdp_getgtp1(gsn, &secondary_pdp,
+					     pdp->secondary_tei[n])) {
+				LOGP(DLGTP, LOGL_ERROR,
+					"Unknown secondary PDP context\n");
+				continue;
+			}
+			if (pdp != secondary_pdp) {
+				gtp_freepdp(gsn, secondary_pdp);
+			}
+		}
+	}
+
+	return gtp_freepdp(gsn, pdp);
+}
+
+/* gtp_gpdu */
+
+extern int gtp_fd(struct gsn_t *gsn)
+{
+	return gsn->fd0;
+}
+
+int gtp_set_cb_unsup_ind(struct gsn_t *gsn,
+			 int (*cb) (struct sockaddr_in * peer))
+{
+	gsn->cb_unsup_ind = cb;
+	return 0;
+}
+
+int gtp_set_cb_extheader_ind(struct gsn_t *gsn,
+			     int (*cb) (struct sockaddr_in * peer))
+{
+	gsn->cb_extheader_ind = cb;
+	return 0;
+}
+
+int gtp_set_cb_ran_info_relay_ind(struct gsn_t *gsn,
+			     int (*cb) (struct sockaddr_in * peer, union gtpie_member **ie))
+{
+	gsn->cb_ran_info_relay_ind = cb;
+	return 0;
+}
+
+/* API: Initialise delete context callback */
+/* Called whenever a pdp context is deleted for any reason */
+int gtp_set_cb_delete_context(struct gsn_t *gsn, int (*cb) (struct pdp_t * pdp))
+{
+	gsn->cb_delete_context = cb;
+	return 0;
+}
+
+int gtp_set_cb_conf(struct gsn_t *gsn,
+		    int (*cb) (int type, int cause,
+			       struct pdp_t * pdp, void *cbp))
+{
+	gsn->cb_conf = cb;
+	return 0;
+}
+
+int gtp_set_cb_recovery(struct gsn_t *gsn,
+			int (*cb) (struct sockaddr_in * peer, uint8_t recovery))
+{
+	gsn->cb_recovery = cb;
+	return 0;
+}
+
+/* cb_recovery()
+ * pdp may be NULL if Recovery IE was received from a message independent
+ * of any PDP ctx (such as Echo Response), or because pdp ctx is unknown to the
+ * local setup. In case pdp is known, caller may want to keep that pdp alive to
+ * handle subsequent msg cb as this specific pdp ctx is still valid according to
+ * specs.
+ */
+int gtp_set_cb_recovery2(struct gsn_t *gsn,
+			int (*cb_recovery2) (struct sockaddr_in * peer, struct pdp_t * pdp, uint8_t recovery))
+{
+	gsn->cb_recovery2 = cb_recovery2;
+	return 0;
+}
+
+/* cb_recovery()
+ * pdp may be NULL if Recovery IE was received from a message independent
+ * of any PDP ctx (such as Echo Response), or because pdp ctx is unknown to the
+ * local setup. In case pdp is known, caller may want to keep that pdp alive to
+ * handle subsequent msg cb as this specific pdp ctx is still valid according to
+ * specs.
+ */
+int gtp_set_cb_recovery3(struct gsn_t *gsn,
+			 int (*cb_recovery3) (struct gsn_t *gsn, struct sockaddr_in *peer,
+					      struct pdp_t *pdp, uint8_t recovery))
+{
+	gsn->cb_recovery3 = cb_recovery3;
+	return 0;
+}
+
+int gtp_set_cb_data_ind(struct gsn_t *gsn,
+			       int (*cb_data_ind) (struct pdp_t * pdp,
+						   void *pack, unsigned len))
+{
+	gsn->cb_data_ind = cb_data_ind;
+	return 0;
+}
+
+static int queue_timer_retrans(struct gsn_t *gsn)
+{
+	/* Retransmit any outstanding packets */
+	/* Remove from queue if maxretrans exceeded */
+	time_t now;
+	struct qmsg_t *qmsg;
+	unsigned int t3_response, n3_requests;
+
+	now = time(NULL);
+	t3_response = osmo_tdef_get(gsn->tdef, GTP_GSN_TIMER_T3_RESPONSE, OSMO_TDEF_S, -1);
+	n3_requests = osmo_tdef_get(gsn->tdef, GTP_GSN_TIMER_N3_REQUESTS, OSMO_TDEF_CUSTOM, -1);
+
+	/* get first element in queue, as long as the timeout of that
+	 * element has expired */
+	while ((!queue_getfirst(gsn->queue_req, &qmsg)) &&
+	       (qmsg->timeout <= now)) {
+		if (qmsg->retrans > n3_requests) {	/* Too many retrans */
+			LOGP(DLGTP, LOGL_NOTICE, "Retransmit req queue timeout of seq %" PRIu16 "\n",
+			     qmsg->seq);
+			if (gsn->cb_conf)
+				gsn->cb_conf(qmsg->type, EOF, NULL, qmsg->cbp);
+			queue_freemsg(gsn->queue_req, qmsg);
+		} else {
+			LOGP(DLGTP, LOGL_INFO, "Retransmit (%d) of seq %" PRIu16 "\n",
+			     qmsg->retrans, qmsg->seq);
+			if (sendto(qmsg->fd, &qmsg->p, qmsg->l, 0,
+				   (struct sockaddr *)&qmsg->peer,
+				   sizeof(struct sockaddr_in)) < 0) {
+				rate_ctr_inc2(gsn->ctrg, GSN_CTR_ERR_SENDTO);
+				LOGP(DLGTP, LOGL_ERROR,
+					"Sendto(fd0=%d, msg=%lx, len=%d) failed: Error = %s\n",
+					gsn->fd0, (unsigned long)&qmsg->p,
+					qmsg->l, strerror(errno));
+			}
+			queue_back(gsn->queue_req, qmsg);
+			qmsg->timeout = now + t3_response;
+			qmsg->retrans++;
+		}
+	}
+
+	/* Also clean up reply timeouts */
+	while ((!queue_getfirst(gsn->queue_resp, &qmsg)) &&
+	       (qmsg->timeout < now)) {
+		LOGP(DLGTP, LOGL_DEBUG, "Retransmit resp queue seq %"
+		     PRIu16 " expired, removing from queue\n", qmsg->seq);
+		queue_freemsg(gsn->queue_resp, qmsg);
+	}
+
+	return 0;
+}
+
+static int queue_timer_retranstimeout(struct gsn_t *gsn, struct timeval *timeout)
+{
+	time_t now, later, diff;
+	struct qmsg_t *qmsg;
+	timeout->tv_usec = 0;
+
+	if (queue_getfirst(gsn->queue_req, &qmsg)) {
+		timeout->tv_sec = 10;
+	} else {
+		now = time(NULL);
+		later = qmsg->timeout;
+		timeout->tv_sec = later - now;
+		if (timeout->tv_sec < 0)
+			timeout->tv_sec = 0;	/* No negative allowed */
+		if (timeout->tv_sec > 10)
+			timeout->tv_sec = 10;	/* Max sleep for 10 sec */
+	}
+
+	if (queue_getfirst(gsn->queue_resp, &qmsg)) {
+		/* already set by queue_req, do nothing */
+	} else { /* trigger faster if earlier timeout exists in queue_resp */
+		now = time(NULL);
+		later = qmsg->timeout;
+		diff = later - now;
+		if (diff < 0)
+			diff = 0;
+		if (diff < timeout->tv_sec)
+			timeout->tv_sec = diff;
+	}
+
+	return 0;
+}
+
+void gtp_queue_timer_start(struct gsn_t *gsn)
+{
+	struct timeval next;
+
+	/* Retrieve next retransmission as timeval */
+	queue_timer_retranstimeout(gsn, &next);
+
+	/* re-schedule the timer */
+	osmo_timer_schedule(&gsn->queue_timer, next.tv_sec, next.tv_usec/1000);
+}
+
+/* timer callback for libgtp retransmission and ping */
+static void queue_timer_cb(void *data)
+{
+	struct gsn_t *gsn = data;
+
+	/* do all the retransmissions as needed */
+	queue_timer_retrans(gsn);
+
+	gtp_queue_timer_start(gsn);
+}
+
+
+/**
+ * @brief clear the request and response queue. Useful for debugging to reset "some" state.
+ * @param gsn The GGSN instance
+ */
+void gtp_clear_queues(struct gsn_t *gsn)
+{
+	struct qmsg_t *qmsg;
+
+	LOGP(DLGTP, LOGL_INFO, "Clearing req & resp retransmit queues\n");
+	while (!queue_getfirst(gsn->queue_req, &qmsg)) {
+		queue_freemsg(gsn->queue_req, qmsg);
+	}
+
+	while (!queue_getfirst(gsn->queue_resp, &qmsg)) {
+		queue_freemsg(gsn->queue_resp, qmsg);
+	}
+}
+
+/* Perform restoration and recovery error handling as described in 29.060 */
+static void log_restart(struct gsn_t *gsn)
+{
+	FILE *f;
+	int i, rc;
+	int counter = 0;
+	char *filename;
+
+	filename = talloc_asprintf(NULL, "%s/%s", gsn->statedir, RESTART_FILE);
+	OSMO_ASSERT(filename);
+
+	/* We try to open file. On failure we will later try to create file */
+	if (!(f = fopen(filename, "r"))) {
+		LOGP(DLGTP, LOGL_NOTICE,
+			"State information file (%s) not found. Creating new file.\n",
+			filename);
+	} else {
+		rc = fscanf(f, "%d", &counter);
+		if (rc != 1) {
+			LOGP(DLGTP, LOGL_ERROR,
+				"fscanf failed to read counter value\n");
+			goto close_file;
+		}
+		if (fclose(f)) {
+			LOGP(DLGTP, LOGL_ERROR,
+				"fclose failed: Error = %s\n", strerror(errno));
+		}
+	}
+
+	gsn->restart_counter = (unsigned char)counter;
+	gsn->restart_counter++;
+
+	/* Keep the umask closely wrapped around our fopen() call in case the
+	 * log outputs cause file creation. */
+	i = umask(022);
+	f = fopen(filename, "w");
+	umask(i);
+	if (!f) {
+		LOGP(DLGTP, LOGL_ERROR,
+			"fopen(path=%s, mode=%s) failed: Error = %s\n", filename,
+			"w", strerror(errno));
+		goto free_filename;
+	}
+
+	fprintf(f, "%d\n", gsn->restart_counter);
+close_file:
+	if (fclose(f))
+		LOGP(DLGTP, LOGL_ERROR,
+			"fclose failed: Error = %s\n", strerror(errno));
+free_filename:
+	talloc_free(filename);
+}
+
+int gtp_new(struct gsn_t **gsn, char *statedir, struct in_addr *listen,
+	    int mode)
+{
+	struct sockaddr_in addr;
+
+	LOGP(DLGTP, LOGL_NOTICE, "GTP: gtp_newgsn() started at %s\n", inet_ntoa(*listen));
+
+	*gsn = calloc(sizeof(struct gsn_t), 1);	/* TODO */
+
+	(*gsn)->statedir = statedir;
+	log_restart(*gsn);
+
+	/* Initialise sequence number */
+	(*gsn)->seq_next = (*gsn)->restart_counter * 1024;
+
+	/* Initialize timers: */
+	(*gsn)->tdef = gtp_T_defs;
+	/* Small hack to properly reset tdef for old clients not using the tdef_group: */
+	OSMO_ASSERT(gtp_T_defs[0].default_val != 0);
+	if (gtp_T_defs[0].val == 0)
+		osmo_tdefs_reset((*gsn)->tdef);
+
+
+	/* Initialise request retransmit queue */
+	queue_new(&(*gsn)->queue_req);
+	queue_new(&(*gsn)->queue_resp);
+
+	/* Initialise pdp table */
+	pdp_init(*gsn);
+
+	/* Initialize internal queue timer */
+	osmo_timer_setup(&(*gsn)->queue_timer, queue_timer_cb, *gsn);
+
+	/* Initialize counter group: */
+	(*gsn)->ctrg = rate_ctr_group_alloc(NULL, &gsn_ctrg_desc, gsn_ctr_next_idx++);
+
+	/* Initialise call back functions */
+	(*gsn)->cb_create_context_ind = 0;
+	(*gsn)->cb_delete_context = 0;
+	(*gsn)->cb_unsup_ind = 0;
+	(*gsn)->cb_conf = 0;
+	(*gsn)->cb_data_ind = 0;
+
+	/* Store function parameters */
+	(*gsn)->gsnc = *listen;
+	(*gsn)->gsnu = *listen;
+	(*gsn)->mode = mode;
+
+	/* Create GTP version 0 socket */
+	if (((*gsn)->fd0 = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
+		rate_ctr_inc2((*gsn)->ctrg, GSN_CTR_ERR_SOCKET);
+		LOGP(DLGTP, LOGL_ERROR,
+		     "GTPv0 socket(domain=%d, type=%d, protocol=%d) failed: Error = %s\n",
+			AF_INET, SOCK_DGRAM, 0, strerror(errno));
+		return -errno;
+	}
+
+	memset(&addr, 0, sizeof(addr));
+	addr.sin_family = AF_INET;
+	addr.sin_addr = *listen;	/* Same IP for user traffic and signalling */
+	addr.sin_port = htons(GTP0_PORT);
+#if defined(__FreeBSD__) || defined(__APPLE__)
+	addr.sin_len = sizeof(addr);
+#endif
+
+	if (bind((*gsn)->fd0, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
+		rate_ctr_inc2((*gsn)->ctrg, GSN_CTR_ERR_SOCKET);
+		LOGP_WITH_ADDR(DLGTP, LOGL_ERROR, addr,
+			       "bind(fd0=%d) failed: Error = %s\n",
+			       (*gsn)->fd0, strerror(errno));
+		return -errno;
+	}
+
+	/* Create GTP version 1 control plane socket */
+	if (((*gsn)->fd1c = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
+		rate_ctr_inc2((*gsn)->ctrg, GSN_CTR_ERR_SOCKET);
+		LOGP(DLGTP, LOGL_ERROR,
+		     "GTPv1 control plane socket(domain=%d, type=%d, protocol=%d) failed: Error = %s\n",
+			AF_INET, SOCK_DGRAM, 0, strerror(errno));
+		return -errno;
+	}
+
+	memset(&addr, 0, sizeof(addr));
+	addr.sin_family = AF_INET;
+	addr.sin_addr = *listen;	/* Same IP for user traffic and signalling */
+	addr.sin_port = htons(GTP1C_PORT);
+#if defined(__FreeBSD__) || defined(__APPLE__)
+	addr.sin_len = sizeof(addr);
+#endif
+
+	if (bind((*gsn)->fd1c, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
+		rate_ctr_inc2((*gsn)->ctrg, GSN_CTR_ERR_SOCKET);
+		LOGP_WITH_ADDR(DLGTP, LOGL_ERROR, addr,
+				"bind(fd1c=%d) failed: Error = %s\n",
+				(*gsn)->fd1c, strerror(errno));
+		return -errno;
+	}
+
+	/* Create GTP version 1 user plane socket */
+	if (((*gsn)->fd1u = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
+		rate_ctr_inc2((*gsn)->ctrg, GSN_CTR_ERR_SOCKET);
+		LOGP(DLGTP, LOGL_ERROR,
+		     "GTPv1 user plane socket(domain=%d, type=%d, protocol=%d) failed: Error = %s\n",
+			AF_INET, SOCK_DGRAM, 0, strerror(errno));
+		return -errno;
+	}
+
+	memset(&addr, 0, sizeof(addr));
+	addr.sin_family = AF_INET;
+	addr.sin_addr = *listen;	/* Same IP for user traffic and signalling */
+	addr.sin_port = htons(GTP1U_PORT);
+#if defined(__FreeBSD__) || defined(__APPLE__)
+	addr.sin_len = sizeof(addr);
+#endif
+
+	if (bind((*gsn)->fd1u, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
+		rate_ctr_inc2((*gsn)->ctrg, GSN_CTR_ERR_SOCKET);
+		LOGP_WITH_ADDR(DLGTP, LOGL_ERROR, addr,
+			"bind(fd1u=%d) failed: Error = %s\n",
+			(*gsn)->fd1u, strerror(errno));
+		return -errno;
+	}
+
+	/* Start internal queue timer */
+	gtp_queue_timer_start(*gsn);
+
+	return 0;
+}
+
+int gtp_free(struct gsn_t *gsn)
+{
+
+	/* Cleanup internal queue timer */
+	osmo_timer_del(&gsn->queue_timer);
+
+	/* Clean up retransmit queues */
+	queue_free(gsn->queue_req);
+	queue_free(gsn->queue_resp);
+
+	close(gsn->fd0);
+	close(gsn->fd1c);
+	close(gsn->fd1u);
+
+	rate_ctr_group_free(gsn->ctrg);
+
+	free(gsn);
+	return 0;
+}
+
+/* API: Register create context indication callback */
+int gtp_set_cb_create_context_ind(struct gsn_t *gsn,
+				  int (*cb_create_context_ind) (struct pdp_t *
+								pdp))
+{
+	gsn->cb_create_context_ind = cb_create_context_ind;
+	return 0;
+}
+
+int gtp_retrans(struct gsn_t *gsn)
+{
+	/* dummy API, deprecated. */
+	return 0;
+}
+
+int gtp_retranstimeout(struct gsn_t *gsn, struct timeval *timeout)
+{
+	timeout->tv_sec = 24*60*60;
+	timeout->tv_usec = 0;
+	/* dummy API, deprecated. Return a huge timer to do nothing */
+	return 0;
+}

gtp/gsn.h

@@ -0,0 +1,181 @@
+/*
+ *  OsmoGGSN - Gateway GPRS Support Node
+ *  Copyright (C) 2002, 2003, 2004 Mondru AB.
+ *
+ *  The contents of this file may be used under the terms of the GNU
+ *  General Public License Version 2, provided that the above copyright
+ *  notice and this permission notice is included in all copies or
+ *  substantial portions of the software.
+ *
+ */
+
+#ifndef _GSN_H
+#define _GSN_H
+
+#include <osmocom/core/utils.h>
+#include <osmocom/core/defs.h>
+#include <osmocom/core/timer.h>
+#include <osmocom/core/tdef.h>
+#include <osmocom/core/rate_ctr.h>
+
+#include "pdp.h"
+
+#define GTP_MODE_GGSN 1
+#define GTP_MODE_SGSN 2
+
+#define RESTART_FILE "gsn_restart"
+
+extern struct osmo_tdef gtp_T_defs[];
+
+/* ***********************************************************
+ * Information storage for each gsn instance
+ *
+ * Normally each instance of the application corresponds to
+ * one instance of a gsn.
+ *
+ * In order to avoid global variables in the application, and
+ * also in order to allow several instances of a gsn in the same
+ * application this struct is provided in order to store all
+ * relevant information related to the gsn.
+ *
+ * Note that this does not include information storage for '
+ * each pdp context. This is stored in another struct.
+ *************************************************************/
+
+enum gsn_rate_ctr_keys {
+	GSN_CTR_ERR_SOCKET,
+	GSN_CTR_ERR_READFROM,	/* Number of readfrom errors */
+	GSN_CTR_ERR_SENDTO,	/* Number of sendto errors */
+	GSN_CTR_ERR_QUEUEFULL,	/* Number of times queue was full */
+	GSN_CTR_ERR_SEQ,	/* Number of seq out of range */
+	GSN_CTR_ERR_ADDRESS,	/* GSN address conversion failed */
+	GSN_CTR_ERR_UNKNOWN_PDP,	/* GSN address conversion failed */
+	GSN_CTR_ERR_UNEXPECTED_CAUSE,	/* Unexpected cause value received */
+	GSN_CTR_ERR_OUT_OF_PDP,	/* Out of storage for PDP contexts */
+	GSN_CTR_PKT_EMPTY,		/* Number of empty packets */
+	GSN_CTR_PKT_UNSUP,		/* Number of unsupported version 29.60 11.1.1 */
+	GSN_CTR_PKT_TOOSHORT,	/* Number of too short headers 29.60 11.1.2 */
+	GSN_CTR_PKT_UNKNOWN,	/* Number of unknown messages 29.60 11.1.3 */
+	GSN_CTR_PKT_UNEXPECT,	/* Number of unexpected messages 29.60 11.1.4 */
+	GSN_CTR_PKT_DUPLICATE,	/* Number of duplicate or unsolicited replies */
+	GSN_CTR_PKT_MISSING,	/* Number of missing information field messages */
+	GSN_CTR_PKT_INCORRECT,	/* Number of incorrect information field messages */
+	GSN_CTR_PKT_INVALID,	/* Number of invalid message format messages */
+};
+
+/* 3GPP TS 29.006 14.1, 14,2 */
+enum gtp_gsn_timers {
+	GTP_GSN_TIMER_T3_RESPONSE = 3,
+	GTP_GSN_TIMER_N3_REQUESTS = 1003,
+	GTP_GSN_TIMER_T3_HOLD_RESPONSE = -3,
+};
+
+struct gsn_t {
+	/* Parameters related to the network interface */
+
+	int fd0;		/* GTP0 file descriptor */
+	int fd1c;		/* GTP1 control plane file descriptor */
+	int fd1u;		/* GTP0 user plane file descriptor */
+	int mode;		/* Mode of operation: GGSN or SGSN */
+	struct in_addr gsnc;	/* IP address of this gsn for signalling */
+	struct in_addr gsnu;	/* IP address of this gsn for user traffic */
+
+	/* Parameters related to signalling messages */
+	uint16_t seq_next;	/* Next sequence number to use */
+	int seq_first;		/* First packet in queue (oldest timeout) */
+	int seq_last;		/* Last packet in queue (youngest timeout) */
+
+	unsigned char restart_counter;	/* Increment on restart. Stored on disk */
+	char *statedir;		/* Disk location for permanent storage */
+	void *priv;		/* used by libgtp users to attach their own state) */
+	struct queue_t *queue_req;	/* Request queue */
+	struct queue_t *queue_resp;	/* Response queue */
+
+	struct pdp_t pdpa[PDP_MAX];	/* PDP storage */
+	struct pdp_t *hashtid[PDP_MAX];	/* Hash table for IMSI + NSAPI */
+
+	struct osmo_timer_list queue_timer; /* internal queue_{req,resp} timer */
+
+	/* Call back functions */
+	int (*cb_delete_context) (struct pdp_t *);
+	int (*cb_create_context_ind) (struct pdp_t *);
+	int (*cb_unsup_ind) (struct sockaddr_in * peer);
+	int (*cb_extheader_ind) (struct sockaddr_in * peer);
+	int (*cb_ran_info_relay_ind) (struct sockaddr_in *peer, union gtpie_member **ie);
+	int (*cb_conf) (int type, int cause, struct pdp_t * pdp, void *cbp);
+	int (*cb_data_ind) (struct pdp_t * pdp, void *pack, unsigned len);
+	int (*cb_recovery) (struct sockaddr_in * peer, uint8_t recovery);
+	int (*cb_recovery2) (struct sockaddr_in * peer, struct pdp_t * pdp, uint8_t recovery);
+	int (*cb_recovery3) (struct gsn_t *gsn, struct sockaddr_in *peer, struct pdp_t *pdp, uint8_t recovery);
+
+	/* Counters */
+	struct rate_ctr_group *ctrg;
+
+	/* Timers: */
+	struct osmo_tdef *tdef;
+};
+
+/* External API functions */
+
+extern int gtp_new(struct gsn_t **gsn, char *statedir, struct in_addr *listen,
+		   int mode);
+
+extern int gtp_free(struct gsn_t *gsn);
+
+extern int gtp_newpdp(struct gsn_t *gsn, struct pdp_t **pdp,
+		      uint64_t imsi, uint8_t nsapi) OSMO_DEPRECATED("Use gtp_pdp_newpdp() instead");
+extern int gtp_freepdp(struct gsn_t *gsn, struct pdp_t *pdp);
+extern int gtp_freepdp_teardown(struct gsn_t *gsn, struct pdp_t *pdp);
+
+extern int gtp_create_context_req(struct gsn_t *gsn, struct pdp_t *pdp,
+				  void *cbp);
+
+extern int gtp_set_cb_create_context_ind(struct gsn_t *gsn,
+					 int (*cb_create_context_ind) (struct
+								       pdp_t *
+								       pdp));
+extern int gtp_set_cb_data_ind(struct gsn_t *gsn,
+			       int (*cb_data_ind) (struct pdp_t * pdp,
+						   void *pack, unsigned len));
+extern int gtp_set_cb_delete_context(struct gsn_t *gsn,
+				     int (*cb_delete_context) (struct pdp_t *
+							       pdp));
+/*extern int gtp_set_cb_create_context(struct gsn_t *gsn,
+  int (*cb_create_context) (struct pdp_t* pdp)); */
+
+extern int gtp_set_cb_unsup_ind(struct gsn_t *gsn,
+				int (*cb) (struct sockaddr_in * peer));
+
+extern int gtp_set_cb_extheader_ind(struct gsn_t *gsn,
+				    int (*cb) (struct sockaddr_in * peer));
+
+extern int gtp_set_cb_ran_info_relay_ind(struct gsn_t *gsn,
+				    int (*cb) (struct sockaddr_in * peer, union gtpie_member **ie));
+
+extern int gtp_set_cb_conf(struct gsn_t *gsn,
+			   int (*cb) (int type, int cause, struct pdp_t * pdp,
+				      void *cbp));
+
+int gtp_set_cb_recovery(struct gsn_t *gsn,
+			int (*cb) (struct sockaddr_in * peer,
+				   uint8_t recovery))
+	OSMO_DEPRECATED("Use gtp_set_cb_recovery2() instead, to obtain pdp ctx originating the recovery");
+int gtp_set_cb_recovery2(struct gsn_t *gsn,
+			int (*cb) (struct sockaddr_in * peer,
+				   struct pdp_t * pdp,
+				   uint8_t recovery))
+	OSMO_DEPRECATED("Use gtp_set_cb_recovery3() instead, to obtain gsn handling the recovery");
+int gtp_set_cb_recovery3(struct gsn_t *gsn,
+			int (*cb) (struct gsn_t * gsn, struct sockaddr_in * peer,
+				   struct pdp_t * pdp,
+				   uint8_t recovery));
+void gtp_clear_queues(struct gsn_t *gsn);
+extern int gtp_fd(struct gsn_t *gsn);
+
+extern int gtp_retrans(struct gsn_t *gsn) OSMO_DEPRECATED("This API is a no-op, libgtp already does the job internally");
+extern int gtp_retranstimeout(struct gsn_t *gsn, struct timeval *timeout) OSMO_DEPRECATED("This API is a no-op and will return a 1 day timeout");
+
+/* Internal APIs: */
+void gtp_queue_timer_start(struct gsn_t *gsn);
+
+#endif /* !_GSN_H */

gtp/gtp.h

@@ -13,14 +13,10 @@
 #define _GTP_H
 
 #include <osmocom/core/utils.h>
-#include <osmocom/core/defs.h>
-#include <osmocom/core/timer.h>
 
 #include "gtpie.h"
 #include "pdp.h"
-
-#define GTP_MODE_GGSN 1
-#define GTP_MODE_SGSN 2
+#include "gsn.h"
 
 #define GTP0_PORT	3386
 #define GTP1C_PORT	2123
@@ -32,12 +28,10 @@
 #define GTP1_HEADER_SIZE_SHORT  8
 #define GTP1_HEADER_SIZE_LONG  12
 
+#define NAMESIZE 1024
 #define SYSLOG_PRINTSIZE 255
 #define ERRMSG_SIZE 255
 
-#define RESTART_FILE "gsn_restart"
-#define NAMESIZE 1024
-
 /* GTP version 1 extension header type definitions. */
 #define GTP_EXT_PDCP_PDU    0xC0	/* PDCP PDU Number */
 
@@ -232,105 +226,13 @@ union gtp_packet {
 	struct gtp1_packet_long gtp1l;
 } __attribute__ ((packed));
 
-/* ***********************************************************
- * Information storage for each gsn instance
- *
- * Normally each instance of the application corresponds to
- * one instance of a gsn.
- *
- * In order to avoid global variables in the application, and
- * also in order to allow several instances of a gsn in the same
- * application this struct is provided in order to store all
- * relevant information related to the gsn.
- *
- * Note that this does not include information storage for '
- * each pdp context. This is stored in another struct.
- *************************************************************/
-
-struct gsn_t {
-	/* Parameters related to the network interface */
-
-	int fd0;		/* GTP0 file descriptor */
-	int fd1c;		/* GTP1 control plane file descriptor */
-	int fd1u;		/* GTP0 user plane file descriptor */
-	int mode;		/* Mode of operation: GGSN or SGSN */
-	struct in_addr gsnc;	/* IP address of this gsn for signalling */
-	struct in_addr gsnu;	/* IP address of this gsn for user traffic */
-
-	/* Parameters related to signalling messages */
-	uint16_t seq_next;	/* Next sequence number to use */
-	int seq_first;		/* First packet in queue (oldest timeout) */
-	int seq_last;		/* Last packet in queue (youngest timeout) */
-
-	unsigned char restart_counter;	/* Increment on restart. Stored on disk */
-	char *statedir;		/* Disk location for permanent storage */
-	void *priv;		/* used by libgtp users to attach their own state) */
-	struct queue_t *queue_req;	/* Request queue */
-	struct queue_t *queue_resp;	/* Response queue */
-
-	struct pdp_t pdpa[PDP_MAX];	/* PDP storage */
-	struct pdp_t *hashtid[PDP_MAX];	/* Hash table for IMSI + NSAPI */
-
-	struct osmo_timer_list queue_timer; /* internal queue_{req,resp} timer */
-
-	/* Call back functions */
-	int (*cb_delete_context) (struct pdp_t *);
-	int (*cb_create_context_ind) (struct pdp_t *);
-	int (*cb_unsup_ind) (struct sockaddr_in * peer);
-	int (*cb_extheader_ind) (struct sockaddr_in * peer);
-	int (*cb_ran_info_relay_ind) (struct sockaddr_in *peer, union gtpie_member **ie);
-	int (*cb_conf) (int type, int cause, struct pdp_t * pdp, void *cbp);
-	int (*cb_data_ind) (struct pdp_t * pdp, void *pack, unsigned len);
-	int (*cb_recovery) (struct sockaddr_in * peer, uint8_t recovery);
-	int (*cb_recovery2) (struct sockaddr_in * peer, struct pdp_t * pdp, uint8_t recovery);
-	int (*cb_recovery3) (struct gsn_t *gsn, struct sockaddr_in *peer, struct pdp_t *pdp, uint8_t recovery);
-
-	/* Counters */
-
-	uint64_t err_socket;	/* Number of socket errors */
-	uint64_t err_readfrom;	/* Number of readfrom errors */
-	uint64_t err_sendto;	/* Number of sendto errors */
-	uint64_t err_memcpy;	/* Number of memcpy */
-	uint64_t err_queuefull;	/* Number of times queue was full */
-	uint64_t err_seq;	/* Number of seq out of range */
-	uint64_t err_address;	/* GSN address conversion failed */
-	uint64_t err_unknownpdp;	/* GSN address conversion failed */
-	uint64_t err_unknowntid;	/* Application supplied unknown imsi+nsapi */
-	uint64_t err_cause;	/* Unexpected cause value received */
-	uint64_t err_outofpdp;	/* Out of storage for PDP contexts */
-
-	uint64_t empty;		/* Number of empty packets */
-	uint64_t unsup;		/* Number of unsupported version 29.60 11.1.1 */
-	uint64_t tooshort;	/* Number of too short headers 29.60 11.1.2 */
-	uint64_t unknown;	/* Number of unknown messages 29.60 11.1.3 */
-	uint64_t unexpect;	/* Number of unexpected messages 29.60 11.1.4 */
-	uint64_t duplicate;	/* Number of duplicate or unsolicited replies */
-	uint64_t missing;	/* Number of missing information field messages */
-	uint64_t incorrect;	/* Number of incorrect information field messages */
-	uint64_t invalid;	/* Number of invalid message format messages */
-};
-
 /* External API functions */
 
 extern const char *gtp_version();
-extern int gtp_new(struct gsn_t **gsn, char *statedir, struct in_addr *listen,
-		   int mode);
-
-extern int gtp_free(struct gsn_t *gsn);
-
-extern int gtp_newpdp(struct gsn_t *gsn, struct pdp_t **pdp,
-		      uint64_t imsi, uint8_t nsapi) OSMO_DEPRECATED("Use gtp_pdp_newpdp() instead");
-extern int gtp_freepdp(struct gsn_t *gsn, struct pdp_t *pdp);
-extern int gtp_freepdp_teardown(struct gsn_t *gsn, struct pdp_t *pdp);
 
 extern int gtp_create_context_req(struct gsn_t *gsn, struct pdp_t *pdp,
 				  void *cbp);
 
-extern int gtp_set_cb_create_context_ind(struct gsn_t *gsn,
-					 int (*cb_create_context_ind) (struct
-								       pdp_t *
-								       pdp));
-
 extern int gtp_create_context_resp(struct gsn_t *gsn, struct pdp_t *pdp,
 				   int cause);
 
@@ -351,53 +253,10 @@ extern int gtp_ran_info_relay_req(struct gsn_t *gsn, const struct sockaddr_in *p
 				  const uint8_t *rim_route_addr, size_t rim_route_addr_len,
 				  uint8_t rim_route_addr_discr);
 
-extern int gtp_set_cb_data_ind(struct gsn_t *gsn,
-			       int (*cb_data_ind) (struct pdp_t * pdp,
-						   void *pack, unsigned len));
-
-extern int gtp_fd(struct gsn_t *gsn);
 extern int gtp_decaps0(struct gsn_t *gsn);
 extern int gtp_decaps1c(struct gsn_t *gsn);
 extern int gtp_decaps1u(struct gsn_t *gsn);
-extern int gtp_retrans(struct gsn_t *gsn) OSMO_DEPRECATED("This API is a no-op, libgtp already does the job internally");
-extern int gtp_retranstimeout(struct gsn_t *gsn, struct timeval *timeout) OSMO_DEPRECATED("This API is a no-op and will return a 1 day timeout");
-
-extern int gtp_set_cb_delete_context(struct gsn_t *gsn,
-				     int (*cb_delete_context) (struct pdp_t *
-							       pdp));
-/*extern int gtp_set_cb_create_context(struct gsn_t *gsn,
-  int (*cb_create_context) (struct pdp_t* pdp)); */
-
-extern int gtp_set_cb_unsup_ind(struct gsn_t *gsn,
-				int (*cb) (struct sockaddr_in * peer));
-
-extern int gtp_set_cb_extheader_ind(struct gsn_t *gsn,
-				    int (*cb) (struct sockaddr_in * peer));
-
-extern int gtp_set_cb_ran_info_relay_ind(struct gsn_t *gsn,
-				    int (*cb) (struct sockaddr_in * peer, union gtpie_member **ie));
-
-extern int gtp_set_cb_conf(struct gsn_t *gsn,
-			   int (*cb) (int type, int cause, struct pdp_t * pdp,
-				      void *cbp));
-
-int gtp_set_cb_recovery(struct gsn_t *gsn,
-			int (*cb) (struct sockaddr_in * peer,
-				   uint8_t recovery))
-	OSMO_DEPRECATED("Use gtp_set_cb_recovery2() instead, to obtain pdp ctx originating the recovery");
-int gtp_set_cb_recovery2(struct gsn_t *gsn,
-			int (*cb) (struct sockaddr_in * peer,
-				   struct pdp_t * pdp,
-				   uint8_t recovery))
-	OSMO_DEPRECATED("Use gtp_set_cb_recovery3() instead, to obtain gsn handling the recovery");;
-int gtp_set_cb_recovery3(struct gsn_t *gsn,
-			int (*cb) (struct gsn_t * gsn, struct sockaddr_in * peer,
-				   struct pdp_t * pdp,
-				   uint8_t recovery));
-
-void gtp_clear_queues(struct gsn_t *gsn);
-
-/* Internal functions (not part of the API */
+/* Internal functions (not part of the API) */
 
 extern int gtp_echo_req(struct gsn_t *gsn, int version, void *cbp,
 			struct in_addr *inetaddrs);

gtp/queue.h

@@ -23,7 +23,7 @@
 
 #define QUEUE_DEBUG 0		/* Print debug information */
 
-#define QUEUE_SIZE 1024		/* Size of retransmission queue */
+#define QUEUE_SIZE (PDP_MAX*2)	/* Size of retransmission queue */
 #define QUEUE_HASH_SIZE 65536	/* Size of hash table (2^16) */
 
 struct qmsg_t {			/* Holder for queued packets */

lib/Makefile.am

@@ -2,7 +2,7 @@ noinst_LIBRARIES = libmisc.a
 
 noinst_HEADERS = gnugetopt.h ippool.h lookup.h syserr.h tun.h in46_addr.h netdev.h gtp-kernel.h netns.h util.h icmpv6.h checksum.h
 
-AM_CFLAGS = -O2 -fno-builtin -Wall -DSBINDIR='"$(sbindir)"' -ggdb $(LIBOSMOCORE_CFLAGS)
+AM_CFLAGS = -fno-builtin -Wall -DSBINDIR='"$(sbindir)"' $(LIBOSMOCORE_CFLAGS)
 
 libmisc_a_SOURCES = getopt1.c getopt.c ippool.c lookup.c tun.c debug.c in46_addr.c netdev.c netns.c util.c icmpv6.c checksum.c
 

lib/icmpv6.h

@@ -44,10 +44,9 @@ struct icmpv6_radv_hdr {
 	uint8_t res:6,
 		m:1,
 		o:1;
-#else
-	uint8_t m:1,
-		o:1,
-		res:6;
+#elif OSMO_IS_BIG_ENDIAN
+/* auto-generated from the little endian part above (libosmocore/contrib/struct_endianness.py) */
+	uint8_t o:1, m:1, res:6;
 #endif
 	uint16_t router_lifetime;
 	uint32_t reachable_time;
@@ -72,10 +71,9 @@ struct icmpv6_opt_prefix {
 	uint8_t res:6,
 		a:1,
 		l:1;
-#else
-	uint8_t l:1,
-		a:1,
-		res:6;
+#elif OSMO_IS_BIG_ENDIAN
+/* auto-generated from the little endian part above (libosmocore/contrib/struct_endianness.py) */
+	uint8_t l:1, a:1, res:6;
 #endif
 	uint32_t valid_lifetime;
 	uint32_t preferred_lifetime;

lib/tun.c

@@ -318,7 +318,14 @@ int tun_decaps(struct tun_t *this)
 
 int tun_encaps(struct tun_t *tun, void *pack, unsigned len)
 {
-	return write(tun->fd, pack, len);
+	int rc;
+	rc = write(tun->fd, pack, len);
+	if (rc < 0) {
+		SYS_ERR(DTUN, LOGL_ERROR, errno, "TUN(%s): write() failed", tun->devname);
+	} else if (rc < len) {
+		LOGTUN(LOGL_ERROR, tun, "short write() %d < %u\n", rc, len);
+	}
+	return rc;
 }
 
 int tun_runscript(struct tun_t *tun, char *script)

lib/tun.h

@@ -59,4 +59,7 @@ extern int tun_runscript(struct tun_t *tun, char *script);
 int tun_ip_local_get(const struct tun_t *tun, struct in46_prefix *prefix_list,
 		     size_t prefix_size, int flags);
 
+#define LOGTUN(level, tun, fmt, args...) \
+	LOGP(DTUN, level, "TUN(%s): " fmt, (tun)->devname, ## args)
+
 #endif /* !_TUN_H */

sgsnemu/Makefile.am

@@ -2,7 +2,7 @@ bin_PROGRAMS = sgsnemu
 
 AM_LDFLAGS = @EXEC_LDFLAGS@
 
-AM_CFLAGS = -O2 -D_GNU_SOURCE -fno-builtin -Wall -DSBINDIR='"$(sbindir)"' -ggdb $(LIBOSMOCORE_CFLAGS)
+AM_CFLAGS = -D_GNU_SOURCE -fno-builtin -Wall -DSBINDIR='"$(sbindir)"' $(LIBOSMOCORE_CFLAGS)
 
 sgsnemu_LDADD = @EXEC_LDADD@ -lgtp -L../gtp ../lib/libmisc.a $(LIBOSMOCORE_LIBS)
 

tests/gtp/Makefile.am

@@ -1,11 +1,12 @@
-AM_CFLAGS = -Wall -I$(top_srcdir)/include $(LIBOSMOCORE_CFLAGS) -g
+AM_CFLAGS = -Wall -I$(top_srcdir)/include $(LIBOSMOCORE_CFLAGS)
+AM_LDFLAGS = -no-install
 
 EXTRA_DIST = \
 	gtpie_test.ok \
 	queue_test.ok \
 	$(NULL)
 
-noinst_PROGRAMS = \
+check_PROGRAMS = \
 	gtpie_test \
 	queue_test \
 	$(NULL)

tests/lib/Makefile.am

@@ -1,4 +1,5 @@
-AM_CFLAGS = -Wall -I$(top_srcdir)/include $(LIBOSMOCORE_CFLAGS) -g
+AM_CFLAGS = -Wall -I$(top_srcdir)/include $(LIBOSMOCORE_CFLAGS)
+AM_LDFLAGS = -no-install
 
 EXTRA_DIST = ippool_test.ok \
 	     ippool_test.err \
@@ -7,7 +8,7 @@ EXTRA_DIST = ippool_test.ok \
 	     in46a_test.ok \
 	     in46a_v6_test.ok
 
-noinst_PROGRAMS = ippool_test in46a_test
+check_PROGRAMS = ippool_test in46a_test
 
 ippool_test_SOURCES = \
 	ippool_test.c \

tests/lib/in46a_test.c

@@ -146,7 +146,7 @@ static void test_in46a_to_eua(void)
 
 static void test_in46a_from_eua(void)
 {
-	struct in46_addr ia;
+	struct in46_addr ia[2];
 	struct ul66_t eua;
 	const uint8_t v4_unspec[] = { PDP_EUA_ORG_IETF, PDP_EUA_TYPE_v4 };
 	const uint8_t v4_spec[] = { PDP_EUA_ORG_IETF, PDP_EUA_TYPE_v4, 1,2,3,4 };
@@ -155,35 +155,35 @@ static void test_in46a_from_eua(void)
 	printf("Testing in46a_from_eua() with IPv4 addresses\n");
 
 	/* default: v4 unspec */
-	OSMO_ASSERT(in46a_from_eua(&eua, &ia) == 1);
-	OSMO_ASSERT(ia.len == 4);
-	OSMO_ASSERT(ia.v4.s_addr == 0);
+	OSMO_ASSERT(in46a_from_eua(&eua, ia) == 1);
+	OSMO_ASSERT(ia[0].len == 4);
+	OSMO_ASSERT(ia[0].v4.s_addr == 0);
 
 	/* invalid */
 	eua.v[0] = 0x23;
 	eua.v[1] = PDP_EUA_TYPE_v4;
 	eua.l = 6;
-	OSMO_ASSERT(in46a_from_eua(&eua, &ia) < 0);
+	OSMO_ASSERT(in46a_from_eua(&eua, ia) < 0);
 
 	/* invalid */
 	eua.v[0] = PDP_EUA_ORG_IETF;
 	eua.v[1] = 0x23;
 	eua.l = 6;
-	OSMO_ASSERT(in46a_from_eua(&eua, &ia) < 0);
+	OSMO_ASSERT(in46a_from_eua(&eua, ia) < 0);
 
 	/* unspecified V4 */
 	memcpy(eua.v, v4_unspec, sizeof(v4_unspec));
 	eua.l = sizeof(v4_unspec);
-	OSMO_ASSERT(in46a_from_eua(&eua, &ia) == 1);
-	OSMO_ASSERT(ia.len == 4);
-	OSMO_ASSERT(ia.v4.s_addr == 0);
+	OSMO_ASSERT(in46a_from_eua(&eua, ia) == 1);
+	OSMO_ASSERT(ia[0].len == 4);
+	OSMO_ASSERT(ia[0].v4.s_addr == 0);
 
 	/* specified V4 */
 	memcpy(eua.v, v4_spec, sizeof(v4_spec));
 	eua.l = sizeof(v4_spec);
-	OSMO_ASSERT(in46a_from_eua(&eua, &ia) == 1);
-	OSMO_ASSERT(ia.len == 4);
-	OSMO_ASSERT(ia.v4.s_addr == htonl(0x01020304));
+	OSMO_ASSERT(in46a_from_eua(&eua, ia) == 1);
+	OSMO_ASSERT(ia[0].len == 4);
+	OSMO_ASSERT(ia[0].v4.s_addr == htonl(0x01020304));
 }
 
 static void test_in46a_netmasklen(void)
@@ -318,7 +318,7 @@ static void test_in46a_to_eua_v4v6() {
 
 static void test_in46a_from_eua_v6(void)
 {
-	struct in46_addr ia;
+	struct in46_addr ia[2];
 	struct ul66_t eua;
 	const uint8_t v6_unspec[] = { PDP_EUA_ORG_IETF, PDP_EUA_TYPE_v6 };
 	const uint8_t v6_spec[] = { PDP_EUA_ORG_IETF, PDP_EUA_TYPE_v6,
@@ -331,16 +331,16 @@ static void test_in46a_from_eua_v6(void)
 	/* unspecified V6 */
 	memcpy(eua.v, v6_unspec, sizeof(v6_unspec));
 	eua.l = sizeof(v6_unspec);
-	OSMO_ASSERT(in46a_from_eua(&eua, &ia) == 1);
-	OSMO_ASSERT(ia.len == 16);
-	OSMO_ASSERT(IN6_IS_ADDR_UNSPECIFIED(&ia.v6));
+	OSMO_ASSERT(in46a_from_eua(&eua, ia) == 1);
+	OSMO_ASSERT(ia[0].len == 16);
+	OSMO_ASSERT(IN6_IS_ADDR_UNSPECIFIED(&ia[0].v6));
 
 	/* specified V6 */
 	memcpy(eua.v, v6_spec, sizeof(v6_spec));
 	eua.l = sizeof(v6_spec);
-	OSMO_ASSERT(in46a_from_eua(&eua, &ia) == 1);
-	OSMO_ASSERT(ia.len == 16);
-	OSMO_ASSERT(!memcmp(&ia.v6, v6_spec+2, ia.len));
+	OSMO_ASSERT(in46a_from_eua(&eua, ia) == 1);
+	OSMO_ASSERT(ia[0].len == 16);
+	OSMO_ASSERT(!memcmp(&ia[0].v6, v6_spec+2, ia[0].len));
 }
 
 static void test_in46a_from_eua_v4v6(void) {

utils/Makefile.am

@@ -0,0 +1,3 @@
+bin_PROGRAMS = gtp-echo-responder
+
+gtp_echo_responder_SOURCES = gtp_echo_responder.c

utils/gtp_echo_responder.c

@@ -0,0 +1,470 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2021 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * Author: Pau Espin Pedrol <pespin@sysmocom.de>
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+/* For more info see:
+ * 3GPP TS 29.060 (GTPv1 and GTPv0)
+ * 3GPP TS 29.274 (GTPv2C)
+ */
+
+#include "../config.h"
+
+#include <stdlib.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <inttypes.h>
+#include <unistd.h>
+#include <limits.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <getopt.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <sys/select.h>
+#include <sys/socket.h>
+
+#define GTP1C_PORT	2123
+#define GTP_MSGTYPE_ECHO_REQ	1
+#define GTP_MSGTYPE_ECHO_RSP	2
+#define GTP1C_IE_RECOVERY 14
+#define GTP2C_IE_RECOVERY 3
+#define GTP2C_IE_NODE_FEATURES 152
+
+struct gtp1_hdr {
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	uint8_t pn:1, s:1, e:1, spare:1, pt:1, version:3;
+#else
+	uint8_t version:3, pt:1, spare:1, e:1, s:1, pn:1;
+#endif
+	uint8_t type;
+	uint16_t length;
+	uint32_t tei;
+	uint16_t seq;
+	uint8_t npdu;
+	uint8_t next;
+} __attribute__((packed));
+
+struct gtp2_hdr {
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	uint8_t reserved:3, t:1, p:1, version:3;
+#else
+	uint8_t version:3, p:1, t:1, reserved:1;
+#endif
+	uint8_t type;
+	uint16_t length;
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	uint32_t reserved2:8, seq:24;
+#else
+	uint8_t seq:24, reserved2:1;
+#endif
+} __attribute__((packed));
+
+struct gtp_echo_resp_state {
+	struct {
+		char laddr[INET6_ADDRSTRLEN];
+		uint8_t recovery_ctr;
+		uint8_t node_features;
+	} cfg;
+	struct sockaddr_storage laddr_gtpc;
+	int fd_gtpc;
+};
+
+struct gtp_echo_resp_state *g_st;
+
+static void print_usage(void)
+{
+	printf("Usage: gtp-echo-responder [-h] [-V] [-l listen_addr]\n");
+}
+
+static void print_help(void)
+{
+	printf("  Some useful help...\n"
+	       "  -h --help		This help text\n"
+	       "  -V --version		Print the version of gtp-echo-responder\n"
+	       "  -l --listen-addr	Listend address for GTPCv1 and GTPCv2\n"
+	       "  -R --recovery-counter GTP Recovery Counter to transmit in GTP Echo Response message\n"
+	       "  -n --node-features	GTPCv2 Node Features bitmask to transmit in GTP Echo Response message\n"
+	       );
+}
+
+static void print_version(void)
+{
+	printf("gtp-echo-responder version %s\n", PACKAGE_VERSION);
+}
+
+static uint8_t parse_node_features_mask(const char *arg)
+{
+	unsigned long res;
+	char *end;
+	errno = 0;
+
+	res = strtoul(arg, &end, 0);
+	if ((errno == ERANGE && res == ULONG_MAX) || (errno && !res) ||
+	    arg == end || *end != '\0') {
+		fprintf(stderr, "Failed parsing Node Features bitmask: '%s'\n", arg);
+		exit(1);
+	}
+	if (res > 0xff) {
+		fprintf(stderr, "Failed parsing Node Features bitmask: '%s' > 0xFF\n", arg);
+		exit(1);
+	}
+	return (uint8_t)res;
+}
+static void handle_options(int argc, char **argv)
+{
+	while (1) {
+		int option_index = 0, c;
+		static struct option long_options[] = {
+			{ "help", 0, 0, 'h' },
+			{ "version", 0, 0, 'V' },
+			{ "listen-addr", 1, 0, 'l'},
+			{ "recovery-counter", 1, 0, 'R'},
+			{ "node-features", 1, 0, 'N'},
+			{ 0, 0, 0, 0 }
+		};
+
+		c = getopt_long(argc, argv, "hVl:R:N:", long_options, &option_index);
+		if (c == -1)
+			break;
+
+		switch (c) {
+		case 'h':
+			print_usage();
+			print_help();
+			exit(0);
+		case 'V':
+			print_version();
+			exit(0);
+			break;
+		case 'l':
+			strncpy(&g_st->cfg.laddr[0], optarg, sizeof(g_st->cfg.laddr));
+			g_st->cfg.laddr[sizeof(g_st->cfg.laddr) - 1] = '\0';
+			break;
+		case 'R':
+			g_st->cfg.recovery_ctr = (uint8_t)atoi(optarg);
+			break;
+		case 'N':
+			g_st->cfg.node_features = parse_node_features_mask(optarg);
+			break;
+		}
+	}
+}
+
+static int init_socket(void)
+{
+	struct in_addr addr;
+	struct in6_addr addr6;
+	struct sockaddr_in *saddr;
+	struct sockaddr_in6 *saddr6;
+	int family;
+
+	if (inet_pton(AF_INET6, g_st->cfg.laddr, &addr6) == 1) {
+		family = AF_INET6;
+		saddr6 = (struct sockaddr_in6 *)&g_st->laddr_gtpc;
+		saddr6->sin6_family = family;
+		saddr6->sin6_port = htons(GTP1C_PORT);
+		memcpy(&saddr6->sin6_addr, &addr6, sizeof(addr6));
+	} else if (inet_pton(AF_INET, g_st->cfg.laddr, &addr) == 1) {
+		family = AF_INET;
+		saddr = (struct sockaddr_in *)&g_st->laddr_gtpc;
+		saddr->sin_family = family;
+		saddr->sin_port = htons(GTP1C_PORT);
+		memcpy(&saddr->sin_addr, &addr, sizeof(addr));
+	} else {
+		fprintf(stderr, "Failed parsing address %s\n", g_st->cfg.laddr);
+		return -1;
+	}
+
+	if ((g_st->fd_gtpc = socket(family, SOCK_DGRAM, 0)) < 0) {
+		fprintf(stderr, "socket() failed: %s\n", strerror(errno));
+		return -2;
+	}
+
+	if (bind(g_st->fd_gtpc, (struct sockaddr *)&g_st->laddr_gtpc, sizeof(g_st->laddr_gtpc)) < 0) {
+		fprintf(stderr, "bind() failed: %s\n", strerror(errno));
+		return -3;
+	}
+
+	return 0;
+}
+
+static const char *sockaddr2str(const struct sockaddr *saddr)
+{
+	static char _rem_addr_str[INET6_ADDRSTRLEN];
+	struct sockaddr_in *saddr4;
+	struct sockaddr_in6 *saddr6;
+
+	switch (saddr->sa_family) {
+	case AF_INET6:
+		saddr6 = (struct sockaddr_in6 *)saddr;
+		if (!inet_ntop(saddr6->sin6_family, &saddr6->sin6_addr, _rem_addr_str, sizeof(_rem_addr_str)))
+			strcpy(_rem_addr_str, "unknown");
+		return _rem_addr_str;
+	case AF_INET:
+		saddr4 = (struct sockaddr_in *)saddr;
+		if (!inet_ntop(saddr4->sin_family, &saddr4->sin_addr, _rem_addr_str, sizeof(_rem_addr_str)))
+			strcpy(_rem_addr_str, "unknown");
+		return _rem_addr_str;
+	default:
+		strcpy(_rem_addr_str, "unknown-family");
+		return _rem_addr_str;
+	}
+}
+
+static int write_cb(int fd, const uint8_t *buf, size_t buf_len, const struct sockaddr *rem_saddr)
+{
+	ssize_t rc;
+
+	rc = sendto(fd, buf, buf_len, 0, rem_saddr, sizeof(struct sockaddr_storage));
+	if (rc < 0) {
+		fprintf(stderr, "sendto() failed: %s\n", strerror(errno));
+		return -1;
+	}
+	if (rc != buf_len) {
+		fprintf(stderr, "sendto() short write: %zd vs exp %zu\n", rc, buf_len);
+		return -1;
+	}
+	return 0;
+}
+
+static int gen_gtpc1_echo_rsp(uint8_t *buf, struct gtp1_hdr *echo_req)
+{
+	int offset = 0;
+	struct gtp1_hdr *echo_rsp = (struct gtp1_hdr *)buf;
+	unsigned exp_hdr_len = (echo_req->s || echo_req->pn || echo_req->e) ? 12 : 8;
+
+	memcpy(echo_rsp, echo_req, exp_hdr_len);
+	echo_rsp->type = GTP_MSGTYPE_ECHO_RSP;
+	offset = exp_hdr_len;
+	buf[offset++] = GTP1C_IE_RECOVERY;
+	buf[offset++] = g_st->cfg.recovery_ctr;
+
+	/* Update Length */
+	echo_rsp->length = htons(offset - 8);
+	return offset;
+}
+
+static int gen_gtpc2_echo_rsp(uint8_t *buf, struct gtp2_hdr *echo_req)
+{
+	int offset = 0;
+	struct gtp1_hdr *echo_rsp = (struct gtp1_hdr *)buf;
+	unsigned exp_hdr_len = 8;
+
+	memcpy(echo_rsp, echo_req, exp_hdr_len);
+	echo_rsp->type = GTP_MSGTYPE_ECHO_RSP;
+	offset = exp_hdr_len;
+
+	/* 3GPP TS 29.274 sec 8.5 Recovery (Restart Counter) */
+	buf[offset++] = GTP2C_IE_RECOVERY;
+	buf[offset++] = 0; /* IE Length (high) */
+	buf[offset++] = 1; /* IE Length (low) */
+	buf[offset++] = 0; /* Spare=0 | Instance=0 (Table 7.1.1-1) */
+	buf[offset++] = g_st->cfg.recovery_ctr;
+
+	/* 3GPP TS 29.274 sec 8.83 Node Features */
+	if (g_st->cfg.node_features > 0) {
+		buf[offset++] = GTP2C_IE_NODE_FEATURES;
+		buf[offset++] = 0; /* IE Length (high) */
+		buf[offset++] = 1; /* IE Length (low) */
+		buf[offset++] = 0; /* Spare=0 | Instance=0 (Table 7.1.1-1) */
+		buf[offset++] = g_st->cfg.node_features;
+	}
+
+	/* Update Length */
+	echo_rsp->length = htons(offset - 4);
+	return offset;
+}
+
+static int rx_gtpc1_echo_req(struct gtp1_hdr *echo_req, unsigned buf_len, const struct sockaddr *rem_saddr)
+{
+	int rc;
+	const size_t tx_buf_len = buf_len + 128; /* Leave some extra room */
+	uint8_t *tx_buf = alloca(tx_buf_len);
+
+	printf("Rx GTPCv1_ECHO_REQ from %s, Tx GTPCv1_ECHO_RSP\n", sockaddr2str(rem_saddr));
+
+	memset(tx_buf, 0, tx_buf_len);
+	rc = gen_gtpc1_echo_rsp(tx_buf, echo_req);
+	return write_cb(g_st->fd_gtpc, tx_buf, rc, rem_saddr);
+}
+
+static int rx_gtpc1(struct gtp1_hdr *hdr, unsigned buf_len, const struct sockaddr *rem_saddr)
+{
+	unsigned exp_hdr_len = (hdr->s || hdr->pn || hdr->e) ? 12 : 8;
+	unsigned pdu_len;
+
+	if (buf_len < exp_hdr_len) {
+		fprintf(stderr, "GTPCv1 packet size smaller than header! %u < exp %u\n", buf_len, exp_hdr_len);
+		return -1;
+	}
+
+	pdu_len = ntohs(hdr->length);
+	if (buf_len < 8 + pdu_len) {
+		fprintf(stderr, "GTPCv1 packet size smaller than announced! %u < exp %u\n", buf_len, 8 + pdu_len);
+		return -1;
+	}
+
+	if (hdr->pt != 1) {
+		fprintf(stderr, "GTPCv1 Protocol Type GTP' not supported!\n");
+		return -1;
+	}
+
+	switch (hdr->type) {
+	case GTP_MSGTYPE_ECHO_REQ:
+		return rx_gtpc1_echo_req(hdr, buf_len, rem_saddr);
+	default:
+		fprintf(stderr, "Silently ignoring unexpected packet of type %u\n", hdr->type);
+		return 0;
+	}
+}
+
+static int rx_gtpc2_echo_req(struct gtp2_hdr *echo_req, unsigned buf_len, const struct sockaddr *rem_saddr)
+{
+	int rc;
+	const size_t tx_buf_len = buf_len + 128; /* Leave some extra room */
+	uint8_t *tx_buf = alloca(tx_buf_len);
+
+	if (echo_req->t) {
+		fprintf(stderr, "GTPCv2 ECHO message should contain T=0!\n");
+		return -1;
+	}
+
+	printf("Rx GTPCv2_ECHO_REQ from %s, Tx GTPCv2_ECHO_RSP\n", sockaddr2str(rem_saddr));
+
+	memset(tx_buf, 0, tx_buf_len);
+	rc = gen_gtpc2_echo_rsp(tx_buf, echo_req);
+	return write_cb(g_st->fd_gtpc, tx_buf, rc, rem_saddr);
+}
+
+static int rx_gtpc2(struct gtp2_hdr *hdr, unsigned buf_len, const struct sockaddr *rem_saddr)
+{
+	unsigned exp_hdr_len = hdr->t ? 12 : 8;
+	unsigned pdu_len;
+
+	if (hdr->p) {
+		fprintf(stderr, "GTPCv2 piggybacked message not supported!\n");
+		return -1;
+	}
+
+	if (buf_len < exp_hdr_len) {
+		fprintf(stderr, "GTPCv2 packet size smaller than header! %u < exp %u\n", buf_len, exp_hdr_len);
+		return -1;
+	}
+
+	pdu_len = ntohs(hdr->length);
+	/* 3GPP TS 29.274 sec 5.5.1: "Octets 3 to 4 represent the Message Length
+	 * field. This field shall indicate the length of the message in octets
+	 * excluding the mandatory part of the GTP-C header (the first 4
+	 * octets). The TEID (if present) and the Sequence  Number shall be
+	 * included in the length count" */
+	if (buf_len < 4 + pdu_len) {
+		fprintf(stderr, "GTPCv2 packet size smaller than announced! %u < exp %u\n", buf_len, 4 + pdu_len);
+		return -1;
+	}
+
+	switch (hdr->type) {
+	case GTP_MSGTYPE_ECHO_REQ:
+		return rx_gtpc2_echo_req(hdr, buf_len, rem_saddr);
+	default:
+		fprintf(stderr, "Silently ignoring unexpected packet of type %u\n", hdr->type);
+		return 0;
+	}
+}
+
+static int read_cb(int fd)
+{
+	ssize_t sz;
+	uint8_t buf[4096];
+	struct sockaddr_storage rem_saddr;
+	socklen_t rem_saddr_len = sizeof(rem_saddr);
+	struct gtp1_hdr *hdr1;
+
+	if ((sz = recvfrom(fd, buf, sizeof(buf), 0, (struct sockaddr *)&rem_saddr, &rem_saddr_len)) < 0) {
+		fprintf(stderr, "recvfrom() failed: %s\n", strerror(errno));
+		return -1;
+	}
+	if (sz == 0) {
+		fprintf(stderr, "recvfrom() read zero bytes!\n");
+		return -1;
+	}
+
+	hdr1 = (struct gtp1_hdr *)&buf[0];
+	switch (hdr1->version) {
+	case 1:
+		return rx_gtpc1(hdr1, sz, (const struct sockaddr *)&rem_saddr);
+	case 2:
+		return rx_gtpc2((struct gtp2_hdr *)&buf[0], sz, (const struct sockaddr *)&rem_saddr);
+	default:
+		fprintf(stderr, "Rx GTPv%u: not supported (flags=0x%x)\n", hdr1->version, buf[0]);
+		return -1;
+	}
+}
+
+static int loop(void)
+{
+	int rc;
+	fd_set rfds;
+	int nfds;
+
+	while (true) {
+		FD_ZERO(&rfds);
+		FD_SET(g_st->fd_gtpc, &rfds);
+		nfds = g_st->fd_gtpc + 1;
+		rc = select(nfds, &rfds, NULL, NULL, NULL);
+		if (rc == 0)
+			continue;
+		if (rc < 0) {
+			fprintf(stderr, "select() failed: %s\n", strerror(errno));
+			return -1;
+		}
+
+		if (FD_ISSET(g_st->fd_gtpc, &rfds))
+			read_cb(g_st->fd_gtpc);
+	}
+}
+
+int main(int argc, char **argv)
+{
+	g_st = calloc(1, sizeof(struct gtp_echo_resp_state));
+
+	strcpy(g_st->cfg.laddr, "::");
+
+	handle_options(argc, argv);
+
+	printf("Listening on: %s\n", g_st->cfg.laddr);
+
+	if (init_socket() < 0)
+		exit(1);
+
+	printf("Socket bound successfully, listening for requests...\n");
+
+	if (loop() < 0)
+		exit(1);
+
+	return 0;
+}

utils/gtp_echo_responder_test.py

@@ -0,0 +1,111 @@
+#!/usr/bin/env python3
+# MIT License
+#
+# Copyright (c) 2021 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+# Author: Pau Espin Pedrol <pespin@sysmocom.de>
+#
+# SPDX-License-Identifier: MIT
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice (including the next
+# paragraph) shall be included in all copies or substantial portions of the
+# Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+
+import socket
+import argparse
+import struct
+from ipaddress import ip_address, IPv4Address
+
+GTP1C_PORT = 2123
+BUF_SIZE = 4096
+
+GTP_HDRv1_FLAG_PN = (1<<0)
+GTP_HDRv1_FLAG_S = (1<<1)
+GTP_HDRv1_FLAG_E = (1<<2)
+GTP_HDRv1_PT_GTP = (1<<4)
+GTP_HDRv1_VER_GTP1 = (1<<5)
+
+GTP_HDRv2_FLAG_T = (1<<3)
+GTP_HDRv2_FLAG_P = (1<<4)
+GTP_HDRv2_VER_GTP2 = (2<<5)
+
+def gen_gtpc_v1_hdr(flags, type, length, tei, seq=0, npdu=0, next=0):
+    spare = 0
+    if (flags & (GTP_HDRv1_FLAG_PN|GTP_HDRv1_FLAG_S|GTP_HDRv1_FLAG_E)):
+        #long format
+        length += 4
+        d = struct.pack('!BBHIHBB', flags, type, length, tei, seq, npdu, next)
+    else:
+        #short format
+        d = struct.pack('!BBHI', flags, type, length, tei)
+    return d
+
+def gen_gtpc_v2_hdr(flags, type, length, tei=0, seq=0):
+    spare = 0
+    if (flags & (GTP_HDRv2_FLAG_T)):
+        #long format, with TEI
+        length += 4 + 4
+        d = struct.pack('!BBHIHBB', flags, type, length, tei, seq >> 8, seq & 0xff, spare)
+    else:
+        #short format
+        length += 4
+        d = struct.pack('!BBHHBB', flags, type, length, seq >> 8, seq & 0xff, spare)
+    return d
+
+def gen_gtpc_v1_echo_req(tei=0, append_flags=0, seq=0, npdu=0, next=0):
+    return gen_gtpc_v1_hdr(GTP_HDRv1_VER_GTP1 | GTP_HDRv1_PT_GTP | append_flags, 1, 0, tei, seq, npdu, next)
+
+def gen_gtpc_v2_echo_req(append_flags=0, seq=0, recovery=0, node_features=-1):
+    length = 0
+    payload = b''
+    if (recovery > 0):
+        recovery_ie = struct.pack('!BHBB', 3, 1, 0, recovery)
+        payload += recovery_ie
+        length += len(recovery_ie)
+    if (node_features > 0):
+        node_features_ie = struct.pack('!BHBB', 152, 1, 0, node_features)
+        payload += node_features_ie
+        length += len(node_features_ie)
+    return gen_gtpc_v2_hdr(GTP_HDRv2_VER_GTP2 | append_flags, 1, length, 0, seq) + payload
+
+def tx_rx(sk, rem_addr, tx_buf, exp_rx = True):
+    print('Tx ECHO_REQ to %r: %r' % (repr(rem_addr), repr(tx_buf)))
+    sk.sendto(tx_buf, rem_addr)
+    if exp_rx:
+        rx_buf = sk.recvfrom(BUF_SIZE)
+        msg = "Message from Server {}".format(rx_buf)
+        print(msg)
+
+if __name__ == '__main__':
+    p = argparse.ArgumentParser(description='Tester for gtp-echo-recorder.')
+    p.add_argument('-l', '--local-address', default='127.0.0.2', help="Local GTP address")
+    p.add_argument('-r', '--remote-address', default='127.0.0.1', help="Remote GTP address")
+    args = p.parse_args()
+
+    print('Binding socket on %r...' % repr((args.local_address, GTP1C_PORT)))
+    family = socket.AF_INET if type(ip_address(args.local_address)) is IPv4Address else socket.AF_INET6
+    sk = socket.socket(family=family, type=socket.SOCK_DGRAM)
+    sk.bind((args.local_address, GTP1C_PORT));
+
+    rem_addr = (args.remote_address, GTP1C_PORT)
+
+    tx_rx(sk, rem_addr, gen_gtpc_v1_echo_req())
+    tx_rx(sk, rem_addr, gen_gtpc_v1_echo_req(1, GTP_HDRv1_FLAG_S, seq=67))
+    tx_rx(sk, rem_addr, gen_gtpc_v2_echo_req(0, seq=300, recovery=-1, node_features=-1))
+    tx_rx(sk, rem_addr, gen_gtpc_v2_echo_req(0, seq=20, recovery=99, node_features=-1))
+    tx_rx(sk, rem_addr, gen_gtpc_v2_echo_req(0, seq=20, recovery=100, node_features=0xbb))