bsc: Add code responsible for connecting, reconnecting to the MSC

Add the code that is forwarding data, from and to the MSC, also
handling ping/pong timers and authentication. Hook it into the
osmo_bsc. The code is only compile tested and ported from the
on-waves/bsc-master branch.

openbsc/include/openbsc/osmo_msc_data.h

@@ -26,6 +26,8 @@
 
 #include "bsc_msc.h"
 
+#include <osmocore/timer.h>
+
 struct osmo_bsc_rf;
 
 struct osmo_msc_data {
@@ -36,11 +38,18 @@ struct osmo_msc_data {
 	char *msc_ip;
 	int ping_timeout;
 	int pong_timeout;
+	struct timer_list ping_timer;
+	struct timer_list pong_timer;
 	struct bsc_msc_connection *msc_con;
 
+	/* mgcp agent */
+	struct write_queue mgcp_agent;
+
 	/* rf ctl related bits */
 	char *ussd_grace_txt;
 	struct osmo_bsc_rf *rf_ctl;
 };
 
+int osmo_bsc_msc_init(struct gsm_network *network);
+
 #endif

openbsc/src/bsc/Makefile.am

@@ -6,7 +6,7 @@ bin_PROGRAMS = osmo-bsc
 
 
 osmo_bsc_SOURCES = osmo_bsc_main.c osmo_bsc_rf.c osmo_bsc_vty.c osmo_bsc_api.c \
-		   osmo_bsc_grace.c \
+		   osmo_bsc_grace.c osmo_bsc_msc.c \
 		   $(top_srcdir)/src/debug.c $(top_srcdir)/src/bsc_msc.c \
 		   $(top_srcdir)/src/bsc_init.c
 osmo_bsc_LDADD = $(top_builddir)/src/libvty.a \

openbsc/src/bsc/osmo_bsc_main.c

@@ -224,6 +224,11 @@ int main(int argc, char **argv)
 		}
 	}
 
+	if (osmo_bsc_msc_init(bsc_gsmnet) != 0) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to start up. Exiting.\n");
+		exit(1);
+	}
+
 	signal(SIGINT, &signal_handler);
 	signal(SIGABRT, &signal_handler);
 	signal(SIGUSR1, &signal_handler);

openbsc/src/bsc/osmo_bsc_msc.c

@@ -0,0 +1,371 @@
+/*
+ * Handle the connection to the MSC. This include ping/timeout/reconnect
+ * (C) 2008-2009 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2009-2010 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2009-2010 by On-Waves
+ * 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, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <openbsc/bsc_nat.h>
+#include <openbsc/ipaccess.h>
+#include <openbsc/gsm_data.h>
+#include <openbsc/osmo_msc_data.h>
+#include <openbsc/debug.h>
+
+#include <osmocore/gsm0808.h>
+
+#include <osmocom/sccp/sccp.h>
+
+#include <sys/socket.h>
+#include <netinet/tcp.h>
+#include <unistd.h>
+
+
+static int msc_queue_write(struct bsc_msc_connection *conn, struct msgb *msg, int proto);
+static void initialize_if_needed(struct bsc_msc_connection *conn);
+static void send_id_get_response(struct osmo_msc_data *data, int fd);
+static void send_ping(struct osmo_msc_data *data);
+
+/*
+ * MGCP forwarding code
+ */
+static int mgcp_do_read(struct bsc_fd *fd)
+{
+	struct osmo_msc_data *data = (struct osmo_msc_data *) fd->data;
+	struct msgb *mgcp;
+	int ret;
+
+	mgcp = msgb_alloc_headroom(4096, 128, "mgcp_from_gw");
+	if (!mgcp) {
+		LOGP(DMGCP, LOGL_ERROR, "Failed to allocate MGCP message.\n");
+		return -1;
+	}
+
+	ret = read(fd->fd, mgcp->data, 4096 - 128);
+	if (ret <= 0) {
+		LOGP(DMGCP, LOGL_ERROR, "Failed to read: %d/%s\n", errno, strerror(errno));
+		msgb_free(mgcp);
+		return -1;
+	} else if (ret > 4096 - 128) {
+		LOGP(DMGCP, LOGL_ERROR, "Too much data: %d\n", ret);
+		msgb_free(mgcp);
+		return -1;
+        }
+
+	mgcp->l2h = msgb_put(mgcp, ret);
+	msc_queue_write(data->msc_con, mgcp, NAT_IPAC_PROTO_MGCP);
+	return 0;
+}
+
+static int mgcp_do_write(struct bsc_fd *fd, struct msgb *msg)
+{
+	int ret;
+
+	LOGP(DMGCP, LOGL_DEBUG, "Sending msg to MGCP GW size: %u\n", msg->len);
+
+	ret = write(fd->fd, msg->data, msg->len);
+	if (ret != msg->len)
+		LOGP(DMGCP, LOGL_ERROR, "Failed to forward message to MGCP GW (%s).\n", strerror(errno));
+
+	return ret;
+}
+
+static void mgcp_forward(struct osmo_msc_data *data, struct msgb *msg)
+{
+	struct msgb *mgcp;
+
+	if (msgb_l2len(msg) > 4096) {
+		LOGP(DMGCP, LOGL_ERROR, "Can not forward too big message.\n");
+		return;
+	}
+
+	mgcp = msgb_alloc(4096, "mgcp_to_gw");
+	if (!mgcp) {
+		LOGP(DMGCP, LOGL_ERROR, "Failed to send message.\n");
+		return;
+	}
+
+	msgb_put(mgcp, msgb_l2len(msg));
+	memcpy(mgcp->data, msg->l2h, mgcp->len);
+	if (write_queue_enqueue(&data->mgcp_agent, mgcp) != 0) {
+		LOGP(DMGCP, LOGL_FATAL, "Could not queue message to MGCP GW.\n");
+		msgb_free(mgcp);
+	}
+}
+
+static int mgcp_create_port(struct osmo_msc_data *data)
+{
+	int on;
+	struct sockaddr_in addr;
+
+	data->mgcp_agent.bfd.fd = socket(AF_INET, SOCK_DGRAM, 0);
+	if (data->mgcp_agent.bfd.fd < 0) {
+		LOGP(DMGCP, LOGL_FATAL, "Failed to create UDP socket errno: %d\n", errno);
+		return -1;
+	}
+
+	on = 1;
+	setsockopt(data->mgcp_agent.bfd.fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
+
+	/* try to bind the socket */
+	memset(&addr, 0, sizeof(addr));
+	addr.sin_family = AF_INET;
+	addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+	addr.sin_port = 0;
+
+	if (bind(data->mgcp_agent.bfd.fd, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
+		LOGP(DMGCP, LOGL_FATAL, "Failed to bind to any port.\n");
+		close(data->mgcp_agent.bfd.fd);
+		data->mgcp_agent.bfd.fd = -1;
+		return -1;
+	}
+
+	/* connect to the remote */
+	addr.sin_port = htons(2427);
+	if (connect(data->mgcp_agent.bfd.fd, (struct sockaddr *) & addr, sizeof(addr)) < 0) {
+		LOGP(DMGCP, LOGL_FATAL, "Failed to connect to local MGCP GW. %s\n", strerror(errno));
+		close(data->mgcp_agent.bfd.fd);
+		data->mgcp_agent.bfd.fd = -1;
+		return -1;
+	}
+
+	write_queue_init(&data->mgcp_agent, 10);
+	data->mgcp_agent.bfd.when = BSC_FD_READ;
+	data->mgcp_agent.bfd.data = data;
+	data->mgcp_agent.read_cb = mgcp_do_read;
+	data->mgcp_agent.write_cb = mgcp_do_write;
+
+	if (bsc_register_fd(&data->mgcp_agent.bfd) != 0) {
+		LOGP(DMGCP, LOGL_FATAL, "Failed to register BFD\n");
+		close(data->mgcp_agent.bfd.fd);
+		data->mgcp_agent.bfd.fd = -1;
+		return -1;
+	}
+
+	return 0;
+}
+
+/*
+ * Send data to the network
+ */
+static int msc_queue_write(struct bsc_msc_connection *conn, struct msgb *msg, int proto)
+{
+	ipaccess_prepend_header(msg, proto);
+	if (write_queue_enqueue(&conn->write_queue, msg) != 0) {
+		LOGP(DMSC, LOGL_FATAL, "Failed to queue IPA/%d\n", proto);
+		msgb_free(msg);
+		return -1;
+	}
+
+	return 0;
+}
+
+static int msc_sccp_do_write(struct bsc_fd *fd, struct msgb *msg)
+{
+	int ret;
+
+	LOGP(DMSC, LOGL_DEBUG, "Sending SCCP to MSC: %u\n", msgb_l2len(msg));
+	LOGP(DMI, LOGL_DEBUG, "MSC TX %s\n", hexdump(msg->l2h, msgb_l2len(msg)));
+
+	ret = write(fd->fd, msg->data, msg->len);
+	if (ret < msg->len)
+		perror("MSC: Failed to send SCCP");
+
+	return ret;
+}
+
+static int ipaccess_a_fd_cb(struct bsc_fd *bfd)
+{
+	int error;
+	struct msgb *msg = ipaccess_read_msg(bfd, &error);
+	struct ipaccess_head *hh;
+	struct gsm_network *net = (struct gsm_network *) bfd->data;
+	struct osmo_msc_data *data = net->msc_data;
+
+	if (!msg) {
+		if (error == 0) {
+			LOGP(DMSC, LOGL_ERROR, "The connection to the MSC was lost.\n");
+			bsc_msc_lost(data->msc_con);
+			return -1;
+		}
+
+		LOGP(DMSC, LOGL_ERROR, "Failed to parse ip access message: %d\n", error);
+		return -1;
+	}
+
+	LOGP(DMSC, LOGL_DEBUG, "From MSC: %s proto: %d\n", hexdump(msg->data, msg->len), msg->l2h[0]);
+
+	/* handle base message handling */
+	hh = (struct ipaccess_head *) msg->data;
+	ipaccess_rcvmsg_base(msg, bfd);
+
+	/* initialize the networking. This includes sending a GSM08.08 message */
+	if (hh->proto == IPAC_PROTO_IPACCESS) {
+		if (msg->l2h[0] == IPAC_MSGT_ID_ACK)
+			initialize_if_needed(data->msc_con);
+		else if (msg->l2h[0] == IPAC_MSGT_ID_GET) {
+			send_id_get_response(data, bfd->fd);
+		} else if (msg->l2h[0] == IPAC_MSGT_PONG) {
+			bsc_del_timer(&data->pong_timer);
+		}
+	} else if (hh->proto == IPAC_PROTO_SCCP) {
+		sccp_system_incoming(msg);
+	} else if (hh->proto == NAT_IPAC_PROTO_MGCP) {
+		mgcp_forward(data, msg);
+	}
+
+	msgb_free(msg);
+	return 0;
+}
+
+static void send_ping(struct osmo_msc_data *data)
+{
+	struct msgb *msg;
+
+	msg = msgb_alloc_headroom(4096, 128, "ping");
+	if (!msg) {
+		LOGP(DMSC, LOGL_ERROR, "Failed to create PING.\n");
+		return;
+	}
+
+	msg->l2h = msgb_put(msg, 1);
+	msg->l2h[0] = IPAC_MSGT_PING;
+
+	msc_queue_write(data->msc_con, msg, IPAC_PROTO_IPACCESS);
+}
+
+static void msc_ping_timeout_cb(void *_data)
+{
+	struct osmo_msc_data *data = (struct osmo_msc_data *) _data;
+	if (data->ping_timeout < 0)
+		return;
+
+	send_ping(data);
+
+	/* send another ping in 20 seconds */
+	bsc_schedule_timer(&data->ping_timer, data->ping_timeout, 0);
+
+	/* also start a pong timer */
+	bsc_schedule_timer(&data->pong_timer, data->pong_timeout, 0);
+}
+
+static void msc_pong_timeout_cb(void *_data)
+{
+	struct osmo_msc_data *data = (struct osmo_msc_data *) _data;
+
+	LOGP(DMSC, LOGL_ERROR, "MSC didn't answer PING. Closing connection.\n");
+	bsc_msc_lost(data->msc_con);
+}
+
+static void msc_connection_connected(struct bsc_msc_connection *con)
+{
+	struct osmo_msc_data *data;
+	int ret, on;
+	on = 1;
+	ret = setsockopt(con->write_queue.bfd.fd, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on));
+	if (ret != 0)
+                LOGP(DMSC, LOGL_ERROR, "Failed to set TCP_NODELAY: %s\n", strerror(errno));
+
+	data = (struct osmo_msc_data *) con->write_queue.bfd.data;
+	msc_ping_timeout_cb(con);
+}
+
+/*
+ * The connection to the MSC was lost and we will need to free all
+ * resources and then attempt to reconnect.
+ */
+static void msc_connection_was_lost(struct bsc_msc_connection *msc)
+{
+	struct osmo_msc_data *data;
+
+	LOGP(DMSC, LOGL_ERROR, "Lost MSC connection. Freing stuff.\n");
+
+#if 0
+	struct bss_sccp_connection_data *bss, *tmp;
+	llist_for_each_entry_safe(bss, tmp, &active_connections, active_connections) {
+		bss_force_close(bss);
+	}
+#else
+#warning "This needs to be ported..."
+#endif
+
+	data = (struct osmo_msc_data *) msc->write_queue.bfd.data;
+	bsc_del_timer(&data->ping_timer);
+	bsc_del_timer(&data->pong_timer);
+
+	msc->is_authenticated = 0;
+	bsc_msc_schedule_connect(msc);
+}
+
+static void initialize_if_needed(struct bsc_msc_connection *conn)
+{
+	struct msgb *msg;
+
+	if (!conn->is_authenticated) {
+		/* send a gsm 08.08 reset message from here */
+		msg = gsm0808_create_reset();
+		if (!msg) {
+			LOGP(DMSC, LOGL_ERROR, "Failed to create the reset message.\n");
+			return;
+		}
+
+		sccp_write(msg, &sccp_ssn_bssap, &sccp_ssn_bssap, 0);
+		msgb_free(msg);
+		conn->is_authenticated = 1;
+	}
+}
+
+static void send_id_get_response(struct osmo_msc_data *data, int fd)
+{
+	struct msgb *msg;
+
+	msg = bsc_msc_id_get_resp(data->bsc_token);
+	if (!msg)
+		return;
+	msc_queue_write(data->msc_con, msg, IPAC_PROTO_IPACCESS);
+}
+
+int osmo_bsc_msc_init(struct gsm_network *network)
+{
+	struct osmo_msc_data *data = network->msc_data;
+
+	if (mgcp_create_port(data) != 0)
+		return -1;
+
+	data->msc_con = bsc_msc_create(data->msc_ip,
+				       data->msc_port,
+				       data->msc_ip_dscp);
+	if (!data->msc_con) {
+		LOGP(DMSC, LOGL_ERROR, "Creating the MSC network connection failed.\n");
+		return -1;
+	}
+
+	data->ping_timer.cb = msc_ping_timeout_cb;
+	data->ping_timer.data = data;
+	data->pong_timer.cb = msc_pong_timeout_cb;
+	data->pong_timer.data = data;
+
+	data->msc_con->write_queue.bfd.data = data;
+	data->msc_con->connection_loss = msc_connection_was_lost;
+	data->msc_con->connected = msc_connection_connected;
+	data->msc_con->write_queue.read_cb = ipaccess_a_fd_cb;
+	data->msc_con->write_queue.write_cb = msc_sccp_do_write;
+	bsc_msc_connect(data->msc_con);
+
+	return 0;
+}