msc: Create a real interface for BSC MSC and start handling reconnects

Create a BSC<->MSC interface and use it for the BSC MSC IP and the
BSC NAT to reduce code duplication on handling reconnects to the MSC
and cleaning up the local state. The code is only partially tested
and will contain bugs. Currently both the BSC and the NAT will just
exit on connection loss and this way have the current behavior.

openbsc/include/openbsc/bsc_msc.h

@@ -23,8 +23,24 @@
 #ifndef BSC_MSC_H
 #define BSC_MSC_H
 
-#include <osmocore/select.h>
+#include <osmocore/write_queue.h>
+#include <osmocore/timer.h>
 
-int connect_to_msc(struct bsc_fd *fd, const char *ip, int port);
+struct bsc_msc_connection {
+	struct write_queue write_queue;
+	int is_connected;
+	const char *ip;
+	int port;
+
+	void (*connection_loss) (struct bsc_msc_connection *);
+	void (*connected) (struct bsc_msc_connection *);
+	struct timer_list reconnect_timer;
+};
+
+struct bsc_msc_connection *bsc_msc_create(const char *ip, int port);
+int bsc_msc_connect(struct bsc_msc_connection *);
+void bsc_msc_schedule_connect(struct bsc_msc_connection *);
+
+void bsc_msc_lost(struct bsc_msc_connection *);
 
 #endif

openbsc/src/bsc_msc.c

@@ -24,6 +24,7 @@
 #include <openbsc/debug.h>
 
 #include <osmocore/write_queue.h>
+#include <osmocore/talloc.h>
 
 #include <arpa/inet.h>
 #include <sys/socket.h>
@@ -33,11 +34,27 @@
 #include <string.h>
 #include <unistd.h>
 
+static void connection_loss(struct bsc_msc_connection *con)
+{
+	struct bsc_fd *fd;
+
+	fd = &con->write_queue.bfd;
+
+	close(fd->fd);
+	fd->fd = -1;
+	fd->cb = write_queue_bfd_cb;
+	fd->when = 0;
+
+	con->is_connected = 0;
+	con->connection_loss(con);
+}
+
 /* called in the case of a non blocking connect */
 static int msc_connection_connect(struct bsc_fd *fd, unsigned int what)
 {
 	int rc;
 	int val;
+	struct bsc_msc_connection *con;
 	struct write_queue *queue;
 
 	socklen_t len = sizeof(val);
@@ -47,6 +64,9 @@ static int msc_connection_connect(struct bsc_fd *fd, unsigned int what)
 		return -1;
 	}
 
+	queue = container_of(fd, struct write_queue, bfd);
+	con = container_of(queue, struct bsc_msc_connection, write_queue);
+
 	/* check the socket state */
 	rc = getsockopt(fd->fd, SOL_SOCKET, SO_ERROR, &val, &len);
 	if (rc != 0) {
@@ -60,19 +80,17 @@ static int msc_connection_connect(struct bsc_fd *fd, unsigned int what)
 
 
 	/* go to full operation */
-	queue = container_of(fd, struct write_queue, bfd);
 	fd->cb = write_queue_bfd_cb;
 	fd->when = BSC_FD_READ;
-	if (!llist_empty(&queue->msg_queue))
-		fd->when |= BSC_FD_WRITE;
+
+	con->is_connected = 1;
+	if (con->connected)
+		con->connected(con);
 	return 0;
 
 error:
 	bsc_unregister_fd(fd);
-	close(fd->fd);
-	fd->fd = -1;
-	fd->cb = write_queue_bfd_cb;
-	fd->when = 0;
+	connection_loss(con);
 	return -1;
 }
 static void setnonblocking(struct bsc_fd *fd)
@@ -97,13 +115,17 @@ static void setnonblocking(struct bsc_fd *fd)
 	}
 }
 
-int connect_to_msc(struct bsc_fd *fd, const char *ip, int port)
+int bsc_msc_connect(struct bsc_msc_connection *con)
 {
+	struct bsc_fd *fd;
 	struct sockaddr_in sin;
 	int on = 1, ret;
 
-	printf("Attempting to connect MSC at %s:%d\n", ip, port);
+	LOGP(DMSC, LOGL_NOTICE, "Attempting to connect MSC at %s:%d\n", con->ip, con->port);
 
+	con->is_connected = 0;
+
+	fd = &con->write_queue.bfd;
 	fd->fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
 	fd->data = NULL;
 	fd->priv_nr = 1;
@@ -118,8 +140,8 @@ int connect_to_msc(struct bsc_fd *fd, const char *ip, int port)
 
 	memset(&sin, 0, sizeof(sin));
 	sin.sin_family = AF_INET;
-	sin.sin_port = htons(port);
-        inet_aton(ip, &sin.sin_addr);
+	sin.sin_port = htons(con->port);
+	inet_aton(con->ip, &sin.sin_addr);
 
 	setsockopt(fd->fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
 	ret = connect(fd->fd, (struct sockaddr *) &sin, sizeof(sin));
@@ -130,12 +152,14 @@ int connect_to_msc(struct bsc_fd *fd, const char *ip, int port)
 		fd->cb = msc_connection_connect;
 	} else if (ret < 0) {
 		perror("Connection failed");
-		close(fd->fd);
-		fd->fd = -1;
+		connection_loss(con);
 		return ret;
 	} else {
 		fd->when = BSC_FD_READ;
 		fd->cb = write_queue_bfd_cb;
+		con->is_connected = 1;
+		if (con->connected)
+			con->connected(con);
 	}
 
 	ret = bsc_register_fd(fd);
@@ -147,3 +171,41 @@ int connect_to_msc(struct bsc_fd *fd, const char *ip, int port)
 
 	return ret;
 }
+
+struct bsc_msc_connection *bsc_msc_create(const char *ip, int port)
+{
+	struct bsc_msc_connection *con;
+
+	con = talloc_zero(NULL, struct bsc_msc_connection);
+	if (!con) {
+		LOGP(DMSC, LOGL_FATAL, "Failed to create the MSC connection.\n");
+		return NULL;
+	}
+
+	con->ip = ip;
+	con->port = port;
+	write_queue_init(&con->write_queue, 100);
+	return con;
+}
+
+void bsc_msc_lost(struct bsc_msc_connection *con)
+{
+	bsc_unregister_fd(&con->write_queue.bfd);
+	connection_loss(con);
+}
+
+static void reconnect_msc(void *_msc)
+{
+	struct bsc_msc_connection *con = _msc;
+
+	LOGP(DMSC, LOGL_NOTICE, "Attempting to reconnect to the MSC.\n");
+	bsc_msc_connect(con);
+}
+
+void bsc_msc_schedule_connect(struct bsc_msc_connection *con)
+{
+	LOGP(DMSC, LOGL_NOTICE, "Attempting to reconnect to the MSC.\n");
+	con->reconnect_timer.cb = reconnect_msc;
+	con->reconnect_timer.data = con;
+	bsc_schedule_timer(&con->reconnect_timer, 5, 0);
+}

openbsc/src/nat/bsc_nat.c

@@ -53,7 +53,7 @@ struct debug_target *stderr_target;
 static const char *config_file = "bsc-nat.cfg";
 static char *msc_address = "127.0.0.1";
 static struct in_addr local_addr;
-static struct write_queue msc_queue;
+static struct bsc_msc_connection *msc_con;
 static struct bsc_fd bsc_listen;
 
 
@@ -420,6 +420,12 @@ exit:
 	return 0;
 }
 
+static void msc_connection_was_lost(struct bsc_msc_connection *con)
+{
+	LOGP(DMSC, LOGL_FATAL, "Lost the connection.\n");
+	exit(0);
+}
+
 static int ipaccess_msc_read_cb(struct bsc_fd *bfd)
 {
 	int error;
@@ -429,7 +435,8 @@ static int ipaccess_msc_read_cb(struct bsc_fd *bfd)
 	if (!msg) {
 		if (error == 0) {
 			LOGP(DNAT, LOGL_FATAL, "The connection the MSC was lost, exiting\n");
-			exit(-2);
+			bsc_msc_lost(msc_con);
+			return -1;
 		}
 
 		LOGP(DNAT, LOGL_ERROR, "Failed to parse ip access message: %d\n", error);
@@ -576,7 +583,7 @@ static int forward_sccp_to_msc(struct bsc_connection *bsc, struct msgb *msg)
 	}
 
 	/* send the non-filtered but maybe modified msg */
-	if (write_queue_enqueue(&msc_queue, msg) != 0) {
+	if (write_queue_enqueue(&msc_con->write_queue, msg) != 0) {
 		LOGP(DNAT, LOGL_ERROR, "Can not queue message for the MSC.\n");
 		msgb_free(msg);
 	}
@@ -822,7 +829,6 @@ static void signal_handler(int signal)
 
 int main(int argc, char** argv)
 {
-	int rc;
 
 	debug_init();
 	stderr_target = debug_target_create_stderr();
@@ -851,15 +857,17 @@ int main(int argc, char** argv)
 	srand(time(NULL));
 
 	/* connect to the MSC */
-	write_queue_init(&msc_queue, 100);
-	msc_queue.read_cb = ipaccess_msc_read_cb;
-	msc_queue.write_cb = ipaccess_msc_write_cb;
-	rc = connect_to_msc(&msc_queue.bfd, msc_address, 5000);
-	if (rc < 0) {
-		fprintf(stderr, "Opening the MSC connection failed.\n");
+	msc_con = bsc_msc_create(msc_address, 5000);
+	if (!msc_con) {
+		fprintf(stderr, "Creating a bsc_msc_connection failed.\n");
 		exit(1);
 	}
 
+	msc_con->connection_loss = msc_connection_was_lost;
+	msc_con->write_queue.read_cb = ipaccess_msc_read_cb;
+	msc_con->write_queue.write_cb = ipaccess_msc_write_cb;;
+	bsc_msc_connect(msc_con);
+
 	/* wait for the BSC */
 	if (listen_for_bsc(&bsc_listen, &local_addr, 5000) < 0) {
 		fprintf(stderr, "Failed to listen for BSC.\n");