ipa: Use enhanced ipa_msg_recv_buffered() to cope with partioned IPA messages

The old ipa_msg_recv() implementation didn't support partial receive,
so IPA connections got disconnected when this happened.

This patch adds the handling of the temporary message buffers and uses
ipa_msg_recv_buffered().

It has been successfully tested by jerlbeck with osmo-nitb and
osmo-bsc.

Ticket: OW#768
Sponsored-by: On-Waves ehf

openbsc/configure.ac

@@ -25,7 +25,7 @@ AC_SUBST(LIBRARY_DL)
 PKG_CHECK_MODULES(LIBOSMOCORE, libosmocore >= 0.6.4)
 PKG_CHECK_MODULES(LIBOSMOVTY, libosmovty >= 0.3.0)
 PKG_CHECK_MODULES(LIBOSMOGSM, libosmogsm >= 0.6.0)
-PKG_CHECK_MODULES(LIBOSMOABIS, libosmoabis >= 0.1.0)
+PKG_CHECK_MODULES(LIBOSMOABIS, libosmoabis >= 0.2.0)
 PKG_CHECK_MODULES(LIBOSMOGB, libosmogb >= 0.6.4)
 
 # Enabke/disable the NAT?

openbsc/include/openbsc/bsc_msc.h

@@ -48,6 +48,8 @@ struct bsc_msc_connection {
 	void (*connected) (struct bsc_msc_connection *);
 	struct osmo_timer_list reconnect_timer;
 	struct osmo_timer_list timeout_timer;
+
+	struct msgb *pending_msg;
 };
 
 struct bsc_msc_connection *bsc_msc_create(void *ctx, struct llist_head *dest);

openbsc/include/openbsc/bsc_nat.h

@@ -97,6 +97,9 @@ struct bsc_connection {
 	/* the fd we use to communicate */
 	struct osmo_wqueue write_queue;
 
+	/* incoming message buffer */
+	struct msgb *pending_msg;
+
 	/* the BSS associated */
 	struct bsc_config *cfg;
 
@@ -343,6 +346,8 @@ struct bsc_nat_ussd_con {
 	struct bsc_nat *nat;
 	int authorized;
 
+	struct msgb *pending_msg;
+
 	struct osmo_timer_list auth_timeout;
 };
 

openbsc/include/openbsc/control_cmd.h

@@ -39,6 +39,9 @@ struct ctrl_connection {
 	/* The queue for sending data back */
 	struct osmo_wqueue write_queue;
 
+	/* Buffer for partial input data */
+	struct msgb *pending_msg;
+
 	/* Callback if the connection was closed */
 	void (*closed_cb)(struct ctrl_connection *conn);
 

openbsc/src/libbsc/bsc_msc.c

@@ -42,6 +42,13 @@ static void connection_loss(struct bsc_msc_connection *con)
 
 	fd = &con->write_queue.bfd;
 
+	if (con->pending_msg) {
+		LOGP(DMSC, LOGL_ERROR,
+		     "MSC(%s) dropping incomplete message.\n", con->name);
+		msgb_free(con->pending_msg);
+		con->pending_msg = NULL;
+	}
+
 	close(fd->fd);
 	fd->fd = -1;
 	fd->cb = osmo_wqueue_bfd_cb;
@@ -162,6 +169,9 @@ int bsc_msc_connect(struct bsc_msc_connection *con)
 
 	con->is_connected = 0;
 
+	msgb_free(con->pending_msg);
+	con->pending_msg = NULL;
+
 	fd = &con->write_queue.bfd;
 	fd->fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
 	fd->priv_nr = 1;

openbsc/src/libctrl/control_if.c

@@ -123,6 +123,7 @@ static void control_close_conn(struct ctrl_connection *ccon)
 	llist_del(&ccon->list_entry);
 	if (ccon->closed_cb)
 		ccon->closed_cb(ccon);
+	msgb_free(ccon->pending_msg);
 	talloc_free(ccon);
 }
 
@@ -140,8 +141,10 @@ static int handle_control_read(struct osmo_fd * bfd)
 	queue = container_of(bfd, struct osmo_wqueue, bfd);
 	ccon = container_of(queue, struct ctrl_connection, write_queue);
 
-	ret = ipa_msg_recv(bfd->fd, &msg);
+	ret = ipa_msg_recv_buffered(bfd->fd, &msg, &ccon->pending_msg);
 	if (ret <= 0) {
+		if (ret == -EAGAIN)
+			return 0;
 		if (ret == 0)
 			LOGP(DCTRL, LOGL_INFO, "The control connection was closed\n");
 		else

openbsc/src/osmo-bsc/osmo_bsc_msc.c

@@ -247,13 +247,15 @@ static void osmo_ext_handle(struct osmo_msc_data *msc, struct msgb *msg)
 
 static int ipaccess_a_fd_cb(struct osmo_fd *bfd)
 {
-	struct msgb *msg;
+	struct msgb *msg = NULL;
 	struct ipaccess_head *hh;
 	struct osmo_msc_data *data = (struct osmo_msc_data *) bfd->data;
 	int ret;
 
-	ret = ipa_msg_recv(bfd->fd, &msg);
+	ret = ipa_msg_recv_buffered(bfd->fd, &msg, &data->msc_con->pending_msg);
 	if (ret <= 0) {
+		if (ret == -EAGAIN)
+			return 0;
 		if (ret == 0) {
 			LOGP(DMSC, LOGL_ERROR, "The connection to the MSC was lost.\n");
 			bsc_msc_lost(data->msc_con);

openbsc/src/osmo-bsc_nat/bsc_nat.c

@@ -796,14 +796,16 @@ static void msc_send_reset(struct bsc_msc_connection *msc_con)
 static int ipaccess_msc_read_cb(struct osmo_fd *bfd)
 {
 	struct bsc_msc_connection *msc_con;
-	struct msgb *msg;
+	struct msgb *msg = NULL;
 	struct ipaccess_head *hh;
 	int ret;
 
 	msc_con = (struct bsc_msc_connection *) bfd->data;
 
-	ret = ipa_msg_recv(bfd->fd, &msg);
+	ret = ipa_msg_recv_buffered(bfd->fd, &msg, &msc_con->pending_msg);
 	if (ret <= 0) {
+		if (ret == -EAGAIN)
+			return 0;
 		if (ret == 0)
 			LOGP(DNAT, LOGL_FATAL,
 				"The connection the MSC(%s) was lost, exiting\n",
@@ -912,6 +914,13 @@ void bsc_close_connection(struct bsc_connection *connection)
 	osmo_wqueue_clear(&connection->write_queue);
 	llist_del(&connection->list_entry);
 
+	if (connection->pending_msg) {
+		LOGP(DNAT, LOGL_ERROR, "Dropping partial message on connection %d.\n",
+		     connection->cfg->nr);
+		msgb_free(connection->pending_msg);
+		connection->pending_msg = NULL;
+	}
+
 	talloc_free(connection);
 }
 
@@ -1206,13 +1215,15 @@ exit3:
 static int ipaccess_bsc_read_cb(struct osmo_fd *bfd)
 {
 	struct bsc_connection *bsc = bfd->data;
-	struct msgb *msg;
+	struct msgb *msg = NULL;
 	struct ipaccess_head *hh;
 	struct ipaccess_head_ext *hh_ext;
 	int ret;
 
-	ret = ipa_msg_recv(bfd->fd, &msg);
+	ret = ipa_msg_recv_buffered(bfd->fd, &msg, &bsc->pending_msg);
 	if (ret <= 0) {
+		if (ret == -EAGAIN)
+			return 0;
 		if (ret == 0)
 			LOGP(DNAT, LOGL_ERROR,
 			     "The connection to the BSC Nr: %d was lost. Cleaning it\n",

openbsc/src/osmo-bsc_nat/bsc_ussd.c

@@ -66,6 +66,8 @@ static void bsc_nat_ussd_destroy(struct bsc_nat_ussd_con *con)
 	osmo_fd_unregister(&con->queue.bfd);
 	osmo_timer_del(&con->auth_timeout);
 	osmo_wqueue_clear(&con->queue);
+
+	msgb_free(con->pending_msg);
 	talloc_free(con);
 }
 
@@ -117,12 +119,14 @@ static int forward_sccp(struct bsc_nat *nat, struct msgb *msg)
 static int ussd_read_cb(struct osmo_fd *bfd)
 {
 	struct bsc_nat_ussd_con *conn = bfd->data;
-	struct msgb *msg;
+	struct msgb *msg = NULL;
 	struct ipaccess_head *hh;
 	int ret;
 
-	ret = ipa_msg_recv(bfd->fd, &msg);
+	ret = ipa_msg_recv_buffered(bfd->fd, &msg, &conn->pending_msg);
 	if (ret <= 0) {
+		if (ret == -EAGAIN)
+			return 0;
 		LOGP(DNAT, LOGL_ERROR, "USSD Connection was lost.\n");
 		bsc_nat_ussd_destroy(conn);
 		return -1;