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

2 files changed, 21 insertions, 6 deletions

diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat.c b/openbsc/src/osmo-bsc_nat/bsc_nat.c
index d9fc0ca48..524186a55 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_nat.c
+++ b/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",
diff --git a/openbsc/src/osmo-bsc_nat/bsc_ussd.c b/openbsc/src/osmo-bsc_nat/bsc_ussd.c
index 8da818119..5f073bf4f 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_ussd.c
+++ b/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;