[PATCH 6/8] mgcp/nat: Take payload type from SDP data

[Jacob Erlbeck]

So far the payload type used in RTP streams has been taken from the
trunk configuration in NAT mode.

This patch changes the implementation to use the payload type
announced in the SDP part of MGCP messages and responses. SDP
descriptions more than one m=audio line are not yet supported
properly (always the last one is taken).

Ticket: OW#466
Sponsored-by: On-Waves ehf
---
 openbsc/include/openbsc/bsc_nat.h         |    3 ++-
 openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c |   17 +++++++++++++----
 openbsc/tests/bsc-nat/bsc_nat_test.c      |    2 +-
 3 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/openbsc/include/openbsc/bsc_nat.h b/openbsc/include/openbsc/bsc_nat.h
index 635b125..150979b 100644
--- a/openbsc/include/openbsc/bsc_nat.h
+++ b/openbsc/include/openbsc/bsc_nat.h
@@ -408,7 +408,8 @@ void bsc_mgcp_free_endpoints(struct bsc_nat *nat);
 int bsc_mgcp_nat_init(struct bsc_nat *nat);
 
 struct nat_sccp_connection *bsc_mgcp_find_con(struct bsc_nat *, int endpoint_number);
-struct msgb *bsc_mgcp_rewrite(char *input, int length, int endp, const char *ip, int port);
+struct msgb *bsc_mgcp_rewrite(char *input, int length, int endp, const char *ip,
+			      int port, int *payload_type);
 void bsc_mgcp_forward(struct bsc_connection *bsc, struct msgb *msg);
 
 void bsc_mgcp_clear_endpoints_for(struct bsc_connection *bsc);
diff --git a/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c b/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c
index 8bb6075..3dad396 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c
@@ -542,8 +542,10 @@ static int bsc_mgcp_policy_cb(struct mgcp_trunk_config *tcfg, int endpoint, int
 	}
 
 	/* we need to generate a new and patched message */
-	bsc_msg = bsc_mgcp_rewrite((char *) nat->mgcp_msg, nat->mgcp_length, sccp->bsc_endp,
-				   nat->mgcp_cfg->source_addr, mgcp_endp->bts_end.local_port);
+	bsc_msg = bsc_mgcp_rewrite((char *) nat->mgcp_msg, nat->mgcp_length,
+				   sccp->bsc_endp, nat->mgcp_cfg->source_addr,
+				   mgcp_endp->bts_end.local_port,
+				   &mgcp_endp->net_end.payload_type);
 	if (!bsc_msg) {
 		LOGP(DMGCP, LOGL_ERROR, "Failed to patch the msg.\n");
 		return MGCP_POLICY_CONT;
@@ -683,7 +685,9 @@ void bsc_mgcp_forward(struct bsc_connection *bsc, struct msgb *msg)
 	 * with the value of 0 should be no problem.
 	 */
 	output = bsc_mgcp_rewrite((char * ) msg->l2h, msgb_l2len(msg), -1,
-				  bsc->nat->mgcp_cfg->source_addr, endp->net_end.local_port);
+				  bsc->nat->mgcp_cfg->source_addr,
+				  endp->net_end.local_port,
+				  &endp->bts_end.payload_type);
 
 	if (!output) {
 		LOGP(DMGCP, LOGL_ERROR, "Failed to rewrite MGCP msg.\n");
@@ -743,7 +747,9 @@ static void patch_mgcp(struct msgb *output, const char *op, const char *tok,
 }
 
 /* we need to replace some strings... */
-struct msgb *bsc_mgcp_rewrite(char *input, int length, int endpoint, const char *ip, int port)
+struct msgb *bsc_mgcp_rewrite(char *input, int length, int endpoint,
+			      const char *ip, int port,
+			      int *payload_type)
 {
 	static const char crcx_str[] = "CRCX ";
 	static const char dlcx_str[] = "DLCX ";
@@ -836,6 +842,9 @@ copy:
 		memcpy(output->l3h, buf, strlen(buf));
 	}
 
+	if (payload != -1 && payload_type)
+		*payload_type = payload;
+
 	return output;
 }
 
diff --git a/openbsc/tests/bsc-nat/bsc_nat_test.c b/openbsc/tests/bsc-nat/bsc_nat_test.c
index 3320e06..a121c8a 100644
--- a/openbsc/tests/bsc-nat/bsc_nat_test.c
+++ b/openbsc/tests/bsc-nat/bsc_nat_test.c
@@ -630,7 +630,7 @@ static void test_mgcp_rewrite(void)
 		char *input = strdup(orig);
 
 		output = bsc_mgcp_rewrite(input, strlen(input), 0x1e,
-					  ip, port);
+					  ip, port, &payload_type);
 
 		if (payload_type != -1) {
 			fprintf(stderr, "Found media payload type %d in SDP data\n",
-- 
1.7.9.5