mgcp-client: Transmit remote IP addr in CRCX if known and port=0

A client may know the IP address during CRCX but not yet the port, or it
may simply want to hint an initial IP address so that the MGW can better
guess when allocating a local IP address.

Related: SYS#6657
Change-Id: I30165dbac5e484011d0acf46af36f105954a501d
---
M src/libosmo-mgcp-client/mgcp_client.c
M src/libosmo-mgcp-client/mgcp_client_fsm.c
2 files changed, 56 insertions(+), 31 deletions(-)

diff --git a/src/libosmo-mgcp-client/mgcp_client.c b/src/libosmo-mgcp-client/mgcp_client.c
index ceb9592..8693b1b 100644
--- a/src/libosmo-mgcp-client/mgcp_client.c
+++ b/src/libosmo-mgcp-client/mgcp_client.c
@@ -1302,9 +1302,6 @@
 	local_ip_family = osmo_ip_str_type(local_ip);
 	if (local_ip_family == AF_UNSPEC)
 		return -EINVAL;
-	audio_ip_family = osmo_ip_str_type(mgcp_msg->audio_ip);
-	if (audio_ip_family == AF_UNSPEC)
-		return -EINVAL;
 
 	/* Add owner/creator (SDP) */
 	MSGB_PRINTF_OR_RET("o=- %x 23 IN IP%c %s\r\n", mgcp_msg->call_id,
@@ -1314,33 +1311,39 @@
 	/* Add session name (none) */
 	MSGB_PRINTF_OR_RET("s=-\r\n");
 
-	/* Add RTP address and port */
-	if (mgcp_msg->audio_port == 0) {
-		LOGPMGW(mgcp, LOGL_ERROR,
-			"Invalid port number, can not generate MGCP message\n");
-		msgb_free(msg);
-		return -EINVAL;
+	/* Add RTP address */
+	if (mgcp_msg->presence & MGCP_MSG_PRESENCE_AUDIO_IP) {
+		audio_ip_family = osmo_ip_str_type(mgcp_msg->audio_ip);
+		if (audio_ip_family == AF_UNSPEC)
+			return -EINVAL;
+		if (strlen(mgcp_msg->audio_ip) <= 0) {
+			LOGPMGW(mgcp, LOGL_ERROR,
+				"Empty ip address, can not generate MGCP message\n");
+			return -EINVAL;
+		}
+		MSGB_PRINTF_OR_RET("c=IN IP%c %s\r\n",
+				   audio_ip_family == AF_INET6 ? '6' : '4',
+				   mgcp_msg->audio_ip);
 	}
-	if (strlen(mgcp_msg->audio_ip) <= 0) {
-		LOGPMGW(mgcp, LOGL_ERROR,
-			"Empty ip address, can not generate MGCP message\n");
-		msgb_free(msg);
-		return -EINVAL;
-	}
-	MSGB_PRINTF_OR_RET("c=IN IP%c %s\r\n",
-			  audio_ip_family == AF_INET6 ? '6' : '4',
-			  mgcp_msg->audio_ip);
 
 	/* Add time description, active time (SDP) */
 	MSGB_PRINTF_OR_RET("t=0 0\r\n");
 
-	MSGB_PRINTF_OR_RET("m=audio %u RTP/AVP", mgcp_msg->audio_port);
-	for (i = 0; i < mgcp_msg->codecs_len; i++) {
-		pt = map_codec_to_pt(mgcp_msg->ptmap, mgcp_msg->ptmap_len, mgcp_msg->codecs[i]);
-		MSGB_PRINTF_OR_RET(" %u", pt);
+	/* Add RTP address port and codecs */
+	if (mgcp_msg->presence & MGCP_MSG_PRESENCE_AUDIO_PORT) {
+		if (mgcp_msg->audio_port == 0) {
+			LOGPMGW(mgcp, LOGL_ERROR,
+				"Invalid port number, can not generate MGCP message\n");
+			return -EINVAL;
+		}
+		MSGB_PRINTF_OR_RET("m=audio %u RTP/AVP", mgcp_msg->audio_port);
+		for (i = 0; i < mgcp_msg->codecs_len; i++) {
+			pt = map_codec_to_pt(mgcp_msg->ptmap, mgcp_msg->ptmap_len, mgcp_msg->codecs[i]);
+			MSGB_PRINTF_OR_RET(" %u", pt);
 
+		}
+		MSGB_PRINTF_OR_RET("\r\n");
 	}
-	MSGB_PRINTF_OR_RET("\r\n");
 
 	/* Add optional codec parameters (fmtp) */
 	if (mgcp_msg->param_present) {
@@ -1470,10 +1473,10 @@
 		MSGB_PRINTF_OR_RET("I: %s\r\n", mgcp_msg->conn_id);
 	}
 
-	/* Using SDP makes sense when a valid IP/Port combination is specified,
+	/* Using SDP makes sense when a valid IP or Port is specified,
 	 * if we do not know this information yet, we fall back to LCO */
 	if (mgcp_msg->presence & MGCP_MSG_PRESENCE_AUDIO_IP
-	    && mgcp_msg->presence & MGCP_MSG_PRESENCE_AUDIO_PORT)
+	    || mgcp_msg->presence & MGCP_MSG_PRESENCE_AUDIO_PORT)
 		use_sdp = true;
 
 	/* Add local connection options (LCO) */
diff --git a/src/libosmo-mgcp-client/mgcp_client_fsm.c b/src/libosmo-mgcp-client/mgcp_client_fsm.c
index 432ad84..218527c 100644
--- a/src/libosmo-mgcp-client/mgcp_client_fsm.c
+++ b/src/libosmo-mgcp-client/mgcp_client_fsm.c
@@ -136,10 +136,19 @@
 
 static void add_audio(struct mgcp_msg *mgcp_msg, struct mgcp_conn_peer *info)
 {
-	mgcp_msg->presence |= MGCP_MSG_PRESENCE_AUDIO_IP | MGCP_MSG_PRESENCE_AUDIO_PORT;
-	mgcp_msg->audio_ip = info->addr;
-	mgcp_msg->audio_port = info->port;
-	mgcp_msg->conn_mode = MGCP_CONN_RECV_SEND;
+	bool ip_is_set = info->addr[0] != '\0' &&
+			 strncmp(info->addr, "::", sizeof(info->addr)) != 0 &&
+			 strncmp(info->addr, "0.0.0.0", sizeof(info->addr)) != 0;
+	if (ip_is_set) {
+		mgcp_msg->presence |= MGCP_MSG_PRESENCE_AUDIO_IP;
+		mgcp_msg->audio_ip = info->addr;
+	}
+	if (info->port) {
+		mgcp_msg->presence |= MGCP_MSG_PRESENCE_AUDIO_PORT;
+		mgcp_msg->audio_port = info->port;
+	}
+	if (ip_is_set && info->port)
+		mgcp_msg->conn_mode = MGCP_CONN_RECV_SEND;
 }
 
 static void set_conn_mode(struct mgcp_msg *mgcp_msg, struct mgcp_conn_peer *peer)
@@ -221,8 +230,7 @@
 			 mgcp_ctx->conn_peer_local.endpoint);
 
 		make_crcx_msg(&mgcp_msg, &mgcp_ctx->conn_peer_local);
-		if (mgcp_ctx->conn_peer_local.port)
-			add_audio(&mgcp_msg, &mgcp_ctx->conn_peer_local);
+		add_audio(&mgcp_msg, &mgcp_ctx->conn_peer_local);
 		set_conn_mode(&mgcp_msg, &mgcp_ctx->conn_peer_local);
 
 		msg = mgcp_msg_gen(mgcp_ctx->mgcp, &mgcp_msg);

