Improve SDP offer/answer RFC compliance

Asterisk should not accept SDP offers that contain unknown RTP profiles (for
audio/video streams) or unknown top-level media types. When it does, it answers
with an SDP that does not match the offer properly, and this will nearly
always result in a broken call. This patch causes such offers to be rejected.

Review: https://reviewboard.asterisk.org/r/1811/



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@368269 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -9225,7 +9225,8 @@ static int process_sdp(struct sip_pvt *p, struct sip_request *req, int t38action
 					secure_audio = 1;
 				} else if (strcmp(protocol, "AVP")) {
 					ast_log(LOG_WARNING, "Unknown RTP profile in audio offer: %s\n", m);
-					continue;
+					res = -1;
+					goto process_sdp_cleanup;
 				}
 				if (p->offered_media[SDP_AUDIO].order_offered) {
@@ -9277,7 +9278,8 @@ static int process_sdp(struct sip_pvt *p, struct sip_request *req, int t38action
 					secure_video = 1;
 				} else if (strcmp(protocol, "AVP")) {
 					ast_log(LOG_WARNING, "Unknown RTP profile in video offer: %s\n", m);
-					continue;
+					res = -1;
+					goto process_sdp_cleanup;
 				}
 				if (p->offered_media[SDP_VIDEO].order_offered) {
@@ -9398,7 +9400,8 @@ static int process_sdp(struct sip_pvt *p, struct sip_request *req, int t38action
 			}
 		} else {
 			ast_log(LOG_WARNING, "Unsupported top-level media type in offer: %s\n", m);
-			continue;
+			res = -1;
+			goto process_sdp_cleanup;
 		}
 		/* Media stream specific parameters */