chan_sip: Better ICE handling for RTCP-MUX

If we are offered or are offering RTCP-MUX, don't consider RTCP ICE
candidates. This confuses certain browsers (current Firefox for
example) and causes intial audio setup delays.

ASTERISK-26982 #close

Change-Id: Ifeaf47e83972fe8dbe58b7fb3d6d1823400cfb91

diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 43084cebb64223ea7b55e03c737316278a593de7..1994103288e18df85bf64914b32541965c7aa1d3 100644 (file)
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -1210,7 +1210,7 @@ static int process_sdp(struct sip_pvt *p, struct sip_request *req, int t38action
 static int process_sdp_o(const char *o, struct sip_pvt *p);
 static int process_sdp_c(const char *c, struct ast_sockaddr *addr);
 static int process_sdp_a_sendonly(const char *a, int *sendonly);
-static int process_sdp_a_ice(const char *a, struct sip_pvt *p, struct ast_rtp_instance *instance);
+static int process_sdp_a_ice(const char *a, struct sip_pvt *p, struct ast_rtp_instance *instance, int rtcp_mux);
 static int process_sdp_a_rtcp_mux(const char *a, struct sip_pvt *p, int *requested);
 static int process_sdp_a_dtls(const char *a, struct sip_pvt *p, struct ast_rtp_instance *instance);
 static int process_sdp_a_audio(const char *a, struct sip_pvt *p, struct ast_rtp_codecs *newaudiortp, int *last_rtpmap_codec);
@@ -10144,6 +10144,24 @@ static void set_ice_components(struct sip_pvt *p, struct ast_rtp_instance *insta
        }
 }
 
+static int has_media_level_attribute(int start, struct sip_request *req, const char *attr)
+{
+       int next = start;
+       char type;
+       const char *value;
+
+       /* We don't care about the return result here */
+       get_sdp_iterate(&next, req, "m");
+
+       while ((type = get_sdp_line(&start, next, req, &value)) != '\0') {
+               if (type == 'a' && !strcasecmp(value, attr)) {
+                       return 1;
+               }
+       }
+
+       return 0;
+}
+
 /*! \brief Process SIP SDP offer, select formats and activate media channels
        If offer is rejected, we will not change any properties of the call
        Return 0 on success, a negative value on errors.
@@ -10286,13 +10304,13 @@ static int process_sdp(struct sip_pvt *p, struct sip_request *req, int t38action
                        else if (process_sdp_a_image(value, p))
                                processed = TRUE;
 
-                       if (process_sdp_a_ice(value, p, p->rtp)) {
+                       if (process_sdp_a_ice(value, p, p->rtp, 0)) {
                                processed = TRUE;
                        }
-                       if (process_sdp_a_ice(value, p, p->vrtp)) {
+                       if (process_sdp_a_ice(value, p, p->vrtp, 0)) {
                                processed = TRUE;
                        }
-                       if (process_sdp_a_ice(value, p, p->trtp)) {
+                       if (process_sdp_a_ice(value, p, p->trtp, 0)) {
                                processed = TRUE;
                        }
 
@@ -10332,6 +10350,7 @@ static int process_sdp(struct sip_pvt *p, struct sip_request *req, int t38action
                int image = FALSE;
                int text = FALSE;
                int processed_crypto = FALSE;
+               int rtcp_mux_offered = 0;
                char protocol[18] = {0,};
                unsigned int x;
                struct ast_rtp_engine_dtls *dtls;
@@ -10351,6 +10370,9 @@ static int process_sdp(struct sip_pvt *p, struct sip_request *req, int t38action
                AST_LIST_INSERT_TAIL(&p->offered_media, offer, next);
                offer->type = SDP_UNKNOWN;
 
+               /* We need to check for this ahead of time */
+               rtcp_mux_offered = has_media_level_attribute(iterator, req, "rtcp-mux");
+
                /* Check for 'audio' media offer */
                if (strncmp(m, "audio ", 6) == 0) {
                        if ((sscanf(m, "audio %30u/%30u %17s %n", &x, &numberofports, protocol, &len) == 3 && len > 0) ||
@@ -10717,7 +10739,7 @@ static int process_sdp(struct sip_pvt *p, struct sip_request *req, int t38action
                        case 'a':
                                /* Audio specific scanning */
                                if (audio) {
-                                       if (process_sdp_a_ice(value, p, p->rtp)) {
+                                       if (process_sdp_a_ice(value, p, p->rtp, rtcp_mux_offered)) {
                                                processed = TRUE;
                                        } else if (process_sdp_a_dtls(value, p, p->rtp)) {
                                                processed_crypto = TRUE;
@@ -10738,7 +10760,7 @@ static int process_sdp(struct sip_pvt *p, struct sip_request *req, int t38action
                                }
                                /* Video specific scanning */
                                else if (video) {
-                                       if (process_sdp_a_ice(value, p, p->vrtp)) {
+                                       if (process_sdp_a_ice(value, p, p->vrtp, rtcp_mux_offered)) {
                                                processed = TRUE;
                                        } else if (process_sdp_a_dtls(value, p, p->vrtp)) {
                                                processed_crypto = TRUE;
@@ -10757,7 +10779,7 @@ static int process_sdp(struct sip_pvt *p, struct sip_request *req, int t38action
                                }
                                /* Text (T.140) specific scanning */
                                else if (text) {
-                                       if (process_sdp_a_ice(value, p, p->trtp)) {
+                                       if (process_sdp_a_ice(value, p, p->trtp, rtcp_mux_offered)) {
                                                processed = TRUE;
                                        } else if (process_sdp_a_text(value, p, &newtextrtp, red_fmtp, &red_num_gen, red_data_pt, &last_rtpmap_codec)) {
                                                processed = TRUE;
@@ -11269,7 +11291,7 @@ static int process_sdp_a_sendonly(const char *a, int *sendonly)
        return found;
 }
 
-static int process_sdp_a_ice(const char *a, struct sip_pvt *p, struct ast_rtp_instance *instance)
+static int process_sdp_a_ice(const char *a, struct sip_pvt *p, struct ast_rtp_instance *instance, int rtcp_mux_offered)
 {
        struct ast_rtp_engine_ice *ice;
        int found = FALSE;
@@ -11289,6 +11311,12 @@ static int process_sdp_a_ice(const char *a, struct sip_pvt *p, struct ast_rtp_in
                found = TRUE;
        } else if (sscanf(a, "candidate: %31s %30u %3s %30u %23s %30u typ %5s %*s %23s %*s %30u", foundation, &candidate.id, transport, (unsigned *)&candidate.priority,
                          address, &port, cand_type, relay_address, &relay_port) >= 7) {
+
+               if (rtcp_mux_offered && ast_test_flag(&p->flags[2], SIP_PAGE3_RTCP_MUX) && candidate.id > 1) {
+                       /* If we support RTCP-MUX and they offered it, don't consider RTCP candidates */
+                       return TRUE;
+               }
+
                candidate.foundation = foundation;
                candidate.transport = transport;