transport_srtp: Allow multiple keying methods in SDP offer. Callee will select first available keying method.

Author: amubiera

pjmedia/src/pjmedia/transport_srtp.c

@@ -1892,11 +1892,6 @@ static pj_status_t transport_media_create(pjmedia_transport *tp,
             srtp->keying_cnt--;
             keying_status = st;
             continue;
-        } else if (srtp->offerer_side) {
-            /* Currently we can send one keying only in outgoing offer */
-            srtp->keying[0] = srtp->keying[i];
-            srtp->keying_cnt = 1;
-            break;
         }
 
         ++i;
@@ -2002,14 +1997,6 @@ static pj_status_t transport_encode_sdp(pjmedia_transport *tp,
         srtp->keying_cnt = 0;
     }
 
-    if (srtp->keying_cnt != 0) {
-        /* At this point for now, keying count should be 1 */
-        pj_assert(srtp->keying_cnt == 1);
-        PJ_LOG(4, (srtp->pool->obj_name, "SRTP uses keying method %s",
-                   ((int)srtp->keying[0]->type==PJMEDIA_SRTP_KEYING_SDES?
-                    "SDES":"DTLS-SRTP")));
-    }
-
     return PJ_SUCCESS;
 }
 
@@ -2027,9 +2014,6 @@ static pj_status_t transport_media_start(pjmedia_transport *tp,
 
     PJ_ASSERT_RETURN(tp, PJ_EINVAL);
 
-    /* At this point for now, keying count should be 0 or 1 */
-    pj_assert(srtp->keying_cnt <= 1);
-
     srtp->started = PJ_TRUE;
 
     status = pjmedia_transport_media_start(srtp->member_tp, pool,

pjmedia/src/pjmedia/transport_srtp_sdes.c

@@ -305,6 +305,11 @@ static pj_status_t sdes_media_create( pjmedia_transport *tp,
         /* Get transport protocol and drop any RTCP-FB flag */
         rem_proto = pjmedia_sdp_transport_get_proto(&m->desc.transport);
         PJMEDIA_TP_PROTO_TRIM_FLAG(rem_proto, PJMEDIA_TP_PROFILE_RTCP_FB);
+
+	    /* Drop DTLS proto if crypto is present */
+	    if (pjmedia_sdp_media_find_attr(m, &ID_CRYPTO, NULL) != NULL)
+            PJMEDIA_TP_PROTO_TRIM_FLAG(rem_proto, PJMEDIA_TP_PROTO_DTLS);
+
         if (rem_proto != PJMEDIA_TP_PROTO_RTP_AVP &&
             rem_proto != PJMEDIA_TP_PROTO_RTP_SAVP)
         {
@@ -361,6 +366,12 @@ static pj_status_t sdes_encode_sdp( pjmedia_transport *tp,
         /* Get transport protocol and drop any RTCP-FB flag */
         proto = pjmedia_sdp_transport_get_proto(&m->desc.transport);
         PJMEDIA_TP_PROTO_TRIM_FLAG(proto, PJMEDIA_TP_PROFILE_RTCP_FB);
+
+	    /* Drop DTLS proto if crypto is present */
+	    if (!srtp->offerer_side &&
+            pjmedia_sdp_media_find_attr(m, &ID_CRYPTO, NULL) != NULL)
+            PJMEDIA_TP_PROTO_TRIM_FLAG(proto, PJMEDIA_TP_PROTO_DTLS);
+
         if (proto != PJMEDIA_TP_PROTO_RTP_AVP &&
             proto != PJMEDIA_TP_PROTO_RTP_SAVP)
         {
@@ -444,6 +455,10 @@ static pj_status_t sdes_encode_sdp( pjmedia_transport *tp,
         rem_proto = pjmedia_sdp_transport_get_proto(&m_rem->desc.transport);
         PJMEDIA_TP_PROTO_TRIM_FLAG(rem_proto, PJMEDIA_TP_PROFILE_RTCP_FB);
 
+        /* Drop DTLS proto if crypto is present */
+        if (pjmedia_sdp_media_find_attr(m_rem, &ID_CRYPTO, NULL) != NULL)
+            PJMEDIA_TP_PROTO_TRIM_FLAG(rem_proto, PJMEDIA_TP_PROTO_DTLS);
+
         /* Generate transport */
         switch (srtp->setting.use) {
             case PJMEDIA_SRTP_DISABLED:
@@ -662,6 +677,11 @@ static pj_status_t sdes_media_start( pjmedia_transport *tp,
         /* Get transport protocol and drop any RTCP-FB flag */
         rem_proto = pjmedia_sdp_transport_get_proto(&m_rem->desc.transport);
         PJMEDIA_TP_PROTO_TRIM_FLAG(rem_proto, PJMEDIA_TP_PROFILE_RTCP_FB);
+
+	    /* Drop DTLS proto if crypto is present */
+	    if (pjmedia_sdp_media_find_attr(m_rem, &ID_CRYPTO, NULL) != NULL)
+            PJMEDIA_TP_PROTO_TRIM_FLAG(rem_proto, PJMEDIA_TP_PROTO_DTLS);
+
         if (rem_proto != PJMEDIA_TP_PROTO_RTP_AVP &&
             rem_proto != PJMEDIA_TP_PROTO_RTP_SAVP)
         {