fix(SDP): Add missing msid for p2p sources.

jitsi · May 25, 2021 · 4b25a6f · 4b25a6f
1 parent 1551193
commit 4b25a6f
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Showing 3 changed files with 67 additions and 1 deletion.
diff --git a/modules/sdp/LocalSdpMunger.js b/modules/sdp/LocalSdpMunger.js
@@ -203,9 +203,29 @@ export default class LocalSdpMunger {
         const msid = mediaSection.ssrcs.find(s => s.attribute === 'msid');
 
         if (!this.tpc.isP2P
-            && (!msid || mediaSection.direction === 'recvonly' || mediaSection.direction === 'inactive')) {
+            && (!msid
+                || mediaSection.mLine?.direction === 'recvonly'
+                || mediaSection.mLine?.direction === 'inactive')) {
             mediaSection.ssrcs = undefined;
             mediaSection.ssrcGroups = undefined;
+
+        // Add the msid attribute if it is missing for p2p sources. Firefox doesn't produce a a=ssrc line
+        // with msid attribute.
+        } else if (this.tpc.isP2P && mediaSection.mLine?.direction === 'sendrecv') {
+            const msidLine = mediaSection.mLine?.msid;
+            const trackId = msidLine && msidLine.split(' ')[1];
+            const sources = [ ...new Set(mediaSection.mLine?.ssrcs?.map(s => s.id)) ];
+
+            for (const source of sources) {
+                const msidExists = mediaSection.ssrcs
+                    .find(ssrc => ssrc.id === source && ssrc.attribute === 'msid');
+
+                !msidExists && mediaSection.ssrcs.push({
+                    id: source,
+                    attribute: 'msid',
+                    value: `${this.localEndpointId}-${mediaSection.mLine?.type}-${pcId} ${trackId}-${pcId}`
+                });
+            }
         }
     }
 

diff --git a/modules/sdp/LocalSdpMunger.spec.js b/modules/sdp/LocalSdpMunger.spec.js
@@ -76,5 +76,22 @@ describe('TransformRecvOnly', () => {
                 }
             }
         });
+
+        it('should add msid', () => {
+            // P2P case only.
+            localSdpMunger.tpc.isP2P = true;
+
+            const sdpStr = transform.write(SampleSdpStrings.firefoxP2pSdp);
+            const desc = new RTCSessionDescription({
+                type: 'offer',
+                sdp: sdpStr
+            });
+            const transformedDesc = localSdpMunger.transformStreamIdentifiers(desc);
+            const newSdp = transform.parse(transformedDesc.sdp);
+            const videoSsrcs = getSsrcLines(newSdp, 'video');
+            const msidExists = videoSsrcs.find(s => s.attribute === 'msid');
+
+            expect(msidExists).toBeDefined();
+        });
     });
 });
diff --git a/modules/sdp/SampleSdpStrings.js b/modules/sdp/SampleSdpStrings.js
@@ -359,6 +359,26 @@ const videoMlineFF = ''
 + 'a=ssrc:984899560 cname:peDGrDD6WsxUOki/\r\n'
 + 'a=rtcp-mux\r\n';
 
+const videoLineP2pFF = ''
++ 'm=video 9 RTP/SAVPF 100 96\r\n'
++ 'c=IN IP4 0.0.0.0\r\n'
++ 'a=rtpmap:100 VP8/90000\r\n'
++ 'a=fmtp:96 apt=100\r\n'
++ 'a=rtcp:9 IN IP4 0.0.0.0\r\n'
++ 'a=rtcp-fb:100 ccm fir\r\n'
++ 'a=rtcp-fb:100 nack\r\n'
++ 'a=rtcp-fb:100 nack pli\r\n'
++ 'a=rtcp-fb:100 goog-remb\r\n'
++ 'a=extmap:3 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time\r\n'
++ 'a=setup:passive\r\n'
++ 'a=mid:video\r\n'
++ 'a=sendrecv\r\n'
++ 'a=ice-ufrag:adPg\r\n'
++ 'a=ice-pwd:Xsr05Mq8S7CR44DAnusZE26F\r\n'
++ 'a=fingerprint:sha-256 6A:39:DE:11:24:AD:2E:4E:63:D6:69:D3:85:05:53:C7:3C:38:A4:B7:91:74:C0:91:44:FC:94:63:7F:01:AB:A9\r\n'
++ 'a=ssrc:984899560 cname:peDGrDD6WsxUOki/\r\n'
++ 'a=rtcp-mux\r\n';
+
 // A full sdp string representing a client doing simulcast
 const simulcastSdpStr = baseSessionSdp + baseAudioMLineSdp + simulcastVideoMLineSdp + baseDataMLineSdp;
 
@@ -380,8 +400,12 @@ const flexFecSdpStr = baseSessionSdp + baseAudioMLineSdp + flexFecVideoMLineSdp
 // A full sdp string representing a client that doesn't have local sources added on Firefox.
 const recvOnlySdpStr = baseSessionSdp + recvOnlyAudioMline + recvOnlyVideoMline;
 
+// A full sdp string representing a Firefox client with msid set to '-'.
 const sdpFirefoxStr = baseSessionSdp + baseAudioMLineSdp + videoMlineFF;
 
+// A full sdp string representing a Firefox client with missing msid attribute.
+const sdpFirefoxP2pStr = baseSessionSdp + baseAudioMLineSdp + videoLineP2pFF;
+
 export default {
     get simulcastSdp() {
         return transform.parse(simulcastSdpStr);
@@ -413,7 +437,12 @@ export default {
 
     get firefoxSdp() {
         return transform.parse(sdpFirefoxStr);
+    },
+
+    get firefoxP2pSdp() {
+        return transform.parse(sdpFirefoxP2pStr);
     }
+
 };
 
 /* eslint-enable max-len*/