fix(peerconnection): create a new description to modify sdp (#631)

Firefox has deprecated modifying a description's sdp through
re-assignment. Safari (without temasys) does not allow it.
As such, wherever the sdp has to be modified instead create
a new description with the modified sdp.

modules/RTC/LocalSdpMunger.js

@@ -169,19 +169,19 @@ export default class LocalSdpMunger {
      * description.
      */
     maybeMungeLocalSdp(desc) {
-        // Nothing to be done in early stage when localDescription
-        // is not available yet
-        if (!desc || !desc.sdp) {
-            return;
+        if (!desc || !(desc instanceof RTCSessionDescription)) {
+            throw new Error('Incorrect type, expected RTCSessionDescription');
         }
 
         const transformer = new SdpTransformWrap(desc.sdp);
 
         if (this._addMutedLocalVideoTracksToSDP(transformer)) {
-            // Write
-            desc.sdp = transformer.toRawSDP();
-
-            // logger.info("Post TRANSFORM: ", desc.sdp);
+            return new RTCSessionDescription({
+                type: desc.type,
+                sdp: transformer.toRawSDP()
+            });
         }
+
+        return desc;
     }
 }

modules/RTC/TraceablePeerConnection.js

@@ -1075,26 +1075,35 @@ const normalizePlanB = function(desc) {
  * @param {Object} localDescription the SDP object as defined by WebRTC.
  */
 const enforceSendRecv = function(localDescription) {
-    if (localDescription && localDescription.sdp) {
-        const transformer = new SdpTransformWrap(localDescription.sdp);
-        const audioMedia = transformer.selectMedia('audio');
-        let changed = false;
-
-        if (audioMedia && audioMedia.direction !== 'sendrecv') {
-            audioMedia.direction = 'sendrecv';
-            changed = true;
-        }
-        const videoMedia = transformer.selectMedia('video');
+    if (!localDescription
+        || !(localDescription instanceof RTCSessionDescription)) {
+        throw new Error('Incorrect type, expected RTCSessionDescription');
+    }
 
-        if (videoMedia && videoMedia.direction !== 'sendrecv') {
-            videoMedia.direction = 'sendrecv';
-            changed = true;
-        }
+    const transformer = new SdpTransformWrap(localDescription.sdp);
+    const audioMedia = transformer.selectMedia('audio');
+    let changed = false;
 
-        if (changed) {
-            localDescription.sdp = transformer.toRawSDP();
-        }
+    if (audioMedia && audioMedia.direction !== 'sendrecv') {
+        audioMedia.direction = 'sendrecv';
+        changed = true;
     }
+
+    const videoMedia = transformer.selectMedia('video');
+
+    if (videoMedia && videoMedia.direction !== 'sendrecv') {
+        videoMedia.direction = 'sendrecv';
+        changed = true;
+    }
+
+    if (changed) {
+        return new RTCSessionDescription({
+            type: localDescription.type,
+            sdp: transformer.toRawSDP()
+        });
+    }
+
+    return localDescription;
 };
 
 /**
@@ -1146,9 +1155,11 @@ TraceablePeerConnection.prototype._injectSsrcGroupForUnifiedSimulcast
                 ssrcs: ssrcs.join(' ')
             });
         }
-        desc.sdp = transform.write(sdp);
 
-        return desc;
+        return new RTCSessionDescription({
+            type: desc.type,
+            sdp: transform.write(sdp)
+        });
     };
 
 /* eslint-disable-next-line vars-on-top */
@@ -1169,13 +1180,14 @@ const getters = {
             desc = this.interop.toPlanB(desc);
             this.trace('getLocalDescription::postTransform (Plan B)',
                 dumpSDP(desc));
+
             desc = this._injectSsrcGroupForUnifiedSimulcast(desc);
             this.trace('getLocalDescription::postTransform (inject ssrc group)',
                 dumpSDP(desc));
         }
 
         if (RTCBrowserType.doesVideoMuteByStreamRemove()) {
-            this.localSdpMunger.maybeMungeLocalSdp(desc);
+            desc = this.localSdpMunger.maybeMungeLocalSdp(desc);
             logger.debug(
                 'getLocalDescription::postTransform (munge local SDP)', desc);
         }
@@ -1188,7 +1200,7 @@ const getters = {
         // Note that the description we set in chrome does have the accurate
         // direction (e.g. 'recvonly'), since that is technically what is
         // happening (check setLocalDescription impl).
-        enforceSendRecv(desc);
+        desc = enforceSendRecv(desc);
 
         return desc || {};
     },
@@ -1499,7 +1511,7 @@ TraceablePeerConnection.prototype._ensureSimulcastGroupIsLast = function(
     if (simStartIndex === -1
         || otherStartIndex === -1
         || otherStartIndex === simStartIndex) {
-        return;
+        return localSdp;
     }
 
     const simEndIndex = sdpStr.indexOf('\r\n', simStartIndex);
@@ -1514,7 +1526,10 @@ TraceablePeerConnection.prototype._ensureSimulcastGroupIsLast = function(
 
     sdpStr = `${sdpHead}\r\n${simStrTrimmed}${sdpTail}`;
 
-    localSdp.sdp = sdpStr;
+    return new RTCSessionDescription({
+        type: localSdp.type,
+        sdp: sdpStr
+    });
 };
 
 /**
@@ -1562,8 +1577,13 @@ TraceablePeerConnection.prototype._adjustLocalMediaDirection = function(
     }
 
     if (modifiedDirection) {
-        localDescription.sdp = transformer.toRawSDP();
+        return new RTCSessionDescription({
+            type: localDescription.type,
+            sdp: transformer.toRawSDP()
+        });
     }
+
+    return localDescription;
 };
 
 TraceablePeerConnection.prototype.setLocalDescription = function(
@@ -1584,15 +1604,18 @@ TraceablePeerConnection.prototype.setLocalDescription = function(
             SDPUtil.preferVideoCodec(videoMLine, 'h264');
         }
 
-        localSdp.sdp = transform.write(parsedSdp);
+        localSdp = new RTCSessionDescription({
+            type: localSdp.type,
+            sdp: transform.write(parsedSdp)
+        });
 
         this.trace('setLocalDescription::postTransform (H264)',
             dumpSDP(localSdp));
     }
 
-    this._adjustLocalMediaDirection(localSdp);
+    localSdp = this._adjustLocalMediaDirection(localSdp);
 
-    this._ensureSimulcastGroupIsLast(localSdp);
+    localSdp = this._ensureSimulcastGroupIsLast(localSdp);
 
     // if we're using unified plan, transform to it first.
     if (RTCBrowserType.usesUnifiedPlan()) {
@@ -1680,9 +1703,11 @@ TraceablePeerConnection.prototype._insertUnifiedPlanSimulcastReceive
         video.simulcast_03 = {
             value: `recv rid=${SIM_LAYER_RIDS.join(';')}`
         };
-        desc.sdp = transform.write(sdp);
 
-        return desc;
+        return new RTCSessionDescription({
+            type: desc.type,
+            sdp: transform.write(sdp)
+        });
     };
 
 TraceablePeerConnection.prototype.setRemoteDescription = function(
@@ -1703,12 +1728,22 @@ TraceablePeerConnection.prototype.setRemoteDescription = function(
         const videoMLine = parsedSdp.media.find(m => m.type === 'video');
 
         SDPUtil.preferVideoCodec(videoMLine, 'h264');
-        description.sdp = transform.write(parsedSdp);
+
+        // eslint-disable-next-line no-param-reassign
+        description = new RTCSessionDescription({
+            type: description.type,
+            sdp: transform.write(parsedSdp)
+        });
     }
 
     // If the browser uses unified plan, transform to it first
     if (RTCBrowserType.usesUnifiedPlan()) {
-        description.sdp = this.rtxModifier.stripRtx(description.sdp);
+        // eslint-disable-next-line no-param-reassign
+        description = new RTCSessionDescription({
+            type: description.type,
+            sdp: this.rtxModifier.stripRtx(description.sdp)
+        });
+
         this.trace(
             'setRemoteDescription::postTransform (stripRtx)',
             dumpSDP(description));
@@ -1976,9 +2011,14 @@ TraceablePeerConnection.prototype._createOfferOrAnswer = function(
                     && !this.sdpConsistency.hasPrimarySsrcCached()) {
                     this.generateRecvonlySsrc();
                 }
-                resultSdp.sdp
-                    = this.sdpConsistency.makeVideoPrimarySsrcsConsistent(
-                        resultSdp.sdp);
+
+                // eslint-disable-next-line no-param-reassign
+                resultSdp = new RTCSessionDescription({
+                    type: resultSdp.type,
+                    sdp: this.sdpConsistency.makeVideoPrimarySsrcsConsistent(
+                        resultSdp.sdp)
+                });
+
                 this.trace(
                     `create${logName}OnSuccess::postTransform `
                          + '(make primary audio/video ssrcs consistent)',
@@ -1997,8 +2037,12 @@ TraceablePeerConnection.prototype._createOfferOrAnswer = function(
             }
 
             if (!this.options.disableRtx && RTCBrowserType.supportsRtx()) {
-                resultSdp.sdp
-                    = this.rtxModifier.modifyRtxSsrcs(resultSdp.sdp);
+                // eslint-disable-next-line no-param-reassign
+                resultSdp = new RTCSessionDescription({
+                    type: resultSdp.type,
+                    sdp: this.rtxModifier.modifyRtxSsrcs(resultSdp.sdp)
+                });
+
                 this.trace(
                     `create${logName}`
                          + 'OnSuccess::postTransform (rtx modifier)',
@@ -2013,7 +2057,12 @@ TraceablePeerConnection.prototype._createOfferOrAnswer = function(
                 const localDescription = new SDP(resultSdp.sdp);
 
                 _fixAnswerRFC4145Setup(remoteDescription, localDescription);
-                resultSdp.sdp = localDescription.raw;
+
+                // eslint-disable-next-line no-param-reassign
+                resultSdp = new RTCSessionDescription({
+                    type: resultSdp.type,
+                    sdp: localDescription.raw
+                });
             }
 
             const ssrcMap = extractSSRCMap(resultSdp);