MM-50415 - Fix addIceCandidate error due to potential race (#7104)

app/products/calls/rtcpeer/index.ts

@@ -7,12 +7,15 @@ import {EventEmitter} from 'events';
 import {
     MediaStream,
     MediaStreamTrack,
+    RTCIceCandidate,
     RTCPeerConnection,
     RTCPeerConnectionIceEvent,
     RTCRtpSender,
     RTCSessionDescription,
 } from 'react-native-webrtc';
 
+import {logDebug, logError} from '@utils/log';
+
 import type {RTCPeerConfig} from './types';
 import type RTCTrackEvent from 'react-native-webrtc/lib/typescript/RTCTrackEvent';
 
@@ -21,6 +24,7 @@ const rtcConnFailedErr = new Error('rtc connection failed');
 export default class RTCPeer extends EventEmitter {
     private pc: RTCPeerConnection | null;
     private readonly senders: { [key: string]: RTCRtpSender };
+    private candidates: RTCIceCandidate[] = [];
 
     public connected: boolean;
 
@@ -113,7 +117,17 @@ export default class RTCPeer extends EventEmitter {
         try {
             switch (msg.type) {
                 case 'candidate':
-                    await this.pc.addIceCandidate(msg.candidate);
+                    // It's possible that ICE candidates are received moments before
+                    // we set the initial remote description which would cause an
+                    // error. In such case we queue them up to be added later.
+                    if (this.pc.remoteDescription && this.pc.remoteDescription.type) {
+                        this.pc.addIceCandidate(msg.candidate).catch((err) => {
+                            logError('failed to add candidate', err);
+                        });
+                    } else {
+                        logDebug('received ice candidate before remote description, queuing...');
+                        this.candidates.push(msg.candidate);
+                    }
                     break;
                 case 'offer':
                     await this.pc.setRemoteDescription(new RTCSessionDescription(msg));
@@ -122,6 +136,12 @@ export default class RTCPeer extends EventEmitter {
                     break;
                 case 'answer':
                     await this.pc.setRemoteDescription(msg);
+                    for (const candidate of this.candidates) {
+                        logDebug('adding queued ice candidate');
+                        this.pc.addIceCandidate(candidate).catch((err) => {
+                            logError('failed to add candidate', err);
+                        });
+                    }
                     break;
                 default:
                     this.emit('error', Error('invalid signaling data received'));