bigbluebutton-Github/bigbluebutton-html5/imports/ui/services/webrtc-base/peer.js

import { EventEmitter2 } from 'eventemitter2';
import {
  stopStream,
  stopTrack,
  silentConsole,
} from '/imports/ui/services/webrtc-base/utils';

export default class WebRtcPeer extends EventEmitter2 {
  constructor(mode, options = {}) {
    super({ newListener: true });

    this.mode = mode;

    this.options = options;
    this.peerConnection = this.options.peerConnection;
    this.videoStream = this.options.videoStream;
    this.audioStream = this.options.audioStream;
    this.mediaConstraints = this.options.mediaConstraints;
    this.trace = this.options.trace;
    this.configuration = this.options.configuration;
    this.onicecandidate = this.options.onicecandidate;
    this.oncandidategatheringdone = this.options.oncandidategatheringdone;
    this.candidateGatheringDone = false;

    this._outboundCandidateQueue = [];
    this._inboundCandidateQueue = [];
    this._handleIceCandidate = this._handleIceCandidate.bind(this);
    this._handleSignalingStateChange = this._handleSignalingStateChange.bind(this);

    if (this.onicecandidate) this.on('icecandidate', this.onicecandidate);
    if (this.oncandidategatheringdone) this.on('candidategatheringdone', this.oncandidategatheringdone);
  }

  _flushInboundCandidateQueue() {
    while (this._inboundCandidateQueue.length) {
      const entry = this._inboundCandidateQueue.shift();
      if (entry.candidate && entry.promise) {
        try {
          if (this.isPeerConnectionClosed()) {
            entry.promise.resolve();
          } else {
            this.peerConnection.addIceCandidate(entry.candidate)
              .then(entry.promise.resolve)
              .catch(entry.promise.reject);
          }
        } catch (error) {
          entry.promise.reject(error);
        }
      }
    }
  }

  _trackQueueFlushEvents() {
    this.on('newListener', (event) => {
      if (event === 'icecandidate' || event === 'candidategatheringdone') {
        while (this._outboundCandidateQueue.length) {
          const candidate = this._outboundCandidateQueue.shift();

          if (!candidate) this._emitCandidateGatheringDone();
        }
      }
    });

    this.peerConnection?.addEventListener('signalingstatechange', this._handleSignalingStateChange);
  }

  _emitCandidateGatheringDone() {
    if (!this.candidateGatheringDone) {
      this.emit('candidategatheringdone');
      this.candidateGatheringDone = true;
    }
  }

  _handleIceCandidate({ candidate }) {
    if (this.hasListeners('icecandidate') || this.hasListeners('candidategatheringdone')) {
      if (candidate) {
        this.emit('icecandidate', candidate);
        this.candidateGatheringDone = false;
      } else this._emitCandidateGatheringDone();
    } else if (!this.candidateGatheringDone) {
      this._outboundCandidateQueue.push(candidate);
      if (!candidate) this.candidateGatheringDone = true;
    }
  }

  _handleSignalingStateChange() {
    if (this.peerConnection?.signalingState === 'stable') {
      this._flushInboundCandidateQueue();
    }
  }

  set peerConnection(pc) {
    this._pc = pc;
  }

  get peerConnection() {
    return this._pc;
  }

  get logger() {
    if (this.trace) return console;
    return silentConsole;
  }

  getLocalSessionDescriptor() {
    return this.peerConnection?.localDescription;
  }

  getRemoteSessionDescriptor() {
    return this.peerConnection?.remoteDescription;
  }

  getLocalStream() {
    if (this.localStream) {
      return this.localStream;
    }

    if (this.peerConnection) {
      this.localStream = new MediaStream();
      const senders = this.peerConnection.getSenders();
      senders.forEach(({ track }) => {
        if (track) {
          this.localStream.addTrack(track);
        }
      });

      return this.localStream;
    }

    return null;
  }

  getRemoteStream() {
    if (this.remoteStream) {
      return this.remoteStream;
    }

    if (this.peerConnection) {
      this.remoteStream = new MediaStream();
      this.peerConnection.getReceivers().forEach(({ track }) => {
        if (track) {
          this.remoteStream.addTrack(track);
        }
      });
      return this.remoteStream;
    }

    return null;
  }

  isPeerConnectionClosed() {
    return !this.peerConnection || this.peerConnection.signalingState === 'closed';
  }

  start() {
    // Init PeerConnection
    if (!this.peerConnection) {
      this.peerConnection = new RTCPeerConnection(this.configuration);
    }

    if (this.isPeerConnectionClosed()) {
      this.logger.trace('BBB::WebRtcPeer::start - peer connection closed');
      throw new Error('Invalid peer state: closed');
    }

    this.peerConnection.addEventListener('icecandidate', this._handleIceCandidate);
    this._trackQueueFlushEvents();

    if (this.videoStream) {
      this.videoStream.getTracks().forEach((track) => {
        this.peerConnection.addTrack(track, this.videoStream);
      });
    }

    if (this.audioStream) {
      this.audioStream.getTracks().forEach((track) => {
        this.peerConnection.addTrack(track, this.audioStream);
      });
    }
  }

  addIceCandidate(iceCandidate) {
    const candidate = new RTCIceCandidate(iceCandidate);

    switch (this.peerConnection?.signalingState) {
      case 'closed':
        this.logger.trace('BBB::WebRtcPeer::addIceCandidate - peer connection closed');
        throw new Error('PeerConnection object is closed');
      case 'stable': {
        if (this.peerConnection.remoteDescription) {
          this.logger.debug('BBB::WebRtcPeer::addIceCandidate - adding candidate', candidate);
          return this.peerConnection.addIceCandidate(candidate);
        }
      }
      // eslint-ignore-next-line no-fallthrough
      default: {
        this.logger.debug('BBB::WebRtcPeer::addIceCandidate - buffering inbound candidate', candidate);
        const promise = new Promise();
        this._inboundCandidateQueue.push({
          candidate,
          promise,
        });
        return promise;
      }
    }
  }

  generateOffer() {
    switch (this.mode) {
      case 'recvonly': {
        const useAudio = this.mediaConstraints
        && ((typeof this.mediaConstraints.audio === 'boolean')
          || (typeof this.mediaConstraints.audio === 'object'));
        const useVideo = this.mediaConstraints
        && ((typeof this.mediaConstraints.video === 'boolean')
          || (typeof this.mediaConstraints.video === 'object'));

        if (useAudio) {
          this.peerConnection.addTransceiver('audio', {
            direction: 'recvonly',
          });
        }

        if (useVideo) {
          this.peerConnection.addTransceiver('video', {
            direction: 'recvonly',
          });
        }
        break;
      }

      case 'sendonly': {
        this.peerConnection.getTransceivers().forEach((transceiver) => {
          // eslint-disable-next-line no-param-reassign
          transceiver.direction = 'sendonly';
        });
        break;
      }

      default:
        break;
    }

    return this.peerConnection.createOffer()
      .then((offer) => {
        this.logger.debug('BBB::WebRtcPeer::generateOffer - created offer', offer);
        return this.peerConnection.setLocalDescription(offer);
      })
      .then(() => {
        const localDescription = this.getLocalSessionDescriptor();
        this.logger.debug('BBB::WebRtcPeer::generateOffer - local description set', localDescription);
        return localDescription.sdp;
      });
  }

  processAnswer(sdp) {
    const answer = new RTCSessionDescription({
      type: 'answer',
      sdp,
    });

    if (this.isPeerConnectionClosed()) {
      this.logger.error('BBB::WebRtcPeer::processAnswer - peer connection closed');
      throw new Error('Peer connection is closed');
    }

    this.logger.debug('BBB::WebRtcPeer::processAnswer - setting remote description');

    return this.peerConnection.setRemoteDescription(answer);
  }

  processOffer(sdp) {
    const offer = new RTCSessionDescription({
      type: 'offer',
      sdp,
    });

    if (this.isPeerConnectionClosed()) {
      this.logger.error('BBB::WebRtcPeer::processOffer - peer connection closed');
      throw new Error('Peer connection is closed');
    }

    this.logger.debug('BBB::WebRtcPeer::processOffer - setting remote description', offer);

    return this.peerConnection.setRemoteDescription(offer)
      .then(() => this.peerConnection.createAnswer())
      .then((answer) => {
        this.logger.debug('BBB::WebRtcPeer::processOffer - created answer', answer);
        return this.peerConnection.setLocalDescription(answer);
      })
      .then(() => {
        const localDescription = this.getLocalSessionDescriptor();
        this.logger.debug('BBB::WebRtcPeer::processOffer - local description set', localDescription.sdp);
        return localDescription.sdp;
      });
  }

  dispose() {
    this.logger.debug('BBB::WebRtcPeer::dispose');

    try {
      if (this.peerConnection) {
        this.peerConnection.getSenders().forEach(({ track }) => stopTrack(track));
        if (!this.isPeerConnectionClosed()) this.peerConnection.close();
        this.peerConnection = null;
      }

      if (this.localStream) {
        stopStream(this.localStream);
        this.localStream = null;
      }

      if (this.remoteStream) {
        stopStream(this.remoteStream);
        this.remoteStream = null;
      }

      this._outboundCandidateQueue = [];
      this.candidateGatheringDone = false;
    } catch (error) {
      this.logger.trace('BBB::WebRtcPeer::dispose - failed', error);
    }

    this.removeAllListeners();
  }
}