RTCPeerConnection.prototype.setLocalDescription = function()

in monitoring-stack-cdk/resources/frontend/connect-rtc.js [3642:3734]
75 lines of code
16 McCabe index (conditional complexity)

      RTCPeerConnection.prototype.setLocalDescription = function(description) {
        var pc = this;
    
        // Note: pranswer is not supported.
        if (['offer', 'answer'].indexOf(description.type) === -1) {
          return Promise.reject(makeError('TypeError',
              'Unsupported type "' + description.type + '"'));
        }
    
        if (!isActionAllowedInSignalingState('setLocalDescription',
            description.type, pc.signalingState) || pc._isClosed) {
          return Promise.reject(makeError('InvalidStateError',
              'Can not set local ' + description.type +
              ' in state ' + pc.signalingState));
        }
    
        var sections;
        var sessionpart;
        if (description.type === 'offer') {
          // VERY limited support for SDP munging. Limited to:
          // * changing the order of codecs
          sections = SDPUtils.splitSections(description.sdp);
          sessionpart = sections.shift();
          sections.forEach(function(mediaSection, sdpMLineIndex) {
            var caps = SDPUtils.parseRtpParameters(mediaSection);
            pc.transceivers[sdpMLineIndex].localCapabilities = caps;
          });
    
          pc.transceivers.forEach(function(transceiver, sdpMLineIndex) {
            pc._gather(transceiver.mid, sdpMLineIndex);
          });
        } else if (description.type === 'answer') {
          sections = SDPUtils.splitSections(pc._remoteDescription.sdp);
          sessionpart = sections.shift();
          var isIceLite = SDPUtils.matchPrefix(sessionpart,
              'a=ice-lite').length > 0;
          sections.forEach(function(mediaSection, sdpMLineIndex) {
            var transceiver = pc.transceivers[sdpMLineIndex];
            var iceGatherer = transceiver.iceGatherer;
            var iceTransport = transceiver.iceTransport;
            var dtlsTransport = transceiver.dtlsTransport;
            var localCapabilities = transceiver.localCapabilities;
            var remoteCapabilities = transceiver.remoteCapabilities;
    
            // treat bundle-only as not-rejected.
            var rejected = SDPUtils.isRejected(mediaSection) &&
                SDPUtils.matchPrefix(mediaSection, 'a=bundle-only').length === 0;
    
            if (!rejected && !transceiver.rejected) {
              var remoteIceParameters = SDPUtils.getIceParameters(
                  mediaSection, sessionpart);
              var remoteDtlsParameters = SDPUtils.getDtlsParameters(
                  mediaSection, sessionpart);
              if (isIceLite) {
                remoteDtlsParameters.role = 'server';
              }
    
              if (!pc.usingBundle || sdpMLineIndex === 0) {
                pc._gather(transceiver.mid, sdpMLineIndex);
                if (iceTransport.state === 'new') {
                  iceTransport.start(iceGatherer, remoteIceParameters,
                      isIceLite ? 'controlling' : 'controlled');
                }
                if (dtlsTransport.state === 'new') {
                  dtlsTransport.start(remoteDtlsParameters);
                }
              }
    
              // Calculate intersection of capabilities.
              var params = getCommonCapabilities(localCapabilities,
                  remoteCapabilities);
    
              // Start the RTCRtpSender. The RTCRtpReceiver for this
              // transceiver has already been started in setRemoteDescription.
              pc._transceive(transceiver,
                  params.codecs.length > 0,
                  false);
            }
          });
        }
    
        pc._localDescription = {
          type: description.type,
          sdp: description.sdp
        };
        if (description.type === 'offer') {
          pc._updateSignalingState('have-local-offer');
        } else {
          pc._updateSignalingState('stable');
        }
    
        return Promise.resolve();
      };