index.js

var libnice = require("libnice");
var WebSocket = require('ws');
var transform = require('sdp-transform');

var ws_uri = "";

if(process.argv[2]){
  //quick and dirty; no validation
  ws_uri = process.argv[2];
}else{
  console.error("Required argument missing: node index.js <ws_uri>");
  console.error("Example: node index.js wss://127.0.0.1:8443/helloworld");
  process.exit();
}



//An audio-only SDP generated by Chrome.
//This contains some values we modify later on
var chromeSdp = "v=0\r\no=- 6531765081352225389 2 IN IP4 127.0.0.1\r\ns=-\r\nt=0 0\r\na=group:BUNDLE audio video\r\na=msid-semantic: WMS ZSXaL1I4ymOMSLQB4bzYQrRJ3uDk6Q3ww2nq\r\nm=audio 9 UDP/TLS/RTP/SAVPF 111 103 104 9 0 8 106 105 13 110 112 113 126\r\nc=IN IP4 0.0.0.0\r\na=rtcp:9 IN IP4 0.0.0.0\r\na=ice-ufrag:yASt\r\na=ice-pwd:y5tGa4TBBSnRAy7Gr8fjAEh7\r\na=fingerprint:sha-256 26:37:BF:39:10:F5:67:C5:A7:71:5A:91:BD:CF:9A:61:44:D0:5A:D9:32:06:FE:FA:0F:7B:84:42:EF:55:0C:F5\r\na=setup:actpass\r\na=mid:audio\r\na=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level\r\na=sendrecv\r\na=rtcp-mux\r\na=rtpmap:111 opus/48000/2\r\na=rtcp-fb:111 transport-cc\r\na=fmtp:111 minptime=10;useinbandfec=1\r\na=rtpmap:103 ISAC/16000\r\na=rtpmap:104 ISAC/32000\r\na=rtpmap:9 G722/8000\r\na=rtpmap:0 PCMU/8000\r\na=rtpmap:8 PCMA/8000\r\na=rtpmap:106 CN/32000\r\na=rtpmap:105 CN/16000\r\na=rtpmap:13 CN/8000\r\na=rtpmap:110 telephone-event/48000\r\na=rtpmap:112 telephone-event/32000\r\na=rtpmap:113 telephone-event/16000\r\na=rtpmap:126 telephone-event/8000\r\na=ssrc:1116726908 cname:wPe25fuDNItpo6aG\r\na=ssrc:1116726908 msid:ZSXaL1I4ymOMSLQB4bzYQrRJ3uDk6Q3ww2nq 504c5016-033a-43c6-8f11-1c81ddf1c5d6\r\na=ssrc:1116726908 mslabel:ZSXaL1I4ymOMSLQB4bzYQrRJ3uDk6Q3ww2nq\r\na=ssrc:1116726908 label:504c5016-033a-43c6-8f11-1c81ddf1c5d6\r\n";


var agent = new libnice.NiceAgent();
agent.setStunServer("74.125.143.127:19302"); // stun.l.google.com

var stream = agent.createStream(1);

//Let libnice generate the ice-ufrag and ice-pwd values for this session
var credentials = stream.getLocalCredentials();
console.log("credentials", credentials);

//Parse the Chrome SDP to be able to modify it easily
var sdp = transform.parse(chromeSdp);
console.log('sdp:', sdp);

//change the ice-ufrag and ice-pwd values
sdp.media[0].iceUfrag = credentials.ufrag;
sdp.media[0].icePwd = credentials.pwd;

//write the modified SDP to a string so we can send it to the other end
var localSdp = transform.write(sdp);

stream.on('gatheringDone', function(candidates) {
  console.log("gatheringDone", candidates);
  
  var ws = new WebSocket(ws_uri, {
    perMessageDeflate: false
  });

  ws.on('open', function open() {
    console.log("websocket open");
    ws.send(JSON.stringify({
      "id":"start",
      "sdpOffer":localSdp
    }));

    var candidates = stream.getLocalIceCandidates();
    console.log("candidates", candidates);

    for(var i=0; i<candidates.length; i++){
    
      var candidateMessage = {
        "id":"onIceCandidate",
        "candidate":{
          "candidate":candidates[i].substring(2), //strip of first 2 chars: a=
          "sdpMid":"audio",
          "sdpMLineIndex":0
        }
      };
      ws.send(JSON.stringify(candidateMessage));
    }
  });
     
  ws.on('message', function incoming(data) {
    console.log("websocket data", data);
    var parsedData = JSON.parse(data);
    
    if(parsedData.id == 'iceCandidate'){
      var candidate = parsedData.candidate.candidate;
      console.log("adding remote candidate", candidate);
      stream.addRemoteIceCandidate( "a="+candidate);
    }
    
    if(parsedData.id == 'startResponse'){
      var remoteSdp = transform.parse(parsedData.sdpAnswer);
      console.log('Remote sdp:', remoteSdp);
      stream.setRemoteCredentials(remoteSdp.media[0].iceUfrag, remoteSdp.media[0].icePwd);
    }
    
  });
    
});

stream.on('stateChanged', function(component, state) {
	console.log("stateChanged", component, state);
  // state is a string
});

stream.on('receive', function(component, data) {
    // data is a buffer
    console.log("receive", component, data);
    
    //echoing incoming data. This is where it all happens
    stream.send(1, data);
});

stream.on('ready', function(component, data) {
    // data is a buffer
    console.log("ready", component, data);
});

//kick off candidate gathering
stream.gatherCandidates();