WebRTC Peerconnection: Which IP flow of candidates set is used?

Question

I am currently working on a monitoring tool for webrtc sessions investigating into the transferred SDP from caller to callee and vice versa. Unfortunately I cannot figure out which ip flow is really used since there are >10 candidate lines per session establishment and somehow the session is established after some candidates are pushed inside the PC.

Is there any way to figure out which flow is being used of the set of candidate flows?

Answer 1

I solved the issue by myself! :)

There is a function called peerConnection.getStats(callback);

This will give a lot of information of the ongoing peerconnection.

• Example: http://webrtc.googlecode.com/svn/trunk/samples/js/demos/html/constraints-and-stats.html
• W3C Standard Description: http://dev.w3.org/2011/webrtc/editor/webrtc.html#statistics-model

Bye

Answer 2

I wanted to find out the same thing, so wrote a small funtion which returns a promise which resolves to candidate details:

function getConnectionDetails(peerConnection){


  var connectionDetails = {};   // the final result object.

  if(window.chrome){  // checking if chrome

    var reqFields = [   'googLocalAddress',
                        'googLocalCandidateType',   
                        'googRemoteAddress',
                        'googRemoteCandidateType'
                    ];
    return new Promise(function(resolve, reject){
      peerConnection.getStats(function(stats){
        var filtered = stats.result().filter(function(e){return e.id.indexOf('Conn-audio')==0 && e.stat('googActiveConnection')=='true'})[0];
        if(!filtered) return reject('Something is wrong...');
        reqFields.forEach(function(e){connectionDetails[e.replace('goog', '')] = filtered.stat(e)});
        resolve(connectionDetails);
      });
    });

  }else{  // assuming it is firefox
    var stream = peerConnection.getLocalStreams()[0];
    if(!stream || !stream.getTracks()[0]) stream = peerConnection.getRemoteStreams()[0];
    if(!stream) Promise.reject('no stream found')
    var track = stream.getTracks()[0];
    if(!track)  Promise.reject('No Media Tracks Found');
    return peerConnection.getStats(track).then(function(stats){
        var selectedCandidatePair = stats[Object.keys(stats).filter(function(key){return stats[key].selected})[0]]
          , localICE = stats[selectedCandidatePair.localCandidateId]
          , remoteICE = stats[selectedCandidatePair.remoteCandidateId];
        connectionDetails.LocalAddress = [localICE.ipAddress, localICE.portNumber].join(':');
        connectionDetails.RemoteAddress = [remoteICE.ipAddress, remoteICE.portNumber].join(':');
        connectionDetails.LocalCandidateType = localICE.candidateType;
        connectionDetails.RemoteCandidateType = remoteICE.candidateType;
        return connectionDetails;
    });

  }
}