webrtc/webrtc.js

var util = require('util');
var webrtc = require('webrtcsupport');
var PeerConnection = require('rtcpeerconnection');
var WildEmitter = require('wildemitter');
var mockconsole = require('mockconsole');
var localMedia = require('localmedia');


function WebRTC(opts) {
    var self = this;
    var options = opts || {};
    var config = this.config = {
            debug: false,
            // makes the entire PC config overridable
            peerConnectionConfig: {
                iceServers: [{"url": "stun:stun.l.google.com:19302"}]
            },
            peerConnectionContraints: {
                optional: [
                    {DtlsSrtpKeyAgreement: true}
                ]
            },
            receiveMedia: {
                mandatory: {
                    OfferToReceiveAudio: true,
                    OfferToReceiveVideo: true
                }
            },
            enableDataChannels: true
        };
    var item;

    // expose screensharing check
    this.screenSharingSupport = webrtc.screenSharing;

    // We also allow a 'logger' option. It can be any object that implements
    // log, warn, and error methods.
    // We log nothing by default, following "the rule of silence":
    // http://www.linfo.org/rule_of_silence.html
    this.logger = function () {
        // we assume that if you're in debug mode and you didn't
        // pass in a logger, you actually want to log as much as
        // possible.
        if (opts.debug) {
            return opts.logger || console;
        } else {
        // or we'll use your logger which should have its own logic
        // for output. Or we'll return the no-op.
            return opts.logger || mockconsole;
        }
    }();

    // set options
    for (item in options) {
        this.config[item] = options[item];
    }

    // check for support
    if (!webrtc.support) {
        this.logger.error('Your browser doesn\'t seem to support WebRTC');
    }

    // where we'll store our peer connections
    this.peers = [];

    // call localMedia constructor
    localMedia.call(this, this.config);

    this.on('speaking', function () {
        if (!self.hardMuted) {
            // FIXME: should use sendDirectlyToAll, but currently has different semantics wrt payload
            self.peers.forEach(function (peer) {
                if (peer.enableDataChannels) {
                    var dc = peer.getDataChannel('hark');
                    if (dc.readyState != 'open') return;
                    dc.send(JSON.stringify({type: 'speaking'}));
                }
            });
        }
    });
    this.on('stoppedSpeaking', function () {
        if (!self.hardMuted) {
            // FIXME: should use sendDirectlyToAll, but currently has different semantics wrt payload
            self.peers.forEach(function (peer) {
                if (peer.enableDataChannels) {
                    var dc = peer.getDataChannel('hark');
                    if (dc.readyState != 'open') return;
                    dc.send(JSON.stringify({type: 'stoppedSpeaking'}));
                }
            });
        }
    });
    this.on('volumeChange', function (volume, treshold) {
        if (!self.hardMuted) {
            // FIXME: should use sendDirectlyToAll, but currently has different semantics wrt payload
            self.peers.forEach(function (peer) {
                if (peer.enableDataChannels) {
                    var dc = peer.getDataChannel('hark');
                    if (dc.readyState != 'open') return;
                    dc.send(JSON.stringify({type: 'volume', volume: volume }));
                }
            });
        }
    });

    // log events in debug mode
    if (this.config.debug) {
        this.on('*', function (event, val1, val2) {
            var logger;
            // if you didn't pass in a logger and you explicitly turning on debug
            // we're just going to assume you're wanting log output with console
            if (self.config.logger === mockconsole) {
                logger = console;
            } else {
                logger = self.logger;
            }
            logger.log('event:', event, val1, val2);
        });
    }
}

util.inherits(WebRTC, localMedia);

WebRTC.prototype.createPeer = function (opts) {
    var peer;
    opts.parent = this;
    peer = new Peer(opts);
    this.peers.push(peer);
    return peer;
};

// removes peers
WebRTC.prototype.removePeers = function (id, type) {
    this.getPeers(id, type).forEach(function (peer) {
        peer.end();
    });
};

// fetches all Peer objects by session id and/or type
WebRTC.prototype.getPeers = function (sessionId, type) {
    return this.peers.filter(function (peer) {
        return (!sessionId || peer.id === sessionId) && (!type || peer.type === type);
    });
};

// sends message to all
WebRTC.prototype.sendToAll = function (message, payload) {
    this.peers.forEach(function (peer) {
        peer.send(message, payload);
    });
};

// sends message to all using a datachannel
// only sends to anyone who has an open datachannel
WebRTC.prototype.sendDirectlyToAll = function (channel, message, payload) {
    this.peers.forEach(function (peer) {
        if (peer.enableDataChannels) {
            peer.sendDirectly(channel, message, payload);
        }
    });
};

function Peer(options) {
    var self = this;

    this.id = options.id;
    this.parent = options.parent;
    this.type = options.type || 'video';
    this.oneway = options.oneway || false;
    this.sharemyscreen = options.sharemyscreen || false;
    this.browserPrefix = options.prefix;
    this.stream = options.stream;
    this.enableDataChannels = options.enableDataChannels === undefined ? this.parent.config.enableDataChannels : options.enableDataChannels;
    this.receiveMedia = options.receiveMedia || this.parent.config.receiveMedia;
    this.channels = {};
    // Create an RTCPeerConnection via the polyfill
    this.pc = new PeerConnection(this.parent.config.peerConnectionConfig, this.parent.config.peerConnectionContraints);
    this.pc.on('ice', this.onIceCandidate.bind(this));
    this.pc.on('addStream', this.handleRemoteStreamAdded.bind(this));
    this.pc.on('addChannel', this.handleDataChannelAdded.bind(this));
    this.pc.on('removeStream', this.handleStreamRemoved.bind(this));
    // Just fire negotiation needed events for now
    // When browser re-negotiation handling seems to work
    // we can use this as the trigger for starting the offer/answer process
    // automatically. We'll just leave it be for now while this stabalizes.
    this.pc.on('negotiationNeeded', this.emit.bind(this, 'negotiationNeeded'));
    this.pc.on('iceConnectionStateChange', this.emit.bind(this, 'iceConnectionStateChange'));
    this.pc.on('iceConnectionStateChange', function () {
        switch (self.pc.iceConnectionState) {
        case 'failed':
            // currently, in chrome only the initiator goes to failed
            // so we need to signal this to the peer
            if (self.pc.pc.peerconnection.localDescription.type === 'offer') {
                self.parent.emit('iceFailed', self);
                self.send('connectivityError');
            }
            break;
        }
    });
    this.pc.on('signalingStateChange', this.emit.bind(this, 'signalingStateChange'));
    this.logger = this.parent.logger;

    // handle screensharing/broadcast mode
    if (options.type === 'screen') {
        if (this.parent.localScreen && this.sharemyscreen) {
            this.logger.log('adding local screen stream to peer connection');
            this.pc.addStream(this.parent.localScreen);
            this.broadcaster = options.broadcaster;
        }
    } else {
        this.parent.localStreams.forEach(function (stream) {
            self.pc.addStream(stream);
        });
    }

    // call emitter constructor
    WildEmitter.call(this);

    // proxy events to parent
    this.on('*', function () {
        self.parent.emit.apply(self.parent, arguments);
    });
}

Peer.prototype = Object.create(WildEmitter.prototype, {
    constructor: {
        value: Peer
    }
});

Peer.prototype.handleMessage = function (message) {
    var self = this;

    this.logger.log('getting', message.type, message);

    if (message.prefix) this.browserPrefix = message.prefix;

    if (message.type === 'offer') {
        this.pc.handleOffer(message.payload, function (err) {
            if (err) {
                return;
            }
            // auto-accept
            self.pc.answer(self.receiveMedia, function (err, sessionDescription) {
                self.send('answer', sessionDescription);
            });
        });
    } else if (message.type === 'answer') {
        this.pc.handleAnswer(message.payload);
    } else if (message.type === 'candidate') {
        this.pc.processIce(message.payload);
    } else if (message.type === 'connectivityError') {
        this.parent.emit('connectivityError', self);
    } else if (message.type === 'mute') {
        this.parent.emit('mute', {id: message.from, name: message.payload.name});
    } else if (message.type === 'unmute') {
        this.parent.emit('unmute', {id: message.from, name: message.payload.name});
    }
};

// send via signalling channel
Peer.prototype.send = function (messageType, payload) {
    var message = {
        to: this.id,
        broadcaster: this.broadcaster,
        roomType: this.type,
        type: messageType,
        payload: payload,
        prefix: webrtc.prefix
    };
    this.logger.log('sending', messageType, message);
    this.parent.emit('message', message);
};

// send via data channel
// returns true when message was sent and false if channel is not open
Peer.prototype.sendDirectly = function (channel, messageType, payload) {
    var message = {
        type: messageType,
        payload: payload
    };
    this.logger.log('sending via datachannel', channel, messageType, message);
    var dc = this.getDataChannel(channel);
    if (dc.readyState != 'open') return false;
    dc.send(JSON.stringify(message));
    return true;
};

// Internal method registering handlers for a data channel and emitting events on the peer
Peer.prototype._observeDataChannel = function (channel) {
    var self = this;
    channel.onclose = this.emit.bind(this, 'channelClose', channel);
    channel.onerror = this.emit.bind(this, 'channelError', channel);
    channel.onmessage = function (event) {
        self.emit('channelMessage', self, channel.label, JSON.parse(event.data), channel, event);
    };
    channel.onopen = this.emit.bind(this, 'channelOpen', channel);
};

// Fetch or create a data channel by the given name
Peer.prototype.getDataChannel = function (name, opts) {
    if (!webrtc.dataChannel) return this.emit('error', new Error('createDataChannel not supported'));
    var channel = this.channels[name];
    opts || (opts = {});
    if (channel) return channel;
    // if we don't have one by this label, create it
    channel = this.channels[name] = this.pc.createDataChannel(name, opts);
    this._observeDataChannel(channel);
    return channel;
};

Peer.prototype.onIceCandidate = function (candidate) {
    if (this.closed) return;
    if (candidate) {
        this.send('candidate', candidate);
    } else {
        this.logger.log("End of candidates.");
    }
};

Peer.prototype.start = function () {
    var self = this;

    // well, the webrtc api requires that we either
    // a) create a datachannel a priori
    // b) do a renegotiation later to add the SCTP m-line
    // Let's do (a) first...
    if (this.enableDataChannels) {
        this.getDataChannel('simplewebrtc');
    }

    this.pc.offer(this.receiveMedia, function (err, sessionDescription) {
        self.send('offer', sessionDescription);
    });
};

Peer.prototype.end = function () {
    if (this.closed) return;
    this.pc.close();
    this.handleStreamRemoved();
};

Peer.prototype.handleRemoteStreamAdded = function (event) {
    var self = this;
    if (this.stream) {
        this.logger.warn('Already have a remote stream');
    } else {
        this.stream = event.stream;
        // FIXME: addEventListener('ended', ...) would be nicer
        // but does not work in firefox 
        this.stream.onended = function () {
            self.end();
        };
        this.parent.emit('peerStreamAdded', this);
    }
};

Peer.prototype.handleStreamRemoved = function () {
    this.parent.peers.splice(this.parent.peers.indexOf(this), 1);
    this.closed = true;
    this.parent.emit('peerStreamRemoved', this);
};

Peer.prototype.handleDataChannelAdded = function (channel) {
    this.channels[channel.label] = channel;
    this._observeDataChannel(channel);
};

module.exports = WebRTC;