307 lines
8.4 KiB
JavaScript
307 lines
8.4 KiB
JavaScript
var util = require('./util');
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var express = require('express');
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var http = require('http');
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var EventEmitter = require('events').EventEmitter;
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var WebSocketServer = require('ws').Server;
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var url = require('url');
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function PeerServer(options) {
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if (!(this instanceof PeerServer)) return new PeerServer(options);
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EventEmitter.call(this);
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this._app = express();
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this._httpServer = http.createServer(this._app);
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this._app.use(express.bodyParser());
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this._app.use(this._allowCrossDomain);
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this._options = util.extend({
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port: 80,
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debug: false,
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timeout: 5000
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}, options);
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util.debug = this._options.debug;
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// Listen on user-specified port and create WebSocket server as well.
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this._httpServer.listen(this._options.port);
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this._wss = new WebSocketServer({ path: '/ws', server: this._httpServer });
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// WebSockets that are opened or HTTP responses (which are paired with
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// something in timeouts.
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this._clients = {};
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// Timeouts for HTTP responses.
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this._timeouts = {};
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// Connections waiting for another peer.
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this._outstandingOffers = {};
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// Initailize WebSocket server handlers.
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this._initializeWSS();
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// Initialize HTTP routes. This is only used for the first few milliseconds
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// before a socket is opened for a Peer.
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this._initializeHTTP();
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};
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util.inherits(PeerServer, EventEmitter);
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/** Handle CORS */
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PeerServer.prototype._allowCrossDomain = function(req, res, next) {
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res.setHeader('Access-Control-Allow-Origin', '*');
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res.setHeader('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE');
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res.setHeader('Access-Control-Allow-Headers', 'Content-Type');
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next();
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}
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/** Initialize WebSocket server. */
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PeerServer.prototype._initializeWSS = function() {
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var self = this;
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this._wss.on('connection', function(socket) {
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var id = url.parse(socket.upgradeReq.url, true).query.id;
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if (!!id && !!self._clients[id]) {
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// If response client and timeout exist, overwrite and clear.
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if (!!self._timeouts[id]) {
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clearTimeout(self._timeouts[id]);
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delete self._timeouts[id];
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self._clients[id].end(JSON.stringify({ type: 'HTTP-SOCKET' }));
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} else {
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socket.send(JSON.stringify({ type: 'ID-TAKEN', msg: 'ID is taken' }));
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socket.close();
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return;
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}
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} else if (id === undefined) {
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id = self._generateClientId();
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}
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socket.send(JSON.stringify({ type: 'OPEN', id: id }));
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// Save the socket for this id.
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self._clients[id] = socket;
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self._processOutstandingOffers(id);
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// Cleanup after a socket closes.
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socket.on('close', function() {
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util.log('Socket closed:', id);
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self._removePeer(id);
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});
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// Handle messages from peers.
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socket.on('message', function(data) {
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try {
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var message = JSON.parse(data);
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util.log(message);
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switch (message.type) {
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case 'LEAVE':
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// Clean up if a Peer sends a LEAVE.
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if (!message.dst) {
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self._removePeer(id);
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break;
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}
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// ICE candidates
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case 'CANDIDATE':
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// Offer or answer between peers.
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case 'OFFER':
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case 'ANSWER':
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// Firefoxism (connectDataConnection ports)
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case 'PORT':
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// Use the ID we know to be correct to prevent spoofing.
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message.src = id;
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self._handleTransmission(message);
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break;
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default:
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util.prettyError('Message unrecognized');
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}
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} catch(e) {
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util.log('Invalid message', data);
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}
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});
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});
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};
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/** Process outstanding peer offers. */
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PeerServer.prototype._processOutstandingOffers = function(id) {
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var offers = this._outstandingOffers[id];
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if (offers === undefined) {
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return;
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}
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var sources = Object.keys(offers);
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for (var i = 0, ii = sources.length; i < ii; i += 1) {
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var messages = offers[sources[i]];
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for (var j = 0, jj = messages.length; j < jj; j += 1) {
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this._handleTransmission.apply(this, messages[j]);
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}
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delete this._outstandingOffers[id][sources[i]];
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}
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};
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/** Initialize HTTP server routes. */
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PeerServer.prototype._initializeHTTP = function() {
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var self = this;
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this._app.options('/*', function(req, res, next) {
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res.send(200);
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});
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// Server sets up HTTP streaming whether you get or post an ID.
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// Retrieve guaranteed random ID.
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this._app.get('/id', function(req, res) {
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var clientId = util.randomId();
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while (!!self._clients[clientId]) {
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clientId = util.randomId();
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}
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self._startStreaming(res, clientId, function() {
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// Chrome hacks.
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res.write('{"id":"' + clientId + '"}\n');
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});
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});
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this._app.post('/id', function(req, res) {
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var id = req.body.id;
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self._startStreaming(res, id);
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});
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this._app.post('/offer', function(req, res) {
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self._handleTransmission(req.body, res);
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});
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this._app.post('/candidate', function(req, res) {
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self._handleTransmission(req.body, res);
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});
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this._app.post('/answer', function(req, res) {
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self._handleTransmission(req.body, res);
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});
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this._app.post('/leave', function(req, res) {
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self._handleTransmission(req.body, res);
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});
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this._app.post('/port', function(req, res) {
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self._handleTransmission(req.body, res);
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});
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};
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PeerServer.prototype._removePeer = function(id) {
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delete this._clients[id];
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if (this._timeouts[id]) {
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clearTimeout(this._timeouts[id]);
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delete this._timeouts[id];
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}
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};
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/** Saves a streaming response and takes care of timeouts and headers. */
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PeerServer.prototype._startStreaming = function(res, id, write) {
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res.writeHead(200, {'Content-Type': 'application/octet-stream'});
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if (!!write) {
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write();
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}
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var pad = '00';
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var iterations = 10;
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for (var i = 0; i < iterations; i++) {
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pad += pad;
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}
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res.write(pad + '\n');
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// Save res so we can write to it.
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if (!this._clients[id]) {
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this._clients[id] = res;
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// Set timeout to expire.
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var self = this;
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this._timeouts[id] = setTimeout(function() {
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self._removePeer(id);
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res.end(JSON.stringify({ type: 'HTTP-END' }));
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}, 30000);
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this._processOutstandingOffers(id);
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} else {
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res.end(JSON.stringify({ type: 'HTTP-ERROR' }));
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}
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};
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/** Handles passing on a message. */
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PeerServer.prototype._handleTransmission = function(message, res) {
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var type = message.type;
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var src = message.src;
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var dst = message.dst;
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var data = JSON.stringify(message);
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var destination = this._clients[dst];
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if (!!destination) {
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try {
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if (this._timeouts[dst]) {
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data += '\n';
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destination.write(data);
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} else {
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destination.send(data);
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}
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if (!!res) {
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res.send(200);
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}
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} catch (e) {
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// This happens when a peer disconnects without closing connections and
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// the associated WebSocket has not closed.
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util.prettyError(e);
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// Tell other side to stop trying.
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this._removePeer(dst);
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this._handleTransmission({
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type: 'LEAVE',
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src: dst,
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dst: src
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});
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if (!!res) res.send(501);
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}
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} else {
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// Wait 5 seconds for this client to connect/reconnect (XHR) for important
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// messages.
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if (type !== 'LEAVE') {
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var self = this;
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if (!this._outstandingOffers[dst]) {
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this._outstandingOffers[dst] = {};
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}
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if (!this._outstandingOffers[dst][src]) {
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this._outstandingOffers[dst][src] = [];
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setTimeout(function() {
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if(!!self._outstandingOffers[dst][src]) {
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delete self._outstandingOffers[dst][src];
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self._handleTransmission({
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type: 'EXPIRE',
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src: dst,
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dst: src
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});
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}
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}, this._options.timeout);
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}
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this._outstandingOffers[dst][src].push([message]);
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if (!!res) res.send(200);
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} else if (type === 'LEAVE' && !dst) {
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this._removePeer(src);
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if (!!res) res.send(200);
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} else if (src) {
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// Assume a disconnect if the client no longer exists.
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// Unless it's a message from the server.
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this._handleTransmission({
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type: 'EXPIRE',
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src: dst,
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dst: src
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});
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// 410: Resource not available.
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if (!!res) res.send(410);
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}
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}
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};
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PeerServer.prototype._generateClientId = function() {
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var clientId = util.randomId();
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while (!!this._clients[clientId]) {
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clientId = util.randomId();
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}
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return clientId;
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};
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exports.PeerServer = PeerServer;
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