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shrine-medco/shrine-webclient/src/main/html/node_modules/engine.io/lib/server.js
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server.js
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			/**
			* Module dependencies.
			*/

			var qs = require('querystring')
			, parse = require('url').parse
			, readFileSync = require('fs').readFileSync
			, crypto = require('crypto')
			, base64id = require('base64id')
			, transports = require('./transports')
			, EventEmitter = require('events').EventEmitter
			, Socket = require('./socket')
			, WebSocketServer = require('ws').Server
			, debug = require('debug')('engine');

			/**
			* Module exports.
			*/

			module.exports = Server;

			/**
			* Server constructor.
			*
			* @param {Object} options
			* @api public
			*/

			function Server(opts){
			if (!(this instanceof Server)) {
			return new Server(opts);
			}

			this.clients = {};
			this.clientsCount = 0;

			opts = opts \|\| {};
			this.pingTimeout = opts.pingTimeout \|\| 60000;
			this.pingInterval = opts.pingInterval \|\| 25000;
			this.upgradeTimeout = opts.upgradeTimeout \|\| 10000;
			this.maxHttpBufferSize = opts.maxHttpBufferSize \|\| 10E7;
			this.transports = opts.transports \|\| Object.keys(transports);
			this.allowUpgrades = false !== opts.allowUpgrades;
			this.allowRequest = opts.allowRequest;
			this.cookie = false !== opts.cookie ? (opts.cookie \|\| 'io') : false;
			this.cookiePath = false !== opts.cookiePath ? (opts.cookiePath \|\| false) : false;
			this.perMessageDeflate = false !== opts.perMessageDeflate ? (opts.perMessageDeflate \|\| true) : false;
			this.httpCompression = false !== opts.httpCompression ? (opts.httpCompression \|\| {}) : false;

			var self = this;

			// turn off per message deflate for node 0.8
			// due to it not supporting DeflateRaw#close
			// and thus not working with ws 0.8.x
			if (/^v0\.8\./.test(process.version)) {
			debug('perMessageDeflate not supported by node 0.8');
			this.perMessageDeflate = false;
			}

			// initialize compression options
			['perMessageDeflate', 'httpCompression'].forEach(function(type) {
			var compression = self[type];
			if (true === compression) self[type] = compression = {};
			if (compression && null == compression.threshold) {
			compression.threshold = 1024;
			}
			});

			// initialize websocket server
			if (~this.transports.indexOf('websocket')) {
			this.ws = new WebSocketServer({
			noServer: true,
			clientTracking: false,
			perMessageDeflate: this.perMessageDeflate,
			maxPayload: this.maxHttpBufferSize
			});
			}
			}

			/**
			* Protocol errors mappings.
			*/

			Server.errors = {
			UNKNOWN_TRANSPORT: 0,
			UNKNOWN_SID: 1,
			BAD_HANDSHAKE_METHOD: 2,
			BAD_REQUEST: 3
			};

			Server.errorMessages = {
			0: 'Transport unknown',
			1: 'Session ID unknown',
			2: 'Bad handshake method',
			3: 'Bad request'
			};

			/**
			* Inherits from EventEmitter.
			*/

			Server.prototype.__proto__ = EventEmitter.prototype;

			/**
			* Hash of open clients.
			*
			* @api public
			*/

			Server.prototype.clients;

			/**
			* Returns a list of available transports for upgrade given a certain transport.
			*
			* @return {Array}
			* @api public
			*/

			Server.prototype.upgrades = function(transport){
			if (!this.allowUpgrades) return [];
			return transports[transport].upgradesTo \|\| [];
			};

			/**
			* Verifies a request.
			*
			* @param {http.ServerRequest}
			* @return {Boolean} whether the request is valid
			* @api private
			*/

			Server.prototype.verify = function(req, upgrade, fn){
			// transport check
			var transport = req._query.transport;
			if (!~this.transports.indexOf(transport)) {
			debug('unknown transport "%s"', transport);
			return fn(Server.errors.UNKNOWN_TRANSPORT, false);
			}

			// sid check
			var sid = req._query.sid;
			if (sid) {
			if (!this.clients.hasOwnProperty(sid))
			return fn(Server.errors.UNKNOWN_SID, false);
			if (!upgrade && this.clients[sid].transport.name !== transport) {
			debug('bad request: unexpected transport without upgrade');
			return fn(Server.errors.BAD_REQUEST, false);
			}
			} else {
			// handshake is GET only
			if ('GET' != req.method) return fn(Server.errors.BAD_HANDSHAKE_METHOD, false);
			if (!this.allowRequest) return fn(null, true);
			return this.allowRequest(req, fn);
			}

			fn(null, true);
			};

			/**
			* Prepares a request by processing the query string.
			*
			* @api private
			*/

			Server.prototype.prepare = function(req){
			// try to leverage pre-existing `req._query` (e.g: from connect)
			if (!req._query) {
			req._query = ~req.url.indexOf('?') ? qs.parse(parse(req.url).query) : {};
			}
			};

			/**
			* Closes all clients.
			*
			* @api public
			*/

			Server.prototype.close = function(){
			debug('closing all open clients');
			for (var i in this.clients) {
			if (this.clients.hasOwnProperty(i)) {
			this.clients[i].close(true);
			}
			}
			return this;
			};

			/**
			* Handles an Engine.IO HTTP request.
			*
			* @param {http.ServerRequest} request
			* @param {http.ServerResponse\|http.OutgoingMessage} response
			* @api public
			*/

			Server.prototype.handleRequest = function(req, res){
			debug('handling "%s" http request "%s"', req.method, req.url);
			this.prepare(req);
			req.res = res;

			var self = this;
			this.verify(req, false, function(err, success) {
			if (!success) {
			sendErrorMessage(req, res, err);
			return;
			}

			if (req._query.sid) {
			debug('setting new request for existing client');
			self.clients[req._query.sid].transport.onRequest(req);
			} else {
			self.handshake(req._query.transport, req);
			}
			});
			};

			/**
			* Sends an Engine.IO Error Message
			*
			* @param {http.ServerResponse} response
			* @param {code} error code
			* @api private
			*/

			function sendErrorMessage(req, res, code) {
			var headers = { 'Content-Type': 'application/json' };

			if (req.headers.origin) {
			headers['Access-Control-Allow-Credentials'] = 'true';
			headers['Access-Control-Allow-Origin'] = req.headers.origin;
			} else {
			headers['Access-Control-Allow-Origin'] = '*';
			}
			res.writeHead(400, headers);
			res.end(JSON.stringify({
			code: code,
			message: Server.errorMessages[code]
			}));
			}

			/**
			* generate a socket id.
			* Overwrite this method to generate your custom socket id
			*
			* @param {Object} request object
			* @api public
			*/

			Server.prototype.generateId = function(req){
			return base64id.generateId();
			};

			/**
			* Handshakes a new client.
			*
			* @param {String} transport name
			* @param {Object} request object
			* @api private
			*/

			Server.prototype.handshake = function(transportName, req){
			var id = this.generateId(req);

			debug('handshaking client "%s"', id);

			try {
			var transport = new transports[transportName](req);
			if ('polling' == transportName) {
			transport.maxHttpBufferSize = this.maxHttpBufferSize;
			transport.httpCompression = this.httpCompression;
			} else if ('websocket' == transportName) {
			transport.perMessageDeflate = this.perMessageDeflate;
			}

			if (req._query && req._query.b64) {
			transport.supportsBinary = false;
			} else {
			transport.supportsBinary = true;
			}
			}
			catch (e) {
			sendErrorMessage(req, req.res, Server.errors.BAD_REQUEST);
			return;
			}
			var socket = new Socket(id, this, transport, req);
			var self = this;

			if (false !== this.cookie) {
			transport.on('headers', function(headers){
			var cookie = self.cookie + '=' + id;
			if(false !== self.cookiePath) {
			cookie += '; path=' + self.cookiePath;
			}
			headers['Set-Cookie'] = cookie;
			});
			}

			transport.onRequest(req);

			this.clients[id] = socket;
			this.clientsCount++;

			socket.once('close', function(){
			delete self.clients[id];
			self.clientsCount--;
			});

			this.emit('connection', socket);
			};

			/**
			* Handles an Engine.IO HTTP Upgrade.
			*
			* @api public
			*/

			Server.prototype.handleUpgrade = function(req, socket, upgradeHead){
			this.prepare(req);

			var self = this;
			this.verify(req, true, function(err, success) {
			if (!success) {
			socket.end();
			return;
			}

			var head = new Buffer(upgradeHead.length);
			upgradeHead.copy(head);
			upgradeHead = null;

			// delegate to ws
			self.ws.handleUpgrade(req, socket, head, function(conn){
			self.onWebSocket(req, conn);
			});
			});
			};

			/**
			* Called upon a ws.io connection.
			*
			* @param {ws.Socket} websocket
			* @api private
			*/

			Server.prototype.onWebSocket = function(req, socket){
			socket.on('error', onUpgradeError);

			if (!transports[req._query.transport].prototype.handlesUpgrades) {
			debug('transport doesnt handle upgraded requests');
			socket.close();
			return;
			}

			// get client id
			var id = req._query.sid;

			// keep a reference to the ws.Socket
			req.websocket = socket;

			if (id) {
			var client = this.clients[id];
			if (!client) {
			debug('upgrade attempt for closed client');
			socket.close();
			} else if (client.upgrading) {
			debug('transport has already been trying to upgrade');
			socket.close();
			} else if (client.upgraded) {
			debug('transport had already been upgraded');
			socket.close();
			} else {
			debug('upgrading existing transport');

			// transport error handling takes over
			socket.removeListener('error', onUpgradeError);

			var transport = new transports[req._query.transport](req);
			if (req._query && req._query.b64) {
			transport.supportsBinary = false;
			} else {
			transport.supportsBinary = true;
			}
			transport.perMessageDeflate = this.perMessageDeflate;
			client.maybeUpgrade(transport);
			}
			} else {
			// transport error handling takes over
			socket.removeListener('error', onUpgradeError);

			this.handshake(req._query.transport, req);
			}

			function onUpgradeError(){
			debug('websocket error before upgrade');
			// socket.close() not needed
			}
			};

			/**
			* Captures upgrade requests for a http.Server.
			*
			* @param {http.Server} server
			* @param {Object} options
			* @api public
			*/

			Server.prototype.attach = function(server, options){
			var self = this;
			var options = options \|\| {};
			var path = (options.path \|\| '/engine.io').replace(/\/$/, '');

			var destroyUpgrade = (options.destroyUpgrade !== undefined) ? options.destroyUpgrade : true;
			var destroyUpgradeTimeout = options.destroyUpgradeTimeout \|\| 1000;

			// normalize path
			path += '/';

			function check (req) {
			return path == req.url.substr(0, path.length);
			}

			// cache and clean up listeners
			var listeners = server.listeners('request').slice(0);
			server.removeAllListeners('request');
			server.on('close', self.close.bind(self));

			// add request handler
			server.on('request', function(req, res){
			if (check(req)) {
			debug('intercepting request for path "%s"', path);
			self.handleRequest(req, res);
			} else {
			for (var i = 0, l = listeners.length; i < l; i++) {
			listeners[i].call(server, req, res);
			}
			}
			});

			if(~self.transports.indexOf('websocket')) {
			server.on('upgrade', function (req, socket, head) {
			if (check(req)) {
			self.handleUpgrade(req, socket, head);
			} else if (false !== options.destroyUpgrade) {
			// default node behavior is to disconnect when no handlers
			// but by adding a handler, we prevent that
			// and if no eio thing handles the upgrade
			// then the socket needs to die!
			setTimeout(function() {
			if (socket.writable && socket.bytesWritten <= 0) {
			return socket.end();
			}
			}, options.destroyUpgradeTimeout);
			}
			});
			}
			};