buddy

websocket-server.js (11398B)

---

 'use strict';
 
 const EventEmitter = require('events');
 const { createHash } = require('crypto');
 const { createServer, STATUS_CODES } = require('http');
 
 const PerMessageDeflate = require('./permessage-deflate');
 const WebSocket = require('./websocket');
 const { format, parse } = require('./extension');
 const { GUID, kWebSocket } = require('./constants');
 
 const keyRegex = /^[+/0-9A-Za-z]{22}==$/;
 
 /**
  * Class representing a WebSocket server.
  *
  * @extends EventEmitter
  */
 class WebSocketServer extends EventEmitter {
   /**
    * Create a `WebSocketServer` instance.
    *
    * @param {Object} options Configuration options
    * @param {Number} options.backlog The maximum length of the queue of pending
    *     connections
    * @param {Boolean} options.clientTracking Specifies whether or not to track
    *     clients
    * @param {Function} options.handleProtocols A hook to handle protocols
    * @param {String} options.host The hostname where to bind the server
    * @param {Number} options.maxPayload The maximum allowed message size
    * @param {Boolean} options.noServer Enable no server mode
    * @param {String} options.path Accept only connections matching this path
    * @param {(Boolean|Object)} options.perMessageDeflate Enable/disable
    *     permessage-deflate
    * @param {Number} options.port The port where to bind the server
    * @param {http.Server} options.server A pre-created HTTP/S server to use
    * @param {Function} options.verifyClient A hook to reject connections
    * @param {Function} callback A listener for the `listening` event
    */
   constructor(options, callback) {
     super();
 
     options = {
       maxPayload: 100 * 1024 * 1024,
       perMessageDeflate: false,
       handleProtocols: null,
       clientTracking: true,
       verifyClient: null,
       noServer: false,
       backlog: null, // use default (511 as implemented in net.js)
       server: null,
       host: null,
       path: null,
       port: null,
       ...options
     };
 
     if (options.port == null && !options.server && !options.noServer) {
       throw new TypeError(
         'One of the "port", "server", or "noServer" options must be specified'
       );
     }
 
     if (options.port != null) {
       this._server = createServer((req, res) => {
         const body = STATUS_CODES[426];
 
         res.writeHead(426, {
           'Content-Length': body.length,
           'Content-Type': 'text/plain'
         });
         res.end(body);
       });
       this._server.listen(
         options.port,
         options.host,
         options.backlog,
         callback
       );
     } else if (options.server) {
       this._server = options.server;
     }
 
     if (this._server) {
       this._removeListeners = addListeners(this._server, {
         listening: this.emit.bind(this, 'listening'),
         error: this.emit.bind(this, 'error'),
         upgrade: (req, socket, head) => {
           this.handleUpgrade(req, socket, head, (ws) => {
             this.emit('connection', ws, req);
           });
         }
       });
     }
 
     if (options.perMessageDeflate === true) options.perMessageDeflate = {};
     if (options.clientTracking) this.clients = new Set();
     this.options = options;
   }
 
   /**
    * Returns the bound address, the address family name, and port of the server
    * as reported by the operating system if listening on an IP socket.
    * If the server is listening on a pipe or UNIX domain socket, the name is
    * returned as a string.
    *
    * @return {(Object|String|null)} The address of the server
    * @public
    */
   address() {
     if (this.options.noServer) {
       throw new Error('The server is operating in "noServer" mode');
     }
 
     if (!this._server) return null;
     return this._server.address();
   }
 
   /**
    * Close the server.
    *
    * @param {Function} cb Callback
    * @public
    */
   close(cb) {
     if (cb) this.once('close', cb);
 
     //
     // Terminate all associated clients.
     //
     if (this.clients) {
       for (const client of this.clients) client.terminate();
     }
 
     const server = this._server;
 
     if (server) {
       this._removeListeners();
       this._removeListeners = this._server = null;
 
       //
       // Close the http server if it was internally created.
       //
       if (this.options.port != null) {
         server.close(() => this.emit('close'));
         return;
       }
     }
 
     process.nextTick(emitClose, this);
   }
 
   /**
    * See if a given request should be handled by this server instance.
    *
    * @param {http.IncomingMessage} req Request object to inspect
    * @return {Boolean} `true` if the request is valid, else `false`
    * @public
    */
   shouldHandle(req) {
     if (this.options.path) {
       const index = req.url.indexOf('?');
       const pathname = index !== -1 ? req.url.slice(0, index) : req.url;
 
       if (pathname !== this.options.path) return false;
     }
 
     return true;
   }
 
   /**
    * Handle a HTTP Upgrade request.
    *
    * @param {http.IncomingMessage} req The request object
    * @param {net.Socket} socket The network socket between the server and client
    * @param {Buffer} head The first packet of the upgraded stream
    * @param {Function} cb Callback
    * @public
    */
   handleUpgrade(req, socket, head, cb) {
     socket.on('error', socketOnError);
 
     const key =
       req.headers['sec-websocket-key'] !== undefined
         ? req.headers['sec-websocket-key'].trim()
         : false;
     const version = +req.headers['sec-websocket-version'];
     const extensions = {};
 
     if (
       req.method !== 'GET' ||
       req.headers.upgrade.toLowerCase() !== 'websocket' ||
       !key ||
       !keyRegex.test(key) ||
       (version !== 8 && version !== 13) ||
       !this.shouldHandle(req)
     ) {
       return abortHandshake(socket, 400);
     }
 
     if (this.options.perMessageDeflate) {
       const perMessageDeflate = new PerMessageDeflate(
         this.options.perMessageDeflate,
         true,
         this.options.maxPayload
       );
 
       try {
         const offers = parse(req.headers['sec-websocket-extensions']);
 
         if (offers[PerMessageDeflate.extensionName]) {
           perMessageDeflate.accept(offers[PerMessageDeflate.extensionName]);
           extensions[PerMessageDeflate.extensionName] = perMessageDeflate;
         }
       } catch (err) {
         return abortHandshake(socket, 400);
       }
     }
 
     //
     // Optionally call external client verification handler.
     //
     if (this.options.verifyClient) {
       const info = {
         origin:
           req.headers[`${version === 8 ? 'sec-websocket-origin' : 'origin'}`],
         secure: !!(req.connection.authorized || req.connection.encrypted),
         req
       };
 
       if (this.options.verifyClient.length === 2) {
         this.options.verifyClient(info, (verified, code, message, headers) => {
           if (!verified) {
             return abortHandshake(socket, code || 401, message, headers);
           }
 
           this.completeUpgrade(key, extensions, req, socket, head, cb);
         });
         return;
       }
 
       if (!this.options.verifyClient(info)) return abortHandshake(socket, 401);
     }
 
     this.completeUpgrade(key, extensions, req, socket, head, cb);
   }
 
   /**
    * Upgrade the connection to WebSocket.
    *
    * @param {String} key The value of the `Sec-WebSocket-Key` header
    * @param {Object} extensions The accepted extensions
    * @param {http.IncomingMessage} req The request object
    * @param {net.Socket} socket The network socket between the server and client
    * @param {Buffer} head The first packet of the upgraded stream
    * @param {Function} cb Callback
    * @throws {Error} If called more than once with the same socket
    * @private
    */
   completeUpgrade(key, extensions, req, socket, head, cb) {
     //
     // Destroy the socket if the client has already sent a FIN packet.
     //
     if (!socket.readable || !socket.writable) return socket.destroy();
 
     if (socket[kWebSocket]) {
       throw new Error(
         'server.handleUpgrade() was called more than once with the same ' +
           'socket, possibly due to a misconfiguration'
       );
     }
 
     const digest = createHash('sha1')
       .update(key + GUID)
       .digest('base64');
 
     const headers = [
       'HTTP/1.1 101 Switching Protocols',
       'Upgrade: websocket',
       'Connection: Upgrade',
       `Sec-WebSocket-Accept: ${digest}`
     ];
 
     const ws = new WebSocket(null);
     let protocol = req.headers['sec-websocket-protocol'];
 
     if (protocol) {
       protocol = protocol.trim().split(/ *, */);
 
       //
       // Optionally call external protocol selection handler.
       //
       if (this.options.handleProtocols) {
         protocol = this.options.handleProtocols(protocol, req);
       } else {
         protocol = protocol[0];
       }
 
       if (protocol) {
         headers.push(`Sec-WebSocket-Protocol: ${protocol}`);
         ws.protocol = protocol;
       }
     }
 
     if (extensions[PerMessageDeflate.extensionName]) {
       const params = extensions[PerMessageDeflate.extensionName].params;
       const value = format({
         [PerMessageDeflate.extensionName]: [params]
       });
       headers.push(`Sec-WebSocket-Extensions: ${value}`);
       ws._extensions = extensions;
     }
 
     //
     // Allow external modification/inspection of handshake headers.
     //
     this.emit('headers', headers, req);
 
     socket.write(headers.concat('\r\n').join('\r\n'));
     socket.removeListener('error', socketOnError);
 
     ws.setSocket(socket, head, this.options.maxPayload);
 
     if (this.clients) {
       this.clients.add(ws);
       ws.on('close', () => this.clients.delete(ws));
     }
 
     cb(ws);
   }
 }
 
 module.exports = WebSocketServer;
 
 /**
  * Add event listeners on an `EventEmitter` using a map of <event, listener>
  * pairs.
  *
  * @param {EventEmitter} server The event emitter
  * @param {Object.<String, Function>} map The listeners to add
  * @return {Function} A function that will remove the added listeners when called
  * @private
  */
 function addListeners(server, map) {
   for (const event of Object.keys(map)) server.on(event, map[event]);
 
   return function removeListeners() {
     for (const event of Object.keys(map)) {
       server.removeListener(event, map[event]);
     }
   };
 }
 
 /**
  * Emit a `'close'` event on an `EventEmitter`.
  *
  * @param {EventEmitter} server The event emitter
  * @private
  */
 function emitClose(server) {
   server.emit('close');
 }
 
 /**
  * Handle premature socket errors.
  *
  * @private
  */
 function socketOnError() {
   this.destroy();
 }
 
 /**
  * Close the connection when preconditions are not fulfilled.
  *
  * @param {net.Socket} socket The socket of the upgrade request
  * @param {Number} code The HTTP response status code
  * @param {String} [message] The HTTP response body
  * @param {Object} [headers] Additional HTTP response headers
  * @private
  */
 function abortHandshake(socket, code, message, headers) {
   if (socket.writable) {
     message = message || STATUS_CODES[code];
     headers = {
       Connection: 'close',
       'Content-Type': 'text/html',
       'Content-Length': Buffer.byteLength(message),
       ...headers
     };
 
     socket.write(
       `HTTP/1.1 ${code} ${STATUS_CODES[code]}\r\n` +
         Object.keys(headers)
           .map((h) => `${h}: ${headers[h]}`)
           .join('\r\n') +
         '\r\n\r\n' +
         message
     );
   }
 
   socket.removeListener('error', socketOnError);
   socket.destroy();
 }