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