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536 lines
16 KiB
536 lines
16 KiB
/* eslint no-unused-vars: ["error", { "varsIgnorePattern": "^net|tls|https$" }] */
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'use strict';
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const EventEmitter = require('events');
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const http = require('http');
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const https = require('https');
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const net = require('net');
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const tls = require('tls');
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const { createHash } = require('crypto');
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const extension = require('./extension');
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const PerMessageDeflate = require('./permessage-deflate');
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const subprotocol = require('./subprotocol');
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const WebSocket = require('./websocket');
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const { GUID, kWebSocket } = require('./constants');
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const keyRegex = /^[+/0-9A-Za-z]{22}==$/;
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const RUNNING = 0;
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const CLOSING = 1;
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const CLOSED = 2;
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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 {Number} [options.backlog=511] The maximum length of the queue of
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* pending connections
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* @param {Boolean} [options.clientTracking=true] Specifies whether or not to
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* track clients
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* @param {Function} [options.handleProtocols] A hook to handle protocols
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* @param {String} [options.host] The hostname where to bind the server
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* @param {Number} [options.maxPayload=104857600] The maximum allowed message
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* size
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* @param {Boolean} [options.noServer=false] Enable no server mode
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* @param {String} [options.path] Accept only connections matching this path
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* @param {(Boolean|Object)} [options.perMessageDeflate=false] Enable/disable
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* permessage-deflate
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* @param {Number} [options.port] The port where to bind the server
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* @param {(http.Server|https.Server)} [options.server] A pre-created HTTP/S
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* server to use
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* @param {Boolean} [options.skipUTF8Validation=false] Specifies whether or
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* not to skip UTF-8 validation for text and close messages
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* @param {Function} [options.verifyClient] A hook to reject connections
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* @param {Function} [options.WebSocket=WebSocket] Specifies the `WebSocket`
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* class to use. It must be the `WebSocket` class or class that extends it
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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 = {
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maxPayload: 100 * 1024 * 1024,
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skipUTF8Validation: false,
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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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WebSocket,
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...options
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};
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if (
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(options.port == null && !options.server && !options.noServer) ||
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(options.port != null && (options.server || options.noServer)) ||
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(options.server && options.noServer)
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) {
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throw new TypeError(
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'One and only one of the "port", "server", or "noServer" options ' +
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'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(
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options.port,
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options.host,
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options.backlog,
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callback
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);
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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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const emitConnection = this.emit.bind(this, 'connection');
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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, emitConnection);
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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) {
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this.clients = new Set();
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this._shouldEmitClose = false;
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}
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this.options = options;
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this._state = RUNNING;
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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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* Stop the server from accepting new connections and emit the `'close'` event
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* when all existing connections are closed.
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*
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* @param {Function} [cb] A one-time listener for the `'close'` event
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* @public
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*/
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close(cb) {
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if (this._state === CLOSED) {
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if (cb) {
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this.once('close', () => {
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cb(new Error('The server is not running'));
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});
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}
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process.nextTick(emitClose, this);
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return;
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}
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if (cb) this.once('close', cb);
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if (this._state === CLOSING) return;
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this._state = CLOSING;
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if (this.options.noServer || this.options.server) {
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if (this._server) {
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this._removeListeners();
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this._removeListeners = this._server = null;
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}
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if (this.clients) {
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if (!this.clients.size) {
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process.nextTick(emitClose, this);
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} else {
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this._shouldEmitClose = true;
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}
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} else {
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process.nextTick(emitClose, this);
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}
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} else {
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const server = this._server;
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this._removeListeners();
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this._removeListeners = this._server = null;
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//
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// The HTTP/S server was created internally. Close it, and rely on its
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// `'close'` event.
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//
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server.close(() => {
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emitClose(this);
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});
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}
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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) {
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const index = req.url.indexOf('?');
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const pathname = index !== -1 ? req.url.slice(0, index) : req.url;
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if (pathname !== this.options.path) 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|tls.Socket)} socket The network socket between the
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* 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 key = req.headers['sec-websocket-key'];
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const version = +req.headers['sec-websocket-version'];
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if (req.method !== 'GET') {
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const message = 'Invalid HTTP method';
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abortHandshakeOrEmitwsClientError(this, req, socket, 405, message);
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return;
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}
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if (req.headers.upgrade.toLowerCase() !== 'websocket') {
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const message = 'Invalid Upgrade header';
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abortHandshakeOrEmitwsClientError(this, req, socket, 400, message);
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return;
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}
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if (!key || !keyRegex.test(key)) {
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const message = 'Missing or invalid Sec-WebSocket-Key header';
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abortHandshakeOrEmitwsClientError(this, req, socket, 400, message);
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return;
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}
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if (version !== 8 && version !== 13) {
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const message = 'Missing or invalid Sec-WebSocket-Version header';
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abortHandshakeOrEmitwsClientError(this, req, socket, 400, message);
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return;
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}
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if (!this.shouldHandle(req)) {
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abortHandshake(socket, 400);
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return;
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}
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const secWebSocketProtocol = req.headers['sec-websocket-protocol'];
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let protocols = new Set();
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if (secWebSocketProtocol !== undefined) {
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try {
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protocols = subprotocol.parse(secWebSocketProtocol);
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} catch (err) {
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const message = 'Invalid Sec-WebSocket-Protocol header';
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abortHandshakeOrEmitwsClientError(this, req, socket, 400, message);
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return;
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}
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}
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const secWebSocketExtensions = req.headers['sec-websocket-extensions'];
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const extensions = {};
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if (
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this.options.perMessageDeflate &&
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secWebSocketExtensions !== undefined
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) {
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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(secWebSocketExtensions);
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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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const message =
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'Invalid or unacceptable Sec-WebSocket-Extensions header';
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abortHandshakeOrEmitwsClientError(this, req, socket, 400, message);
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return;
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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:
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req.headers[`${version === 8 ? 'sec-websocket-origin' : 'origin'}`],
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secure: !!(req.socket.authorized || req.socket.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(
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extensions,
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key,
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protocols,
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req,
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socket,
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head,
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cb
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);
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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, key, protocols, 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 {String} key The value of the `Sec-WebSocket-Key` header
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* @param {Set} protocols The subprotocols
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* @param {http.IncomingMessage} req The request object
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* @param {(net.Socket|tls.Socket)} socket The network socket between the
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* 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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* @throws {Error} If called more than once with the same socket
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* @private
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*/
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completeUpgrade(extensions, key, protocols, 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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if (socket[kWebSocket]) {
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throw new Error(
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'server.handleUpgrade() was called more than once with the same ' +
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'socket, possibly due to a misconfiguration'
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);
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}
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if (this._state > RUNNING) return abortHandshake(socket, 503);
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const digest = createHash('sha1')
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.update(key + GUID)
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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: ${digest}`
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];
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const ws = new this.options.WebSocket(null);
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if (protocols.size) {
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//
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// Optionally call external protocol selection handler.
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//
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const protocol = this.options.handleProtocols
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? this.options.handleProtocols(protocols, req)
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: protocols.values().next().value;
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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, {
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maxPayload: this.options.maxPayload,
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skipUTF8Validation: this.options.skipUTF8Validation
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});
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if (this.clients) {
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this.clients.add(ws);
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ws.on('close', () => {
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this.clients.delete(ws);
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if (this._shouldEmitClose && !this.clients.size) {
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process.nextTick(emitClose, this);
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}
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});
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}
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cb(ws, req);
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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
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* 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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* Emit a `'close'` event on an `EventEmitter`.
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*
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* @param {EventEmitter} server The event emitter
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* @private
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*/
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function emitClose(server) {
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server._state = CLOSED;
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server.emit('close');
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}
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/**
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* Handle 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|tls.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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//
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// The socket is writable unless the user destroyed or ended it before calling
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// `server.handleUpgrade()` or in the `verifyClient` function, which is a user
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// error. Handling this does not make much sense as the worst that can happen
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// is that some of the data written by the user might be discarded due to the
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// call to `socket.end()` below, which triggers an `'error'` event that in
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// turn causes the socket to be destroyed.
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//
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message = message || http.STATUS_CODES[code];
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headers = {
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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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};
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socket.once('finish', socket.destroy);
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socket.end(
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`HTTP/1.1 ${code} ${http.STATUS_CODES[code]}\r\n` +
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Object.keys(headers)
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.map((h) => `${h}: ${headers[h]}`)
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.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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/**
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* Emit a `'wsClientError'` event on a `WebSocketServer` if there is at least
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* one listener for it, otherwise call `abortHandshake()`.
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*
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* @param {WebSocketServer} server The WebSocket server
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* @param {http.IncomingMessage} req The request object
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* @param {(net.Socket|tls.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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* @private
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*/
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function abortHandshakeOrEmitwsClientError(server, req, socket, code, message) {
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if (server.listenerCount('wsClientError')) {
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const err = new Error(message);
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Error.captureStackTrace(err, abortHandshakeOrEmitwsClientError);
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server.emit('wsClientError', err, socket, req);
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} else {
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abortHandshake(socket, code, message);
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}
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}
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