websocket.js

/**
 * Module dependencies.
 */

var Transport = require('../transport');
var parser = require('engine.io-parser');
var parseqs = require('parseqs');
var inherit = require('component-inherit');
var yeast = require('yeast');
var debug = require('debug')('engine.io-client:websocket');

var BrowserWebSocket, NodeWebSocket;

if (typeof WebSocket !== 'undefined') {
  BrowserWebSocket = WebSocket;
} else if (typeof self !== 'undefined') {
  BrowserWebSocket = self.WebSocket || self.MozWebSocket;
}

if (typeof window === 'undefined') {
  try {
    NodeWebSocket = require('ws');
  } catch (e) { }
}

/**
 * Get either the `WebSocket` or `MozWebSocket` globals
 * in the browser or try to resolve WebSocket-compatible
 * interface exposed by `ws` for Node-like environment.
 */

var WebSocketImpl = BrowserWebSocket || NodeWebSocket;

/**
 * Module exports.
 */

module.exports = WS;

/**
 * WebSocket transport constructor.
 *
 * @api {Object} connection options
 * @api public
 */

function WS (opts) {
  var forceBase64 = (opts && opts.forceBase64);
  if (forceBase64) {
    this.supportsBinary = false;
  }
  this.perMessageDeflate = opts.perMessageDeflate;
  this.usingBrowserWebSocket = BrowserWebSocket && !opts.forceNode;
  this.protocols = opts.protocols;
  if (!this.usingBrowserWebSocket) {
    WebSocketImpl = NodeWebSocket;
  }
  Transport.call(this, opts);
}

/**
 * Inherits from Transport.
 */

inherit(WS, Transport);

/**
 * Transport name.
 *
 * @api public
 */

WS.prototype.name = 'websocket';

/*
 * WebSockets support binary
 */

WS.prototype.supportsBinary = true;

/**
 * Opens socket.
 *
 * @api private
 */

WS.prototype.doOpen = function () {
  if (!this.check()) {
    // let probe timeout
    return;
  }

  var uri = this.uri();
  var protocols = this.protocols;
  var opts = {
    agent: this.agent,
    perMessageDeflate: this.perMessageDeflate
  };

  // SSL options for Node.js client
  opts.pfx = this.pfx;
  opts.key = this.key;
  opts.passphrase = this.passphrase;
  opts.cert = this.cert;
  opts.ca = this.ca;
  opts.ciphers = this.ciphers;
  opts.rejectUnauthorized = this.rejectUnauthorized;
  if (this.extraHeaders) {
    opts.headers = this.extraHeaders;
  }
  if (this.localAddress) {
    opts.localAddress = this.localAddress;
  }

  try {
    this.ws =
      this.usingBrowserWebSocket && !this.isReactNative
        ? protocols
          ? new WebSocketImpl(uri, protocols)
          : new WebSocketImpl(uri)
        : new WebSocketImpl(uri, protocols, opts);
  } catch (err) {
    return this.emit('error', err);
  }

  if (this.ws.binaryType === undefined) {
    this.supportsBinary = false;
  }

  if (this.ws.supports && this.ws.supports.binary) {
    this.supportsBinary = true;
    this.ws.binaryType = 'nodebuffer';
  } else {
    this.ws.binaryType = 'arraybuffer';
  }

  this.addEventListeners();
};

/**
 * Adds event listeners to the socket
 *
 * @api private
 */

WS.prototype.addEventListeners = function () {
  var self = this;

  this.ws.onopen = function () {
    self.onOpen();
  };
  this.ws.onclose = function () {
    self.onClose();
  };
  this.ws.onmessage = function (ev) {
    self.onData(ev.data);
  };
  this.ws.onerror = function (e) {
    self.onError('websocket error', e);
  };
};

/**
 * Writes data to socket.
 *
 * @param {Array} array of packets.
 * @api private
 */

WS.prototype.write = function (packets) {
  var self = this;
  this.writable = false;

  // encodePacket efficient as it uses WS framing
  // no need for encodePayload
  var total = packets.length;
  for (var i = 0, l = total; i < l; i++) {
    (function (packet) {
      parser.encodePacket(packet, self.supportsBinary, function (data) {
        if (!self.usingBrowserWebSocket) {
          // always create a new object (GH-437)
          var opts = {};
          if (packet.options) {
            opts.compress = packet.options.compress;
          }

          if (self.perMessageDeflate) {
            var len = 'string' === typeof data ? Buffer.byteLength(data) : data.length;
            if (len < self.perMessageDeflate.threshold) {
              opts.compress = false;
            }
          }
        }

        // Sometimes the websocket has already been closed but the browser didn't
        // have a chance of informing us about it yet, in that case send will
        // throw an error
        try {
          if (self.usingBrowserWebSocket) {
            // TypeError is thrown when passing the second argument on Safari
            self.ws.send(data);
          } else {
            self.ws.send(data, opts);
          }
        } catch (e) {
          debug('websocket closed before onclose event');
        }

        --total || done();
      });
    })(packets[i]);
  }

  function done () {
    self.emit('flush');

    // fake drain
    // defer to next tick to allow Socket to clear writeBuffer
    setTimeout(function () {
      self.writable = true;
      self.emit('drain');
    }, 0);
  }
};

/**
 * Called upon close
 *
 * @api private
 */

WS.prototype.onClose = function () {
  Transport.prototype.onClose.call(this);
};

/**
 * Closes socket.
 *
 * @api private
 */

WS.prototype.doClose = function () {
  if (typeof this.ws !== 'undefined') {
    this.ws.close();
  }
};

/**
 * Generates uri for connection.
 *
 * @api private
 */

WS.prototype.uri = function () {
  var query = this.query || {};
  var schema = this.secure ? 'wss' : 'ws';
  var port = '';

  // avoid port if default for schema
  if (this.port && (('wss' === schema && Number(this.port) !== 443) ||
    ('ws' === schema && Number(this.port) !== 80))) {
    port = ':' + this.port;
  }

  // append timestamp to URI
  if (this.timestampRequests) {
    query[this.timestampParam] = yeast();
  }

  // communicate binary support capabilities
  if (!this.supportsBinary) {
    query.b64 = 1;
  }

  query = parseqs.encode(query);

  // prepend ? to query
  if (query.length) {
    query = '?' + query;
  }

  var ipv6 = this.hostname.indexOf(':') !== -1;
  return schema + '://' + (ipv6 ? '[' + this.hostname + ']' : this.hostname) + port + this.path + query;
};

/**
 * Feature detection for WebSocket.
 *
 * @return {Boolean} whether this transport is available.
 * @api public
 */

WS.prototype.check = function () {
  return !!WebSocketImpl && !('__initialize' in WebSocketImpl && this.name === WS.prototype.name);
};