Firebase Update

express-server/node_modules/websocket-driver/lib/websocket/driver.js

@@ -0,0 +1,50 @@
+'use strict';
+
+// Protocol references:
+// 
+// * http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol-75
+// * http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol-76
+// * http://tools.ietf.org/html/draft-ietf-hybi-thewebsocketprotocol-17
+
+var Base   = require('./driver/base'),
+    Client = require('./driver/client'),
+    Server = require('./driver/server');
+
+var Driver = {
+  client: function(url, options) {
+    options = options || {};
+    if (options.masking === undefined) options.masking = true;
+    return new Client(url, options);
+  },
+
+  server: function(options) {
+    options = options || {};
+    if (options.requireMasking === undefined) options.requireMasking = true;
+    return new Server(options);
+  },
+
+  http: function() {
+    return Server.http.apply(Server, arguments);
+  },
+
+  isSecureRequest: function(request) {
+    return Server.isSecureRequest(request);
+  },
+
+  isWebSocket: function(request) {
+    if (request.method !== 'GET') return false;
+
+    var connection = request.headers.connection || '',
+        upgrade    = request.headers.upgrade || '';
+
+    return request.method === 'GET' &&
+           connection.toLowerCase().split(/ *, */).indexOf('upgrade') >= 0 &&
+           upgrade.toLowerCase() === 'websocket';
+  },
+
+  validateOptions: function(options, validKeys) {
+    Base.validateOptions(options, validKeys);
+  }
+};
+
+module.exports = Driver;

express-server/node_modules/websocket-driver/lib/websocket/driver/base.js

@@ -0,0 +1,155 @@
+'use strict';
+
+var Emitter = require('events').EventEmitter,
+    util    = require('util'),
+    streams = require('../streams'),
+    Headers = require('./headers'),
+    Reader  = require('./stream_reader');
+
+var Base = function(request, url, options) {
+  Emitter.call(this);
+  Base.validateOptions(options || {}, ['maxLength', 'masking', 'requireMasking', 'protocols']);
+
+  this._request   = request;
+  this._reader    = new Reader();
+  this._options   = options || {};
+  this._maxLength = this._options.maxLength || this.MAX_LENGTH;
+  this._headers   = new Headers();
+  this.__queue    = [];
+  this.readyState = 0;
+  this.url        = url;
+
+  this.io = new streams.IO(this);
+  this.messages = new streams.Messages(this);
+  this._bindEventListeners();
+};
+util.inherits(Base, Emitter);
+
+Base.validateOptions = function(options, validKeys) {
+  for (var key in options) {
+    if (validKeys.indexOf(key) < 0)
+      throw new Error('Unrecognized option: ' + key);
+  }
+};
+
+var instance = {
+  // This is 64MB, small enough for an average VPS to handle without
+  // crashing from process out of memory
+  MAX_LENGTH: 0x3ffffff,
+
+  STATES: ['connecting', 'open', 'closing', 'closed'],
+
+  _bindEventListeners: function() {
+    var self = this;
+
+    // Protocol errors are informational and do not have to be handled
+    this.messages.on('error', function() {});
+
+    this.on('message', function(event) {
+      var messages = self.messages;
+      if (messages.readable) messages.emit('data', event.data);
+    });
+
+    this.on('error', function(error) {
+      var messages = self.messages;
+      if (messages.readable) messages.emit('error', error);
+    });
+
+    this.on('close', function() {
+      var messages = self.messages;
+      if (!messages.readable) return;
+      messages.readable = messages.writable = false;
+      messages.emit('end');
+    });
+  },
+
+  getState: function() {
+    return this.STATES[this.readyState] || null;
+  },
+
+  addExtension: function(extension) {
+    return false;
+  },
+
+  setHeader: function(name, value) {
+    if (this.readyState > 0) return false;
+    this._headers.set(name, value);
+    return true;
+  },
+
+  start: function() {
+    if (this.readyState !== 0) return false;
+    var response = this._handshakeResponse();
+    if (!response) return false;
+    this._write(response);
+    if (this._stage !== -1) this._open();
+    return true;
+  },
+
+  text: function(message) {
+    return this.frame(message);
+  },
+
+  binary: function(message) {
+    return false;
+  },
+
+  ping: function() {
+    return false;
+  },
+
+  pong: function() {
+      return false;
+  },
+
+  close: function(reason, code) {
+    if (this.readyState !== 1) return false;
+    this.readyState = 3;
+    this.emit('close', new Base.CloseEvent(null, null));
+    return true;
+  },
+
+  _open: function() {
+    this.readyState = 1;
+    this.__queue.forEach(function(args) { this.frame.apply(this, args) }, this);
+    this.__queue = [];
+    this.emit('open', new Base.OpenEvent());
+  },
+
+  _queue: function(message) {
+    this.__queue.push(message);
+    return true;
+  },
+
+  _write: function(chunk) {
+    var io = this.io;
+    if (io.readable) io.emit('data', chunk);
+  }
+};
+
+for (var key in instance)
+  Base.prototype[key] = instance[key];
+
+
+Base.ConnectEvent = function() {};
+
+Base.OpenEvent = function() {};
+
+Base.CloseEvent = function(code, reason) {
+  this.code   = code;
+  this.reason = reason;
+};
+
+Base.MessageEvent = function(data) {
+  this.data = data;
+};
+
+Base.PingEvent = function(data) {
+  this.data = data;
+};
+
+Base.PongEvent = function(data) {
+  this.data = data;
+};
+
+module.exports = Base;

express-server/node_modules/websocket-driver/lib/websocket/driver/client.js

@@ -0,0 +1,141 @@
+'use strict';
+
+var crypto     = require('crypto'),
+    url        = require('url'),
+    util       = require('util'),
+    HttpParser = require('../http_parser'),
+    Base       = require('./base'),
+    Hybi       = require('./hybi'),
+    Proxy      = require('./proxy');
+
+var Client = function(_url, options) {
+  this.version = 'hybi-13';
+  Hybi.call(this, null, _url, options);
+
+  this.readyState = -1;
+  this._key       = Client.generateKey();
+  this._accept    = Hybi.generateAccept(this._key);
+  this._http      = new HttpParser('response');
+
+  var uri  = url.parse(this.url),
+      auth = uri.auth && new Buffer(uri.auth, 'utf8').toString('base64');
+
+  if (this.VALID_PROTOCOLS.indexOf(uri.protocol) < 0)
+    throw new Error(this.url + ' is not a valid WebSocket URL');
+
+  this._pathname = (uri.pathname || '/') + (uri.search || '');
+
+  this._headers.set('Host', uri.host);
+  this._headers.set('Upgrade', 'websocket');
+  this._headers.set('Connection', 'Upgrade');
+  this._headers.set('Sec-WebSocket-Key', this._key);
+  this._headers.set('Sec-WebSocket-Version', '13');
+
+  if (this._protocols.length > 0)
+    this._headers.set('Sec-WebSocket-Protocol', this._protocols.join(', '));
+
+  if (auth)
+    this._headers.set('Authorization', 'Basic ' + auth);
+};
+util.inherits(Client, Hybi);
+
+Client.generateKey = function() {
+  return crypto.randomBytes(16).toString('base64');
+};
+
+var instance = {
+  VALID_PROTOCOLS: ['ws:', 'wss:'],
+
+  proxy: function(origin, options) {
+    return new Proxy(this, origin, options);
+  },
+
+  start: function() {
+    if (this.readyState !== -1) return false;
+    this._write(this._handshakeRequest());
+    this.readyState = 0;
+    return true;
+  },
+
+  parse: function(chunk) {
+    if (this.readyState === 3) return;
+    if (this.readyState > 0) return Hybi.prototype.parse.call(this, chunk);
+
+    this._http.parse(chunk);
+    if (!this._http.isComplete()) return;
+
+    this._validateHandshake();
+    if (this.readyState === 3) return;
+
+    this._open();
+    this.parse(this._http.body);
+  },
+
+  _handshakeRequest: function() {
+    var extensions = this._extensions.generateOffer();
+    if (extensions)
+      this._headers.set('Sec-WebSocket-Extensions', extensions);
+
+    var start   = 'GET ' + this._pathname + ' HTTP/1.1',
+        headers = [start, this._headers.toString(), ''];
+
+    return new Buffer(headers.join('\r\n'), 'utf8');
+  },
+
+  _failHandshake: function(message) {
+    message = 'Error during WebSocket handshake: ' + message;
+    this.readyState = 3;
+    this.emit('error', new Error(message));
+    this.emit('close', new Base.CloseEvent(this.ERRORS.protocol_error, message));
+  },
+
+  _validateHandshake: function() {
+    this.statusCode = this._http.statusCode;
+    this.headers    = this._http.headers;
+
+    if (this._http.error)
+      return this._failHandshake(this._http.error.message);
+
+    if (this._http.statusCode !== 101)
+      return this._failHandshake('Unexpected response code: ' + this._http.statusCode);
+
+    var headers    = this._http.headers,
+        upgrade    = headers['upgrade'] || '',
+        connection = headers['connection'] || '',
+        accept     = headers['sec-websocket-accept'] || '',
+        protocol   = headers['sec-websocket-protocol'] || '';
+
+    if (upgrade === '')
+      return this._failHandshake("'Upgrade' header is missing");
+    if (upgrade.toLowerCase() !== 'websocket')
+      return this._failHandshake("'Upgrade' header value is not 'WebSocket'");
+
+    if (connection === '')
+      return this._failHandshake("'Connection' header is missing");
+    if (connection.toLowerCase() !== 'upgrade')
+      return this._failHandshake("'Connection' header value is not 'Upgrade'");
+
+    if (accept !== this._accept)
+      return this._failHandshake('Sec-WebSocket-Accept mismatch');
+
+    this.protocol = null;
+
+    if (protocol !== '') {
+      if (this._protocols.indexOf(protocol) < 0)
+        return this._failHandshake('Sec-WebSocket-Protocol mismatch');
+      else
+        this.protocol = protocol;
+    }
+
+    try {
+      this._extensions.activate(this.headers['sec-websocket-extensions']);
+    } catch (e) {
+      return this._failHandshake(e.message);
+    }
+  }
+};
+
+for (var key in instance)
+  Client.prototype[key] = instance[key];
+
+module.exports = Client;

express-server/node_modules/websocket-driver/lib/websocket/driver/draft75.js

@@ -0,0 +1,122 @@
+'use strict';
+
+var Base = require('./base'),
+    util = require('util');
+
+var Draft75 = function(request, url, options) {
+  Base.apply(this, arguments);
+  this._stage  = 0;
+  this.version = 'hixie-75';
+
+  this._headers.set('Upgrade', 'WebSocket');
+  this._headers.set('Connection', 'Upgrade');
+  this._headers.set('WebSocket-Origin', this._request.headers.origin);
+  this._headers.set('WebSocket-Location', this.url);
+};
+util.inherits(Draft75, Base);
+
+var instance = {
+  close: function() {
+    if (this.readyState === 3) return false;
+    this.readyState = 3;
+    this.emit('close', new Base.CloseEvent(null, null));
+    return true;
+  },
+
+  parse: function(chunk) {
+    if (this.readyState > 1) return;
+
+    this._reader.put(chunk);
+
+    this._reader.eachByte(function(octet) {
+      var message;
+
+      switch (this._stage) {
+        case -1:
+          this._body.push(octet);
+          this._sendHandshakeBody();
+          break;
+
+        case 0:
+          this._parseLeadingByte(octet);
+          break;
+
+        case 1:
+          this._length = (octet & 0x7F) + 128 * this._length;
+
+          if (this._closing && this._length === 0) {
+            return this.close();
+          }
+          else if ((octet & 0x80) !== 0x80) {
+            if (this._length === 0) {
+              this._stage = 0;
+            }
+            else {
+              this._skipped = 0;
+              this._stage   = 2;
+            }
+          }
+          break;
+
+        case 2:
+          if (octet === 0xFF) {
+            this._stage = 0;
+            message = new Buffer(this._buffer).toString('utf8', 0, this._buffer.length);
+            this.emit('message', new Base.MessageEvent(message));
+          }
+          else {
+            if (this._length) {
+              this._skipped += 1;
+              if (this._skipped === this._length)
+                this._stage = 0;
+            } else {
+              this._buffer.push(octet);
+              if (this._buffer.length > this._maxLength) return this.close();
+            }
+          }
+          break;
+      }
+    }, this);
+  },
+
+  frame: function(buffer) {
+    if (this.readyState === 0) return this._queue([buffer]);
+    if (this.readyState > 1) return false;
+
+    if (typeof buffer !== 'string') buffer = buffer.toString();
+
+    var payload = new Buffer(buffer, 'utf8'),
+        frame   = new Buffer(payload.length + 2);
+
+    frame[0] = 0x00;
+    frame[payload.length + 1] = 0xFF;
+    payload.copy(frame, 1);
+
+    this._write(frame);
+    return true;
+  },
+
+  _handshakeResponse: function() {
+    var start   = 'HTTP/1.1 101 Web Socket Protocol Handshake',
+        headers = [start, this._headers.toString(), ''];
+
+    return new Buffer(headers.join('\r\n'), 'utf8');
+  },
+
+  _parseLeadingByte: function(octet) {
+    if ((octet & 0x80) === 0x80) {
+      this._length = 0;
+      this._stage  = 1;
+    } else {
+      delete this._length;
+      delete this._skipped;
+      this._buffer = [];
+      this._stage  = 2;
+    }
+  }
+};
+
+for (var key in instance)
+  Draft75.prototype[key] = instance[key];
+
+module.exports = Draft75;

express-server/node_modules/websocket-driver/lib/websocket/driver/draft76.js

@@ -0,0 +1,116 @@
+'use strict';
+
+var Base    = require('./base'),
+    Draft75 = require('./draft75'),
+    crypto  = require('crypto'),
+    util    = require('util');
+
+
+var numberFromKey = function(key) {
+  return parseInt(key.match(/[0-9]/g).join(''), 10);
+};
+
+var spacesInKey = function(key) {
+  return key.match(/ /g).length;
+};
+
+
+var Draft76 = function(request, url, options) {
+  Draft75.apply(this, arguments);
+  this._stage  = -1;
+  this._body   = [];
+  this.version = 'hixie-76';
+
+  this._headers.clear();
+
+  this._headers.set('Upgrade', 'WebSocket');
+  this._headers.set('Connection', 'Upgrade');
+  this._headers.set('Sec-WebSocket-Origin', this._request.headers.origin);
+  this._headers.set('Sec-WebSocket-Location', this.url);
+};
+util.inherits(Draft76, Draft75);
+
+var instance = {
+  BODY_SIZE: 8,
+
+  start: function() {
+    if (!Draft75.prototype.start.call(this)) return false;
+    this._started = true;
+    this._sendHandshakeBody();
+    return true;
+  },
+
+  close: function() {
+    if (this.readyState === 3) return false;
+    this._write(new Buffer([0xFF, 0x00]));
+    this.readyState = 3;
+    this.emit('close', new Base.CloseEvent(null, null));
+    return true;
+  },
+
+  _handshakeResponse: function() {
+    var headers = this._request.headers,
+
+        key1    = headers['sec-websocket-key1'],
+        number1 = numberFromKey(key1),
+        spaces1 = spacesInKey(key1),
+
+        key2    = headers['sec-websocket-key2'],
+        number2 = numberFromKey(key2),
+        spaces2 = spacesInKey(key2);
+
+    if (number1 % spaces1 !== 0 || number2 % spaces2 !== 0) {
+      this.emit('error', new Error('Client sent invalid Sec-WebSocket-Key headers'));
+      this.close();
+      return null;
+    }
+
+    this._keyValues = [number1 / spaces1, number2 / spaces2];
+
+    var start   = 'HTTP/1.1 101 WebSocket Protocol Handshake',
+        headers = [start, this._headers.toString(), ''];
+
+    return new Buffer(headers.join('\r\n'), 'binary');
+  },
+
+  _handshakeSignature: function() {
+    if (this._body.length < this.BODY_SIZE) return null;
+
+    var md5    = crypto.createHash('md5'),
+        buffer = new Buffer(8 + this.BODY_SIZE);
+
+    buffer.writeUInt32BE(this._keyValues[0], 0);
+    buffer.writeUInt32BE(this._keyValues[1], 4);
+    new Buffer(this._body).copy(buffer, 8, 0, this.BODY_SIZE);
+
+    md5.update(buffer);
+    return new Buffer(md5.digest('binary'), 'binary');
+  },
+
+  _sendHandshakeBody: function() {
+    if (!this._started) return;
+    var signature = this._handshakeSignature();
+    if (!signature) return;
+
+    this._write(signature);
+    this._stage = 0;
+    this._open();
+
+    if (this._body.length > this.BODY_SIZE)
+      this.parse(this._body.slice(this.BODY_SIZE));
+  },
+
+  _parseLeadingByte: function(octet) {
+    if (octet !== 0xFF)
+      return Draft75.prototype._parseLeadingByte.call(this, octet);
+
+    this._closing = true;
+    this._length  = 0;
+    this._stage   = 1;
+  }
+};
+
+for (var key in instance)
+  Draft76.prototype[key] = instance[key];
+
+module.exports = Draft76;

express-server/node_modules/websocket-driver/lib/websocket/driver/headers.js

@@ -0,0 +1,35 @@
+'use strict';
+
+var Headers = function() {
+  this.clear();
+};
+
+Headers.prototype.ALLOWED_DUPLICATES = ['set-cookie', 'set-cookie2', 'warning', 'www-authenticate'];
+
+Headers.prototype.clear = function() {
+  this._sent  = {};
+  this._lines = [];
+};
+
+Headers.prototype.set = function(name, value) {
+  if (value === undefined) return;
+
+  name = this._strip(name);
+  value = this._strip(value);
+
+  var key = name.toLowerCase();
+  if (!this._sent.hasOwnProperty(key) || this.ALLOWED_DUPLICATES.indexOf(key) >= 0) {
+    this._sent[key] = true;
+    this._lines.push(name + ': ' + value + '\r\n');
+  }
+};
+
+Headers.prototype.toString = function() {
+  return this._lines.join('');
+};
+
+Headers.prototype._strip = function(string) {
+  return string.toString().replace(/^ */, '').replace(/ *$/, '');
+};
+
+module.exports = Headers;

express-server/node_modules/websocket-driver/lib/websocket/driver/hybi.js

@@ -0,0 +1,477 @@
+'use strict';
+
+var crypto     = require('crypto'),
+    util       = require('util'),
+    Extensions = require('websocket-extensions'),
+    Base       = require('./base'),
+    Frame      = require('./hybi/frame'),
+    Message    = require('./hybi/message');
+
+var Hybi = function(request, url, options) {
+  Base.apply(this, arguments);
+
+  this._extensions     = new Extensions();
+  this._stage          = 0;
+  this._masking        = this._options.masking;
+  this._protocols      = this._options.protocols || [];
+  this._requireMasking = this._options.requireMasking;
+  this._pingCallbacks  = {};
+
+  if (typeof this._protocols === 'string')
+    this._protocols = this._protocols.split(/ *, */);
+
+  if (!this._request) return;
+
+  var secKey    = this._request.headers['sec-websocket-key'],
+      protos    = this._request.headers['sec-websocket-protocol'],
+      version   = this._request.headers['sec-websocket-version'],
+      supported = this._protocols;
+
+  this._headers.set('Upgrade', 'websocket');
+  this._headers.set('Connection', 'Upgrade');
+  this._headers.set('Sec-WebSocket-Accept', Hybi.generateAccept(secKey));
+
+  if (protos !== undefined) {
+    if (typeof protos === 'string') protos = protos.split(/ *, */);
+    this.protocol = protos.filter(function(p) { return supported.indexOf(p) >= 0 })[0];
+    if (this.protocol) this._headers.set('Sec-WebSocket-Protocol', this.protocol);
+  }
+
+  this.version = 'hybi-' + version;
+};
+util.inherits(Hybi, Base);
+
+Hybi.mask = function(payload, mask, offset) {
+  if (!mask || mask.length === 0) return payload;
+  offset = offset || 0;
+
+  for (var i = 0, n = payload.length - offset; i < n; i++) {
+    payload[offset + i] = payload[offset + i] ^ mask[i % 4];
+  }
+  return payload;
+};
+
+Hybi.generateAccept = function(key) {
+  var sha1 = crypto.createHash('sha1');
+  sha1.update(key + Hybi.GUID);
+  return sha1.digest('base64');
+};
+
+Hybi.GUID = '258EAFA5-E914-47DA-95CA-C5AB0DC85B11';
+
+var instance = {
+  FIN:    0x80,
+  MASK:   0x80,
+  RSV1:   0x40,
+  RSV2:   0x20,
+  RSV3:   0x10,
+  OPCODE: 0x0F,
+  LENGTH: 0x7F,
+
+  OPCODES: {
+    continuation: 0,
+    text:         1,
+    binary:       2,
+    close:        8,
+    ping:         9,
+    pong:         10
+  },
+
+  OPCODE_CODES:    [0, 1, 2, 8, 9, 10],
+  MESSAGE_OPCODES: [0, 1, 2],
+  OPENING_OPCODES: [1, 2],
+
+  ERRORS: {
+    normal_closure:       1000,
+    going_away:           1001,
+    protocol_error:       1002,
+    unacceptable:         1003,
+    encoding_error:       1007,
+    policy_violation:     1008,
+    too_large:            1009,
+    extension_error:      1010,
+    unexpected_condition: 1011
+  },
+
+  ERROR_CODES:        [1000, 1001, 1002, 1003, 1007, 1008, 1009, 1010, 1011],
+  DEFAULT_ERROR_CODE: 1000,
+  MIN_RESERVED_ERROR: 3000,
+  MAX_RESERVED_ERROR: 4999,
+
+  // http://www.w3.org/International/questions/qa-forms-utf-8.en.php
+  UTF8_MATCH: /^([\x00-\x7F]|[\xC2-\xDF][\x80-\xBF]|\xE0[\xA0-\xBF][\x80-\xBF]|[\xE1-\xEC\xEE\xEF][\x80-\xBF]{2}|\xED[\x80-\x9F][\x80-\xBF]|\xF0[\x90-\xBF][\x80-\xBF]{2}|[\xF1-\xF3][\x80-\xBF]{3}|\xF4[\x80-\x8F][\x80-\xBF]{2})*$/,
+
+  addExtension: function(extension) {
+    this._extensions.add(extension);
+    return true;
+  },
+
+  parse: function(chunk) {
+    this._reader.put(chunk);
+    var buffer = true;
+    while (buffer) {
+      switch (this._stage) {
+        case 0:
+          buffer = this._reader.read(1);
+          if (buffer) this._parseOpcode(buffer[0]);
+          break;
+
+        case 1:
+          buffer = this._reader.read(1);
+          if (buffer) this._parseLength(buffer[0]);
+          break;
+
+        case 2:
+          buffer = this._reader.read(this._frame.lengthBytes);
+          if (buffer) this._parseExtendedLength(buffer);
+          break;
+
+        case 3:
+          buffer = this._reader.read(4);
+          if (buffer) {
+            this._stage = 4;
+            this._frame.maskingKey = buffer;
+          }
+          break;
+
+        case 4:
+          buffer = this._reader.read(this._frame.length);
+          if (buffer) {
+            this._stage = 0;
+            this._emitFrame(buffer);
+          }
+          break;
+
+        default:
+          buffer = null;
+      }
+    }
+  },
+
+  text: function(message) {
+    if (this.readyState > 1) return false;
+    return this.frame(message, 'text');
+  },
+
+  binary: function(message) {
+    if (this.readyState > 1) return false;
+    return this.frame(message, 'binary');
+  },
+
+  ping: function(message, callback) {
+    if (this.readyState > 1) return false;
+    message = message || '';
+    if (callback) this._pingCallbacks[message] = callback;
+    return this.frame(message, 'ping');
+  },
+
+  pong: function(message) {
+      if (this.readyState > 1) return false;
+      message = message ||'';
+      return this.frame(message, 'pong');
+  },
+
+  close: function(reason, code) {
+    reason = reason || '';
+    code   = code   || this.ERRORS.normal_closure;
+
+    if (this.readyState <= 0) {
+      this.readyState = 3;
+      this.emit('close', new Base.CloseEvent(code, reason));
+      return true;
+    } else if (this.readyState === 1) {
+      this.readyState = 2;
+      this._extensions.close(function() { this.frame(reason, 'close', code) }, this);
+      return true;
+    } else {
+      return false;
+    }
+  },
+
+  frame: function(buffer, type, code) {
+    if (this.readyState <= 0) return this._queue([buffer, type, code]);
+    if (this.readyState > 2) return false;
+
+    if (buffer instanceof Array)    buffer = new Buffer(buffer);
+    if (typeof buffer === 'number') buffer = buffer.toString();
+
+    var message = new Message(),
+        isText  = (typeof buffer === 'string'),
+        payload, copy;
+
+    message.rsv1   = message.rsv2 = message.rsv3 = false;
+    message.opcode = this.OPCODES[type || (isText ? 'text' : 'binary')];
+
+    payload = isText ? new Buffer(buffer, 'utf8') : buffer;
+
+    if (code) {
+      copy = payload;
+      payload = new Buffer(2 + copy.length);
+      payload.writeUInt16BE(code, 0);
+      copy.copy(payload, 2);
+    }
+    message.data = payload;
+
+    var onMessageReady = function(message) {
+      var frame = new Frame();
+
+      frame.final   = true;
+      frame.rsv1    = message.rsv1;
+      frame.rsv2    = message.rsv2;
+      frame.rsv3    = message.rsv3;
+      frame.opcode  = message.opcode;
+      frame.masked  = !!this._masking;
+      frame.length  = message.data.length;
+      frame.payload = message.data;
+
+      if (frame.masked) frame.maskingKey = crypto.randomBytes(4);
+
+      this._sendFrame(frame);
+    };
+
+    if (this.MESSAGE_OPCODES.indexOf(message.opcode) >= 0)
+      this._extensions.processOutgoingMessage(message, function(error, message) {
+        if (error) return this._fail('extension_error', error.message);
+        onMessageReady.call(this, message);
+      }, this);
+    else
+      onMessageReady.call(this, message);
+
+    return true;
+  },
+
+  _sendFrame: function(frame) {
+    var length = frame.length,
+        header = (length <= 125) ? 2 : (length <= 65535 ? 4 : 10),
+        offset = header + (frame.masked ? 4 : 0),
+        buffer = new Buffer(offset + length),
+        masked = frame.masked ? this.MASK : 0;
+
+    buffer[0] = (frame.final ? this.FIN : 0) |
+                (frame.rsv1 ? this.RSV1 : 0) |
+                (frame.rsv2 ? this.RSV2 : 0) |
+                (frame.rsv3 ? this.RSV3 : 0) |
+                frame.opcode;
+
+    if (length <= 125) {
+      buffer[1] = masked | length;
+    } else if (length <= 65535) {
+      buffer[1] = masked | 126;
+      buffer.writeUInt16BE(length, 2);
+    } else {
+      buffer[1] = masked | 127;
+      buffer.writeUInt32BE(Math.floor(length / 0x100000000), 2);
+      buffer.writeUInt32BE(length % 0x100000000, 6);
+    }
+
+    frame.payload.copy(buffer, offset);
+
+    if (frame.masked) {
+      frame.maskingKey.copy(buffer, header);
+      Hybi.mask(buffer, frame.maskingKey, offset);
+    }
+
+    this._write(buffer);
+  },
+
+  _handshakeResponse: function() {
+    try {
+      var extensions = this._extensions.generateResponse(this._request.headers['sec-websocket-extensions']);
+    } catch (e) {
+      return this._fail('protocol_error', e.message);
+    }
+
+    if (extensions) this._headers.set('Sec-WebSocket-Extensions', extensions);
+
+    var start   = 'HTTP/1.1 101 Switching Protocols',
+        headers = [start, this._headers.toString(), ''];
+
+    return new Buffer(headers.join('\r\n'), 'utf8');
+  },
+
+  _shutdown: function(code, reason, error) {
+    delete this._frame;
+    delete this._message;
+    this._stage = 5;
+
+    var sendCloseFrame = (this.readyState === 1);
+    this.readyState = 2;
+
+    this._extensions.close(function() {
+      if (sendCloseFrame) this.frame(reason, 'close', code);
+      this.readyState = 3;
+      if (error) this.emit('error', new Error(reason));
+      this.emit('close', new Base.CloseEvent(code, reason));
+    }, this);
+  },
+
+  _fail: function(type, message) {
+    if (this.readyState > 1) return;
+    this._shutdown(this.ERRORS[type], message, true);
+  },
+
+  _parseOpcode: function(octet) {
+    var rsvs = [this.RSV1, this.RSV2, this.RSV3].map(function(rsv) {
+      return (octet & rsv) === rsv;
+    });
+
+    var frame = this._frame = new Frame();
+
+    frame.final  = (octet & this.FIN) === this.FIN;
+    frame.rsv1   = rsvs[0];
+    frame.rsv2   = rsvs[1];
+    frame.rsv3   = rsvs[2];
+    frame.opcode = (octet & this.OPCODE);
+
+    this._stage = 1;
+
+    if (!this._extensions.validFrameRsv(frame))
+      return this._fail('protocol_error',
+          'One or more reserved bits are on: reserved1 = ' + (frame.rsv1 ? 1 : 0) +
+          ', reserved2 = ' + (frame.rsv2 ? 1 : 0) +
+          ', reserved3 = ' + (frame.rsv3 ? 1 : 0));
+
+    if (this.OPCODE_CODES.indexOf(frame.opcode) < 0)
+      return this._fail('protocol_error', 'Unrecognized frame opcode: ' + frame.opcode);
+
+    if (this.MESSAGE_OPCODES.indexOf(frame.opcode) < 0 && !frame.final)
+      return this._fail('protocol_error', 'Received fragmented control frame: opcode = ' + frame.opcode);
+
+    if (this._message && this.OPENING_OPCODES.indexOf(frame.opcode) >= 0)
+      return this._fail('protocol_error', 'Received new data frame but previous continuous frame is unfinished');
+  },
+
+  _parseLength: function(octet) {
+    var frame = this._frame;
+    frame.masked = (octet & this.MASK) === this.MASK;
+    frame.length = (octet & this.LENGTH);
+
+    if (frame.length >= 0 && frame.length <= 125) {
+      this._stage = frame.masked ? 3 : 4;
+      if (!this._checkFrameLength()) return;
+    } else {
+      this._stage = 2;
+      frame.lengthBytes = (frame.length === 126 ? 2 : 8);
+    }
+
+    if (this._requireMasking && !frame.masked)
+      return this._fail('unacceptable', 'Received unmasked frame but masking is required');
+  },
+
+  _parseExtendedLength: function(buffer) {
+    var frame = this._frame;
+    frame.length = this._readUInt(buffer);
+
+    this._stage = frame.masked ? 3 : 4;
+
+    if (this.MESSAGE_OPCODES.indexOf(frame.opcode) < 0 && frame.length > 125)
+      return this._fail('protocol_error', 'Received control frame having too long payload: ' + frame.length);
+
+    if (!this._checkFrameLength()) return;
+  },
+
+  _checkFrameLength: function() {
+    var length = this._message ? this._message.length : 0;
+
+    if (length + this._frame.length > this._maxLength) {
+      this._fail('too_large', 'WebSocket frame length too large');
+      return false;
+    } else {
+      return true;
+    }
+  },
+
+  _emitFrame: function(buffer) {
+    var frame   = this._frame,
+        payload = frame.payload = Hybi.mask(buffer, frame.maskingKey),
+        opcode  = frame.opcode,
+        message,
+        code, reason,
+        callbacks, callback;
+
+    delete this._frame;
+
+    if (opcode === this.OPCODES.continuation) {
+      if (!this._message) return this._fail('protocol_error', 'Received unexpected continuation frame');
+      this._message.pushFrame(frame);
+    }
+
+    if (opcode === this.OPCODES.text || opcode === this.OPCODES.binary) {
+      this._message = new Message();
+      this._message.pushFrame(frame);
+    }
+
+    if (frame.final && this.MESSAGE_OPCODES.indexOf(opcode) >= 0)
+      return this._emitMessage(this._message);
+
+    if (opcode === this.OPCODES.close) {
+      code   = (payload.length >= 2) ? payload.readUInt16BE(0) : null;
+      reason = (payload.length > 2) ? this._encode(payload.slice(2)) : null;
+
+      if (!(payload.length === 0) &&
+          !(code !== null && code >= this.MIN_RESERVED_ERROR && code <= this.MAX_RESERVED_ERROR) &&
+          this.ERROR_CODES.indexOf(code) < 0)
+        code = this.ERRORS.protocol_error;
+
+      if (payload.length > 125 || (payload.length > 2 && !reason))
+        code = this.ERRORS.protocol_error;
+
+      this._shutdown(code || this.DEFAULT_ERROR_CODE, reason || '');
+    }
+
+    if (opcode === this.OPCODES.ping) {
+      this.frame(payload, 'pong');
+      this.emit('ping', new Base.PingEvent(payload.toString()))
+    }
+
+    if (opcode === this.OPCODES.pong) {
+      callbacks = this._pingCallbacks;
+      message   = this._encode(payload);
+      callback  = callbacks[message];
+
+      delete callbacks[message];
+      if (callback) callback()
+
+      this.emit('pong', new Base.PongEvent(payload.toString()))
+    }
+  },
+
+  _emitMessage: function(message) {
+    var message = this._message;
+    message.read();
+
+    delete this._message;
+
+    this._extensions.processIncomingMessage(message, function(error, message) {
+      if (error) return this._fail('extension_error', error.message);
+
+      var payload = message.data;
+      if (message.opcode === this.OPCODES.text) payload = this._encode(payload);
+
+      if (payload === null)
+        return this._fail('encoding_error', 'Could not decode a text frame as UTF-8');
+      else
+        this.emit('message', new Base.MessageEvent(payload));
+    }, this);
+  },
+
+  _encode: function(buffer) {
+    try {
+      var string = buffer.toString('binary', 0, buffer.length);
+      if (!this.UTF8_MATCH.test(string)) return null;
+    } catch (e) {}
+    return buffer.toString('utf8', 0, buffer.length);
+  },
+
+  _readUInt: function(buffer) {
+    if (buffer.length === 2) return buffer.readUInt16BE(0);
+
+    return buffer.readUInt32BE(0) * 0x100000000 +
+           buffer.readUInt32BE(4);
+  }
+};
+
+for (var key in instance)
+  Hybi.prototype[key] = instance[key];
+
+module.exports = Hybi;

express-server/node_modules/websocket-driver/lib/websocket/driver/hybi/frame.js

@@ -0,0 +1,21 @@
+'use strict';
+
+var Frame = function() {};
+
+var instance = {
+  final:        false,
+  rsv1:         false,
+  rsv2:         false,
+  rsv3:         false,
+  opcode:       null,
+  masked:       false,
+  maskingKey:   null,
+  lengthBytes:  1,
+  length:       0,
+  payload:      null
+};
+
+for (var key in instance)
+  Frame.prototype[key] = instance[key];
+
+module.exports = Frame;

express-server/node_modules/websocket-driver/lib/websocket/driver/hybi/message.js

@@ -0,0 +1,41 @@
+'use strict';
+
+var Message = function() {
+  this.rsv1    = false;
+  this.rsv2    = false;
+  this.rsv3    = false;
+  this.opcode  = null
+  this.length  = 0;
+  this._chunks = [];
+};
+
+var instance = {
+  read: function() {
+    if (this.data) return this.data;
+
+    this.data  = new Buffer(this.length);
+    var offset = 0;
+
+    for (var i = 0, n = this._chunks.length; i < n; i++) {
+      this._chunks[i].copy(this.data, offset);
+      offset += this._chunks[i].length;
+    }
+    return this.data;
+  },
+
+  pushFrame: function(frame) {
+    this.rsv1 = this.rsv1 || frame.rsv1;
+    this.rsv2 = this.rsv2 || frame.rsv2;
+    this.rsv3 = this.rsv3 || frame.rsv3;
+
+    if (this.opcode === null) this.opcode = frame.opcode;
+
+    this._chunks.push(frame.payload);
+    this.length += frame.length;
+  }
+};
+
+for (var key in instance)
+  Message.prototype[key] = instance[key];
+
+module.exports = Message;

express-server/node_modules/websocket-driver/lib/websocket/driver/proxy.js

@@ -0,0 +1,98 @@
+'use strict';
+
+var Stream     = require('stream').Stream,
+    url        = require('url'),
+    util       = require('util'),
+    Base       = require('./base'),
+    Headers    = require('./headers'),
+    HttpParser = require('../http_parser');
+
+var PORTS = {'ws:': 80, 'wss:': 443};
+
+var Proxy = function(client, origin, options) {
+  this._client  = client;
+  this._http    = new HttpParser('response');
+  this._origin  = (typeof client.url === 'object') ? client.url : url.parse(client.url);
+  this._url     = (typeof origin === 'object') ? origin : url.parse(origin);
+  this._options = options || {};
+  this._state   = 0;
+
+  this.readable = this.writable = true;
+  this._paused  = false;
+
+  this._headers = new Headers();
+  this._headers.set('Host', this._origin.host);
+  this._headers.set('Connection', 'keep-alive');
+  this._headers.set('Proxy-Connection', 'keep-alive');
+
+  var auth = this._url.auth && new Buffer(this._url.auth, 'utf8').toString('base64');
+  if (auth) this._headers.set('Proxy-Authorization', 'Basic ' + auth);
+};
+util.inherits(Proxy, Stream);
+
+var instance = {
+  setHeader: function(name, value) {
+    if (this._state !== 0) return false;
+    this._headers.set(name, value);
+    return true;
+  },
+
+  start: function() {
+    if (this._state !== 0) return false;
+    this._state = 1;
+
+    var origin = this._origin,
+        port   = origin.port || PORTS[origin.protocol],
+        start  = 'CONNECT ' + origin.hostname + ':' + port + ' HTTP/1.1';
+
+    var headers = [start, this._headers.toString(), ''];
+
+    this.emit('data', new Buffer(headers.join('\r\n'), 'utf8'));
+    return true;
+  },
+
+  pause: function() {
+    this._paused = true;
+  },
+
+  resume: function() {
+    this._paused = false;
+    this.emit('drain');
+  },
+
+  write: function(chunk) {
+    if (!this.writable) return false;
+
+    this._http.parse(chunk);
+    if (!this._http.isComplete()) return !this._paused;
+
+    this.statusCode = this._http.statusCode;
+    this.headers    = this._http.headers;
+
+    if (this.statusCode === 200) {
+      this.emit('connect', new Base.ConnectEvent());
+    } else {
+      var message = "Can't establish a connection to the server at " + this._origin.href;
+      this.emit('error', new Error(message));
+    }
+    this.end();
+    return !this._paused;
+  },
+
+  end: function(chunk) {
+    if (!this.writable) return;
+    if (chunk !== undefined) this.write(chunk);
+    this.readable = this.writable = false;
+    this.emit('close');
+    this.emit('end');
+  },
+
+  destroy: function() {
+    this.end();
+  }
+};
+
+for (var key in instance)
+  Proxy.prototype[key] = instance[key];
+
+module.exports = Proxy;

express-server/node_modules/websocket-driver/lib/websocket/driver/server.js

@@ -0,0 +1,108 @@
+'use strict';
+
+var util       = require('util'),
+    HttpParser = require('../http_parser'),
+    Base       = require('./base'),
+    Draft75    = require('./draft75'),
+    Draft76    = require('./draft76'),
+    Hybi       = require('./hybi');
+
+var Server = function(options) {
+  Base.call(this, null, null, options);
+  this._http = new HttpParser('request');
+};
+util.inherits(Server, Base);
+
+var instance = {
+  EVENTS: ['open', 'message', 'error', 'close'],
+
+  _bindEventListeners: function() {
+    this.messages.on('error', function() {});
+    this.on('error', function() {});
+  },
+
+  parse: function(chunk) {
+    if (this._delegate) return this._delegate.parse(chunk);
+
+    this._http.parse(chunk);
+    if (!this._http.isComplete()) return;
+
+    this.method  = this._http.method;
+    this.url     = this._http.url;
+    this.headers = this._http.headers;
+    this.body    = this._http.body;
+
+    var self = this;
+    this._delegate = Server.http(this, this._options);
+    this._delegate.messages = this.messages;
+    this._delegate.io = this.io;
+    this._open();
+
+    this.EVENTS.forEach(function(event) {
+      this._delegate.on(event, function(e) { self.emit(event, e) });
+    }, this);
+
+    this.protocol = this._delegate.protocol;
+    this.version  = this._delegate.version;
+
+    this.parse(this._http.body);
+    this.emit('connect', new Base.ConnectEvent());
+  },
+
+  _open: function() {
+    this.__queue.forEach(function(msg) {
+      this._delegate[msg[0]].apply(this._delegate, msg[1]);
+    }, this);
+    this.__queue = [];
+  }
+};
+
+['addExtension', 'setHeader', 'start', 'frame', 'text', 'binary', 'ping', 'close'].forEach(function(method) {
+  instance[method] = function() {
+    if (this._delegate) {
+      return this._delegate[method].apply(this._delegate, arguments);
+    } else {
+      this.__queue.push([method, arguments]);
+      return true;
+    }
+  };
+});
+
+for (var key in instance)
+  Server.prototype[key] = instance[key];
+
+Server.isSecureRequest = function(request) {
+  if (request.connection && request.connection.authorized !== undefined) return true;
+  if (request.socket && request.socket.secure) return true;
+
+  var headers = request.headers;
+  if (!headers) return false;
+  if (headers['https'] === 'on') return true;
+  if (headers['x-forwarded-ssl'] === 'on') return true;
+  if (headers['x-forwarded-scheme'] === 'https') return true;
+  if (headers['x-forwarded-proto'] === 'https') return true;
+
+  return false;
+};
+
+Server.determineUrl = function(request) {
+  var scheme = this.isSecureRequest(request) ? 'wss:' : 'ws:';
+  return scheme + '//' + request.headers.host + request.url;
+};
+
+Server.http = function(request, options) {
+  options = options || {};
+  if (options.requireMasking === undefined) options.requireMasking = true;
+
+  var headers = request.headers,
+      url     = this.determineUrl(request);
+
+  if (headers['sec-websocket-version'])
+    return new Hybi(request, url, options);
+  else if (headers['sec-websocket-key1'])
+    return new Draft76(request, url, options);
+  else
+    return new Draft75(request, url, options);
+};
+
+module.exports = Server;

express-server/node_modules/websocket-driver/lib/websocket/driver/stream_reader.js

@@ -0,0 +1,80 @@
+'use strict';
+
+var StreamReader = function() {
+  this._queue     = [];
+  this._queueSize = 0;
+  this._offset    = 0;
+};
+
+StreamReader.prototype.put = function(buffer) {
+  if (!buffer || buffer.length === 0) return;
+  if (!buffer.copy) buffer = new Buffer(buffer);
+  this._queue.push(buffer);
+  this._queueSize += buffer.length;
+};
+
+StreamReader.prototype.read = function(length) {
+  if (length > this._queueSize) return null;
+  if (length === 0) return new Buffer(0);
+
+  this._queueSize -= length;
+
+  var queue  = this._queue,
+      remain = length,
+      first  = queue[0],
+      buffers, buffer;
+
+  if (first.length >= length) {
+    if (first.length === length) {
+      return queue.shift();
+    } else {
+      buffer = first.slice(0, length);
+      queue[0] = first.slice(length);
+      return buffer;
+    }
+  }
+
+  for (var i = 0, n = queue.length; i < n; i++) {
+    if (remain < queue[i].length) break;
+    remain -= queue[i].length;
+  }
+  buffers = queue.splice(0, i);
+
+  if (remain > 0 && queue.length > 0) {
+    buffers.push(queue[0].slice(0, remain));
+    queue[0] = queue[0].slice(remain);
+  }
+  return this._concat(buffers, length);
+};
+
+StreamReader.prototype.eachByte = function(callback, context) {
+  var buffer, n, index;
+
+  while (this._queue.length > 0) {
+    buffer = this._queue[0];
+    n = buffer.length;
+
+    while (this._offset < n) {
+      index = this._offset;
+      this._offset += 1;
+      callback.call(context, buffer[index]);
+    }
+    this._offset = 0;
+    this._queue.shift();
+  }
+};
+
+StreamReader.prototype._concat = function(buffers, length) {
+  if (Buffer.concat) return Buffer.concat(buffers, length);
+
+  var buffer = new Buffer(length),
+      offset = 0;
+
+  for (var i = 0, n = buffers.length; i < n; i++) {
+    buffers[i].copy(buffer, offset);
+    offset += buffers[i].length;
+  }
+  return buffer;
+};
+
+module.exports = StreamReader;

express-server/node_modules/websocket-driver/lib/websocket/http_parser.js

@@ -0,0 +1,134 @@
+'use strict';
+
+var NodeHTTPParser = require('http-parser-js').HTTPParser;
+
+var VERSION = process.version.match(/[0-9]+/g).map(function(n) { return parseInt(n, 10) });
+
+var TYPES = {
+  request:  NodeHTTPParser.REQUEST  || 'request',
+  response: NodeHTTPParser.RESPONSE || 'response'
+};
+
+var HttpParser = function(type) {
+  this._type     = type;
+  this._parser   = new NodeHTTPParser(TYPES[type]);
+  this._complete = false;
+  this.headers   = {};
+
+  var current = null,
+      self    = this;
+
+  this._parser.onHeaderField = function(b, start, length) {
+    current = b.toString('utf8', start, start + length).toLowerCase();
+  };
+
+  this._parser.onHeaderValue = function(b, start, length) {
+    var value = b.toString('utf8', start, start + length);
+
+    if (self.headers.hasOwnProperty(current))
+      self.headers[current] += ', ' + value;
+    else
+      self.headers[current] = value;
+  };
+
+  this._parser.onHeadersComplete = this._parser[NodeHTTPParser.kOnHeadersComplete] =
+  function(majorVersion, minorVersion, headers, method, pathname, statusCode) {
+    var info = arguments[0];
+
+    if (typeof info === 'object') {
+      method     = info.method;
+      pathname   = info.url;
+      statusCode = info.statusCode;
+      headers    = info.headers;
+    }
+
+    self.method     = (typeof method === 'number') ? HttpParser.METHODS[method] : method;
+    self.statusCode = statusCode;
+    self.url        = pathname;
+
+    if (!headers) return;
+
+    for (var i = 0, n = headers.length, key, value; i < n; i += 2) {
+      key   = headers[i].toLowerCase();
+      value = headers[i+1];
+      if (self.headers.hasOwnProperty(key))
+        self.headers[key] += ', ' + value;
+      else
+        self.headers[key] = value;
+    }
+
+    self._complete = true;
+  };
+};
+
+HttpParser.METHODS = {
+  0:  'DELETE',
+  1:  'GET',
+  2:  'HEAD',
+  3:  'POST',
+  4:  'PUT',
+  5:  'CONNECT',
+  6:  'OPTIONS',
+  7:  'TRACE',
+  8:  'COPY',
+  9:  'LOCK',
+  10: 'MKCOL',
+  11: 'MOVE',
+  12: 'PROPFIND',
+  13: 'PROPPATCH',
+  14: 'SEARCH',
+  15: 'UNLOCK',
+  16: 'BIND',
+  17: 'REBIND',
+  18: 'UNBIND',
+  19: 'ACL',
+  20: 'REPORT',
+  21: 'MKACTIVITY',
+  22: 'CHECKOUT',
+  23: 'MERGE',
+  24: 'M-SEARCH',
+  25: 'NOTIFY',
+  26: 'SUBSCRIBE',
+  27: 'UNSUBSCRIBE',
+  28: 'PATCH',
+  29: 'PURGE',
+  30: 'MKCALENDAR',
+  31: 'LINK',
+  32: 'UNLINK'
+};
+
+if (VERSION[0] === 0 && VERSION[1] === 12) {
+  HttpParser.METHODS[16] = 'REPORT';
+  HttpParser.METHODS[17] = 'MKACTIVITY';
+  HttpParser.METHODS[18] = 'CHECKOUT';
+  HttpParser.METHODS[19] = 'MERGE';
+  HttpParser.METHODS[20] = 'M-SEARCH';
+  HttpParser.METHODS[21] = 'NOTIFY';
+  HttpParser.METHODS[22] = 'SUBSCRIBE';
+  HttpParser.METHODS[23] = 'UNSUBSCRIBE';
+  HttpParser.METHODS[24] = 'PATCH';
+  HttpParser.METHODS[25] = 'PURGE';
+}
+
+HttpParser.prototype.isComplete = function() {
+  return this._complete;
+};
+
+HttpParser.prototype.parse = function(chunk) {
+  var consumed = this._parser.execute(chunk, 0, chunk.length);
+
+  if (typeof consumed !== 'number') {
+    this.error     = consumed;
+    this._complete = true;
+    return;
+  }
+
+  if (VERSION[0] === 0 && VERSION[1] < 6) consumed += 1;
+
+  if (this._complete)
+    this.body = (consumed < chunk.length)
+              ? chunk.slice(consumed)
+              : new Buffer(0);
+};
+
+module.exports = HttpParser;

express-server/node_modules/websocket-driver/lib/websocket/streams.js

@@ -0,0 +1,146 @@
+'use strict';
+
+/**
+
+Streams in a WebSocket connection
+---------------------------------
+
+We model a WebSocket as two duplex streams: one stream is for the wire protocol
+over an I/O socket, and the other is for incoming/outgoing messages.
+
+
+                        +----------+      +---------+      +----------+
+    [1] write(chunk) -->| ~~~~~~~~ +----->| parse() +----->| ~~~~~~~~ +--> emit('data') [2]
+                        |          |      +----+----+      |          |
+                        |          |           |           |          |
+                        |    IO    |           | [5]       | Messages |
+                        |          |           V           |          |
+                        |          |      +---------+      |          |
+    [4] emit('data') <--+ ~~~~~~~~ |<-----+ frame() |<-----+ ~~~~~~~~ |<-- write(chunk) [3]
+                        +----------+      +---------+      +----------+
+
+
+Message transfer in each direction is simple: IO receives a byte stream [1] and
+sends this stream for parsing. The parser will periodically emit a complete
+message text on the Messages stream [2]. Similarly, when messages are written
+to the Messages stream [3], they are framed using the WebSocket wire format and
+emitted via IO [4].
+
+There is a feedback loop via [5] since some input from [1] will be things like
+ping, pong and close frames. In these cases the protocol responds by emitting
+responses directly back to [4] rather than emitting messages via [2].
+
+For the purposes of flow control, we consider the sources of each Readable
+stream to be as follows:
+
+* [2] receives input from [1]
+* [4] receives input from [1] and [3]
+
+The classes below express the relationships described above without prescribing
+anything about how parse() and frame() work, other than assuming they emit
+'data' events to the IO and Messages streams. They will work with any protocol
+driver having these two methods.
+**/
+
+
+var Stream = require('stream').Stream,
+    util   = require('util');
+
+
+var IO = function(driver) {
+  this.readable = this.writable = true;
+  this._paused  = false;
+  this._driver  = driver;
+};
+util.inherits(IO, Stream);
+
+// The IO pause() and resume() methods will be called when the socket we are
+// piping to gets backed up and drains. Since IO output [4] comes from IO input
+// [1] and Messages input [3], we need to tell both of those to return false
+// from write() when this stream is paused.
+
+IO.prototype.pause = function() {
+  this._paused = true;
+  this._driver.messages._paused = true;
+};
+
+IO.prototype.resume = function() {
+  this._paused = false;
+  this.emit('drain');
+
+  var messages = this._driver.messages;
+  messages._paused = false;
+  messages.emit('drain');
+};
+
+// When we receive input from a socket, send it to the parser and tell the
+// source whether to back off.
+IO.prototype.write = function(chunk) {
+  if (!this.writable) return false;
+  this._driver.parse(chunk);
+  return !this._paused;
+};
+
+// The IO end() method will be called when the socket piping into it emits
+// 'close' or 'end', i.e. the socket is closed. In this situation the Messages
+// stream will not emit any more data so we emit 'end'.
+IO.prototype.end = function(chunk) {
+  if (!this.writable) return;
+  if (chunk !== undefined) this.write(chunk);
+  this.writable = false;
+
+  var messages = this._driver.messages;
+  if (messages.readable) {
+    messages.readable = messages.writable = false;
+    messages.emit('end');
+  }
+};
+
+IO.prototype.destroy = function() {
+  this.end();
+};
+
+
+var Messages = function(driver) {
+  this.readable = this.writable = true;
+  this._paused  = false;
+  this._driver  = driver;
+};
+util.inherits(Messages, Stream);
+
+// The Messages pause() and resume() methods will be called when the app that's
+// processing the messages gets backed up and drains. If we're emitting
+// messages too fast we should tell the source to slow down. Message output [2]
+// comes from IO input [1].
+
+Messages.prototype.pause = function() {
+  this._driver.io._paused = true;
+};
+
+Messages.prototype.resume = function() {
+  this._driver.io._paused = false;
+  this._driver.io.emit('drain');
+};
+
+// When we receive messages from the user, send them to the formatter and tell
+// the source whether to back off.
+Messages.prototype.write = function(message) {
+  if (!this.writable) return false;
+  if (typeof message === 'string') this._driver.text(message);
+  else this._driver.binary(message);
+  return !this._paused;
+};
+
+// The Messages end() method will be called when a stream piping into it emits
+// 'end'. Many streams may be piped into the WebSocket and one of them ending
+// does not mean the whole socket is done, so just process the input and move
+// on leaving the socket open.
+Messages.prototype.end = function(message) {
+  if (message !== undefined) this.write(message);
+};
+
+Messages.prototype.destroy = function() {};
+
+
+exports.IO = IO;
+exports.Messages = Messages;