/**
* Module dependencies.
*/
var EventEmitter = require('events').EventEmitter;
var util = require('util');
var debug = require('debug')('engine:socket');
/**
* Module exports.
*/
module.exports = Socket;
/**
* Client class (abstract).
*
* @api private
*/
function Socket (id, server, transport, req) {
this.id = id;
this.server = server;
this.upgrading = false;
this.upgraded = false;
this.readyState = 'opening';
this.writeBuffer = [];
this.packetsFn = [];
this.sentCallbackFn = [];
this.cleanupFn = [];
this.request = req;
// Cache IP since it might not be in the req later
if (req.websocket && req.websocket._socket) {
this.remoteAddress = req.websocket._socket.remoteAddress;
} else {
this.remoteAddress = req.connection.remoteAddress;
}
this.checkIntervalTimer = null;
this.upgradeTimeoutTimer = null;
this.pingTimeoutTimer = null;
this.setTransport(transport);
this.onOpen();
}
/**
* Inherits from EventEmitter.
*/
util.inherits(Socket, EventEmitter);
/**
* Called upon transport considered open.
*
* @api private
*/
Socket.prototype.onOpen = function () {
this.readyState = 'open';
// sends an `open` packet
this.transport.sid = this.id;
this.sendPacket('open', JSON.stringify({
sid: this.id,
upgrades: this.getAvailableUpgrades(),
pingInterval: this.server.pingInterval,
pingTimeout: this.server.pingTimeout
}));
if (this.server.initialPacket) {
this.sendPacket('message', this.server.initialPacket);
}
this.emit('open');
this.setPingTimeout();
};
/**
* Called upon transport packet.
*
* @param {Object} packet
* @api private
*/
Socket.prototype.onPacket = function (packet) {
if ('open' === this.readyState) {
// export packet event
debug('packet');
this.emit('packet', packet);
// Reset ping timeout on any packet, incoming data is a good sign of
// other side's liveness
this.setPingTimeout();
switch (packet.type) {
case 'ping':
debug('got ping');
this.sendPacket('pong');
this.emit('heartbeat');
break;
case 'error':
this.onClose('parse error');
break;
case 'message':
this.emit('data', packet.data);
this.emit('message', packet.data);
break;
}
} else {
debug('packet received with closed socket');
}
};
/**
* Called upon transport error.
*
* @param {Error} error object
* @api private
*/
Socket.prototype.onError = function (err) {
debug('transport error');
this.onClose('transport error', err);
};
/**
* Sets and resets ping timeout timer based on client pings.
*
* @api private
*/
Socket.prototype.setPingTimeout = function () {
var self = this;
clearTimeout(self.pingTimeoutTimer);
self.pingTimeoutTimer = setTimeout(function () {
self.onClose('ping timeout');
}, self.server.pingInterval + self.server.pingTimeout);
};
/**
* Attaches handlers for the given transport.
*
* @param {Transport} transport
* @api private
*/
Socket.prototype.setTransport = function (transport) {
var onError = this.onError.bind(this);
var onPacket = this.onPacket.bind(this);
var flush = this.flush.bind(this);
var onClose = this.onClose.bind(this, 'transport close');
this.transport = transport;
this.transport.once('error', onError);
this.transport.on('packet', onPacket);
this.transport.on('drain', flush);
this.transport.once('close', onClose);
// this function will manage packet events (also message callbacks)
this.setupSendCallback();
this.cleanupFn.push(function () {
transport.removeListener('error', onError);
transport.removeListener('packet', onPacket);
transport.removeListener('drain', flush);
transport.removeListener('close', onClose);
});
};
/**
* Upgrades socket to the given transport
*
* @param {Transport} transport
* @api private
*/
Socket.prototype.maybeUpgrade = function (transport) {
debug('might upgrade socket transport from "%s" to "%s"'
, this.transport.name, transport.name);
this.upgrading = true;
var self = this;
// set transport upgrade timer
self.upgradeTimeoutTimer = setTimeout(function () {
debug('client did not complete upgrade - closing transport');
cleanup();
if ('open' === transport.readyState) {
transport.close();
}
}, this.server.upgradeTimeout);
function onPacket (packet) {
if ('ping' === packet.type && 'probe' === packet.data) {
transport.send([{ type: 'pong', data: 'probe' }]);
self.emit('upgrading', transport);
clearInterval(self.checkIntervalTimer);
self.checkIntervalTimer = setInterval(check, 100);
} else if ('upgrade' === packet.type && self.readyState !== 'closed') {
debug('got upgrade packet - upgrading');
cleanup();
self.transport.discard();
self.upgraded = true;
self.clearTransport();
self.setTransport(transport);
self.emit('upgrade', transport);
self.setPingTimeout();
self.flush();
if (self.readyState === 'closing') {
transport.close(function () {
self.onClose('forced close');
});
}
} else {
cleanup();
transport.close();
}
}
// we force a polling cycle to ensure a fast upgrade
function check () {
if ('polling' === self.transport.name && self.transport.writable) {
debug('writing a noop packet to polling for fast upgrade');
self.transport.send([{ type: 'noop' }]);
}
}
function cleanup () {
self.upgrading = false;
clearInterval(self.checkIntervalTimer);
self.checkIntervalTimer = null;
clearTimeout(self.upgradeTimeoutTimer);
self.upgradeTimeoutTimer = null;
transport.removeListener('packet', onPacket);
transport.removeListener('close', onTransportClose);
transport.removeListener('error', onError);
self.removeListener('close', onClose);
}
function onError (err) {
debug('client did not complete upgrade - %s', err);
cleanup();
transport.close();
transport = null;
}
function onTransportClose () {
onError('transport closed');
}
function onClose () {
onError('socket closed');
}
transport.on('packet', onPacket);
transport.once('close', onTransportClose);
transport.once('error', onError);
self.once('close', onClose);
};
/**
* Clears listeners and timers associated with current transport.
*
* @api private
*/
Socket.prototype.clearTransport = function () {
var cleanup;
var toCleanUp = this.cleanupFn.length;
for (var i = 0; i < toCleanUp; i++) {
cleanup = this.cleanupFn.shift();
cleanup();
}
// silence further transport errors and prevent uncaught exceptions
this.transport.on('error', function () {
debug('error triggered by discarded transport');
});
// ensure transport won't stay open
this.transport.close();
clearTimeout(this.pingTimeoutTimer);
};
/**
* Called upon transport considered closed.
* Possible reasons: `ping timeout`, `client error`, `parse error`,
* `transport error`, `server close`, `transport close`
*/
Socket.prototype.onClose = function (reason, description) {
if ('closed' !== this.readyState) {
this.readyState = 'closed';
clearTimeout(this.pingTimeoutTimer);
clearInterval(this.checkIntervalTimer);
this.checkIntervalTimer = null;
clearTimeout(this.upgradeTimeoutTimer);
var self = this;
// clean writeBuffer in next tick, so developers can still
// grab the writeBuffer on 'close' event
process.nextTick(function () {
self.writeBuffer = [];
});
this.packetsFn = [];
this.sentCallbackFn = [];
this.clearTransport();
this.emit('close', reason, description);
}
};
/**
* Setup and manage send callback
*
* @api private
*/
Socket.prototype.setupSendCallback = function () {
var self = this;
this.transport.on('drain', onDrain);
this.cleanupFn.push(function () {
self.transport.removeListener('drain', onDrain);
});
// the message was sent successfully, execute the callback
function onDrain () {
if (self.sentCallbackFn.length > 0) {
var seqFn = self.sentCallbackFn.splice(0, 1)[0];
if ('function' === typeof seqFn) {
debug('executing send callback');
seqFn(self.transport);
} else if (Array.isArray(seqFn)) {
debug('executing batch send callback');
for (var l = seqFn.length, i = 0; i < l; i++) {
if ('function' === typeof seqFn[i]) {
seqFn[i](self.transport);
}
}
}
}
}
};
/**
* Sends a message packet.
*
* @param {String} message
* @param {Object} options
* @param {Function} callback
* @return {Socket} for chaining
* @api public
*/
Socket.prototype.send =
Socket.prototype.write = function (data, options, callback) {
this.sendPacket('message', data, options, callback);
return this;
};
/**
* Sends a packet.
*
* @param {String} packet type
* @param {String} optional, data
* @param {Object} options
* @api private
*/
Socket.prototype.sendPacket = function (type, data, options, callback) {
if ('function' === typeof options) {
callback = options;
options = null;
}
options = options || {};
options.compress = false !== options.compress;
if ('closing' !== this.readyState && 'closed' !== this.readyState) {
debug('sending packet "%s" (%s)', type, data);
var packet = {
type: type,
options: options
};
if (data) packet.data = data;
// exports packetCreate event
this.emit('packetCreate', packet);
this.writeBuffer.push(packet);
// add send callback to object, if defined
if (callback) this.packetsFn.push(callback);
this.flush();
}
};
/**
* Attempts to flush the packets buffer.
*
* @api private
*/
Socket.prototype.flush = function () {
if ('closed' !== this.readyState &&
this.transport.writable &&
this.writeBuffer.length) {
debug('flushing buffer to transport');
this.emit('flush', this.writeBuffer);
this.server.emit('flush', this, this.writeBuffer);
var wbuf = this.writeBuffer;
this.writeBuffer = [];
if (!this.transport.supportsFraming) {
this.sentCallbackFn.push(this.packetsFn);
} else {
this.sentCallbackFn.push.apply(this.sentCallbackFn, this.packetsFn);
}
this.packetsFn = [];
this.transport.send(wbuf);
this.emit('drain');
this.server.emit('drain', this);
}
};
/**
* Get available upgrades for this socket.
*
* @api private
*/
Socket.prototype.getAvailableUpgrades = function () {
var availableUpgrades = [];
var allUpgrades = this.server.upgrades(this.transport.name);
for (var i = 0, l = allUpgrades.length; i < l; ++i) {
var upg = allUpgrades[i];
if (this.server.transports.indexOf(upg) !== -1) {
availableUpgrades.push(upg);
}
}
return availableUpgrades;
};
/**
* Closes the socket and underlying transport.
*
* @param {Boolean} optional, discard
* @return {Socket} for chaining
* @api public
*/
Socket.prototype.close = function (discard) {
if ('open' !== this.readyState) return;
this.readyState = 'closing';
if (this.writeBuffer.length) {
this.once('drain', this.closeTransport.bind(this, discard));
return;
}
this.closeTransport(discard);
};
/**
* Closes the underlying transport.
*
* @param {Boolean} discard
* @api private
*/
Socket.prototype.closeTransport = function (discard) {
if (discard) this.transport.discard();
this.transport.close(this.onClose.bind(this, 'forced close'));
};