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index.js
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index.js
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/**
* Module dependencies.
*/
var engine = require('engine.io');
var redis = require('redis');
var url = require('url');
var crypto = require('crypto');
var Client = require('./client');
var Subscription = require('./subscription');
var EventEmitter = require('events').EventEmitter;
var debug = require('debug')('mydb');
/**
* Module exports.
*/
module.exports = exports = Server;
/**
* Exports `Client`.
*/
exports.Client = Client;
/**
* Exports `Subscription`
*/
exports.Subscription = Subscription;
/**
* Server.
*
* Options
* - `redis` main redis client
* - `subTimeout` subscription timeout if no client connects (`60000`)
* - `engine` options to pass to engine.io
*
* @param {http.Server} http server to attach to
* @param {Object} options
* @api private
*/
function Server(http, opts){
if (!(this instanceof Server)) return new Server(http, opts);
opts = opts || {};
// redis
var uri = parse(opts.redis || 'localhost:6379');
uri.port = uri.port || 6379;
this.redis = redis.createClient({ url: 'redis://' + uri.host + ':' + uri.port });
this.redisSub = redis.createClient({ url: 'redis://' + uri.host + ':' + uri.port });
this.redisSub.setMaxListeners(0);
this.redis.connect();
this.redisSub.connect();
this.redisUri = uri;
this.subscriptions = {};
// secret for validating subscription payloads
this.secret = opts.secret || 'youareagoodmydbcracker';
// subscription timeout
this.subTimeout = null == opts.subTimeout ? 60000 : opts.subTimeout;
// sids
this.ids = {};
// pending subscriptions
this.pending = {};
opts.engine = opts.engine || {};
if ( ! ( 'allowEIO3' in opts.engine ) ) {
opts.engine.allowEIO3 = true;
}
// initialize engine server
this.http = http;
this.engine = engine.attach(http, opts.engine);
this.engine.on('connection', this.onConnection.bind(this));
// hijack again
var self = this;
var listeners = http.listeners('request').slice();
http.removeAllListeners('request');
http.on('request', function(req, res){
if (0 == req.url.indexOf('/mydb/')) {
debug('intercepting mydb api request');
self.onrequest(req, res);
} else {
for (var i = 0, l = listeners.length; i < l; i++) {
listeners[i].call(http, req, res);
}
}
});
}
/**
* Inherits from `EventEmitter`.
*/
Server.prototype.__proto__ = EventEmitter.prototype;
/**
* Called upon each connection.
*
* @param {Socket} engine.io socket
* @api private
*/
Server.prototype.onConnection = function(socket){
var client = new Client(this, socket);
var id = client.id;
debug('initializing new client %s', id);
var self = this;
this.ids[id] = client;
// handle client close
client.on('close', this.onclose.bind(this, client));
// add pending subscriptions
if (this.pending[id]) {
debug('flushing pending subscriptions to client %s', id);
this.pending[id].forEach(function(sub){
client.add(sub);
});
delete this.pending[id];
}
this.emit('client', client);
};
/**
* Called upon client close.
*
* @param {Client} client
* @api private
*/
Server.prototype.onclose = function(client){
var id = client.id;
debug('client "%s" close', id);
// destroy pending subscriptions
if (this.pending[id]) {
debug('destroying pending subscriptions');
this.pending[id].forEach(function(sus){
sus.destroy();
});
delete this.pending[id];
}
// remove from list of open clients
delete this.ids[id];
};
/**
* Capture SUBSCRIBE packets.
*
* @api private
*/
Server.prototype.subscribe = function(data, fn){
var sid = data.socket_id;
var sub = new Subscription(
this,
data.subscription_id,
data.document_id,
data.fields
);
debug('subscription "%s" for socket id "%s"', sub.id, sid);
var start = Date.now();
if (this.ids[sid]) {
this.ids[sid].add(sub);
} else {
this.buffer(sid, sub);
}
sub.once('error', onerror);
sub.on('subscribed', onsubscribe);
function onerror(err){
sub.removeListener('subscribed', onsubscribe);
fn(err);
}
function onsubscribe(){
debug('subscribe took %dms', Date.now() - start);
sub.removeListener('error', onerror);
fn(null);
}
};
/**
* Handle an incoming HTTP request.
*
* @param {String} socket id
* @api private
*/
Server.prototype.onrequest = function(req, res){
if ('/mydb/subscribe' != req.url) return;
if ('POST' != req.method) {
res.writeHead(400);
res.end('Method unsupported');
return;
}
var signature = req.headers['x-mydb-signature'];
if (!signature) {
res.writeHead(400);
res.end('Missing `X-MyDB-Signature` header');
return;
}
var body = '';
var self = this;
function ondata(data){
body += data;
}
function onend(){
cleanup();
if (signature != sign(body, self.secret)) {
debug('bad signature');
res.writeHead(403);
res.end('Bad signature');
return;
}
var data;
try {
data = JSON.parse(body);
} catch(e){
debug('json parse error');
res.writeHead(400);
res.end('Bad JSON body');
return;
}
self.subscribe(data, function(err){
if (err) {
debug('subscription error %j', err);
res.writeHead(500);
res.end('Subscription error');
return;
}
res.writeHead(200);
res.end();
});
}
function cleanup(){
req.removeListener('data', ondata);
req.removeListener('end', onend);
req.removeListener('error', onerror);
}
function onerror(){
debug('request error');
cleanup();
}
req.setEncoding('utf8');
req.on('end', onend);
req.on('data', ondata);
req.on('error', onerror);
};
/**
* Buffers a subscription.
*
* @param {String} socket id
* @param {Subscription} subscription
* @api private
*/
Server.prototype.buffer = function(sid, sub){
var self = this;
debug('adding subscription to pending cache for "%s"', sid);
this.pending[sid] = this.pending[sid] || [];
this.pending[sid].push(sub);
// handle subscription errors while pending
function onerror(err){
debug('subscription "%s" error %s in pending state', sub.id, err.stack);
sub.destroy();
}
sub.on('error', onerror);
// handle destroy callback from either `error` or timeout
function ondestroy(){
debug('removing subscription from pending cache');
var index = self.pending[sid].indexOf(sub);
self.pending[sid].splice(index, 1);
}
sub.on('destroy', ondestroy);
// subscription timeout
var timer = setTimeout(function(){
debug('timeout elapsed for subscription');
if (self.pending[sid]) {
debug('subscription still pending - destroying');
sub.destroy();
} else {
debug('subscription has been claimed - ignoring');
}
}, this.subTimeout);
// cleanup
sub.once('attach', function(){
sub.removeListener('error', onerror);
sub.removeListener('destroy', ondestroy);
clearTimeout(timer);
});
};
/**
* Called upon redis subscriber message.
*
* @api private
*/
Server.prototype.onpub = function(channel, msg){
var obj;
if (!this.subscriptions[channel]) return;
try {
obj = JSON.parse(msg);
} catch(e){
debug('json parse error');
this.emit('error', e);
return;
}
this.emit(channel, obj);
};
/**
* Connection URI parsing utility.
*
* @param {String} uri
* @return {Object} `name: 'localhost', port: 6379`
* @api private
*/
function parse(uri){
var pieces = uri.split(':');
var host = pieces.shift();
var port = pieces.pop();
return { host: host, port: port };
}
/**
* HMac signing helper.
*
* @param {String} data
* @param {String} secret
* @api private
*/
function sign(data, secret){
return crypto
.createHmac('sha1', secret)
.update(data)
.digest('hex');
}