longpope.js

var http = require('http'),
    httpProxy = require('http-proxy'),
    url = require('url');

var doproxy = false; //use true if we want to place this in front of another server
                     //could be worth it if we're sitting in front of apache instead of an evented server?
var lport = 4881;
var rport = 81;
var rhost = '127.0.0.1';
var targetuid = 'www-data';
var targetgid = targetuid;
var waiters = {};

function doCleanup()
{
    for(var channel in waiters)
    {
        waiters[channel] = waiters[channel].filter(function(rq) { return !rq.dead; });
    }
}

function doTrigger(channel) {
    if(waiters[channel])
    {
        waiters[channel].forEach(function(rq) {
                if(!rq.dead) {
                    console.log("Finishing wait for " + channel);
                    rq.response.writeHead(303,
                        {'Location': 'http://' + rq.request.headers['host'] + rq.dest});
                    rq.response.end();
                    rq.dead = true;
                }
            });
    }
    doCleanup();
}

var server = http.createServer(function(req, resp) {
    if(req.url.substring(0,6) == "/poll/")
    {
        //It's a longpoll rq, probably.
        var rqurl = url.parse(req.url, true);
        var timeout = 60; //Default timeout 1min.
        var errorout = false;
        var destination = false;
        var channel = rqurl.pathname.substring(6);
        if(rqurl.query['timeout'])
            timeout = rqurl.query['timeout'];
        if(rqurl.query['dest'])
            destination = rqurl.query['dest'];
        if(rqurl.query['errorout'])
            errorout = true;
        var rqrecord = {
            request: req,
            response: resp,
            dead: false,
            error: errorout,
            dest: destination};
        if(!waiters[channel]) waiters[channel] = [];
        console.log("Adding waiter for " + channel);
        waiters[channel].push(rqrecord);
        setTimeout(function() {
            console.log("Wait for " + channel + " timed out");
            rqrecord.dead = true;
            if(rqrecord.response.connection) {
                if(rqrecord.error) {
                rqrecord.response.writeHead(504);
                rqrecord.response.end();
                } else {
                    rqrecord.response.writeHead(303,
                         {'Location': 'http://' + rqrecord.request.headers['host'] + rqrecord.dest});
                    rqrecord.response.end();
                    rqrecord.dead = true;
                }
            }
            doCleanup();
        }, timeout * 1000);
        return;
    }
    if(req.url.substring(0,6) == "/trig/" && req.connection.remoteAddress == '127.0.0.1')
    {
        var rqurl = url.parse(req.url, true);
        var channel = rqurl.pathname.substring(6);
        var after = 0;
        if(rqurl.query['after'])
            after = 1000 * rqurl.query['after'];
        setTimeout(function() { doTrigger(channel); }, after);
        resp.writeHead(400, {'Content-Type': 'application/json'});
        resp.end('{"ok": true}');
        return;
    }
    if(doproxy) {
        var proxy = new httpProxy.HttpProxy(req, resp);
        proxy.proxyRequest(rport, rhost, req, resp);
    }
});
console.log("Listening...");
server.listen(lport);

if(process.getuid() == 0) { // oh hell, we're root. DROP PRIVS!
    process.setgid(targetgid);
    process.setuid(targetuid);
    console.log("dropped privs");
}