I've got quite silly questions, i'm trying to make redirection service using node.js based on conditions pulled from mongodb... so code lookis like that:

var http = require('http'),
util = require('util'),
url = require('url');

var server = http.createServer(function(req, res) {
    domain = req.headers['host'];
    var url = getRedirect(domain);

    res.writeHead(301, { 'Location': url});
    res.end();
});

server.listen(8080);

var getRedirect = function(domain) {

    Domain.findOne({ 'name': domain }, 'url', function (err, domain) {
        if (err) return handleError(err);
        console.log('redirect url %s.', domain.url) 
        return domain.url
    })
}

Of course - doesn't work as it should be, because Domain.findOne is finding results with delay, and return doesn't assign resuluts to url... I tried to pass "res" object into getRedirect function but i'm pretty sure that it's wrong.

Any clues?

You'll need to use a callback for this, since (as you've pointed out), the domain/url fetching is asynchronous. The node convention is to use an "error first callback" signature.

Try this:

var http = require('http'),
    util = require('util'),
    url = require('url');

var server = http.createServer(function(req, res) {
    var domain = req.headers['host'];
    // provide a callback to getRedirect so we can get the value asynchronously
    getRedirect(domain, function(err, url) {
        if (err) return handleError(err);
        res.writeHead(301, { 'Location': url });
        res.end();
    });
});

server.listen(8080);

var getRedirect = function(domain, cb) {
    Domain.findOne({ 'name': domain }, 'url', function (err, domain) {
        if (err) return cb(err);
        console.log('redirect url %s.', domain.url);
        // instead of returning, pass the result to the callback
        cb(null, domain.url);
    });
};