node.js - Http Server for ip lookup from domain

lookup-server.js

var http = require("http");
var dns = require("dns");
var u = require("util");

var urls = { length: 0 }

http.createServer(function(req,res) {
    res.writeHead(200, {'Content-Type': 'text/plain'});
    var url = req.url.replace(/^\/(https?:\/\/)?/i,"");
    url = url.split("/")[0];

    var writeIp = function(wurl, wip) {
        res.write(String(wurl) + ": " + String(wip) + "\n");
    };

    var finished = function() {
        if(urls[url] == "undefined") {
            res.write("Die IP von '" + url + "' konnte nicht gefunden werden.\n");
        } else {
            res.write("Die IP von '" + url + "' ist " + String(urls[url]) + "\n");
        }
        if(url != "favicon.ico")
            console.log("Die IP von '" + url + "' wurde nachgeschaut. Die IP ist " + urls[url]);
        if(urls.length > 1 || ( urls.length > 0 && urls[url] == "undefined" )  ) {
            res.write("\n\n\nWeiter IP Adressen:\n\n");
        };

        for( var key in urls ) {
            if( key != "undefined" && key != url && key != "length" && urls[key] != "undefined") {
                writeIp(key, urls[key]);
            };
        };
        res.end("");
    };

    var cb = function(err, adress, family) {
        if(url != "favicon.ico") {
            if( urls[url] == undefined && String(adress) != "undefined") {
                urls.length += 1;
            };
            urls[url] = String(adress);
        };
        finished();
    };

    dns.lookup(url, cb);

}).listen(3000);

http://localhost:3000/localhost
=> Die IP von 'localhost' ist 127.0.0.1

http://localhost:3000/google.de
=>
Die IP von 'google.de' ist 209.85.148.106
Weiter IP Adressen:
localhost: 127.0.0.1