Blocket Easter Eggs - Sista uppgiften

udp.js

/**
  Name: Node.js UDP server
	Supported Platforms: Only tested on Linux
	Date: 2013-03-28
	Author: Oskar Hane <oh@oskarhane.com>
	Website: http://oskarhane.com
	Purpose: For Blocket's Easter Egg comptetition. A UDP server which replies all requests 
			with a binary representation of the string "$your_ip.$current_unix_timestamp"
	Usage: 
		1. Install Node.js via Package: https://github.com/joyent/node/wiki/Installing-Node.js-via-package-manager 
						or via Source: http://oodavid.tumblr.com/post/15090798307/how-to-install-node-js-on-linux
		2. Install npm https://npmjs.org. "curl http://npmjs.org/install.sh | sh".
		3. Install Forever to make it a deamon. "npm install forever -g"
		4. Run "forever start udp.js" and connect with a UDP-client on port 2600.
*/

var dgram = require("dgram");
var Buffer = require('buffer').Buffer;
var server = dgram.createSocket("udp4");

server.on("message", function (msg, rinfo) {
	var time = Math.round(new Date().getTime() / 1000);
	var bin = ascii2bin(rinfo.address + time);
	
	var buf = new Buffer(bin + '\n');
	server.send(buf, 0, buf.length, rinfo.port, rinfo.address);
});

server.bind(2600);

//Convert to binary representation
//Not the most "correct" way, but it works
function ascii2bin(str, index){
	index = index || 0;
	
	if(index > str.length-1)
		return '';
		
	return ('00000000' + str.charCodeAt(index).toString(2)).slice(-8) + ' ' + ascii2bin(str, index+1);
}