Simple NodeJS UDP forwarding server

udp-forward.js

/**
 * Simple NodeJS UDP forwarding server
 *
 * @author dale3h
 *
 * This script was built to run on a Raspberry Pi that is connected to two networks (wired + wireless).
 * By default it listens on port 443, but only serves HTTP (not HTTPS)
 *
 * @usage
 *   http://192.168.1.102:443/send-udp?host=192.168.1.113&port=12345&device=wlan0&command=PACKET_CONTENTS
 *
 * This would be a Raspberry Pi running at 192.168.1.102 (on eth0), forwarding a UDP packet with the
 *   contents "PACKET_CONTENTS" to host 192.168.1.113, port 12345, using the wlan0 interface.
 *
 * @dependency httpdispatcher
 */

var http       = require( 'http' );
var dispatcher = require( 'httpdispatcher' );
var util       = require( 'util' );
var exec       = require( 'child_process' ).exec;

const LISTEN_PORT = 443;
const SEND_TRIES  = 3;

function handleRequest( request, response ) {
	try {
		//console.log( request.url );
		dispatcher.dispatch( request, response );
	} catch( err ) {
		console.log( err );
	}
}

function sendUDP( request, response ) {
	var host     = request.params.host || false;
	var port     = request.params.port || false;
	var device   = request.params.device || false;
	var command  = request.params.command || false;
	var tries    = request.params.tries || SEND_TRIES;

	if ( ! host || ! port || ! command ) {
		response.writeHead( 400, { 'Content-Type': 'text/plain' } );
		response.end( '400 Bad Request' );

		return;
	}

	sendUDPHelper( host, port, device, command, tries );

	response.writeHead( 200, { 'Content-Type': 'text/plain' } );
	response.end( command );
}

function sendUDPHelper( host, port, device, command, tries ) {
	var child;
	var bindto = '';

	if ( device ) {
		bindto = ',so-bindtodevice=' + device;
	}

	var cmd = 'echo \"' + command + '\" | sudo socat - UDP-DATAGRAM:' + host + ':' + port + bindto;

	child = exec( cmd, function( error, stdout, stderr ) {
		var header = '[' + getDateTime() + '] [' + (device ? device + ':' : '' ) + host + ':' + port + '] ';

		if ( error !== null ) {
			console.log( header + 'ERROR: ' + error );
			return;
		}

		console.log( header + command );
	} );

	if ( --tries > 0 ) {
		sendUDPHelper( host, port, device, command, tries );
	}
}

function getDateTime() {
    var date = new Date();

    var hour = date.getHours();
    hour = ( hour < 10 ? "0" : "" ) + hour;

    var min  = date.getMinutes();
    min = ( min < 10 ? "0" : "" ) + min;

    var sec  = date.getSeconds();
    sec = ( sec < 10 ? "0" : "" ) + sec;

    var year = date.getFullYear();

    var month = date.getMonth() + 1;
    month = ( month < 10 ? "0" : "" ) + month;

    var day  = date.getDate();
    day = ( day < 10 ? "0" : "" ) + day;

    return year + "-" + month + "-" + day + " " + hour + ":" + min + ":" + sec;
}

dispatcher.onGet( '/send-udp', sendUDP );
dispatcher.onPost( '/send-udp', sendUDP );

var server = http.createServer( handleRequest );

server.listen( LISTEN_PORT, function() {
	console.log( '[' + getDateTime() + '] Server listening on: http://localhost:%s', LISTEN_PORT );
} );