JS listener for local control of an RC Car with a Spark Core

rccar-listener.js

var dgram = require("dgram");
var os = require('os');

var getIPAddresses = function () {
	var nics = os.networkInterfaces();

	var results = [];
	for (var name in nics) {
		if (!nics.hasOwnProperty(name)) { continue; }
		var nic = nics[name];

		for (var i = 0; i < nic.length; i++) {
			var addy = nic[i];
			if ((addy.family == "IPv4")
                           && (addy.address != "127.0.0.1")) {
				results.push(addy.address);
			}
		}
	}
	return results;
};


var server = dgram.createSocket("udp4");
server.on("error", function (err) {
	console.log("server error:\n" + err.stack);
	server.close();
});
server.on("message", function (msg, rinfo) {
	var hex = msg.toString('hex');
	var idx = hex.indexOf('ff');
	var id = hex.substring(idx + 2);

	console.log("a core just announced itself! core id:" + id + " ip address: " + rinfo.address);
});
server.on("listening", function () {
	var address = server.address();
	console.log("server listening " + address.address + ":" + address.port);
});


var ips = getIPAddresses();
if (!ips || (ips.length == 0)) {
	console.error("error getting IP address!");
}
server.bind(5683, '0.0.0.0', function () {
	for(var i=0;i<ips.length;i++) {
		server.addMembership('224.0.1.187', ips[i]);
	}
});