STUN IP request thing in NodeJS (bad)

STUNgetIP.js

var dgram = require("dgram");
var udp4 = dgram.createSocket("udp4");
var udp6 = dgram.createSocket("udp6");

var stunServer = "stun.l.google.com";
var stunPort = 19302;

function makeSTUNRequest() {
	var buffer = Buffer.alloc(20);
	buffer.writeUInt16BE(0x0001, 0); // STUN request
	buffer.writeUInt16BE(0x0000, 2); // message size (0 bytes)
	buffer.writeUInt32BE(0x2112a442, 4); // magic cookie (always 0x2112a442)
	for (var i = 8; i < 20; i++) {
		var randInt = Math.floor(Math.random() * 255);
		buffer.writeUInt8(randInt, i); // write transaction ID
	}
	return buffer;
}

function parseSTUNResponse(buf, rinfo) {
	if (buf.length < 20) {
		console.log(`Bad response (packet length ${buf.length}}): ${buf.toString('hex')}`);
		return;
	}
	
	// parse the STUN header
	var messageType = buf.readUInt16BE(0);
	var messageSize = buf.readUInt16BE(2);
	var magicCookie = buf.readUInt32BE(4);
	var transID = Buffer.alloc(12);
	for (var i = 8; i < 20; i++) transID[i-8] = buf.readUInt8(i);
	
	// read the STUN message
	if (messageSize <= 0) {
		console.log(`Bad response (no message): ${buf.toString('hex')}`);
		return;
	}
	var message = Buffer.alloc(messageSize);
	for (var i = 0; i < messageSize; i++) message[i] = buf.readUInt8(20+i);
	
	// parse the STUN message
	for (var i = 0; i < messageSize;) {
		// read attribute header
		var attribute = message.readUInt16BE(i + 0);
		var attributeLength = message.readUInt16BE(i + 2);
		i += 4;
		if (attribute == 0x0001) { // MAPPED-ADDRESS
		    var reserved = message.readUInt8(i + 0);
			var addressFamily = message.readUInt8(i + 1);
			if (addressFamily == 1) { // IPv4
				var port = message.readUInt16BE(i + 2);
				var ip1 = message.readUInt8(i + 4);
				var ip2 = message.readUInt8(i + 5);
				var ip3 = message.readUInt8(i + 6);
				var ip4 = message.readUInt8(i + 7);
				console.log(`MAPPED-ADDRESS IPv4: ${ip1}.${ip2}.${ip3}.${ip4}:${port}`);
			} else if (addressFamily == 2) { // IPv6
				var port = message.readUInt16BE(i + 2);
				var ip = "";
				// TODO: there's got to be a cleaner way to do this...
				ip += message.readUInt16BE(i + 4).toString(16) + ":";
				ip += message.readUInt16BE(i + 6).toString(16) + ":";
				ip += message.readUInt16BE(i + 8).toString(16) + ":";
				ip += message.readUInt16BE(i + 10).toString(16) + ":";
				ip += message.readUInt16BE(i + 12).toString(16) + ":";
				ip += message.readUInt16BE(i + 14).toString(16) + ":";
				ip += message.readUInt16BE(i + 16).toString(16) + ":";
				ip += message.readUInt16BE(i + 18).toString(16);
				console.log(`MAPPED-ADDRESS IPv6: [${ip}]:${port}`);
			} else {
				console.log(`Unknown MAPPED-ADDRESS family ${addressFamily}: ${message.slice(i+2, i+attributeLength).toString('hex')}`);
			}
		} else if (attribute == 0x0020) { // XOR-MAPPED-ADDRESS
		    var reserved = message.readUInt8(i + 0);
			var addressFamily = message.readUInt8(i + 1);
			if (addressFamily == 1) { // IPv4
				var port = message.readUInt16BE(i + 2) ^ 0x2112;
				var ip1 = message.readUInt8(i + 4) ^ 0x21;
				var ip2 = message.readUInt8(i + 5) ^ 0x12;
				var ip3 = message.readUInt8(i + 6) ^ 0xa4;
				var ip4 = message.readUInt8(i + 7) ^ 0x42;
				console.log(`XOR-MAPPED-ADDRESS IPv4: ${ip1}.${ip2}.${ip3}.${ip4}:${port}`);
			} else if (addressFamily == 2) { // IPv6
				var port = message.readUInt16BE(i + 2) ^ 0x2112;
				var ip = "";
				// TODO: there's got to be a cleaner way to do this...
				ip += (message.readUInt16BE(i + 4) ^ 0x2112).toString(16) + ":";
				ip += (message.readUInt16BE(i + 6) ^ 0xa442).toString(16) + ":";
				ip += (message.readUInt16BE(i + 8) ^ transID.readUInt16BE(0)).toString(16) + ":";
				ip += (message.readUInt16BE(i + 10) ^ transID.readUInt16BE(2)).toString(16) + ":";
				ip += (message.readUInt16BE(i + 12) ^ transID.readUInt16BE(4)).toString(16) + ":";
				ip += (message.readUInt16BE(i + 14) ^ transID.readUInt16BE(6)).toString(16) + ":";
				ip += (message.readUInt16BE(i + 16) ^ transID.readUInt16BE(8)).toString(16) + ":";
				ip += (message.readUInt16BE(i + 18) ^ transID.readUInt16BE(10)).toString(16);
				console.log(`XOR-MAPPED-ADDRESS IPv6: [${ip}]:${port}`);
			} else {
				console.log(`Unknown XOR-MAPPED-ADDRESS family ${addressFamily}: ${message.slice(i+2, i+attributeLength).toString('hex')}`);
			}
		} else {
			console.log(`Unknown attribute ${attribute.toString(16)} (length ${attributeLength}): ${message.slice(i, i+attributeLength).toString('hex')}`);
		}
		i += attributeLength;
	}
}

udp4.on("message", parseSTUNResponse);
udp6.on("message", parseSTUNResponse);

console.log("Sending STUN request to server...");
udp4.send(makeSTUNRequest(), 0, 20, stunPort, stunServer);
udp6.send(makeSTUNRequest(), 0, 20, stunPort, stunServer);
setTimeout(process.exit, 2000)