NodeJS UDP Multicast How to

Question

I'm trying to send a UDP Multicast Packet to: 230.185.192.108 so everyone subscribed will receive. A bit stuck. I believe it's broadcasting correctly, but can't seem to pick anything up with any client.

Server:

var news = [
   "Borussia Dortmund wins German championship",
   "Tornado warning for the Bay Area",
   "More rain for the weekend",
   "Android tablets take over the world",
   "iPad2 sold out",
   "Nation's rappers down to last two samples"
];

var dgram = require('dgram'); 
var server = dgram.createSocket("udp4"); 
server.bind();
server.setBroadcast(true)
server.setMulticastTTL(128);
server.addMembership('230.185.192.108'); 

setInterval(broadcastNew, 3000);

function broadcastNew() {
    var message = new Buffer(news[Math.floor(Math.random()*news.length)]);
    server.send(message, 0, message.length, 8088, "230.185.192.108");
    console.log("Sent " + message + " to the wire...");
    //server.close();
}

Client

var PORT = 8088;
var HOST = '192.168.0.102';
var dgram = require('dgram');
var client = dgram.createSocket('udp4');

client.on('listening', function () {
    var address = client.address();
    console.log('UDP Client listening on ' + address.address + ":" + address.port);
    client.setBroadcast(true)
    client.setMulticastTTL(128); 
    client.addMembership('230.185.192.108');
});

client.on('message', function (message, remote) {   
    console.log('A: Epic Command Received. Preparing Relay.');
    console.log('B: From: ' + remote.address + ':' + remote.port +' - ' + message);
});

client.bind(PORT, HOST);

References More info on NodeJS Datagram

• http://nodejs.org/api/dgram.html

Answer 1

Changed:

client.addMembership('230.185.192.108');

to

client.addMembership('230.185.192.108',HOST); //Local IP Address

Answer 2

This answer is old, but shows up high on Google's search results. With Node v4.4.3, the server example fails with error EBADF. The complete working block of code is listed below:

Server:

//Multicast Server sending messages
var news = [
   "Borussia Dortmund wins German championship",
   "Tornado warning for the Bay Area",
   "More rain for the weekend",
   "Android tablets take over the world",
   "iPad2 sold out",
   "Nation's rappers down to last two samples"
];

var PORT = 41848;
var MCAST_ADDR = "230.185.192.108"; //not your IP and should be a Class D address, see http://www.iana.org/assignments/multicast-addresses/multicast-addresses.xhtml
var dgram = require('dgram'); 
var server = dgram.createSocket("udp4"); 
server.bind(PORT, function(){
    server.setBroadcast(true);
    server.setMulticastTTL(128);
    server.addMembership(MCAST_ADDR);
});

setInterval(broadcastNew, 3000);

function broadcastNew() {
    var message = new Buffer(news[Math.floor(Math.random()*news.length)]);
    server.send(message, 0, message.length, PORT,MCAST_ADDR);
    console.log("Sent " + message + " to the wire...");
}

Client:

//Multicast Client receiving sent messages
var PORT = 41848;
var MCAST_ADDR = "230.185.192.108"; //same mcast address as Server
var HOST = '192.168.1.9'; //this is your own IP
var dgram = require('dgram');
var client = dgram.createSocket('udp4');

client.on('listening', function () {
    var address = client.address();
    console.log('UDP Client listening on ' + address.address + ":" + address.port);
    client.setBroadcast(true)
    client.setMulticastTTL(128); 
    client.addMembership(MCAST_ADDR);
});

client.on('message', function (message, remote) {   
    console.log('MCast Msg: From: ' + remote.address + ':' + remote.port +' - ' + message);
});

client.bind(PORT, HOST);

For the novices like me, client.bind(PORT,HOST); is the important bit. I couldn't get the client to receive anything when bound to HOST=127.0.0.1, but worked when the IP address was used. Again, HOST if excluded, the example won't work when testing using a single machine (client will throw EADDRINUSE error)

Answer 3

The solution provided here was not working for me, while this gist worked right out of the box: https://gist.github.com/ciaranj/9056285

I copied that here for convenience, all credits should go to @ciaranj.

client.js:

var PORT = 5007;
var dgram = require('dgram');
var client = dgram.createSocket({ type: 'udp4', reuseAddr: true })

client.on('listening', function () {
    var address = client.address();
    console.log('UDP Client listening on ' + address.address + ":" + address.port);
    client.setBroadcast(true)
    client.setMulticastTTL(128);
    client.addMembership('224.1.1.1');
});

client.on('message', function (message, remote) {
    console.log('A: Epic Command Received. Preparing Relay.');
    console.log('B: From: ' + remote.address + ':' + remote.port + ' - ' + message);
});

client.bind(PORT);

server.js:

var news = [
    "Borussia Dortmund wins German championship",
    "Tornado warning for the Bay Area",
    "More rain for the weekend",
    "Android tablets take over the world",
    "iPad2 sold out",
    "Nation's rappers down to last two samples"
];

var dgram = require('dgram');
var server = dgram.createSocket("udp4");
server.bind(function () {
    server.setBroadcast(true)
    server.setMulticastTTL(128);
    setInterval(broadcastNew, 3000);
});

function broadcastNew() {
    var message = new Buffer.from(news[Math.floor(Math.random() * news.length)]);
    server.send(message, 0, message.length, 5007, "224.1.1.1");
    console.log("Sent " + message + " to the wire...");
}