Multicast-Manager

example.js

var net_manager = require('./net_manager');

net_manager.withSocket(function (api) {
   return api.broadcast('This is a test')
       .then(api.unbind);
});

net_manager.js

var promise = require('bluebird');
var dgram = require('dgram');

function getSocket(port, multicastAddress) {
    return new promise(function (resolve, reject) {
        try {
            var socket = dgram.createSocket({type: 'udp4', reuseAddr: true});

            socket._port = port;

            socket.once('listening', function () {
                socket._multicastAddress = multicastAddress || '224.0.2.1';

                socket.setBroadcast(true);
                socket.setMulticastLoopback(true);
                socket.setMulticastTTL(1);
                socket.addMembership(socket._multicastAddress);

                resolve(socket);
            });

            socket.bind(socket._port);
        } catch (ex) {
            reject(ex);
        }
    }).disposer(function (socket, promise) {
        if (socket._handle) {
            socket.close();
        }
    });
}

exports.withSocket = function bind(port, multicastAddress, callback) {
    var p = typeof port === 'number' ? port : 61088;
    var cb = typeof port === 'function' ? port : callback;

    return promise.using(getSocket(p, multicastAddress), function (socket) {
        var api = {
            broadcast: broadcast.bind(socket),
            /*
            ... other high-level protocol functions here
            */
            unbind: unbind.bind(socket)
        };

        return promise.try(cb, api);
    });
};

function broadcast(message) {
    var socket = this;
    var messageBuffer = new Buffer(message);

    return promise.fromCallback(function (callback) {
        socket.send(messageBuffer, 0, messageBuffer.length, socket._port, socket._multicastAddress, callback);
    });
}

function unbind() {
    var socket = this;

    return promise.fromCallback(function (callback) {
        socket.close(callback);
    });
}