Node.js socket.setMulticastLoopback() Method
The socket.setMulticastLoopback() method is an inbuilt application programming interface of class Socket within dgram module which is used to set or clear the IP_MULTICAST_LOOP socket option which helps the server in receiving the multicast packet at the local interface.
Syntax:
const socket.setMulticastLoopback( flag )
Parameters: This method takes the Boolean value as a parameter true for enabling the IP_MULTICAST_LOOP socket option and false for disabling it.
Return Value: This method does not return any value.
Example 1: In this example, we will see the use of the socket.setMulticastLoopback() method
Filename: index.js
Javascript
// Node.js program to demonstrate the// socket.setMulticastLoopback() method// Importing dgram moduleconst dgram = require('dgram');// Creating and initializing client// and server socketlet server = dgram.createSocket("udp4");let client = dgram.createSocket("udp4");let broadcast_address = 12345;// Catching the message eventserver.on("message", function (msg) { // Displaying the client message process.stdout.write("UDP String: " + msg + "\n"); // Exiting process process.exit();}) .bind(broadcast_address, () => { // Enable the IP_MULTICAST_LOOP socket option // by using the setMulticastLoopback() method server.setMulticastLoopback(true); });// Client sending message to serverclient.send("Hello", 0, 7, broadcast_address, "localhost"); |
Output:
UDP String: Hello
Example 2: In this example, we will see the use of the socket.setMulticastLoopback() method
Filename: index.js
Javascript
// Node.js program to demonstrate the// socket.setMulticastLoopback() method// Importing dgram moduleconst dgram = require('dgram');// Creating and initializing client// and server socketlet client = dgram.createSocket("udp4");let server = dgram.createSocket("udp4");// Catching the message eventserver.on("message", function (msg) { // Displaying the client message process.stdout.write("UDP String: " + msg + "\n"); // Exiting process process.exit();});// Catching the listening eventserver.on('listening', () => { const address = server.address(); console.log(`server listening ${address.address}:${address.port}`);});// Binding server with port addressserver.bind(1234, () => { // Enable the IP_MULTICAST_LOOP socket option // by using the setMulticastLoopback() method server.setMulticastLoopback(true);});// Client sending message to serverclient.send("Hello", 0, 7, 1234, "localhost"); |
Output:
server listening 0.0.0.0:1234 UDP String: Hello
Run the index.js file using the following command:
node index.js
Reference: https://nodejs.org/dist/latest-v12.x/docs/api/dgram.html#dgram_socket_setmulticastloopback_flag