Node.js socket.setMulticastLoopback() 方法

socket.setMulticastLoopback()方法是 dgram 模块中 Socket 类的内置应用程序编程接口，用于设置或清除IP_MULTICAST_LOOP套接字选项，帮助服务器在本地接口接收多播数据包。

句法：

const socket.setBroadcast( flag )

参数：此方法将布尔值作为参数，true 用于启用IP_MULTICAST_LOOP套接字选项，false 用于禁用它。

返回值：此方法不返回任何值。

示例 1：文件名：index.js

Javascript

// Node.js program to demonstrate the
// socket.setMulticastLoopback() method
 
// Importing dgram module
var dgram = require('dgram');
 
// Creating and initializing client
// and server socket
var client = dgram.createSocket("udp4");
var server = dgram.createSocket("udp4");
let broadcast_address = 12345;
 
// Catching the message event
server.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 server
client.send("Hello", 0, 7,
    broadcast_address, "localhost");

输出：

UDP String: Hello

示例 2：文件名：index.js

Javascript

// Node.js program to demonstrate the
// socket.setMulticastLoopback() method
 
// Importing dgram module
var dgram = require('dgram');
 
// Creating and initializing client
// and server socket
var client = dgram.createSocket("udp4");
var server = dgram.createSocket("udp4");
 
// Catching the message event
server.on("message", function (msg) {
 
    // Displaying the client message
    process.stdout.write("UDP String: " + msg + "\n");
 
    // Exiting process
    process.exit();
});
 
// Catching the listening event
server.on('listening', () => {
    const address = server.address();
    console.log(`server listening
        ${address.address}:${address.port}`);
});
 
// Binding server with port address
server.bind(1234, () => {
 
    // Enable the IP_MULTICAST_LOOP socket option
    // by using the setMulticastLoopback() method
    server.setMulticastLoopback(true);
});
 
// Client sending message to server
client.send("Hello", 0, 7, 1234, "localhost");

输出：

server listening 0.0.0.0:1234
UDP String: Hello

使用以下命令运行 index.js 文件：

node index.js

参考： https://nodejs.org/dist/latest-v12.x/docs/api/dgram.html#dgram_socket_setmulticastloopback_flag