Node.js socket.setMulticastTTL()用法及代碼示例

socket.setMulticastTTL()是dgram模塊中Socket類的內置應用程序編程接口，用於設置或清除IP_MULTICAST_TTL套接字選項，該選項有助於指定允許數據包通過指定的多播流量傳輸的IP跳數。

用法:

const socket.setMulticastTTL( ttl )

參數：此方法采用整數值，該整數值表示允許數據包通過指定的多播流量傳輸的IP跳數。

返回值：此方法不返回任何值。

範例1： 文件名：index.js

// Node.js program to demonstrate the 
// server.setMulticastTTL()  API 
  
// 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; 
  
// Handling 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_TTL socket option  
  // and specifiing the number of IP hopes 
  // by using the setMulticastTTL() method 
  server.setMulticastTTL(144); 
}); 
  
// Client sending message to server 
client.send("Hello", 0, 7, 
    broadcast_address, "localhost");

輸出：

UDP String:Hello

範例2： 文件名：index.js

// Node.js program to demonstrate the 
// server.setMulticastTTL()  API 
  
// Importing dgram module 
var dgram = require('dgram'); 
  
// Creating and initializing client 
// and server socket 
var client = dgram.createSocket("udp4"); 
var server = dgram.createSocket("udp4"); 
  
// Handling the message event 
server.on("message", function (msg) { 
  
  // Displaying the client message 
  process.stdout.write("UDP String:"
                       + msg + "\n"); 
  
  // Exiting process 
  process.exit(); 
  
}); 
  
// Handling 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_TTL socket option  
   // and specifiing the number of IP hopes 
   // by using the setMulticastTTL() method 
   server.setMulticastTTL(255); 
}); 
  
// Client sending message to server 
client.send("Hello", 0, 7,  
    1234, "localhost");

使用以下命令運行index.js文件：

node index.js

輸出：

server listening 0.0.0.0:1234
UDP String:Hello

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

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注：本文由純淨天空篩選整理自RohitPrasad3大神的英文原創作品 Node.js socket.setMulticastTTL() Method。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。