從Node.js連接到UDP服務器

Question

我已經用C語言編寫了一個UDP服務器，並且嘗試使用以下客戶端代碼從nodejs連接到它：

const dgram = require('dgram');
const server = dgram.createSocket('udp4');

server.on('error', (err) => {
  console.log(`server error:\n${err.stack}`);
  server.close();
});

server.on('message', (msg, rinfo) => {
  console.log(`server got: ${msg} from ${rinfo.address}:${rinfo.port}`);
});

server.on('listening', () => {
  const address = server.address();
  console.log(`server listening ${address.address}:${address.port}`);
});

server.bind(3000);

服務器也在端口3000上運行，執行nodejs代碼時出現此錯誤：

client error:
Error: bind EADDRINUSE 0.0.0.0:3000
    at state.handle.lookup (dgram.js:242:18)
    at process._tickCallback (internal/process/next_tick.js:63:19)
    at Function.Module.runMain (internal/modules/cjs/loader.js:745:11)
    at startup (internal/bootstrap/node.js:283:19)
    at bootstrapNodeJSCore (internal/bootstrap/node.js:743:3

為什么會這樣呢？

謝謝

Answer 1

也許您可以嘗試以下代碼，這將創建一個UDP客戶端並將一條消息發送到您的服務器，我假設它位於localhost，端口3000上。

它還將打印任何響應：

client.js：

const dgram = require("dgram");
const PORT = 3000;
const HOST = '127.0.0.1';

const message = Buffer.from("Hey there!!", "utf8");

const client = dgram.createSocket('udp4');

client.on("message", function (message, remote) {
    console.log(`UDP message received from: ${remote.address}:${remote.port} - ${message}`);
});

client.send(message, 0, message.length, PORT, HOST, function(err, bytes) {
    if (err) {
        console.error(`UDP message send error:`, err);
    } else {
        console.log(`UDP message sent to ${HOST}:${PORT}`);
    }
});

如果願意，也可以嘗試使用Node.js服務器進行測試，這是來自Node.js文檔的一些經過修改的代碼：

server.js：

const dgram = require('dgram');
const server = dgram.createSocket('udp4');

server.on('error', (err) => {
    console.log(`server error:`, err);
    server.close();
});

server.on('message', (msg, rinfo) => {
    console.log(`server got: ${msg} from ${rinfo.address}:${rinfo.port}`);
    // Echo message back to client
    server.send("I got a message from you: " + msg, rinfo.port);
});

server.on('listening', () => {
    const address = server.address();
    console.log(`server listening ${address.address}:${address.port}`);
});

server.bind(3000);