udp server

Node.js

  1. const dgram = require('dgram')
  2. const server = dgram.createSocket('udp4')
  4. server.on('error', err => {
  5.   console.error(err)
  6.   server.close()
  7. })
  9. server.on('message', (msg, rinfo) => {
  10.   const data = msg.toString('utf8').trim()
  11.   console.log(`received: ${data} from ${rinfo.address}:${rinfo.port}`)
  12. })
  14. server.on('listening', () => {
  15.   const address = server.address()
  16.   console.log(`server listening ${address.address}:${address.port}`)
  17. })
  19. server.bind(3000)

Output

  1. $ echo 'hello world' > /dev/udp/0.0.0.0/3000
  3. server listening 0.0.0.0:3000
  4. received: hello world from 127.0.0.1:51452

Go

  1. package main
  3. import (
  4.     "fmt"
  5.     "net"
  6.     "strings"
  7. )
  9. func main() {
  10.     conn, err := net.ListenUDP("udp", &net.UDPAddr{
  11.         Port: 3000,
  12.         IP:   net.ParseIP("0.0.0.0"),
  13.     })
  14.     if err != nil {
  15.         panic(err)
  16.     }
  18.     defer conn.Close()
  19.     fmt.Printf("server listening %s\n", conn.LocalAddr().String())
  21.     for {
  22.         message := make([]byte, 20)
  23.         rlen, remote, err := conn.ReadFromUDP(message[:])
  24.         if err != nil {
  25.             panic(err)
  26.         }
  28.         data := strings.TrimSpace(string(message[:rlen]))
  29.         fmt.Printf("received: %s from %s\n", data, remote)
  30.     }
  31. }

Output

  1. $ echo 'hello world' > /dev/udp/0.0.0.0/3000
  3. server listening [::]:3000
  4. received: hello world from 127.0.0.1:50275