udp server

udp server

Node.js

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

server.on('error', err => {
  console.error(err)
  server.close()
})

server.on('message', (msg, rinfo) => {
  const data = msg.toString('utf8').trim()
  console.log(`received: ${data} from ${rinfo.address}:${rinfo.port}`)
})

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

server.bind(3000)

Output

$ echo 'hello world' > /dev/udp/0.0.0.0/3000

server listening 0.0.0.0:3000
received: hello world from 127.0.0.1:51452

Go

package main

import (
    "fmt"
    "net"
    "strings"
)

func main() {
    conn, err := net.ListenUDP("udp", &net.UDPAddr{
        Port: 3000,
        IP:   net.ParseIP("0.0.0.0"),
    })
    if err != nil {
        panic(err)
    }

    defer conn.Close()
    fmt.Printf("server listening %s\n", conn.LocalAddr().String())

    for {
        message := make([]byte, 20)
        rlen, remote, err := conn.ReadFromUDP(message[:])
        if err != nil {
            panic(err)
        }

        data := strings.TrimSpace(string(message[:rlen]))
        fmt.Printf("received: %s from %s\n", data, remote)
    }
}

Output

$ echo 'hello world' > /dev/udp/0.0.0.0/3000

server listening [::]:3000
received: hello world from 127.0.0.1:50275