DelayNoMore/udp_server_prac/main.go

package main

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

func main() {
	conn, err := net.ListenUDP("udp", &net.UDPAddr{
		Port: 3000,
		IP:   net.ParseIP("127.0.0.1"),
	})
	if err != nil {
		panic(err)
	}

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

	for {
		message := make([]byte, 2046)
		rlen, remote, err := conn.ReadFromUDP(message[:])
		if err != nil {
			panic(err)
		}

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

		// echo
		rlen, wrerr := conn.WriteTo(message[0:rlen], remote)
		if wrerr != nil {
			fmt.Printf("net.WriteTo() error: %s\n", wrerr)
		} else {
			fmt.Printf("Wrote %d bytes to socket\n", rlen)
		}
	}
}