go and udp

client.go

package main

import (
	"log"
	"net"
)

func main() {
	log.Println("Start")
	addr, _ := net.ResolveUDPAddr("udp4", "localhost:8080")
	// по внешнему ip не работает
	// addr, _ := net.ResolveUDPAddr("udp4", "23.32.11.22:8080")
	con, err := net.DialUDP("udp4", nil, addr)
	if err != nil {
		log.Println("Dial: ", err)
	}
	buff := []byte("test packet")
	_, err = con.Write(buff)
	if err != nil {
		log.Println("Write: ", err)
	}
	log.Println("End")
}

server.go

package main

import (
	"log"
	"net"
)

func main() {
	addr, _ := net.ResolveUDPAddr("udp4", ":8080")
	sock, _ := net.ListenUDP("udp4", addr)

	for {
		buff := make([]byte, 1024)
		log.Println("Waiting...")
		rlen, _, err := sock.ReadFromUDP(buff)

		if err != nil {
			log.Println("ReadFromUdp: ", err)
		}

		log.Println("Receive: ", string(buff[0:rlen]))
	}
}