Basic UDP Server and Client

client.go

package main

import (
	"flag"
	"log"
	"net"
	"time"
)

var serverAddress *string = flag.String("s", "127.0.0.1:9000", "server address")

func main() {

	buf := make([]byte, 0xffff)

	flag.Parse()

	// Convert address to udp address type
	addr, err := net.ResolveUDPAddr("udp", *serverAddress)
	if err != nil {
		log.Fatal(err)
	}

	// No set local address. Leverage the operating system to set one for us
	conn, err := net.DialUDP("udp", nil, addr)
	if err != nil {
		log.Fatal(err)
	}

	// Send a message with the specified payload
	buf = []byte("hello")
	n, err := conn.Write(buf)
	if err != nil {
		log.Fatal(err)
	}

	log.Println("SEND:", string(buf[:n]))

	// Wait for response packet and set a timeout of a second if not packet is received
	conn.SetReadDeadline(time.Now().Add(time.Second * 1))
	n, err = conn.Read(buf)
	if err != nil {
		log.Fatal(err)
	}

	log.Println("RECV:", string(buf[:n]))
}

server.go

package main

import (
	"flag"
	"log"
	"net"
)

var serverAddress *string = flag.String("s", "127.0.0.1:9000", "server address")

func main() {

	buf := make([]byte, 0xffff)

	flag.Parse()

	// Convert address to udp address type
	addr, err := net.ResolveUDPAddr("udp", *serverAddress)
	if err != nil {
		log.Fatal(err)
	}

	// Create socket, bind to addr and start listening
	conn, err := net.ListenUDP("udp", addr)
	if err != nil {
		log.Fatal(err)
	}

	log.Println("Listening on", addr)

	for {
		// Waiting for new packet
		n, addr, err := conn.ReadFromUDP(buf)
		if err != nil {
			log.Println(err)
			continue
		}
		log.Printf("RECV: %s from %s\n", buf[:n], addr.String())

		// Echo packet to client
		n, err = conn.WriteToUDP(buf[:n], addr)
		if err != nil {
			log.Println(err)
			continue
		}
		log.Printf("SEND: %s to   %s\n", buf[:n], addr.String())
	}
}