UDP size buffer

udp.go

package main

import (
	"encoding/binary"
	"fmt"
	"net"
	"os"
	"time"
)

/* A Simple function to verify error */
func CheckError(err error) {
	if err != nil {
		fmt.Println("Error: ", err)
		os.Exit(0)
	}
}

func main() {
	ch := make(chan bool)
	go server(ch)
	time.Sleep(1 * time.Second)
	client()
	<-ch
}
func server(ch chan bool) {
	/* Lets prepare a address at any address at port 10001*/
	ServerAddr, err := net.ResolveUDPAddr("udp", ":10001")
	CheckError(err)

	/* Now listen at selected port */
	serverConn, err := net.ListenUDP("udp", ServerAddr)
	CheckError(err)
	defer serverConn.Close()
	// read first the size
	var size int32
	if err := binary.Read(serverConn, binary.LittleEndian, &size); err != nil {
		fmt.Println("err", err)
	}
	buf := make([]byte, size)
	if err := binary.Read(serverConn, binary.LittleEndian, &buf); err != nil {
		fmt.Println("err", err)
	}
	fmt.Printf("buf = %s\n", buf)
	ch <- true
}

func client() {
	ServerAddr, err := net.ResolveUDPAddr("udp", "127.0.0.1:10001")
	CheckError(err)

	LocalAddr, err := net.ResolveUDPAddr("udp", "127.0.0.1:0")
	CheckError(err)

	Conn, err := net.DialUDP("udp", LocalAddr, ServerAddr)
	CheckError(err)

	defer Conn.Close()

	msg := []byte("Hello World!\n")
	var size int32 = int32(len(msg))
	if err := binary.Write(Conn, binary.LittleEndian, size); err != nil {
		fmt.Println("err", err)
	}
	if err := binary.Write(Conn, binary.LittleEndian, msg); err != nil {
		fmt.Println("err", err)
	}
}