package main

import (
	"fmt"
	"net"
	"os"
)

func sendResponse(conn *net.UDPConn, addr *net.UDPAddr){
	_,err := conn.WriteToUDP([]byte("Hello from Server. Message received. "), addr)
	if err != nil {
		fmt.Printf("Couldn't send response %v", err)
	}

}

func main(){

	/* Create the server.  */
	ServerAddr, err := net.ResolveUDPAddr("udp", "0.0.0.0:11000")
	if(err != nil){
		fmt.Println("Error ", err)
		os.Exit(0)
	}

	/* Equivalent to listen */
	ServerConn, err := net.ListenUDP("udp", ServerAddr)
	if(err != nil){
		fmt.Println("Error ", err)
		os.Exit(0)
	}

	/* Defer is executed when the surrounding function returns. */
	defer ServerConn.Close()

	buf := make([]byte, 1024)

	for {
		/* Equivalent to accept */
		n, addr, err := ServerConn.ReadFromUDP(buf)
		fmt.Println("Received from ", addr," value: ", string(buf[0:n]))
		if(err != nil){
			fmt.Println("Error ", err)
			os.Exit(0)
		}

		go sendResponse(ServerConn, addr)

	}

}