package main

import (
	"fmt"
	"log"
	"net"
	"time"
	"syscall"
)


type mystruct struct {
	myconn *net.UDPConn
}

func bindToInterface(conn net.PacketConn, iface string) {
	file, err := conn.(*net.UDPConn).File()
	if err != nil {
		log.Fatal("Could not bind to interface ", iface)
	}
	fd := file.Fd()
	syscall.BindToDevice(int(fd), iface)
}


func manageUDP(structure *mystruct) {
	buf := make([]byte, 1000)
	udpAddr, _ := net.ResolveUDPAddr("udp", "127.0.0.1:9999")
	udpConn, err := net.DialUDP("udp", nil, udpAddr)
	if err != nil {
		log.Fatal(err.Error())
	}

	structure.myconn = udpConn

	bindToInterface(udpConn, "eth0")

	for {
		n, err := udpConn.Read(buf)
		if err != nil {
			log.Fatal("FATAL->", err.Error())
		} else {
			log.Print("Received some data: ", n)
		}
	}
}

func main() {
	count := 1
	m := &mystruct{}

	go manageUDP(m)

	go func() {
		c := time.Tick(1 * time.Second)
		for now := range c {
			fmt.Printf("%v %d\n", now, count)
			count += 1
		}
	}()

	fmt.Println("Will *normally* timeout after 5 seconds")

	select {
	case <-time.After(5 * time.Second):
		fmt.Println("Trying to time out")
		m.myconn.SetReadDeadline(time.Now().Add(-1 * time.Second))
	}

	select {}

}