package main

import (
	"net"
	"fmt"
	"time"
	"crypto/rand"
	"github.com/d2g/dhcp4"
	"github.com/d2g/dhcp4client"
)

func RandomMacAddr() (hw net.HardwareAddr, err error) {
	buf := make([]byte, 6)
    _, err = rand.Read(buf)
    if err != nil {
        panic(err)
    }
    buf[0] |= 2

    return net.ParseMAC(fmt.Sprintf("%02X:%02X:%02X:%02X:%02X:%02X", buf[0], buf[1], buf[2], buf[3], buf[4], buf[5]))
}

func main() {
	m, err := RandomMacAddr()
	if err != nil {
		panic(err)
	}

	conn, err := dhcp4client.NewInetSock()
	if err != nil {
		panic(err)
	}

	defer conn.Close()

	client, err := dhcp4client.New(
		dhcp4client.HardwareAddr(m),
		dhcp4client.Connection(conn),
		dhcp4client.Timeout(time.Second * 30))

	if err != nil {
		panic(err)
	}

	defer client.Close()

	success, packet, err := client.Request()
	if success == true && err == nil {
		options := packet.ParseOptions()
		fmt.Printf("domain name server: %s\n", net.IP(options[dhcp4.OptionDomainNameServer]))
		fmt.Printf("dhcp offer: %v\n\n", options)
	}
}