golang wol use syscall

wol.go

package main

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

var ifName = flag.String("i", "eth0", "interface to use")
var targetMac = flag.String("t", "00:00:00:00:00:00", "target mac address")

func main() {
	flag.Parse()
	// Open a raw socket
	fd, err := syscall.Socket(syscall.AF_PACKET, syscall.SOCK_RAW, syscall.ETH_P_ALL)
	if err != nil {
		log.Fatal(err)
	}
	defer syscall.Close(fd)

	// Get the MAC address of the network interface
	ifi, err := net.InterfaceByName(*ifName)
	if err != nil {
		log.Fatal(err)
	}
	srcAddr := syscall.SockaddrLinklayer{
		Protocol: syscall.ETH_P_ALL,
		Ifindex:  ifi.Index,
		Halen:    6,
	}
	copy(srcAddr.Addr[:], ifi.HardwareAddr)

	// Create the Ethernet frame
	dstAddr, _ := net.ParseMAC(*targetMac)
	ethFrame := make([]byte, 14)
	copy(ethFrame[0:6], dstAddr)
	copy(ethFrame[6:12], ifi.HardwareAddr)
	ethFrame[12] = 0x08
	ethFrame[13] = 0x42 // Ethernet type WOL

	// create wol payload
	payload := genPayload(dstAddr)

	// Send the Ethernet frame
	err = syscall.Sendto(fd, append(ethFrame, payload...), 0, &srcAddr)
	if err != nil {
		log.Fatal(err)
	}
}

func genPayload(targetMAC net.HardwareAddr) []byte {
	// Create the magic packet payload
	payload := make([]byte, 6+16*6)
	copy(payload[0:6], []byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xff})

	for i := 1; i <= 16; i++ {
		start := i * 6
		end := start + 6
		copy(payload[start:end], targetMAC)
	}
	return payload
}