MAC address to IPv6 link-local address

mac2ip.go

package main

import (
	"fmt"
	"log"
	"net"
)

func mac2ip(s string) (net.IP, error) {
	mac, err := net.ParseMAC(s)
	if err != nil {
		return nil, err
	}

	// Invert the bit at the index 6 (counting from 0)
	mac[0] ^= (1 << (2 - 1))

	ip := []byte{
		0xfe, 0x80, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, // prepend with fe80::
		mac[0], mac[1], mac[2], 0xff, 0xfe, mac[3], mac[4], mac[5], // insert ff:fe in the middle
	}

	return ip, nil
}

func main() {
	ip, err := mac2ip("02:42:18:35:e7:5a")
	if err != nil {
		log.Fatalln(err)
	}

	fmt.Println(ip) // prints fe80::42:18ff:fe35:e75a
}