package soundbox

import (
	"fmt"
	"net"
)

// toLinkLocal converts a MAC address to the corresponding IPv6 link-local
// address.
func toLinkLocal(ha net.HardwareAddr) (net.IP, error) {
	switch len(ha) {
	case 6:
		ip := net.IP{0xfe, 0x80, 0, 0, 0, 0, 0, 0,
			ha[0] ^ 0b10, ha[1], ha[2], 0xff, 0xfe, ha[3], ha[4], ha[5]}
		return ip, nil
	default:
		return nil, fmt.Errorf("Only IEEE 802 MAC-48 addresses supported")
	}
}