// care".
	nlen, alen, slen := int(b[1]), int(b[2]), int(b[3])
	if nlen == 0xff {
		nlen = 0
	}
	if alen == 0xff {
		alen = 0
	}
	if slen == 0xff {
		slen = 0
	}
	l := 4 + nlen + alen + slen
	if len(b) < l {
		return 0, nil, errInvalidAddr
	}
	data := b[4:]
	var name string
	var addr []byte
	if nlen > 0 {
		name = string(data[:nlen])

	return as, nil
}

func parseLinkAddr(b []byte) ([]byte, error) {
	nlen, alen, slen := int(b[1]), int(b[2]), int(b[3])
	l := 4 + nlen + alen + slen
	if len(b) < l {
		return nil, errors.New("invalid address")
	}
	b = b[4:]
	var addr []byte
	if nlen > 0 {
		b = b[nlen:]
	}
	if alen > 0 {
		addr = make([]byte, alen)
		copy(addr, b[:alen])
	}
	return addr, nil

				ifi := &Interface{Index: int(ifm.Index), Flags: linkFlags(ifm.Flags)}
				ifi.Name = string(sdl.Data[:sdl.Nlen])
				ifi.HardwareAddr = sdl.Data[sdl.Nlen : sdl.Nlen+sdl.Alen]

				// Retrieve MTU
				ifr := &ifreq{}
				copy(ifr.Name[:], ifi.Name)
				err = unix.Ioctl(sock, syscall.SIOCGIFMTU, unsafe.Pointer(ifr))
				if err != nil {
					return nil, err
				}

	type linkLayerAddr struct {
		Type byte
		Nlen byte
		Alen byte
		Slen byte
	}
	lla := (*linkLayerAddr)(unsafe.Pointer(&b[0]))
	l := 4 + int(lla.Nlen) + int(lla.Alen) + int(lla.Slen)
	if len(b) < l {
		return nil, 0, EINVAL
	}
	b = b[4:]
	sa := &SockaddrDatalink{Type: lla.Type, Nlen: lla.Nlen, Alen: lla.Alen, Slen: lla.Slen}
	for i := 0; len(sa.Data) > i && i < l-4; i++ {
		sa.Data[i] = int8(b[i])
	}

	sa.raw.Type = sa.Type
	sa.raw.Nlen = sa.Nlen
	sa.raw.Alen = sa.Alen
	sa.raw.Slen = sa.Slen
	sa.raw.Data = sa.Data
	return unsafe.Pointer(&sa.raw), SizeofSockaddrDatalink, nil
}

func anyToSockaddr(rsa *RawSockaddrAny) (Sockaddr, error) {
	switch rsa.Addr.Family {
	case AF_LINK:
		pp := (*RawSockaddrDatalink)(unsafe.Pointer(rsa))
		sa := new(SockaddrDatalink)
		sa.Len = pp.Len
		sa.Family = pp.Family

	sa.raw.Type = sa.Type
	sa.raw.Nlen = sa.Nlen
	sa.raw.Alen = sa.Alen
	sa.raw.Slen = sa.Slen
	sa.raw.Data = sa.Data
	return unsafe.Pointer(&sa.raw), SizeofSockaddrDatalink, nil
}

func anyToSockaddr(fd int, rsa *RawSockaddrAny) (Sockaddr, error) {
	switch rsa.Addr.Family {
	case AF_LINK:
		pp := (*RawSockaddrDatalink)(unsafe.Pointer(rsa))
		sa := new(SockaddrDatalink)
		sa.Len = pp.Len
		sa.Family = pp.Family

	length := len(name)
	if length <= nameSize || !isASCII(name) {
		return "", "", false
	} else if length > prefixSize+1 {
		length = prefixSize + 1
	} else if name[length-1] == '/' {
		length--
	}

	i := strings.LastIndex(name[:length], "/")
	nlen := len(name) - i - 1 // nlen is length of suffix
	plen := i                 // plen is length of prefix

	Len    uint8
	Family uint8
	Index  uint16
	Type   uint8
	Nlen   uint8
	Alen   uint8
	Slen   uint8
	Data   [120]uint8
}

type RawSockaddr struct {
	Len    uint8
	Family uint8
	Data   [14]uint8
}

type RawSockaddrAny struct {
	Addr RawSockaddr
	Pad  [1012]uint8
}

type _Socklen uint32

type Cmsghdr struct {
	Len   uint32
	Level int32

	Len    uint8
	Family uint8
	Index  uint16
	Type   uint8
	Nlen   uint8
	Alen   uint8
	Slen   uint8
	Data   [120]uint8
}

type RawSockaddr struct {
	Len    uint8
	Family uint8
	Data   [14]uint8
}

type RawSockaddrAny struct {
	Addr RawSockaddr
	Pad  [1012]uint8
}

type _Socklen uint32

type Cmsghdr struct {
	Len   uint32
	Level int32

type RawSockaddrDatalink struct {
	Len    uint8
	Family uint8
	Index  uint16
	Type   uint8
	Nlen   uint8
	Alen   uint8
	Slen   uint8
	Data   [12]int8
}

type RawSockaddr struct {
	Len    uint8
	Family uint8
	Data   [14]int8
}

type RawSockaddrAny struct {
	Addr RawSockaddr
	Pad  [92]int8
}

type _Socklen uint32

type Linger struct {
	Onoff  int32
	Linger int32
}