msg.Namelen = uint32(SizeofSockaddrAny)
	var iov Iovec
	if len(p) > 0 {
		iov.Base = &p[0]
		iov.SetLen(len(p))
	}
	var dummy byte
	if len(oob) > 0 {
		var sockType int
		sockType, err = GetsockoptInt(fd, SOL_SOCKET, SO_TYPE)
		if err != nil {
			return
		}
		// receive at least one normal byte
		if sockType != SOCK_DGRAM && len(p) == 0 {
			iov.Base = &dummy
			iov.SetLen(1)
		}

	var rsa RawSockaddrAny
	var len _Socklen = SizeofSockaddrAny
	if err = getpeername(fd, &rsa, &len); err != nil {
		return
	}
	return anyToSockaddr(&rsa)
}

func GetsockoptInt(fd, level, opt int) (value int, err error) {
	var n int32
	vallen := _Socklen(4)
	err = getsockopt(fd, level, opt, unsafe.Pointer(&n), &vallen)
	return int(n), err
}

}

func GetsockoptByte(fd, level, opt int) (value byte, err error) {
	var n byte
	vallen := _Socklen(1)
	err = getsockopt(fd, level, opt, unsafe.Pointer(&n), &vallen)
	return n, err
}

func GetsockoptInt(fd, level, opt int) (value int, err error) {
	var n int32
	vallen := _Socklen(4)
	err = getsockopt(fd, level, opt, unsafe.Pointer(&n), &vallen)
	return int(n), err
}

	var iov Iovec
	if len(p) > 0 {
		iov.Base = &p[0]
		iov.SetLen(len(p))
	}
	var dummy byte
	if len(oob) > 0 {
		if len(p) == 0 {
			var sockType int
			sockType, err = GetsockoptInt(fd, SOL_SOCKET, SO_TYPE)
			if err != nil {
				return
			}
			// receive at least one normal byte
			if sockType != SOCK_DGRAM {
				iov.Base = &dummy
				iov.SetLen(1)
			}
		}