func nlmAlignOf(msglen int) int {
	return (msglen + NLMSG_ALIGNTO - 1) & ^(NLMSG_ALIGNTO - 1)
}

// Round the length of a netlink route attribute up to align it
// properly.
func rtaAlignOf(attrlen int) int {
	return (attrlen + RTA_ALIGNTO - 1) & ^(RTA_ALIGNTO - 1)
}

// NetlinkRouteRequest represents a request message to receive routing
// and link states from the kernel.
type NetlinkRouteRequest struct {