Function ip6_randomflowlabel

freebsd/netinet6/ip6_id.c:258–274

}

u_int32_t
ip6_randomflowlabel(void)
{
#ifndef FSTACK
	/*
	 * It's ok to emit zero flow labels early, before random is available
	 * (seeded).  RFC 6437:
	 *
	 * "A Flow Label of zero is used to indicate packets that have not been
	 * labeled."
	 */
	if (__predict_false(!is_random_seeded()))
		return (0);
#endif

	return randomid(&randomtab_20) & 0xfffff;
}