Function carp_input_c

freebsd/netinet/ip_carp.c:644–778

}

static void
carp_input_c(struct mbuf *m, struct carp_header *ch, sa_family_t af)
{
	struct ifnet *ifp = m->m_pkthdr.rcvif;
	struct ifaddr *ifa, *match;
	struct carp_softc *sc;
	uint64_t tmp_counter;
	struct timeval sc_tv, ch_tv;
	int error;

	NET_EPOCH_ASSERT();

	/*
	 * Verify that the VHID is valid on the receiving interface.
	 *
	 * There should be just one match.  If there are none
	 * the VHID is not valid and we drop the packet.  If
	 * there are multiple VHID matches, take just the first
	 * one, for compatibility with previous code.  While we're
	 * scanning, check for obvious loops in the network topology
	 * (these should never happen, and as noted above, we may
	 * miss real loops; this is just a double-check).
	 */
	error = 0;
	match = NULL;
	IFNET_FOREACH_IFA(ifp, ifa) {
		if (match == NULL && ifa->ifa_carp != NULL &&
		    ifa->ifa_addr->sa_family == af &&
		    ifa->ifa_carp->sc_vhid == ch->carp_vhid)
			match = ifa;
		if (ch->carp_vhid == 0 && carp_source_is_self(m, ifa, af))
			error = ELOOP;
	}
	ifa = error ? NULL : match;
	if (ifa != NULL)
		ifa_ref(ifa);

	if (ifa == NULL) {
		if (error == ELOOP) {
			CARP_DEBUG("dropping looped packet on interface %s\n",
			    ifp->if_xname);
			CARPSTATS_INC(carps_badif);	/* ??? */
		} else {
			CARPSTATS_INC(carps_badvhid);
		}
		m_freem(m);
		return;
	}

	/* verify the CARP version. */
	if (ch->carp_version != CARP_VERSION) {
		CARPSTATS_INC(carps_badver);
		CARP_DEBUG("%s: invalid version %d\n", ifp->if_xname,
		    ch->carp_version);
		ifa_free(ifa);
		m_freem(m);
		return;
	}