Function mld_dispatch_packet

freebsd/netinet6/mld6.c:3082–3183

* Transmit the next pending message in the output queue. * * VIMAGE: Needs to store/restore vnet pointer on a per-mbuf-chain basis. * MRT: Nothing needs to be done, as MLD traffic is always local to * a link and uses a link-scope multicast address. */

 * a link and uses a link-scope multicast address.
 */
static void
mld_dispatch_packet(struct mbuf *m)
{
	struct ip6_moptions	 im6o;
	struct ifnet		*ifp;
	struct ifnet		*oifp;
	struct mbuf		*m0;
	struct mbuf		*md;
	struct ip6_hdr		*ip6;
	struct mld_hdr		*mld;
	int			 error;
	int			 off;
	int			 type;
	uint32_t		 ifindex;

	CTR2(KTR_MLD, "%s: transmit %p", __func__, m);
	NET_EPOCH_ASSERT();

	/*
	 * Set VNET image pointer from enqueued mbuf chain
	 * before doing anything else. Whilst we use interface
	 * indexes to guard against interface detach, they are
	 * unique to each VIMAGE and must be retrieved.
	 */
	ifindex = mld_restore_context(m);

	/*
	 * Check if the ifnet still exists. This limits the scope of
	 * any race in the absence of a global ifp lock for low cost
	 * (an array lookup).
	 */
	ifp = ifnet_byindex(ifindex);
	if (ifp == NULL) {
		CTR3(KTR_MLD, "%s: dropped %p as ifindex %u went away.",
		    __func__, m, ifindex);
		m_freem(m);
		IP6STAT_INC(ip6s_noroute);
		goto out;
	}

	im6o.im6o_multicast_hlim  = 1;
	im6o.im6o_multicast_loop = (V_ip6_mrouter != NULL);
	im6o.im6o_multicast_ifp = ifp;

	if (m->m_flags & M_MLDV1) {
		m0 = m;
	} else {
		m0 = mld_v2_encap_report(ifp, m);
		if (m0 == NULL) {
			CTR2(KTR_MLD, "%s: dropped %p", __func__, m);
			IP6STAT_INC(ip6s_odropped);
			goto out;
		}
	}

	mld_scrub_context(m0);
	m_clrprotoflags(m);
	m0->m_pkthdr.rcvif = V_loif;