Function igmp_v1v2_queue_report

freebsd/netinet/igmp.c:2236–2294

* Dispatch an IGMPv1/v2 host report or leave message. * These are always small enough to fit inside a single mbuf. */

 * These are always small enough to fit inside a single mbuf.
 */
static int
igmp_v1v2_queue_report(struct in_multi *inm, const int type)
{
	struct epoch_tracker 	et;
	struct ifnet		*ifp;
	struct igmp		*igmp;
	struct ip		*ip;
	struct mbuf		*m;

	IN_MULTI_LIST_LOCK_ASSERT();
	IGMP_LOCK_ASSERT();

	ifp = inm->inm_ifp;

	m = m_gethdr(M_NOWAIT, MT_DATA);
	if (m == NULL)
		return (ENOMEM);
	M_ALIGN(m, sizeof(struct ip) + sizeof(struct igmp));

	m->m_pkthdr.len = sizeof(struct ip) + sizeof(struct igmp);

	m->m_data += sizeof(struct ip);
	m->m_len = sizeof(struct igmp);

	igmp = mtod(m, struct igmp *);
	igmp->igmp_type = type;
	igmp->igmp_code = 0;
	igmp->igmp_group = inm->inm_addr;
	igmp->igmp_cksum = 0;
	igmp->igmp_cksum = in_cksum(m, sizeof(struct igmp));

	m->m_data -= sizeof(struct ip);
	m->m_len += sizeof(struct ip);

	ip = mtod(m, struct ip *);
	ip->ip_tos = 0;
	ip->ip_len = htons(sizeof(struct ip) + sizeof(struct igmp));
	ip->ip_off = 0;
	ip->ip_p = IPPROTO_IGMP;
	ip->ip_src.s_addr = INADDR_ANY;

	if (type == IGMP_HOST_LEAVE_MESSAGE)
		ip->ip_dst.s_addr = htonl(INADDR_ALLRTRS_GROUP);
	else
		ip->ip_dst = inm->inm_addr;

	igmp_save_context(m, ifp);

	m->m_flags |= M_IGMPV2;
	if (inm->inm_igi->igi_flags & IGIF_LOOPBACK)
		m->m_flags |= M_IGMP_LOOP;

	CTR2(KTR_IGMPV3, "%s: netisr_dispatch(NETISR_IGMP, %p)", __func__, m);
	NET_EPOCH_ENTER(et);
	netisr_dispatch(NETISR_IGMP, m);
	NET_EPOCH_EXIT(et);

	return (0);