Do not obliterate QQI with MAXRESP.

[FreeBSD/FreeBSD.git] / sys / netinet / igmp.c

/*-
 * Copyright (c) 2007-2009 Bruce Simpson.
 * Copyright (c) 1988 Stephen Deering.
 * Copyright (c) 1992, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Stephen Deering of Stanford University.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)igmp.c      8.1 (Berkeley) 7/19/93
 */

/*
 * Internet Group Management Protocol (IGMP) routines.
 * [RFC1112, RFC2236, RFC3376]
 *
 * Written by Steve Deering, Stanford, May 1988.
 * Modified by Rosen Sharma, Stanford, Aug 1994.
 * Modified by Bill Fenner, Xerox PARC, Feb 1995.
 * Modified to fully comply to IGMPv2 by Bill Fenner, Oct 1995.
 * Significantly rewritten for IGMPv3, VIMAGE, and SMP by Bruce Simpson.
 *
 * MULTICAST Revision: 3.5.1.4
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include "opt_mac.h"
#include "opt_route.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/module.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/protosw.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/vimage.h>
#include <sys/ktr.h>
#include <sys/condvar.h>

#include <net/if.h>
#include <net/netisr.h>
#include <net/route.h>
#include <net/vnet.h>

#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/ip_options.h>
#include <netinet/igmp.h>
#include <netinet/igmp_var.h>
#include <netinet/vinet.h>

#include <machine/in_cksum.h>

#include <security/mac/mac_framework.h>

#ifndef KTR_IGMPV3
#define KTR_IGMPV3 KTR_SUBSYS
#endif

static struct igmp_ifinfo *
                igi_alloc_locked(struct ifnet *);
static void     igi_delete_locked(const struct ifnet *);
static void     igmp_dispatch_queue(struct ifqueue *, int, const int);
static void     igmp_fasttimo_vnet(void);
static void     igmp_final_leave(struct in_multi *, struct igmp_ifinfo *);
static int      igmp_handle_state_change(struct in_multi *,
                    struct igmp_ifinfo *);
static int      igmp_initial_join(struct in_multi *, struct igmp_ifinfo *);
static int      igmp_input_v1_query(struct ifnet *, const struct ip *);
static int      igmp_input_v2_query(struct ifnet *, const struct ip *,
                    const struct igmp *);
static int      igmp_input_v3_query(struct ifnet *, const struct ip *,
                    /*const*/ struct igmpv3 *);
static int      igmp_input_v3_group_query(struct in_multi *,
                    struct igmp_ifinfo *, int, /*const*/ struct igmpv3 *);
static int      igmp_input_v1_report(struct ifnet *, /*const*/ struct ip *,
                    /*const*/ struct igmp *);
static int      igmp_input_v2_report(struct ifnet *, /*const*/ struct ip *,
                    /*const*/ struct igmp *);
static void     igmp_intr(struct mbuf *);
static int      igmp_isgroupreported(const struct in_addr);
static struct mbuf *
                igmp_ra_alloc(void);
#ifdef KTR
static char *   igmp_rec_type_to_str(const int);
#endif
static void     igmp_set_version(struct igmp_ifinfo *, const int);
static void     igmp_slowtimo_vnet(void);
static void     igmp_sysinit(void);
static int      igmp_v1v2_queue_report(struct in_multi *, const int);
static void     igmp_v1v2_process_group_timer(struct in_multi *, const int);
static void     igmp_v1v2_process_querier_timers(struct igmp_ifinfo *);
static void     igmp_v2_update_group(struct in_multi *, const int);
static void     igmp_v3_cancel_link_timers(struct igmp_ifinfo *);
static void     igmp_v3_dispatch_general_query(struct igmp_ifinfo *);
static struct mbuf *
                igmp_v3_encap_report(struct ifnet *, struct mbuf *);
static int      igmp_v3_enqueue_group_record(struct ifqueue *,
                    struct in_multi *, const int, const int, const int);
static int      igmp_v3_enqueue_filter_change(struct ifqueue *,
                    struct in_multi *);
static void     igmp_v3_process_group_timers(struct igmp_ifinfo *,
                    struct ifqueue *, struct ifqueue *, struct in_multi *,
                    const int);
static int      igmp_v3_merge_state_changes(struct in_multi *,
                    struct ifqueue *);
static void     igmp_v3_suppress_group_record(struct in_multi *);
static int      sysctl_igmp_default_version(SYSCTL_HANDLER_ARGS);
static int      sysctl_igmp_gsr(SYSCTL_HANDLER_ARGS);
static int      sysctl_igmp_ifinfo(SYSCTL_HANDLER_ARGS);

#ifdef VIMAGE
static vnet_attach_fn   vnet_igmp_iattach;
static vnet_detach_fn   vnet_igmp_idetach;
#else
static int      vnet_igmp_iattach(const void *);
static int      vnet_igmp_idetach(const void *);
#endif /* VIMAGE */

/*
 * System-wide globals.
 *
 * Unlocked access to these is OK, except for the global IGMP output
 * queue. The IGMP subsystem lock ends up being system-wide for the moment,
 * because all VIMAGEs have to share a global output queue, as netisrs
 * themselves are not virtualized.
 *
 * Locking:
 *  * The permitted lock order is: IN_MULTI_LOCK, IGMP_LOCK, IF_ADDR_LOCK.
 *    Any may be taken independently; if any are held at the same
 *    time, the above lock order must be followed.
 *  * All output is delegated to the netisr to handle IFF_NEEDSGIANT.
 *    Most of the time, direct dispatch will be fine.
 *  * IN_MULTI_LOCK covers in_multi.
 *  * IGMP_LOCK covers igmp_ifinfo and any global variables in this file,
 *    including the output queue.
 *  * IF_ADDR_LOCK covers if_multiaddrs, which is used for a variety of
 *    per-link state iterators.
 *  * igmp_ifinfo is valid as long as PF_INET is attached to the interface,
 *    therefore it is not refcounted.
 *    We allow unlocked reads of igmp_ifinfo when accessed via in_multi.
 *
 * Reference counting
 *  * IGMP acquires its own reference every time an in_multi is passed to
 *    it and the group is being joined for the first time.
 *  * IGMP releases its reference(s) on in_multi in a deferred way,
 *    because the operations which process the release run as part of
 *    a loop whose control variables are directly affected by the release
 *    (that, and not recursing on the IF_ADDR_LOCK).
 *
 * VIMAGE: Each in_multi corresponds to an ifp, and each ifp corresponds
 * to a vnet in ifp->if_vnet.
 *
 * SMPng: XXX We may potentially race operations on ifma_protospec.
 * The problem is that we currently lack a clean way of taking the
 * IF_ADDR_LOCK() between the ifnet and in layers w/o recursing,
 * as anything which modifies ifma needs to be covered by that lock.
 * So check for ifma_protospec being NULL before proceeding.
 */
struct mtx               igmp_mtx;
int                      mpsafe_igmp = 0;
SYSCTL_INT(_debug, OID_AUTO, mpsafe_igmp, CTLFLAG_RDTUN, &mpsafe_igmp, 0,
    "Enable SMP-safe IGMPv3");

struct mbuf             *m_raopt;                /* Router Alert option */
MALLOC_DEFINE(M_IGMP, "igmp", "igmp state");

/*
 * Global netisr output queue.
 * This is only used as a last resort if we cannot directly dispatch.
 * As IN_MULTI_LOCK is no longer in the bottom half of IP, we can do
 * this, providing mpsafe_igmp is set. If it is not, we take Giant,
 * and queueing is forced.
 */
struct ifqueue           igmpoq;

/*
 * VIMAGE-wide globals.
 *
 * The IGMPv3 timers themselves need to run per-image, however,
 * protosw timers run globally (see tcp).
 * An ifnet can only be in one vimage at a time, and the loopback
 * ifnet, loif, is itself virtualized.
 * It would otherwise be possible to seriously hose IGMP state,
 * and create inconsistencies in upstream multicast routing, if you have
 * multiple VIMAGEs running on the same link joining different multicast
 * groups, UNLESS the "primary IP address" is different. This is because
 * IGMP for IPv4 does not force link-local addresses to be used for each
 * node, unlike MLD for IPv6.
 * Obviously the IGMPv3 per-interface state has per-vimage granularity
 * also as a result.
 *
 * FUTURE: Stop using IFP_TO_IA/INADDR_ANY, and use source address selection
 * policy to control the address used by IGMP on the link.
 */
#ifdef VIMAGE_GLOBALS
int      interface_timers_running;       /* IGMPv3 general query response */
int      state_change_timers_running;    /* IGMPv3 state-change retransmit */
int      current_state_timers_running;   /* IGMPv1/v2 host report;
                                          * IGMPv3 g/sg query response */

LIST_HEAD(, igmp_ifinfo)         igi_head;
struct igmpstat                  igmpstat;
struct timeval                   igmp_gsrdelay;

int      igmp_recvifkludge;
int      igmp_sendra;
int      igmp_sendlocal;
int      igmp_v1enable;
int      igmp_v2enable;
int      igmp_legacysupp;
int      igmp_default_version;
#endif /* VIMAGE_GLOBALS */

/*
 * Virtualized sysctls.
 */
SYSCTL_V_STRUCT(V_NET, vnet_inet, _net_inet_igmp, IGMPCTL_STATS, stats,
    CTLFLAG_RW, igmpstat, igmpstat, "");
SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_igmp, OID_AUTO, recvifkludge,
    CTLFLAG_RW, igmp_recvifkludge, 0,
    "Rewrite IGMPv1/v2 reports from 0.0.0.0 to contain subnet address");
SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_igmp, OID_AUTO, sendra,
    CTLFLAG_RW, igmp_sendra, 0,
    "Send IP Router Alert option in IGMPv2/v3 messages");
SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_igmp, OID_AUTO, sendlocal,
    CTLFLAG_RW, igmp_sendlocal, 0,
    "Send IGMP membership reports for 224.0.0.0/24 groups");
SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_igmp, OID_AUTO, v1enable,
    CTLFLAG_RW, igmp_v1enable, 0,
    "Enable backwards compatibility with IGMPv1");
SYSCTL_V_INT(V_NET, vnet_inet,  _net_inet_igmp, OID_AUTO, v2enable,
    CTLFLAG_RW, igmp_v2enable, 0,
    "Enable backwards compatibility with IGMPv2");
SYSCTL_V_INT(V_NET, vnet_inet, _net_inet_igmp, OID_AUTO, legacysupp,
    CTLFLAG_RW, igmp_legacysupp, 0,
    "Allow v1/v2 reports to suppress v3 group responses");
SYSCTL_V_PROC(V_NET, vnet_inet, _net_inet_igmp, OID_AUTO, default_version,
    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, igmp_default_version, 0,
    sysctl_igmp_default_version, "I",
    "Default version of IGMP to run on each interface");
SYSCTL_V_PROC(V_NET, vnet_inet, _net_inet_igmp, OID_AUTO, gsrdelay,
    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, igmp_gsrdelay.tv_sec, 0,
    sysctl_igmp_gsr, "I",
    "Rate limit for IGMPv3 Group-and-Source queries in seconds");

/*
 * Non-virtualized sysctls.
 */
SYSCTL_NODE(_net_inet_igmp, OID_AUTO, ifinfo, CTLFLAG_RD | CTLFLAG_MPSAFE,
    sysctl_igmp_ifinfo, "Per-interface IGMPv3 state");

static __inline void
igmp_save_context(struct mbuf *m, struct ifnet *ifp)
{

#ifdef VIMAGE
        m->m_pkthdr.header = ifp->if_vnet;
#endif /* VIMAGE */
        m->m_pkthdr.flowid = ifp->if_index;
}

static __inline void
igmp_scrub_context(struct mbuf *m)
{

        m->m_pkthdr.header = NULL;
        m->m_pkthdr.flowid = 0;
}

#ifdef KTR
static __inline char *
inet_ntoa_haddr(in_addr_t haddr)
{
        struct in_addr ia;

        ia.s_addr = htonl(haddr);
        return (inet_ntoa(ia));
}
#endif

/*
 * Restore context from a queued IGMP output chain.
 * Return saved ifindex.
 *
 * VIMAGE: The assertion is there to make sure that we
 * actually called CURVNET_SET() with what's in the mbuf chain.
 */
static __inline uint32_t
igmp_restore_context(struct mbuf *m)
{

#ifdef notyet
#if defined(VIMAGE) && defined(INVARIANTS)
        KASSERT(curvnet == (m->m_pkthdr.header),
            ("%s: called when curvnet was not restored", __func__));
#endif
#endif
        return (m->m_pkthdr.flowid);
}

/*
 * Retrieve or set default IGMP version.
 *
 * VIMAGE: Assume curvnet set by caller.
 * SMPng: NOTE: Serialized by IGMP lock.
 */
static int
sysctl_igmp_default_version(SYSCTL_HANDLER_ARGS)
{
        int      error;
        int      new;

        error = sysctl_wire_old_buffer(req, sizeof(int));
        if (error)
                return (error);

        IGMP_LOCK();

        new = V_igmp_default_version;

        error = sysctl_handle_int(oidp, &new, 0, req);
        if (error || !req->newptr)
                goto out_locked;

        if (new < IGMP_VERSION_1 || new > IGMP_VERSION_3) {
                error = EINVAL;
                goto out_locked;
        }

        CTR2(KTR_IGMPV3, "change igmp_default_version from %d to %d",
             V_igmp_default_version, new);

        V_igmp_default_version = new;

out_locked:
        IGMP_UNLOCK();
        return (error);
}

/*
 * Retrieve or set threshold between group-source queries in seconds.
 *
 * VIMAGE: Assume curvnet set by caller.
 * SMPng: NOTE: Serialized by IGMP lock.
 */
static int
sysctl_igmp_gsr(SYSCTL_HANDLER_ARGS)
{
        int error;
        int i;

        error = sysctl_wire_old_buffer(req, sizeof(int));
        if (error)
                return (error);

        IGMP_LOCK();

        i = V_igmp_gsrdelay.tv_sec;

        error = sysctl_handle_int(oidp, &i, 0, req);
        if (error || !req->newptr)
                goto out_locked;

        if (i < -1 || i >= 60) {
                error = EINVAL;
                goto out_locked;
        }

        CTR2(KTR_IGMPV3, "change igmp_gsrdelay from %d to %d",
             V_igmp_gsrdelay.tv_sec, i);
        V_igmp_gsrdelay.tv_sec = i;

out_locked:
        IGMP_UNLOCK();
        return (error);
}

/*
 * Expose struct igmp_ifinfo to userland, keyed by ifindex.
 * For use by ifmcstat(8).
 *
 * SMPng: NOTE: Does an unlocked ifindex space read.
 * VIMAGE: Assume curvnet set by caller. The node handler itself
 * is not directly virtualized.
 */
static int
sysctl_igmp_ifinfo(SYSCTL_HANDLER_ARGS)
{
        INIT_VNET_NET(curvnet);
        int                     *name;
        int                      error;
        u_int                    namelen;
        struct ifnet            *ifp;
        struct igmp_ifinfo      *igi;

        name = (int *)arg1;
        namelen = arg2;

        if (req->newptr != NULL)
                return (EPERM);

        if (namelen != 1)
                return (EINVAL);

        error = sysctl_wire_old_buffer(req, sizeof(struct igmp_ifinfo));
        if (error)
                return (error);

        IN_MULTI_LOCK();
        IGMP_LOCK();

        if (name[0] <= 0 || name[0] > V_if_index) {
                error = ENOENT;
                goto out_locked;
        }

        error = ENOENT;

        ifp = ifnet_byindex(name[0]);
        if (ifp == NULL)
                goto out_locked;

        LIST_FOREACH(igi, &V_igi_head, igi_link) {
                if (ifp == igi->igi_ifp) {
                        error = SYSCTL_OUT(req, igi,
                            sizeof(struct igmp_ifinfo));
                        break;
                }
        }

out_locked:
        IGMP_UNLOCK();
        IN_MULTI_UNLOCK();
        return (error);
}

/*
 * Dispatch an entire queue of pending packet chains
 * using the netisr.
 * VIMAGE: Assumes the vnet pointer has been set.
 */
static void
igmp_dispatch_queue(struct ifqueue *ifq, int limit, const int loop)
{
        struct mbuf *m;

        for (;;) {
                _IF_DEQUEUE(ifq, m);
                if (m == NULL)
                        break;
                CTR3(KTR_IGMPV3, "%s: dispatch %p from %p", __func__, ifq, m);
                if (loop)
                        m->m_flags |= M_IGMP_LOOP;
                netisr_dispatch(NETISR_IGMP, m);
                if (--limit == 0)
                        break;
        }
}

/*
 * Filter outgoing IGMP report state by group.
 *
 * Reports are ALWAYS suppressed for ALL-HOSTS (224.0.0.1).
 * If the net.inet.igmp.sendlocal sysctl is 0, then IGMP reports are
 * disabled for all groups in the 224.0.0.0/24 link-local scope. However,
 * this may break certain IGMP snooping switches which rely on the old
 * report behaviour.
 *
 * Return zero if the given group is one for which IGMP reports
 * should be suppressed, or non-zero if reports should be issued.
 */
static __inline int
igmp_isgroupreported(const struct in_addr addr)
{

        if (in_allhosts(addr) ||
            ((!V_igmp_sendlocal && IN_LOCAL_GROUP(ntohl(addr.s_addr)))))
                return (0);

        return (1);
}

/*
 * Construct a Router Alert option to use in outgoing packets.
 */
static struct mbuf *
igmp_ra_alloc(void)
{
        struct mbuf     *m;
        struct ipoption *p;

        MGET(m, M_DONTWAIT, MT_DATA);
        p = mtod(m, struct ipoption *);
        p->ipopt_dst.s_addr = INADDR_ANY;
        p->ipopt_list[0] = IPOPT_RA;    /* Router Alert Option */
        p->ipopt_list[1] = 0x04;        /* 4 bytes long */
        p->ipopt_list[2] = IPOPT_EOL;   /* End of IP option list */
        p->ipopt_list[3] = 0x00;        /* pad byte */
        m->m_len = sizeof(p->ipopt_dst) + p->ipopt_list[1];

        return (m);
}

/*
 * Attach IGMP when PF_INET is attached to an interface.
 *
 * VIMAGE: Currently we set the vnet pointer, although it is
 * likely that it was already set by our caller.
 */
struct igmp_ifinfo *
igmp_domifattach(struct ifnet *ifp)
{
        struct igmp_ifinfo *igi;

        CTR3(KTR_IGMPV3, "%s: called for ifp %p(%s)",
            __func__, ifp, ifp->if_xname);

        CURVNET_SET(ifp->if_vnet);
        IGMP_LOCK();

        igi = igi_alloc_locked(ifp);
        if (!(ifp->if_flags & IFF_MULTICAST))
                igi->igi_flags |= IGIF_SILENT;

        IGMP_UNLOCK();
        CURVNET_RESTORE();

        return (igi);
}

/*
 * VIMAGE: assume curvnet set by caller.
 */
static struct igmp_ifinfo *
igi_alloc_locked(/*const*/ struct ifnet *ifp)
{
        struct igmp_ifinfo *igi;

        IGMP_LOCK_ASSERT();

        igi = malloc(sizeof(struct igmp_ifinfo), M_IGMP, M_NOWAIT|M_ZERO);
        if (igi == NULL)
                goto out;

        igi->igi_ifp = ifp;
        igi->igi_version = V_igmp_default_version;
        igi->igi_flags = 0;
        igi->igi_rv = IGMP_RV_INIT;
        igi->igi_qi = IGMP_QI_INIT;
        igi->igi_qri = IGMP_QRI_INIT;
        igi->igi_uri = IGMP_URI_INIT;

        SLIST_INIT(&igi->igi_relinmhead);

        /*
         * Responses to general queries are subject to bounds.
         */
        IFQ_SET_MAXLEN(&igi->igi_gq, IGMP_MAX_RESPONSE_PACKETS);

        LIST_INSERT_HEAD(&V_igi_head, igi, igi_link);

        CTR2(KTR_IGMPV3, "allocate igmp_ifinfo for ifp %p(%s)",
             ifp, ifp->if_xname);

out:
        return (igi);
}

/*
 * Hook for ifdetach.
 *
 * NOTE: Some finalization tasks need to run before the protocol domain
 * is detached, but also before the link layer does its cleanup.
 *
 * SMPNG: igmp_ifdetach() needs to take IF_ADDR_LOCK().
 * XXX This is also bitten by unlocked ifma_protospec access.
 *
 * VIMAGE: curvnet should have been set by caller, but let's not assume
 * that for now.
 */
void
igmp_ifdetach(struct ifnet *ifp)
{
        struct igmp_ifinfo      *igi;
        struct ifmultiaddr      *ifma;
        struct in_multi         *inm, *tinm;

        CTR3(KTR_IGMPV3, "%s: called for ifp %p(%s)", __func__, ifp,
            ifp->if_xname);

        CURVNET_SET(ifp->if_vnet);

        IGMP_LOCK();

        igi = ((struct in_ifinfo *)ifp->if_afdata[AF_INET])->ii_igmp;
        if (igi->igi_version == IGMP_VERSION_3) {
                IF_ADDR_LOCK(ifp);
                TAILQ_FOREACH(ifma, &ifp->if_multiaddrs, ifma_link) {
                        if (ifma->ifma_addr->sa_family != AF_INET ||
                            ifma->ifma_protospec == NULL)
                                continue;
#if 0
                        KASSERT(ifma->ifma_protospec != NULL,
                            ("%s: ifma_protospec is NULL", __func__));
#endif
                        inm = (struct in_multi *)ifma->ifma_protospec;
                        if (inm->inm_state == IGMP_LEAVING_MEMBER) {
                                SLIST_INSERT_HEAD(&igi->igi_relinmhead,
                                    inm, inm_nrele);
                        }
                        inm_clear_recorded(inm);
                }
                IF_ADDR_UNLOCK(ifp);
                /*
                 * Free the in_multi reference(s) for this IGMP lifecycle.
                 */
                SLIST_FOREACH_SAFE(inm, &igi->igi_relinmhead, inm_nrele,
                    tinm) {
                        SLIST_REMOVE_HEAD(&igi->igi_relinmhead, inm_nrele);
                        inm_release_locked(inm);
                }
        }

        IGMP_UNLOCK();

#ifdef VIMAGE
        /*
         * Plug the potential race which may occur when a VIMAGE
         * is detached and we are forced to queue pending IGMP output for
         * output netisr processing due to !mpsafe_igmp. In this case it
         * is possible that igmp_intr() is about to see mbuf chains with
         * invalid cached curvnet pointers.
         * This is a rare condition, so just blow them all away.
         * FUTURE: This may in fact not be needed, because IFF_NEEDSGIANT
         * is being removed in 8.x and the netisr may then be eliminated;
         * it is needed only if VIMAGE and IFF_NEEDSGIANT need to co-exist
         */
        if (!mpsafe_igmp) {
                int drops;

                IF_LOCK(&igmpoq);
                drops = igmpoq.ifq_len;
                _IF_DRAIN(&igmpoq);
                IF_UNLOCK(&igmpoq);
                if (bootverbose && drops) {
                        printf("%s: dropped %d pending IGMP output packets\n",
                            __func__, drops);
                }
        }
#endif /* VIMAGE */

        CURVNET_RESTORE();
}

/*
 * Hook for domifdetach.
 *
 * VIMAGE: curvnet should have been set by caller, but let's not assume
 * that for now.
 */
void
igmp_domifdetach(struct ifnet *ifp)
{
        struct igmp_ifinfo *igi;

        CTR3(KTR_IGMPV3, "%s: called for ifp %p(%s)",
            __func__, ifp, ifp->if_xname);

        CURVNET_SET(ifp->if_vnet);
        IGMP_LOCK();

        igi = ((struct in_ifinfo *)ifp->if_afdata[AF_INET])->ii_igmp;
        igi_delete_locked(ifp);

        IGMP_UNLOCK();
        CURVNET_RESTORE();
}

static void
igi_delete_locked(const struct ifnet *ifp)
{
        struct igmp_ifinfo *igi, *tigi;

        CTR3(KTR_IGMPV3, "%s: freeing igmp_ifinfo for ifp %p(%s)",
            __func__, ifp, ifp->if_xname);

        IGMP_LOCK_ASSERT();

        LIST_FOREACH_SAFE(igi, &V_igi_head, igi_link, tigi) {
                if (igi->igi_ifp == ifp) {
                        /*
                         * Free deferred General Query responses.
                         */
                        _IF_DRAIN(&igi->igi_gq);

                        LIST_REMOVE(igi, igi_link);

                        KASSERT(SLIST_EMPTY(&igi->igi_relinmhead),
                            ("%s: there are dangling in_multi references",
                            __func__));

                        free(igi, M_IGMP);
                        return;
                }
        }

#ifdef INVARIANTS
        panic("%s: igmp_ifinfo not found for ifp %p\n", __func__,  ifp);
#endif
}

/*
 * Process a received IGMPv1 query.
 * Return non-zero if the message should be dropped.
 *
 * VIMAGE: The curvnet pointer is derived from the input ifp.
 */
static int
igmp_input_v1_query(struct ifnet *ifp, const struct ip *ip)
{
        INIT_VNET_INET(ifp->if_vnet);
        struct ifmultiaddr      *ifma;
        struct igmp_ifinfo      *igi;
        struct in_multi         *inm;

        /*
         * IGMPv1 General Queries SHOULD always addressed to 224.0.0.1.
         * igmp_group is always ignored. Do not drop it as a userland
         * daemon may wish to see it.
         */
        if (!in_allhosts(ip->ip_dst)) {
                ++V_igmpstat.igps_rcv_badqueries;
                return (0);
        }

        ++V_igmpstat.igps_rcv_gen_queries;

        /*
         * Switch to IGMPv1 host compatibility mode.
         */
        IN_MULTI_LOCK();
        IGMP_LOCK();

        igi = ((struct in_ifinfo *)ifp->if_afdata[AF_INET])->ii_igmp;
        KASSERT(igi != NULL, ("%s: no igmp_ifinfo for ifp %p", __func__, ifp));

        if (igi->igi_flags & IGIF_LOOPBACK) {
                CTR2(KTR_IGMPV3, "ignore v1 query on IGIF_LOOPBACK ifp %p(%s)",
                    ifp, ifp->if_xname);
                goto out_locked;
        }

        igmp_set_version(igi, IGMP_VERSION_1);

        CTR2(KTR_IGMPV3, "process v1 query on ifp %p(%s)", ifp, ifp->if_xname);

        /*
         * Start the timers in all of our group records
         * for the interface on which the query arrived,
         * except those which are already running.
         */
        IF_ADDR_LOCK(ifp);
        TAILQ_FOREACH(ifma, &ifp->if_multiaddrs, ifma_link) {
                if (ifma->ifma_addr->sa_family != AF_INET ||
                    ifma->ifma_protospec == NULL)
                        continue;
                inm = (struct in_multi *)ifma->ifma_protospec;
                if (inm->inm_timer != 0)
                        continue;
                switch (inm->inm_state) {
                case IGMP_NOT_MEMBER:
                case IGMP_SILENT_MEMBER:
                        break;
                case IGMP_G_QUERY_PENDING_MEMBER:
                case IGMP_SG_QUERY_PENDING_MEMBER:
                case IGMP_REPORTING_MEMBER:
                case IGMP_IDLE_MEMBER:
                case IGMP_LAZY_MEMBER:
                case IGMP_SLEEPING_MEMBER:
                case IGMP_AWAKENING_MEMBER:
                        inm->inm_state = IGMP_REPORTING_MEMBER;
                        inm->inm_timer = IGMP_RANDOM_DELAY(
                            IGMP_V1V2_MAX_RI * PR_FASTHZ);
                        V_current_state_timers_running = 1;
                        break;
                case IGMP_LEAVING_MEMBER:
                        break;
                }
        }
        IF_ADDR_UNLOCK(ifp);

out_locked:
        IGMP_UNLOCK();
        IN_MULTI_UNLOCK();

        return (0);
}

/*
 * Process a received IGMPv2 general or group-specific query.
 */
static int
igmp_input_v2_query(struct ifnet *ifp, const struct ip *ip,
    const struct igmp *igmp)
{
        struct ifmultiaddr      *ifma;
        struct igmp_ifinfo      *igi;
        struct in_multi         *inm;
        uint16_t                 timer;

        /*
         * Perform lazy allocation of IGMP link info if required,
         * and switch to IGMPv2 host compatibility mode.
         */
        IN_MULTI_LOCK();
        IGMP_LOCK();

        igi = ((struct in_ifinfo *)ifp->if_afdata[AF_INET])->ii_igmp;
        KASSERT(igi != NULL, ("%s: no igmp_ifinfo for ifp %p", __func__, ifp));

        if (igi->igi_flags & IGIF_LOOPBACK) {
                CTR2(KTR_IGMPV3, "ignore v2 query on IGIF_LOOPBACK ifp %p(%s)",
                    ifp, ifp->if_xname);
                goto out_locked;
        }

        igmp_set_version(igi, IGMP_VERSION_2);

        timer = igmp->igmp_code * PR_FASTHZ / IGMP_TIMER_SCALE;
        if (timer == 0)
                timer = 1;

        if (!in_nullhost(igmp->igmp_group)) {
                /*
                 * IGMPv2 Group-Specific Query.
                 * If this is a group-specific IGMPv2 query, we need only
                 * look up the single group to process it.
                 */
                inm = inm_lookup(ifp, igmp->igmp_group);
                if (inm != NULL) {
                        CTR3(KTR_IGMPV3, "process v2 query %s on ifp %p(%s)",
                            inet_ntoa(igmp->igmp_group), ifp, ifp->if_xname);
                        igmp_v2_update_group(inm, timer);
                }
                ++V_igmpstat.igps_rcv_group_queries;
        } else {
                /*
                 * IGMPv2 General Query.
                 * If this was not sent to the all-hosts group, ignore it.
                 */
                if (in_allhosts(ip->ip_dst)) {
                        /*
                         * For each reporting group joined on this
                         * interface, kick the report timer.
                         */
                        CTR2(KTR_IGMPV3,
                            "process v2 general query on ifp %p(%s)",
                            ifp, ifp->if_xname);

                        IF_ADDR_LOCK(ifp);
                        TAILQ_FOREACH(ifma, &ifp->if_multiaddrs, ifma_link) {
                                if (ifma->ifma_addr->sa_family != AF_INET ||
                                    ifma->ifma_protospec == NULL)
                                        continue;
                                inm = (struct in_multi *)ifma->ifma_protospec;
                                igmp_v2_update_group(inm, timer);
                        }
                        IF_ADDR_UNLOCK(ifp);
                }
                ++V_igmpstat.igps_rcv_gen_queries;
        }

out_locked:
        IGMP_UNLOCK();
        IN_MULTI_UNLOCK();

        return (0);
}

/*
 * Update the report timer on a group in response to an IGMPv2 query.
 *
 * If we are becoming the reporting member for this group, start the timer.
 * If we already are the reporting member for this group, and timer is
 * below the threshold, reset it.
 *
 * We may be updating the group for the first time since we switched
 * to IGMPv3. If we are, then we must clear any recorded source lists,
 * and transition to REPORTING state; the group timer is overloaded
 * for group and group-source query responses. 
 *
 * Unlike IGMPv3, the delay per group should be jittered
 * to avoid bursts of IGMPv2 reports.
 */
static void
igmp_v2_update_group(struct in_multi *inm, const int timer)
{

        CTR4(KTR_IGMPV3, "%s: %s/%s timer=%d", __func__,
            inet_ntoa(inm->inm_addr), inm->inm_ifp->if_xname, timer);

        IN_MULTI_LOCK_ASSERT();

        switch (inm->inm_state) {
        case IGMP_NOT_MEMBER:
        case IGMP_SILENT_MEMBER:
                break;
        case IGMP_REPORTING_MEMBER:
                if (inm->inm_timer != 0 &&
                    inm->inm_timer <= timer) {
                        CTR1(KTR_IGMPV3, "%s: REPORTING and timer running, "
                            "skipping.", __func__);
                        break;
                }
                /* FALLTHROUGH */
        case IGMP_SG_QUERY_PENDING_MEMBER:
        case IGMP_G_QUERY_PENDING_MEMBER:
        case IGMP_IDLE_MEMBER:
        case IGMP_LAZY_MEMBER:
        case IGMP_AWAKENING_MEMBER:
                CTR1(KTR_IGMPV3, "%s: ->REPORTING", __func__);
                inm->inm_state = IGMP_REPORTING_MEMBER;
                inm->inm_timer = IGMP_RANDOM_DELAY(timer);
                V_current_state_timers_running = 1;
                break;
        case IGMP_SLEEPING_MEMBER:
                CTR1(KTR_IGMPV3, "%s: ->AWAKENING", __func__);
                inm->inm_state = IGMP_AWAKENING_MEMBER;
                break;
        case IGMP_LEAVING_MEMBER:
                break;
        }
}

/*
 * Process a received IGMPv3 general, group-specific or
 * group-and-source-specific query.
 * Assumes m has already been pulled up to the full IGMP message length.
 * Return 0 if successful, otherwise an appropriate error code is returned.
 */
static int
igmp_input_v3_query(struct ifnet *ifp, const struct ip *ip,
    /*const*/ struct igmpv3 *igmpv3)
{
        struct igmp_ifinfo      *igi;
        struct in_multi         *inm;
        uint32_t                 maxresp, nsrc, qqi;
        uint16_t                 timer;
        uint8_t                  qrv;

        CTR2(KTR_IGMPV3, "process v3 query on ifp %p(%s)", ifp, ifp->if_xname);

        maxresp = igmpv3->igmp_code;    /* in 1/10ths of a second */
        if (maxresp >= 128) {
                maxresp = IGMP_MANT(igmpv3->igmp_code) <<
                          (IGMP_EXP(igmpv3->igmp_code) + 3);
        }

        /*
         * Robustness must never be less than 2 for on-wire IGMPv3.
         * FIXME: Check if ifp has IGIF_LOOPBACK set, as we make
         * an exception for interfaces whose IGMPv3 state changes
         * are redirected to loopback (e.g. MANET).
         */
        qrv = IGMP_QRV(igmpv3->igmp_misc);
        if (qrv < 2) {
                CTR3(KTR_IGMPV3, "%s: clamping qrv %d to %d", __func__,
                    qrv, IGMP_RV_INIT);
                qrv = IGMP_RV_INIT;
        }

        qqi = igmpv3->igmp_qqi;
        if (qqi >= 128) {
                qqi = IGMP_MANT(igmpv3->igmp_qqi) <<
                     (IGMP_EXP(igmpv3->igmp_qqi) + 3);
        }

        timer = maxresp * PR_FASTHZ / IGMP_TIMER_SCALE;
        if (timer == 0)
                timer = 1;

        nsrc = ntohs(igmpv3->igmp_numsrc);

        IN_MULTI_LOCK();
        IGMP_LOCK();

        igi = ((struct in_ifinfo *)ifp->if_afdata[AF_INET])->ii_igmp;
        KASSERT(igi != NULL, ("%s: no igmp_ifinfo for ifp %p", __func__, ifp));

        if (igi->igi_flags & IGIF_LOOPBACK) {
                CTR2(KTR_IGMPV3, "ignore v3 query on IGIF_LOOPBACK ifp %p(%s)",
                    ifp, ifp->if_xname);
                goto out_locked;
        }

        igmp_set_version(igi, IGMP_VERSION_3);

        igi->igi_rv = qrv;
        igi->igi_qi = qqi;
        igi->igi_qri = maxresp;

        CTR4(KTR_IGMPV3, "%s: qrv %d qi %d qri %d", __func__, qrv, qqi,
            maxresp);

        if (in_nullhost(igmpv3->igmp_group)) {
                /*
                 * IGMPv3 General Query.
                 * Schedule a current-state report on this ifp for
                 * all groups, possibly containing source lists.
                 */
                ++V_igmpstat.igps_rcv_gen_queries;

                if (!in_allhosts(ip->ip_dst) || nsrc > 0) {
                        /*
                         * General Queries SHOULD be directed to 224.0.0.1.
                         * A general query with a source list has undefined
                         * behaviour; discard it.
                         */
                        ++V_igmpstat.igps_rcv_badqueries;
                        goto out_locked;
                }

                CTR2(KTR_IGMPV3, "process v3 general query on ifp %p(%s)",
                    ifp, ifp->if_xname);

                /*
                 * If there is a pending General Query response
                 * scheduled earlier than the selected delay, do
                 * not schedule any other reports.
                 * Otherwise, reset the interface timer.
                 */
                if (igi->igi_v3_timer == 0 || igi->igi_v3_timer >= timer) {
                        igi->igi_v3_timer = IGMP_RANDOM_DELAY(timer);
                        V_interface_timers_running = 1;
                }
        } else {
                /*
                 * IGMPv3 Group-specific or Group-and-source-specific Query.
                 *
                 * Group-source-specific queries are throttled on
                 * a per-group basis to defeat denial-of-service attempts.
                 * Queries for groups we are not a member of on this
                 * link are simply ignored.
                 */
                inm = inm_lookup(ifp, igmpv3->igmp_group);
                if (inm == NULL)
                        goto out_locked;
                if (nsrc > 0) {
                        ++V_igmpstat.igps_rcv_gsr_queries;
                        if (!ratecheck(&inm->inm_lastgsrtv,
                            &V_igmp_gsrdelay)) {
                                CTR1(KTR_IGMPV3, "%s: GS query throttled.",
                                    __func__);
                                ++V_igmpstat.igps_drop_gsr_queries;
                                goto out_locked;
                        }
                } else {
                        ++V_igmpstat.igps_rcv_group_queries;
                }
                CTR3(KTR_IGMPV3, "process v3 %s query on ifp %p(%s)",
                     inet_ntoa(igmpv3->igmp_group), ifp, ifp->if_xname);
                /*
                 * If there is a pending General Query response
                 * scheduled sooner than the selected delay, no
                 * further report need be scheduled.
                 * Otherwise, prepare to respond to the
                 * group-specific or group-and-source query.
                 */
                if (igi->igi_v3_timer == 0 || igi->igi_v3_timer >= timer)
                        igmp_input_v3_group_query(inm, igi, timer, igmpv3);
        }

out_locked:
        IGMP_UNLOCK();
        IN_MULTI_UNLOCK();

        return (0);
}

/*
 * Process a recieved IGMPv3 group-specific or group-and-source-specific
 * query.
 * Return <0 if any error occured. Currently this is ignored.
 */
static int
igmp_input_v3_group_query(struct in_multi *inm, struct igmp_ifinfo *igi,
    int timer, /*const*/ struct igmpv3 *igmpv3)
{
        int                      retval;
        uint16_t                 nsrc;

        IN_MULTI_LOCK_ASSERT();
        IGMP_LOCK_ASSERT();

        retval = 0;

        switch (inm->inm_state) {
        case IGMP_NOT_MEMBER:
        case IGMP_SILENT_MEMBER:
        case IGMP_SLEEPING_MEMBER:
        case IGMP_LAZY_MEMBER:
        case IGMP_AWAKENING_MEMBER:
        case IGMP_IDLE_MEMBER:
        case IGMP_LEAVING_MEMBER:
                return (retval);
                break;
        case IGMP_REPORTING_MEMBER:
        case IGMP_G_QUERY_PENDING_MEMBER:
        case IGMP_SG_QUERY_PENDING_MEMBER:
                break;
        }

        nsrc = ntohs(igmpv3->igmp_numsrc);

        /*
         * Deal with group-specific queries upfront.
         * If any group query is already pending, purge any recorded
         * source-list state if it exists, and schedule a query response
         * for this group-specific query.
         */
        if (nsrc == 0) {
                if (inm->inm_state == IGMP_G_QUERY_PENDING_MEMBER ||
                    inm->inm_state == IGMP_SG_QUERY_PENDING_MEMBER) {
                        inm_clear_recorded(inm);
                        timer = min(inm->inm_timer, timer);
                }
                inm->inm_state = IGMP_G_QUERY_PENDING_MEMBER;
                inm->inm_timer = IGMP_RANDOM_DELAY(timer);
                V_current_state_timers_running = 1;
                return (retval);
        }

        /*
         * Deal with the case where a group-and-source-specific query has
         * been received but a group-specific query is already pending.
         */
        if (inm->inm_state == IGMP_G_QUERY_PENDING_MEMBER) {
                timer = min(inm->inm_timer, timer);
                inm->inm_timer = IGMP_RANDOM_DELAY(timer);
                V_current_state_timers_running = 1;
                return (retval);
        }

        /*
         * Finally, deal with the case where a group-and-source-specific
         * query has been received, where a response to a previous g-s-r
         * query exists, or none exists.
         * In this case, we need to parse the source-list which the Querier
         * has provided us with and check if we have any source list filter
         * entries at T1 for these sources. If we do not, there is no need
         * schedule a report and the query may be dropped.
         * If we do, we must record them and schedule a current-state
         * report for those sources.
         * FIXME: Handling source lists larger than 1 mbuf requires that
         * we pass the mbuf chain pointer down to this function, and use
         * m_getptr() to walk the chain.
         */
        if (inm->inm_nsrc > 0) {
                const struct in_addr    *ap;
                int                      i, nrecorded;

                ap = (const struct in_addr *)(igmpv3 + 1);
                nrecorded = 0;
                for (i = 0; i < nsrc; i++, ap++) {
                        retval = inm_record_source(inm, ap->s_addr);
                        if (retval < 0)
                                break;
                        nrecorded += retval;
                }
                if (nrecorded > 0) {
                        CTR1(KTR_IGMPV3,
                            "%s: schedule response to SG query", __func__);
                        inm->inm_state = IGMP_SG_QUERY_PENDING_MEMBER;
                        inm->inm_timer = IGMP_RANDOM_DELAY(timer);
                        V_current_state_timers_running = 1;
                }
        }

        return (retval);
}

/*
 * Process a received IGMPv1 host membership report.
 *
 * NOTE: 0.0.0.0 workaround breaks const correctness.
 */
static int
igmp_input_v1_report(struct ifnet *ifp, /*const*/ struct ip *ip,
    /*const*/ struct igmp *igmp)
{
        struct in_ifaddr *ia;
        struct in_multi *inm;

        ++V_igmpstat.igps_rcv_reports;

        if (ifp->if_flags & IFF_LOOPBACK)
                return (0);

        if (!IN_MULTICAST(ntohl(igmp->igmp_group.s_addr) ||
            !in_hosteq(igmp->igmp_group, ip->ip_dst))) {
                ++V_igmpstat.igps_rcv_badreports;
                return (EINVAL);
        }

        /*
         * RFC 3376, Section 4.2.13, 9.2, 9.3:
         * Booting clients may use the source address 0.0.0.0. Some
         * IGMP daemons may not know how to use IP_RECVIF to determine
         * the interface upon which this message was received.
         * Replace 0.0.0.0 with the subnet address if told to do so.
         */
        if (V_igmp_recvifkludge && in_nullhost(ip->ip_src)) {
                IFP_TO_IA(ifp, ia);
                if (ia != NULL)
                        ip->ip_src.s_addr = htonl(ia->ia_subnet);
        }

        CTR3(KTR_IGMPV3, "process v1 report %s on ifp %p(%s)",
             inet_ntoa(igmp->igmp_group), ifp, ifp->if_xname);

        /*
         * IGMPv1 report suppression.
         * If we are a member of this group, and our membership should be
         * reported, stop our group timer and transition to the 'lazy' state.
         */
        IN_MULTI_LOCK();
        inm = inm_lookup(ifp, igmp->igmp_group);
        if (inm != NULL) {
                struct igmp_ifinfo *igi;

                igi = inm->inm_igi;
                if (igi == NULL) {
                        KASSERT(igi != NULL,
                            ("%s: no igi for ifp %p", __func__, ifp));
                        goto out_locked;
                }

                ++V_igmpstat.igps_rcv_ourreports;

                /*
                 * If we are in IGMPv3 host mode, do not allow the
                 * other host's IGMPv1 report to suppress our reports
                 * unless explicitly configured to do so.
                 */
                if (igi->igi_version == IGMP_VERSION_3) {
                        if (V_igmp_legacysupp)
                                igmp_v3_suppress_group_record(inm);
                        goto out_locked;
                }

                inm->inm_timer = 0;

                switch (inm->inm_state) {
                case IGMP_NOT_MEMBER:
                case IGMP_SILENT_MEMBER:
                        break;
                case IGMP_IDLE_MEMBER:
                case IGMP_LAZY_MEMBER:
                case IGMP_AWAKENING_MEMBER:
                        CTR3(KTR_IGMPV3,
                            "report suppressed for %s on ifp %p(%s)",
                            inet_ntoa(igmp->igmp_group), ifp, ifp->if_xname);
                case IGMP_SLEEPING_MEMBER:
                        inm->inm_state = IGMP_SLEEPING_MEMBER;
                        break;
                case IGMP_REPORTING_MEMBER:
                        CTR3(KTR_IGMPV3,
                            "report suppressed for %s on ifp %p(%s)",
                            inet_ntoa(igmp->igmp_group), ifp, ifp->if_xname);
                        if (igi->igi_version == IGMP_VERSION_1)
                                inm->inm_state = IGMP_LAZY_MEMBER;
                        else if (igi->igi_version == IGMP_VERSION_2)
                                inm->inm_state = IGMP_SLEEPING_MEMBER;
                        break;
                case IGMP_G_QUERY_PENDING_MEMBER:
                case IGMP_SG_QUERY_PENDING_MEMBER:
                case IGMP_LEAVING_MEMBER:
                        break;
                }
        }

out_locked:
        IN_MULTI_UNLOCK();

        return (0);
}

/*
 * Process a received IGMPv2 host membership report.
 *
 * NOTE: 0.0.0.0 workaround breaks const correctness.
 */
static int
igmp_input_v2_report(struct ifnet *ifp, /*const*/ struct ip *ip,
    /*const*/ struct igmp *igmp)
{
        struct in_ifaddr *ia;
        struct in_multi *inm;

        /*
         * Make sure we don't hear our own membership report.  Fast
         * leave requires knowing that we are the only member of a
         * group.
         */
        IFP_TO_IA(ifp, ia);
        if (ia != NULL && in_hosteq(ip->ip_src, IA_SIN(ia)->sin_addr))
                return (0);

        ++V_igmpstat.igps_rcv_reports;

        if (ifp->if_flags & IFF_LOOPBACK)
                return (0);

        if (!IN_MULTICAST(ntohl(igmp->igmp_group.s_addr)) ||
            !in_hosteq(igmp->igmp_group, ip->ip_dst)) {
                ++V_igmpstat.igps_rcv_badreports;
                return (EINVAL);
        }

        /*
         * RFC 3376, Section 4.2.13, 9.2, 9.3:
         * Booting clients may use the source address 0.0.0.0. Some
         * IGMP daemons may not know how to use IP_RECVIF to determine
         * the interface upon which this message was received.
         * Replace 0.0.0.0 with the subnet address if told to do so.
         */
        if (V_igmp_recvifkludge && in_nullhost(ip->ip_src)) {
                if (ia != NULL)
                        ip->ip_src.s_addr = htonl(ia->ia_subnet);
        }

        CTR3(KTR_IGMPV3, "process v2 report %s on ifp %p(%s)",
             inet_ntoa(igmp->igmp_group), ifp, ifp->if_xname);

        /*
         * IGMPv2 report suppression.
         * If we are a member of this group, and our membership should be
         * reported, and our group timer is pending or about to be reset,
         * stop our group timer by transitioning to the 'lazy' state.
         */
        IN_MULTI_LOCK();
        inm = inm_lookup(ifp, igmp->igmp_group);
        if (inm != NULL) {
                struct igmp_ifinfo *igi;

                igi = inm->inm_igi;
                KASSERT(igi != NULL, ("%s: no igi for ifp %p", __func__, ifp));

                ++V_igmpstat.igps_rcv_ourreports;

                /*
                 * If we are in IGMPv3 host mode, do not allow the
                 * other host's IGMPv1 report to suppress our reports
                 * unless explicitly configured to do so.
                 */
                if (igi->igi_version == IGMP_VERSION_3) {
                        if (V_igmp_legacysupp)
                                igmp_v3_suppress_group_record(inm);
                        goto out_locked;
                }

                inm->inm_timer = 0;

                switch (inm->inm_state) {
                case IGMP_NOT_MEMBER:
                case IGMP_SILENT_MEMBER:
                case IGMP_SLEEPING_MEMBER:
                        break;
                case IGMP_REPORTING_MEMBER:
                case IGMP_IDLE_MEMBER:
                case IGMP_AWAKENING_MEMBER:
                        CTR3(KTR_IGMPV3,
                            "report suppressed for %s on ifp %p(%s)",
                            inet_ntoa(igmp->igmp_group), ifp, ifp->if_xname);
                case IGMP_LAZY_MEMBER:
                        inm->inm_state = IGMP_LAZY_MEMBER;
                        break;
                case IGMP_G_QUERY_PENDING_MEMBER:
                case IGMP_SG_QUERY_PENDING_MEMBER:
                case IGMP_LEAVING_MEMBER:
                        break;
                }
        }

out_locked:
        IN_MULTI_UNLOCK();

        return (0);
}

void
igmp_input(struct mbuf *m, int off)
{
        int iphlen;
        struct ifnet *ifp;
        struct igmp *igmp;
        struct ip *ip;
        int igmplen;
        int minlen;
        int queryver;

        CTR3(KTR_IGMPV3, "%s: called w/mbuf (%p,%d)", __func__, m, off);

        ifp = m->m_pkthdr.rcvif;
        INIT_VNET_INET(ifp->if_vnet);

        ++V_igmpstat.igps_rcv_total;

        ip = mtod(m, struct ip *);
        iphlen = off;
        igmplen = ip->ip_len;

        /*
         * Validate lengths.
         */
        if (igmplen < IGMP_MINLEN) {
                ++V_igmpstat.igps_rcv_tooshort;
                m_freem(m);
                return;
        }

        /*
         * Always pullup to the minimum size for v1/v2 or v3
         * to amortize calls to m_pullup().
         */
        minlen = iphlen;
        if (igmplen >= IGMP_V3_QUERY_MINLEN)
                minlen += IGMP_V3_QUERY_MINLEN;
        else
                minlen += IGMP_MINLEN;
        if ((m->m_flags & M_EXT || m->m_len < minlen) &&
            (m = m_pullup(m, minlen)) == 0) {
                ++V_igmpstat.igps_rcv_tooshort;
                return;
        }
        ip = mtod(m, struct ip *);

        if (ip->ip_ttl != 1) {
                ++V_igmpstat.igps_rcv_badttl;
                m_freem(m);
                return;
        }

        /*
         * Validate checksum.
         */
        m->m_data += iphlen;
        m->m_len -= iphlen;
        igmp = mtod(m, struct igmp *);
        if (in_cksum(m, igmplen)) {
                ++V_igmpstat.igps_rcv_badsum;
                m_freem(m);
                return;
        }
        m->m_data -= iphlen;
        m->m_len += iphlen;

        switch (igmp->igmp_type) {
        case IGMP_HOST_MEMBERSHIP_QUERY:
                if (igmplen == IGMP_MINLEN) {
                        if (igmp->igmp_code == 0)
                                queryver = IGMP_VERSION_1;
                        else
                                queryver = IGMP_VERSION_2;
                } else if (igmplen >= IGMP_V3_QUERY_MINLEN) {
                        queryver = IGMP_VERSION_3;
                } else {
                        ++V_igmpstat.igps_rcv_tooshort;
                        m_freem(m);
                        return;
                }

                switch (queryver) {
                case IGMP_VERSION_1:
                        ++V_igmpstat.igps_rcv_v1v2_queries;
                        if (!V_igmp_v1enable)
                                break;
                        if (igmp_input_v1_query(ifp, ip) != 0) {
                                m_freem(m);
                                return;
                        }
                        break;

                case IGMP_VERSION_2:
                        ++V_igmpstat.igps_rcv_v1v2_queries;
                        if (!V_igmp_v2enable)
                                break;
                        if (igmp_input_v2_query(ifp, ip, igmp) != 0) {
                                m_freem(m);
                                return;
                        }
                        break;

                case IGMP_VERSION_3: {
                                struct igmpv3 *igmpv3;
                                uint16_t igmpv3len;
                                uint16_t srclen;
                                int nsrc;

                                ++V_igmpstat.igps_rcv_v3_queries;
                                igmpv3 = (struct igmpv3 *)igmp;
                                /*
                                 * Validate length based on source count.
                                 */
                                nsrc = ntohs(igmpv3->igmp_numsrc);
                                srclen = sizeof(struct in_addr) * nsrc;
                                if (nsrc * sizeof(in_addr_t) > srclen) {
                                        ++V_igmpstat.igps_rcv_tooshort;
                                        return;
                                }
                                /*
                                 * m_pullup() may modify m, so pullup in
                                 * this scope.
                                 */
                                igmpv3len = iphlen + IGMP_V3_QUERY_MINLEN +
                                    srclen;
                                if ((m->m_flags & M_EXT ||
                                     m->m_len < igmpv3len) &&
                                    (m = m_pullup(m, igmpv3len)) == NULL) {
                                        ++V_igmpstat.igps_rcv_tooshort;
                                        return;
                                }
                                igmpv3 = (struct igmpv3 *)(mtod(m, uint8_t *)
                                    + iphlen);
                                if (igmp_input_v3_query(ifp, ip, igmpv3) != 0) {
                                        m_freem(m);
                                        return;
                                }
                        }
                        break;
                }
                break;

        case IGMP_v1_HOST_MEMBERSHIP_REPORT:
                if (!V_igmp_v1enable)
                        break;
                if (igmp_input_v1_report(ifp, ip, igmp) != 0) {
                        m_freem(m);
                        return;
                }
                break;

        case IGMP_v2_HOST_MEMBERSHIP_REPORT:
                if (!V_igmp_v2enable)
                        break;
                if (!ip_checkrouteralert(m))
                        ++V_igmpstat.igps_rcv_nora;
                if (igmp_input_v2_report(ifp, ip, igmp) != 0) {
                        m_freem(m);
                        return;
                }
                break;

        case IGMP_v3_HOST_MEMBERSHIP_REPORT:
                /*
                 * Hosts do not need to process IGMPv3 membership reports,
                 * as report suppression is no longer required.
                 */
                if (!ip_checkrouteralert(m))
                        ++V_igmpstat.igps_rcv_nora;
                break;

        default:
                break;
        }

        /*
         * Pass all valid IGMP packets up to any process(es) listening on a
         * raw IGMP socket.
         */
        rip_input(m, off);
}


/*
 * Fast timeout handler (global).
 * VIMAGE: Timeout handlers are expected to service all vimages.
 */
void
igmp_fasttimo(void)
{
#ifdef VIMAGE
        VNET_ITERATOR_DECL(vnet_iter);

        VNET_LIST_RLOCK();
        VNET_FOREACH(vnet_iter) {
                CURVNET_SET(vnet_iter);
                INIT_VNET_INET(vnet_iter);
                igmp_fasttimo_vnet();
                CURVNET_RESTORE();
        }
        VNET_LIST_RUNLOCK();
#else /* !VIMAGE */

        igmp_fasttimo_vnet();
#endif /* VIMAGE */
}

/*
 * Fast timeout handler (per-vnet).
 * Sends are shuffled off to a netisr to deal with Giant.
 *
 * VIMAGE: Assume caller has set up our curvnet.
 */
static void
igmp_fasttimo_vnet(void)
{
        struct ifqueue           scq;   /* State-change packets */
        struct ifqueue           qrq;   /* Query response packets */
        struct ifnet            *ifp;
        struct igmp_ifinfo      *igi;
        struct ifmultiaddr      *ifma, *tifma;
        struct in_multi         *inm;
        int                      loop, uri_fasthz;

        loop = 0;
        uri_fasthz = 0;

        /*
         * Quick check to see if any work needs to be done, in order to
         * minimize the overhead of fasttimo processing.
         * SMPng: XXX Unlocked reads.
         */
        if (!V_current_state_timers_running &&
            !V_interface_timers_running &&
            !V_state_change_timers_running)
                return;

        if (!mpsafe_igmp)
                mtx_lock(&Giant);

        IN_MULTI_LOCK();
        IGMP_LOCK();

        /*
         * IGMPv3 General Query response timer processing.
         */
        if (V_interface_timers_running) {
                CTR1(KTR_IGMPV3, "%s: interface timers running", __func__);

                V_interface_timers_running = 0;
                LIST_FOREACH(igi, &V_igi_head, igi_link) {
                        if (igi->igi_v3_timer == 0) {
                                /* Do nothing. */
                        } else if (--igi->igi_v3_timer == 0) {
                                igmp_v3_dispatch_general_query(igi);
                        } else {
                                V_interface_timers_running = 1;
                        }
                }
        }

        if (!V_current_state_timers_running &&
            !V_state_change_timers_running)
                goto out_locked;

        V_current_state_timers_running = 0;
        V_state_change_timers_running = 0;

        CTR1(KTR_IGMPV3, "%s: state change timers running", __func__);

        /*
         * IGMPv1/v2/v3 host report and state-change timer processing.
         * Note: Processing a v3 group timer may remove a node.
         */
        LIST_FOREACH(igi, &V_igi_head, igi_link) {
                ifp = igi->igi_ifp;

                if (igi->igi_version == IGMP_VERSION_3) {
                        loop = (igi->igi_flags & IGIF_LOOPBACK) ? 1 : 0;
                        uri_fasthz = IGMP_RANDOM_DELAY(igi->igi_uri *
                            PR_FASTHZ);

                        memset(&qrq, 0, sizeof(struct ifqueue));
                        IFQ_SET_MAXLEN(&qrq, IGMP_MAX_G_GS_PACKETS);

                        memset(&scq, 0, sizeof(struct ifqueue));
                        IFQ_SET_MAXLEN(&scq, IGMP_MAX_STATE_CHANGE_PACKETS);
                }

                IF_ADDR_LOCK(ifp);
                TAILQ_FOREACH_SAFE(ifma, &ifp->if_multiaddrs, ifma_link,
                    tifma) {
                        if (ifma->ifma_addr->sa_family != AF_INET ||
                            ifma->ifma_protospec == NULL)
                                continue;
                        inm = (struct in_multi *)ifma->ifma_protospec;
                        switch (igi->igi_version) {
                        case IGMP_VERSION_1:
                        case IGMP_VERSION_2:
                                igmp_v1v2_process_group_timer(inm,
                                    igi->igi_version);
                                break;
                        case IGMP_VERSION_3:
                                igmp_v3_process_group_timers(igi, &qrq,
                                    &scq, inm, uri_fasthz);
                                break;
                        }
                }
                IF_ADDR_UNLOCK(ifp);

                if (igi->igi_version == IGMP_VERSION_3) {
                        struct in_multi         *tinm;

                        igmp_dispatch_queue(&qrq, 0, loop);
                        igmp_dispatch_queue(&scq, 0, loop);

                        /*
                         * Free the in_multi reference(s) for this
                         * IGMP lifecycle.
                         */
                        SLIST_FOREACH_SAFE(inm, &igi->igi_relinmhead,
                            inm_nrele, tinm) {
                                SLIST_REMOVE_HEAD(&igi->igi_relinmhead,
                                    inm_nrele);
                                inm_release_locked(inm);
                        }
                }
        }

out_locked:
        IGMP_UNLOCK();
        IN_MULTI_UNLOCK();
        if (!mpsafe_igmp)
                mtx_unlock(&Giant);
}

/*
 * Update host report group timer for IGMPv1/v2.
 * Will update the global pending timer flags.
 */
static void
igmp_v1v2_process_group_timer(struct in_multi *inm, const int version)
{
        int report_timer_expired;

        IN_MULTI_LOCK_ASSERT();
        IGMP_LOCK_ASSERT();

        if (inm->inm_timer == 0) {
                report_timer_expired = 0;
        } else if (--inm->inm_timer == 0) {
                report_timer_expired = 1;
        } else {
                V_current_state_timers_running = 1;
                return;
        }

        switch (inm->inm_state) {
        case IGMP_NOT_MEMBER:
        case IGMP_SILENT_MEMBER:
        case IGMP_IDLE_MEMBER:
        case IGMP_LAZY_MEMBER:
        case IGMP_SLEEPING_MEMBER:
        case IGMP_AWAKENING_MEMBER:
                break;
        case IGMP_REPORTING_MEMBER:
                if (report_timer_expired) {
                        inm->inm_state = IGMP_IDLE_MEMBER;
                        (void)igmp_v1v2_queue_report(inm,
                            (version == IGMP_VERSION_2) ?
                             IGMP_v2_HOST_MEMBERSHIP_REPORT :
                             IGMP_v1_HOST_MEMBERSHIP_REPORT);
                }
                break;
        case IGMP_G_QUERY_PENDING_MEMBER:
        case IGMP_SG_QUERY_PENDING_MEMBER:
        case IGMP_LEAVING_MEMBER:
                break;
        }
}

/*
 * Update a group's timers for IGMPv3.
 * Will update the global pending timer flags.
 * Note: Unlocked read from igi.
 */
static void
igmp_v3_process_group_timers(struct igmp_ifinfo *igi,
    struct ifqueue *qrq, struct ifqueue *scq,
    struct in_multi *inm, const int uri_fasthz)
{
        int query_response_timer_expired;
        int state_change_retransmit_timer_expired;

        IN_MULTI_LOCK_ASSERT();
        IGMP_LOCK_ASSERT();

        query_response_timer_expired = 0;
        state_change_retransmit_timer_expired = 0;

        /*
         * During a transition from v1/v2 compatibility mode back to v3,
         * a group record in REPORTING state may still have its group
         * timer active. This is a no-op in this function; it is easier
         * to deal with it here than to complicate the slow-timeout path.
         */
        if (inm->inm_timer == 0) {
                query_response_timer_expired = 0;
        } else if (--inm->inm_timer == 0) {
                query_response_timer_expired = 1;
        } else {
                V_current_state_timers_running = 1;
        }

        if (inm->inm_sctimer == 0) {
                state_change_retransmit_timer_expired = 0;
        } else if (--inm->inm_sctimer == 0) {
                state_change_retransmit_timer_expired = 1;
        } else {
                V_state_change_timers_running = 1;
        }

        /* We are in fasttimo, so be quick about it. */
        if (!state_change_retransmit_timer_expired &&
            !query_response_timer_expired)
                return;

        switch (inm->inm_state) {
        case IGMP_NOT_MEMBER:
        case IGMP_SILENT_MEMBER:
        case IGMP_SLEEPING_MEMBER:
        case IGMP_LAZY_MEMBER:
        case IGMP_AWAKENING_MEMBER:
        case IGMP_IDLE_MEMBER:
                break;
        case IGMP_G_QUERY_PENDING_MEMBER:
        case IGMP_SG_QUERY_PENDING_MEMBER:
                /*
                 * Respond to a previously pending Group-Specific
                 * or Group-and-Source-Specific query by enqueueing
                 * the appropriate Current-State report for
                 * immediate transmission.
                 */
                if (query_response_timer_expired) {
                        int retval;

                        retval = igmp_v3_enqueue_group_record(qrq, inm, 0, 1,
                            (inm->inm_state == IGMP_SG_QUERY_PENDING_MEMBER));
                        CTR2(KTR_IGMPV3, "%s: enqueue record = %d",
                            __func__, retval);
                        inm->inm_state = IGMP_REPORTING_MEMBER;
                        /* XXX Clear recorded sources for next time. */
                        inm_clear_recorded(inm);
                }
                /* FALLTHROUGH */
        case IGMP_REPORTING_MEMBER:
        case IGMP_LEAVING_MEMBER:
                if (state_change_retransmit_timer_expired) {
                        /*
                         * State-change retransmission timer fired.
                         * If there are any further pending retransmissions,
                         * set the global pending state-change flag, and
                         * reset the timer.
                         */
                        if (--inm->inm_scrv > 0) {
                                inm->inm_sctimer = uri_fasthz;
                                V_state_change_timers_running = 1;
                        }
                        /*
                         * Retransmit the previously computed state-change
                         * report. If there are no further pending
                         * retransmissions, the mbuf queue will be consumed.
                         * Update T0 state to T1 as we have now sent
                         * a state-change.
                         */
                        (void)igmp_v3_merge_state_changes(inm, scq);

                        inm_commit(inm);
                        CTR3(KTR_IGMPV3, "%s: T1 -> T0 for %s/%s", __func__,
                            inet_ntoa(inm->inm_addr), inm->inm_ifp->if_xname);

                        /*
                         * If we are leaving the group for good, make sure
                         * we release IGMP's reference to it.
                         * This release must be deferred using a SLIST,
                         * as we are called from a loop which traverses
                         * the in_ifmultiaddr TAILQ.
                         */
                        if (inm->inm_state == IGMP_LEAVING_MEMBER &&
                            inm->inm_scrv == 0) {
                                inm->inm_state = IGMP_NOT_MEMBER;
                                SLIST_INSERT_HEAD(&igi->igi_relinmhead,
                                    inm, inm_nrele);
                        }
                }
                break;
        }
}


/*
 * Suppress a group's pending response to a group or source/group query.
 *
 * Do NOT suppress state changes. This leads to IGMPv3 inconsistency.
 * Do NOT update ST1/ST0 as this operation merely suppresses
 * the currently pending group record.
 * Do NOT suppress the response to a general query. It is possible but
 * it would require adding another state or flag.
 */
static void
igmp_v3_suppress_group_record(struct in_multi *inm)
{

        IN_MULTI_LOCK_ASSERT();

        KASSERT(inm->inm_igi->igi_version == IGMP_VERSION_3,
                ("%s: not IGMPv3 mode on link", __func__));

        if (inm->inm_state != IGMP_G_QUERY_PENDING_MEMBER ||
            inm->inm_state != IGMP_SG_QUERY_PENDING_MEMBER)
                return;

        if (inm->inm_state == IGMP_SG_QUERY_PENDING_MEMBER)
                inm_clear_recorded(inm);

        inm->inm_timer = 0;
        inm->inm_state = IGMP_REPORTING_MEMBER;
}

/*
 * Switch to a different IGMP version on the given interface,
 * as per Section 7.2.1.
 */
static void
igmp_set_version(struct igmp_ifinfo *igi, const int version)
{

        IGMP_LOCK_ASSERT();

        CTR4(KTR_IGMPV3, "%s: switching to v%d on ifp %p(%s)", __func__,
            version, igi->igi_ifp, igi->igi_ifp->if_xname);

        if (version == IGMP_VERSION_1 || version == IGMP_VERSION_2) {
                int old_version_timer;
                /*
                 * Compute the "Older Version Querier Present" timer as per
                 * Section 8.12.
                 */
                old_version_timer = igi->igi_rv * igi->igi_qi + igi->igi_qri;
                old_version_timer *= PR_SLOWHZ;

                if (version == IGMP_VERSION_1) {
                        igi->igi_v1_timer = old_version_timer;
                        igi->igi_v2_timer = 0;
                } else if (version == IGMP_VERSION_2) {
                        igi->igi_v1_timer = 0;
                        igi->igi_v2_timer = old_version_timer;
                }
        }

        if (igi->igi_v1_timer == 0 && igi->igi_v2_timer > 0) {
                if (igi->igi_version != IGMP_VERSION_2) {
                        igi->igi_version = IGMP_VERSION_2;
                        igmp_v3_cancel_link_timers(igi);
                }
        } else if (igi->igi_v1_timer > 0) {
                if (igi->igi_version != IGMP_VERSION_1) {
                        igi->igi_version = IGMP_VERSION_1;
                        igmp_v3_cancel_link_timers(igi);
                }
        }
}

/*
 * Cancel pending IGMPv3 timers for the given link and all groups
 * joined on it; state-change, general-query, and group-query timers.
 */
static void
igmp_v3_cancel_link_timers(struct igmp_ifinfo *igi)
{
        struct ifmultiaddr      *ifma;
        struct ifnet            *ifp;
        struct in_multi         *inm;

        CTR3(KTR_IGMPV3, "%s: cancel v3 timers on ifp %p(%s)", __func__,
            igi->igi_ifp, igi->igi_ifp->if_xname);

        IN_MULTI_LOCK_ASSERT();
        IGMP_LOCK_ASSERT();

        /*
         * Fast-track this potentially expensive operation
         * by checking all the global 'timer pending' flags.
         */
        if (!V_interface_timers_running &&
            !V_state_change_timers_running &&
            !V_current_state_timers_running)
                return;

        igi->igi_v3_timer = 0;

        ifp = igi->igi_ifp;

        IF_ADDR_LOCK(ifp);
        TAILQ_FOREACH(ifma, &ifp->if_multiaddrs, ifma_link) {
                if (ifma->ifma_addr->sa_family != AF_INET)
                        continue;
                inm = (struct in_multi *)ifma->ifma_protospec;
                switch (inm->inm_state) {
                case IGMP_NOT_MEMBER:
                case IGMP_SILENT_MEMBER:
                case IGMP_IDLE_MEMBER:
                case IGMP_LAZY_MEMBER:
                case IGMP_SLEEPING_MEMBER:
                case IGMP_AWAKENING_MEMBER:
                        break;
                case IGMP_LEAVING_MEMBER:
                        /*
                         * If we are leaving the group and switching
                         * IGMP version, we need to release the final
                         * reference held for issuing the INCLUDE {}.
                         *
                         * SMPNG: Must drop and re-acquire IF_ADDR_LOCK
                         * around inm_release_locked(), as it is not
                         * a recursive mutex.
                         */
                        IF_ADDR_UNLOCK(ifp);
                        inm_release_locked(inm);
                        IF_ADDR_LOCK(ifp);
                        /* FALLTHROUGH */
                case IGMP_G_QUERY_PENDING_MEMBER:
                case IGMP_SG_QUERY_PENDING_MEMBER:
                        inm_clear_recorded(inm);
                        /* FALLTHROUGH */
                case IGMP_REPORTING_MEMBER:
                        inm->inm_sctimer = 0;
                        inm->inm_timer = 0;
                        inm->inm_state = IGMP_REPORTING_MEMBER;
                        /*
                         * Free any pending IGMPv3 state-change records.
                         */
                        _IF_DRAIN(&inm->inm_scq);
                        break;
                }
        }
        IF_ADDR_UNLOCK(ifp);
}

/*
 * Update the Older Version Querier Present timers for a link.
 * See Section 7.2.1 of RFC 3376.
 */
static void
igmp_v1v2_process_querier_timers(struct igmp_ifinfo *igi)
{

        IGMP_LOCK_ASSERT();

        if (igi->igi_v1_timer == 0 && igi->igi_v2_timer == 0) {
                /*
                 * IGMPv1 and IGMPv2 Querier Present timers expired.
                 *
                 * Revert to IGMPv3.
                 */
                if (igi->igi_version != IGMP_VERSION_3) {
                        CTR5(KTR_IGMPV3,
                            "%s: transition from v%d -> v%d on %p(%s)",
                            __func__, igi->igi_version, IGMP_VERSION_3,
                            igi->igi_ifp, igi->igi_ifp->if_xname);
                        igi->igi_version = IGMP_VERSION_3;
                }
        } else if (igi->igi_v1_timer == 0 && igi->igi_v2_timer > 0) {
                /*
                 * IGMPv1 Querier Present timer expired,
                 * IGMPv2 Querier Present timer running.
                 * If IGMPv2 was disabled since last timeout,
                 * revert to IGMPv3.
                 * If IGMPv2 is enabled, revert to IGMPv2.
                 */
                if (!V_igmp_v2enable) {
                        CTR5(KTR_IGMPV3,
                            "%s: transition from v%d -> v%d on %p(%s)",
                            __func__, igi->igi_version, IGMP_VERSION_3,
                            igi->igi_ifp, igi->igi_ifp->if_xname);
                        igi->igi_v2_timer = 0;
                        igi->igi_version = IGMP_VERSION_3;
                } else {
                        --igi->igi_v2_timer;
                        if (igi->igi_version != IGMP_VERSION_2) {
                                CTR5(KTR_IGMPV3,
                                    "%s: transition from v%d -> v%d on %p(%s)",
                                    __func__, igi->igi_version, IGMP_VERSION_2,
                                    igi->igi_ifp, igi->igi_ifp->if_xname);
                                igi->igi_version = IGMP_VERSION_2;
                        }
                }
        } else if (igi->igi_v1_timer > 0) {
                /*
                 * IGMPv1 Querier Present timer running.
                 * Stop IGMPv2 timer if running.
                 *
                 * If IGMPv1 was disabled since last timeout,
                 * revert to IGMPv3.
                 * If IGMPv1 is enabled, reset IGMPv2 timer if running.
                 */
                if (!V_igmp_v1enable) {
                        CTR5(KTR_IGMPV3,
                            "%s: transition from v%d -> v%d on %p(%s)",
                            __func__, igi->igi_version, IGMP_VERSION_3,
                            igi->igi_ifp, igi->igi_ifp->if_xname);
                        igi->igi_v1_timer = 0;
                        igi->igi_version = IGMP_VERSION_3;
                } else {
                        --igi->igi_v1_timer;
                }
                if (igi->igi_v2_timer > 0) {
                        CTR3(KTR_IGMPV3,
                            "%s: cancel v2 timer on %p(%s)",
                            __func__, igi->igi_ifp, igi->igi_ifp->if_xname);
                        igi->igi_v2_timer = 0;
                }
        }
}

/*
 * Global slowtimo handler.
 * VIMAGE: Timeout handlers are expected to service all vimages.
 */
void
igmp_slowtimo(void)
{
#ifdef VIMAGE
        VNET_ITERATOR_DECL(vnet_iter);

        VNET_LIST_RLOCK();
        VNET_FOREACH(vnet_iter) {
                CURVNET_SET(vnet_iter);
                INIT_VNET_INET(vnet_iter);
                igmp_slowtimo_vnet();
                CURVNET_RESTORE();
        }
        VNET_LIST_RUNLOCK();
#else /* !VIMAGE */
        igmp_slowtimo_vnet();
#endif /* VIMAGE */
}

/*
 * Per-vnet slowtimo handler.
 */
static void
igmp_slowtimo_vnet(void)
{
        struct igmp_ifinfo *igi;

        IGMP_LOCK();

        LIST_FOREACH(igi, &V_igi_head, igi_link) {
                igmp_v1v2_process_querier_timers(igi);
        }

        IGMP_UNLOCK();
}

/*
 * Dispatch an IGMPv1/v2 host report or leave message.
 * 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 ifnet            *ifp;
        struct igmp             *igmp;
        struct ip               *ip;
        struct mbuf             *m;

        IN_MULTI_LOCK_ASSERT();
        IGMP_LOCK_ASSERT();

        ifp = inm->inm_ifp;
        /* XXX are these needed ? */
        INIT_VNET_NET(ifp->if_vnet);
        INIT_VNET_INET(ifp->if_vnet);

        MGETHDR(m, M_DONTWAIT, MT_DATA);
        if (m == NULL)
                return (ENOMEM);
        MH_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 = 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);
        netisr_dispatch(NETISR_IGMP, m);

        return (0);
}

/*
 * Process a state change from the upper layer for the given IPv4 group.
 *
 * Each socket holds a reference on the in_multi in its own ip_moptions.
 * The socket layer will have made the necessary updates to.the group
 * state, it is now up to IGMP to issue a state change report if there
 * has been any change between T0 (when the last state-change was issued)
 * and T1 (now).
 *
 * We use the IGMPv3 state machine at group level. The IGMP module
 * however makes the decision as to which IGMP protocol version to speak.
 * A state change *from* INCLUDE {} always means an initial join.
 * A state change *to* INCLUDE {} always means a final leave.
 *
 * FUTURE: If IGIF_V3LITE is enabled for this interface, then we can
 * save ourselves a bunch of work; any exclusive mode groups need not
 * compute source filter lists.
 *
 * VIMAGE: curvnet should have been set by caller, as this routine
 * is called from the socket option handlers.
 */
int
igmp_change_state(struct in_multi *inm)
{
        struct igmp_ifinfo *igi;
        struct ifnet *ifp;
        int error;

        IN_MULTI_LOCK_ASSERT();

        error = 0;

        /*
         * Try to detect if the upper layer just asked us to change state
         * for an interface which has now gone away.
         */
        KASSERT(inm->inm_ifma != NULL, ("%s: no ifma", __func__));
        ifp = inm->inm_ifma->ifma_ifp;
        if (ifp != NULL) {
                /*
                 * Sanity check that netinet's notion of ifp is the
                 * same as net's.
                 */
                KASSERT(inm->inm_ifp == ifp, ("%s: bad ifp", __func__));
        }

        IGMP_LOCK();

        igi = ((struct in_ifinfo *)ifp->if_afdata[AF_INET])->ii_igmp;
        KASSERT(igi != NULL, ("%s: no igmp_ifinfo for ifp %p", __func__, ifp));

        /*
         * If we detect a state transition to or from MCAST_UNDEFINED
         * for this group, then we are starting or finishing an IGMP
         * life cycle for this group.
         */
        if (inm->inm_st[1].iss_fmode != inm->inm_st[0].iss_fmode) {
                CTR3(KTR_IGMPV3, "%s: inm transition %d -> %d", __func__,
                    inm->inm_st[0].iss_fmode, inm->inm_st[1].iss_fmode);
                if (inm->inm_st[0].iss_fmode == MCAST_UNDEFINED) {
                        CTR1(KTR_IGMPV3, "%s: initial join", __func__);
                        error = igmp_initial_join(inm, igi);
                        goto out_locked;
                } else if (inm->inm_st[1].iss_fmode == MCAST_UNDEFINED) {
                        CTR1(KTR_IGMPV3, "%s: final leave", __func__);
                        igmp_final_leave(inm, igi);
                        goto out_locked;
                }
        } else {
                CTR1(KTR_IGMPV3, "%s: filter set change", __func__);
        }

        error = igmp_handle_state_change(inm, igi);

out_locked:
        IGMP_UNLOCK();
        return (error);
}

/*
 * Perform the initial join for an IGMP group.
 *
 * When joining a group:
 *  If the group should have its IGMP traffic suppressed, do nothing.
 *  IGMPv1 starts sending IGMPv1 host membership reports.
 *  IGMPv2 starts sending IGMPv2 host membership reports.
 *  IGMPv3 will schedule an IGMPv3 state-change report containing the
 *  initial state of the membership.
 */
static int
igmp_initial_join(struct in_multi *inm, struct igmp_ifinfo *igi)
{
        struct ifnet            *ifp;
        struct ifqueue          *ifq;
        int                      error, retval, syncstates;

        CTR4(KTR_IGMPV3, "%s: initial join %s on ifp %p(%s)",
            __func__, inet_ntoa(inm->inm_addr), inm->inm_ifp,
            inm->inm_ifp->if_xname);

        error = 0;
        syncstates = 1;

        ifp = inm->inm_ifp;

        IN_MULTI_LOCK_ASSERT();
        IGMP_LOCK_ASSERT();

        KASSERT(igi && igi->igi_ifp == ifp, ("%s: inconsistent ifp", __func__));

        /*
         * Groups joined on loopback or marked as 'not reported',
         * e.g. 224.0.0.1, enter the IGMP_SILENT_MEMBER state and
         * are never reported in any IGMP protocol exchanges.
         * All other groups enter the appropriate IGMP state machine
         * for the version in use on this link.
         * A link marked as IGIF_SILENT causes IGMP to be completely
         * disabled for the link.
         */
        if ((ifp->if_flags & IFF_LOOPBACK) ||
            (igi->igi_flags & IGIF_SILENT) ||
            !igmp_isgroupreported(inm->inm_addr)) {
                CTR1(KTR_IGMPV3,
"%s: not kicking state machine for silent group", __func__);
                inm->inm_state = IGMP_SILENT_MEMBER;
                inm->inm_timer = 0;
        } else {
                /*
                 * Deal with overlapping in_multi lifecycle.
                 * If this group was LEAVING, then make sure
                 * we drop the reference we picked up to keep the
                 * group around for the final INCLUDE {} enqueue.
                 */
                if (igi->igi_version == IGMP_VERSION_3 &&
                    inm->inm_state == IGMP_LEAVING_MEMBER)
                        inm_release_locked(inm);

                inm->inm_state = IGMP_REPORTING_MEMBER;

                switch (igi->igi_version) {
                case IGMP_VERSION_1:
                case IGMP_VERSION_2:
                        inm->inm_state = IGMP_IDLE_MEMBER;
                        error = igmp_v1v2_queue_report(inm,
                            (igi->igi_version == IGMP_VERSION_2) ?
                             IGMP_v2_HOST_MEMBERSHIP_REPORT :
                             IGMP_v1_HOST_MEMBERSHIP_REPORT);
                        if (error == 0) {
                                inm->inm_timer = IGMP_RANDOM_DELAY(
                                    IGMP_V1V2_MAX_RI * PR_FASTHZ);
                                V_current_state_timers_running = 1;
                        }
                        break;

                case IGMP_VERSION_3:
                        /*
                         * Defer update of T0 to T1, until the first copy
                         * of the state change has been transmitted.
                         */
                        syncstates = 0;

                        /*
                         * Immediately enqueue a State-Change Report for
                         * this interface, freeing any previous reports.
                         * Don't kick the timers if there is nothing to do,
                         * or if an error occurred.
                         */
                        ifq = &inm->inm_scq;
                        _IF_DRAIN(ifq);
                        retval = igmp_v3_enqueue_group_record(ifq, inm, 1,
                            0, 0);
                        CTR2(KTR_IGMPV3, "%s: enqueue record = %d",
                            __func__, retval);
                        if (retval <= 0) {
                                error = retval * -1;
                                break;
                        }

                        /*
                         * Schedule transmission of pending state-change
                         * report up to RV times for this link. The timer
                         * will fire at the next igmp_fasttimo (~200ms),
                         * giving us an opportunity to merge the reports.
                         */
                        if (igi->igi_flags & IGIF_LOOPBACK) {
                                inm->inm_scrv = 1;
                        } else {
                                KASSERT(igi->igi_rv > 1,
                                   ("%s: invalid robustness %d", __func__,
                                    igi->igi_rv));
                                inm->inm_scrv = igi->igi_rv;
                        }
                        inm->inm_sctimer = 1;
                        V_state_change_timers_running = 1;

                        error = 0;
                        break;
                }
        }

        /*
         * Only update the T0 state if state change is atomic,
         * i.e. we don't need to wait for a timer to fire before we
         * can consider the state change to have been communicated.
         */
        if (syncstates) {
                inm_commit(inm);
                CTR3(KTR_IGMPV3, "%s: T1 -> T0 for %s/%s", __func__,
                    inet_ntoa(inm->inm_addr), inm->inm_ifp->if_xname);
        }

        return (error);
}

/*
 * Issue an intermediate state change during the IGMP life-cycle.
 */
static int
igmp_handle_state_change(struct in_multi *inm, struct igmp_ifinfo *igi)
{
        struct ifnet            *ifp;
        int                      retval;

        CTR4(KTR_IGMPV3, "%s: state change for %s on ifp %p(%s)",
            __func__, inet_ntoa(inm->inm_addr), inm->inm_ifp,
            inm->inm_ifp->if_xname);

        ifp = inm->inm_ifp;

        IN_MULTI_LOCK_ASSERT();
        IGMP_LOCK_ASSERT();

        KASSERT(igi && igi->igi_ifp == ifp, ("%s: inconsistent ifp", __func__));

        if ((ifp->if_flags & IFF_LOOPBACK) ||
            (igi->igi_flags & IGIF_SILENT) ||
            !igmp_isgroupreported(inm->inm_addr) ||
            (igi->igi_version != IGMP_VERSION_3)) {
                if (!igmp_isgroupreported(inm->inm_addr)) {
                        CTR1(KTR_IGMPV3,
"%s: not kicking state machine for silent group", __func__);
                }
                CTR1(KTR_IGMPV3, "%s: nothing to do", __func__);
                inm_commit(inm);
                CTR3(KTR_IGMPV3, "%s: T1 -> T0 for %s/%s", __func__,
                    inet_ntoa(inm->inm_addr), inm->inm_ifp->if_xname);
                return (0);
        }

        _IF_DRAIN(&inm->inm_scq);

        retval = igmp_v3_enqueue_group_record(&inm->inm_scq, inm, 1, 0, 0);
        CTR2(KTR_IGMPV3, "%s: enqueue record = %d", __func__, retval);
        if (retval <= 0)
                return (-retval);

        /*
         * If record(s) were enqueued, start the state-change
         * report timer for this group.
         */
        inm->inm_scrv = ((igi->igi_flags & IGIF_LOOPBACK) ? 1 : igi->igi_rv);
        inm->inm_sctimer = 1;
        V_state_change_timers_running = 1;

        return (0);
}

/*
 * Perform the final leave for an IGMP group.
 *
 * When leaving a group:
 *  IGMPv1 does nothing.
 *  IGMPv2 sends a host leave message, if and only if we are the reporter.
 *  IGMPv3 enqueues a state-change report containing a transition
 *  to INCLUDE {} for immediate transmission.
 */
static void
igmp_final_leave(struct in_multi *inm, struct igmp_ifinfo *igi)
{
        int syncstates;

        syncstates = 1;

        CTR4(KTR_IGMPV3, "%s: final leave %s on ifp %p(%s)",
            __func__, inet_ntoa(inm->inm_addr), inm->inm_ifp,
            inm->inm_ifp->if_xname);

        IN_MULTI_LOCK_ASSERT();
        IGMP_LOCK_ASSERT();

        switch (inm->inm_state) {
        case IGMP_NOT_MEMBER:
        case IGMP_SILENT_MEMBER:
        case IGMP_LEAVING_MEMBER:
                /* Already leaving or left; do nothing. */
                CTR1(KTR_IGMPV3,
"%s: not kicking state machine for silent group", __func__);
                break;
        case IGMP_REPORTING_MEMBER:
        case IGMP_IDLE_MEMBER:
        case IGMP_G_QUERY_PENDING_MEMBER:
        case IGMP_SG_QUERY_PENDING_MEMBER:
                if (igi->igi_version == IGMP_VERSION_2) {
#ifdef INVARIANTS
                        if (inm->inm_state == IGMP_G_QUERY_PENDING_MEMBER ||
                            inm->inm_state == IGMP_SG_QUERY_PENDING_MEMBER)
                        panic("%s: IGMPv3 state reached, not IGMPv3 mode",
                             __func__);
#endif
                        igmp_v1v2_queue_report(inm, IGMP_HOST_LEAVE_MESSAGE);
                        inm->inm_state = IGMP_NOT_MEMBER;
                } else if (igi->igi_version == IGMP_VERSION_3) {
                        /*
                         * Stop group timer and all pending reports.
                         * Immediately enqueue a state-change report
                         * TO_IN {} to be sent on the next fast timeout,
                         * giving us an opportunity to merge reports.
                         */
                        _IF_DRAIN(&inm->inm_scq);
                        inm->inm_timer = 0;
                        if (igi->igi_flags & IGIF_LOOPBACK) {
                                inm->inm_scrv = 1;
                        } else {
                                inm->inm_scrv = igi->igi_rv;
                        }
                        CTR4(KTR_IGMPV3, "%s: Leaving %s/%s with %d "
                            "pending retransmissions.", __func__,
                            inet_ntoa(inm->inm_addr),
                            inm->inm_ifp->if_xname, inm->inm_scrv);
                        if (inm->inm_scrv == 0) {
                                inm->inm_state = IGMP_NOT_MEMBER;
                                inm->inm_sctimer = 0;
                        } else {
                                int retval;

                                inm_acquire_locked(inm);

                                retval = igmp_v3_enqueue_group_record(
                                    &inm->inm_scq, inm, 1, 0, 0);
                                KASSERT(retval != 0,
                                    ("%s: enqueue record = %d", __func__,
                                     retval));

                                inm->inm_state = IGMP_LEAVING_MEMBER;
                                inm->inm_sctimer = 1;
                                V_state_change_timers_running = 1;
                                syncstates = 0;
                        }
                        break;
                }
                break;
        case IGMP_LAZY_MEMBER:
        case IGMP_SLEEPING_MEMBER:
        case IGMP_AWAKENING_MEMBER:
                /* Our reports are suppressed; do nothing. */
                break;
        }

        if (syncstates) {
                inm_commit(inm);
                CTR3(KTR_IGMPV3, "%s: T1 -> T0 for %s/%s", __func__,
                    inet_ntoa(inm->inm_addr), inm->inm_ifp->if_xname);
                inm->inm_st[1].iss_fmode = MCAST_UNDEFINED;
                CTR3(KTR_IGMPV3, "%s: T1 now MCAST_UNDEFINED for %s/%s",
                    __func__, inet_ntoa(inm->inm_addr), inm->inm_ifp->if_xname);
        }
}

/*
 * Enqueue an IGMPv3 group record to the given output queue.
 *
 * XXX This function could do with having the allocation code
 * split out, and the multiple-tree-walks coalesced into a single
 * routine as has been done in igmp_v3_enqueue_filter_change().
 *
 * If is_state_change is zero, a current-state record is appended.
 * If is_state_change is non-zero, a state-change report is appended.
 *
 * If is_group_query is non-zero, an mbuf packet chain is allocated.
 * If is_group_query is zero, and if there is a packet with free space
 * at the tail of the queue, it will be appended to providing there
 * is enough free space.
 * Otherwise a new mbuf packet chain is allocated.
 *
 * If is_source_query is non-zero, each source is checked to see if
 * it was recorded for a Group-Source query, and will be omitted if
 * it is not both in-mode and recorded.
 *
 * The function will attempt to allocate leading space in the packet
 * for the IP/IGMP header to be prepended without fragmenting the chain.
 *
 * If successful the size of all data appended to the queue is returned,
 * otherwise an error code less than zero is returned, or zero if
 * no record(s) were appended.
 */
static int
igmp_v3_enqueue_group_record(struct ifqueue *ifq, struct in_multi *inm,
    const int is_state_change, const int is_group_query,
    const int is_source_query)
{
        struct igmp_grouprec     ig;
        struct igmp_grouprec    *pig;
        struct ifnet            *ifp;
        struct ip_msource       *ims, *nims;
        struct mbuf             *m0, *m, *md;
        int                      error, is_filter_list_change;
        int                      minrec0len, m0srcs, msrcs, nbytes, off;
        int                      record_has_sources;
        int                      now;
        int                      type;
        in_addr_t                naddr;
        uint8_t                  mode;

        IN_MULTI_LOCK_ASSERT();

        error = 0;
        ifp = inm->inm_ifp;
        is_filter_list_change = 0;
        m = NULL;
        m0 = NULL;
        m0srcs = 0;
        msrcs = 0;
        nbytes = 0;
        nims = NULL;
        record_has_sources = 1;
        pig = NULL;
        type = IGMP_DO_NOTHING;
        mode = inm->inm_st[1].iss_fmode;

        /*
         * If we did not transition out of ASM mode during t0->t1,
         * and there are no source nodes to process, we can skip
         * the generation of source records.
         */
        if (inm->inm_st[0].iss_asm > 0 && inm->inm_st[1].iss_asm > 0 &&
            inm->inm_nsrc == 0)
                record_has_sources = 0;

        if (is_state_change) {
                /*
                 * Queue a state change record.
                 * If the mode did not change, and there are non-ASM
                 * listeners or source filters present,
                 * we potentially need to issue two records for the group.
                 * If we are transitioning to MCAST_UNDEFINED, we need
                 * not send any sources.
                 * If there are ASM listeners, and there was no filter
                 * mode transition of any kind, do nothing.
                 */
                if (mode != inm->inm_st[0].iss_fmode) {
                        if (mode == MCAST_EXCLUDE) {
                                CTR1(KTR_IGMPV3, "%s: change to EXCLUDE",
                                    __func__);
                                type = IGMP_CHANGE_TO_EXCLUDE_MODE;
                        } else {
                                CTR1(KTR_IGMPV3, "%s: change to INCLUDE",
                                    __func__);
                                type = IGMP_CHANGE_TO_INCLUDE_MODE;
                                if (mode == MCAST_UNDEFINED)
                                        record_has_sources = 0;
                        }
                } else {
                        if (record_has_sources) {
                                is_filter_list_change = 1;
                        } else {
                                type = IGMP_DO_NOTHING;
                        }
                }
        } else {
                /*
                 * Queue a current state record.
                 */
                if (mode == MCAST_EXCLUDE) {
                        type = IGMP_MODE_IS_EXCLUDE;
                } else if (mode == MCAST_INCLUDE) {
                        type = IGMP_MODE_IS_INCLUDE;
                        KASSERT(inm->inm_st[1].iss_asm == 0,
                            ("%s: inm %p is INCLUDE but ASM count is %d",
                             __func__, inm, inm->inm_st[1].iss_asm));
                }
        }

        /*
         * Generate the filter list changes using a separate function.
         */
        if (is_filter_list_change)
                return (igmp_v3_enqueue_filter_change(ifq, inm));

        if (type == IGMP_DO_NOTHING) {
                CTR3(KTR_IGMPV3, "%s: nothing to do for %s/%s",
                    __func__, inet_ntoa(inm->inm_addr),
                    inm->inm_ifp->if_xname);
                return (0);
        }

        /*
         * If any sources are present, we must be able to fit at least
         * one in the trailing space of the tail packet's mbuf,
         * ideally more.
         */
        minrec0len = sizeof(struct igmp_grouprec);
        if (record_has_sources)
                minrec0len += sizeof(in_addr_t);

        CTR4(KTR_IGMPV3, "%s: queueing %s for %s/%s", __func__,
            igmp_rec_type_to_str(type), inet_ntoa(inm->inm_addr),
            inm->inm_ifp->if_xname);

        /*
         * Check if we have a packet in the tail of the queue for this
         * group into which the first group record for this group will fit.
         * Otherwise allocate a new packet.
         * Always allocate leading space for IP+RA_OPT+IGMP+REPORT.
         * Note: Group records for G/GSR query responses MUST be sent
         * in their own packet.
         */
        m0 = ifq->ifq_tail;
        if (!is_group_query &&
            m0 != NULL &&
            (m0->m_pkthdr.PH_vt.vt_nrecs + 1 <= IGMP_V3_REPORT_MAXRECS) &&
            (m0->m_pkthdr.len + minrec0len) <
             (ifp->if_mtu - IGMP_LEADINGSPACE)) {
                m0srcs = (ifp->if_mtu - m0->m_pkthdr.len -
                            sizeof(struct igmp_grouprec)) / sizeof(in_addr_t);
                m = m0;
                CTR1(KTR_IGMPV3, "%s: use existing packet", __func__);
        } else {
                if (_IF_QFULL(ifq)) {
                        CTR1(KTR_IGMPV3, "%s: outbound queue full", __func__);
                        return (-ENOMEM);
                }
                m = NULL;
                m0srcs = (ifp->if_mtu - IGMP_LEADINGSPACE -
                    sizeof(struct igmp_grouprec)) / sizeof(in_addr_t);
                if (!is_state_change && !is_group_query)
                        m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
                if (m == NULL) {
                        m = m_gethdr(M_DONTWAIT, MT_DATA);
                        if (m)
                                MH_ALIGN(m, IGMP_LEADINGSPACE);
                }
                if (m == NULL)
                        return (-ENOMEM);
                m->m_data += IGMP_LEADINGSPACE;

                igmp_save_context(m, ifp);

                CTR1(KTR_IGMPV3, "%s: allocated first packet", __func__);
        }

        /*
         * Append group record.
         * If we have sources, we don't know how many yet.
         */
        ig.ig_type = type;
        ig.ig_datalen = 0;
        ig.ig_numsrc = 0;
        ig.ig_group = inm->inm_addr;
        if (!m_append(m, sizeof(struct igmp_grouprec), (void *)&ig)) {
                if (m != m0)
                        m_freem(m);
                CTR1(KTR_IGMPV3, "%s: m_append() failed.", __func__);
                return (-ENOMEM);
        }
        nbytes += sizeof(struct igmp_grouprec);

        /*
         * Append as many sources as will fit in the first packet.
         * If we are appending to a new packet, the chain allocation
         * may potentially use clusters; use m_getptr() in this case.
         * If we are appending to an existing packet, we need to obtain
         * a pointer to the group record after m_append(), in case a new
         * mbuf was allocated.
         * Only append sources which are in-mode at t1. If we are
         * transitioning to MCAST_UNDEFINED state on the group, do not
         * include source entries.
         * Only report recorded sources in our filter set when responding
         * to a group-source query.
         */
        if (record_has_sources) {
                if (m == m0) {
                        md = m_last(m);
                        pig = (struct igmp_grouprec *)(mtod(md, uint8_t *) +
                            md->m_len - nbytes);
                } else {
                        md = m_getptr(m, 0, &off);
                        pig = (struct igmp_grouprec *)(mtod(md, uint8_t *) +
                            off);
                }
                msrcs = 0;
                RB_FOREACH_SAFE(ims, ip_msource_tree, &inm->inm_srcs, nims) {
                        CTR2(KTR_IGMPV3, "%s: visit node %s", __func__,
                            inet_ntoa_haddr(ims->ims_haddr));
                        now = ims_get_mode(inm, ims, 1);
                        CTR2(KTR_IGMPV3, "%s: node is %d", __func__, now);
                        if ((now != mode) ||
                            (now == mode && mode == MCAST_UNDEFINED)) {
                                CTR1(KTR_IGMPV3, "%s: skip node", __func__);
                                continue;
                        }
                        if (is_source_query && ims->ims_stp == 0) {
                                CTR1(KTR_IGMPV3, "%s: skip unrecorded node",
                                    __func__);
                                continue;
                        }
                        CTR1(KTR_IGMPV3, "%s: append node", __func__);
                        naddr = htonl(ims->ims_haddr);
                        if (!m_append(m, sizeof(in_addr_t), (void *)&naddr)) {
                                if (m != m0)
                                        m_freem(m);
                                CTR1(KTR_IGMPV3, "%s: m_append() failed.",
                                    __func__);
                                return (-ENOMEM);
                        }
                        nbytes += sizeof(in_addr_t);
                        ++msrcs;
                        if (msrcs == m0srcs)
                                break;
                }
                CTR2(KTR_IGMPV3, "%s: msrcs is %d this packet", __func__,
                    msrcs);
                pig->ig_numsrc = htons(msrcs);
                nbytes += (msrcs * sizeof(in_addr_t));
        }

        if (is_source_query && msrcs == 0) {
                CTR1(KTR_IGMPV3, "%s: no recorded sources to report", __func__);
                if (m != m0)
                        m_freem(m);
                return (0);
        }

        /*
         * We are good to go with first packet.
         */
        if (m != m0) {
                CTR1(KTR_IGMPV3, "%s: enqueueing first packet", __func__);
                m->m_pkthdr.PH_vt.vt_nrecs = 1;
                _IF_ENQUEUE(ifq, m);
        } else
                m->m_pkthdr.PH_vt.vt_nrecs++;

        /*
         * No further work needed if no source list in packet(s).
         */
        if (!record_has_sources)
                return (nbytes);

        /*
         * Whilst sources remain to be announced, we need to allocate
         * a new packet and fill out as many sources as will fit.
         * Always try for a cluster first.
         */
        while (nims != NULL) {
                if (_IF_QFULL(ifq)) {
                        CTR1(KTR_IGMPV3, "%s: outbound queue full", __func__);
                        return (-ENOMEM);
                }
                m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
                if (m == NULL) {
                        m = m_gethdr(M_DONTWAIT, MT_DATA);
                        if (m)
                                MH_ALIGN(m, IGMP_LEADINGSPACE);
                }
                if (m == NULL)
                        return (-ENOMEM);
                igmp_save_context(m, ifp);
                m->m_data += IGMP_LEADINGSPACE;
                md = m_getptr(m, 0, &off);
                pig = (struct igmp_grouprec *)(mtod(md, uint8_t *) + off);
                CTR1(KTR_IGMPV3, "%s: allocated next packet", __func__);

                if (!m_append(m, sizeof(struct igmp_grouprec), (void *)&ig)) {
                        if (m != m0)
                                m_freem(m);
                        CTR1(KTR_IGMPV3, "%s: m_append() failed.", __func__);
                        return (-ENOMEM);
                }
                m->m_pkthdr.PH_vt.vt_nrecs = 1;
                nbytes += sizeof(struct igmp_grouprec);

                m0srcs = (ifp->if_mtu - IGMP_LEADINGSPACE -
                    sizeof(struct igmp_grouprec)) / sizeof(in_addr_t);

                msrcs = 0;
                RB_FOREACH_FROM(ims, ip_msource_tree, nims) {
                        CTR2(KTR_IGMPV3, "%s: visit node %s", __func__,
                            inet_ntoa_haddr(ims->ims_haddr));
                        now = ims_get_mode(inm, ims, 1);
                        if ((now != mode) ||
                            (now == mode && mode == MCAST_UNDEFINED)) {
                                CTR1(KTR_IGMPV3, "%s: skip node", __func__);
                                continue;
                        }
                        if (is_source_query && ims->ims_stp == 0) {
                                CTR1(KTR_IGMPV3, "%s: skip unrecorded node",
                                    __func__);
                                continue;
                        }
                        CTR1(KTR_IGMPV3, "%s: append node", __func__);
                        naddr = htonl(ims->ims_haddr);
                        if (!m_append(m, sizeof(in_addr_t), (void *)&naddr)) {
                                if (m != m0)
                                        m_freem(m);
                                CTR1(KTR_IGMPV3, "%s: m_append() failed.",
                                    __func__);
                                return (-ENOMEM);
                        }
                        ++msrcs;
                        if (msrcs == m0srcs)
                                break;
                }
                pig->ig_numsrc = htons(msrcs);
                nbytes += (msrcs * sizeof(in_addr_t));

                CTR1(KTR_IGMPV3, "%s: enqueueing next packet", __func__);
                _IF_ENQUEUE(ifq, m);
        }

        return (nbytes);
}

/*
 * Type used to mark record pass completion.
 * We exploit the fact we can cast to this easily from the
 * current filter modes on each ip_msource node.
 */
typedef enum {
        REC_NONE = 0x00,        /* MCAST_UNDEFINED */
        REC_ALLOW = 0x01,       /* MCAST_INCLUDE */
        REC_BLOCK = 0x02,       /* MCAST_EXCLUDE */
        REC_FULL = REC_ALLOW | REC_BLOCK
} rectype_t;

/*
 * Enqueue an IGMPv3 filter list change to the given output queue.
 *
 * Source list filter state is held in an RB-tree. When the filter list
 * for a group is changed without changing its mode, we need to compute
 * the deltas between T0 and T1 for each source in the filter set,
 * and enqueue the appropriate ALLOW_NEW/BLOCK_OLD records.
 *
 * As we may potentially queue two record types, and the entire R-B tree
 * needs to be walked at once, we break this out into its own function
 * so we can generate a tightly packed queue of packets.
 *
 * XXX This could be written to only use one tree walk, although that makes
 * serializing into the mbuf chains a bit harder. For now we do two walks
 * which makes things easier on us, and it may or may not be harder on
 * the L2 cache.
 *
 * If successful the size of all data appended to the queue is returned,
 * otherwise an error code less than zero is returned, or zero if
 * no record(s) were appended.
 */
static int
igmp_v3_enqueue_filter_change(struct ifqueue *ifq, struct in_multi *inm)
{
        static const int MINRECLEN =
            sizeof(struct igmp_grouprec) + sizeof(in_addr_t);
        struct ifnet            *ifp;
        struct igmp_grouprec     ig;
        struct igmp_grouprec    *pig;
        struct ip_msource       *ims, *nims;
        struct mbuf             *m, *m0, *md;
        in_addr_t                naddr;
        int                      m0srcs, nbytes, off, rsrcs, schanged;
        int                      nallow, nblock;
        uint8_t                  mode, now, then;
        rectype_t                crt, drt, nrt;

        IN_MULTI_LOCK_ASSERT();

        if (inm->inm_nsrc == 0 ||
            (inm->inm_st[0].iss_asm > 0 && inm->inm_st[1].iss_asm > 0))
                return (0);

        ifp = inm->inm_ifp;                     /* interface */
        mode = inm->inm_st[1].iss_fmode;        /* filter mode at t1 */
        crt = REC_NONE; /* current group record type */
        drt = REC_NONE; /* mask of completed group record types */
        nrt = REC_NONE; /* record type for current node */
        m0srcs = 0;     /* # source which will fit in current mbuf chain */
        nbytes = 0;     /* # of bytes appended to group's state-change queue */
        rsrcs = 0;      /* # sources encoded in current record */
        schanged = 0;   /* # nodes encoded in overall filter change */
        nallow = 0;     /* # of source entries in ALLOW_NEW */
        nblock = 0;     /* # of source entries in BLOCK_OLD */
        nims = NULL;    /* next tree node pointer */

        /*
         * For each possible filter record mode.
         * The first kind of source we encounter tells us which
         * is the first kind of record we start appending.
         * If a node transitioned to UNDEFINED at t1, its mode is treated
         * as the inverse of the group's filter mode.
         */
        while (drt != REC_FULL) {
                do {
                        m0 = ifq->ifq_tail;
                        if (m0 != NULL &&
                            (m0->m_pkthdr.PH_vt.vt_nrecs + 1 <=
                             IGMP_V3_REPORT_MAXRECS) &&
                            (m0->m_pkthdr.len + MINRECLEN) <
                             (ifp->if_mtu - IGMP_LEADINGSPACE)) {
                                m = m0;
                                m0srcs = (ifp->if_mtu - m0->m_pkthdr.len -
                                            sizeof(struct igmp_grouprec)) /
                                    sizeof(in_addr_t);
                                CTR1(KTR_IGMPV3,
                                    "%s: use previous packet", __func__);
                        } else {
                                m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
                                if (m == NULL) {
                                        m = m_gethdr(M_DONTWAIT, MT_DATA);
                                        if (m)
                                                MH_ALIGN(m, IGMP_LEADINGSPACE);
                                }
                                if (m == NULL) {
                                        CTR1(KTR_IGMPV3,
                                            "%s: m_get*() failed", __func__);
                                        return (-ENOMEM);
                                }
                                m->m_pkthdr.PH_vt.vt_nrecs = 0;
                                igmp_save_context(m, ifp);
                                m->m_data += IGMP_LEADINGSPACE;
                                m0srcs = (ifp->if_mtu - IGMP_LEADINGSPACE -
                                    sizeof(struct igmp_grouprec)) /
                                    sizeof(in_addr_t);
                                CTR1(KTR_IGMPV3,
                                    "%s: allocated new packet", __func__);
                        }
                        /*
                         * Append the IGMP group record header to the
                         * current packet's data area.
                         * Recalculate pointer to free space for next
                         * group record, in case m_append() allocated
                         * a new mbuf or cluster.
                         */
                        memset(&ig, 0, sizeof(ig));
                        ig.ig_group = inm->inm_addr;
                        if (!m_append(m, sizeof(ig), (void *)&ig)) {
                                if (m != m0)
                                        m_freem(m);
                                CTR1(KTR_IGMPV3,
                                    "%s: m_append() failed", __func__);
                                return (-ENOMEM);
                        }
                        nbytes += sizeof(struct igmp_grouprec);
                        if (m == m0) {
                                md = m_last(m);
                                pig = (struct igmp_grouprec *)(mtod(md,
                                    uint8_t *) + md->m_len - nbytes);
                        } else {
                                md = m_getptr(m, 0, &off);
                                pig = (struct igmp_grouprec *)(mtod(md,
                                    uint8_t *) + off);
                        }
                        /*
                         * Begin walking the tree for this record type
                         * pass, or continue from where we left off
                         * previously if we had to allocate a new packet.
                         * Only report deltas in-mode at t1.
                         * We need not report included sources as allowed
                         * if we are in inclusive mode on the group,
                         * however the converse is not true.
                         */
                        rsrcs = 0;
                        if (nims == NULL)
                                nims = RB_MIN(ip_msource_tree, &inm->inm_srcs);
                        RB_FOREACH_FROM(ims, ip_msource_tree, nims) {
                                CTR2(KTR_IGMPV3, "%s: visit node %s",
                                    __func__, inet_ntoa_haddr(ims->ims_haddr));
                                now = ims_get_mode(inm, ims, 1);
                                then = ims_get_mode(inm, ims, 0);
                                CTR3(KTR_IGMPV3, "%s: mode: t0 %d, t1 %d",
                                    __func__, then, now);
                                if (now == then) {
                                        CTR1(KTR_IGMPV3,
                                            "%s: skip unchanged", __func__);
                                        continue;
                                }
                                if (mode == MCAST_EXCLUDE &&
                                    now == MCAST_INCLUDE) {
                                        CTR1(KTR_IGMPV3,
                                            "%s: skip IN src on EX group",
                                            __func__);
                                        continue;
                                }
                                nrt = (rectype_t)now;
                                if (nrt == REC_NONE)
                                        nrt = (rectype_t)(~mode & REC_FULL);
                                if (schanged++ == 0) {
                                        crt = nrt;
                                } else if (crt != nrt)
                                        continue;
                                naddr = htonl(ims->ims_haddr);
                                if (!m_append(m, sizeof(in_addr_t),
                                    (void *)&naddr)) {
                                        if (m != m0)
                                                m_freem(m);
                                        CTR1(KTR_IGMPV3,
                                            "%s: m_append() failed", __func__);
                                        return (-ENOMEM);
                                }
                                nallow += !!(crt == REC_ALLOW);
                                nblock += !!(crt == REC_BLOCK);
                                if (++rsrcs == m0srcs)
                                        break;
                        }
                        /*
                         * If we did not append any tree nodes on this
                         * pass, back out of allocations.
                         */
                        if (rsrcs == 0) {
                                nbytes -= sizeof(struct igmp_grouprec);
                                if (m != m0) {
                                        CTR1(KTR_IGMPV3,
                                            "%s: m_free(m)", __func__);
                                        m_freem(m);
                                } else {
                                        CTR1(KTR_IGMPV3,
                                            "%s: m_adj(m, -ig)", __func__);
                                        m_adj(m, -((int)sizeof(
                                            struct igmp_grouprec)));
                                }
                                continue;
                        }
                        nbytes += (rsrcs * sizeof(in_addr_t));
                        if (crt == REC_ALLOW)
                                pig->ig_type = IGMP_ALLOW_NEW_SOURCES;
                        else if (crt == REC_BLOCK)
                                pig->ig_type = IGMP_BLOCK_OLD_SOURCES;
                        pig->ig_numsrc = htons(rsrcs);
                        /*
                         * Count the new group record, and enqueue this
                         * packet if it wasn't already queued.
                         */
                        m->m_pkthdr.PH_vt.vt_nrecs++;
                        if (m != m0)
                                _IF_ENQUEUE(ifq, m);
                } while (nims != NULL);
                drt |= crt;
                crt = (~crt & REC_FULL);
        }

        CTR3(KTR_IGMPV3, "%s: queued %d ALLOW_NEW, %d BLOCK_OLD", __func__,
            nallow, nblock);

        return (nbytes);
}

static int
igmp_v3_merge_state_changes(struct in_multi *inm, struct ifqueue *ifscq)
{
        struct ifqueue  *gq;
        struct mbuf     *m;             /* pending state-change */
        struct mbuf     *m0;            /* copy of pending state-change */
        struct mbuf     *mt;            /* last state-change in packet */
        int              docopy, domerge;
        u_int            recslen;

        docopy = 0;
        domerge = 0;
        recslen = 0;

        IN_MULTI_LOCK_ASSERT();
        IGMP_LOCK_ASSERT();

        /*
         * If there are further pending retransmissions, make a writable
         * copy of each queued state-change message before merging.
         */
        if (inm->inm_scrv > 0)
                docopy = 1;

        gq = &inm->inm_scq;
#ifdef KTR
        if (gq->ifq_head == NULL) {
                CTR2(KTR_IGMPV3, "%s: WARNING: queue for inm %p is empty",
                    __func__, inm);
        }
#endif

        m = gq->ifq_head;
        while (m != NULL) {
                /*
                 * Only merge the report into the current packet if
                 * there is sufficient space to do so; an IGMPv3 report
                 * packet may only contain 65,535 group records.
                 * Always use a simple mbuf chain concatentation to do this,
                 * as large state changes for single groups may have
                 * allocated clusters.
                 */
                domerge = 0;
                mt = ifscq->ifq_tail;
                if (mt != NULL) {
                        recslen = m_length(m, NULL);

                        if ((mt->m_pkthdr.PH_vt.vt_nrecs +
                            m->m_pkthdr.PH_vt.vt_nrecs <=
                            IGMP_V3_REPORT_MAXRECS) &&
                            (mt->m_pkthdr.len + recslen <=
                            (inm->inm_ifp->if_mtu - IGMP_LEADINGSPACE)))
                                domerge = 1;
                }

                if (!domerge && _IF_QFULL(gq)) {
                        CTR2(KTR_IGMPV3,
                            "%s: outbound queue full, skipping whole packet %p",
                            __func__, m);
                        mt = m->m_nextpkt;
                        if (!docopy)
                                m_freem(m);
                        m = mt;
                        continue;
                }

                if (!docopy) {
                        CTR2(KTR_IGMPV3, "%s: dequeueing %p", __func__, m);
                        _IF_DEQUEUE(gq, m0);
                        m = m0->m_nextpkt;
                } else {
                        CTR2(KTR_IGMPV3, "%s: copying %p", __func__, m);
                        m0 = m_dup(m, M_NOWAIT);
                        if (m0 == NULL)
                                return (ENOMEM);
                        m0->m_nextpkt = NULL;
                        m = m->m_nextpkt;
                }

                if (!domerge) {
                        CTR3(KTR_IGMPV3, "%s: queueing %p to ifscq %p)",
                            __func__, m0, ifscq);
                        _IF_ENQUEUE(ifscq, m0);
                } else {
                        struct mbuf *mtl;       /* last mbuf of packet mt */

                        CTR3(KTR_IGMPV3, "%s: merging %p with ifscq tail %p)",
                            __func__, m0, mt);

                        mtl = m_last(mt);
                        m0->m_flags &= ~M_PKTHDR;
                        mt->m_pkthdr.len += recslen;
                        mt->m_pkthdr.PH_vt.vt_nrecs +=
                            m0->m_pkthdr.PH_vt.vt_nrecs;

                        mtl->m_next = m0;
                }
        }

        return (0);
}

/*
 * Respond to a pending IGMPv3 General Query.
 */
static void
igmp_v3_dispatch_general_query(struct igmp_ifinfo *igi)
{
        struct ifmultiaddr      *ifma, *tifma;
        struct ifnet            *ifp;
        struct in_multi         *inm;
        int                      retval, loop;

        IN_MULTI_LOCK_ASSERT();
        IGMP_LOCK_ASSERT();

        KASSERT(igi->igi_version == IGMP_VERSION_3,
            ("%s: called when version %d", __func__, igi->igi_version));

        ifp = igi->igi_ifp;

        IF_ADDR_LOCK(ifp);
        TAILQ_FOREACH_SAFE(ifma, &ifp->if_multiaddrs, ifma_link, tifma) {
                if (ifma->ifma_addr->sa_family != AF_INET ||
                    ifma->ifma_protospec == NULL)
                        continue;

                inm = (struct in_multi *)ifma->ifma_protospec;
                KASSERT(ifp == inm->inm_ifp,
                    ("%s: inconsistent ifp", __func__));

                switch (inm->inm_state) {
                case IGMP_NOT_MEMBER:
                case IGMP_SILENT_MEMBER:
                        break;
                case IGMP_REPORTING_MEMBER:
                case IGMP_IDLE_MEMBER:
                case IGMP_LAZY_MEMBER:
                case IGMP_SLEEPING_MEMBER:
                case IGMP_AWAKENING_MEMBER:
                        inm->inm_state = IGMP_REPORTING_MEMBER;
                        retval = igmp_v3_enqueue_group_record(&igi->igi_gq,
                            inm, 0, 0, 0);
                        CTR2(KTR_IGMPV3, "%s: enqueue record = %d",
                            __func__, retval);
                        break;
                case IGMP_G_QUERY_PENDING_MEMBER:
                case IGMP_SG_QUERY_PENDING_MEMBER:
                case IGMP_LEAVING_MEMBER:
                        break;
                }
        }
        IF_ADDR_UNLOCK(ifp);

        loop = (igi->igi_flags & IGIF_LOOPBACK) ? 1 : 0;
        igmp_dispatch_queue(&igi->igi_gq, IGMP_MAX_RESPONSE_BURST, loop);

        /*
         * Slew transmission of bursts over 500ms intervals.
         */
        if (igi->igi_gq.ifq_head != NULL) {
                igi->igi_v3_timer = 1 + IGMP_RANDOM_DELAY(
                    IGMP_RESPONSE_BURST_INTERVAL);
                V_interface_timers_running = 1;
        }
}

/*
 * Transmit the next pending IGMP message in the output queue.
 *
 * We get called from netisr_processqueue(). A mutex private to igmpoq
 * will be acquired and released around this routine.
 *
 * VIMAGE: Needs to store/restore vnet pointer on a per-mbuf-chain basis.
 * MRT: Nothing needs to be done, as IGMP traffic is always local to
 * a link and uses a link-scope multicast address.
 */
static void
igmp_intr(struct mbuf *m)
{
        struct ip_moptions       imo;
        struct ifnet            *ifp;
        struct mbuf             *ipopts, *m0;
        int                      error;
        uint32_t                 ifindex;

        CTR2(KTR_IGMPV3, "%s: transmit %p", __func__, m);

        /*
         * Restore 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.
         */
        CURVNET_SET(m->m_pkthdr.header);
        ifindex = igmp_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_IGMPV3, "%s: dropped %p as ifindex %u went away.",
                    __func__, m, ifindex);
                m_freem(m);
                V_ipstat.ips_noroute++;
                goto out;
        }

        ipopts = V_igmp_sendra ? m_raopt : NULL;

        imo.imo_multicast_ttl  = 1;
        imo.imo_multicast_vif  = -1;
        imo.imo_multicast_loop = (V_ip_mrouter != NULL);

        /*
         * If the user requested that IGMP traffic be explicitly
         * redirected to the loopback interface (e.g. they are running a
         * MANET interface and the routing protocol needs to see the
         * updates), handle this now.
         */
        if (m->m_flags & M_IGMP_LOOP)
                imo.imo_multicast_ifp = V_loif;
        else
                imo.imo_multicast_ifp = ifp;

        if (m->m_flags & M_IGMPV2) {
                m0 = m;
        } else {
                m0 = igmp_v3_encap_report(ifp, m);
                if (m0 == NULL) {
                        CTR2(KTR_IGMPV3, "%s: dropped %p", __func__, m);
                        m_freem(m);
                        V_ipstat.ips_odropped++;
                        goto out;
                }
        }

        igmp_scrub_context(m0);
        m->m_flags &= ~(M_PROTOFLAGS);
        m0->m_pkthdr.rcvif = V_loif;
#ifdef MAC
        mac_netinet_igmp_send(ifp, m0);
#endif
        error = ip_output(m0, ipopts, NULL, 0, &imo, NULL);
        if (error) {
                CTR3(KTR_IGMPV3, "%s: ip_output(%p) = %d", __func__, m0, error);
                goto out;
        }

        ++V_igmpstat.igps_snd_reports;

out:
        /*
         * We must restore the existing vnet pointer before
         * continuing as we are run from netisr context.
         */
        CURVNET_RESTORE();
}

/*
 * Encapsulate an IGMPv3 report.
 *
 * The internal mbuf flag M_IGMPV3_HDR is used to indicate that the mbuf
 * chain has already had its IP/IGMPv3 header prepended. In this case
 * the function will not attempt to prepend; the lengths and checksums
 * will however be re-computed.
 *
 * Returns a pointer to the new mbuf chain head, or NULL if the
 * allocation failed.
 */
static struct mbuf *
igmp_v3_encap_report(struct ifnet *ifp, struct mbuf *m)
{
        INIT_VNET_NET(curvnet);
        INIT_VNET_INET(curvnet);
        struct igmp_report      *igmp;
        struct ip               *ip;
        int                      hdrlen, igmpreclen;

        KASSERT((m->m_flags & M_PKTHDR),
            ("%s: mbuf chain %p is !M_PKTHDR", __func__, m));

        igmpreclen = m_length(m, NULL);
        hdrlen = sizeof(struct ip) + sizeof(struct igmp_report);

        if (m->m_flags & M_IGMPV3_HDR) {
                igmpreclen -= hdrlen;
        } else {
                M_PREPEND(m, hdrlen, M_DONTWAIT);
                if (m == NULL)
                        return (NULL);
                m->m_flags |= M_IGMPV3_HDR;
        }

        CTR2(KTR_IGMPV3, "%s: igmpreclen is %d", __func__, igmpreclen);

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

        igmp = mtod(m, struct igmp_report *);
        igmp->ir_type = IGMP_v3_HOST_MEMBERSHIP_REPORT;
        igmp->ir_rsv1 = 0;
        igmp->ir_rsv2 = 0;
        igmp->ir_numgrps = htons(m->m_pkthdr.PH_vt.vt_nrecs);
        igmp->ir_cksum = 0;
        igmp->ir_cksum = in_cksum(m, sizeof(struct igmp_report) + igmpreclen);
        m->m_pkthdr.PH_vt.vt_nrecs = 0;

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

        ip = mtod(m, struct ip *);
        ip->ip_tos = IPTOS_PREC_INTERNETCONTROL;
        ip->ip_len = hdrlen + igmpreclen;
        ip->ip_off = IP_DF;
        ip->ip_p = IPPROTO_IGMP;
        ip->ip_sum = 0;

        ip->ip_src.s_addr = INADDR_ANY;

        if (m->m_flags & M_IGMP_LOOP) {
                struct in_ifaddr *ia;

                IFP_TO_IA(ifp, ia);
                if (ia != NULL)
                        ip->ip_src = ia->ia_addr.sin_addr;
        }

        ip->ip_dst.s_addr = htonl(INADDR_ALLRPTS_GROUP);

        return (m);
}

#ifdef KTR
static char *
igmp_rec_type_to_str(const int type)
{

        switch (type) {
                case IGMP_CHANGE_TO_EXCLUDE_MODE:
                        return "TO_EX";
                        break;
                case IGMP_CHANGE_TO_INCLUDE_MODE:
                        return "TO_IN";
                        break;
                case IGMP_MODE_IS_EXCLUDE:
                        return "MODE_EX";
                        break;
                case IGMP_MODE_IS_INCLUDE:
                        return "MODE_IN";
                        break;
                case IGMP_ALLOW_NEW_SOURCES:
                        return "ALLOW_NEW";
                        break;
                case IGMP_BLOCK_OLD_SOURCES:
                        return "BLOCK_OLD";
                        break;
                default:
                        break;
        }
        return "unknown";
}
#endif

static void
igmp_sysinit(void)
{

        CTR1(KTR_IGMPV3, "%s: initializing", __func__);

        IGMP_LOCK_INIT();
        TUNABLE_INT_FETCH("debug.mpsafeigmp", &mpsafe_igmp);

        mtx_init(&igmpoq.ifq_mtx, "igmpoq_mtx", NULL, MTX_DEF);
        IFQ_SET_MAXLEN(&igmpoq, IFQ_MAXLEN);

        m_raopt = igmp_ra_alloc();

#if __FreeBSD_version < 800000
        netisr_register(NETISR_IGMP, igmp_intr, &igmpoq,
            mpsafe_igmp ? NETISR_MPSAFE : 0);
#else
        netisr_register(NETISR_IGMP, igmp_intr, &igmpoq,
            mpsafe_igmp ? 0 : NETISR_FORCEQUEUE);
#endif
}

static void
igmp_sysuninit(void)
{

        CTR1(KTR_IGMPV3, "%s: tearing down", __func__);

        netisr_unregister(NETISR_IGMP);
        mtx_destroy(&igmpoq.ifq_mtx);

        m_free(m_raopt);
        m_raopt = NULL;

        IGMP_LOCK_DESTROY();
}

/*
 * Initialize an IGMPv3 instance.
 * VIMAGE: Assumes curvnet set by caller and called per vimage.
 */
static int
vnet_igmp_iattach(const void *unused __unused)
{
        INIT_VNET_INET(curvnet);

        CTR1(KTR_IGMPV3, "%s: initializing", __func__);

        LIST_INIT(&V_igi_head);

        V_current_state_timers_running = 0;
        V_state_change_timers_running = 0;
        V_interface_timers_running = 0;

        /*
         * Initialize sysctls to default values.
         */
        V_igmp_recvifkludge = 1;
        V_igmp_sendra = 1;
        V_igmp_sendlocal = 1;
        V_igmp_v1enable = 1;
        V_igmp_v2enable = 1;
        V_igmp_legacysupp = 0;
        V_igmp_default_version = IGMP_VERSION_3;
        V_igmp_gsrdelay.tv_sec = 10;
        V_igmp_gsrdelay.tv_usec = 0;

        memset(&V_igmpstat, 0, sizeof(struct igmpstat));
        V_igmpstat.igps_version = IGPS_VERSION_3;
        V_igmpstat.igps_len = sizeof(struct igmpstat);

        return (0);
}

static int
vnet_igmp_idetach(const void *unused __unused)
{
        INIT_VNET_INET(curvnet);

        CTR1(KTR_IGMPV3, "%s: tearing down", __func__);

        KASSERT(LIST_EMPTY(&V_igi_head),
            ("%s: igi list not empty; ifnets not detached?", __func__));

        return (0);
}

#ifdef VIMAGE
static struct vnet_symmap vnet_igmp_symmap[] = {
        VNET_SYMMAP(igmp, igi_head),
        VNET_SYMMAP(igmp, igmpstat),
        VNET_SYMMAP_END
};
VNET_MOD_DECLARE(IGMP, igmp, vnet_igmp_iattach, vnet_igmp_idetach,
    vnet_igmp_symmap);
#endif /* VIMAGE */

static int
igmp_modevent(module_t mod, int type, void *unused __unused)
{

    switch (type) {
    case MOD_LOAD:
        igmp_sysinit();
#ifdef VIMAGE
        vnet_mod_register(&vnet_igmp_modinfo);
#else
        (void)vnet_igmp_iattach(NULL);
#endif /* VIMAGE */
        break;
    case MOD_UNLOAD:
#ifdef VIMAGE
        /*
         * TODO: Allow module unload if any VIMAGE instances
         * are using this module.
         */
        return (EBUSY);
#else
        (void)vnet_igmp_idetach(NULL);
#endif /* VIMAGE */
        igmp_sysuninit();
        break;
    default:
        return (EOPNOTSUPP);
    }
    return (0);
}

static moduledata_t igmp_mod = {
    "igmp",
    igmp_modevent,
    0
};
DECLARE_MODULE(igmp, igmp_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);