xnu-2422.115.4.tar.gz

[apple/xnu.git] / bsd / netinet / in_mcast.c

/*
 * Copyright (c) 2010-2013 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*-
 * Copyright (c) 2007-2009 Bruce Simpson.
 * Copyright (c) 2005 Robert N. M. Watson.
 * All rights reserved.
 *
 * 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.
 * 3. The name of the author may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 */

/*
 * IPv4 multicast socket, group, and socket option processing module.
 */

#include <sys/cdefs.h>

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/protosw.h>
#include <sys/sysctl.h>
#include <sys/tree.h>
#include <sys/mcache.h>

#include <kern/zalloc.h>

#include <pexpert/pexpert.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/route.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_pcb.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#include <netinet/igmp_var.h>

#ifndef __SOCKUNION_DECLARED
union sockunion {
        struct sockaddr_storage ss;
        struct sockaddr         sa;
        struct sockaddr_dl      sdl;
        struct sockaddr_in      sin;
};
typedef union sockunion sockunion_t;
#define __SOCKUNION_DECLARED
#endif /* __SOCKUNION_DECLARED */

/*
 * Functions with non-static linkage defined in this file should be
 * declared in in_var.h:
 *  imo_multi_filter()
 *  in_addmulti()
 *  in_delmulti()
 *  in_joingroup()
 *  in_leavegroup()
 * and ip_var.h:
 *  inp_freemoptions()
 *  inp_getmoptions()
 *  inp_setmoptions()
 *
 * XXX: Both carp and pf need to use the legacy (*,G) KPIs in_addmulti()
 * and in_delmulti().
 */
static void     imf_commit(struct in_mfilter *);
static int      imf_get_source(struct in_mfilter *imf,
                    const struct sockaddr_in *psin,
                    struct in_msource **);
static struct in_msource *
                imf_graft(struct in_mfilter *, const uint8_t,
                    const struct sockaddr_in *);
static int      imf_prune(struct in_mfilter *, const struct sockaddr_in *);
static void     imf_rollback(struct in_mfilter *);
static void     imf_reap(struct in_mfilter *);
static int      imo_grow(struct ip_moptions *, size_t);
static size_t   imo_match_group(const struct ip_moptions *,
                    const struct ifnet *, const struct sockaddr *);
static struct in_msource *
                imo_match_source(const struct ip_moptions *, const size_t,
                    const struct sockaddr *);
static void     ims_merge(struct ip_msource *ims,
                    const struct in_msource *lims, const int rollback);
static int      in_getmulti(struct ifnet *, const struct in_addr *,
                    struct in_multi **);
static int      in_joingroup(struct ifnet *, const struct in_addr *,
                    struct in_mfilter *, struct in_multi **);
static int      inm_get_source(struct in_multi *inm, const in_addr_t haddr,
                    const int noalloc, struct ip_msource **pims);
static int      inm_is_ifp_detached(const struct in_multi *);
static int      inm_merge(struct in_multi *, /*const*/ struct in_mfilter *);
static void     inm_reap(struct in_multi *);
static struct ip_moptions *
                inp_findmoptions(struct inpcb *);
static int      inp_get_source_filters(struct inpcb *, struct sockopt *);
static struct ifnet *
                inp_lookup_mcast_ifp(const struct inpcb *,
                    const struct sockaddr_in *, const struct in_addr);
static int      inp_block_unblock_source(struct inpcb *, struct sockopt *);
static int      inp_set_multicast_if(struct inpcb *, struct sockopt *);
static int      inp_set_source_filters(struct inpcb *, struct sockopt *);
static int      sysctl_ip_mcast_filters SYSCTL_HANDLER_ARGS;
static struct ifnet * ip_multicast_if(struct in_addr *, unsigned int *);
static __inline__ int ip_msource_cmp(const struct ip_msource *,
    const struct ip_msource *);

SYSCTL_NODE(_net_inet_ip, OID_AUTO, mcast, CTLFLAG_RW | CTLFLAG_LOCKED, 0, "IPv4 multicast");

static u_long in_mcast_maxgrpsrc = IP_MAX_GROUP_SRC_FILTER;
SYSCTL_LONG(_net_inet_ip_mcast, OID_AUTO, maxgrpsrc,
    CTLFLAG_RW | CTLFLAG_LOCKED, &in_mcast_maxgrpsrc, "Max source filters per group");

static u_long in_mcast_maxsocksrc = IP_MAX_SOCK_SRC_FILTER;
SYSCTL_LONG(_net_inet_ip_mcast, OID_AUTO, maxsocksrc,
    CTLFLAG_RW | CTLFLAG_LOCKED, &in_mcast_maxsocksrc, 
    "Max source filters per socket");

int in_mcast_loop = IP_DEFAULT_MULTICAST_LOOP;
SYSCTL_INT(_net_inet_ip_mcast, OID_AUTO, loop, CTLFLAG_RW | CTLFLAG_LOCKED, 
    &in_mcast_loop, 0, "Loopback multicast datagrams by default");

SYSCTL_NODE(_net_inet_ip_mcast, OID_AUTO, filters,
    CTLFLAG_RD | CTLFLAG_LOCKED, sysctl_ip_mcast_filters,
    "Per-interface stack-wide source filters");

RB_GENERATE_PREV(ip_msource_tree, ip_msource, ims_link, ip_msource_cmp);

#define INM_TRACE_HIST_SIZE     32      /* size of trace history */

/* For gdb */
__private_extern__ unsigned int inm_trace_hist_size = INM_TRACE_HIST_SIZE;

struct in_multi_dbg {
        struct in_multi         inm;                    /* in_multi */
        u_int16_t               inm_refhold_cnt;        /* # of ref */
        u_int16_t               inm_refrele_cnt;        /* # of rele */
        /*
         * Circular lists of inm_addref and inm_remref callers.
         */
        ctrace_t                inm_refhold[INM_TRACE_HIST_SIZE];
        ctrace_t                inm_refrele[INM_TRACE_HIST_SIZE];
        /*
         * Trash list linkage
         */
        TAILQ_ENTRY(in_multi_dbg) inm_trash_link;
};

/* List of trash in_multi entries protected by inm_trash_lock */
static TAILQ_HEAD(, in_multi_dbg) inm_trash_head;
static decl_lck_mtx_data(, inm_trash_lock);

#define INM_ZONE_MAX            64              /* maximum elements in zone */
#define INM_ZONE_NAME           "in_multi"      /* zone name */

#if DEBUG
static unsigned int inm_debug = 1;              /* debugging (enabled) */
#else
static unsigned int inm_debug;                  /* debugging (disabled) */
#endif /* !DEBUG */
static unsigned int inm_size;                   /* size of zone element */
static struct zone *inm_zone;                   /* zone for in_multi */

#define IPMS_ZONE_MAX           64              /* maximum elements in zone */
#define IPMS_ZONE_NAME          "ip_msource"    /* zone name */

static unsigned int ipms_size;                  /* size of zone element */
static struct zone *ipms_zone;                  /* zone for ip_msource */

#define INMS_ZONE_MAX           64              /* maximum elements in zone */
#define INMS_ZONE_NAME          "in_msource"    /* zone name */

static unsigned int inms_size;                  /* size of zone element */
static struct zone *inms_zone;                  /* zone for in_msource */

/* Lock group and attribute for in_multihead_lock lock */
static lck_attr_t       *in_multihead_lock_attr;
static lck_grp_t        *in_multihead_lock_grp;
static lck_grp_attr_t   *in_multihead_lock_grp_attr;

static decl_lck_rw_data(, in_multihead_lock);
struct in_multihead in_multihead;

static struct in_multi *in_multi_alloc(int);
static void in_multi_free(struct in_multi *);
static void in_multi_attach(struct in_multi *);
static void inm_trace(struct in_multi *, int);

static struct ip_msource *ipms_alloc(int);
static void ipms_free(struct ip_msource *);
static struct in_msource *inms_alloc(int);
static void inms_free(struct in_msource *);

static __inline int
ip_msource_cmp(const struct ip_msource *a, const struct ip_msource *b)
{

        if (a->ims_haddr < b->ims_haddr)
                return (-1);
        if (a->ims_haddr == b->ims_haddr)
                return (0);
        return (1);
}

/*
 * Inline function which wraps assertions for a valid ifp.
 */
static __inline__ int
inm_is_ifp_detached(const struct in_multi *inm)
{
        VERIFY(inm->inm_ifma != NULL);
        VERIFY(inm->inm_ifp == inm->inm_ifma->ifma_ifp);

        return (!ifnet_is_attached(inm->inm_ifp, 0));
}

/*
 * Initialize an in_mfilter structure to a known state at t0, t1
 * with an empty source filter list.
 */
static __inline__ void
imf_init(struct in_mfilter *imf, const int st0, const int st1)
{
        memset(imf, 0, sizeof(struct in_mfilter));
        RB_INIT(&imf->imf_sources);
        imf->imf_st[0] = st0;
        imf->imf_st[1] = st1;
}

/*
 * Resize the ip_moptions vector to the next power-of-two minus 1.
 */
static int
imo_grow(struct ip_moptions *imo, size_t newmax)
{
        struct in_multi         **nmships;
        struct in_multi         **omships;
        struct in_mfilter        *nmfilters;
        struct in_mfilter        *omfilters;
        size_t                    idx;
        size_t                    oldmax;

        IMO_LOCK_ASSERT_HELD(imo);

        nmships = NULL;
        nmfilters = NULL;
        omships = imo->imo_membership;
        omfilters = imo->imo_mfilters;
        oldmax = imo->imo_max_memberships;
        if (newmax == 0)
                newmax = ((oldmax + 1) * 2) - 1;

        if (newmax > IP_MAX_MEMBERSHIPS)
                return (ETOOMANYREFS);

        if ((nmships = (struct in_multi **)_REALLOC(omships,
            sizeof (struct in_multi *) * newmax, M_IPMOPTS,
            M_WAITOK | M_ZERO)) == NULL)
                return (ENOMEM);

        imo->imo_membership = nmships;

        if ((nmfilters = (struct in_mfilter *)_REALLOC(omfilters,
            sizeof (struct in_mfilter) * newmax, M_INMFILTER,
            M_WAITOK | M_ZERO)) == NULL)
                return (ENOMEM);

        imo->imo_mfilters = nmfilters;

        /* Initialize newly allocated source filter heads. */
        for (idx = oldmax; idx < newmax; idx++)
                imf_init(&nmfilters[idx], MCAST_UNDEFINED, MCAST_EXCLUDE);

        imo->imo_max_memberships = newmax;

        return (0);
}

/*
 * Find an IPv4 multicast group entry for this ip_moptions instance
 * which matches the specified group, and optionally an interface.
 * Return its index into the array, or -1 if not found.
 */
static size_t
imo_match_group(const struct ip_moptions *imo, const struct ifnet *ifp,
    const struct sockaddr *group)
{
        const struct sockaddr_in *gsin;
        struct in_multi *pinm;
        int               idx;
        int               nmships;

        IMO_LOCK_ASSERT_HELD(__DECONST(struct ip_moptions *, imo));

        gsin = (struct sockaddr_in *)(uintptr_t)(size_t)group;

        /* The imo_membership array may be lazy allocated. */
        if (imo->imo_membership == NULL || imo->imo_num_memberships == 0)
                return (-1);

        nmships = imo->imo_num_memberships;
        for (idx = 0; idx < nmships; idx++) {
                pinm = imo->imo_membership[idx];
                if (pinm == NULL)
                        continue;
                INM_LOCK(pinm);
                if ((ifp == NULL || (pinm->inm_ifp == ifp)) &&
                    in_hosteq(pinm->inm_addr, gsin->sin_addr)) {
                        INM_UNLOCK(pinm);
                        break;
                }
                INM_UNLOCK(pinm);
        }
        if (idx >= nmships)
                idx = -1;

        return (idx);
}

/*
 * Find an IPv4 multicast source entry for this imo which matches
 * the given group index for this socket, and source address.
 *
 * NOTE: This does not check if the entry is in-mode, merely if
 * it exists, which may not be the desired behaviour.
 */
static struct in_msource *
imo_match_source(const struct ip_moptions *imo, const size_t gidx,
    const struct sockaddr *src)
{
        struct ip_msource        find;
        struct in_mfilter       *imf;
        struct ip_msource       *ims;
        const sockunion_t       *psa;

        IMO_LOCK_ASSERT_HELD(__DECONST(struct ip_moptions *, imo));

        VERIFY(src->sa_family == AF_INET);
        VERIFY(gidx != (size_t)-1 && gidx < imo->imo_num_memberships);

        /* The imo_mfilters array may be lazy allocated. */
        if (imo->imo_mfilters == NULL)
                return (NULL);
        imf = &imo->imo_mfilters[gidx];

        /* Source trees are keyed in host byte order. */
        psa = (sockunion_t *)(uintptr_t)(size_t)src;
        find.ims_haddr = ntohl(psa->sin.sin_addr.s_addr);
        ims = RB_FIND(ip_msource_tree, &imf->imf_sources, &find);

        return ((struct in_msource *)ims);
}

/*
 * Perform filtering for multicast datagrams on a socket by group and source.
 *
 * Returns 0 if a datagram should be allowed through, or various error codes
 * if the socket was not a member of the group, or the source was muted, etc.
 */
int
imo_multi_filter(const struct ip_moptions *imo, const struct ifnet *ifp,
    const struct sockaddr *group, const struct sockaddr *src)
{
        size_t gidx;
        struct in_msource *ims;
        int mode;

        IMO_LOCK_ASSERT_HELD(__DECONST(struct ip_moptions *, imo));
        VERIFY(ifp != NULL);

        gidx = imo_match_group(imo, ifp, group);
        if (gidx == (size_t)-1)
                return (MCAST_NOTGMEMBER);

        /*
         * Check if the source was included in an (S,G) join.
         * Allow reception on exclusive memberships by default,
         * reject reception on inclusive memberships by default.
         * Exclude source only if an in-mode exclude filter exists.
         * Include source only if an in-mode include filter exists.
         * NOTE: We are comparing group state here at IGMP t1 (now)
         * with socket-layer t0 (since last downcall).
         */
        mode = imo->imo_mfilters[gidx].imf_st[1];
        ims = imo_match_source(imo, gidx, src);

        if ((ims == NULL && mode == MCAST_INCLUDE) ||
            (ims != NULL && ims->imsl_st[0] != mode)) {
                return (MCAST_NOTSMEMBER);
        }

        return (MCAST_PASS);
}

int
imo_clone(struct inpcb *from_inp, struct inpcb *to_inp)
{
        int i, err = 0;
        struct ip_moptions *from;
        struct ip_moptions *to;

        from = inp_findmoptions(from_inp);
        if (from == NULL)
                return (ENOMEM); 

        to = inp_findmoptions(to_inp);
        if (to == NULL) {
                IMO_REMREF(from);
                return (ENOMEM);
        }

        IMO_LOCK(from);
        IMO_LOCK(to);

        to->imo_multicast_ifp = from->imo_multicast_ifp;
        to->imo_multicast_vif = from->imo_multicast_vif;
        to->imo_multicast_ttl = from->imo_multicast_ttl;
        to->imo_multicast_loop = from->imo_multicast_loop;

        /*
         * We're cloning, so drop any existing memberships and source
         * filters on the destination ip_moptions.
         */
        for (i = 0; i < to->imo_num_memberships; ++i) {
                struct in_mfilter *imf;

                imf = to->imo_mfilters ? &to->imo_mfilters[i] : NULL;
                if (imf != NULL)
                        imf_leave(imf);

                (void) in_leavegroup(to->imo_membership[i], imf);

                if (imf != NULL)
                        imf_purge(imf);

                INM_REMREF(to->imo_membership[i]);
                to->imo_membership[i] = NULL;
        }
        to->imo_num_memberships = 0;

        VERIFY(to->imo_max_memberships != 0 && from->imo_max_memberships != 0);
        if (to->imo_max_memberships < from->imo_max_memberships) {
                /*
                 * Ensure source and destination ip_moptions memberships
                 * and source filters arrays are at least equal in size.
                 */
                err = imo_grow(to, from->imo_max_memberships);
                if (err != 0)
                        goto done;
        }
        VERIFY(to->imo_max_memberships >= from->imo_max_memberships);

        /*
         * Source filtering doesn't apply to OpenTransport socket,
         * so simply hold additional reference count per membership.
         */
        for (i = 0; i < from->imo_num_memberships; i++) {
                to->imo_membership[i] = 
                        in_addmulti(&from->imo_membership[i]->inm_addr,
                                                from->imo_membership[i]->inm_ifp);
                if (to->imo_membership[i] == NULL)
                        break;
                to->imo_num_memberships++;
        }
        VERIFY(to->imo_num_memberships == from->imo_num_memberships);

done:
        IMO_UNLOCK(to);
        IMO_REMREF(to);
        IMO_UNLOCK(from);
        IMO_REMREF(from);

        return (err);
}

/*
 * Find and return a reference to an in_multi record for (ifp, group),
 * and bump its reference count.
 * If one does not exist, try to allocate it, and update link-layer multicast
 * filters on ifp to listen for group.
 * Return 0 if successful, otherwise return an appropriate error code.
 */
static int
in_getmulti(struct ifnet *ifp, const struct in_addr *group,
    struct in_multi **pinm)
{
        struct sockaddr_in       gsin;
        struct ifmultiaddr      *ifma;
        struct in_multi         *inm;
        int                     error;

        in_multihead_lock_shared();
        IN_LOOKUP_MULTI(group, ifp, inm);
        if (inm != NULL) {
                INM_LOCK(inm);
                VERIFY(inm->inm_reqcnt >= 1);
                inm->inm_reqcnt++;
                VERIFY(inm->inm_reqcnt != 0);
                *pinm = inm;
                INM_UNLOCK(inm);
                in_multihead_lock_done();
                /*
                 * We already joined this group; return the inm
                 * with a refcount held (via lookup) for caller.
                 */
                return (0);
        }
        in_multihead_lock_done();

        bzero(&gsin, sizeof(gsin));
        gsin.sin_family = AF_INET;
        gsin.sin_len = sizeof(struct sockaddr_in);
        gsin.sin_addr = *group;

        /*
         * Check if a link-layer group is already associated
         * with this network-layer group on the given ifnet.
         */
        error = if_addmulti(ifp, (struct sockaddr *)&gsin, &ifma);
        if (error != 0)
                return (error);

        /*
         * See comments in inm_remref() for access to ifma_protospec.
         */
        in_multihead_lock_exclusive();
        IFMA_LOCK(ifma);
        if ((inm = ifma->ifma_protospec) != NULL) {
                VERIFY(ifma->ifma_addr != NULL);
                VERIFY(ifma->ifma_addr->sa_family == AF_INET);
                INM_ADDREF(inm);        /* for caller */
                IFMA_UNLOCK(ifma);
                INM_LOCK(inm);
                VERIFY(inm->inm_ifma == ifma);
                VERIFY(inm->inm_ifp == ifp);
                VERIFY(in_hosteq(inm->inm_addr, *group));
                if (inm->inm_debug & IFD_ATTACHED) {
                        VERIFY(inm->inm_reqcnt >= 1);
                        inm->inm_reqcnt++;
                        VERIFY(inm->inm_reqcnt != 0);
                        *pinm = inm;
                        INM_UNLOCK(inm);
                        in_multihead_lock_done();
                        IFMA_REMREF(ifma);
                        /*
                         * We lost the race with another thread doing
                         * in_getmulti(); since this group has already
                         * been joined; return the inm with a refcount
                         * held for caller.
                         */
                        return (0);
                }
                /*
                 * We lost the race with another thread doing in_delmulti();
                 * the inm referring to the ifma has been detached, thus we
                 * reattach it back to the in_multihead list and return the
                 * inm with a refcount held for the caller.
                 */
                in_multi_attach(inm);
                VERIFY((inm->inm_debug &
                    (IFD_ATTACHED | IFD_TRASHED)) == IFD_ATTACHED);
                *pinm = inm;
                INM_UNLOCK(inm);
                in_multihead_lock_done();
                IFMA_REMREF(ifma);
                return (0);
        }
        IFMA_UNLOCK(ifma);

        /*
         * A new in_multi record is needed; allocate and initialize it.
         * We DO NOT perform an IGMP join as the in_ layer may need to
         * push an initial source list down to IGMP to support SSM.
         *
         * The initial source filter state is INCLUDE, {} as per the RFC.
         */
        inm = in_multi_alloc(M_WAITOK);
        if (inm == NULL) {
                in_multihead_lock_done();
                IFMA_REMREF(ifma);
                return (ENOMEM);
        }
        INM_LOCK(inm);
        inm->inm_addr = *group;
        inm->inm_ifp = ifp;
        inm->inm_igi = IGMP_IFINFO(ifp);
        VERIFY(inm->inm_igi != NULL);
        IGI_ADDREF(inm->inm_igi);
        inm->inm_ifma = ifma;           /* keep refcount from if_addmulti() */
        inm->inm_state = IGMP_NOT_MEMBER;
        /*
         * Pending state-changes per group are subject to a bounds check.
         */
        inm->inm_scq.ifq_maxlen = IGMP_MAX_STATE_CHANGES;
        inm->inm_st[0].iss_fmode = MCAST_UNDEFINED;
        inm->inm_st[1].iss_fmode = MCAST_UNDEFINED;
        RB_INIT(&inm->inm_srcs);
        *pinm = inm;
        in_multi_attach(inm);
        VERIFY((inm->inm_debug & (IFD_ATTACHED | IFD_TRASHED)) == IFD_ATTACHED);
        INM_ADDREF_LOCKED(inm);         /* for caller */
        INM_UNLOCK(inm);

        IFMA_LOCK(ifma);
        VERIFY(ifma->ifma_protospec == NULL);
        ifma->ifma_protospec = inm;
        IFMA_UNLOCK(ifma);
        in_multihead_lock_done();

        return (0);
}

/*
 * Clear recorded source entries for a group.
 * Used by the IGMP code.
 * FIXME: Should reap.
 */
void
inm_clear_recorded(struct in_multi *inm)
{
        struct ip_msource       *ims;

        INM_LOCK_ASSERT_HELD(inm);

        RB_FOREACH(ims, ip_msource_tree, &inm->inm_srcs) {
                if (ims->ims_stp) {
                        ims->ims_stp = 0;
                        --inm->inm_st[1].iss_rec;
                }
        }
        VERIFY(inm->inm_st[1].iss_rec == 0);
}

/*
 * Record a source as pending for a Source-Group IGMPv3 query.
 * This lives here as it modifies the shared tree.
 *
 * inm is the group descriptor.
 * naddr is the address of the source to record in network-byte order.
 *
 * If the net.inet.igmp.sgalloc sysctl is non-zero, we will
 * lazy-allocate a source node in response to an SG query.
 * Otherwise, no allocation is performed. This saves some memory
 * with the trade-off that the source will not be reported to the
 * router if joined in the window between the query response and
 * the group actually being joined on the local host.
 *
 * Return 0 if the source didn't exist or was already marked as recorded.
 * Return 1 if the source was marked as recorded by this function.
 * Return <0 if any error occured (negated errno code).
 */
int
inm_record_source(struct in_multi *inm, const in_addr_t naddr)
{
        struct ip_msource        find;
        struct ip_msource       *ims, *nims;

        INM_LOCK_ASSERT_HELD(inm);

        find.ims_haddr = ntohl(naddr);
        ims = RB_FIND(ip_msource_tree, &inm->inm_srcs, &find);
        if (ims && ims->ims_stp)
                return (0);
        if (ims == NULL) {
                if (inm->inm_nsrc == in_mcast_maxgrpsrc)
                        return (-ENOSPC);
                nims = ipms_alloc(M_WAITOK);
                if (nims == NULL)
                        return (-ENOMEM);
                nims->ims_haddr = find.ims_haddr;
                RB_INSERT(ip_msource_tree, &inm->inm_srcs, nims);
                ++inm->inm_nsrc;
                ims = nims;
        }

        /*
         * Mark the source as recorded and update the recorded
         * source count.
         */
        ++ims->ims_stp;
        ++inm->inm_st[1].iss_rec;

        return (1);
}

/*
 * Return a pointer to an in_msource owned by an in_mfilter,
 * given its source address.
 * Lazy-allocate if needed. If this is a new entry its filter state is
 * undefined at t0.
 *
 * imf is the filter set being modified.
 * haddr is the source address in *host* byte-order.
 *
 * Caller is expected to be holding imo_lock.
 */
static int
imf_get_source(struct in_mfilter *imf, const struct sockaddr_in *psin,
    struct in_msource **plims)
{
        struct ip_msource        find;
        struct ip_msource       *ims;
        struct in_msource       *lims;
        int                      error;

        error = 0;
        ims = NULL;
        lims = NULL;

        /* key is host byte order */
        find.ims_haddr = ntohl(psin->sin_addr.s_addr);
        ims = RB_FIND(ip_msource_tree, &imf->imf_sources, &find);
        lims = (struct in_msource *)ims;
        if (lims == NULL) {
                if (imf->imf_nsrc == in_mcast_maxsocksrc)
                        return (ENOSPC);
                lims = inms_alloc(M_WAITOK);
                if (lims == NULL)
                        return (ENOMEM);
                lims->ims_haddr = find.ims_haddr;
                lims->imsl_st[0] = MCAST_UNDEFINED;
                RB_INSERT(ip_msource_tree, &imf->imf_sources,
                    (struct ip_msource *)lims);
                ++imf->imf_nsrc;
        }

        *plims = lims;

        return (error);
}

/*
 * Graft a source entry into an existing socket-layer filter set,
 * maintaining any required invariants and checking allocations.
 *
 * The source is marked as being in the new filter mode at t1.
 *
 * Return the pointer to the new node, otherwise return NULL.
 *
 * Caller is expected to be holding imo_lock.
 */
static struct in_msource *
imf_graft(struct in_mfilter *imf, const uint8_t st1,
    const struct sockaddr_in *psin)
{
        struct in_msource       *lims;

        lims = inms_alloc(M_WAITOK);
        if (lims == NULL)
                return (NULL);
        lims->ims_haddr = ntohl(psin->sin_addr.s_addr);
        lims->imsl_st[0] = MCAST_UNDEFINED;
        lims->imsl_st[1] = st1;
        RB_INSERT(ip_msource_tree, &imf->imf_sources,
            (struct ip_msource *)lims);
        ++imf->imf_nsrc;

        return (lims);
}

/*
 * Prune a source entry from an existing socket-layer filter set,
 * maintaining any required invariants and checking allocations.
 *
 * The source is marked as being left at t1, it is not freed.
 *
 * Return 0 if no error occurred, otherwise return an errno value.
 *
 * Caller is expected to be holding imo_lock.
 */
static int
imf_prune(struct in_mfilter *imf, const struct sockaddr_in *psin)
{
        struct ip_msource        find;
        struct ip_msource       *ims;
        struct in_msource       *lims;

        /* key is host byte order */
        find.ims_haddr = ntohl(psin->sin_addr.s_addr);
        ims = RB_FIND(ip_msource_tree, &imf->imf_sources, &find);
        if (ims == NULL)
                return (ENOENT);
        lims = (struct in_msource *)ims;
        lims->imsl_st[1] = MCAST_UNDEFINED;
        return (0);
}

/*
 * Revert socket-layer filter set deltas at t1 to t0 state.
 *
 * Caller is expected to be holding imo_lock.
 */
static void
imf_rollback(struct in_mfilter *imf)
{
        struct ip_msource       *ims, *tims;
        struct in_msource       *lims;

        RB_FOREACH_SAFE(ims, ip_msource_tree, &imf->imf_sources, tims) {
                lims = (struct in_msource *)ims;
                if (lims->imsl_st[0] == lims->imsl_st[1]) {
                        /* no change at t1 */
                        continue;
                } else if (lims->imsl_st[0] != MCAST_UNDEFINED) {
                        /* revert change to existing source at t1 */
                        lims->imsl_st[1] = lims->imsl_st[0];
                } else {
                        /* revert source added t1 */
                        IGMP_PRINTF(("%s: free inms 0x%llx\n", __func__,
                            (uint64_t)VM_KERNEL_ADDRPERM(lims)));
                        RB_REMOVE(ip_msource_tree, &imf->imf_sources, ims);
                        inms_free(lims);
                        imf->imf_nsrc--;
                }
        }
        imf->imf_st[1] = imf->imf_st[0];
}

/*
 * Mark socket-layer filter set as INCLUDE {} at t1.
 *
 * Caller is expected to be holding imo_lock.
 */
void
imf_leave(struct in_mfilter *imf)
{
        struct ip_msource       *ims;
        struct in_msource       *lims;

        RB_FOREACH(ims, ip_msource_tree, &imf->imf_sources) {
                lims = (struct in_msource *)ims;
                lims->imsl_st[1] = MCAST_UNDEFINED;
        }
        imf->imf_st[1] = MCAST_INCLUDE;
}

/*
 * Mark socket-layer filter set deltas as committed.
 *
 * Caller is expected to be holding imo_lock.
 */
static void
imf_commit(struct in_mfilter *imf)
{
        struct ip_msource       *ims;
        struct in_msource       *lims;

        RB_FOREACH(ims, ip_msource_tree, &imf->imf_sources) {
                lims = (struct in_msource *)ims;
                lims->imsl_st[0] = lims->imsl_st[1];
        }
        imf->imf_st[0] = imf->imf_st[1];
}

/*
 * Reap unreferenced sources from socket-layer filter set.
 *
 * Caller is expected to be holding imo_lock.
 */
static void
imf_reap(struct in_mfilter *imf)
{
        struct ip_msource       *ims, *tims;
        struct in_msource       *lims;

        RB_FOREACH_SAFE(ims, ip_msource_tree, &imf->imf_sources, tims) {
                lims = (struct in_msource *)ims;
                if ((lims->imsl_st[0] == MCAST_UNDEFINED) &&
                    (lims->imsl_st[1] == MCAST_UNDEFINED)) {
                        IGMP_PRINTF(("%s: free inms 0x%llx\n", __func__,
                            (uint64_t)VM_KERNEL_ADDRPERM(lims)));
                        RB_REMOVE(ip_msource_tree, &imf->imf_sources, ims);
                        inms_free(lims);
                        imf->imf_nsrc--;
                }
        }
}

/*
 * Purge socket-layer filter set.
 *
 * Caller is expected to be holding imo_lock.
 */
void
imf_purge(struct in_mfilter *imf)
{
        struct ip_msource       *ims, *tims;
        struct in_msource       *lims;

        RB_FOREACH_SAFE(ims, ip_msource_tree, &imf->imf_sources, tims) {
                lims = (struct in_msource *)ims;
                IGMP_PRINTF(("%s: free inms 0x%llx\n", __func__,
                    (uint64_t)VM_KERNEL_ADDRPERM(lims)));
                RB_REMOVE(ip_msource_tree, &imf->imf_sources, ims);
                inms_free(lims);
                imf->imf_nsrc--;
        }
        imf->imf_st[0] = imf->imf_st[1] = MCAST_UNDEFINED;
        VERIFY(RB_EMPTY(&imf->imf_sources));
}

/*
 * Look up a source filter entry for a multicast group.
 *
 * inm is the group descriptor to work with.
 * haddr is the host-byte-order IPv4 address to look up.
 * noalloc may be non-zero to suppress allocation of sources.
 * *pims will be set to the address of the retrieved or allocated source.
 *
 * Return 0 if successful, otherwise return a non-zero error code.
 */
static int
inm_get_source(struct in_multi *inm, const in_addr_t haddr,
    const int noalloc, struct ip_msource **pims)
{
        struct ip_msource        find;
        struct ip_msource       *ims, *nims;
#ifdef IGMP_DEBUG
        struct in_addr ia;
        char buf[MAX_IPv4_STR_LEN];
#endif
        INM_LOCK_ASSERT_HELD(inm);

        find.ims_haddr = haddr;
        ims = RB_FIND(ip_msource_tree, &inm->inm_srcs, &find);
        if (ims == NULL && !noalloc) {
                if (inm->inm_nsrc == in_mcast_maxgrpsrc)
                        return (ENOSPC);
                nims = ipms_alloc(M_WAITOK);
                if (nims == NULL)
                        return (ENOMEM);
                nims->ims_haddr = haddr;
                RB_INSERT(ip_msource_tree, &inm->inm_srcs, nims);
                ++inm->inm_nsrc;
                ims = nims;
#ifdef IGMP_DEBUG
                ia.s_addr = htonl(haddr);
                inet_ntop(AF_INET, &ia, buf, sizeof(buf));
                IGMP_PRINTF(("%s: allocated %s as 0x%llx\n", __func__,
                    buf, (uint64_t)VM_KERNEL_ADDRPERM(ims)));
#endif
        }

        *pims = ims;
        return (0);
}

/*
 * Helper function to derive the filter mode on a source entry
 * from its internal counters. Predicates are:
 *  A source is only excluded if all listeners exclude it.
 *  A source is only included if no listeners exclude it,
 *  and at least one listener includes it.
 * May be used by ifmcstat(8).
 */
uint8_t
ims_get_mode(const struct in_multi *inm, const struct ip_msource *ims,
    uint8_t t)
{
        INM_LOCK_ASSERT_HELD(__DECONST(struct in_multi *, inm));

        t = !!t;
        if (inm->inm_st[t].iss_ex > 0 &&
            inm->inm_st[t].iss_ex == ims->ims_st[t].ex)
                return (MCAST_EXCLUDE);
        else if (ims->ims_st[t].in > 0 && ims->ims_st[t].ex == 0)
                return (MCAST_INCLUDE);
        return (MCAST_UNDEFINED);
}

/*
 * Merge socket-layer source into IGMP-layer source.
 * If rollback is non-zero, perform the inverse of the merge.
 */
static void
ims_merge(struct ip_msource *ims, const struct in_msource *lims,
    const int rollback)
{
        int n = rollback ? -1 : 1;
#ifdef IGMP_DEBUG
        struct in_addr ia;

        ia.s_addr = htonl(ims->ims_haddr);
#endif

        if (lims->imsl_st[0] == MCAST_EXCLUDE) {
                IGMP_INET_PRINTF(ia,
                    ("%s: t1 ex -= %d on %s\n",
                    __func__, n, _igmp_inet_buf));
                ims->ims_st[1].ex -= n;
        } else if (lims->imsl_st[0] == MCAST_INCLUDE) {
                IGMP_INET_PRINTF(ia,
                    ("%s: t1 in -= %d on %s\n",
                    __func__, n, _igmp_inet_buf));
                ims->ims_st[1].in -= n;
        }

        if (lims->imsl_st[1] == MCAST_EXCLUDE) {
                IGMP_INET_PRINTF(ia,
                    ("%s: t1 ex += %d on %s\n",
                    __func__, n, _igmp_inet_buf));
                ims->ims_st[1].ex += n;
        } else if (lims->imsl_st[1] == MCAST_INCLUDE) {
                IGMP_INET_PRINTF(ia,
                    ("%s: t1 in += %d on %s\n",
                    __func__, n, _igmp_inet_buf));
                ims->ims_st[1].in += n;
        }
}

/*
 * Atomically update the global in_multi state, when a membership's
 * filter list is being updated in any way.
 *
 * imf is the per-inpcb-membership group filter pointer.
 * A fake imf may be passed for in-kernel consumers.
 *
 * XXX This is a candidate for a set-symmetric-difference style loop
 * which would eliminate the repeated lookup from root of ims nodes,
 * as they share the same key space.
 *
 * If any error occurred this function will back out of refcounts
 * and return a non-zero value.
 */
static int
inm_merge(struct in_multi *inm, /*const*/ struct in_mfilter *imf)
{
        struct ip_msource       *ims, *nims;
        struct in_msource       *lims;
        int                      schanged, error;
        int                      nsrc0, nsrc1;

        INM_LOCK_ASSERT_HELD(inm);

        schanged = 0;
        error = 0;
        nsrc1 = nsrc0 = 0;

        /*
         * Update the source filters first, as this may fail.
         * Maintain count of in-mode filters at t0, t1. These are
         * used to work out if we transition into ASM mode or not.
         * Maintain a count of source filters whose state was
         * actually modified by this operation.
         */
        RB_FOREACH(ims, ip_msource_tree, &imf->imf_sources) {
                lims = (struct in_msource *)ims;
                if (lims->imsl_st[0] == imf->imf_st[0]) nsrc0++;
                if (lims->imsl_st[1] == imf->imf_st[1]) nsrc1++;
                if (lims->imsl_st[0] == lims->imsl_st[1]) continue;
                error = inm_get_source(inm, lims->ims_haddr, 0, &nims);
                ++schanged;
                if (error)
                        break;
                ims_merge(nims, lims, 0);
        }
        if (error) {
                struct ip_msource *bims;

                RB_FOREACH_REVERSE_FROM(ims, ip_msource_tree, nims) {
                        lims = (struct in_msource *)ims;
                        if (lims->imsl_st[0] == lims->imsl_st[1])
                                continue;
                        (void) inm_get_source(inm, lims->ims_haddr, 1, &bims);
                        if (bims == NULL)
                                continue;
                        ims_merge(bims, lims, 1);
                }
                goto out_reap;
        }

        IGMP_PRINTF(("%s: imf filters in-mode: %d at t0, %d at t1\n",
            __func__, nsrc0, nsrc1));

        /* Handle transition between INCLUDE {n} and INCLUDE {} on socket. */
        if (imf->imf_st[0] == imf->imf_st[1] &&
            imf->imf_st[1] == MCAST_INCLUDE) {
                if (nsrc1 == 0) {
                        IGMP_PRINTF(("%s: --in on inm at t1\n", __func__));
                        --inm->inm_st[1].iss_in;
                }
        }

        /* Handle filter mode transition on socket. */
        if (imf->imf_st[0] != imf->imf_st[1]) {
                IGMP_PRINTF(("%s: imf transition %d to %d\n",
                    __func__, imf->imf_st[0], imf->imf_st[1]));

                if (imf->imf_st[0] == MCAST_EXCLUDE) {
                        IGMP_PRINTF(("%s: --ex on inm at t1\n", __func__));
                        --inm->inm_st[1].iss_ex;
                } else if (imf->imf_st[0] == MCAST_INCLUDE) {
                        IGMP_PRINTF(("%s: --in on inm at t1\n", __func__));
                        --inm->inm_st[1].iss_in;
                }

                if (imf->imf_st[1] == MCAST_EXCLUDE) {
                        IGMP_PRINTF(("%s: ex++ on inm at t1\n", __func__));
                        inm->inm_st[1].iss_ex++;
                } else if (imf->imf_st[1] == MCAST_INCLUDE && nsrc1 > 0) {
                        IGMP_PRINTF(("%s: in++ on inm at t1\n", __func__));
                        inm->inm_st[1].iss_in++;
                }
        }

        /*
         * Track inm filter state in terms of listener counts.
         * If there are any exclusive listeners, stack-wide
         * membership is exclusive.
         * Otherwise, if only inclusive listeners, stack-wide is inclusive.
         * If no listeners remain, state is undefined at t1,
         * and the IGMP lifecycle for this group should finish.
         */
        if (inm->inm_st[1].iss_ex > 0) {
                IGMP_PRINTF(("%s: transition to EX\n", __func__));
                inm->inm_st[1].iss_fmode = MCAST_EXCLUDE;
        } else if (inm->inm_st[1].iss_in > 0) {
                IGMP_PRINTF(("%s: transition to IN\n", __func__));
                inm->inm_st[1].iss_fmode = MCAST_INCLUDE;
        } else {
                IGMP_PRINTF(("%s: transition to UNDEF\n", __func__));
                inm->inm_st[1].iss_fmode = MCAST_UNDEFINED;
        }

        /* Decrement ASM listener count on transition out of ASM mode. */
        if (imf->imf_st[0] == MCAST_EXCLUDE && nsrc0 == 0) {
                if ((imf->imf_st[1] != MCAST_EXCLUDE) ||
                    (imf->imf_st[1] == MCAST_EXCLUDE && nsrc1 > 0)) {
                        IGMP_PRINTF(("%s: --asm on inm at t1\n", __func__));
                        --inm->inm_st[1].iss_asm;
                }
        }

        /* Increment ASM listener count on transition to ASM mode. */
        if (imf->imf_st[1] == MCAST_EXCLUDE && nsrc1 == 0) {
                IGMP_PRINTF(("%s: asm++ on inm at t1\n", __func__));
                inm->inm_st[1].iss_asm++;
        }

        IGMP_PRINTF(("%s: merged imf 0x%llx to inm 0x%llx\n", __func__,
            (uint64_t)VM_KERNEL_ADDRPERM(imf),
            (uint64_t)VM_KERNEL_ADDRPERM(inm)));
        inm_print(inm);

out_reap:
        if (schanged > 0) {
                IGMP_PRINTF(("%s: sources changed; reaping\n", __func__));
                inm_reap(inm);
        }
        return (error);
}

/*
 * Mark an in_multi's filter set deltas as committed.
 * Called by IGMP after a state change has been enqueued.
 */
void
inm_commit(struct in_multi *inm)
{
        struct ip_msource       *ims;

        INM_LOCK_ASSERT_HELD(inm);

        IGMP_PRINTF(("%s: commit inm 0x%llx\n", __func__,
            (uint64_t)VM_KERNEL_ADDRPERM(inm)));
        IGMP_PRINTF(("%s: pre commit:\n", __func__));
        inm_print(inm);

        RB_FOREACH(ims, ip_msource_tree, &inm->inm_srcs) {
                ims->ims_st[0] = ims->ims_st[1];
        }
        inm->inm_st[0] = inm->inm_st[1];
}

/*
 * Reap unreferenced nodes from an in_multi's filter set.
 */
static void
inm_reap(struct in_multi *inm)
{
        struct ip_msource       *ims, *tims;

        INM_LOCK_ASSERT_HELD(inm);

        RB_FOREACH_SAFE(ims, ip_msource_tree, &inm->inm_srcs, tims) {
                if (ims->ims_st[0].ex > 0 || ims->ims_st[0].in > 0 ||
                    ims->ims_st[1].ex > 0 || ims->ims_st[1].in > 0 ||
                    ims->ims_stp != 0)
                        continue;
                IGMP_PRINTF(("%s: free ims 0x%llx\n", __func__,
                    (uint64_t)VM_KERNEL_ADDRPERM(ims)));
                RB_REMOVE(ip_msource_tree, &inm->inm_srcs, ims);
                ipms_free(ims);
                inm->inm_nsrc--;
        }
}

/*
 * Purge all source nodes from an in_multi's filter set.
 */
void
inm_purge(struct in_multi *inm)
{
        struct ip_msource       *ims, *tims;

        INM_LOCK_ASSERT_HELD(inm);

        RB_FOREACH_SAFE(ims, ip_msource_tree, &inm->inm_srcs, tims) {
                IGMP_PRINTF(("%s: free ims 0x%llx\n", __func__,
                    (uint64_t)VM_KERNEL_ADDRPERM(ims)));
                RB_REMOVE(ip_msource_tree, &inm->inm_srcs, ims);
                ipms_free(ims);
                inm->inm_nsrc--;
        }
}

/*
 * Join a multicast group; real entry point.
 *
 * Only preserves atomicity at inm level.
 * NOTE: imf argument cannot be const due to sys/tree.h limitations.
 *
 * If the IGMP downcall fails, the group is not joined, and an error
 * code is returned.
 */
static int
in_joingroup(struct ifnet *ifp, const struct in_addr *gina,
    /*const*/ struct in_mfilter *imf, struct in_multi **pinm)
{
        struct in_mfilter        timf;
        struct in_multi         *inm = NULL;
        int                      error = 0;
        struct igmp_tparams      itp;

        IGMP_INET_PRINTF(*gina, ("%s: join %s on 0x%llx(%s))\n", __func__,
            _igmp_inet_buf, (uint64_t)VM_KERNEL_ADDRPERM(ifp), if_name(ifp)));

        bzero(&itp, sizeof (itp));
        *pinm = NULL;

        /*
         * If no imf was specified (i.e. kernel consumer),
         * fake one up and assume it is an ASM join.
         */
        if (imf == NULL) {
                imf_init(&timf, MCAST_UNDEFINED, MCAST_EXCLUDE);
                imf = &timf;
        }

        error = in_getmulti(ifp, gina, &inm);
        if (error) {
                IGMP_PRINTF(("%s: in_getmulti() failure\n", __func__));
                return (error);
        }

        IGMP_PRINTF(("%s: merge inm state\n", __func__));

        INM_LOCK(inm);
        error = inm_merge(inm, imf);
        if (error) {
                IGMP_PRINTF(("%s: failed to merge inm state\n", __func__));
                goto out_inm_release;
        }

        IGMP_PRINTF(("%s: doing igmp downcall\n", __func__));
        error = igmp_change_state(inm, &itp);
        if (error) {
                IGMP_PRINTF(("%s: failed to update source\n", __func__));
                imf_rollback(imf);
                goto out_inm_release;
        }

out_inm_release:
        if (error) {
                IGMP_PRINTF(("%s: dropping ref on 0x%llx\n", __func__,
                    (uint64_t)VM_KERNEL_ADDRPERM(inm)));
                INM_UNLOCK(inm);
                INM_REMREF(inm);
        } else {
                INM_UNLOCK(inm);
                *pinm = inm;    /* keep refcount from in_getmulti() */
        }

        /* schedule timer now that we've dropped the lock(s) */
        igmp_set_timeout(&itp);

        return (error);
}

/*
 * Leave a multicast group; real entry point.
 * All source filters will be expunged.
 *
 * Only preserves atomicity at inm level.
 *
 * Note: This is not the same as inm_release(*) as this function also
 * makes a state change downcall into IGMP.
 */
int
in_leavegroup(struct in_multi *inm, /*const*/ struct in_mfilter *imf)
{
        struct in_mfilter        timf;
        int                      error, lastref;
        struct igmp_tparams      itp;

        bzero(&itp, sizeof (itp));
        error = 0;

        INM_LOCK_ASSERT_NOTHELD(inm);

        in_multihead_lock_exclusive();
        INM_LOCK(inm);

        IGMP_INET_PRINTF(inm->inm_addr,
            ("%s: leave inm 0x%llx, %s/%s%d, imf 0x%llx\n", __func__,
            (uint64_t)VM_KERNEL_ADDRPERM(inm), _igmp_inet_buf,
            (inm_is_ifp_detached(inm) ? "null" : inm->inm_ifp->if_name),
            inm->inm_ifp->if_unit, (uint64_t)VM_KERNEL_ADDRPERM(imf)));

        /*
         * If no imf was specified (i.e. kernel consumer),
         * fake one up and assume it is an ASM join.
         */
        if (imf == NULL) {
                imf_init(&timf, MCAST_EXCLUDE, MCAST_UNDEFINED);
                imf = &timf;
        }

        /*
         * Begin state merge transaction at IGMP layer.
         *
         * As this particular invocation should not cause any memory
         * to be allocated, and there is no opportunity to roll back
         * the transaction, it MUST NOT fail.
         */
        IGMP_PRINTF(("%s: merge inm state\n", __func__));

        error = inm_merge(inm, imf);
        KASSERT(error == 0, ("%s: failed to merge inm state\n", __func__));

        IGMP_PRINTF(("%s: doing igmp downcall\n", __func__));
        error = igmp_change_state(inm, &itp);
#if IGMP_DEBUG
        if (error)
                IGMP_PRINTF(("%s: failed igmp downcall\n", __func__));
#endif
        lastref = in_multi_detach(inm);
        VERIFY(!lastref || (!(inm->inm_debug & IFD_ATTACHED) &&
            inm->inm_reqcnt == 0));
        INM_UNLOCK(inm);
        in_multihead_lock_done();

        if (lastref)
                INM_REMREF(inm);        /* for in_multihead list */

        /* schedule timer now that we've dropped the lock(s) */
        igmp_set_timeout(&itp);

        return (error);
}

/*
 * Join an IPv4 multicast group in (*,G) exclusive mode.
 * The group must be a 224.0.0.0/24 link-scope group.
 * This KPI is for legacy kernel consumers only.
 */
struct in_multi *
in_addmulti(struct in_addr *ap, struct ifnet *ifp)
{
        struct in_multi *pinm = NULL;
        int error;

        KASSERT(IN_LOCAL_GROUP(ntohl(ap->s_addr)),
            ("%s: %s not in 224.0.0.0/24\n", __func__, inet_ntoa(*ap)));

        error = in_joingroup(ifp, ap, NULL, &pinm);
        VERIFY(pinm != NULL || error != 0);

        return (pinm);
}

/*
 * Leave an IPv4 multicast group, assumed to be in exclusive (*,G) mode.
 * This KPI is for legacy kernel consumers only.
 */
void
in_delmulti(struct in_multi *inm)
{

        (void) in_leavegroup(inm, NULL);
}

/*
 * Block or unblock an ASM multicast source on an inpcb.
 * This implements the delta-based API described in RFC 3678.
 *
 * The delta-based API applies only to exclusive-mode memberships.
 * An IGMP downcall will be performed.
 *
 * Return 0 if successful, otherwise return an appropriate error code.
 */
static int
inp_block_unblock_source(struct inpcb *inp, struct sockopt *sopt)
{
        struct group_source_req          gsr;
        sockunion_t                     *gsa, *ssa;
        struct ifnet                    *ifp;
        struct in_mfilter               *imf;
        struct ip_moptions              *imo;
        struct in_msource               *ims;
        struct in_multi                 *inm;
        size_t                           idx;
        uint16_t                         fmode;
        int                              error, doblock;
        unsigned int                     ifindex = 0;
        struct igmp_tparams              itp;

        bzero(&itp, sizeof (itp));
        ifp = NULL;
        error = 0;
        doblock = 0;

        memset(&gsr, 0, sizeof(struct group_source_req));
        gsa = (sockunion_t *)&gsr.gsr_group;
        ssa = (sockunion_t *)&gsr.gsr_source;

        switch (sopt->sopt_name) {
        case IP_BLOCK_SOURCE:
        case IP_UNBLOCK_SOURCE: {
                struct ip_mreq_source    mreqs;

                error = sooptcopyin(sopt, &mreqs,
                    sizeof(struct ip_mreq_source),
                    sizeof(struct ip_mreq_source));
                if (error)
                        return (error);

                gsa->sin.sin_family = AF_INET;
                gsa->sin.sin_len = sizeof(struct sockaddr_in);
                gsa->sin.sin_addr = mreqs.imr_multiaddr;

                ssa->sin.sin_family = AF_INET;
                ssa->sin.sin_len = sizeof(struct sockaddr_in);
                ssa->sin.sin_addr = mreqs.imr_sourceaddr;

                if (!in_nullhost(mreqs.imr_interface))
                        ifp = ip_multicast_if(&mreqs.imr_interface, &ifindex);

                if (sopt->sopt_name == IP_BLOCK_SOURCE)
                        doblock = 1;

                IGMP_INET_PRINTF(mreqs.imr_interface,
                    ("%s: imr_interface = %s, ifp = 0x%llx\n", __func__,
                    _igmp_inet_buf, (uint64_t)VM_KERNEL_ADDRPERM(ifp)));
                break;
            }

        case MCAST_BLOCK_SOURCE:
        case MCAST_UNBLOCK_SOURCE:
                error = sooptcopyin(sopt, &gsr,
                    sizeof(struct group_source_req),
                    sizeof(struct group_source_req));
                if (error)
                        return (error);

                if (gsa->sin.sin_family != AF_INET ||
                    gsa->sin.sin_len != sizeof(struct sockaddr_in))
                        return (EINVAL);

                if (ssa->sin.sin_family != AF_INET ||
                    ssa->sin.sin_len != sizeof(struct sockaddr_in))
                        return (EINVAL);

                ifnet_head_lock_shared();
                if (gsr.gsr_interface == 0 ||
                    (u_int)if_index < gsr.gsr_interface) {
                        ifnet_head_done();
                        return (EADDRNOTAVAIL);
                }

                ifp = ifindex2ifnet[gsr.gsr_interface];
                ifnet_head_done();

                if (ifp == NULL)
                        return (EADDRNOTAVAIL);

                if (sopt->sopt_name == MCAST_BLOCK_SOURCE)
                        doblock = 1;
                break;

        default:
                IGMP_PRINTF(("%s: unknown sopt_name %d\n",
                    __func__, sopt->sopt_name));
                return (EOPNOTSUPP);
                break;
        }

        if (!IN_MULTICAST(ntohl(gsa->sin.sin_addr.s_addr)))
                return (EINVAL);

        /*
         * Check if we are actually a member of this group.
         */
        imo = inp_findmoptions(inp);
        if (imo == NULL)
                return (ENOMEM);

        IMO_LOCK(imo);
        idx = imo_match_group(imo, ifp, &gsa->sa);
        if (idx == (size_t)-1 || imo->imo_mfilters == NULL) {
                error = EADDRNOTAVAIL;
                goto out_imo_locked;
        }

        VERIFY(imo->imo_mfilters != NULL);
        imf = &imo->imo_mfilters[idx];
        inm = imo->imo_membership[idx];

        /*
         * Attempting to use the delta-based API on an
         * non exclusive-mode membership is an error.
         */
        fmode = imf->imf_st[0];
        if (fmode != MCAST_EXCLUDE) {
                error = EINVAL;
                goto out_imo_locked;
        }

        /*
         * Deal with error cases up-front:
         *  Asked to block, but already blocked; or
         *  Asked to unblock, but nothing to unblock.
         * If adding a new block entry, allocate it.
         */
        ims = imo_match_source(imo, idx, &ssa->sa);
        if ((ims != NULL && doblock) || (ims == NULL && !doblock)) {
                IGMP_INET_PRINTF(ssa->sin.sin_addr,
                    ("%s: source %s %spresent\n", __func__,
                    _igmp_inet_buf, doblock ? "" : "not "));
                error = EADDRNOTAVAIL;
                goto out_imo_locked;
        }

        /*
         * Begin state merge transaction at socket layer.
         */
        if (doblock) {
                IGMP_PRINTF(("%s: %s source\n", __func__, "block"));
                ims = imf_graft(imf, fmode, &ssa->sin);
                if (ims == NULL)
                        error = ENOMEM;
        } else {
                IGMP_PRINTF(("%s: %s source\n", __func__, "allow"));
                error = imf_prune(imf, &ssa->sin);
        }

        if (error) {
                IGMP_PRINTF(("%s: merge imf state failed\n", __func__));
                goto out_imf_rollback;
        }

        /*
         * Begin state merge transaction at IGMP layer.
         */
        INM_LOCK(inm);
        IGMP_PRINTF(("%s: merge inm state\n", __func__));
        error = inm_merge(inm, imf);
        if (error) {
                IGMP_PRINTF(("%s: failed to merge inm state\n", __func__));
                INM_UNLOCK(inm);
                goto out_imf_rollback;
        }

        IGMP_PRINTF(("%s: doing igmp downcall\n", __func__));
        error = igmp_change_state(inm, &itp);
        INM_UNLOCK(inm);
#if IGMP_DEBUG
        if (error)
                IGMP_PRINTF(("%s: failed igmp downcall\n", __func__));
#endif

out_imf_rollback:
        if (error)
                imf_rollback(imf);
        else
                imf_commit(imf);

        imf_reap(imf);

out_imo_locked:
        IMO_UNLOCK(imo);
        IMO_REMREF(imo);        /* from inp_findmoptions() */

        /* schedule timer now that we've dropped the lock(s) */
        igmp_set_timeout(&itp);

        return (error);
}

/*
 * Given an inpcb, return its multicast options structure pointer.
 *
 * Caller is responsible for locking the inpcb, and releasing the
 * extra reference held on the imo, upon a successful return.
 */
static struct ip_moptions *
inp_findmoptions(struct inpcb *inp)
{
        struct ip_moptions       *imo;
        struct in_multi         **immp;
        struct in_mfilter        *imfp;
        size_t                    idx;

        if ((imo = inp->inp_moptions) != NULL) {
                IMO_ADDREF(imo);        /* for caller */
                return (imo);
        }

        imo = ip_allocmoptions(M_WAITOK);
        if (imo == NULL)
                return (NULL);

        immp = _MALLOC(sizeof (*immp) * IP_MIN_MEMBERSHIPS, M_IPMOPTS,
            M_WAITOK | M_ZERO);
        if (immp == NULL) {
                IMO_REMREF(imo);
                return (NULL);
        }

        imfp = _MALLOC(sizeof (struct in_mfilter) * IP_MIN_MEMBERSHIPS,
            M_INMFILTER, M_WAITOK | M_ZERO);
        if (imfp == NULL) {
                _FREE(immp, M_IPMOPTS);
                IMO_REMREF(imo);
                return (NULL);
        }

        imo->imo_multicast_ifp = NULL;
        imo->imo_multicast_addr.s_addr = INADDR_ANY;
        imo->imo_multicast_vif = -1;
        imo->imo_multicast_ttl = IP_DEFAULT_MULTICAST_TTL;
        imo->imo_multicast_loop = in_mcast_loop;
        imo->imo_num_memberships = 0;
        imo->imo_max_memberships = IP_MIN_MEMBERSHIPS;
        imo->imo_membership = immp;

        /* Initialize per-group source filters. */
        for (idx = 0; idx < IP_MIN_MEMBERSHIPS; idx++)
                imf_init(&imfp[idx], MCAST_UNDEFINED, MCAST_EXCLUDE);

        imo->imo_mfilters = imfp;
        inp->inp_moptions = imo; /* keep reference from ip_allocmoptions() */
        IMO_ADDREF(imo);        /* for caller */

        return (imo);
}
/*
 * Atomically get source filters on a socket for an IPv4 multicast group.
 */
static int
inp_get_source_filters(struct inpcb *inp, struct sockopt *sopt)
{
        struct __msfilterreq64  msfr, msfr64;
        struct __msfilterreq32  msfr32;
        sockunion_t             *gsa;
        struct ifnet            *ifp;
        struct ip_moptions      *imo;
        struct in_mfilter       *imf;
        struct ip_msource       *ims;
        struct in_msource       *lims;
        struct sockaddr_in      *psin;
        struct sockaddr_storage *ptss;
        struct sockaddr_storage *tss;
        int                      error;
        size_t                   idx, nsrcs, ncsrcs;
        user_addr_t              tmp_ptr;

        imo = inp->inp_moptions;
        VERIFY(imo != NULL);

        if (IS_64BIT_PROCESS(current_proc())) {
                error = sooptcopyin(sopt, &msfr64,
                    sizeof(struct __msfilterreq64),
                    sizeof(struct __msfilterreq64));
                if (error)
                        return (error);
                /* we never use msfr.msfr_srcs; */
                memcpy(&msfr, &msfr64, sizeof(msfr));
        } else {
                error = sooptcopyin(sopt, &msfr32,
                    sizeof(struct __msfilterreq32),
                    sizeof(struct __msfilterreq32));
                if (error)
                        return (error);
                /* we never use msfr.msfr_srcs; */
                memcpy(&msfr, &msfr32, sizeof(msfr));
        }

        ifnet_head_lock_shared();
        if (msfr.msfr_ifindex == 0 || (u_int)if_index < msfr.msfr_ifindex) {
                ifnet_head_done();
                return (EADDRNOTAVAIL);
        }

        ifp = ifindex2ifnet[msfr.msfr_ifindex];
        ifnet_head_done();

        if (ifp == NULL)
                return (EADDRNOTAVAIL);

        if ((size_t) msfr.msfr_nsrcs >
            UINT32_MAX / sizeof(struct sockaddr_storage))
                msfr.msfr_nsrcs = UINT32_MAX / sizeof(struct sockaddr_storage);

        if (msfr.msfr_nsrcs > in_mcast_maxsocksrc)
                msfr.msfr_nsrcs = in_mcast_maxsocksrc;

        IMO_LOCK(imo);
        /*
         * Lookup group on the socket.
         */
        gsa = (sockunion_t *)&msfr.msfr_group;
        idx = imo_match_group(imo, ifp, &gsa->sa);
        if (idx == (size_t)-1 || imo->imo_mfilters == NULL) {
                IMO_UNLOCK(imo);
                return (EADDRNOTAVAIL);
        }
        imf = &imo->imo_mfilters[idx];

        /*
         * Ignore memberships which are in limbo.
         */
        if (imf->imf_st[1] == MCAST_UNDEFINED) {
                IMO_UNLOCK(imo);
                return (EAGAIN);
        }
        msfr.msfr_fmode = imf->imf_st[1];

        /*
         * If the user specified a buffer, copy out the source filter
         * entries to userland gracefully.
         * We only copy out the number of entries which userland
         * has asked for, but we always tell userland how big the
         * buffer really needs to be.
         */

        if (IS_64BIT_PROCESS(current_proc())) 
                tmp_ptr = msfr64.msfr_srcs;
        else
                tmp_ptr = CAST_USER_ADDR_T(msfr32.msfr_srcs);

        tss = NULL;
        if (tmp_ptr != USER_ADDR_NULL && msfr.msfr_nsrcs > 0) {
                tss = _MALLOC((size_t) msfr.msfr_nsrcs * sizeof(*tss),
                    M_TEMP, M_WAITOK | M_ZERO);
                if (tss == NULL) {
                        IMO_UNLOCK(imo);
                        return (ENOBUFS);
                }
                bzero(tss, (size_t) msfr.msfr_nsrcs * sizeof(*tss));
        }

        /*
         * Count number of sources in-mode at t0.
         * If buffer space exists and remains, copy out source entries.
         */
        nsrcs = msfr.msfr_nsrcs;
        ncsrcs = 0;
        ptss = tss;
        RB_FOREACH(ims, ip_msource_tree, &imf->imf_sources) {
                lims = (struct in_msource *)ims;
                if (lims->imsl_st[0] == MCAST_UNDEFINED ||
                    lims->imsl_st[0] != imf->imf_st[0])
                        continue;
                if (tss != NULL && nsrcs > 0) {
                        psin = (struct sockaddr_in *)ptss;
                        psin->sin_family = AF_INET;
                        psin->sin_len = sizeof(struct sockaddr_in);
                        psin->sin_addr.s_addr = htonl(lims->ims_haddr);
                        psin->sin_port = 0;
                        ++ptss;
                        --nsrcs;
                        ++ncsrcs;
                }
        }

        IMO_UNLOCK(imo);

        if (tss != NULL) {
                error = copyout(tss, tmp_ptr, ncsrcs * sizeof(*tss));
                FREE(tss, M_TEMP);
                if (error)
                        return (error);
        }

        msfr.msfr_nsrcs = ncsrcs;
        if (IS_64BIT_PROCESS(current_proc())) {
                msfr64.msfr_ifindex = msfr.msfr_ifindex;
                msfr64.msfr_fmode   = msfr.msfr_fmode;
                msfr64.msfr_nsrcs   = msfr.msfr_nsrcs;
                memcpy(&msfr64.msfr_group, &msfr.msfr_group,
                    sizeof(struct sockaddr_storage));
                error = sooptcopyout(sopt, &msfr64,
                    sizeof(struct __msfilterreq64));
        } else {
                msfr32.msfr_ifindex = msfr.msfr_ifindex;
                msfr32.msfr_fmode   = msfr.msfr_fmode;
                msfr32.msfr_nsrcs   = msfr.msfr_nsrcs;
                memcpy(&msfr64.msfr_group, &msfr.msfr_group,
                    sizeof(struct sockaddr_storage));
                error = sooptcopyout(sopt, &msfr32,
                    sizeof(struct __msfilterreq32));
        }

        return (error);
}

/*
 * Return the IP multicast options in response to user getsockopt().
 */
int
inp_getmoptions(struct inpcb *inp, struct sockopt *sopt)
{
        struct ip_mreqn          mreqn;
        struct ip_moptions      *imo;
        struct ifnet            *ifp;
        struct in_ifaddr        *ia;
        int                      error, optval;
        unsigned int             ifindex;
        u_char                   coptval;

        imo = inp->inp_moptions;
        /*
         * If socket is neither of type SOCK_RAW or SOCK_DGRAM,
         * or is a divert socket, reject it.
         */
        if (SOCK_PROTO(inp->inp_socket) == IPPROTO_DIVERT ||
            (SOCK_TYPE(inp->inp_socket) != SOCK_RAW &&
            SOCK_TYPE(inp->inp_socket) != SOCK_DGRAM)) {
                return (EOPNOTSUPP);
        }

        error = 0;
        switch (sopt->sopt_name) {
#ifdef MROUTING
        case IP_MULTICAST_VIF:
                if (imo != NULL) {
                        IMO_LOCK(imo);
                        optval = imo->imo_multicast_vif;
                        IMO_UNLOCK(imo);
                } else
                        optval = -1;
                error = sooptcopyout(sopt, &optval, sizeof(int));
                break;
#endif /* MROUTING */

        case IP_MULTICAST_IF:
                memset(&mreqn, 0, sizeof(struct ip_mreqn));
                if (imo != NULL) {
                        IMO_LOCK(imo);
                        ifp = imo->imo_multicast_ifp;
                        if (!in_nullhost(imo->imo_multicast_addr)) {
                                mreqn.imr_address = imo->imo_multicast_addr;
                        } else if (ifp != NULL) {
                                mreqn.imr_ifindex = ifp->if_index;
                                IFP_TO_IA(ifp, ia);
                                if (ia != NULL) {
                                        IFA_LOCK_SPIN(&ia->ia_ifa);
                                        mreqn.imr_address =
                                            IA_SIN(ia)->sin_addr;
                                        IFA_UNLOCK(&ia->ia_ifa);
                                        IFA_REMREF(&ia->ia_ifa);
                                }
                        }
                        IMO_UNLOCK(imo);
                }
                if (sopt->sopt_valsize == sizeof(struct ip_mreqn)) {
                        error = sooptcopyout(sopt, &mreqn,
                            sizeof(struct ip_mreqn));
                } else {
                        error = sooptcopyout(sopt, &mreqn.imr_address,
                            sizeof(struct in_addr));
                }
                break;

        case IP_MULTICAST_IFINDEX:
                if (imo != NULL)
                        IMO_LOCK(imo);
                if (imo == NULL || imo->imo_multicast_ifp == NULL) {
                        ifindex = 0;
                } else {
                        ifindex = imo->imo_multicast_ifp->if_index;
                }
                if (imo != NULL)
                        IMO_UNLOCK(imo);
                error = sooptcopyout(sopt, &ifindex, sizeof (ifindex));
                break;

        case IP_MULTICAST_TTL:
                if (imo == NULL) 
                        optval = coptval = IP_DEFAULT_MULTICAST_TTL;
                else {
                        IMO_LOCK(imo);
                        optval = coptval = imo->imo_multicast_ttl;
                        IMO_UNLOCK(imo);
                }
                if (sopt->sopt_valsize == sizeof(u_char))
                        error = sooptcopyout(sopt, &coptval, sizeof(u_char));
                else
                        error = sooptcopyout(sopt, &optval, sizeof(int));
                break;

        case IP_MULTICAST_LOOP:
                if (imo == 0)
                        optval = coptval = IP_DEFAULT_MULTICAST_LOOP;
                else {
                        IMO_LOCK(imo);
                        optval = coptval = imo->imo_multicast_loop;
                        IMO_UNLOCK(imo);
                }
                if (sopt->sopt_valsize == sizeof(u_char))
                        error = sooptcopyout(sopt, &coptval, sizeof(u_char));
                else
                        error = sooptcopyout(sopt, &optval, sizeof(int));
                break;

        case IP_MSFILTER:
                if (imo == NULL) {
                        error = EADDRNOTAVAIL;
                } else {
                        error = inp_get_source_filters(inp, sopt);
                }
                break;

        default:
                error = ENOPROTOOPT;
                break;
        }

        return (error);
}

/*
 * Look up the ifnet to use for a multicast group membership,
 * given the IPv4 address of an interface, and the IPv4 group address.
 *
 * This routine exists to support legacy multicast applications
 * which do not understand that multicast memberships are scoped to
 * specific physical links in the networking stack, or which need
 * to join link-scope groups before IPv4 addresses are configured.
 *
 * If inp is non-NULL and is bound to an interface, use this socket's
 * inp_boundif for any required routing table lookup.
 *
 * If the route lookup fails, attempt to use the first non-loopback
 * interface with multicast capability in the system as a
 * last resort. The legacy IPv4 ASM API requires that we do
 * this in order to allow groups to be joined when the routing
 * table has not yet been populated during boot.
 *
 * Returns NULL if no ifp could be found.
 *
 */
static struct ifnet *
inp_lookup_mcast_ifp(const struct inpcb *inp,
    const struct sockaddr_in *gsin, const struct in_addr ina)
{
        struct ifnet    *ifp;
        unsigned int     ifindex = 0;

        VERIFY(gsin->sin_family == AF_INET);
        VERIFY(IN_MULTICAST(ntohl(gsin->sin_addr.s_addr)));

        ifp = NULL;
        if (!in_nullhost(ina)) {
                struct in_addr new_ina;
                memcpy(&new_ina, &ina, sizeof(struct in_addr));
                ifp = ip_multicast_if(&new_ina, &ifindex);
        } else {
                struct route ro;
                unsigned int ifscope = IFSCOPE_NONE;

                if (inp != NULL && (inp->inp_flags & INP_BOUND_IF))
                        ifscope = inp->inp_boundifp->if_index;

                bzero(&ro, sizeof (ro));
                memcpy(&ro.ro_dst, gsin, sizeof(struct sockaddr_in));
                rtalloc_scoped_ign(&ro, 0, ifscope);
                if (ro.ro_rt != NULL) {
                        ifp = ro.ro_rt->rt_ifp;
                        VERIFY(ifp != NULL);
                } else {
                        struct in_ifaddr *ia;
                        struct ifnet *mifp;

                        mifp = NULL;
                        lck_rw_lock_shared(in_ifaddr_rwlock);
                        TAILQ_FOREACH(ia, &in_ifaddrhead, ia_link) {
                                IFA_LOCK_SPIN(&ia->ia_ifa);
                                mifp = ia->ia_ifp;
                                IFA_UNLOCK(&ia->ia_ifa);
                                if (!(mifp->if_flags & IFF_LOOPBACK) &&
                                     (mifp->if_flags & IFF_MULTICAST)) {
                                        ifp = mifp;
                                        break;
                                }
                        }
                        lck_rw_done(in_ifaddr_rwlock);
                }
                ROUTE_RELEASE(&ro);
        }

        return (ifp);
}

/*
 * Join an IPv4 multicast group, possibly with a source.
 *
 * NB: sopt->sopt_val might point to the kernel address space. This means that
 * we were called by the IPv6 stack due to the presence of an IPv6 v4 mapped
 * address. In this scenario, sopt_p points to kernproc and sooptcopyin() will
 * just issue an in-kernel memcpy.
 */
int
inp_join_group(struct inpcb *inp, struct sockopt *sopt)
{
        struct group_source_req          gsr;
        sockunion_t                     *gsa, *ssa;
        struct ifnet                    *ifp;
        struct in_mfilter               *imf;
        struct ip_moptions              *imo;
        struct in_multi                 *inm = NULL;
        struct in_msource               *lims;
        size_t                           idx;
        int                              error, is_new;
        struct igmp_tparams              itp;

        bzero(&itp, sizeof (itp));
        ifp = NULL;
        imf = NULL;
        error = 0;
        is_new = 0;

        memset(&gsr, 0, sizeof(struct group_source_req));
        gsa = (sockunion_t *)&gsr.gsr_group;
        gsa->ss.ss_family = AF_UNSPEC;
        ssa = (sockunion_t *)&gsr.gsr_source;
        ssa->ss.ss_family = AF_UNSPEC;

        switch (sopt->sopt_name) {
        case IP_ADD_MEMBERSHIP:
        case IP_ADD_SOURCE_MEMBERSHIP: {
                struct ip_mreq_source    mreqs;

                if (sopt->sopt_name == IP_ADD_MEMBERSHIP) {
                        error = sooptcopyin(sopt, &mreqs,
                            sizeof(struct ip_mreq),
                            sizeof(struct ip_mreq));
                        /*
                         * Do argument switcharoo from ip_mreq into
                         * ip_mreq_source to avoid using two instances.
                         */
                        mreqs.imr_interface = mreqs.imr_sourceaddr;
                        mreqs.imr_sourceaddr.s_addr = INADDR_ANY;
                } else if (sopt->sopt_name == IP_ADD_SOURCE_MEMBERSHIP) {
                        error = sooptcopyin(sopt, &mreqs,
                            sizeof(struct ip_mreq_source),
                            sizeof(struct ip_mreq_source));
                }
                if (error) {
                        IGMP_PRINTF(("%s: error copyin IP_ADD_MEMBERSHIP/"
                            "IP_ADD_SOURCE_MEMBERSHIP %d err=%d\n",
                            __func__, sopt->sopt_name, error));
                        return (error);
                }

                gsa->sin.sin_family = AF_INET;
                gsa->sin.sin_len = sizeof(struct sockaddr_in);
                gsa->sin.sin_addr = mreqs.imr_multiaddr;

                if (sopt->sopt_name == IP_ADD_SOURCE_MEMBERSHIP) {
                        ssa->sin.sin_family = AF_INET;
                        ssa->sin.sin_len = sizeof(struct sockaddr_in);
                        ssa->sin.sin_addr = mreqs.imr_sourceaddr;
                }

                if (!IN_MULTICAST(ntohl(gsa->sin.sin_addr.s_addr)))
                        return (EINVAL);

                ifp = inp_lookup_mcast_ifp(inp, &gsa->sin,
                    mreqs.imr_interface);
                IGMP_INET_PRINTF(mreqs.imr_interface,
                    ("%s: imr_interface = %s, ifp = 0x%llx\n", __func__,
                    _igmp_inet_buf, (uint64_t)VM_KERNEL_ADDRPERM(ifp)));
                break;
        }

        case MCAST_JOIN_GROUP:
        case MCAST_JOIN_SOURCE_GROUP:
                if (sopt->sopt_name == MCAST_JOIN_GROUP) {
                        error = sooptcopyin(sopt, &gsr,
                            sizeof(struct group_req),
                            sizeof(struct group_req));
                } else if (sopt->sopt_name == MCAST_JOIN_SOURCE_GROUP) {
                        error = sooptcopyin(sopt, &gsr,
                            sizeof(struct group_source_req),
                            sizeof(struct group_source_req));
                }
                if (error)
                        return (error);

                if (gsa->sin.sin_family != AF_INET ||
                    gsa->sin.sin_len != sizeof(struct sockaddr_in))
                        return (EINVAL);

                /*
                 * Overwrite the port field if present, as the sockaddr
                 * being copied in may be matched with a binary comparison.
                 */
                gsa->sin.sin_port = 0;
                if (sopt->sopt_name == MCAST_JOIN_SOURCE_GROUP) {
                        if (ssa->sin.sin_family != AF_INET ||
                            ssa->sin.sin_len != sizeof(struct sockaddr_in))
                                return (EINVAL);
                        ssa->sin.sin_port = 0;
                }

                if (!IN_MULTICAST(ntohl(gsa->sin.sin_addr.s_addr)))
                        return (EINVAL);

                ifnet_head_lock_shared();
                if (gsr.gsr_interface == 0 ||
                    (u_int)if_index < gsr.gsr_interface) {
                        ifnet_head_done();
                        return (EADDRNOTAVAIL);
                }
                ifp = ifindex2ifnet[gsr.gsr_interface];
                ifnet_head_done();

                break;

        default:
                IGMP_PRINTF(("%s: unknown sopt_name %d\n",
                    __func__, sopt->sopt_name));
                return (EOPNOTSUPP);
                break;
        }

        if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0)
                return (EADDRNOTAVAIL);

        imo = inp_findmoptions(inp);
        if (imo == NULL)
                return (ENOMEM);

        IMO_LOCK(imo);
        idx = imo_match_group(imo, ifp, &gsa->sa);
        if (idx == (size_t)-1) {
                is_new = 1;
        } else {
                inm = imo->imo_membership[idx];
                imf = &imo->imo_mfilters[idx];
                if (ssa->ss.ss_family != AF_UNSPEC) {
                        /*
                         * MCAST_JOIN_SOURCE_GROUP on an exclusive membership
                         * is an error. On an existing inclusive membership,
                         * it just adds the source to the filter list.
                         */
                        if (imf->imf_st[1] != MCAST_INCLUDE) {
                                error = EINVAL;
                                goto out_imo_locked;
                        }
                        /*
                         * Throw out duplicates.
                         *
                         * XXX FIXME: This makes a naive assumption that
                         * even if entries exist for *ssa in this imf,
                         * they will be rejected as dupes, even if they
                         * are not valid in the current mode (in-mode).
                         *
                         * in_msource is transactioned just as for anything
                         * else in SSM -- but note naive use of inm_graft()
                         * below for allocating new filter entries.
                         *
                         * This is only an issue if someone mixes the
                         * full-state SSM API with the delta-based API,
                         * which is discouraged in the relevant RFCs.
                         */
                        lims = imo_match_source(imo, idx, &ssa->sa);
                        if (lims != NULL /*&&
                            lims->imsl_st[1] == MCAST_INCLUDE*/) {
                                error = EADDRNOTAVAIL;
                                goto out_imo_locked;
                        }
                } else {
                        /*
                         * MCAST_JOIN_GROUP on an existing exclusive
                         * membership is an error; return EADDRINUSE
                         * to preserve 4.4BSD API idempotence, and
                         * avoid tedious detour to code below.
                         * NOTE: This is bending RFC 3678 a bit.
                         *
                         * On an existing inclusive membership, this is also
                         * an error; if you want to change filter mode,
                         * you must use the userland API setsourcefilter().
                         * XXX We don't reject this for imf in UNDEFINED
                         * state at t1, because allocation of a filter
                         * is atomic with allocation of a membership.
                         */
                        error = EINVAL;
                        /* See comments above for EADDRINUSE */
                        if (imf->imf_st[1] == MCAST_EXCLUDE)
                                error = EADDRINUSE;
                        goto out_imo_locked;
                }
        }

        /*
         * Begin state merge transaction at socket layer.
         */

        if (is_new) {
                if (imo->imo_num_memberships == imo->imo_max_memberships) {
                        error = imo_grow(imo, 0);
                        if (error)
                                goto out_imo_locked;
                }
                /*
                 * Allocate the new slot upfront so we can deal with
                 * grafting the new source filter in same code path
                 * as for join-source on existing membership.
                 */
                idx = imo->imo_num_memberships;
                imo->imo_membership[idx] = NULL;
                imo->imo_num_memberships++;
                VERIFY(imo->imo_mfilters != NULL);
                imf = &imo->imo_mfilters[idx];
                VERIFY(RB_EMPTY(&imf->imf_sources));
        }

        /*
         * Graft new source into filter list for this inpcb's
         * membership of the group. The in_multi may not have
         * been allocated yet if this is a new membership, however,
         * the in_mfilter slot will be allocated and must be initialized.
         */
        if (ssa->ss.ss_family != AF_UNSPEC) {
                /* Membership starts in IN mode */
                if (is_new) {
                        IGMP_PRINTF(("%s: new join w/source\n", __func__));
                        imf_init(imf, MCAST_UNDEFINED, MCAST_INCLUDE);
                } else {
                        IGMP_PRINTF(("%s: %s source\n", __func__, "allow"));
                }
                lims = imf_graft(imf, MCAST_INCLUDE, &ssa->sin);
                if (lims == NULL) {
                        IGMP_PRINTF(("%s: merge imf state failed\n",
                            __func__));
                        error = ENOMEM;
                        goto out_imo_free;
                }
        } else {
                /* No address specified; Membership starts in EX mode */
                if (is_new) {
                        IGMP_PRINTF(("%s: new join w/o source\n", __func__));
                        imf_init(imf, MCAST_UNDEFINED, MCAST_EXCLUDE);
                }
        }

        /*
         * Begin state merge transaction at IGMP layer.
         */

        if (is_new) {
                VERIFY(inm == NULL);
                error = in_joingroup(ifp, &gsa->sin.sin_addr, imf, &inm);
                VERIFY(inm != NULL || error != 0);
                if (error)
                        goto out_imo_free;
                imo->imo_membership[idx] = inm; /* from in_joingroup() */
        } else {
                IGMP_PRINTF(("%s: merge inm state\n", __func__));
                INM_LOCK(inm);
                error = inm_merge(inm, imf);
                if (error) {
                        IGMP_PRINTF(("%s: failed to merge inm state\n",
                            __func__));
                        INM_UNLOCK(inm);
                        goto out_imf_rollback;
                }
                IGMP_PRINTF(("%s: doing igmp downcall\n", __func__));
                error = igmp_change_state(inm, &itp);
                INM_UNLOCK(inm);
                if (error) {
                        IGMP_PRINTF(("%s: failed igmp downcall\n",
                            __func__));
                        goto out_imf_rollback;
                }
        }

out_imf_rollback:
        if (error) {
                imf_rollback(imf);
                if (is_new)
                        imf_purge(imf);
                else
                        imf_reap(imf);
        } else {
                imf_commit(imf);
        }

out_imo_free:
        if (error && is_new) {
                VERIFY(inm == NULL);
                imo->imo_membership[idx] = NULL;
                --imo->imo_num_memberships;
        }

out_imo_locked:
        IMO_UNLOCK(imo);
        IMO_REMREF(imo);        /* from inp_findmoptions() */

        /* schedule timer now that we've dropped the lock(s) */
        igmp_set_timeout(&itp);

        return (error);
}

/*
 * Leave an IPv4 multicast group on an inpcb, possibly with a source.
 *
 * NB: sopt->sopt_val might point to the kernel address space. Refer to the
 * block comment on top of inp_join_group() for more information.
 */
int
inp_leave_group(struct inpcb *inp, struct sockopt *sopt)
{
        struct group_source_req          gsr;
        struct ip_mreq_source            mreqs;
        sockunion_t                     *gsa, *ssa;
        struct ifnet                    *ifp;
        struct in_mfilter               *imf;
        struct ip_moptions              *imo;
        struct in_msource               *ims;
        struct in_multi                 *inm = NULL;
        size_t                           idx;
        int                              error, is_final;
        unsigned int                     ifindex = 0;
        struct igmp_tparams              itp;

        bzero(&itp, sizeof (itp));
        ifp = NULL;
        error = 0;
        is_final = 1;

        memset(&gsr, 0, sizeof(struct group_source_req));
        gsa = (sockunion_t *)&gsr.gsr_group;
        gsa->ss.ss_family = AF_UNSPEC;
        ssa = (sockunion_t *)&gsr.gsr_source;
        ssa->ss.ss_family = AF_UNSPEC;

        switch (sopt->sopt_name) {
        case IP_DROP_MEMBERSHIP:
        case IP_DROP_SOURCE_MEMBERSHIP:
                if (sopt->sopt_name == IP_DROP_MEMBERSHIP) {
                        error = sooptcopyin(sopt, &mreqs,
                            sizeof(struct ip_mreq),
                            sizeof(struct ip_mreq));
                        /*
                         * Swap interface and sourceaddr arguments,
                         * as ip_mreq and ip_mreq_source are laid
                         * out differently.
                         */
                        mreqs.imr_interface = mreqs.imr_sourceaddr;
                        mreqs.imr_sourceaddr.s_addr = INADDR_ANY;
                } else if (sopt->sopt_name == IP_DROP_SOURCE_MEMBERSHIP) {
                        error = sooptcopyin(sopt, &mreqs,
                            sizeof(struct ip_mreq_source),
                            sizeof(struct ip_mreq_source));
                }
                if (error)
                        return (error);

                gsa->sin.sin_family = AF_INET;
                gsa->sin.sin_len = sizeof(struct sockaddr_in);
                gsa->sin.sin_addr = mreqs.imr_multiaddr;

                if (sopt->sopt_name == IP_DROP_SOURCE_MEMBERSHIP) {
                        ssa->sin.sin_family = AF_INET;
                        ssa->sin.sin_len = sizeof(struct sockaddr_in);
                        ssa->sin.sin_addr = mreqs.imr_sourceaddr;
                }
                /*
                 * Attempt to look up hinted ifp from interface address.
                 * Fallthrough with null ifp iff lookup fails, to
                 * preserve 4.4BSD mcast API idempotence.
                 * XXX NOTE WELL: The RFC 3678 API is preferred because
                 * using an IPv4 address as a key is racy.
                 */
                if (!in_nullhost(mreqs.imr_interface))
                        ifp = ip_multicast_if(&mreqs.imr_interface, &ifindex);

                IGMP_INET_PRINTF(mreqs.imr_interface,
                    ("%s: imr_interface = %s, ifp = 0x%llx\n", __func__,
                    _igmp_inet_buf, (uint64_t)VM_KERNEL_ADDRPERM(ifp)));

                break;

        case MCAST_LEAVE_GROUP:
        case MCAST_LEAVE_SOURCE_GROUP:
                if (sopt->sopt_name == MCAST_LEAVE_GROUP) {
                        error = sooptcopyin(sopt, &gsr,
                            sizeof(struct group_req),
                            sizeof(struct group_req));
                } else if (sopt->sopt_name == MCAST_LEAVE_SOURCE_GROUP) {
                        error = sooptcopyin(sopt, &gsr,
                            sizeof(struct group_source_req),
                            sizeof(struct group_source_req));
                }
                if (error)
                        return (error);

                if (gsa->sin.sin_family != AF_INET ||
                    gsa->sin.sin_len != sizeof(struct sockaddr_in))
                        return (EINVAL);

                if (sopt->sopt_name == MCAST_LEAVE_SOURCE_GROUP) {
                        if (ssa->sin.sin_family != AF_INET ||
                            ssa->sin.sin_len != sizeof(struct sockaddr_in))
                                return (EINVAL);
                }

                ifnet_head_lock_shared();
                if (gsr.gsr_interface == 0 ||
                    (u_int)if_index < gsr.gsr_interface) {
                        ifnet_head_done();
                        return (EADDRNOTAVAIL);
                }

                ifp = ifindex2ifnet[gsr.gsr_interface];
                ifnet_head_done();
                break;

        default:
                IGMP_PRINTF(("%s: unknown sopt_name %d\n",
                    __func__, sopt->sopt_name));
                return (EOPNOTSUPP);
                break;
        }

        if (!IN_MULTICAST(ntohl(gsa->sin.sin_addr.s_addr)))
                return (EINVAL);

        /*
         * Find the membership in the membership array.
         */
        imo = inp_findmoptions(inp);
        if (imo == NULL)
                return (ENOMEM);

        IMO_LOCK(imo);
        idx = imo_match_group(imo, ifp, &gsa->sa);
        if (idx == (size_t)-1) {
                error = EADDRNOTAVAIL;
                goto out_locked;
        }
        inm = imo->imo_membership[idx];
        imf = &imo->imo_mfilters[idx];

        if (ssa->ss.ss_family != AF_UNSPEC) {
                IGMP_PRINTF(("%s: opt=%d is_final=0\n", __func__,
                    sopt->sopt_name));
                is_final = 0;
        }

        /*
         * Begin state merge transaction at socket layer.
         */

        /*
         * If we were instructed only to leave a given source, do so.
         * MCAST_LEAVE_SOURCE_GROUP is only valid for inclusive memberships.
         */
        if (is_final) {
                imf_leave(imf);
        } else {
                if (imf->imf_st[0] == MCAST_EXCLUDE) {
                        error = EADDRNOTAVAIL;
                        goto out_locked;
                }
                ims = imo_match_source(imo, idx, &ssa->sa);
                if (ims == NULL) {
                        IGMP_INET_PRINTF(ssa->sin.sin_addr,
                            ("%s: source %s %spresent\n", __func__,
                            _igmp_inet_buf, "not "));
                        error = EADDRNOTAVAIL;
                        goto out_locked;
                }
                IGMP_PRINTF(("%s: %s source\n", __func__, "block"));
                error = imf_prune(imf, &ssa->sin);
                if (error) {
                        IGMP_PRINTF(("%s: merge imf state failed\n",
                            __func__));
                        goto out_locked;
                }
        }

        /*
         * Begin state merge transaction at IGMP layer.
         */

        if (is_final) {
                /*
                 * Give up the multicast address record to which
                 * the membership points.  Reference held in imo
                 * will be released below.
                 */
                (void) in_leavegroup(inm, imf);
        } else {
                IGMP_PRINTF(("%s: merge inm state\n", __func__));
                INM_LOCK(inm);
                error = inm_merge(inm, imf);
                if (error) {
                        IGMP_PRINTF(("%s: failed to merge inm state\n",
                            __func__));
                        INM_UNLOCK(inm);
                        goto out_imf_rollback;
                }

                IGMP_PRINTF(("%s: doing igmp downcall\n", __func__));
                error = igmp_change_state(inm, &itp);
                if (error) {
                        IGMP_PRINTF(("%s: failed igmp downcall\n", __func__));
                }
                INM_UNLOCK(inm);
        }

out_imf_rollback:
        if (error)
                imf_rollback(imf);
        else
                imf_commit(imf);

        imf_reap(imf);

        if (is_final) {
                /* Remove the gap in the membership and filter array. */
                VERIFY(inm == imo->imo_membership[idx]);
                imo->imo_membership[idx] = NULL;
                INM_REMREF(inm);
                for (++idx; idx < imo->imo_num_memberships; ++idx) {
                        imo->imo_membership[idx-1] = imo->imo_membership[idx];
                        imo->imo_mfilters[idx-1] = imo->imo_mfilters[idx];
                }
                imo->imo_num_memberships--;
        }

out_locked:
        IMO_UNLOCK(imo);
        IMO_REMREF(imo);        /* from inp_findmoptions() */

        /* schedule timer now that we've dropped the lock(s) */
        igmp_set_timeout(&itp);

        return (error);
}

/*
 * Select the interface for transmitting IPv4 multicast datagrams.
 *
 * Either an instance of struct in_addr or an instance of struct ip_mreqn
 * may be passed to this socket option. An address of INADDR_ANY or an
 * interface index of 0 is used to remove a previous selection.
 * When no interface is selected, one is chosen for every send.
 */
static int
inp_set_multicast_if(struct inpcb *inp, struct sockopt *sopt)
{
        struct in_addr           addr;
        struct ip_mreqn          mreqn;
        struct ifnet            *ifp;
        struct ip_moptions      *imo;
        int                      error = 0 ;
        unsigned int             ifindex = 0;

        if (sopt->sopt_valsize == sizeof(struct ip_mreqn)) {
                /*
                 * An interface index was specified using the
                 * Linux-derived ip_mreqn structure.
                 */
                error = sooptcopyin(sopt, &mreqn, sizeof(struct ip_mreqn),
                    sizeof(struct ip_mreqn));
                if (error)
                        return (error);

                ifnet_head_lock_shared();
                if (mreqn.imr_ifindex < 0 || if_index < mreqn.imr_ifindex) {
                        ifnet_head_done();
                        return (EINVAL);
                }

                if (mreqn.imr_ifindex == 0) {
                        ifp = NULL;
                } else {
                        ifp = ifindex2ifnet[mreqn.imr_ifindex];
                        if (ifp == NULL) {
                                ifnet_head_done();
                                return (EADDRNOTAVAIL);
                        }
                }
                ifnet_head_done();
        } else {
                /*
                 * An interface was specified by IPv4 address.
                 * This is the traditional BSD usage.
                 */
                error = sooptcopyin(sopt, &addr, sizeof(struct in_addr),
                    sizeof(struct in_addr));
                if (error)
                        return (error);
                if (in_nullhost(addr)) {
                        ifp = NULL;
                } else {
                        ifp = ip_multicast_if(&addr, &ifindex);
                        if (ifp == NULL) {
                                IGMP_INET_PRINTF(addr,
                                    ("%s: can't find ifp for addr=%s\n",
                                    __func__, _igmp_inet_buf));
                                return (EADDRNOTAVAIL);
                        }
                }
                /* XXX remove? */
#ifdef IGMP_DEBUG0
                IGMP_PRINTF(("%s: ifp = 0x%llx, addr = %s\n", __func__,
                    (uint64_t)VM_KERNEL_ADDRPERM(ifp), inet_ntoa(addr)));
#endif
        }

        /* Reject interfaces which do not support multicast. */
        if (ifp != NULL && (ifp->if_flags & IFF_MULTICAST) == 0)
                return (EOPNOTSUPP);

        imo = inp_findmoptions(inp);
        if (imo == NULL)
                return (ENOMEM);

        IMO_LOCK(imo);
        imo->imo_multicast_ifp = ifp;
        if (ifindex)
                imo->imo_multicast_addr = addr;
        else
                imo->imo_multicast_addr.s_addr = INADDR_ANY;
        IMO_UNLOCK(imo);
        IMO_REMREF(imo);        /* from inp_findmoptions() */

        return (0);
}

/*
 * Atomically set source filters on a socket for an IPv4 multicast group.
 */
static int
inp_set_source_filters(struct inpcb *inp, struct sockopt *sopt)
{
        struct __msfilterreq64   msfr, msfr64;
        struct __msfilterreq32   msfr32;
        sockunion_t             *gsa;
        struct ifnet            *ifp;
        struct in_mfilter       *imf;
        struct ip_moptions      *imo;
        struct in_multi         *inm;
        size_t                   idx;
        int                      error;
        user_addr_t              tmp_ptr;
        struct igmp_tparams      itp;

        bzero(&itp, sizeof (itp));

        if (IS_64BIT_PROCESS(current_proc())) {
                error = sooptcopyin(sopt, &msfr64,
                    sizeof(struct __msfilterreq64),
                    sizeof(struct __msfilterreq64));
                if (error)
                        return (error);
                /* we never use msfr.msfr_srcs; */
                memcpy(&msfr, &msfr64, sizeof(msfr));
        } else {
                error = sooptcopyin(sopt, &msfr32,
                    sizeof(struct __msfilterreq32),
                    sizeof(struct __msfilterreq32));
                if (error)
                        return (error);
                /* we never use msfr.msfr_srcs; */
                memcpy(&msfr, &msfr32, sizeof(msfr));
        }

        if ((size_t) msfr.msfr_nsrcs >
            UINT32_MAX / sizeof(struct sockaddr_storage))
                msfr.msfr_nsrcs = UINT32_MAX / sizeof(struct sockaddr_storage);

        if (msfr.msfr_nsrcs > in_mcast_maxsocksrc)
                return (ENOBUFS);

        if ((msfr.msfr_fmode != MCAST_EXCLUDE &&
             msfr.msfr_fmode != MCAST_INCLUDE))
                return (EINVAL);

        if (msfr.msfr_group.ss_family != AF_INET ||
            msfr.msfr_group.ss_len != sizeof(struct sockaddr_in))
                return (EINVAL);

        gsa = (sockunion_t *)&msfr.msfr_group;
        if (!IN_MULTICAST(ntohl(gsa->sin.sin_addr.s_addr)))
                return (EINVAL);

        gsa->sin.sin_port = 0;  /* ignore port */

        ifnet_head_lock_shared();
        if (msfr.msfr_ifindex == 0 || (u_int)if_index < msfr.msfr_ifindex) {
                ifnet_head_done();
                return (EADDRNOTAVAIL);
        }

        ifp = ifindex2ifnet[msfr.msfr_ifindex];
        ifnet_head_done();
        if (ifp == NULL)
                return (EADDRNOTAVAIL);

        /*
         * Check if this socket is a member of this group.
         */
        imo = inp_findmoptions(inp);
        if (imo == NULL)
                return (ENOMEM);

        IMO_LOCK(imo);
        idx = imo_match_group(imo, ifp, &gsa->sa);
        if (idx == (size_t)-1 || imo->imo_mfilters == NULL) {
                error = EADDRNOTAVAIL;
                goto out_imo_locked;
        }
        inm = imo->imo_membership[idx];
        imf = &imo->imo_mfilters[idx];

        /*
         * Begin state merge transaction at socket layer.
         */

        imf->imf_st[1] = msfr.msfr_fmode;

        /*
         * Apply any new source filters, if present.
         * Make a copy of the user-space source vector so
         * that we may copy them with a single copyin. This
         * allows us to deal with page faults up-front.
         */
        if (msfr.msfr_nsrcs > 0) {
                struct in_msource       *lims;
                struct sockaddr_in      *psin;
                struct sockaddr_storage *kss, *pkss;
                int                      i;

                if (IS_64BIT_PROCESS(current_proc()))
                        tmp_ptr = msfr64.msfr_srcs;
                else
                        tmp_ptr = CAST_USER_ADDR_T(msfr32.msfr_srcs);

                IGMP_PRINTF(("%s: loading %lu source list entries\n",
                    __func__, (unsigned long)msfr.msfr_nsrcs));
                kss = _MALLOC((size_t) msfr.msfr_nsrcs * sizeof(*kss),
                    M_TEMP, M_WAITOK);
                if (kss == NULL) {
                        error = ENOMEM;
                        goto out_imo_locked;
                }
                error = copyin(tmp_ptr, kss,
                    (size_t) msfr.msfr_nsrcs * sizeof(*kss));
                if (error) {
                        FREE(kss, M_TEMP);
                        goto out_imo_locked;
                }

                /*
                 * Mark all source filters as UNDEFINED at t1.
                 * Restore new group filter mode, as imf_leave()
                 * will set it to INCLUDE.
                 */
                imf_leave(imf);
                imf->imf_st[1] = msfr.msfr_fmode;

                /*
                 * Update socket layer filters at t1, lazy-allocating
                 * new entries. This saves a bunch of memory at the
                 * cost of one RB_FIND() per source entry; duplicate
                 * entries in the msfr_nsrcs vector are ignored.
                 * If we encounter an error, rollback transaction.
                 *
                 * XXX This too could be replaced with a set-symmetric
                 * difference like loop to avoid walking from root
                 * every time, as the key space is common.
                 */
                for (i = 0, pkss = kss; (u_int)i < msfr.msfr_nsrcs;
                    i++, pkss++) {
                        psin = (struct sockaddr_in *)pkss;
                        if (psin->sin_family != AF_INET) {
                                error = EAFNOSUPPORT;
                                break;
                        }
                        if (psin->sin_len != sizeof(struct sockaddr_in)) {
                                error = EINVAL;
                                break;
                        }
                        error = imf_get_source(imf, psin, &lims);
                        if (error)
                                break;
                        lims->imsl_st[1] = imf->imf_st[1];
                }
                FREE(kss, M_TEMP);
        }

        if (error)
                goto out_imf_rollback;

        /*
         * Begin state merge transaction at IGMP layer.
         */
        INM_LOCK(inm);
        IGMP_PRINTF(("%s: merge inm state\n", __func__));
        error = inm_merge(inm, imf);
        if (error) {
                IGMP_PRINTF(("%s: failed to merge inm state\n", __func__));
                INM_UNLOCK(inm);
                goto out_imf_rollback;
        }

        IGMP_PRINTF(("%s: doing igmp downcall\n", __func__));
        error = igmp_change_state(inm, &itp);
        INM_UNLOCK(inm);
#ifdef IGMP_DEBUG
        if (error)
                IGMP_PRINTF(("%s: failed igmp downcall\n", __func__));
#endif

out_imf_rollback:
        if (error)
                imf_rollback(imf);
        else
                imf_commit(imf);

        imf_reap(imf);

out_imo_locked:
        IMO_UNLOCK(imo);
        IMO_REMREF(imo);        /* from inp_findmoptions() */

        /* schedule timer now that we've dropped the lock(s) */
        igmp_set_timeout(&itp);

        return (error);
}

/*
 * Set the IP multicast options in response to user setsockopt().
 *
 * Many of the socket options handled in this function duplicate the
 * functionality of socket options in the regular unicast API. However,
 * it is not possible to merge the duplicate code, because the idempotence
 * of the IPv4 multicast part of the BSD Sockets API must be preserved;
 * the effects of these options must be treated as separate and distinct.
 *
 * FUTURE: The IP_MULTICAST_VIF option may be eliminated if MROUTING
 * is refactored to no longer use vifs.
 */
int
inp_setmoptions(struct inpcb *inp, struct sockopt *sopt)
{
        struct ip_moptions      *imo;
        int                      error;
        unsigned int             ifindex;
        struct ifnet            *ifp;

        error = 0;

        /*
         * If socket is neither of type SOCK_RAW or SOCK_DGRAM,
         * or is a divert socket, reject it.
         */
        if (SOCK_PROTO(inp->inp_socket) == IPPROTO_DIVERT ||
            (SOCK_TYPE(inp->inp_socket) != SOCK_RAW &&
             SOCK_TYPE(inp->inp_socket) != SOCK_DGRAM))
                return (EOPNOTSUPP);

        switch (sopt->sopt_name) {
#if MROUTING
        case IP_MULTICAST_VIF: {
                int vifi;
                /*
                 * Select a multicast VIF for transmission.
                 * Only useful if multicast forwarding is active.
                 */
                if (legal_vif_num == NULL) {
                        error = EOPNOTSUPP;
                        break;
                }
                error = sooptcopyin(sopt, &vifi, sizeof(int), sizeof(int));
                if (error)
                        break;
                if (!legal_vif_num(vifi) && (vifi != -1)) {
                        error = EINVAL;
                        break;
                }
                imo = inp_findmoptions(inp);
                if (imo == NULL) {
                        error = ENOMEM;
                        break;
                }
                IMO_LOCK(imo);
                imo->imo_multicast_vif = vifi;
                IMO_UNLOCK(imo);
                IMO_REMREF(imo);        /* from inp_findmoptions() */
                break;
        }
#endif
        case IP_MULTICAST_IF:
                error = inp_set_multicast_if(inp, sopt);
                break;

        case IP_MULTICAST_IFINDEX:
                /*
                 * Select the interface for outgoing multicast packets.
                 */
                error = sooptcopyin(sopt, &ifindex, sizeof (ifindex),
                    sizeof (ifindex));
                if (error)
                        break;

                imo = inp_findmoptions(inp);
                if (imo == NULL) {
                        error = ENOMEM;
                        break;
                }
                /*
                 * Index 0 is used to remove a previous selection.
                 * When no interface is selected, a default one is
                 * chosen every time a multicast packet is sent.
                 */
                if (ifindex == 0) {
                        IMO_LOCK(imo);
                        imo->imo_multicast_ifp = NULL;
                        IMO_UNLOCK(imo);
                        IMO_REMREF(imo);        /* from inp_findmoptions() */
                        break;
                }

                ifnet_head_lock_shared();
                /* Don't need to check is ifindex is < 0 since it's unsigned */
                if ((unsigned int)if_index < ifindex) {
                        ifnet_head_done();
                        IMO_REMREF(imo);        /* from inp_findmoptions() */
                        error = ENXIO;  /* per IPV6_MULTICAST_IF */
                        break;
                }
                ifp = ifindex2ifnet[ifindex];
                ifnet_head_done();

                /* If it's detached or isn't a multicast interface, bail out */
                if (ifp == NULL || !(ifp->if_flags & IFF_MULTICAST)) {
                        IMO_REMREF(imo);        /* from inp_findmoptions() */
                        error = EADDRNOTAVAIL;
                        break;
                }
                IMO_LOCK(imo);
                imo->imo_multicast_ifp = ifp;
                /*
                 * Clear out any remnants of past IP_MULTICAST_IF.  The addr
                 * isn't really used anywhere in the kernel; we could have
                 * iterated thru the addresses of the interface and pick one
                 * here, but that is redundant since ip_getmoptions() already
                 * takes care of that for INADDR_ANY.
                 */
                imo->imo_multicast_addr.s_addr = INADDR_ANY;
                IMO_UNLOCK(imo);
                IMO_REMREF(imo);        /* from inp_findmoptions() */
                break;

        case IP_MULTICAST_TTL: {
                u_char ttl;

                /*
                 * Set the IP time-to-live for outgoing multicast packets.
                 * The original multicast API required a char argument,
                 * which is inconsistent with the rest of the socket API.
                 * We allow either a char or an int.
                 */
                if (sopt->sopt_valsize == sizeof(u_char)) {
                        error = sooptcopyin(sopt, &ttl, sizeof(u_char),
                            sizeof(u_char));
                        if (error)
                                break;
                } else {
                        u_int ittl;

                        error = sooptcopyin(sopt, &ittl, sizeof(u_int),
                            sizeof(u_int));
                        if (error)
                                break;
                        if (ittl > 255) {
                                error = EINVAL;
                                break;
                        }
                        ttl = (u_char)ittl;
                }
                imo = inp_findmoptions(inp);
                if (imo == NULL) {
                        error = ENOMEM;
                        break;
                }
                IMO_LOCK(imo);
                imo->imo_multicast_ttl = ttl;
                IMO_UNLOCK(imo);
                IMO_REMREF(imo);        /* from inp_findmoptions() */
                break;
        }

        case IP_MULTICAST_LOOP: {
                u_char loop;

                /*
                 * Set the loopback flag for outgoing multicast packets.
                 * Must be zero or one.  The original multicast API required a
                 * char argument, which is inconsistent with the rest
                 * of the socket API.  We allow either a char or an int.
                 */
                if (sopt->sopt_valsize == sizeof(u_char)) {
                        error = sooptcopyin(sopt, &loop, sizeof(u_char),
                            sizeof(u_char));
                        if (error)
                                break;
                } else {
                        u_int iloop;

                        error = sooptcopyin(sopt, &iloop, sizeof(u_int),
                                            sizeof(u_int));
                        if (error)
                                break;
                        loop = (u_char)iloop;
                }
                imo = inp_findmoptions(inp);
                if (imo == NULL) {
                        error = ENOMEM;
                        break;
                }
                IMO_LOCK(imo);
                imo->imo_multicast_loop = !!loop;
                IMO_UNLOCK(imo);
                IMO_REMREF(imo);        /* from inp_findmoptions() */
                break;
        }

        case IP_ADD_MEMBERSHIP:
        case IP_ADD_SOURCE_MEMBERSHIP:
        case MCAST_JOIN_GROUP:
        case MCAST_JOIN_SOURCE_GROUP:
                error = inp_join_group(inp, sopt);
                break;

        case IP_DROP_MEMBERSHIP:
        case IP_DROP_SOURCE_MEMBERSHIP:
        case MCAST_LEAVE_GROUP:
        case MCAST_LEAVE_SOURCE_GROUP:
                error = inp_leave_group(inp, sopt);
                break;

        case IP_BLOCK_SOURCE:
        case IP_UNBLOCK_SOURCE:
        case MCAST_BLOCK_SOURCE:
        case MCAST_UNBLOCK_SOURCE:
                error = inp_block_unblock_source(inp, sopt);
                break;

        case IP_MSFILTER:
                error = inp_set_source_filters(inp, sopt);
                break;

        default:
                error = EOPNOTSUPP;
                break;
        }

        return (error);
}

/*
 * Expose IGMP's multicast filter mode and source list(s) to userland,
 * keyed by (ifindex, group).
 * The filter mode is written out as a uint32_t, followed by
 * 0..n of struct in_addr.
 * For use by ifmcstat(8).
 */
static int
sysctl_ip_mcast_filters SYSCTL_HANDLER_ARGS
{
#pragma unused(oidp)

        struct in_addr                   src, group;
        struct ifnet                    *ifp;
        struct in_multi                 *inm;
        struct in_multistep             step;
        struct ip_msource               *ims;
        int                             *name;
        int                              retval = 0;
        u_int                            namelen;
        uint32_t                         fmode, ifindex;

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

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

        if (namelen != 2)
                return (EINVAL);

        ifindex = name[0];
        ifnet_head_lock_shared();
        if (ifindex <= 0 || ifindex > (u_int)if_index) {
                IGMP_PRINTF(("%s: ifindex %u out of range\n",
                    __func__, ifindex));
                ifnet_head_done();
                return (ENOENT);
        }

        group.s_addr = name[1];
        if (!IN_MULTICAST(ntohl(group.s_addr))) {
                IGMP_INET_PRINTF(group,
                    ("%s: group %s is not multicast\n",
                    __func__, _igmp_inet_buf));
                ifnet_head_done();
                return (EINVAL);
        }

        ifp = ifindex2ifnet[ifindex];
        ifnet_head_done();
        if (ifp == NULL) {
                IGMP_PRINTF(("%s: no ifp for ifindex %u\n", __func__, ifindex));
                return (ENOENT);
        }

        in_multihead_lock_shared();
        IN_FIRST_MULTI(step, inm);
        while (inm != NULL) {
                INM_LOCK(inm);
                if (inm->inm_ifp != ifp)
                        goto next;

                if (!in_hosteq(inm->inm_addr, group))
                        goto next;

                fmode = inm->inm_st[1].iss_fmode;
                retval = SYSCTL_OUT(req, &fmode, sizeof(uint32_t));
                if (retval != 0) {
                        INM_UNLOCK(inm);
                        break;          /* abort */
                }
                RB_FOREACH(ims, ip_msource_tree, &inm->inm_srcs) {
#ifdef IGMP_DEBUG
                        struct in_addr ina;
                        ina.s_addr = htonl(ims->ims_haddr);
                        IGMP_INET_PRINTF(ina,
                            ("%s: visit node %s\n", __func__, _igmp_inet_buf));
#endif
                        /*
                         * Only copy-out sources which are in-mode.
                         */
                        if (fmode != ims_get_mode(inm, ims, 1)) {
                                IGMP_PRINTF(("%s: skip non-in-mode\n",
                                    __func__));
                                continue; /* process next source */
                        }
                        src.s_addr = htonl(ims->ims_haddr);
                        retval = SYSCTL_OUT(req, &src, sizeof(struct in_addr));
                        if (retval != 0)
                                break;  /* process next inm */
                }
next:
                INM_UNLOCK(inm);
                IN_NEXT_MULTI(step, inm);
        }
        in_multihead_lock_done();

        return (retval);
}

/*
 * XXX
 * The whole multicast option thing needs to be re-thought.
 * Several of these options are equally applicable to non-multicast
 * transmission, and one (IP_MULTICAST_TTL) totally duplicates a
 * standard option (IP_TTL).
 */
/*
 * following RFC1724 section 3.3, 0.0.0.0/8 is interpreted as interface index.
 */
static struct ifnet *
ip_multicast_if(struct in_addr *a, unsigned int *ifindexp)
{
        unsigned int ifindex;
        struct ifnet *ifp;

        if (ifindexp != NULL)
                *ifindexp = 0;
        if (ntohl(a->s_addr) >> 24 == 0) {
                ifindex = ntohl(a->s_addr) & 0xffffff;
                ifnet_head_lock_shared();
                /* Don't need to check is ifindex is < 0 since it's unsigned */
                if ((unsigned int)if_index < ifindex) {
                        ifnet_head_done();
                        return (NULL);
                }
                ifp = ifindex2ifnet[ifindex];
                ifnet_head_done();
                if (ifp != NULL && ifindexp != NULL)
                        *ifindexp = ifindex;
        } else {
                INADDR_TO_IFP(*a, ifp);
        }
        return (ifp);
}

void
in_multi_init(void)
{
        PE_parse_boot_argn("ifa_debug", &inm_debug, sizeof (inm_debug));

        /* Setup lock group and attribute for in_multihead */
        in_multihead_lock_grp_attr = lck_grp_attr_alloc_init();
        in_multihead_lock_grp = lck_grp_alloc_init("in_multihead",
            in_multihead_lock_grp_attr);
        in_multihead_lock_attr = lck_attr_alloc_init();
        lck_rw_init(&in_multihead_lock, in_multihead_lock_grp,
            in_multihead_lock_attr);

        lck_mtx_init(&inm_trash_lock, in_multihead_lock_grp,
            in_multihead_lock_attr);
        TAILQ_INIT(&inm_trash_head);

        inm_size = (inm_debug == 0) ? sizeof (struct in_multi) :
            sizeof (struct in_multi_dbg);
        inm_zone = zinit(inm_size, INM_ZONE_MAX * inm_size,
            0, INM_ZONE_NAME);
        if (inm_zone == NULL) {
                panic("%s: failed allocating %s", __func__, INM_ZONE_NAME);
                /* NOTREACHED */
        }
        zone_change(inm_zone, Z_EXPAND, TRUE);

        ipms_size = sizeof (struct ip_msource);
        ipms_zone = zinit(ipms_size, IPMS_ZONE_MAX * ipms_size,
            0, IPMS_ZONE_NAME);
        if (ipms_zone == NULL) {
                panic("%s: failed allocating %s", __func__, IPMS_ZONE_NAME);
                /* NOTREACHED */
        }
        zone_change(ipms_zone, Z_EXPAND, TRUE);

        inms_size = sizeof (struct in_msource);
        inms_zone = zinit(inms_size, INMS_ZONE_MAX * inms_size,
            0, INMS_ZONE_NAME);
        if (inms_zone == NULL) {
                panic("%s: failed allocating %s", __func__, INMS_ZONE_NAME);
                /* NOTREACHED */
        }
        zone_change(inms_zone, Z_EXPAND, TRUE);
}

static struct in_multi *
in_multi_alloc(int how)
{
        struct in_multi *inm;

        inm = (how == M_WAITOK) ? zalloc(inm_zone) : zalloc_noblock(inm_zone);
        if (inm != NULL) {
                bzero(inm, inm_size);
                lck_mtx_init(&inm->inm_lock, in_multihead_lock_grp,
                    in_multihead_lock_attr);
                inm->inm_debug |= IFD_ALLOC;
                if (inm_debug != 0) {
                        inm->inm_debug |= IFD_DEBUG;
                        inm->inm_trace = inm_trace;
                }
        }
        return (inm);
}

static void
in_multi_free(struct in_multi *inm)
{
        INM_LOCK(inm);
        if (inm->inm_debug & IFD_ATTACHED) {
                panic("%s: attached inm=%p is being freed", __func__, inm);
                /* NOTREACHED */
        } else if (inm->inm_ifma != NULL) {
                panic("%s: ifma not NULL for inm=%p", __func__, inm);
                /* NOTREACHED */
        } else if (!(inm->inm_debug & IFD_ALLOC)) {
                panic("%s: inm %p cannot be freed", __func__, inm);
                /* NOTREACHED */
        } else if (inm->inm_refcount != 0) {
                panic("%s: non-zero refcount inm=%p", __func__, inm);
                /* NOTREACHED */
        } else if (inm->inm_reqcnt != 0) {
                panic("%s: non-zero reqcnt inm=%p", __func__, inm);
                /* NOTREACHED */
        }

        /* Free any pending IGMPv3 state-change records */
        IF_DRAIN(&inm->inm_scq);

        inm->inm_debug &= ~IFD_ALLOC;
        if ((inm->inm_debug & (IFD_DEBUG | IFD_TRASHED)) ==
            (IFD_DEBUG | IFD_TRASHED)) {
                lck_mtx_lock(&inm_trash_lock);
                TAILQ_REMOVE(&inm_trash_head, (struct in_multi_dbg *)inm,
                    inm_trash_link);
                lck_mtx_unlock(&inm_trash_lock);
                inm->inm_debug &= ~IFD_TRASHED;
        }
        INM_UNLOCK(inm);

        lck_mtx_destroy(&inm->inm_lock, in_multihead_lock_grp);
        zfree(inm_zone, inm);
}

static void
in_multi_attach(struct in_multi *inm)
{
        in_multihead_lock_assert(LCK_RW_ASSERT_EXCLUSIVE);
        INM_LOCK_ASSERT_HELD(inm);

        if (inm->inm_debug & IFD_ATTACHED) {
                panic("%s: Attempt to attach an already attached inm=%p",
                    __func__, inm);
                /* NOTREACHED */
        } else if (inm->inm_debug & IFD_TRASHED) {
                panic("%s: Attempt to reattach a detached inm=%p",
                    __func__, inm);
                /* NOTREACHED */
        }

        inm->inm_reqcnt++;
        VERIFY(inm->inm_reqcnt == 1);
        INM_ADDREF_LOCKED(inm);
        inm->inm_debug |= IFD_ATTACHED;
        /*
         * Reattach case:  If debugging is enabled, take it
         * out of the trash list and clear IFD_TRASHED.
         */
        if ((inm->inm_debug & (IFD_DEBUG | IFD_TRASHED)) ==
            (IFD_DEBUG | IFD_TRASHED)) {
                /* Become a regular mutex, just in case */
                INM_CONVERT_LOCK(inm);
                lck_mtx_lock(&inm_trash_lock);
                TAILQ_REMOVE(&inm_trash_head, (struct in_multi_dbg *)inm,
                    inm_trash_link);
                lck_mtx_unlock(&inm_trash_lock);
                inm->inm_debug &= ~IFD_TRASHED;
        }

        LIST_INSERT_HEAD(&in_multihead, inm, inm_link);
}

int
in_multi_detach(struct in_multi *inm)
{
        in_multihead_lock_assert(LCK_RW_ASSERT_EXCLUSIVE);
        INM_LOCK_ASSERT_HELD(inm);

        if (inm->inm_reqcnt == 0) {
                panic("%s: inm=%p negative reqcnt", __func__, inm);
                /* NOTREACHED */
        }

        --inm->inm_reqcnt;
        if (inm->inm_reqcnt > 0)
                return (0);

        if (!(inm->inm_debug & IFD_ATTACHED)) {
                panic("%s: Attempt to detach an unattached record inm=%p",
                    __func__, inm);
                /* NOTREACHED */
        } else if (inm->inm_debug & IFD_TRASHED) {
                panic("%s: inm %p is already in trash list", __func__, inm);
                /* NOTREACHED */
        }

        /*
         * NOTE: Caller calls IFMA_REMREF
         */
        inm->inm_debug &= ~IFD_ATTACHED;
        LIST_REMOVE(inm, inm_link);

        if (inm->inm_debug & IFD_DEBUG) {
                /* Become a regular mutex, just in case */
                INM_CONVERT_LOCK(inm);
                lck_mtx_lock(&inm_trash_lock);
                TAILQ_INSERT_TAIL(&inm_trash_head,
                    (struct in_multi_dbg *)inm, inm_trash_link);
                lck_mtx_unlock(&inm_trash_lock);
                inm->inm_debug |= IFD_TRASHED;
        }

        return (1);
}

void
inm_addref(struct in_multi *inm, int locked)
{
        if (!locked)
                INM_LOCK_SPIN(inm);
        else
                INM_LOCK_ASSERT_HELD(inm);

        if (++inm->inm_refcount == 0) {
                panic("%s: inm=%p wraparound refcnt", __func__, inm);
                /* NOTREACHED */
        } else if (inm->inm_trace != NULL) {
                (*inm->inm_trace)(inm, TRUE);
        }
        if (!locked)
                INM_UNLOCK(inm);
}

void
inm_remref(struct in_multi *inm, int locked)
{
        struct ifmultiaddr *ifma;
        struct igmp_ifinfo *igi;

        if (!locked)
                INM_LOCK_SPIN(inm);
        else
                INM_LOCK_ASSERT_HELD(inm);

        if (inm->inm_refcount == 0 || (inm->inm_refcount == 1 && locked)) {
                panic("%s: inm=%p negative/missing refcnt", __func__, inm);
                /* NOTREACHED */
        } else if (inm->inm_trace != NULL) {
                (*inm->inm_trace)(inm, FALSE);
        }

        --inm->inm_refcount;
        if (inm->inm_refcount > 0) {
                if (!locked)
                        INM_UNLOCK(inm);
                return;
        }

        /*
         * Synchronization with in_getmulti().  In the event the inm has been
         * detached, the underlying ifma would still be in the if_multiaddrs
         * list, and thus can be looked up via if_addmulti().  At that point,
         * the only way to find this inm is via ifma_protospec.  To avoid
         * race conditions between the last inm_remref() of that inm and its
         * use via ifma_protospec, in_multihead lock is used for serialization.
         * In order to avoid violating the lock order, we must drop inm_lock
         * before acquiring in_multihead lock.  To prevent the inm from being
         * freed prematurely, we hold an extra reference.
         */
        ++inm->inm_refcount;
        INM_UNLOCK(inm);
        in_multihead_lock_shared();
        INM_LOCK_SPIN(inm);
        --inm->inm_refcount;
        if (inm->inm_refcount > 0) {
                /* We've lost the race, so abort since inm is still in use */
                INM_UNLOCK(inm);
                in_multihead_lock_done();
                /* If it was locked, return it as such */
                if (locked)
                        INM_LOCK(inm);
                return;
        }
        inm_purge(inm);
        ifma = inm->inm_ifma;
        inm->inm_ifma = NULL;
        inm->inm_ifp = NULL;
        igi = inm->inm_igi;
        inm->inm_igi = NULL;
        INM_UNLOCK(inm);
        IFMA_LOCK_SPIN(ifma);
        ifma->ifma_protospec = NULL;
        IFMA_UNLOCK(ifma);
        in_multihead_lock_done();

        in_multi_free(inm);
        if_delmulti_ifma(ifma);
        /* Release reference held to the underlying ifmultiaddr */
        IFMA_REMREF(ifma);

        if (igi != NULL)
                IGI_REMREF(igi);
}

static void
inm_trace(struct in_multi *inm, int refhold)
{
        struct in_multi_dbg *inm_dbg = (struct in_multi_dbg *)inm;
        ctrace_t *tr;
        u_int32_t idx;
        u_int16_t *cnt;

        if (!(inm->inm_debug & IFD_DEBUG)) {
                panic("%s: inm %p has no debug structure", __func__, inm);
                /* NOTREACHED */
        }
        if (refhold) {
                cnt = &inm_dbg->inm_refhold_cnt;
                tr = inm_dbg->inm_refhold;
        } else {
                cnt = &inm_dbg->inm_refrele_cnt;
                tr = inm_dbg->inm_refrele;
        }

        idx = atomic_add_16_ov(cnt, 1) % INM_TRACE_HIST_SIZE;
        ctrace_record(&tr[idx]);
}

void
in_multihead_lock_exclusive(void)
{
        lck_rw_lock_exclusive(&in_multihead_lock);
}

void
in_multihead_lock_shared(void)
{
        lck_rw_lock_shared(&in_multihead_lock);
}

void
in_multihead_lock_assert(int what)
{
        lck_rw_assert(&in_multihead_lock, what);
}

void
in_multihead_lock_done(void)
{
        lck_rw_done(&in_multihead_lock);
}

static struct ip_msource *
ipms_alloc(int how)
{
        struct ip_msource *ims;

        ims = (how == M_WAITOK) ? zalloc(ipms_zone) : zalloc_noblock(ipms_zone);
        if (ims != NULL)
                bzero(ims, ipms_size);

        return (ims);
}

static void
ipms_free(struct ip_msource *ims)
{
        zfree(ipms_zone, ims);
}

static struct in_msource *
inms_alloc(int how)
{
        struct in_msource *inms;

        inms = (how == M_WAITOK) ? zalloc(inms_zone) :
            zalloc_noblock(inms_zone);
        if (inms != NULL)
                bzero(inms, inms_size);

        return (inms);
}

static void
inms_free(struct in_msource *inms)
{
        zfree(inms_zone, inms);
}

#ifdef IGMP_DEBUG

static const char *inm_modestrs[] = { "un\n", "in", "ex" };

static const char *
inm_mode_str(const int mode)
{
        if (mode >= MCAST_UNDEFINED && mode <= MCAST_EXCLUDE)
                return (inm_modestrs[mode]);
        return ("??");
}

static const char *inm_statestrs[] = {
        "not-member\n",
        "silent\n",
        "reporting\n",
        "idle\n",
        "lazy\n",
        "sleeping\n",
        "awakening\n",
        "query-pending\n",
        "sg-query-pending\n",
        "leaving"
};

static const char *
inm_state_str(const int state)
{
        if (state >= IGMP_NOT_MEMBER && state <= IGMP_LEAVING_MEMBER)
                return (inm_statestrs[state]);
        return ("??");
}

/*
 * Dump an in_multi structure to the console.
 */
void
inm_print(const struct in_multi *inm)
{
        int t;
        char buf[MAX_IPv4_STR_LEN];

        INM_LOCK_ASSERT_HELD(__DECONST(struct in_multi *, inm));

        if (igmp_debug == 0)
                return;

        inet_ntop(AF_INET, &inm->inm_addr, buf, sizeof(buf));
        printf("%s: --- begin inm 0x%llx ---\n", __func__,
            (uint64_t)VM_KERNEL_ADDRPERM(inm));
        printf("addr %s ifp 0x%llx(%s) ifma 0x%llx\n",
            buf,
            (uint64_t)VM_KERNEL_ADDRPERM(inm->inm_ifp),
            if_name(inm->inm_ifp),
            (uint64_t)VM_KERNEL_ADDRPERM(inm->inm_ifma));
        printf("timer %u state %s refcount %u scq.len %u\n",
            inm->inm_timer,
            inm_state_str(inm->inm_state),
            inm->inm_refcount,
            inm->inm_scq.ifq_len);
        printf("igi 0x%llx nsrc %lu sctimer %u scrv %u\n",
            (uint64_t)VM_KERNEL_ADDRPERM(inm->inm_igi),
            inm->inm_nsrc,
            inm->inm_sctimer,
            inm->inm_scrv);
        for (t = 0; t < 2; t++) {
                printf("t%d: fmode %s asm %u ex %u in %u rec %u\n", t,
                    inm_mode_str(inm->inm_st[t].iss_fmode),
                    inm->inm_st[t].iss_asm,
                    inm->inm_st[t].iss_ex,
                    inm->inm_st[t].iss_in,
                    inm->inm_st[t].iss_rec);
        }
        printf("%s: --- end inm 0x%llx ---\n", __func__,
            (uint64_t)VM_KERNEL_ADDRPERM(inm));
}

#else

void
inm_print(__unused const struct in_multi *inm)
{

}

#endif