[apple/xnu.git] / bsd / netinet6 / in6_mcast.c

/*
 * Copyright (c) 2010-2017 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) 2009 Bruce Simpson.
 * 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.
 */

/*
 * IPv6 multicast socket, group, and socket option processing module.
 * Normative references: RFC 2292, RFC 3492, RFC 3542, RFC 3678, RFC 3810.
 */

#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/net_api_stats.h>
#include <net/route.h>

#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet6/in6_var.h>
#include <netinet/ip6.h>
#include <netinet/icmp6.h>
#include <netinet6/ip6_var.h>
#include <netinet/in_pcb.h>
#include <netinet/tcp.h>
#include <netinet/tcp_seq.h>
#include <netinet/tcp_var.h>
#include <netinet6/nd6.h>
#include <netinet6/mld6_var.h>
#include <netinet6/scope6_var.h>

static void     im6f_commit(struct in6_mfilter *);
static int      im6f_get_source(struct in6_mfilter *imf,
                    const struct sockaddr_in6 *psin,
                    struct in6_msource **);
static struct in6_msource *
                im6f_graft(struct in6_mfilter *, const uint8_t,
                    const struct sockaddr_in6 *);
static int      im6f_prune(struct in6_mfilter *, const struct sockaddr_in6 *);
static void     im6f_rollback(struct in6_mfilter *);
static void     im6f_reap(struct in6_mfilter *);
static int      im6o_grow(struct ip6_moptions *, size_t);
static size_t   im6o_match_group(const struct ip6_moptions *,
                    const struct ifnet *, const struct sockaddr_in6 *);
static struct in6_msource *
                im6o_match_source(const struct ip6_moptions *,
                    const size_t, const struct sockaddr_in6 *);
static void     im6s_merge(struct ip6_msource *ims,
                    const struct in6_msource *lims, const int rollback);
static int      in6_mc_get(struct ifnet *, const struct in6_addr *,
                    struct in6_multi **);
static int      in6m_get_source(struct in6_multi *inm,
                    const struct in6_addr *addr, const int noalloc,
                    struct ip6_msource **pims);
static int      in6m_is_ifp_detached(const struct in6_multi *);
static int      in6m_merge(struct in6_multi *, /*const*/ struct in6_mfilter *);
static void     in6m_reap(struct in6_multi *);
static struct ip6_moptions *
                in6p_findmoptions(struct inpcb *);
static int      in6p_get_source_filters(struct inpcb *, struct sockopt *);
static int      in6p_lookup_v4addr(struct ipv6_mreq *, struct ip_mreq *);
static int      in6p_join_group(struct inpcb *, struct sockopt *);
static int      in6p_leave_group(struct inpcb *, struct sockopt *);
static struct ifnet *
                in6p_lookup_mcast_ifp(const struct inpcb *,
                    const struct sockaddr_in6 *);
static int      in6p_block_unblock_source(struct inpcb *, struct sockopt *);
static int      in6p_set_multicast_if(struct inpcb *, struct sockopt *);
static int      in6p_set_source_filters(struct inpcb *, struct sockopt *);
static int      sysctl_ip6_mcast_filters SYSCTL_HANDLER_ARGS;
static __inline__ int ip6_msource_cmp(const struct ip6_msource *,
                    const struct ip6_msource *);

SYSCTL_DECL(_net_inet6_ip6);    /* XXX Not in any common header. */

SYSCTL_NODE(_net_inet6_ip6, OID_AUTO, mcast, CTLFLAG_RW | CTLFLAG_LOCKED, 0, "IPv6 multicast");

static unsigned long in6_mcast_maxgrpsrc = IPV6_MAX_GROUP_SRC_FILTER;
SYSCTL_LONG(_net_inet6_ip6_mcast, OID_AUTO, maxgrpsrc,
    CTLFLAG_RW | CTLFLAG_LOCKED, &in6_mcast_maxgrpsrc, 
    "Max source filters per group");

static unsigned long in6_mcast_maxsocksrc = IPV6_MAX_SOCK_SRC_FILTER;
SYSCTL_LONG(_net_inet6_ip6_mcast, OID_AUTO, maxsocksrc,
    CTLFLAG_RW | CTLFLAG_LOCKED, &in6_mcast_maxsocksrc, 
    "Max source filters per socket");

int in6_mcast_loop = IPV6_DEFAULT_MULTICAST_LOOP;
SYSCTL_INT(_net_inet6_ip6_mcast, OID_AUTO, loop, CTLFLAG_RW | CTLFLAG_LOCKED,
    &in6_mcast_loop, 0, "Loopback multicast datagrams by default");

SYSCTL_NODE(_net_inet6_ip6_mcast, OID_AUTO, filters,
    CTLFLAG_RD | CTLFLAG_LOCKED, sysctl_ip6_mcast_filters,
    "Per-interface stack-wide source filters");

RB_GENERATE_PREV(ip6_msource_tree, ip6_msource, im6s_link, ip6_msource_cmp);

#define IN6M_TRACE_HIST_SIZE    32      /* size of trace history */

/* For gdb */
__private_extern__ unsigned int in6m_trace_hist_size = IN6M_TRACE_HIST_SIZE;

struct in6_multi_dbg {
        struct in6_multi        in6m;                   /* in6_multi */
        u_int16_t               in6m_refhold_cnt;       /* # of ref */
        u_int16_t               in6m_refrele_cnt;       /* # of rele */
        /*
         * Circular lists of in6m_addref and in6m_remref callers.
         */
        ctrace_t                in6m_refhold[IN6M_TRACE_HIST_SIZE];
        ctrace_t                in6m_refrele[IN6M_TRACE_HIST_SIZE];
        /*
         * Trash list linkage
         */
        TAILQ_ENTRY(in6_multi_dbg) in6m_trash_link;
};

/* List of trash in6_multi entries protected by in6m_trash_lock */
static TAILQ_HEAD(, in6_multi_dbg) in6m_trash_head;
static decl_lck_mtx_data(, in6m_trash_lock);

#if DEBUG
static unsigned int in6m_debug = 1;             /* debugging (enabled) */
#else
static unsigned int in6m_debug;                 /* debugging (disabled) */
#endif /* !DEBUG */
static unsigned int in6m_size;                  /* size of zone element */
static struct zone *in6m_zone;                  /* zone for in6_multi */

#define IN6M_ZONE_MAX           64              /* maximum elements in zone */
#define IN6M_ZONE_NAME          "in6_multi"     /* zone name */

static unsigned int imm_size;                   /* size of zone element */
static struct zone *imm_zone;                   /* zone for in6_multi_mship */

#define IMM_ZONE_MAX            64              /* maximum elements in zone */
#define IMM_ZONE_NAME           "in6_multi_mship" /* zone name */

#define IP6MS_ZONE_MAX          64              /* maximum elements in zone */
#define IP6MS_ZONE_NAME         "ip6_msource"   /* zone name */

static unsigned int ip6ms_size;                 /* size of zone element */
static struct zone *ip6ms_zone;                 /* zone for ip6_msource */

#define IN6MS_ZONE_MAX          64              /* maximum elements in zone */
#define IN6MS_ZONE_NAME         "in6_msource"   /* zone name */

static unsigned int in6ms_size;                 /* size of zone element */
static struct zone *in6ms_zone;                 /* zone for in6_msource */

/* Lock group and attribute for in6_multihead_lock lock */
static lck_attr_t       *in6_multihead_lock_attr;
static lck_grp_t        *in6_multihead_lock_grp;
static lck_grp_attr_t   *in6_multihead_lock_grp_attr;

static decl_lck_rw_data(, in6_multihead_lock);
struct in6_multihead in6_multihead;

static struct in6_multi *in6_multi_alloc(int);
static void in6_multi_free(struct in6_multi *);
static void in6_multi_attach(struct in6_multi *);
static struct in6_multi_mship *in6_multi_mship_alloc(int);
static void in6_multi_mship_free(struct in6_multi_mship *);
static void in6m_trace(struct in6_multi *, int);

static struct ip6_msource *ip6ms_alloc(int);
static void ip6ms_free(struct ip6_msource *);
static struct in6_msource *in6ms_alloc(int);
static void in6ms_free(struct in6_msource *);

/*
 * IPv6 source tree comparison function.
 *
 * An ordered predicate is necessary; bcmp() is not documented to return
 * an indication of order, memcmp() is, and is an ISO C99 requirement.
 */
static __inline int
ip6_msource_cmp(const struct ip6_msource *a, const struct ip6_msource *b)
{
        return (memcmp(&a->im6s_addr, &b->im6s_addr, sizeof(struct in6_addr)));
}

/*
 * Inline function which wraps assertions for a valid ifp.
 */
static __inline__ int
in6m_is_ifp_detached(const struct in6_multi *inm)
{
        VERIFY(inm->in6m_ifma != NULL);
        VERIFY(inm->in6m_ifp == inm->in6m_ifma->ifma_ifp);

        return (!ifnet_is_attached(inm->in6m_ifp, 0));
}

/*
 * Initialize an in6_mfilter structure to a known state at t0, t1
 * with an empty source filter list.
 */
static __inline__ void
im6f_init(struct in6_mfilter *imf, const int st0, const int st1)
{
        memset(imf, 0, sizeof(struct in6_mfilter));
        RB_INIT(&imf->im6f_sources);
        imf->im6f_st[0] = st0;
        imf->im6f_st[1] = st1;
}

/*
 * Resize the ip6_moptions vector to the next power-of-two minus 1.
 */
static int
im6o_grow(struct ip6_moptions *imo, size_t newmax)
{
        struct in6_multi        **nmships;
        struct in6_multi        **omships;
        struct in6_mfilter       *nmfilters;
        struct in6_mfilter       *omfilters;
        size_t                    idx;
        size_t                    oldmax;

        IM6O_LOCK_ASSERT_HELD(imo);

        nmships = NULL;
        nmfilters = NULL;
        omships = imo->im6o_membership;
        omfilters = imo->im6o_mfilters;
        oldmax = imo->im6o_max_memberships;
        if (newmax == 0)
                newmax = ((oldmax + 1) * 2) - 1;

        if (newmax > IPV6_MAX_MEMBERSHIPS)
                return (ETOOMANYREFS);

        if ((nmships = (struct in6_multi **)_REALLOC(omships,
            sizeof (struct in6_multi *) * newmax, M_IP6MOPTS,
            M_WAITOK | M_ZERO)) == NULL)
                return (ENOMEM);

        imo->im6o_membership = nmships;

        if ((nmfilters = (struct in6_mfilter *)_REALLOC(omfilters,
            sizeof (struct in6_mfilter) * newmax, M_IN6MFILTER,
            M_WAITOK | M_ZERO)) == NULL)
                return (ENOMEM);

        imo->im6o_mfilters = nmfilters;

        /* Initialize newly allocated source filter heads. */
        for (idx = oldmax; idx < newmax; idx++)
                im6f_init(&nmfilters[idx], MCAST_UNDEFINED, MCAST_EXCLUDE);

        imo->im6o_max_memberships = newmax;

        return (0);
}

/*
 * Find an IPv6 multicast group entry for this ip6_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
im6o_match_group(const struct ip6_moptions *imo, const struct ifnet *ifp,
    const struct sockaddr_in6 *group)
{
        const struct sockaddr_in6 *gsin6;
        struct in6_multi *pinm;
        int               idx;
        int               nmships;

        IM6O_LOCK_ASSERT_HELD(__DECONST(struct ip6_moptions *, imo));

        gsin6 = group;

        /* The im6o_membership array may be lazy allocated. */
        if (imo->im6o_membership == NULL || imo->im6o_num_memberships == 0)
                return (-1);

        nmships = imo->im6o_num_memberships;
        for (idx = 0; idx < nmships; idx++) {
                pinm = imo->im6o_membership[idx];
                if (pinm == NULL)
                        continue;
                IN6M_LOCK(pinm);
                if ((ifp == NULL || (pinm->in6m_ifp == ifp)) &&
                    IN6_ARE_ADDR_EQUAL(&pinm->in6m_addr,
                    &gsin6->sin6_addr)) {
                        IN6M_UNLOCK(pinm);
                        break;
                }
                IN6M_UNLOCK(pinm);
        }
        if (idx >= nmships)
                idx = -1;

        return (idx);
}

/*
 * Find an IPv6 multicast source entry for this imo which matches
 * the given group index for this socket, and source address.
 *
 * XXX TODO: The scope ID, if present in src, is stripped before
 * any comparison. We SHOULD enforce scope/zone checks where the source
 * filter entry has a link scope.
 *
 * NOTE: This does not check if the entry is in-mode, merely if
 * it exists, which may not be the desired behaviour.
 */
static struct in6_msource *
im6o_match_source(const struct ip6_moptions *imo, const size_t gidx,
    const struct sockaddr_in6 *src)
{
        struct ip6_msource       find;
        struct in6_mfilter      *imf;
        struct ip6_msource      *ims;
        const struct sockaddr_in6 *psa;

        IM6O_LOCK_ASSERT_HELD(__DECONST(struct ip6_moptions *, imo));

        VERIFY(src->sin6_family == AF_INET6);
        VERIFY(gidx != (size_t)-1 && gidx < imo->im6o_num_memberships);

        /* The im6o_mfilters array may be lazy allocated. */
        if (imo->im6o_mfilters == NULL)
                return (NULL);
        imf = &imo->im6o_mfilters[gidx];

        psa = src;
        find.im6s_addr = psa->sin6_addr;
        in6_clearscope(&find.im6s_addr);                /* XXX */
        ims = RB_FIND(ip6_msource_tree, &imf->im6f_sources, &find);

        return ((struct in6_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
im6o_mc_filter(const struct ip6_moptions *imo, const struct ifnet *ifp,
    const struct sockaddr_in6 *group, const struct sockaddr_in6 *src)
{
        size_t gidx;
        struct in6_msource *ims;
        int mode;

        IM6O_LOCK_ASSERT_HELD(__DECONST(struct ip6_moptions *, imo));
        VERIFY(ifp != NULL);

        gidx = im6o_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 MLD t1 (now)
         * with socket-layer t0 (since last downcall).
         */
        mode = imo->im6o_mfilters[gidx].im6f_st[1];
        ims = im6o_match_source(imo, gidx, src);

        if ((ims == NULL && mode == MCAST_INCLUDE) ||
            (ims != NULL && ims->im6sl_st[0] != mode))
                return (MCAST_NOTSMEMBER);

        return (MCAST_PASS);
}

/*
 * Find and return a reference to an in6_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.
 * Assumes the IN6_MULTI lock is held across the call.
 * Return 0 if successful, otherwise return an appropriate error code.
 */
static int
in6_mc_get(struct ifnet *ifp, const struct in6_addr *group,
    struct in6_multi **pinm)
{
        struct sockaddr_in6      gsin6;
        struct ifmultiaddr      *ifma;
        struct in6_multi        *inm;
        int                      error;

        *pinm = NULL;

        in6_multihead_lock_shared();
        IN6_LOOKUP_MULTI(group, ifp, inm);
        if (inm != NULL) {
                IN6M_LOCK(inm);
                VERIFY(inm->in6m_reqcnt >= 1);
                inm->in6m_reqcnt++;
                VERIFY(inm->in6m_reqcnt != 0);
                *pinm = inm;
                IN6M_UNLOCK(inm);
                in6_multihead_lock_done();
                /*
                 * We already joined this group; return the in6m
                 * with a refcount held (via lookup) for caller.
                 */
                return (0);
        }
        in6_multihead_lock_done();

        memset(&gsin6, 0, sizeof(gsin6));
        gsin6.sin6_family = AF_INET6;
        gsin6.sin6_len = sizeof(struct sockaddr_in6);
        gsin6.sin6_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 *)&gsin6, &ifma);
        if (error != 0)
                return (error);

        /*
         * See comments in in6m_remref() for access to ifma_protospec.
         */
        in6_multihead_lock_exclusive();
        IFMA_LOCK(ifma);
        if ((inm = ifma->ifma_protospec) != NULL) {
                VERIFY(ifma->ifma_addr != NULL);
                VERIFY(ifma->ifma_addr->sa_family == AF_INET6);
                IN6M_ADDREF(inm);       /* for caller */
                IFMA_UNLOCK(ifma);
                IN6M_LOCK(inm);
                VERIFY(inm->in6m_ifma == ifma);
                VERIFY(inm->in6m_ifp == ifp);
                VERIFY(IN6_ARE_ADDR_EQUAL(&inm->in6m_addr, group));
                if (inm->in6m_debug & IFD_ATTACHED) {
                        VERIFY(inm->in6m_reqcnt >= 1);
                        inm->in6m_reqcnt++;
                        VERIFY(inm->in6m_reqcnt != 0);
                        *pinm = inm;
                        IN6M_UNLOCK(inm);
                        in6_multihead_lock_done();
                        IFMA_REMREF(ifma);
                        /*
                         * We lost the race with another thread doing
                         * in6_mc_get(); 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 in6_delmulti();
                 * the inm referring to the ifma has been detached, thus we
                 * reattach it back to the in6_multihead list, and return the
                 * inm with a refcount held for the caller.
                 */
                in6_multi_attach(inm);
                VERIFY((inm->in6m_debug &
                    (IFD_ATTACHED | IFD_TRASHED)) == IFD_ATTACHED);
                *pinm = inm;
                IN6M_UNLOCK(inm);
                in6_multihead_lock_done();
                IFMA_REMREF(ifma);
                return (0);
        }
        IFMA_UNLOCK(ifma);

        /*
         * A new in6_multi record is needed; allocate and initialize it.
         * We DO NOT perform an MLD join as the in6_ layer may need to
         * push an initial source list down to MLD to support SSM.
         *
         * The initial source filter state is INCLUDE, {} as per the RFC.
         * Pending state-changes per group are subject to a bounds check.
         */
        inm = in6_multi_alloc(M_WAITOK);
        if (inm == NULL) {
                in6_multihead_lock_done();
                IFMA_REMREF(ifma);
                return (ENOMEM);
        }
        IN6M_LOCK(inm);
        inm->in6m_addr = *group;
        inm->in6m_ifp = ifp;
        inm->in6m_mli = MLD_IFINFO(ifp);
        VERIFY(inm->in6m_mli != NULL);
        MLI_ADDREF(inm->in6m_mli);
        inm->in6m_ifma = ifma;          /* keep refcount from if_addmulti() */
        inm->in6m_state = MLD_NOT_MEMBER;
        /*
         * Pending state-changes per group are subject to a bounds check.
         */
        inm->in6m_scq.ifq_maxlen = MLD_MAX_STATE_CHANGES;
        inm->in6m_st[0].iss_fmode = MCAST_UNDEFINED;
        inm->in6m_st[1].iss_fmode = MCAST_UNDEFINED;
        RB_INIT(&inm->in6m_srcs);
        *pinm = inm;
        in6_multi_attach(inm);
        VERIFY((inm->in6m_debug &
            (IFD_ATTACHED | IFD_TRASHED)) == IFD_ATTACHED);
        IN6M_ADDREF_LOCKED(inm);        /* for caller */
        IN6M_UNLOCK(inm);

        IFMA_LOCK(ifma);
        VERIFY(ifma->ifma_protospec == NULL);
        ifma->ifma_protospec = inm;
        IFMA_UNLOCK(ifma);
        in6_multihead_lock_done();

        return (0);
}

/*
 * Clear recorded source entries for a group.
 * Used by the MLD code. Caller must hold the IN6_MULTI lock.
 * FIXME: Should reap.
 */
void
in6m_clear_recorded(struct in6_multi *inm)
{
        struct ip6_msource      *ims;

        IN6M_LOCK_ASSERT_HELD(inm);

        RB_FOREACH(ims, ip6_msource_tree, &inm->in6m_srcs) {
                if (ims->im6s_stp) {
                        ims->im6s_stp = 0;
                        --inm->in6m_st[1].iss_rec;
                }
        }
        VERIFY(inm->in6m_st[1].iss_rec == 0);
}

/*
 * Record a source as pending for a Source-Group MLDv2 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.inet6.mld.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.
 *
 * VIMAGE: XXX: Currently the mld_sgalloc feature has been removed.
 * This turns off the allocation of a recorded source entry if
 * the group has not been joined.
 *
 * 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
in6m_record_source(struct in6_multi *inm, const struct in6_addr *addr)
{
        struct ip6_msource       find;
        struct ip6_msource      *ims, *nims;

        IN6M_LOCK_ASSERT_HELD(inm);

        find.im6s_addr = *addr;
        ims = RB_FIND(ip6_msource_tree, &inm->in6m_srcs, &find);
        if (ims && ims->im6s_stp)
                return (0);
        if (ims == NULL) {
                if (inm->in6m_nsrc == in6_mcast_maxgrpsrc)
                        return (-ENOSPC);
                nims = ip6ms_alloc(M_WAITOK);
                if (nims == NULL)
                        return (-ENOMEM);
                nims->im6s_addr = find.im6s_addr;
                RB_INSERT(ip6_msource_tree, &inm->in6m_srcs, nims);
                ++inm->in6m_nsrc;
                ims = nims;
        }

        /*
         * Mark the source as recorded and update the recorded
         * source count.
         */
        ++ims->im6s_stp;
        ++inm->in6m_st[1].iss_rec;

        return (1);
}

/*
 * Return a pointer to an in6_msource owned by an in6_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.
 * addr is the source address.
 *
 * Caller is expected to be holding im6o_lock.
 */
static int
im6f_get_source(struct in6_mfilter *imf, const struct sockaddr_in6 *psin,
    struct in6_msource **plims)
{
        struct ip6_msource       find;
        struct ip6_msource      *ims;
        struct in6_msource      *lims;
        int                      error;

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

        find.im6s_addr = psin->sin6_addr;
        ims = RB_FIND(ip6_msource_tree, &imf->im6f_sources, &find);
        lims = (struct in6_msource *)ims;
        if (lims == NULL) {
                if (imf->im6f_nsrc == in6_mcast_maxsocksrc)
                        return (ENOSPC);
                lims = in6ms_alloc(M_WAITOK);
                if (lims == NULL)
                        return (ENOMEM);
                lims->im6s_addr = find.im6s_addr;
                lims->im6sl_st[0] = MCAST_UNDEFINED;
                RB_INSERT(ip6_msource_tree, &imf->im6f_sources,
                    (struct ip6_msource *)lims);
                ++imf->im6f_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 im6o_lock.
 */
static struct in6_msource *
im6f_graft(struct in6_mfilter *imf, const uint8_t st1,
    const struct sockaddr_in6 *psin)
{
        struct in6_msource      *lims;

        lims = in6ms_alloc(M_WAITOK);
        if (lims == NULL)
                return (NULL);
        lims->im6s_addr = psin->sin6_addr;
        lims->im6sl_st[0] = MCAST_UNDEFINED;
        lims->im6sl_st[1] = st1;
        RB_INSERT(ip6_msource_tree, &imf->im6f_sources,
            (struct ip6_msource *)lims);
        ++imf->im6f_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 im6o_lock.
 */
static int
im6f_prune(struct in6_mfilter *imf, const struct sockaddr_in6 *psin)
{
        struct ip6_msource       find;
        struct ip6_msource      *ims;
        struct in6_msource      *lims;

        find.im6s_addr = psin->sin6_addr;
        ims = RB_FIND(ip6_msource_tree, &imf->im6f_sources, &find);
        if (ims == NULL)
                return (ENOENT);
        lims = (struct in6_msource *)ims;
        lims->im6sl_st[1] = MCAST_UNDEFINED;
        return (0);
}

/*
 * Revert socket-layer filter set deltas at t1 to t0 state.
 *
 * Caller is expected to be holding im6o_lock.
 */
static void
im6f_rollback(struct in6_mfilter *imf)
{
        struct ip6_msource      *ims, *tims;
        struct in6_msource      *lims;

        RB_FOREACH_SAFE(ims, ip6_msource_tree, &imf->im6f_sources, tims) {
                lims = (struct in6_msource *)ims;
                if (lims->im6sl_st[0] == lims->im6sl_st[1]) {
                        /* no change at t1 */
                        continue;
                } else if (lims->im6sl_st[0] != MCAST_UNDEFINED) {
                        /* revert change to existing source at t1 */
                        lims->im6sl_st[1] = lims->im6sl_st[0];
                } else {
                        /* revert source added t1 */
                        MLD_PRINTF(("%s: free in6ms 0x%llx\n", __func__,
                            (uint64_t)VM_KERNEL_ADDRPERM(lims)));
                        RB_REMOVE(ip6_msource_tree, &imf->im6f_sources, ims);
                        in6ms_free(lims);
                        imf->im6f_nsrc--;
                }
        }
        imf->im6f_st[1] = imf->im6f_st[0];
}

/*
 * Mark socket-layer filter set as INCLUDE {} at t1.
 *
 * Caller is expected to be holding im6o_lock.
 */
void
im6f_leave(struct in6_mfilter *imf)
{
        struct ip6_msource      *ims;
        struct in6_msource      *lims;

        RB_FOREACH(ims, ip6_msource_tree, &imf->im6f_sources) {
                lims = (struct in6_msource *)ims;
                lims->im6sl_st[1] = MCAST_UNDEFINED;
        }
        imf->im6f_st[1] = MCAST_INCLUDE;
}

/*
 * Mark socket-layer filter set deltas as committed.
 *
 * Caller is expected to be holding im6o_lock.
 */
static void
im6f_commit(struct in6_mfilter *imf)
{
        struct ip6_msource      *ims;
        struct in6_msource      *lims;

        RB_FOREACH(ims, ip6_msource_tree, &imf->im6f_sources) {
                lims = (struct in6_msource *)ims;
                lims->im6sl_st[0] = lims->im6sl_st[1];
        }
        imf->im6f_st[0] = imf->im6f_st[1];
}

/*
 * Reap unreferenced sources from socket-layer filter set.
 *
 * Caller is expected to be holding im6o_lock.
 */
static void
im6f_reap(struct in6_mfilter *imf)
{
        struct ip6_msource      *ims, *tims;
        struct in6_msource      *lims;

        RB_FOREACH_SAFE(ims, ip6_msource_tree, &imf->im6f_sources, tims) {
                lims = (struct in6_msource *)ims;
                if ((lims->im6sl_st[0] == MCAST_UNDEFINED) &&
                    (lims->im6sl_st[1] == MCAST_UNDEFINED)) {
                        MLD_PRINTF(("%s: free in6ms 0x%llx\n", __func__,
                            (uint64_t)VM_KERNEL_ADDRPERM(lims)));
                        RB_REMOVE(ip6_msource_tree, &imf->im6f_sources, ims);
                        in6ms_free(lims);
                        imf->im6f_nsrc--;
                }
        }
}

/*
 * Purge socket-layer filter set.
 *
 * Caller is expected to be holding im6o_lock.
 */
void
im6f_purge(struct in6_mfilter *imf)
{
        struct ip6_msource      *ims, *tims;
        struct in6_msource      *lims;

        RB_FOREACH_SAFE(ims, ip6_msource_tree, &imf->im6f_sources, tims) {
                lims = (struct in6_msource *)ims;
                MLD_PRINTF(("%s: free in6ms 0x%llx\n", __func__,
                    (uint64_t)VM_KERNEL_ADDRPERM(lims)));
                RB_REMOVE(ip6_msource_tree, &imf->im6f_sources, ims);
                in6ms_free(lims);
                imf->im6f_nsrc--;
        }
        imf->im6f_st[0] = imf->im6f_st[1] = MCAST_UNDEFINED;
        VERIFY(RB_EMPTY(&imf->im6f_sources));
}

/*
 * Look up a source filter entry for a multicast group.
 *
 * inm is the group descriptor to work with.
 * addr is the IPv6 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
in6m_get_source(struct in6_multi *inm, const struct in6_addr *addr,
    const int noalloc, struct ip6_msource **pims)
{
        struct ip6_msource       find;
        struct ip6_msource      *ims, *nims;

        IN6M_LOCK_ASSERT_HELD(inm);

        find.im6s_addr = *addr;
        ims = RB_FIND(ip6_msource_tree, &inm->in6m_srcs, &find);
        if (ims == NULL && !noalloc) {
                if (inm->in6m_nsrc == in6_mcast_maxgrpsrc)
                        return (ENOSPC);
                nims = ip6ms_alloc(M_WAITOK);
                if (nims == NULL)
                        return (ENOMEM);
                nims->im6s_addr = *addr;
                RB_INSERT(ip6_msource_tree, &inm->in6m_srcs, nims);
                ++inm->in6m_nsrc;
                ims = nims;
                MLD_PRINTF(("%s: allocated %s as 0x%llx\n", __func__,
                    ip6_sprintf(addr), (uint64_t)VM_KERNEL_ADDRPERM(ims)));
        }

        *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
im6s_get_mode(const struct in6_multi *inm, const struct ip6_msource *ims,
    uint8_t t)
{
        IN6M_LOCK_ASSERT_HELD(__DECONST(struct in6_multi *, inm));

        t = !!t;
        if (inm->in6m_st[t].iss_ex > 0 &&
            inm->in6m_st[t].iss_ex == ims->im6s_st[t].ex)
                return (MCAST_EXCLUDE);
        else if (ims->im6s_st[t].in > 0 && ims->im6s_st[t].ex == 0)
                return (MCAST_INCLUDE);
        return (MCAST_UNDEFINED);
}

/*
 * Merge socket-layer source into MLD-layer source.
 * If rollback is non-zero, perform the inverse of the merge.
 */
static void
im6s_merge(struct ip6_msource *ims, const struct in6_msource *lims,
    const int rollback)
{
        int n = rollback ? -1 : 1;

        if (lims->im6sl_st[0] == MCAST_EXCLUDE) {
                MLD_PRINTF(("%s: t1 ex -= %d on %s\n", __func__, n,
                    ip6_sprintf(&lims->im6s_addr)));
                ims->im6s_st[1].ex -= n;
        } else if (lims->im6sl_st[0] == MCAST_INCLUDE) {
                MLD_PRINTF(("%s: t1 in -= %d on %s\n", __func__, n,
                    ip6_sprintf(&lims->im6s_addr)));
                ims->im6s_st[1].in -= n;
        }

        if (lims->im6sl_st[1] == MCAST_EXCLUDE) {
                MLD_PRINTF(("%s: t1 ex += %d on %s\n", __func__, n,
                    ip6_sprintf(&lims->im6s_addr)));
                ims->im6s_st[1].ex += n;
        } else if (lims->im6sl_st[1] == MCAST_INCLUDE) {
                MLD_PRINTF(("%s: t1 in += %d on %s\n", __func__, n,
                    ip6_sprintf(&lims->im6s_addr)));
                ims->im6s_st[1].in += n;
        }
}

/*
 * Atomically update the global in6_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
in6m_merge(struct in6_multi *inm, /*const*/ struct in6_mfilter *imf)
{
        struct ip6_msource      *ims, *nims = NULL;
        struct in6_msource      *lims;
        int                      schanged, error;
        int                      nsrc0, nsrc1;

        IN6M_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, ip6_msource_tree, &imf->im6f_sources) {
                lims = (struct in6_msource *)ims;
                if (lims->im6sl_st[0] == imf->im6f_st[0]) nsrc0++;
                if (lims->im6sl_st[1] == imf->im6f_st[1]) nsrc1++;
                if (lims->im6sl_st[0] == lims->im6sl_st[1]) continue;
                error = in6m_get_source(inm, &lims->im6s_addr, 0, &nims);
                ++schanged;
                if (error)
                        break;
                im6s_merge(nims, lims, 0);
        }
        if (error) {
                struct ip6_msource *bims;

                RB_FOREACH_REVERSE_FROM(ims, ip6_msource_tree, nims) {
                        lims = (struct in6_msource *)ims;
                        if (lims->im6sl_st[0] == lims->im6sl_st[1])
                                continue;
                        (void) in6m_get_source(inm, &lims->im6s_addr, 1, &bims);
                        if (bims == NULL)
                                continue;
                        im6s_merge(bims, lims, 1);
                }
                goto out_reap;
        }

        MLD_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->im6f_st[0] == imf->im6f_st[1] &&
            imf->im6f_st[1] == MCAST_INCLUDE) {
                if (nsrc1 == 0) {
                        MLD_PRINTF(("%s: --in on inm at t1\n", __func__));
                        --inm->in6m_st[1].iss_in;
                }
        }

        /* Handle filter mode transition on socket. */
        if (imf->im6f_st[0] != imf->im6f_st[1]) {
                MLD_PRINTF(("%s: imf transition %d to %d\n",
                    __func__, imf->im6f_st[0], imf->im6f_st[1]));

                if (imf->im6f_st[0] == MCAST_EXCLUDE) {
                        MLD_PRINTF(("%s: --ex on inm at t1\n", __func__));
                        --inm->in6m_st[1].iss_ex;
                } else if (imf->im6f_st[0] == MCAST_INCLUDE) {
                        MLD_PRINTF(("%s: --in on inm at t1\n", __func__));
                        --inm->in6m_st[1].iss_in;
                }

                if (imf->im6f_st[1] == MCAST_EXCLUDE) {
                        MLD_PRINTF(("%s: ex++ on inm at t1\n", __func__));
                        inm->in6m_st[1].iss_ex++;
                } else if (imf->im6f_st[1] == MCAST_INCLUDE && nsrc1 > 0) {
                        MLD_PRINTF(("%s: in++ on inm at t1\n", __func__));
                        inm->in6m_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 MLD lifecycle for this group should finish.
         */
        if (inm->in6m_st[1].iss_ex > 0) {
                MLD_PRINTF(("%s: transition to EX\n", __func__));
                inm->in6m_st[1].iss_fmode = MCAST_EXCLUDE;
        } else if (inm->in6m_st[1].iss_in > 0) {
                MLD_PRINTF(("%s: transition to IN\n", __func__));
                inm->in6m_st[1].iss_fmode = MCAST_INCLUDE;
        } else {
                MLD_PRINTF(("%s: transition to UNDEF\n", __func__));
                inm->in6m_st[1].iss_fmode = MCAST_UNDEFINED;
        }

        /* Decrement ASM listener count on transition out of ASM mode. */
        if (imf->im6f_st[0] == MCAST_EXCLUDE && nsrc0 == 0) {
                if ((imf->im6f_st[1] != MCAST_EXCLUDE) ||
                    (imf->im6f_st[1] == MCAST_EXCLUDE && nsrc1 > 0)) {
                        MLD_PRINTF(("%s: --asm on inm at t1\n", __func__));
                        --inm->in6m_st[1].iss_asm;
                }
        }

        /* Increment ASM listener count on transition to ASM mode. */
        if (imf->im6f_st[1] == MCAST_EXCLUDE && nsrc1 == 0) {
                MLD_PRINTF(("%s: asm++ on inm at t1\n", __func__));
                inm->in6m_st[1].iss_asm++;
        }

        MLD_PRINTF(("%s: merged imf 0x%llx to inm 0x%llx\n", __func__,
            (uint64_t)VM_KERNEL_ADDRPERM(imf),
            (uint64_t)VM_KERNEL_ADDRPERM(inm)));
        in6m_print(inm);

out_reap:
        if (schanged > 0) {
                MLD_PRINTF(("%s: sources changed; reaping\n", __func__));
                in6m_reap(inm);
        }
        return (error);
}

/*
 * Mark an in6_multi's filter set deltas as committed.
 * Called by MLD after a state change has been enqueued.
 */
void
in6m_commit(struct in6_multi *inm)
{
        struct ip6_msource      *ims;

        IN6M_LOCK_ASSERT_HELD(inm);

        MLD_PRINTF(("%s: commit inm 0x%llx\n", __func__,
            (uint64_t)VM_KERNEL_ADDRPERM(inm)));
        MLD_PRINTF(("%s: pre commit:\n", __func__));
        in6m_print(inm);

        RB_FOREACH(ims, ip6_msource_tree, &inm->in6m_srcs) {
                ims->im6s_st[0] = ims->im6s_st[1];
        }
        inm->in6m_st[0] = inm->in6m_st[1];
}

/*
 * Reap unreferenced nodes from an in6_multi's filter set.
 */
static void
in6m_reap(struct in6_multi *inm)
{
        struct ip6_msource      *ims, *tims;

        IN6M_LOCK_ASSERT_HELD(inm);

        RB_FOREACH_SAFE(ims, ip6_msource_tree, &inm->in6m_srcs, tims) {
                if (ims->im6s_st[0].ex > 0 || ims->im6s_st[0].in > 0 ||
                    ims->im6s_st[1].ex > 0 || ims->im6s_st[1].in > 0 ||
                    ims->im6s_stp != 0)
                        continue;
                MLD_PRINTF(("%s: free ims 0x%llx\n", __func__,
                    (uint64_t)VM_KERNEL_ADDRPERM(ims)));
                RB_REMOVE(ip6_msource_tree, &inm->in6m_srcs, ims);
                ip6ms_free(ims);
                inm->in6m_nsrc--;
        }
}

/*
 * Purge all source nodes from an in6_multi's filter set.
 */
void
in6m_purge(struct in6_multi *inm)
{
        struct ip6_msource      *ims, *tims;

        IN6M_LOCK_ASSERT_HELD(inm);

        RB_FOREACH_SAFE(ims, ip6_msource_tree, &inm->in6m_srcs, tims) {
                MLD_PRINTF(("%s: free ims 0x%llx\n", __func__,
                    (uint64_t)VM_KERNEL_ADDRPERM(ims)));
                RB_REMOVE(ip6_msource_tree, &inm->in6m_srcs, ims);
                ip6ms_free(ims);
                inm->in6m_nsrc--;
        }
}

/*
 * Join a multicast address w/o sources.
 * KAME compatibility entry point.
 *
 */
struct in6_multi_mship *
in6_joingroup(struct ifnet *ifp, struct in6_addr *mcaddr,
    int *errorp, int delay)
{
        struct in6_multi_mship *imm;
        int error;

        *errorp = 0;

        imm = in6_multi_mship_alloc(M_WAITOK);
        if (imm == NULL) {
                *errorp = ENOBUFS;
                return (NULL);
        }

        error = in6_mc_join(ifp, mcaddr, NULL, &imm->i6mm_maddr, delay);
        if (error) {
                *errorp = error;
                in6_multi_mship_free(imm);
                return (NULL);
        }

        return (imm);
}

/*
 * Leave a multicast address w/o sources.
 * KAME compatibility entry point.
 */
int
in6_leavegroup(struct in6_multi_mship *imm)
{
        if (imm->i6mm_maddr != NULL) {
                in6_mc_leave(imm->i6mm_maddr, NULL);
                IN6M_REMREF(imm->i6mm_maddr);
                imm->i6mm_maddr = NULL;
        }
        in6_multi_mship_free(imm);
        return 0;
}

/*
 * 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 MLD downcall fails, the group is not joined, and an error
 * code is returned.
 */
int
in6_mc_join(struct ifnet *ifp, const struct in6_addr *mcaddr,
    /*const*/ struct in6_mfilter *imf, struct in6_multi **pinm,
    const int delay)
{
        struct in6_mfilter       timf;
        struct in6_multi        *inm = NULL;
        int                      error = 0;
        struct mld_tparams       mtp;

        /*
         * Sanity: Check scope zone ID was set for ifp, if and
         * only if group is scoped to an interface.
         */
        VERIFY(IN6_IS_ADDR_MULTICAST(mcaddr));
        if (IN6_IS_ADDR_MC_LINKLOCAL(mcaddr) ||
            IN6_IS_ADDR_MC_INTFACELOCAL(mcaddr)) {
                VERIFY(mcaddr->s6_addr16[1] != 0);
        }

        MLD_PRINTF(("%s: join %s on 0x%llx(%s))\n", __func__,
            ip6_sprintf(mcaddr), (uint64_t)VM_KERNEL_ADDRPERM(ifp),
            if_name(ifp)));

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

        /*
         * If no imf was specified (i.e. kernel consumer),
         * fake one up and assume it is an ASM join.
         */
        if (imf == NULL) {
                im6f_init(&timf, MCAST_UNDEFINED, MCAST_EXCLUDE);
                imf = &timf;
        }

        error = in6_mc_get(ifp, mcaddr, &inm);
        if (error) {
                MLD_PRINTF(("%s: in6_mc_get() failure\n", __func__));
                return (error);
        }

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

        IN6M_LOCK(inm);
        error = in6m_merge(inm, imf);
        if (error) {
                MLD_PRINTF(("%s: failed to merge inm state\n", __func__));
                goto out_in6m_release;
        }

        MLD_PRINTF(("%s: doing mld downcall\n", __func__));
        error = mld_change_state(inm, &mtp, delay);
        if (error) {
                MLD_PRINTF(("%s: failed to update source\n", __func__));
                im6f_rollback(imf);
                goto out_in6m_release;
        }

out_in6m_release:
        if (error) {
                MLD_PRINTF(("%s: dropping ref on 0x%llx\n", __func__,
                    (uint64_t)VM_KERNEL_ADDRPERM(inm)));
                IN6M_UNLOCK(inm);
                IN6M_REMREF(inm);
        } else {
                IN6M_UNLOCK(inm);
                *pinm = inm;    /* keep refcount from in6_mc_get() */
        }

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

        return (error);
}

/*
 * Leave a multicast group; real entry point.
 * All source filters will be expunged.
 *
 * Only preserves atomicity at inm level.
 *
 * Holding the write lock for the INP which contains imf
 * is highly advisable. We can't assert for it as imf does not
 * contain a back-pointer to the owning inp.
 *
 * Note: This is not the same as in6m_release(*) as this function also
 * makes a state change downcall into MLD.
 */
int
in6_mc_leave(struct in6_multi *inm, /*const*/ struct in6_mfilter *imf)
{
        struct in6_mfilter       timf;
        int                      error, lastref;
        struct mld_tparams       mtp;

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

        IN6M_LOCK_ASSERT_NOTHELD(inm);

        in6_multihead_lock_exclusive();
        IN6M_LOCK(inm);

        MLD_PRINTF(("%s: leave inm 0x%llx, %s/%s%d, imf 0x%llx\n", __func__,
            (uint64_t)VM_KERNEL_ADDRPERM(inm), ip6_sprintf(&inm->in6m_addr),
            (in6m_is_ifp_detached(inm) ? "null" : inm->in6m_ifp->if_name),
            inm->in6m_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) {
                im6f_init(&timf, MCAST_EXCLUDE, MCAST_UNDEFINED);
                imf = &timf;
        }

        /*
         * Begin state merge transaction at MLD 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.
         */
        MLD_PRINTF(("%s: merge inm state\n", __func__));

        error = in6m_merge(inm, imf);
        KASSERT(error == 0, ("%s: failed to merge inm state\n", __func__));

        MLD_PRINTF(("%s: doing mld downcall\n", __func__));
        error = mld_change_state(inm, &mtp, 0);
#if MLD_DEBUG
        if (error)
                MLD_PRINTF(("%s: failed mld downcall\n", __func__));
#endif
        lastref = in6_multi_detach(inm);
        VERIFY(!lastref || (!(inm->in6m_debug & IFD_ATTACHED) &&
            inm->in6m_reqcnt == 0));
        IN6M_UNLOCK(inm);
        in6_multihead_lock_done();

        if (lastref)
                IN6M_REMREF(inm);       /* for in6_multihead list */

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

        return (error);
}

/*
 * 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 MLD downcall will be performed.
 *
 * Return 0 if successful, otherwise return an appropriate error code.
 */
static int
in6p_block_unblock_source(struct inpcb *inp, struct sockopt *sopt)
{
        struct group_source_req          gsr;
        struct sockaddr_in6             *gsa, *ssa;
        struct ifnet                    *ifp;
        struct in6_mfilter              *imf;
        struct ip6_moptions             *imo;
        struct in6_msource              *ims;
        struct in6_multi                *inm;
        size_t                           idx;
        uint16_t                         fmode;
        int                              error, doblock;
        struct mld_tparams               mtp;

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

        memset(&gsr, 0, sizeof(struct group_source_req));
        gsa = (struct sockaddr_in6 *)&gsr.gsr_group;
        ssa = (struct sockaddr_in6 *)&gsr.gsr_source;

        switch (sopt->sopt_name) {
        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->sin6_family != AF_INET6 ||
                    gsa->sin6_len != sizeof(struct sockaddr_in6))
                        return (EINVAL);

                if (ssa->sin6_family != AF_INET6 ||
                    ssa->sin6_len != sizeof(struct sockaddr_in6))
                        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:
                MLD_PRINTF(("%s: unknown sopt_name %d\n",
                    __func__, sopt->sopt_name));
                return (EOPNOTSUPP);
        }

        if (!IN6_IS_ADDR_MULTICAST(&gsa->sin6_addr))
                return (EINVAL);

        (void) in6_setscope(&gsa->sin6_addr, ifp, NULL);

        /*
         * Check if we are actually a member of this group.
         */
        imo = in6p_findmoptions(inp);
        if (imo == NULL)
                return (ENOMEM);

        IM6O_LOCK(imo);
        idx = im6o_match_group(imo, ifp, gsa);
        if (idx == (size_t)-1 || imo->im6o_mfilters == NULL) {
                error = EADDRNOTAVAIL;
                goto out_imo_locked;
        }

        VERIFY(imo->im6o_mfilters != NULL);
        imf = &imo->im6o_mfilters[idx];
        inm = imo->im6o_membership[idx];

        /*
         * Attempting to use the delta-based API on an
         * non exclusive-mode membership is an error.
         */
        fmode = imf->im6f_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 = im6o_match_source(imo, idx, ssa);
        if ((ims != NULL && doblock) || (ims == NULL && !doblock)) {
                MLD_PRINTF(("%s: source %s %spresent\n", __func__,
                    ip6_sprintf(&ssa->sin6_addr),
                    doblock ? "" : "not "));
                error = EADDRNOTAVAIL;
                goto out_imo_locked;
        }

        /*
         * Begin state merge transaction at socket layer.
         */
        if (doblock) {
                MLD_PRINTF(("%s: %s source\n", __func__, "block"));
                ims = im6f_graft(imf, fmode, ssa);
                if (ims == NULL)
                        error = ENOMEM;
        } else {
                MLD_PRINTF(("%s: %s source\n", __func__, "allow"));
                error = im6f_prune(imf, ssa);
        }

        if (error) {
                MLD_PRINTF(("%s: merge imf state failed\n", __func__));
                goto out_im6f_rollback;
        }

        /*
         * Begin state merge transaction at MLD layer.
         */
        IN6M_LOCK(inm);
        MLD_PRINTF(("%s: merge inm state\n", __func__));
        error = in6m_merge(inm, imf);
        if (error) {
                MLD_PRINTF(("%s: failed to merge inm state\n", __func__));
                IN6M_UNLOCK(inm);
                goto out_im6f_rollback;
        }

        MLD_PRINTF(("%s: doing mld downcall\n", __func__));
        error = mld_change_state(inm, &mtp, 0);
        IN6M_UNLOCK(inm);
#if MLD_DEBUG
        if (error)
                MLD_PRINTF(("%s: failed mld downcall\n", __func__));
#endif

out_im6f_rollback:
        if (error)
                im6f_rollback(imf);
        else
                im6f_commit(imf);

        im6f_reap(imf);

out_imo_locked:
        IM6O_UNLOCK(imo);
        IM6O_REMREF(imo);       /* from in6p_findmoptions() */

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

        return (error);
}

/*
 * Given an inpcb, return its multicast options structure pointer.  Accepts
 * an unlocked inpcb pointer, but will return it locked.  May sleep.
 *
 */
static struct ip6_moptions *
in6p_findmoptions(struct inpcb *inp)
{
        struct ip6_moptions      *imo;
        struct in6_multi        **immp;
        struct in6_mfilter       *imfp;
        size_t                    idx;

        if ((imo = inp->in6p_moptions) != NULL) {
                IM6O_ADDREF(imo);       /* for caller */
                return (imo);
        }

        imo = ip6_allocmoptions(M_WAITOK);
        if (imo == NULL)
                return (NULL);

        immp = _MALLOC(sizeof (*immp) * IPV6_MIN_MEMBERSHIPS, M_IP6MOPTS,
            M_WAITOK | M_ZERO);
        if (immp == NULL) {
                IM6O_REMREF(imo);
                return (NULL);
        }

        imfp = _MALLOC(sizeof (struct in6_mfilter) * IPV6_MIN_MEMBERSHIPS,
            M_IN6MFILTER, M_WAITOK | M_ZERO);
        if (imfp == NULL) {
                _FREE(immp, M_IP6MOPTS);
                IM6O_REMREF(imo);
                return (NULL);
        }

        imo->im6o_multicast_ifp = NULL;
        imo->im6o_multicast_hlim = ip6_defmcasthlim;
        imo->im6o_multicast_loop = in6_mcast_loop;
        imo->im6o_num_memberships = 0;
        imo->im6o_max_memberships = IPV6_MIN_MEMBERSHIPS;
        imo->im6o_membership = immp;

        /* Initialize per-group source filters. */
        for (idx = 0; idx < IPV6_MIN_MEMBERSHIPS; idx++)
                im6f_init(&imfp[idx], MCAST_UNDEFINED, MCAST_EXCLUDE);

        imo->im6o_mfilters = imfp;
        inp->in6p_moptions = imo; /* keep reference from ip6_allocmoptions() */
        IM6O_ADDREF(imo);       /* for caller */

        return (imo);
}

/*
 * Atomically get source filters on a socket for an IPv6 multicast group.
 * Called with INP lock held; returns with lock released.
 */
static int
in6p_get_source_filters(struct inpcb *inp, struct sockopt *sopt)
{
        struct __msfilterreq64  msfr = {}, msfr64;
        struct __msfilterreq32  msfr32;
        struct sockaddr_in6     *gsa;
        struct ifnet            *ifp;
        struct ip6_moptions     *imo;
        struct in6_mfilter      *imf;
        struct ip6_msource      *ims;
        struct in6_msource      *lims;
        struct sockaddr_in6     *psin;
        struct sockaddr_storage *ptss;
        struct sockaddr_storage *tss;
        int                      error;
        size_t                   idx, nsrcs, ncsrcs;
        user_addr_t              tmp_ptr;

        imo = inp->in6p_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(msfr64));
        } 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(msfr32));
        }

        if (msfr.msfr_group.ss_family != AF_INET6 ||
            msfr.msfr_group.ss_len != sizeof(struct sockaddr_in6))
                return (EINVAL);

        gsa = (struct sockaddr_in6 *)&msfr.msfr_group;
        if (!IN6_IS_ADDR_MULTICAST(&gsa->sin6_addr))
                return (EINVAL);

        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 > in6_mcast_maxsocksrc)
                msfr.msfr_nsrcs = in6_mcast_maxsocksrc;

        (void)in6_setscope(&gsa->sin6_addr, ifp, NULL);

        IM6O_LOCK(imo);
        /*
         * Lookup group on the socket.
         */
        idx = im6o_match_group(imo, ifp, gsa);
        if (idx == (size_t)-1 || imo->im6o_mfilters == NULL) {
                IM6O_UNLOCK(imo);
                return (EADDRNOTAVAIL);
        }
        imf = &imo->im6o_mfilters[idx];

        /*
         * Ignore memberships which are in limbo.
         */
        if (imf->im6f_st[1] == MCAST_UNDEFINED) {
                IM6O_UNLOCK(imo);
                return (EAGAIN);
        }
        msfr.msfr_fmode = imf->im6f_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.
         */
        tss = NULL;

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

        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) {
                        IM6O_UNLOCK(imo);
                        return (ENOBUFS);
                }
        }

        /*
         * 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, ip6_msource_tree, &imf->im6f_sources) {
                lims = (struct in6_msource *)ims;
                if (lims->im6sl_st[0] == MCAST_UNDEFINED ||
                    lims->im6sl_st[0] != imf->im6f_st[0])
                        continue;
                if (tss != NULL && nsrcs > 0) {
                        psin = (struct sockaddr_in6 *)ptss;
                        psin->sin6_family = AF_INET6;
                        psin->sin6_len = sizeof(struct sockaddr_in6);
                        psin->sin6_addr = lims->im6s_addr;
                        psin->sin6_port = 0;
                        --nsrcs;
                        ++ptss;
                        ++ncsrcs;
                }
        }

        IM6O_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(&msfr32.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
ip6_getmoptions(struct inpcb *inp, struct sockopt *sopt)
{
        struct ip6_moptions     *im6o;
        int                      error;
        u_int                    optval;

        im6o = inp->in6p_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) {
        case IPV6_MULTICAST_IF:
                if (im6o != NULL)
                        IM6O_LOCK(im6o);
                if (im6o == NULL || im6o->im6o_multicast_ifp == NULL) {
                        optval = 0;
                } else {
                        optval = im6o->im6o_multicast_ifp->if_index;
                }
                if (im6o != NULL)
                        IM6O_UNLOCK(im6o);
                error = sooptcopyout(sopt, &optval, sizeof(u_int));
                break;

        case IPV6_MULTICAST_HOPS:
                if (im6o == NULL) {
                        optval = ip6_defmcasthlim;
                } else {
                        IM6O_LOCK(im6o);
                        optval = im6o->im6o_multicast_hlim;
                        IM6O_UNLOCK(im6o);
                }
                error = sooptcopyout(sopt, &optval, sizeof(u_int));
                break;

        case IPV6_MULTICAST_LOOP:
                if (im6o == NULL) {
                        optval = in6_mcast_loop; /* XXX VIMAGE */
                } else {
                        IM6O_LOCK(im6o);
                        optval = im6o->im6o_multicast_loop;
                        IM6O_UNLOCK(im6o);
                }
                error = sooptcopyout(sopt, &optval, sizeof(u_int));
                break;

        case IPV6_MSFILTER:
                if (im6o == NULL) {
                        error = EADDRNOTAVAIL;
                } else {
                        error = in6p_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 address of an IPv6 group.
 *
 * This routine exists to support legacy IPv6 multicast applications.
 *
 * 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, return NULL.
 *
 * FUTURE: Support multiple forwarding tables for IPv6.
 *
 * Returns NULL if no ifp could be found.
 */
static struct ifnet *
in6p_lookup_mcast_ifp(const struct inpcb *in6p,
    const struct sockaddr_in6 *gsin6)
{
        struct route_in6         ro6;
        struct ifnet            *ifp;
        unsigned int            ifscope = IFSCOPE_NONE;

        VERIFY(in6p == NULL || (in6p->inp_vflag & INP_IPV6));
        VERIFY(gsin6->sin6_family == AF_INET6);
        if (IN6_IS_ADDR_MULTICAST(&gsin6->sin6_addr) == 0)  
                return NULL;

        if (in6p != NULL && (in6p->inp_flags & INP_BOUND_IF))
                ifscope = in6p->inp_boundifp->if_index;

        ifp = NULL;
        memset(&ro6, 0, sizeof(struct route_in6));
        memcpy(&ro6.ro_dst, gsin6, sizeof(struct sockaddr_in6));
        rtalloc_scoped_ign((struct route *)&ro6, 0, ifscope);
        if (ro6.ro_rt != NULL) {
                ifp = ro6.ro_rt->rt_ifp;
                VERIFY(ifp != NULL);
        }
        ROUTE_RELEASE(&ro6);

        return (ifp);
}

/*
 * Since ipv6_mreq contains an ifindex and ip_mreq contains an AF_INET
 * address, we need to lookup the AF_INET address when translating an
 * ipv6_mreq structure into an ipmreq structure.
 * This is used when userland performs multicast setsockopt() on AF_INET6
 * sockets with AF_INET multicast addresses (IPv6 v4 mapped addresses).
 */
static int
in6p_lookup_v4addr(struct ipv6_mreq *mreq, struct ip_mreq *v4mreq)
{
        struct ifnet *ifp;
        struct ifaddr *ifa;
        struct sockaddr_in *sin;

        ifnet_head_lock_shared();
        if (mreq->ipv6mr_interface > (unsigned int)if_index) {
                ifnet_head_done();
                return (EADDRNOTAVAIL);
        } else
                ifp = ifindex2ifnet[mreq->ipv6mr_interface];
        ifnet_head_done();
        if (ifp == NULL)
                return (EADDRNOTAVAIL);
        ifa = ifa_ifpgetprimary(ifp, AF_INET);
        if (ifa == NULL)
                return (EADDRNOTAVAIL);
        sin = (struct sockaddr_in *)(uintptr_t)(size_t)ifa->ifa_addr;
        v4mreq->imr_interface.s_addr = sin->sin_addr.s_addr;
        IFA_REMREF(ifa);

        return (0);
}

/*
 * Join an IPv6 multicast group, possibly with a source.
 *
 * FIXME: The KAME use of the unspecified address (::)
 * to join *all* multicast groups is currently unsupported.
 */
static int
in6p_join_group(struct inpcb *inp, struct sockopt *sopt)
{
        struct group_source_req          gsr;
        struct sockaddr_in6             *gsa, *ssa;
        struct ifnet                    *ifp;
        struct in6_mfilter              *imf;
        struct ip6_moptions             *imo;
        struct in6_multi                *inm = NULL;
        struct in6_msource              *lims = NULL;
        size_t                           idx;
        int                              error, is_new;
        uint32_t                        scopeid = 0;
        struct mld_tparams              mtp;

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

        memset(&gsr, 0, sizeof(struct group_source_req));
        gsa = (struct sockaddr_in6 *)&gsr.gsr_group;
        ssa = (struct sockaddr_in6 *)&gsr.gsr_source;

        /*
         * Chew everything into struct group_source_req.
         * Overwrite the port field if present, as the sockaddr
         * being copied in may be matched with a binary comparison.
         * Ignore passed-in scope ID.
         */
        switch (sopt->sopt_name) {
        case IPV6_JOIN_GROUP: {
                struct ipv6_mreq mreq;

                error = sooptcopyin(sopt, &mreq, sizeof(struct ipv6_mreq),
                    sizeof(struct ipv6_mreq));
                if (error)
                        return (error);
                if (IN6_IS_ADDR_V4MAPPED(&mreq.ipv6mr_multiaddr)) {
                        struct ip_mreq v4mreq;
                        struct sockopt v4sopt;

                        v4mreq.imr_multiaddr.s_addr =
                            mreq.ipv6mr_multiaddr.s6_addr32[3];
                        if (mreq.ipv6mr_interface == 0) 
                                v4mreq.imr_interface.s_addr = INADDR_ANY;
                        else
                                error = in6p_lookup_v4addr(&mreq, &v4mreq);
                        if (error)
                                return (error);
                        v4sopt.sopt_dir     = SOPT_SET;
                        v4sopt.sopt_level   = sopt->sopt_level; 
                        v4sopt.sopt_name    = IP_ADD_MEMBERSHIP;
                        v4sopt.sopt_val     = CAST_USER_ADDR_T(&v4mreq);
                        v4sopt.sopt_valsize = sizeof(v4mreq);
                        v4sopt.sopt_p       = kernproc;

                        return (inp_join_group(inp, &v4sopt));
                }
                gsa->sin6_family = AF_INET6;
                gsa->sin6_len = sizeof(struct sockaddr_in6);
                gsa->sin6_addr = mreq.ipv6mr_multiaddr;

                /* Only allow IPv6 multicast addresses */       
                if (IN6_IS_ADDR_MULTICAST(&gsa->sin6_addr) == 0) {
                        return (EINVAL);
                }

                if (mreq.ipv6mr_interface == 0) {
                        ifp = in6p_lookup_mcast_ifp(inp, gsa);
                } else {
                        ifnet_head_lock_shared();
                        if ((u_int)if_index < mreq.ipv6mr_interface) {
                                ifnet_head_done();
                                return (EADDRNOTAVAIL);
                            }
                        ifp = ifindex2ifnet[mreq.ipv6mr_interface];
                        ifnet_head_done();
                }
                MLD_PRINTF(("%s: ipv6mr_interface = %d, ifp = 0x%llx\n",
                    __func__, mreq.ipv6mr_interface,
                    (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->sin6_family != AF_INET6 ||
                    gsa->sin6_len != sizeof(struct sockaddr_in6))
                        return (EINVAL);

                if (sopt->sopt_name == MCAST_JOIN_SOURCE_GROUP) {
                        if (ssa->sin6_family != AF_INET6 ||
                            ssa->sin6_len != sizeof(struct sockaddr_in6))
                                return (EINVAL);
                        if (IN6_IS_ADDR_MULTICAST(&ssa->sin6_addr))
                                return (EINVAL);
                        /*
                         * TODO: Validate embedded scope ID in source
                         * list entry against passed-in ifp, if and only
                         * if source list filter entry is iface or node local.
                         */
                        in6_clearscope(&ssa->sin6_addr);
                        ssa->sin6_port = 0;
                        ssa->sin6_scope_id = 0;
                }

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

        if (!IN6_IS_ADDR_MULTICAST(&gsa->sin6_addr))
                return (EINVAL);

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

        INC_ATOMIC_INT64_LIM(net_api_stats.nas_socket_mcast_join_total);
        /*
         * TBD: revisit the criteria for non-OS initiated joins
         */
        if (inp->inp_lport == htons(5353)) {
                INC_ATOMIC_INT64_LIM(net_api_stats.nas_socket_mcast_join_os_total);
        }

        gsa->sin6_port = 0;
        gsa->sin6_scope_id = 0;

        /*
         * Always set the scope zone ID on memberships created from userland.
         * Use the passed-in ifp to do this.
         */
        (void)in6_setscope(&gsa->sin6_addr, ifp, &scopeid);
        /*
         * Some addresses are not valid without an embedded scopeid.
         * This check must be present because otherwise we will later hit
         * a VERIFY() in in6_mc_join().
         */
        if ((IN6_IS_ADDR_MC_LINKLOCAL(&gsa->sin6_addr) ||
            IN6_IS_ADDR_MC_INTFACELOCAL(&gsa->sin6_addr)) &&
            (scopeid == 0 || gsa->sin6_addr.s6_addr16[1] == 0))
                return (EINVAL);

        imo = in6p_findmoptions(inp);
        if (imo == NULL)
                return (ENOMEM);

        IM6O_LOCK(imo);
        idx = im6o_match_group(imo, ifp, gsa);
        if (idx == (size_t)-1) {
                is_new = 1;
        } else {
                inm = imo->im6o_membership[idx];
                imf = &imo->im6o_mfilters[idx];
                if (ssa->sin6_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->im6f_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).
                         *
                         * in6_msource is transactioned just as for anything
                         * else in SSM -- but note naive use of in6m_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 = im6o_match_source(imo, idx, ssa);
                        if (lims != NULL /*&&
                            lims->im6sl_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->im6f_st[1] == MCAST_EXCLUDE)
                                error = EADDRINUSE;
                        goto out_imo_locked;
                }
        }

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

        if (is_new) {
                if (imo->im6o_num_memberships == imo->im6o_max_memberships) {
                        error = im6o_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->im6o_num_memberships;
                imo->im6o_membership[idx] = NULL;
                imo->im6o_num_memberships++;
                VERIFY(imo->im6o_mfilters != NULL);
                imf = &imo->im6o_mfilters[idx];
                VERIFY(RB_EMPTY(&imf->im6f_sources));
        }

        /*
         * Graft new source into filter list for this inpcb's
         * membership of the group. The in6_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.
         *
         * Note: Grafting of exclusive mode filters doesn't happen
         * in this path.
         * XXX: Should check for non-NULL lims (node exists but may
         * not be in-mode) for interop with full-state API.
         */
        if (ssa->sin6_family != AF_UNSPEC) {
                /* Membership starts in IN mode */
                if (is_new) {
                        MLD_PRINTF(("%s: new join w/source\n", __func__);
                        im6f_init(imf, MCAST_UNDEFINED, MCAST_INCLUDE));
                } else {
                        MLD_PRINTF(("%s: %s source\n", __func__, "allow"));
                }
                lims = im6f_graft(imf, MCAST_INCLUDE, ssa);
                if (lims == NULL) {
                        MLD_PRINTF(("%s: merge imf state failed\n",
                            __func__));
                        error = ENOMEM;
                        goto out_im6o_free;
                }
        } else {
                /* No address specified; Membership starts in EX mode */
                if (is_new) {
                        MLD_PRINTF(("%s: new join w/o source", __func__));
                        im6f_init(imf, MCAST_UNDEFINED, MCAST_EXCLUDE);
                }
        }

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

        if (is_new) {
                /*
                 * See inp_join_group() for why we need to unlock
                 */
                IM6O_ADDREF_LOCKED(imo);
                IM6O_UNLOCK(imo);
                socket_unlock(inp->inp_socket, 0);

                VERIFY(inm == NULL);
                error = in6_mc_join(ifp, &gsa->sin6_addr, imf, &inm, 0);
                VERIFY(inm != NULL || error != 0);

                socket_lock(inp->inp_socket, 0);
                IM6O_REMREF(imo);
                IM6O_LOCK(imo);

                if (error)
                        goto out_im6o_free;
                imo->im6o_membership[idx] = inm; /* from in6_mc_join() */
        } else {
                MLD_PRINTF(("%s: merge inm state\n", __func__));
                IN6M_LOCK(inm);
                error = in6m_merge(inm, imf);
                if (error) {
                        MLD_PRINTF(("%s: failed to merge inm state\n",
                            __func__));
                        IN6M_UNLOCK(inm);
                        goto out_im6f_rollback;
                }
                MLD_PRINTF(("%s: doing mld downcall\n", __func__));
                error = mld_change_state(inm, &mtp, 0);
                IN6M_UNLOCK(inm);
                if (error) {
                        MLD_PRINTF(("%s: failed mld downcall\n",
                            __func__));
                        goto out_im6f_rollback;
                }
        }

out_im6f_rollback:
        if (error) {
                im6f_rollback(imf);
                if (is_new)
                        im6f_purge(imf);
                else
                        im6f_reap(imf);
        } else {
                im6f_commit(imf);
        }

out_im6o_free:
        if (error && is_new) {
                VERIFY(inm == NULL);
                imo->im6o_membership[idx] = NULL;
                --imo->im6o_num_memberships;
        }

out_imo_locked:
        IM6O_UNLOCK(imo);
        IM6O_REMREF(imo);       /* from in6p_findmoptions() */

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

        return (error);
}

/*
 * Leave an IPv6 multicast group on an inpcb, possibly with a source.
 */
static int
in6p_leave_group(struct inpcb *inp, struct sockopt *sopt)
{
        struct ipv6_mreq                 mreq;
        struct group_source_req          gsr;
        struct sockaddr_in6             *gsa, *ssa;
        struct ifnet                    *ifp;
        struct in6_mfilter              *imf;
        struct ip6_moptions             *imo;
        struct in6_msource              *ims;
        struct in6_multi                *inm = NULL;
        uint32_t                         ifindex = 0;
        size_t                           idx;
        int                              error, is_final;
        struct mld_tparams               mtp;

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

        memset(&gsr, 0, sizeof(struct group_source_req));
        gsa = (struct sockaddr_in6 *)&gsr.gsr_group;
        ssa = (struct sockaddr_in6 *)&gsr.gsr_source;

        /*
         * Chew everything passed in up into a struct group_source_req
         * as that is easier to process.
         * Note: Any embedded scope ID in the multicast group passed
         * in by userland is ignored, the interface index is the recommended
         * mechanism to specify an interface; see below.
         */
        switch (sopt->sopt_name) {
        case IPV6_LEAVE_GROUP: {

                error = sooptcopyin(sopt, &mreq, sizeof(struct ipv6_mreq),
                    sizeof(struct ipv6_mreq));
                if (error)
                        return (error);
                if (IN6_IS_ADDR_V4MAPPED(&mreq.ipv6mr_multiaddr)) {
                        struct ip_mreq v4mreq;
                        struct sockopt v4sopt;

                        v4mreq.imr_multiaddr.s_addr =
                            mreq.ipv6mr_multiaddr.s6_addr32[3];
                        if (mreq.ipv6mr_interface == 0) 
                                v4mreq.imr_interface.s_addr = INADDR_ANY;
                        else
                                error = in6p_lookup_v4addr(&mreq, &v4mreq);
                        if (error)
                                return (error);
                        v4sopt.sopt_dir     = SOPT_SET;
                        v4sopt.sopt_level   = sopt->sopt_level; 
                        v4sopt.sopt_name    = IP_DROP_MEMBERSHIP;
                        v4sopt.sopt_val     = CAST_USER_ADDR_T(&v4mreq);
                        v4sopt.sopt_valsize = sizeof(v4mreq);
                        v4sopt.sopt_p       = kernproc;

                        return (inp_leave_group(inp, &v4sopt));
                }
                gsa->sin6_family = AF_INET6;
                gsa->sin6_len = sizeof(struct sockaddr_in6);
                gsa->sin6_addr = mreq.ipv6mr_multiaddr;
                gsa->sin6_port = 0;
                gsa->sin6_scope_id = 0;
                ifindex = mreq.ipv6mr_interface;
                /* Only allow IPv6 multicast addresses */       
                if (IN6_IS_ADDR_MULTICAST(&gsa->sin6_addr) == 0) {
                        return (EINVAL);
                }
                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->sin6_family != AF_INET6 ||
                    gsa->sin6_len != sizeof(struct sockaddr_in6))
                        return (EINVAL);
                if (sopt->sopt_name == MCAST_LEAVE_SOURCE_GROUP) {
                        if (ssa->sin6_family != AF_INET6 ||
                            ssa->sin6_len != sizeof(struct sockaddr_in6))
                                return (EINVAL);
                        if (IN6_IS_ADDR_MULTICAST(&ssa->sin6_addr))
                                return (EINVAL);
                        /*
                         * TODO: Validate embedded scope ID in source
                         * list entry against passed-in ifp, if and only
                         * if source list filter entry is iface or node local.
                         */
                        in6_clearscope(&ssa->sin6_addr);
                }
                gsa->sin6_port = 0;
                gsa->sin6_scope_id = 0;
                ifindex = gsr.gsr_interface;
                break;

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

        if (!IN6_IS_ADDR_MULTICAST(&gsa->sin6_addr))
                return (EINVAL);

        /*
         * Validate interface index if provided. If no interface index
         * was provided separately, attempt to look the membership up
         * from the default scope as a last resort to disambiguate
         * the membership we are being asked to leave.
         * XXX SCOPE6 lock potentially taken here.
         */
        if (ifindex != 0) {
                ifnet_head_lock_shared();
                if ((u_int)if_index < ifindex) {
                        ifnet_head_done();
                        return (EADDRNOTAVAIL);
                }
                ifp = ifindex2ifnet[ifindex];
                ifnet_head_done();
                if (ifp == NULL)
                        return (EADDRNOTAVAIL);
                (void) in6_setscope(&gsa->sin6_addr, ifp, NULL);
        } else {
                error = sa6_embedscope(gsa, ip6_use_defzone);
                if (error)
                        return (EADDRNOTAVAIL);
                /*
                 * Some badly behaved applications don't pass an ifindex
                 * or a scope ID, which is an API violation. In this case,
                 * perform a lookup as per a v6 join.
                 *
                 * XXX For now, stomp on zone ID for the corner case.
                 * This is not the 'KAME way', but we need to see the ifp
                 * directly until such time as this implementation is
                 * refactored, assuming the scope IDs are the way to go.
                 */
                ifindex = ntohs(gsa->sin6_addr.s6_addr16[1]);
                if (ifindex == 0) {
                        MLD_PRINTF(("%s: warning: no ifindex, looking up "
                            "ifp for group %s.\n", __func__,
                            ip6_sprintf(&gsa->sin6_addr)));
                        ifp = in6p_lookup_mcast_ifp(inp, gsa);
                } else {
                        if (!IF_INDEX_IN_RANGE(ifindex))
                                return (EADDRNOTAVAIL);
                        ifnet_head_lock_shared();
                        ifp = ifindex2ifnet[ifindex];
                        ifnet_head_done();
                }
                if (ifp == NULL)
                        return (EADDRNOTAVAIL);
        }

        VERIFY(ifp != NULL);
        MLD_PRINTF(("%s: ifp = 0x%llx\n", __func__,
            (uint64_t)VM_KERNEL_ADDRPERM(ifp)));

        /*
         * Find the membership in the membership array.
         */
        imo = in6p_findmoptions(inp);
        if (imo == NULL)
                return (ENOMEM);

        IM6O_LOCK(imo);
        idx = im6o_match_group(imo, ifp, gsa);
        if (idx == (size_t)-1) {
                error = EADDRNOTAVAIL;
                goto out_locked;
        }
        inm = imo->im6o_membership[idx];
        imf = &imo->im6o_mfilters[idx];

        if (ssa->sin6_family != AF_UNSPEC)
                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) {
                im6f_leave(imf);
        } else {
                if (imf->im6f_st[0] == MCAST_EXCLUDE) {
                        error = EADDRNOTAVAIL;
                        goto out_locked;
                }
                ims = im6o_match_source(imo, idx, ssa);
                if (ims == NULL) {
                        MLD_PRINTF(("%s: source %s %spresent\n", __func__,
                            ip6_sprintf(&ssa->sin6_addr),
                            "not "));
                        error = EADDRNOTAVAIL;
                        goto out_locked;
                }
                MLD_PRINTF(("%s: %s source\n", __func__, "block"));
                error = im6f_prune(imf, ssa);
                if (error) {
                        MLD_PRINTF(("%s: merge imf state failed\n",
                            __func__));
                        goto out_locked;
                }
        }

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

        if (is_final) {
                /*
                 * Give up the multicast address record to which
                 * the membership points.  Reference held in im6o
                 * will be released below.
                 */
                (void) in6_mc_leave(inm, imf);
        } else {
                MLD_PRINTF(("%s: merge inm state\n", __func__));
                IN6M_LOCK(inm);
                error = in6m_merge(inm, imf);
                if (error) {
                        MLD_PRINTF(("%s: failed to merge inm state\n",
                            __func__));
                        IN6M_UNLOCK(inm);
                        goto out_im6f_rollback;
                }

                MLD_PRINTF(("%s: doing mld downcall\n", __func__));
                error = mld_change_state(inm, &mtp, 0);
                if (error) {
                        MLD_PRINTF(("%s: failed mld downcall\n", __func__));
                }
                IN6M_UNLOCK(inm);
        }

out_im6f_rollback:
        if (error)
                im6f_rollback(imf);
        else
                im6f_commit(imf);

        im6f_reap(imf);

        if (is_final) {
                /* Remove the gap in the membership array. */
                VERIFY(inm == imo->im6o_membership[idx]);
                imo->im6o_membership[idx] = NULL;

                /*
                 * See inp_join_group() for why we need to unlock
                 */
                IM6O_ADDREF_LOCKED(imo);
                IM6O_UNLOCK(imo);
                socket_unlock(inp->inp_socket, 0);

                IN6M_REMREF(inm);

                socket_lock(inp->inp_socket, 0);
                IM6O_REMREF(imo);
                IM6O_LOCK(imo);

                for (++idx; idx < imo->im6o_num_memberships; ++idx) {
                        imo->im6o_membership[idx-1] = imo->im6o_membership[idx];
                        imo->im6o_mfilters[idx-1] = imo->im6o_mfilters[idx];
                }
                imo->im6o_num_memberships--;
        }

out_locked:
        IM6O_UNLOCK(imo);
        IM6O_REMREF(imo);       /* from in6p_findmoptions() */

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

        return (error);
}

/*
 * Select the interface for transmitting IPv6 multicast datagrams.
 *
 * Either an instance of struct in6_addr or an instance of struct ipv6_mreqn
 * may be passed to this socket option. An address of in6addr_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
in6p_set_multicast_if(struct inpcb *inp, struct sockopt *sopt)
{
        struct ifnet            *ifp;
        struct ip6_moptions     *imo;
        u_int                    ifindex;
        int                      error;

        if (sopt->sopt_valsize != sizeof(u_int))
                return (EINVAL);

        error = sooptcopyin(sopt, &ifindex, sizeof(u_int), sizeof(u_int));
        if (error)
                return (error);

        ifnet_head_lock_shared();
        if ((u_int)if_index < ifindex) {
                ifnet_head_done();
                return (EINVAL);
        }

        ifp = ifindex2ifnet[ifindex];
        ifnet_head_done();
        if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0)
                return (EADDRNOTAVAIL);

        imo = in6p_findmoptions(inp);
        if (imo == NULL)
                return (ENOMEM);

        IM6O_LOCK(imo);
        imo->im6o_multicast_ifp = ifp;
        IM6O_UNLOCK(imo);
        IM6O_REMREF(imo);       /* from in6p_findmoptions() */

        return (0);
}

/*
 * Atomically set source filters on a socket for an IPv6 multicast group.
 *
 */
static int
in6p_set_source_filters(struct inpcb *inp, struct sockopt *sopt)
{
        struct __msfilterreq64   msfr = {}, msfr64;
        struct __msfilterreq32   msfr32;
        struct sockaddr_in6     *gsa;
        struct ifnet            *ifp;
        struct in6_mfilter      *imf;
        struct ip6_moptions     *imo;
        struct in6_multi        *inm;
        size_t                   idx;
        int                      error;
        user_addr_t              tmp_ptr;
        struct mld_tparams       mtp;

        bzero(&mtp, sizeof (mtp));

        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 > in6_mcast_maxsocksrc)
                return (ENOBUFS);

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

        if (msfr.msfr_group.ss_family != AF_INET6 ||
            msfr.msfr_group.ss_len != sizeof(struct sockaddr_in6))
                return (EINVAL);

        gsa = (struct sockaddr_in6 *)&msfr.msfr_group;
        if (!IN6_IS_ADDR_MULTICAST(&gsa->sin6_addr))
                return (EINVAL);

        gsa->sin6_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);

        (void)in6_setscope(&gsa->sin6_addr, ifp, NULL);

        /*
         * Take the INP write lock.
         * Check if this socket is a member of this group.
         */
        imo = in6p_findmoptions(inp);
        if (imo == NULL)
                return (ENOMEM);

        IM6O_LOCK(imo);
        idx = im6o_match_group(imo, ifp, gsa);
        if (idx == (size_t)-1 || imo->im6o_mfilters == NULL) {
                error = EADDRNOTAVAIL;
                goto out_imo_locked;
        }
        inm = imo->im6o_membership[idx];
        imf = &imo->im6o_mfilters[idx];

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

        imf->im6f_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 in6_msource      *lims;
                struct sockaddr_in6     *psin;
                struct sockaddr_storage *kss, *pkss;
                unsigned int             i;

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

                MLD_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 im6f_leave()
                 * will set it to INCLUDE.
                 */
                im6f_leave(imf);
                imf->im6f_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; i < msfr.msfr_nsrcs; i++, pkss++) {
                        psin = (struct sockaddr_in6 *)pkss;
                        if (psin->sin6_family != AF_INET6) {
                                error = EAFNOSUPPORT;
                                break;
                        }
                        if (psin->sin6_len != sizeof(struct sockaddr_in6)) {
                                error = EINVAL;
                                break;
                        }
                        if (IN6_IS_ADDR_MULTICAST(&psin->sin6_addr)) {
                                error = EINVAL;
                                break;
                        }
                        /*
                         * TODO: Validate embedded scope ID in source
                         * list entry against passed-in ifp, if and only
                         * if source list filter entry is iface or node local.
                         */
                        in6_clearscope(&psin->sin6_addr);
                        error = im6f_get_source(imf, psin, &lims);
                        if (error)
                                break;
                        lims->im6sl_st[1] = imf->im6f_st[1];
                }
                FREE(kss, M_TEMP);
        }

        if (error)
                goto out_im6f_rollback;

        /*
         * Begin state merge transaction at MLD layer.
         */
        IN6M_LOCK(inm);
        MLD_PRINTF(("%s: merge inm state\n", __func__));
        error = in6m_merge(inm, imf);
        if (error) {
                MLD_PRINTF(("%s: failed to merge inm state\n", __func__));
                IN6M_UNLOCK(inm);
                goto out_im6f_rollback;
        }

        MLD_PRINTF(("%s: doing mld downcall\n", __func__));
        error = mld_change_state(inm, &mtp, 0);
        IN6M_UNLOCK(inm);
#if MLD_DEBUG
        if (error)
                MLD_PRINTF(("%s: failed mld downcall\n", __func__));
#endif

out_im6f_rollback:
        if (error)
                im6f_rollback(imf);
        else
                im6f_commit(imf);

        im6f_reap(imf);

out_imo_locked:
        IM6O_UNLOCK(imo);
        IM6O_REMREF(imo);       /* from in6p_findmoptions() */

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

        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 IPv6 multicast part of the BSD Sockets API must be preserved;
 * the effects of these options must be treated as separate and distinct.
 *
 */
int
ip6_setmoptions(struct inpcb *inp, struct sockopt *sopt)
{
        struct ip6_moptions     *im6o;
        int                      error;

        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) {
        case IPV6_MULTICAST_IF:
                error = in6p_set_multicast_if(inp, sopt);
                break;

        case IPV6_MULTICAST_HOPS: {
                int hlim;

                if (sopt->sopt_valsize != sizeof(int)) {
                        error = EINVAL;
                        break;
                }
                error = sooptcopyin(sopt, &hlim, sizeof(hlim), sizeof(int));
                if (error)
                        break;
                if (hlim < -1 || hlim > 255) {
                        error = EINVAL;
                        break;
                } else if (hlim == -1) {
                        hlim = ip6_defmcasthlim;
                }
                im6o = in6p_findmoptions(inp);
                if (im6o == NULL) {
                        error = ENOMEM;
                        break;
                }
                IM6O_LOCK(im6o);
                im6o->im6o_multicast_hlim = hlim;
                IM6O_UNLOCK(im6o);
                IM6O_REMREF(im6o);      /* from in6p_findmoptions() */
                break;
        }

        case IPV6_MULTICAST_LOOP: {
                u_int loop;

                /*
                 * Set the loopback flag for outgoing multicast packets.
                 * Must be zero or one.
                 */
                if (sopt->sopt_valsize != sizeof(u_int)) {
                        error = EINVAL;
                        break;
                }
                error = sooptcopyin(sopt, &loop, sizeof(u_int), sizeof(u_int));
                if (error)
                        break;
                if (loop > 1) {
                        error = EINVAL;
                        break;
                }
                im6o = in6p_findmoptions(inp);
                if (im6o == NULL) {
                        error = ENOMEM;
                        break;
                }
                IM6O_LOCK(im6o);
                im6o->im6o_multicast_loop = loop;
                IM6O_UNLOCK(im6o);
                IM6O_REMREF(im6o);      /* from in6p_findmoptions() */
                break;
        }

        case IPV6_JOIN_GROUP:
        case MCAST_JOIN_GROUP:
        case MCAST_JOIN_SOURCE_GROUP:
                error = in6p_join_group(inp, sopt);
                break;

        case IPV6_LEAVE_GROUP:
        case MCAST_LEAVE_GROUP:
        case MCAST_LEAVE_SOURCE_GROUP:
                error = in6p_leave_group(inp, sopt);
                break;

        case MCAST_BLOCK_SOURCE:
        case MCAST_UNBLOCK_SOURCE:
                error = in6p_block_unblock_source(inp, sopt);
                break;

        case IPV6_MSFILTER:
                error = in6p_set_source_filters(inp, sopt);
                break;

        default:
                error = EOPNOTSUPP;
                break;
        }

        return (error);
}
/*
 * Expose MLD'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 in6_addr.
 * For use by ifmcstat(8).
 */
static int
sysctl_ip6_mcast_filters SYSCTL_HANDLER_ARGS
{
#pragma unused(oidp)

        struct in6_addr                  mcaddr;
        struct in6_addr                  src;
        struct ifnet                    *ifp;
        struct in6_multi                *inm;
        struct in6_multistep            step;
        struct ip6_msource              *ims;
        int                             *name;
        int                              retval = 0;
        u_int                            namelen;
        uint32_t                         fmode, ifindex;

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

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

        /* int: ifindex + 4 * 32 bits of IPv6 address */
        if (namelen != 5)
                return (EINVAL);

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

        memcpy(&mcaddr, &name[1], sizeof(struct in6_addr));
        if (!IN6_IS_ADDR_MULTICAST(&mcaddr)) {
                MLD_PRINTF(("%s: group %s is not multicast\n",
                    __func__, ip6_sprintf(&mcaddr)));
                ifnet_head_done();
                return (EINVAL);
        }

        ifp = ifindex2ifnet[ifindex];
        ifnet_head_done();
        if (ifp == NULL) {
                MLD_PRINTF(("%s: no ifp for ifindex %u\n", __func__, ifindex));
                return (ENOENT);
        }
        /*
         * Internal MLD lookups require that scope/zone ID is set.
         */
        (void)in6_setscope(&mcaddr, ifp, NULL);

        in6_multihead_lock_shared();
        IN6_FIRST_MULTI(step, inm);
        while (inm != NULL) {
                IN6M_LOCK(inm);
                if (inm->in6m_ifp != ifp)
                        goto next;

                if (!IN6_ARE_ADDR_EQUAL(&inm->in6m_addr, &mcaddr))
                        goto next;

                fmode = inm->in6m_st[1].iss_fmode;
                retval = SYSCTL_OUT(req, &fmode, sizeof(uint32_t));
                if (retval != 0) {
                        IN6M_UNLOCK(inm);
                        break;          /* abort */
                }
                RB_FOREACH(ims, ip6_msource_tree, &inm->in6m_srcs) {
                        MLD_PRINTF(("%s: visit node 0x%llx\n", __func__,
                            (uint64_t)VM_KERNEL_ADDRPERM(ims)));
                        /*
                         * Only copy-out sources which are in-mode.
                         */
                        if (fmode != im6s_get_mode(inm, ims, 1)) {
                                MLD_PRINTF(("%s: skip non-in-mode\n",
                                    __func__));
                                continue; /* process next source */
                        }
                        src = ims->im6s_addr;
                        retval = SYSCTL_OUT(req, &src, sizeof(struct in6_addr));
                        if (retval != 0)
                                break;  /* process next inm */
                }
next:
                IN6M_UNLOCK(inm);
                IN6_NEXT_MULTI(step, inm);
        }
        in6_multihead_lock_done();

        return (retval);
}

void
in6_multi_init(void)
{
        PE_parse_boot_argn("ifa_debug", &in6m_debug, sizeof (in6m_debug));

        /* Setup lock group and attribute for in6_multihead */
        in6_multihead_lock_grp_attr = lck_grp_attr_alloc_init();
        in6_multihead_lock_grp = lck_grp_alloc_init("in6_multihead",
            in6_multihead_lock_grp_attr);
        in6_multihead_lock_attr = lck_attr_alloc_init();
        lck_rw_init(&in6_multihead_lock, in6_multihead_lock_grp,
            in6_multihead_lock_attr);

        lck_mtx_init(&in6m_trash_lock, in6_multihead_lock_grp,
            in6_multihead_lock_attr);
        TAILQ_INIT(&in6m_trash_head);

        in6m_size = (in6m_debug == 0) ? sizeof (struct in6_multi) :
            sizeof (struct in6_multi_dbg);
        in6m_zone = zinit(in6m_size, IN6M_ZONE_MAX * in6m_size,
            0, IN6M_ZONE_NAME);
        if (in6m_zone == NULL) {
                panic("%s: failed allocating %s", __func__, IN6M_ZONE_NAME);
                /* NOTREACHED */
        }
        zone_change(in6m_zone, Z_EXPAND, TRUE);

        imm_size = sizeof (struct in6_multi_mship);
        imm_zone = zinit(imm_size, IMM_ZONE_MAX * imm_size, 0, IMM_ZONE_NAME);
        if (imm_zone == NULL) {
                panic("%s: failed allocating %s", __func__, IMM_ZONE_NAME);
                /* NOTREACHED */
        }
        zone_change(imm_zone, Z_EXPAND, TRUE);

        ip6ms_size = sizeof (struct ip6_msource);
        ip6ms_zone = zinit(ip6ms_size, IP6MS_ZONE_MAX * ip6ms_size,
            0, IP6MS_ZONE_NAME);
        if (ip6ms_zone == NULL) {
                panic("%s: failed allocating %s", __func__, IP6MS_ZONE_NAME);
                /* NOTREACHED */
        }
        zone_change(ip6ms_zone, Z_EXPAND, TRUE);

        in6ms_size = sizeof (struct in6_msource);
        in6ms_zone = zinit(in6ms_size, IN6MS_ZONE_MAX * in6ms_size,
            0, IN6MS_ZONE_NAME);
        if (in6ms_zone == NULL) {
                panic("%s: failed allocating %s", __func__, IN6MS_ZONE_NAME);
                /* NOTREACHED */
        }
        zone_change(in6ms_zone, Z_EXPAND, TRUE);
}

static struct in6_multi *
in6_multi_alloc(int how)
{
        struct in6_multi *in6m;

        in6m = (how == M_WAITOK) ? zalloc(in6m_zone) :
            zalloc_noblock(in6m_zone);
        if (in6m != NULL) {
                bzero(in6m, in6m_size);
                lck_mtx_init(&in6m->in6m_lock, in6_multihead_lock_grp,
                    in6_multihead_lock_attr);
                in6m->in6m_debug |= IFD_ALLOC;
                if (in6m_debug != 0) {
                        in6m->in6m_debug |= IFD_DEBUG;
                        in6m->in6m_trace = in6m_trace;
                }
        }
        return (in6m);
}

static void
in6_multi_free(struct in6_multi *in6m)
{
        IN6M_LOCK(in6m);
        if (in6m->in6m_debug & IFD_ATTACHED) {
                panic("%s: attached in6m=%p is being freed", __func__, in6m);
                /* NOTREACHED */
        } else if (in6m->in6m_ifma != NULL) {
                panic("%s: ifma not NULL for in6m=%p", __func__, in6m);
                /* NOTREACHED */
        } else if (!(in6m->in6m_debug & IFD_ALLOC)) {
                panic("%s: in6m %p cannot be freed", __func__, in6m);
                /* NOTREACHED */
        } else if (in6m->in6m_refcount != 0) {
                panic("%s: non-zero refcount in6m=%p", __func__, in6m);
                /* NOTREACHED */
        } else if (in6m->in6m_reqcnt != 0) {
                panic("%s: non-zero reqcnt in6m=%p", __func__, in6m);
                /* NOTREACHED */
        }

        /* Free any pending MLDv2 state-change records */
        IF_DRAIN(&in6m->in6m_scq);

        in6m->in6m_debug &= ~IFD_ALLOC;
        if ((in6m->in6m_debug & (IFD_DEBUG | IFD_TRASHED)) ==
            (IFD_DEBUG | IFD_TRASHED)) {
                lck_mtx_lock(&in6m_trash_lock);
                TAILQ_REMOVE(&in6m_trash_head, (struct in6_multi_dbg *)in6m,
                    in6m_trash_link);
                lck_mtx_unlock(&in6m_trash_lock);
                in6m->in6m_debug &= ~IFD_TRASHED;
        }
        IN6M_UNLOCK(in6m);

        lck_mtx_destroy(&in6m->in6m_lock, in6_multihead_lock_grp);
        zfree(in6m_zone, in6m);
}

static void
in6_multi_attach(struct in6_multi *in6m)
{
        in6_multihead_lock_assert(LCK_RW_ASSERT_EXCLUSIVE);
        IN6M_LOCK_ASSERT_HELD(in6m);

        if (in6m->in6m_debug & IFD_ATTACHED) {
                panic("%s: Attempt to attach an already attached in6m=%p",
                    __func__, in6m);
                /* NOTREACHED */
        }

        in6m->in6m_reqcnt++;
        VERIFY(in6m->in6m_reqcnt == 1);
        IN6M_ADDREF_LOCKED(in6m);
        in6m->in6m_debug |= IFD_ATTACHED;
        /*
         * Reattach case:  If debugging is enabled, take it
         * out of the trash list and clear IFD_TRASHED.
         */
        if ((in6m->in6m_debug & (IFD_DEBUG | IFD_TRASHED)) ==
            (IFD_DEBUG | IFD_TRASHED)) {
                /* Become a regular mutex, just in case */
                IN6M_CONVERT_LOCK(in6m);
                lck_mtx_lock(&in6m_trash_lock);
                TAILQ_REMOVE(&in6m_trash_head, (struct in6_multi_dbg *)in6m,
                    in6m_trash_link);
                lck_mtx_unlock(&in6m_trash_lock);
                in6m->in6m_debug &= ~IFD_TRASHED;
        }

        LIST_INSERT_HEAD(&in6_multihead, in6m, in6m_entry);
}

int
in6_multi_detach(struct in6_multi *in6m)
{
        in6_multihead_lock_assert(LCK_RW_ASSERT_EXCLUSIVE);
        IN6M_LOCK_ASSERT_HELD(in6m);

        if (in6m->in6m_reqcnt == 0) {
                panic("%s: in6m=%p negative reqcnt", __func__, in6m);
                /* NOTREACHED */
        }

        --in6m->in6m_reqcnt;
        if (in6m->in6m_reqcnt > 0)
                return (0);

        if (!(in6m->in6m_debug & IFD_ATTACHED)) {
                panic("%s: Attempt to detach an unattached record in6m=%p",
                    __func__, in6m);
                /* NOTREACHED */
        } else if (in6m->in6m_debug & IFD_TRASHED) {
                panic("%s: in6m %p is already in trash list", __func__, in6m);
                /* NOTREACHED */
        }

        /*
         * NOTE: Caller calls IFMA_REMREF
         */
        in6m->in6m_debug &= ~IFD_ATTACHED;
        LIST_REMOVE(in6m, in6m_entry);

        if (in6m->in6m_debug & IFD_DEBUG) {
                /* Become a regular mutex, just in case */
                IN6M_CONVERT_LOCK(in6m);
                lck_mtx_lock(&in6m_trash_lock);
                TAILQ_INSERT_TAIL(&in6m_trash_head,
                    (struct in6_multi_dbg *)in6m, in6m_trash_link);
                lck_mtx_unlock(&in6m_trash_lock);
                in6m->in6m_debug |= IFD_TRASHED;
        }

        return (1);
}

void
in6m_addref(struct in6_multi *in6m, int locked)
{
        if (!locked)
                IN6M_LOCK_SPIN(in6m);
        else
                IN6M_LOCK_ASSERT_HELD(in6m);

        if (++in6m->in6m_refcount == 0) {
                panic("%s: in6m=%p wraparound refcnt", __func__, in6m);
                /* NOTREACHED */
        } else if (in6m->in6m_trace != NULL) {
                (*in6m->in6m_trace)(in6m, TRUE);
        }
        if (!locked)
                IN6M_UNLOCK(in6m);
}

void
in6m_remref(struct in6_multi *in6m, int locked)
{
        struct ifmultiaddr *ifma;
        struct mld_ifinfo *mli;

        if (!locked)
                IN6M_LOCK_SPIN(in6m);
        else
                IN6M_LOCK_ASSERT_HELD(in6m);

        if (in6m->in6m_refcount == 0 || (in6m->in6m_refcount == 1 && locked)) {
                panic("%s: in6m=%p negative refcnt", __func__, in6m);
                /* NOTREACHED */
        } else if (in6m->in6m_trace != NULL) {
                (*in6m->in6m_trace)(in6m, FALSE);
        }

        --in6m->in6m_refcount;
        if (in6m->in6m_refcount > 0) {
                if (!locked)
                        IN6M_UNLOCK(in6m);
                return;
        }

        /*
         * Synchronization with in6_mc_get().  In the event the in6m 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 in6m is via ifma_protospec.  To avoid
         * race conditions between the last in6m_remref() of that in6m and its
         * use via ifma_protospec, in6_multihead lock is used for serialization.
         * In order to avoid violating the lock order, we must drop in6m_lock
         * before acquiring in6_multihead lock.  To prevent the in6m from being
         * freed prematurely, we hold an extra reference.
         */
        ++in6m->in6m_refcount;
        IN6M_UNLOCK(in6m);
        in6_multihead_lock_shared();
        IN6M_LOCK_SPIN(in6m);
        --in6m->in6m_refcount;
        if (in6m->in6m_refcount > 0) {
                /* We've lost the race, so abort since in6m is still in use */
                IN6M_UNLOCK(in6m);
                in6_multihead_lock_done();
                /* If it was locked, return it as such */
                if (locked)
                        IN6M_LOCK(in6m);
                return;
        }
        in6m_purge(in6m);
        ifma = in6m->in6m_ifma;
        in6m->in6m_ifma = NULL;
        in6m->in6m_ifp = NULL;
        mli = in6m->in6m_mli;
        in6m->in6m_mli = NULL;
        IN6M_UNLOCK(in6m);
        IFMA_LOCK_SPIN(ifma);
        ifma->ifma_protospec = NULL;
        IFMA_UNLOCK(ifma);
        in6_multihead_lock_done();

        in6_multi_free(in6m);
        if_delmulti_ifma(ifma);
        /* Release reference held to the underlying ifmultiaddr */
        IFMA_REMREF(ifma);

        if (mli != NULL)
                MLI_REMREF(mli);
}

static void
in6m_trace(struct in6_multi *in6m, int refhold)
{
        struct in6_multi_dbg *in6m_dbg = (struct in6_multi_dbg *)in6m;
        ctrace_t *tr;
        u_int32_t idx;
        u_int16_t *cnt;

        if (!(in6m->in6m_debug & IFD_DEBUG)) {
                panic("%s: in6m %p has no debug structure", __func__, in6m);
                /* NOTREACHED */
        }
        if (refhold) {
                cnt = &in6m_dbg->in6m_refhold_cnt;
                tr = in6m_dbg->in6m_refhold;
        } else {
                cnt = &in6m_dbg->in6m_refrele_cnt;
                tr = in6m_dbg->in6m_refrele;
        }

        idx = atomic_add_16_ov(cnt, 1) % IN6M_TRACE_HIST_SIZE;
        ctrace_record(&tr[idx]);
}

static struct in6_multi_mship *
in6_multi_mship_alloc(int how)
{
        struct in6_multi_mship *imm;

        imm = (how == M_WAITOK) ? zalloc(imm_zone) : zalloc_noblock(imm_zone);
        if (imm != NULL)
                bzero(imm, imm_size);

        return (imm);
}

static void
in6_multi_mship_free(struct in6_multi_mship *imm)
{
        if (imm->i6mm_maddr != NULL) {
                panic("%s: i6mm_maddr not NULL for imm=%p", __func__, imm);
                /* NOTREACHED */
        }
        zfree(imm_zone, imm);
}

void
in6_multihead_lock_exclusive(void)
{
        lck_rw_lock_exclusive(&in6_multihead_lock);
}

void
in6_multihead_lock_shared(void)
{
        lck_rw_lock_shared(&in6_multihead_lock);
}

void
in6_multihead_lock_assert(int what)
{
#if !MACH_ASSERT
#pragma unused(what)
#endif
        LCK_RW_ASSERT(&in6_multihead_lock, what);
}

void
in6_multihead_lock_done(void)
{
        lck_rw_done(&in6_multihead_lock);
}

static struct ip6_msource *
ip6ms_alloc(int how)
{
        struct ip6_msource *i6ms;

        i6ms = (how == M_WAITOK) ? zalloc(ip6ms_zone) :
            zalloc_noblock(ip6ms_zone);
        if (i6ms != NULL)
                bzero(i6ms, ip6ms_size);

        return (i6ms);
}

static void
ip6ms_free(struct ip6_msource *i6ms)
{
        zfree(ip6ms_zone, i6ms);
}

static struct in6_msource *
in6ms_alloc(int how)
{
        struct in6_msource *in6ms;

        in6ms = (how == M_WAITOK) ? zalloc(in6ms_zone) :
            zalloc_noblock(in6ms_zone);
        if (in6ms != NULL)
                bzero(in6ms, in6ms_size);

        return (in6ms);
}

static void
in6ms_free(struct in6_msource *in6ms)
{
        zfree(in6ms_zone, in6ms);
}

#ifdef MLD_DEBUG

static const char *in6m_modestrs[] = { "un\n", "in", "ex" };

static const char *
in6m_mode_str(const int mode)
{
        if (mode >= MCAST_UNDEFINED && mode <= MCAST_EXCLUDE)
                return (in6m_modestrs[mode]);
        return ("??");
}

static const char *in6m_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 *
in6m_state_str(const int state)
{
        if (state >= MLD_NOT_MEMBER && state <= MLD_LEAVING_MEMBER)
                return (in6m_statestrs[state]);
        return ("??");
}

/*
 * Dump an in6_multi structure to the console.
 */
void
in6m_print(const struct in6_multi *inm)
{
        int t;

        IN6M_LOCK_ASSERT_HELD(__DECONST(struct in6_multi *, inm));

        if (mld_debug == 0)
                return;

        printf("%s: --- begin in6m 0x%llx ---\n", __func__,
            (uint64_t)VM_KERNEL_ADDRPERM(inm));
        printf("addr %s ifp 0x%llx(%s) ifma 0x%llx\n",
            ip6_sprintf(&inm->in6m_addr),
            (uint64_t)VM_KERNEL_ADDRPERM(inm->in6m_ifp),
            if_name(inm->in6m_ifp),
            (uint64_t)VM_KERNEL_ADDRPERM(inm->in6m_ifma));
        printf("timer %u state %s refcount %u scq.len %u\n",
            inm->in6m_timer,
            in6m_state_str(inm->in6m_state),
            inm->in6m_refcount,
            inm->in6m_scq.ifq_len);
        printf("mli 0x%llx nsrc %lu sctimer %u scrv %u\n",
            (uint64_t)VM_KERNEL_ADDRPERM(inm->in6m_mli),
            inm->in6m_nsrc,
            inm->in6m_sctimer,
            inm->in6m_scrv);
        for (t = 0; t < 2; t++) {
                printf("t%d: fmode %s asm %u ex %u in %u rec %u\n", t,
                    in6m_mode_str(inm->in6m_st[t].iss_fmode),
                    inm->in6m_st[t].iss_asm,
                    inm->in6m_st[t].iss_ex,
                    inm->in6m_st[t].iss_in,
                    inm->in6m_st[t].iss_rec);
        }
        printf("%s: --- end in6m 0x%llx ---\n", __func__,
            (uint64_t)VM_KERNEL_ADDRPERM(inm));
}

#else 

void
in6m_print(__unused const struct in6_multi *inm)
{

}

#endif