Fix TCP IPv6 SYN cache kernel information disclosure.

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

/*-
 * Copyright (c) 2007-2009 Bruce Simpson.
 * Copyright (c) 2005 Robert N. M. Watson.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

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

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

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/rmlock.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/protosw.h>
#include <sys/sysctl.h>
#include <sys/ktr.h>
#include <sys/taskqueue.h>
#include <sys/tree.h>

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

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

#ifndef KTR_IGMPV3
#define KTR_IGMPV3 KTR_INET
#endif

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

static MALLOC_DEFINE(M_INMFILTER, "in_mfilter",
    "IPv4 multicast PCB-layer source filter");
static MALLOC_DEFINE(M_IPMADDR, "in_multi", "IPv4 multicast group");
static MALLOC_DEFINE(M_IPMOPTS, "ip_moptions", "IPv4 multicast options");
static MALLOC_DEFINE(M_IPMSOURCE, "ip_msource",
    "IPv4 multicast IGMP-layer source filter");

/*
 * Locking:
 * - Lock order is: Giant, INP_WLOCK, IN_MULTI_LOCK, IGMP_LOCK, IF_ADDR_LOCK.
 * - The IF_ADDR_LOCK is implicitly taken by inm_lookup() earlier, however
 *   it can be taken by code in net/if.c also.
 * - ip_moptions and in_mfilter are covered by the INP_WLOCK.
 *
 * struct in_multi is covered by IN_MULTI_LOCK. There isn't strictly
 * any need for in_multi itself to be virtualized -- it is bound to an ifp
 * anyway no matter what happens.
 */
struct mtx in_multi_mtx;
MTX_SYSINIT(in_multi_mtx, &in_multi_mtx, "in_multi_mtx", MTX_DEF);

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

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

static u_long in_mcast_maxgrpsrc = IP_MAX_GROUP_SRC_FILTER;
SYSCTL_ULONG(_net_inet_ip_mcast, OID_AUTO, maxgrpsrc,
    CTLFLAG_RWTUN, &in_mcast_maxgrpsrc, 0,
    "Max source filters per group");

static u_long in_mcast_maxsocksrc = IP_MAX_SOCK_SRC_FILTER;
SYSCTL_ULONG(_net_inet_ip_mcast, OID_AUTO, maxsocksrc,
    CTLFLAG_RWTUN, &in_mcast_maxsocksrc, 0,
    "Max source filters per socket");

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

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

static STAILQ_HEAD(, ip_moptions) imo_gc_list =
    STAILQ_HEAD_INITIALIZER(imo_gc_list);
static struct task imo_gc_task = TASK_INITIALIZER(0, inp_gcmoptions, NULL);

#ifdef KTR
/*
 * Inline function which wraps assertions for a valid ifp.
 * The ifnet layer will set the ifma's ifp pointer to NULL if the ifp
 * is detached.
 */
static int __inline
inm_is_ifp_detached(const struct in_multi *inm)
{
        struct ifnet *ifp;

        KASSERT(inm->inm_ifma != NULL, ("%s: no ifma", __func__));
        ifp = inm->inm_ifma->ifma_ifp;
        if (ifp != NULL) {
                /*
                 * Sanity check that netinet's notion of ifp is the
                 * same as net's.
                 */
                KASSERT(inm->inm_ifp == ifp, ("%s: bad ifp", __func__));
        }

        return (ifp == NULL);
}
#endif

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

/*
 * Function for looking up an in_multi record for an IPv4 multicast address
 * on a given interface. ifp must be valid. If no record found, return NULL.
 * The IN_MULTI_LOCK and IF_ADDR_LOCK on ifp must be held.
 */
struct in_multi *
inm_lookup_locked(struct ifnet *ifp, const struct in_addr ina)
{
        struct ifmultiaddr *ifma;
        struct in_multi *inm;

        IN_MULTI_LOCK_ASSERT();
        IF_ADDR_LOCK_ASSERT(ifp);

        inm = NULL;
        TAILQ_FOREACH(ifma, &((ifp)->if_multiaddrs), ifma_link) {
                if (ifma->ifma_addr->sa_family == AF_INET) {
                        inm = (struct in_multi *)ifma->ifma_protospec;
                        if (inm->inm_addr.s_addr == ina.s_addr)
                                break;
                        inm = NULL;
                }
        }
        return (inm);
}

/*
 * Wrapper for inm_lookup_locked().
 * The IF_ADDR_LOCK will be taken on ifp and released on return.
 */
struct in_multi *
inm_lookup(struct ifnet *ifp, const struct in_addr ina)
{
        struct in_multi *inm;

        IN_MULTI_LOCK_ASSERT();
        IF_ADDR_RLOCK(ifp);
        inm = inm_lookup_locked(ifp, ina);
        IF_ADDR_RUNLOCK(ifp);

        return (inm);
}

/*
 * Resize the ip_moptions vector to the next power-of-two minus 1.
 * May be called with locks held; do not sleep.
 */
static int
imo_grow(struct ip_moptions *imo)
{
        struct in_multi         **nmships;
        struct in_multi         **omships;
        struct in_mfilter        *nmfilters;
        struct in_mfilter        *omfilters;
        size_t                    idx;
        size_t                    newmax;
        size_t                    oldmax;

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

        if (newmax <= IP_MAX_MEMBERSHIPS) {
                nmships = (struct in_multi **)realloc(omships,
                    sizeof(struct in_multi *) * newmax, M_IPMOPTS, M_NOWAIT);
                nmfilters = (struct in_mfilter *)realloc(omfilters,
                    sizeof(struct in_mfilter) * newmax, M_INMFILTER, M_NOWAIT);
                if (nmships != NULL && nmfilters != NULL) {
                        /* Initialize newly allocated source filter heads. */
                        for (idx = oldmax; idx < newmax; idx++) {
                                imf_init(&nmfilters[idx], MCAST_UNDEFINED,
                                    MCAST_EXCLUDE);
                        }
                        imo->imo_max_memberships = newmax;
                        imo->imo_membership = nmships;
                        imo->imo_mfilters = nmfilters;
                }
        }

        if (nmships == NULL || nmfilters == NULL) {
                if (nmships != NULL)
                        free(nmships, M_IPMOPTS);
                if (nmfilters != NULL)
                        free(nmfilters, M_INMFILTER);
                return (ETOOMANYREFS);
        }

        return (0);
}

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

        gsin = (const struct sockaddr_in *)group;

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

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

        return (idx);
}

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

        KASSERT(src->sa_family == AF_INET, ("%s: !AF_INET", __func__));
        KASSERT(gidx != -1 && gidx < imo->imo_num_memberships,
            ("%s: invalid index %d\n", __func__, (int)gidx));

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

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

        return ((struct in_msource *)ims);
}

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

        KASSERT(ifp != NULL, ("%s: null ifp", __func__));

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

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

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

        return (MCAST_PASS);
}

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

        IN_MULTI_LOCK_ASSERT();

        ii = (struct in_ifinfo *)ifp->if_afdata[AF_INET];

        inm = inm_lookup(ifp, *group);
        if (inm != NULL) {
                /*
                 * If we already joined this group, just bump the
                 * refcount and return it.
                 */
                KASSERT(inm->inm_refcount >= 1,
                    ("%s: bad refcount %d", __func__, inm->inm_refcount));
                ++inm->inm_refcount;
                *pinm = inm;
                return (0);
        }

        memset(&gsin, 0, sizeof(gsin));
        gsin.sin_family = AF_INET;
        gsin.sin_len = sizeof(struct sockaddr_in);
        gsin.sin_addr = *group;

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

        /* XXX ifma_protospec must be covered by IF_ADDR_LOCK */
        IF_ADDR_WLOCK(ifp);

        /*
         * If something other than netinet is occupying the link-layer
         * group, print a meaningful error message and back out of
         * the allocation.
         * Otherwise, bump the refcount on the existing network-layer
         * group association and return it.
         */
        if (ifma->ifma_protospec != NULL) {
                inm = (struct in_multi *)ifma->ifma_protospec;
#ifdef INVARIANTS
                KASSERT(ifma->ifma_addr != NULL, ("%s: no ifma_addr",
                    __func__));
                KASSERT(ifma->ifma_addr->sa_family == AF_INET,
                    ("%s: ifma not AF_INET", __func__));
                KASSERT(inm != NULL, ("%s: no ifma_protospec", __func__));
                if (inm->inm_ifma != ifma || inm->inm_ifp != ifp ||
                    !in_hosteq(inm->inm_addr, *group)) {
                        char addrbuf[INET_ADDRSTRLEN];

                        panic("%s: ifma %p is inconsistent with %p (%s)",
                            __func__, ifma, inm, inet_ntoa_r(*group, addrbuf));
                }
#endif
                ++inm->inm_refcount;
                *pinm = inm;
                IF_ADDR_WUNLOCK(ifp);
                return (0);
        }

        IF_ADDR_WLOCK_ASSERT(ifp);

        /*
         * A new in_multi record is needed; allocate and initialize it.
         * We DO NOT perform an IGMP join as the in_ layer may need to
         * push an initial source list down to IGMP to support SSM.
         *
         * The initial source filter state is INCLUDE, {} as per the RFC.
         */
        inm = malloc(sizeof(*inm), M_IPMADDR, M_NOWAIT | M_ZERO);
        if (inm == NULL) {
                IF_ADDR_WUNLOCK(ifp);
                if_delmulti_ifma(ifma);
                return (ENOMEM);
        }
        inm->inm_addr = *group;
        inm->inm_ifp = ifp;
        inm->inm_igi = ii->ii_igmp;
        inm->inm_ifma = ifma;
        inm->inm_refcount = 1;
        inm->inm_state = IGMP_NOT_MEMBER;
        mbufq_init(&inm->inm_scq, IGMP_MAX_STATE_CHANGES);
        inm->inm_st[0].iss_fmode = MCAST_UNDEFINED;
        inm->inm_st[1].iss_fmode = MCAST_UNDEFINED;
        RB_INIT(&inm->inm_srcs);

        ifma->ifma_protospec = inm;

        *pinm = inm;

        IF_ADDR_WUNLOCK(ifp);
        return (0);
}

/*
 * Drop a reference to an in_multi record.
 *
 * If the refcount drops to 0, free the in_multi record and
 * delete the underlying link-layer membership.
 */
void
inm_release_locked(struct in_multi *inm)
{
        struct ifmultiaddr *ifma;

        IN_MULTI_LOCK_ASSERT();

        CTR2(KTR_IGMPV3, "%s: refcount is %d", __func__, inm->inm_refcount);

        if (--inm->inm_refcount > 0) {
                CTR2(KTR_IGMPV3, "%s: refcount is now %d", __func__,
                    inm->inm_refcount);
                return;
        }

        CTR2(KTR_IGMPV3, "%s: freeing inm %p", __func__, inm);

        ifma = inm->inm_ifma;

        /* XXX this access is not covered by IF_ADDR_LOCK */
        CTR2(KTR_IGMPV3, "%s: purging ifma %p", __func__, ifma);
        KASSERT(ifma->ifma_protospec == inm,
            ("%s: ifma_protospec != inm", __func__));
        ifma->ifma_protospec = NULL;

        inm_purge(inm);

        free(inm, M_IPMADDR);

        if_delmulti_ifma(ifma);
}

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

        IN_MULTI_LOCK_ASSERT();

        RB_FOREACH(ims, ip_msource_tree, &inm->inm_srcs) {
                if (ims->ims_stp) {
                        ims->ims_stp = 0;
                        --inm->inm_st[1].iss_rec;
                }
        }
        KASSERT(inm->inm_st[1].iss_rec == 0,
            ("%s: iss_rec %d not 0", __func__, inm->inm_st[1].iss_rec));
}

/*
 * Record a source as pending for a Source-Group IGMPv3 query.
 * This lives here as it modifies the shared tree.
 *
 * inm is the group descriptor.
 * naddr is the address of the source to record in network-byte order.
 *
 * If the net.inet.igmp.sgalloc sysctl is non-zero, we will
 * lazy-allocate a source node in response to an SG query.
 * Otherwise, no allocation is performed. This saves some memory
 * with the trade-off that the source will not be reported to the
 * router if joined in the window between the query response and
 * the group actually being joined on the local host.
 *
 * VIMAGE: XXX: Currently the igmp_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 occurred (negated errno code).
 */
int
inm_record_source(struct in_multi *inm, const in_addr_t naddr)
{
        struct ip_msource        find;
        struct ip_msource       *ims, *nims;

        IN_MULTI_LOCK_ASSERT();

        find.ims_haddr = ntohl(naddr);
        ims = RB_FIND(ip_msource_tree, &inm->inm_srcs, &find);
        if (ims && ims->ims_stp)
                return (0);
        if (ims == NULL) {
                if (inm->inm_nsrc == in_mcast_maxgrpsrc)
                        return (-ENOSPC);
                nims = malloc(sizeof(struct ip_msource), M_IPMSOURCE,
                    M_NOWAIT | M_ZERO);
                if (nims == NULL)
                        return (-ENOMEM);
                nims->ims_haddr = find.ims_haddr;
                RB_INSERT(ip_msource_tree, &inm->inm_srcs, nims);
                ++inm->inm_nsrc;
                ims = nims;
        }

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

        return (1);
}

/*
 * Return a pointer to an in_msource owned by an in_mfilter,
 * given its source address.
 * Lazy-allocate if needed. If this is a new entry its filter state is
 * undefined at t0.
 *
 * imf is the filter set being modified.
 * haddr is the source address in *host* byte-order.
 *
 * SMPng: May be called with locks held; malloc must not block.
 */
static int
imf_get_source(struct in_mfilter *imf, const struct sockaddr_in *psin,
    struct in_msource **plims)
{
        struct ip_msource        find;
        struct ip_msource       *ims, *nims;
        struct in_msource       *lims;
        int                      error;

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

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

        *plims = lims;

        return (error);
}

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

        nims = malloc(sizeof(struct in_msource), M_INMFILTER,
            M_NOWAIT | M_ZERO);
        if (nims == NULL)
                return (NULL);
        lims = (struct in_msource *)nims;
        lims->ims_haddr = ntohl(psin->sin_addr.s_addr);
        lims->imsl_st[0] = MCAST_UNDEFINED;
        lims->imsl_st[1] = st1;
        RB_INSERT(ip_msource_tree, &imf->imf_sources, nims);
        ++imf->imf_nsrc;

        return (lims);
}

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

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

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

        RB_FOREACH_SAFE(ims, ip_msource_tree, &imf->imf_sources, tims) {
                lims = (struct in_msource *)ims;
                if (lims->imsl_st[0] == lims->imsl_st[1]) {
                        /* no change at t1 */
                        continue;
                } else if (lims->imsl_st[0] != MCAST_UNDEFINED) {
                        /* revert change to existing source at t1 */
                        lims->imsl_st[1] = lims->imsl_st[0];
                } else {
                        /* revert source added t1 */
                        CTR2(KTR_IGMPV3, "%s: free ims %p", __func__, ims);
                        RB_REMOVE(ip_msource_tree, &imf->imf_sources, ims);
                        free(ims, M_INMFILTER);
                        imf->imf_nsrc--;
                }
        }
        imf->imf_st[1] = imf->imf_st[0];
}

/*
 * Mark socket-layer filter set as INCLUDE {} at t1.
 */
static void
imf_leave(struct in_mfilter *imf)
{
        struct ip_msource       *ims;
        struct in_msource       *lims;

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

/*
 * Mark socket-layer filter set deltas as committed.
 */
static void
imf_commit(struct in_mfilter *imf)
{
        struct ip_msource       *ims;
        struct in_msource       *lims;

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

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

        RB_FOREACH_SAFE(ims, ip_msource_tree, &imf->imf_sources, tims) {
                lims = (struct in_msource *)ims;
                if ((lims->imsl_st[0] == MCAST_UNDEFINED) &&
                    (lims->imsl_st[1] == MCAST_UNDEFINED)) {
                        CTR2(KTR_IGMPV3, "%s: free lims %p", __func__, ims);
                        RB_REMOVE(ip_msource_tree, &imf->imf_sources, ims);
                        free(ims, M_INMFILTER);
                        imf->imf_nsrc--;
                }
        }
}

/*
 * Purge socket-layer filter set.
 */
static void
imf_purge(struct in_mfilter *imf)
{
        struct ip_msource       *ims, *tims;

        RB_FOREACH_SAFE(ims, ip_msource_tree, &imf->imf_sources, tims) {
                CTR2(KTR_IGMPV3, "%s: free ims %p", __func__, ims);
                RB_REMOVE(ip_msource_tree, &imf->imf_sources, ims);
                free(ims, M_INMFILTER);
                imf->imf_nsrc--;
        }
        imf->imf_st[0] = imf->imf_st[1] = MCAST_UNDEFINED;
        KASSERT(RB_EMPTY(&imf->imf_sources),
            ("%s: imf_sources not empty", __func__));
}

/*
 * Look up a source filter entry for a multicast group.
 *
 * inm is the group descriptor to work with.
 * haddr is the host-byte-order IPv4 address to look up.
 * noalloc may be non-zero to suppress allocation of sources.
 * *pims will be set to the address of the retrieved or allocated source.
 *
 * SMPng: NOTE: may be called with locks held.
 * Return 0 if successful, otherwise return a non-zero error code.
 */
static int
inm_get_source(struct in_multi *inm, const in_addr_t haddr,
    const int noalloc, struct ip_msource **pims)
{
        struct ip_msource        find;
        struct ip_msource       *ims, *nims;

        find.ims_haddr = haddr;
        ims = RB_FIND(ip_msource_tree, &inm->inm_srcs, &find);
        if (ims == NULL && !noalloc) {
                if (inm->inm_nsrc == in_mcast_maxgrpsrc)
                        return (ENOSPC);
                nims = malloc(sizeof(struct ip_msource), M_IPMSOURCE,
                    M_NOWAIT | M_ZERO);
                if (nims == NULL)
                        return (ENOMEM);
                nims->ims_haddr = haddr;
                RB_INSERT(ip_msource_tree, &inm->inm_srcs, nims);
                ++inm->inm_nsrc;
                ims = nims;
#ifdef KTR
                CTR3(KTR_IGMPV3, "%s: allocated 0x%08x as %p", __func__,
                    haddr, ims);
#endif
        }

        *pims = ims;
        return (0);
}

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

        if (lims->imsl_st[0] == MCAST_EXCLUDE) {
                CTR3(KTR_IGMPV3, "%s: t1 ex -= %d on 0x%08x",
                    __func__, n, ims->ims_haddr);
                ims->ims_st[1].ex -= n;
        } else if (lims->imsl_st[0] == MCAST_INCLUDE) {
                CTR3(KTR_IGMPV3, "%s: t1 in -= %d on 0x%08x",
                    __func__, n, ims->ims_haddr);
                ims->ims_st[1].in -= n;
        }

        if (lims->imsl_st[1] == MCAST_EXCLUDE) {
                CTR3(KTR_IGMPV3, "%s: t1 ex += %d on 0x%08x",
                    __func__, n, ims->ims_haddr);
                ims->ims_st[1].ex += n;
        } else if (lims->imsl_st[1] == MCAST_INCLUDE) {
                CTR3(KTR_IGMPV3, "%s: t1 in += %d on 0x%08x",
                    __func__, n, ims->ims_haddr);
                ims->ims_st[1].in += n;
        }
}

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

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

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

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

        CTR3(KTR_IGMPV3, "%s: imf filters in-mode: %d at t0, %d at t1",
            __func__, nsrc0, nsrc1);

        /* Handle transition between INCLUDE {n} and INCLUDE {} on socket. */
        if (imf->imf_st[0] == imf->imf_st[1] &&
            imf->imf_st[1] == MCAST_INCLUDE) {
                if (nsrc1 == 0) {
                        CTR1(KTR_IGMPV3, "%s: --in on inm at t1", __func__);
                        --inm->inm_st[1].iss_in;
                }
        }

        /* Handle filter mode transition on socket. */
        if (imf->imf_st[0] != imf->imf_st[1]) {
                CTR3(KTR_IGMPV3, "%s: imf transition %d to %d",
                    __func__, imf->imf_st[0], imf->imf_st[1]);

                if (imf->imf_st[0] == MCAST_EXCLUDE) {
                        CTR1(KTR_IGMPV3, "%s: --ex on inm at t1", __func__);
                        --inm->inm_st[1].iss_ex;
                } else if (imf->imf_st[0] == MCAST_INCLUDE) {
                        CTR1(KTR_IGMPV3, "%s: --in on inm at t1", __func__);
                        --inm->inm_st[1].iss_in;
                }

                if (imf->imf_st[1] == MCAST_EXCLUDE) {
                        CTR1(KTR_IGMPV3, "%s: ex++ on inm at t1", __func__);
                        inm->inm_st[1].iss_ex++;
                } else if (imf->imf_st[1] == MCAST_INCLUDE && nsrc1 > 0) {
                        CTR1(KTR_IGMPV3, "%s: in++ on inm at t1", __func__);
                        inm->inm_st[1].iss_in++;
                }
        }

        /*
         * Track inm filter state in terms of listener counts.
         * If there are any exclusive listeners, stack-wide
         * membership is exclusive.
         * Otherwise, if only inclusive listeners, stack-wide is inclusive.
         * If no listeners remain, state is undefined at t1,
         * and the IGMP lifecycle for this group should finish.
         */
        if (inm->inm_st[1].iss_ex > 0) {
                CTR1(KTR_IGMPV3, "%s: transition to EX", __func__);
                inm->inm_st[1].iss_fmode = MCAST_EXCLUDE;
        } else if (inm->inm_st[1].iss_in > 0) {
                CTR1(KTR_IGMPV3, "%s: transition to IN", __func__);
                inm->inm_st[1].iss_fmode = MCAST_INCLUDE;
        } else {
                CTR1(KTR_IGMPV3, "%s: transition to UNDEF", __func__);
                inm->inm_st[1].iss_fmode = MCAST_UNDEFINED;
        }

        /* Decrement ASM listener count on transition out of ASM mode. */
        if (imf->imf_st[0] == MCAST_EXCLUDE && nsrc0 == 0) {
                if ((imf->imf_st[1] != MCAST_EXCLUDE) ||
                    (imf->imf_st[1] == MCAST_EXCLUDE && nsrc1 > 0)) {
                        CTR1(KTR_IGMPV3, "%s: --asm on inm at t1", __func__);
                        --inm->inm_st[1].iss_asm;
                }
        }

        /* Increment ASM listener count on transition to ASM mode. */
        if (imf->imf_st[1] == MCAST_EXCLUDE && nsrc1 == 0) {
                CTR1(KTR_IGMPV3, "%s: asm++ on inm at t1", __func__);
                inm->inm_st[1].iss_asm++;
        }

        CTR3(KTR_IGMPV3, "%s: merged imf %p to inm %p", __func__, imf, inm);
        inm_print(inm);

out_reap:
        if (schanged > 0) {
                CTR1(KTR_IGMPV3, "%s: sources changed; reaping", __func__);
                inm_reap(inm);
        }
        return (error);
}

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

        CTR2(KTR_IGMPV3, "%s: commit inm %p", __func__, inm);
        CTR1(KTR_IGMPV3, "%s: pre commit:", __func__);
        inm_print(inm);

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

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

        RB_FOREACH_SAFE(ims, ip_msource_tree, &inm->inm_srcs, tims) {
                if (ims->ims_st[0].ex > 0 || ims->ims_st[0].in > 0 ||
                    ims->ims_st[1].ex > 0 || ims->ims_st[1].in > 0 ||
                    ims->ims_stp != 0)
                        continue;
                CTR2(KTR_IGMPV3, "%s: free ims %p", __func__, ims);
                RB_REMOVE(ip_msource_tree, &inm->inm_srcs, ims);
                free(ims, M_IPMSOURCE);
                inm->inm_nsrc--;
        }
}

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

        RB_FOREACH_SAFE(ims, ip_msource_tree, &inm->inm_srcs, tims) {
                CTR2(KTR_IGMPV3, "%s: free ims %p", __func__, ims);
                RB_REMOVE(ip_msource_tree, &inm->inm_srcs, ims);
                free(ims, M_IPMSOURCE);
                inm->inm_nsrc--;
        }
}

/*
 * Join a multicast group; unlocked entry point.
 *
 * SMPng: XXX: in_joingroup() is called from in_control() when Giant
 * is not held. Fortunately, ifp is unlikely to have been detached
 * at this point, so we assume it's OK to recurse.
 */
int
in_joingroup(struct ifnet *ifp, const struct in_addr *gina,
    /*const*/ struct in_mfilter *imf, struct in_multi **pinm)
{
        int error;

        IN_MULTI_LOCK();
        error = in_joingroup_locked(ifp, gina, imf, pinm);
        IN_MULTI_UNLOCK();

        return (error);
}

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

        IN_MULTI_LOCK_ASSERT();

        CTR4(KTR_IGMPV3, "%s: join 0x%08x on %p(%s))", __func__,
            ntohl(gina->s_addr), ifp, ifp->if_xname);

        error = 0;
        inm = NULL;

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

        error = in_getmulti(ifp, gina, &inm);
        if (error) {
                CTR1(KTR_IGMPV3, "%s: in_getmulti() failure", __func__);
                return (error);
        }

        CTR1(KTR_IGMPV3, "%s: merge inm state", __func__);
        error = inm_merge(inm, imf);
        if (error) {
                CTR1(KTR_IGMPV3, "%s: failed to merge inm state", __func__);
                goto out_inm_release;
        }

        CTR1(KTR_IGMPV3, "%s: doing igmp downcall", __func__);
        error = igmp_change_state(inm);
        if (error) {
                CTR1(KTR_IGMPV3, "%s: failed to update source", __func__);
                goto out_inm_release;
        }

out_inm_release:
        if (error) {
                CTR2(KTR_IGMPV3, "%s: dropping ref on %p", __func__, inm);
                inm_release_locked(inm);
        } else {
                *pinm = inm;
        }

        return (error);
}

/*
 * Leave a multicast group; unlocked entry point.
 */
int
in_leavegroup(struct in_multi *inm, /*const*/ struct in_mfilter *imf)
{
        int error;

        IN_MULTI_LOCK();
        error = in_leavegroup_locked(inm, imf);
        IN_MULTI_UNLOCK();

        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 inm_release(*) as this function also
 * makes a state change downcall into IGMP.
 */
int
in_leavegroup_locked(struct in_multi *inm, /*const*/ struct in_mfilter *imf)
{
        struct in_mfilter        timf;
        int                      error;

        error = 0;

        IN_MULTI_LOCK_ASSERT();

        CTR5(KTR_IGMPV3, "%s: leave inm %p, 0x%08x/%s, imf %p", __func__,
            inm, ntohl(inm->inm_addr.s_addr),
            (inm_is_ifp_detached(inm) ? "null" : inm->inm_ifp->if_xname),
            imf);

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

        /*
         * Begin state merge transaction at IGMP layer.
         *
         * As this particular invocation should not cause any memory
         * to be allocated, and there is no opportunity to roll back
         * the transaction, it MUST NOT fail.
         */
        CTR1(KTR_IGMPV3, "%s: merge inm state", __func__);
        error = inm_merge(inm, imf);
        KASSERT(error == 0, ("%s: failed to merge inm state", __func__));

        CTR1(KTR_IGMPV3, "%s: doing igmp downcall", __func__);
        CURVNET_SET(inm->inm_ifp->if_vnet);
        error = igmp_change_state(inm);
        CURVNET_RESTORE();
        if (error)
                CTR1(KTR_IGMPV3, "%s: failed igmp downcall", __func__);

        CTR2(KTR_IGMPV3, "%s: dropping ref on %p", __func__, inm);
        inm_release_locked(inm);

        return (error);
}

/*#ifndef BURN_BRIDGES*/
/*
 * Join an IPv4 multicast group in (*,G) exclusive mode.
 * The group must be a 224.0.0.0/24 link-scope group.
 * This KPI is for legacy kernel consumers only.
 */
struct in_multi *
in_addmulti(struct in_addr *ap, struct ifnet *ifp)
{
        struct in_multi *pinm;
        int error;
#ifdef INVARIANTS
        char addrbuf[INET_ADDRSTRLEN];
#endif

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

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

        return (pinm);
}

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

        (void)in_leavegroup(inm, NULL);
}
/*#endif*/

/*
 * Block or unblock an ASM multicast source on an inpcb.
 * This implements the delta-based API described in RFC 3678.
 *
 * The delta-based API applies only to exclusive-mode memberships.
 * An IGMP downcall will be performed.
 *
 * SMPng: NOTE: Must take Giant as a join may create a new ifma.
 *
 * Return 0 if successful, otherwise return an appropriate error code.
 */
static int
inp_block_unblock_source(struct inpcb *inp, struct sockopt *sopt)
{
        struct group_source_req          gsr;
        struct rm_priotracker            in_ifa_tracker;
        sockunion_t                     *gsa, *ssa;
        struct ifnet                    *ifp;
        struct in_mfilter               *imf;
        struct ip_moptions              *imo;
        struct in_msource               *ims;
        struct in_multi                 *inm;
        size_t                           idx;
        uint16_t                         fmode;
        int                              error, doblock;

        ifp = NULL;
        error = 0;
        doblock = 0;

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

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

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

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

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

                if (!in_nullhost(mreqs.imr_interface)) {
                        IN_IFADDR_RLOCK(&in_ifa_tracker);
                        INADDR_TO_IFP(mreqs.imr_interface, ifp);
                        IN_IFADDR_RUNLOCK(&in_ifa_tracker);
                }
                if (sopt->sopt_name == IP_BLOCK_SOURCE)
                        doblock = 1;

                CTR3(KTR_IGMPV3, "%s: imr_interface = 0x%08x, ifp = %p",
                    __func__, ntohl(mreqs.imr_interface.s_addr), ifp);
                break;
            }

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

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

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

                if (gsr.gsr_interface == 0 || V_if_index < gsr.gsr_interface)
                        return (EADDRNOTAVAIL);

                ifp = ifnet_byindex(gsr.gsr_interface);

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

        default:
                CTR2(KTR_IGMPV3, "%s: unknown sopt_name %d",
                    __func__, sopt->sopt_name);
                return (EOPNOTSUPP);
                break;
        }

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

        /*
         * Check if we are actually a member of this group.
         */
        imo = inp_findmoptions(inp);
        idx = imo_match_group(imo, ifp, &gsa->sa);
        if (idx == -1 || imo->imo_mfilters == NULL) {
                error = EADDRNOTAVAIL;
                goto out_inp_locked;
        }

        KASSERT(imo->imo_mfilters != NULL,
            ("%s: imo_mfilters not allocated", __func__));
        imf = &imo->imo_mfilters[idx];
        inm = imo->imo_membership[idx];

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

        /*
         * Deal with error cases up-front:
         *  Asked to block, but already blocked; or
         *  Asked to unblock, but nothing to unblock.
         * If adding a new block entry, allocate it.
         */
        ims = imo_match_source(imo, idx, &ssa->sa);
        if ((ims != NULL && doblock) || (ims == NULL && !doblock)) {
                CTR3(KTR_IGMPV3, "%s: source 0x%08x %spresent", __func__,
                    ntohl(ssa->sin.sin_addr.s_addr), doblock ? "" : "not ");
                error = EADDRNOTAVAIL;
                goto out_inp_locked;
        }

        INP_WLOCK_ASSERT(inp);

        /*
         * Begin state merge transaction at socket layer.
         */
        if (doblock) {
                CTR2(KTR_IGMPV3, "%s: %s source", __func__, "block");
                ims = imf_graft(imf, fmode, &ssa->sin);
                if (ims == NULL)
                        error = ENOMEM;
        } else {
                CTR2(KTR_IGMPV3, "%s: %s source", __func__, "allow");
                error = imf_prune(imf, &ssa->sin);
        }

        if (error) {
                CTR1(KTR_IGMPV3, "%s: merge imf state failed", __func__);
                goto out_imf_rollback;
        }

        /*
         * Begin state merge transaction at IGMP layer.
         */
        IN_MULTI_LOCK();

        CTR1(KTR_IGMPV3, "%s: merge inm state", __func__);
        error = inm_merge(inm, imf);
        if (error) {
                CTR1(KTR_IGMPV3, "%s: failed to merge inm state", __func__);
                goto out_in_multi_locked;
        }

        CTR1(KTR_IGMPV3, "%s: doing igmp downcall", __func__);
        error = igmp_change_state(inm);
        if (error)
                CTR1(KTR_IGMPV3, "%s: failed igmp downcall", __func__);

out_in_multi_locked:

        IN_MULTI_UNLOCK();

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

        imf_reap(imf);

out_inp_locked:
        INP_WUNLOCK(inp);
        return (error);
}

/*
 * Given an inpcb, return its multicast options structure pointer.  Accepts
 * an unlocked inpcb pointer, but will return it locked.  May sleep.
 *
 * SMPng: NOTE: Potentially calls malloc(M_WAITOK) with Giant held.
 * SMPng: NOTE: Returns with the INP write lock held.
 */
static struct ip_moptions *
inp_findmoptions(struct inpcb *inp)
{
        struct ip_moptions       *imo;
        struct in_multi         **immp;
        struct in_mfilter        *imfp;
        size_t                    idx;

        INP_WLOCK(inp);
        if (inp->inp_moptions != NULL)
                return (inp->inp_moptions);

        INP_WUNLOCK(inp);

        imo = malloc(sizeof(*imo), M_IPMOPTS, M_WAITOK);
        immp = malloc(sizeof(*immp) * IP_MIN_MEMBERSHIPS, M_IPMOPTS,
            M_WAITOK | M_ZERO);
        imfp = malloc(sizeof(struct in_mfilter) * IP_MIN_MEMBERSHIPS,
            M_INMFILTER, M_WAITOK);

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

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

        INP_WLOCK(inp);
        if (inp->inp_moptions != NULL) {
                free(imfp, M_INMFILTER);
                free(immp, M_IPMOPTS);
                free(imo, M_IPMOPTS);
                return (inp->inp_moptions);
        }
        inp->inp_moptions = imo;
        return (imo);
}

/*
 * Discard the IP multicast options (and source filters).  To minimize
 * the amount of work done while holding locks such as the INP's
 * pcbinfo lock (which is used in the receive path), the free
 * operation is performed asynchronously in a separate task.
 *
 * SMPng: NOTE: assumes INP write lock is held.
 */
void
inp_freemoptions(struct ip_moptions *imo)
{

        KASSERT(imo != NULL, ("%s: ip_moptions is NULL", __func__));
        IN_MULTI_LOCK();
        STAILQ_INSERT_TAIL(&imo_gc_list, imo, imo_link);
        IN_MULTI_UNLOCK();
        taskqueue_enqueue(taskqueue_thread, &imo_gc_task);
}

static void
inp_freemoptions_internal(struct ip_moptions *imo)
{
        struct in_mfilter       *imf;
        size_t                   idx, nmships;

        nmships = imo->imo_num_memberships;
        for (idx = 0; idx < nmships; ++idx) {
                imf = imo->imo_mfilters ? &imo->imo_mfilters[idx] : NULL;
                if (imf)
                        imf_leave(imf);
                (void)in_leavegroup(imo->imo_membership[idx], imf);
                if (imf)
                        imf_purge(imf);
        }

        if (imo->imo_mfilters)
                free(imo->imo_mfilters, M_INMFILTER);
        free(imo->imo_membership, M_IPMOPTS);
        free(imo, M_IPMOPTS);
}

static void
inp_gcmoptions(void *context, int pending)
{
        struct ip_moptions *imo;

        IN_MULTI_LOCK();
        while (!STAILQ_EMPTY(&imo_gc_list)) {
                imo = STAILQ_FIRST(&imo_gc_list);
                STAILQ_REMOVE_HEAD(&imo_gc_list, imo_link);
                IN_MULTI_UNLOCK();
                inp_freemoptions_internal(imo);
                IN_MULTI_LOCK();
        }
        IN_MULTI_UNLOCK();
}

/*
 * Atomically get source filters on a socket for an IPv4 multicast group.
 * Called with INP lock held; returns with lock released.
 */
static int
inp_get_source_filters(struct inpcb *inp, struct sockopt *sopt)
{
        struct __msfilterreq     msfr;
        sockunion_t             *gsa;
        struct ifnet            *ifp;
        struct ip_moptions      *imo;
        struct in_mfilter       *imf;
        struct ip_msource       *ims;
        struct in_msource       *lims;
        struct sockaddr_in      *psin;
        struct sockaddr_storage *ptss;
        struct sockaddr_storage *tss;
        int                      error;
        size_t                   idx, nsrcs, ncsrcs;

        INP_WLOCK_ASSERT(inp);

        imo = inp->inp_moptions;
        KASSERT(imo != NULL, ("%s: null ip_moptions", __func__));

        INP_WUNLOCK(inp);

        error = sooptcopyin(sopt, &msfr, sizeof(struct __msfilterreq),
            sizeof(struct __msfilterreq));
        if (error)
                return (error);

        if (msfr.msfr_ifindex == 0 || V_if_index < msfr.msfr_ifindex)
                return (EINVAL);

        ifp = ifnet_byindex(msfr.msfr_ifindex);
        if (ifp == NULL)
                return (EINVAL);

        INP_WLOCK(inp);

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

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

        /*
         * If the user specified a buffer, copy out the source filter
         * entries to userland gracefully.
         * We only copy out the number of entries which userland
         * has asked for, but we always tell userland how big the
         * buffer really needs to be.
         */
        if (msfr.msfr_nsrcs > in_mcast_maxsocksrc)
                msfr.msfr_nsrcs = in_mcast_maxsocksrc;
        tss = NULL;
        if (msfr.msfr_srcs != NULL && msfr.msfr_nsrcs > 0) {
                tss = malloc(sizeof(struct sockaddr_storage) * msfr.msfr_nsrcs,
                    M_TEMP, M_NOWAIT | M_ZERO);
                if (tss == NULL) {
                        INP_WUNLOCK(inp);
                        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, ip_msource_tree, &imf->imf_sources) {
                lims = (struct in_msource *)ims;
                if (lims->imsl_st[0] == MCAST_UNDEFINED ||
                    lims->imsl_st[0] != imf->imf_st[0])
                        continue;
                ++ncsrcs;
                if (tss != NULL && nsrcs > 0) {
                        psin = (struct sockaddr_in *)ptss;
                        psin->sin_family = AF_INET;
                        psin->sin_len = sizeof(struct sockaddr_in);
                        psin->sin_addr.s_addr = htonl(lims->ims_haddr);
                        psin->sin_port = 0;
                        ++ptss;
                        --nsrcs;
                }
        }

        INP_WUNLOCK(inp);

        if (tss != NULL) {
                error = copyout(tss, msfr.msfr_srcs,
                    sizeof(struct sockaddr_storage) * msfr.msfr_nsrcs);
                free(tss, M_TEMP);
                if (error)
                        return (error);
        }

        msfr.msfr_nsrcs = ncsrcs;
        error = sooptcopyout(sopt, &msfr, sizeof(struct __msfilterreq));

        return (error);
}

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

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

        error = 0;
        switch (sopt->sopt_name) {
        case IP_MULTICAST_VIF:
                if (imo != NULL)
                        optval = imo->imo_multicast_vif;
                else
                        optval = -1;
                INP_WUNLOCK(inp);
                error = sooptcopyout(sopt, &optval, sizeof(int));
                break;

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

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

        case IP_MULTICAST_LOOP:
                if (imo == NULL)
                        optval = coptval = IP_DEFAULT_MULTICAST_LOOP;
                else
                        optval = coptval = imo->imo_multicast_loop;
                INP_WUNLOCK(inp);
                if (sopt->sopt_valsize == sizeof(u_char))
                        error = sooptcopyout(sopt, &coptval, sizeof(u_char));
                else
                        error = sooptcopyout(sopt, &optval, sizeof(int));
                break;

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

        default:
                INP_WUNLOCK(inp);
                error = ENOPROTOOPT;
                break;
        }

        INP_UNLOCK_ASSERT(inp);

        return (error);
}

/*
 * Look up the ifnet to use for a multicast group membership,
 * given the IPv4 address of an interface, and the IPv4 group address.
 *
 * This routine exists to support legacy multicast applications
 * which do not understand that multicast memberships are scoped to
 * specific physical links in the networking stack, or which need
 * to join link-scope groups before IPv4 addresses are configured.
 *
 * If inp is non-NULL, use this socket's current FIB number for any
 * required FIB lookup.
 * If ina is INADDR_ANY, look up the group address in the unicast FIB,
 * and use its ifp; usually, this points to the default next-hop.
 *
 * If the FIB lookup fails, attempt to use the first non-loopback
 * interface with multicast capability in the system as a
 * last resort. The legacy IPv4 ASM API requires that we do
 * this in order to allow groups to be joined when the routing
 * table has not yet been populated during boot.
 *
 * Returns NULL if no ifp could be found.
 *
 * FUTURE: Implement IPv4 source-address selection.
 */
static struct ifnet *
inp_lookup_mcast_ifp(const struct inpcb *inp,
    const struct sockaddr_in *gsin, const struct in_addr ina)
{
        struct rm_priotracker in_ifa_tracker;
        struct ifnet *ifp;
        struct nhop4_basic nh4;
        uint32_t fibnum;

        KASSERT(gsin->sin_family == AF_INET, ("%s: not AF_INET", __func__));
        KASSERT(IN_MULTICAST(ntohl(gsin->sin_addr.s_addr)),
            ("%s: not multicast", __func__));

        ifp = NULL;
        if (!in_nullhost(ina)) {
                IN_IFADDR_RLOCK(&in_ifa_tracker);
                INADDR_TO_IFP(ina, ifp);
                IN_IFADDR_RUNLOCK(&in_ifa_tracker);
        } else {
                fibnum = inp ? inp->inp_inc.inc_fibnum : 0;
                if (fib4_lookup_nh_basic(fibnum, gsin->sin_addr, 0, 0, &nh4)==0)
                        ifp = nh4.nh_ifp;
                else {
                        struct in_ifaddr *ia;
                        struct ifnet *mifp;

                        mifp = NULL;
                        IN_IFADDR_RLOCK(&in_ifa_tracker);
                        TAILQ_FOREACH(ia, &V_in_ifaddrhead, ia_link) {
                                mifp = ia->ia_ifp;
                                if (!(mifp->if_flags & IFF_LOOPBACK) &&
                                     (mifp->if_flags & IFF_MULTICAST)) {
                                        ifp = mifp;
                                        break;
                                }
                        }
                        IN_IFADDR_RUNLOCK(&in_ifa_tracker);
                }
        }

        return (ifp);
}

/*
 * Join an IPv4 multicast group, possibly with a source.
 */
static int
inp_join_group(struct inpcb *inp, struct sockopt *sopt)
{
        struct group_source_req          gsr;
        sockunion_t                     *gsa, *ssa;
        struct ifnet                    *ifp;
        struct in_mfilter               *imf;
        struct ip_moptions              *imo;
        struct in_multi                 *inm;
        struct in_msource               *lims;
        size_t                           idx;
        int                              error, is_new;

        ifp = NULL;
        imf = NULL;
        lims = NULL;
        error = 0;
        is_new = 0;

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

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

                if (sopt->sopt_name == IP_ADD_MEMBERSHIP) {
                        error = sooptcopyin(sopt, &mreqs,
                            sizeof(struct ip_mreq),
                            sizeof(struct ip_mreq));
                        /*
                         * Do argument switcharoo from ip_mreq into
                         * ip_mreq_source to avoid using two instances.
                         */
                        mreqs.imr_interface = mreqs.imr_sourceaddr;
                        mreqs.imr_sourceaddr.s_addr = INADDR_ANY;
                } else if (sopt->sopt_name == IP_ADD_SOURCE_MEMBERSHIP) {
                        error = sooptcopyin(sopt, &mreqs,
                            sizeof(struct ip_mreq_source),
                            sizeof(struct ip_mreq_source));
                }
                if (error)
                        return (error);

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

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

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

                ifp = inp_lookup_mcast_ifp(inp, &gsa->sin,
                    mreqs.imr_interface);
                CTR3(KTR_IGMPV3, "%s: imr_interface = 0x%08x, ifp = %p",
                    __func__, ntohl(mreqs.imr_interface.s_addr), ifp);
                break;
        }

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

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

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

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

                if (gsr.gsr_interface == 0 || V_if_index < gsr.gsr_interface)
                        return (EADDRNOTAVAIL);
                ifp = ifnet_byindex(gsr.gsr_interface);
                break;

        default:
                CTR2(KTR_IGMPV3, "%s: unknown sopt_name %d",
                    __func__, sopt->sopt_name);
                return (EOPNOTSUPP);
                break;
        }

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

        imo = inp_findmoptions(inp);
        idx = imo_match_group(imo, ifp, &gsa->sa);
        if (idx == -1) {
                is_new = 1;
        } else {
                inm = imo->imo_membership[idx];
                imf = &imo->imo_mfilters[idx];
                if (ssa->ss.ss_family != AF_UNSPEC) {
                        /*
                         * MCAST_JOIN_SOURCE_GROUP on an exclusive membership
                         * is an error. On an existing inclusive membership,
                         * it just adds the source to the filter list.
                         */
                        if (imf->imf_st[1] != MCAST_INCLUDE) {
                                error = EINVAL;
                                goto out_inp_locked;
                        }
                        /*
                         * Throw out duplicates.
                         *
                         * XXX FIXME: This makes a naive assumption that
                         * even if entries exist for *ssa in this imf,
                         * they will be rejected as dupes, even if they
                         * are not valid in the current mode (in-mode).
                         *
                         * in_msource is transactioned just as for anything
                         * else in SSM -- but note naive use of inm_graft()
                         * below for allocating new filter entries.
                         *
                         * This is only an issue if someone mixes the
                         * full-state SSM API with the delta-based API,
                         * which is discouraged in the relevant RFCs.
                         */
                        lims = imo_match_source(imo, idx, &ssa->sa);
                        if (lims != NULL /*&&
                            lims->imsl_st[1] == MCAST_INCLUDE*/) {
                                error = EADDRNOTAVAIL;
                                goto out_inp_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;
                        if (imf->imf_st[1] == MCAST_EXCLUDE)
                                error = EADDRINUSE;
                        goto out_inp_locked;
                }
        }

        /*
         * Begin state merge transaction at socket layer.
         */
        INP_WLOCK_ASSERT(inp);

        if (is_new) {
                if (imo->imo_num_memberships == imo->imo_max_memberships) {
                        error = imo_grow(imo);
                        if (error)
                                goto out_inp_locked;
                }
                /*
                 * Allocate the new slot upfront so we can deal with
                 * grafting the new source filter in same code path
                 * as for join-source on existing membership.
                 */
                idx = imo->imo_num_memberships;
                imo->imo_membership[idx] = NULL;
                imo->imo_num_memberships++;
                KASSERT(imo->imo_mfilters != NULL,
                    ("%s: imf_mfilters vector was not allocated", __func__));
                imf = &imo->imo_mfilters[idx];
                KASSERT(RB_EMPTY(&imf->imf_sources),
                    ("%s: imf_sources not empty", __func__));
        }

        /*
         * Graft new source into filter list for this inpcb's
         * membership of the group. The in_multi may not have
         * been allocated yet if this is a new membership, however,
         * the in_mfilter slot will be allocated and must be initialized.
         *
         * 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->ss.ss_family != AF_UNSPEC) {
                /* Membership starts in IN mode */
                if (is_new) {
                        CTR1(KTR_IGMPV3, "%s: new join w/source", __func__);
                        imf_init(imf, MCAST_UNDEFINED, MCAST_INCLUDE);
                } else {
                        CTR2(KTR_IGMPV3, "%s: %s source", __func__, "allow");
                }
                lims = imf_graft(imf, MCAST_INCLUDE, &ssa->sin);
                if (lims == NULL) {
                        CTR1(KTR_IGMPV3, "%s: merge imf state failed",
                            __func__);
                        error = ENOMEM;
                        goto out_imo_free;
                }
        } else {
                /* No address specified; Membership starts in EX mode */
                if (is_new) {
                        CTR1(KTR_IGMPV3, "%s: new join w/o source", __func__);
                        imf_init(imf, MCAST_UNDEFINED, MCAST_EXCLUDE);
                }
        }

        /*
         * Begin state merge transaction at IGMP layer.
         */
        IN_MULTI_LOCK();

        if (is_new) {
                error = in_joingroup_locked(ifp, &gsa->sin.sin_addr, imf,
                    &inm);
                if (error) {
                        CTR1(KTR_IGMPV3, "%s: in_joingroup_locked failed", 
                            __func__);
                        IN_MULTI_UNLOCK();
                        goto out_imo_free;
                }
                imo->imo_membership[idx] = inm;
        } else {
                CTR1(KTR_IGMPV3, "%s: merge inm state", __func__);
                error = inm_merge(inm, imf);
                if (error) {
                        CTR1(KTR_IGMPV3, "%s: failed to merge inm state",
                            __func__);
                        goto out_in_multi_locked;
                }
                CTR1(KTR_IGMPV3, "%s: doing igmp downcall", __func__);
                error = igmp_change_state(inm);
                if (error) {
                        CTR1(KTR_IGMPV3, "%s: failed igmp downcall",
                            __func__);
                        goto out_in_multi_locked;
                }
        }

out_in_multi_locked:

        IN_MULTI_UNLOCK();

        INP_WLOCK_ASSERT(inp);
        if (error) {
                imf_rollback(imf);
                if (is_new)
                        imf_purge(imf);
                else
                        imf_reap(imf);
        } else {
                imf_commit(imf);
        }

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

out_inp_locked:
        INP_WUNLOCK(inp);
        return (error);
}

/*
 * Leave an IPv4 multicast group on an inpcb, possibly with a source.
 */
static int
inp_leave_group(struct inpcb *inp, struct sockopt *sopt)
{
        struct group_source_req          gsr;
        struct ip_mreq_source            mreqs;
        struct rm_priotracker            in_ifa_tracker;
        sockunion_t                     *gsa, *ssa;
        struct ifnet                    *ifp;
        struct in_mfilter               *imf;
        struct ip_moptions              *imo;
        struct in_msource               *ims;
        struct in_multi                 *inm;
        size_t                           idx;
        int                              error, is_final;

        ifp = NULL;
        error = 0;
        is_final = 1;

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

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

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

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

                /*
                 * Attempt to look up hinted ifp from interface address.
                 * Fallthrough with null ifp iff lookup fails, to
                 * preserve 4.4BSD mcast API idempotence.
                 * XXX NOTE WELL: The RFC 3678 API is preferred because
                 * using an IPv4 address as a key is racy.
                 */
                if (!in_nullhost(mreqs.imr_interface)) {
                        IN_IFADDR_RLOCK(&in_ifa_tracker);
                        INADDR_TO_IFP(mreqs.imr_interface, ifp);
                        IN_IFADDR_RUNLOCK(&in_ifa_tracker);
                }
                CTR3(KTR_IGMPV3, "%s: imr_interface = 0x%08x, ifp = %p",
                    __func__, ntohl(mreqs.imr_interface.s_addr), ifp);

                break;

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

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

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

                if (gsr.gsr_interface == 0 || V_if_index < gsr.gsr_interface)
                        return (EADDRNOTAVAIL);

                ifp = ifnet_byindex(gsr.gsr_interface);

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

        default:
                CTR2(KTR_IGMPV3, "%s: unknown sopt_name %d",
                    __func__, sopt->sopt_name);
                return (EOPNOTSUPP);
                break;
        }

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

        /*
         * Find the membership in the membership array.
         */
        imo = inp_findmoptions(inp);
        idx = imo_match_group(imo, ifp, &gsa->sa);
        if (idx == -1) {
                error = EADDRNOTAVAIL;
                goto out_inp_locked;
        }
        inm = imo->imo_membership[idx];
        imf = &imo->imo_mfilters[idx];

        if (ssa->ss.ss_family != AF_UNSPEC)
                is_final = 0;

        /*
         * Begin state merge transaction at socket layer.
         */
        INP_WLOCK_ASSERT(inp);

        /*
         * If we were instructed only to leave a given source, do so.
         * MCAST_LEAVE_SOURCE_GROUP is only valid for inclusive memberships.
         */
        if (is_final) {
                imf_leave(imf);
        } else {
                if (imf->imf_st[0] == MCAST_EXCLUDE) {
                        error = EADDRNOTAVAIL;
                        goto out_inp_locked;
                }
                ims = imo_match_source(imo, idx, &ssa->sa);
                if (ims == NULL) {
                        CTR3(KTR_IGMPV3, "%s: source 0x%08x %spresent",
                            __func__, ntohl(ssa->sin.sin_addr.s_addr), "not ");
                        error = EADDRNOTAVAIL;
                        goto out_inp_locked;
                }
                CTR2(KTR_IGMPV3, "%s: %s source", __func__, "block");
                error = imf_prune(imf, &ssa->sin);
                if (error) {
                        CTR1(KTR_IGMPV3, "%s: merge imf state failed",
                            __func__);
                        goto out_inp_locked;
                }
        }

        /*
         * Begin state merge transaction at IGMP layer.
         */
        IN_MULTI_LOCK();

        if (is_final) {
                /*
                 * Give up the multicast address record to which
                 * the membership points.
                 */
                (void)in_leavegroup_locked(inm, imf);
        } else {
                CTR1(KTR_IGMPV3, "%s: merge inm state", __func__);
                error = inm_merge(inm, imf);
                if (error) {
                        CTR1(KTR_IGMPV3, "%s: failed to merge inm state",
                            __func__);
                        goto out_in_multi_locked;
                }

                CTR1(KTR_IGMPV3, "%s: doing igmp downcall", __func__);
                error = igmp_change_state(inm);
                if (error) {
                        CTR1(KTR_IGMPV3, "%s: failed igmp downcall",
                            __func__);
                }
        }

out_in_multi_locked:

        IN_MULTI_UNLOCK();

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

        imf_reap(imf);

        if (is_final) {
                /* Remove the gap in the membership and filter array. */
                KASSERT(RB_EMPTY(&imf->imf_sources),
                    ("%s: imf_sources not empty", __func__));
                for (++idx; idx < imo->imo_num_memberships; ++idx) {
                        imo->imo_membership[idx - 1] = imo->imo_membership[idx];
                        imo->imo_mfilters[idx - 1] = imo->imo_mfilters[idx];
                }
                imf_init(&imo->imo_mfilters[idx - 1], MCAST_UNDEFINED,
                    MCAST_EXCLUDE);
                imo->imo_num_memberships--;
        }

out_inp_locked:
        INP_WUNLOCK(inp);
        return (error);
}

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

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

                if (mreqn.imr_ifindex < 0 || V_if_index < mreqn.imr_ifindex)
                        return (EINVAL);

                if (mreqn.imr_ifindex == 0) {
                        ifp = NULL;
                } else {
                        ifp = ifnet_byindex(mreqn.imr_ifindex);
                        if (ifp == NULL)
                                return (EADDRNOTAVAIL);
                }
        } else {
                /*
                 * An interface was specified by IPv4 address.
                 * This is the traditional BSD usage.
                 */
                error = sooptcopyin(sopt, &addr, sizeof(struct in_addr),
                    sizeof(struct in_addr));
                if (error)
                        return (error);
                if (in_nullhost(addr)) {
                        ifp = NULL;
                } else {
                        IN_IFADDR_RLOCK(&in_ifa_tracker);
                        INADDR_TO_IFP(addr, ifp);
                        IN_IFADDR_RUNLOCK(&in_ifa_tracker);
                        if (ifp == NULL)
                                return (EADDRNOTAVAIL);
                }
                CTR3(KTR_IGMPV3, "%s: ifp = %p, addr = 0x%08x", __func__, ifp,
                    ntohl(addr.s_addr));
        }

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

        imo = inp_findmoptions(inp);
        imo->imo_multicast_ifp = ifp;
        imo->imo_multicast_addr.s_addr = INADDR_ANY;
        INP_WUNLOCK(inp);

        return (0);
}

/*
 * Atomically set source filters on a socket for an IPv4 multicast group.
 *
 * SMPng: NOTE: Potentially calls malloc(M_WAITOK) with Giant held.
 */
static int
inp_set_source_filters(struct inpcb *inp, struct sockopt *sopt)
{
        struct __msfilterreq     msfr;
        sockunion_t             *gsa;
        struct ifnet            *ifp;
        struct in_mfilter       *imf;
        struct ip_moptions      *imo;
        struct in_multi         *inm;
        size_t                   idx;
        int                      error;

        error = sooptcopyin(sopt, &msfr, sizeof(struct __msfilterreq),
            sizeof(struct __msfilterreq));
        if (error)
                return (error);

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

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

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

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

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

        if (msfr.msfr_ifindex == 0 || V_if_index < msfr.msfr_ifindex)
                return (EADDRNOTAVAIL);

        ifp = ifnet_byindex(msfr.msfr_ifindex);
        if (ifp == NULL)
                return (EADDRNOTAVAIL);

        /*
         * Take the INP write lock.
         * Check if this socket is a member of this group.
         */
        imo = inp_findmoptions(inp);
        idx = imo_match_group(imo, ifp, &gsa->sa);
        if (idx == -1 || imo->imo_mfilters == NULL) {
                error = EADDRNOTAVAIL;
                goto out_inp_locked;
        }
        inm = imo->imo_membership[idx];
        imf = &imo->imo_mfilters[idx];

        /*
         * Begin state merge transaction at socket layer.
         */
        INP_WLOCK_ASSERT(inp);

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

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

                INP_WUNLOCK(inp);
 
                CTR2(KTR_IGMPV3, "%s: loading %lu source list entries",
                    __func__, (unsigned long)msfr.msfr_nsrcs);
                kss = malloc(sizeof(struct sockaddr_storage) * msfr.msfr_nsrcs,
                    M_TEMP, M_WAITOK);
                error = copyin(msfr.msfr_srcs, kss,
                    sizeof(struct sockaddr_storage) * msfr.msfr_nsrcs);
                if (error) {
                        free(kss, M_TEMP);
                        return (error);
                }

                INP_WLOCK(inp);

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

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

        if (error)
                goto out_imf_rollback;

        INP_WLOCK_ASSERT(inp);
        IN_MULTI_LOCK();

        /*
         * Begin state merge transaction at IGMP layer.
         */
        CTR1(KTR_IGMPV3, "%s: merge inm state", __func__);
        error = inm_merge(inm, imf);
        if (error) {
                CTR1(KTR_IGMPV3, "%s: failed to merge inm state", __func__);
                goto out_in_multi_locked;
        }

        CTR1(KTR_IGMPV3, "%s: doing igmp downcall", __func__);
        error = igmp_change_state(inm);
        if (error)
                CTR1(KTR_IGMPV3, "%s: failed igmp downcall", __func__);

out_in_multi_locked:

        IN_MULTI_UNLOCK();

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

        imf_reap(imf);

out_inp_locked:
        INP_WUNLOCK(inp);
        return (error);
}

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

        error = 0;

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

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

        case IP_MULTICAST_IF:
                error = inp_set_multicast_if(inp, sopt);
                break;

        case IP_MULTICAST_TTL: {
                u_char ttl;

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

                        error = sooptcopyin(sopt, &ittl, sizeof(u_int),
                            sizeof(u_int));
                        if (error)
                                break;
                        if (ittl > 255) {
                                error = EINVAL;
                                break;
                        }
                        ttl = (u_char)ittl;
                }
                imo = inp_findmoptions(inp);
                imo->imo_multicast_ttl = ttl;
                INP_WUNLOCK(inp);
                break;
        }

        case IP_MULTICAST_LOOP: {
                u_char loop;

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

                        error = sooptcopyin(sopt, &iloop, sizeof(u_int),
                                            sizeof(u_int));
                        if (error)
                                break;
                        loop = (u_char)iloop;
                }
                imo = inp_findmoptions(inp);
                imo->imo_multicast_loop = !!loop;
                INP_WUNLOCK(inp);
                break;
        }

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

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

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

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

        default:
                error = EOPNOTSUPP;
                break;
        }

        INP_UNLOCK_ASSERT(inp);

        return (error);
}

/*
 * Expose IGMP's multicast filter mode and source list(s) to userland,
 * keyed by (ifindex, group).
 * The filter mode is written out as a uint32_t, followed by
 * 0..n of struct in_addr.
 * For use by ifmcstat(8).
 * SMPng: NOTE: unlocked read of ifindex space.
 */
static int
sysctl_ip_mcast_filters(SYSCTL_HANDLER_ARGS)
{
        struct in_addr                   src, group;
        struct ifnet                    *ifp;
        struct ifmultiaddr              *ifma;
        struct in_multi                 *inm;
        struct ip_msource               *ims;
        int                             *name;
        int                              retval;
        u_int                            namelen;
        uint32_t                         fmode, ifindex;

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

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

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

        ifindex = name[0];
        if (ifindex <= 0 || ifindex > V_if_index) {
                CTR2(KTR_IGMPV3, "%s: ifindex %u out of range",
                    __func__, ifindex);
                return (ENOENT);
        }

        group.s_addr = name[1];
        if (!IN_MULTICAST(ntohl(group.s_addr))) {
                CTR2(KTR_IGMPV3, "%s: group 0x%08x is not multicast",
                    __func__, ntohl(group.s_addr));
                return (EINVAL);
        }

        ifp = ifnet_byindex(ifindex);
        if (ifp == NULL) {
                CTR2(KTR_IGMPV3, "%s: no ifp for ifindex %u",
                    __func__, ifindex);
                return (ENOENT);
        }

        retval = sysctl_wire_old_buffer(req,
            sizeof(uint32_t) + (in_mcast_maxgrpsrc * sizeof(struct in_addr)));
        if (retval)
                return (retval);

        IN_MULTI_LOCK();

        IF_ADDR_RLOCK(ifp);
        TAILQ_FOREACH(ifma, &ifp->if_multiaddrs, ifma_link) {
                if (ifma->ifma_addr->sa_family != AF_INET ||
                    ifma->ifma_protospec == NULL)
                        continue;
                inm = (struct in_multi *)ifma->ifma_protospec;
                if (!in_hosteq(inm->inm_addr, group))
                        continue;
                fmode = inm->inm_st[1].iss_fmode;
                retval = SYSCTL_OUT(req, &fmode, sizeof(uint32_t));
                if (retval != 0)
                        break;
                RB_FOREACH(ims, ip_msource_tree, &inm->inm_srcs) {
                        CTR2(KTR_IGMPV3, "%s: visit node 0x%08x", __func__,
                            ims->ims_haddr);
                        /*
                         * Only copy-out sources which are in-mode.
                         */
                        if (fmode != ims_get_mode(inm, ims, 1)) {
                                CTR1(KTR_IGMPV3, "%s: skip non-in-mode",
                                    __func__);
                                continue;
                        }
                        src.s_addr = htonl(ims->ims_haddr);
                        retval = SYSCTL_OUT(req, &src, sizeof(struct in_addr));
                        if (retval != 0)
                                break;
                }
        }
        IF_ADDR_RUNLOCK(ifp);

        IN_MULTI_UNLOCK();

        return (retval);
}

#if defined(KTR) && (KTR_COMPILE & KTR_IGMPV3)

static const char *inm_modestrs[] = {
        [MCAST_UNDEFINED] = "un",
        [MCAST_INCLUDE] = "in",
        [MCAST_EXCLUDE] = "ex",
};
_Static_assert(MCAST_UNDEFINED == 0 &&
               MCAST_EXCLUDE + 1 == nitems(inm_modestrs),
               "inm_modestrs: no longer matches #defines");

static const char *
inm_mode_str(const int mode)
{

        if (mode >= MCAST_UNDEFINED && mode <= MCAST_EXCLUDE)
                return (inm_modestrs[mode]);
        return ("??");
}

static const char *inm_statestrs[] = {
        [IGMP_NOT_MEMBER] = "not-member",
        [IGMP_SILENT_MEMBER] = "silent",
        [IGMP_REPORTING_MEMBER] = "reporting",
        [IGMP_IDLE_MEMBER] = "idle",
        [IGMP_LAZY_MEMBER] = "lazy",
        [IGMP_SLEEPING_MEMBER] = "sleeping",
        [IGMP_AWAKENING_MEMBER] = "awakening",
        [IGMP_G_QUERY_PENDING_MEMBER] = "query-pending",
        [IGMP_SG_QUERY_PENDING_MEMBER] = "sg-query-pending",
        [IGMP_LEAVING_MEMBER] = "leaving",
};
_Static_assert(IGMP_NOT_MEMBER == 0 &&
               IGMP_LEAVING_MEMBER + 1 == nitems(inm_statestrs),
               "inm_statetrs: no longer matches #defines");

static const char *
inm_state_str(const int state)
{

        if (state >= IGMP_NOT_MEMBER && state <= IGMP_LEAVING_MEMBER)
                return (inm_statestrs[state]);
        return ("??");
}

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

        if ((ktr_mask & KTR_IGMPV3) == 0)
                return;

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

#else /* !KTR || !(KTR_COMPILE & KTR_IGMPV3) */

void
inm_print(const struct in_multi *inm)
{

}

#endif /* KTR && (KTR_COMPILE & KTR_IGMPV3) */

RB_GENERATE(ip_msource_tree, ip_msource, ims_link, ip_msource_cmp);