FreeBSD/Linux Kernel Cross Reference
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: releng/11.1/sys/netinet/in_mcast.c 315456 2017-03-17 14:54:10Z vangyzen $");
    
    #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;
          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))
                          INADDR_TO_IFP(mreqs.imr_interface, ifp);
  
                  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.
   *
   * SMPng: TODO: Acquire the appropriate locks for INADDR_TO_IFP.
   * 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)) {
                  INADDR_TO_IFP(ina, ifp);
          } 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;
          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))
                          INADDR_TO_IFP(mreqs.imr_interface, ifp);
  
                  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. */
                  for (++idx; idx < imo->imo_num_memberships; ++idx) {
                          imo->imo_membership[idx-1] = imo->imo_membership[idx];
                          imo->imo_mfilters[idx-1] = imo->imo_mfilters[idx];
                  }
                  imo->imo_num_memberships--;
          }
  
  out_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 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 {
                          INADDR_TO_IFP(addr, ifp);
                          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[] = { "un", "in", "ex" };
  
  static const char *
  inm_mode_str(const int mode)
  {
  
          if (mode >= MCAST_UNDEFINED && mode <= MCAST_EXCLUDE)
                  return (inm_modestrs[mode]);
          return ("??");
  }
  
  static const char *inm_statestrs[] = {
          "not-member",
          "silent",
          "idle",
          "lazy",
          "sleeping",
          "awakening",
          "query-pending",
          "sg-query-pending",
          "leaving"
  };
  
  static const char *
  inm_state_str(const int state)
  {
  
          if (state >= IGMP_NOT_MEMBER && state <= IGMP_LEAVING_MEMBER)
                  return (inm_statestrs[state]);
          return ("??");
  }
  
  /*
   * Dump an in_multi structure to the console.
   */
  void
  inm_print(const struct in_multi *inm)
  {
          int t;
          char 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);

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