FreeBSD/Linux Kernel Cross Reference
sys/netinet/igmp.c

     /*-
      * Copyright (c) 2007-2009 Bruce Simpson.
      * Copyright (c) 1988 Stephen Deering.
      * Copyright (c) 1992, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * This code is derived from software contributed to Berkeley by
      * Stephen Deering of Stanford University.
      *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)igmp.c      8.1 (Berkeley) 7/19/93
     */
    
    /*
     * Internet Group Management Protocol (IGMP) routines.
     * [RFC1112, RFC2236, RFC3376]
     *
     * Written by Steve Deering, Stanford, May 1988.
     * Modified by Rosen Sharma, Stanford, Aug 1994.
     * Modified by Bill Fenner, Xerox PARC, Feb 1995.
     * Modified to fully comply to IGMPv2 by Bill Fenner, Oct 1995.
     * Significantly rewritten for IGMPv3, VIMAGE, and SMP by Bruce Simpson.
     *
     * MULTICAST Revision: 3.5.1.4
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/10.0/sys/netinet/igmp.c 279264 2015-02-25 05:56:16Z delphij $");
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/module.h>
    #include <sys/malloc.h>
    #include <sys/mbuf.h>
    #include <sys/socket.h>
    #include <sys/protosw.h>
    #include <sys/kernel.h>
    #include <sys/sysctl.h>
    #include <sys/ktr.h>
    #include <sys/condvar.h>
    
    #include <net/if.h>
    #include <net/netisr.h>
    #include <net/vnet.h>
    
    #include <netinet/in.h>
    #include <netinet/in_var.h>
    #include <netinet/in_systm.h>
    #include <netinet/ip.h>
    #include <netinet/ip_var.h>
    #include <netinet/ip_options.h>
    #include <netinet/igmp.h>
    #include <netinet/igmp_var.h>
    
    #include <machine/in_cksum.h>
    
    #include <security/mac/mac_framework.h>
    
    #ifndef KTR_IGMPV3
    #define KTR_IGMPV3 KTR_INET
    #endif
    
    static struct igmp_ifinfo *
                    igi_alloc_locked(struct ifnet *);
    static void     igi_delete_locked(const struct ifnet *);
    static void     igmp_dispatch_queue(struct ifqueue *, int, const int);
    static void     igmp_fasttimo_vnet(void);
    static void     igmp_final_leave(struct in_multi *, struct igmp_ifinfo *);
    static int      igmp_handle_state_change(struct in_multi *,
                        struct igmp_ifinfo *);
    static int      igmp_initial_join(struct in_multi *, struct igmp_ifinfo *);
    static int      igmp_input_v1_query(struct ifnet *, const struct ip *,
                        const struct igmp *);
    static int      igmp_input_v2_query(struct ifnet *, const struct ip *,
                        const struct igmp *);
    static int      igmp_input_v3_query(struct ifnet *, const struct ip *,
                       /*const*/ struct igmpv3 *);
   static int      igmp_input_v3_group_query(struct in_multi *,
                       struct igmp_ifinfo *, int, /*const*/ struct igmpv3 *);
   static int      igmp_input_v1_report(struct ifnet *, /*const*/ struct ip *,
                       /*const*/ struct igmp *);
   static int      igmp_input_v2_report(struct ifnet *, /*const*/ struct ip *,
                       /*const*/ struct igmp *);
   static void     igmp_intr(struct mbuf *);
   static int      igmp_isgroupreported(const struct in_addr);
   static struct mbuf *
                   igmp_ra_alloc(void);
   #ifdef KTR
   static char *   igmp_rec_type_to_str(const int);
   #endif
   static void     igmp_set_version(struct igmp_ifinfo *, const int);
   static void     igmp_slowtimo_vnet(void);
   static int      igmp_v1v2_queue_report(struct in_multi *, const int);
   static void     igmp_v1v2_process_group_timer(struct in_multi *, const int);
   static void     igmp_v1v2_process_querier_timers(struct igmp_ifinfo *);
   static void     igmp_v2_update_group(struct in_multi *, const int);
   static void     igmp_v3_cancel_link_timers(struct igmp_ifinfo *);
   static void     igmp_v3_dispatch_general_query(struct igmp_ifinfo *);
   static struct mbuf *
                   igmp_v3_encap_report(struct ifnet *, struct mbuf *);
   static int      igmp_v3_enqueue_group_record(struct ifqueue *,
                       struct in_multi *, const int, const int, const int);
   static int      igmp_v3_enqueue_filter_change(struct ifqueue *,
                       struct in_multi *);
   static void     igmp_v3_process_group_timers(struct igmp_ifinfo *,
                       struct ifqueue *, struct ifqueue *, struct in_multi *,
                       const int);
   static int      igmp_v3_merge_state_changes(struct in_multi *,
                       struct ifqueue *);
   static void     igmp_v3_suppress_group_record(struct in_multi *);
   static int      sysctl_igmp_default_version(SYSCTL_HANDLER_ARGS);
   static int      sysctl_igmp_gsr(SYSCTL_HANDLER_ARGS);
   static int      sysctl_igmp_ifinfo(SYSCTL_HANDLER_ARGS);
   
   static const struct netisr_handler igmp_nh = {
           .nh_name = "igmp",
           .nh_handler = igmp_intr,
           .nh_proto = NETISR_IGMP,
           .nh_policy = NETISR_POLICY_SOURCE,
   };
   
   /*
    * System-wide globals.
    *
    * Unlocked access to these is OK, except for the global IGMP output
    * queue. The IGMP subsystem lock ends up being system-wide for the moment,
    * because all VIMAGEs have to share a global output queue, as netisrs
    * themselves are not virtualized.
    *
    * Locking:
    *  * The permitted lock order is: IN_MULTI_LOCK, IGMP_LOCK, IF_ADDR_LOCK.
    *    Any may be taken independently; if any are held at the same
    *    time, the above lock order must be followed.
    *  * All output is delegated to the netisr.
    *    Now that Giant has been eliminated, the netisr may be inlined.
    *  * IN_MULTI_LOCK covers in_multi.
    *  * IGMP_LOCK covers igmp_ifinfo and any global variables in this file,
    *    including the output queue.
    *  * IF_ADDR_LOCK covers if_multiaddrs, which is used for a variety of
    *    per-link state iterators.
    *  * igmp_ifinfo is valid as long as PF_INET is attached to the interface,
    *    therefore it is not refcounted.
    *    We allow unlocked reads of igmp_ifinfo when accessed via in_multi.
    *
    * Reference counting
    *  * IGMP acquires its own reference every time an in_multi is passed to
    *    it and the group is being joined for the first time.
    *  * IGMP releases its reference(s) on in_multi in a deferred way,
    *    because the operations which process the release run as part of
    *    a loop whose control variables are directly affected by the release
    *    (that, and not recursing on the IF_ADDR_LOCK).
    *
    * VIMAGE: Each in_multi corresponds to an ifp, and each ifp corresponds
    * to a vnet in ifp->if_vnet.
    *
    * SMPng: XXX We may potentially race operations on ifma_protospec.
    * The problem is that we currently lack a clean way of taking the
    * IF_ADDR_LOCK() between the ifnet and in layers w/o recursing,
    * as anything which modifies ifma needs to be covered by that lock.
    * So check for ifma_protospec being NULL before proceeding.
    */
   struct mtx               igmp_mtx;
   
   struct mbuf             *m_raopt;                /* Router Alert option */
   static MALLOC_DEFINE(M_IGMP, "igmp", "igmp state");
   
   /*
    * VIMAGE-wide globals.
    *
    * The IGMPv3 timers themselves need to run per-image, however,
    * protosw timers run globally (see tcp).
    * An ifnet can only be in one vimage at a time, and the loopback
    * ifnet, loif, is itself virtualized.
    * It would otherwise be possible to seriously hose IGMP state,
    * and create inconsistencies in upstream multicast routing, if you have
    * multiple VIMAGEs running on the same link joining different multicast
    * groups, UNLESS the "primary IP address" is different. This is because
    * IGMP for IPv4 does not force link-local addresses to be used for each
    * node, unlike MLD for IPv6.
    * Obviously the IGMPv3 per-interface state has per-vimage granularity
    * also as a result.
    *
    * FUTURE: Stop using IFP_TO_IA/INADDR_ANY, and use source address selection
    * policy to control the address used by IGMP on the link.
    */
   static VNET_DEFINE(int, interface_timers_running);      /* IGMPv3 general
                                                            * query response */
   static VNET_DEFINE(int, state_change_timers_running);   /* IGMPv3 state-change
                                                            * retransmit */
   static VNET_DEFINE(int, current_state_timers_running);  /* IGMPv1/v2 host
                                                            * report; IGMPv3 g/sg
                                                            * query response */
   
   #define V_interface_timers_running      VNET(interface_timers_running)
   #define V_state_change_timers_running   VNET(state_change_timers_running)
   #define V_current_state_timers_running  VNET(current_state_timers_running)
   
   static VNET_DEFINE(LIST_HEAD(, igmp_ifinfo), igi_head);
   static VNET_DEFINE(struct igmpstat, igmpstat) = {
           .igps_version = IGPS_VERSION_3,
           .igps_len = sizeof(struct igmpstat),
   };
   static VNET_DEFINE(struct timeval, igmp_gsrdelay) = {10, 0};
   
   #define V_igi_head                      VNET(igi_head)
   #define V_igmpstat                      VNET(igmpstat)
   #define V_igmp_gsrdelay                 VNET(igmp_gsrdelay)
   
   static VNET_DEFINE(int, igmp_recvifkludge) = 1;
   static VNET_DEFINE(int, igmp_sendra) = 1;
   static VNET_DEFINE(int, igmp_sendlocal) = 1;
   static VNET_DEFINE(int, igmp_v1enable) = 1;
   static VNET_DEFINE(int, igmp_v2enable) = 1;
   static VNET_DEFINE(int, igmp_legacysupp);
   static VNET_DEFINE(int, igmp_default_version) = IGMP_VERSION_3;
   
   #define V_igmp_recvifkludge             VNET(igmp_recvifkludge)
   #define V_igmp_sendra                   VNET(igmp_sendra)
   #define V_igmp_sendlocal                VNET(igmp_sendlocal)
   #define V_igmp_v1enable                 VNET(igmp_v1enable)
   #define V_igmp_v2enable                 VNET(igmp_v2enable)
   #define V_igmp_legacysupp               VNET(igmp_legacysupp)
   #define V_igmp_default_version          VNET(igmp_default_version)
   
   /*
    * Virtualized sysctls.
    */
   SYSCTL_VNET_STRUCT(_net_inet_igmp, IGMPCTL_STATS, stats, CTLFLAG_RW,
       &VNET_NAME(igmpstat), igmpstat, "");
   SYSCTL_VNET_INT(_net_inet_igmp, OID_AUTO, recvifkludge, CTLFLAG_RW,
       &VNET_NAME(igmp_recvifkludge), 0,
       "Rewrite IGMPv1/v2 reports from 0.0.0.0 to contain subnet address");
   SYSCTL_VNET_INT(_net_inet_igmp, OID_AUTO, sendra, CTLFLAG_RW,
       &VNET_NAME(igmp_sendra), 0,
       "Send IP Router Alert option in IGMPv2/v3 messages");
   SYSCTL_VNET_INT(_net_inet_igmp, OID_AUTO, sendlocal, CTLFLAG_RW,
       &VNET_NAME(igmp_sendlocal), 0,
       "Send IGMP membership reports for 224.0.0.0/24 groups");
   SYSCTL_VNET_INT(_net_inet_igmp, OID_AUTO, v1enable, CTLFLAG_RW,
       &VNET_NAME(igmp_v1enable), 0,
       "Enable backwards compatibility with IGMPv1");
   SYSCTL_VNET_INT(_net_inet_igmp, OID_AUTO, v2enable, CTLFLAG_RW,
       &VNET_NAME(igmp_v2enable), 0,
       "Enable backwards compatibility with IGMPv2");
   SYSCTL_VNET_INT(_net_inet_igmp, OID_AUTO, legacysupp, CTLFLAG_RW,
       &VNET_NAME(igmp_legacysupp), 0,
       "Allow v1/v2 reports to suppress v3 group responses");
   SYSCTL_VNET_PROC(_net_inet_igmp, OID_AUTO, default_version,
       CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
       &VNET_NAME(igmp_default_version), 0, sysctl_igmp_default_version, "I",
       "Default version of IGMP to run on each interface");
   SYSCTL_VNET_PROC(_net_inet_igmp, OID_AUTO, gsrdelay,
       CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
       &VNET_NAME(igmp_gsrdelay.tv_sec), 0, sysctl_igmp_gsr, "I",
       "Rate limit for IGMPv3 Group-and-Source queries in seconds");
   
   /*
    * Non-virtualized sysctls.
    */
   static SYSCTL_NODE(_net_inet_igmp, OID_AUTO, ifinfo,
       CTLFLAG_RD | CTLFLAG_MPSAFE, sysctl_igmp_ifinfo,
       "Per-interface IGMPv3 state");
   
   static __inline void
   igmp_save_context(struct mbuf *m, struct ifnet *ifp)
   {
   
   #ifdef VIMAGE
           m->m_pkthdr.PH_loc.ptr = ifp->if_vnet;
   #endif /* VIMAGE */
           m->m_pkthdr.flowid = ifp->if_index;
   }
   
   static __inline void
   igmp_scrub_context(struct mbuf *m)
   {
   
           m->m_pkthdr.PH_loc.ptr = NULL;
           m->m_pkthdr.flowid = 0;
   }
   
   #ifdef KTR
   static __inline char *
   inet_ntoa_haddr(in_addr_t haddr)
   {
           struct in_addr ia;
   
           ia.s_addr = htonl(haddr);
           return (inet_ntoa(ia));
   }
   #endif
   
   /*
    * Restore context from a queued IGMP output chain.
    * Return saved ifindex.
    *
    * VIMAGE: The assertion is there to make sure that we
    * actually called CURVNET_SET() with what's in the mbuf chain.
    */
   static __inline uint32_t
   igmp_restore_context(struct mbuf *m)
   {
   
   #ifdef notyet
   #if defined(VIMAGE) && defined(INVARIANTS)
           KASSERT(curvnet == (m->m_pkthdr.PH_loc.ptr),
               ("%s: called when curvnet was not restored", __func__));
   #endif
   #endif
           return (m->m_pkthdr.flowid);
   }
   
   /*
    * Retrieve or set default IGMP version.
    *
    * VIMAGE: Assume curvnet set by caller.
    * SMPng: NOTE: Serialized by IGMP lock.
    */
   static int
   sysctl_igmp_default_version(SYSCTL_HANDLER_ARGS)
   {
           int      error;
           int      new;
   
           error = sysctl_wire_old_buffer(req, sizeof(int));
           if (error)
                   return (error);
   
           IGMP_LOCK();
   
           new = V_igmp_default_version;
   
           error = sysctl_handle_int(oidp, &new, 0, req);
           if (error || !req->newptr)
                   goto out_locked;
   
           if (new < IGMP_VERSION_1 || new > IGMP_VERSION_3) {
                   error = EINVAL;
                   goto out_locked;
           }
   
           CTR2(KTR_IGMPV3, "change igmp_default_version from %d to %d",
                V_igmp_default_version, new);
   
           V_igmp_default_version = new;
   
   out_locked:
           IGMP_UNLOCK();
           return (error);
   }
   
   /*
    * Retrieve or set threshold between group-source queries in seconds.
    *
    * VIMAGE: Assume curvnet set by caller.
    * SMPng: NOTE: Serialized by IGMP lock.
    */
   static int
   sysctl_igmp_gsr(SYSCTL_HANDLER_ARGS)
   {
           int error;
           int i;
   
           error = sysctl_wire_old_buffer(req, sizeof(int));
           if (error)
                   return (error);
   
           IGMP_LOCK();
   
           i = V_igmp_gsrdelay.tv_sec;
   
           error = sysctl_handle_int(oidp, &i, 0, req);
           if (error || !req->newptr)
                   goto out_locked;
   
           if (i < -1 || i >= 60) {
                   error = EINVAL;
                   goto out_locked;
           }
   
           CTR2(KTR_IGMPV3, "change igmp_gsrdelay from %d to %d",
                V_igmp_gsrdelay.tv_sec, i);
           V_igmp_gsrdelay.tv_sec = i;
   
   out_locked:
           IGMP_UNLOCK();
           return (error);
   }
   
   /*
    * Expose struct igmp_ifinfo to userland, keyed by ifindex.
    * For use by ifmcstat(8).
    *
    * SMPng: NOTE: Does an unlocked ifindex space read.
    * VIMAGE: Assume curvnet set by caller. The node handler itself
    * is not directly virtualized.
    */
   static int
   sysctl_igmp_ifinfo(SYSCTL_HANDLER_ARGS)
   {
           int                     *name;
           int                      error;
           u_int                    namelen;
           struct ifnet            *ifp;
           struct igmp_ifinfo      *igi;
   
           name = (int *)arg1;
           namelen = arg2;
   
           if (req->newptr != NULL)
                   return (EPERM);
   
           if (namelen != 1)
                   return (EINVAL);
   
           error = sysctl_wire_old_buffer(req, sizeof(struct igmp_ifinfo));
           if (error)
                   return (error);
   
           IN_MULTI_LOCK();
           IGMP_LOCK();
   
           if (name[0] <= 0 || name[0] > V_if_index) {
                   error = ENOENT;
                   goto out_locked;
           }
   
           error = ENOENT;
   
           ifp = ifnet_byindex(name[0]);
           if (ifp == NULL)
                   goto out_locked;
   
           LIST_FOREACH(igi, &V_igi_head, igi_link) {
                   if (ifp == igi->igi_ifp) {
                           error = SYSCTL_OUT(req, igi,
                               sizeof(struct igmp_ifinfo));
                           break;
                   }
           }
   
   out_locked:
           IGMP_UNLOCK();
           IN_MULTI_UNLOCK();
           return (error);
   }
   
   /*
    * Dispatch an entire queue of pending packet chains
    * using the netisr.
    * VIMAGE: Assumes the vnet pointer has been set.
    */
   static void
   igmp_dispatch_queue(struct ifqueue *ifq, int limit, const int loop)
   {
           struct mbuf *m;
   
           for (;;) {
                   _IF_DEQUEUE(ifq, m);
                   if (m == NULL)
                           break;
                   CTR3(KTR_IGMPV3, "%s: dispatch %p from %p", __func__, ifq, m);
                   if (loop)
                           m->m_flags |= M_IGMP_LOOP;
                   netisr_dispatch(NETISR_IGMP, m);
                   if (--limit == 0)
                           break;
           }
   }
   
   /*
    * Filter outgoing IGMP report state by group.
    *
    * Reports are ALWAYS suppressed for ALL-HOSTS (224.0.0.1).
    * If the net.inet.igmp.sendlocal sysctl is 0, then IGMP reports are
    * disabled for all groups in the 224.0.0.0/24 link-local scope. However,
    * this may break certain IGMP snooping switches which rely on the old
    * report behaviour.
    *
    * Return zero if the given group is one for which IGMP reports
    * should be suppressed, or non-zero if reports should be issued.
    */
   static __inline int
   igmp_isgroupreported(const struct in_addr addr)
   {
   
           if (in_allhosts(addr) ||
               ((!V_igmp_sendlocal && IN_LOCAL_GROUP(ntohl(addr.s_addr)))))
                   return (0);
   
           return (1);
   }
   
   /*
    * Construct a Router Alert option to use in outgoing packets.
    */
   static struct mbuf *
   igmp_ra_alloc(void)
   {
           struct mbuf     *m;
           struct ipoption *p;
   
           m = m_get(M_WAITOK, MT_DATA);
           p = mtod(m, struct ipoption *);
           p->ipopt_dst.s_addr = INADDR_ANY;
           p->ipopt_list[0] = IPOPT_RA;    /* Router Alert Option */
           p->ipopt_list[1] = 0x04;        /* 4 bytes long */
           p->ipopt_list[2] = IPOPT_EOL;   /* End of IP option list */
           p->ipopt_list[3] = 0x00;        /* pad byte */
           m->m_len = sizeof(p->ipopt_dst) + p->ipopt_list[1];
   
           return (m);
   }
   
   /*
    * Attach IGMP when PF_INET is attached to an interface.
    */
   struct igmp_ifinfo *
   igmp_domifattach(struct ifnet *ifp)
   {
           struct igmp_ifinfo *igi;
   
           CTR3(KTR_IGMPV3, "%s: called for ifp %p(%s)",
               __func__, ifp, ifp->if_xname);
   
           IGMP_LOCK();
   
           igi = igi_alloc_locked(ifp);
           if (!(ifp->if_flags & IFF_MULTICAST))
                   igi->igi_flags |= IGIF_SILENT;
   
           IGMP_UNLOCK();
   
           return (igi);
   }
   
   /*
    * VIMAGE: assume curvnet set by caller.
    */
   static struct igmp_ifinfo *
   igi_alloc_locked(/*const*/ struct ifnet *ifp)
   {
           struct igmp_ifinfo *igi;
   
           IGMP_LOCK_ASSERT();
   
           igi = malloc(sizeof(struct igmp_ifinfo), M_IGMP, M_NOWAIT|M_ZERO);
           if (igi == NULL)
                   goto out;
   
           igi->igi_ifp = ifp;
           igi->igi_version = V_igmp_default_version;
           igi->igi_flags = 0;
           igi->igi_rv = IGMP_RV_INIT;
           igi->igi_qi = IGMP_QI_INIT;
           igi->igi_qri = IGMP_QRI_INIT;
           igi->igi_uri = IGMP_URI_INIT;
   
           SLIST_INIT(&igi->igi_relinmhead);
   
           /*
            * Responses to general queries are subject to bounds.
            */
           IFQ_SET_MAXLEN(&igi->igi_gq, IGMP_MAX_RESPONSE_PACKETS);
   
           LIST_INSERT_HEAD(&V_igi_head, igi, igi_link);
   
           CTR2(KTR_IGMPV3, "allocate igmp_ifinfo for ifp %p(%s)",
                ifp, ifp->if_xname);
   
   out:
           return (igi);
   }
   
   /*
    * Hook for ifdetach.
    *
    * NOTE: Some finalization tasks need to run before the protocol domain
    * is detached, but also before the link layer does its cleanup.
    *
    * SMPNG: igmp_ifdetach() needs to take IF_ADDR_LOCK().
    * XXX This is also bitten by unlocked ifma_protospec access.
    */
   void
   igmp_ifdetach(struct ifnet *ifp)
   {
           struct igmp_ifinfo      *igi;
           struct ifmultiaddr      *ifma;
           struct in_multi         *inm, *tinm;
   
           CTR3(KTR_IGMPV3, "%s: called for ifp %p(%s)", __func__, ifp,
               ifp->if_xname);
   
           IGMP_LOCK();
   
           igi = ((struct in_ifinfo *)ifp->if_afdata[AF_INET])->ii_igmp;
           if (igi->igi_version == IGMP_VERSION_3) {
                   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;
   #if 0
                           KASSERT(ifma->ifma_protospec != NULL,
                               ("%s: ifma_protospec is NULL", __func__));
   #endif
                           inm = (struct in_multi *)ifma->ifma_protospec;
                           if (inm->inm_state == IGMP_LEAVING_MEMBER) {
                                   SLIST_INSERT_HEAD(&igi->igi_relinmhead,
                                       inm, inm_nrele);
                           }
                           inm_clear_recorded(inm);
                   }
                   IF_ADDR_RUNLOCK(ifp);
                   /*
                    * Free the in_multi reference(s) for this IGMP lifecycle.
                    */
                   SLIST_FOREACH_SAFE(inm, &igi->igi_relinmhead, inm_nrele,
                       tinm) {
                           SLIST_REMOVE_HEAD(&igi->igi_relinmhead, inm_nrele);
                           inm_release_locked(inm);
                   }
           }
   
           IGMP_UNLOCK();
   }
   
   /*
    * Hook for domifdetach.
    */
   void
   igmp_domifdetach(struct ifnet *ifp)
   {
           struct igmp_ifinfo *igi;
   
           CTR3(KTR_IGMPV3, "%s: called for ifp %p(%s)",
               __func__, ifp, ifp->if_xname);
   
           IGMP_LOCK();
   
           igi = ((struct in_ifinfo *)ifp->if_afdata[AF_INET])->ii_igmp;
           igi_delete_locked(ifp);
   
           IGMP_UNLOCK();
   }
   
   static void
   igi_delete_locked(const struct ifnet *ifp)
   {
           struct igmp_ifinfo *igi, *tigi;
   
           CTR3(KTR_IGMPV3, "%s: freeing igmp_ifinfo for ifp %p(%s)",
               __func__, ifp, ifp->if_xname);
   
           IGMP_LOCK_ASSERT();
   
           LIST_FOREACH_SAFE(igi, &V_igi_head, igi_link, tigi) {
                   if (igi->igi_ifp == ifp) {
                           /*
                            * Free deferred General Query responses.
                            */
                           _IF_DRAIN(&igi->igi_gq);
   
                           LIST_REMOVE(igi, igi_link);
   
                           KASSERT(SLIST_EMPTY(&igi->igi_relinmhead),
                               ("%s: there are dangling in_multi references",
                               __func__));
   
                           free(igi, M_IGMP);
                           return;
                   }
           }
   
   #ifdef INVARIANTS
           panic("%s: igmp_ifinfo not found for ifp %p\n", __func__,  ifp);
   #endif
   }
   
   /*
    * Process a received IGMPv1 query.
    * Return non-zero if the message should be dropped.
    *
    * VIMAGE: The curvnet pointer is derived from the input ifp.
    */
   static int
   igmp_input_v1_query(struct ifnet *ifp, const struct ip *ip,
       const struct igmp *igmp)
   {
           struct ifmultiaddr      *ifma;
           struct igmp_ifinfo      *igi;
           struct in_multi         *inm;
   
           /*
            * IGMPv1 Host Mmembership Queries SHOULD always be addressed to
            * 224.0.0.1. They are always treated as General Queries.
            * igmp_group is always ignored. Do not drop it as a userland
            * daemon may wish to see it.
            * XXX SMPng: unlocked increments in igmpstat assumed atomic.
            */
           if (!in_allhosts(ip->ip_dst) || !in_nullhost(igmp->igmp_group)) {
                   IGMPSTAT_INC(igps_rcv_badqueries);
                   return (0);
           }
           IGMPSTAT_INC(igps_rcv_gen_queries);
   
           IN_MULTI_LOCK();
           IGMP_LOCK();
   
           igi = ((struct in_ifinfo *)ifp->if_afdata[AF_INET])->ii_igmp;
           KASSERT(igi != NULL, ("%s: no igmp_ifinfo for ifp %p", __func__, ifp));
   
           if (igi->igi_flags & IGIF_LOOPBACK) {
                   CTR2(KTR_IGMPV3, "ignore v1 query on IGIF_LOOPBACK ifp %p(%s)",
                       ifp, ifp->if_xname);
                   goto out_locked;
           }
   
           /*
            * Switch to IGMPv1 host compatibility mode.
            */
           igmp_set_version(igi, IGMP_VERSION_1);
   
           CTR2(KTR_IGMPV3, "process v1 query on ifp %p(%s)", ifp, ifp->if_xname);
   
           /*
            * Start the timers in all of our group records
            * for the interface on which the query arrived,
            * except those which are already running.
            */
           IF_ADDR_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 (inm->inm_timer != 0)
                           continue;
                   switch (inm->inm_state) {
                   case IGMP_NOT_MEMBER:
                   case IGMP_SILENT_MEMBER:
                           break;
                   case IGMP_G_QUERY_PENDING_MEMBER:
                   case IGMP_SG_QUERY_PENDING_MEMBER:
                   case IGMP_REPORTING_MEMBER:
                   case IGMP_IDLE_MEMBER:
                   case IGMP_LAZY_MEMBER:
                   case IGMP_SLEEPING_MEMBER:
                   case IGMP_AWAKENING_MEMBER:
                           inm->inm_state = IGMP_REPORTING_MEMBER;
                           inm->inm_timer = IGMP_RANDOM_DELAY(
                               IGMP_V1V2_MAX_RI * PR_FASTHZ);
                           V_current_state_timers_running = 1;
                           break;
                   case IGMP_LEAVING_MEMBER:
                           break;
                   }
           }
           IF_ADDR_RUNLOCK(ifp);
   
   out_locked:
           IGMP_UNLOCK();
           IN_MULTI_UNLOCK();
   
           return (0);
   }
   
   /*
    * Process a received IGMPv2 general or group-specific query.
    */
   static int
   igmp_input_v2_query(struct ifnet *ifp, const struct ip *ip,
       const struct igmp *igmp)
   {
           struct ifmultiaddr      *ifma;
           struct igmp_ifinfo      *igi;
           struct in_multi         *inm;
           int                      is_general_query;
           uint16_t                 timer;
   
           is_general_query = 0;
   
           /*
            * Validate address fields upfront.
            * XXX SMPng: unlocked increments in igmpstat assumed atomic.
            */
           if (in_nullhost(igmp->igmp_group)) {
                   /*
                    * IGMPv2 General Query.
                    * If this was not sent to the all-hosts group, ignore it.
                    */
                   if (!in_allhosts(ip->ip_dst))
                           return (0);
                   IGMPSTAT_INC(igps_rcv_gen_queries);
                   is_general_query = 1;
           } else {
                   /* IGMPv2 Group-Specific Query. */
                   IGMPSTAT_INC(igps_rcv_group_queries);
           }
   
           IN_MULTI_LOCK();
           IGMP_LOCK();
   
           igi = ((struct in_ifinfo *)ifp->if_afdata[AF_INET])->ii_igmp;
           KASSERT(igi != NULL, ("%s: no igmp_ifinfo for ifp %p", __func__, ifp));
   
           if (igi->igi_flags & IGIF_LOOPBACK) {
                   CTR2(KTR_IGMPV3, "ignore v2 query on IGIF_LOOPBACK ifp %p(%s)",
                       ifp, ifp->if_xname);
                   goto out_locked;
           }
   
           /*
            * Ignore v2 query if in v1 Compatibility Mode.
            */
           if (igi->igi_version == IGMP_VERSION_1)
                   goto out_locked;
   
           igmp_set_version(igi, IGMP_VERSION_2);
   
           timer = igmp->igmp_code * PR_FASTHZ / IGMP_TIMER_SCALE;
           if (timer == 0)
                   timer = 1;
   
           if (is_general_query) {
                   /*
                    * For each reporting group joined on this
                    * interface, kick the report timer.
                    */
                   CTR2(KTR_IGMPV3, "process v2 general query on ifp %p(%s)",
                       ifp, ifp->if_xname);
                   IF_ADDR_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;
                           igmp_v2_update_group(inm, timer);
                   }
                   IF_ADDR_RUNLOCK(ifp);
           } else {
                   /*
                    * Group-specific IGMPv2 query, we need only
                    * look up the single group to process it.
                    */
                   inm = inm_lookup(ifp, igmp->igmp_group);
                   if (inm != NULL) {
                           CTR3(KTR_IGMPV3, "process v2 query %s on ifp %p(%s)",
                               inet_ntoa(igmp->igmp_group), ifp, ifp->if_xname);
                           igmp_v2_update_group(inm, timer);
                   }
           }
   
   out_locked:
           IGMP_UNLOCK();
           IN_MULTI_UNLOCK();
   
           return (0);
   }
   
   /*
    * Update the report timer on a group in response to an IGMPv2 query.
    *
    * If we are becoming the reporting member for this group, start the timer.
    * If we already are the reporting member for this group, and timer is
    * below the threshold, reset it.
    *
    * We may be updating the group for the first time since we switched
    * to IGMPv3. If we are, then we must clear any recorded source lists,
    * and transition to REPORTING state; the group timer is overloaded
    * for group and group-source query responses. 
    *
    * Unlike IGMPv3, the delay per group should be jittered
    * to avoid bursts of IGMPv2 reports.
    */
   static void
   igmp_v2_update_group(struct in_multi *inm, const int timer)
   {
   
           CTR4(KTR_IGMPV3, "%s: %s/%s timer=%d", __func__,
               inet_ntoa(inm->inm_addr), inm->inm_ifp->if_xname, timer);
   
           IN_MULTI_LOCK_ASSERT();
   
           switch (inm->inm_state) {
           case IGMP_NOT_MEMBER:
           case IGMP_SILENT_MEMBER:
                   break;
           case IGMP_REPORTING_MEMBER:
                   if (inm->inm_timer != 0 &&
                       inm->inm_timer <= timer) {
                           CTR1(KTR_IGMPV3, "%s: REPORTING and timer running, "
                               "skipping.", __func__);
                           break;
                   }
                   /* FALLTHROUGH */
           case IGMP_SG_QUERY_PENDING_MEMBER:
           case IGMP_G_QUERY_PENDING_MEMBER:
           case IGMP_IDLE_MEMBER:
           case IGMP_LAZY_MEMBER:
           case IGMP_AWAKENING_MEMBER:
                   CTR1(KTR_IGMPV3, "%s: ->REPORTING", __func__);
                   inm->inm_state = IGMP_REPORTING_MEMBER;
                   inm->inm_timer = IGMP_RANDOM_DELAY(timer);
                   V_current_state_timers_running = 1;
                   break;
           case IGMP_SLEEPING_MEMBER:
                   CTR1(KTR_IGMPV3, "%s: ->AWAKENING", __func__);
                   inm->inm_state = IGMP_AWAKENING_MEMBER;
                   break;
           case IGMP_LEAVING_MEMBER:
                   break;
           }
   }
   
   /*
    * Process a received IGMPv3 general, group-specific or
    * group-and-source-specific query.
    * Assumes m has already been pulled up to the full IGMP message length.
    * Return 0 if successful, otherwise an appropriate error code is returned.
    */
   static int
   igmp_input_v3_query(struct ifnet *ifp, const struct ip *ip,
       /*const*/ struct igmpv3 *igmpv3)
   {
           struct igmp_ifinfo      *igi;
           struct in_multi         *inm;
           int                      is_general_query;
           uint32_t                 maxresp, nsrc, qqi;
           uint16_t                 timer;
           uint8_t                  qrv;
   
           is_general_query = 0;
   
           CTR2(KTR_IGMPV3, "process v3 query on ifp %p(%s)", ifp, ifp->if_xname);
   
           maxresp = igmpv3->igmp_code;    /* in 1/10ths of a second */
           if (maxresp >= 128) {
                   maxresp = IGMP_MANT(igmpv3->igmp_code) <<
                             (IGMP_EXP(igmpv3->igmp_code) + 3);
           }
   
           /*
            * Robustness must never be less than 2 for on-wire IGMPv3.
            * FUTURE: Check if ifp has IGIF_LOOPBACK set, as we will make
            * an exception for interfaces whose IGMPv3 state changes
            * are redirected to loopback (e.g. MANET).
            */
           qrv = IGMP_QRV(igmpv3->igmp_misc);
           if (qrv < 2) {
                   CTR3(KTR_IGMPV3, "%s: clamping qrv %d to %d", __func__,
                       qrv, IGMP_RV_INIT);
                   qrv = IGMP_RV_INIT;
           }
   
           qqi = igmpv3->igmp_qqi;
           if (qqi >= 128) {
                   qqi = IGMP_MANT(igmpv3->igmp_qqi) <<
                        (IGMP_EXP(igmpv3->igmp_qqi) + 3);
           }
   
           timer = maxresp * PR_FASTHZ / IGMP_TIMER_SCALE;
           if (timer == 0)
                   timer = 1;
   
           nsrc = ntohs(igmpv3->igmp_numsrc);
   
           /*
            * Validate address fields and versions upfront before
            * accepting v3 query.
            * XXX SMPng: Unlocked access to igmpstat counters here.
            */
           if (in_nullhost(igmpv3->igmp_group)) {
                   /*
                    * IGMPv3 General Query.
                    *
                   * General Queries SHOULD be directed to 224.0.0.1.
                   * A general query with a source list has undefined
                   * behaviour; discard it.
                   */
                  IGMPSTAT_INC(igps_rcv_gen_queries);
                  if (!in_allhosts(ip->ip_dst) || nsrc > 0) {
                          IGMPSTAT_INC(igps_rcv_badqueries);
                          return (0);
                  }
                  is_general_query = 1;
          } else {
                  /* Group or group-source specific query. */
                  if (nsrc == 0)
                          IGMPSTAT_INC(igps_rcv_group_queries);
                  else
                          IGMPSTAT_INC(igps_rcv_gsr_queries);
          }
  
          IN_MULTI_LOCK();
          IGMP_LOCK();
  
          igi = ((struct in_ifinfo *)ifp->if_afdata[AF_INET])->ii_igmp;
          KASSERT(igi != NULL, ("%s: no igmp_ifinfo for ifp %p", __func__, ifp));
  
          if (igi->igi_flags & IGIF_LOOPBACK) {
                  CTR2(KTR_IGMPV3, "ignore v3 query on IGIF_LOOPBACK ifp %p(%s)",
                      ifp, ifp->if_xname);
                  goto out_locked;
          }
  
          /*
           * Discard the v3 query if we're in Compatibility Mode.
           * The RFC is not obviously worded that hosts need to stay in
           * compatibility mode until the Old Version Querier Present
           * timer expires.
           */
          if (igi->igi_version != IGMP_VERSION_3) {
                  CTR3(KTR_IGMPV3, "ignore v3 query in v%d mode on ifp %p(%s)",
                      igi->igi_version, ifp, ifp->if_xname);
                  goto out_locked;
          }
  
          igmp_set_version(igi, IGMP_VERSION_3);
          igi->igi_rv = qrv;
          igi->igi_qi = qqi;
          igi->igi_qri = maxresp;
  
          CTR4(KTR_IGMPV3, "%s: qrv %d qi %d qri %d", __func__, qrv, qqi,
              maxresp);
  
          if (is_general_query) {
                  /*
                   * Schedule a current-state report on this ifp for
                   * all groups, possibly containing source lists.
                   * If there is a pending General Query response
                   * scheduled earlier than the selected delay, do
                   * not schedule any other reports.
                   * Otherwise, reset the interface timer.
                   */
                  CTR2(KTR_IGMPV3, "process v3 general query on ifp %p(%s)",
                      ifp, ifp->if_xname);
                  if (igi->igi_v3_timer == 0 || igi->igi_v3_timer >= timer) {
                          igi->igi_v3_timer = IGMP_RANDOM_DELAY(timer);
                          V_interface_timers_running = 1;
                  }
          } else {
                  /*
                   * Group-source-specific queries are throttled on
                   * a per-group basis to defeat denial-of-service attempts.
                   * Queries for groups we are not a member of on this
                   * link are simply ignored.
                   */
                  inm = inm_lookup(ifp, igmpv3->igmp_group);
                  if (inm == NULL)
                          goto out_locked;
                  if (nsrc > 0) {
                          if (!ratecheck(&inm->inm_lastgsrtv,
                              &V_igmp_gsrdelay)) {
                                  CTR1(KTR_IGMPV3, "%s: GS query throttled.",
                                      __func__);
                                  IGMPSTAT_INC(igps_drop_gsr_queries);
                                  goto out_locked;
                          }
                  }
                  CTR3(KTR_IGMPV3, "process v3 %s query on ifp %p(%s)",
                       inet_ntoa(igmpv3->igmp_group), ifp, ifp->if_xname);
                  /*
                   * If there is a pending General Query response
                   * scheduled sooner than the selected delay, no
                   * further report need be scheduled.
                   * Otherwise, prepare to respond to the
                   * group-specific or group-and-source query.
                   */
                  if (igi->igi_v3_timer == 0 || igi->igi_v3_timer >= timer)
                          igmp_input_v3_group_query(inm, igi, timer, igmpv3);
          }
  
  out_locked:
          IGMP_UNLOCK();
          IN_MULTI_UNLOCK();
  
          return (0);
  }
  
  /*
   * Process a recieved IGMPv3 group-specific or group-and-source-specific
   * query.
   * Return <0 if any error occured. Currently this is ignored.
   */
  static int
  igmp_input_v3_group_query(struct in_multi *inm, struct igmp_ifinfo *igi,
      int timer, /*const*/ struct igmpv3 *igmpv3)
  {
          int                      retval;
          uint16_t                 nsrc;
  
          IN_MULTI_LOCK_ASSERT();
          IGMP_LOCK_ASSERT();
  
          retval = 0;
  
          switch (inm->inm_state) {
          case IGMP_NOT_MEMBER:
          case IGMP_SILENT_MEMBER:
          case IGMP_SLEEPING_MEMBER:
          case IGMP_LAZY_MEMBER:
          case IGMP_AWAKENING_MEMBER:
          case IGMP_IDLE_MEMBER:
          case IGMP_LEAVING_MEMBER:
                  return (retval);
                  break;
          case IGMP_REPORTING_MEMBER:
          case IGMP_G_QUERY_PENDING_MEMBER:
          case IGMP_SG_QUERY_PENDING_MEMBER:
                  break;
          }
  
          nsrc = ntohs(igmpv3->igmp_numsrc);
  
          /*
           * Deal with group-specific queries upfront.
           * If any group query is already pending, purge any recorded
           * source-list state if it exists, and schedule a query response
           * for this group-specific query.
           */
          if (nsrc == 0) {
                  if (inm->inm_state == IGMP_G_QUERY_PENDING_MEMBER ||
                      inm->inm_state == IGMP_SG_QUERY_PENDING_MEMBER) {
                          inm_clear_recorded(inm);
                          timer = min(inm->inm_timer, timer);
                  }
                  inm->inm_state = IGMP_G_QUERY_PENDING_MEMBER;
                  inm->inm_timer = IGMP_RANDOM_DELAY(timer);
                  V_current_state_timers_running = 1;
                  return (retval);
          }
  
          /*
           * Deal with the case where a group-and-source-specific query has
           * been received but a group-specific query is already pending.
           */
          if (inm->inm_state == IGMP_G_QUERY_PENDING_MEMBER) {
                  timer = min(inm->inm_timer, timer);
                  inm->inm_timer = IGMP_RANDOM_DELAY(timer);
                  V_current_state_timers_running = 1;
                  return (retval);
          }
  
          /*
           * Finally, deal with the case where a group-and-source-specific
           * query has been received, where a response to a previous g-s-r
           * query exists, or none exists.
           * In this case, we need to parse the source-list which the Querier
           * has provided us with and check if we have any source list filter
           * entries at T1 for these sources. If we do not, there is no need
           * schedule a report and the query may be dropped.
           * If we do, we must record them and schedule a current-state
           * report for those sources.
           * FIXME: Handling source lists larger than 1 mbuf requires that
           * we pass the mbuf chain pointer down to this function, and use
           * m_getptr() to walk the chain.
           */
          if (inm->inm_nsrc > 0) {
                  const struct in_addr    *ap;
                  int                      i, nrecorded;
  
                  ap = (const struct in_addr *)(igmpv3 + 1);
                  nrecorded = 0;
                  for (i = 0; i < nsrc; i++, ap++) {
                          retval = inm_record_source(inm, ap->s_addr);
                          if (retval < 0)
                                  break;
                          nrecorded += retval;
                  }
                  if (nrecorded > 0) {
                          CTR1(KTR_IGMPV3,
                              "%s: schedule response to SG query", __func__);
                          inm->inm_state = IGMP_SG_QUERY_PENDING_MEMBER;
                          inm->inm_timer = IGMP_RANDOM_DELAY(timer);
                          V_current_state_timers_running = 1;
                  }
          }
  
          return (retval);
  }
  
  /*
   * Process a received IGMPv1 host membership report.
   *
   * NOTE: 0.0.0.0 workaround breaks const correctness.
   */
  static int
  igmp_input_v1_report(struct ifnet *ifp, /*const*/ struct ip *ip,
      /*const*/ struct igmp *igmp)
  {
          struct in_ifaddr *ia;
          struct in_multi *inm;
  
          IGMPSTAT_INC(igps_rcv_reports);
  
          if (ifp->if_flags & IFF_LOOPBACK)
                  return (0);
  
          if (!IN_MULTICAST(ntohl(igmp->igmp_group.s_addr)) ||
              !in_hosteq(igmp->igmp_group, ip->ip_dst)) {
                  IGMPSTAT_INC(igps_rcv_badreports);
                  return (EINVAL);
          }
  
          /*
           * RFC 3376, Section 4.2.13, 9.2, 9.3:
           * Booting clients may use the source address 0.0.0.0. Some
           * IGMP daemons may not know how to use IP_RECVIF to determine
           * the interface upon which this message was received.
           * Replace 0.0.0.0 with the subnet address if told to do so.
           */
          if (V_igmp_recvifkludge && in_nullhost(ip->ip_src)) {
                  IFP_TO_IA(ifp, ia);
                  if (ia != NULL) {
                          ip->ip_src.s_addr = htonl(ia->ia_subnet);
                          ifa_free(&ia->ia_ifa);
                  }
          }
  
          CTR3(KTR_IGMPV3, "process v1 report %s on ifp %p(%s)",
               inet_ntoa(igmp->igmp_group), ifp, ifp->if_xname);
  
          /*
           * IGMPv1 report suppression.
           * If we are a member of this group, and our membership should be
           * reported, stop our group timer and transition to the 'lazy' state.
           */
          IN_MULTI_LOCK();
          inm = inm_lookup(ifp, igmp->igmp_group);
          if (inm != NULL) {
                  struct igmp_ifinfo *igi;
  
                  igi = inm->inm_igi;
                  if (igi == NULL) {
                          KASSERT(igi != NULL,
                              ("%s: no igi for ifp %p", __func__, ifp));
                          goto out_locked;
                  }
  
                  IGMPSTAT_INC(igps_rcv_ourreports);
  
                  /*
                   * If we are in IGMPv3 host mode, do not allow the
                   * other host's IGMPv1 report to suppress our reports
                   * unless explicitly configured to do so.
                   */
                  if (igi->igi_version == IGMP_VERSION_3) {
                          if (V_igmp_legacysupp)
                                  igmp_v3_suppress_group_record(inm);
                          goto out_locked;
                  }
  
                  inm->inm_timer = 0;
  
                  switch (inm->inm_state) {
                  case IGMP_NOT_MEMBER:
                  case IGMP_SILENT_MEMBER:
                          break;
                  case IGMP_IDLE_MEMBER:
                  case IGMP_LAZY_MEMBER:
                  case IGMP_AWAKENING_MEMBER:
                          CTR3(KTR_IGMPV3,
                              "report suppressed for %s on ifp %p(%s)",
                              inet_ntoa(igmp->igmp_group), ifp, ifp->if_xname);
                  case IGMP_SLEEPING_MEMBER:
                          inm->inm_state = IGMP_SLEEPING_MEMBER;
                          break;
                  case IGMP_REPORTING_MEMBER:
                          CTR3(KTR_IGMPV3,
                              "report suppressed for %s on ifp %p(%s)",
                              inet_ntoa(igmp->igmp_group), ifp, ifp->if_xname);
                          if (igi->igi_version == IGMP_VERSION_1)
                                  inm->inm_state = IGMP_LAZY_MEMBER;
                          else if (igi->igi_version == IGMP_VERSION_2)
                                  inm->inm_state = IGMP_SLEEPING_MEMBER;
                          break;
                  case IGMP_G_QUERY_PENDING_MEMBER:
                  case IGMP_SG_QUERY_PENDING_MEMBER:
                  case IGMP_LEAVING_MEMBER:
                          break;
                  }
          }
  
  out_locked:
          IN_MULTI_UNLOCK();
  
          return (0);
  }
  
  /*
   * Process a received IGMPv2 host membership report.
   *
   * NOTE: 0.0.0.0 workaround breaks const correctness.
   */
  static int
  igmp_input_v2_report(struct ifnet *ifp, /*const*/ struct ip *ip,
      /*const*/ struct igmp *igmp)
  {
          struct in_ifaddr *ia;
          struct in_multi *inm;
  
          /*
           * Make sure we don't hear our own membership report.  Fast
           * leave requires knowing that we are the only member of a
           * group.
           */
          IFP_TO_IA(ifp, ia);
          if (ia != NULL && in_hosteq(ip->ip_src, IA_SIN(ia)->sin_addr)) {
                  ifa_free(&ia->ia_ifa);
                  return (0);
          }
  
          IGMPSTAT_INC(igps_rcv_reports);
  
          if (ifp->if_flags & IFF_LOOPBACK) {
                  if (ia != NULL)
                          ifa_free(&ia->ia_ifa);
                  return (0);
          }
  
          if (!IN_MULTICAST(ntohl(igmp->igmp_group.s_addr)) ||
              !in_hosteq(igmp->igmp_group, ip->ip_dst)) {
                  if (ia != NULL)
                          ifa_free(&ia->ia_ifa);
                  IGMPSTAT_INC(igps_rcv_badreports);
                  return (EINVAL);
          }
  
          /*
           * RFC 3376, Section 4.2.13, 9.2, 9.3:
           * Booting clients may use the source address 0.0.0.0. Some
           * IGMP daemons may not know how to use IP_RECVIF to determine
           * the interface upon which this message was received.
           * Replace 0.0.0.0 with the subnet address if told to do so.
           */
          if (V_igmp_recvifkludge && in_nullhost(ip->ip_src)) {
                  if (ia != NULL)
                          ip->ip_src.s_addr = htonl(ia->ia_subnet);
          }
          if (ia != NULL)
                  ifa_free(&ia->ia_ifa);
  
          CTR3(KTR_IGMPV3, "process v2 report %s on ifp %p(%s)",
               inet_ntoa(igmp->igmp_group), ifp, ifp->if_xname);
  
          /*
           * IGMPv2 report suppression.
           * If we are a member of this group, and our membership should be
           * reported, and our group timer is pending or about to be reset,
           * stop our group timer by transitioning to the 'lazy' state.
           */
          IN_MULTI_LOCK();
          inm = inm_lookup(ifp, igmp->igmp_group);
          if (inm != NULL) {
                  struct igmp_ifinfo *igi;
  
                  igi = inm->inm_igi;
                  KASSERT(igi != NULL, ("%s: no igi for ifp %p", __func__, ifp));
  
                  IGMPSTAT_INC(igps_rcv_ourreports);
  
                  /*
                   * If we are in IGMPv3 host mode, do not allow the
                   * other host's IGMPv1 report to suppress our reports
                   * unless explicitly configured to do so.
                   */
                  if (igi->igi_version == IGMP_VERSION_3) {
                          if (V_igmp_legacysupp)
                                  igmp_v3_suppress_group_record(inm);
                          goto out_locked;
                  }
  
                  inm->inm_timer = 0;
  
                  switch (inm->inm_state) {
                  case IGMP_NOT_MEMBER:
                  case IGMP_SILENT_MEMBER:
                  case IGMP_SLEEPING_MEMBER:
                          break;
                  case IGMP_REPORTING_MEMBER:
                  case IGMP_IDLE_MEMBER:
                  case IGMP_AWAKENING_MEMBER:
                          CTR3(KTR_IGMPV3,
                              "report suppressed for %s on ifp %p(%s)",
                              inet_ntoa(igmp->igmp_group), ifp, ifp->if_xname);
                  case IGMP_LAZY_MEMBER:
                          inm->inm_state = IGMP_LAZY_MEMBER;
                          break;
                  case IGMP_G_QUERY_PENDING_MEMBER:
                  case IGMP_SG_QUERY_PENDING_MEMBER:
                  case IGMP_LEAVING_MEMBER:
                          break;
                  }
          }
  
  out_locked:
          IN_MULTI_UNLOCK();
  
          return (0);
  }
  
  void
  igmp_input(struct mbuf *m, int off)
  {
          int iphlen;
          struct ifnet *ifp;
          struct igmp *igmp;
          struct ip *ip;
          int igmplen;
          int minlen;
          int queryver;
  
          CTR3(KTR_IGMPV3, "%s: called w/mbuf (%p,%d)", __func__, m, off);
  
          ifp = m->m_pkthdr.rcvif;
  
          IGMPSTAT_INC(igps_rcv_total);
  
          ip = mtod(m, struct ip *);
          iphlen = off;
          igmplen = ntohs(ip->ip_len) - off;
  
          /*
           * Validate lengths.
           */
          if (igmplen < IGMP_MINLEN) {
                  IGMPSTAT_INC(igps_rcv_tooshort);
                  m_freem(m);
                  return;
          }
  
          /*
           * Always pullup to the minimum size for v1/v2 or v3
           * to amortize calls to m_pullup().
           */
          minlen = iphlen;
          if (igmplen >= IGMP_V3_QUERY_MINLEN)
                  minlen += IGMP_V3_QUERY_MINLEN;
          else
                  minlen += IGMP_MINLEN;
          if ((m->m_flags & M_EXT || m->m_len < minlen) &&
              (m = m_pullup(m, minlen)) == 0) {
                  IGMPSTAT_INC(igps_rcv_tooshort);
                  return;
          }
          ip = mtod(m, struct ip *);
  
          /*
           * Validate checksum.
           */
          m->m_data += iphlen;
          m->m_len -= iphlen;
          igmp = mtod(m, struct igmp *);
          if (in_cksum(m, igmplen)) {
                  IGMPSTAT_INC(igps_rcv_badsum);
                  m_freem(m);
                  return;
          }
          m->m_data -= iphlen;
          m->m_len += iphlen;
  
          /*
           * IGMP control traffic is link-scope, and must have a TTL of 1.
           * DVMRP traffic (e.g. mrinfo, mtrace) is an exception;
           * probe packets may come from beyond the LAN.
           */
          if (igmp->igmp_type != IGMP_DVMRP && ip->ip_ttl != 1) {
                  IGMPSTAT_INC(igps_rcv_badttl);
                  m_freem(m);
                  return;
          }
  
          switch (igmp->igmp_type) {
          case IGMP_HOST_MEMBERSHIP_QUERY:
                  if (igmplen == IGMP_MINLEN) {
                          if (igmp->igmp_code == 0)
                                  queryver = IGMP_VERSION_1;
                          else
                                  queryver = IGMP_VERSION_2;
                  } else if (igmplen >= IGMP_V3_QUERY_MINLEN) {
                          queryver = IGMP_VERSION_3;
                  } else {
                          IGMPSTAT_INC(igps_rcv_tooshort);
                          m_freem(m);
                          return;
                  }
  
                  switch (queryver) {
                  case IGMP_VERSION_1:
                          IGMPSTAT_INC(igps_rcv_v1v2_queries);
                          if (!V_igmp_v1enable)
                                  break;
                          if (igmp_input_v1_query(ifp, ip, igmp) != 0) {
                                  m_freem(m);
                                  return;
                          }
                          break;
  
                  case IGMP_VERSION_2:
                          IGMPSTAT_INC(igps_rcv_v1v2_queries);
                          if (!V_igmp_v2enable)
                                  break;
                          if (igmp_input_v2_query(ifp, ip, igmp) != 0) {
                                  m_freem(m);
                                  return;
                          }
                          break;
  
                  case IGMP_VERSION_3: {
                                  struct igmpv3 *igmpv3;
                                  uint16_t igmpv3len;
                                  uint16_t nsrc;
                                  int srclen;
  
                                  IGMPSTAT_INC(igps_rcv_v3_queries);
                                  igmpv3 = (struct igmpv3 *)igmp;
                                  /*
                                   * Validate length based on source count.
                                   */
                                  nsrc = ntohs(igmpv3->igmp_numsrc);
                                  srclen = sizeof(struct in_addr) * nsrc;
                                  if (nsrc * sizeof(in_addr_t) > srclen) {
                                          IGMPSTAT_INC(igps_rcv_tooshort);
                                          return;
                                  }
                                  /*
                                   * m_pullup() may modify m, so pullup in
                                   * this scope.
                                   */
                                  igmpv3len = iphlen + IGMP_V3_QUERY_MINLEN +
                                      srclen;
                                  if ((m->m_flags & M_EXT ||
                                       m->m_len < igmpv3len) &&
                                      (m = m_pullup(m, igmpv3len)) == NULL) {
                                          IGMPSTAT_INC(igps_rcv_tooshort);
                                          return;
                                  }
                                  igmpv3 = (struct igmpv3 *)(mtod(m, uint8_t *)
                                      + iphlen);
                                  if (igmp_input_v3_query(ifp, ip, igmpv3) != 0) {
                                          m_freem(m);
                                          return;
                                  }
                          }
                          break;
                  }
                  break;
  
          case IGMP_v1_HOST_MEMBERSHIP_REPORT:
                  if (!V_igmp_v1enable)
                          break;
                  if (igmp_input_v1_report(ifp, ip, igmp) != 0) {
                          m_freem(m);
                          return;
                  }
                  break;
  
          case IGMP_v2_HOST_MEMBERSHIP_REPORT:
                  if (!V_igmp_v2enable)
                          break;
                  if (!ip_checkrouteralert(m))
                          IGMPSTAT_INC(igps_rcv_nora);
                  if (igmp_input_v2_report(ifp, ip, igmp) != 0) {
                          m_freem(m);
                          return;
                  }
                  break;
  
          case IGMP_v3_HOST_MEMBERSHIP_REPORT:
                  /*
                   * Hosts do not need to process IGMPv3 membership reports,
                   * as report suppression is no longer required.
                   */
                  if (!ip_checkrouteralert(m))
                          IGMPSTAT_INC(igps_rcv_nora);
                  break;
  
          default:
                  break;
          }
  
          /*
           * Pass all valid IGMP packets up to any process(es) listening on a
           * raw IGMP socket.
           */
          rip_input(m, off);
  }
  
  
  /*
   * Fast timeout handler (global).
   * VIMAGE: Timeout handlers are expected to service all vimages.
   */
  void
  igmp_fasttimo(void)
  {
          VNET_ITERATOR_DECL(vnet_iter);
  
          VNET_LIST_RLOCK_NOSLEEP();
          VNET_FOREACH(vnet_iter) {
                  CURVNET_SET(vnet_iter);
                  igmp_fasttimo_vnet();
                  CURVNET_RESTORE();
          }
          VNET_LIST_RUNLOCK_NOSLEEP();
  }
  
  /*
   * Fast timeout handler (per-vnet).
   * Sends are shuffled off to a netisr to deal with Giant.
   *
   * VIMAGE: Assume caller has set up our curvnet.
   */
  static void
  igmp_fasttimo_vnet(void)
  {
          struct ifqueue           scq;   /* State-change packets */
          struct ifqueue           qrq;   /* Query response packets */
          struct ifnet            *ifp;
          struct igmp_ifinfo      *igi;
          struct ifmultiaddr      *ifma;
          struct in_multi         *inm;
          int                      loop, uri_fasthz;
  
          loop = 0;
          uri_fasthz = 0;
  
          /*
           * Quick check to see if any work needs to be done, in order to
           * minimize the overhead of fasttimo processing.
           * SMPng: XXX Unlocked reads.
           */
          if (!V_current_state_timers_running &&
              !V_interface_timers_running &&
              !V_state_change_timers_running)
                  return;
  
          IN_MULTI_LOCK();
          IGMP_LOCK();
  
          /*
           * IGMPv3 General Query response timer processing.
           */
          if (V_interface_timers_running) {
                  CTR1(KTR_IGMPV3, "%s: interface timers running", __func__);
  
                  V_interface_timers_running = 0;
                  LIST_FOREACH(igi, &V_igi_head, igi_link) {
                          if (igi->igi_v3_timer == 0) {
                                  /* Do nothing. */
                          } else if (--igi->igi_v3_timer == 0) {
                                  igmp_v3_dispatch_general_query(igi);
                          } else {
                                  V_interface_timers_running = 1;
                          }
                  }
          }
  
          if (!V_current_state_timers_running &&
              !V_state_change_timers_running)
                  goto out_locked;
  
          V_current_state_timers_running = 0;
          V_state_change_timers_running = 0;
  
          CTR1(KTR_IGMPV3, "%s: state change timers running", __func__);
  
          /*
           * IGMPv1/v2/v3 host report and state-change timer processing.
           * Note: Processing a v3 group timer may remove a node.
           */
          LIST_FOREACH(igi, &V_igi_head, igi_link) {
                  ifp = igi->igi_ifp;
  
                  if (igi->igi_version == IGMP_VERSION_3) {
                          loop = (igi->igi_flags & IGIF_LOOPBACK) ? 1 : 0;
                          uri_fasthz = IGMP_RANDOM_DELAY(igi->igi_uri *
                              PR_FASTHZ);
  
                          memset(&qrq, 0, sizeof(struct ifqueue));
                          IFQ_SET_MAXLEN(&qrq, IGMP_MAX_G_GS_PACKETS);
  
                          memset(&scq, 0, sizeof(struct ifqueue));
                          IFQ_SET_MAXLEN(&scq, IGMP_MAX_STATE_CHANGE_PACKETS);
                  }
  
                  IF_ADDR_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;
                          switch (igi->igi_version) {
                          case IGMP_VERSION_1:
                          case IGMP_VERSION_2:
                                  igmp_v1v2_process_group_timer(inm,
                                      igi->igi_version);
                                  break;
                          case IGMP_VERSION_3:
                                  igmp_v3_process_group_timers(igi, &qrq,
                                      &scq, inm, uri_fasthz);
                                  break;
                          }
                  }
                  IF_ADDR_RUNLOCK(ifp);
  
                  if (igi->igi_version == IGMP_VERSION_3) {
                          struct in_multi         *tinm;
  
                          igmp_dispatch_queue(&qrq, 0, loop);
                          igmp_dispatch_queue(&scq, 0, loop);
  
                          /*
                           * Free the in_multi reference(s) for this
                           * IGMP lifecycle.
                           */
                          SLIST_FOREACH_SAFE(inm, &igi->igi_relinmhead,
                              inm_nrele, tinm) {
                                  SLIST_REMOVE_HEAD(&igi->igi_relinmhead,
                                      inm_nrele);
                                  inm_release_locked(inm);
                          }
                  }
          }
  
  out_locked:
          IGMP_UNLOCK();
          IN_MULTI_UNLOCK();
  }
  
  /*
   * Update host report group timer for IGMPv1/v2.
   * Will update the global pending timer flags.
   */
  static void
  igmp_v1v2_process_group_timer(struct in_multi *inm, const int version)
  {
          int report_timer_expired;
  
          IN_MULTI_LOCK_ASSERT();
          IGMP_LOCK_ASSERT();
  
          if (inm->inm_timer == 0) {
                  report_timer_expired = 0;
          } else if (--inm->inm_timer == 0) {
                  report_timer_expired = 1;
          } else {
                  V_current_state_timers_running = 1;
                  return;
          }
  
          switch (inm->inm_state) {
          case IGMP_NOT_MEMBER:
          case IGMP_SILENT_MEMBER:
          case IGMP_IDLE_MEMBER:
          case IGMP_LAZY_MEMBER:
          case IGMP_SLEEPING_MEMBER:
          case IGMP_AWAKENING_MEMBER:
                  break;
          case IGMP_REPORTING_MEMBER:
                  if (report_timer_expired) {
                          inm->inm_state = IGMP_IDLE_MEMBER;
                          (void)igmp_v1v2_queue_report(inm,
                              (version == IGMP_VERSION_2) ?
                               IGMP_v2_HOST_MEMBERSHIP_REPORT :
                               IGMP_v1_HOST_MEMBERSHIP_REPORT);
                  }
                  break;
          case IGMP_G_QUERY_PENDING_MEMBER:
          case IGMP_SG_QUERY_PENDING_MEMBER:
          case IGMP_LEAVING_MEMBER:
                  break;
          }
  }
  
  /*
   * Update a group's timers for IGMPv3.
   * Will update the global pending timer flags.
   * Note: Unlocked read from igi.
   */
  static void
  igmp_v3_process_group_timers(struct igmp_ifinfo *igi,
      struct ifqueue *qrq, struct ifqueue *scq,
      struct in_multi *inm, const int uri_fasthz)
  {
          int query_response_timer_expired;
          int state_change_retransmit_timer_expired;
  
          IN_MULTI_LOCK_ASSERT();
          IGMP_LOCK_ASSERT();
  
          query_response_timer_expired = 0;
          state_change_retransmit_timer_expired = 0;
  
          /*
           * During a transition from v1/v2 compatibility mode back to v3,
           * a group record in REPORTING state may still have its group
           * timer active. This is a no-op in this function; it is easier
           * to deal with it here than to complicate the slow-timeout path.
           */
          if (inm->inm_timer == 0) {
                  query_response_timer_expired = 0;
          } else if (--inm->inm_timer == 0) {
                  query_response_timer_expired = 1;
          } else {
                  V_current_state_timers_running = 1;
          }
  
          if (inm->inm_sctimer == 0) {
                  state_change_retransmit_timer_expired = 0;
          } else if (--inm->inm_sctimer == 0) {
                  state_change_retransmit_timer_expired = 1;
          } else {
                  V_state_change_timers_running = 1;
          }
  
          /* We are in fasttimo, so be quick about it. */
          if (!state_change_retransmit_timer_expired &&
              !query_response_timer_expired)
                  return;
  
          switch (inm->inm_state) {
          case IGMP_NOT_MEMBER:
          case IGMP_SILENT_MEMBER:
          case IGMP_SLEEPING_MEMBER:
          case IGMP_LAZY_MEMBER:
          case IGMP_AWAKENING_MEMBER:
          case IGMP_IDLE_MEMBER:
                  break;
          case IGMP_G_QUERY_PENDING_MEMBER:
          case IGMP_SG_QUERY_PENDING_MEMBER:
                  /*
                   * Respond to a previously pending Group-Specific
                   * or Group-and-Source-Specific query by enqueueing
                   * the appropriate Current-State report for
                   * immediate transmission.
                   */
                  if (query_response_timer_expired) {
                          int retval;
  
                          retval = igmp_v3_enqueue_group_record(qrq, inm, 0, 1,
                              (inm->inm_state == IGMP_SG_QUERY_PENDING_MEMBER));
                          CTR2(KTR_IGMPV3, "%s: enqueue record = %d",
                              __func__, retval);
                          inm->inm_state = IGMP_REPORTING_MEMBER;
                          /* XXX Clear recorded sources for next time. */
                          inm_clear_recorded(inm);
                  }
                  /* FALLTHROUGH */
          case IGMP_REPORTING_MEMBER:
          case IGMP_LEAVING_MEMBER:
                  if (state_change_retransmit_timer_expired) {
                          /*
                           * State-change retransmission timer fired.
                           * If there are any further pending retransmissions,
                           * set the global pending state-change flag, and
                           * reset the timer.
                           */
                          if (--inm->inm_scrv > 0) {
                                  inm->inm_sctimer = uri_fasthz;
                                  V_state_change_timers_running = 1;
                          }
                          /*
                           * Retransmit the previously computed state-change
                           * report. If there are no further pending
                           * retransmissions, the mbuf queue will be consumed.
                           * Update T0 state to T1 as we have now sent
                           * a state-change.
                           */
                          (void)igmp_v3_merge_state_changes(inm, scq);
  
                          inm_commit(inm);
                          CTR3(KTR_IGMPV3, "%s: T1 -> T0 for %s/%s", __func__,
                              inet_ntoa(inm->inm_addr), inm->inm_ifp->if_xname);
  
                          /*
                           * If we are leaving the group for good, make sure
                           * we release IGMP's reference to it.
                           * This release must be deferred using a SLIST,
                           * as we are called from a loop which traverses
                           * the in_ifmultiaddr TAILQ.
                           */
                          if (inm->inm_state == IGMP_LEAVING_MEMBER &&
                              inm->inm_scrv == 0) {
                                  inm->inm_state = IGMP_NOT_MEMBER;
                                  SLIST_INSERT_HEAD(&igi->igi_relinmhead,
                                      inm, inm_nrele);
                          }
                  }
                  break;
          }
  }
  
  
  /*
   * Suppress a group's pending response to a group or source/group query.
   *
   * Do NOT suppress state changes. This leads to IGMPv3 inconsistency.
   * Do NOT update ST1/ST0 as this operation merely suppresses
   * the currently pending group record.
   * Do NOT suppress the response to a general query. It is possible but
   * it would require adding another state or flag.
   */
  static void
  igmp_v3_suppress_group_record(struct in_multi *inm)
  {
  
          IN_MULTI_LOCK_ASSERT();
  
          KASSERT(inm->inm_igi->igi_version == IGMP_VERSION_3,
                  ("%s: not IGMPv3 mode on link", __func__));
  
          if (inm->inm_state != IGMP_G_QUERY_PENDING_MEMBER ||
              inm->inm_state != IGMP_SG_QUERY_PENDING_MEMBER)
                  return;
  
          if (inm->inm_state == IGMP_SG_QUERY_PENDING_MEMBER)
                  inm_clear_recorded(inm);
  
          inm->inm_timer = 0;
          inm->inm_state = IGMP_REPORTING_MEMBER;
  }
  
  /*
   * Switch to a different IGMP version on the given interface,
   * as per Section 7.2.1.
   */
  static void
  igmp_set_version(struct igmp_ifinfo *igi, const int version)
  {
          int old_version_timer;
  
          IGMP_LOCK_ASSERT();
  
          CTR4(KTR_IGMPV3, "%s: switching to v%d on ifp %p(%s)", __func__,
              version, igi->igi_ifp, igi->igi_ifp->if_xname);
  
          if (version == IGMP_VERSION_1 || version == IGMP_VERSION_2) {
                  /*
                   * Compute the "Older Version Querier Present" timer as per
                   * Section 8.12.
                   */
                  old_version_timer = igi->igi_rv * igi->igi_qi + igi->igi_qri;
                  old_version_timer *= PR_SLOWHZ;
  
                  if (version == IGMP_VERSION_1) {
                          igi->igi_v1_timer = old_version_timer;
                          igi->igi_v2_timer = 0;
                  } else if (version == IGMP_VERSION_2) {
                          igi->igi_v1_timer = 0;
                          igi->igi_v2_timer = old_version_timer;
                  }
          }
  
          if (igi->igi_v1_timer == 0 && igi->igi_v2_timer > 0) {
                  if (igi->igi_version != IGMP_VERSION_2) {
                          igi->igi_version = IGMP_VERSION_2;
                          igmp_v3_cancel_link_timers(igi);
                  }
          } else if (igi->igi_v1_timer > 0) {
                  if (igi->igi_version != IGMP_VERSION_1) {
                          igi->igi_version = IGMP_VERSION_1;
                          igmp_v3_cancel_link_timers(igi);
                  }
          }
  }
  
  /*
   * Cancel pending IGMPv3 timers for the given link and all groups
   * joined on it; state-change, general-query, and group-query timers.
   *
   * Only ever called on a transition from v3 to Compatibility mode. Kill
   * the timers stone dead (this may be expensive for large N groups), they
   * will be restarted if Compatibility Mode deems that they must be due to
   * query processing.
   */
  static void
  igmp_v3_cancel_link_timers(struct igmp_ifinfo *igi)
  {
          struct ifmultiaddr      *ifma;
          struct ifnet            *ifp;
          struct in_multi         *inm, *tinm;
  
          CTR3(KTR_IGMPV3, "%s: cancel v3 timers on ifp %p(%s)", __func__,
              igi->igi_ifp, igi->igi_ifp->if_xname);
  
          IN_MULTI_LOCK_ASSERT();
          IGMP_LOCK_ASSERT();
  
          /*
           * Stop the v3 General Query Response on this link stone dead.
           * If fasttimo is woken up due to V_interface_timers_running,
           * the flag will be cleared if there are no pending link timers.
           */
          igi->igi_v3_timer = 0;
  
          /*
           * Now clear the current-state and state-change report timers
           * for all memberships scoped to this link.
           */
          ifp = igi->igi_ifp;
          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;
                  switch (inm->inm_state) {
                  case IGMP_NOT_MEMBER:
                  case IGMP_SILENT_MEMBER:
                  case IGMP_IDLE_MEMBER:
                  case IGMP_LAZY_MEMBER:
                  case IGMP_SLEEPING_MEMBER:
                  case IGMP_AWAKENING_MEMBER:
                          /*
                           * These states are either not relevant in v3 mode,
                           * or are unreported. Do nothing.
                           */
                          break;
                  case IGMP_LEAVING_MEMBER:
                          /*
                           * If we are leaving the group and switching to
                           * compatibility mode, we need to release the final
                           * reference held for issuing the INCLUDE {}, and
                           * transition to REPORTING to ensure the host leave
                           * message is sent upstream to the old querier --
                           * transition to NOT would lose the leave and race.
                           */
                          SLIST_INSERT_HEAD(&igi->igi_relinmhead, inm, inm_nrele);
                          /* FALLTHROUGH */
                  case IGMP_G_QUERY_PENDING_MEMBER:
                  case IGMP_SG_QUERY_PENDING_MEMBER:
                          inm_clear_recorded(inm);
                          /* FALLTHROUGH */
                  case IGMP_REPORTING_MEMBER:
                          inm->inm_state = IGMP_REPORTING_MEMBER;
                          break;
                  }
                  /*
                   * Always clear state-change and group report timers.
                   * Free any pending IGMPv3 state-change records.
                   */
                  inm->inm_sctimer = 0;
                  inm->inm_timer = 0;
                  _IF_DRAIN(&inm->inm_scq);
          }
          IF_ADDR_RUNLOCK(ifp);
          SLIST_FOREACH_SAFE(inm, &igi->igi_relinmhead, inm_nrele, tinm) {
                  SLIST_REMOVE_HEAD(&igi->igi_relinmhead, inm_nrele);
                  inm_release_locked(inm);
          }
  }
  
  /*
   * Update the Older Version Querier Present timers for a link.
   * See Section 7.2.1 of RFC 3376.
   */
  static void
  igmp_v1v2_process_querier_timers(struct igmp_ifinfo *igi)
  {
  
          IGMP_LOCK_ASSERT();
  
          if (igi->igi_v1_timer == 0 && igi->igi_v2_timer == 0) {
                  /*
                   * IGMPv1 and IGMPv2 Querier Present timers expired.
                   *
                   * Revert to IGMPv3.
                   */
                  if (igi->igi_version != IGMP_VERSION_3) {
                          CTR5(KTR_IGMPV3,
                              "%s: transition from v%d -> v%d on %p(%s)",
                              __func__, igi->igi_version, IGMP_VERSION_3,
                              igi->igi_ifp, igi->igi_ifp->if_xname);
                          igi->igi_version = IGMP_VERSION_3;
                  }
          } else if (igi->igi_v1_timer == 0 && igi->igi_v2_timer > 0) {
                  /*
                   * IGMPv1 Querier Present timer expired,
                   * IGMPv2 Querier Present timer running.
                   * If IGMPv2 was disabled since last timeout,
                   * revert to IGMPv3.
                   * If IGMPv2 is enabled, revert to IGMPv2.
                   */
                  if (!V_igmp_v2enable) {
                          CTR5(KTR_IGMPV3,
                              "%s: transition from v%d -> v%d on %p(%s)",
                              __func__, igi->igi_version, IGMP_VERSION_3,
                              igi->igi_ifp, igi->igi_ifp->if_xname);
                          igi->igi_v2_timer = 0;
                          igi->igi_version = IGMP_VERSION_3;
                  } else {
                          --igi->igi_v2_timer;
                          if (igi->igi_version != IGMP_VERSION_2) {
                                  CTR5(KTR_IGMPV3,
                                      "%s: transition from v%d -> v%d on %p(%s)",
                                      __func__, igi->igi_version, IGMP_VERSION_2,
                                      igi->igi_ifp, igi->igi_ifp->if_xname);
                                  igi->igi_version = IGMP_VERSION_2;
                                  igmp_v3_cancel_link_timers(igi);
                          }
                  }
          } else if (igi->igi_v1_timer > 0) {
                  /*
                   * IGMPv1 Querier Present timer running.
                   * Stop IGMPv2 timer if running.
                   *
                   * If IGMPv1 was disabled since last timeout,
                   * revert to IGMPv3.
                   * If IGMPv1 is enabled, reset IGMPv2 timer if running.
                   */
                  if (!V_igmp_v1enable) {
                          CTR5(KTR_IGMPV3,
                              "%s: transition from v%d -> v%d on %p(%s)",
                              __func__, igi->igi_version, IGMP_VERSION_3,
                              igi->igi_ifp, igi->igi_ifp->if_xname);
                          igi->igi_v1_timer = 0;
                          igi->igi_version = IGMP_VERSION_3;
                  } else {
                          --igi->igi_v1_timer;
                  }
                  if (igi->igi_v2_timer > 0) {
                          CTR3(KTR_IGMPV3,
                              "%s: cancel v2 timer on %p(%s)",
                              __func__, igi->igi_ifp, igi->igi_ifp->if_xname);
                          igi->igi_v2_timer = 0;
                  }
          }
  }
  
  /*
   * Global slowtimo handler.
   * VIMAGE: Timeout handlers are expected to service all vimages.
   */
  void
  igmp_slowtimo(void)
  {
          VNET_ITERATOR_DECL(vnet_iter);
  
          VNET_LIST_RLOCK_NOSLEEP();
          VNET_FOREACH(vnet_iter) {
                  CURVNET_SET(vnet_iter);
                  igmp_slowtimo_vnet();
                  CURVNET_RESTORE();
          }
          VNET_LIST_RUNLOCK_NOSLEEP();
  }
  
  /*
   * Per-vnet slowtimo handler.
   */
  static void
  igmp_slowtimo_vnet(void)
  {
          struct igmp_ifinfo *igi;
  
          IGMP_LOCK();
  
          LIST_FOREACH(igi, &V_igi_head, igi_link) {
                  igmp_v1v2_process_querier_timers(igi);
          }
  
          IGMP_UNLOCK();
  }
  
  /*
   * Dispatch an IGMPv1/v2 host report or leave message.
   * These are always small enough to fit inside a single mbuf.
   */
  static int
  igmp_v1v2_queue_report(struct in_multi *inm, const int type)
  {
          struct ifnet            *ifp;
          struct igmp             *igmp;
          struct ip               *ip;
          struct mbuf             *m;
  
          IN_MULTI_LOCK_ASSERT();
          IGMP_LOCK_ASSERT();
  
          ifp = inm->inm_ifp;
  
          m = m_gethdr(M_NOWAIT, MT_DATA);
          if (m == NULL)
                  return (ENOMEM);
          MH_ALIGN(m, sizeof(struct ip) + sizeof(struct igmp));
  
          m->m_pkthdr.len = sizeof(struct ip) + sizeof(struct igmp);
  
          m->m_data += sizeof(struct ip);
          m->m_len = sizeof(struct igmp);
  
          igmp = mtod(m, struct igmp *);
          igmp->igmp_type = type;
          igmp->igmp_code = 0;
          igmp->igmp_group = inm->inm_addr;
          igmp->igmp_cksum = 0;
          igmp->igmp_cksum = in_cksum(m, sizeof(struct igmp));
  
          m->m_data -= sizeof(struct ip);
          m->m_len += sizeof(struct ip);
  
          ip = mtod(m, struct ip *);
          ip->ip_tos = 0;
          ip->ip_len = htons(sizeof(struct ip) + sizeof(struct igmp));
          ip->ip_off = 0;
          ip->ip_p = IPPROTO_IGMP;
          ip->ip_src.s_addr = INADDR_ANY;
  
          if (type == IGMP_HOST_LEAVE_MESSAGE)
                  ip->ip_dst.s_addr = htonl(INADDR_ALLRTRS_GROUP);
          else
                  ip->ip_dst = inm->inm_addr;
  
          igmp_save_context(m, ifp);
  
          m->m_flags |= M_IGMPV2;
          if (inm->inm_igi->igi_flags & IGIF_LOOPBACK)
                  m->m_flags |= M_IGMP_LOOP;
  
          CTR2(KTR_IGMPV3, "%s: netisr_dispatch(NETISR_IGMP, %p)", __func__, m);
          netisr_dispatch(NETISR_IGMP, m);
  
          return (0);
  }
  
  /*
   * Process a state change from the upper layer for the given IPv4 group.
   *
   * Each socket holds a reference on the in_multi in its own ip_moptions.
   * The socket layer will have made the necessary updates to.the group
   * state, it is now up to IGMP to issue a state change report if there
   * has been any change between T0 (when the last state-change was issued)
   * and T1 (now).
   *
   * We use the IGMPv3 state machine at group level. The IGMP module
   * however makes the decision as to which IGMP protocol version to speak.
   * A state change *from* INCLUDE {} always means an initial join.
   * A state change *to* INCLUDE {} always means a final leave.
   *
   * FUTURE: If IGIF_V3LITE is enabled for this interface, then we can
   * save ourselves a bunch of work; any exclusive mode groups need not
   * compute source filter lists.
   *
   * VIMAGE: curvnet should have been set by caller, as this routine
   * is called from the socket option handlers.
   */
  int
  igmp_change_state(struct in_multi *inm)
  {
          struct igmp_ifinfo *igi;
          struct ifnet *ifp;
          int error;
  
          IN_MULTI_LOCK_ASSERT();
  
          error = 0;
  
          /*
           * Try to detect if the upper layer just asked us to change state
           * for an interface which has now gone away.
           */
          KASSERT(inm->inm_ifma != NULL, ("%s: no ifma", __func__));
          ifp = inm->inm_ifma->ifma_ifp;
          /*
           * Sanity check that netinet's notion of ifp is the
           * same as net's.
           */
          KASSERT(inm->inm_ifp == ifp, ("%s: bad ifp", __func__));
  
          IGMP_LOCK();
  
          igi = ((struct in_ifinfo *)ifp->if_afdata[AF_INET])->ii_igmp;
          KASSERT(igi != NULL, ("%s: no igmp_ifinfo for ifp %p", __func__, ifp));
  
          /*
           * If we detect a state transition to or from MCAST_UNDEFINED
           * for this group, then we are starting or finishing an IGMP
           * life cycle for this group.
           */
          if (inm->inm_st[1].iss_fmode != inm->inm_st[0].iss_fmode) {
                  CTR3(KTR_IGMPV3, "%s: inm transition %d -> %d", __func__,
                      inm->inm_st[0].iss_fmode, inm->inm_st[1].iss_fmode);
                  if (inm->inm_st[0].iss_fmode == MCAST_UNDEFINED) {
                          CTR1(KTR_IGMPV3, "%s: initial join", __func__);
                          error = igmp_initial_join(inm, igi);
                          goto out_locked;
                  } else if (inm->inm_st[1].iss_fmode == MCAST_UNDEFINED) {
                          CTR1(KTR_IGMPV3, "%s: final leave", __func__);
                          igmp_final_leave(inm, igi);
                          goto out_locked;
                  }
          } else {
                  CTR1(KTR_IGMPV3, "%s: filter set change", __func__);
          }
  
          error = igmp_handle_state_change(inm, igi);
  
  out_locked:
          IGMP_UNLOCK();
          return (error);
  }
  
  /*
   * Perform the initial join for an IGMP group.
   *
   * When joining a group:
   *  If the group should have its IGMP traffic suppressed, do nothing.
   *  IGMPv1 starts sending IGMPv1 host membership reports.
   *  IGMPv2 starts sending IGMPv2 host membership reports.
   *  IGMPv3 will schedule an IGMPv3 state-change report containing the
   *  initial state of the membership.
   */
  static int
  igmp_initial_join(struct in_multi *inm, struct igmp_ifinfo *igi)
  {
          struct ifnet            *ifp;
          struct ifqueue          *ifq;
          int                      error, retval, syncstates;
  
          CTR4(KTR_IGMPV3, "%s: initial join %s on ifp %p(%s)",
              __func__, inet_ntoa(inm->inm_addr), inm->inm_ifp,
              inm->inm_ifp->if_xname);
  
          error = 0;
          syncstates = 1;
  
          ifp = inm->inm_ifp;
  
          IN_MULTI_LOCK_ASSERT();
          IGMP_LOCK_ASSERT();
  
          KASSERT(igi && igi->igi_ifp == ifp, ("%s: inconsistent ifp", __func__));
  
          /*
           * Groups joined on loopback or marked as 'not reported',
           * e.g. 224.0.0.1, enter the IGMP_SILENT_MEMBER state and
           * are never reported in any IGMP protocol exchanges.
           * All other groups enter the appropriate IGMP state machine
           * for the version in use on this link.
           * A link marked as IGIF_SILENT causes IGMP to be completely
           * disabled for the link.
           */
          if ((ifp->if_flags & IFF_LOOPBACK) ||
              (igi->igi_flags & IGIF_SILENT) ||
              !igmp_isgroupreported(inm->inm_addr)) {
                  CTR1(KTR_IGMPV3,
  "%s: not kicking state machine for silent group", __func__);
                  inm->inm_state = IGMP_SILENT_MEMBER;
                  inm->inm_timer = 0;
          } else {
                  /*
                   * Deal with overlapping in_multi lifecycle.
                   * If this group was LEAVING, then make sure
                   * we drop the reference we picked up to keep the
                   * group around for the final INCLUDE {} enqueue.
                   */
                  if (igi->igi_version == IGMP_VERSION_3 &&
                      inm->inm_state == IGMP_LEAVING_MEMBER)
                          inm_release_locked(inm);
  
                  inm->inm_state = IGMP_REPORTING_MEMBER;
  
                  switch (igi->igi_version) {
                  case IGMP_VERSION_1:
                  case IGMP_VERSION_2:
                          inm->inm_state = IGMP_IDLE_MEMBER;
                          error = igmp_v1v2_queue_report(inm,
                              (igi->igi_version == IGMP_VERSION_2) ?
                               IGMP_v2_HOST_MEMBERSHIP_REPORT :
                               IGMP_v1_HOST_MEMBERSHIP_REPORT);
                          if (error == 0) {
                                  inm->inm_timer = IGMP_RANDOM_DELAY(
                                      IGMP_V1V2_MAX_RI * PR_FASTHZ);
                                  V_current_state_timers_running = 1;
                          }
                          break;
  
                  case IGMP_VERSION_3:
                          /*
                           * Defer update of T0 to T1, until the first copy
                           * of the state change has been transmitted.
                           */
                          syncstates = 0;
  
                          /*
                           * Immediately enqueue a State-Change Report for
                           * this interface, freeing any previous reports.
                           * Don't kick the timers if there is nothing to do,
                           * or if an error occurred.
                           */
                          ifq = &inm->inm_scq;
                          _IF_DRAIN(ifq);
                          retval = igmp_v3_enqueue_group_record(ifq, inm, 1,
                              0, 0);
                          CTR2(KTR_IGMPV3, "%s: enqueue record = %d",
                              __func__, retval);
                          if (retval <= 0) {
                                  error = retval * -1;
                                  break;
                          }
  
                          /*
                           * Schedule transmission of pending state-change
                           * report up to RV times for this link. The timer
                           * will fire at the next igmp_fasttimo (~200ms),
                           * giving us an opportunity to merge the reports.
                           */
                          if (igi->igi_flags & IGIF_LOOPBACK) {
                                  inm->inm_scrv = 1;
                          } else {
                                  KASSERT(igi->igi_rv > 1,
                                     ("%s: invalid robustness %d", __func__,
                                      igi->igi_rv));
                                  inm->inm_scrv = igi->igi_rv;
                          }
                          inm->inm_sctimer = 1;
                          V_state_change_timers_running = 1;
  
                          error = 0;
                          break;
                  }
          }
  
          /*
           * Only update the T0 state if state change is atomic,
           * i.e. we don't need to wait for a timer to fire before we
           * can consider the state change to have been communicated.
           */
          if (syncstates) {
                  inm_commit(inm);
                  CTR3(KTR_IGMPV3, "%s: T1 -> T0 for %s/%s", __func__,
                      inet_ntoa(inm->inm_addr), inm->inm_ifp->if_xname);
          }
  
          return (error);
  }
  
  /*
   * Issue an intermediate state change during the IGMP life-cycle.
   */
  static int
  igmp_handle_state_change(struct in_multi *inm, struct igmp_ifinfo *igi)
  {
          struct ifnet            *ifp;
          int                      retval;
  
          CTR4(KTR_IGMPV3, "%s: state change for %s on ifp %p(%s)",
              __func__, inet_ntoa(inm->inm_addr), inm->inm_ifp,
              inm->inm_ifp->if_xname);
  
          ifp = inm->inm_ifp;
  
          IN_MULTI_LOCK_ASSERT();
          IGMP_LOCK_ASSERT();
  
          KASSERT(igi && igi->igi_ifp == ifp, ("%s: inconsistent ifp", __func__));
  
          if ((ifp->if_flags & IFF_LOOPBACK) ||
              (igi->igi_flags & IGIF_SILENT) ||
              !igmp_isgroupreported(inm->inm_addr) ||
              (igi->igi_version != IGMP_VERSION_3)) {
                  if (!igmp_isgroupreported(inm->inm_addr)) {
                          CTR1(KTR_IGMPV3,
  "%s: not kicking state machine for silent group", __func__);
                  }
                  CTR1(KTR_IGMPV3, "%s: nothing to do", __func__);
                  inm_commit(inm);
                  CTR3(KTR_IGMPV3, "%s: T1 -> T0 for %s/%s", __func__,
                      inet_ntoa(inm->inm_addr), inm->inm_ifp->if_xname);
                  return (0);
          }
  
          _IF_DRAIN(&inm->inm_scq);
  
          retval = igmp_v3_enqueue_group_record(&inm->inm_scq, inm, 1, 0, 0);
          CTR2(KTR_IGMPV3, "%s: enqueue record = %d", __func__, retval);
          if (retval <= 0)
                  return (-retval);
  
          /*
           * If record(s) were enqueued, start the state-change
           * report timer for this group.
           */
          inm->inm_scrv = ((igi->igi_flags & IGIF_LOOPBACK) ? 1 : igi->igi_rv);
          inm->inm_sctimer = 1;
          V_state_change_timers_running = 1;
  
          return (0);
  }
  
  /*
   * Perform the final leave for an IGMP group.
   *
   * When leaving a group:
   *  IGMPv1 does nothing.
   *  IGMPv2 sends a host leave message, if and only if we are the reporter.
   *  IGMPv3 enqueues a state-change report containing a transition
   *  to INCLUDE {} for immediate transmission.
   */
  static void
  igmp_final_leave(struct in_multi *inm, struct igmp_ifinfo *igi)
  {
          int syncstates;
  
          syncstates = 1;
  
          CTR4(KTR_IGMPV3, "%s: final leave %s on ifp %p(%s)",
              __func__, inet_ntoa(inm->inm_addr), inm->inm_ifp,
              inm->inm_ifp->if_xname);
  
          IN_MULTI_LOCK_ASSERT();
          IGMP_LOCK_ASSERT();
  
          switch (inm->inm_state) {
          case IGMP_NOT_MEMBER:
          case IGMP_SILENT_MEMBER:
          case IGMP_LEAVING_MEMBER:
                  /* Already leaving or left; do nothing. */
                  CTR1(KTR_IGMPV3,
  "%s: not kicking state machine for silent group", __func__);
                  break;
          case IGMP_REPORTING_MEMBER:
          case IGMP_IDLE_MEMBER:
          case IGMP_G_QUERY_PENDING_MEMBER:
          case IGMP_SG_QUERY_PENDING_MEMBER:
                  if (igi->igi_version == IGMP_VERSION_2) {
  #ifdef INVARIANTS
                          if (inm->inm_state == IGMP_G_QUERY_PENDING_MEMBER ||
                              inm->inm_state == IGMP_SG_QUERY_PENDING_MEMBER)
                          panic("%s: IGMPv3 state reached, not IGMPv3 mode",
                               __func__);
  #endif
                          igmp_v1v2_queue_report(inm, IGMP_HOST_LEAVE_MESSAGE);
                          inm->inm_state = IGMP_NOT_MEMBER;
                  } else if (igi->igi_version == IGMP_VERSION_3) {
                          /*
                           * Stop group timer and all pending reports.
                           * Immediately enqueue a state-change report
                           * TO_IN {} to be sent on the next fast timeout,
                           * giving us an opportunity to merge reports.
                           */
                          _IF_DRAIN(&inm->inm_scq);
                          inm->inm_timer = 0;
                          if (igi->igi_flags & IGIF_LOOPBACK) {
                                  inm->inm_scrv = 1;
                          } else {
                                  inm->inm_scrv = igi->igi_rv;
                          }
                          CTR4(KTR_IGMPV3, "%s: Leaving %s/%s with %d "
                              "pending retransmissions.", __func__,
                              inet_ntoa(inm->inm_addr),
                              inm->inm_ifp->if_xname, inm->inm_scrv);
                          if (inm->inm_scrv == 0) {
                                  inm->inm_state = IGMP_NOT_MEMBER;
                                  inm->inm_sctimer = 0;
                          } else {
                                  int retval;
  
                                  inm_acquire_locked(inm);
  
                                  retval = igmp_v3_enqueue_group_record(
                                      &inm->inm_scq, inm, 1, 0, 0);
                                  KASSERT(retval != 0,
                                      ("%s: enqueue record = %d", __func__,
                                       retval));
  
                                  inm->inm_state = IGMP_LEAVING_MEMBER;
                                  inm->inm_sctimer = 1;
                                  V_state_change_timers_running = 1;
                                  syncstates = 0;
                          }
                          break;
                  }
                  break;
          case IGMP_LAZY_MEMBER:
          case IGMP_SLEEPING_MEMBER:
          case IGMP_AWAKENING_MEMBER:
                  /* Our reports are suppressed; do nothing. */
                  break;
          }
  
          if (syncstates) {
                  inm_commit(inm);
                  CTR3(KTR_IGMPV3, "%s: T1 -> T0 for %s/%s", __func__,
                      inet_ntoa(inm->inm_addr), inm->inm_ifp->if_xname);
                  inm->inm_st[1].iss_fmode = MCAST_UNDEFINED;
                  CTR3(KTR_IGMPV3, "%s: T1 now MCAST_UNDEFINED for %s/%s",
                      __func__, inet_ntoa(inm->inm_addr), inm->inm_ifp->if_xname);
          }
  }
  
  /*
   * Enqueue an IGMPv3 group record to the given output queue.
   *
   * XXX This function could do with having the allocation code
   * split out, and the multiple-tree-walks coalesced into a single
   * routine as has been done in igmp_v3_enqueue_filter_change().
   *
   * If is_state_change is zero, a current-state record is appended.
   * If is_state_change is non-zero, a state-change report is appended.
   *
   * If is_group_query is non-zero, an mbuf packet chain is allocated.
   * If is_group_query is zero, and if there is a packet with free space
   * at the tail of the queue, it will be appended to providing there
   * is enough free space.
   * Otherwise a new mbuf packet chain is allocated.
   *
   * If is_source_query is non-zero, each source is checked to see if
   * it was recorded for a Group-Source query, and will be omitted if
   * it is not both in-mode and recorded.
   *
   * The function will attempt to allocate leading space in the packet
   * for the IP/IGMP header to be prepended without fragmenting the chain.
   *
   * If successful the size of all data appended to the queue is returned,
   * otherwise an error code less than zero is returned, or zero if
   * no record(s) were appended.
   */
  static int
  igmp_v3_enqueue_group_record(struct ifqueue *ifq, struct in_multi *inm,
      const int is_state_change, const int is_group_query,
      const int is_source_query)
  {
          struct igmp_grouprec     ig;
          struct igmp_grouprec    *pig;
          struct ifnet            *ifp;
          struct ip_msource       *ims, *nims;
          struct mbuf             *m0, *m, *md;
          int                      error, is_filter_list_change;
          int                      minrec0len, m0srcs, msrcs, nbytes, off;
          int                      record_has_sources;
          int                      now;
          int                      type;
          in_addr_t                naddr;
          uint8_t                  mode;
  
          IN_MULTI_LOCK_ASSERT();
  
          error = 0;
          ifp = inm->inm_ifp;
          is_filter_list_change = 0;
          m = NULL;
          m0 = NULL;
          m0srcs = 0;
          msrcs = 0;
          nbytes = 0;
          nims = NULL;
          record_has_sources = 1;
          pig = NULL;
          type = IGMP_DO_NOTHING;
          mode = inm->inm_st[1].iss_fmode;
  
          /*
           * If we did not transition out of ASM mode during t0->t1,
           * and there are no source nodes to process, we can skip
           * the generation of source records.
           */
          if (inm->inm_st[0].iss_asm > 0 && inm->inm_st[1].iss_asm > 0 &&
              inm->inm_nsrc == 0)
                  record_has_sources = 0;
  
          if (is_state_change) {
                  /*
                   * Queue a state change record.
                   * If the mode did not change, and there are non-ASM
                   * listeners or source filters present,
                   * we potentially need to issue two records for the group.
                   * If we are transitioning to MCAST_UNDEFINED, we need
                   * not send any sources.
                   * If there are ASM listeners, and there was no filter
                   * mode transition of any kind, do nothing.
                   */
                  if (mode != inm->inm_st[0].iss_fmode) {
                          if (mode == MCAST_EXCLUDE) {
                                  CTR1(KTR_IGMPV3, "%s: change to EXCLUDE",
                                      __func__);
                                  type = IGMP_CHANGE_TO_EXCLUDE_MODE;
                          } else {
                                  CTR1(KTR_IGMPV3, "%s: change to INCLUDE",
                                      __func__);
                                  type = IGMP_CHANGE_TO_INCLUDE_MODE;
                                  if (mode == MCAST_UNDEFINED)
                                          record_has_sources = 0;
                          }
                  } else {
                          if (record_has_sources) {
                                  is_filter_list_change = 1;
                          } else {
                                  type = IGMP_DO_NOTHING;
                          }
                  }
          } else {
                  /*
                   * Queue a current state record.
                   */
                  if (mode == MCAST_EXCLUDE) {
                          type = IGMP_MODE_IS_EXCLUDE;
                  } else if (mode == MCAST_INCLUDE) {
                          type = IGMP_MODE_IS_INCLUDE;
                          KASSERT(inm->inm_st[1].iss_asm == 0,
                              ("%s: inm %p is INCLUDE but ASM count is %d",
                               __func__, inm, inm->inm_st[1].iss_asm));
                  }
          }
  
          /*
           * Generate the filter list changes using a separate function.
           */
          if (is_filter_list_change)
                  return (igmp_v3_enqueue_filter_change(ifq, inm));
  
          if (type == IGMP_DO_NOTHING) {
                  CTR3(KTR_IGMPV3, "%s: nothing to do for %s/%s",
                      __func__, inet_ntoa(inm->inm_addr),
                      inm->inm_ifp->if_xname);
                  return (0);
          }
  
          /*
           * If any sources are present, we must be able to fit at least
           * one in the trailing space of the tail packet's mbuf,
           * ideally more.
           */
          minrec0len = sizeof(struct igmp_grouprec);
          if (record_has_sources)
                  minrec0len += sizeof(in_addr_t);
  
          CTR4(KTR_IGMPV3, "%s: queueing %s for %s/%s", __func__,
              igmp_rec_type_to_str(type), inet_ntoa(inm->inm_addr),
              inm->inm_ifp->if_xname);
  
          /*
           * Check if we have a packet in the tail of the queue for this
           * group into which the first group record for this group will fit.
           * Otherwise allocate a new packet.
           * Always allocate leading space for IP+RA_OPT+IGMP+REPORT.
           * Note: Group records for G/GSR query responses MUST be sent
           * in their own packet.
           */
          m0 = ifq->ifq_tail;
          if (!is_group_query &&
              m0 != NULL &&
              (m0->m_pkthdr.PH_vt.vt_nrecs + 1 <= IGMP_V3_REPORT_MAXRECS) &&
              (m0->m_pkthdr.len + minrec0len) <
               (ifp->if_mtu - IGMP_LEADINGSPACE)) {
                  m0srcs = (ifp->if_mtu - m0->m_pkthdr.len -
                              sizeof(struct igmp_grouprec)) / sizeof(in_addr_t);
                  m = m0;
                  CTR1(KTR_IGMPV3, "%s: use existing packet", __func__);
          } else {
                  if (_IF_QFULL(ifq)) {
                          CTR1(KTR_IGMPV3, "%s: outbound queue full", __func__);
                          return (-ENOMEM);
                  }
                  m = NULL;
                  m0srcs = (ifp->if_mtu - IGMP_LEADINGSPACE -
                      sizeof(struct igmp_grouprec)) / sizeof(in_addr_t);
                  if (!is_state_change && !is_group_query) {
                          m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
                          if (m)
                                  m->m_data += IGMP_LEADINGSPACE;
                  }
                  if (m == NULL) {
                          m = m_gethdr(M_NOWAIT, MT_DATA);
                          if (m)
                                  MH_ALIGN(m, IGMP_LEADINGSPACE);
                  }
                  if (m == NULL)
                          return (-ENOMEM);
  
                  igmp_save_context(m, ifp);
  
                  CTR1(KTR_IGMPV3, "%s: allocated first packet", __func__);
          }
  
          /*
           * Append group record.
           * If we have sources, we don't know how many yet.
           */
          ig.ig_type = type;
          ig.ig_datalen = 0;
          ig.ig_numsrc = 0;
          ig.ig_group = inm->inm_addr;
          if (!m_append(m, sizeof(struct igmp_grouprec), (void *)&ig)) {
                  if (m != m0)
                          m_freem(m);
                  CTR1(KTR_IGMPV3, "%s: m_append() failed.", __func__);
                  return (-ENOMEM);
          }
          nbytes += sizeof(struct igmp_grouprec);
  
          /*
           * Append as many sources as will fit in the first packet.
           * If we are appending to a new packet, the chain allocation
           * may potentially use clusters; use m_getptr() in this case.
           * If we are appending to an existing packet, we need to obtain
           * a pointer to the group record after m_append(), in case a new
           * mbuf was allocated.
           * Only append sources which are in-mode at t1. If we are
           * transitioning to MCAST_UNDEFINED state on the group, do not
           * include source entries.
           * Only report recorded sources in our filter set when responding
           * to a group-source query.
           */
          if (record_has_sources) {
                  if (m == m0) {
                          md = m_last(m);
                          pig = (struct igmp_grouprec *)(mtod(md, uint8_t *) +
                              md->m_len - nbytes);
                  } else {
                          md = m_getptr(m, 0, &off);
                          pig = (struct igmp_grouprec *)(mtod(md, uint8_t *) +
                              off);
                  }
                  msrcs = 0;
                  RB_FOREACH_SAFE(ims, ip_msource_tree, &inm->inm_srcs, nims) {
                          CTR2(KTR_IGMPV3, "%s: visit node %s", __func__,
                              inet_ntoa_haddr(ims->ims_haddr));
                          now = ims_get_mode(inm, ims, 1);
                          CTR2(KTR_IGMPV3, "%s: node is %d", __func__, now);
                          if ((now != mode) ||
                              (now == mode && mode == MCAST_UNDEFINED)) {
                                  CTR1(KTR_IGMPV3, "%s: skip node", __func__);
                                  continue;
                          }
                          if (is_source_query && ims->ims_stp == 0) {
                                  CTR1(KTR_IGMPV3, "%s: skip unrecorded node",
                                      __func__);
                                  continue;
                          }
                          CTR1(KTR_IGMPV3, "%s: append node", __func__);
                          naddr = htonl(ims->ims_haddr);
                          if (!m_append(m, sizeof(in_addr_t), (void *)&naddr)) {
                                  if (m != m0)
                                          m_freem(m);
                                  CTR1(KTR_IGMPV3, "%s: m_append() failed.",
                                      __func__);
                                  return (-ENOMEM);
                          }
                          nbytes += sizeof(in_addr_t);
                          ++msrcs;
                          if (msrcs == m0srcs)
                                  break;
                  }
                  CTR2(KTR_IGMPV3, "%s: msrcs is %d this packet", __func__,
                      msrcs);
                  pig->ig_numsrc = htons(msrcs);
                  nbytes += (msrcs * sizeof(in_addr_t));
          }
  
          if (is_source_query && msrcs == 0) {
                  CTR1(KTR_IGMPV3, "%s: no recorded sources to report", __func__);
                  if (m != m0)
                          m_freem(m);
                  return (0);
          }
  
          /*
           * We are good to go with first packet.
           */
          if (m != m0) {
                  CTR1(KTR_IGMPV3, "%s: enqueueing first packet", __func__);
                  m->m_pkthdr.PH_vt.vt_nrecs = 1;
                  _IF_ENQUEUE(ifq, m);
          } else
                  m->m_pkthdr.PH_vt.vt_nrecs++;
  
          /*
           * No further work needed if no source list in packet(s).
           */
          if (!record_has_sources)
                  return (nbytes);
  
          /*
           * Whilst sources remain to be announced, we need to allocate
           * a new packet and fill out as many sources as will fit.
           * Always try for a cluster first.
           */
          while (nims != NULL) {
                  if (_IF_QFULL(ifq)) {
                          CTR1(KTR_IGMPV3, "%s: outbound queue full", __func__);
                          return (-ENOMEM);
                  }
                  m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
                  if (m)
                          m->m_data += IGMP_LEADINGSPACE;
                  if (m == NULL) {
                          m = m_gethdr(M_NOWAIT, MT_DATA);
                          if (m)
                                  MH_ALIGN(m, IGMP_LEADINGSPACE);
                  }
                  if (m == NULL)
                          return (-ENOMEM);
                  igmp_save_context(m, ifp);
                  md = m_getptr(m, 0, &off);
                  pig = (struct igmp_grouprec *)(mtod(md, uint8_t *) + off);
                  CTR1(KTR_IGMPV3, "%s: allocated next packet", __func__);
  
                  if (!m_append(m, sizeof(struct igmp_grouprec), (void *)&ig)) {
                          if (m != m0)
                                  m_freem(m);
                          CTR1(KTR_IGMPV3, "%s: m_append() failed.", __func__);
                          return (-ENOMEM);
                  }
                  m->m_pkthdr.PH_vt.vt_nrecs = 1;
                  nbytes += sizeof(struct igmp_grouprec);
  
                  m0srcs = (ifp->if_mtu - IGMP_LEADINGSPACE -
                      sizeof(struct igmp_grouprec)) / sizeof(in_addr_t);
  
                  msrcs = 0;
                  RB_FOREACH_FROM(ims, ip_msource_tree, nims) {
                          CTR2(KTR_IGMPV3, "%s: visit node %s", __func__,
                              inet_ntoa_haddr(ims->ims_haddr));
                          now = ims_get_mode(inm, ims, 1);
                          if ((now != mode) ||
                              (now == mode && mode == MCAST_UNDEFINED)) {
                                  CTR1(KTR_IGMPV3, "%s: skip node", __func__);
                                  continue;
                          }
                          if (is_source_query && ims->ims_stp == 0) {
                                  CTR1(KTR_IGMPV3, "%s: skip unrecorded node",
                                      __func__);
                                  continue;
                          }
                          CTR1(KTR_IGMPV3, "%s: append node", __func__);
                          naddr = htonl(ims->ims_haddr);
                          if (!m_append(m, sizeof(in_addr_t), (void *)&naddr)) {
                                  if (m != m0)
                                          m_freem(m);
                                  CTR1(KTR_IGMPV3, "%s: m_append() failed.",
                                      __func__);
                                  return (-ENOMEM);
                          }
                          ++msrcs;
                          if (msrcs == m0srcs)
                                  break;
                  }
                  pig->ig_numsrc = htons(msrcs);
                  nbytes += (msrcs * sizeof(in_addr_t));
  
                  CTR1(KTR_IGMPV3, "%s: enqueueing next packet", __func__);
                  _IF_ENQUEUE(ifq, m);
          }
  
          return (nbytes);
  }
  
  /*
   * Type used to mark record pass completion.
   * We exploit the fact we can cast to this easily from the
   * current filter modes on each ip_msource node.
   */
  typedef enum {
          REC_NONE = 0x00,        /* MCAST_UNDEFINED */
          REC_ALLOW = 0x01,       /* MCAST_INCLUDE */
          REC_BLOCK = 0x02,       /* MCAST_EXCLUDE */
          REC_FULL = REC_ALLOW | REC_BLOCK
  } rectype_t;
  
  /*
   * Enqueue an IGMPv3 filter list change to the given output queue.
   *
   * Source list filter state is held in an RB-tree. When the filter list
   * for a group is changed without changing its mode, we need to compute
   * the deltas between T0 and T1 for each source in the filter set,
   * and enqueue the appropriate ALLOW_NEW/BLOCK_OLD records.
   *
   * As we may potentially queue two record types, and the entire R-B tree
   * needs to be walked at once, we break this out into its own function
   * so we can generate a tightly packed queue of packets.
   *
   * XXX This could be written to only use one tree walk, although that makes
   * serializing into the mbuf chains a bit harder. For now we do two walks
   * which makes things easier on us, and it may or may not be harder on
   * the L2 cache.
   *
   * If successful the size of all data appended to the queue is returned,
   * otherwise an error code less than zero is returned, or zero if
   * no record(s) were appended.
   */
  static int
  igmp_v3_enqueue_filter_change(struct ifqueue *ifq, struct in_multi *inm)
  {
          static const int MINRECLEN =
              sizeof(struct igmp_grouprec) + sizeof(in_addr_t);
          struct ifnet            *ifp;
          struct igmp_grouprec     ig;
          struct igmp_grouprec    *pig;
          struct ip_msource       *ims, *nims;
          struct mbuf             *m, *m0, *md;
          in_addr_t                naddr;
          int                      m0srcs, nbytes, npbytes, off, rsrcs, schanged;
          int                      nallow, nblock;
          uint8_t                  mode, now, then;
          rectype_t                crt, drt, nrt;
  
          IN_MULTI_LOCK_ASSERT();
  
          if (inm->inm_nsrc == 0 ||
              (inm->inm_st[0].iss_asm > 0 && inm->inm_st[1].iss_asm > 0))
                  return (0);
  
          ifp = inm->inm_ifp;                     /* interface */
          mode = inm->inm_st[1].iss_fmode;        /* filter mode at t1 */
          crt = REC_NONE; /* current group record type */
          drt = REC_NONE; /* mask of completed group record types */
          nrt = REC_NONE; /* record type for current node */
          m0srcs = 0;     /* # source which will fit in current mbuf chain */
          nbytes = 0;     /* # of bytes appended to group's state-change queue */
          npbytes = 0;    /* # of bytes appended this packet */
          rsrcs = 0;      /* # sources encoded in current record */
          schanged = 0;   /* # nodes encoded in overall filter change */
          nallow = 0;     /* # of source entries in ALLOW_NEW */
          nblock = 0;     /* # of source entries in BLOCK_OLD */
          nims = NULL;    /* next tree node pointer */
  
          /*
           * For each possible filter record mode.
           * The first kind of source we encounter tells us which
           * is the first kind of record we start appending.
           * If a node transitioned to UNDEFINED at t1, its mode is treated
           * as the inverse of the group's filter mode.
           */
          while (drt != REC_FULL) {
                  do {
                          m0 = ifq->ifq_tail;
                          if (m0 != NULL &&
                              (m0->m_pkthdr.PH_vt.vt_nrecs + 1 <=
                               IGMP_V3_REPORT_MAXRECS) &&
                              (m0->m_pkthdr.len + MINRECLEN) <
                               (ifp->if_mtu - IGMP_LEADINGSPACE)) {
                                  m = m0;
                                  m0srcs = (ifp->if_mtu - m0->m_pkthdr.len -
                                              sizeof(struct igmp_grouprec)) /
                                      sizeof(in_addr_t);
                                  CTR1(KTR_IGMPV3,
                                      "%s: use previous packet", __func__);
                          } else {
                                  m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
                                  if (m)
                                          m->m_data += IGMP_LEADINGSPACE;
                                  if (m == NULL) {
                                          m = m_gethdr(M_NOWAIT, MT_DATA);
                                          if (m)
                                                  MH_ALIGN(m, IGMP_LEADINGSPACE);
                                  }
                                  if (m == NULL) {
                                          CTR1(KTR_IGMPV3,
                                              "%s: m_get*() failed", __func__);
                                          return (-ENOMEM);
                                  }
                                  m->m_pkthdr.PH_vt.vt_nrecs = 0;
                                  igmp_save_context(m, ifp);
                                  m0srcs = (ifp->if_mtu - IGMP_LEADINGSPACE -
                                      sizeof(struct igmp_grouprec)) /
                                      sizeof(in_addr_t);
                                  npbytes = 0;
                                  CTR1(KTR_IGMPV3,
                                      "%s: allocated new packet", __func__);
                          }
                          /*
                           * Append the IGMP group record header to the
                           * current packet's data area.
                           * Recalculate pointer to free space for next
                           * group record, in case m_append() allocated
                           * a new mbuf or cluster.
                           */
                          memset(&ig, 0, sizeof(ig));
                          ig.ig_group = inm->inm_addr;
                          if (!m_append(m, sizeof(ig), (void *)&ig)) {
                                  if (m != m0)
                                          m_freem(m);
                                  CTR1(KTR_IGMPV3,
                                      "%s: m_append() failed", __func__);
                                  return (-ENOMEM);
                          }
                          npbytes += sizeof(struct igmp_grouprec);
                          if (m != m0) {
                                  /* new packet; offset in c hain */
                                  md = m_getptr(m, npbytes -
                                      sizeof(struct igmp_grouprec), &off);
                                  pig = (struct igmp_grouprec *)(mtod(md,
                                      uint8_t *) + off);
                          } else {
                                  /* current packet; offset from last append */
                                  md = m_last(m);
                                  pig = (struct igmp_grouprec *)(mtod(md,
                                      uint8_t *) + md->m_len -
                                      sizeof(struct igmp_grouprec));
                          }
                          /*
                           * Begin walking the tree for this record type
                           * pass, or continue from where we left off
                           * previously if we had to allocate a new packet.
                           * Only report deltas in-mode at t1.
                           * We need not report included sources as allowed
                           * if we are in inclusive mode on the group,
                           * however the converse is not true.
                           */
                          rsrcs = 0;
                          if (nims == NULL)
                                  nims = RB_MIN(ip_msource_tree, &inm->inm_srcs);
                          RB_FOREACH_FROM(ims, ip_msource_tree, nims) {
                                  CTR2(KTR_IGMPV3, "%s: visit node %s",
                                      __func__, inet_ntoa_haddr(ims->ims_haddr));
                                  now = ims_get_mode(inm, ims, 1);
                                  then = ims_get_mode(inm, ims, 0);
                                  CTR3(KTR_IGMPV3, "%s: mode: t0 %d, t1 %d",
                                      __func__, then, now);
                                  if (now == then) {
                                          CTR1(KTR_IGMPV3,
                                              "%s: skip unchanged", __func__);
                                          continue;
                                  }
                                  if (mode == MCAST_EXCLUDE &&
                                      now == MCAST_INCLUDE) {
                                          CTR1(KTR_IGMPV3,
                                              "%s: skip IN src on EX group",
                                              __func__);
                                          continue;
                                  }
                                  nrt = (rectype_t)now;
                                  if (nrt == REC_NONE)
                                          nrt = (rectype_t)(~mode & REC_FULL);
                                  if (schanged++ == 0) {
                                          crt = nrt;
                                  } else if (crt != nrt)
                                          continue;
                                  naddr = htonl(ims->ims_haddr);
                                  if (!m_append(m, sizeof(in_addr_t),
                                      (void *)&naddr)) {
                                          if (m != m0)
                                                  m_freem(m);
                                          CTR1(KTR_IGMPV3,
                                              "%s: m_append() failed", __func__);
                                          return (-ENOMEM);
                                  }
                                  nallow += !!(crt == REC_ALLOW);
                                  nblock += !!(crt == REC_BLOCK);
                                  if (++rsrcs == m0srcs)
                                          break;
                          }
                          /*
                           * If we did not append any tree nodes on this
                           * pass, back out of allocations.
                           */
                          if (rsrcs == 0) {
                                  npbytes -= sizeof(struct igmp_grouprec);
                                  if (m != m0) {
                                          CTR1(KTR_IGMPV3,
                                              "%s: m_free(m)", __func__);
                                          m_freem(m);
                                  } else {
                                          CTR1(KTR_IGMPV3,
                                              "%s: m_adj(m, -ig)", __func__);
                                          m_adj(m, -((int)sizeof(
                                              struct igmp_grouprec)));
                                  }
                                  continue;
                          }
                          npbytes += (rsrcs * sizeof(in_addr_t));
                          if (crt == REC_ALLOW)
                                  pig->ig_type = IGMP_ALLOW_NEW_SOURCES;
                          else if (crt == REC_BLOCK)
                                  pig->ig_type = IGMP_BLOCK_OLD_SOURCES;
                          pig->ig_numsrc = htons(rsrcs);
                          /*
                           * Count the new group record, and enqueue this
                           * packet if it wasn't already queued.
                           */
                          m->m_pkthdr.PH_vt.vt_nrecs++;
                          if (m != m0)
                                  _IF_ENQUEUE(ifq, m);
                          nbytes += npbytes;
                  } while (nims != NULL);
                  drt |= crt;
                  crt = (~crt & REC_FULL);
          }
  
          CTR3(KTR_IGMPV3, "%s: queued %d ALLOW_NEW, %d BLOCK_OLD", __func__,
              nallow, nblock);
  
          return (nbytes);
  }
  
  static int
  igmp_v3_merge_state_changes(struct in_multi *inm, struct ifqueue *ifscq)
  {
          struct ifqueue  *gq;
          struct mbuf     *m;             /* pending state-change */
          struct mbuf     *m0;            /* copy of pending state-change */
          struct mbuf     *mt;            /* last state-change in packet */
          int              docopy, domerge;
          u_int            recslen;
  
          docopy = 0;
          domerge = 0;
          recslen = 0;
  
          IN_MULTI_LOCK_ASSERT();
          IGMP_LOCK_ASSERT();
  
          /*
           * If there are further pending retransmissions, make a writable
           * copy of each queued state-change message before merging.
           */
          if (inm->inm_scrv > 0)
                  docopy = 1;
  
          gq = &inm->inm_scq;
  #ifdef KTR
          if (gq->ifq_head == NULL) {
                  CTR2(KTR_IGMPV3, "%s: WARNING: queue for inm %p is empty",
                      __func__, inm);
          }
  #endif
  
          m = gq->ifq_head;
          while (m != NULL) {
                  /*
                   * Only merge the report into the current packet if
                   * there is sufficient space to do so; an IGMPv3 report
                   * packet may only contain 65,535 group records.
                   * Always use a simple mbuf chain concatentation to do this,
                   * as large state changes for single groups may have
                   * allocated clusters.
                   */
                  domerge = 0;
                  mt = ifscq->ifq_tail;
                  if (mt != NULL) {
                          recslen = m_length(m, NULL);
  
                          if ((mt->m_pkthdr.PH_vt.vt_nrecs +
                              m->m_pkthdr.PH_vt.vt_nrecs <=
                              IGMP_V3_REPORT_MAXRECS) &&
                              (mt->m_pkthdr.len + recslen <=
                              (inm->inm_ifp->if_mtu - IGMP_LEADINGSPACE)))
                                  domerge = 1;
                  }
  
                  if (!domerge && _IF_QFULL(gq)) {
                          CTR2(KTR_IGMPV3,
                              "%s: outbound queue full, skipping whole packet %p",
                              __func__, m);
                          mt = m->m_nextpkt;
                          if (!docopy)
                                  m_freem(m);
                          m = mt;
                          continue;
                  }
  
                  if (!docopy) {
                          CTR2(KTR_IGMPV3, "%s: dequeueing %p", __func__, m);
                          _IF_DEQUEUE(gq, m0);
                          m = m0->m_nextpkt;
                  } else {
                          CTR2(KTR_IGMPV3, "%s: copying %p", __func__, m);
                          m0 = m_dup(m, M_NOWAIT);
                          if (m0 == NULL)
                                  return (ENOMEM);
                          m0->m_nextpkt = NULL;
                          m = m->m_nextpkt;
                  }
  
                  if (!domerge) {
                          CTR3(KTR_IGMPV3, "%s: queueing %p to ifscq %p)",
                              __func__, m0, ifscq);
                          _IF_ENQUEUE(ifscq, m0);
                  } else {
                          struct mbuf *mtl;       /* last mbuf of packet mt */
  
                          CTR3(KTR_IGMPV3, "%s: merging %p with ifscq tail %p)",
                              __func__, m0, mt);
  
                          mtl = m_last(mt);
                          m0->m_flags &= ~M_PKTHDR;
                          mt->m_pkthdr.len += recslen;
                          mt->m_pkthdr.PH_vt.vt_nrecs +=
                              m0->m_pkthdr.PH_vt.vt_nrecs;
  
                          mtl->m_next = m0;
                  }
          }
  
          return (0);
  }
  
  /*
   * Respond to a pending IGMPv3 General Query.
   */
  static void
  igmp_v3_dispatch_general_query(struct igmp_ifinfo *igi)
  {
          struct ifmultiaddr      *ifma;
          struct ifnet            *ifp;
          struct in_multi         *inm;
          int                      retval, loop;
  
          IN_MULTI_LOCK_ASSERT();
          IGMP_LOCK_ASSERT();
  
          KASSERT(igi->igi_version == IGMP_VERSION_3,
              ("%s: called when version %d", __func__, igi->igi_version));
  
          ifp = igi->igi_ifp;
  
          IF_ADDR_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;
                  KASSERT(ifp == inm->inm_ifp,
                      ("%s: inconsistent ifp", __func__));
  
                  switch (inm->inm_state) {
                  case IGMP_NOT_MEMBER:
                  case IGMP_SILENT_MEMBER:
                          break;
                  case IGMP_REPORTING_MEMBER:
                  case IGMP_IDLE_MEMBER:
                  case IGMP_LAZY_MEMBER:
                  case IGMP_SLEEPING_MEMBER:
                  case IGMP_AWAKENING_MEMBER:
                          inm->inm_state = IGMP_REPORTING_MEMBER;
                          retval = igmp_v3_enqueue_group_record(&igi->igi_gq,
                              inm, 0, 0, 0);
                          CTR2(KTR_IGMPV3, "%s: enqueue record = %d",
                              __func__, retval);
                          break;
                  case IGMP_G_QUERY_PENDING_MEMBER:
                  case IGMP_SG_QUERY_PENDING_MEMBER:
                  case IGMP_LEAVING_MEMBER:
                          break;
                  }
          }
          IF_ADDR_RUNLOCK(ifp);
  
          loop = (igi->igi_flags & IGIF_LOOPBACK) ? 1 : 0;
          igmp_dispatch_queue(&igi->igi_gq, IGMP_MAX_RESPONSE_BURST, loop);
  
          /*
           * Slew transmission of bursts over 500ms intervals.
           */
          if (igi->igi_gq.ifq_head != NULL) {
                  igi->igi_v3_timer = 1 + IGMP_RANDOM_DELAY(
                      IGMP_RESPONSE_BURST_INTERVAL);
                  V_interface_timers_running = 1;
          }
  }
  
  /*
   * Transmit the next pending IGMP message in the output queue.
   *
   * We get called from netisr_processqueue(). A mutex private to igmpoq
   * will be acquired and released around this routine.
   *
   * VIMAGE: Needs to store/restore vnet pointer on a per-mbuf-chain basis.
   * MRT: Nothing needs to be done, as IGMP traffic is always local to
   * a link and uses a link-scope multicast address.
   */
  static void
  igmp_intr(struct mbuf *m)
  {
          struct ip_moptions       imo;
          struct ifnet            *ifp;
          struct mbuf             *ipopts, *m0;
          int                      error;
          uint32_t                 ifindex;
  
          CTR2(KTR_IGMPV3, "%s: transmit %p", __func__, m);
  
          /*
           * Set VNET image pointer from enqueued mbuf chain
           * before doing anything else. Whilst we use interface
           * indexes to guard against interface detach, they are
           * unique to each VIMAGE and must be retrieved.
           */
          CURVNET_SET((struct vnet *)(m->m_pkthdr.PH_loc.ptr));
          ifindex = igmp_restore_context(m);
  
          /*
           * Check if the ifnet still exists. This limits the scope of
           * any race in the absence of a global ifp lock for low cost
           * (an array lookup).
           */
          ifp = ifnet_byindex(ifindex);
          if (ifp == NULL) {
                  CTR3(KTR_IGMPV3, "%s: dropped %p as ifindex %u went away.",
                      __func__, m, ifindex);
                  m_freem(m);
                  IPSTAT_INC(ips_noroute);
                  goto out;
          }
  
          ipopts = V_igmp_sendra ? m_raopt : NULL;
  
          imo.imo_multicast_ttl  = 1;
          imo.imo_multicast_vif  = -1;
          imo.imo_multicast_loop = (V_ip_mrouter != NULL);
  
          /*
           * If the user requested that IGMP traffic be explicitly
           * redirected to the loopback interface (e.g. they are running a
           * MANET interface and the routing protocol needs to see the
           * updates), handle this now.
           */
          if (m->m_flags & M_IGMP_LOOP)
                  imo.imo_multicast_ifp = V_loif;
          else
                  imo.imo_multicast_ifp = ifp;
  
          if (m->m_flags & M_IGMPV2) {
                  m0 = m;
          } else {
                  m0 = igmp_v3_encap_report(ifp, m);
                  if (m0 == NULL) {
                          CTR2(KTR_IGMPV3, "%s: dropped %p", __func__, m);
                          m_freem(m);
                          IPSTAT_INC(ips_odropped);
                          goto out;
                  }
          }
  
          igmp_scrub_context(m0);
          m_clrprotoflags(m);
          m0->m_pkthdr.rcvif = V_loif;
  #ifdef MAC
          mac_netinet_igmp_send(ifp, m0);
  #endif
          error = ip_output(m0, ipopts, NULL, 0, &imo, NULL);
          if (error) {
                  CTR3(KTR_IGMPV3, "%s: ip_output(%p) = %d", __func__, m0, error);
                  goto out;
          }
  
          IGMPSTAT_INC(igps_snd_reports);
  
  out:
          /*
           * We must restore the existing vnet pointer before
           * continuing as we are run from netisr context.
           */
          CURVNET_RESTORE();
  }
  
  /*
   * Encapsulate an IGMPv3 report.
   *
   * The internal mbuf flag M_IGMPV3_HDR is used to indicate that the mbuf
   * chain has already had its IP/IGMPv3 header prepended. In this case
   * the function will not attempt to prepend; the lengths and checksums
   * will however be re-computed.
   *
   * Returns a pointer to the new mbuf chain head, or NULL if the
   * allocation failed.
   */
  static struct mbuf *
  igmp_v3_encap_report(struct ifnet *ifp, struct mbuf *m)
  {
          struct igmp_report      *igmp;
          struct ip               *ip;
          int                      hdrlen, igmpreclen;
  
          KASSERT((m->m_flags & M_PKTHDR),
              ("%s: mbuf chain %p is !M_PKTHDR", __func__, m));
  
          igmpreclen = m_length(m, NULL);
          hdrlen = sizeof(struct ip) + sizeof(struct igmp_report);
  
          if (m->m_flags & M_IGMPV3_HDR) {
                  igmpreclen -= hdrlen;
          } else {
                  M_PREPEND(m, hdrlen, M_NOWAIT);
                  if (m == NULL)
                          return (NULL);
                  m->m_flags |= M_IGMPV3_HDR;
          }
  
          CTR2(KTR_IGMPV3, "%s: igmpreclen is %d", __func__, igmpreclen);
  
          m->m_data += sizeof(struct ip);
          m->m_len -= sizeof(struct ip);
  
          igmp = mtod(m, struct igmp_report *);
          igmp->ir_type = IGMP_v3_HOST_MEMBERSHIP_REPORT;
          igmp->ir_rsv1 = 0;
          igmp->ir_rsv2 = 0;
          igmp->ir_numgrps = htons(m->m_pkthdr.PH_vt.vt_nrecs);
          igmp->ir_cksum = 0;
          igmp->ir_cksum = in_cksum(m, sizeof(struct igmp_report) + igmpreclen);
          m->m_pkthdr.PH_vt.vt_nrecs = 0;
  
          m->m_data -= sizeof(struct ip);
          m->m_len += sizeof(struct ip);
  
          ip = mtod(m, struct ip *);
          ip->ip_tos = IPTOS_PREC_INTERNETCONTROL;
          ip->ip_len = htons(hdrlen + igmpreclen);
          ip->ip_off = htons(IP_DF);
          ip->ip_p = IPPROTO_IGMP;
          ip->ip_sum = 0;
  
          ip->ip_src.s_addr = INADDR_ANY;
  
          if (m->m_flags & M_IGMP_LOOP) {
                  struct in_ifaddr *ia;
  
                  IFP_TO_IA(ifp, ia);
                  if (ia != NULL) {
                          ip->ip_src = ia->ia_addr.sin_addr;
                          ifa_free(&ia->ia_ifa);
                  }
          }
  
          ip->ip_dst.s_addr = htonl(INADDR_ALLRPTS_GROUP);
  
          return (m);
  }
  
  #ifdef KTR
  static char *
  igmp_rec_type_to_str(const int type)
  {
  
          switch (type) {
                  case IGMP_CHANGE_TO_EXCLUDE_MODE:
                          return "TO_EX";
                          break;
                  case IGMP_CHANGE_TO_INCLUDE_MODE:
                          return "TO_IN";
                          break;
                  case IGMP_MODE_IS_EXCLUDE:
                          return "MODE_EX";
                          break;
                  case IGMP_MODE_IS_INCLUDE:
                          return "MODE_IN";
                          break;
                  case IGMP_ALLOW_NEW_SOURCES:
                          return "ALLOW_NEW";
                          break;
                  case IGMP_BLOCK_OLD_SOURCES:
                          return "BLOCK_OLD";
                          break;
                  default:
                          break;
          }
          return "unknown";
  }
  #endif
  
  static void
  igmp_init(void *unused __unused)
  {
  
          CTR1(KTR_IGMPV3, "%s: initializing", __func__);
  
          IGMP_LOCK_INIT();
  
          m_raopt = igmp_ra_alloc();
  
          netisr_register(&igmp_nh);
  }
  SYSINIT(igmp_init, SI_SUB_PSEUDO, SI_ORDER_MIDDLE, igmp_init, NULL);
  
  static void
  igmp_uninit(void *unused __unused)
  {
  
          CTR1(KTR_IGMPV3, "%s: tearing down", __func__);
  
          netisr_unregister(&igmp_nh);
  
          m_free(m_raopt);
          m_raopt = NULL;
  
          IGMP_LOCK_DESTROY();
  }
  SYSUNINIT(igmp_uninit, SI_SUB_PSEUDO, SI_ORDER_MIDDLE, igmp_uninit, NULL);
  
  static void
  vnet_igmp_init(const void *unused __unused)
  {
  
          CTR1(KTR_IGMPV3, "%s: initializing", __func__);
  
          LIST_INIT(&V_igi_head);
  }
  VNET_SYSINIT(vnet_igmp_init, SI_SUB_PSEUDO, SI_ORDER_ANY, vnet_igmp_init,
      NULL);
  
  static void
  vnet_igmp_uninit(const void *unused __unused)
  {
  
          CTR1(KTR_IGMPV3, "%s: tearing down", __func__);
  
          KASSERT(LIST_EMPTY(&V_igi_head),
              ("%s: igi list not empty; ifnets not detached?", __func__));
  }
  VNET_SYSUNINIT(vnet_igmp_uninit, SI_SUB_PSEUDO, SI_ORDER_ANY,
      vnet_igmp_uninit, NULL);
  
  static int
  igmp_modevent(module_t mod, int type, void *unused __unused)
  {
  
      switch (type) {
      case MOD_LOAD:
      case MOD_UNLOAD:
          break;
      default:
          return (EOPNOTSUPP);
      }
      return (0);
  }
  
  static moduledata_t igmp_mod = {
      "igmp",
      igmp_modevent,
      0
  };
  DECLARE_MODULE(igmp, igmp_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);