FreeBSD/Linux Kernel Cross Reference
sys/net/if_bridge.c

     /*      $NetBSD: if_bridge.c,v 1.189 2022/07/29 07:58:18 skrll Exp $    */
     
     /*
      * Copyright 2001 Wasabi Systems, Inc.
      * All rights reserved.
      *
      * Written by Jason R. Thorpe for Wasabi Systems, Inc.
      *
      * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed for the NetBSD Project by
     *      Wasabi Systems, Inc.
     * 4. The name of Wasabi Systems, Inc. may not be used to endorse
     *    or promote products derived from this software without specific prior
     *    written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``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 WASABI SYSTEMS, INC
     * 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.
     */
    
    /*
     * Copyright (c) 1999, 2000 Jason L. Wright (jason@thought.net)
     * All rights reserved.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by Jason L. Wright
     * 4. The name of the author may not be used to endorse or promote products
     *    derived from this software without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR 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.
     *
     * OpenBSD: if_bridge.c,v 1.60 2001/06/15 03:38:33 itojun Exp
     */
    
    /*
     * Network interface bridge support.
     *
     * TODO:
     *
     *      - Currently only supports Ethernet-like interfaces (Ethernet,
     *        802.11, VLANs on Ethernet, etc.)  Figure out a nice way
     *        to bridge other types of interfaces (FDDI-FDDI, and maybe
     *        consider heterogenous bridges).
     */
    
    #include <sys/cdefs.h>
    __KERNEL_RCSID(0, "$NetBSD: if_bridge.c,v 1.189 2022/07/29 07:58:18 skrll Exp $");
    
    #ifdef _KERNEL_OPT
    #include "opt_inet.h"
    #include "opt_net_mpsafe.h"
    #endif /* _KERNEL_OPT */
    
    #include <sys/param.h>
    #include <sys/kernel.h>
    #include <sys/mbuf.h>
    #include <sys/queue.h>
    #include <sys/socket.h>
    #include <sys/socketvar.h> /* for softnet_lock */
    #include <sys/sockio.h>
    #include <sys/systm.h>
    #include <sys/proc.h>
    #include <sys/pool.h>
   #include <sys/kauth.h>
   #include <sys/cpu.h>
   #include <sys/cprng.h>
   #include <sys/mutex.h>
   #include <sys/kmem.h>
   
   #include <net/bpf.h>
   #include <net/if.h>
   #include <net/if_dl.h>
   #include <net/if_types.h>
   #include <net/if_llc.h>
   
   #include <net/if_ether.h>
   #include <net/if_bridgevar.h>
   #include <net/ether_sw_offload.h>
   
   /* Used for bridge_ip[6]_checkbasic */
   #include <netinet/in.h>
   #include <netinet/in_systm.h>
   #include <netinet/ip.h>
   #include <netinet/ip_var.h>
   #include <netinet/ip_private.h>         /* XXX */
   #include <netinet/ip6.h>
   #include <netinet6/in6_var.h>
   #include <netinet6/ip6_var.h>
   #include <netinet6/ip6_private.h>       /* XXX */
   
   /*
    * Size of the route hash table.  Must be a power of two.
    */
   #ifndef BRIDGE_RTHASH_SIZE
   #define BRIDGE_RTHASH_SIZE              1024
   #endif
   
   #define BRIDGE_RTHASH_MASK              (BRIDGE_RTHASH_SIZE - 1)
   
   #include "carp.h"
   #if NCARP > 0
   #include <netinet/in.h>
   #include <netinet/in_var.h>
   #include <netinet/ip_carp.h>
   #endif
   
   #include "ioconf.h"
   
   __CTASSERT(sizeof(struct ifbifconf) == sizeof(struct ifbaconf));
   __CTASSERT(offsetof(struct ifbifconf, ifbic_len) == offsetof(struct ifbaconf, ifbac_len));
   __CTASSERT(offsetof(struct ifbifconf, ifbic_buf) == offsetof(struct ifbaconf, ifbac_buf));
   
   /*
    * Maximum number of addresses to cache.
    */
   #ifndef BRIDGE_RTABLE_MAX
   #define BRIDGE_RTABLE_MAX               100
   #endif
   
   /*
    * Spanning tree defaults.
    */
   #define BSTP_DEFAULT_MAX_AGE            (20 * 256)
   #define BSTP_DEFAULT_HELLO_TIME         (2 * 256)
   #define BSTP_DEFAULT_FORWARD_DELAY      (15 * 256)
   #define BSTP_DEFAULT_HOLD_TIME          (1 * 256)
   #define BSTP_DEFAULT_BRIDGE_PRIORITY    0x8000
   #define BSTP_DEFAULT_PORT_PRIORITY      0x80
   #define BSTP_DEFAULT_PATH_COST          55
   
   /*
    * Timeout (in seconds) for entries learned dynamically.
    */
   #ifndef BRIDGE_RTABLE_TIMEOUT
   #define BRIDGE_RTABLE_TIMEOUT           (20 * 60)       /* same as ARP */
   #endif
   
   /*
    * Number of seconds between walks of the route list.
    */
   #ifndef BRIDGE_RTABLE_PRUNE_PERIOD
   #define BRIDGE_RTABLE_PRUNE_PERIOD      (5 * 60)
   #endif
   
   #define BRIDGE_RT_LOCK(_sc)     mutex_enter((_sc)->sc_rtlist_lock)
   #define BRIDGE_RT_UNLOCK(_sc)   mutex_exit((_sc)->sc_rtlist_lock)
   #define BRIDGE_RT_LOCKED(_sc)   mutex_owned((_sc)->sc_rtlist_lock)
   
   #define BRIDGE_RT_PSZ_PERFORM(_sc) \
                                   pserialize_perform((_sc)->sc_rtlist_psz)
   
   #define BRIDGE_RT_RENTER(__s)   do { __s = pserialize_read_enter(); } while (0)
   #define BRIDGE_RT_REXIT(__s)    do { pserialize_read_exit(__s); } while (0)
   
   #define BRIDGE_RTLIST_READER_FOREACH(_brt, _sc)                 \
           PSLIST_READER_FOREACH((_brt), &((_sc)->sc_rtlist),              \
               struct bridge_rtnode, brt_list)
   #define BRIDGE_RTLIST_WRITER_FOREACH(_brt, _sc)                 \
           PSLIST_WRITER_FOREACH((_brt), &((_sc)->sc_rtlist),              \
               struct bridge_rtnode, brt_list)
   #define BRIDGE_RTLIST_WRITER_INSERT_HEAD(_sc, _brt)                     \
           PSLIST_WRITER_INSERT_HEAD(&(_sc)->sc_rtlist, brt, brt_list)
   #define BRIDGE_RTLIST_WRITER_REMOVE(_brt)                               \
           PSLIST_WRITER_REMOVE((_brt), brt_list)
   
   #define BRIDGE_RTHASH_READER_FOREACH(_brt, _sc, _hash)                  \
           PSLIST_READER_FOREACH((_brt), &(_sc)->sc_rthash[(_hash)],       \
               struct bridge_rtnode, brt_hash)
   #define BRIDGE_RTHASH_WRITER_FOREACH(_brt, _sc, _hash)                  \
           PSLIST_WRITER_FOREACH((_brt), &(_sc)->sc_rthash[(_hash)],       \
               struct bridge_rtnode, brt_hash)
   #define BRIDGE_RTHASH_WRITER_INSERT_HEAD(_sc, _hash, _brt)              \
           PSLIST_WRITER_INSERT_HEAD(&(_sc)->sc_rthash[(_hash)], brt, brt_hash)
   #define BRIDGE_RTHASH_WRITER_INSERT_AFTER(_brt, _new)                   \
           PSLIST_WRITER_INSERT_AFTER((_brt), (_new), brt_hash)
   #define BRIDGE_RTHASH_WRITER_REMOVE(_brt)                               \
           PSLIST_WRITER_REMOVE((_brt), brt_hash)
   
   #ifdef NET_MPSAFE
   #define DECLARE_LOCK_VARIABLE
   #define ACQUIRE_GLOBAL_LOCKS()  do { } while (0)
   #define RELEASE_GLOBAL_LOCKS()  do { } while (0)
   #else
   #define DECLARE_LOCK_VARIABLE   int __s
   #define ACQUIRE_GLOBAL_LOCKS()  do {                                    \
                                           KERNEL_LOCK(1, NULL);           \
                                           mutex_enter(softnet_lock);      \
                                           __s = splsoftnet();             \
                                   } while (0)
   #define RELEASE_GLOBAL_LOCKS()  do {                                    \
                                           splx(__s);                      \
                                           mutex_exit(softnet_lock);       \
                                           KERNEL_UNLOCK_ONE(NULL);        \
                                   } while (0)
   #endif
   
   struct psref_class *bridge_psref_class __read_mostly;
   
   int     bridge_rtable_prune_period = BRIDGE_RTABLE_PRUNE_PERIOD;
   
   static struct pool bridge_rtnode_pool;
   
   static int      bridge_clone_create(struct if_clone *, int);
   static int      bridge_clone_destroy(struct ifnet *);
   
   static int      bridge_ioctl(struct ifnet *, u_long, void *);
   static int      bridge_init(struct ifnet *);
   static void     bridge_stop(struct ifnet *, int);
   static void     bridge_start(struct ifnet *);
   static void     bridge_ifdetach(void *);
   
   static void     bridge_input(struct ifnet *, struct mbuf *);
   static void     bridge_forward(struct bridge_softc *, struct mbuf *);
   
   static void     bridge_timer(void *);
   
   static void     bridge_broadcast(struct bridge_softc *, struct ifnet *,
                                    struct mbuf *);
   
   static int      bridge_rtupdate(struct bridge_softc *, const uint8_t *,
                                   struct ifnet *, int, uint8_t);
   static struct ifnet *bridge_rtlookup(struct bridge_softc *, const uint8_t *);
   static void     bridge_rttrim(struct bridge_softc *);
   static void     bridge_rtage(struct bridge_softc *);
   static void     bridge_rtage_work(struct work *, void *);
   static void     bridge_rtflush(struct bridge_softc *, int);
   static int      bridge_rtdaddr(struct bridge_softc *, const uint8_t *);
   static void     bridge_rtdelete(struct bridge_softc *, struct ifnet *ifp);
   
   static void     bridge_rtable_init(struct bridge_softc *);
   static void     bridge_rtable_fini(struct bridge_softc *);
   
   static struct bridge_rtnode *bridge_rtnode_lookup(struct bridge_softc *,
                                                     const uint8_t *);
   static int      bridge_rtnode_insert(struct bridge_softc *,
                                        struct bridge_rtnode *);
   static void     bridge_rtnode_remove(struct bridge_softc *,
                                        struct bridge_rtnode *);
   static void     bridge_rtnode_destroy(struct bridge_rtnode *);
   
   static struct bridge_iflist *bridge_lookup_member(struct bridge_softc *,
                                                     const char *name,
                                                     struct psref *);
   static struct bridge_iflist *bridge_lookup_member_if(struct bridge_softc *,
                                                        struct ifnet *ifp,
                                                        struct psref *);
   static void     bridge_release_member(struct bridge_softc *, struct bridge_iflist *,
                                         struct psref *);
   static void     bridge_delete_member(struct bridge_softc *,
                                        struct bridge_iflist *);
   static void     bridge_acquire_member(struct bridge_softc *sc,
                                         struct bridge_iflist *,
                                         struct psref *);
   
   static int      bridge_ioctl_add(struct bridge_softc *, void *);
   static int      bridge_ioctl_del(struct bridge_softc *, void *);
   static int      bridge_ioctl_gifflags(struct bridge_softc *, void *);
   static int      bridge_ioctl_sifflags(struct bridge_softc *, void *);
   static int      bridge_ioctl_scache(struct bridge_softc *, void *);
   static int      bridge_ioctl_gcache(struct bridge_softc *, void *);
   static int      bridge_ioctl_gifs(struct bridge_softc *, void *);
   static int      bridge_ioctl_rts(struct bridge_softc *, void *);
   static int      bridge_ioctl_saddr(struct bridge_softc *, void *);
   static int      bridge_ioctl_sto(struct bridge_softc *, void *);
   static int      bridge_ioctl_gto(struct bridge_softc *, void *);
   static int      bridge_ioctl_daddr(struct bridge_softc *, void *);
   static int      bridge_ioctl_flush(struct bridge_softc *, void *);
   static int      bridge_ioctl_gpri(struct bridge_softc *, void *);
   static int      bridge_ioctl_spri(struct bridge_softc *, void *);
   static int      bridge_ioctl_ght(struct bridge_softc *, void *);
   static int      bridge_ioctl_sht(struct bridge_softc *, void *);
   static int      bridge_ioctl_gfd(struct bridge_softc *, void *);
   static int      bridge_ioctl_sfd(struct bridge_softc *, void *);
   static int      bridge_ioctl_gma(struct bridge_softc *, void *);
   static int      bridge_ioctl_sma(struct bridge_softc *, void *);
   static int      bridge_ioctl_sifprio(struct bridge_softc *, void *);
   static int      bridge_ioctl_sifcost(struct bridge_softc *, void *);
   static int      bridge_ioctl_gfilt(struct bridge_softc *, void *);
   static int      bridge_ioctl_sfilt(struct bridge_softc *, void *);
   static int      bridge_ipf(void *, struct mbuf **, struct ifnet *, int);
   static int      bridge_ip_checkbasic(struct mbuf **mp);
   # ifdef INET6
   static int      bridge_ip6_checkbasic(struct mbuf **mp);
   # endif /* INET6 */
   
   struct bridge_control {
           int     (*bc_func)(struct bridge_softc *, void *);
           int     bc_argsize;
           int     bc_flags;
   };
   
   #define BC_F_COPYIN             0x01    /* copy arguments in */
   #define BC_F_COPYOUT            0x02    /* copy arguments out */
   #define BC_F_SUSER              0x04    /* do super-user check */
   #define BC_F_XLATEIN            0x08    /* xlate arguments in */
   #define BC_F_XLATEOUT           0x10    /* xlate arguments out */
   
   static const struct bridge_control bridge_control_table[] = {
   [BRDGADD] = {bridge_ioctl_add, sizeof(struct ifbreq), BC_F_COPYIN|BC_F_SUSER},
   [BRDGDEL] = {bridge_ioctl_del, sizeof(struct ifbreq), BC_F_COPYIN|BC_F_SUSER},
   
   [BRDGGIFFLGS] = {bridge_ioctl_gifflags, sizeof(struct ifbreq), BC_F_COPYIN|BC_F_COPYOUT},
   [BRDGSIFFLGS] = {bridge_ioctl_sifflags, sizeof(struct ifbreq), BC_F_COPYIN|BC_F_SUSER},
   
   [BRDGSCACHE] = {bridge_ioctl_scache, sizeof(struct ifbrparam), BC_F_COPYIN|BC_F_SUSER},
   [BRDGGCACHE] = {bridge_ioctl_gcache, sizeof(struct ifbrparam), BC_F_COPYOUT},
   
   [OBRDGGIFS] = {bridge_ioctl_gifs, sizeof(struct ifbifconf), BC_F_COPYIN|BC_F_COPYOUT},
   [OBRDGRTS] = {bridge_ioctl_rts, sizeof(struct ifbaconf), BC_F_COPYIN|BC_F_COPYOUT},
   
   [BRDGSADDR] = {bridge_ioctl_saddr, sizeof(struct ifbareq), BC_F_COPYIN|BC_F_SUSER},
   
   [BRDGSTO] = {bridge_ioctl_sto, sizeof(struct ifbrparam), BC_F_COPYIN|BC_F_SUSER},
   [BRDGGTO] = {bridge_ioctl_gto, sizeof(struct ifbrparam), BC_F_COPYOUT},
   
   [BRDGDADDR] = {bridge_ioctl_daddr, sizeof(struct ifbareq), BC_F_COPYIN|BC_F_SUSER},
   
   [BRDGFLUSH] = {bridge_ioctl_flush, sizeof(struct ifbreq), BC_F_COPYIN|BC_F_SUSER},
   
   [BRDGGPRI] = {bridge_ioctl_gpri, sizeof(struct ifbrparam), BC_F_COPYOUT},
   [BRDGSPRI] = {bridge_ioctl_spri, sizeof(struct ifbrparam), BC_F_COPYIN|BC_F_SUSER},
   
   [BRDGGHT] = {bridge_ioctl_ght, sizeof(struct ifbrparam), BC_F_COPYOUT},
   [BRDGSHT] = {bridge_ioctl_sht, sizeof(struct ifbrparam), BC_F_COPYIN|BC_F_SUSER},
   
   [BRDGGFD] = {bridge_ioctl_gfd, sizeof(struct ifbrparam), BC_F_COPYOUT},
   [BRDGSFD] = {bridge_ioctl_sfd, sizeof(struct ifbrparam), BC_F_COPYIN|BC_F_SUSER},
   
   [BRDGGMA] = {bridge_ioctl_gma, sizeof(struct ifbrparam), BC_F_COPYOUT},
   [BRDGSMA] = {bridge_ioctl_sma, sizeof(struct ifbrparam), BC_F_COPYIN|BC_F_SUSER},
   
   [BRDGSIFPRIO] = {bridge_ioctl_sifprio, sizeof(struct ifbreq), BC_F_COPYIN|BC_F_SUSER},
   
   [BRDGSIFCOST] = {bridge_ioctl_sifcost, sizeof(struct ifbreq), BC_F_COPYIN|BC_F_SUSER},
   
   [BRDGGFILT] = {bridge_ioctl_gfilt, sizeof(struct ifbrparam), BC_F_COPYOUT},
   [BRDGSFILT] = {bridge_ioctl_sfilt, sizeof(struct ifbrparam), BC_F_COPYIN|BC_F_SUSER},
   
   [BRDGGIFS] = {bridge_ioctl_gifs, sizeof(struct ifbifconf), BC_F_XLATEIN|BC_F_XLATEOUT},
   [BRDGRTS] = {bridge_ioctl_rts, sizeof(struct ifbaconf), BC_F_XLATEIN|BC_F_XLATEOUT},
   };
   
   static const int bridge_control_table_size = __arraycount(bridge_control_table);
   
   static struct if_clone bridge_cloner =
       IF_CLONE_INITIALIZER("bridge", bridge_clone_create, bridge_clone_destroy);
   
   /*
    * bridgeattach:
    *
    *      Pseudo-device attach routine.
    */
   void
   bridgeattach(int n)
   {
   
           pool_init(&bridge_rtnode_pool, sizeof(struct bridge_rtnode),
               0, 0, 0, "brtpl", NULL, IPL_NET);
   
           bridge_psref_class = psref_class_create("bridge", IPL_SOFTNET);
   
           if_clone_attach(&bridge_cloner);
   }
   
   /*
    * bridge_clone_create:
    *
    *      Create a new bridge instance.
    */
   static int
   bridge_clone_create(struct if_clone *ifc, int unit)
   {
           struct bridge_softc *sc;
           struct ifnet *ifp;
           int error;
   
           sc = kmem_zalloc(sizeof(*sc),  KM_SLEEP);
           ifp = &sc->sc_if;
   
           sc->sc_brtmax = BRIDGE_RTABLE_MAX;
           sc->sc_brttimeout = BRIDGE_RTABLE_TIMEOUT;
           sc->sc_bridge_max_age = BSTP_DEFAULT_MAX_AGE;
           sc->sc_bridge_hello_time = BSTP_DEFAULT_HELLO_TIME;
           sc->sc_bridge_forward_delay = BSTP_DEFAULT_FORWARD_DELAY;
           sc->sc_bridge_priority = BSTP_DEFAULT_BRIDGE_PRIORITY;
           sc->sc_hold_time = BSTP_DEFAULT_HOLD_TIME;
           sc->sc_filter_flags = 0;
   
           /* Initialize our routing table. */
           bridge_rtable_init(sc);
   
           error = workqueue_create(&sc->sc_rtage_wq, "bridge_rtage",
               bridge_rtage_work, sc, PRI_SOFTNET, IPL_SOFTNET, WQ_MPSAFE);
           if (error)
                   panic("%s: workqueue_create %d\n", __func__, error);
   
           callout_init(&sc->sc_brcallout, CALLOUT_MPSAFE);
           callout_init(&sc->sc_bstpcallout, CALLOUT_MPSAFE);
   
           mutex_init(&sc->sc_iflist_psref.bip_lock, MUTEX_DEFAULT, IPL_NONE);
           PSLIST_INIT(&sc->sc_iflist_psref.bip_iflist);
           sc->sc_iflist_psref.bip_psz = pserialize_create();
   
           if_initname(ifp, ifc->ifc_name, unit);
           ifp->if_softc = sc;
   #ifdef NET_MPSAFE
           ifp->if_extflags = IFEF_MPSAFE;
   #endif
           ifp->if_mtu = ETHERMTU;
           ifp->if_ioctl = bridge_ioctl;
           ifp->if_output = bridge_output;
           ifp->if_start = bridge_start;
           ifp->if_stop = bridge_stop;
           ifp->if_init = bridge_init;
           ifp->if_type = IFT_BRIDGE;
           ifp->if_addrlen = 0;
           ifp->if_dlt = DLT_EN10MB;
           ifp->if_hdrlen = ETHER_HDR_LEN;
           if_initialize(ifp);
   
           /*
            * Set the link state to down.
            * When interfaces are added the link state will reflect
            * the best link state of the combined interfaces.
            */
           ifp->if_link_state = LINK_STATE_DOWN;
   
           if_alloc_sadl(ifp);
           if_register(ifp);
   
           return 0;
   }
   
   /*
    * bridge_clone_destroy:
    *
    *      Destroy a bridge instance.
    */
   static int
   bridge_clone_destroy(struct ifnet *ifp)
   {
           struct bridge_softc *sc = ifp->if_softc;
           struct bridge_iflist *bif;
   
           if ((ifp->if_flags & IFF_RUNNING) != 0)
                   bridge_stop(ifp, 1);
   
           BRIDGE_LOCK(sc);
           for (;;) {
                   bif = PSLIST_WRITER_FIRST(&sc->sc_iflist_psref.bip_iflist, struct bridge_iflist,
                       bif_next);
                   if (bif == NULL)
                           break;
                   bridge_delete_member(sc, bif);
           }
           PSLIST_DESTROY(&sc->sc_iflist_psref.bip_iflist);
           BRIDGE_UNLOCK(sc);
   
           if_detach(ifp);
   
           /* Tear down the routing table. */
           bridge_rtable_fini(sc);
   
           pserialize_destroy(sc->sc_iflist_psref.bip_psz);
           mutex_destroy(&sc->sc_iflist_psref.bip_lock);
           callout_destroy(&sc->sc_brcallout);
           callout_destroy(&sc->sc_bstpcallout);
           workqueue_destroy(sc->sc_rtage_wq);
           kmem_free(sc, sizeof(*sc));
   
           return 0;
   }
   
   /*
    * bridge_ioctl:
    *
    *      Handle a control request from the operator.
    */
   static int
   bridge_ioctl(struct ifnet *ifp, u_long cmd, void *data)
   {
           struct bridge_softc *sc = ifp->if_softc;
           struct lwp *l = curlwp; /* XXX */
           union {
                   struct ifbreq ifbreq;
                   struct ifbifconf ifbifconf;
                   struct ifbareq ifbareq;
                   struct ifbaconf ifbaconf;
                   struct ifbrparam ifbrparam;
           } args;
           struct ifdrv *ifd = (struct ifdrv *) data;
           const struct bridge_control *bc = NULL; /* XXXGCC */
           int error = 0;
   
           /* Authorize command before calling splsoftnet(). */
           switch (cmd) {
           case SIOCGDRVSPEC:
           case SIOCSDRVSPEC:
                   if (ifd->ifd_cmd >= bridge_control_table_size
                       || (bc = &bridge_control_table[ifd->ifd_cmd]) == NULL) {
                           error = EINVAL;
                           return error;
                   }
   
                   /* We only care about BC_F_SUSER at this point. */
                   if ((bc->bc_flags & BC_F_SUSER) == 0)
                           break;
   
                   error = kauth_authorize_network(l->l_cred,
                       KAUTH_NETWORK_INTERFACE_BRIDGE,
                       cmd == SIOCGDRVSPEC ?
                        KAUTH_REQ_NETWORK_INTERFACE_BRIDGE_GETPRIV :
                        KAUTH_REQ_NETWORK_INTERFACE_BRIDGE_SETPRIV,
                        ifd, NULL, NULL);
                   if (error)
                           return error;
   
                   break;
           }
   
           const int s = splsoftnet();
   
           switch (cmd) {
           case SIOCGDRVSPEC:
           case SIOCSDRVSPEC:
                   KASSERT(bc != NULL);
                   if (cmd == SIOCGDRVSPEC &&
                       (bc->bc_flags & (BC_F_COPYOUT|BC_F_XLATEOUT)) == 0) {
                           error = EINVAL;
                           break;
                   }
                   else if (cmd == SIOCSDRVSPEC &&
                       (bc->bc_flags & (BC_F_COPYOUT|BC_F_XLATEOUT)) != 0) {
                           error = EINVAL;
                           break;
                   }
   
                   /* BC_F_SUSER is checked above, before splsoftnet(). */
   
                   if ((bc->bc_flags & (BC_F_XLATEIN|BC_F_XLATEOUT)) == 0
                       && (ifd->ifd_len != bc->bc_argsize
                           || ifd->ifd_len > sizeof(args))) {
                           error = EINVAL;
                           break;
                   }
   
                   memset(&args, 0, sizeof(args));
                   if (bc->bc_flags & BC_F_COPYIN) {
                           error = copyin(ifd->ifd_data, &args, ifd->ifd_len);
                           if (error)
                                   break;
                   } else if (bc->bc_flags & BC_F_XLATEIN) {
                           args.ifbifconf.ifbic_len = ifd->ifd_len;
                           args.ifbifconf.ifbic_buf = ifd->ifd_data;
                   }
   
                   error = (*bc->bc_func)(sc, &args);
                   if (error)
                           break;
   
                   if (bc->bc_flags & BC_F_COPYOUT) {
                           error = copyout(&args, ifd->ifd_data, ifd->ifd_len);
                   } else if (bc->bc_flags & BC_F_XLATEOUT) {
                           ifd->ifd_len = args.ifbifconf.ifbic_len;
                           ifd->ifd_data = args.ifbifconf.ifbic_buf;
                   }
                   break;
   
           case SIOCSIFFLAGS:
                   if ((error = ifioctl_common(ifp, cmd, data)) != 0)
                           break;
                   switch (ifp->if_flags & (IFF_UP|IFF_RUNNING)) {
                   case IFF_RUNNING:
                           /*
                            * If interface is marked down and it is running,
                            * then stop and disable it.
                            */
                           if_stop(ifp, 1);
                           break;
                   case IFF_UP:
                           /*
                            * If interface is marked up and it is stopped, then
                            * start it.
                            */
                           error = if_init(ifp);
                           break;
                   default:
                           break;
                   }
                   break;
   
           case SIOCSIFMTU:
                   if ((error = ifioctl_common(ifp, cmd, data)) == ENETRESET)
                           error = 0;
                   break;
   
           case SIOCGIFCAP:
               {
                   struct ifcapreq *ifcr = (struct ifcapreq *)data;
                   ifcr->ifcr_capabilities = sc->sc_capenable;
                   ifcr->ifcr_capenable = sc->sc_capenable;
                   break;
               }
   
           default:
                   error = ifioctl_common(ifp, cmd, data);
                   break;
           }
   
           splx(s);
   
           return error;
   }
   
   /*
    * bridge_lookup_member:
    *
    *      Lookup a bridge member interface.
    */
   static struct bridge_iflist *
   bridge_lookup_member(struct bridge_softc *sc, const char *name, struct psref *psref)
   {
           struct bridge_iflist *bif;
           struct ifnet *ifp;
           int s;
   
           BRIDGE_PSZ_RENTER(s);
   
           BRIDGE_IFLIST_READER_FOREACH(bif, sc) {
                   ifp = bif->bif_ifp;
                   if (strcmp(ifp->if_xname, name) == 0)
                           break;
           }
           if (bif != NULL)
                   bridge_acquire_member(sc, bif, psref);
   
           BRIDGE_PSZ_REXIT(s);
   
           return bif;
   }
   
   /*
    * bridge_lookup_member_if:
    *
    *      Lookup a bridge member interface by ifnet*.
    */
   static struct bridge_iflist *
   bridge_lookup_member_if(struct bridge_softc *sc, struct ifnet *member_ifp,
       struct psref *psref)
   {
           struct bridge_iflist *bif;
           int s;
   
           BRIDGE_PSZ_RENTER(s);
   
           bif = member_ifp->if_bridgeif;
           if (bif != NULL) {
                   psref_acquire(psref, &bif->bif_psref,
                       bridge_psref_class);
           }
   
           BRIDGE_PSZ_REXIT(s);
   
           return bif;
   }
   
   static void
   bridge_acquire_member(struct bridge_softc *sc, struct bridge_iflist *bif,
       struct psref *psref)
   {
   
           psref_acquire(psref, &bif->bif_psref, bridge_psref_class);
   }
   
   /*
    * bridge_release_member:
    *
    *      Release the specified member interface.
    */
   static void
   bridge_release_member(struct bridge_softc *sc, struct bridge_iflist *bif,
       struct psref *psref)
   {
   
           psref_release(psref, &bif->bif_psref, bridge_psref_class);
   }
   
   /*
    * bridge_delete_member:
    *
    *      Delete the specified member interface.
    */
   static void
   bridge_delete_member(struct bridge_softc *sc, struct bridge_iflist *bif)
   {
           struct ifnet *ifs = bif->bif_ifp;
   
           KASSERT(BRIDGE_LOCKED(sc));
   
           ifs->_if_input = ether_input;
           ifs->if_bridge = NULL;
           ifs->if_bridgeif = NULL;
   
           PSLIST_WRITER_REMOVE(bif, bif_next);
           BRIDGE_PSZ_PERFORM(sc);
   
           if_linkstate_change_disestablish(ifs,
               bif->bif_linkstate_hook, BRIDGE_LOCK_OBJ(sc));
           ether_ifdetachhook_disestablish(ifs,
               bif->bif_ifdetach_hook, BRIDGE_LOCK_OBJ(sc));
   
           BRIDGE_UNLOCK(sc);
   
           switch (ifs->if_type) {
           case IFT_ETHER:
           case IFT_L2TP:
                   /*
                    * Take the interface out of promiscuous mode.
                    * Don't call it with holding a spin lock.
                    */
                   (void) ifpromisc(ifs, 0);
                   IFNET_LOCK(ifs);
                   (void) ether_disable_vlan_mtu(ifs);
                   IFNET_UNLOCK(ifs);
                   break;
           default:
   #ifdef DIAGNOSTIC
                   panic("%s: impossible", __func__);
   #endif
                   break;
           }
   
           psref_target_destroy(&bif->bif_psref, bridge_psref_class);
   
           PSLIST_ENTRY_DESTROY(bif, bif_next);
           kmem_free(bif, sizeof(*bif));
   
           BRIDGE_LOCK(sc);
   }
   
   /*
    * bridge_calc_csum_flags:
    *
    *      Calculate logical and b/w csum flags each member interface supports.
    */
   void
   bridge_calc_csum_flags(struct bridge_softc *sc)
   {
           struct bridge_iflist *bif;
           struct ifnet *ifs = NULL;
           int flags = ~0;
           int capenable = ~0;
   
           BRIDGE_LOCK(sc);
           BRIDGE_IFLIST_READER_FOREACH(bif, sc) {
                   ifs = bif->bif_ifp;
                   flags &= ifs->if_csum_flags_tx;
                   capenable &= ifs->if_capenable;
           }
           sc->sc_csum_flags_tx = flags;
           sc->sc_capenable = (ifs != NULL) ? capenable : 0;
           BRIDGE_UNLOCK(sc);
   }
   
   /*
    * bridge_calc_link_state:
    *
    *      Calculate the link state based on each member interface.
    */
   static void
   bridge_calc_link_state(void *xsc)
   {
           struct bridge_softc *sc = xsc;
           struct bridge_iflist *bif;
           struct ifnet *ifs;
           int link_state = LINK_STATE_DOWN;
   
           BRIDGE_LOCK(sc);
           BRIDGE_IFLIST_READER_FOREACH(bif, sc) {
                   ifs = bif->bif_ifp;
                   if (ifs->if_link_state == LINK_STATE_UP) {
                           link_state = LINK_STATE_UP;
                           break;
                   }
                   if (ifs->if_link_state == LINK_STATE_UNKNOWN)
                           link_state = LINK_STATE_UNKNOWN;
           }
           if_link_state_change(&sc->sc_if, link_state);
           BRIDGE_UNLOCK(sc);
   }
   
   static int
   bridge_ioctl_add(struct bridge_softc *sc, void *arg)
   {
           struct ifbreq *req = arg;
           struct bridge_iflist *bif = NULL;
           struct ifnet *ifs;
           int error = 0;
           struct psref psref;
   
           ifs = if_get(req->ifbr_ifsname, &psref);
           if (ifs == NULL)
                   return ENOENT;
   
           if (ifs->if_bridge == sc) {
                   error = EEXIST;
                   goto out;
           }
   
           if (ifs->if_bridge != NULL) {
                   error = EBUSY;
                   goto out;
           }
   
           if (ifs->_if_input != ether_input) {
                   error = EINVAL;
                   goto out;
           }
   
           /* FIXME: doesn't work with non-IFF_SIMPLEX interfaces */
           if ((ifs->if_flags & IFF_SIMPLEX) == 0) {
                   error = EINVAL;
                   goto out;
           }
   
           bif = kmem_alloc(sizeof(*bif), KM_SLEEP);
   
           switch (ifs->if_type) {
           case IFT_ETHER:
                   if (sc->sc_if.if_mtu != ifs->if_mtu) {
                           /* Change MTU of added interface to bridge MTU */
                           struct ifreq ifr;
                           memset(&ifr, 0, sizeof(ifr));
                           ifr.ifr_mtu = sc->sc_if.if_mtu;
                           IFNET_LOCK(ifs);
                           error = if_ioctl(ifs, SIOCSIFMTU, &ifr);
                           IFNET_UNLOCK(ifs);
                           if (error != 0)
                                   goto out;
                   }
                   /* FALLTHROUGH */
           case IFT_L2TP:
                   IFNET_LOCK(ifs);
                   error = ether_enable_vlan_mtu(ifs);
                   IFNET_UNLOCK(ifs);
                   if (error > 0)
                           goto out;
                   /*
                    * Place the interface into promiscuous mode.
                    */
                   error = ifpromisc(ifs, 1);
                   if (error)
                           goto out;
                   break;
           default:
                   error = EINVAL;
                   goto out;
           }
   
           bif->bif_ifp = ifs;
           bif->bif_flags = IFBIF_LEARNING | IFBIF_DISCOVER;
           bif->bif_priority = BSTP_DEFAULT_PORT_PRIORITY;
           bif->bif_path_cost = BSTP_DEFAULT_PATH_COST;
           bif->bif_linkstate_hook = if_linkstate_change_establish(ifs,
               bridge_calc_link_state, sc);
           PSLIST_ENTRY_INIT(bif, bif_next);
           psref_target_init(&bif->bif_psref, bridge_psref_class);
   
           BRIDGE_LOCK(sc);
   
           ifs->if_bridge = sc;
           ifs->if_bridgeif = bif;
           PSLIST_WRITER_INSERT_HEAD(&sc->sc_iflist_psref.bip_iflist, bif, bif_next);
           ifs->_if_input = bridge_input;
   
           BRIDGE_UNLOCK(sc);
   
           bif->bif_ifdetach_hook = ether_ifdetachhook_establish(ifs,
               bridge_ifdetach, (void *)ifs);
   
           bridge_calc_csum_flags(sc);
           bridge_calc_link_state(sc);
   
           if (sc->sc_if.if_flags & IFF_RUNNING)
                   bstp_initialization(sc);
           else
                   bstp_stop(sc);
   
   out:
           if_put(ifs, &psref);
           if (error) {
                   if (bif != NULL)
                           kmem_free(bif, sizeof(*bif));
           }
           return error;
   }
   
   static int
   bridge_ioctl_del(struct bridge_softc *sc, void *arg)
   {
           struct ifbreq *req = arg;
           const char *name = req->ifbr_ifsname;
           struct bridge_iflist *bif;
           struct ifnet *ifs;
   
           BRIDGE_LOCK(sc);
   
           /*
            * Don't use bridge_lookup_member. We want to get a member
            * with bif_refs == 0.
            */
           BRIDGE_IFLIST_WRITER_FOREACH(bif, sc) {
                   ifs = bif->bif_ifp;
                   if (strcmp(ifs->if_xname, name) == 0)
                           break;
           }
   
           if (bif == NULL) {
                   BRIDGE_UNLOCK(sc);
                   return ENOENT;
           }
   
           bridge_delete_member(sc, bif);
   
           BRIDGE_UNLOCK(sc);
   
           bridge_rtdelete(sc, ifs);
           bridge_calc_csum_flags(sc);
           bridge_calc_link_state(sc);
   
           if (sc->sc_if.if_flags & IFF_RUNNING)
                   bstp_initialization(sc);
   
           return 0;
   }
   
   static int
   bridge_ioctl_gifflags(struct bridge_softc *sc, void *arg)
   {
           struct ifbreq *req = arg;
           struct bridge_iflist *bif;
           struct psref psref;
   
           bif = bridge_lookup_member(sc, req->ifbr_ifsname, &psref);
           if (bif == NULL)
                   return ENOENT;
   
           req->ifbr_ifsflags = bif->bif_flags;
           req->ifbr_state = bif->bif_state;
           req->ifbr_priority = bif->bif_priority;
           req->ifbr_path_cost = bif->bif_path_cost;
           req->ifbr_portno = bif->bif_ifp->if_index & 0xff;
   
           bridge_release_member(sc, bif, &psref);
   
           return 0;
   }
   
   static int
   bridge_ioctl_sifflags(struct bridge_softc *sc, void *arg)
   {
           struct ifbreq *req = arg;
           struct bridge_iflist *bif;
          struct psref psref;
  
          bif = bridge_lookup_member(sc, req->ifbr_ifsname, &psref);
          if (bif == NULL)
                  return ENOENT;
  
          if (req->ifbr_ifsflags & IFBIF_STP) {
                  switch (bif->bif_ifp->if_type) {
                  case IFT_ETHER:
                  case IFT_L2TP:
                          /* These can do spanning tree. */
                          break;
  
                  default:
                          /* Nothing else can. */
                          bridge_release_member(sc, bif, &psref);
                          return EINVAL;
                  }
          }
  
          bif->bif_flags = req->ifbr_ifsflags;
  
          bridge_release_member(sc, bif, &psref);
  
          if (sc->sc_if.if_flags & IFF_RUNNING)
                  bstp_initialization(sc);
  
          return 0;
  }
  
  static int
  bridge_ioctl_scache(struct bridge_softc *sc, void *arg)
  {
          struct ifbrparam *param = arg;
  
          sc->sc_brtmax = param->ifbrp_csize;
          bridge_rttrim(sc);
  
          return 0;
  }
  
  static int
  bridge_ioctl_gcache(struct bridge_softc *sc, void *arg)
  {
          struct ifbrparam *param = arg;
  
          param->ifbrp_csize = sc->sc_brtmax;
  
          return 0;
  }
  
  static int
  bridge_ioctl_gifs(struct bridge_softc *sc, void *arg)
  {
          struct ifbifconf *bifc = arg;
          struct bridge_iflist *bif;
          struct ifbreq *breqs;
          int i, count, error = 0;
  
  retry:
          BRIDGE_LOCK(sc);
          count = 0;
          BRIDGE_IFLIST_WRITER_FOREACH(bif, sc)
                  count++;
          BRIDGE_UNLOCK(sc);
  
          if (count == 0) {
                  bifc->ifbic_len = 0;
                  return 0;
          }
  
          if (bifc->ifbic_len == 0 || bifc->ifbic_len < (sizeof(*breqs) * count)) {
                  /* Tell that a larger buffer is needed */
                  bifc->ifbic_len = sizeof(*breqs) * count;
                  return 0;
          }
  
          breqs = kmem_alloc(sizeof(*breqs) * count, KM_SLEEP);
  
          BRIDGE_LOCK(sc);
  
          i = 0;
          BRIDGE_IFLIST_WRITER_FOREACH(bif, sc)
                  i++;
          if (i > count) {
                  /*
                   * The number of members has been increased.
                   * We need more memory!
                   */
                  BRIDGE_UNLOCK(sc);
                  kmem_free(breqs, sizeof(*breqs) * count);
                  goto retry;
          }
  
          i = 0;
          BRIDGE_IFLIST_WRITER_FOREACH(bif, sc) {
                  struct ifbreq *breq = &breqs[i++];
                  memset(breq, 0, sizeof(*breq));
  
                  strlcpy(breq->ifbr_ifsname, bif->bif_ifp->if_xname,
                      sizeof(breq->ifbr_ifsname));
                  breq->ifbr_ifsflags = bif->bif_flags;
                  breq->ifbr_state = bif->bif_state;
                  breq->ifbr_priority = bif->bif_priority;
                  breq->ifbr_path_cost = bif->bif_path_cost;
                  breq->ifbr_portno = bif->bif_ifp->if_index & 0xff;
          }
  
          /* Don't call copyout with holding the mutex */
          BRIDGE_UNLOCK(sc);
  
          for (i = 0; i < count; i++) {
                  error = copyout(&breqs[i], bifc->ifbic_req + i, sizeof(*breqs));
                  if (error)
                          break;
          }
          bifc->ifbic_len = sizeof(*breqs) * i;
  
          kmem_free(breqs, sizeof(*breqs) * count);
  
          return error;
  }
  
  static int
  bridge_ioctl_rts(struct bridge_softc *sc, void *arg)
  {
          struct ifbaconf *bac = arg;
          struct bridge_rtnode *brt;
          struct ifbareq bareq;
          int count = 0, error = 0, len;
  
          if (bac->ifbac_len == 0)
                  return 0;
  
          BRIDGE_RT_LOCK(sc);
  
          /* The passed buffer is not enough, tell a required size. */
          if (bac->ifbac_len < (sizeof(bareq) * sc->sc_brtcnt)) {
                  count = sc->sc_brtcnt;
                  goto out;
          }
  
          len = bac->ifbac_len;
          BRIDGE_RTLIST_WRITER_FOREACH(brt, sc) {
                  if (len < sizeof(bareq))
                          goto out;
                  memset(&bareq, 0, sizeof(bareq));
                  strlcpy(bareq.ifba_ifsname, brt->brt_ifp->if_xname,
                      sizeof(bareq.ifba_ifsname));
                  memcpy(bareq.ifba_dst, brt->brt_addr, sizeof(brt->brt_addr));
                  if ((brt->brt_flags & IFBAF_TYPEMASK) == IFBAF_DYNAMIC) {
                          bareq.ifba_expire = brt->brt_expire - time_uptime;
                  } else
                          bareq.ifba_expire = 0;
                  bareq.ifba_flags = brt->brt_flags;
  
                  error = copyout(&bareq, bac->ifbac_req + count, sizeof(bareq));
                  if (error)
                          goto out;
                  count++;
                  len -= sizeof(bareq);
          }
  out:
          BRIDGE_RT_UNLOCK(sc);
  
          bac->ifbac_len = sizeof(bareq) * count;
          return error;
  }
  
  static int
  bridge_ioctl_saddr(struct bridge_softc *sc, void *arg)
  {
          struct ifbareq *req = arg;
          struct bridge_iflist *bif;
          int error;
          struct psref psref;
  
          bif = bridge_lookup_member(sc, req->ifba_ifsname, &psref);
          if (bif == NULL)
                  return ENOENT;
  
          error = bridge_rtupdate(sc, req->ifba_dst, bif->bif_ifp, 1,
              req->ifba_flags);
  
          bridge_release_member(sc, bif, &psref);
  
          return error;
  }
  
  static int
  bridge_ioctl_sto(struct bridge_softc *sc, void *arg)
  {
          struct ifbrparam *param = arg;
  
          sc->sc_brttimeout = param->ifbrp_ctime;
  
          return 0;
  }
  
  static int
  bridge_ioctl_gto(struct bridge_softc *sc, void *arg)
  {
          struct ifbrparam *param = arg;
  
          param->ifbrp_ctime = sc->sc_brttimeout;
  
          return 0;
  }
  
  static int
  bridge_ioctl_daddr(struct bridge_softc *sc, void *arg)
  {
          struct ifbareq *req = arg;
  
          return (bridge_rtdaddr(sc, req->ifba_dst));
  }
  
  static int
  bridge_ioctl_flush(struct bridge_softc *sc, void *arg)
  {
          struct ifbreq *req = arg;
  
          bridge_rtflush(sc, req->ifbr_ifsflags);
  
          return 0;
  }
  
  static int
  bridge_ioctl_gpri(struct bridge_softc *sc, void *arg)
  {
          struct ifbrparam *param = arg;
  
          param->ifbrp_prio = sc->sc_bridge_priority;
  
          return 0;
  }
  
  static int
  bridge_ioctl_spri(struct bridge_softc *sc, void *arg)
  {
          struct ifbrparam *param = arg;
  
          sc->sc_bridge_priority = param->ifbrp_prio;
  
          if (sc->sc_if.if_flags & IFF_RUNNING)
                  bstp_initialization(sc);
  
          return 0;
  }
  
  static int
  bridge_ioctl_ght(struct bridge_softc *sc, void *arg)
  {
          struct ifbrparam *param = arg;
  
          param->ifbrp_hellotime = sc->sc_bridge_hello_time >> 8;
  
          return 0;
  }
  
  static int
  bridge_ioctl_sht(struct bridge_softc *sc, void *arg)
  {
          struct ifbrparam *param = arg;
  
          if (param->ifbrp_hellotime == 0)
                  return EINVAL;
          sc->sc_bridge_hello_time = param->ifbrp_hellotime << 8;
  
          if (sc->sc_if.if_flags & IFF_RUNNING)
                  bstp_initialization(sc);
  
          return 0;
  }
  
  static int
  bridge_ioctl_gfd(struct bridge_softc *sc, void *arg)
  {
          struct ifbrparam *param = arg;
  
          param->ifbrp_fwddelay = sc->sc_bridge_forward_delay >> 8;
  
          return 0;
  }
  
  static int
  bridge_ioctl_sfd(struct bridge_softc *sc, void *arg)
  {
          struct ifbrparam *param = arg;
  
          if (param->ifbrp_fwddelay == 0)
                  return EINVAL;
          sc->sc_bridge_forward_delay = param->ifbrp_fwddelay << 8;
  
          if (sc->sc_if.if_flags & IFF_RUNNING)
                  bstp_initialization(sc);
  
          return 0;
  }
  
  static int
  bridge_ioctl_gma(struct bridge_softc *sc, void *arg)
  {
          struct ifbrparam *param = arg;
  
          param->ifbrp_maxage = sc->sc_bridge_max_age >> 8;
  
          return 0;
  }
  
  static int
  bridge_ioctl_sma(struct bridge_softc *sc, void *arg)
  {
          struct ifbrparam *param = arg;
  
          if (param->ifbrp_maxage == 0)
                  return EINVAL;
          sc->sc_bridge_max_age = param->ifbrp_maxage << 8;
  
          if (sc->sc_if.if_flags & IFF_RUNNING)
                  bstp_initialization(sc);
  
          return 0;
  }
  
  static int
  bridge_ioctl_sifprio(struct bridge_softc *sc, void *arg)
  {
          struct ifbreq *req = arg;
          struct bridge_iflist *bif;
          struct psref psref;
  
          bif = bridge_lookup_member(sc, req->ifbr_ifsname, &psref);
          if (bif == NULL)
                  return ENOENT;
  
          bif->bif_priority = req->ifbr_priority;
  
          if (sc->sc_if.if_flags & IFF_RUNNING)
                  bstp_initialization(sc);
  
          bridge_release_member(sc, bif, &psref);
  
          return 0;
  }
  
  static int
  bridge_ioctl_gfilt(struct bridge_softc *sc, void *arg)
  {
          struct ifbrparam *param = arg;
  
          param->ifbrp_filter = sc->sc_filter_flags;
  
          return 0;
  }
  
  static int
  bridge_ioctl_sfilt(struct bridge_softc *sc, void *arg)
  {
          struct ifbrparam *param = arg;
          uint32_t nflags, oflags;
  
          if (param->ifbrp_filter & ~IFBF_FILT_MASK)
                  return EINVAL;
  
          nflags = param->ifbrp_filter;
          oflags = sc->sc_filter_flags;
  
          if ((nflags & IFBF_FILT_USEIPF) && !(oflags & IFBF_FILT_USEIPF)) {
                  pfil_add_hook((void *)bridge_ipf, NULL, PFIL_IN|PFIL_OUT,
                          sc->sc_if.if_pfil);
          }
          if (!(nflags & IFBF_FILT_USEIPF) && (oflags & IFBF_FILT_USEIPF)) {
                  pfil_remove_hook((void *)bridge_ipf, NULL, PFIL_IN|PFIL_OUT,
                          sc->sc_if.if_pfil);
          }
  
          sc->sc_filter_flags = nflags;
  
          return 0;
  }
  
  static int
  bridge_ioctl_sifcost(struct bridge_softc *sc, void *arg)
  {
          struct ifbreq *req = arg;
          struct bridge_iflist *bif;
          struct psref psref;
  
          bif = bridge_lookup_member(sc, req->ifbr_ifsname, &psref);
          if (bif == NULL)
                  return ENOENT;
  
          bif->bif_path_cost = req->ifbr_path_cost;
  
          if (sc->sc_if.if_flags & IFF_RUNNING)
                  bstp_initialization(sc);
  
          bridge_release_member(sc, bif, &psref);
  
          return 0;
  }
  
  /*
   * bridge_ifdetach:
   *
   *      Detach an interface from a bridge.  Called when a member
   *      interface is detaching.
   */
  static void
  bridge_ifdetach(void *xifs)
  {
          struct ifnet *ifs;
          struct bridge_softc *sc;
          struct ifbreq breq;
  
          ifs = (struct ifnet *)xifs;
          sc = ifs->if_bridge;
  
          /* ioctl_lock should prevent this from happening */
          KASSERT(sc != NULL);
  
          memset(&breq, 0, sizeof(breq));
          strlcpy(breq.ifbr_ifsname, ifs->if_xname, sizeof(breq.ifbr_ifsname));
  
          (void) bridge_ioctl_del(sc, &breq);
  }
  
  /*
   * bridge_init:
   *
   *      Initialize a bridge interface.
   */
  static int
  bridge_init(struct ifnet *ifp)
  {
          struct bridge_softc *sc = ifp->if_softc;
  
          KASSERT((ifp->if_flags & IFF_RUNNING) == 0);
  
          callout_reset(&sc->sc_brcallout, bridge_rtable_prune_period * hz,
              bridge_timer, sc);
          bstp_initialization(sc);
  
          ifp->if_flags |= IFF_RUNNING;
          return 0;
  }
  
  /*
   * bridge_stop:
   *
   *      Stop the bridge interface.
   */
  static void
  bridge_stop(struct ifnet *ifp, int disable)
  {
          struct bridge_softc *sc = ifp->if_softc;
  
          KASSERT((ifp->if_flags & IFF_RUNNING) != 0);
          ifp->if_flags &= ~IFF_RUNNING;
  
          callout_halt(&sc->sc_brcallout, NULL);
          workqueue_wait(sc->sc_rtage_wq, &sc->sc_rtage_wk);
          bstp_stop(sc);
          bridge_rtflush(sc, IFBF_FLUSHDYN);
  }
  
  /*
   * bridge_enqueue:
   *
   *      Enqueue a packet on a bridge member interface.
   */
  void
  bridge_enqueue(struct bridge_softc *sc, struct ifnet *dst_ifp, struct mbuf *m,
      int runfilt)
  {
          int len, error;
          short mflags;
  
          if (runfilt) {
                  if (pfil_run_hooks(sc->sc_if.if_pfil, &m,
                      dst_ifp, PFIL_OUT) != 0) {
                          if (m != NULL)
                                  m_freem(m);
                          return;
                  }
                  if (m == NULL)
                          return;
          }
  
  #ifdef ALTQ
          KERNEL_LOCK(1, NULL);
          /*
           * If ALTQ is enabled on the member interface, do
           * classification; the queueing discipline might
           * not require classification, but might require
           * the address family/header pointer in the pktattr.
           */
          if (ALTQ_IS_ENABLED(&dst_ifp->if_snd)) {
                  /* XXX IFT_ETHER */
                  altq_etherclassify(&dst_ifp->if_snd, m);
          }
          KERNEL_UNLOCK_ONE(NULL);
  #endif /* ALTQ */
  
          if (vlan_has_tag(m) &&
              !vlan_is_hwtag_enabled(dst_ifp)) {
                  (void)ether_inject_vlantag(&m, ETHERTYPE_VLAN,
                      vlan_get_tag(m));
                  if (m == NULL) {
                          if_statinc(&sc->sc_if, if_oerrors);
                          return;
                  }
          }
  
          len = m->m_pkthdr.len;
          mflags = m->m_flags;
  
          error = if_transmit_lock(dst_ifp, m);
          if (error) {
                  /* mbuf is already freed */
                  if_statinc(&sc->sc_if, if_oerrors);
                  return;
          }
  
          net_stat_ref_t nsr = IF_STAT_GETREF(&sc->sc_if);
          if_statinc_ref(nsr, if_opackets);
          if_statadd_ref(nsr, if_obytes, len);
          if (mflags & M_MCAST)
                  if_statinc_ref(nsr, if_omcasts);
          IF_STAT_PUTREF(&sc->sc_if);
  }
  
  /*
   * bridge_output:
   *
   *      Send output from a bridge member interface.  This
   *      performs the bridging function for locally originated
   *      packets.
   *
   *      The mbuf has the Ethernet header already attached.  We must
   *      enqueue or free the mbuf before returning.
   */
  int
  bridge_output(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *sa,
      const struct rtentry *rt)
  {
          struct ether_header *eh;
          struct ifnet *dst_if;
          struct bridge_softc *sc;
          struct mbuf *n;
          int s;
  
          /*
           * bridge_output() is called from ether_output(), furthermore
           * ifp argument doesn't point to bridge(4). So, don't assert
           * IFEF_MPSAFE here.
           */
  
          KASSERT(m->m_len >= ETHER_HDR_LEN);
  
          eh = mtod(m, struct ether_header *);
          sc = ifp->if_bridge;
  
          if (ETHER_IS_MULTICAST(eh->ether_dhost)) {
                  if (memcmp(etherbroadcastaddr,
                      eh->ether_dhost, ETHER_ADDR_LEN) == 0)
                          m->m_flags |= M_BCAST;
                  else
                          m->m_flags |= M_MCAST;
          }
  
          /*
           * If bridge is down, but the original output interface is up,
           * go ahead and send out that interface.  Otherwise, the packet
           * is dropped below.
           */
          if (__predict_false(sc == NULL) ||
              (sc->sc_if.if_flags & IFF_RUNNING) == 0) {
                  dst_if = ifp;
                  goto unicast_asis;
          }
  
          /*
           * If the packet is a multicast, or we don't know a better way to
           * get there, send to all interfaces.
           */
          if ((m->m_flags & (M_MCAST | M_BCAST)) != 0)
                  dst_if = NULL;
          else
                  dst_if = bridge_rtlookup(sc, eh->ether_dhost);
  
          /*
           * In general, we need to handle TX offload in software before
           * enqueueing a packet. However, we can send it as is in the
           * cases of unicast via (1) the source interface, or (2) an
           * interface which supports the specified offload options.
           * For multicast or broadcast, send it as is only if (3) all
           * the member interfaces support the specified options.
           */
  
          /*
           * Unicast via the source interface.
           */
          if (dst_if == ifp)
                  goto unicast_asis;
  
          /*
           * Unicast via other interface.
           */
          if (dst_if != NULL) {
                  KASSERT(m->m_flags & M_PKTHDR);
                  if (TX_OFFLOAD_SUPPORTED(dst_if->if_csum_flags_tx,
                      m->m_pkthdr.csum_flags)) {
                          /*
                           * Unicast via an interface which supports the
                           * specified offload options.
                           */
                          goto unicast_asis;
                  }
  
                  /*
                   * Handle TX offload in software. For TSO, a packet is
                   * split into multiple chunks. Thus, the return value of
                   * ether_sw_offload_tx() is mbuf queue consists of them.
                   */
                  m = ether_sw_offload_tx(ifp, m);
                  if (m == NULL)
                          return 0;
  
                  do {
                          n = m->m_nextpkt;
                          if ((dst_if->if_flags & IFF_RUNNING) == 0)
                                  m_freem(m);
                          else
                                  bridge_enqueue(sc, dst_if, m, 0);
                          m = n;
                  } while (m != NULL);
  
                  return 0;
          }
  
          /*
           * Multicast or broadcast.
           */
          if (TX_OFFLOAD_SUPPORTED(sc->sc_csum_flags_tx,
              m->m_pkthdr.csum_flags)) {
                  /*
                   * Specified TX offload options are supported by all
                   * the member interfaces of this bridge.
                   */
                  m->m_nextpkt = NULL;    /* XXX */
          } else {
                  /*
                   * Otherwise, handle TX offload in software.
                   */
                  m = ether_sw_offload_tx(ifp, m);
                  if (m == NULL)
                          return 0;
          }
  
          do {
                  /* XXX Should call bridge_broadcast, but there are locking
                   * issues which need resolving first. */
                  struct bridge_iflist *bif;
                  struct mbuf *mc;
                  bool used = false;
  
                  n = m->m_nextpkt;
  
                  BRIDGE_PSZ_RENTER(s);
                  BRIDGE_IFLIST_READER_FOREACH(bif, sc) {
                          struct psref psref;
  
                          bridge_acquire_member(sc, bif, &psref);
                          BRIDGE_PSZ_REXIT(s);
  
                          dst_if = bif->bif_ifp;
                          if ((dst_if->if_flags & IFF_RUNNING) == 0)
                                  goto next;
  
                          /*
                           * If this is not the original output interface,
                           * and the interface is participating in spanning
                           * tree, make sure the port is in a state that
                           * allows forwarding.
                           */
                          if (dst_if != ifp &&
                              (bif->bif_flags & IFBIF_STP) != 0) {
                                  switch (bif->bif_state) {
                                  case BSTP_IFSTATE_BLOCKING:
                                  case BSTP_IFSTATE_LISTENING:
                                  case BSTP_IFSTATE_DISABLED:
                                          goto next;
                                  }
                          }
  
                          if (PSLIST_READER_NEXT(bif, struct bridge_iflist,
                              bif_next) == NULL &&
                              ((m->m_flags & (M_MCAST | M_BCAST)) == 0 ||
                              dst_if == ifp))
                          {
                                  used = true;
                                  mc = m;
                          } else {
                                  mc = m_copypacket(m, M_DONTWAIT);
                                  if (mc == NULL) {
                                          if_statinc(&sc->sc_if, if_oerrors);
                                          goto next;
                                  }
                          }
  
                          bridge_enqueue(sc, dst_if, mc, 0);
  
                          if ((m->m_flags & (M_MCAST | M_BCAST)) != 0 &&
                              dst_if != ifp)
                          {
                                  if (PSLIST_READER_NEXT(bif,
                                      struct bridge_iflist, bif_next) == NULL)
                                  {
                                          used = true;
                                          mc = m;
                                  } else {
                                          mc = m_copypacket(m, M_DONTWAIT);
                                          if (mc == NULL) {
                                                  if_statinc(&sc->sc_if,
                                                      if_oerrors);
                                                  goto next;
                                          }
                                  }
  
                                  m_set_rcvif(mc, dst_if);
                                  mc->m_flags &= ~M_PROMISC;
  
                                  const int _s = splsoftnet();
                                  KERNEL_LOCK_UNLESS_IFP_MPSAFE(dst_if);
                                  ether_input(dst_if, mc);
                                  KERNEL_UNLOCK_UNLESS_IFP_MPSAFE(dst_if);
                                  splx(_s);
                          }
  
  next:
                          BRIDGE_PSZ_RENTER(s);
                          bridge_release_member(sc, bif, &psref);
  
                          /* Guarantee we don't re-enter the loop as we already
                           * decided we're at the end. */
                          if (used)
                                  break;
                  }
                  BRIDGE_PSZ_REXIT(s);
  
                  if (!used)
                          m_freem(m);
  
                  m = n;
          } while (m != NULL);
          return 0;
  
  unicast_asis:
          /*
           * XXX Spanning tree consideration here?
           */
          if ((dst_if->if_flags & IFF_RUNNING) == 0)
                  m_freem(m);
          else
                  bridge_enqueue(sc, dst_if, m, 0);
          return 0;
  }
  
  /*
   * bridge_start:
   *
   *      Start output on a bridge.
   *
   *      NOTE: This routine should never be called in this implementation.
   */
  static void
  bridge_start(struct ifnet *ifp)
  {
  
          printf("%s: bridge_start() called\n", ifp->if_xname);
  }
  
  /*
   * bridge_forward:
   *
   *      The forwarding function of the bridge.
   */
  static void
  bridge_forward(struct bridge_softc *sc, struct mbuf *m)
  {
          struct bridge_iflist *bif;
          struct ifnet *src_if, *dst_if;
          struct ether_header *eh;
          struct psref psref;
          struct psref psref_src;
          DECLARE_LOCK_VARIABLE;
  
          if ((sc->sc_if.if_flags & IFF_RUNNING) == 0)
                  return;
  
          src_if = m_get_rcvif_psref(m, &psref_src);
          if (src_if == NULL) {
                  /* Interface is being destroyed? */
                  m_freem(m);
                  goto out;
          }
  
          if_statadd2(&sc->sc_if, if_ipackets, 1, if_ibytes, m->m_pkthdr.len);
  
          /*
           * Look up the bridge_iflist.
           */
          bif = bridge_lookup_member_if(sc, src_if, &psref);
          if (bif == NULL) {
                  /* Interface is not a bridge member (anymore?) */
                  m_freem(m);
                  goto out;
          }
  
          if (bif->bif_flags & IFBIF_STP) {
                  switch (bif->bif_state) {
                  case BSTP_IFSTATE_BLOCKING:
                  case BSTP_IFSTATE_LISTENING:
                  case BSTP_IFSTATE_DISABLED:
                          m_freem(m);
                          bridge_release_member(sc, bif, &psref);
                          goto out;
                  }
          }
  
          eh = mtod(m, struct ether_header *);
  
          /*
           * If the interface is learning, and the source
           * address is valid and not multicast, record
           * the address.
           */
          if ((bif->bif_flags & IFBIF_LEARNING) != 0 &&
              ETHER_IS_MULTICAST(eh->ether_shost) == 0 &&
              (eh->ether_shost[0] == 0 &&
               eh->ether_shost[1] == 0 &&
               eh->ether_shost[2] == 0 &&
               eh->ether_shost[3] == 0 &&
               eh->ether_shost[4] == 0 &&
               eh->ether_shost[5] == 0) == 0) {
                  (void) bridge_rtupdate(sc, eh->ether_shost,
                      src_if, 0, IFBAF_DYNAMIC);
          }
  
          if ((bif->bif_flags & IFBIF_STP) != 0 &&
              bif->bif_state == BSTP_IFSTATE_LEARNING) {
                  m_freem(m);
                  bridge_release_member(sc, bif, &psref);
                  goto out;
          }
  
          bridge_release_member(sc, bif, &psref);
  
          /*
           * At this point, the port either doesn't participate
           * in spanning tree or it is in the forwarding state.
           */
  
          /*
           * If the packet is unicast, destined for someone on
           * "this" side of the bridge, drop it.
           */
          if ((m->m_flags & (M_BCAST|M_MCAST)) == 0) {
                  dst_if = bridge_rtlookup(sc, eh->ether_dhost);
                  if (src_if == dst_if) {
                          m_freem(m);
                          goto out;
                  }
          } else {
                  /* ...forward it to all interfaces. */
                  if_statinc(&sc->sc_if, if_imcasts);
                  dst_if = NULL;
          }
  
          if (pfil_run_hooks(sc->sc_if.if_pfil, &m, src_if, PFIL_IN) != 0) {
                  if (m != NULL)
                          m_freem(m);
                  goto out;
          }
          if (m == NULL)
                  goto out;
  
          if (dst_if == NULL) {
                  bridge_broadcast(sc, src_if, m);
                  goto out;
          }
  
          m_put_rcvif_psref(src_if, &psref_src);
          src_if = NULL;
  
          /*
           * At this point, we're dealing with a unicast frame
           * going to a different interface.
           */
          if ((dst_if->if_flags & IFF_RUNNING) == 0) {
                  m_freem(m);
                  goto out;
          }
  
          bif = bridge_lookup_member_if(sc, dst_if, &psref);
          if (bif == NULL) {
                  /* Not a member of the bridge (anymore?) */
                  m_freem(m);
                  goto out;
          }
  
          if (bif->bif_flags & IFBIF_STP) {
                  switch (bif->bif_state) {
                  case BSTP_IFSTATE_DISABLED:
                  case BSTP_IFSTATE_BLOCKING:
                          m_freem(m);
                          bridge_release_member(sc, bif, &psref);
                          goto out;
                  }
          }
  
          bridge_release_member(sc, bif, &psref);
  
          /*
           * Before enqueueing this packet to the destination interface,
           * clear any in-bound checksum flags to prevent them from being
           * misused as out-bound flags.
           */
          m->m_pkthdr.csum_flags = 0;
  
          ACQUIRE_GLOBAL_LOCKS();
          bridge_enqueue(sc, dst_if, m, 1);
          RELEASE_GLOBAL_LOCKS();
  out:
          if (src_if != NULL)
                  m_put_rcvif_psref(src_if, &psref_src);
          return;
  }
  
  static bool
  bstp_state_before_learning(struct bridge_iflist *bif)
  {
          if (bif->bif_flags & IFBIF_STP) {
                  switch (bif->bif_state) {
                  case BSTP_IFSTATE_BLOCKING:
                  case BSTP_IFSTATE_LISTENING:
                  case BSTP_IFSTATE_DISABLED:
                          return true;
                  }
          }
          return false;
  }
  
  static bool
  bridge_ourether(struct bridge_iflist *bif, struct ether_header *eh, int src)
  {
          uint8_t *ether = src ? eh->ether_shost : eh->ether_dhost;
  
          if (memcmp(CLLADDR(bif->bif_ifp->if_sadl), ether, ETHER_ADDR_LEN) == 0
  #if NCARP > 0
              || (bif->bif_ifp->if_carp &&
                  carp_ourether(bif->bif_ifp->if_carp, eh, IFT_ETHER, src) != NULL)
  #endif /* NCARP > 0 */
              )
                  return true;
  
          return false;
  }
  
  /*
   * bridge_input:
   *
   *      Receive input from a member interface.  Queue the packet for
   *      bridging if it is not for us.
   */
  static void
  bridge_input(struct ifnet *ifp, struct mbuf *m)
  {
          struct bridge_softc *sc = ifp->if_bridge;
          struct bridge_iflist *bif;
          struct ether_header *eh;
          struct psref psref;
          int bound;
          DECLARE_LOCK_VARIABLE;
  
          KASSERT(!cpu_intr_p());
  
          if (__predict_false(sc == NULL) ||
              (sc->sc_if.if_flags & IFF_RUNNING) == 0) {
                  ACQUIRE_GLOBAL_LOCKS();
                  ether_input(ifp, m);
                  RELEASE_GLOBAL_LOCKS();
                  return;
          }
  
          bound = curlwp_bind();
          bif = bridge_lookup_member_if(sc, ifp, &psref);
          if (bif == NULL) {
                  curlwp_bindx(bound);
                  ACQUIRE_GLOBAL_LOCKS();
                  ether_input(ifp, m);
                  RELEASE_GLOBAL_LOCKS();
                  return;
          }
  
          eh = mtod(m, struct ether_header *);
  
          if (ETHER_IS_MULTICAST(eh->ether_dhost)) {
                  if (memcmp(etherbroadcastaddr,
                      eh->ether_dhost, ETHER_ADDR_LEN) == 0)
                          m->m_flags |= M_BCAST;
                  else
                          m->m_flags |= M_MCAST;
          }
  
          /*
           * A 'fast' path for packets addressed to interfaces that are
           * part of this bridge.
           */
          if (!(m->m_flags & (M_BCAST|M_MCAST)) &&
              !bstp_state_before_learning(bif)) {
                  struct bridge_iflist *_bif;
                  struct ifnet *_ifp = NULL;
                  int s;
                  struct psref _psref;
  
                  BRIDGE_PSZ_RENTER(s);
                  BRIDGE_IFLIST_READER_FOREACH(_bif, sc) {
                          /* It is destined for us. */
                          if (bridge_ourether(_bif, eh, 0)) {
                                  bridge_acquire_member(sc, _bif, &_psref);
                                  BRIDGE_PSZ_REXIT(s);
                                  if (_bif->bif_flags & IFBIF_LEARNING)
                                          (void) bridge_rtupdate(sc,
                                              eh->ether_shost, ifp, 0, IFBAF_DYNAMIC);
                                  m_set_rcvif(m, _bif->bif_ifp);
                                  _ifp = _bif->bif_ifp;
                                  bridge_release_member(sc, _bif, &_psref);
                                  goto out;
                          }
  
                          /* We just received a packet that we sent out. */
                          if (bridge_ourether(_bif, eh, 1))
                                  break;
                  }
                  BRIDGE_PSZ_REXIT(s);
  out:
  
                  if (_bif != NULL) {
                          bridge_release_member(sc, bif, &psref);
                          curlwp_bindx(bound);
                          if (_ifp != NULL) {
                                  m->m_flags &= ~M_PROMISC;
                                  ACQUIRE_GLOBAL_LOCKS();
                                  ether_input(_ifp, m);
                                  RELEASE_GLOBAL_LOCKS();
                          } else
                                  m_freem(m);
                          return;
                  }
          }
  
          /* Tap off 802.1D packets; they do not get forwarded. */
          if (bif->bif_flags & IFBIF_STP &&
              memcmp(eh->ether_dhost, bstp_etheraddr, ETHER_ADDR_LEN) == 0) {
                  bstp_input(sc, bif, m);
                  bridge_release_member(sc, bif, &psref);
                  curlwp_bindx(bound);
                  return;
          }
  
          /*
           * A normal switch would discard the packet here, but that's not what
           * we've done historically. This also prevents some obnoxious behaviour.
           */
          if (bstp_state_before_learning(bif)) {
                  bridge_release_member(sc, bif, &psref);
                  curlwp_bindx(bound);
                  ACQUIRE_GLOBAL_LOCKS();
                  ether_input(ifp, m);
                  RELEASE_GLOBAL_LOCKS();
                  return;
          }
  
          bridge_release_member(sc, bif, &psref);
  
          bridge_forward(sc, m);
  
          curlwp_bindx(bound);
  }
  
  /*
   * bridge_broadcast:
   *
   *      Send a frame to all interfaces that are members of
   *      the bridge, except for the one on which the packet
   *      arrived.
   */
  static void
  bridge_broadcast(struct bridge_softc *sc, struct ifnet *src_if,
      struct mbuf *m)
  {
          struct bridge_iflist *bif;
          struct mbuf *mc;
          struct ifnet *dst_if;
          bool bmcast;
          int s;
          DECLARE_LOCK_VARIABLE;
  
          bmcast = m->m_flags & (M_BCAST|M_MCAST);
  
          BRIDGE_PSZ_RENTER(s);
          BRIDGE_IFLIST_READER_FOREACH(bif, sc) {
                  struct psref psref;
  
                  bridge_acquire_member(sc, bif, &psref);
                  BRIDGE_PSZ_REXIT(s);
  
                  dst_if = bif->bif_ifp;
  
                  if (bif->bif_flags & IFBIF_STP) {
                          switch (bif->bif_state) {
                          case BSTP_IFSTATE_BLOCKING:
                          case BSTP_IFSTATE_DISABLED:
                                  goto next;
                          }
                  }
  
                  if ((bif->bif_flags & IFBIF_DISCOVER) == 0 && !bmcast)
                          goto next;
  
                  if ((dst_if->if_flags & IFF_RUNNING) == 0)
                          goto next;
  
                  if (dst_if != src_if) {
                          mc = m_copypacket(m, M_DONTWAIT);
                          if (mc == NULL) {
                                  if_statinc(&sc->sc_if, if_oerrors);
                                  goto next;
                          }
                          /*
                           * Before enqueueing this packet to the destination
                           * interface, clear any in-bound checksum flags to
                           * prevent them from being misused as out-bound flags.
                           */
                          mc->m_pkthdr.csum_flags = 0;
  
                          ACQUIRE_GLOBAL_LOCKS();
                          bridge_enqueue(sc, dst_if, mc, 1);
                          RELEASE_GLOBAL_LOCKS();
                  }
  
                  if (bmcast) {
                          mc = m_copypacket(m, M_DONTWAIT);
                          if (mc == NULL) {
                                  if_statinc(&sc->sc_if, if_oerrors);
                                  goto next;
                          }
                          /*
                           * Before enqueueing this packet to the destination
                           * interface, clear any in-bound checksum flags to
                           * prevent them from being misused as out-bound flags.
                           */
                          mc->m_pkthdr.csum_flags = 0;
  
                          m_set_rcvif(mc, dst_if);
                          mc->m_flags &= ~M_PROMISC;
  
                          ACQUIRE_GLOBAL_LOCKS();
                          ether_input(dst_if, mc);
                          RELEASE_GLOBAL_LOCKS();
                  }
  next:
                  BRIDGE_PSZ_RENTER(s);
                  bridge_release_member(sc, bif, &psref);
          }
          BRIDGE_PSZ_REXIT(s);
  
          m_freem(m);
  }
  
  static int
  bridge_rtalloc(struct bridge_softc *sc, const uint8_t *dst,
      struct bridge_rtnode **brtp)
  {
          struct bridge_rtnode *brt;
          int error;
  
          if (sc->sc_brtcnt >= sc->sc_brtmax)
                  return ENOSPC;
  
          /*
           * Allocate a new bridge forwarding node, and
           * initialize the expiration time and Ethernet
           * address.
           */
          brt = pool_get(&bridge_rtnode_pool, PR_NOWAIT);
          if (brt == NULL)
                  return ENOMEM;
  
          memset(brt, 0, sizeof(*brt));
          brt->brt_expire = time_uptime + sc->sc_brttimeout;
          brt->brt_flags = IFBAF_DYNAMIC;
          memcpy(brt->brt_addr, dst, ETHER_ADDR_LEN);
          PSLIST_ENTRY_INIT(brt, brt_list);
          PSLIST_ENTRY_INIT(brt, brt_hash);
  
          BRIDGE_RT_LOCK(sc);
          error = bridge_rtnode_insert(sc, brt);
          BRIDGE_RT_UNLOCK(sc);
  
          if (error != 0) {
                  pool_put(&bridge_rtnode_pool, brt);
                  return error;
          }
  
          *brtp = brt;
          return 0;
  }
  
  /*
   * bridge_rtupdate:
   *
   *      Add a bridge routing entry.
   */
  static int
  bridge_rtupdate(struct bridge_softc *sc, const uint8_t *dst,
      struct ifnet *dst_if, int setflags, uint8_t flags)
  {
          struct bridge_rtnode *brt;
          int s;
  
  again:
          /*
           * A route for this destination might already exist.  If so,
           * update it, otherwise create a new one.
           */
          BRIDGE_RT_RENTER(s);
          brt = bridge_rtnode_lookup(sc, dst);
  
          if (brt != NULL) {
                  brt->brt_ifp = dst_if;
                  if (setflags) {
                          brt->brt_flags = flags;
                          if (flags & IFBAF_STATIC)
                                  brt->brt_expire = 0;
                          else
                                  brt->brt_expire = time_uptime + sc->sc_brttimeout;
                  } else {
                          if ((brt->brt_flags & IFBAF_TYPEMASK) == IFBAF_DYNAMIC)
                                  brt->brt_expire = time_uptime + sc->sc_brttimeout;
                  }
          }
          BRIDGE_RT_REXIT(s);
  
          if (brt == NULL) {
                  int r;
  
                  r = bridge_rtalloc(sc, dst, &brt);
                  if (r != 0)
                          return r;
                  goto again;
          }
  
          return 0;
  }
  
  /*
   * bridge_rtlookup:
   *
   *      Lookup the destination interface for an address.
   */
  static struct ifnet *
  bridge_rtlookup(struct bridge_softc *sc, const uint8_t *addr)
  {
          struct bridge_rtnode *brt;
          struct ifnet *ifs = NULL;
          int s;
  
          BRIDGE_RT_RENTER(s);
          brt = bridge_rtnode_lookup(sc, addr);
          if (brt != NULL)
                  ifs = brt->brt_ifp;
          BRIDGE_RT_REXIT(s);
  
          return ifs;
  }
  
  typedef bool (*bridge_iterate_cb_t)
      (struct bridge_softc *, struct bridge_rtnode *, bool *, void *);
  
  /*
   * bridge_rtlist_iterate_remove:
   *
   *      It iterates on sc->sc_rtlist and removes rtnodes of it which func
   *      callback judges to remove. Removals of rtnodes are done in a manner
   *      of pserialize. To this end, all kmem_* operations are placed out of
   *      mutexes.
   */
  static void
  bridge_rtlist_iterate_remove(struct bridge_softc *sc, bridge_iterate_cb_t func, void *arg)
  {
          struct bridge_rtnode *brt;
          struct bridge_rtnode **brt_list;
          int i, count;
  
  retry:
          count = sc->sc_brtcnt;
          if (count == 0)
                  return;
          brt_list = kmem_alloc(sizeof(*brt_list) * count, KM_SLEEP);
  
          BRIDGE_RT_LOCK(sc);
          if (__predict_false(sc->sc_brtcnt > count)) {
                  /* The rtnodes increased, we need more memory */
                  BRIDGE_RT_UNLOCK(sc);
                  kmem_free(brt_list, sizeof(*brt_list) * count);
                  goto retry;
          }
  
          i = 0;
          /*
           * We don't need to use a _SAFE variant here because we know
           * that a removed item keeps its next pointer as-is thanks to
           * pslist(9) and isn't freed in the loop.
           */
          BRIDGE_RTLIST_WRITER_FOREACH(brt, sc) {
                  bool need_break = false;
                  if (func(sc, brt, &need_break, arg)) {
                          bridge_rtnode_remove(sc, brt);
                          brt_list[i++] = brt;
                  }
                  if (need_break)
                          break;
          }
  
          if (i > 0)
                  BRIDGE_RT_PSZ_PERFORM(sc);
          BRIDGE_RT_UNLOCK(sc);
  
          while (--i >= 0)
                  bridge_rtnode_destroy(brt_list[i]);
  
          kmem_free(brt_list, sizeof(*brt_list) * count);
  }
  
  static bool
  bridge_rttrim0_cb(struct bridge_softc *sc, struct bridge_rtnode *brt,
      bool *need_break, void *arg)
  {
          if ((brt->brt_flags & IFBAF_TYPEMASK) == IFBAF_DYNAMIC) {
                  /* Take into account of the subsequent removal */
                  if ((sc->sc_brtcnt - 1) <= sc->sc_brtmax)
                          *need_break = true;
                  return true;
          } else
                  return false;
  }
  
  static void
  bridge_rttrim0(struct bridge_softc *sc)
  {
          bridge_rtlist_iterate_remove(sc, bridge_rttrim0_cb, NULL);
  }
  
  /*
   * bridge_rttrim:
   *
   *      Trim the routine table so that we have a number
   *      of routing entries less than or equal to the
   *      maximum number.
   */
  static void
  bridge_rttrim(struct bridge_softc *sc)
  {
  
          /* Make sure we actually need to do this. */
          if (sc->sc_brtcnt <= sc->sc_brtmax)
                  return;
  
          /* Force an aging cycle; this might trim enough addresses. */
          bridge_rtage(sc);
          if (sc->sc_brtcnt <= sc->sc_brtmax)
                  return;
  
          bridge_rttrim0(sc);
  
          return;
  }
  
  /*
   * bridge_timer:
   *
   *      Aging timer for the bridge.
   */
  static void
  bridge_timer(void *arg)
  {
          struct bridge_softc *sc = arg;
  
          workqueue_enqueue(sc->sc_rtage_wq, &sc->sc_rtage_wk, NULL);
  }
  
  static void
  bridge_rtage_work(struct work *wk, void *arg)
  {
          struct bridge_softc *sc = arg;
  
          KASSERT(wk == &sc->sc_rtage_wk);
  
          bridge_rtage(sc);
  
          if (sc->sc_if.if_flags & IFF_RUNNING)
                  callout_reset(&sc->sc_brcallout,
                      bridge_rtable_prune_period * hz, bridge_timer, sc);
  }
  
  static bool
  bridge_rtage_cb(struct bridge_softc *sc, struct bridge_rtnode *brt,
      bool *need_break, void *arg)
  {
          if ((brt->brt_flags & IFBAF_TYPEMASK) == IFBAF_DYNAMIC &&
              time_uptime >= brt->brt_expire)
                  return true;
          else
                  return false;
  }
  
  /*
   * bridge_rtage:
   *
   *      Perform an aging cycle.
   */
  static void
  bridge_rtage(struct bridge_softc *sc)
  {
          bridge_rtlist_iterate_remove(sc, bridge_rtage_cb, NULL);
  }
  
  
  static bool
  bridge_rtflush_cb(struct bridge_softc *sc, struct bridge_rtnode *brt,
      bool *need_break, void *arg)
  {
          int full = *(int*)arg;
  
          if (full || (brt->brt_flags & IFBAF_TYPEMASK) == IFBAF_DYNAMIC)
                  return true;
          else
                  return false;
  }
  
  /*
   * bridge_rtflush:
   *
   *      Remove all dynamic addresses from the bridge.
   */
  static void
  bridge_rtflush(struct bridge_softc *sc, int full)
  {
          bridge_rtlist_iterate_remove(sc, bridge_rtflush_cb, &full);
  }
  
  /*
   * bridge_rtdaddr:
   *
   *      Remove an address from the table.
   */
  static int
  bridge_rtdaddr(struct bridge_softc *sc, const uint8_t *addr)
  {
          struct bridge_rtnode *brt;
  
          BRIDGE_RT_LOCK(sc);
          if ((brt = bridge_rtnode_lookup(sc, addr)) == NULL) {
                  BRIDGE_RT_UNLOCK(sc);
                  return ENOENT;
          }
          bridge_rtnode_remove(sc, brt);
          BRIDGE_RT_PSZ_PERFORM(sc);
          BRIDGE_RT_UNLOCK(sc);
  
          bridge_rtnode_destroy(brt);
  
          return 0;
  }
  
  /*
   * bridge_rtdelete:
   *
   *      Delete routes to a speicifc member interface.
   */
  static void
  bridge_rtdelete(struct bridge_softc *sc, struct ifnet *ifp)
  {
          struct bridge_rtnode *brt;
  
          /* XXX pserialize_perform for each entry is slow */
  again:
          BRIDGE_RT_LOCK(sc);
          BRIDGE_RTLIST_WRITER_FOREACH(brt, sc) {
                  if (brt->brt_ifp == ifp)
                          break;
          }
          if (brt == NULL) {
                  BRIDGE_RT_UNLOCK(sc);
                  return;
          }
          bridge_rtnode_remove(sc, brt);
          BRIDGE_RT_PSZ_PERFORM(sc);
          BRIDGE_RT_UNLOCK(sc);
  
          bridge_rtnode_destroy(brt);
  
          goto again;
  }
  
  /*
   * bridge_rtable_init:
   *
   *      Initialize the route table for this bridge.
   */
  static void
  bridge_rtable_init(struct bridge_softc *sc)
  {
          int i;
  
          sc->sc_rthash = kmem_alloc(sizeof(*sc->sc_rthash) * BRIDGE_RTHASH_SIZE,
              KM_SLEEP);
  
          for (i = 0; i < BRIDGE_RTHASH_SIZE; i++)
                  PSLIST_INIT(&sc->sc_rthash[i]);
  
          sc->sc_rthash_key = cprng_fast32();
  
          PSLIST_INIT(&sc->sc_rtlist);
  
          sc->sc_rtlist_psz = pserialize_create();
          sc->sc_rtlist_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_SOFTNET);
  }
  
  /*
   * bridge_rtable_fini:
   *
   *      Deconstruct the route table for this bridge.
   */
  static void
  bridge_rtable_fini(struct bridge_softc *sc)
  {
  
          kmem_free(sc->sc_rthash, sizeof(*sc->sc_rthash) * BRIDGE_RTHASH_SIZE);
          mutex_obj_free(sc->sc_rtlist_lock);
          pserialize_destroy(sc->sc_rtlist_psz);
  }
  
  /*
   * The following hash function is adapted from "Hash Functions" by Bob Jenkins
   * ("Algorithm Alley", Dr. Dobbs Journal, September 1997).
   */
  #define mix(a, b, c)                                                    \
  do {                                                                    \
          a -= b; a -= c; a ^= (c >> 13);                                 \
          b -= c; b -= a; b ^= (a << 8);                                  \
          c -= a; c -= b; c ^= (b >> 13);                                 \
          a -= b; a -= c; a ^= (c >> 12);                                 \
          b -= c; b -= a; b ^= (a << 16);                                 \
          c -= a; c -= b; c ^= (b >> 5);                                  \
          a -= b; a -= c; a ^= (c >> 3);                                  \
          b -= c; b -= a; b ^= (a << 10);                                 \
          c -= a; c -= b; c ^= (b >> 15);                                 \
  } while (/*CONSTCOND*/0)
  
  static inline uint32_t
  bridge_rthash(struct bridge_softc *sc, const uint8_t *addr)
  {
          uint32_t a = 0x9e3779b9, b = 0x9e3779b9, c = sc->sc_rthash_key;
  
          b += addr[5] << 8;
          b += addr[4];
          a += (uint32_t)addr[3] << 24;
          a += addr[2] << 16;
          a += addr[1] << 8;
          a += addr[0];
  
          mix(a, b, c);
  
          return (c & BRIDGE_RTHASH_MASK);
  }
  
  #undef mix
  
  /*
   * bridge_rtnode_lookup:
   *
   *      Look up a bridge route node for the specified destination.
   */
  static struct bridge_rtnode *
  bridge_rtnode_lookup(struct bridge_softc *sc, const uint8_t *addr)
  {
          struct bridge_rtnode *brt;
          uint32_t hash;
          int dir;
  
          hash = bridge_rthash(sc, addr);
          BRIDGE_RTHASH_READER_FOREACH(brt, sc, hash) {
                  dir = memcmp(addr, brt->brt_addr, ETHER_ADDR_LEN);
                  if (dir == 0)
                          return brt;
                  if (dir > 0)
                          return NULL;
          }
  
          return NULL;
  }
  
  /*
   * bridge_rtnode_insert:
   *
   *      Insert the specified bridge node into the route table.  We
   *      assume the entry is not already in the table.
   */
  static int
  bridge_rtnode_insert(struct bridge_softc *sc, struct bridge_rtnode *brt)
  {
          struct bridge_rtnode *lbrt, *prev = NULL;
          uint32_t hash;
  
          KASSERT(BRIDGE_RT_LOCKED(sc));
  
          hash = bridge_rthash(sc, brt->brt_addr);
          BRIDGE_RTHASH_WRITER_FOREACH(lbrt, sc, hash) {
                  int dir = memcmp(brt->brt_addr, lbrt->brt_addr, ETHER_ADDR_LEN);
                  if (dir == 0)
                          return EEXIST;
                  if (dir > 0)
                          break;
                  prev = lbrt;
          }
          if (prev == NULL)
                  BRIDGE_RTHASH_WRITER_INSERT_HEAD(sc, hash, brt);
          else
                  BRIDGE_RTHASH_WRITER_INSERT_AFTER(prev, brt);
  
          BRIDGE_RTLIST_WRITER_INSERT_HEAD(sc, brt);
          sc->sc_brtcnt++;
  
          return 0;
  }
  
  /*
   * bridge_rtnode_remove:
   *
   *      Remove a bridge rtnode from the rthash and the rtlist of a bridge.
   */
  static void
  bridge_rtnode_remove(struct bridge_softc *sc, struct bridge_rtnode *brt)
  {
  
          KASSERT(BRIDGE_RT_LOCKED(sc));
  
          BRIDGE_RTHASH_WRITER_REMOVE(brt);
          BRIDGE_RTLIST_WRITER_REMOVE(brt);
          sc->sc_brtcnt--;
  }
  
  /*
   * bridge_rtnode_destroy:
   *
   *      Destroy a bridge rtnode.
   */
  static void
  bridge_rtnode_destroy(struct bridge_rtnode *brt)
  {
  
          PSLIST_ENTRY_DESTROY(brt, brt_list);
          PSLIST_ENTRY_DESTROY(brt, brt_hash);
          pool_put(&bridge_rtnode_pool, brt);
  }
  
  extern pfil_head_t *inet_pfil_hook;                 /* XXX */
  extern pfil_head_t *inet6_pfil_hook;                /* XXX */
  
  /*
   * Send bridge packets through IPF if they are one of the types IPF can deal
   * with, or if they are ARP or REVARP.  (IPF will pass ARP and REVARP without
   * question.)
   */
  static int
  bridge_ipf(void *arg, struct mbuf **mp, struct ifnet *ifp, int dir)
  {
          int snap, error;
          struct ether_header *eh1, eh2;
          struct llc llc1;
          uint16_t ether_type;
  
          snap = 0;
          error = -1;     /* Default error if not error == 0 */
          eh1 = mtod(*mp, struct ether_header *);
          ether_type = ntohs(eh1->ether_type);
  
          /*
           * Check for SNAP/LLC.
           */
          if (ether_type < ETHERMTU) {
                  struct llc *llc2 = (struct llc *)(eh1 + 1);
  
                  if ((*mp)->m_len >= ETHER_HDR_LEN + 8 &&
                      llc2->llc_dsap == LLC_SNAP_LSAP &&
                      llc2->llc_ssap == LLC_SNAP_LSAP &&
                      llc2->llc_control == LLC_UI) {
                          ether_type = htons(llc2->llc_un.type_snap.ether_type);
                          snap = 1;
                  }
          }
  
          /* drop VLAN traffic untagged by hardware offloading */
          if (vlan_has_tag(*mp))
                  goto bad;
  
          /*
           * If we're trying to filter bridge traffic, don't look at anything
           * other than IP and ARP traffic.  If the filter doesn't understand
           * IPv6, don't allow IPv6 through the bridge either.  This is lame
           * since if we really wanted, say, an AppleTalk filter, we are hosed,
           * but of course we don't have an AppleTalk filter to begin with.
           * (Note that since IPF doesn't understand ARP it will pass *ALL*
           * ARP traffic.)
           */
          switch (ether_type) {
                  case ETHERTYPE_ARP:
                  case ETHERTYPE_REVARP:
                          return 0; /* Automatically pass */
                  case ETHERTYPE_IP:
  # ifdef INET6
                  case ETHERTYPE_IPV6:
  # endif /* INET6 */
                          break;
                  default:
                          goto bad;
          }
  
          /* Strip off the Ethernet header and keep a copy. */
          m_copydata(*mp, 0, ETHER_HDR_LEN, (void *) &eh2);
          m_adj(*mp, ETHER_HDR_LEN);
  
          /* Strip off snap header, if present */
          if (snap) {
                  m_copydata(*mp, 0, sizeof(struct llc), (void *) &llc1);
                  m_adj(*mp, sizeof(struct llc));
          }
  
          /*
           * Check basic packet sanity and run IPF through pfil.
           */
          KASSERT(!cpu_intr_p());
          switch (ether_type)
          {
          case ETHERTYPE_IP :
                  error = bridge_ip_checkbasic(mp);
                  if (error == 0)
                          error = pfil_run_hooks(inet_pfil_hook, mp, ifp, dir);
                  break;
  # ifdef INET6
          case ETHERTYPE_IPV6 :
                  error = bridge_ip6_checkbasic(mp);
                  if (error == 0)
                          error = pfil_run_hooks(inet6_pfil_hook, mp, ifp, dir);
                  break;
  # endif
          default :
                  error = 0;
                  break;
          }
  
          if (*mp == NULL)
                  return error;
          if (error != 0)
                  goto bad;
  
          error = -1;
  
          /*
           * Finally, put everything back the way it was and return
           */
          if (snap) {
                  M_PREPEND(*mp, sizeof(struct llc), M_DONTWAIT);
                  if (*mp == NULL)
                          return error;
                  bcopy(&llc1, mtod(*mp, void *), sizeof(struct llc));
          }
  
          M_PREPEND(*mp, ETHER_HDR_LEN, M_DONTWAIT);
          if (*mp == NULL)
                  return error;
          bcopy(&eh2, mtod(*mp, void *), ETHER_HDR_LEN);
  
          return 0;
  
      bad:
          m_freem(*mp);
          *mp = NULL;
          return error;
  }
  
  /*
   * Perform basic checks on header size since
   * IPF assumes ip_input has already processed
   * it for it.  Cut-and-pasted from ip_input.c.
   * Given how simple the IPv6 version is,
   * does the IPv4 version really need to be
   * this complicated?
   *
   * XXX Should we update ipstat here, or not?
   * XXX Right now we update ipstat but not
   * XXX csum_counter.
   */
  static int
  bridge_ip_checkbasic(struct mbuf **mp)
  {
          struct mbuf *m = *mp;
          struct ip *ip;
          int len, hlen;
  
          if (*mp == NULL)
                  return -1;
  
          if (M_GET_ALIGNED_HDR(&m, struct ip, true) != 0) {
                  /* XXXJRT new stat, please */
                  ip_statinc(IP_STAT_TOOSMALL);
                  goto bad;
          }
          ip = mtod(m, struct ip *);
          if (ip == NULL) goto bad;
  
          if (ip->ip_v != IPVERSION) {
                  ip_statinc(IP_STAT_BADVERS);
                  goto bad;
          }
          hlen = ip->ip_hl << 2;
          if (hlen < sizeof(struct ip)) { /* minimum header length */
                  ip_statinc(IP_STAT_BADHLEN);
                  goto bad;
          }
          if (hlen > m->m_len) {
                  if ((m = m_pullup(m, hlen)) == 0) {
                          ip_statinc(IP_STAT_BADHLEN);
                          goto bad;
                  }
                  ip = mtod(m, struct ip *);
                  if (ip == NULL) goto bad;
          }
  
          switch (m->m_pkthdr.csum_flags &
                  ((m_get_rcvif_NOMPSAFE(m)->if_csum_flags_rx & M_CSUM_IPv4) |
                   M_CSUM_IPv4_BAD)) {
          case M_CSUM_IPv4|M_CSUM_IPv4_BAD:
                  /* INET_CSUM_COUNTER_INCR(&ip_hwcsum_bad); */
                  goto bad;
  
          case M_CSUM_IPv4:
                  /* Checksum was okay. */
                  /* INET_CSUM_COUNTER_INCR(&ip_hwcsum_ok); */
                  break;
  
          default:
                  /* Must compute it ourselves. */
                  /* INET_CSUM_COUNTER_INCR(&ip_swcsum); */
                  if (in_cksum(m, hlen) != 0)
                          goto bad;
                  break;
          }
  
          /* Retrieve the packet length. */
          len = ntohs(ip->ip_len);
  
          /*
           * Check for additional length bogosity
           */
          if (len < hlen) {
                  ip_statinc(IP_STAT_BADLEN);
                  goto bad;
          }
  
          /*
           * Check that the amount of data in the buffers
           * is as at least much as the IP header would have us expect.
           * Drop packet if shorter than we expect.
           */
          if (m->m_pkthdr.len < len) {
                  ip_statinc(IP_STAT_TOOSHORT);
                  goto bad;
          }
  
          /* Checks out, proceed */
          *mp = m;
          return 0;
  
      bad:
          *mp = m;
          return -1;
  }
  
  # ifdef INET6
  /*
   * Same as above, but for IPv6.
   * Cut-and-pasted from ip6_input.c.
   * XXX Should we update ip6stat, or not?
   */
  static int
  bridge_ip6_checkbasic(struct mbuf **mp)
  {
          struct mbuf *m = *mp;
          struct ip6_hdr *ip6;
  
          /*
           * If the IPv6 header is not aligned, slurp it up into a new
           * mbuf with space for link headers, in the event we forward
           * it.  Otherwise, if it is aligned, make sure the entire base
           * IPv6 header is in the first mbuf of the chain.
           */
          if (M_GET_ALIGNED_HDR(&m, struct ip6_hdr, true) != 0) {
                  struct ifnet *inifp = m_get_rcvif_NOMPSAFE(m);
                  /* XXXJRT new stat, please */
                  ip6_statinc(IP6_STAT_TOOSMALL);
                  in6_ifstat_inc(inifp, ifs6_in_hdrerr);
                  goto bad;
          }
  
          ip6 = mtod(m, struct ip6_hdr *);
  
          if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
                  ip6_statinc(IP6_STAT_BADVERS);
                  in6_ifstat_inc(m_get_rcvif_NOMPSAFE(m), ifs6_in_hdrerr);
                  goto bad;
          }
  
          /* Checks out, proceed */
          *mp = m;
          return 0;
  
      bad:
          *mp = m;
          return -1;
  }
  # endif /* INET6 */

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