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

     /*-
      * Copyright (c) 1980, 1986, 1993
      *      The Regents of the University of California.  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.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)if.c        8.5 (Berkeley) 1/9/95
     * $FreeBSD: releng/9.0/sys/net/if.c 223735 2011-07-03 12:22:02Z bz $
     */
    
    #include "opt_compat.h"
    #include "opt_inet6.h"
    #include "opt_inet.h"
    
    #include <sys/param.h>
    #include <sys/types.h>
    #include <sys/conf.h>
    #include <sys/malloc.h>
    #include <sys/sbuf.h>
    #include <sys/bus.h>
    #include <sys/mbuf.h>
    #include <sys/systm.h>
    #include <sys/priv.h>
    #include <sys/proc.h>
    #include <sys/socket.h>
    #include <sys/socketvar.h>
    #include <sys/protosw.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/refcount.h>
    #include <sys/module.h>
    #include <sys/rwlock.h>
    #include <sys/sockio.h>
    #include <sys/syslog.h>
    #include <sys/sysctl.h>
    #include <sys/taskqueue.h>
    #include <sys/domain.h>
    #include <sys/jail.h>
    #include <sys/priv.h>
    
    #include <machine/stdarg.h>
    #include <vm/uma.h>
    
    #include <net/if.h>
    #include <net/if_arp.h>
    #include <net/if_clone.h>
    #include <net/if_dl.h>
    #include <net/if_types.h>
    #include <net/if_var.h>
    #include <net/radix.h>
    #include <net/route.h>
    #include <net/vnet.h>
    
    #if defined(INET) || defined(INET6)
    /*XXX*/
    #include <netinet/in.h>
    #include <netinet/in_var.h>
    #include <netinet/ip_carp.h>
    #ifdef INET6
    #include <netinet6/in6_var.h>
    #include <netinet6/in6_ifattach.h>
    #endif
    #endif
    #ifdef INET
    #include <netinet/if_ether.h>
    #endif
    
    #include <security/mac/mac_framework.h>
    
    #ifdef COMPAT_FREEBSD32
    #include <sys/mount.h>
    #include <compat/freebsd32/freebsd32.h>
    #endif
    
    struct ifindex_entry {
            struct  ifnet *ife_ifnet;
    };
   
   SYSCTL_NODE(_net, PF_LINK, link, CTLFLAG_RW, 0, "Link layers");
   SYSCTL_NODE(_net_link, 0, generic, CTLFLAG_RW, 0, "Generic link-management");
   
   TUNABLE_INT("net.link.ifqmaxlen", &ifqmaxlen);
   SYSCTL_INT(_net_link, OID_AUTO, ifqmaxlen, CTLFLAG_RDTUN,
       &ifqmaxlen, 0, "max send queue size");
   
   /* Log link state change events */
   static int log_link_state_change = 1;
   
   SYSCTL_INT(_net_link, OID_AUTO, log_link_state_change, CTLFLAG_RW,
           &log_link_state_change, 0,
           "log interface link state change events");
   
   /* Interface description */
   static unsigned int ifdescr_maxlen = 1024;
   SYSCTL_UINT(_net, OID_AUTO, ifdescr_maxlen, CTLFLAG_RW,
           &ifdescr_maxlen, 0,
           "administrative maximum length for interface description");
   
   MALLOC_DEFINE(M_IFDESCR, "ifdescr", "ifnet descriptions");
   
   /* global sx for non-critical path ifdescr */
   static struct sx ifdescr_sx;
   SX_SYSINIT(ifdescr_sx, &ifdescr_sx, "ifnet descr");
   
   void    (*bstp_linkstate_p)(struct ifnet *ifp, int state);
   void    (*ng_ether_link_state_p)(struct ifnet *ifp, int state);
   void    (*lagg_linkstate_p)(struct ifnet *ifp, int state);
   /* These are external hooks for CARP. */
   void    (*carp_linkstate_p)(struct ifnet *ifp);
   #if defined(INET) || defined(INET6)
   struct ifnet *(*carp_forus_p)(struct ifnet *ifp, u_char *dhost);
   int     (*carp_output_p)(struct ifnet *ifp, struct mbuf *m,
       struct sockaddr *sa, struct rtentry *rt);
   #endif
   #ifdef INET
   int (*carp_iamatch_p)(struct ifnet *, struct in_ifaddr *, struct in_addr *,
       u_int8_t **);
   #endif
   #ifdef INET6
   struct ifaddr *(*carp_iamatch6_p)(struct ifnet *ifp, struct in6_addr *taddr6);
   caddr_t (*carp_macmatch6_p)(struct ifnet *ifp, struct mbuf *m,
       const struct in6_addr *taddr);
   #endif
   
   struct mbuf *(*tbr_dequeue_ptr)(struct ifaltq *, int) = NULL;
   
   /*
    * XXX: Style; these should be sorted alphabetically, and unprototyped
    * static functions should be prototyped. Currently they are sorted by
    * declaration order.
    */
   static void     if_attachdomain(void *);
   static void     if_attachdomain1(struct ifnet *);
   static int      ifconf(u_long, caddr_t);
   static void     if_freemulti(struct ifmultiaddr *);
   static void     if_init(void *);
   static void     if_grow(void);
   static void     if_route(struct ifnet *, int flag, int fam);
   static int      if_setflag(struct ifnet *, int, int, int *, int);
   static int      if_transmit(struct ifnet *ifp, struct mbuf *m);
   static void     if_unroute(struct ifnet *, int flag, int fam);
   static void     link_rtrequest(int, struct rtentry *, struct rt_addrinfo *);
   static int      if_rtdel(struct radix_node *, void *);
   static int      ifhwioctl(u_long, struct ifnet *, caddr_t, struct thread *);
   static int      if_delmulti_locked(struct ifnet *, struct ifmultiaddr *, int);
   static void     do_link_state_change(void *, int);
   static int      if_getgroup(struct ifgroupreq *, struct ifnet *);
   static int      if_getgroupmembers(struct ifgroupreq *);
   static void     if_delgroups(struct ifnet *);
   static void     if_attach_internal(struct ifnet *, int);
   static void     if_detach_internal(struct ifnet *, int);
   
   #ifdef INET6
   /*
    * XXX: declare here to avoid to include many inet6 related files..
    * should be more generalized?
    */
   extern void     nd6_setmtu(struct ifnet *);
   #endif
   
   VNET_DEFINE(int, if_index);
   int     ifqmaxlen = IFQ_MAXLEN;
   VNET_DEFINE(struct ifnethead, ifnet);   /* depend on static init XXX */
   VNET_DEFINE(struct ifgrouphead, ifg_head);
   
   static VNET_DEFINE(int, if_indexlim) = 8;
   
   /* Table of ifnet by index. */
   VNET_DEFINE(struct ifindex_entry *, ifindex_table);
   
   #define V_if_indexlim           VNET(if_indexlim)
   #define V_ifindex_table         VNET(ifindex_table)
   
   /*
    * The global network interface list (V_ifnet) and related state (such as
    * if_index, if_indexlim, and ifindex_table) are protected by an sxlock and
    * an rwlock.  Either may be acquired shared to stablize the list, but both
    * must be acquired writable to modify the list.  This model allows us to
    * both stablize the interface list during interrupt thread processing, but
    * also to stablize it over long-running ioctls, without introducing priority
    * inversions and deadlocks.
    */
   struct rwlock ifnet_rwlock;
   struct sx ifnet_sxlock;
   
   /*
    * The allocation of network interfaces is a rather non-atomic affair; we
    * need to select an index before we are ready to expose the interface for
    * use, so will use this pointer value to indicate reservation.
    */
   #define IFNET_HOLD      (void *)(uintptr_t)(-1)
   
   static  if_com_alloc_t *if_com_alloc[256];
   static  if_com_free_t *if_com_free[256];
   
   MALLOC_DEFINE(M_IFNET, "ifnet", "interface internals");
   MALLOC_DEFINE(M_IFADDR, "ifaddr", "interface address");
   MALLOC_DEFINE(M_IFMADDR, "ether_multi", "link-level multicast address");
   
   struct ifnet *
   ifnet_byindex_locked(u_short idx)
   {
   
           if (idx > V_if_index)
                   return (NULL);
           if (V_ifindex_table[idx].ife_ifnet == IFNET_HOLD)
                   return (NULL);
           return (V_ifindex_table[idx].ife_ifnet);
   }
   
   struct ifnet *
   ifnet_byindex(u_short idx)
   {
           struct ifnet *ifp;
   
           IFNET_RLOCK_NOSLEEP();
           ifp = ifnet_byindex_locked(idx);
           IFNET_RUNLOCK_NOSLEEP();
           return (ifp);
   }
   
   struct ifnet *
   ifnet_byindex_ref(u_short idx)
   {
           struct ifnet *ifp;
   
           IFNET_RLOCK_NOSLEEP();
           ifp = ifnet_byindex_locked(idx);
           if (ifp == NULL || (ifp->if_flags & IFF_DYING)) {
                   IFNET_RUNLOCK_NOSLEEP();
                   return (NULL);
           }
           if_ref(ifp);
           IFNET_RUNLOCK_NOSLEEP();
           return (ifp);
   }
   
   /*
    * Allocate an ifindex array entry; return 0 on success or an error on
    * failure.
    */
   static int
   ifindex_alloc_locked(u_short *idxp)
   {
           u_short idx;
   
           IFNET_WLOCK_ASSERT();
   
   retry:
           /*
            * Try to find an empty slot below V_if_index.  If we fail, take the
            * next slot.
            */
           for (idx = 1; idx <= V_if_index; idx++) {
                   if (V_ifindex_table[idx].ife_ifnet == NULL)
                           break;
           }
   
           /* Catch if_index overflow. */
           if (idx < 1)
                   return (ENOSPC);
           if (idx >= V_if_indexlim) {
                   if_grow();
                   goto retry;
           }
           if (idx > V_if_index)
                   V_if_index = idx;
           *idxp = idx;
           return (0);
   }
   
   static void
   ifindex_free_locked(u_short idx)
   {
   
           IFNET_WLOCK_ASSERT();
   
           V_ifindex_table[idx].ife_ifnet = NULL;
           while (V_if_index > 0 &&
               V_ifindex_table[V_if_index].ife_ifnet == NULL)
                   V_if_index--;
   }
   
   static void
   ifindex_free(u_short idx)
   {
   
           IFNET_WLOCK();
           ifindex_free_locked(idx);
           IFNET_WUNLOCK();
   }
   
   static void
   ifnet_setbyindex_locked(u_short idx, struct ifnet *ifp)
   {
   
           IFNET_WLOCK_ASSERT();
   
           V_ifindex_table[idx].ife_ifnet = ifp;
   }
   
   static void
   ifnet_setbyindex(u_short idx, struct ifnet *ifp)
   {
   
           IFNET_WLOCK();
           ifnet_setbyindex_locked(idx, ifp);
           IFNET_WUNLOCK();
   }
   
   struct ifaddr *
   ifaddr_byindex(u_short idx)
   {
           struct ifaddr *ifa;
   
           IFNET_RLOCK_NOSLEEP();
           ifa = ifnet_byindex_locked(idx)->if_addr;
           if (ifa != NULL)
                   ifa_ref(ifa);
           IFNET_RUNLOCK_NOSLEEP();
           return (ifa);
   }
   
   /*
    * Network interface utility routines.
    *
    * Routines with ifa_ifwith* names take sockaddr *'s as
    * parameters.
    */
   
   static void
   vnet_if_init(const void *unused __unused)
   {
   
           TAILQ_INIT(&V_ifnet);
           TAILQ_INIT(&V_ifg_head);
           IFNET_WLOCK();
           if_grow();                              /* create initial table */
           IFNET_WUNLOCK();
           vnet_if_clone_init();
   }
   VNET_SYSINIT(vnet_if_init, SI_SUB_INIT_IF, SI_ORDER_SECOND, vnet_if_init,
       NULL);
   
   /* ARGSUSED*/
   static void
   if_init(void *dummy __unused)
   {
   
           IFNET_LOCK_INIT();
           if_clone_init();
   }
   SYSINIT(interfaces, SI_SUB_INIT_IF, SI_ORDER_FIRST, if_init, NULL);
   
   
   #ifdef VIMAGE
   static void
   vnet_if_uninit(const void *unused __unused)
   {
   
           VNET_ASSERT(TAILQ_EMPTY(&V_ifnet), ("%s:%d tailq &V_ifnet=%p "
               "not empty", __func__, __LINE__, &V_ifnet));
           VNET_ASSERT(TAILQ_EMPTY(&V_ifg_head), ("%s:%d tailq &V_ifg_head=%p "
               "not empty", __func__, __LINE__, &V_ifg_head));
   
           free((caddr_t)V_ifindex_table, M_IFNET);
   }
   VNET_SYSUNINIT(vnet_if_uninit, SI_SUB_INIT_IF, SI_ORDER_FIRST,
       vnet_if_uninit, NULL);
   #endif
   
   static void
   if_grow(void)
   {
           int oldlim;
           u_int n;
           struct ifindex_entry *e;
   
           IFNET_WLOCK_ASSERT();
           oldlim = V_if_indexlim;
           IFNET_WUNLOCK();
           n = (oldlim << 1) * sizeof(*e);
           e = malloc(n, M_IFNET, M_WAITOK | M_ZERO);
           IFNET_WLOCK();
           if (V_if_indexlim != oldlim) {
                   free(e, M_IFNET);
                   return;
           }
           if (V_ifindex_table != NULL) {
                   memcpy((caddr_t)e, (caddr_t)V_ifindex_table, n/2);
                   free((caddr_t)V_ifindex_table, M_IFNET);
           }
           V_if_indexlim <<= 1;
           V_ifindex_table = e;
   }
   
   /*
    * Allocate a struct ifnet and an index for an interface.  A layer 2
    * common structure will also be allocated if an allocation routine is
    * registered for the passed type.
    */
   struct ifnet *
   if_alloc(u_char type)
   {
           struct ifnet *ifp;
           u_short idx;
   
           ifp = malloc(sizeof(struct ifnet), M_IFNET, M_WAITOK|M_ZERO);
           IFNET_WLOCK();
           if (ifindex_alloc_locked(&idx) != 0) {
                   IFNET_WUNLOCK();
                   free(ifp, M_IFNET);
                   return (NULL);
           }
           ifnet_setbyindex_locked(idx, IFNET_HOLD);
           IFNET_WUNLOCK();
           ifp->if_index = idx;
           ifp->if_type = type;
           ifp->if_alloctype = type;
           if (if_com_alloc[type] != NULL) {
                   ifp->if_l2com = if_com_alloc[type](type, ifp);
                   if (ifp->if_l2com == NULL) {
                           free(ifp, M_IFNET);
                           ifindex_free(idx);
                           return (NULL);
                   }
           }
   
           IF_ADDR_LOCK_INIT(ifp);
           TASK_INIT(&ifp->if_linktask, 0, do_link_state_change, ifp);
           ifp->if_afdata_initialized = 0;
           IF_AFDATA_LOCK_INIT(ifp);
           TAILQ_INIT(&ifp->if_addrhead);
           TAILQ_INIT(&ifp->if_prefixhead);
           TAILQ_INIT(&ifp->if_multiaddrs);
           TAILQ_INIT(&ifp->if_groups);
   #ifdef MAC
           mac_ifnet_init(ifp);
   #endif
           ifq_init(&ifp->if_snd, ifp);
   
           refcount_init(&ifp->if_refcount, 1);    /* Index reference. */
           ifnet_setbyindex(ifp->if_index, ifp);
           return (ifp);
   }
   
   /*
    * Do the actual work of freeing a struct ifnet, and layer 2 common
    * structure.  This call is made when the last reference to an
    * interface is released.
    */
   static void
   if_free_internal(struct ifnet *ifp)
   {
   
           KASSERT((ifp->if_flags & IFF_DYING),
               ("if_free_internal: interface not dying"));
   
           if (if_com_free[ifp->if_alloctype] != NULL)
                   if_com_free[ifp->if_alloctype](ifp->if_l2com,
                       ifp->if_alloctype);
   
   #ifdef MAC
           mac_ifnet_destroy(ifp);
   #endif /* MAC */
           if (ifp->if_description != NULL)
                   free(ifp->if_description, M_IFDESCR);
           IF_AFDATA_DESTROY(ifp);
           IF_ADDR_LOCK_DESTROY(ifp);
           ifq_delete(&ifp->if_snd);
           free(ifp, M_IFNET);
   }
   
   /*
    * This version should only be called by intefaces that switch their type
    * after calling if_alloc().  if_free_type() will go away again now that we
    * have if_alloctype to cache the original allocation type.  For now, assert
    * that they match, since we require that in practice.
    */
   void
   if_free_type(struct ifnet *ifp, u_char type)
   {
   
           KASSERT(ifp->if_alloctype == type,
               ("if_free_type: type (%d) != alloctype (%d)", type,
               ifp->if_alloctype));
   
           ifp->if_flags |= IFF_DYING;                     /* XXX: Locking */
   
           IFNET_WLOCK();
           KASSERT(ifp == ifnet_byindex_locked(ifp->if_index),
               ("%s: freeing unallocated ifnet", ifp->if_xname));
   
           ifindex_free_locked(ifp->if_index);
           IFNET_WUNLOCK();
   
           if (!refcount_release(&ifp->if_refcount))
                   return;
           if_free_internal(ifp);
   }
   
   /*
    * This is the normal version of if_free(), used by device drivers to free a
    * detached network interface.  The contents of if_free_type() will move into
    * here when if_free_type() goes away.
    */
   void
   if_free(struct ifnet *ifp)
   {
   
           if_free_type(ifp, ifp->if_alloctype);
   }
   
   /*
    * Interfaces to keep an ifnet type-stable despite the possibility of the
    * driver calling if_free().  If there are additional references, we defer
    * freeing the underlying data structure.
    */
   void
   if_ref(struct ifnet *ifp)
   {
   
           /* We don't assert the ifnet list lock here, but arguably should. */
           refcount_acquire(&ifp->if_refcount);
   }
   
   void
   if_rele(struct ifnet *ifp)
   {
   
           if (!refcount_release(&ifp->if_refcount))
                   return;
           if_free_internal(ifp);
   }
   
   void
   ifq_init(struct ifaltq *ifq, struct ifnet *ifp)
   {
           
           mtx_init(&ifq->ifq_mtx, ifp->if_xname, "if send queue", MTX_DEF);
   
           if (ifq->ifq_maxlen == 0) 
                   ifq->ifq_maxlen = ifqmaxlen;
   
           ifq->altq_type = 0;
           ifq->altq_disc = NULL;
           ifq->altq_flags &= ALTQF_CANTCHANGE;
           ifq->altq_tbr  = NULL;
           ifq->altq_ifp  = ifp;
   }
   
   void
   ifq_delete(struct ifaltq *ifq)
   {
           mtx_destroy(&ifq->ifq_mtx);
   }
   
   /*
    * Perform generic interface initalization tasks and attach the interface
    * to the list of "active" interfaces.  If vmove flag is set on entry
    * to if_attach_internal(), perform only a limited subset of initialization
    * tasks, given that we are moving from one vnet to another an ifnet which
    * has already been fully initialized.
    *
    * XXX:
    *  - The decision to return void and thus require this function to
    *    succeed is questionable.
    *  - We should probably do more sanity checking.  For instance we don't
    *    do anything to insure if_xname is unique or non-empty.
    */
   void
   if_attach(struct ifnet *ifp)
   {
   
           if_attach_internal(ifp, 0);
   }
   
   static void
   if_attach_internal(struct ifnet *ifp, int vmove)
   {
           unsigned socksize, ifasize;
           int namelen, masklen;
           struct sockaddr_dl *sdl;
           struct ifaddr *ifa;
   
           if (ifp->if_index == 0 || ifp != ifnet_byindex(ifp->if_index))
                   panic ("%s: BUG: if_attach called without if_alloc'd input()\n",
                       ifp->if_xname);
   
   #ifdef VIMAGE
           ifp->if_vnet = curvnet;
           if (ifp->if_home_vnet == NULL)
                   ifp->if_home_vnet = curvnet;
   #endif
   
           if_addgroup(ifp, IFG_ALL);
   
           getmicrotime(&ifp->if_lastchange);
           ifp->if_data.ifi_epoch = time_uptime;
           ifp->if_data.ifi_datalen = sizeof(struct if_data);
   
           KASSERT((ifp->if_transmit == NULL && ifp->if_qflush == NULL) ||
               (ifp->if_transmit != NULL && ifp->if_qflush != NULL),
               ("transmit and qflush must both either be set or both be NULL"));
           if (ifp->if_transmit == NULL) {
                   ifp->if_transmit = if_transmit;
                   ifp->if_qflush = if_qflush;
           }
           
           if (!vmove) {
   #ifdef MAC
                   mac_ifnet_create(ifp);
   #endif
   
                   /*
                    * Create a Link Level name for this device.
                    */
                   namelen = strlen(ifp->if_xname);
                   /*
                    * Always save enough space for any possiable name so we
                    * can do a rename in place later.
                    */
                   masklen = offsetof(struct sockaddr_dl, sdl_data[0]) + IFNAMSIZ;
                   socksize = masklen + ifp->if_addrlen;
                   if (socksize < sizeof(*sdl))
                           socksize = sizeof(*sdl);
                   socksize = roundup2(socksize, sizeof(long));
                   ifasize = sizeof(*ifa) + 2 * socksize;
                   ifa = malloc(ifasize, M_IFADDR, M_WAITOK | M_ZERO);
                   ifa_init(ifa);
                   sdl = (struct sockaddr_dl *)(ifa + 1);
                   sdl->sdl_len = socksize;
                   sdl->sdl_family = AF_LINK;
                   bcopy(ifp->if_xname, sdl->sdl_data, namelen);
                   sdl->sdl_nlen = namelen;
                   sdl->sdl_index = ifp->if_index;
                   sdl->sdl_type = ifp->if_type;
                   ifp->if_addr = ifa;
                   ifa->ifa_ifp = ifp;
                   ifa->ifa_rtrequest = link_rtrequest;
                   ifa->ifa_addr = (struct sockaddr *)sdl;
                   sdl = (struct sockaddr_dl *)(socksize + (caddr_t)sdl);
                   ifa->ifa_netmask = (struct sockaddr *)sdl;
                   sdl->sdl_len = masklen;
                   while (namelen != 0)
                           sdl->sdl_data[--namelen] = 0xff;
                   TAILQ_INSERT_HEAD(&ifp->if_addrhead, ifa, ifa_link);
                   /* Reliably crash if used uninitialized. */
                   ifp->if_broadcastaddr = NULL;
           }
   #ifdef VIMAGE
           else {
                   /*
                    * Update the interface index in the link layer address
                    * of the interface.
                    */
                   for (ifa = ifp->if_addr; ifa != NULL;
                       ifa = TAILQ_NEXT(ifa, ifa_link)) {
                           if (ifa->ifa_addr->sa_family == AF_LINK) {
                                   sdl = (struct sockaddr_dl *)ifa->ifa_addr;
                                   sdl->sdl_index = ifp->if_index;
                           }
                   }
           }
   #endif
   
           IFNET_WLOCK();
           TAILQ_INSERT_TAIL(&V_ifnet, ifp, if_link);
   #ifdef VIMAGE
           curvnet->vnet_ifcnt++;
   #endif
           IFNET_WUNLOCK();
   
           if (domain_init_status >= 2)
                   if_attachdomain1(ifp);
   
           EVENTHANDLER_INVOKE(ifnet_arrival_event, ifp);
           if (IS_DEFAULT_VNET(curvnet))
                   devctl_notify("IFNET", ifp->if_xname, "ATTACH", NULL);
   
           /* Announce the interface. */
           rt_ifannouncemsg(ifp, IFAN_ARRIVAL);
   }
   
   static void
   if_attachdomain(void *dummy)
   {
           struct ifnet *ifp;
           int s;
   
           s = splnet();
           TAILQ_FOREACH(ifp, &V_ifnet, if_link)
                   if_attachdomain1(ifp);
           splx(s);
   }
   SYSINIT(domainifattach, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_SECOND,
       if_attachdomain, NULL);
   
   static void
   if_attachdomain1(struct ifnet *ifp)
   {
           struct domain *dp;
           int s;
   
           s = splnet();
   
           /*
            * Since dp->dom_ifattach calls malloc() with M_WAITOK, we
            * cannot lock ifp->if_afdata initialization, entirely.
            */
           if (IF_AFDATA_TRYLOCK(ifp) == 0) {
                   splx(s);
                   return;
           }
           if (ifp->if_afdata_initialized >= domain_init_status) {
                   IF_AFDATA_UNLOCK(ifp);
                   splx(s);
                   printf("if_attachdomain called more than once on %s\n",
                       ifp->if_xname);
                   return;
           }
           ifp->if_afdata_initialized = domain_init_status;
           IF_AFDATA_UNLOCK(ifp);
   
           /* address family dependent data region */
           bzero(ifp->if_afdata, sizeof(ifp->if_afdata));
           for (dp = domains; dp; dp = dp->dom_next) {
                   if (dp->dom_ifattach)
                           ifp->if_afdata[dp->dom_family] =
                               (*dp->dom_ifattach)(ifp);
           }
   
           splx(s);
   }
   
   /*
    * Remove any unicast or broadcast network addresses from an interface.
    */
   void
   if_purgeaddrs(struct ifnet *ifp)
   {
           struct ifaddr *ifa, *next;
   
           TAILQ_FOREACH_SAFE(ifa, &ifp->if_addrhead, ifa_link, next) {
                   if (ifa->ifa_addr->sa_family == AF_LINK)
                           continue;
   #ifdef INET
                   /* XXX: Ugly!! ad hoc just for INET */
                   if (ifa->ifa_addr->sa_family == AF_INET) {
                           struct ifaliasreq ifr;
   
                           bzero(&ifr, sizeof(ifr));
                           ifr.ifra_addr = *ifa->ifa_addr;
                           if (ifa->ifa_dstaddr)
                                   ifr.ifra_broadaddr = *ifa->ifa_dstaddr;
                           if (in_control(NULL, SIOCDIFADDR, (caddr_t)&ifr, ifp,
                               NULL) == 0)
                                   continue;
                   }
   #endif /* INET */
   #ifdef INET6
                   if (ifa->ifa_addr->sa_family == AF_INET6) {
                           in6_purgeaddr(ifa);
                           /* ifp_addrhead is already updated */
                           continue;
                   }
   #endif /* INET6 */
                   TAILQ_REMOVE(&ifp->if_addrhead, ifa, ifa_link);
                   ifa_free(ifa);
           }
   }
   
   /*
    * Remove any multicast network addresses from an interface when an ifnet
    * is going away.
    */
   static void
   if_purgemaddrs(struct ifnet *ifp)
   {
           struct ifmultiaddr *ifma;
           struct ifmultiaddr *next;
   
           IF_ADDR_LOCK(ifp);
           TAILQ_FOREACH_SAFE(ifma, &ifp->if_multiaddrs, ifma_link, next)
                   if_delmulti_locked(ifp, ifma, 1);
           IF_ADDR_UNLOCK(ifp);
   }
   
   /*
    * Detach an interface, removing it from the list of "active" interfaces.
    * If vmove flag is set on entry to if_detach_internal(), perform only a
    * limited subset of cleanup tasks, given that we are moving an ifnet from
    * one vnet to another, where it must be fully operational.
    *
    * XXXRW: There are some significant questions about event ordering, and
    * how to prevent things from starting to use the interface during detach.
    */
   void
   if_detach(struct ifnet *ifp)
   {
   
           if_detach_internal(ifp, 0);
   }
   
   static void
   if_detach_internal(struct ifnet *ifp, int vmove)
   {
           struct ifaddr *ifa;
           struct radix_node_head  *rnh;
           int i, j;
           struct domain *dp;
           struct ifnet *iter;
           int found = 0;
   
           IFNET_WLOCK();
           TAILQ_FOREACH(iter, &V_ifnet, if_link)
                   if (iter == ifp) {
                           TAILQ_REMOVE(&V_ifnet, ifp, if_link);
                           found = 1;
                           break;
                   }
   #ifdef VIMAGE
           if (found)
                   curvnet->vnet_ifcnt--;
   #endif
           IFNET_WUNLOCK();
           if (!found) {
                   if (vmove)
                           panic("%s: ifp=%p not on the ifnet tailq %p",
                               __func__, ifp, &V_ifnet);
                   else
                           return; /* XXX this should panic as well? */
           }
   
           /*
            * Remove/wait for pending events.
            */
           taskqueue_drain(taskqueue_swi, &ifp->if_linktask);
   
           /*
            * Remove routes and flush queues.
            */
           if_down(ifp);
   #ifdef ALTQ
           if (ALTQ_IS_ENABLED(&ifp->if_snd))
                   altq_disable(&ifp->if_snd);
           if (ALTQ_IS_ATTACHED(&ifp->if_snd))
                   altq_detach(&ifp->if_snd);
   #endif
   
           if_purgeaddrs(ifp);
   
   #ifdef INET
           in_ifdetach(ifp);
   #endif
   
   #ifdef INET6
           /*
            * Remove all IPv6 kernel structs related to ifp.  This should be done
            * before removing routing entries below, since IPv6 interface direct
            * routes are expected to be removed by the IPv6-specific kernel API.
            * Otherwise, the kernel will detect some inconsistency and bark it.
            */
           in6_ifdetach(ifp);
   #endif
           if_purgemaddrs(ifp);
   
           if (!vmove) {
                   /*
                    * Prevent further calls into the device driver via ifnet.
                    */
                   if_dead(ifp);
   
                   /*
                    * Remove link ifaddr pointer and maybe decrement if_index.
                    * Clean up all addresses.
                    */
                   ifp->if_addr = NULL;
   
                   /* We can now free link ifaddr. */
                   if (!TAILQ_EMPTY(&ifp->if_addrhead)) {
                           ifa = TAILQ_FIRST(&ifp->if_addrhead);
                           TAILQ_REMOVE(&ifp->if_addrhead, ifa, ifa_link);
                           ifa_free(ifa);
                   }
           }
   
           /*
            * Delete all remaining routes using this interface
            * Unfortuneatly the only way to do this is to slog through
            * the entire routing table looking for routes which point
            * to this interface...oh well...
            */
           for (i = 1; i <= AF_MAX; i++) {
                   for (j = 0; j < rt_numfibs; j++) {
                           rnh = rt_tables_get_rnh(j, i);
                           if (rnh == NULL)
                                   continue;
                           RADIX_NODE_HEAD_LOCK(rnh);
                           (void) rnh->rnh_walktree(rnh, if_rtdel, ifp);
                           RADIX_NODE_HEAD_UNLOCK(rnh);
                   }
           }
   
           /* Announce that the interface is gone. */
           rt_ifannouncemsg(ifp, IFAN_DEPARTURE);
           EVENTHANDLER_INVOKE(ifnet_departure_event, ifp);
           if (IS_DEFAULT_VNET(curvnet))
                   devctl_notify("IFNET", ifp->if_xname, "DETACH", NULL);
           if_delgroups(ifp);
   
           /*
            * We cannot hold the lock over dom_ifdetach calls as they might
            * sleep, for example trying to drain a callout, thus open up the
            * theoretical race with re-attaching.
            */
           IF_AFDATA_LOCK(ifp);
           i = ifp->if_afdata_initialized;
           ifp->if_afdata_initialized = 0;
           IF_AFDATA_UNLOCK(ifp);
           for (dp = domains; i > 0 && dp; dp = dp->dom_next) {
                   if (dp->dom_ifdetach && ifp->if_afdata[dp->dom_family])
                           (*dp->dom_ifdetach)(ifp,
                               ifp->if_afdata[dp->dom_family]);
           }
   }
   
   #ifdef VIMAGE
   /*
    * if_vmove() performs a limited version of if_detach() in current
    * vnet and if_attach()es the ifnet to the vnet specified as 2nd arg.
    * An attempt is made to shrink if_index in current vnet, find an
    * unused if_index in target vnet and calls if_grow() if necessary,
    * and finally find an unused if_xname for the target vnet.
    */
   void
   if_vmove(struct ifnet *ifp, struct vnet *new_vnet)
   {
           u_short idx;
   
           /*
            * Detach from current vnet, but preserve LLADDR info, do not
            * mark as dead etc. so that the ifnet can be reattached later.
            */
           if_detach_internal(ifp, 1);
   
           /*
            * Unlink the ifnet from ifindex_table[] in current vnet, and shrink
            * the if_index for that vnet if possible.
            *
            * NOTE: IFNET_WLOCK/IFNET_WUNLOCK() are assumed to be unvirtualized,
            * or we'd lock on one vnet and unlock on another.
            */
           IFNET_WLOCK();
           ifindex_free_locked(ifp->if_index);
           IFNET_WUNLOCK();
   
           /*
            * Perform interface-specific reassignment tasks, if provided by
            * the driver.
            */
           if (ifp->if_reassign != NULL)
                   ifp->if_reassign(ifp, new_vnet, NULL);
   
           /*
            * Switch to the context of the target vnet.
            */
           CURVNET_SET_QUIET(new_vnet);
   
           IFNET_WLOCK();
           if (ifindex_alloc_locked(&idx) != 0) {
                   IFNET_WUNLOCK();
                   panic("if_index overflow");
           }
           ifp->if_index = idx;
           ifnet_setbyindex_locked(ifp->if_index, ifp);
           IFNET_WUNLOCK();
  
          if_attach_internal(ifp, 1);
  
          CURVNET_RESTORE();
  }
  
  /*
   * Move an ifnet to or from another child prison/vnet, specified by the jail id.
   */
  static int
  if_vmove_loan(struct thread *td, struct ifnet *ifp, char *ifname, int jid)
  {
          struct prison *pr;
          struct ifnet *difp;
  
          /* Try to find the prison within our visibility. */
          sx_slock(&allprison_lock);
          pr = prison_find_child(td->td_ucred->cr_prison, jid);
          sx_sunlock(&allprison_lock);
          if (pr == NULL)
                  return (ENXIO);
          prison_hold_locked(pr);
          mtx_unlock(&pr->pr_mtx);
  
          /* Do not try to move the iface from and to the same prison. */
          if (pr->pr_vnet == ifp->if_vnet) {
                  prison_free(pr);
                  return (EEXIST);
          }
  
          /* Make sure the named iface does not exists in the dst. prison/vnet. */
          /* XXX Lock interfaces to avoid races. */
          CURVNET_SET_QUIET(pr->pr_vnet);
          difp = ifunit(ifname);
          CURVNET_RESTORE();
          if (difp != NULL) {
                  prison_free(pr);
                  return (EEXIST);
          }
  
          /* Move the interface into the child jail/vnet. */
          if_vmove(ifp, pr->pr_vnet);
  
          /* Report the new if_xname back to the userland. */
          sprintf(ifname, "%s", ifp->if_xname);
  
          prison_free(pr);
          return (0);
  }
  
  static int
  if_vmove_reclaim(struct thread *td, char *ifname, int jid)
  {
          struct prison *pr;
          struct vnet *vnet_dst;
          struct ifnet *ifp;
  
          /* Try to find the prison within our visibility. */
          sx_slock(&allprison_lock);
          pr = prison_find_child(td->td_ucred->cr_prison, jid);
          sx_sunlock(&allprison_lock);
          if (pr == NULL)
                  return (ENXIO);
          prison_hold_locked(pr);
          mtx_unlock(&pr->pr_mtx);
  
          /* Make sure the named iface exists in the source prison/vnet. */
          CURVNET_SET(pr->pr_vnet);
          ifp = ifunit(ifname);           /* XXX Lock to avoid races. */
          if (ifp == NULL) {
                  CURVNET_RESTORE();
                  prison_free(pr);
                  return (ENXIO);
          }
  
          /* Do not try to move the iface from and to the same prison. */
          vnet_dst = TD_TO_VNET(td);
          if (vnet_dst == ifp->if_vnet) {
                  CURVNET_RESTORE();
                  prison_free(pr);
                  return (EEXIST);
          }
  
          /* Get interface back from child jail/vnet. */
          if_vmove(ifp, vnet_dst);
          CURVNET_RESTORE();
  
          /* Report the new if_xname back to the userland. */
          sprintf(ifname, "%s", ifp->if_xname);
  
          prison_free(pr);
          return (0);
  }
  #endif /* VIMAGE */
  
  /*
   * Add a group to an interface
   */
  int
  if_addgroup(struct ifnet *ifp, const char *groupname)
  {
          struct ifg_list         *ifgl;
          struct ifg_group        *ifg = NULL;
          struct ifg_member       *ifgm;
  
          if (groupname[0] && groupname[strlen(groupname) - 1] >= '' &&
              groupname[strlen(groupname) - 1] <= '9')
                  return (EINVAL);
  
          IFNET_WLOCK();
          TAILQ_FOREACH(ifgl, &ifp->if_groups, ifgl_next)
                  if (!strcmp(ifgl->ifgl_group->ifg_group, groupname)) {
                          IFNET_WUNLOCK();
                          return (EEXIST);
                  }
  
          if ((ifgl = (struct ifg_list *)malloc(sizeof(struct ifg_list), M_TEMP,
              M_NOWAIT)) == NULL) {
                  IFNET_WUNLOCK();
                  return (ENOMEM);
          }
  
          if ((ifgm = (struct ifg_member *)malloc(sizeof(struct ifg_member),
              M_TEMP, M_NOWAIT)) == NULL) {
                  free(ifgl, M_TEMP);
                  IFNET_WUNLOCK();
                  return (ENOMEM);
          }
  
          TAILQ_FOREACH(ifg, &V_ifg_head, ifg_next)
                  if (!strcmp(ifg->ifg_group, groupname))
                          break;
  
          if (ifg == NULL) {
                  if ((ifg = (struct ifg_group *)malloc(sizeof(struct ifg_group),
                      M_TEMP, M_NOWAIT)) == NULL) {
                          free(ifgl, M_TEMP);
                          free(ifgm, M_TEMP);
                          IFNET_WUNLOCK();
                          return (ENOMEM);
                  }
                  strlcpy(ifg->ifg_group, groupname, sizeof(ifg->ifg_group));
                  ifg->ifg_refcnt = 0;
                  TAILQ_INIT(&ifg->ifg_members);
                  EVENTHANDLER_INVOKE(group_attach_event, ifg);
                  TAILQ_INSERT_TAIL(&V_ifg_head, ifg, ifg_next);
          }
  
          ifg->ifg_refcnt++;
          ifgl->ifgl_group = ifg;
          ifgm->ifgm_ifp = ifp;
  
          IF_ADDR_LOCK(ifp);
          TAILQ_INSERT_TAIL(&ifg->ifg_members, ifgm, ifgm_next);
          TAILQ_INSERT_TAIL(&ifp->if_groups, ifgl, ifgl_next);
          IF_ADDR_UNLOCK(ifp);
  
          IFNET_WUNLOCK();
  
          EVENTHANDLER_INVOKE(group_change_event, groupname);
  
          return (0);
  }
  
  /*
   * Remove a group from an interface
   */
  int
  if_delgroup(struct ifnet *ifp, const char *groupname)
  {
          struct ifg_list         *ifgl;
          struct ifg_member       *ifgm;
  
          IFNET_WLOCK();
          TAILQ_FOREACH(ifgl, &ifp->if_groups, ifgl_next)
                  if (!strcmp(ifgl->ifgl_group->ifg_group, groupname))
                          break;
          if (ifgl == NULL) {
                  IFNET_WUNLOCK();
                  return (ENOENT);
          }
  
          IF_ADDR_LOCK(ifp);
          TAILQ_REMOVE(&ifp->if_groups, ifgl, ifgl_next);
          IF_ADDR_UNLOCK(ifp);
  
          TAILQ_FOREACH(ifgm, &ifgl->ifgl_group->ifg_members, ifgm_next)
                  if (ifgm->ifgm_ifp == ifp)
                          break;
  
          if (ifgm != NULL) {
                  TAILQ_REMOVE(&ifgl->ifgl_group->ifg_members, ifgm, ifgm_next);
                  free(ifgm, M_TEMP);
          }
  
          if (--ifgl->ifgl_group->ifg_refcnt == 0) {
                  TAILQ_REMOVE(&V_ifg_head, ifgl->ifgl_group, ifg_next);
                  EVENTHANDLER_INVOKE(group_detach_event, ifgl->ifgl_group);
                  free(ifgl->ifgl_group, M_TEMP);
          }
          IFNET_WUNLOCK();
  
          free(ifgl, M_TEMP);
  
          EVENTHANDLER_INVOKE(group_change_event, groupname);
  
          return (0);
  }
  
  /*
   * Remove an interface from all groups
   */
  static void
  if_delgroups(struct ifnet *ifp)
  {
          struct ifg_list         *ifgl;
          struct ifg_member       *ifgm;
          char groupname[IFNAMSIZ];
  
          IFNET_WLOCK();
          while (!TAILQ_EMPTY(&ifp->if_groups)) {
                  ifgl = TAILQ_FIRST(&ifp->if_groups);
  
                  strlcpy(groupname, ifgl->ifgl_group->ifg_group, IFNAMSIZ);
  
                  IF_ADDR_LOCK(ifp);
                  TAILQ_REMOVE(&ifp->if_groups, ifgl, ifgl_next);
                  IF_ADDR_UNLOCK(ifp);
  
                  TAILQ_FOREACH(ifgm, &ifgl->ifgl_group->ifg_members, ifgm_next)
                          if (ifgm->ifgm_ifp == ifp)
                                  break;
  
                  if (ifgm != NULL) {
                          TAILQ_REMOVE(&ifgl->ifgl_group->ifg_members, ifgm,
                              ifgm_next);
                          free(ifgm, M_TEMP);
                  }
  
                  if (--ifgl->ifgl_group->ifg_refcnt == 0) {
                          TAILQ_REMOVE(&V_ifg_head, ifgl->ifgl_group, ifg_next);
                          EVENTHANDLER_INVOKE(group_detach_event,
                              ifgl->ifgl_group);
                          free(ifgl->ifgl_group, M_TEMP);
                  }
                  IFNET_WUNLOCK();
  
                  free(ifgl, M_TEMP);
  
                  EVENTHANDLER_INVOKE(group_change_event, groupname);
  
                  IFNET_WLOCK();
          }
          IFNET_WUNLOCK();
  }
  
  /*
   * Stores all groups from an interface in memory pointed
   * to by data
   */
  static int
  if_getgroup(struct ifgroupreq *data, struct ifnet *ifp)
  {
          int                      len, error;
          struct ifg_list         *ifgl;
          struct ifg_req           ifgrq, *ifgp;
          struct ifgroupreq       *ifgr = data;
  
          if (ifgr->ifgr_len == 0) {
                  IF_ADDR_LOCK(ifp);
                  TAILQ_FOREACH(ifgl, &ifp->if_groups, ifgl_next)
                          ifgr->ifgr_len += sizeof(struct ifg_req);
                  IF_ADDR_UNLOCK(ifp);
                  return (0);
          }
  
          len = ifgr->ifgr_len;
          ifgp = ifgr->ifgr_groups;
          /* XXX: wire */
          IF_ADDR_LOCK(ifp);
          TAILQ_FOREACH(ifgl, &ifp->if_groups, ifgl_next) {
                  if (len < sizeof(ifgrq)) {
                          IF_ADDR_UNLOCK(ifp);
                          return (EINVAL);
                  }
                  bzero(&ifgrq, sizeof ifgrq);
                  strlcpy(ifgrq.ifgrq_group, ifgl->ifgl_group->ifg_group,
                      sizeof(ifgrq.ifgrq_group));
                  if ((error = copyout(&ifgrq, ifgp, sizeof(struct ifg_req)))) {
                          IF_ADDR_UNLOCK(ifp);
                          return (error);
                  }
                  len -= sizeof(ifgrq);
                  ifgp++;
          }
          IF_ADDR_UNLOCK(ifp);
  
          return (0);
  }
  
  /*
   * Stores all members of a group in memory pointed to by data
   */
  static int
  if_getgroupmembers(struct ifgroupreq *data)
  {
          struct ifgroupreq       *ifgr = data;
          struct ifg_group        *ifg;
          struct ifg_member       *ifgm;
          struct ifg_req           ifgrq, *ifgp;
          int                      len, error;
  
          IFNET_RLOCK();
          TAILQ_FOREACH(ifg, &V_ifg_head, ifg_next)
                  if (!strcmp(ifg->ifg_group, ifgr->ifgr_name))
                          break;
          if (ifg == NULL) {
                  IFNET_RUNLOCK();
                  return (ENOENT);
          }
  
          if (ifgr->ifgr_len == 0) {
                  TAILQ_FOREACH(ifgm, &ifg->ifg_members, ifgm_next)
                          ifgr->ifgr_len += sizeof(ifgrq);
                  IFNET_RUNLOCK();
                  return (0);
          }
  
          len = ifgr->ifgr_len;
          ifgp = ifgr->ifgr_groups;
          TAILQ_FOREACH(ifgm, &ifg->ifg_members, ifgm_next) {
                  if (len < sizeof(ifgrq)) {
                          IFNET_RUNLOCK();
                          return (EINVAL);
                  }
                  bzero(&ifgrq, sizeof ifgrq);
                  strlcpy(ifgrq.ifgrq_member, ifgm->ifgm_ifp->if_xname,
                      sizeof(ifgrq.ifgrq_member));
                  if ((error = copyout(&ifgrq, ifgp, sizeof(struct ifg_req)))) {
                          IFNET_RUNLOCK();
                          return (error);
                  }
                  len -= sizeof(ifgrq);
                  ifgp++;
          }
          IFNET_RUNLOCK();
  
          return (0);
  }
  
  /*
   * Delete Routes for a Network Interface
   *
   * Called for each routing entry via the rnh->rnh_walktree() call above
   * to delete all route entries referencing a detaching network interface.
   *
   * Arguments:
   *      rn      pointer to node in the routing table
   *      arg     argument passed to rnh->rnh_walktree() - detaching interface
   *
   * Returns:
   *      0       successful
   *      errno   failed - reason indicated
   *
   */
  static int
  if_rtdel(struct radix_node *rn, void *arg)
  {
          struct rtentry  *rt = (struct rtentry *)rn;
          struct ifnet    *ifp = arg;
          int             err;
  
          if (rt->rt_ifp == ifp) {
  
                  /*
                   * Protect (sorta) against walktree recursion problems
                   * with cloned routes
                   */
                  if ((rt->rt_flags & RTF_UP) == 0)
                          return (0);
  
                  err = rtrequest_fib(RTM_DELETE, rt_key(rt), rt->rt_gateway,
                                  rt_mask(rt), rt->rt_flags|RTF_RNH_LOCKED,
                                  (struct rtentry **) NULL, rt->rt_fibnum);
                  if (err) {
                          log(LOG_WARNING, "if_rtdel: error %d\n", err);
                  }
          }
  
          return (0);
  }
  
  /*
   * Wrapper functions for struct ifnet address list locking macros.  These are
   * used by kernel modules to avoid encoding programming interface or binary
   * interface assumptions that may be violated when kernel-internal locking
   * approaches change.
   */
  void
  if_addr_rlock(struct ifnet *ifp)
  {
  
          IF_ADDR_LOCK(ifp);
  }
  
  void
  if_addr_runlock(struct ifnet *ifp)
  {
  
          IF_ADDR_UNLOCK(ifp);
  }
  
  void
  if_maddr_rlock(struct ifnet *ifp)
  {
  
          IF_ADDR_LOCK(ifp);
  }
  
  void
  if_maddr_runlock(struct ifnet *ifp)
  {
  
          IF_ADDR_UNLOCK(ifp);
  }
  
  /*
   * Reference count functions for ifaddrs.
   */
  void
  ifa_init(struct ifaddr *ifa)
  {
  
          mtx_init(&ifa->ifa_mtx, "ifaddr", NULL, MTX_DEF);
          refcount_init(&ifa->ifa_refcnt, 1);
  }
  
  void
  ifa_ref(struct ifaddr *ifa)
  {
  
          refcount_acquire(&ifa->ifa_refcnt);
  }
  
  void
  ifa_free(struct ifaddr *ifa)
  {
  
          if (refcount_release(&ifa->ifa_refcnt)) {
                  mtx_destroy(&ifa->ifa_mtx);
                  free(ifa, M_IFADDR);
          }
  }
  
  int
  ifa_add_loopback_route(struct ifaddr *ifa, struct sockaddr *ia)
  {
          int error = 0;
          struct rtentry *rt = NULL;
          struct rt_addrinfo info;
          static struct sockaddr_dl null_sdl = {sizeof(null_sdl), AF_LINK};
  
          bzero(&info, sizeof(info));
          info.rti_ifp = V_loif;
          info.rti_flags = ifa->ifa_flags | RTF_HOST | RTF_STATIC;
          info.rti_info[RTAX_DST] = ia;
          info.rti_info[RTAX_GATEWAY] = (struct sockaddr *)&null_sdl;
          error = rtrequest1_fib(RTM_ADD, &info, &rt, 0);
  
          if (error == 0 && rt != NULL) {
                  RT_LOCK(rt);
                  ((struct sockaddr_dl *)rt->rt_gateway)->sdl_type  =
                          ifa->ifa_ifp->if_type;
                  ((struct sockaddr_dl *)rt->rt_gateway)->sdl_index =
                          ifa->ifa_ifp->if_index;
                  RT_REMREF(rt);
                  RT_UNLOCK(rt);
          } else if (error != 0)
                  log(LOG_INFO, "ifa_add_loopback_route: insertion failed\n");
  
          return (error);
  }
  
  int
  ifa_del_loopback_route(struct ifaddr *ifa, struct sockaddr *ia)
  {
          int error = 0;
          struct rt_addrinfo info;
          struct sockaddr_dl null_sdl;
  
          bzero(&null_sdl, sizeof(null_sdl));
          null_sdl.sdl_len = sizeof(null_sdl);
          null_sdl.sdl_family = AF_LINK;
          null_sdl.sdl_type = ifa->ifa_ifp->if_type;
          null_sdl.sdl_index = ifa->ifa_ifp->if_index;
          bzero(&info, sizeof(info));
          info.rti_flags = ifa->ifa_flags | RTF_HOST | RTF_STATIC;
          info.rti_info[RTAX_DST] = ia;
          info.rti_info[RTAX_GATEWAY] = (struct sockaddr *)&null_sdl;
          error = rtrequest1_fib(RTM_DELETE, &info, NULL, 0);
  
          if (error != 0)
                  log(LOG_INFO, "ifa_del_loopback_route: deletion failed\n");
  
          return (error);
  }
  
  /*
   * XXX: Because sockaddr_dl has deeper structure than the sockaddr
   * structs used to represent other address families, it is necessary
   * to perform a different comparison.
   */
  
  #define sa_equal(a1, a2)        \
          (bcmp((a1), (a2), ((a1))->sa_len) == 0)
  
  #define sa_dl_equal(a1, a2)     \
          ((((struct sockaddr_dl *)(a1))->sdl_len ==                      \
           ((struct sockaddr_dl *)(a2))->sdl_len) &&                      \
           (bcmp(LLADDR((struct sockaddr_dl *)(a1)),                      \
                 LLADDR((struct sockaddr_dl *)(a2)),                      \
                 ((struct sockaddr_dl *)(a1))->sdl_alen) == 0))
  
  /*
   * Locate an interface based on a complete address.
   */
  /*ARGSUSED*/
  static struct ifaddr *
  ifa_ifwithaddr_internal(struct sockaddr *addr, int getref)
  {
          struct ifnet *ifp;
          struct ifaddr *ifa;
  
          IFNET_RLOCK_NOSLEEP();
          TAILQ_FOREACH(ifp, &V_ifnet, if_link) {
                  IF_ADDR_LOCK(ifp);
                  TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                          if (ifa->ifa_addr->sa_family != addr->sa_family)
                                  continue;
                          if (sa_equal(addr, ifa->ifa_addr)) {
                                  if (getref)
                                          ifa_ref(ifa);
                                  IF_ADDR_UNLOCK(ifp);
                                  goto done;
                          }
                          /* IP6 doesn't have broadcast */
                          if ((ifp->if_flags & IFF_BROADCAST) &&
                              ifa->ifa_broadaddr &&
                              ifa->ifa_broadaddr->sa_len != 0 &&
                              sa_equal(ifa->ifa_broadaddr, addr)) {
                                  if (getref)
                                          ifa_ref(ifa);
                                  IF_ADDR_UNLOCK(ifp);
                                  goto done;
                          }
                  }
                  IF_ADDR_UNLOCK(ifp);
          }
          ifa = NULL;
  done:
          IFNET_RUNLOCK_NOSLEEP();
          return (ifa);
  }
  
  struct ifaddr *
  ifa_ifwithaddr(struct sockaddr *addr)
  {
  
          return (ifa_ifwithaddr_internal(addr, 1));
  }
  
  int
  ifa_ifwithaddr_check(struct sockaddr *addr)
  {
  
          return (ifa_ifwithaddr_internal(addr, 0) != NULL);
  }
  
  /*
   * Locate an interface based on the broadcast address.
   */
  /* ARGSUSED */
  struct ifaddr *
  ifa_ifwithbroadaddr(struct sockaddr *addr)
  {
          struct ifnet *ifp;
          struct ifaddr *ifa;
  
          IFNET_RLOCK_NOSLEEP();
          TAILQ_FOREACH(ifp, &V_ifnet, if_link) {
                  IF_ADDR_LOCK(ifp);
                  TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                          if (ifa->ifa_addr->sa_family != addr->sa_family)
                                  continue;
                          if ((ifp->if_flags & IFF_BROADCAST) &&
                              ifa->ifa_broadaddr &&
                              ifa->ifa_broadaddr->sa_len != 0 &&
                              sa_equal(ifa->ifa_broadaddr, addr)) {
                                  ifa_ref(ifa);
                                  IF_ADDR_UNLOCK(ifp);
                                  goto done;
                          }
                  }
                  IF_ADDR_UNLOCK(ifp);
          }
          ifa = NULL;
  done:
          IFNET_RUNLOCK_NOSLEEP();
          return (ifa);
  }
  
  /*
   * Locate the point to point interface with a given destination address.
   */
  /*ARGSUSED*/
  struct ifaddr *
  ifa_ifwithdstaddr(struct sockaddr *addr)
  {
          struct ifnet *ifp;
          struct ifaddr *ifa;
  
          IFNET_RLOCK_NOSLEEP();
          TAILQ_FOREACH(ifp, &V_ifnet, if_link) {
                  if ((ifp->if_flags & IFF_POINTOPOINT) == 0)
                          continue;
                  IF_ADDR_LOCK(ifp);
                  TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                          if (ifa->ifa_addr->sa_family != addr->sa_family)
                                  continue;
                          if (ifa->ifa_dstaddr != NULL &&
                              sa_equal(addr, ifa->ifa_dstaddr)) {
                                  ifa_ref(ifa);
                                  IF_ADDR_UNLOCK(ifp);
                                  goto done;
                          }
                  }
                  IF_ADDR_UNLOCK(ifp);
          }
          ifa = NULL;
  done:
          IFNET_RUNLOCK_NOSLEEP();
          return (ifa);
  }
  
  /*
   * Find an interface on a specific network.  If many, choice
   * is most specific found.
   */
  struct ifaddr *
  ifa_ifwithnet(struct sockaddr *addr, int ignore_ptp)
  {
          struct ifnet *ifp;
          struct ifaddr *ifa;
          struct ifaddr *ifa_maybe = NULL;
          u_int af = addr->sa_family;
          char *addr_data = addr->sa_data, *cplim;
  
          /*
           * AF_LINK addresses can be looked up directly by their index number,
           * so do that if we can.
           */
          if (af == AF_LINK) {
              struct sockaddr_dl *sdl = (struct sockaddr_dl *)addr;
              if (sdl->sdl_index && sdl->sdl_index <= V_if_index)
                  return (ifaddr_byindex(sdl->sdl_index));
          }
  
          /*
           * Scan though each interface, looking for ones that have addresses
           * in this address family.  Maintain a reference on ifa_maybe once
           * we find one, as we release the IF_ADDR_LOCK() that kept it stable
           * when we move onto the next interface.
           */
          IFNET_RLOCK_NOSLEEP();
          TAILQ_FOREACH(ifp, &V_ifnet, if_link) {
                  IF_ADDR_LOCK(ifp);
                  TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                          char *cp, *cp2, *cp3;
  
                          if (ifa->ifa_addr->sa_family != af)
  next:                           continue;
                          if (af == AF_INET && 
                              ifp->if_flags & IFF_POINTOPOINT && !ignore_ptp) {
                                  /*
                                   * This is a bit broken as it doesn't
                                   * take into account that the remote end may
                                   * be a single node in the network we are
                                   * looking for.
                                   * The trouble is that we don't know the
                                   * netmask for the remote end.
                                   */
                                  if (ifa->ifa_dstaddr != NULL &&
                                      sa_equal(addr, ifa->ifa_dstaddr)) {
                                          ifa_ref(ifa);
                                          IF_ADDR_UNLOCK(ifp);
                                          goto done;
                                  }
                          } else {
                                  /*
                                   * if we have a special address handler,
                                   * then use it instead of the generic one.
                                   */
                                  if (ifa->ifa_claim_addr) {
                                          if ((*ifa->ifa_claim_addr)(ifa, addr)) {
                                                  ifa_ref(ifa);
                                                  IF_ADDR_UNLOCK(ifp);
                                                  goto done;
                                          }
                                          continue;
                                  }
  
                                  /*
                                   * Scan all the bits in the ifa's address.
                                   * If a bit dissagrees with what we are
                                   * looking for, mask it with the netmask
                                   * to see if it really matters.
                                   * (A byte at a time)
                                   */
                                  if (ifa->ifa_netmask == 0)
                                          continue;
                                  cp = addr_data;
                                  cp2 = ifa->ifa_addr->sa_data;
                                  cp3 = ifa->ifa_netmask->sa_data;
                                  cplim = ifa->ifa_netmask->sa_len
                                          + (char *)ifa->ifa_netmask;
                                  while (cp3 < cplim)
                                          if ((*cp++ ^ *cp2++) & *cp3++)
                                                  goto next; /* next address! */
                                  /*
                                   * If the netmask of what we just found
                                   * is more specific than what we had before
                                   * (if we had one) then remember the new one
                                   * before continuing to search
                                   * for an even better one.
                                   */
                                  if (ifa_maybe == NULL ||
                                      rn_refines((caddr_t)ifa->ifa_netmask,
                                      (caddr_t)ifa_maybe->ifa_netmask)) {
                                          if (ifa_maybe != NULL)
                                                  ifa_free(ifa_maybe);
                                          ifa_maybe = ifa;
                                          ifa_ref(ifa_maybe);
                                  }
                          }
                  }
                  IF_ADDR_UNLOCK(ifp);
          }
          ifa = ifa_maybe;
          ifa_maybe = NULL;
  done:
          IFNET_RUNLOCK_NOSLEEP();
          if (ifa_maybe != NULL)
                  ifa_free(ifa_maybe);
          return (ifa);
  }
  
  /*
   * Find an interface address specific to an interface best matching
   * a given address.
   */
  struct ifaddr *
  ifaof_ifpforaddr(struct sockaddr *addr, struct ifnet *ifp)
  {
          struct ifaddr *ifa;
          char *cp, *cp2, *cp3;
          char *cplim;
          struct ifaddr *ifa_maybe = NULL;
          u_int af = addr->sa_family;
  
          if (af >= AF_MAX)
                  return (NULL);
          IF_ADDR_LOCK(ifp);
          TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                  if (ifa->ifa_addr->sa_family != af)
                          continue;
                  if (ifa_maybe == NULL)
                          ifa_maybe = ifa;
                  if (ifa->ifa_netmask == 0) {
                          if (sa_equal(addr, ifa->ifa_addr) ||
                              (ifa->ifa_dstaddr &&
                              sa_equal(addr, ifa->ifa_dstaddr)))
                                  goto done;
                          continue;
                  }
                  if (ifp->if_flags & IFF_POINTOPOINT) {
                          if (sa_equal(addr, ifa->ifa_dstaddr))
                                  goto done;
                  } else {
                          cp = addr->sa_data;
                          cp2 = ifa->ifa_addr->sa_data;
                          cp3 = ifa->ifa_netmask->sa_data;
                          cplim = ifa->ifa_netmask->sa_len + (char *)ifa->ifa_netmask;
                          for (; cp3 < cplim; cp3++)
                                  if ((*cp++ ^ *cp2++) & *cp3)
                                          break;
                          if (cp3 == cplim)
                                  goto done;
                  }
          }
          ifa = ifa_maybe;
  done:
          if (ifa != NULL)
                  ifa_ref(ifa);
          IF_ADDR_UNLOCK(ifp);
          return (ifa);
  }
  
  #include <net/if_llatbl.h>
  
  /*
   * Default action when installing a route with a Link Level gateway.
   * Lookup an appropriate real ifa to point to.
   * This should be moved to /sys/net/link.c eventually.
   */
  static void
  link_rtrequest(int cmd, struct rtentry *rt, struct rt_addrinfo *info)
  {
          struct ifaddr *ifa, *oifa;
          struct sockaddr *dst;
          struct ifnet *ifp;
  
          RT_LOCK_ASSERT(rt);
  
          if (cmd != RTM_ADD || ((ifa = rt->rt_ifa) == 0) ||
              ((ifp = ifa->ifa_ifp) == 0) || ((dst = rt_key(rt)) == 0))
                  return;
          ifa = ifaof_ifpforaddr(dst, ifp);
          if (ifa) {
                  oifa = rt->rt_ifa;
                  rt->rt_ifa = ifa;
                  ifa_free(oifa);
                  if (ifa->ifa_rtrequest && ifa->ifa_rtrequest != link_rtrequest)
                          ifa->ifa_rtrequest(cmd, rt, info);
          }
  }
  
  /*
   * Mark an interface down and notify protocols of
   * the transition.
   * NOTE: must be called at splnet or eqivalent.
   */
  static void
  if_unroute(struct ifnet *ifp, int flag, int fam)
  {
          struct ifaddr *ifa;
  
          KASSERT(flag == IFF_UP, ("if_unroute: flag != IFF_UP"));
  
          ifp->if_flags &= ~flag;
          getmicrotime(&ifp->if_lastchange);
          TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
                  if (fam == PF_UNSPEC || (fam == ifa->ifa_addr->sa_family))
                          pfctlinput(PRC_IFDOWN, ifa->ifa_addr);
          ifp->if_qflush(ifp);
  
          if (ifp->if_carp)
                  (*carp_linkstate_p)(ifp);
          rt_ifmsg(ifp);
  }
  
  /*
   * Mark an interface up and notify protocols of
   * the transition.
   * NOTE: must be called at splnet or eqivalent.
   */
  static void
  if_route(struct ifnet *ifp, int flag, int fam)
  {
          struct ifaddr *ifa;
  
          KASSERT(flag == IFF_UP, ("if_route: flag != IFF_UP"));
  
          ifp->if_flags |= flag;
          getmicrotime(&ifp->if_lastchange);
          TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
                  if (fam == PF_UNSPEC || (fam == ifa->ifa_addr->sa_family))
                          pfctlinput(PRC_IFUP, ifa->ifa_addr);
          if (ifp->if_carp)
                  (*carp_linkstate_p)(ifp);
          rt_ifmsg(ifp);
  #ifdef INET6
          in6_if_up(ifp);
  #endif
  }
  
  void    (*vlan_link_state_p)(struct ifnet *);   /* XXX: private from if_vlan */
  void    (*vlan_trunk_cap_p)(struct ifnet *);            /* XXX: private from if_vlan */
  struct ifnet *(*vlan_trunkdev_p)(struct ifnet *);
  struct  ifnet *(*vlan_devat_p)(struct ifnet *, uint16_t);
  int     (*vlan_tag_p)(struct ifnet *, uint16_t *);
  int     (*vlan_setcookie_p)(struct ifnet *, void *);
  void    *(*vlan_cookie_p)(struct ifnet *);
  
  /*
   * Handle a change in the interface link state. To avoid LORs
   * between driver lock and upper layer locks, as well as possible
   * recursions, we post event to taskqueue, and all job
   * is done in static do_link_state_change().
   */
  void
  if_link_state_change(struct ifnet *ifp, int link_state)
  {
          /* Return if state hasn't changed. */
          if (ifp->if_link_state == link_state)
                  return;
  
          ifp->if_link_state = link_state;
  
          taskqueue_enqueue(taskqueue_swi, &ifp->if_linktask);
  }
  
  static void
  do_link_state_change(void *arg, int pending)
  {
          struct ifnet *ifp = (struct ifnet *)arg;
          int link_state = ifp->if_link_state;
          CURVNET_SET(ifp->if_vnet);
  
          /* Notify that the link state has changed. */
          rt_ifmsg(ifp);
          if (ifp->if_vlantrunk != NULL)
                  (*vlan_link_state_p)(ifp);
  
          if ((ifp->if_type == IFT_ETHER || ifp->if_type == IFT_L2VLAN) &&
              IFP2AC(ifp)->ac_netgraph != NULL)
                  (*ng_ether_link_state_p)(ifp, link_state);
          if (ifp->if_carp)
                  (*carp_linkstate_p)(ifp);
          if (ifp->if_bridge) {
                  KASSERT(bstp_linkstate_p != NULL,("if_bridge bstp not loaded!"));
                  (*bstp_linkstate_p)(ifp, link_state);
          }
          if (ifp->if_lagg) {
                  KASSERT(lagg_linkstate_p != NULL,("if_lagg not loaded!"));
                  (*lagg_linkstate_p)(ifp, link_state);
          }
  
          if (IS_DEFAULT_VNET(curvnet))
                  devctl_notify("IFNET", ifp->if_xname,
                      (link_state == LINK_STATE_UP) ? "LINK_UP" : "LINK_DOWN",
                      NULL);
          if (pending > 1)
                  if_printf(ifp, "%d link states coalesced\n", pending);
          if (log_link_state_change)
                  log(LOG_NOTICE, "%s: link state changed to %s\n", ifp->if_xname,
                      (link_state == LINK_STATE_UP) ? "UP" : "DOWN" );
          EVENTHANDLER_INVOKE(ifnet_link_event, ifp, ifp->if_link_state);
          CURVNET_RESTORE();
  }
  
  /*
   * Mark an interface down and notify protocols of
   * the transition.
   * NOTE: must be called at splnet or eqivalent.
   */
  void
  if_down(struct ifnet *ifp)
  {
  
          if_unroute(ifp, IFF_UP, AF_UNSPEC);
  }
  
  /*
   * Mark an interface up and notify protocols of
   * the transition.
   * NOTE: must be called at splnet or eqivalent.
   */
  void
  if_up(struct ifnet *ifp)
  {
  
          if_route(ifp, IFF_UP, AF_UNSPEC);
  }
  
  /*
   * Flush an interface queue.
   */
  void
  if_qflush(struct ifnet *ifp)
  {
          struct mbuf *m, *n;
          struct ifaltq *ifq;
          
          ifq = &ifp->if_snd;
          IFQ_LOCK(ifq);
  #ifdef ALTQ
          if (ALTQ_IS_ENABLED(ifq))
                  ALTQ_PURGE(ifq);
  #endif
          n = ifq->ifq_head;
          while ((m = n) != 0) {
                  n = m->m_act;
                  m_freem(m);
          }
          ifq->ifq_head = 0;
          ifq->ifq_tail = 0;
          ifq->ifq_len = 0;
          IFQ_UNLOCK(ifq);
  }
  
  /*
   * Map interface name to interface structure pointer, with or without
   * returning a reference.
   */
  struct ifnet *
  ifunit_ref(const char *name)
  {
          struct ifnet *ifp;
  
          IFNET_RLOCK_NOSLEEP();
          TAILQ_FOREACH(ifp, &V_ifnet, if_link) {
                  if (strncmp(name, ifp->if_xname, IFNAMSIZ) == 0 &&
                      !(ifp->if_flags & IFF_DYING))
                          break;
          }
          if (ifp != NULL)
                  if_ref(ifp);
          IFNET_RUNLOCK_NOSLEEP();
          return (ifp);
  }
  
  struct ifnet *
  ifunit(const char *name)
  {
          struct ifnet *ifp;
  
          IFNET_RLOCK_NOSLEEP();
          TAILQ_FOREACH(ifp, &V_ifnet, if_link) {
                  if (strncmp(name, ifp->if_xname, IFNAMSIZ) == 0)
                          break;
          }
          IFNET_RUNLOCK_NOSLEEP();
          return (ifp);
  }
  
  /*
   * Hardware specific interface ioctls.
   */
  static int
  ifhwioctl(u_long cmd, struct ifnet *ifp, caddr_t data, struct thread *td)
  {
          struct ifreq *ifr;
          struct ifstat *ifs;
          int error = 0;
          int new_flags, temp_flags;
          size_t namelen, onamelen;
          size_t descrlen;
          char *descrbuf, *odescrbuf;
          char new_name[IFNAMSIZ];
          struct ifaddr *ifa;
          struct sockaddr_dl *sdl;
  
          ifr = (struct ifreq *)data;
          switch (cmd) {
          case SIOCGIFINDEX:
                  ifr->ifr_index = ifp->if_index;
                  break;
  
          case SIOCGIFFLAGS:
                  temp_flags = ifp->if_flags | ifp->if_drv_flags;
                  ifr->ifr_flags = temp_flags & 0xffff;
                  ifr->ifr_flagshigh = temp_flags >> 16;
                  break;
  
          case SIOCGIFCAP:
                  ifr->ifr_reqcap = ifp->if_capabilities;
                  ifr->ifr_curcap = ifp->if_capenable;
                  break;
  
  #ifdef MAC
          case SIOCGIFMAC:
                  error = mac_ifnet_ioctl_get(td->td_ucred, ifr, ifp);
                  break;
  #endif
  
          case SIOCGIFMETRIC:
                  ifr->ifr_metric = ifp->if_metric;
                  break;
  
          case SIOCGIFMTU:
                  ifr->ifr_mtu = ifp->if_mtu;
                  break;
  
          case SIOCGIFPHYS:
                  ifr->ifr_phys = ifp->if_physical;
                  break;
  
          case SIOCGIFDESCR:
                  error = 0;
                  sx_slock(&ifdescr_sx);
                  if (ifp->if_description == NULL)
                          error = ENOMSG;
                  else {
                          /* space for terminating nul */
                          descrlen = strlen(ifp->if_description) + 1;
                          if (ifr->ifr_buffer.length < descrlen)
                                  ifr->ifr_buffer.buffer = NULL;
                          else
                                  error = copyout(ifp->if_description,
                                      ifr->ifr_buffer.buffer, descrlen);
                          ifr->ifr_buffer.length = descrlen;
                  }
                  sx_sunlock(&ifdescr_sx);
                  break;
  
          case SIOCSIFDESCR:
                  error = priv_check(td, PRIV_NET_SETIFDESCR);
                  if (error)
                          return (error);
  
                  /*
                   * Copy only (length-1) bytes to make sure that
                   * if_description is always nul terminated.  The
                   * length parameter is supposed to count the
                   * terminating nul in.
                   */
                  if (ifr->ifr_buffer.length > ifdescr_maxlen)
                          return (ENAMETOOLONG);
                  else if (ifr->ifr_buffer.length == 0)
                          descrbuf = NULL;
                  else {
                          descrbuf = malloc(ifr->ifr_buffer.length, M_IFDESCR,
                              M_WAITOK | M_ZERO);
                          error = copyin(ifr->ifr_buffer.buffer, descrbuf,
                              ifr->ifr_buffer.length - 1);
                          if (error) {
                                  free(descrbuf, M_IFDESCR);
                                  break;
                          }
                  }
  
                  sx_xlock(&ifdescr_sx);
                  odescrbuf = ifp->if_description;
                  ifp->if_description = descrbuf;
                  sx_xunlock(&ifdescr_sx);
  
                  getmicrotime(&ifp->if_lastchange);
                  free(odescrbuf, M_IFDESCR);
                  break;
  
          case SIOCGIFFIB:
                  ifr->ifr_fib = ifp->if_fib;
                  break;
  
          case SIOCSIFFIB:
                  error = priv_check(td, PRIV_NET_SETIFFIB);
                  if (error)
                          return (error);
                  if (ifr->ifr_fib >= rt_numfibs)
                          return (EINVAL);
  
                  ifp->if_fib = ifr->ifr_fib;
                  break;
  
          case SIOCSIFFLAGS:
                  error = priv_check(td, PRIV_NET_SETIFFLAGS);
                  if (error)
                          return (error);
                  /*
                   * Currently, no driver owned flags pass the IFF_CANTCHANGE
                   * check, so we don't need special handling here yet.
                   */
                  new_flags = (ifr->ifr_flags & 0xffff) |
                      (ifr->ifr_flagshigh << 16);
                  if (ifp->if_flags & IFF_SMART) {
                          /* Smart drivers twiddle their own routes */
                  } else if (ifp->if_flags & IFF_UP &&
                      (new_flags & IFF_UP) == 0) {
                          int s = splimp();
                          if_down(ifp);
                          splx(s);
                  } else if (new_flags & IFF_UP &&
                      (ifp->if_flags & IFF_UP) == 0) {
                          int s = splimp();
                          if_up(ifp);
                          splx(s);
                  }
                  /* See if permanently promiscuous mode bit is about to flip */
                  if ((ifp->if_flags ^ new_flags) & IFF_PPROMISC) {
                          if (new_flags & IFF_PPROMISC)
                                  ifp->if_flags |= IFF_PROMISC;
                          else if (ifp->if_pcount == 0)
                                  ifp->if_flags &= ~IFF_PROMISC;
                          log(LOG_INFO, "%s: permanently promiscuous mode %s\n",
                              ifp->if_xname,
                              (new_flags & IFF_PPROMISC) ? "enabled" : "disabled");
                  }
                  ifp->if_flags = (ifp->if_flags & IFF_CANTCHANGE) |
                          (new_flags &~ IFF_CANTCHANGE);
                  if (ifp->if_ioctl) {
                          (void) (*ifp->if_ioctl)(ifp, cmd, data);
                  }
                  getmicrotime(&ifp->if_lastchange);
                  break;
  
          case SIOCSIFCAP:
                  error = priv_check(td, PRIV_NET_SETIFCAP);
                  if (error)
                          return (error);
                  if (ifp->if_ioctl == NULL)
                          return (EOPNOTSUPP);
                  if (ifr->ifr_reqcap & ~ifp->if_capabilities)
                          return (EINVAL);
                  error = (*ifp->if_ioctl)(ifp, cmd, data);
                  if (error == 0)
                          getmicrotime(&ifp->if_lastchange);
                  break;
  
  #ifdef MAC
          case SIOCSIFMAC:
                  error = mac_ifnet_ioctl_set(td->td_ucred, ifr, ifp);
                  break;
  #endif
  
          case SIOCSIFNAME:
                  error = priv_check(td, PRIV_NET_SETIFNAME);
                  if (error)
                          return (error);
                  error = copyinstr(ifr->ifr_data, new_name, IFNAMSIZ, NULL);
                  if (error != 0)
                          return (error);
                  if (new_name[0] == '\0')
                          return (EINVAL);
                  if (ifunit(new_name) != NULL)
                          return (EEXIST);
  
                  /*
                   * XXX: Locking.  Nothing else seems to lock if_flags,
                   * and there are numerous other races with the
                   * ifunit() checks not being atomic with namespace
                   * changes (renames, vmoves, if_attach, etc).
                   */
                  ifp->if_flags |= IFF_RENAMING;
                  
                  /* Announce the departure of the interface. */
                  rt_ifannouncemsg(ifp, IFAN_DEPARTURE);
                  EVENTHANDLER_INVOKE(ifnet_departure_event, ifp);
  
                  log(LOG_INFO, "%s: changing name to '%s'\n",
                      ifp->if_xname, new_name);
  
                  strlcpy(ifp->if_xname, new_name, sizeof(ifp->if_xname));
                  ifa = ifp->if_addr;
                  IFA_LOCK(ifa);
                  sdl = (struct sockaddr_dl *)ifa->ifa_addr;
                  namelen = strlen(new_name);
                  onamelen = sdl->sdl_nlen;
                  /*
                   * Move the address if needed.  This is safe because we
                   * allocate space for a name of length IFNAMSIZ when we
                   * create this in if_attach().
                   */
                  if (namelen != onamelen) {
                          bcopy(sdl->sdl_data + onamelen,
                              sdl->sdl_data + namelen, sdl->sdl_alen);
                  }
                  bcopy(new_name, sdl->sdl_data, namelen);
                  sdl->sdl_nlen = namelen;
                  sdl = (struct sockaddr_dl *)ifa->ifa_netmask;
                  bzero(sdl->sdl_data, onamelen);
                  while (namelen != 0)
                          sdl->sdl_data[--namelen] = 0xff;
                  IFA_UNLOCK(ifa);
  
                  EVENTHANDLER_INVOKE(ifnet_arrival_event, ifp);
                  /* Announce the return of the interface. */
                  rt_ifannouncemsg(ifp, IFAN_ARRIVAL);
  
                  ifp->if_flags &= ~IFF_RENAMING;
                  break;
  
  #ifdef VIMAGE
          case SIOCSIFVNET:
                  error = priv_check(td, PRIV_NET_SETIFVNET);
                  if (error)
                          return (error);
                  error = if_vmove_loan(td, ifp, ifr->ifr_name, ifr->ifr_jid);
                  break;
  #endif
  
          case SIOCSIFMETRIC:
                  error = priv_check(td, PRIV_NET_SETIFMETRIC);
                  if (error)
                          return (error);
                  ifp->if_metric = ifr->ifr_metric;
                  getmicrotime(&ifp->if_lastchange);
                  break;
  
          case SIOCSIFPHYS:
                  error = priv_check(td, PRIV_NET_SETIFPHYS);
                  if (error)
                          return (error);
                  if (ifp->if_ioctl == NULL)
                          return (EOPNOTSUPP);
                  error = (*ifp->if_ioctl)(ifp, cmd, data);
                  if (error == 0)
                          getmicrotime(&ifp->if_lastchange);
                  break;
  
          case SIOCSIFMTU:
          {
                  u_long oldmtu = ifp->if_mtu;
  
                  error = priv_check(td, PRIV_NET_SETIFMTU);
                  if (error)
                          return (error);
                  if (ifr->ifr_mtu < IF_MINMTU || ifr->ifr_mtu > IF_MAXMTU)
                          return (EINVAL);
                  if (ifp->if_ioctl == NULL)
                          return (EOPNOTSUPP);
                  error = (*ifp->if_ioctl)(ifp, cmd, data);
                  if (error == 0) {
                          getmicrotime(&ifp->if_lastchange);
                          rt_ifmsg(ifp);
                  }
                  /*
                   * If the link MTU changed, do network layer specific procedure.
                   */
                  if (ifp->if_mtu != oldmtu) {
  #ifdef INET6
                          nd6_setmtu(ifp);
  #endif
                  }
                  break;
          }
  
          case SIOCADDMULTI:
          case SIOCDELMULTI:
                  if (cmd == SIOCADDMULTI)
                          error = priv_check(td, PRIV_NET_ADDMULTI);
                  else
                          error = priv_check(td, PRIV_NET_DELMULTI);
                  if (error)
                          return (error);
  
                  /* Don't allow group membership on non-multicast interfaces. */
                  if ((ifp->if_flags & IFF_MULTICAST) == 0)
                          return (EOPNOTSUPP);
  
                  /* Don't let users screw up protocols' entries. */
                  if (ifr->ifr_addr.sa_family != AF_LINK)
                          return (EINVAL);
  
                  if (cmd == SIOCADDMULTI) {
                          struct ifmultiaddr *ifma;
  
                          /*
                           * Userland is only permitted to join groups once
                           * via the if_addmulti() KPI, because it cannot hold
                           * struct ifmultiaddr * between calls. It may also
                           * lose a race while we check if the membership
                           * already exists.
                           */
                          IF_ADDR_LOCK(ifp);
                          ifma = if_findmulti(ifp, &ifr->ifr_addr);
                          IF_ADDR_UNLOCK(ifp);
                          if (ifma != NULL)
                                  error = EADDRINUSE;
                          else
                                  error = if_addmulti(ifp, &ifr->ifr_addr, &ifma);
                  } else {
                          error = if_delmulti(ifp, &ifr->ifr_addr);
                  }
                  if (error == 0)
                          getmicrotime(&ifp->if_lastchange);
                  break;
  
          case SIOCSIFPHYADDR:
          case SIOCDIFPHYADDR:
  #ifdef INET6
          case SIOCSIFPHYADDR_IN6:
  #endif
          case SIOCSLIFPHYADDR:
          case SIOCSIFMEDIA:
          case SIOCSIFGENERIC:
                  error = priv_check(td, PRIV_NET_HWIOCTL);
                  if (error)
                          return (error);
                  if (ifp->if_ioctl == NULL)
                          return (EOPNOTSUPP);
                  error = (*ifp->if_ioctl)(ifp, cmd, data);
                  if (error == 0)
                          getmicrotime(&ifp->if_lastchange);
                  break;
  
          case SIOCGIFSTATUS:
                  ifs = (struct ifstat *)data;
                  ifs->ascii[0] = '\0';
  
          case SIOCGIFPSRCADDR:
          case SIOCGIFPDSTADDR:
          case SIOCGLIFPHYADDR:
          case SIOCGIFMEDIA:
          case SIOCGIFGENERIC:
                  if (ifp->if_ioctl == NULL)
                          return (EOPNOTSUPP);
                  error = (*ifp->if_ioctl)(ifp, cmd, data);
                  break;
  
          case SIOCSIFLLADDR:
                  error = priv_check(td, PRIV_NET_SETLLADDR);
                  if (error)
                          return (error);
                  error = if_setlladdr(ifp,
                      ifr->ifr_addr.sa_data, ifr->ifr_addr.sa_len);
                  EVENTHANDLER_INVOKE(iflladdr_event, ifp);
                  break;
  
          case SIOCAIFGROUP:
          {
                  struct ifgroupreq *ifgr = (struct ifgroupreq *)ifr;
  
                  error = priv_check(td, PRIV_NET_ADDIFGROUP);
                  if (error)
                          return (error);
                  if ((error = if_addgroup(ifp, ifgr->ifgr_group)))
                          return (error);
                  break;
          }
  
          case SIOCGIFGROUP:
                  if ((error = if_getgroup((struct ifgroupreq *)ifr, ifp)))
                          return (error);
                  break;
  
          case SIOCDIFGROUP:
          {
                  struct ifgroupreq *ifgr = (struct ifgroupreq *)ifr;
  
                  error = priv_check(td, PRIV_NET_DELIFGROUP);
                  if (error)
                          return (error);
                  if ((error = if_delgroup(ifp, ifgr->ifgr_group)))
                          return (error);
                  break;
          }
  
          default:
                  error = ENOIOCTL;
                  break;
          }
          return (error);
  }
  
  #ifdef COMPAT_FREEBSD32
  struct ifconf32 {
          int32_t ifc_len;
          union {
                  uint32_t        ifcu_buf;
                  uint32_t        ifcu_req;
          } ifc_ifcu;
  };
  #define SIOCGIFCONF32   _IOWR('i', 36, struct ifconf32)
  #endif
  
  /*
   * Interface ioctls.
   */
  int
  ifioctl(struct socket *so, u_long cmd, caddr_t data, struct thread *td)
  {
          struct ifnet *ifp;
          struct ifreq *ifr;
          int error;
          int oif_flags;
  
          CURVNET_SET(so->so_vnet);
          switch (cmd) {
          case SIOCGIFCONF:
          case OSIOCGIFCONF:
                  error = ifconf(cmd, data);
                  CURVNET_RESTORE();
                  return (error);
  
  #ifdef COMPAT_FREEBSD32
          case SIOCGIFCONF32:
                  {
                          struct ifconf32 *ifc32;
                          struct ifconf ifc;
  
                          ifc32 = (struct ifconf32 *)data;
                          ifc.ifc_len = ifc32->ifc_len;
                          ifc.ifc_buf = PTRIN(ifc32->ifc_buf);
  
                          error = ifconf(SIOCGIFCONF, (void *)&ifc);
                          CURVNET_RESTORE();
                          if (error == 0)
                                  ifc32->ifc_len = ifc.ifc_len;
                          return (error);
                  }
  #endif
          }
          ifr = (struct ifreq *)data;
  
          switch (cmd) {
  #ifdef VIMAGE
          case SIOCSIFRVNET:
                  error = priv_check(td, PRIV_NET_SETIFVNET);
                  if (error == 0)
                          error = if_vmove_reclaim(td, ifr->ifr_name,
                              ifr->ifr_jid);
                  CURVNET_RESTORE();
                  return (error);
  #endif
          case SIOCIFCREATE:
          case SIOCIFCREATE2:
                  error = priv_check(td, PRIV_NET_IFCREATE);
                  if (error == 0)
                          error = if_clone_create(ifr->ifr_name,
                              sizeof(ifr->ifr_name),
                              cmd == SIOCIFCREATE2 ? ifr->ifr_data : NULL);
                  CURVNET_RESTORE();
                  return (error);
          case SIOCIFDESTROY:
                  error = priv_check(td, PRIV_NET_IFDESTROY);
                  if (error == 0)
                          error = if_clone_destroy(ifr->ifr_name);
                  CURVNET_RESTORE();
                  return (error);
  
          case SIOCIFGCLONERS:
                  error = if_clone_list((struct if_clonereq *)data);
                  CURVNET_RESTORE();
                  return (error);
          case SIOCGIFGMEMB:
                  error = if_getgroupmembers((struct ifgroupreq *)data);
                  CURVNET_RESTORE();
                  return (error);
          }
  
          ifp = ifunit_ref(ifr->ifr_name);
          if (ifp == NULL) {
                  CURVNET_RESTORE();
                  return (ENXIO);
          }
  
          error = ifhwioctl(cmd, ifp, data, td);
          if (error != ENOIOCTL) {
                  if_rele(ifp);
                  CURVNET_RESTORE();
                  return (error);
          }
  
          oif_flags = ifp->if_flags;
          if (so->so_proto == NULL) {
                  if_rele(ifp);
                  CURVNET_RESTORE();
                  return (EOPNOTSUPP);
          }
  #ifndef COMPAT_43
          error = ((*so->so_proto->pr_usrreqs->pru_control)(so, cmd,
                                                                   data,
                                                                   ifp, td));
          if (error == EOPNOTSUPP && ifp != NULL && ifp->if_ioctl != NULL)
                  error = (*ifp->if_ioctl)(ifp, cmd, data);
  #else
          {
                  u_long ocmd = cmd;
  
                  switch (cmd) {
  
                  case SIOCSIFDSTADDR:
                  case SIOCSIFADDR:
                  case SIOCSIFBRDADDR:
                  case SIOCSIFNETMASK:
  #if BYTE_ORDER != BIG_ENDIAN
                          if (ifr->ifr_addr.sa_family == 0 &&
                              ifr->ifr_addr.sa_len < 16) {
                                  ifr->ifr_addr.sa_family = ifr->ifr_addr.sa_len;
                                  ifr->ifr_addr.sa_len = 16;
                          }
  #else
                          if (ifr->ifr_addr.sa_len == 0)
                                  ifr->ifr_addr.sa_len = 16;
  #endif
                          break;
  
                  case OSIOCGIFADDR:
                          cmd = SIOCGIFADDR;
                          break;
  
                  case OSIOCGIFDSTADDR:
                          cmd = SIOCGIFDSTADDR;
                          break;
  
                  case OSIOCGIFBRDADDR:
                          cmd = SIOCGIFBRDADDR;
                          break;
  
                  case OSIOCGIFNETMASK:
                          cmd = SIOCGIFNETMASK;
                  }
                  error =  ((*so->so_proto->pr_usrreqs->pru_control)(so,
                                                                     cmd,
                                                                     data,
                                                                     ifp, td));
                  if (error == EOPNOTSUPP && ifp != NULL &&
                      ifp->if_ioctl != NULL)
                          error = (*ifp->if_ioctl)(ifp, cmd, data);
                  switch (ocmd) {
  
                  case OSIOCGIFADDR:
                  case OSIOCGIFDSTADDR:
                  case OSIOCGIFBRDADDR:
                  case OSIOCGIFNETMASK:
                          *(u_short *)&ifr->ifr_addr = ifr->ifr_addr.sa_family;
  
                  }
          }
  #endif /* COMPAT_43 */
  
          if ((oif_flags ^ ifp->if_flags) & IFF_UP) {
  #ifdef INET6
                  if (ifp->if_flags & IFF_UP) {
                          int s = splimp();
                          in6_if_up(ifp);
                          splx(s);
                  }
  #endif
          }
          if_rele(ifp);
          CURVNET_RESTORE();
          return (error);
  }
  
  /*
   * The code common to handling reference counted flags,
   * e.g., in ifpromisc() and if_allmulti().
   * The "pflag" argument can specify a permanent mode flag to check,
   * such as IFF_PPROMISC for promiscuous mode; should be 0 if none.
   *
   * Only to be used on stack-owned flags, not driver-owned flags.
   */
  static int
  if_setflag(struct ifnet *ifp, int flag, int pflag, int *refcount, int onswitch)
  {
          struct ifreq ifr;
          int error;
          int oldflags, oldcount;
  
          /* Sanity checks to catch programming errors */
          KASSERT((flag & (IFF_DRV_OACTIVE|IFF_DRV_RUNNING)) == 0,
              ("%s: setting driver-owned flag %d", __func__, flag));
  
          if (onswitch)
                  KASSERT(*refcount >= 0,
                      ("%s: increment negative refcount %d for flag %d",
                      __func__, *refcount, flag));
          else
                  KASSERT(*refcount > 0,
                      ("%s: decrement non-positive refcount %d for flag %d",
                      __func__, *refcount, flag));
  
          /* In case this mode is permanent, just touch refcount */
          if (ifp->if_flags & pflag) {
                  *refcount += onswitch ? 1 : -1;
                  return (0);
          }
  
          /* Save ifnet parameters for if_ioctl() may fail */
          oldcount = *refcount;
          oldflags = ifp->if_flags;
          
          /*
           * See if we aren't the only and touching refcount is enough.
           * Actually toggle interface flag if we are the first or last.
           */
          if (onswitch) {
                  if ((*refcount)++)
                          return (0);
                  ifp->if_flags |= flag;
          } else {
                  if (--(*refcount))
                          return (0);
                  ifp->if_flags &= ~flag;
          }
  
          /* Call down the driver since we've changed interface flags */
          if (ifp->if_ioctl == NULL) {
                  error = EOPNOTSUPP;
                  goto recover;
          }
          ifr.ifr_flags = ifp->if_flags & 0xffff;
          ifr.ifr_flagshigh = ifp->if_flags >> 16;
          error = (*ifp->if_ioctl)(ifp, SIOCSIFFLAGS, (caddr_t)&ifr);
          if (error)
                  goto recover;
          /* Notify userland that interface flags have changed */
          rt_ifmsg(ifp);
          return (0);
  
  recover:
          /* Recover after driver error */
          *refcount = oldcount;
          ifp->if_flags = oldflags;
          return (error);
  }
  
  /*
   * Set/clear promiscuous mode on interface ifp based on the truth value
   * of pswitch.  The calls are reference counted so that only the first
   * "on" request actually has an effect, as does the final "off" request.
   * Results are undefined if the "off" and "on" requests are not matched.
   */
  int
  ifpromisc(struct ifnet *ifp, int pswitch)
  {
          int error;
          int oldflags = ifp->if_flags;
  
          error = if_setflag(ifp, IFF_PROMISC, IFF_PPROMISC,
                             &ifp->if_pcount, pswitch);
          /* If promiscuous mode status has changed, log a message */
          if (error == 0 && ((ifp->if_flags ^ oldflags) & IFF_PROMISC))
                  log(LOG_INFO, "%s: promiscuous mode %s\n",
                      ifp->if_xname,
                      (ifp->if_flags & IFF_PROMISC) ? "enabled" : "disabled");
          return (error);
  }
  
  /*
   * Return interface configuration
   * of system.  List may be used
   * in later ioctl's (above) to get
   * other information.
   */
  /*ARGSUSED*/
  static int
  ifconf(u_long cmd, caddr_t data)
  {
          struct ifconf *ifc = (struct ifconf *)data;
          struct ifnet *ifp;
          struct ifaddr *ifa;
          struct ifreq ifr;
          struct sbuf *sb;
          int error, full = 0, valid_len, max_len;
  
          /* Limit initial buffer size to MAXPHYS to avoid DoS from userspace. */
          max_len = MAXPHYS - 1;
  
          /* Prevent hostile input from being able to crash the system */
          if (ifc->ifc_len <= 0)
                  return (EINVAL);
  
  again:
          if (ifc->ifc_len <= max_len) {
                  max_len = ifc->ifc_len;
                  full = 1;
          }
          sb = sbuf_new(NULL, NULL, max_len + 1, SBUF_FIXEDLEN);
          max_len = 0;
          valid_len = 0;
  
          IFNET_RLOCK();
          TAILQ_FOREACH(ifp, &V_ifnet, if_link) {
                  int addrs;
  
                  /*
                   * Zero the ifr_name buffer to make sure we don't
                   * disclose the contents of the stack.
                   */
                  memset(ifr.ifr_name, 0, sizeof(ifr.ifr_name));
  
                  if (strlcpy(ifr.ifr_name, ifp->if_xname, sizeof(ifr.ifr_name))
                      >= sizeof(ifr.ifr_name)) {
                          sbuf_delete(sb);
                          IFNET_RUNLOCK();
                          return (ENAMETOOLONG);
                  }
  
                  addrs = 0;
                  IF_ADDR_LOCK(ifp);
                  TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                          struct sockaddr *sa = ifa->ifa_addr;
  
                          if (prison_if(curthread->td_ucred, sa) != 0)
                                  continue;
                          addrs++;
  #ifdef COMPAT_43
                          if (cmd == OSIOCGIFCONF) {
                                  struct osockaddr *osa =
                                           (struct osockaddr *)&ifr.ifr_addr;
                                  ifr.ifr_addr = *sa;
                                  osa->sa_family = sa->sa_family;
                                  sbuf_bcat(sb, &ifr, sizeof(ifr));
                                  max_len += sizeof(ifr);
                          } else
  #endif
                          if (sa->sa_len <= sizeof(*sa)) {
                                  ifr.ifr_addr = *sa;
                                  sbuf_bcat(sb, &ifr, sizeof(ifr));
                                  max_len += sizeof(ifr);
                          } else {
                                  sbuf_bcat(sb, &ifr,
                                      offsetof(struct ifreq, ifr_addr));
                                  max_len += offsetof(struct ifreq, ifr_addr);
                                  sbuf_bcat(sb, sa, sa->sa_len);
                                  max_len += sa->sa_len;
                          }
  
                          if (sbuf_error(sb) == 0)
                                  valid_len = sbuf_len(sb);
                  }
                  IF_ADDR_UNLOCK(ifp);
                  if (addrs == 0) {
                          bzero((caddr_t)&ifr.ifr_addr, sizeof(ifr.ifr_addr));
                          sbuf_bcat(sb, &ifr, sizeof(ifr));
                          max_len += sizeof(ifr);
  
                          if (sbuf_error(sb) == 0)
                                  valid_len = sbuf_len(sb);
                  }
          }
          IFNET_RUNLOCK();
  
          /*
           * If we didn't allocate enough space (uncommon), try again.  If
           * we have already allocated as much space as we are allowed,
           * return what we've got.
           */
          if (valid_len != max_len && !full) {
                  sbuf_delete(sb);
                  goto again;
          }
  
          ifc->ifc_len = valid_len;
          sbuf_finish(sb);
          error = copyout(sbuf_data(sb), ifc->ifc_req, ifc->ifc_len);
          sbuf_delete(sb);
          return (error);
  }
  
  /*
   * Just like ifpromisc(), but for all-multicast-reception mode.
   */
  int
  if_allmulti(struct ifnet *ifp, int onswitch)
  {
  
          return (if_setflag(ifp, IFF_ALLMULTI, 0, &ifp->if_amcount, onswitch));
  }
  
  struct ifmultiaddr *
  if_findmulti(struct ifnet *ifp, struct sockaddr *sa)
  {
          struct ifmultiaddr *ifma;
  
          IF_ADDR_LOCK_ASSERT(ifp);
  
          TAILQ_FOREACH(ifma, &ifp->if_multiaddrs, ifma_link) {
                  if (sa->sa_family == AF_LINK) {
                          if (sa_dl_equal(ifma->ifma_addr, sa))
                                  break;
                  } else {
                          if (sa_equal(ifma->ifma_addr, sa))
                                  break;
                  }
          }
  
          return ifma;
  }
  
  /*
   * Allocate a new ifmultiaddr and initialize based on passed arguments.  We
   * make copies of passed sockaddrs.  The ifmultiaddr will not be added to
   * the ifnet multicast address list here, so the caller must do that and
   * other setup work (such as notifying the device driver).  The reference
   * count is initialized to 1.
   */
  static struct ifmultiaddr *
  if_allocmulti(struct ifnet *ifp, struct sockaddr *sa, struct sockaddr *llsa,
      int mflags)
  {
          struct ifmultiaddr *ifma;
          struct sockaddr *dupsa;
  
          ifma = malloc(sizeof *ifma, M_IFMADDR, mflags |
              M_ZERO);
          if (ifma == NULL)
                  return (NULL);
  
          dupsa = malloc(sa->sa_len, M_IFMADDR, mflags);
          if (dupsa == NULL) {
                  free(ifma, M_IFMADDR);
                  return (NULL);
          }
          bcopy(sa, dupsa, sa->sa_len);
          ifma->ifma_addr = dupsa;
  
          ifma->ifma_ifp = ifp;
          ifma->ifma_refcount = 1;
          ifma->ifma_protospec = NULL;
  
          if (llsa == NULL) {
                  ifma->ifma_lladdr = NULL;
                  return (ifma);
          }
  
          dupsa = malloc(llsa->sa_len, M_IFMADDR, mflags);
          if (dupsa == NULL) {
                  free(ifma->ifma_addr, M_IFMADDR);
                  free(ifma, M_IFMADDR);
                  return (NULL);
          }
          bcopy(llsa, dupsa, llsa->sa_len);
          ifma->ifma_lladdr = dupsa;
  
          return (ifma);
  }
  
  /*
   * if_freemulti: free ifmultiaddr structure and possibly attached related
   * addresses.  The caller is responsible for implementing reference
   * counting, notifying the driver, handling routing messages, and releasing
   * any dependent link layer state.
   */
  static void
  if_freemulti(struct ifmultiaddr *ifma)
  {
  
          KASSERT(ifma->ifma_refcount == 0, ("if_freemulti: refcount %d",
              ifma->ifma_refcount));
          KASSERT(ifma->ifma_protospec == NULL,
              ("if_freemulti: protospec not NULL"));
  
          if (ifma->ifma_lladdr != NULL)
                  free(ifma->ifma_lladdr, M_IFMADDR);
          free(ifma->ifma_addr, M_IFMADDR);
          free(ifma, M_IFMADDR);
  }
  
  /*
   * Register an additional multicast address with a network interface.
   *
   * - If the address is already present, bump the reference count on the
   *   address and return.
   * - If the address is not link-layer, look up a link layer address.
   * - Allocate address structures for one or both addresses, and attach to the
   *   multicast address list on the interface.  If automatically adding a link
   *   layer address, the protocol address will own a reference to the link
   *   layer address, to be freed when it is freed.
   * - Notify the network device driver of an addition to the multicast address
   *   list.
   *
   * 'sa' points to caller-owned memory with the desired multicast address.
   *
   * 'retifma' will be used to return a pointer to the resulting multicast
   * address reference, if desired.
   */
  int
  if_addmulti(struct ifnet *ifp, struct sockaddr *sa,
      struct ifmultiaddr **retifma)
  {
          struct ifmultiaddr *ifma, *ll_ifma;
          struct sockaddr *llsa;
          int error;
  
          /*
           * If the address is already present, return a new reference to it;
           * otherwise, allocate storage and set up a new address.
           */
          IF_ADDR_LOCK(ifp);
          ifma = if_findmulti(ifp, sa);
          if (ifma != NULL) {
                  ifma->ifma_refcount++;
                  if (retifma != NULL)
                          *retifma = ifma;
                  IF_ADDR_UNLOCK(ifp);
                  return (0);
          }
  
          /*
           * The address isn't already present; resolve the protocol address
           * into a link layer address, and then look that up, bump its
           * refcount or allocate an ifma for that also.  If 'llsa' was
           * returned, we will need to free it later.
           */
          llsa = NULL;
          ll_ifma = NULL;
          if (ifp->if_resolvemulti != NULL) {
                  error = ifp->if_resolvemulti(ifp, &llsa, sa);
                  if (error)
                          goto unlock_out;
          }
  
          /*
           * Allocate the new address.  Don't hook it up yet, as we may also
           * need to allocate a link layer multicast address.
           */
          ifma = if_allocmulti(ifp, sa, llsa, M_NOWAIT);
          if (ifma == NULL) {
                  error = ENOMEM;
                  goto free_llsa_out;
          }
  
          /*
           * If a link layer address is found, we'll need to see if it's
           * already present in the address list, or allocate is as well.
           * When this block finishes, the link layer address will be on the
           * list.
           */
          if (llsa != NULL) {
                  ll_ifma = if_findmulti(ifp, llsa);
                  if (ll_ifma == NULL) {
                          ll_ifma = if_allocmulti(ifp, llsa, NULL, M_NOWAIT);
                          if (ll_ifma == NULL) {
                                  --ifma->ifma_refcount;
                                  if_freemulti(ifma);
                                  error = ENOMEM;
                                  goto free_llsa_out;
                          }
                          TAILQ_INSERT_HEAD(&ifp->if_multiaddrs, ll_ifma,
                              ifma_link);
                  } else
                          ll_ifma->ifma_refcount++;
                  ifma->ifma_llifma = ll_ifma;
          }
  
          /*
           * We now have a new multicast address, ifma, and possibly a new or
           * referenced link layer address.  Add the primary address to the
           * ifnet address list.
           */
          TAILQ_INSERT_HEAD(&ifp->if_multiaddrs, ifma, ifma_link);
  
          if (retifma != NULL)
                  *retifma = ifma;
  
          /*
           * Must generate the message while holding the lock so that 'ifma'
           * pointer is still valid.
           */
          rt_newmaddrmsg(RTM_NEWMADDR, ifma);
          IF_ADDR_UNLOCK(ifp);
  
          /*
           * We are certain we have added something, so call down to the
           * interface to let them know about it.
           */
          if (ifp->if_ioctl != NULL) {
                  (void) (*ifp->if_ioctl)(ifp, SIOCADDMULTI, 0);
          }
  
          if (llsa != NULL)
                  free(llsa, M_IFMADDR);
  
          return (0);
  
  free_llsa_out:
          if (llsa != NULL)
                  free(llsa, M_IFMADDR);
  
  unlock_out:
          IF_ADDR_UNLOCK(ifp);
          return (error);
  }
  
  /*
   * Delete a multicast group membership by network-layer group address.
   *
   * Returns ENOENT if the entry could not be found. If ifp no longer
   * exists, results are undefined. This entry point should only be used
   * from subsystems which do appropriate locking to hold ifp for the
   * duration of the call.
   * Network-layer protocol domains must use if_delmulti_ifma().
   */
  int
  if_delmulti(struct ifnet *ifp, struct sockaddr *sa)
  {
          struct ifmultiaddr *ifma;
          int lastref;
  #ifdef INVARIANTS
          struct ifnet *oifp;
  
          IFNET_RLOCK_NOSLEEP();
          TAILQ_FOREACH(oifp, &V_ifnet, if_link)
                  if (ifp == oifp)
                          break;
          if (ifp != oifp)
                  ifp = NULL;
          IFNET_RUNLOCK_NOSLEEP();
  
          KASSERT(ifp != NULL, ("%s: ifnet went away", __func__));
  #endif
          if (ifp == NULL)
                  return (ENOENT);
  
          IF_ADDR_LOCK(ifp);
          lastref = 0;
          ifma = if_findmulti(ifp, sa);
          if (ifma != NULL)
                  lastref = if_delmulti_locked(ifp, ifma, 0);
          IF_ADDR_UNLOCK(ifp);
  
          if (ifma == NULL)
                  return (ENOENT);
  
          if (lastref && ifp->if_ioctl != NULL) {
                  (void)(*ifp->if_ioctl)(ifp, SIOCDELMULTI, 0);
          }
  
          return (0);
  }
  
  /*
   * Delete all multicast group membership for an interface.
   * Should be used to quickly flush all multicast filters.
   */
  void
  if_delallmulti(struct ifnet *ifp)
  {
          struct ifmultiaddr *ifma;
          struct ifmultiaddr *next;
  
          IF_ADDR_LOCK(ifp);
          TAILQ_FOREACH_SAFE(ifma, &ifp->if_multiaddrs, ifma_link, next)
                  if_delmulti_locked(ifp, ifma, 0);
          IF_ADDR_UNLOCK(ifp);
  }
  
  /*
   * Delete a multicast group membership by group membership pointer.
   * Network-layer protocol domains must use this routine.
   *
   * It is safe to call this routine if the ifp disappeared.
   */
  void
  if_delmulti_ifma(struct ifmultiaddr *ifma)
  {
          struct ifnet *ifp;
          int lastref;
  
          ifp = ifma->ifma_ifp;
  #ifdef DIAGNOSTIC
          if (ifp == NULL) {
                  printf("%s: ifma_ifp seems to be detached\n", __func__);
          } else {
                  struct ifnet *oifp;
  
                  IFNET_RLOCK_NOSLEEP();
                  TAILQ_FOREACH(oifp, &V_ifnet, if_link)
                          if (ifp == oifp)
                                  break;
                  if (ifp != oifp) {
                          printf("%s: ifnet %p disappeared\n", __func__, ifp);
                          ifp = NULL;
                  }
                  IFNET_RUNLOCK_NOSLEEP();
          }
  #endif
          /*
           * If and only if the ifnet instance exists: Acquire the address lock.
           */
          if (ifp != NULL)
                  IF_ADDR_LOCK(ifp);
  
          lastref = if_delmulti_locked(ifp, ifma, 0);
  
          if (ifp != NULL) {
                  /*
                   * If and only if the ifnet instance exists:
                   *  Release the address lock.
                   *  If the group was left: update the hardware hash filter.
                   */
                  IF_ADDR_UNLOCK(ifp);
                  if (lastref && ifp->if_ioctl != NULL) {
                          (void)(*ifp->if_ioctl)(ifp, SIOCDELMULTI, 0);
                  }
          }
  }
  
  /*
   * Perform deletion of network-layer and/or link-layer multicast address.
   *
   * Return 0 if the reference count was decremented.
   * Return 1 if the final reference was released, indicating that the
   * hardware hash filter should be reprogrammed.
   */
  static int
  if_delmulti_locked(struct ifnet *ifp, struct ifmultiaddr *ifma, int detaching)
  {
          struct ifmultiaddr *ll_ifma;
  
          if (ifp != NULL && ifma->ifma_ifp != NULL) {
                  KASSERT(ifma->ifma_ifp == ifp,
                      ("%s: inconsistent ifp %p", __func__, ifp));
                  IF_ADDR_LOCK_ASSERT(ifp);
          }
  
          ifp = ifma->ifma_ifp;
  
          /*
           * If the ifnet is detaching, null out references to ifnet,
           * so that upper protocol layers will notice, and not attempt
           * to obtain locks for an ifnet which no longer exists. The
           * routing socket announcement must happen before the ifnet
           * instance is detached from the system.
           */
          if (detaching) {
  #ifdef DIAGNOSTIC
                  printf("%s: detaching ifnet instance %p\n", __func__, ifp);
  #endif
                  /*
                   * ifp may already be nulled out if we are being reentered
                   * to delete the ll_ifma.
                   */
                  if (ifp != NULL) {
                          rt_newmaddrmsg(RTM_DELMADDR, ifma);
                          ifma->ifma_ifp = NULL;
                  }
          }
  
          if (--ifma->ifma_refcount > 0)
                  return 0;
  
          /*
           * If this ifma is a network-layer ifma, a link-layer ifma may
           * have been associated with it. Release it first if so.
           */
          ll_ifma = ifma->ifma_llifma;
          if (ll_ifma != NULL) {
                  KASSERT(ifma->ifma_lladdr != NULL,
                      ("%s: llifma w/o lladdr", __func__));
                  if (detaching)
                          ll_ifma->ifma_ifp = NULL;       /* XXX */
                  if (--ll_ifma->ifma_refcount == 0) {
                          if (ifp != NULL) {
                                  TAILQ_REMOVE(&ifp->if_multiaddrs, ll_ifma,
                                      ifma_link);
                          }
                          if_freemulti(ll_ifma);
                  }
          }
  
          if (ifp != NULL)
                  TAILQ_REMOVE(&ifp->if_multiaddrs, ifma, ifma_link);
  
          if_freemulti(ifma);
  
          /*
           * The last reference to this instance of struct ifmultiaddr
           * was released; the hardware should be notified of this change.
           */
          return 1;
  }
  
  /*
   * Set the link layer address on an interface.
   *
   * At this time we only support certain types of interfaces,
   * and we don't allow the length of the address to change.
   */
  int
  if_setlladdr(struct ifnet *ifp, const u_char *lladdr, int len)
  {
          struct sockaddr_dl *sdl;
          struct ifaddr *ifa;
          struct ifreq ifr;
  
          IF_ADDR_LOCK(ifp);
          ifa = ifp->if_addr;
          if (ifa == NULL) {
                  IF_ADDR_UNLOCK(ifp);
                  return (EINVAL);
          }
          ifa_ref(ifa);
          IF_ADDR_UNLOCK(ifp);
          sdl = (struct sockaddr_dl *)ifa->ifa_addr;
          if (sdl == NULL) {
                  ifa_free(ifa);
                  return (EINVAL);
          }
          if (len != sdl->sdl_alen) {     /* don't allow length to change */
                  ifa_free(ifa);
                  return (EINVAL);
          }
          switch (ifp->if_type) {
          case IFT_ETHER:
          case IFT_FDDI:
          case IFT_XETHER:
          case IFT_ISO88025:
          case IFT_L2VLAN:
          case IFT_BRIDGE:
          case IFT_ARCNET:
          case IFT_IEEE8023ADLAG:
          case IFT_IEEE80211:
                  bcopy(lladdr, LLADDR(sdl), len);
                  ifa_free(ifa);
                  break;
          default:
                  ifa_free(ifa);
                  return (ENODEV);
          }
  
          /*
           * If the interface is already up, we need
           * to re-init it in order to reprogram its
           * address filter.
           */
          if ((ifp->if_flags & IFF_UP) != 0) {
                  if (ifp->if_ioctl) {
                          ifp->if_flags &= ~IFF_UP;
                          ifr.ifr_flags = ifp->if_flags & 0xffff;
                          ifr.ifr_flagshigh = ifp->if_flags >> 16;
                          (*ifp->if_ioctl)(ifp, SIOCSIFFLAGS, (caddr_t)&ifr);
                          ifp->if_flags |= IFF_UP;
                          ifr.ifr_flags = ifp->if_flags & 0xffff;
                          ifr.ifr_flagshigh = ifp->if_flags >> 16;
                          (*ifp->if_ioctl)(ifp, SIOCSIFFLAGS, (caddr_t)&ifr);
                  }
  #ifdef INET
                  /*
                   * Also send gratuitous ARPs to notify other nodes about
                   * the address change.
                   */
                  TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                          if (ifa->ifa_addr->sa_family == AF_INET)
                                  arp_ifinit(ifp, ifa);
                  }
  #endif
          }
          return (0);
  }
  
  /*
   * The name argument must be a pointer to storage which will last as
   * long as the interface does.  For physical devices, the result of
   * device_get_name(dev) is a good choice and for pseudo-devices a
   * static string works well.
   */
  void
  if_initname(struct ifnet *ifp, const char *name, int unit)
  {
          ifp->if_dname = name;
          ifp->if_dunit = unit;
          if (unit != IF_DUNIT_NONE)
                  snprintf(ifp->if_xname, IFNAMSIZ, "%s%d", name, unit);
          else
                  strlcpy(ifp->if_xname, name, IFNAMSIZ);
  }
  
  int
  if_printf(struct ifnet *ifp, const char * fmt, ...)
  {
          va_list ap;
          int retval;
  
          retval = printf("%s: ", ifp->if_xname);
          va_start(ap, fmt);
          retval += vprintf(fmt, ap);
          va_end(ap);
          return (retval);
  }
  
  void
  if_start(struct ifnet *ifp)
  {
  
          (*(ifp)->if_start)(ifp);
  }
  
  /*
   * Backwards compatibility interface for drivers 
   * that have not implemented it
   */
  static int
  if_transmit(struct ifnet *ifp, struct mbuf *m)
  {
          int error;
  
          IFQ_HANDOFF(ifp, m, error);
          return (error);
  }
  
  int
  if_handoff(struct ifqueue *ifq, struct mbuf *m, struct ifnet *ifp, int adjust)
  {
          int active = 0;
  
          IF_LOCK(ifq);
          if (_IF_QFULL(ifq)) {
                  _IF_DROP(ifq);
                  IF_UNLOCK(ifq);
                  m_freem(m);
                  return (0);
          }
          if (ifp != NULL) {
                  ifp->if_obytes += m->m_pkthdr.len + adjust;
                  if (m->m_flags & (M_BCAST|M_MCAST))
                          ifp->if_omcasts++;
                  active = ifp->if_drv_flags & IFF_DRV_OACTIVE;
          }
          _IF_ENQUEUE(ifq, m);
          IF_UNLOCK(ifq);
          if (ifp != NULL && !active)
                  (*(ifp)->if_start)(ifp);
          return (1);
  }
  
  void
  if_register_com_alloc(u_char type,
      if_com_alloc_t *a, if_com_free_t *f)
  {
          
          KASSERT(if_com_alloc[type] == NULL,
              ("if_register_com_alloc: %d already registered", type));
          KASSERT(if_com_free[type] == NULL,
              ("if_register_com_alloc: %d free already registered", type));
  
          if_com_alloc[type] = a;
          if_com_free[type] = f;
  }
  
  void
  if_deregister_com_alloc(u_char type)
  {
          
          KASSERT(if_com_alloc[type] != NULL,
              ("if_deregister_com_alloc: %d not registered", type));
          KASSERT(if_com_free[type] != NULL,
              ("if_deregister_com_alloc: %d free not registered", type));
          if_com_alloc[type] = NULL;
          if_com_free[type] = NULL;
  }