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/6.0/sys/net/if.c 150731 2005-09-29 20:57:07Z rwatson $
     */
    
    #include "opt_compat.h"
    #include "opt_inet6.h"
    #include "opt_inet.h"
    #include "opt_mac.h"
    #include "opt_carp.h"
    
    #include <sys/param.h>
    #include <sys/types.h>
    #include <sys/conf.h>
    #include <sys/mac.h>
    #include <sys/malloc.h>
    #include <sys/sbuf.h>
    #include <sys/bus.h>
    #include <sys/mbuf.h>
    #include <sys/systm.h>
    #include <sys/proc.h>
    #include <sys/socket.h>
    #include <sys/socketvar.h>
    #include <sys/protosw.h>
    #include <sys/kernel.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 <machine/stdarg.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>
    
    #if defined(INET) || defined(INET6)
    /*XXX*/
    #include <netinet/in.h>
    #include <netinet/in_var.h>
    #ifdef INET6
    #include <netinet6/in6_var.h>
    #include <netinet6/in6_ifattach.h>
    #endif
    #endif
    #ifdef INET
    #include <netinet/if_ether.h>
    #endif
    #ifdef DEV_CARP
    #include <netinet/ip_carp.h>
    #endif
    
    SYSCTL_NODE(_net, PF_LINK, link, CTLFLAG_RW, 0, "Link layers");
    SYSCTL_NODE(_net_link, 0, generic, CTLFLAG_RW, 0, "Generic link-management");
    
    /* 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");
    
    void    (*bstp_linkstate_p)(struct ifnet *ifp, int state);
    void    (*ng_ether_link_state_p)(struct ifnet *ifp, int state);
    
    struct mbuf *(*tbr_dequeue_ptr)(struct ifaltq *, int) = NULL;
   
   static void     if_attachdomain(void *);
   static void     if_attachdomain1(struct ifnet *);
   static int      ifconf(u_long, caddr_t);
   static void     if_grow(void);
   static void     if_init(void *);
   static void     if_check(void *);
   static void     if_qflush(struct ifaltq *);
   static void     if_route(struct ifnet *, int flag, int fam);
   static int      if_setflag(struct ifnet *, int, int, int *, int);
   static void     if_slowtimo(void *);
   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 void     if_start_deferred(void *context, int pending);
   static void     do_link_state_change(void *, 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
   
   int     if_index = 0;
   struct  ifindex_entry *ifindex_table = NULL;
   int     ifqmaxlen = IFQ_MAXLEN;
   struct  ifnethead ifnet;        /* depend on static init XXX */
   struct  mtx ifnet_lock;
   static  if_com_alloc_t *if_com_alloc[256];
   static  if_com_free_t *if_com_free[256];
   
   static int      if_indexlim = 8;
   static struct   knlist ifklist;
   
   static void     filt_netdetach(struct knote *kn);
   static int      filt_netdev(struct knote *kn, long hint);
   
   static struct filterops netdev_filtops =
       { 1, NULL, filt_netdetach, filt_netdev };
   
   /*
    * System initialization
    */
   SYSINIT(interfaces, SI_SUB_INIT_IF, SI_ORDER_FIRST, if_init, NULL)
   SYSINIT(interface_check, SI_SUB_PROTO_IF, SI_ORDER_FIRST, if_check, NULL)
   
   MALLOC_DEFINE(M_IFNET, "ifnet", "interface internals");
   MALLOC_DEFINE(M_IFADDR, "ifaddr", "interface address");
   MALLOC_DEFINE(M_IFMADDR, "ether_multi", "link-level multicast address");
   
   static d_open_t         netopen;
   static d_close_t        netclose;
   static d_ioctl_t        netioctl;
   static d_kqfilter_t     netkqfilter;
   
   static struct cdevsw net_cdevsw = {
           .d_version =    D_VERSION,
           .d_flags =      D_NEEDGIANT,
           .d_open =       netopen,
           .d_close =      netclose,
           .d_ioctl =      netioctl,
           .d_name =       "net",
           .d_kqfilter =   netkqfilter,
   };
   
   static int
   netopen(struct cdev *dev, int flag, int mode, struct thread *td)
   {
           return (0);
   }
   
   static int
   netclose(struct cdev *dev, int flags, int fmt, struct thread *td)
   {
           return (0);
   }
   
   static int
   netioctl(struct cdev *dev, u_long cmd, caddr_t data, int flag, struct thread *td)
   {
           struct ifnet *ifp;
           int error, idx;
   
           /* only support interface specific ioctls */
           if (IOCGROUP(cmd) != 'i')
                   return (EOPNOTSUPP);
           idx = minor(dev);
           if (idx == 0) {
                   /*
                    * special network device, not interface.
                    */
                   if (cmd == SIOCGIFCONF)
                           return (ifconf(cmd, data));     /* XXX remove cmd */
                   return (EOPNOTSUPP);
           }
   
           ifp = ifnet_byindex(idx);
           if (ifp == NULL)
                   return (ENXIO);
   
           error = ifhwioctl(cmd, ifp, data, td);
           if (error == ENOIOCTL)
                   error = EOPNOTSUPP;
           return (error);
   }
   
   static int
   netkqfilter(struct cdev *dev, struct knote *kn)
   {
           struct knlist *klist;
           struct ifnet *ifp;
           int idx;
   
           switch (kn->kn_filter) {
           case EVFILT_NETDEV:
                   kn->kn_fop = &netdev_filtops;
                   break;
           default:
                   return (EINVAL);
           }
   
           idx = minor(dev);
           if (idx == 0) {
                   klist = &ifklist;
           } else {
                   ifp = ifnet_byindex(idx);
                   if (ifp == NULL)
                           return (1);
                   klist = &ifp->if_klist;
           }
   
           kn->kn_hook = (caddr_t)klist;
   
           knlist_add(klist, kn, 0);
   
           return (0);
   }
   
   static void
   filt_netdetach(struct knote *kn)
   {
           struct knlist *klist = (struct knlist *)kn->kn_hook;
   
           knlist_remove(klist, kn, 0);
   }
   
   static int
   filt_netdev(struct knote *kn, long hint)
   {
           struct knlist *klist = (struct knlist *)kn->kn_hook;
   
           /*
            * Currently NOTE_EXIT is abused to indicate device detach.
            */
           if (hint == NOTE_EXIT) {
                   kn->kn_data = NOTE_LINKINV;
                   kn->kn_flags |= (EV_EOF | EV_ONESHOT);
                   knlist_remove_inevent(klist, kn);
                   return (1);
           }
           if (hint != 0)
                   kn->kn_data = hint;                     /* current status */
           if (kn->kn_sfflags & hint)
                   kn->kn_fflags |= hint;
           return (kn->kn_fflags != 0);
   }
   
   /*
    * Network interface utility routines.
    *
    * Routines with ifa_ifwith* names take sockaddr *'s as
    * parameters.
    */
   /* ARGSUSED*/
   static void
   if_init(void *dummy __unused)
   {
   
           IFNET_LOCK_INIT();
           TAILQ_INIT(&ifnet);
           knlist_init(&ifklist, NULL, NULL, NULL, NULL);
           if_grow();                              /* create initial table */
           ifdev_byindex(0) = make_dev(&net_cdevsw, 0,
               UID_ROOT, GID_WHEEL, 0600, "network");
           if_clone_init();
   }
   
   static void
   if_grow(void)
   {
           u_int n;
           struct ifindex_entry *e;
   
           if_indexlim <<= 1;
           n = if_indexlim * sizeof(*e);
           e = malloc(n, M_IFNET, M_WAITOK | M_ZERO);
           if (ifindex_table != NULL) {
                   memcpy((caddr_t)e, (caddr_t)ifindex_table, n/2);
                   free((caddr_t)ifindex_table, M_IFNET);
           }
           ifindex_table = e;
   }
   
   /* ARGSUSED*/
   static void
   if_check(void *dummy __unused)
   {
           struct ifnet *ifp;
           int s;
   
           s = splimp();
           IFNET_RLOCK();  /* could sleep on rare error; mostly okay XXX */
           TAILQ_FOREACH(ifp, &ifnet, if_link) {
                   if (ifp->if_snd.ifq_maxlen == 0) {
                           if_printf(ifp, "XXX: driver didn't set ifq_maxlen\n");
                           ifp->if_snd.ifq_maxlen = ifqmaxlen;
                   }
                   if (!mtx_initialized(&ifp->if_snd.ifq_mtx)) {
                           if_printf(ifp,
                               "XXX: driver didn't initialize queue mtx\n");
                           mtx_init(&ifp->if_snd.ifq_mtx, "unknown",
                               MTX_NETWORK_LOCK, MTX_DEF);
                   }
           }
           IFNET_RUNLOCK();
           splx(s);
           if_slowtimo(0);
   }
   
   /*
    * Allocate a struct ifnet and in index for an interface.
    */
   struct ifnet*
   if_alloc(u_char type)
   {
           struct ifnet *ifp;
   
           ifp = malloc(sizeof(struct ifnet), M_IFNET, M_WAITOK|M_ZERO);
   
           /*
            * Try to find an empty slot below if_index.  If we fail, take
            * the next slot.
            *
            * XXX: should be locked!
            */
           for (ifp->if_index = 1; ifp->if_index <= if_index; ifp->if_index++) {
                   if (ifnet_byindex(ifp->if_index) == NULL)
                           break;
           }
           /* Catch if_index overflow. */
           if (ifp->if_index < 1) {
                   free(ifp, M_IFNET);
                   return (NULL);
           }
           if (ifp->if_index > if_index)
                   if_index = ifp->if_index;
           if (if_index >= if_indexlim)
                   if_grow();
           ifnet_byindex(ifp->if_index) = ifp;
   
           ifp->if_type = 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);
                           return (NULL);
                   }
           }
           IF_ADDR_LOCK_INIT(ifp);
   
           return (ifp);
   }
   
   void
   if_free(struct ifnet *ifp)
   {
   
           /* Do not add code to this function!  Add it to if_free_type(). */
           if_free_type(ifp, ifp->if_type);
   }
   
   void
   if_free_type(struct ifnet *ifp, u_char type)
   {
   
           if (ifp != ifnet_byindex(ifp->if_index)) {
                   if_printf(ifp, "%s: value was not if_alloced, skipping\n",
                       __func__);
                   return;
           }
   
           IF_ADDR_LOCK_DESTROY(ifp);
   
           ifnet_byindex(ifp->if_index) = NULL;
   
           /* XXX: should be locked with if_findindex() */
           while (if_index > 0 && ifnet_byindex(if_index) == NULL)
                   if_index--;
   
           if (if_com_free[type] != NULL)
                   if_com_free[type](ifp->if_l2com, type);
   
           free(ifp, M_IFNET);
   };
   
   /*
    * Attach an interface to the
    * list of "active" interfaces.
    */
   void
   if_attach(struct ifnet *ifp)
   {
           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);
   
           TASK_INIT(&ifp->if_starttask, 0, if_start_deferred, ifp);
           TASK_INIT(&ifp->if_linktask, 0, do_link_state_change, ifp);
           IF_AFDATA_LOCK_INIT(ifp);
           ifp->if_afdata_initialized = 0;
           IFNET_WLOCK();
           TAILQ_INSERT_TAIL(&ifnet, ifp, if_link);
           IFNET_WUNLOCK();
           /*
            * XXX -
            * The old code would work if the interface passed a pre-existing
            * chain of ifaddrs to this code.  We don't trust our callers to
            * properly initialize the tailq, however, so we no longer allow
            * this unlikely case.
            */
           TAILQ_INIT(&ifp->if_addrhead);
           TAILQ_INIT(&ifp->if_prefixhead);
           TAILQ_INIT(&ifp->if_multiaddrs);
           knlist_init(&ifp->if_klist, NULL, NULL, NULL, NULL);
           getmicrotime(&ifp->if_lastchange);
           ifp->if_data.ifi_epoch = time_uptime;
           ifp->if_data.ifi_datalen = sizeof(struct if_data);
   
   #ifdef MAC
           mac_init_ifnet(ifp);
           mac_create_ifnet(ifp);
   #endif
   
           ifdev_byindex(ifp->if_index) = make_dev(&net_cdevsw,
               unit2minor(ifp->if_index),
               UID_ROOT, GID_WHEEL, 0600, "%s/%s",
               net_cdevsw.d_name, ifp->if_xname);
           make_dev_alias(ifdev_byindex(ifp->if_index), "%s%d",
               net_cdevsw.d_name, ifp->if_index);
   
           mtx_init(&ifp->if_snd.ifq_mtx, ifp->if_xname, "if send queue", MTX_DEF);
   
           /*
            * 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_LOCK_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;
           ifaddr_byindex(ifp->if_index) = 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;
           ifa->ifa_refcnt = 1;
           TAILQ_INSERT_HEAD(&ifp->if_addrhead, ifa, ifa_link);
           ifp->if_broadcastaddr = NULL; /* reliably crash if used uninitialized */
           ifp->if_snd.altq_type = 0;
           ifp->if_snd.altq_disc = NULL;
           ifp->if_snd.altq_flags &= ALTQF_CANTCHANGE;
           ifp->if_snd.altq_tbr  = NULL;
           ifp->if_snd.altq_ifp  = ifp;
   
           if (domain_init_status >= 2)
                   if_attachdomain1(ifp);
   
           EVENTHANDLER_INVOKE(ifnet_arrival_event, ifp);
   
           /* Announce the interface. */
           rt_ifannouncemsg(ifp, IFAN_ARRIVAL);
   }
   
   static void
   if_attachdomain(void *dummy)
   {
           struct ifnet *ifp;
           int s;
   
           s = splnet();
           TAILQ_FOREACH(ifp, &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 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 && 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 && 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);
                   IFAFREE(ifa);
           }
   }
   
   /*
    * Detach an interface, removing it from the
    * list of "active" interfaces and freeing the struct ifnet.
    *
    * 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)
   {
           struct ifaddr *ifa;
           struct radix_node_head  *rnh;
           int s;
           int i;
           struct domain *dp;
           struct ifnet *iter;
           int found;
   
           /*
            * Remove/wait for pending events.
            */
           taskqueue_drain(taskqueue_swi, &ifp->if_linktask);
   
   #ifdef DEV_CARP
           /* Maybe hook to the generalized departure handler above?!? */
           if (ifp->if_carp)
                   carp_ifdetach(ifp);
   #endif
   
           /*
            * Remove routes and flush queues.
            */
           s = splnet();
           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
           /*
            * Remove address from ifindex_table[] and maybe decrement if_index.
            * Clean up all addresses.
            */
           ifaddr_byindex(ifp->if_index) = NULL;
           destroy_dev(ifdev_byindex(ifp->if_index));
           ifdev_byindex(ifp->if_index) = 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);
                   IFAFREE(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++) {
                   if ((rnh = rt_tables[i]) == 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_AFDATA_LOCK(ifp);
           for (dp = domains; 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]);
           }
           IF_AFDATA_UNLOCK(ifp);
   
   #ifdef MAC
           mac_destroy_ifnet(ifp);
   #endif /* MAC */
           KNOTE_UNLOCKED(&ifp->if_klist, NOTE_EXIT);
           knlist_clear(&ifp->if_klist, 0);
           knlist_destroy(&ifp->if_klist);
           IFNET_WLOCK();
           found = 0;
           TAILQ_FOREACH(iter, &ifnet, if_link)
                   if (iter == ifp) {
                           found = 1;
                           break;
                   }
           if (found)
                   TAILQ_REMOVE(&ifnet, ifp, if_link);
           IFNET_WUNLOCK();
           mtx_destroy(&ifp->if_snd.ifq_mtx);
           IF_AFDATA_DESTROY(ifp);
           splx(s);
   }
   
   /*
    * 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(RTM_DELETE, rt_key(rt), rt->rt_gateway,
                                   rt_mask(rt), rt->rt_flags,
                                   (struct rtentry **) NULL);
                   if (err) {
                           log(LOG_WARNING, "if_rtdel: error %d\n", err);
                   }
           }
   
           return (0);
   }
   
   #define sa_equal(a1, a2)        (bcmp((a1), (a2), ((a1))->sa_len) == 0)
   
   /*
    * Locate an interface based on a complete address.
    */
   /*ARGSUSED*/
   struct ifaddr *
   ifa_ifwithaddr(struct sockaddr *addr)
   {
           struct ifnet *ifp;
           struct ifaddr *ifa;
   
           IFNET_RLOCK();
           TAILQ_FOREACH(ifp, &ifnet, if_link)
                   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))
                                   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))
                                   goto done;
                   }
           ifa = NULL;
   done:
           IFNET_RUNLOCK();
           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();
           TAILQ_FOREACH(ifp, &ifnet, if_link) {
                   if ((ifp->if_flags & IFF_POINTOPOINT) == 0)
                           continue;
                   TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                           if (ifa->ifa_addr->sa_family != addr->sa_family)
                                   continue;
                           if (ifa->ifa_dstaddr &&
                               sa_equal(addr, ifa->ifa_dstaddr))
                                   goto done;
                   }
           }
           ifa = NULL;
   done:
           IFNET_RUNLOCK();
           return (ifa);
   }
   
   /*
    * Find an interface on a specific network.  If many, choice
    * is most specific found.
    */
   struct ifaddr *
   ifa_ifwithnet(struct sockaddr *addr)
   {
           struct ifnet *ifp;
           struct ifaddr *ifa;
           struct ifaddr *ifa_maybe = (struct ifaddr *) 0;
           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 <= if_index)
                   return (ifaddr_byindex(sdl->sdl_index));
           }
   
           /*
            * Scan though each interface, looking for ones that have
            * addresses in this address family.
            */
           IFNET_RLOCK();
           TAILQ_FOREACH(ifp, &ifnet, if_link) {
                   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) {
                                   /*
                                    * 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 != 0 &&
                                       sa_equal(addr, ifa->ifa_dstaddr))
                                           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))
                                                   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 == 0 ||
                                       rn_refines((caddr_t)ifa->ifa_netmask,
                                       (caddr_t)ifa_maybe->ifa_netmask))
                                           ifa_maybe = ifa;
                           }
                   }
           }
           ifa = ifa_maybe;
   done:
           IFNET_RUNLOCK();
           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 = 0;
           u_int af = addr->sa_family;
   
           if (af >= AF_MAX)
                   return (0);
           TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                   if (ifa->ifa_addr->sa_family != af)
                           continue;
                   if (ifa_maybe == 0)
                           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:
           return (ifa);
   }
   
   #include <net/route.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) {
                   IFAREF(ifa);            /* XXX */
                   oifa = rt->rt_ifa;
                   rt->rt_ifa = ifa;
                   IFAFREE(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);
          if_qflush(&ifp->if_snd);
  #ifdef DEV_CARP
          if (ifp->if_carp)
                  carp_carpdev_state(ifp->if_carp);
  #endif
          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);
  #ifdef DEV_CARP
          if (ifp->if_carp)
                  carp_carpdev_state(ifp->if_carp);
  #endif
          rt_ifmsg(ifp);
  #ifdef INET6
          in6_if_up(ifp);
  #endif
  }
  
  void    (*vlan_link_state_p)(struct ifnet *, int);      /* XXX: private from if_vlan */
  
  /*
   * 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;
          int link;
  
          /* Notify that the link state has changed. */
          rt_ifmsg(ifp);
          if (link_state == LINK_STATE_UP)
                  link = NOTE_LINKUP;
          else if (link_state == LINK_STATE_DOWN)
                  link = NOTE_LINKDOWN;
          else
                  link = NOTE_LINKINV;
          KNOTE_UNLOCKED(&ifp->if_klist, link);
          if (ifp->if_nvlans != 0)
                  (*vlan_link_state_p)(ifp, link);
  
          if ((ifp->if_type == IFT_ETHER || ifp->if_type == IFT_L2VLAN) &&
              IFP2AC(ifp)->ac_netgraph != NULL)
                  (*ng_ether_link_state_p)(ifp, link_state);
  #ifdef DEV_CARP
          if (ifp->if_carp)
                  carp_carpdev_state(ifp->if_carp);
  #endif
          if (ifp->if_bridge) {
                  KASSERT(bstp_linkstate_p != NULL,("if_bridge bstp not loaded!"));
                  (*bstp_linkstate_p)(ifp, link_state);
          }
  
          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" );
  }
  
  /*
   * 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.
   */
  static void
  if_qflush(struct ifaltq *ifq)
  {
          struct mbuf *m, *n;
  
          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);
  }
  
  /*
   * Handle interface watchdog timer routines.  Called
   * from softclock, we decrement timers (if set) and
   * call the appropriate interface routine on expiration.
   *
   * XXXRW: Note that because timeouts run with Giant, if_watchdog() is called
   * holding Giant.  If we switch to an MPSAFE callout, we likely need to grab
   * Giant before entering if_watchdog() on an IFF_NEEDSGIANT interface.
   */
  static void
  if_slowtimo(void *arg)
  {
          struct ifnet *ifp;
          int s = splimp();
  
          IFNET_RLOCK();
          TAILQ_FOREACH(ifp, &ifnet, if_link) {
                  if (ifp->if_timer == 0 || --ifp->if_timer)
                          continue;
                  if (ifp->if_watchdog)
                          (*ifp->if_watchdog)(ifp);
          }
          IFNET_RUNLOCK();
          splx(s);
          timeout(if_slowtimo, (void *)0, hz / IFNET_SLOWHZ);
  }
  
  /*
   * Map interface name to
   * interface structure pointer.
   */
  struct ifnet *
  ifunit(const char *name)
  {
          struct ifnet *ifp;
  
          IFNET_RLOCK();
          TAILQ_FOREACH(ifp, &ifnet, if_link) {
                  if (strncmp(name, ifp->if_xname, IFNAMSIZ) == 0)
                          break;
          }
          IFNET_RUNLOCK();
          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;
          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_ioctl_ifnet_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 SIOCSIFFLAGS:
                  error = suser(td);
                  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);
                  }
                  ifp->if_flags = (ifp->if_flags & IFF_CANTCHANGE) |
                          (new_flags &~ IFF_CANTCHANGE);
                  if (new_flags & IFF_PPROMISC) {
                          /* Permanently promiscuous mode requested */
                          ifp->if_flags |= IFF_PROMISC;
                  } else if (ifp->if_pcount == 0) {
                          ifp->if_flags &= ~IFF_PROMISC;
                  }
                  if (ifp->if_ioctl != NULL) {
                          IFF_LOCKGIANT(ifp);
                          (void) (*ifp->if_ioctl)(ifp, cmd, data);
                          IFF_UNLOCKGIANT(ifp);
                  }
                  getmicrotime(&ifp->if_lastchange);
                  break;
  
          case SIOCSIFCAP:
                  error = suser(td);
                  if (error)
                          return (error);
                  if (ifp->if_ioctl == NULL)
                          return (EOPNOTSUPP);
                  if (ifr->ifr_reqcap & ~ifp->if_capabilities)
                          return (EINVAL);
                  IFF_LOCKGIANT(ifp);
                  error = (*ifp->if_ioctl)(ifp, cmd, data);
                  IFF_UNLOCKGIANT(ifp);
                  if (error == 0)
                          getmicrotime(&ifp->if_lastchange);
                  break;
  
  #ifdef MAC
          case SIOCSIFMAC:
                  error = mac_ioctl_ifnet_set(td->td_ucred, ifr, ifp);
                  break;
  #endif
  
          case SIOCSIFNAME:
                  error = suser(td);
                  if (error != 0)
                          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);
                  
                  /* 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 = ifaddr_byindex(ifp->if_index);
                  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);
                  break;
  
          case SIOCSIFMETRIC:
                  error = suser(td);
                  if (error)
                          return (error);
                  ifp->if_metric = ifr->ifr_metric;
                  getmicrotime(&ifp->if_lastchange);
                  break;
  
          case SIOCSIFPHYS:
                  error = suser(td);
                  if (error)
                          return (error);
                  if (ifp->if_ioctl == NULL)
                          return (EOPNOTSUPP);
                  IFF_LOCKGIANT(ifp);
                  error = (*ifp->if_ioctl)(ifp, cmd, data);
                  IFF_UNLOCKGIANT(ifp);
                  if (error == 0)
                          getmicrotime(&ifp->if_lastchange);
                  break;
  
          case SIOCSIFMTU:
          {
                  u_long oldmtu = ifp->if_mtu;
  
                  error = suser(td);
                  if (error)
                          return (error);
                  if (ifr->ifr_mtu < IF_MINMTU || ifr->ifr_mtu > IF_MAXMTU)
                          return (EINVAL);
                  if (ifp->if_ioctl == NULL)
                          return (EOPNOTSUPP);
                  IFF_LOCKGIANT(ifp);
                  error = (*ifp->if_ioctl)(ifp, cmd, data);
                  IFF_UNLOCKGIANT(ifp);
                  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:
                  error = suser(td);
                  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;
                          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 = suser(td);
                  if (error)
                          return (error);
                  if (ifp->if_ioctl == NULL)
                          return (EOPNOTSUPP);
                  IFF_LOCKGIANT(ifp);
                  error = (*ifp->if_ioctl)(ifp, cmd, data);
                  IFF_UNLOCKGIANT(ifp);
                  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);
                  IFF_LOCKGIANT(ifp);
                  error = (*ifp->if_ioctl)(ifp, cmd, data);
                  IFF_UNLOCKGIANT(ifp);
                  break;
  
          case SIOCSIFLLADDR:
                  error = suser(td);
                  if (error)
                          return (error);
                  error = if_setlladdr(ifp,
                      ifr->ifr_addr.sa_data, ifr->ifr_addr.sa_len);
                  break;
  
          default:
                  error = ENOIOCTL;
                  break;
          }
          return (error);
  }
  
  /*
   * 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;
  
          switch (cmd) {
          case SIOCGIFCONF:
          case OSIOCGIFCONF:
                  return (ifconf(cmd, data));
          }
          ifr = (struct ifreq *)data;
  
          switch (cmd) {
          case SIOCIFCREATE:
          case SIOCIFDESTROY:
                  if ((error = suser(td)) != 0)
                          return (error);
                  return ((cmd == SIOCIFCREATE) ?
                          if_clone_create(ifr->ifr_name, sizeof(ifr->ifr_name)) :
                          if_clone_destroy(ifr->ifr_name));
  
          case SIOCIFGCLONERS:
                  return (if_clone_list((struct if_clonereq *)data));
          }
  
          ifp = ifunit(ifr->ifr_name);
          if (ifp == 0)
                  return (ENXIO);
  
          error = ifhwioctl(cmd, ifp, data, td);
          if (error != ENOIOCTL)
                  return (error);
  
          oif_flags = ifp->if_flags;
          if (so->so_proto == 0)
                  return (EOPNOTSUPP);
  #ifndef COMPAT_43
          error = ((*so->so_proto->pr_usrreqs->pru_control)(so, cmd,
                                                                   data,
                                                                   ifp, td));
  #else
          {
                  int 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));
                  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
                  DELAY(100);/* XXX: temporary workaround for fxp issue*/
                  if (ifp->if_flags & IFF_UP) {
                          int s = splimp();
                          in6_if_up(ifp);
                          splx(s);
                  }
  #endif
          }
          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,
   * 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;
  
          KASSERT((flag & (IFF_DRV_OACTIVE|IFF_DRV_RUNNING)) == 0,
              ("if_setflag: setting driver-ownded flag %d", flag));
  
          /* Sanity checks to catch programming errors */
          if (onswitch) {
                  if (*refcount < 0) {
                          if_printf(ifp,
                              "refusing to increment negative refcount %d "
                              "for interface flag %d\n", *refcount, flag);
                          return (EINVAL);
                  }
          } else {
                  if (*refcount <= 0) {
                          if_printf(ifp,
                              "refusing to decrement non-positive refcount %d"
                              "for interface flag %d\n", *refcount, flag);
                          return (EINVAL);
                  }
          }
  
          /* 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;
          IFF_LOCKGIANT(ifp);
          error = (*ifp->if_ioctl)(ifp, SIOCSIFFLAGS, (caddr_t)&ifr);
          IFF_UNLOCKGIANT(ifp);
          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();          /* could sleep XXX */
          TAILQ_FOREACH(ifp, &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;
                  TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                          struct sockaddr *sa = ifa->ifa_addr;
  
                          if (jailed(curthread->td_ucred) &&
                              prison_if(curthread->td_ucred, sa))
                                  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_overflowed(sb))
                                  valid_len = sbuf_len(sb);
                  }
                  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_overflowed(sb))
                                  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));
  }
  
  static 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_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;
  
          MALLOC(ifma, struct ifmultiaddr *, sizeof *ifma, M_IFMADDR, mflags |
              M_ZERO);
          if (ifma == NULL)
                  return (NULL);
  
          MALLOC(dupsa, struct sockaddr *, 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);
          }
  
          MALLOC(dupsa, struct sockaddr *, 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 == 1, ("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) {
                                  if_freemulti(ifma);
                                  error = ENOMEM;
                                  goto free_llsa_out;
                          }
                          TAILQ_INSERT_HEAD(&ifp->if_multiaddrs, ll_ifma,
                              ifma_link);
                  } else
                          ll_ifma->ifma_refcount++;
          }
  
          /*
           * 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.
           *
           * XXXRW: How come we don't announce ll_ifma?
           */
          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) {
                  IFF_LOCKGIANT(ifp);
                  (void) (*ifp->if_ioctl)(ifp, SIOCADDMULTI, 0);
                  IFF_UNLOCKGIANT(ifp);
          }
  
          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);
  }
  
  /*
   * Remove a reference to a multicast address on this interface.  Yell
   * if the request does not match an existing membership.
   */
  int
  if_delmulti(struct ifnet *ifp, struct sockaddr *sa)
  {
          struct ifmultiaddr *ifma, *ll_ifma;
  
          IF_ADDR_LOCK(ifp);
          ifma = if_findmulti(ifp, sa);
          if (ifma == NULL) {
                  IF_ADDR_UNLOCK(ifp);
                  return ENOENT;
          }
  
          if (ifma->ifma_refcount > 1) {
                  ifma->ifma_refcount--;
                  IF_ADDR_UNLOCK(ifp);
                  return 0;
          }
  
          sa = ifma->ifma_lladdr;
          if (sa != NULL)
                  ll_ifma = if_findmulti(ifp, sa);
          else
                  ll_ifma = NULL;
  
          /*
           * XXXRW: How come we don't announce ll_ifma?
           */
          rt_newmaddrmsg(RTM_DELMADDR, ifma);
  
          TAILQ_REMOVE(&ifp->if_multiaddrs, ifma, ifma_link);
          if_freemulti(ifma);
  
          if (ll_ifma != NULL) {
                  if (ll_ifma->ifma_refcount == 1) {
                          TAILQ_REMOVE(&ifp->if_multiaddrs, ll_ifma, ifma_link);
                          if_freemulti(ll_ifma);
                  } else
                          ll_ifma->ifma_refcount--;
          }
          IF_ADDR_UNLOCK(ifp);
  
          /*
           * Make sure the interface driver is notified
           * in the case of a link layer mcast group being left.
           */
          if (ifp->if_ioctl) {
                  IFF_LOCKGIANT(ifp);
                  (void) (*ifp->if_ioctl)(ifp, SIOCDELMULTI, 0);
                  IFF_UNLOCKGIANT(ifp);
          }
  
          return 0;
  }
  
  /*
   * 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;
  
          ifa = ifaddr_byindex(ifp->if_index);
          if (ifa == NULL)
                  return (EINVAL);
          sdl = (struct sockaddr_dl *)ifa->ifa_addr;
          if (sdl == NULL)
                  return (EINVAL);
          if (len != sdl->sdl_alen)       /* don't allow length to change */
                  return (EINVAL);
          switch (ifp->if_type) {
          case IFT_ETHER:                 /* these types use struct arpcom */
          case IFT_FDDI:
          case IFT_XETHER:
          case IFT_ISO88025:
          case IFT_L2VLAN:
          case IFT_BRIDGE:
                  bcopy(lladdr, IFP2ENADDR(ifp), len);
                  /*
                   * XXX We also need to store the lladdr in LLADDR(sdl),
                   * which is done below. This is a pain because we must
                   * remember to keep the info in sync.
                   */
                  /* FALLTHROUGH */
          case IFT_ARCNET:
                  bcopy(lladdr, LLADDR(sdl), len);
                  break;
          default:
                  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) {
                          IFF_LOCKGIANT(ifp);
                          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);
                          IFF_UNLOCKGIANT(ifp);
                  }
  #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 != NULL &&
                              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);
  }
  
  /*
   * When an interface is marked IFF_NEEDSGIANT, its if_start() routine cannot
   * be called without Giant.  However, we often can't acquire the Giant lock
   * at those points; instead, we run it via a task queue that holds Giant via
   * if_start_deferred.
   *
   * XXXRW: We need to make sure that the ifnet isn't fully detached until any
   * outstanding if_start_deferred() tasks that will run after the free.  This
   * probably means waiting in if_detach().
   */
  void
  if_start(struct ifnet *ifp)
  {
  
          NET_ASSERT_GIANT();
  
          if ((ifp->if_flags & IFF_NEEDSGIANT) != 0 && debug_mpsafenet != 0) {
                  if (mtx_owned(&Giant))
                          (*(ifp)->if_start)(ifp);
                  else
                          taskqueue_enqueue(taskqueue_swi_giant,
                              &ifp->if_starttask);
          } else
                  (*(ifp)->if_start)(ifp);
  }
  
  static void
  if_start_deferred(void *context, int pending)
  {
          struct ifnet *ifp;
  
          /*
           * This code must be entered with Giant, and should never run if
           * we're not running with debug.mpsafenet.
           */
          KASSERT(debug_mpsafenet != 0, ("if_start_deferred: debug.mpsafenet"));
          GIANT_REQUIRED;
  
          ifp = context;
          (ifp->if_start)(ifp);
  }
  
  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)
                  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;
  }

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