/*      $NetBSD: if.c,v 1.538 2026/05/14 08:05:48 roy Exp $     */

/*-
 * Copyright (c) 1999, 2000, 2001, 2008 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by William Studenmund and Jason R. Thorpe.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project 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 PROJECT 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 PROJECT 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.
 */

/*
 * 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.
 * 3. 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
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: if.c,v 1.538 2026/05/14 08:05:48 roy Exp $");

#if defined(_KERNEL_OPT)
#include "opt_inet.h"
#include "opt_ipsec.h"
#include "opt_atalk.h"
#include "opt_wlan.h"
#include "opt_net_mpsafe.h"
#include "opt_mrouting.h"
#endif

#include <sys/param.h>
#include <sys/mbuf.h>
#include <sys/systm.h>
#include <sys/callout.h>
#include <sys/proc.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/kernel.h>
#include <sys/ioctl.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/kauth.h>
#include <sys/kmem.h>
#include <sys/xcall.h>
#include <sys/cpu.h>
#include <sys/intr.h>
#include <sys/module_hook.h>
#include <sys/compat_stub.h>
#include <sys/msan.h>
#include <sys/hook.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_ether.h>
#include <net/if_media.h>
#include <net80211/ieee80211.h>
#include <net80211/ieee80211_ioctl.h>
#include <net/if_types.h>
#include <net/route.h>
#include <sys/module.h>
#ifdef NETATALK
#include <netatalk/at_extern.h>
#include <netatalk/at.h>
#endif
#include <net/pfil.h>
#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/ip_encap.h>
#include <net/bpf.h>

#ifdef INET6
#include <netinet6/in6_var.h>
#include <netinet6/nd6.h>
#endif

#include "ether.h"

#include "bridge.h"
#if NBRIDGE > 0
#include <net/if_bridgevar.h>
#endif

#include "carp.h"
#if NCARP > 0
#include <netinet/ip_carp.h>
#endif

#include <compat/sys/sockio.h>

MALLOC_DEFINE(M_IFADDR, "ifaddr", "interface address");
MALLOC_DEFINE(M_IFMADDR, "ether_multi", "link-level multicast address");

/*
 * XXX reusing (ifp)->if_snd->ifq_lock rather than having another spin mutex
 * for each ifnet.  It doesn't matter because:
 * - if IFEF_MPSAFE is enabled, if_snd isn't used and lock contentions on
 *   ifq_lock don't happen
 * - if IFEF_MPSAFE is disabled, there is no lock contention on ifq_lock
 *   because if_snd, if_link_state_change and if_link_state_change_process
 *   are all called with KERNEL_LOCK
 */
#define IF_LINK_STATE_CHANGE_LOCK(ifp)          \
        mutex_enter((ifp)->if_snd.ifq_lock)
#define IF_LINK_STATE_CHANGE_UNLOCK(ifp)        \
        mutex_exit((ifp)->if_snd.ifq_lock)

/*
 * Global list of interfaces.
 */
/* DEPRECATED. Remove it once kvm(3) users disappeared */
struct ifnet_head               ifnet_list;

struct pslist_head              ifnet_pslist;
static ifnet_t **               ifindex2ifnet = NULL;
static u_int                    if_index = 1;
static size_t                   if_indexlim = 0;
static uint64_t                 index_gen;
/* Mutex to protect the above objects. */
kmutex_t                        ifnet_mtx __cacheline_aligned;
static struct psref_class       *ifnet_psref_class __read_mostly;
static pserialize_t             ifnet_psz;
static struct workqueue         *ifnet_link_state_wq __read_mostly;

static struct workqueue         *if_slowtimo_wq __read_mostly;

static kmutex_t                 if_clone_mtx;

struct ifnet *lo0ifp;
int     ifqmaxlen = IFQ_MAXLEN;

struct psref_class              *ifa_psref_class __read_mostly;

static int      if_delroute_matcher(struct rtentry *, void *);

static bool if_is_unit(const char *);
static struct if_clone *if_clone_lookup(const char *, int *);

static LIST_HEAD(, if_clone) if_cloners = LIST_HEAD_INITIALIZER(if_cloners);
static int if_cloners_count;

/* Packet filtering hook for interfaces. */
pfil_head_t *                   if_pfil __read_mostly;

static kauth_listener_t if_listener;

static int doifioctl(struct socket *, u_long, void *, struct lwp *);
static void sysctl_sndq_setup(struct sysctllog **, const char *,
    struct ifaltq *);
static void if_slowtimo_intr(void *);
static void if_slowtimo_work(struct work *, void *);
static int sysctl_if_watchdog(SYSCTLFN_PROTO);
static void sysctl_watchdog_setup(struct ifnet *);
static void if_attachdomain1(struct ifnet *);
static int ifconf(u_long, void *);
static int if_transmit(struct ifnet *, struct mbuf *);
static int if_clone_create(const char *);
static int if_clone_destroy(const char *);
static void if_link_state_change_work(struct work *, void *);
static void if_up_locked(struct ifnet *);
static void _if_down(struct ifnet *);
static void if_down_deactivated(struct ifnet *);

struct if_percpuq {
        struct ifnet    *ipq_ifp;
        void            *ipq_si;
        struct percpu   *ipq_ifqs;      /* struct ifqueue */
};

static struct mbuf *if_percpuq_dequeue(struct if_percpuq *);

static void if_percpuq_drops(void *, void *, struct cpu_info *);
static int sysctl_percpuq_drops_handler(SYSCTLFN_PROTO);
static void sysctl_percpuq_setup(struct sysctllog **, const char *,
    struct if_percpuq *);

struct if_deferred_start {
        struct ifnet    *ids_ifp;
        void            (*ids_if_start)(struct ifnet *);
        void            *ids_si;
};

static void if_deferred_start_softint(void *);
static void if_deferred_start_common(struct ifnet *);
static void if_deferred_start_destroy(struct ifnet *);

struct if_slowtimo_data {
        kmutex_t                isd_lock;
        struct callout          isd_ch;
        struct work             isd_work;
        struct ifnet            *isd_ifp;
        bool                    isd_queued;
        bool                    isd_dying;
        bool                    isd_trigger;
};

/*
 * Hook for if_vlan - needed by if_agr
 */
struct if_vlan_vlan_input_hook_t if_vlan_vlan_input_hook;

static void if_sysctl_setup(struct sysctllog **);

static int
if_listener_cb(kauth_cred_t cred, kauth_action_t action, void *cookie,
    void *arg0, void *arg1, void *arg2, void *arg3)
{
        int result;
        enum kauth_network_req req;

        result = KAUTH_RESULT_DEFER;
        req = (enum kauth_network_req)(uintptr_t)arg1;

        if (action != KAUTH_NETWORK_INTERFACE)
                return result;

        if ((req == KAUTH_REQ_NETWORK_INTERFACE_GET) ||
            (req == KAUTH_REQ_NETWORK_INTERFACE_SET))
                result = KAUTH_RESULT_ALLOW;

        return result;
}

/*
 * Network interface utility routines.
 *
 * Routines with ifa_ifwith* names take sockaddr *'s as
 * parameters.
 */
void
ifinit(void)
{

#if (defined(INET) || defined(INET6))
        encapinit();
#endif

        if_listener = kauth_listen_scope(KAUTH_SCOPE_NETWORK,
            if_listener_cb, NULL);

        /* interfaces are available, inform socket code */
        ifioctl = doifioctl;
}

/*
 * XXX Initialization before configure().
 * XXX hack to get pfil_add_hook working in autoconf.
 */
void
ifinit1(void)
{
        int error __diagused;

#ifdef NET_MPSAFE
        printf("NET_MPSAFE enabled\n");
#endif

        mutex_init(&if_clone_mtx, MUTEX_DEFAULT, IPL_NONE);

        TAILQ_INIT(&ifnet_list);
        mutex_init(&ifnet_mtx, MUTEX_DEFAULT, IPL_NONE);
        ifnet_psz = pserialize_create();
        ifnet_psref_class = psref_class_create("ifnet", IPL_SOFTNET);
        ifa_psref_class = psref_class_create("ifa", IPL_SOFTNET);
        error = workqueue_create(&ifnet_link_state_wq, "iflnkst",
            if_link_state_change_work, NULL, PRI_SOFTNET, IPL_NET,
            WQ_MPSAFE);
        KASSERT(error == 0);
        PSLIST_INIT(&ifnet_pslist);

        error = workqueue_create(&if_slowtimo_wq, "ifwdog",
            if_slowtimo_work, NULL, PRI_SOFTNET, IPL_SOFTCLOCK, WQ_MPSAFE);
        KASSERTMSG(error == 0, "error=%d", error);

        if_indexlim = 8;

        if_pfil = pfil_head_create(PFIL_TYPE_IFNET, NULL);
        KASSERT(if_pfil != NULL);

#if NETHER > 0 || defined(NETATALK) || defined(WLAN)
        etherinit();
#endif
}

/* XXX must be after domaininit() */
void
ifinit_post(void)
{

        if_sysctl_setup(NULL);
}

ifnet_t *
if_alloc(u_char type)
{

        return kmem_zalloc(sizeof(ifnet_t), KM_SLEEP);
}

void
if_free(ifnet_t *ifp)
{

        kmem_free(ifp, sizeof(ifnet_t));
}

void
if_initname(struct ifnet *ifp, const char *name, int unit)
{

        (void)snprintf(ifp->if_xname, sizeof(ifp->if_xname),
            "%s%d", name, unit);
}

/*
 * Null routines used while an interface is going away.  These routines
 * just return an error.
 */

int
if_nulloutput(struct ifnet *ifp, struct mbuf *m,
    const struct sockaddr *so, const struct rtentry *rt)
{

        return ENXIO;
}

void
if_nullinput(struct ifnet *ifp, struct mbuf *m)
{

        /* Nothing. */
}

void
if_nullstart(struct ifnet *ifp)
{

        /* Nothing. */
}

int
if_nulltransmit(struct ifnet *ifp, struct mbuf *m)
{

        m_freem(m);
        return ENXIO;
}

int
if_nullioctl(struct ifnet *ifp, u_long cmd, void *data)
{

        return ENXIO;
}

int
if_nullinit(struct ifnet *ifp)
{

        return ENXIO;
}

void
if_nullstop(struct ifnet *ifp, int disable)
{

        /* Nothing. */
}

void
if_nullslowtimo(struct ifnet *ifp)
{

        /* Nothing. */
}

void
if_nulldrain(struct ifnet *ifp)
{

        /* Nothing. */
}

void
if_set_sadl(struct ifnet *ifp, const void *lla, u_char addrlen, bool factory)
{
        struct ifaddr *ifa;
        struct sockaddr_dl *sdl;

        ifp->if_addrlen = addrlen;
        if_alloc_sadl(ifp);
        ifa = ifp->if_dl;
        sdl = satosdl(ifa->ifa_addr);

        (void)sockaddr_dl_setaddr(sdl, sdl->sdl_len, lla, ifp->if_addrlen);
        if (factory) {
                KASSERT(ifp->if_hwdl == NULL);
                ifp->if_hwdl = ifp->if_dl;
                ifaref(ifp->if_hwdl);
        }
        /* TBD routing socket */
}

struct ifaddr *
if_dl_create(const struct ifnet *ifp, const struct sockaddr_dl **sdlp)
{
        unsigned socksize, ifasize;
        int addrlen, namelen;
        struct sockaddr_dl *mask, *sdl;
        struct ifaddr *ifa;

        namelen = strlen(ifp->if_xname);
        addrlen = ifp->if_addrlen;
        socksize = roundup(sockaddr_dl_measure(namelen, addrlen),
            sizeof(long));
        ifasize = sizeof(*ifa) + 2 * socksize;
        ifa = malloc(ifasize, M_IFADDR, M_WAITOK | M_ZERO);

        sdl = (struct sockaddr_dl *)(ifa + 1);
        mask = (struct sockaddr_dl *)(socksize + (char *)sdl);

        sockaddr_dl_init(sdl, socksize, ifp->if_index, ifp->if_type,
            ifp->if_xname, namelen, NULL, addrlen);
        mask->sdl_family = AF_LINK;
        mask->sdl_len = sockaddr_dl_measure(namelen, 0);
        memset(&mask->sdl_data[0], 0xff, namelen);
        ifa->ifa_rtrequest = link_rtrequest;
        ifa->ifa_addr = (struct sockaddr *)sdl;
        ifa->ifa_netmask = (struct sockaddr *)mask;
        ifa_psref_init(ifa);

        *sdlp = sdl;

        return ifa;
}

static void
if_sadl_setrefs(struct ifnet *ifp, struct ifaddr *ifa)
{
        const struct sockaddr_dl *sdl;

        ifp->if_dl = ifa;
        ifaref(ifa);
        sdl = satosdl(ifa->ifa_addr);
        ifp->if_sadl = sdl;
}

/*
 * Allocate the link level name for the specified interface.  This
 * is an attachment helper.  It must be called after ifp->if_addrlen
 * is initialized, which may not be the case when if_attach() is
 * called.
 */
void
if_alloc_sadl(struct ifnet *ifp)
{
        struct ifaddr *ifa;
        const struct sockaddr_dl *sdl;

        /*
         * If the interface already has a link name, release it
         * now.  This is useful for interfaces that can change
         * link types, and thus switch link names often.
         */
        if (ifp->if_sadl != NULL)
                if_free_sadl(ifp, 0);

        ifa = if_dl_create(ifp, &sdl);

        ifa_insert(ifp, ifa);
        if_sadl_setrefs(ifp, ifa);
}

static void
if_deactivate_sadl(struct ifnet *ifp)
{
        struct ifaddr *ifa;

        KASSERT(ifp->if_dl != NULL);

        ifa = ifp->if_dl;

        ifp->if_sadl = NULL;

        ifp->if_dl = NULL;
        ifafree(ifa);
}

static void
if_replace_sadl(struct ifnet *ifp, struct ifaddr *ifa)
{
        struct ifaddr *old;

        KASSERT(ifp->if_dl != NULL);

        old = ifp->if_dl;

        ifaref(ifa);
        /* XXX Update if_dl and if_sadl atomically */
        ifp->if_dl = ifa;
        ifp->if_sadl = satosdl(ifa->ifa_addr);

        ifafree(old);
}

void
if_activate_sadl(struct ifnet *ifp, struct ifaddr *ifa0,
    const struct sockaddr_dl *sdl)
{
        struct ifaddr *ifa;
        const int bound = curlwp_bind();

        KASSERT(ifa_held(ifa0));

        const int s = splsoftnet();

        if_replace_sadl(ifp, ifa0);

        int ss = pserialize_read_enter();
        IFADDR_READER_FOREACH(ifa, ifp) {
                struct psref psref;
                ifa_acquire(ifa, &psref);
                pserialize_read_exit(ss);

                rtinit(ifa, RTM_LLINFO_UPD, 0);

                ss = pserialize_read_enter();
                ifa_release(ifa, &psref);
        }
        pserialize_read_exit(ss);

        splx(s);
        curlwp_bindx(bound);
}

/*
 * Free the link level name for the specified interface.  This is
 * a detach helper.  This is called from if_detach().
 */
void
if_free_sadl(struct ifnet *ifp, int factory)
{
        struct ifaddr *ifa;

        if (factory && ifp->if_hwdl != NULL) {
                ifa = ifp->if_hwdl;
                ifp->if_hwdl = NULL;
                ifafree(ifa);
        }

        ifa = ifp->if_dl;
        if (ifa == NULL) {
                KASSERT(ifp->if_sadl == NULL);
                return;
        }

        KASSERT(ifp->if_sadl != NULL);

        const int s = splsoftnet();
        KASSERT(ifa->ifa_addr->sa_family == AF_LINK);
        ifa_remove(ifp, ifa);
        if_deactivate_sadl(ifp);
        splx(s);
}

static void
if_getindex(ifnet_t *ifp)
{
        bool hitlimit = false;

        ifp->if_index_gen = index_gen++;

        ifp->if_index = if_index;
        if (ifindex2ifnet == NULL) {
                if_index++;
                goto skip;
        }
        while (if_byindex(ifp->if_index)) {
                /*
                 * If we hit USHRT_MAX, we skip back to 0 since
                 * there are a number of places where the value
                 * of if_index or if_index itself is compared
                 * to or stored in an unsigned short.  By
                 * jumping back, we won't botch those assignments
                 * or comparisons.
                 */
                if (++if_index == 0) {
                        if_index = 1;
                } else if (if_index == USHRT_MAX) {
                        /*
                         * However, if we have to jump back to
                         * zero *twice* without finding an empty
                         * slot in ifindex2ifnet[], then there
                         * there are too many (>65535) interfaces.
                         */
                        if (hitlimit)
                                panic("too many interfaces");
                        hitlimit = true;
                        if_index = 1;
                }
                ifp->if_index = if_index;
        }
skip:
        /*
         * ifindex2ifnet is indexed by if_index. Since if_index will
         * grow dynamically, it should grow too.
         */
        if (ifindex2ifnet == NULL || ifp->if_index >= if_indexlim) {
                size_t m, n, oldlim;
                void *q;

                oldlim = if_indexlim;
                while (ifp->if_index >= if_indexlim)
                        if_indexlim <<= 1;

                /* grow ifindex2ifnet */
                m = oldlim * sizeof(struct ifnet *);
                n = if_indexlim * sizeof(struct ifnet *);
                q = malloc(n, M_IFADDR, M_WAITOK | M_ZERO);
                if (ifindex2ifnet != NULL) {
                        memcpy(q, ifindex2ifnet, m);
                        free(ifindex2ifnet, M_IFADDR);
                }
                ifindex2ifnet = (struct ifnet **)q;
        }
        ifindex2ifnet[ifp->if_index] = ifp;
}

/*
 * Initialize an interface and assign an index for it.
 *
 * It must be called prior to a device specific attach routine
 * (e.g., ether_ifattach and ieee80211_ifattach) or if_alloc_sadl,
 * and be followed by if_register:
 *
 *     if_initialize(ifp);
 *     ether_ifattach(ifp, enaddr);
 *     if_register(ifp);
 */
void
if_initialize(ifnet_t *ifp)
{
        char xnamebuf[HOOKNAMSIZ];

        KASSERT(if_indexlim > 0);
        TAILQ_INIT(&ifp->if_addrlist);

        /*
         * Link level name is allocated later by a separate call to
         * if_alloc_sadl().
         */

        if (ifp->if_snd.ifq_maxlen == 0)
                ifp->if_snd.ifq_maxlen = ifqmaxlen;

        ifp->if_broadcastaddr = 0; /* reliably crash if used uninitialized */

        ifp->if_link_state = LINK_STATE_UNKNOWN;
        ifp->if_link_queue = 0;

        ifp->if_capenable = 0;
        ifp->if_csum_flags_tx = 0;
        ifp->if_csum_flags_rx = 0;

#ifdef ALTQ
        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;
#endif

        IFQ_LOCK_INIT(&ifp->if_snd);

        ifp->if_pfil = pfil_head_create(PFIL_TYPE_IFNET, ifp);
        pfil_run_ifhooks(if_pfil, PFIL_IFNET_ATTACH, ifp);

        IF_AFDATA_LOCK_INIT(ifp);

        PSLIST_ENTRY_INIT(ifp, if_pslist_entry);
        PSLIST_INIT(&ifp->if_addr_pslist);
        psref_target_init(&ifp->if_psref, ifnet_psref_class);
        ifp->if_ioctl_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_NONE);
        LIST_INIT(&ifp->if_multiaddrs);
        if_stats_init(ifp);

        snprintf(xnamebuf, sizeof(xnamebuf), "%s-lshk", ifp->if_xname);
        ifp->if_linkstate_hooks = simplehook_create(IPL_NET, xnamebuf);

        IFNET_GLOBAL_LOCK();
        if_getindex(ifp);
        IFNET_GLOBAL_UNLOCK();
}

/*
 * Register an interface to the list of "active" interfaces.
 */
void
if_register(ifnet_t *ifp)
{
        /*
         * If the driver has not supplied its own if_ioctl or if_stop,
         * then supply the default.
         */
        if (ifp->if_ioctl == NULL)
                ifp->if_ioctl = ifioctl_common;
        if (ifp->if_stop == NULL)
                ifp->if_stop = if_nullstop;

        sysctl_sndq_setup(&ifp->if_sysctl_log, ifp->if_xname, &ifp->if_snd);

        if (!STAILQ_EMPTY(&domains))
                if_attachdomain1(ifp);

        /* Announce the interface. */
        rt_ifannouncemsg(ifp, IFAN_ARRIVAL);

        if (ifp->if_slowtimo != NULL) {
                struct if_slowtimo_data *isd;

                isd = kmem_zalloc(sizeof(*isd), KM_SLEEP);
                mutex_init(&isd->isd_lock, MUTEX_DEFAULT, IPL_SOFTCLOCK);
                callout_init(&isd->isd_ch, CALLOUT_MPSAFE);
                callout_setfunc(&isd->isd_ch, if_slowtimo_intr, ifp);
                isd->isd_ifp = ifp;

                ifp->if_slowtimo_data = isd;

                if_slowtimo_intr(ifp);

                sysctl_watchdog_setup(ifp);
        }

        if (ifp->if_transmit == NULL || ifp->if_transmit == if_nulltransmit)
                ifp->if_transmit = if_transmit;

        IFNET_GLOBAL_LOCK();
        TAILQ_INSERT_TAIL(&ifnet_list, ifp, if_list);
        IFNET_WRITER_INSERT_TAIL(ifp);
        IFNET_GLOBAL_UNLOCK();
}

/*
 * The if_percpuq framework
 *
 * It allows network device drivers to execute the network stack
 * in softint (so called softint-based if_input). It utilizes
 * softint and percpu ifqueue. It doesn't distribute any packets
 * between CPUs, unlike pktqueue(9).
 *
 * Currently we support two options for device drivers to apply the framework:
 * - Use it implicitly with less changes
 *   - If you use if_attach in driver's _attach function and if_input in
 *     driver's Rx interrupt handler, a packet is queued and a softint handles
 *     the packet implicitly
 * - Use it explicitly in each driver (recommended)
 *   - You can use if_percpuq_* directly in your driver
 *   - In this case, you need to allocate struct if_percpuq in driver's softc
 *   - See wm(4) as a reference implementation
 */

static void
if_percpuq_softint(void *arg)
{
        struct if_percpuq *ipq = arg;
        struct ifnet *ifp = ipq->ipq_ifp;
        struct mbuf *m;

        while ((m = if_percpuq_dequeue(ipq)) != NULL) {
                if_statinc(ifp, if_ipackets);
                bpf_mtap(ifp, m, BPF_D_IN);

                ifp->_if_input(ifp, m);
        }
}

static void
if_percpuq_init_ifq(void *p, void *arg __unused, struct cpu_info *ci __unused)
{
        struct ifqueue *const ifq = p;

        memset(ifq, 0, sizeof(*ifq));
        ifq->ifq_maxlen = IFQ_MAXLEN;
}

struct if_percpuq *
if_percpuq_create(struct ifnet *ifp)
{
        struct if_percpuq *ipq;
        u_int flags = SOFTINT_NET;

        flags |= if_is_mpsafe(ifp) ? SOFTINT_MPSAFE : 0;

        ipq = kmem_zalloc(sizeof(*ipq), KM_SLEEP);
        ipq->ipq_ifp = ifp;
        ipq->ipq_si = softint_establish(flags, if_percpuq_softint, ipq);
        ipq->ipq_ifqs = percpu_alloc(sizeof(struct ifqueue));
        percpu_foreach(ipq->ipq_ifqs, &if_percpuq_init_ifq, NULL);

        sysctl_percpuq_setup(&ifp->if_sysctl_log, ifp->if_xname, ipq);

        return ipq;
}

static struct mbuf *
if_percpuq_dequeue(struct if_percpuq *ipq)
{
        struct mbuf *m;
        struct ifqueue *ifq;

        const int s = splnet();
        ifq = percpu_getref(ipq->ipq_ifqs);
        IF_DEQUEUE(ifq, m);
        percpu_putref(ipq->ipq_ifqs);
        splx(s);

        return m;
}

static void
if_percpuq_purge_ifq(void *p, void *arg __unused, struct cpu_info *ci __unused)
{
        struct ifqueue *const ifq = p;

        IF_PURGE(ifq);
}

void
if_percpuq_destroy(struct if_percpuq *ipq)
{

        /* if_detach may already destroy it */
        if (ipq == NULL)
                return;

        softint_disestablish(ipq->ipq_si);
        percpu_foreach(ipq->ipq_ifqs, &if_percpuq_purge_ifq, NULL);
        percpu_free(ipq->ipq_ifqs, sizeof(struct ifqueue));
        kmem_free(ipq, sizeof(*ipq));
}

void
if_percpuq_enqueue(struct if_percpuq *ipq, struct mbuf *m)
{
        struct ifqueue *ifq;

        KASSERT(ipq != NULL);

        const int s = splnet();
        ifq = percpu_getref(ipq->ipq_ifqs);
        if (IF_QFULL(ifq)) {
                IF_DROP(ifq);
                percpu_putref(ipq->ipq_ifqs);
                if_statinc(ipq->ipq_ifp, if_iqdrops);
                m_freem(m);
                goto out;
        }
        IF_ENQUEUE(ifq, m);
        percpu_putref(ipq->ipq_ifqs);

        softint_schedule(ipq->ipq_si);
out:
        splx(s);
}

static void
if_percpuq_drops(void *p, void *arg, struct cpu_info *ci __unused)
{
        struct ifqueue *const ifq = p;
        uint64_t *sum = arg;

        *sum += ifq->ifq_drops;
}

static int
sysctl_percpuq_drops_handler(SYSCTLFN_ARGS)
{
        struct sysctlnode node;
        struct if_percpuq *ipq;
        uint64_t sum = 0;
        int error;

        node = *rnode;
        ipq = node.sysctl_data;

        percpu_foreach(ipq->ipq_ifqs, if_percpuq_drops, &sum);

        node.sysctl_data = &sum;
        error = sysctl_lookup(SYSCTLFN_CALL(&node));
        if (error != 0 || newp == NULL)
                return error;

        return 0;
}

static void
sysctl_percpuq_setup(struct sysctllog **clog, const char* ifname,
    struct if_percpuq *ipq)
{
        const struct sysctlnode *cnode, *rnode;

        if (sysctl_createv(clog, 0, NULL, &rnode,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "interfaces",
                       SYSCTL_DESCR("Per-interface controls"),
                       NULL, 0, NULL, 0,
                       CTL_NET, CTL_CREATE, CTL_EOL) != 0)
                goto bad;

        if (sysctl_createv(clog, 0, &rnode, &rnode,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, ifname,
                       SYSCTL_DESCR("Interface controls"),
                       NULL, 0, NULL, 0,
                       CTL_CREATE, CTL_EOL) != 0)
                goto bad;

        if (sysctl_createv(clog, 0, &rnode, &rnode,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "rcvq",
                       SYSCTL_DESCR("Interface input queue controls"),
                       NULL, 0, NULL, 0,
                       CTL_CREATE, CTL_EOL) != 0)
                goto bad;

#ifdef NOTYET
        /* XXX Should show each per-CPU queue length? */
        if (sysctl_createv(clog, 0, &rnode, &rnode,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_INT, "len",
                       SYSCTL_DESCR("Current input queue length"),
                       sysctl_percpuq_len, 0, NULL, 0,
                       CTL_CREATE, CTL_EOL) != 0)
                goto bad;

        if (sysctl_createv(clog, 0, &rnode, &cnode,
                       CTLFLAG_PERMANENT | CTLFLAG_READWRITE,
                       CTLTYPE_INT, "maxlen",
                       SYSCTL_DESCR("Maximum allowed input queue length"),
                       sysctl_percpuq_maxlen_handler, 0, (void *)ipq, 0,
                       CTL_CREATE, CTL_EOL) != 0)
                goto bad;
#endif

        if (sysctl_createv(clog, 0, &rnode, &cnode,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_QUAD, "drops",
                       SYSCTL_DESCR("Total packets dropped due to full input queue"),
                       sysctl_percpuq_drops_handler, 0, (void *)ipq, 0,
                       CTL_CREATE, CTL_EOL) != 0)
                goto bad;

        return;
bad:
        printf("%s: could not attach sysctl nodes\n", ifname);
        return;
}

/*
 * The deferred if_start framework
 *
 * The common APIs to defer if_start to softint when if_start is requested
 * from a device driver running in hardware interrupt context.
 */
/*
 * Call ifp->if_start (or equivalent) in a dedicated softint for
 * deferred if_start.
 */
static void
if_deferred_start_softint(void *arg)
{
        struct if_deferred_start *ids = arg;
        struct ifnet *ifp = ids->ids_ifp;

        ids->ids_if_start(ifp);
}

/*
 * The default callback function for deferred if_start.
 */
static void
if_deferred_start_common(struct ifnet *ifp)
{
        const int s = splnet();
        if_start_lock(ifp);
        splx(s);
}

static inline bool
if_snd_is_used(struct ifnet *ifp)
{

        return ALTQ_IS_ENABLED(&ifp->if_snd) ||
            ifp->if_transmit == if_transmit ||
            ifp->if_transmit == NULL ||
            ifp->if_transmit == if_nulltransmit;
}

/*
 * Schedule deferred if_start.
 */
void
if_schedule_deferred_start(struct ifnet *ifp)
{

        KASSERT(ifp->if_deferred_start != NULL);

        if (if_snd_is_used(ifp) && IFQ_IS_EMPTY(&ifp->if_snd))
                return;

        softint_schedule(ifp->if_deferred_start->ids_si);
}

/*
 * Create an instance of deferred if_start. A driver should call the function
 * only if the driver needs deferred if_start. Drivers can setup their own
 * deferred if_start function via 2nd argument.
 */
void
if_deferred_start_init(struct ifnet *ifp, void (*func)(struct ifnet *))
{
        struct if_deferred_start *ids;
        u_int flags = SOFTINT_NET;

        flags |= if_is_mpsafe(ifp) ? SOFTINT_MPSAFE : 0;

        ids = kmem_zalloc(sizeof(*ids), KM_SLEEP);
        ids->ids_ifp = ifp;
        ids->ids_si = softint_establish(flags, if_deferred_start_softint, ids);
        if (func != NULL)
                ids->ids_if_start = func;
        else
                ids->ids_if_start = if_deferred_start_common;

        ifp->if_deferred_start = ids;
}

static void
if_deferred_start_destroy(struct ifnet *ifp)
{

        if (ifp->if_deferred_start == NULL)
                return;

        softint_disestablish(ifp->if_deferred_start->ids_si);
        kmem_free(ifp->if_deferred_start, sizeof(*ifp->if_deferred_start));
        ifp->if_deferred_start = NULL;
}

/*
 * The common interface input routine that is called by device drivers,
 * which should be used only when the driver's rx handler already runs
 * in softint.
 */
void
if_input(struct ifnet *ifp, struct mbuf *m)
{

        KASSERT(ifp->if_percpuq == NULL);
        KASSERT(!cpu_intr_p());

        if_statinc(ifp, if_ipackets);
        bpf_mtap(ifp, m, BPF_D_IN);

        ifp->_if_input(ifp, m);
}

/*
 * DEPRECATED. Use if_initialize and if_register instead.
 * See the above comment of if_initialize.
 *
 * Note that it implicitly enables if_percpuq to make drivers easy to
 * migrate softint-based if_input without much changes. If you don't
 * want to enable it, use if_initialize instead.
 */
void
if_attach(ifnet_t *ifp)
{

        if_initialize(ifp);
        ifp->if_percpuq = if_percpuq_create(ifp);
        if_register(ifp);
}

void
if_attachdomain(void)
{
        struct ifnet *ifp;
        const int bound = curlwp_bind();

        int s = pserialize_read_enter();
        IFNET_READER_FOREACH(ifp) {
                struct psref psref;
                psref_acquire(&psref, &ifp->if_psref, ifnet_psref_class);
                pserialize_read_exit(s);
                if_attachdomain1(ifp);
                s = pserialize_read_enter();
                psref_release(&psref, &ifp->if_psref, ifnet_psref_class);
        }
        pserialize_read_exit(s);
        curlwp_bindx(bound);
}

static void
if_attachdomain1(struct ifnet *ifp)
{
        struct domain *dp;
        const int s = splsoftnet();

        /* address family dependent data region */
        memset(ifp->if_afdata, 0, sizeof(ifp->if_afdata));
        DOMAIN_FOREACH(dp) {
                if (dp->dom_ifattach != NULL)
                        ifp->if_afdata[dp->dom_family] =
                            (*dp->dom_ifattach)(ifp);
        }

        splx(s);
}

/*
 * Deactivate an interface.  This points all of the procedure
 * handles at error stubs.  May be called from interrupt context.
 */
void
if_deactivate(struct ifnet *ifp)
{
        const int s = splsoftnet();

        ifp->if_output   = if_nulloutput;
        ifp->_if_input   = if_nullinput;
        ifp->if_start    = if_nullstart;
        ifp->if_transmit = if_nulltransmit;
        ifp->if_ioctl    = if_nullioctl;
        ifp->if_init     = if_nullinit;
        ifp->if_stop     = if_nullstop;
        if (ifp->if_slowtimo)
                ifp->if_slowtimo = if_nullslowtimo;
        ifp->if_drain    = if_nulldrain;

        /* No more packets may be enqueued. */
        ifp->if_snd.ifq_maxlen = 0;

        splx(s);
}

bool
if_is_deactivated(const struct ifnet *ifp)
{

        return ifp->if_output == if_nulloutput;
}

void
if_purgeaddrs(struct ifnet *ifp, int family,
    void (*purgeaddr)(struct ifaddr *))
{
        struct ifaddr *ifa, *nifa;
        int s;

        s = pserialize_read_enter();
        for (ifa = IFADDR_READER_FIRST(ifp); ifa; ifa = nifa) {
                nifa = IFADDR_READER_NEXT(ifa);
                if (ifa->ifa_addr->sa_family != family)
                        continue;
                pserialize_read_exit(s);

                (*purgeaddr)(ifa);

                s = pserialize_read_enter();
        }
        pserialize_read_exit(s);
}

#ifdef IFAREF_DEBUG
static struct ifaddr **ifa_list;
static int ifa_list_size;

/* Depends on only one if_attach runs at once */
static void
if_build_ifa_list(struct ifnet *ifp)
{
        struct ifaddr *ifa;
        int i;

        KASSERT(ifa_list == NULL);
        KASSERT(ifa_list_size == 0);

        IFADDR_READER_FOREACH(ifa, ifp)
                ifa_list_size++;

        ifa_list = kmem_alloc(sizeof(*ifa) * ifa_list_size, KM_SLEEP);
        i = 0;
        IFADDR_READER_FOREACH(ifa, ifp) {
                ifa_list[i++] = ifa;
                ifaref(ifa);
        }
}

static void
if_check_and_free_ifa_list(struct ifnet *ifp)
{
        int i;
        struct ifaddr *ifa;

        if (ifa_list == NULL)
                return;

        for (i = 0; i < ifa_list_size; i++) {
                char buf[64];

                ifa = ifa_list[i];
                sockaddr_format(ifa->ifa_addr, buf, sizeof(buf));
                if (ifa->ifa_refcnt > 1) {
                        log(LOG_WARNING,
                            "ifa(%s) still referenced (refcnt=%d)\n",
                            buf, ifa->ifa_refcnt - 1);
                } else
                        log(LOG_DEBUG,
                            "ifa(%s) not referenced (refcnt=%d)\n",
                            buf, ifa->ifa_refcnt - 1);
                ifafree(ifa);
        }

        kmem_free(ifa_list, sizeof(*ifa) * ifa_list_size);
        ifa_list = NULL;
        ifa_list_size = 0;
}
#endif

/*
 * Detach an interface from the list of "active" interfaces,
 * freeing any resources as we go along.
 *
 * NOTE: This routine must be called with a valid thread context,
 * as it may block.
 */
void
if_detach(struct ifnet *ifp)
{
        struct socket so;
        struct ifaddr *ifa;
#ifdef IFAREF_DEBUG
        struct ifaddr *last_ifa = NULL;
#endif
        struct domain *dp;
        const struct protosw *pr;
        int i, family, purged;

#ifdef IFAREF_DEBUG
        if_build_ifa_list(ifp);
#endif
        /*
         * XXX It's kind of lame that we have to have the
         * XXX socket structure...
         */
        memset(&so, 0, sizeof(so));

        const int s = splnet();

        sysctl_teardown(&ifp->if_sysctl_log);

        IFNET_LOCK(ifp);

        /*
         * Lock the link queue.
         * This stops any more link state changes occurring for this
         * interface while it's being detached so it's safe
         * to drain the workqueue.
         */
        IF_LINK_STATE_CHANGE_LOCK(ifp);
        ifp->if_link_queue = LINK_QUEUE_LOCKED;
        IF_LINK_STATE_CHANGE_UNLOCK(ifp);
        workqueue_wait(ifnet_link_state_wq, &ifp->if_link_work);

        if_deactivate(ifp);
        IFNET_UNLOCK(ifp);

        /*
         * Unlink from the list and wait for all readers to leave
         * from pserialize read sections.  Note that we can't do
         * psref_target_destroy here.  See below.
         */
        IFNET_GLOBAL_LOCK();
        ifindex2ifnet[ifp->if_index] = NULL;
        TAILQ_REMOVE(&ifnet_list, ifp, if_list);
        IFNET_WRITER_REMOVE(ifp);
        pserialize_perform(ifnet_psz);
        IFNET_GLOBAL_UNLOCK();

        if (ifp->if_slowtimo != NULL) {
                struct if_slowtimo_data *isd = ifp->if_slowtimo_data;

                mutex_enter(&isd->isd_lock);
                isd->isd_dying = true;
                mutex_exit(&isd->isd_lock);
                callout_halt(&isd->isd_ch, NULL);
                workqueue_wait(if_slowtimo_wq, &isd->isd_work);
                callout_destroy(&isd->isd_ch);
                mutex_destroy(&isd->isd_lock);
                kmem_free(isd, sizeof(*isd));

                ifp->if_slowtimo_data = NULL; /* paraonia */
                ifp->if_slowtimo = NULL;      /* paranoia */
        }
        if_deferred_start_destroy(ifp);

        /*
         * Do an if_down() to give protocols a chance to do something.
         */
        if_down_deactivated(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 NCARP > 0
        /* Remove the interface from any carp group it is a part of.  */
        if (ifp->if_carp != NULL && ifp->if_type != IFT_CARP)
                carp_ifdetach(ifp);
#endif

        /*
         * Ensure that all packets on protocol input pktqueues have been
         * processed, or, at least, removed from the queues.
         *
         * A cross-call will ensure that the interrupts have completed.
         * FIXME: not quite..
         */
        pktq_ifdetach();
        xc_barrier(0);

        /*
         * Rip all the addresses off the interface.  This should make
         * all of the routes go away.
         *
         * pr_usrreq calls can remove an arbitrary number of ifaddrs
         * from the list, including our "cursor", ifa.  For safety,
         * and to honor the TAILQ abstraction, I just restart the
         * loop after each removal.  Note that the loop will exit
         * when all of the remaining ifaddrs belong to the AF_LINK
         * family.  I am counting on the historical fact that at
         * least one pr_usrreq in each address domain removes at
         * least one ifaddr.
         */
again:
        /*
         * At this point, no other one tries to remove ifa in the list,
         * so we don't need to take a lock or psref.  Avoid using
         * IFADDR_READER_FOREACH to pass over an inspection of contract
         * violations of pserialize.
         */
        IFADDR_WRITER_FOREACH(ifa, ifp) {
                family = ifa->ifa_addr->sa_family;
#ifdef IFAREF_DEBUG
                printf("if_detach: ifaddr %p, family %d, refcnt %d\n",
                    ifa, family, ifa->ifa_refcnt);
                if (last_ifa != NULL && ifa == last_ifa)
                        panic("if_detach: loop detected");
                last_ifa = ifa;
#endif
                if (family == AF_LINK)
                        continue;
                dp = pffinddomain(family);
                KASSERTMSG(dp != NULL, "no domain for AF %d", family);
                /*
                 * XXX These PURGEIF calls are redundant with the
                 * purge-all-families calls below, but are left in for
                 * now both to make a smaller change, and to avoid
                 * unplanned interactions with clearing of
                 * ifp->if_addrlist.
                 */
                purged = 0;
                for (pr = dp->dom_protosw;
                     pr < dp->dom_protoswNPROTOSW; pr++) {
                        so.so_proto = pr;
                        if (pr->pr_usrreqs) {
                                (void) (*pr->pr_usrreqs->pr_purgeif)(&so, ifp);
                                purged = 1;
                        }
                }
                if (purged == 0) {
                        /*
                         * XXX What's really the best thing to do
                         * XXX here?  --thorpej@NetBSD.org
                         */
                        printf("if_detach: WARNING: AF %d not purged\n",
                            family);
                        ifa_remove(ifp, ifa);
                }
                goto again;
        }

        if_free_sadl(ifp, 1);

restart:
        IFADDR_WRITER_FOREACH(ifa, ifp) {
                family = ifa->ifa_addr->sa_family;
                KASSERT(family == AF_LINK);
                ifa_remove(ifp, ifa);
                goto restart;
        }

        /* Delete stray routes from the routing table. */
        for (i = 0; i <= AF_MAX; i++)
                rt_delete_matched_entries(i, if_delroute_matcher, ifp, false);

        DOMAIN_FOREACH(dp) {
                if (dp->dom_ifdetach != NULL && ifp->if_afdata[dp->dom_family])
                {
                        void *p = ifp->if_afdata[dp->dom_family];
                        if (p) {
                                ifp->if_afdata[dp->dom_family] = NULL;
                                (*dp->dom_ifdetach)(ifp, p);
                        }
                }

                /*
                 * One would expect multicast memberships (INET and
                 * INET6) on UDP sockets to be purged by the PURGEIF
                 * calls above, but if all addresses were removed from
                 * the interface prior to destruction, the calls will
                 * not be made (e.g. ppp, for which pppd(8) generally
                 * removes addresses before destroying the interface).
                 * Because there is no invariant that multicast
                 * memberships only exist for interfaces with IPv4
                 * addresses, we must call PURGEIF regardless of
                 * addresses.  (Protocols which might store ifnet
                 * pointers are marked with PR_PURGEIF.)
                 */
                for (pr = dp->dom_protosw; pr < dp->dom_protoswNPROTOSW; pr++)
                {
                        so.so_proto = pr;
                        if (pr->pr_usrreqs && pr->pr_flags & PR_PURGEIF)
                                (void)(*pr->pr_usrreqs->pr_purgeif)(&so, ifp);
                }
        }

        /*
         * Must be done after the above pr_purgeif because if_psref may be
         * still used in pr_purgeif.
         */
        psref_target_destroy(&ifp->if_psref, ifnet_psref_class);
        PSLIST_ENTRY_DESTROY(ifp, if_pslist_entry);

        pfil_run_ifhooks(if_pfil, PFIL_IFNET_DETACH, ifp);
        (void)pfil_head_destroy(ifp->if_pfil);

        /* Announce that the interface is gone. */
        rt_ifannouncemsg(ifp, IFAN_DEPARTURE);

        IF_AFDATA_LOCK_DESTROY(ifp);

        if (ifp->if_percpuq != NULL) {
                if_percpuq_destroy(ifp->if_percpuq);
                ifp->if_percpuq = NULL;
        }

        mutex_obj_free(ifp->if_ioctl_lock);
        ifp->if_ioctl_lock = NULL;
        mutex_obj_free(ifp->if_snd.ifq_lock);
        if_stats_fini(ifp);
        KASSERT(!simplehook_has_hooks(ifp->if_linkstate_hooks));
        simplehook_destroy(ifp->if_linkstate_hooks);

        splx(s);

#ifdef IFAREF_DEBUG
        if_check_and_free_ifa_list(ifp);
#endif
}

/*
 * Callback for a radix tree walk to delete all references to an
 * ifnet.
 */
static int
if_delroute_matcher(struct rtentry *rt, void *v)
{
        struct ifnet *ifp = (struct ifnet *)v;

        if (rt->rt_ifp == ifp)
                return 1;
        else
                return 0;
}

/*
 * Create a clone network interface.
 */
static int
if_clone_create(const char *name)
{
        struct if_clone *ifc;
        struct ifnet *ifp;
        struct psref psref;
        int unit;

        KASSERT(mutex_owned(&if_clone_mtx));

        ifc = if_clone_lookup(name, &unit);
        if (ifc == NULL)
                return EINVAL;

        ifp = if_get(name, &psref);
        if (ifp != NULL) {
                if_put(ifp, &psref);
                return EEXIST;
        }

        return (*ifc->ifc_create)(ifc, unit);
}

/*
 * Destroy a clone network interface.
 */
static int
if_clone_destroy(const char *name)
{
        struct if_clone *ifc;
        struct ifnet *ifp;
        struct psref psref;
        int error;
        int (*if_ioctlfn)(struct ifnet *, u_long, void *);

        KASSERT(mutex_owned(&if_clone_mtx));

        ifc = if_clone_lookup(name, NULL);
        if (ifc == NULL)
                return EINVAL;

        if (ifc->ifc_destroy == NULL)
                return EOPNOTSUPP;

        ifp = if_get(name, &psref);
        if (ifp == NULL)
                return ENXIO;

        /* We have to disable ioctls here */
        IFNET_LOCK(ifp);
        if_ioctlfn = ifp->if_ioctl;
        ifp->if_ioctl = if_nullioctl;
        IFNET_UNLOCK(ifp);

        /*
         * We cannot call ifc_destroy with holding ifp.
         * Releasing ifp here is safe thanks to if_clone_mtx.
         */
        if_put(ifp, &psref);

        error = (*ifc->ifc_destroy)(ifp);

        if (error != 0) {
                /* We have to restore if_ioctl on error */
                IFNET_LOCK(ifp);
                ifp->if_ioctl = if_ioctlfn;
                IFNET_UNLOCK(ifp);
        }

        return error;
}

static bool
if_is_unit(const char *name)
{

        while (*name != '\0') {
                if (*name < '0' || *name > '9')
                        return false;
                name++;
        }

        return true;
}

/*
 * Look up a network interface cloner.
 */
static struct if_clone *
if_clone_lookup(const char *name, int *unitp)
{
        struct if_clone *ifc;
        const char *cp;
        char *dp, ifname[IFNAMSIZ + 3];
        int unit;

        KASSERT(mutex_owned(&if_clone_mtx));

        strcpy(ifname, "if_");
        /* separate interface name from unit */
        /* TODO: search unit number from backward */
        for (dp = ifname + 3, cp = name; cp - name < IFNAMSIZ &&
            *cp && !if_is_unit(cp);)
                *dp++ = *cp++;

        if (cp == name || cp - name == IFNAMSIZ || !*cp)
                return NULL;    /* No name or unit number */
        *dp++ = '\0';

again:
        LIST_FOREACH(ifc, &if_cloners, ifc_list) {
                if (strcmp(ifname + 3, ifc->ifc_name) == 0)
                        break;
        }

        if (ifc == NULL) {
                int error;
                if (*ifname == '\0')
                        return NULL;
                mutex_exit(&if_clone_mtx);
                error = module_autoload(ifname, MODULE_CLASS_DRIVER);
                mutex_enter(&if_clone_mtx);
                if (error)
                        return NULL;
                *ifname = '\0';
                goto again;
        }

        unit = 0;
        while (cp - name < IFNAMSIZ && *cp) {
                if (*cp < '0' || *cp > '9' || unit >= INT_MAX / 10) {
                        /* Bogus unit number. */
                        return NULL;
                }
                unit = (unit * 10) + (*cp++ - '0');
        }

        if (unitp != NULL)
                *unitp = unit;
        return ifc;
}

/*
 * Register a network interface cloner.
 */
void
if_clone_attach(struct if_clone *ifc)
{

        mutex_enter(&if_clone_mtx);
        LIST_INSERT_HEAD(&if_cloners, ifc, ifc_list);
        if_cloners_count++;
        mutex_exit(&if_clone_mtx);
}

/*
 * Unregister a network interface cloner.
 */
void
if_clone_detach(struct if_clone *ifc)
{

        mutex_enter(&if_clone_mtx);
        LIST_REMOVE(ifc, ifc_list);
        if_cloners_count--;
        mutex_exit(&if_clone_mtx);
}

/*
 * Provide list of interface cloners to userspace.
 */
int
if_clone_list(int buf_count, char *buffer, int *total)
{
        char outbuf[IFNAMSIZ], *dst;
        struct if_clone *ifc;
        int count, error = 0;

        mutex_enter(&if_clone_mtx);
        *total = if_cloners_count;
        if ((dst = buffer) == NULL) {
                /* Just asking how many there are. */
                goto out;
        }

        if (buf_count < 0) {
                error = EINVAL;
                goto out;
        }

        count = (if_cloners_count < buf_count) ? if_cloners_count : buf_count;

        for (ifc = LIST_FIRST(&if_cloners); ifc != NULL && count != 0;
             ifc = LIST_NEXT(ifc, ifc_list), count--, dst += IFNAMSIZ) {
                (void)strncpy(outbuf, ifc->ifc_name, sizeof(outbuf));
                if (outbuf[sizeof(outbuf) - 1] != '\0') {
                        error = ENAMETOOLONG;
                        goto out;
                }
                error = copyout(outbuf, dst, sizeof(outbuf));
                if (error != 0)
                        break;
        }

out:
        mutex_exit(&if_clone_mtx);
        return error;
}

void
ifa_psref_init(struct ifaddr *ifa)
{

        psref_target_init(&ifa->ifa_psref, ifa_psref_class);
}

void
ifaref(struct ifaddr *ifa)
{

        atomic_inc_uint(&ifa->ifa_refcnt);
}

void
ifafree(struct ifaddr *ifa)
{
        KASSERT(ifa != NULL);
        KASSERTMSG(ifa->ifa_refcnt > 0, "ifa_refcnt=%d", ifa->ifa_refcnt);

        membar_release();
        if (atomic_dec_uint_nv(&ifa->ifa_refcnt) != 0)
                return;
        membar_acquire();
        free(ifa, M_IFADDR);
}

bool
ifa_is_destroying(struct ifaddr *ifa)
{

        return ISSET(ifa->ifa_flags, IFA_DESTROYING);
}

void
ifa_insert(struct ifnet *ifp, struct ifaddr *ifa)
{

        ifa->ifa_ifp = ifp;

        /*
         * Check MP-safety for IFEF_MPSAFE drivers.
         * Check !IFF_RUNNING for initialization routines that normally don't
         * take IFNET_LOCK but it's safe because there is no competitor.
         * XXX there are false positive cases because IFF_RUNNING can be off on
         * if_stop.
         */
        KASSERT(!if_is_mpsafe(ifp) || !ISSET(ifp->if_flags, IFF_RUNNING) ||
            IFNET_LOCKED(ifp));

        TAILQ_INSERT_TAIL(&ifp->if_addrlist, ifa, ifa_list);
        IFADDR_ENTRY_INIT(ifa);
        IFADDR_WRITER_INSERT_TAIL(ifp, ifa);

        ifaref(ifa);
}

void
ifa_remove(struct ifnet *ifp, struct ifaddr *ifa)
{

        KASSERT(ifa->ifa_ifp == ifp);
        /*
         * Check MP-safety for IFEF_MPSAFE drivers.
         * if_is_deactivated indicates ifa_remove is called from if_detach
         * where it is safe even if IFNET_LOCK isn't held.
         */
        KASSERT(!if_is_mpsafe(ifp) || if_is_deactivated(ifp) ||
            IFNET_LOCKED(ifp));

        TAILQ_REMOVE(&ifp->if_addrlist, ifa, ifa_list);
        IFADDR_WRITER_REMOVE(ifa);
#ifdef NET_MPSAFE
        IFNET_GLOBAL_LOCK();
        pserialize_perform(ifnet_psz);
        IFNET_GLOBAL_UNLOCK();
#endif

#ifdef NET_MPSAFE
        psref_target_destroy(&ifa->ifa_psref, ifa_psref_class);
#endif
        IFADDR_ENTRY_DESTROY(ifa);
        ifafree(ifa);
}

void
ifa_acquire(struct ifaddr *ifa, struct psref *psref)
{

        PSREF_DEBUG_FILL_RETURN_ADDRESS(psref);
        psref_acquire(psref, &ifa->ifa_psref, ifa_psref_class);
}

void
ifa_release(struct ifaddr *ifa, struct psref *psref)
{

        if (ifa == NULL)
                return;

        psref_release(psref, &ifa->ifa_psref, ifa_psref_class);
}

bool
ifa_held(struct ifaddr *ifa)
{

        return psref_held(&ifa->ifa_psref, ifa_psref_class);
}

static inline int
equal(const struct sockaddr *sa1, const struct sockaddr *sa2)
{

        return sockaddr_cmp(sa1, sa2) == 0;
}

/*
 * Locate an interface based on a complete address.
 */
/*ARGSUSED*/
struct ifaddr *
ifa_ifwithaddr(const struct sockaddr *addr)
{
        struct ifnet *ifp;
        struct ifaddr *ifa;

        IFNET_READER_FOREACH(ifp) {
                if (if_is_deactivated(ifp))
                        continue;
                IFADDR_READER_FOREACH(ifa, ifp) {
                        if (ifa->ifa_addr->sa_family != addr->sa_family)
                                continue;
                        if (equal(addr, ifa->ifa_addr))
                                return ifa;
                        if ((ifp->if_flags & IFF_BROADCAST) &&
                            ifa->ifa_broadaddr &&
                            /* IP6 doesn't have broadcast */
                            ifa->ifa_broadaddr->sa_len != 0 &&
                            equal(ifa->ifa_broadaddr, addr))
                                return ifa;
                }
        }
        return NULL;
}

struct ifaddr *
ifa_ifwithaddr_psref(const struct sockaddr *addr, struct psref *psref)
{
        struct ifaddr *ifa;
        int s = pserialize_read_enter();

        ifa = ifa_ifwithaddr(addr);
        if (ifa != NULL)
                ifa_acquire(ifa, psref);
        pserialize_read_exit(s);

        return ifa;
}

/*
 * Locate the point to point interface with a given destination address.
 */
/*ARGSUSED*/
struct ifaddr *
ifa_ifwithdstaddr(const struct sockaddr *addr)
{
        struct ifnet *ifp;
        struct ifaddr *ifa;

        IFNET_READER_FOREACH(ifp) {
                if (if_is_deactivated(ifp))
                        continue;
                if ((ifp->if_flags & IFF_POINTOPOINT) == 0)
                        continue;
                IFADDR_READER_FOREACH(ifa, ifp) {
                        if (ifa->ifa_addr->sa_family != addr->sa_family ||
                            ifa->ifa_dstaddr == NULL)
                                continue;
                        if (equal(addr, ifa->ifa_dstaddr))
                                return ifa;
                }
        }

        return NULL;
}

struct ifaddr *
ifa_ifwithdstaddr_psref(const struct sockaddr *addr, struct psref *psref)
{
        struct ifaddr *ifa;
        int s;

        s = pserialize_read_enter();
        ifa = ifa_ifwithdstaddr(addr);
        if (ifa != NULL)
                ifa_acquire(ifa, psref);
        pserialize_read_exit(s);

        return ifa;
}

/*
 * Find an interface on a specific network.  If many, choice
 * is most specific found.
 */
struct ifaddr *
ifa_ifwithnet(const struct sockaddr *addr)
{
        struct ifnet *ifp;
        struct ifaddr *ifa, *ifa_maybe = NULL;
        const struct sockaddr_dl *sdl;
        u_int af = addr->sa_family;
        const char *addr_data = addr->sa_data, *cplim;

        if (af == AF_LINK) {
                sdl = satocsdl(addr);
                if (sdl->sdl_index && sdl->sdl_index < if_indexlim &&
                    ifindex2ifnet[sdl->sdl_index] &&
                    !if_is_deactivated(ifindex2ifnet[sdl->sdl_index])) {
                        return ifindex2ifnet[sdl->sdl_index]->if_dl;
                }
        }
#ifdef NETATALK
        if (af == AF_APPLETALK) {
                const struct sockaddr_at *sat, *sat2;
                sat = (const struct sockaddr_at *)addr;
                IFNET_READER_FOREACH(ifp) {
                        if (if_is_deactivated(ifp))
                                continue;
                        ifa = at_ifawithnet((const struct sockaddr_at *)addr,
                            ifp);
                        if (ifa == NULL)
                                continue;
                        sat2 = (struct sockaddr_at *)ifa->ifa_addr;
                        if (sat2->sat_addr.s_net == sat->sat_addr.s_net)
                                return ifa; /* exact match */
                        if (ifa_maybe == NULL) {
                                /* else keep the if with the right range */
                                ifa_maybe = ifa;
                        }
                }
                return ifa_maybe;
        }
#endif
        IFNET_READER_FOREACH(ifp) {
                if (if_is_deactivated(ifp))
                        continue;
                IFADDR_READER_FOREACH(ifa, ifp) {
                        const char *cp, *cp2, *cp3;

                        if (ifa->ifa_addr->sa_family != af ||
                            ifa->ifa_netmask == NULL)
 next:                          continue;
                        cp = addr_data;
                        cp2 = ifa->ifa_addr->sa_data;
                        cp3 = ifa->ifa_netmask->sa_data;
                        cplim = (const char *)ifa->ifa_netmask +
                            ifa->ifa_netmask->sa_len;
                        while (cp3 < cplim) {
                                if ((*cp++ ^ *cp2++) & *cp3++) {
                                        /* want to continue for() loop */
                                        goto next;
                                }
                        }
                        if (ifa_maybe == NULL ||
                            rt_refines(ifa->ifa_netmask,
                                       ifa_maybe->ifa_netmask))
                                ifa_maybe = ifa;
                }
        }
        return ifa_maybe;
}

struct ifaddr *
ifa_ifwithnet_psref(const struct sockaddr *addr, struct psref *psref)
{
        struct ifaddr *ifa;
        int s;

        s = pserialize_read_enter();
        ifa = ifa_ifwithnet(addr);
        if (ifa != NULL)
                ifa_acquire(ifa, psref);
        pserialize_read_exit(s);

        return ifa;
}

/*
 * Find the interface of the address.
 */
struct ifaddr *
ifa_ifwithladdr(const struct sockaddr *addr)
{
        struct ifaddr *ia;

        if ((ia = ifa_ifwithaddr(addr)) || (ia = ifa_ifwithdstaddr(addr)) ||
            (ia = ifa_ifwithnet(addr)))
                return ia;
        return NULL;
}

struct ifaddr *
ifa_ifwithladdr_psref(const struct sockaddr *addr, struct psref *psref)
{
        struct ifaddr *ifa;
        int s;

        s = pserialize_read_enter();
        ifa = ifa_ifwithladdr(addr);
        if (ifa != NULL)
                ifa_acquire(ifa, psref);
        pserialize_read_exit(s);

        return ifa;
}

struct ifaddr *
if_first_addr(const struct ifnet *ifp, const int af)
{
        struct ifaddr *ifa = NULL;

        IFADDR_READER_FOREACH(ifa, ifp) {
                if (ifa->ifa_addr->sa_family == af)
                        break;
        }
        return ifa;
}

struct ifaddr *
if_first_addr_psref(const struct ifnet *ifp, const int af, struct psref *psref)
{
        struct ifaddr *ifa;
        int s;

        s = pserialize_read_enter();
        ifa = if_first_addr(ifp, af);
        if (ifa != NULL)
                ifa_acquire(ifa, psref);
        pserialize_read_exit(s);

        return ifa;
}

/*
 * Find an interface address specific to an interface best matching
 * a given address.
 */
struct ifaddr *
ifaof_ifpforaddr(const struct sockaddr *addr, struct ifnet *ifp)
{
        struct ifaddr *ifa;
        const char *cp, *cp2, *cp3;
        const char *cplim;
        struct ifaddr *ifa_maybe = 0;
        u_int af = addr->sa_family;

        if (if_is_deactivated(ifp))
                return NULL;

        if (af >= AF_MAX)
                return NULL;

        IFADDR_READER_FOREACH(ifa, ifp) {
                if (ifa->ifa_addr->sa_family != af)
                        continue;
                ifa_maybe = ifa;
                if (ifa->ifa_netmask == NULL) {
                        if (equal(addr, ifa->ifa_addr) ||
                            (ifa->ifa_dstaddr &&
                             equal(addr, ifa->ifa_dstaddr)))
                                return ifa;
                        continue;
                }
                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)
                        return ifa;
        }
        return ifa_maybe;
}

struct ifaddr *
ifaof_ifpforaddr_psref(const struct sockaddr *addr, struct ifnet *ifp,
    struct psref *psref)
{
        struct ifaddr *ifa;
        int s;

        s = pserialize_read_enter();
        ifa = ifaof_ifpforaddr(addr, ifp);
        if (ifa != NULL)
                ifa_acquire(ifa, psref);
        pserialize_read_exit(s);

        return ifa;
}

/*
 * 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.
 */
void
link_rtrequest(int cmd, struct rtentry *rt, const struct rt_addrinfo *info)
{
        struct ifaddr *ifa;
        const struct sockaddr *dst;
        struct ifnet *ifp;
        struct psref psref;

        if (cmd != RTM_ADD || ISSET(info->rti_flags, RTF_DONTCHANGEIFA))
                return;
        ifp = rt->rt_ifa->ifa_ifp;
        dst = rt_getkey(rt);
        if ((ifa = ifaof_ifpforaddr_psref(dst, ifp, &psref)) != NULL) {
                rt_replace_ifa(rt, ifa);
                if (ifa->ifa_rtrequest && ifa->ifa_rtrequest != link_rtrequest)
                        ifa->ifa_rtrequest(cmd, rt, info);
                ifa_release(ifa, &psref);
        }
}

/*
 * Handle a change in the interface link state and
 * queue notifications.
 */
void
if_link_state_change(struct ifnet *ifp, int link_state)
{
        uint16_t queue;

        IF_LINK_STATE_CHANGE_LOCK(ifp);

        if (ifp->if_link_queue & LINK_QUEUE_LOCKED)
                goto out;

        /* If nothing is queued and we are already at the state, do nothing. */
        if (ifp->if_link_queue == 0 && ifp->if_link_state == link_state)
                goto out;

        /*
         * The logic is simple.
         * DOWN will remove any existing states and will be processed first.
         * UNKNOWN will remove the UP state and will be processed after DOWN.
         * UP will be processed last.
         * So if an interface link state flaps fast, userland will be kept in
         * sane state with minimal notifications.
         */
        queue = ifp->if_link_queue;
        switch (link_state) {
        case LINK_STATE_UNKNOWN:
                /* cannot be UP */
                queue &= ~LINK_QUEUE_UP;
                queue |= LINK_QUEUE_UNKNOWN;
                break;
        case LINK_STATE_DOWN:
                /* cannot be UNKNOWN or UP */
                queue &= ~(LINK_QUEUE_UNKNOWN | LINK_QUEUE_UP);
                queue |= LINK_QUEUE_DOWN;
                break;
        case LINK_STATE_UP:
                queue |= LINK_QUEUE_UP;
                break;
        default:
#ifdef DEBUG
                printf("%s: invalid link state %d\n",
                    ifp->if_xname, link_state);
#endif
                goto out;
        }

        if (ifp->if_link_queue == queue)
                goto out;

        ifp->if_link_queue = queue;
        if (ifp->if_link_queue & LINK_QUEUE_SCHEDULED)
                goto out;

        ifp->if_link_queue |= LINK_QUEUE_SCHEDULED;
        workqueue_enqueue(ifnet_link_state_wq, &ifp->if_link_work, NULL);

out:
        IF_LINK_STATE_CHANGE_UNLOCK(ifp);
}

/*
 * Handle interface link state change notifications.
 */
static void
if_link_state_change_process(struct ifnet *ifp, int link_state)
{
        struct domain *dp;
        const int s = splnet();
        bool notify;

        KASSERT(!cpu_intr_p());

        IF_LINK_STATE_CHANGE_LOCK(ifp);

        /* Ensure the change is still valid. */
        if (ifp->if_link_state == link_state) {
                IF_LINK_STATE_CHANGE_UNLOCK(ifp);
                splx(s);
                return;
        }

#ifdef DEBUG
        log(LOG_DEBUG, "%s: link state %s (was %s)\n", ifp->if_xname,
                link_state == LINK_STATE_UP ? "UP" :
                link_state == LINK_STATE_DOWN ? "DOWN" :
                "UNKNOWN",
                ifp->if_link_state == LINK_STATE_UP ? "UP" :
                ifp->if_link_state == LINK_STATE_DOWN ? "DOWN" :
                "UNKNOWN");
#endif

        /*
         * When going from UNKNOWN to UP, we need to mark existing
         * addresses as tentative and restart DAD as we may have
         * erroneously not found a duplicate.
         *
         * This needs to happen before rt_ifmsg to avoid a race where
         * listeners would have an address and expect it to work right
         * away.
         */
        notify = (link_state == LINK_STATE_UP &&
            ifp->if_link_state == LINK_STATE_UNKNOWN);
        ifp->if_link_state = link_state;
        /* The following routines may sleep so release the spin mutex */
        IF_LINK_STATE_CHANGE_UNLOCK(ifp);

        KERNEL_LOCK_UNLESS_NET_MPSAFE();
        if (notify) {
                DOMAIN_FOREACH(dp) {
                        if (dp->dom_if_link_state_change != NULL)
                                dp->dom_if_link_state_change(ifp,
                                    LINK_STATE_DOWN);
                }
        }

        /* Notify that the link state has changed. */
        rt_ifmsg(ifp);

        simplehook_dohooks(ifp->if_linkstate_hooks);

        DOMAIN_FOREACH(dp) {
                if (dp->dom_if_link_state_change != NULL)
                        dp->dom_if_link_state_change(ifp, link_state);
        }
        KERNEL_UNLOCK_UNLESS_NET_MPSAFE();
        splx(s);
}

/*
 * Process the interface link state change queue.
 */
static void
if_link_state_change_work(struct work *work, void *arg)
{
        struct ifnet *ifp = container_of(work, struct ifnet, if_link_work);
        uint8_t state;

        KERNEL_LOCK_UNLESS_NET_MPSAFE();
        const int s = splnet();

        /*
         * Process a single link state in order of precedence:
         *     DOWN, UNKNOWN and finally UP.
         * If locked, abort.
         */
        IF_LINK_STATE_CHANGE_LOCK(ifp);
        ifp->if_link_queue &= ~LINK_QUEUE_SCHEDULED;
        if (ifp->if_link_queue & LINK_QUEUE_LOCKED)
                goto out;
        else if (ifp->if_link_queue & LINK_QUEUE_DOWN) {
                ifp->if_link_queue &= ~LINK_QUEUE_DOWN;
                state = LINK_STATE_DOWN;
        } else if (ifp->if_link_queue & LINK_QUEUE_UNKNOWN) {
                ifp->if_link_queue &= ~LINK_QUEUE_UNKNOWN;
                state = LINK_STATE_UNKNOWN;
        } else if (ifp->if_link_queue & LINK_QUEUE_UP) {
                ifp->if_link_queue &= ~LINK_QUEUE_UP;
                state = LINK_STATE_UP;
        } else {
#ifdef DEBUG
                printf("%s: unknown link queue %u\n",
                    ifp->if_xname, ifp->if_link_queue);
#endif
                goto out;
        }
        IF_LINK_STATE_CHANGE_UNLOCK(ifp);

        IFNET_LOCK(ifp);
        if_link_state_change_process(ifp, state);
        IFNET_UNLOCK(ifp);

        /* If there is a link state change to come, schedule it. */
        IF_LINK_STATE_CHANGE_LOCK(ifp);
        if (ifp->if_link_queue == 0 ||
            (ifp->if_link_queue & (LINK_QUEUE_LOCKED | LINK_QUEUE_SCHEDULED)))
                goto out;

        ifp->if_link_queue |= LINK_QUEUE_SCHEDULED;
        workqueue_enqueue(ifnet_link_state_wq, &ifp->if_link_work, NULL);

out:
        IF_LINK_STATE_CHANGE_UNLOCK(ifp);
        splx(s);
        KERNEL_UNLOCK_UNLESS_NET_MPSAFE();
}

void *
if_linkstate_change_establish(struct ifnet *ifp, void (*fn)(void *), void *arg)
{
        khook_t *hk;

        hk = simplehook_establish(ifp->if_linkstate_hooks, fn, arg);

        return (void *)hk;
}

void
if_linkstate_change_disestablish(struct ifnet *ifp, void *vhook,
    kmutex_t *lock)
{

        simplehook_disestablish(ifp->if_linkstate_hooks, vhook, lock);
}

/*
 * Used to mark addresses on an interface as DETATCHED or TENTATIVE
 * and thus start Duplicate Address Detection without changing the
 * real link state.
 */
void
if_domain_link_state_change(struct ifnet *ifp, int link_state)
{
        struct domain *dp;

        const int s = splnet();
        KERNEL_LOCK_UNLESS_NET_MPSAFE();

        DOMAIN_FOREACH(dp) {
                if (dp->dom_if_link_state_change != NULL)
                        dp->dom_if_link_state_change(ifp, link_state);
        }

        splx(s);
        KERNEL_UNLOCK_UNLESS_NET_MPSAFE();
}

/*
 * Default action when installing a local route on a point-to-point
 * interface.
 */
void
p2p_rtrequest(int req, struct rtentry *rt,
    __unused const struct rt_addrinfo *info)
{
        struct ifnet *ifp = rt->rt_ifp;
        struct ifaddr *ifa, *lo0ifa;
        int s = pserialize_read_enter();

        switch (req) {
        case RTM_ADD:
                if ((rt->rt_flags & RTF_LOCAL) == 0)
                        break;

                rt->rt_ifp = lo0ifp;

                if (ISSET(info->rti_flags, RTF_DONTCHANGEIFA))
                        break;

                IFADDR_READER_FOREACH(ifa, ifp) {
                        if (equal(rt_getkey(rt), ifa->ifa_addr))
                                break;
                }
                if (ifa == NULL)
                        break;

                /*
                 * Ensure lo0 has an address of the same family.
                 */
                IFADDR_READER_FOREACH(lo0ifa, lo0ifp) {
                        if (lo0ifa->ifa_addr->sa_family ==
                            ifa->ifa_addr->sa_family)
                                break;
                }
                if (lo0ifa == NULL)
                        break;

                /*
                 * Make sure to set rt->rt_ifa to the interface
                 * address we are using, otherwise we will have trouble
                 * with source address selection.
                 */
                if (ifa != rt->rt_ifa)
                        rt_replace_ifa(rt, ifa);
                break;
        case RTM_DELETE:
        default:
                break;
        }
        pserialize_read_exit(s);
}

static void
_if_down(struct ifnet *ifp)
{
        struct ifaddr *ifa;
        struct domain *dp;
        struct psref psref;

        ifp->if_flags &= ~IFF_UP;
        nanotime(&ifp->if_lastchange);

        const int bound = curlwp_bind();
        int s = pserialize_read_enter();
        IFADDR_READER_FOREACH(ifa, ifp) {
                ifa_acquire(ifa, &psref);
                pserialize_read_exit(s);

                pfctlinput(PRC_IFDOWN, ifa->ifa_addr);

                s = pserialize_read_enter();
                ifa_release(ifa, &psref);
        }
        pserialize_read_exit(s);
        curlwp_bindx(bound);

        IFQ_PURGE(&ifp->if_snd);
#if NCARP > 0
        if (ifp->if_carp)
                carp_carpdev_state(ifp);
#endif
        rt_ifmsg(ifp);
        DOMAIN_FOREACH(dp) {
                if (dp->dom_if_down)
                        dp->dom_if_down(ifp);
        }
}

static void
if_down_deactivated(struct ifnet *ifp)
{

        KASSERT(if_is_deactivated(ifp));
        _if_down(ifp);
}

void
if_down_locked(struct ifnet *ifp)
{

        KASSERT(IFNET_LOCKED(ifp));
        _if_down(ifp);
}

/*
 * Mark an interface down and notify protocols of
 * the transition.
 * NOTE: must be called at splsoftnet or equivalent.
 */
void
if_down(struct ifnet *ifp)
{

        IFNET_LOCK(ifp);
        if_down_locked(ifp);
        IFNET_UNLOCK(ifp);
}

/*
 * Must be called with holding if_ioctl_lock.
 */
static void
if_up_locked(struct ifnet *ifp)
{
#ifdef notyet
        struct ifaddr *ifa;
#endif
        struct domain *dp;

        KASSERT(IFNET_LOCKED(ifp));

        KASSERT(!if_is_deactivated(ifp));
        ifp->if_flags |= IFF_UP;
        nanotime(&ifp->if_lastchange);
#ifdef notyet
        /* this has no effect on IP, and will kill all ISO connections XXX */
        IFADDR_READER_FOREACH(ifa, ifp)
                pfctlinput(PRC_IFUP, ifa->ifa_addr);
#endif
#if NCARP > 0
        if (ifp->if_carp)
                carp_carpdev_state(ifp);
#endif
        rt_ifmsg(ifp);
        DOMAIN_FOREACH(dp) {
                if (dp->dom_if_up)
                        dp->dom_if_up(ifp);
        }
}

/*
 * Handle interface slowtimo timer routine.  Called
 * from softclock, we decrement timer (if set) and
 * call the appropriate interface routine on expiration.
 */
static bool
if_slowtimo_countdown(struct ifnet *ifp)
{
        bool fire = false;
        const int s = splnet();

        KERNEL_LOCK(1, NULL);
        if (ifp->if_timer != 0 && --ifp->if_timer == 0)
                fire = true;
        KERNEL_UNLOCK_ONE(NULL);
        splx(s);

        return fire;
}

static void
if_slowtimo_intr(void *arg)
{
        struct ifnet *ifp = arg;
        struct if_slowtimo_data *isd = ifp->if_slowtimo_data;

        mutex_enter(&isd->isd_lock);
        if (!isd->isd_dying) {
                if (isd->isd_trigger || if_slowtimo_countdown(ifp)) {
                        if (!isd->isd_queued) {
                                isd->isd_queued = true;
                                workqueue_enqueue(if_slowtimo_wq,
                                    &isd->isd_work, NULL);
                        }
                } else
                        callout_schedule(&isd->isd_ch, hz / IFNET_SLOWHZ);
        }
        mutex_exit(&isd->isd_lock);
}

static void
if_slowtimo_work(struct work *work, void *arg)
{
        struct if_slowtimo_data *isd =
            container_of(work, struct if_slowtimo_data, isd_work);
        struct ifnet *ifp = isd->isd_ifp;
        const int s = splnet();

        KERNEL_LOCK(1, NULL);
        (*ifp->if_slowtimo)(ifp);
        KERNEL_UNLOCK_ONE(NULL);
        splx(s);

        mutex_enter(&isd->isd_lock);
        if (isd->isd_trigger) {
                isd->isd_trigger = false;
                printf("%s: watchdog triggered\n", ifp->if_xname);
        }
        isd->isd_queued = false;
        if (!isd->isd_dying)
                callout_schedule(&isd->isd_ch, hz / IFNET_SLOWHZ);
        mutex_exit(&isd->isd_lock);
}

static int
sysctl_if_watchdog(SYSCTLFN_ARGS)
{
        struct sysctlnode node = *rnode;
        struct ifnet *ifp = node.sysctl_data;
        struct if_slowtimo_data *isd = ifp->if_slowtimo_data;
        int arg = 0;
        int error;

        node.sysctl_data = &arg;
        error = sysctl_lookup(SYSCTLFN_CALL(&node));
        if (error || newp == NULL)
                return error;
        if (arg) {
                mutex_enter(&isd->isd_lock);
                KASSERT(!isd->isd_dying);
                isd->isd_trigger = true;
                callout_schedule(&isd->isd_ch, 0);
                mutex_exit(&isd->isd_lock);
        }

        return 0;
}

static void
sysctl_watchdog_setup(struct ifnet *ifp)
{
        struct sysctllog **clog = &ifp->if_sysctl_log;
        const struct sysctlnode *rnode;

        if (sysctl_createv(clog, 0, NULL, &rnode,
                CTLFLAG_PERMANENT, CTLTYPE_NODE, "interfaces",
                SYSCTL_DESCR("Per-interface controls"),
                NULL, 0, NULL, 0,
                CTL_NET, CTL_CREATE, CTL_EOL) != 0)
                goto bad;
        if (sysctl_createv(clog, 0, &rnode, &rnode,
                CTLFLAG_PERMANENT, CTLTYPE_NODE, ifp->if_xname,
                SYSCTL_DESCR("Interface controls"),
                NULL, 0, NULL, 0,
                CTL_CREATE, CTL_EOL) != 0)
                goto bad;
        if (sysctl_createv(clog, 0, &rnode, &rnode,
                CTLFLAG_PERMANENT, CTLTYPE_NODE, "watchdog",
                SYSCTL_DESCR("Interface watchdog controls"),
                NULL, 0, NULL, 0,
                CTL_CREATE, CTL_EOL) != 0)
                goto bad;
        if (sysctl_createv(clog, 0, &rnode, NULL,
                CTLFLAG_PERMANENT|CTLFLAG_READWRITE, CTLTYPE_INT, "trigger",
                SYSCTL_DESCR("Trigger watchdog timeout"),
                sysctl_if_watchdog, 0, (int *)ifp, 0,
                CTL_CREATE, CTL_EOL) != 0)
                goto bad;

        return;

bad:
        printf("%s: could not attach sysctl watchdog nodes\n", ifp->if_xname);
}

/*
 * Mark an interface up and notify protocols of
 * the transition.
 * NOTE: must be called at splsoftnet or equivalent.
 */
void
if_up(struct ifnet *ifp)
{

        IFNET_LOCK(ifp);
        if_up_locked(ifp);
        IFNET_UNLOCK(ifp);
}

/*
 * 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_locked(struct ifnet *ifp, int pswitch)
{
        int pcount, ret = 0;
        u_short nflags;

        KASSERT(IFNET_LOCKED(ifp));

        pcount = ifp->if_pcount;
        if (pswitch) {
                /*
                 * Allow the device to be "placed" into promiscuous
                 * mode even if it is not configured up.  It will
                 * consult IFF_PROMISC when it is brought up.
                 */
                if (ifp->if_pcount++ != 0)
                        goto out;
                nflags = ifp->if_flags | IFF_PROMISC;
        } else {
                if (--ifp->if_pcount > 0)
                        goto out;
                nflags = ifp->if_flags & ~IFF_PROMISC;
        }
        ret = if_flags_set(ifp, nflags);
        /* Restore interface state if not successful. */
        if (ret != 0)
                ifp->if_pcount = pcount;

out:
        return ret;
}

int
ifpromisc(struct ifnet *ifp, int pswitch)
{
        int e;

        IFNET_LOCK(ifp);
        e = ifpromisc_locked(ifp, pswitch);
        IFNET_UNLOCK(ifp);

        return e;
}

/*
 * if_ioctl(ifp, cmd, data)
 *
 *      Apply an ioctl command to the interface.  Returns 0 on success,
 *      nonzero errno(3) number on failure.
 *
 *      For SIOCADDMULTI/SIOCDELMULTI, caller need not hold locks -- it
 *      is the driver's responsibility to take any internal locks.
 *      (Kernel logic should generally invoke these only through
 *      if_mcast_op.)
 *
 *      For all other ioctls, caller must hold ifp->if_ioctl_lock,
 *      a.k.a. IFNET_LOCK.  May sleep.
 */
int
if_ioctl(struct ifnet *ifp, u_long cmd, void *data)
{

        switch (cmd) {
        case SIOCADDMULTI:
        case SIOCDELMULTI:
                break;
        default:
                KASSERTMSG(IFNET_LOCKED(ifp), "%s", ifp->if_xname);
        }

        return (*ifp->if_ioctl)(ifp, cmd, data);
}

/*
 * if_init(ifp)
 *
 *      Prepare the hardware underlying ifp to process packets
 *      according to its current configuration.  Returns 0 on success,
 *      nonzero errno(3) number on failure.
 *
 *      May sleep.  Caller must hold ifp->if_ioctl_lock, a.k.a
 *      IFNET_LOCK.
 */
int
if_init(struct ifnet *ifp)
{

        KASSERTMSG(IFNET_LOCKED(ifp), "%s", ifp->if_xname);

        return (*ifp->if_init)(ifp);
}

/*
 * if_stop(ifp, disable)
 *
 *      Stop the hardware underlying ifp from processing packets.
 *
 *      If disable is true, ... XXX(?)
 *
 *      May sleep.  Caller must hold ifp->if_ioctl_lock, a.k.a
 *      IFNET_LOCK.
 */
void
if_stop(struct ifnet *ifp, int disable)
{

        KASSERTMSG(IFNET_LOCKED(ifp), "%s", ifp->if_xname);

        (*ifp->if_stop)(ifp, disable);
}

/*
 * Map interface name to
 * interface structure pointer.
 */
struct ifnet *
ifunit(const char *name)
{
        struct ifnet *ifp;
        const char *cp = name;
        u_int unit = 0;
        u_int i;

        /*
         * If the entire name is a number, treat it as an ifindex.
         */
        for (i = 0; i < IFNAMSIZ && *cp >= '0' && *cp <= '9'; i++, cp++)
                unit = unit * 10 + (*cp - '0');

        /*
         * If the number took all of the name, then it's a valid ifindex.
         */
        if (i == IFNAMSIZ || (cp != name && *cp == '\0'))
                return if_byindex(unit);

        ifp = NULL;
        const int s = pserialize_read_enter();
        IFNET_READER_FOREACH(ifp) {
                if (if_is_deactivated(ifp))
                        continue;
                if (strcmp(ifp->if_xname, name) == 0)
                        goto out;
        }
out:
        pserialize_read_exit(s);
        return ifp;
}

/*
 * Get a reference of an ifnet object by an interface name.
 * The returned reference is protected by psref(9). The caller
 * must release a returned reference by if_put after use.
 */
struct ifnet *
if_get(const char *name, struct psref *psref)
{
        struct ifnet *ifp;
        const char *cp = name;
        u_int unit = 0;
        u_int i;

        /*
         * If the entire name is a number, treat it as an ifindex.
         */
        for (i = 0; i < IFNAMSIZ && *cp >= '0' && *cp <= '9'; i++, cp++)
                unit = unit * 10 + (*cp - '0');

        /*
         * If the number took all of the name, then it's a valid ifindex.
         */
        if (i == IFNAMSIZ || (cp != name && *cp == '\0'))
                return if_get_byindex(unit, psref);

        ifp = NULL;
        const int s = pserialize_read_enter();
        IFNET_READER_FOREACH(ifp) {
                if (if_is_deactivated(ifp))
                        continue;
                if (strcmp(ifp->if_xname, name) == 0) {
                        PSREF_DEBUG_FILL_RETURN_ADDRESS(psref);
                        psref_acquire(psref, &ifp->if_psref,
                            ifnet_psref_class);
                        goto out;
                }
        }
out:
        pserialize_read_exit(s);
        return ifp;
}

/*
 * Release a reference of an ifnet object given by if_get, if_get_byindex
 * or if_get_bylla.
 */
void
if_put(const struct ifnet *ifp, struct psref *psref)
{

        if (ifp == NULL)
                return;

        psref_release(psref, &ifp->if_psref, ifnet_psref_class);
}

/*
 * Return ifp having idx. Return NULL if not found.  Normally if_byindex
 * should be used.
 */
ifnet_t *
_if_byindex(u_int idx)
{

        return (__predict_true(idx < if_indexlim)) ? ifindex2ifnet[idx] : NULL;
}

/*
 * Return ifp having idx. Return NULL if not found or the found ifp is
 * already deactivated.
 */
ifnet_t *
if_byindex(u_int idx)
{
        ifnet_t *ifp;

        ifp = _if_byindex(idx);
        if (ifp != NULL && if_is_deactivated(ifp))
                ifp = NULL;
        return ifp;
}

/*
 * Get a reference of an ifnet object by an interface index.
 * The returned reference is protected by psref(9). The caller
 * must release a returned reference by if_put after use.
 */
ifnet_t *
if_get_byindex(u_int idx, struct psref *psref)
{
        ifnet_t *ifp;

        const int s = pserialize_read_enter();
        ifp = if_byindex(idx);
        if (__predict_true(ifp != NULL)) {
                PSREF_DEBUG_FILL_RETURN_ADDRESS(psref);
                psref_acquire(psref, &ifp->if_psref, ifnet_psref_class);
        }
        pserialize_read_exit(s);

        return ifp;
}

ifnet_t *
if_get_bylla(const void *lla, unsigned char lla_len, struct psref *psref)
{
        ifnet_t *ifp;

        const int s = pserialize_read_enter();
        IFNET_READER_FOREACH(ifp) {
                if (if_is_deactivated(ifp))
                        continue;
                if (ifp->if_addrlen != lla_len)
                        continue;
                if (memcmp(lla, CLLADDR(ifp->if_sadl), lla_len) == 0) {
                        psref_acquire(psref, &ifp->if_psref,
                            ifnet_psref_class);
                        break;
                }
        }
        pserialize_read_exit(s);

        return ifp;
}

/*
 * Note that it's safe only if the passed ifp is guaranteed to not be freed,
 * for example using pserialize or the ifp is already held or some other
 * object is held which guarantes the ifp to not be freed indirectly.
 */
void
if_acquire(struct ifnet *ifp, struct psref *psref)
{

        KASSERT(ifp->if_index != 0);
        psref_acquire(psref, &ifp->if_psref, ifnet_psref_class);
}

bool
if_held(struct ifnet *ifp)
{

        return psref_held(&ifp->if_psref, ifnet_psref_class);
}

/*
 * Some tunnel interfaces can nest, e.g. IPv4 over IPv4 gif(4) tunnel over
 * IPv4. Check the tunnel nesting count.
 * Return > 0, if tunnel nesting count is more than limit.
 * Return 0, if tunnel nesting count is equal or less than limit.
 */
int
if_tunnel_check_nesting(struct ifnet *ifp, struct mbuf *m, int limit)
{
        struct m_tag *mtag;
        int *count;

        mtag = m_tag_find(m, PACKET_TAG_TUNNEL_INFO);
        if (mtag != NULL) {
                count = (int *)(mtag + 1);
                if (++(*count) > limit) {
                        log(LOG_NOTICE,
                            "%s: recursively called too many times(%d)\n",
                            ifp->if_xname, *count);
                        return EIO;
                }
        } else {
                mtag = m_tag_get(PACKET_TAG_TUNNEL_INFO, sizeof(*count),
                    M_NOWAIT);
                if (mtag != NULL) {
                        m_tag_prepend(m, mtag);
                        count = (int *)(mtag + 1);
                        *count = 0;
                } else {
                        log(LOG_DEBUG, "%s: m_tag_get() failed, "
                            "recursion calls are not prevented.\n",
                            ifp->if_xname);
                }
        }

        return 0;
}

static void
if_tunnel_ro_init_pc(void *p, void *arg __unused, struct cpu_info *ci __unused)
{
        struct tunnel_ro *tro = p;

        tro->tr_ro = kmem_zalloc(sizeof(*tro->tr_ro), KM_SLEEP);
        tro->tr_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_NONE);
}

static void
if_tunnel_ro_fini_pc(void *p, void *arg __unused, struct cpu_info *ci __unused)
{
        struct tunnel_ro *tro = p;

        rtcache_free(tro->tr_ro);
        kmem_free(tro->tr_ro, sizeof(*tro->tr_ro));

        mutex_obj_free(tro->tr_lock);
}

percpu_t *
if_tunnel_alloc_ro_percpu(void)
{

        return percpu_create(sizeof(struct tunnel_ro),
            if_tunnel_ro_init_pc, if_tunnel_ro_fini_pc, NULL);
}

void
if_tunnel_free_ro_percpu(percpu_t *ro_percpu)
{

        percpu_free(ro_percpu, sizeof(struct tunnel_ro));
}


static void
if_tunnel_rtcache_free_pc(void *p, void *arg __unused,
    struct cpu_info *ci __unused)
{
        struct tunnel_ro *tro = p;

        mutex_enter(tro->tr_lock);
        rtcache_free(tro->tr_ro);
        mutex_exit(tro->tr_lock);
}

void if_tunnel_ro_percpu_rtcache_free(percpu_t *ro_percpu)
{

        percpu_foreach(ro_percpu, if_tunnel_rtcache_free_pc, NULL);
}

void
if_export_if_data(ifnet_t * const ifp, struct if_data *ifi, bool zero_stats)
{

        /* Collect the volatile stats first; this zeros *ifi. */
        if_stats_to_if_data(ifp, ifi, zero_stats);

        ifi->ifi_type = ifp->if_type;
        ifi->ifi_addrlen = ifp->if_addrlen;
        ifi->ifi_hdrlen = ifp->if_hdrlen;
        ifi->ifi_link_state = ifp->if_link_state;
        ifi->ifi_mtu = ifp->if_mtu;
        ifi->ifi_metric = ifp->if_metric;
        ifi->ifi_baudrate = ifp->if_baudrate;
        ifi->ifi_lastchange = ifp->if_lastchange;
}

/* common */
int
ifioctl_common(struct ifnet *ifp, u_long cmd, void *data)
{
        struct ifreq *ifr;
        struct ifcapreq *ifcr;
        struct ifdatareq *ifdr;
        unsigned short flags;
        char *descr;
        int error;

        switch (cmd) {
        case SIOCSIFCAP:
                ifcr = data;
                if ((ifcr->ifcr_capenable & ~ifp->if_capabilities) != 0)
                        return EINVAL;

                if (ifcr->ifcr_capenable == ifp->if_capenable)
                        return 0;

                ifp->if_capenable = ifcr->ifcr_capenable;

                /* Pre-compute the checksum flags mask. */
                ifp->if_csum_flags_tx = 0;
                ifp->if_csum_flags_rx = 0;
                if (ifp->if_capenable & IFCAP_CSUM_IPv4_Tx)
                        ifp->if_csum_flags_tx |= M_CSUM_IPv4;
                if (ifp->if_capenable & IFCAP_CSUM_IPv4_Rx)
                        ifp->if_csum_flags_rx |= M_CSUM_IPv4;

                if (ifp->if_capenable & IFCAP_CSUM_TCPv4_Tx)
                        ifp->if_csum_flags_tx |= M_CSUM_TCPv4;
                if (ifp->if_capenable & IFCAP_CSUM_TCPv4_Rx)
                        ifp->if_csum_flags_rx |= M_CSUM_TCPv4;

                if (ifp->if_capenable & IFCAP_CSUM_UDPv4_Tx)
                        ifp->if_csum_flags_tx |= M_CSUM_UDPv4;
                if (ifp->if_capenable & IFCAP_CSUM_UDPv4_Rx)
                        ifp->if_csum_flags_rx |= M_CSUM_UDPv4;

                if (ifp->if_capenable & IFCAP_CSUM_TCPv6_Tx)
                        ifp->if_csum_flags_tx |= M_CSUM_TCPv6;
                if (ifp->if_capenable & IFCAP_CSUM_TCPv6_Rx)
                        ifp->if_csum_flags_rx |= M_CSUM_TCPv6;

                if (ifp->if_capenable & IFCAP_CSUM_UDPv6_Tx)
                        ifp->if_csum_flags_tx |= M_CSUM_UDPv6;
                if (ifp->if_capenable & IFCAP_CSUM_UDPv6_Rx)
                        ifp->if_csum_flags_rx |= M_CSUM_UDPv6;

                if (ifp->if_capenable & IFCAP_TSOv4)
                        ifp->if_csum_flags_tx |= M_CSUM_TSOv4;
                if (ifp->if_capenable & IFCAP_TSOv6)
                        ifp->if_csum_flags_tx |= M_CSUM_TSOv6;

#if NBRIDGE > 0
                if (ifp->if_bridge != NULL)
                        bridge_calc_csum_flags(ifp->if_bridge);
#endif

                if (ifp->if_flags & IFF_UP)
                        return ENETRESET;
                return 0;
        case SIOCSIFFLAGS:
                ifr = data;
                /*
                 * If if_is_mpsafe(ifp), KERNEL_LOCK isn't held here, but if_up
                 * and if_down aren't MP-safe yet, so we must hold the lock.
                 */
                KERNEL_LOCK_IF_IFP_MPSAFE(ifp);
                if (ifp->if_flags & IFF_UP && (ifr->ifr_flags & IFF_UP) == 0) {
                        const int s = splsoftnet();
                        if_down_locked(ifp);
                        splx(s);
                }
                if (ifr->ifr_flags & IFF_UP && (ifp->if_flags & IFF_UP) == 0) {
                        const int s = splsoftnet();
                        if_up_locked(ifp);
                        splx(s);
                }
                KERNEL_UNLOCK_IF_IFP_MPSAFE(ifp);
                flags = (ifp->if_flags & IFF_CANTCHANGE) |
                    (ifr->ifr_flags &~ IFF_CANTCHANGE);
                if (ifp->if_flags != flags) {
                        ifp->if_flags = flags;
                        /* Notify that the flags have changed. */
                        rt_ifmsg(ifp);
                }
                break;
        case SIOCGIFFLAGS:
                ifr = data;
                ifr->ifr_flags = ifp->if_flags;
                break;

        case SIOCGIFMETRIC:
                ifr = data;
                ifr->ifr_metric = ifp->if_metric;
                break;

        case SIOCGIFMTU:
                ifr = data;
                ifr->ifr_mtu = ifp->if_mtu;
                break;

        case SIOCGIFDLT:
                ifr = data;
                ifr->ifr_dlt = ifp->if_dlt;
                break;

        case SIOCGIFCAP:
                ifcr = data;
                ifcr->ifcr_capabilities = ifp->if_capabilities;
                ifcr->ifcr_capenable = ifp->if_capenable;
                break;

        case SIOCSIFMETRIC:
                ifr = data;
                ifp->if_metric = ifr->ifr_metric;
                break;

        case SIOCGIFDATA:
                ifdr = data;
                if_export_if_data(ifp, &ifdr->ifdr_data, false);
                break;

        case SIOCGIFINDEX:
                ifr = data;
                ifr->ifr_index = ifp->if_index;
                break;

        case SIOCZIFDATA:
                ifdr = data;
                if_export_if_data(ifp, &ifdr->ifdr_data, true);
                getnanotime(&ifp->if_lastchange);
                break;
        case SIOCSIFMTU:
                ifr = data;
                if (ifp->if_mtu == ifr->ifr_mtu)
                        break;
                ifp->if_mtu = ifr->ifr_mtu;
                return ENETRESET;
        case SIOCSIFDESCR:
                error = kauth_authorize_network(kauth_cred_get(),
                    KAUTH_NETWORK_INTERFACE,
                    KAUTH_REQ_NETWORK_INTERFACE_SETPRIV, ifp, KAUTH_ARG(cmd),
                    NULL);
                if (error)
                        return error;

                ifr = data;

                if (ifr->ifr_buflen > IFDESCRSIZE)
                        return ENAMETOOLONG;

                if (ifr->ifr_buf == NULL || ifr->ifr_buflen == 0) {
                        /* unset description */
                        descr = NULL;
                } else {
                        descr = kmem_zalloc(IFDESCRSIZE, KM_SLEEP);
                        /*
                         * copy (IFDESCRSIZE - 1) bytes to ensure
                         * terminating nul
                         */
                        error = copyin(ifr->ifr_buf, descr, IFDESCRSIZE - 1);
                        if (error) {
                                kmem_free(descr, IFDESCRSIZE);
                                return error;
                        }
                }

                if (ifp->if_description != NULL)
                        kmem_free(ifp->if_description, IFDESCRSIZE);

                ifp->if_description = descr;
                break;

        case SIOCGIFDESCR:
                ifr = data;
                descr = ifp->if_description;

                if (descr == NULL)
                        return ENOMSG;

                if (ifr->ifr_buflen < IFDESCRSIZE)
                        return EINVAL;

                error = copyout(descr, ifr->ifr_buf, IFDESCRSIZE);
                if (error)
                        return error;
                break;

        default:
                return ENOTTY;
        }
        return 0;
}

int
ifaddrpref_ioctl(struct socket *so, u_long cmd, void *data, struct ifnet *ifp)
{
        struct if_addrprefreq *ifap = (struct if_addrprefreq *)data;
        struct ifaddr *ifa;
        const struct sockaddr *any, *sa;
        union {
                struct sockaddr sa;
                struct sockaddr_storage ss;
        } u, v;
        int s, error = 0;

        switch (cmd) {
        case SIOCSIFADDRPREF:
                error = kauth_authorize_network(kauth_cred_get(),
                    KAUTH_NETWORK_INTERFACE,
                    KAUTH_REQ_NETWORK_INTERFACE_SETPRIV, ifp, KAUTH_ARG(cmd),
                    NULL);
                if (error)
                        return error;
                break;
        case SIOCGIFADDRPREF:
                break;
        default:
                return EOPNOTSUPP;
        }

        /* sanity checks */
        if (data == NULL || ifp == NULL) {
                panic("invalid argument to %s", __func__);
                /*NOTREACHED*/
        }

        /* address must be specified on ADD and DELETE */
        sa = sstocsa(&ifap->ifap_addr);
        if (sa->sa_family != sofamily(so))
                return EINVAL;
        if ((any = sockaddr_any(sa)) == NULL || sa->sa_len != any->sa_len)
                return EINVAL;

        sockaddr_externalize(&v.sa, sizeof(v.ss), sa);

        s = pserialize_read_enter();
        IFADDR_READER_FOREACH(ifa, ifp) {
                if (ifa->ifa_addr->sa_family != sa->sa_family)
                        continue;
                sockaddr_externalize(&u.sa, sizeof(u.ss), ifa->ifa_addr);
                if (sockaddr_cmp(&u.sa, &v.sa) == 0)
                        break;
        }
        if (ifa == NULL) {
                error = EADDRNOTAVAIL;
                goto out;
        }

        switch (cmd) {
        case SIOCSIFADDRPREF:
                ifa->ifa_preference = ifap->ifap_preference;
                goto out;
        case SIOCGIFADDRPREF:
                /* fill in the if_laddrreq structure */
                (void)sockaddr_copy(sstosa(&ifap->ifap_addr),
                    sizeof(ifap->ifap_addr), ifa->ifa_addr);
                ifap->ifap_preference = ifa->ifa_preference;
                goto out;
        default:
                error = EOPNOTSUPP;
        }
out:
        pserialize_read_exit(s);
        return error;
}

/*
 * Interface ioctls.
 */
static int
doifioctl(struct socket *so, u_long cmd, void *data, struct lwp *l)
{
        struct ifnet *ifp;
        struct ifreq *ifr;
        int error = 0;
        u_long ocmd = cmd;
        u_short oif_flags;
        struct ifreq ifrb;
        struct oifreq *oifr = NULL;
        int r;
        struct psref psref;
        bool do_if43_post = false;
        bool do_ifm80_post = false;

        switch (cmd) {
        case SIOCGIFCONF:
                return ifconf(cmd, data);
        case SIOCINITIFADDR:
                return EPERM;
        default:
                MODULE_HOOK_CALL(uipc_syscalls_40_hook, (cmd, data), enosys(),
                    error);
                if (error != ENOSYS)
                        return error;
                MODULE_HOOK_CALL(uipc_syscalls_50_hook, (l, cmd, data),
                    enosys(), error);
                if (error != ENOSYS)
                        return error;
                error = 0;
                break;
        }

        ifr = data;
        /* Pre-conversion */
        MODULE_HOOK_CALL(if_cvtcmd_43_hook, (&cmd, ocmd), enosys(), error);
        if (cmd != ocmd) {
                oifr = data;
                data = ifr = &ifrb;
                IFREQO2N_43(oifr, ifr);
                do_if43_post = true;
        }
        MODULE_HOOK_CALL(ifmedia_80_pre_hook, (ifr, &cmd, &do_ifm80_post),
            enosys(), error);

        switch (cmd) {
        case SIOCIFCREATE:
        case SIOCIFDESTROY: {
                const int bound = curlwp_bind();
                if (l != NULL) {
                        ifp = if_get(ifr->ifr_name, &psref);
                        error = kauth_authorize_network(l->l_cred,
                            KAUTH_NETWORK_INTERFACE,
                            KAUTH_REQ_NETWORK_INTERFACE_SETPRIV, ifp,
                            KAUTH_ARG(cmd), NULL);
                        if (ifp != NULL)
                                if_put(ifp, &psref);
                        if (error != 0) {
                                curlwp_bindx(bound);
                                return error;
                        }
                }
                KERNEL_LOCK_UNLESS_NET_MPSAFE();
                mutex_enter(&if_clone_mtx);
                r = (cmd == SIOCIFCREATE) ?
                        if_clone_create(ifr->ifr_name) :
                        if_clone_destroy(ifr->ifr_name);
                mutex_exit(&if_clone_mtx);
                KERNEL_UNLOCK_UNLESS_NET_MPSAFE();
                curlwp_bindx(bound);
                return r;
            }
        case SIOCIFGCLONERS: {
                struct if_clonereq *req = (struct if_clonereq *)data;
                return if_clone_list(req->ifcr_count, req->ifcr_buffer,
                    &req->ifcr_total);
            }
        }

        if ((cmd & IOC_IN) == 0 || IOCPARM_LEN(cmd) < sizeof(ifr->ifr_name))
                return EINVAL;

        const int bound = curlwp_bind();
        ifp = if_get(ifr->ifr_name, &psref);
        if (ifp == NULL) {
                curlwp_bindx(bound);
                return ENXIO;
        }

        switch (cmd) {
        case SIOCALIFADDR:
        case SIOCDLIFADDR:
        case SIOCSIFADDRPREF:
        case SIOCSIFFLAGS:
        case SIOCSIFCAP:
        case SIOCSIFMETRIC:
        case SIOCZIFDATA:
        case SIOCSIFMTU:
        case SIOCSIFPHYADDR:
        case SIOCDIFPHYADDR:
#ifdef INET6
        case SIOCSIFPHYADDR_IN6:
#endif
        case SIOCSLIFPHYADDR:
        case SIOCADDMULTI:
        case SIOCDELMULTI:
        case SIOCSETHERCAP:
        case SIOCSIFMEDIA:
        case SIOCSDRVSPEC:
        case SIOCG80211:
        case SIOCS80211:
        case SIOCS80211NWID:
        case SIOCS80211NWKEY:
        case SIOCS80211POWER:
        case SIOCS80211BSSID:
        case SIOCS80211CHANNEL:
        case SIOCSLINKSTR:
                if (l != NULL) {
                        error = kauth_authorize_network(l->l_cred,
                            KAUTH_NETWORK_INTERFACE,
                            KAUTH_REQ_NETWORK_INTERFACE_SETPRIV, ifp,
                            KAUTH_ARG(cmd), NULL);
                        if (error != 0)
                                goto out;
                }
        }

        oif_flags = ifp->if_flags;

        KERNEL_LOCK_UNLESS_IFP_MPSAFE(ifp);
        IFNET_LOCK(ifp);

        error = if_ioctl(ifp, cmd, data);
        if (error != ENOTTY)
                ;
        else if (so->so_proto == NULL)
                error = EOPNOTSUPP;
        else {
                KERNEL_LOCK_IF_IFP_MPSAFE(ifp);
                MODULE_HOOK_CALL(if_ifioctl_43_hook,
                             (so, ocmd, cmd, data, l), enosys(), error);
                if (error == ENOSYS)
                        error = (*so->so_proto->pr_usrreqs->pr_ioctl)(so,
                            cmd, data, ifp);
                KERNEL_UNLOCK_IF_IFP_MPSAFE(ifp);
        }

        if (((oif_flags ^ ifp->if_flags) & IFF_UP) != 0) {
                if ((ifp->if_flags & IFF_UP) != 0) {
                        const int s = splsoftnet();
                        if_up_locked(ifp);
                        splx(s);
                }
        }

        /* Post-conversion */
        if (do_ifm80_post && (error == 0))
                MODULE_HOOK_CALL(ifmedia_80_post_hook, (ifr, cmd),
                    enosys(), error);
        if (do_if43_post)
                IFREQN2O_43(oifr, ifr);

        IFNET_UNLOCK(ifp);
        KERNEL_UNLOCK_UNLESS_IFP_MPSAFE(ifp);
out:
        if_put(ifp, &psref);
        curlwp_bindx(bound);
        return error;
}

/*
 * Return interface configuration
 * of system.  List may be used
 * in later ioctl's (above) to get
 * other information.
 *
 * Each record is a struct ifreq.  Before the addition of
 * sockaddr_storage, the API rule was that sockaddr flavors that did
 * not fit would extend beyond the struct ifreq, with the next struct
 * ifreq starting sa_len beyond the struct sockaddr.  Because the
 * union in struct ifreq includes struct sockaddr_storage, every kind
 * of sockaddr must fit.  Thus, there are no longer any overlength
 * records.
 *
 * Records are added to the user buffer if they fit, and ifc_len is
 * adjusted to the length that was written.  Thus, the user is only
 * assured of getting the complete list if ifc_len on return is at
 * least sizeof(struct ifreq) less than it was on entry.
 *
 * If the user buffer pointer is NULL, this routine copies no data and
 * returns the amount of space that would be needed.
 *
 * Invariants:
 * ifrp points to the next part of the user's buffer to be used.  If
 * ifrp != NULL, space holds the number of bytes remaining that we may
 * write at ifrp.  Otherwise, space holds the number of bytes that
 * would have been written had there been adequate space.
 */
/*ARGSUSED*/
static int
ifconf(u_long cmd, void *data)
{
        struct ifconf *ifc = (struct ifconf *)data;
        struct ifnet *ifp;
        struct ifaddr *ifa;
        struct ifreq ifr, *ifrp = NULL;
        int space = 0, error = 0;
        const int sz = (int)sizeof(struct ifreq);
        const bool docopy = ifc->ifc_req != NULL;
        struct psref psref;

        if (docopy) {
                if (ifc->ifc_len < 0)
                        return EINVAL;

                space = ifc->ifc_len;
                ifrp = ifc->ifc_req;
        }
        memset(&ifr, 0, sizeof(ifr));

        const int bound = curlwp_bind();
        int s = pserialize_read_enter();
        IFNET_READER_FOREACH(ifp) {
                psref_acquire(&psref, &ifp->if_psref, ifnet_psref_class);
                pserialize_read_exit(s);

                (void)strncpy(ifr.ifr_name, ifp->if_xname,
                    sizeof(ifr.ifr_name));
                if (ifr.ifr_name[sizeof(ifr.ifr_name) - 1] != '\0') {
                        error = ENAMETOOLONG;
                        goto release_exit;
                }
                if (IFADDR_READER_EMPTY(ifp)) {
                        /* Interface with no addresses - send zero sockaddr. */
                        memset(&ifr.ifr_addr, 0, sizeof(ifr.ifr_addr));
                        if (!docopy) {
                                space += sz;
                                goto next;
                        }
                        if (space >= sz) {
                                error = copyout(&ifr, ifrp, sz);
                                if (error != 0)
                                        goto release_exit;
                                ifrp++;
                                space -= sz;
                        }
                }

                s = pserialize_read_enter();
                IFADDR_READER_FOREACH(ifa, ifp) {
                        struct sockaddr *sa = ifa->ifa_addr;
                        /* all sockaddrs must fit in sockaddr_storage */
                        KASSERT(sa->sa_len <= sizeof(ifr.ifr_ifru));

                        if (!docopy) {
                                space += sz;
                                continue;
                        }
                        memcpy(&ifr.ifr_space, sa, sa->sa_len);
                        pserialize_read_exit(s);

                        if (space >= sz) {
                                error = copyout(&ifr, ifrp, sz);
                                if (error != 0)
                                        goto release_exit;
                                ifrp++; space -= sz;
                        }
                        s = pserialize_read_enter();
                }
                pserialize_read_exit(s);

next:
                s = pserialize_read_enter();
                psref_release(&psref, &ifp->if_psref, ifnet_psref_class);
        }
        pserialize_read_exit(s);
        curlwp_bindx(bound);

        if (docopy) {
                KASSERT(0 <= space && space <= ifc->ifc_len);
                ifc->ifc_len -= space;
        } else {
                KASSERT(space >= 0);
                ifc->ifc_len = space;
        }
        return 0;

release_exit:
        psref_release(&psref, &ifp->if_psref, ifnet_psref_class);
        curlwp_bindx(bound);
        return error;
}

int
ifreq_setaddr(u_long cmd, struct ifreq *ifr, const struct sockaddr *sa)
{
        uint8_t len = sizeof(ifr->ifr_ifru.ifru_space);
        struct ifreq ifrb;
        struct oifreq *oifr = NULL;
        u_long ocmd = cmd;
        int hook;

        MODULE_HOOK_CALL(if_cvtcmd_43_hook, (&cmd, ocmd), enosys(), hook);
        if (hook != ENOSYS) {
                if (cmd != ocmd) {
                        oifr = (struct oifreq *)(void *)ifr;
                        ifr = &ifrb;
                        IFREQO2N_43(oifr, ifr);
                                len = sizeof(oifr->ifr_addr);
                }
        }

        if (len < sa->sa_len)
                return EFBIG;

        memset(&ifr->ifr_addr, 0, len);
        sockaddr_copy(&ifr->ifr_addr, len, sa);

        if (cmd != ocmd)
                IFREQN2O_43(oifr, ifr);
        return 0;
}

/*
 * wrapper function for the drivers which doesn't have if_transmit().
 */
static int
if_transmit(struct ifnet *ifp, struct mbuf *m)
{
        int error;
        size_t pktlen = m->m_pkthdr.len;
        bool mcast = (m->m_flags & M_MCAST) != 0;

        const int s = splnet();

        IFQ_ENQUEUE(&ifp->if_snd, m, error);
        if (error != 0) {
                /* mbuf is already freed */
                goto out;
        }

        net_stat_ref_t nsr = IF_STAT_GETREF(ifp);
        if_statadd_ref(ifp, nsr, if_obytes, pktlen);
        if (mcast)
                if_statinc_ref(ifp, nsr, if_omcasts);
        IF_STAT_PUTREF(ifp);

        if ((ifp->if_flags & IFF_OACTIVE) == 0)
                if_start_lock(ifp);
out:
        splx(s);

        return error;
}

int
if_transmit_lock(struct ifnet *ifp, struct mbuf *m)
{
        int error;

        kmsan_check_mbuf(m);

#ifdef ALTQ
        KERNEL_LOCK(1, NULL);
        if (ALTQ_IS_ENABLED(&ifp->if_snd)) {
                error = if_transmit(ifp, m);
                KERNEL_UNLOCK_ONE(NULL);
        } else {
                KERNEL_UNLOCK_ONE(NULL);
                error = (*ifp->if_transmit)(ifp, m);
                /* mbuf is already freed */
        }
#else /* !ALTQ */
        error = (*ifp->if_transmit)(ifp, m);
        /* mbuf is already freed */
#endif /* !ALTQ */

        return error;
}

/*
 * Queue message on interface, and start output if interface
 * not yet active.
 */
int
ifq_enqueue(struct ifnet *ifp, struct mbuf *m)
{

        return if_transmit_lock(ifp, m);
}

/*
 * Queue message on interface, possibly using a second fast queue
 */
int
ifq_enqueue2(struct ifnet *ifp, struct ifqueue *ifq, struct mbuf *m)
{
        int error = 0;

        if (ifq != NULL
#ifdef ALTQ
            && ALTQ_IS_ENABLED(&ifp->if_snd) == 0
#endif
            ) {
                if (IF_QFULL(ifq)) {
                        IF_DROP(&ifp->if_snd);
                        m_freem(m);
                        if (error == 0)
                                error = ENOBUFS;
                } else
                        IF_ENQUEUE(ifq, m);
        } else
                IFQ_ENQUEUE(&ifp->if_snd, m, error);
        if (error != 0) {
                if_statinc(ifp, if_oerrors);
                return error;
        }
        return 0;
}

int
if_addr_init(ifnet_t *ifp, struct ifaddr *ifa, const bool src)
{
        int rc;

        KASSERT(IFNET_LOCKED(ifp));
        if (ifp->if_initaddr != NULL)
                rc = (*ifp->if_initaddr)(ifp, ifa, src);
        else if (src || (rc = if_ioctl(ifp, SIOCSIFDSTADDR, ifa)) == ENOTTY)
                rc = if_ioctl(ifp, SIOCINITIFADDR, ifa);

        return rc;
}

int
if_do_dad(struct ifnet *ifp)
{
        if ((ifp->if_flags & IFF_LOOPBACK) != 0)
                return 0;

        switch (ifp->if_type) {
        case IFT_FAITH:
                /*
                 * These interfaces do not have the IFF_LOOPBACK flag,
                 * but loop packets back.  We do not have to do DAD on such
                 * interfaces.  We should even omit it, because loop-backed
                 * responses would confuse the DAD procedure.
                 */
                return 0;
        default:
                /*
                 * Our DAD routine requires the interface up and running.
                 * However, some interfaces can be up before the RUNNING
                 * status.  Additionally, users may try to assign addresses
                 * before the interface becomes up (or running).
                 * We simply skip DAD in such a case as a work around.
                 * XXX: we should rather mark "tentative" on such addresses,
                 * and do DAD after the interface becomes ready.
                 */
                if ((ifp->if_flags & (IFF_UP | IFF_RUNNING)) !=
                    (IFF_UP | IFF_RUNNING))
                        return 0;

                return 1;
        }
}

/*
 * if_flags_set(ifp, flags)
 *
 *      Ask ifp to change ifp->if_flags to flags, as if with the
 *      SIOCSIFFLAGS ioctl command.
 *
 *      May sleep.  Caller must hold ifp->if_ioctl_lock, a.k.a
 *      IFNET_LOCK.
 */
int
if_flags_set(ifnet_t *ifp, const u_short flags)
{
        int rc;

        KASSERT(IFNET_LOCKED(ifp));

        if (ifp->if_setflags != NULL)
                rc = (*ifp->if_setflags)(ifp, flags);
        else {
                u_short cantflags, chgdflags;
                struct ifreq ifr;

                chgdflags = ifp->if_flags ^ flags;
                cantflags = chgdflags & IFF_CANTCHANGE;

                if (cantflags != 0)
                        ifp->if_flags ^= cantflags;

                /*
                 * Traditionally, we do not call if_ioctl after
                 * setting/clearing only IFF_PROMISC if the interface
                 * isn't IFF_UP.  Uphold that tradition.
                 */
                if (chgdflags == IFF_PROMISC && (ifp->if_flags & IFF_UP) == 0)
                        return 0;

                memset(&ifr, 0, sizeof(ifr));

                ifr.ifr_flags = flags & ~IFF_CANTCHANGE;
                rc = if_ioctl(ifp, SIOCSIFFLAGS, &ifr);

                if (rc != 0 && cantflags != 0)
                        ifp->if_flags ^= cantflags;
        }

        return rc;
}

/*
 * if_mcast_op(ifp, cmd, sa)
 *
 *      Apply a multicast command, SIOCADDMULTI/SIOCDELMULTI, to the
 *      interface.  Returns 0 on success, nonzero errno(3) number on
 *      failure.
 *
 *      May sleep.
 *
 *      Use this, not if_ioctl, for the multicast commands.
 */
int
if_mcast_op(ifnet_t *ifp, const unsigned long cmd, const struct sockaddr *sa)
{
        int rc;
        struct ifreq ifr;

        switch (cmd) {
        case SIOCADDMULTI:
        case SIOCDELMULTI:
                break;
        default:
                panic("invalid ifnet multicast command: 0x%lx", cmd);
        }

        ifreq_setaddr(cmd, &ifr, sa);
        rc = if_ioctl(ifp, cmd, &ifr);

        return rc;
}

static void
sysctl_sndq_setup(struct sysctllog **clog, const char *ifname,
    struct ifaltq *ifq)
{
        const struct sysctlnode *cnode, *rnode;

        if (sysctl_createv(clog, 0, NULL, &rnode,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "interfaces",
                       SYSCTL_DESCR("Per-interface controls"),
                       NULL, 0, NULL, 0,
                       CTL_NET, CTL_CREATE, CTL_EOL) != 0)
                goto bad;

        if (sysctl_createv(clog, 0, &rnode, &rnode,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, ifname,
                       SYSCTL_DESCR("Interface controls"),
                       NULL, 0, NULL, 0,
                       CTL_CREATE, CTL_EOL) != 0)
                goto bad;

        if (sysctl_createv(clog, 0, &rnode, &rnode,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "sndq",
                       SYSCTL_DESCR("Interface output queue controls"),
                       NULL, 0, NULL, 0,
                       CTL_CREATE, CTL_EOL) != 0)
                goto bad;

        if (sysctl_createv(clog, 0, &rnode, &cnode,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_INT, "len",
                       SYSCTL_DESCR("Current output queue length"),
                       NULL, 0, &ifq->ifq_len, 0,
                       CTL_CREATE, CTL_EOL) != 0)
                goto bad;

        if (sysctl_createv(clog, 0, &rnode, &cnode,
                       CTLFLAG_PERMANENT | CTLFLAG_READWRITE,
                       CTLTYPE_INT, "maxlen",
                       SYSCTL_DESCR("Maximum allowed output queue length"),
                       NULL, 0, &ifq->ifq_maxlen, 0,
                       CTL_CREATE, CTL_EOL) != 0)
                goto bad;

        if (sysctl_createv(clog, 0, &rnode, &cnode,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_QUAD, "drops",
                       SYSCTL_DESCR("Packets dropped due to full output queue"),
                       NULL, 0, &ifq->ifq_drops, 0,
                       CTL_CREATE, CTL_EOL) != 0)
                goto bad;

        return;
bad:
        printf("%s: could not attach sysctl nodes\n", ifname);
        return;
}

static int
if_sdl_sysctl(SYSCTLFN_ARGS)
{
        struct ifnet *ifp;
        const struct sockaddr_dl *sdl;
        struct psref psref;
        int error = 0;

        if (namelen != 1)
                return EINVAL;

        const int bound = curlwp_bind();
        ifp = if_get_byindex(name[0], &psref);
        if (ifp == NULL) {
                error = ENODEV;
                goto out0;
        }

        sdl = ifp->if_sadl;
        if (sdl == NULL) {
                *oldlenp = 0;
                goto out1;
        }

        if (oldp == NULL) {
                *oldlenp = sdl->sdl_alen;
                goto out1;
        }

        if (*oldlenp >= sdl->sdl_alen)
                *oldlenp = sdl->sdl_alen;
        error = sysctl_copyout(l, &sdl->sdl_data[sdl->sdl_nlen],
            oldp, *oldlenp);
out1:
        if_put(ifp, &psref);
out0:
        curlwp_bindx(bound);
        return error;
}

static void
if_sysctl_setup(struct sysctllog **clog)
{
        const struct sysctlnode *rnode = NULL;

        sysctl_createv(clog, 0, NULL, &rnode,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "sdl",
                       SYSCTL_DESCR("Get active link-layer address"),
                       if_sdl_sysctl, 0, NULL, 0,
                       CTL_NET, CTL_CREATE, CTL_EOL);
}