/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2001 Atsushi Onoe
 * Copyright (c) 2002-2009 Sam Leffler, Errno Consulting
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#include "opt_inet.h"
#include "opt_inet6.h"
#include "opt_wlan.h"

#include <sys/param.h>
#include <sys/systm.h> 
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>   
#include <sys/endian.h>

#include <sys/socket.h>

#include <net/bpf.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <net/if_var.h>
#include <net/if_llc.h>
#include <net/if_media.h>
#include <net/if_private.h>
#include <net/if_vlan_var.h>

#include <net80211/ieee80211_var.h>
#include <net80211/ieee80211_regdomain.h>
#ifdef IEEE80211_SUPPORT_SUPERG
#include <net80211/ieee80211_superg.h>
#endif
#ifdef IEEE80211_SUPPORT_TDMA
#include <net80211/ieee80211_tdma.h>
#endif
#include <net80211/ieee80211_wds.h>
#include <net80211/ieee80211_mesh.h>
#include <net80211/ieee80211_vht.h>

#if defined(INET) || defined(INET6)
#include <netinet/in.h> 
#endif

#ifdef INET
#include <netinet/if_ether.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#endif
#ifdef INET6
#include <netinet/ip6.h>
#endif

#include <security/mac/mac_framework.h>

#define ETHER_HEADER_COPY(dst, src) \
        memcpy(dst, src, sizeof(struct ether_header))

static int ieee80211_fragment(struct ieee80211vap *, struct mbuf *,
        u_int hdrsize, u_int ciphdrsize, u_int mtu);
static  void ieee80211_tx_mgt_cb(struct ieee80211_node *, void *, int);

#ifdef IEEE80211_DEBUG
/*
 * Decide if an outbound management frame should be
 * printed when debugging is enabled.  This filters some
 * of the less interesting frames that come frequently
 * (e.g. beacons).
 */
static __inline int
doprint(struct ieee80211vap *vap, int subtype)
{
        switch (subtype) {
        case IEEE80211_FC0_SUBTYPE_PROBE_RESP:
                return (vap->iv_opmode == IEEE80211_M_IBSS);
        }
        return 1;
}
#endif

/*
 * Transmit a frame to the given destination on the given VAP.
 *
 * It's up to the caller to figure out the details of who this
 * is going to and resolving the node.
 *
 * This routine takes care of queuing it for power save,
 * A-MPDU state stuff, fast-frames state stuff, encapsulation
 * if required, then passing it up to the driver layer.
 *
 * This routine (for now) consumes the mbuf and frees the node
 * reference; it ideally will return a TX status which reflects
 * whether the mbuf was consumed or not, so the caller can
 * free the mbuf (if appropriate) and the node reference (again,
 * if appropriate.)
 */
int
ieee80211_vap_pkt_send_dest(struct ieee80211vap *vap, struct mbuf *m,
    struct ieee80211_node *ni)
{
        struct ieee80211com *ic = vap->iv_ic;
        struct ifnet *ifp = vap->iv_ifp;
        int mcast;
        int do_ampdu = 0;
#ifdef IEEE80211_SUPPORT_SUPERG
        int do_amsdu = 0;
        int do_ampdu_amsdu = 0;
        int no_ampdu = 1; /* Will be set to 0 if ampdu is active */
        int do_ff = 0;
#endif

        if ((ni->ni_flags & IEEE80211_NODE_PWR_MGT) &&
            (m->m_flags & M_PWR_SAV) == 0) {
                /*
                 * Station in power save mode; pass the frame
                 * to the 802.11 layer and continue.  We'll get
                 * the frame back when the time is right.
                 * XXX lose WDS vap linkage?
                 */
                if (ieee80211_pwrsave(ni, m) != 0)
                        if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
                ieee80211_free_node(ni);

                /*
                 * We queued it fine, so tell the upper layer
                 * that we consumed it.
                 */
                return (0);
        }
        /* calculate priority so drivers can find the tx queue */
        if (ieee80211_classify(ni, m)) {
                IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_OUTPUT,
                    ni->ni_macaddr, NULL,
                    "%s", "classification failure");
                vap->iv_stats.is_tx_classify++;
                if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
                m_freem(m);
                ieee80211_free_node(ni);

                /* XXX better status? */
                return (0);
        }
        /*
         * Stash the node pointer.  Note that we do this after
         * any call to ieee80211_dwds_mcast because that code
         * uses any existing value for rcvif to identify the
         * interface it (might have been) received on.
         */
        MPASS((m->m_pkthdr.csum_flags & CSUM_SND_TAG) == 0);
        m->m_pkthdr.rcvif = (void *)ni;
        mcast = (m->m_flags & (M_MCAST | M_BCAST)) ? 1: 0;

        BPF_MTAP(ifp, m);               /* 802.3 tx */

        /*
         * Figure out if we can do A-MPDU, A-MSDU or FF.
         *
         * A-MPDU depends upon vap/node config.
         * A-MSDU depends upon vap/node config.
         * FF depends upon vap config, IE and whether
         *  it's 11abg (and not 11n/11ac/etc.)
         *
         * Note that these flags indiciate whether we can do
         * it at all, rather than the situation (eg traffic type.)
         */
        do_ampdu = ((ni->ni_flags & IEEE80211_NODE_AMPDU_TX) &&
            (vap->iv_flags_ht & IEEE80211_FHT_AMPDU_TX));
#ifdef IEEE80211_SUPPORT_SUPERG
        do_amsdu = ((ni->ni_flags & IEEE80211_NODE_AMSDU_TX) &&
            (vap->iv_flags_ht & IEEE80211_FHT_AMSDU_TX));
        do_ff =
            ((ni->ni_flags & IEEE80211_NODE_HT) == 0) &&
            ((ni->ni_flags & IEEE80211_NODE_VHT) == 0) &&
            (IEEE80211_ATH_CAP(vap, ni, IEEE80211_NODE_FF));
#endif

        /*
         * Check if A-MPDU tx aggregation is setup or if we
         * should try to enable it.  The sta must be associated
         * with HT and A-MPDU enabled for use.  When the policy
         * routine decides we should enable A-MPDU we issue an
         * ADDBA request and wait for a reply.  The frame being
         * encapsulated will go out w/o using A-MPDU, or possibly
         * it might be collected by the driver and held/retransmit.
         * The default ic_ampdu_enable routine handles staggering
         * ADDBA requests in case the receiver NAK's us or we are
         * otherwise unable to establish a BA stream.
         *
         * Don't treat group-addressed frames as candidates for aggregation;
         * net80211 doesn't support 802.11aa-2012 and so group addressed
         * frames will always have sequence numbers allocated from the NON_QOS
         * TID.
         */
        if (!IEEE80211_CONF_AMPDU_OFFLOAD(ic) && do_ampdu) {
                if ((m->m_flags & M_EAPOL) == 0 && (! mcast)) {
                        int tid = WME_AC_TO_TID(M_WME_GETAC(m));
                        struct ieee80211_tx_ampdu *tap = &ni->ni_tx_ampdu[tid];

                        ieee80211_txampdu_count_packet(tap);
                        if (IEEE80211_AMPDU_RUNNING(tap)) {
                                /*
                                 * Operational, mark frame for aggregation.
                                 *
                                 * XXX do tx aggregation here
                                 */
                                m->m_flags |= M_AMPDU_MPDU;
                        } else if (!IEEE80211_AMPDU_REQUESTED(tap) &&
                            ic->ic_ampdu_enable(ni, tap)) {
                                /*
                                 * Not negotiated yet, request service.
                                 */
                                ieee80211_ampdu_request(ni, tap);
                                /* XXX hold frame for reply? */
                        }
                        /*
                         * Now update the no-ampdu flag.  A-MPDU may have been
                         * started or administratively disabled above; so now we
                         * know whether we're running yet or not.
                         *
                         * This will let us know whether we should be doing A-MSDU
                         * at this point.  We only do A-MSDU if we're either not
                         * doing A-MPDU, or A-MPDU is NACKed, or A-MPDU + A-MSDU
                         * is available.
                         *
                         * Whilst here, update the amsdu-ampdu flag.  The above may
                         * have also set or cleared the amsdu-in-ampdu txa_flags
                         * combination so we can correctly do A-MPDU + A-MSDU.
                         */
#ifdef IEEE80211_SUPPORT_SUPERG
                        no_ampdu = (! IEEE80211_AMPDU_RUNNING(tap)
                            || (IEEE80211_AMPDU_NACKED(tap)));
                        do_ampdu_amsdu = IEEE80211_AMPDU_RUNNING_AMSDU(tap);
#endif
                }
        }

#ifdef IEEE80211_SUPPORT_SUPERG
        /*
         * Check for AMSDU/FF; queue for aggregation
         *
         * Note: we don't bother trying to do fast frames or
         * A-MSDU encapsulation for 802.3 drivers.  Now, we
         * likely could do it for FF (because it's a magic
         * atheros tunnel LLC type) but I don't think we're going
         * to really need to.  For A-MSDU we'd have to set the
         * A-MSDU QoS bit in the wifi header, so we just plain
         * can't do it.
         */
        if (__predict_true((vap->iv_caps & IEEE80211_C_8023ENCAP) == 0)) {
                if ((! mcast) &&
                    (do_ampdu_amsdu || (no_ampdu && do_amsdu)) &&
                    ieee80211_amsdu_tx_ok(ni)) {
                        m = ieee80211_amsdu_check(ni, m);
                        if (m == NULL) {
                                /* NB: any ni ref held on stageq */
                                IEEE80211_DPRINTF(vap, IEEE80211_MSG_SUPERG,
                                    "%s: amsdu_check queued frame\n",
                                    __func__);
                                return (0);
                        }
                } else if ((! mcast) && do_ff) {
                        m = ieee80211_ff_check(ni, m);
                        if (m == NULL) {
                                /* NB: any ni ref held on stageq */
                                IEEE80211_DPRINTF(vap, IEEE80211_MSG_SUPERG,
                                    "%s: ff_check queued frame\n",
                                    __func__);
                                return (0);
                        }
                }
        }
#endif /* IEEE80211_SUPPORT_SUPERG */

        /*
         * Grab the TX lock - serialise the TX process from this
         * point (where TX state is being checked/modified)
         * through to driver queue.
         */
        IEEE80211_TX_LOCK(ic);

        /*
         * XXX make the encap and transmit code a separate function
         * so things like the FF (and later A-MSDU) path can just call
         * it for flushed frames.
         */
        if (__predict_true((vap->iv_caps & IEEE80211_C_8023ENCAP) == 0)) {
                /*
                 * Encapsulate the packet in prep for transmission.
                 */
                m = ieee80211_encap(vap, ni, m);
                if (m == NULL) {
                        /* NB: stat+msg handled in ieee80211_encap */
                        IEEE80211_TX_UNLOCK(ic);
                        ieee80211_free_node(ni);
                        if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
                        return (ENOBUFS);
                }
        }
        (void) ieee80211_parent_xmitpkt(ic, m);

        /*
         * Unlock at this point - no need to hold it across
         * ieee80211_free_node() (ie, the comlock)
         */
        IEEE80211_TX_UNLOCK(ic);
        ic->ic_lastdata = ticks;

        return (0);
}

/*
 * Send the given mbuf through the given vap.
 *
 * This consumes the mbuf regardless of whether the transmit
 * was successful or not.
 *
 * This does none of the initial checks that ieee80211_start()
 * does (eg CAC timeout, interface wakeup) - the caller must
 * do this first.
 */
static int
ieee80211_start_pkt(struct ieee80211vap *vap, struct mbuf *m)
{
#define IS_DWDS(vap) \
        (vap->iv_opmode == IEEE80211_M_WDS && \
         (vap->iv_flags_ext & IEEE80211_FEXT_WDSLEGACY) == 0)
        struct ieee80211com *ic = vap->iv_ic;
        struct ifnet *ifp = vap->iv_ifp;
        struct ieee80211_node *ni;
        struct ether_header *eh;

        /*
         * Cancel any background scan.
         */
        if (ic->ic_flags & IEEE80211_F_SCAN)
                ieee80211_cancel_anyscan(vap);
        /* 
         * Find the node for the destination so we can do
         * things like power save and fast frames aggregation.
         *
         * NB: past this point various code assumes the first
         *     mbuf has the 802.3 header present (and contiguous).
         */
        ni = NULL;
        if (m->m_len < sizeof(struct ether_header) &&
           (m = m_pullup(m, sizeof(struct ether_header))) == NULL) {
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_OUTPUT,
                    "discard frame, %s\n", "m_pullup failed");
                vap->iv_stats.is_tx_nobuf++;    /* XXX */
                if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
                return (ENOBUFS);
        }
        eh = mtod(m, struct ether_header *);
        if (ETHER_IS_MULTICAST(eh->ether_dhost)) {
                if (IS_DWDS(vap)) {
                        /*
                         * Only unicast frames from the above go out
                         * DWDS vaps; multicast frames are handled by
                         * dispatching the frame as it comes through
                         * the AP vap (see below).
                         */
                        IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_WDS,
                            eh->ether_dhost, "mcast", "%s", "on DWDS");
                        vap->iv_stats.is_dwds_mcast++;
                        m_freem(m);
                        if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
                        /* XXX better status? */
                        return (ENOBUFS);
                }
                if (vap->iv_opmode == IEEE80211_M_HOSTAP) {
                        /*
                         * Spam DWDS vap's w/ multicast traffic.
                         */
                        /* XXX only if dwds in use? */
                        ieee80211_dwds_mcast(vap, m);
                }
        }
#ifdef IEEE80211_SUPPORT_MESH
        if (vap->iv_opmode != IEEE80211_M_MBSS) {
#endif
                ni = ieee80211_find_txnode(vap, eh->ether_dhost);
                if (ni == NULL) {
                        /* NB: ieee80211_find_txnode does stat+msg */
                        if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
                        m_freem(m);
                        /* XXX better status? */
                        return (ENOBUFS);
                }
                if (ni->ni_associd == 0 &&
                    (ni->ni_flags & IEEE80211_NODE_ASSOCID)) {
                        IEEE80211_DISCARD_MAC(vap, IEEE80211_MSG_OUTPUT,
                            eh->ether_dhost, NULL,
                            "sta not associated (type 0x%04x)",
                            htons(eh->ether_type));
                        vap->iv_stats.is_tx_notassoc++;
                        if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
                        m_freem(m);
                        ieee80211_free_node(ni);
                        /* XXX better status? */
                        return (ENOBUFS);
                }
#ifdef IEEE80211_SUPPORT_MESH
        } else {
                if (!IEEE80211_ADDR_EQ(eh->ether_shost, vap->iv_myaddr)) {
                        /*
                         * Proxy station only if configured.
                         */
                        if (!ieee80211_mesh_isproxyena(vap)) {
                                IEEE80211_DISCARD_MAC(vap,
                                    IEEE80211_MSG_OUTPUT |
                                    IEEE80211_MSG_MESH,
                                    eh->ether_dhost, NULL,
                                    "%s", "proxy not enabled");
                                vap->iv_stats.is_mesh_notproxy++;
                                if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
                                m_freem(m);
                                /* XXX better status? */
                                return (ENOBUFS);
                        }
                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_OUTPUT,
                            "forward frame from DS SA(%6D), DA(%6D)\n",
                            eh->ether_shost, ":",
                            eh->ether_dhost, ":");
                        ieee80211_mesh_proxy_check(vap, eh->ether_shost);
                }
                ni = ieee80211_mesh_discover(vap, eh->ether_dhost, m);
                if (ni == NULL) {
                        /*
                         * NB: ieee80211_mesh_discover holds/disposes
                         * frame (e.g. queueing on path discovery).
                         */
                        if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
                        /* XXX better status? */
                        return (ENOBUFS);
                }
        }
#endif

        /*
         * We've resolved the sender, so attempt to transmit it.
         */

        if (vap->iv_state == IEEE80211_S_SLEEP) {
                /*
                 * In power save; queue frame and then  wakeup device
                 * for transmit.
                 */
                ic->ic_lastdata = ticks;
                if (ieee80211_pwrsave(ni, m) != 0)
                        if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
                ieee80211_free_node(ni);
                ieee80211_new_state(vap, IEEE80211_S_RUN, 0);
                return (0);
        }

        if (ieee80211_vap_pkt_send_dest(vap, m, ni) != 0)
                return (ENOBUFS);
        return (0);
#undef  IS_DWDS
}

/*
 * Start method for vap's.  All packets from the stack come
 * through here.  We handle common processing of the packets
 * before dispatching them to the underlying device.
 *
 * if_transmit() requires that the mbuf be consumed by this call
 * regardless of the return condition.
 */
int
ieee80211_vap_transmit(struct ifnet *ifp, struct mbuf *m)
{
        struct ieee80211vap *vap = ifp->if_softc;
        struct ieee80211com *ic = vap->iv_ic;

        /*
         * No data frames go out unless we're running.
         * Note in particular this covers CAC and CSA
         * states (though maybe we should check muting
         * for CSA).
         */
        if (vap->iv_state != IEEE80211_S_RUN &&
            vap->iv_state != IEEE80211_S_SLEEP) {
                IEEE80211_LOCK(ic);
                /* re-check under the com lock to avoid races */
                if (vap->iv_state != IEEE80211_S_RUN &&
                    vap->iv_state != IEEE80211_S_SLEEP) {
                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_OUTPUT,
                            "%s: ignore queue, in %s state\n",
                            __func__, ieee80211_state_name[vap->iv_state]);
                        vap->iv_stats.is_tx_badstate++;
                        IEEE80211_UNLOCK(ic);
                        ifp->if_drv_flags |= IFF_DRV_OACTIVE;
                        m_freem(m);
                        if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
                        return (ENETDOWN);
                }
                IEEE80211_UNLOCK(ic);
        }

        /*
         * Sanitize mbuf flags for net80211 use.  We cannot
         * clear M_PWR_SAV or M_MORE_DATA because these may
         * be set for frames that are re-submitted from the
         * power save queue.
         *
         * NB: This must be done before ieee80211_classify as
         *     it marks EAPOL in frames with M_EAPOL.
         */
        m->m_flags &= ~(M_80211_TX - M_PWR_SAV - M_MORE_DATA);

        /*
         * Bump to the packet transmission path.
         * The mbuf will be consumed here.
         */
        return (ieee80211_start_pkt(vap, m));
}

void
ieee80211_vap_qflush(struct ifnet *ifp)
{

        /* Empty for now */
}

/*
 * 802.11 raw output routine.
 *
 * XXX TODO: this (and other send routines) should correctly
 * XXX keep the pwr mgmt bit set if it decides to call into the
 * XXX driver to send a frame whilst the state is SLEEP.
 *
 * Otherwise the peer may decide that we're awake and flood us
 * with traffic we are still too asleep to receive!
 */
int
ieee80211_raw_output(struct ieee80211vap *vap, struct ieee80211_node *ni,
    struct mbuf *m, const struct ieee80211_bpf_params *params)
{
        struct ieee80211com *ic = vap->iv_ic;
        int error;

        /*
         * Set node - the caller has taken a reference, so ensure
         * that the mbuf has the same node value that
         * it would if it were going via the normal path.
         */
        MPASS((m->m_pkthdr.csum_flags & CSUM_SND_TAG) == 0);
        m->m_pkthdr.rcvif = (void *)ni;

        /*
         * Attempt to add bpf transmit parameters.
         *
         * For now it's ok to fail; the raw_xmit api still takes
         * them as an option.
         *
         * Later on when ic_raw_xmit() has params removed,
         * they'll have to be added - so fail the transmit if
         * they can't be.
         */
        if (params)
                (void) ieee80211_add_xmit_params(m, params);

        error = ic->ic_raw_xmit(ni, m, params);
        if (error) {
                if_inc_counter(vap->iv_ifp, IFCOUNTER_OERRORS, 1);
                ieee80211_free_node(ni);
        }
        return (error);
}

static int
ieee80211_validate_frame(struct mbuf *m,
    const struct ieee80211_bpf_params *params)
{
        struct ieee80211_frame *wh;
        int type;

        if (m->m_pkthdr.len < sizeof(struct ieee80211_frame_ack))
                return (EINVAL);

        wh = mtod(m, struct ieee80211_frame *);
        if (!IEEE80211_IS_FC0_CHECK_VER(wh, IEEE80211_FC0_VERSION_0))
                return (EINVAL);

        type = wh->i_fc[0] & IEEE80211_FC0_TYPE_MASK;
        if (type != IEEE80211_FC0_TYPE_DATA) {
                if ((wh->i_fc[1] & IEEE80211_FC1_DIR_MASK) !=
                    IEEE80211_FC1_DIR_NODS)
                        return (EINVAL);

                if (type != IEEE80211_FC0_TYPE_MGT &&
                    (wh->i_fc[1] & IEEE80211_FC1_MORE_FRAG) != 0)
                        return (EINVAL);

                /* XXX skip other field checks? */
        }

        if ((params && (params->ibp_flags & IEEE80211_BPF_CRYPTO) != 0) ||
            (IEEE80211_IS_PROTECTED(wh))) {
                int subtype;

                subtype = wh->i_fc[0] & IEEE80211_FC0_SUBTYPE_MASK;

                /*
                 * See IEEE Std 802.11-2012,
                 * 8.2.4.1.9 'Protected Frame field'
                 */
                /* XXX no support for robust management frames yet. */
                if (!(type == IEEE80211_FC0_TYPE_DATA ||
                    (type == IEEE80211_FC0_TYPE_MGT &&
                     subtype == IEEE80211_FC0_SUBTYPE_AUTH)))
                        return (EINVAL);

                wh->i_fc[1] |= IEEE80211_FC1_PROTECTED;
        }

        if (m->m_pkthdr.len < ieee80211_anyhdrsize(wh))
                return (EINVAL);

        return (0);
}

static int
ieee80211_validate_rate(struct ieee80211_node *ni, uint8_t rate)
{
        struct ieee80211com *ic = ni->ni_ic;

        if (IEEE80211_IS_HT_RATE(rate)) {
                if ((ic->ic_htcaps & IEEE80211_HTC_HT) == 0)
                        return (EINVAL);

                rate = IEEE80211_RV(rate);
                if (rate <= 31) {
                        if (rate > ic->ic_txstream * 8 - 1)
                                return (EINVAL);

                        return (0);
                }

                if (rate == 32) {
                        if ((ic->ic_htcaps & IEEE80211_HTC_TXMCS32) == 0)
                                return (EINVAL);

                        return (0);
                }

                if ((ic->ic_htcaps & IEEE80211_HTC_TXUNEQUAL) == 0)
                        return (EINVAL);

                switch (ic->ic_txstream) {
                case 0:
                case 1:
                        return (EINVAL);
                case 2:
                        if (rate > 38)
                                return (EINVAL);

                        return (0);
                case 3:
                        if (rate > 52)
                                return (EINVAL);

                        return (0);
                case 4:
                default:
                        if (rate > 76)
                                return (EINVAL);

                        return (0);
                }
        }

        if (!ieee80211_isratevalid(ic->ic_rt, rate))
                return (EINVAL);

        return (0);
}

static int
ieee80211_sanitize_rates(struct ieee80211_node *ni, struct mbuf *m,
    const struct ieee80211_bpf_params *params)
{
        int error;

        if (!params)
                return (0);     /* nothing to do */

        /* NB: most drivers assume that ibp_rate0 is set (!= 0). */
        if (params->ibp_rate0 != 0) {
                error = ieee80211_validate_rate(ni, params->ibp_rate0);
                if (error != 0)
                        return (error);
        } else {
                /* XXX pre-setup some default (e.g., mgmt / mcast) rate */
                /* XXX __DECONST? */
                (void) m;
        }

        if (params->ibp_rate1 != 0 &&
            (error = ieee80211_validate_rate(ni, params->ibp_rate1)) != 0)
                return (error);

        if (params->ibp_rate2 != 0 &&
            (error = ieee80211_validate_rate(ni, params->ibp_rate2)) != 0)
                return (error);

        if (params->ibp_rate3 != 0 &&
            (error = ieee80211_validate_rate(ni, params->ibp_rate3)) != 0)
                return (error);

        return (0);
}

/*
 * 802.11 output routine. This is (currently) used only to
 * connect bpf write calls to the 802.11 layer for injecting
 * raw 802.11 frames.
 */
int
ieee80211_output(struct ifnet *ifp, struct mbuf *m,
        const struct sockaddr *dst, struct route *ro)
{
#define senderr(e) do { error = (e); goto bad;} while (0)
        const struct ieee80211_bpf_params *params = NULL;
        struct ieee80211_node *ni = NULL;
        struct ieee80211vap *vap;
        struct ieee80211_frame *wh;
        struct ieee80211com *ic = NULL;
        int error;
        int ret;

        if (ifp->if_drv_flags & IFF_DRV_OACTIVE) {
                /*
                 * Short-circuit requests if the vap is marked OACTIVE
                 * as this can happen because a packet came down through
                 * ieee80211_start before the vap entered RUN state in
                 * which case it's ok to just drop the frame.  This
                 * should not be necessary but callers of if_output don't
                 * check OACTIVE.
                 */
                senderr(ENETDOWN);
        }
        vap = ifp->if_softc;
        ic = vap->iv_ic;
        /*
         * Hand to the 802.3 code if not tagged as
         * a raw 802.11 frame.
         */
        if (dst->sa_family != AF_IEEE80211)
                return vap->iv_output(ifp, m, dst, ro);
#ifdef MAC
        error = mac_ifnet_check_transmit(ifp, m);
        if (error)
                senderr(error);
#endif
        if (ieee80211_vap_ifp_check_is_monitor(vap))
                senderr(ENETDOWN);
        if (!IFNET_IS_UP_RUNNING(ifp))
                senderr(ENETDOWN);
        if (vap->iv_state == IEEE80211_S_CAC) {
                IEEE80211_DPRINTF(vap,
                    IEEE80211_MSG_OUTPUT | IEEE80211_MSG_DOTH,
                    "block %s frame in CAC state\n", "raw data");
                vap->iv_stats.is_tx_badstate++;
                senderr(EIO);           /* XXX */
        } else if (vap->iv_state == IEEE80211_S_SCAN)
                senderr(EIO);
        /* XXX bypass bridge, pfil, carp, etc. */

        /*
         * NB: DLT_IEEE802_11_RADIO identifies the parameters are
         * present by setting the sa_len field of the sockaddr (yes,
         * this is a hack).
         * NB: we assume sa_data is suitably aligned to cast.
         */
        if (dst->sa_len != 0)
                params = (const struct ieee80211_bpf_params *)dst->sa_data;

        error = ieee80211_validate_frame(m, params);
        if (error != 0)
                senderr(error);

        wh = mtod(m, struct ieee80211_frame *);

        /* locate destination node */
        switch (wh->i_fc[1] & IEEE80211_FC1_DIR_MASK) {
        case IEEE80211_FC1_DIR_NODS:
        case IEEE80211_FC1_DIR_FROMDS:
                ni = ieee80211_find_txnode(vap, wh->i_addr1);
                break;
        case IEEE80211_FC1_DIR_TODS:
        case IEEE80211_FC1_DIR_DSTODS:
                ni = ieee80211_find_txnode(vap, wh->i_addr3);
                break;
        default:
                senderr(EDOOFUS);
        }
        if (ni == NULL) {
                /*
                 * Permit packets w/ bpf params through regardless
                 * (see below about sa_len).
                 */
                if (dst->sa_len == 0)
                        senderr(EHOSTUNREACH);
                ni = ieee80211_ref_node(vap->iv_bss);
        }

        /*
         * Sanitize mbuf for net80211 flags leaked from above.
         *
         * NB: This must be done before ieee80211_classify as
         *     it marks EAPOL in frames with M_EAPOL.
         */
        m->m_flags &= ~M_80211_TX;
        m->m_flags |= M_ENCAP;          /* mark encapsulated */

        if (IEEE80211_IS_DATA(wh)) {
                /* calculate priority so drivers can find the tx queue */
                if (ieee80211_classify(ni, m))
                        senderr(EIO);           /* XXX */

                /* NB: ieee80211_encap does not include 802.11 header */
                IEEE80211_NODE_STAT_ADD(ni, tx_bytes,
                    m->m_pkthdr.len - ieee80211_hdrsize(wh));
        } else
                M_WME_SETAC(m, WME_AC_BE);

        error = ieee80211_sanitize_rates(ni, m, params);
        if (error != 0)
                senderr(error);

        IEEE80211_NODE_STAT(ni, tx_data);
        if (IEEE80211_IS_MULTICAST(wh->i_addr1)) {
                IEEE80211_NODE_STAT(ni, tx_mcast);
                m->m_flags |= M_MCAST;
        } else
                IEEE80211_NODE_STAT(ni, tx_ucast);

        IEEE80211_TX_LOCK(ic);
        ret = ieee80211_raw_output(vap, ni, m, params);
        IEEE80211_TX_UNLOCK(ic);
        return (ret);
bad:
        if (m != NULL)
                m_freem(m);
        if (ni != NULL)
                ieee80211_free_node(ni);
        if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
        return error;
#undef senderr
}

/*
 * Set the direction field and address fields of an outgoing
 * frame.  Note this should be called early on in constructing
 * a frame as it sets i_fc[1]; other bits can then be or'd in.
 */
void
ieee80211_send_setup(
        struct ieee80211_node *ni,
        struct mbuf *m,
        int type, int tid,
        const uint8_t sa[IEEE80211_ADDR_LEN],
        const uint8_t da[IEEE80211_ADDR_LEN],
        const uint8_t bssid[IEEE80211_ADDR_LEN])
{
#define WH4(wh) ((struct ieee80211_frame_addr4 *)wh)
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211_tx_ampdu *tap;
        struct ieee80211_frame *wh = mtod(m, struct ieee80211_frame *);

        IEEE80211_TX_LOCK_ASSERT(ni->ni_ic);

        wh->i_fc[0] = IEEE80211_FC0_VERSION_0 | type;
        if ((type & IEEE80211_FC0_TYPE_MASK) == IEEE80211_FC0_TYPE_DATA) {
                switch (vap->iv_opmode) {
                case IEEE80211_M_STA:
                        wh->i_fc[1] = IEEE80211_FC1_DIR_TODS;
                        IEEE80211_ADDR_COPY(wh->i_addr1, bssid);
                        IEEE80211_ADDR_COPY(wh->i_addr2, sa);
                        IEEE80211_ADDR_COPY(wh->i_addr3, da);
                        break;
                case IEEE80211_M_IBSS:
                case IEEE80211_M_AHDEMO:
                        wh->i_fc[1] = IEEE80211_FC1_DIR_NODS;
                        IEEE80211_ADDR_COPY(wh->i_addr1, da);
                        IEEE80211_ADDR_COPY(wh->i_addr2, sa);
                        IEEE80211_ADDR_COPY(wh->i_addr3, bssid);
                        break;
                case IEEE80211_M_HOSTAP:
                        wh->i_fc[1] = IEEE80211_FC1_DIR_FROMDS;
                        IEEE80211_ADDR_COPY(wh->i_addr1, da);
                        IEEE80211_ADDR_COPY(wh->i_addr2, bssid);
                        IEEE80211_ADDR_COPY(wh->i_addr3, sa);
                        break;
                case IEEE80211_M_WDS:
                        wh->i_fc[1] = IEEE80211_FC1_DIR_DSTODS;
                        IEEE80211_ADDR_COPY(wh->i_addr1, da);
                        IEEE80211_ADDR_COPY(wh->i_addr2, vap->iv_myaddr);
                        IEEE80211_ADDR_COPY(wh->i_addr3, da);
                        IEEE80211_ADDR_COPY(WH4(wh)->i_addr4, sa);
                        break;
                case IEEE80211_M_MBSS:
#ifdef IEEE80211_SUPPORT_MESH
                        if (IEEE80211_IS_MULTICAST(da)) {
                                wh->i_fc[1] = IEEE80211_FC1_DIR_FROMDS;
                                /* XXX next hop */
                                IEEE80211_ADDR_COPY(wh->i_addr1, da);
                                IEEE80211_ADDR_COPY(wh->i_addr2,
                                    vap->iv_myaddr);
                        } else {
                                wh->i_fc[1] = IEEE80211_FC1_DIR_DSTODS;
                                IEEE80211_ADDR_COPY(wh->i_addr1, da);
                                IEEE80211_ADDR_COPY(wh->i_addr2,
                                    vap->iv_myaddr);
                                IEEE80211_ADDR_COPY(wh->i_addr3, da);
                                IEEE80211_ADDR_COPY(WH4(wh)->i_addr4, sa);
                        }
#endif
                        break;
                case IEEE80211_M_MONITOR:       /* NB: to quiet compiler */
                        break;
                }
        } else {
                wh->i_fc[1] = IEEE80211_FC1_DIR_NODS;
                IEEE80211_ADDR_COPY(wh->i_addr1, da);
                IEEE80211_ADDR_COPY(wh->i_addr2, sa);
#ifdef IEEE80211_SUPPORT_MESH
                if (vap->iv_opmode == IEEE80211_M_MBSS)
                        IEEE80211_ADDR_COPY(wh->i_addr3, sa);
                else
#endif
                        IEEE80211_ADDR_COPY(wh->i_addr3, bssid);
        }
        *(uint16_t *)&wh->i_dur[0] = 0;

        /*
         * XXX TODO: this is what the TX lock is for.
         * Here we're incrementing sequence numbers, and they
         * need to be in lock-step with what the driver is doing
         * both in TX ordering and crypto encap (IV increment.)
         *
         * If the driver does seqno itself, then we can skip
         * assigning sequence numbers here, and we can avoid
         * requiring the TX lock.
         */
        tap = &ni->ni_tx_ampdu[tid];
        if (tid != IEEE80211_NONQOS_TID && IEEE80211_AMPDU_RUNNING(tap)) {
                m->m_flags |= M_AMPDU_MPDU;

                /* NB: zero out i_seq field (for s/w encryption etc) */
                *(uint16_t *)&wh->i_seq[0] = 0;
        } else if (!IEEE80211_CONF_SEQNO_OFFLOAD(ni->ni_ic))
                ieee80211_output_seqno_assign(ni, tid, m);

        if (IEEE80211_IS_MULTICAST(wh->i_addr1))
                m->m_flags |= M_MCAST;
#undef WH4
}

/*
 * Send a management frame to the specified node.  The node pointer
 * must have a reference as the pointer will be passed to the driver
 * and potentially held for a long time.  If the frame is successfully
 * dispatched to the driver, then it is responsible for freeing the
 * reference (and potentially free'ing up any associated storage);
 * otherwise deal with reclaiming any reference (on error).
 */
int
ieee80211_mgmt_output(struct ieee80211_node *ni, struct mbuf *m, int type,
        struct ieee80211_bpf_params *params)
{
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211com *ic = ni->ni_ic;
        struct ieee80211_frame *wh;
        int ret;

        KASSERT(ni != NULL, ("null node"));

        if (vap->iv_state == IEEE80211_S_CAC) {
                IEEE80211_NOTE(vap, IEEE80211_MSG_OUTPUT | IEEE80211_MSG_DOTH,
                    ni, "block %s frame in CAC state",
                        ieee80211_mgt_subtype_name(type));
                vap->iv_stats.is_tx_badstate++;
                ieee80211_free_node(ni);
                m_freem(m);
                return EIO;             /* XXX */
        }

        M_PREPEND(m, sizeof(struct ieee80211_frame), IEEE80211_M_NOWAIT);
        if (m == NULL) {
                ieee80211_free_node(ni);
                return ENOMEM;
        }

        IEEE80211_TX_LOCK(ic);

        wh = mtod(m, struct ieee80211_frame *);
        ieee80211_send_setup(ni, m,
             IEEE80211_FC0_TYPE_MGT | type, IEEE80211_NONQOS_TID,
             vap->iv_myaddr, ni->ni_macaddr, ni->ni_bssid);
        if (params->ibp_flags & IEEE80211_BPF_CRYPTO) {
                IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_AUTH, wh->i_addr1,
                    "encrypting frame (%s)", __func__);
                wh->i_fc[1] |= IEEE80211_FC1_PROTECTED;
        }
        m->m_flags |= M_ENCAP;          /* mark encapsulated */

        KASSERT(type != IEEE80211_FC0_SUBTYPE_PROBE_RESP, ("probe response?"));
        M_WME_SETAC(m, params->ibp_pri);

#ifdef IEEE80211_DEBUG
        /* avoid printing too many frames */
        if ((ieee80211_msg_debug(vap) && doprint(vap, type)) ||
            ieee80211_msg_dumppkts(vap)) {
                ieee80211_note(vap, "[%s] send %s on channel %u\n",
                    ether_sprintf(wh->i_addr1),
                    ieee80211_mgt_subtype_name(type),
                    ieee80211_chan2ieee(ic, ic->ic_curchan));
        }
#endif
        IEEE80211_NODE_STAT(ni, tx_mgmt);

        ret = ieee80211_raw_output(vap, ni, m, params);
        IEEE80211_TX_UNLOCK(ic);
        return (ret);
}

static void
ieee80211_nulldata_transmitted(struct ieee80211_node *ni, void *arg,
    int status)
{
        struct ieee80211vap *vap = ni->ni_vap;

        wakeup(vap);
}

/*
 * Send a null data frame to the specified node.  If the station
 * is setup for QoS then a QoS Null Data frame is constructed.
 * If this is a WDS station then a 4-address frame is constructed.
 *
 * NB: the caller is assumed to have setup a node reference
 *     for use; this is necessary to deal with a race condition
 *     when probing for inactive stations.  Like ieee80211_mgmt_output
 *     we must cleanup any node reference on error;  however we
 *     can safely just unref it as we know it will never be the
 *     last reference to the node.
 */
int
ieee80211_send_nulldata(struct ieee80211_node *ni)
{
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211com *ic = ni->ni_ic;
        struct mbuf *m;
        struct ieee80211_frame *wh;
        int hdrlen;
        uint8_t *frm;
        int ret;

        /* Don't send NULL frames if we've been configured not to do so. */
        if ((ic->ic_flags_ext & IEEE80211_FEXT_NO_NULLDATA) != 0) {
                ieee80211_node_decref(ni);
                return (0);
        }

        if (vap->iv_state == IEEE80211_S_CAC) {
                IEEE80211_NOTE(vap, IEEE80211_MSG_OUTPUT | IEEE80211_MSG_DOTH,
                    ni, "block %s frame in CAC state", "null data");
                ieee80211_node_decref(ni);
                vap->iv_stats.is_tx_badstate++;
                return EIO;             /* XXX */
        }

        if (ni->ni_flags & (IEEE80211_NODE_QOS|IEEE80211_NODE_HT))
                hdrlen = sizeof(struct ieee80211_qosframe);
        else
                hdrlen = sizeof(struct ieee80211_frame);
        /* NB: only WDS vap's get 4-address frames */
        if (vap->iv_opmode == IEEE80211_M_WDS)
                hdrlen += IEEE80211_ADDR_LEN;
        if (ic->ic_flags & IEEE80211_F_DATAPAD)
                hdrlen = roundup(hdrlen, sizeof(uint32_t));

        m = ieee80211_getmgtframe(&frm, ic->ic_headroom + hdrlen, 0);
        if (m == NULL) {
                /* XXX debug msg */
                ieee80211_node_decref(ni);
                vap->iv_stats.is_tx_nobuf++;
                return ENOMEM;
        }
        KASSERT(M_LEADINGSPACE(m) >= hdrlen,
            ("leading space %zd", M_LEADINGSPACE(m)));
        M_PREPEND(m, hdrlen, IEEE80211_M_NOWAIT);
        if (m == NULL) {
                /* NB: cannot happen */
                ieee80211_free_node(ni);
                return ENOMEM;
        }

        IEEE80211_TX_LOCK(ic);

        wh = mtod(m, struct ieee80211_frame *);         /* NB: a little lie */
        if (ni->ni_flags & IEEE80211_NODE_QOS) {
                const int tid = WME_AC_TO_TID(WME_AC_BE);
                uint8_t *qos;

                ieee80211_send_setup(ni, m,
                    IEEE80211_FC0_TYPE_DATA | IEEE80211_FC0_SUBTYPE_QOS_NULL,
                    tid, vap->iv_myaddr, ni->ni_macaddr, ni->ni_bssid);

                if (vap->iv_opmode == IEEE80211_M_WDS)
                        qos = ((struct ieee80211_qosframe_addr4 *) wh)->i_qos;
                else
                        qos = ((struct ieee80211_qosframe *) wh)->i_qos;
                qos[0] = tid & IEEE80211_QOS_TID;
                if (ic->ic_wme.wme_wmeChanParams.cap_wmeParams[WME_AC_BE].wmep_noackPolicy)
                        qos[0] |= IEEE80211_QOS_ACKPOLICY_NOACK;
                qos[1] = 0;
        } else {
                ieee80211_send_setup(ni, m,
                    IEEE80211_FC0_TYPE_DATA | IEEE80211_FC0_SUBTYPE_NODATA,
                    IEEE80211_NONQOS_TID,
                    vap->iv_myaddr, ni->ni_macaddr, ni->ni_bssid);
        }
        if (vap->iv_opmode != IEEE80211_M_WDS) {
                /* NB: power management bit is never sent by an AP */
                if ((ni->ni_flags & IEEE80211_NODE_PWR_MGT) &&
                    vap->iv_opmode != IEEE80211_M_HOSTAP)
                        wh->i_fc[1] |= IEEE80211_FC1_PWR_MGT;
        }
        if ((ic->ic_flags & IEEE80211_F_SCAN) &&
            (ni->ni_flags & IEEE80211_NODE_PWR_MGT)) {
                ieee80211_add_callback(m, ieee80211_nulldata_transmitted,
                    NULL);
        }
        m->m_len = m->m_pkthdr.len = hdrlen;
        m->m_flags |= M_ENCAP;          /* mark encapsulated */

        M_WME_SETAC(m, WME_AC_BE);

        IEEE80211_NODE_STAT(ni, tx_data);

        IEEE80211_NOTE(vap, IEEE80211_MSG_DEBUG | IEEE80211_MSG_DUMPPKTS, ni,
            "send %snull data frame on channel %u, pwr mgt %s",
            ni->ni_flags & IEEE80211_NODE_QOS ? "QoS " : "",
            ieee80211_chan2ieee(ic, ic->ic_curchan),
            wh->i_fc[1] & IEEE80211_FC1_PWR_MGT ? "ena" : "dis");

        ret = ieee80211_raw_output(vap, ni, m, NULL);
        IEEE80211_TX_UNLOCK(ic);
        return (ret);
}

/* 
 * Assign priority to a frame based on any vlan tag assigned
 * to the station and/or any Diffserv setting in an IP header.
 * Finally, if an ACM policy is setup (in station mode) it's
 * applied.
 */
int
ieee80211_classify(struct ieee80211_node *ni, struct mbuf *m)
{
        const struct ether_header *eh = NULL;
        uint16_t ether_type;
        int v_wme_ac, d_wme_ac, ac;

        if (__predict_false(m->m_flags & M_ENCAP)) {
                struct ieee80211_frame *wh = mtod(m, struct ieee80211_frame *);
                struct llc *llc;
                int hdrlen, subtype;

                subtype = wh->i_fc[0] & IEEE80211_FC0_SUBTYPE_MASK;
                if (subtype & IEEE80211_FC0_SUBTYPE_NODATA) {
                        ac = WME_AC_BE;
                        goto done;
                }

                hdrlen = ieee80211_hdrsize(wh);
                if (m->m_pkthdr.len < hdrlen + sizeof(*llc))
                        return 1;

                llc = (struct llc *)mtodo(m, hdrlen);
                if (llc->llc_dsap != LLC_SNAP_LSAP ||
                    llc->llc_ssap != LLC_SNAP_LSAP ||
                    llc->llc_control != LLC_UI ||
                    llc->llc_snap.org_code[0] != 0 ||
                    llc->llc_snap.org_code[1] != 0 ||
                    llc->llc_snap.org_code[2] != 0)
                        return 1;

                ether_type = llc->llc_snap.ether_type;
        } else {
                eh = mtod(m, struct ether_header *);
                ether_type = eh->ether_type;
        }

        /*
         * Always promote PAE/EAPOL frames to high priority.
         */
        if (ether_type == htons(ETHERTYPE_PAE)) {
                /* NB: mark so others don't need to check header */
                m->m_flags |= M_EAPOL;
                ac = WME_AC_VO;
                goto done;
        }
        /*
         * Non-qos traffic goes to BE.
         */
        if ((ni->ni_flags & IEEE80211_NODE_QOS) == 0) {
                ac = WME_AC_BE;
                goto done;
        }

        /* 
         * If node has a vlan tag then all traffic
         * to it must have a matching tag.
         */
        v_wme_ac = 0;
        if (ni->ni_vlan != 0) {
                 if ((m->m_flags & M_VLANTAG) == 0) {
                        IEEE80211_NODE_STAT(ni, tx_novlantag);
                        return 1;
                }
                if (EVL_VLANOFTAG(m->m_pkthdr.ether_vtag) !=
                    EVL_VLANOFTAG(ni->ni_vlan)) {
                        IEEE80211_NODE_STAT(ni, tx_vlanmismatch);
                        return 1;
                }
                /* map vlan priority to AC */
                v_wme_ac = TID_TO_WME_AC(EVL_PRIOFTAG(ni->ni_vlan));
        }

        if (eh == NULL)
                goto no_eh;

        /* XXX m_copydata may be too slow for fast path */
        switch (ntohs(eh->ether_type)) {
#ifdef INET
        case ETHERTYPE_IP:
        {
                uint8_t tos;
                /*
                 * IP frame, map the DSCP bits from the TOS field.
                 */
                /* NB: ip header may not be in first mbuf */
                m_copydata(m, sizeof(struct ether_header) +
                    offsetof(struct ip, ip_tos), sizeof(tos), &tos);
                tos >>= 5;              /* NB: ECN + low 3 bits of DSCP */
                d_wme_ac = TID_TO_WME_AC(tos);
                break;
        }
#endif
#ifdef INET6
        case ETHERTYPE_IPV6:
        {
                uint32_t flow;
                uint8_t tos;
                /*
                 * IPv6 frame, map the DSCP bits from the traffic class field.
                 */
                m_copydata(m, sizeof(struct ether_header) +
                    offsetof(struct ip6_hdr, ip6_flow), sizeof(flow),
                    (caddr_t) &flow);
                tos = (uint8_t)(ntohl(flow) >> 20);
                tos >>= 5;              /* NB: ECN + low 3 bits of DSCP */
                d_wme_ac = TID_TO_WME_AC(tos);
                break;
        }
#endif
        default:
no_eh:
                d_wme_ac = WME_AC_BE;
                break;
        }

        /*
         * Use highest priority AC.
         */
        if (v_wme_ac > d_wme_ac)
                ac = v_wme_ac;
        else
                ac = d_wme_ac;

        /*
         * Apply ACM policy.
         */
        if (ni->ni_vap->iv_opmode == IEEE80211_M_STA) {
                static const int acmap[4] = {
                        WME_AC_BK,      /* WME_AC_BE */
                        WME_AC_BK,      /* WME_AC_BK */
                        WME_AC_BE,      /* WME_AC_VI */
                        WME_AC_VI,      /* WME_AC_VO */
                };
                struct ieee80211com *ic = ni->ni_ic;

                while (ac != WME_AC_BK &&
                    ic->ic_wme.wme_wmeBssChanParams.cap_wmeParams[ac].wmep_acm)
                        ac = acmap[ac];
        }
done:
        M_WME_SETAC(m, ac);
        return 0;
}

/*
 * Insure there is sufficient contiguous space to encapsulate the
 * 802.11 data frame.  If room isn't already there, arrange for it.
 * Drivers and cipher modules assume we have done the necessary work
 * and fail rudely if they don't find the space they need.
 */
struct mbuf *
ieee80211_mbuf_adjust(struct ieee80211vap *vap, int hdrsize,
        struct ieee80211_key *key, struct mbuf *m)
{
#define TO_BE_RECLAIMED (sizeof(struct ether_header) - sizeof(struct llc))
        int needed_space = vap->iv_ic->ic_headroom + hdrsize;

        if (key != NULL) {
                /* XXX belongs in crypto code? */
                needed_space += key->wk_cipher->ic_header;
                /* XXX frags */
                /*
                 * When crypto is being done in the host we must insure
                 * the data are writable for the cipher routines; clone
                 * a writable mbuf chain.
                 * XXX handle SWMIC specially
                 */
                if (key->wk_flags & (IEEE80211_KEY_SWENCRYPT|IEEE80211_KEY_SWENMIC)) {
                        m = m_unshare(m, IEEE80211_M_NOWAIT);
                        if (m == NULL) {
                                IEEE80211_DPRINTF(vap, IEEE80211_MSG_OUTPUT,
                                    "%s: cannot get writable mbuf\n", __func__);
                                vap->iv_stats.is_tx_nobuf++; /* XXX new stat */
                                return NULL;
                        }
                }
        }
        /*
         * We know we are called just before stripping an Ethernet
         * header and prepending an LLC header.  This means we know
         * there will be
         *      sizeof(struct ether_header) - sizeof(struct llc)
         * bytes recovered to which we need additional space for the
         * 802.11 header and any crypto header.
         */
        /* XXX check trailing space and copy instead? */
        if (M_LEADINGSPACE(m) < needed_space - TO_BE_RECLAIMED) {
                struct mbuf *n = m_gethdr(IEEE80211_M_NOWAIT, m->m_type);
                if (n == NULL) {
                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_OUTPUT,
                            "%s: cannot expand storage\n", __func__);
                        vap->iv_stats.is_tx_nobuf++;
                        m_freem(m);
                        return NULL;
                }
                KASSERT(needed_space <= MHLEN,
                    ("not enough room, need %u got %d\n", needed_space, MHLEN));
                /*
                 * Setup new mbuf to have leading space to prepend the
                 * 802.11 header and any crypto header bits that are
                 * required (the latter are added when the driver calls
                 * back to ieee80211_crypto_encap to do crypto encapsulation).
                 */
                /* NB: must be first 'cuz it clobbers m_data */
                m_move_pkthdr(n, m);
                n->m_len = 0;                   /* NB: m_gethdr does not set */
                n->m_data += needed_space;
                /*
                 * Pull up Ethernet header to create the expected layout.
                 * We could use m_pullup but that's overkill (i.e. we don't
                 * need the actual data) and it cannot fail so do it inline
                 * for speed.
                 */
                /* NB: struct ether_header is known to be contiguous */
                n->m_len += sizeof(struct ether_header);
                m->m_len -= sizeof(struct ether_header);
                m->m_data += sizeof(struct ether_header);
                /*
                 * Replace the head of the chain.
                 */
                n->m_next = m;
                m = n;
        }
        return m;
#undef TO_BE_RECLAIMED
}

/*
 * Return the transmit key to use in sending a unicast frame.
 * If a unicast key is set we use that.  When no unicast key is set
 * we fall back to the default transmit key.
 */ 
static __inline struct ieee80211_key *
ieee80211_crypto_getucastkey(struct ieee80211vap *vap,
        struct ieee80211_node *ni)
{
        if (IEEE80211_KEY_UNDEFINED(&ni->ni_ucastkey)) {
                if (vap->iv_def_txkey == IEEE80211_KEYIX_NONE ||
                    IEEE80211_KEY_UNDEFINED(&vap->iv_nw_keys[vap->iv_def_txkey]))
                        return NULL;
                return &vap->iv_nw_keys[vap->iv_def_txkey];
        } else {
                return &ni->ni_ucastkey;
        }
}

/*
 * Return the transmit key to use in sending a multicast frame.
 * Multicast traffic always uses the group key which is installed as
 * the default tx key.
 */ 
static __inline struct ieee80211_key *
ieee80211_crypto_getmcastkey(struct ieee80211vap *vap,
        struct ieee80211_node *ni)
{
        if (vap->iv_def_txkey == IEEE80211_KEYIX_NONE ||
            IEEE80211_KEY_UNDEFINED(&vap->iv_nw_keys[vap->iv_def_txkey]))
                return NULL;
        return &vap->iv_nw_keys[vap->iv_def_txkey];
}

/*
 * Encapsulate an outbound data frame.  The mbuf chain is updated.
 * If an error is encountered NULL is returned.  The caller is required
 * to provide a node reference and pullup the ethernet header in the
 * first mbuf.
 *
 * NB: Packet is assumed to be processed by ieee80211_classify which
 *     marked EAPOL frames w/ M_EAPOL.
 */
struct mbuf *
ieee80211_encap(struct ieee80211vap *vap, struct ieee80211_node *ni,
    struct mbuf *m)
{
#define WH4(wh) ((struct ieee80211_frame_addr4 *)(wh))
#define MC01(mc)        ((struct ieee80211_meshcntl_ae01 *)mc)
        struct ieee80211com *ic = ni->ni_ic;
#ifdef IEEE80211_SUPPORT_MESH
        struct ieee80211_mesh_state *ms = vap->iv_mesh;
        struct ieee80211_meshcntl_ae10 *mc;
        struct ieee80211_mesh_route *rt = NULL;
        int dir = -1;
#endif
        struct ether_header eh;
        struct ieee80211_frame *wh;
        struct ieee80211_key *key;
        struct llc *llc;
        int hdrsize, hdrspace, datalen, addqos, txfrag, is4addr, is_mcast;
        int meshhdrsize, meshae;
        uint8_t *qos;
        int is_amsdu = 0;

        IEEE80211_TX_LOCK_ASSERT(ic);

        is_mcast = !! (m->m_flags & (M_MCAST | M_BCAST));

        /*
         * Copy existing Ethernet header to a safe place.  The
         * rest of the code assumes it's ok to strip it when
         * reorganizing state for the final encapsulation.
         */
        KASSERT(m->m_len >= sizeof(eh), ("no ethernet header!"));
        ETHER_HEADER_COPY(&eh, mtod(m, caddr_t));

        /*
         * Insure space for additional headers.  First identify
         * transmit key to use in calculating any buffer adjustments
         * required.  This is also used below to do privacy
         * encapsulation work.  Then calculate the 802.11 header
         * size and any padding required by the driver.
         *
         * Note key may be NULL if we fall back to the default
         * transmit key and that is not set.  In that case the
         * buffer may not be expanded as needed by the cipher
         * routines, but they will/should discard it.
         */
        if (vap->iv_flags & IEEE80211_F_PRIVACY) {
                if (vap->iv_opmode == IEEE80211_M_STA ||
                    !IEEE80211_IS_MULTICAST(eh.ether_dhost) ||
                    (vap->iv_opmode == IEEE80211_M_WDS &&
                     (vap->iv_flags_ext & IEEE80211_FEXT_WDSLEGACY))) {
                        key = ieee80211_crypto_getucastkey(vap, ni);
                } else if ((vap->iv_opmode == IEEE80211_M_WDS) &&
                    (! (vap->iv_flags_ext & IEEE80211_FEXT_WDSLEGACY))) {
                        /*
                         * Use ucastkey for DWDS transmit nodes, multicast
                         * or otherwise.
                         *
                         * This is required to ensure that multicast frames
                         * from a DWDS AP to a DWDS STA is encrypted with
                         * a key that can actually work.
                         *
                         * There's no default key for multicast traffic
                         * on a DWDS WDS VAP node (note NOT the DWDS enabled
                         * AP VAP, the dynamically created per-STA WDS node)
                         * so encap fails and transmit fails.
                         */
                        key = ieee80211_crypto_getucastkey(vap, ni);
                } else {
                        key = ieee80211_crypto_getmcastkey(vap, ni);
                }
                if (key == NULL && (m->m_flags & M_EAPOL) == 0) {
                        IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_CRYPTO,
                            eh.ether_dhost,
                            "no default transmit key (%s) deftxkey %u",
                            __func__, vap->iv_def_txkey);
                        vap->iv_stats.is_tx_nodefkey++;
                        goto bad;
                }
        } else
                key = NULL;
        /*
         * XXX Some ap's don't handle QoS-encapsulated EAPOL
         * frames so suppress use.  This may be an issue if other
         * ap's require all data frames to be QoS-encapsulated
         * once negotiated in which case we'll need to make this
         * configurable.
         *
         * Don't send multicast QoS frames.
         * Technically multicast frames can be QoS if all stations in the
         * BSS are also QoS.
         *
         * NB: mesh data frames are QoS, including multicast frames.
         */
        addqos =
            (((is_mcast == 0) && (ni->ni_flags &
             (IEEE80211_NODE_QOS|IEEE80211_NODE_HT))) ||
            (vap->iv_opmode == IEEE80211_M_MBSS)) &&
            (m->m_flags & M_EAPOL) == 0;

        if (addqos)
                hdrsize = sizeof(struct ieee80211_qosframe);
        else
                hdrsize = sizeof(struct ieee80211_frame);
#ifdef IEEE80211_SUPPORT_MESH
        if (vap->iv_opmode == IEEE80211_M_MBSS) {
                /*
                 * Mesh data frames are encapsulated according to the
                 * rules of Section 11B.8.5 (p.139 of D3.0 spec).
                 * o Group Addressed data (aka multicast) originating
                 *   at the local sta are sent w/ 3-address format and
                 *   address extension mode 00
                 * o Individually Addressed data (aka unicast) originating
                 *   at the local sta are sent w/ 4-address format and
                 *   address extension mode 00
                 * o Group Addressed data forwarded from a non-mesh sta are
                 *   sent w/ 3-address format and address extension mode 01
                 * o Individually Address data from another sta are sent
                 *   w/ 4-address format and address extension mode 10
                 */
                is4addr = 0;            /* NB: don't use, disable */
                if (!IEEE80211_IS_MULTICAST(eh.ether_dhost)) {
                        rt = ieee80211_mesh_rt_find(vap, eh.ether_dhost);
                        KASSERT(rt != NULL, ("route is NULL"));
                        dir = IEEE80211_FC1_DIR_DSTODS;
                        hdrsize += IEEE80211_ADDR_LEN;
                        if (rt->rt_flags & IEEE80211_MESHRT_FLAGS_PROXY) {
                                if (IEEE80211_ADDR_EQ(rt->rt_mesh_gate,
                                    vap->iv_myaddr)) {
                                        IEEE80211_NOTE_MAC(vap,
                                            IEEE80211_MSG_MESH,
                                            eh.ether_dhost,
                                            "%s", "trying to send to ourself");
                                        goto bad;
                                }
                                meshae = IEEE80211_MESH_AE_10;
                                meshhdrsize =
                                    sizeof(struct ieee80211_meshcntl_ae10);
                        } else {
                                meshae = IEEE80211_MESH_AE_00;
                                meshhdrsize =
                                    sizeof(struct ieee80211_meshcntl);
                        }
                } else {
                        dir = IEEE80211_FC1_DIR_FROMDS;
                        if (!IEEE80211_ADDR_EQ(eh.ether_shost, vap->iv_myaddr)) {
                                /* proxy group */
                                meshae = IEEE80211_MESH_AE_01;
                                meshhdrsize =
                                    sizeof(struct ieee80211_meshcntl_ae01);
                        } else {
                                /* group */
                                meshae = IEEE80211_MESH_AE_00;
                                meshhdrsize = sizeof(struct ieee80211_meshcntl);
                        }
                }
        } else {
#endif
                /*
                 * 4-address frames need to be generated for:
                 * o packets sent through a WDS vap (IEEE80211_M_WDS)
                 * o packets sent through a vap marked for relaying
                 *   (e.g. a station operating with dynamic WDS)
                 */
                is4addr = vap->iv_opmode == IEEE80211_M_WDS ||
                    ((vap->iv_flags_ext & IEEE80211_FEXT_4ADDR) &&
                     !IEEE80211_ADDR_EQ(eh.ether_shost, vap->iv_myaddr));
                if (is4addr)
                        hdrsize += IEEE80211_ADDR_LEN;
                meshhdrsize = meshae = 0;
#ifdef IEEE80211_SUPPORT_MESH
        }
#endif
        /*
         * Honor driver DATAPAD requirement.
         */
        if (ic->ic_flags & IEEE80211_F_DATAPAD)
                hdrspace = roundup(hdrsize, sizeof(uint32_t));
        else
                hdrspace = hdrsize;

        if (__predict_true((m->m_flags & M_FF) == 0)) {
                /*
                 * Normal frame.
                 */
                m = ieee80211_mbuf_adjust(vap, hdrspace + meshhdrsize, key, m);
                if (m == NULL) {
                        /* NB: ieee80211_mbuf_adjust handles msgs+statistics */
                        goto bad;
                }
                /* NB: this could be optimized 'cuz of ieee80211_mbuf_adjust */
                m_adj(m, sizeof(struct ether_header) - sizeof(struct llc));
                llc = mtod(m, struct llc *);
                llc->llc_dsap = llc->llc_ssap = LLC_SNAP_LSAP;
                llc->llc_control = LLC_UI;
                llc->llc_snap.org_code[0] = 0;
                llc->llc_snap.org_code[1] = 0;
                llc->llc_snap.org_code[2] = 0;
                llc->llc_snap.ether_type = eh.ether_type;
        } else {
#ifdef IEEE80211_SUPPORT_SUPERG
                /*
                 * Aggregated frame.  Check if it's for AMSDU or FF.
                 *
                 * XXX TODO: IEEE80211_NODE_AMSDU* isn't implemented
                 * anywhere for some reason.  But, since 11n requires
                 * AMSDU RX, we can just assume "11n" == "AMSDU".
                 */
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_SUPERG, "%s: called; M_FF\n", __func__);
                if (ieee80211_amsdu_tx_ok(ni)) {
                        m = ieee80211_amsdu_encap(vap, m, hdrspace + meshhdrsize, key);
                        is_amsdu = 1;
                } else {
                        m = ieee80211_ff_encap(vap, m, hdrspace + meshhdrsize, key);
                }
                if (m == NULL)
#endif
                        goto bad;
        }
        datalen = m->m_pkthdr.len;              /* NB: w/o 802.11 header */

        M_PREPEND(m, hdrspace + meshhdrsize, IEEE80211_M_NOWAIT);
        if (m == NULL) {
                vap->iv_stats.is_tx_nobuf++;
                goto bad;
        }
        wh = mtod(m, struct ieee80211_frame *);
        wh->i_fc[0] = IEEE80211_FC0_VERSION_0 | IEEE80211_FC0_TYPE_DATA;
        *(uint16_t *)wh->i_dur = 0;
        qos = NULL;     /* NB: quiet compiler */
        if (is4addr) {
                wh->i_fc[1] = IEEE80211_FC1_DIR_DSTODS;
                IEEE80211_ADDR_COPY(wh->i_addr1, ni->ni_macaddr);
                IEEE80211_ADDR_COPY(wh->i_addr2, vap->iv_myaddr);
                IEEE80211_ADDR_COPY(wh->i_addr3, eh.ether_dhost);
                IEEE80211_ADDR_COPY(WH4(wh)->i_addr4, eh.ether_shost);
        } else switch (vap->iv_opmode) {
        case IEEE80211_M_STA:
                wh->i_fc[1] = IEEE80211_FC1_DIR_TODS;
                IEEE80211_ADDR_COPY(wh->i_addr1, ni->ni_bssid);
                IEEE80211_ADDR_COPY(wh->i_addr2, eh.ether_shost);
                IEEE80211_ADDR_COPY(wh->i_addr3, eh.ether_dhost);
                break;
        case IEEE80211_M_IBSS:
        case IEEE80211_M_AHDEMO:
                wh->i_fc[1] = IEEE80211_FC1_DIR_NODS;
                IEEE80211_ADDR_COPY(wh->i_addr1, eh.ether_dhost);
                IEEE80211_ADDR_COPY(wh->i_addr2, eh.ether_shost);
                /*
                 * NB: always use the bssid from iv_bss as the
                 *     neighbor's may be stale after an ibss merge
                 */
                IEEE80211_ADDR_COPY(wh->i_addr3, vap->iv_bss->ni_bssid);
                break;
        case IEEE80211_M_HOSTAP:
                wh->i_fc[1] = IEEE80211_FC1_DIR_FROMDS;
                IEEE80211_ADDR_COPY(wh->i_addr1, eh.ether_dhost);
                IEEE80211_ADDR_COPY(wh->i_addr2, ni->ni_bssid);
                IEEE80211_ADDR_COPY(wh->i_addr3, eh.ether_shost);
                break;
#ifdef IEEE80211_SUPPORT_MESH
        case IEEE80211_M_MBSS:
                /* NB: offset by hdrspace to deal with DATAPAD */
                mc = (struct ieee80211_meshcntl_ae10 *)
                     (mtod(m, uint8_t *) + hdrspace);
                wh->i_fc[1] = dir;
                switch (meshae) {
                case IEEE80211_MESH_AE_00:      /* no proxy */
                        mc->mc_flags = 0;
                        if (dir == IEEE80211_FC1_DIR_DSTODS) { /* ucast */
                                IEEE80211_ADDR_COPY(wh->i_addr1,
                                    ni->ni_macaddr);
                                IEEE80211_ADDR_COPY(wh->i_addr2,
                                    vap->iv_myaddr);
                                IEEE80211_ADDR_COPY(wh->i_addr3,
                                    eh.ether_dhost);
                                IEEE80211_ADDR_COPY(WH4(wh)->i_addr4,
                                    eh.ether_shost);
                                qos =((struct ieee80211_qosframe_addr4 *)
                                    wh)->i_qos;
                        } else if (dir == IEEE80211_FC1_DIR_FROMDS) {
                                 /* mcast */
                                IEEE80211_ADDR_COPY(wh->i_addr1,
                                    eh.ether_dhost);
                                IEEE80211_ADDR_COPY(wh->i_addr2,
                                    vap->iv_myaddr);
                                IEEE80211_ADDR_COPY(wh->i_addr3,
                                    eh.ether_shost);
                                qos = ((struct ieee80211_qosframe *)
                                    wh)->i_qos;
                        }
                        break;
                case IEEE80211_MESH_AE_01:      /* mcast, proxy */
                        wh->i_fc[1] = IEEE80211_FC1_DIR_FROMDS;
                        IEEE80211_ADDR_COPY(wh->i_addr1, eh.ether_dhost);
                        IEEE80211_ADDR_COPY(wh->i_addr2, vap->iv_myaddr);
                        IEEE80211_ADDR_COPY(wh->i_addr3, vap->iv_myaddr);
                        mc->mc_flags = 1;
                        IEEE80211_ADDR_COPY(MC01(mc)->mc_addr4,
                            eh.ether_shost);
                        qos = ((struct ieee80211_qosframe *) wh)->i_qos;
                        break;
                case IEEE80211_MESH_AE_10:      /* ucast, proxy */
                        KASSERT(rt != NULL, ("route is NULL"));
                        IEEE80211_ADDR_COPY(wh->i_addr1, rt->rt_nexthop);
                        IEEE80211_ADDR_COPY(wh->i_addr2, vap->iv_myaddr);
                        IEEE80211_ADDR_COPY(wh->i_addr3, rt->rt_mesh_gate);
                        IEEE80211_ADDR_COPY(WH4(wh)->i_addr4, vap->iv_myaddr);
                        mc->mc_flags = IEEE80211_MESH_AE_10;
                        IEEE80211_ADDR_COPY(mc->mc_addr5, eh.ether_dhost);
                        IEEE80211_ADDR_COPY(mc->mc_addr6, eh.ether_shost);
                        qos = ((struct ieee80211_qosframe_addr4 *) wh)->i_qos;
                        break;
                default:
                        KASSERT(0, ("meshae %d", meshae));
                        break;
                }
                mc->mc_ttl = ms->ms_ttl;
                ms->ms_seq++;
                le32enc(mc->mc_seq, ms->ms_seq);
                break;
#endif
        case IEEE80211_M_WDS:           /* NB: is4addr should always be true */
        default:
                goto bad;
        }
        if (m->m_flags & M_MORE_DATA)
                wh->i_fc[1] |= IEEE80211_FC1_MORE_DATA;
        if (addqos) {
                int ac, tid;

                if (is4addr) {
                        qos = ((struct ieee80211_qosframe_addr4 *) wh)->i_qos;
                /* NB: mesh case handled earlier */
                } else if (vap->iv_opmode != IEEE80211_M_MBSS)
                        qos = ((struct ieee80211_qosframe *) wh)->i_qos;
                ac = M_WME_GETAC(m);
                /* map from access class/queue to 11e header priorty value */
                tid = WME_AC_TO_TID(ac);
                qos[0] = tid & IEEE80211_QOS_TID;
                if (ic->ic_wme.wme_wmeChanParams.cap_wmeParams[ac].wmep_noackPolicy)
                        qos[0] |= IEEE80211_QOS_ACKPOLICY_NOACK;
#ifdef IEEE80211_SUPPORT_MESH
                if (vap->iv_opmode == IEEE80211_M_MBSS)
                        qos[1] = IEEE80211_QOS_MC;
                else
#endif
                        qos[1] = 0;
                wh->i_fc[0] |= IEEE80211_FC0_SUBTYPE_QOS_DATA;

                /*
                 * If this is an A-MSDU then ensure we set the
                 * relevant field.
                 */
                if (is_amsdu)
                        qos[0] |= IEEE80211_QOS_AMSDU;

                /*
                 * XXX TODO TX lock is needed for atomic updates of sequence
                 * numbers.  If the driver does it, then don't do it here;
                 * and we don't need the TX lock held.
                 */
                if ((m->m_flags & M_AMPDU_MPDU) == 0) {
                        if (!IEEE80211_CONF_SEQNO_OFFLOAD(ic))
                                ieee80211_output_seqno_assign(ni, tid, m);
                } else {
                        /*
                         * NB: don't assign a sequence # to potential
                         * aggregates; we expect this happens at the
                         * point the frame comes off any aggregation q
                         * as otherwise we may introduce holes in the
                         * BA sequence space and/or make window accouting
                         * more difficult.
                         *
                         * XXX may want to control this with a driver
                         * capability; this may also change when we pull
                         * aggregation up into net80211
                         */
                        /* NB: zero out i_seq field (for s/w encryption etc) */
                        *(uint16_t *)wh->i_seq = 0;
                }
        } else {
                if (!IEEE80211_CONF_SEQNO_OFFLOAD(ic))
                        ieee80211_output_seqno_assign(ni, IEEE80211_NONQOS_TID,
                            m);
                /*
                 * XXX TODO: we shouldn't allow EAPOL, etc that would
                 * be forced to be non-QoS traffic to be A-MSDU encapsulated.
                 */
                if (is_amsdu)
                        net80211_vap_printf(vap,
                            "%s: XXX ERROR: is_amsdu set; not QoS!\n",
                            __func__);
        }

        /*
         * Check if xmit fragmentation is required.
         *
         * If the hardware does fragmentation offload, then don't bother
         * doing it here.
         *
         * Don't send AMPDU/FF/AMSDU through fragmentation.
         *
         * 802.11-2016 10.2.7 (Fragmentation/defragmentation overview)
         */
        if (IEEE80211_CONF_FRAG_OFFLOAD(ic))
                txfrag = 0;
        else
                txfrag = (m->m_pkthdr.len > vap->iv_fragthreshold &&
                    !IEEE80211_IS_MULTICAST(wh->i_addr1) &&
                    (vap->iv_caps & IEEE80211_C_TXFRAG) &&
                    (m->m_flags & (M_FF | M_AMPDU_MPDU)) == 0);

        if (key != NULL) {
                /*
                 * IEEE 802.1X: send EAPOL frames always in the clear.
                 * WPA/WPA2: encrypt EAPOL keys when pairwise keys are set.
                 */
                if ((m->m_flags & M_EAPOL) == 0 ||
                    ((vap->iv_flags & IEEE80211_F_WPA) &&
                     (vap->iv_opmode == IEEE80211_M_STA ?
                      !IEEE80211_KEY_UNDEFINED(key) :
                      !IEEE80211_KEY_UNDEFINED(&ni->ni_ucastkey)))) {
                        wh->i_fc[1] |= IEEE80211_FC1_PROTECTED;
                        if (!ieee80211_crypto_enmic(vap, key, m, txfrag)) {
                                IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_OUTPUT,
                                    eh.ether_dhost,
                                    "%s", "enmic failed, discard frame");
                                vap->iv_stats.is_crypto_enmicfail++;
                                goto bad;
                        }
                }
        }
        if (txfrag && !ieee80211_fragment(vap, m, hdrsize,
            key != NULL ? key->wk_cipher->ic_header : 0, vap->iv_fragthreshold))
                goto bad;

        m->m_flags |= M_ENCAP;          /* mark encapsulated */

        IEEE80211_NODE_STAT(ni, tx_data);
        if (IEEE80211_IS_MULTICAST(wh->i_addr1)) {
                IEEE80211_NODE_STAT(ni, tx_mcast);
                m->m_flags |= M_MCAST;
        } else
                IEEE80211_NODE_STAT(ni, tx_ucast);
        IEEE80211_NODE_STAT_ADD(ni, tx_bytes, datalen);

        return m;
bad:
        if (m != NULL)
                m_freem(m);
        return NULL;
#undef WH4
#undef MC01
}

/**
 * @brief Free an 802.11 frame mbuf.
 *
 * Note that since a "frame" may consist of an mbuf packet
 * list containing the 802.11 fragments that make up said
 * frame, it will free everything in the mbuf packet list.
 *
 * @param m     mbuf packet list to free
 */
void
ieee80211_free_mbuf(struct mbuf *m)
{
        struct mbuf *next;

        if (m == NULL)
                return;

        do {
                next = m->m_nextpkt;
                m->m_nextpkt = NULL;
                m_freem(m);
        } while ((m = next) != NULL);
}

/**
 * @brief Fragment the frame according to the specified mtu.
 *
 * This implements the fragmentation part of 802.11-2016 10.2.7
 * (Fragmentation/defragmentation overview.)
 *
 * The size of the 802.11 header (w/o padding) is provided
 * so we don't need to recalculate it.  We create a new
 * mbuf for each fragment and chain it through m_nextpkt;
 * we might be able to optimize this by reusing the original
 * packet's mbufs but that is significantly more complicated.
 *
 * A node reference is NOT acquired for each fragment in
 * the list - the caller is assumed to have taken a node
 * reference for the whole list.  The fragment mbufs do not
 * have a node pointer.
 *
 * Fragments will have the sequence number and fragment numbers
 * assigned.  However, Fragments will NOT have a sequence number
 * assigned via M_SEQNO_SET.
 *
 * This must be called after assigning sequence numbers; it
 * modifies the i_seq field in the 802.11 header to include
 * the fragment number.
 *
 * @param vap           ieee80211vap interface
 * @param m0            pointer to mbuf list to fragment
 * @param hdrsize       header size to reserver
 * @param ciphdrsize    crypto cipher header size to reserve
 * @param mtu           maximum fragment size
 * @retval 1 if successful, with the mbuf pointed at by m0
 *   turned into an mbuf list of fragments (with the original
 *   mbuf being truncated.)
 * @retval 0 if failure, the mbuf needs to be freed by the caller
 */
static int
ieee80211_fragment(struct ieee80211vap *vap, struct mbuf *m0,
        u_int hdrsize, u_int ciphdrsize, u_int mtu)
{
        struct ieee80211com *ic = vap->iv_ic;
        struct ieee80211_frame *wh, *whf;
        struct mbuf *m, *prev;
        u_int totalhdrsize, fragno, fragsize, off, remainder, payload;
        u_int hdrspace;

        KASSERT(m0->m_nextpkt == NULL, ("mbuf already chained?"));
        KASSERT(m0->m_pkthdr.len > mtu,
                ("pktlen %u mtu %u", m0->m_pkthdr.len, mtu));

        /*
         * Honor driver DATAPAD requirement.
         */
        if (ic->ic_flags & IEEE80211_F_DATAPAD)
                hdrspace = roundup(hdrsize, sizeof(uint32_t));
        else
                hdrspace = hdrsize;

        wh = mtod(m0, struct ieee80211_frame *);
        /* NB: mark the first frag; it will be propagated below */
        wh->i_fc[1] |= IEEE80211_FC1_MORE_FRAG;
        totalhdrsize = hdrspace + ciphdrsize;
        fragno = 1;
        off = mtu - ciphdrsize;
        remainder = m0->m_pkthdr.len - off;
        prev = m0;
        do {
                fragsize = MIN(totalhdrsize + remainder, mtu);
                m = m_get2(fragsize, IEEE80211_M_NOWAIT, MT_DATA, M_PKTHDR);
                if (m == NULL)
                        goto bad;
                /* leave room to prepend any cipher header */
                m_align(m, fragsize - ciphdrsize);

                /*
                 * Form the header in the fragment.  Note that since
                 * we mark the first fragment with the MORE_FRAG bit
                 * it automatically is propagated to each fragment; we
                 * need only clear it on the last fragment (done below).
                 * NB: frag 1+ dont have Mesh Control field present.
                 */
                whf = mtod(m, struct ieee80211_frame *);
                memcpy(whf, wh, hdrsize);
#ifdef IEEE80211_SUPPORT_MESH
                if (vap->iv_opmode == IEEE80211_M_MBSS)
                        ieee80211_getqos(wh)[1] &= ~IEEE80211_QOS_MC;
#endif
                *(uint16_t *)&whf->i_seq[0] |= htole16(
                        (fragno & IEEE80211_SEQ_FRAG_MASK) <<
                                IEEE80211_SEQ_FRAG_SHIFT);
                fragno++;

                payload = fragsize - totalhdrsize;
                /* NB: destination is known to be contiguous */

                m_copydata(m0, off, payload, mtod(m, uint8_t *) + hdrspace);
                m->m_len = hdrspace + payload;
                m->m_pkthdr.len = hdrspace + payload;
                m->m_flags |= M_FRAG;

                /* chain up the fragment */
                prev->m_nextpkt = m;
                prev = m;

                /* deduct fragment just formed */
                remainder -= payload;
                off += payload;
        } while (remainder != 0);

        /* set the last fragment */
        m->m_flags |= M_LASTFRAG;
        whf->i_fc[1] &= ~IEEE80211_FC1_MORE_FRAG;

        /* strip first mbuf now that everything has been copied */
        m_adj(m0, -(m0->m_pkthdr.len - (mtu - ciphdrsize)));
        m0->m_flags |= M_FIRSTFRAG | M_FRAG;

        vap->iv_stats.is_tx_fragframes++;
        vap->iv_stats.is_tx_frags += fragno-1;

        return 1;
bad:
        /* reclaim fragments but leave original frame for caller to free */
        ieee80211_free_mbuf(m0->m_nextpkt);
        m0->m_nextpkt = NULL;
        return 0;
}

/*
 * Add a supported rates element id to a frame.
 */
uint8_t *
ieee80211_add_rates(uint8_t *frm, const struct ieee80211_rateset *rs)
{
        int nrates;

        *frm++ = IEEE80211_ELEMID_RATES;
        nrates = rs->rs_nrates;
        if (nrates > IEEE80211_RATE_SIZE)
                nrates = IEEE80211_RATE_SIZE;
        *frm++ = nrates;
        memcpy(frm, rs->rs_rates, nrates);
        return frm + nrates;
}

/*
 * Add an extended supported rates element id to a frame.
 */
uint8_t *
ieee80211_add_xrates(uint8_t *frm, const struct ieee80211_rateset *rs)
{
        /*
         * Add an extended supported rates element if operating in 11g mode.
         */
        if (rs->rs_nrates > IEEE80211_RATE_SIZE) {
                int nrates = rs->rs_nrates - IEEE80211_RATE_SIZE;
                *frm++ = IEEE80211_ELEMID_XRATES;
                *frm++ = nrates;
                memcpy(frm, rs->rs_rates + IEEE80211_RATE_SIZE, nrates);
                frm += nrates;
        }
        return frm;
}

/* 
 * Add an ssid element to a frame.
 */
uint8_t *
ieee80211_add_ssid(uint8_t *frm, const uint8_t *ssid, u_int len)
{
        *frm++ = IEEE80211_ELEMID_SSID;
        *frm++ = len;
        memcpy(frm, ssid, len);
        return frm + len;
}

/*
 * Add an erp element to a frame.
 */
static uint8_t *
ieee80211_add_erp(uint8_t *frm, struct ieee80211vap *vap)
{
        struct ieee80211com *ic = vap->iv_ic;
        uint8_t erp;

        *frm++ = IEEE80211_ELEMID_ERP;
        *frm++ = 1;
        erp = 0;

        /*
         * TODO:  This uses the global flags for now because
         * the per-VAP flags are fine for per-VAP, but don't
         * take into account which VAPs share the same channel
         * and which are on different channels.
         *
         * ERP and HT/VHT protection mode is a function of
         * how many stations are on a channel, not specifically
         * the VAP or global.  But, until we grow that status,
         * the global flag will have to do.
         */
        if (ic->ic_flags_ext & IEEE80211_FEXT_NONERP_PR)
                erp |= IEEE80211_ERP_NON_ERP_PRESENT;

        /*
         * TODO: same as above; these should be based not
         * on the vap or ic flags, but instead on a combination
         * of per-VAP and channels.
         */
        if (ic->ic_flags & IEEE80211_F_USEPROT)
                erp |= IEEE80211_ERP_USE_PROTECTION;
        if (ic->ic_flags & IEEE80211_F_USEBARKER)
                erp |= IEEE80211_ERP_LONG_PREAMBLE;
        *frm++ = erp;
        return frm;
}

/*
 * Add a CFParams element to a frame.
 */
static uint8_t *
ieee80211_add_cfparms(uint8_t *frm, struct ieee80211com *ic)
{
#define ADDSHORT(frm, v) do {   \
        le16enc(frm, v);        \
        frm += 2;               \
} while (0)
        *frm++ = IEEE80211_ELEMID_CFPARMS;
        *frm++ = 6;
        *frm++ = 0;             /* CFP count */
        *frm++ = 2;             /* CFP period */
        ADDSHORT(frm, 0);       /* CFP MaxDuration (TU) */
        ADDSHORT(frm, 0);       /* CFP CurRemaining (TU) */
        return frm;
#undef ADDSHORT
}

static __inline uint8_t *
add_appie(uint8_t *frm, const struct ieee80211_appie *ie)
{
        memcpy(frm, ie->ie_data, ie->ie_len);
        return frm + ie->ie_len;
}

static __inline uint8_t *
add_ie(uint8_t *frm, const uint8_t *ie)
{
        memcpy(frm, ie, 2 + ie[1]);
        return frm + 2 + ie[1];
}

#define WME_OUI_BYTES           0x00, 0x50, 0xf2
/*
 * Add a WME information element to a frame.
 */
uint8_t *
ieee80211_add_wme_info(uint8_t *frm, struct ieee80211_wme_state *wme,
    struct ieee80211_node *ni)
{
        static const uint8_t oui[4] = { WME_OUI_BYTES, WME_OUI_TYPE };
        struct ieee80211vap *vap = ni->ni_vap;

        *frm++ = IEEE80211_ELEMID_VENDOR;
        *frm++ = sizeof(struct ieee80211_wme_info) - 2;
        memcpy(frm, oui, sizeof(oui));
        frm += sizeof(oui);
        *frm++ = WME_INFO_OUI_SUBTYPE;
        *frm++ = WME_VERSION;

        /* QoS info field depends upon operating mode */
        switch (vap->iv_opmode) {
        case IEEE80211_M_HOSTAP:
                *frm = wme->wme_bssChanParams.cap_info;
                if (vap->iv_flags_ext & IEEE80211_FEXT_UAPSD)
                        *frm |= WME_CAPINFO_UAPSD_EN;
                frm++;
                break;
        case IEEE80211_M_STA:
                /*
                 * NB: UAPSD drivers must set this up in their
                 * VAP creation method.
                 */
                *frm++ = vap->iv_uapsdinfo;
                break;
        default:
                *frm++ = 0;
                break;
        }

        return frm;
}

/*
 * Add a WME parameters element to a frame.
 */
static uint8_t *
ieee80211_add_wme_param(uint8_t *frm, struct ieee80211_wme_state *wme,
    int uapsd_enable)
{
#define ADDSHORT(frm, v) do {   \
        le16enc(frm, v);        \
        frm += 2;               \
} while (0)
        /* NB: this works 'cuz a param has an info at the front */
        static const struct ieee80211_wme_info param = {
                .wme_id         = IEEE80211_ELEMID_VENDOR,
                .wme_len        = sizeof(struct ieee80211_wme_param) - 2,
                .wme_oui        = { WME_OUI_BYTES },
                .wme_type       = WME_OUI_TYPE,
                .wme_subtype    = WME_PARAM_OUI_SUBTYPE,
                .wme_version    = WME_VERSION,
        };
        int i;

        memcpy(frm, &param, sizeof(param));
        frm += __offsetof(struct ieee80211_wme_info, wme_info);
        *frm = wme->wme_bssChanParams.cap_info; /* AC info */
        if (uapsd_enable)
                *frm |= WME_CAPINFO_UAPSD_EN;
        frm++;
        *frm++ = 0;                                     /* reserved field */
        /* XXX TODO - U-APSD bits - SP, flags below */
        for (i = 0; i < WME_NUM_AC; i++) {
                const struct wmeParams *ac =
                       &wme->wme_bssChanParams.cap_wmeParams[i];
                *frm++ = _IEEE80211_SHIFTMASK(i, WME_PARAM_ACI)
                       | _IEEE80211_SHIFTMASK(ac->wmep_acm, WME_PARAM_ACM)
                       | _IEEE80211_SHIFTMASK(ac->wmep_aifsn, WME_PARAM_AIFSN)
                       ;
                *frm++ = _IEEE80211_SHIFTMASK(ac->wmep_logcwmax,
                            WME_PARAM_LOGCWMAX)
                       | _IEEE80211_SHIFTMASK(ac->wmep_logcwmin,
                            WME_PARAM_LOGCWMIN)
                       ;
                ADDSHORT(frm, ac->wmep_txopLimit);
        }
        return frm;
#undef ADDSHORT
}
#undef WME_OUI_BYTES

/*
 * Add an 11h Power Constraint element to a frame.
 */
static uint8_t *
ieee80211_add_powerconstraint(uint8_t *frm, struct ieee80211vap *vap)
{
        const struct ieee80211_channel *c = vap->iv_bss->ni_chan;
        /* XXX per-vap tx power limit? */
        int8_t limit = vap->iv_ic->ic_txpowlimit / 2;

        frm[0] = IEEE80211_ELEMID_PWRCNSTR;
        frm[1] = 1;
        frm[2] = c->ic_maxregpower > limit ?  c->ic_maxregpower - limit : 0;
        return frm + 3;
}

/*
 * Add an 11h Power Capability element to a frame.
 */
static uint8_t *
ieee80211_add_powercapability(uint8_t *frm, const struct ieee80211_channel *c)
{
        frm[0] = IEEE80211_ELEMID_PWRCAP;
        frm[1] = 2;
        frm[2] = c->ic_minpower;
        frm[3] = c->ic_maxpower;
        return frm + 4;
}

/*
 * Add an 11h Supported Channels element to a frame.
 */
static uint8_t *
ieee80211_add_supportedchannels(uint8_t *frm, struct ieee80211com *ic)
{
        static const int ielen = 26;

        frm[0] = IEEE80211_ELEMID_SUPPCHAN;
        frm[1] = ielen;
        /* XXX not correct */
        memcpy(frm+2, ic->ic_chan_avail, ielen);
        return frm + 2 + ielen;
}

/*
 * Add an 11h Quiet time element to a frame.
 */
static uint8_t *
ieee80211_add_quiet(uint8_t *frm, struct ieee80211vap *vap, int update)
{
        struct ieee80211_quiet_ie *quiet = (struct ieee80211_quiet_ie *) frm;

        quiet->quiet_ie = IEEE80211_ELEMID_QUIET;
        quiet->len = 6;

        /*
         * Only update every beacon interval - otherwise probe responses
         * would update the quiet count value.
         */
        if (update) {
                if (vap->iv_quiet_count_value == 1)
                        vap->iv_quiet_count_value = vap->iv_quiet_count;
                else if (vap->iv_quiet_count_value > 1)
                        vap->iv_quiet_count_value--;
        }

        if (vap->iv_quiet_count_value == 0) {
                /* value 0 is reserved as per 802.11h standerd */
                vap->iv_quiet_count_value = 1;
        }

        quiet->tbttcount = vap->iv_quiet_count_value;
        quiet->period = vap->iv_quiet_period;
        quiet->duration = htole16(vap->iv_quiet_duration);
        quiet->offset = htole16(vap->iv_quiet_offset);
        return frm + sizeof(*quiet);
}

/*
 * Add an 11h Channel Switch Announcement element to a frame.
 * Note that we use the per-vap CSA count to adjust the global
 * counter so we can use this routine to form probe response
 * frames and get the current count.
 */
static uint8_t *
ieee80211_add_csa(uint8_t *frm, struct ieee80211vap *vap)
{
        struct ieee80211com *ic = vap->iv_ic;
        struct ieee80211_csa_ie *csa = (struct ieee80211_csa_ie *) frm;

        csa->csa_ie = IEEE80211_ELEMID_CSA;
        csa->csa_len = 3;
        csa->csa_mode = 1;              /* XXX force quiet on channel */
        csa->csa_newchan = ieee80211_chan2ieee(ic, ic->ic_csa_newchan);
        csa->csa_count = ic->ic_csa_count - vap->iv_csa_count;
        return frm + sizeof(*csa);
}

/*
 * Add an 11h country information element to a frame.
 */
static uint8_t *
ieee80211_add_countryie(uint8_t *frm, struct ieee80211com *ic)
{

        if (ic->ic_countryie == NULL ||
            ic->ic_countryie_chan != ic->ic_bsschan) {
                /*
                 * Handle lazy construction of ie.  This is done on
                 * first use and after a channel change that requires
                 * re-calculation.
                 */
                if (ic->ic_countryie != NULL)
                        IEEE80211_FREE(ic->ic_countryie, M_80211_NODE_IE);
                ic->ic_countryie = ieee80211_alloc_countryie(ic);
                if (ic->ic_countryie == NULL)
                        return frm;
                ic->ic_countryie_chan = ic->ic_bsschan;
        }
        return add_appie(frm, ic->ic_countryie);
}

uint8_t *
ieee80211_add_wpa(uint8_t *frm, const struct ieee80211vap *vap)
{
        if (vap->iv_flags & IEEE80211_F_WPA1 && vap->iv_wpa_ie != NULL)
                return (add_ie(frm, vap->iv_wpa_ie));
        else {
                /* XXX else complain? */
                return (frm);
        }
}

uint8_t *
ieee80211_add_rsn(uint8_t *frm, const struct ieee80211vap *vap)
{
        if (vap->iv_flags & IEEE80211_F_WPA2 && vap->iv_rsn_ie != NULL)
                return (add_ie(frm, vap->iv_rsn_ie));
        else {
                /* XXX else complain? */
                return (frm);
        }
}

uint8_t *
ieee80211_add_qos(uint8_t *frm, const struct ieee80211_node *ni)
{
        if (ni->ni_flags & IEEE80211_NODE_QOS) {
                *frm++ = IEEE80211_ELEMID_QOS;
                *frm++ = 1;
                *frm++ = 0;
        }

        return (frm);
}

/*
 * ieee80211_send_probereq(): send a probe request frame with the specified ssid
 * and any optional information element data;  some helper functions as FW based
 * HW scans need some of that information passed too.
 */
static uint32_t
ieee80211_probereq_ie_len(struct ieee80211vap *vap, struct ieee80211com *ic)
{
        const struct ieee80211_rateset *rs;

        rs = ieee80211_get_suprates(ic, ic->ic_curchan);

        /*
         * prreq frame format
         *      [tlv] ssid
         *      [tlv] supported rates
         *      [tlv] extended supported rates (if needed)
         *      [tlv] HT cap (optional)
         *      [tlv] VHT cap (optional)
         *      [tlv] WPA (optional)
         *      [tlv] user-specified ie's
         */
        return ( 2 + IEEE80211_NWID_LEN
               + 2 + IEEE80211_RATE_SIZE
               + ((rs->rs_nrates > IEEE80211_RATE_SIZE) ?
                   2 + (rs->rs_nrates - IEEE80211_RATE_SIZE) : 0)
               + (((vap->iv_opmode == IEEE80211_M_IBSS) &&
                    (vap->iv_flags_ht & IEEE80211_FHT_HT)) ?
                        sizeof(struct ieee80211_ie_htcap) : 0)
#ifdef notyet
               + sizeof(struct ieee80211_ie_htinfo)     /* XXX not needed? */
               + 2 + sizeof(struct ieee80211_vht_cap)
#endif
               + ((vap->iv_flags & IEEE80211_F_WPA1 && vap->iv_wpa_ie != NULL) ?
                   vap->iv_wpa_ie[1] : 0)
               + (vap->iv_appie_probereq != NULL ?
                   vap->iv_appie_probereq->ie_len : 0)
        );
}

int
ieee80211_probereq_ie(struct ieee80211vap *vap, struct ieee80211com *ic,
    uint8_t **frmp, uint32_t *frmlen, const uint8_t *ssid, size_t ssidlen,
    bool alloc)
{
        const struct ieee80211_rateset *rs;
        uint8_t *frm;
        uint32_t len;

        if (!alloc && (frmp == NULL || frmlen == NULL))
                return (EINVAL);

        len = ieee80211_probereq_ie_len(vap, ic);
        if (!alloc && len > *frmlen)
                return (ENOBUFS);

        /* For HW scans we usually do not pass in the SSID as IE. */
        if (ssidlen == -1)
                len -= (2 + IEEE80211_NWID_LEN);

        if (alloc) {
                frm = IEEE80211_MALLOC(len, M_80211_VAP,
                    IEEE80211_M_WAITOK | IEEE80211_M_ZERO);
                *frmp = frm;
                *frmlen = len;
        } else
                frm = *frmp;

        if (ssidlen != -1)
                frm = ieee80211_add_ssid(frm, ssid, ssidlen);
        rs = ieee80211_get_suprates(ic, ic->ic_curchan);
        frm = ieee80211_add_rates(frm, rs);
        frm = ieee80211_add_xrates(frm, rs);

        /*
         * Note: we can't use bss; we don't have one yet.
         *
         * So, we should announce our capabilities
         * in this channel mode (2g/5g), not the
         * channel details itself.
         */
        if ((vap->iv_opmode == IEEE80211_M_IBSS) &&
            (vap->iv_flags_ht & IEEE80211_FHT_HT)) {
                struct ieee80211_channel *c;

                /*
                 * Get the HT channel that we should try upgrading to.
                 * If we can do 40MHz then this'll upgrade it appropriately.
                 */
                c = ieee80211_ht_adjust_channel(ic, ic->ic_curchan,
                    vap->iv_flags_ht);
                frm = ieee80211_add_htcap_ch(frm, vap, c);
        }

        /*
         * XXX TODO: need to figure out what/how to update the
         * VHT channel.
         */
#ifdef notyet
        if (vap->iv_vht_flags & IEEE80211_FVHT_VHT) {
                struct ieee80211_channel *c;

                c = ieee80211_ht_adjust_channel(ic, ic->ic_curchan,
                    vap->iv_flags_ht);
                c = ieee80211_vht_adjust_channel(ic, c, vap->iv_vht_flags);
                frm = ieee80211_add_vhtcap_ch(frm, vap, c);
        }
#endif

        frm = ieee80211_add_wpa(frm, vap);
        if (vap->iv_appie_probereq != NULL)
                frm = add_appie(frm, vap->iv_appie_probereq);

        if (!alloc) {
                *frmp = frm;
                *frmlen = len;
        }

        return (0);
}

int
ieee80211_send_probereq(struct ieee80211_node *ni,
        const uint8_t sa[IEEE80211_ADDR_LEN],
        const uint8_t da[IEEE80211_ADDR_LEN],
        const uint8_t bssid[IEEE80211_ADDR_LEN],
        const uint8_t *ssid, size_t ssidlen)
{
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211com *ic = ni->ni_ic;
        struct ieee80211_node *bss;
        const struct ieee80211_txparam *tp;
        struct ieee80211_bpf_params params;
        struct mbuf *m;
        uint8_t *frm;
        uint32_t frmlen;
        int ret;

        bss = ieee80211_ref_node(vap->iv_bss);

        if (vap->iv_state == IEEE80211_S_CAC) {
                IEEE80211_NOTE(vap, IEEE80211_MSG_OUTPUT, ni,
                    "block %s frame in CAC state", "probe request");
                vap->iv_stats.is_tx_badstate++;
                ieee80211_free_node(bss);
                return EIO;             /* XXX */
        }

        /*
         * Hold a reference on the node so it doesn't go away until after
         * the xmit is complete all the way in the driver.  On error we
         * will remove our reference.
         */
        IEEE80211_DPRINTF(vap, IEEE80211_MSG_NODE,
                "ieee80211_ref_node (%s:%u) %p<%s> refcnt %d\n",
                __func__, __LINE__,
                ni, ether_sprintf(ni->ni_macaddr),
                ieee80211_node_refcnt(ni)+1);
        ieee80211_ref_node(ni);

        /* See comments above for entire frame format. */
        frmlen = ieee80211_probereq_ie_len(vap, ic);
        m = ieee80211_getmgtframe(&frm,
            ic->ic_headroom + sizeof(struct ieee80211_frame), frmlen);
        if (m == NULL) {
                vap->iv_stats.is_tx_nobuf++;
                ieee80211_free_node(ni);
                ieee80211_free_node(bss);
                return ENOMEM;
        }

        ret = ieee80211_probereq_ie(vap, ic, &frm, &frmlen, ssid, ssidlen,
            false);
        KASSERT(ret == 0,
            ("%s: ieee80211_probereq_ie failed: %d\n", __func__, ret));

        m->m_pkthdr.len = m->m_len = frm - mtod(m, uint8_t *);
        KASSERT(M_LEADINGSPACE(m) >= sizeof(struct ieee80211_frame),
            ("leading space %zd", M_LEADINGSPACE(m)));
        M_PREPEND(m, sizeof(struct ieee80211_frame), IEEE80211_M_NOWAIT);
        if (m == NULL) {
                /* NB: cannot happen */
                ieee80211_free_node(ni);
                ieee80211_free_node(bss);
                return ENOMEM;
        }

        IEEE80211_TX_LOCK(ic);
        ieee80211_send_setup(ni, m,
             IEEE80211_FC0_TYPE_MGT | IEEE80211_FC0_SUBTYPE_PROBE_REQ,
             IEEE80211_NONQOS_TID, sa, da, bssid);
        /* XXX power management? */
        m->m_flags |= M_ENCAP;          /* mark encapsulated */

        M_WME_SETAC(m, WME_AC_BE);

        IEEE80211_NODE_STAT(ni, tx_probereq);
        IEEE80211_NODE_STAT(ni, tx_mgmt);

        IEEE80211_DPRINTF(vap, IEEE80211_MSG_DEBUG | IEEE80211_MSG_DUMPPKTS,
            "send probe req on channel %u bssid %s sa %6D da %6D ssid \"%.*s\"\n",
            ieee80211_chan2ieee(ic, ic->ic_curchan),
            ether_sprintf(bssid),
            sa, ":",
            da, ":",
            ssidlen, ssid);

        memset(&params, 0, sizeof(params));
        params.ibp_pri = M_WME_GETAC(m);
        tp = &vap->iv_txparms[ieee80211_chan2mode(ic->ic_curchan)];
        params.ibp_rate0 = tp->mgmtrate;
        if (IEEE80211_IS_MULTICAST(da)) {
                params.ibp_flags |= IEEE80211_BPF_NOACK;
                params.ibp_try0 = 1;
        } else
                params.ibp_try0 = tp->maxretry;
        params.ibp_power = ni->ni_txpower;
        ret = ieee80211_raw_output(vap, ni, m, &params);
        IEEE80211_TX_UNLOCK(ic);
        ieee80211_free_node(bss);
        return (ret);
}

/*
 * Calculate capability information for mgt frames.
 *
 * This fills out the 16 bit capability field in various management
 * frames for non-DMG STAs.  DMG STAs are not supported.
 *
 * See 802.11-2020 9.4.1.4 (Capability Information Field) for the
 * field definitions.
 */
uint16_t
ieee80211_getcapinfo(struct ieee80211vap *vap, struct ieee80211_channel *chan)
{
        uint16_t capinfo;

        KASSERT(vap->iv_opmode != IEEE80211_M_STA, ("station mode"));

        if (vap->iv_opmode == IEEE80211_M_HOSTAP)
                capinfo = IEEE80211_CAPINFO_ESS;
        else if (vap->iv_opmode == IEEE80211_M_IBSS)
                capinfo = IEEE80211_CAPINFO_IBSS;
        else
                capinfo = 0;
        if (vap->iv_flags & IEEE80211_F_PRIVACY)
                capinfo |= IEEE80211_CAPINFO_PRIVACY;
        if ((vap->iv_flags & IEEE80211_F_SHPREAMBLE) &&
            IEEE80211_IS_CHAN_2GHZ(chan))
                capinfo |= IEEE80211_CAPINFO_SHORT_PREAMBLE;
        if (vap->iv_flags & IEEE80211_F_SHSLOT)
                capinfo |= IEEE80211_CAPINFO_SHORT_SLOTTIME;
        if (IEEE80211_IS_CHAN_5GHZ(chan) && (vap->iv_flags & IEEE80211_F_DOTH))
                capinfo |= IEEE80211_CAPINFO_SPECTRUM_MGMT;
        return capinfo;
}

/*
 * Send a management frame.  The node is for the destination (or ic_bss
 * when in station mode).  Nodes other than ic_bss have their reference
 * count bumped to reflect our use for an indeterminant time.
 */
int
ieee80211_send_mgmt(struct ieee80211_node *ni, int type, int arg)
{
#define HTFLAGS (IEEE80211_NODE_HT | IEEE80211_NODE_HTCOMPAT)
#define senderr(_x, _v) do { vap->iv_stats._v++; ret = _x; goto bad; } while (0)
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211com *ic = ni->ni_ic;
        struct ieee80211_node *bss = vap->iv_bss;
        struct ieee80211_bpf_params params;
        struct mbuf *m;
        uint8_t *frm;
        uint16_t capinfo;
        int has_challenge, is_shared_key, ret, status;

        KASSERT(ni != NULL, ("null node"));

        /*
         * Hold a reference on the node so it doesn't go away until after
         * the xmit is complete all the way in the driver.  On error we
         * will remove our reference.
         */
        IEEE80211_DPRINTF(vap, IEEE80211_MSG_NODE,
                "ieee80211_ref_node (%s:%u) %p<%s> refcnt %d\n",
                __func__, __LINE__,
                ni, ether_sprintf(ni->ni_macaddr),
                ieee80211_node_refcnt(ni)+1);
        ieee80211_ref_node(ni);

        memset(&params, 0, sizeof(params));
        switch (type) {
        case IEEE80211_FC0_SUBTYPE_AUTH:
                status = arg >> 16;
                arg &= 0xffff;
                has_challenge = ((arg == IEEE80211_AUTH_SHARED_CHALLENGE ||
                    arg == IEEE80211_AUTH_SHARED_RESPONSE) &&
                    ni->ni_challenge != NULL);

                /*
                 * Deduce whether we're doing open authentication or
                 * shared key authentication.  We do the latter if
                 * we're in the middle of a shared key authentication
                 * handshake or if we're initiating an authentication
                 * request and configured to use shared key.
                 */
                is_shared_key = has_challenge ||
                     arg >= IEEE80211_AUTH_SHARED_RESPONSE ||
                     (arg == IEEE80211_AUTH_SHARED_REQUEST &&
                      bss->ni_authmode == IEEE80211_AUTH_SHARED);

                m = ieee80211_getmgtframe(&frm,
                          ic->ic_headroom + sizeof(struct ieee80211_frame),
                          3 * sizeof(uint16_t)
                        + (has_challenge && status == IEEE80211_STATUS_SUCCESS ?
                                sizeof(uint16_t)+IEEE80211_CHALLENGE_LEN : 0));
                if (m == NULL)
                        senderr(ENOMEM, is_tx_nobuf);

                ((uint16_t *)frm)[0] =
                    (is_shared_key) ? htole16(IEEE80211_AUTH_ALG_SHARED)
                                    : htole16(IEEE80211_AUTH_ALG_OPEN);
                ((uint16_t *)frm)[1] = htole16(arg);    /* sequence number */
                ((uint16_t *)frm)[2] = htole16(status);/* status */

                if (has_challenge && status == IEEE80211_STATUS_SUCCESS) {
                        ((uint16_t *)frm)[3] =
                            htole16((IEEE80211_CHALLENGE_LEN << 8) |
                            IEEE80211_ELEMID_CHALLENGE);
                        memcpy(&((uint16_t *)frm)[4], ni->ni_challenge,
                            IEEE80211_CHALLENGE_LEN);
                        m->m_pkthdr.len = m->m_len =
                                4 * sizeof(uint16_t) + IEEE80211_CHALLENGE_LEN;
                        if (arg == IEEE80211_AUTH_SHARED_RESPONSE) {
                                IEEE80211_NOTE(vap, IEEE80211_MSG_AUTH, ni,
                                    "request encrypt frame (%s)", __func__);
                                /* mark frame for encryption */
                                params.ibp_flags |= IEEE80211_BPF_CRYPTO;
                        }
                } else
                        m->m_pkthdr.len = m->m_len = 3 * sizeof(uint16_t);

                /* XXX not right for shared key */
                if (status == IEEE80211_STATUS_SUCCESS)
                        IEEE80211_NODE_STAT(ni, tx_auth);
                else
                        IEEE80211_NODE_STAT(ni, tx_auth_fail);

                if (vap->iv_opmode == IEEE80211_M_STA)
                        ieee80211_add_callback(m, ieee80211_tx_mgt_cb,
                                (void *) vap->iv_state);
                break;

        case IEEE80211_FC0_SUBTYPE_DEAUTH:
                IEEE80211_NOTE(vap, IEEE80211_MSG_AUTH, ni,
                    "send station deauthenticate (reason: %d (%s))", arg,
                    ieee80211_reason_to_string(arg));
                m = ieee80211_getmgtframe(&frm,
                        ic->ic_headroom + sizeof(struct ieee80211_frame),
                        sizeof(uint16_t));
                if (m == NULL)
                        senderr(ENOMEM, is_tx_nobuf);
                *(uint16_t *)frm = htole16(arg);        /* reason */
                m->m_pkthdr.len = m->m_len = sizeof(uint16_t);

                IEEE80211_NODE_STAT(ni, tx_deauth);
                IEEE80211_NODE_STAT_SET(ni, tx_deauth_code, arg);

                ieee80211_node_unauthorize(ni);         /* port closed */
                break;

        case IEEE80211_FC0_SUBTYPE_ASSOC_REQ:
        case IEEE80211_FC0_SUBTYPE_REASSOC_REQ:
                /*
                 * asreq frame format
                 *      [2] capability information
                 *      [2] listen interval
                 *      [6*] current AP address (reassoc only)
                 *      [tlv] ssid
                 *      [tlv] supported rates
                 *      [tlv] extended supported rates
                 *      [4] power capability (optional)
                 *      [28] supported channels (optional)
                 *      [tlv] HT capabilities
                 *      [tlv] VHT capabilities
                 *      [tlv] WME (optional)
                 *      [tlv] Vendor OUI HT capabilities (optional)
                 *      [tlv] Atheros capabilities (if negotiated)
                 *      [tlv] AppIE's (optional)
                 */
                m = ieee80211_getmgtframe(&frm,
                         ic->ic_headroom + sizeof(struct ieee80211_frame),
                         sizeof(uint16_t)
                       + sizeof(uint16_t)
                       + IEEE80211_ADDR_LEN
                       + 2 + IEEE80211_NWID_LEN
                       + 2 + IEEE80211_RATE_SIZE
                       + 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE)
                       + 4
                       + 2 + 26
                       + sizeof(struct ieee80211_wme_info)
                       + sizeof(struct ieee80211_ie_htcap)
                       + 2 + sizeof(struct ieee80211_vht_cap)
                       + 4 + sizeof(struct ieee80211_ie_htcap)
#ifdef IEEE80211_SUPPORT_SUPERG
                       + sizeof(struct ieee80211_ath_ie)
#endif
                       + (vap->iv_appie_wpa != NULL ?
                                vap->iv_appie_wpa->ie_len : 0)
                       + (vap->iv_appie_assocreq != NULL ?
                                vap->iv_appie_assocreq->ie_len : 0)
                );
                if (m == NULL)
                        senderr(ENOMEM, is_tx_nobuf);

                KASSERT(vap->iv_opmode == IEEE80211_M_STA,
                    ("wrong mode %u", vap->iv_opmode));
                capinfo = IEEE80211_CAPINFO_ESS;
                if (vap->iv_flags & IEEE80211_F_PRIVACY)
                        capinfo |= IEEE80211_CAPINFO_PRIVACY;
                /*
                 * NB: Some 11a AP's reject the request when
                 *     short preamble is set.
                 */
                if ((vap->iv_flags & IEEE80211_F_SHPREAMBLE) &&
                    IEEE80211_IS_CHAN_2GHZ(ic->ic_curchan))
                        capinfo |= IEEE80211_CAPINFO_SHORT_PREAMBLE;
                if (IEEE80211_IS_CHAN_ANYG(ic->ic_curchan) &&
                    (ic->ic_caps & IEEE80211_C_SHSLOT))
                        capinfo |= IEEE80211_CAPINFO_SHORT_SLOTTIME;
                if ((ni->ni_capinfo & IEEE80211_CAPINFO_SPECTRUM_MGMT) &&
                    (vap->iv_flags & IEEE80211_F_DOTH))
                        capinfo |= IEEE80211_CAPINFO_SPECTRUM_MGMT;
                *(uint16_t *)frm = htole16(capinfo);
                frm += 2;

                KASSERT(bss->ni_intval != 0, ("beacon interval is zero!"));
                *(uint16_t *)frm = htole16(howmany(ic->ic_lintval,
                                                    bss->ni_intval));
                frm += 2;

                if (type == IEEE80211_FC0_SUBTYPE_REASSOC_REQ) {
                        IEEE80211_ADDR_COPY(frm, bss->ni_bssid);
                        frm += IEEE80211_ADDR_LEN;
                }

                frm = ieee80211_add_ssid(frm, ni->ni_essid, ni->ni_esslen);
                frm = ieee80211_add_rates(frm, &ni->ni_rates);
                frm = ieee80211_add_rsn(frm, vap);
                frm = ieee80211_add_xrates(frm, &ni->ni_rates);
                if (capinfo & IEEE80211_CAPINFO_SPECTRUM_MGMT) {
                        frm = ieee80211_add_powercapability(frm,
                            ic->ic_curchan);
                        frm = ieee80211_add_supportedchannels(frm, ic);
                }

                /*
                 * Check the channel - we may be using an 11n NIC with an
                 * 11n capable station, but we're configured to be an 11b
                 * channel.
                 */
                if ((vap->iv_flags_ht & IEEE80211_FHT_HT) &&
                    IEEE80211_IS_CHAN_HT(ni->ni_chan) &&
                    ni->ni_ies.htcap_ie != NULL &&
                    ni->ni_ies.htcap_ie[0] == IEEE80211_ELEMID_HTCAP) {
                        frm = ieee80211_add_htcap(frm, ni);
                }

                if ((vap->iv_vht_flags & IEEE80211_FVHT_VHT) &&
                    IEEE80211_IS_CHAN_VHT(ni->ni_chan) &&
                    ni->ni_ies.vhtcap_ie != NULL &&
                    ni->ni_ies.vhtcap_ie[0] == IEEE80211_ELEMID_VHT_CAP) {
                        frm = ieee80211_add_vhtcap(frm, ni);
                }

                frm = ieee80211_add_wpa(frm, vap);
                if ((vap->iv_flags & IEEE80211_F_WME) &&
                    ni->ni_ies.wme_ie != NULL)
                        frm = ieee80211_add_wme_info(frm, &ic->ic_wme, ni);

                /*
                 * Same deal - only send HT info if we're on an 11n
                 * capable channel.
                 */
                if ((vap->iv_flags_ht & IEEE80211_FHT_HT) &&
                    IEEE80211_IS_CHAN_HT(ni->ni_chan) &&
                    ni->ni_ies.htcap_ie != NULL &&
                    ni->ni_ies.htcap_ie[0] == IEEE80211_ELEMID_VENDOR) {
                        frm = ieee80211_add_htcap_vendor(frm, ni);
                }
#ifdef IEEE80211_SUPPORT_SUPERG
                if (IEEE80211_ATH_CAP(vap, ni, IEEE80211_F_ATHEROS)) {
                        frm = ieee80211_add_ath(frm, 
                                IEEE80211_ATH_CAP(vap, ni, IEEE80211_F_ATHEROS),
                                ((vap->iv_flags & IEEE80211_F_WPA) == 0 &&
                                 ni->ni_authmode != IEEE80211_AUTH_8021X) ?
                                vap->iv_def_txkey : IEEE80211_KEYIX_NONE);
                }
#endif /* IEEE80211_SUPPORT_SUPERG */
                if (vap->iv_appie_assocreq != NULL)
                        frm = add_appie(frm, vap->iv_appie_assocreq);
                m->m_pkthdr.len = m->m_len = frm - mtod(m, uint8_t *);

                ieee80211_add_callback(m, ieee80211_tx_mgt_cb,
                        (void *) vap->iv_state);
                break;

        case IEEE80211_FC0_SUBTYPE_ASSOC_RESP:
        case IEEE80211_FC0_SUBTYPE_REASSOC_RESP:
                /*
                 * asresp frame format
                 *      [2] capability information
                 *      [2] status
                 *      [2] association ID
                 *      [tlv] supported rates
                 *      [tlv] extended supported rates
                 *      [tlv] HT capabilities (standard, if STA enabled)
                 *      [tlv] HT information (standard, if STA enabled)
                 *      [tlv] VHT capabilities (standard, if STA enabled)
                 *      [tlv] VHT information (standard, if STA enabled)
                 *      [tlv] WME (if configured and STA enabled)
                 *      [tlv] HT capabilities (vendor OUI, if STA enabled)
                 *      [tlv] HT information (vendor OUI, if STA enabled)
                 *      [tlv] Atheros capabilities (if STA enabled)
                 *      [tlv] AppIE's (optional)
                 */
                m = ieee80211_getmgtframe(&frm,
                         ic->ic_headroom + sizeof(struct ieee80211_frame),
                         sizeof(uint16_t)
                       + sizeof(uint16_t)
                       + sizeof(uint16_t)
                       + 2 + IEEE80211_RATE_SIZE
                       + 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE)
                       + sizeof(struct ieee80211_ie_htcap) + 4
                       + sizeof(struct ieee80211_ie_htinfo) + 4
                       + 2 + sizeof(struct ieee80211_vht_cap)
                       + 2 + sizeof(struct ieee80211_vht_operation)
                       + sizeof(struct ieee80211_wme_param)
#ifdef IEEE80211_SUPPORT_SUPERG
                       + sizeof(struct ieee80211_ath_ie)
#endif
                       + (vap->iv_appie_assocresp != NULL ?
                                vap->iv_appie_assocresp->ie_len : 0)
                );
                if (m == NULL)
                        senderr(ENOMEM, is_tx_nobuf);

                capinfo = ieee80211_getcapinfo(vap, bss->ni_chan);
                *(uint16_t *)frm = htole16(capinfo);
                frm += 2;

                *(uint16_t *)frm = htole16(arg);        /* status */
                frm += 2;

                if (arg == IEEE80211_STATUS_SUCCESS) {
                        *(uint16_t *)frm = htole16(ni->ni_associd);
                        IEEE80211_NODE_STAT(ni, tx_assoc);
                } else
                        IEEE80211_NODE_STAT(ni, tx_assoc_fail);
                frm += 2;

                frm = ieee80211_add_rates(frm, &ni->ni_rates);
                frm = ieee80211_add_xrates(frm, &ni->ni_rates);
                /* NB: respond according to what we received */
                if ((ni->ni_flags & HTFLAGS) == IEEE80211_NODE_HT) {
                        frm = ieee80211_add_htcap(frm, ni);
                        frm = ieee80211_add_htinfo(frm, ni);
                }
                if ((vap->iv_flags & IEEE80211_F_WME) &&
                    ni->ni_ies.wme_ie != NULL)
                        frm = ieee80211_add_wme_param(frm, &ic->ic_wme,
                            !! (vap->iv_flags_ext & IEEE80211_FEXT_UAPSD));
                if ((ni->ni_flags & HTFLAGS) == HTFLAGS) {
                        frm = ieee80211_add_htcap_vendor(frm, ni);
                        frm = ieee80211_add_htinfo_vendor(frm, ni);
                }
                if (ni->ni_flags & IEEE80211_NODE_VHT) {
                        frm = ieee80211_add_vhtcap(frm, ni);
                        frm = ieee80211_add_vhtinfo(frm, ni);
                }
#ifdef IEEE80211_SUPPORT_SUPERG
                if (IEEE80211_ATH_CAP(vap, ni, IEEE80211_F_ATHEROS))
                        frm = ieee80211_add_ath(frm, 
                                IEEE80211_ATH_CAP(vap, ni, IEEE80211_F_ATHEROS),
                                ((vap->iv_flags & IEEE80211_F_WPA) == 0 &&
                                 ni->ni_authmode != IEEE80211_AUTH_8021X) ?
                                vap->iv_def_txkey : IEEE80211_KEYIX_NONE);
#endif /* IEEE80211_SUPPORT_SUPERG */
                if (vap->iv_appie_assocresp != NULL)
                        frm = add_appie(frm, vap->iv_appie_assocresp);
                m->m_pkthdr.len = m->m_len = frm - mtod(m, uint8_t *);
                break;

        case IEEE80211_FC0_SUBTYPE_DISASSOC:
                IEEE80211_NOTE(vap, IEEE80211_MSG_ASSOC, ni,
                    "send station disassociate (reason: %d (%s))", arg,
                    ieee80211_reason_to_string(arg));
                m = ieee80211_getmgtframe(&frm,
                        ic->ic_headroom + sizeof(struct ieee80211_frame),
                        sizeof(uint16_t));
                if (m == NULL)
                        senderr(ENOMEM, is_tx_nobuf);
                *(uint16_t *)frm = htole16(arg);        /* reason */
                m->m_pkthdr.len = m->m_len = sizeof(uint16_t);

                IEEE80211_NODE_STAT(ni, tx_disassoc);
                IEEE80211_NODE_STAT_SET(ni, tx_disassoc_code, arg);
                break;

        default:
                IEEE80211_NOTE(vap, IEEE80211_MSG_ANY, ni,
                    "invalid mgmt frame type %u", type);
                senderr(EINVAL, is_tx_unknownmgt);
                /* NOTREACHED */
        }

        /* NB: force non-ProbeResp frames to the highest queue */
        params.ibp_pri = WME_AC_VO;
        params.ibp_rate0 = bss->ni_txparms->mgmtrate;
        /* NB: we know all frames are unicast */
        params.ibp_try0 = bss->ni_txparms->maxretry;
        params.ibp_power = bss->ni_txpower;
        return ieee80211_mgmt_output(ni, m, type, &params);
bad:
        ieee80211_free_node(ni);
        return ret;
#undef senderr
#undef HTFLAGS
}

/*
 * Return an mbuf with a probe response frame in it.
 * Space is left to prepend and 802.11 header at the
 * front but it's left to the caller to fill in.
 */
struct mbuf *
ieee80211_alloc_proberesp(struct ieee80211_node *bss, int legacy)
{
        struct ieee80211vap *vap = bss->ni_vap;
        struct ieee80211com *ic = bss->ni_ic;
        const struct ieee80211_rateset *rs;
        struct mbuf *m;
        uint16_t capinfo;
        uint8_t *frm;

        /*
         * probe response frame format
         *      [8] time stamp
         *      [2] beacon interval
         *      [2] cabability information
         *      [tlv] ssid
         *      [tlv] supported rates
         *      [tlv] parameter set (FH/DS)
         *      [tlv] parameter set (IBSS)
         *      [tlv] country (optional)
         *      [3] power control (optional)
         *      [5] channel switch announcement (CSA) (optional)
         *      [tlv] extended rate phy (ERP)
         *      [tlv] extended supported rates
         *      [tlv] RSN (optional)
         *      [tlv] HT capabilities
         *      [tlv] HT information
         *      [tlv] VHT capabilities
         *      [tlv] VHT information
         *      [tlv] WPA (optional)
         *      [tlv] WME (optional)
         *      [tlv] Vendor OUI HT capabilities (optional)
         *      [tlv] Vendor OUI HT information (optional)
         *      [tlv] Atheros capabilities
         *      [tlv] AppIE's (optional)
         *      [tlv] Mesh ID (MBSS)
         *      [tlv] Mesh Conf (MBSS)
         */
        m = ieee80211_getmgtframe(&frm,
                 ic->ic_headroom + sizeof(struct ieee80211_frame),
                 8
               + sizeof(uint16_t)
               + sizeof(uint16_t)
               + 2 + IEEE80211_NWID_LEN
               + 2 + IEEE80211_RATE_SIZE
               + 7      /* max(7,3) */
               + IEEE80211_COUNTRY_MAX_SIZE
               + 3
               + sizeof(struct ieee80211_csa_ie)
               + sizeof(struct ieee80211_quiet_ie)
               + 3
               + 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE)
               + sizeof(struct ieee80211_ie_wpa)
               + sizeof(struct ieee80211_ie_htcap)
               + sizeof(struct ieee80211_ie_htinfo)
               + sizeof(struct ieee80211_ie_wpa)
               + sizeof(struct ieee80211_wme_param)
               + 4 + sizeof(struct ieee80211_ie_htcap)
               + 4 + sizeof(struct ieee80211_ie_htinfo)
               + 2 + sizeof(struct ieee80211_vht_cap)
               + 2 + sizeof(struct ieee80211_vht_operation)
#ifdef IEEE80211_SUPPORT_SUPERG
               + sizeof(struct ieee80211_ath_ie)
#endif
#ifdef IEEE80211_SUPPORT_MESH
               + 2 + IEEE80211_MESHID_LEN
               + sizeof(struct ieee80211_meshconf_ie)
#endif
               + (vap->iv_appie_proberesp != NULL ?
                        vap->iv_appie_proberesp->ie_len : 0)
        );
        if (m == NULL) {
                vap->iv_stats.is_tx_nobuf++;
                return NULL;
        }

        memset(frm, 0, 8);      /* timestamp should be filled later */
        frm += 8;
        *(uint16_t *)frm = htole16(bss->ni_intval);
        frm += 2;
        capinfo = ieee80211_getcapinfo(vap, bss->ni_chan);
        *(uint16_t *)frm = htole16(capinfo);
        frm += 2;

        frm = ieee80211_add_ssid(frm, bss->ni_essid, bss->ni_esslen);
        rs = ieee80211_get_suprates(ic, bss->ni_chan);
        frm = ieee80211_add_rates(frm, rs);

        if (IEEE80211_IS_CHAN_FHSS(bss->ni_chan)) {
                *frm++ = IEEE80211_ELEMID_FHPARMS;
                *frm++ = 5;
                *frm++ = bss->ni_fhdwell & 0x00ff;
                *frm++ = (bss->ni_fhdwell >> 8) & 0x00ff;
                *frm++ = IEEE80211_FH_CHANSET(
                    ieee80211_chan2ieee(ic, bss->ni_chan));
                *frm++ = IEEE80211_FH_CHANPAT(
                    ieee80211_chan2ieee(ic, bss->ni_chan));
                *frm++ = bss->ni_fhindex;
        } else {
                *frm++ = IEEE80211_ELEMID_DSPARMS;
                *frm++ = 1;
                *frm++ = ieee80211_chan2ieee(ic, bss->ni_chan);
        }

        if (vap->iv_opmode == IEEE80211_M_IBSS) {
                *frm++ = IEEE80211_ELEMID_IBSSPARMS;
                *frm++ = 2;
                *frm++ = 0; *frm++ = 0;         /* TODO: ATIM window */
        }
        if ((vap->iv_flags & IEEE80211_F_DOTH) ||
            (vap->iv_flags_ext & IEEE80211_FEXT_DOTD))
                frm = ieee80211_add_countryie(frm, ic);
        if (vap->iv_flags & IEEE80211_F_DOTH) {
                if (IEEE80211_IS_CHAN_5GHZ(bss->ni_chan))
                        frm = ieee80211_add_powerconstraint(frm, vap);
                if (ic->ic_flags & IEEE80211_F_CSAPENDING)
                        frm = ieee80211_add_csa(frm, vap);
        }
        if (vap->iv_flags & IEEE80211_F_DOTH) {
                if (IEEE80211_IS_CHAN_DFS(ic->ic_bsschan) &&
                    (vap->iv_flags_ext & IEEE80211_FEXT_DFS)) {
                        if (vap->iv_quiet)
                                frm = ieee80211_add_quiet(frm, vap, 0);
                }
        }
        if (IEEE80211_IS_CHAN_ANYG(bss->ni_chan))
                frm = ieee80211_add_erp(frm, vap);
        frm = ieee80211_add_xrates(frm, rs);
        frm = ieee80211_add_rsn(frm, vap);
        /*
         * NB: legacy 11b clients do not get certain ie's.
         *     The caller identifies such clients by passing
         *     a token in legacy to us.  Could expand this to be
         *     any legacy client for stuff like HT ie's.
         */
        if (IEEE80211_IS_CHAN_HT(bss->ni_chan) &&
            legacy != IEEE80211_SEND_LEGACY_11B) {
                frm = ieee80211_add_htcap(frm, bss);
                frm = ieee80211_add_htinfo(frm, bss);
        }
        if (IEEE80211_IS_CHAN_VHT(bss->ni_chan) &&
            legacy != IEEE80211_SEND_LEGACY_11B) {
                frm = ieee80211_add_vhtcap(frm, bss);
                frm = ieee80211_add_vhtinfo(frm, bss);
        }
        frm = ieee80211_add_wpa(frm, vap);
        if (vap->iv_flags & IEEE80211_F_WME)
                frm = ieee80211_add_wme_param(frm, &ic->ic_wme,
                    !! (vap->iv_flags_ext & IEEE80211_FEXT_UAPSD));
        if (IEEE80211_IS_CHAN_HT(bss->ni_chan) &&
            (vap->iv_flags_ht & IEEE80211_FHT_HTCOMPAT) &&
            legacy != IEEE80211_SEND_LEGACY_11B) {
                frm = ieee80211_add_htcap_vendor(frm, bss);
                frm = ieee80211_add_htinfo_vendor(frm, bss);
        }
#ifdef IEEE80211_SUPPORT_SUPERG
        if ((vap->iv_flags & IEEE80211_F_ATHEROS) &&
            legacy != IEEE80211_SEND_LEGACY_11B)
                frm = ieee80211_add_athcaps(frm, bss);
#endif
        if (vap->iv_appie_proberesp != NULL)
                frm = add_appie(frm, vap->iv_appie_proberesp);
#ifdef IEEE80211_SUPPORT_MESH
        if (vap->iv_opmode == IEEE80211_M_MBSS) {
                frm = ieee80211_add_meshid(frm, vap);
                frm = ieee80211_add_meshconf(frm, vap);
        }
#endif
        m->m_pkthdr.len = m->m_len = frm - mtod(m, uint8_t *);

        return m;
}

/*
 * Send a probe response frame to the specified mac address.
 * This does not go through the normal mgt frame api so we
 * can specify the destination address and re-use the bss node
 * for the sta reference.
 */
int
ieee80211_send_proberesp(struct ieee80211vap *vap,
        const uint8_t da[IEEE80211_ADDR_LEN], int legacy)
{
        struct ieee80211_node *bss = vap->iv_bss;
        struct ieee80211com *ic = vap->iv_ic;
        struct mbuf *m;
        int ret;

        if (vap->iv_state == IEEE80211_S_CAC) {
                IEEE80211_NOTE(vap, IEEE80211_MSG_OUTPUT, bss,
                    "block %s frame in CAC state", "probe response");
                vap->iv_stats.is_tx_badstate++;
                return EIO;             /* XXX */
        }

        /*
         * Hold a reference on the node so it doesn't go away until after
         * the xmit is complete all the way in the driver.  On error we
         * will remove our reference.
         */
        IEEE80211_DPRINTF(vap, IEEE80211_MSG_NODE,
            "ieee80211_ref_node (%s:%u) %p<%s> refcnt %d\n",
            __func__, __LINE__, bss, ether_sprintf(bss->ni_macaddr),
            ieee80211_node_refcnt(bss)+1);
        ieee80211_ref_node(bss);

        m = ieee80211_alloc_proberesp(bss, legacy);
        if (m == NULL) {
                ieee80211_free_node(bss);
                return ENOMEM;
        }

        M_PREPEND(m, sizeof(struct ieee80211_frame), IEEE80211_M_NOWAIT);
        KASSERT(m != NULL, ("no room for header"));

        IEEE80211_TX_LOCK(ic);
        ieee80211_send_setup(bss, m,
             IEEE80211_FC0_TYPE_MGT | IEEE80211_FC0_SUBTYPE_PROBE_RESP,
             IEEE80211_NONQOS_TID, vap->iv_myaddr, da, bss->ni_bssid);
        /* XXX power management? */
        m->m_flags |= M_ENCAP;          /* mark encapsulated */

        M_WME_SETAC(m, WME_AC_BE);

        IEEE80211_DPRINTF(vap, IEEE80211_MSG_DEBUG | IEEE80211_MSG_DUMPPKTS,
            "send probe resp on channel %u to %s%s\n",
            ieee80211_chan2ieee(ic, ic->ic_curchan), ether_sprintf(da),
            legacy ? " <legacy>" : "");
        IEEE80211_NODE_STAT(bss, tx_mgmt);

        ret = ieee80211_raw_output(vap, bss, m, NULL);
        IEEE80211_TX_UNLOCK(ic);
        return (ret);
}

/*
 * Allocate and build a RTS (Request To Send) control frame.
 */
struct mbuf *
ieee80211_alloc_rts(struct ieee80211com *ic,
        const uint8_t ra[IEEE80211_ADDR_LEN],
        const uint8_t ta[IEEE80211_ADDR_LEN],
        uint16_t dur)
{
        struct ieee80211_frame_rts *rts;
        struct mbuf *m;

        /* XXX honor ic_headroom */
        m = m_gethdr(IEEE80211_M_NOWAIT, MT_DATA);
        if (m != NULL) {
                rts = mtod(m, struct ieee80211_frame_rts *);
                rts->i_fc[0] = IEEE80211_FC0_VERSION_0 |
                        IEEE80211_FC0_TYPE_CTL | IEEE80211_FC0_SUBTYPE_RTS;
                rts->i_fc[1] = IEEE80211_FC1_DIR_NODS;
                *(u_int16_t *)rts->i_dur = htole16(dur);
                IEEE80211_ADDR_COPY(rts->i_ra, ra);
                IEEE80211_ADDR_COPY(rts->i_ta, ta);

                m->m_pkthdr.len = m->m_len = sizeof(struct ieee80211_frame_rts);
        }
        return m;
}

/*
 * Allocate and build a CTS (Clear To Send) control frame.
 */
struct mbuf *
ieee80211_alloc_cts(struct ieee80211com *ic,
        const uint8_t ra[IEEE80211_ADDR_LEN], uint16_t dur)
{
        struct ieee80211_frame_cts *cts;
        struct mbuf *m;

        /* XXX honor ic_headroom */
        m = m_gethdr(IEEE80211_M_NOWAIT, MT_DATA);
        if (m != NULL) {
                cts = mtod(m, struct ieee80211_frame_cts *);
                cts->i_fc[0] = IEEE80211_FC0_VERSION_0 |
                        IEEE80211_FC0_TYPE_CTL | IEEE80211_FC0_SUBTYPE_CTS;
                cts->i_fc[1] = IEEE80211_FC1_DIR_NODS;
                *(u_int16_t *)cts->i_dur = htole16(dur);
                IEEE80211_ADDR_COPY(cts->i_ra, ra);

                m->m_pkthdr.len = m->m_len = sizeof(struct ieee80211_frame_cts);
        }
        return m;
}

/*
 * Wrapper for CTS/RTS frame allocation.
 */
struct mbuf *
ieee80211_alloc_prot(struct ieee80211_node *ni, const struct mbuf *m,
    uint8_t rate, int prot)
{
        struct ieee80211com *ic = ni->ni_ic;
        struct ieee80211vap *vap = ni->ni_vap;
        const struct ieee80211_frame *wh;
        struct mbuf *mprot;
        uint16_t dur;
        int pktlen, isshort;

        KASSERT(prot == IEEE80211_PROT_RTSCTS ||
            prot == IEEE80211_PROT_CTSONLY,
            ("wrong protection type %d", prot));

        wh = mtod(m, const struct ieee80211_frame *);
        pktlen = m->m_pkthdr.len + IEEE80211_CRC_LEN;
        isshort = (vap->iv_flags & IEEE80211_F_SHPREAMBLE) != 0;
        dur = ieee80211_compute_duration(ic->ic_rt, pktlen, rate, isshort)
            + ieee80211_ack_duration(ic->ic_rt, rate, isshort);

        if (prot == IEEE80211_PROT_RTSCTS) {
                /* NB: CTS is the same size as an ACK */
                dur += ieee80211_ack_duration(ic->ic_rt, rate, isshort);
                mprot = ieee80211_alloc_rts(ic, wh->i_addr1, wh->i_addr2, dur);
        } else
                mprot = ieee80211_alloc_cts(ic, vap->iv_myaddr, dur);

        return (mprot);
}

static void
ieee80211_tx_mgt_timeout(void *arg)
{
        struct ieee80211vap *vap = arg;

        IEEE80211_DPRINTF(vap, IEEE80211_MSG_STATE | IEEE80211_MSG_DEBUG,
            "vap %p mode %s state %s flags %#x & %#x\n", vap,
            ieee80211_opmode_name[vap->iv_opmode],
            ieee80211_state_name[vap->iv_state],
            vap->iv_ic->ic_flags, IEEE80211_F_SCAN);

        IEEE80211_LOCK(vap->iv_ic);
        if (vap->iv_state != IEEE80211_S_INIT &&
            (vap->iv_ic->ic_flags & IEEE80211_F_SCAN) == 0) {
                /*
                 * NB: it's safe to specify a timeout as the reason here;
                 *     it'll only be used in the right state.
                 */
                ieee80211_new_state_locked(vap, IEEE80211_S_SCAN,
                        IEEE80211_SCAN_FAIL_TIMEOUT);
        }
        IEEE80211_UNLOCK(vap->iv_ic);
}

/*
 * This is the callback set on net80211-sourced transmitted
 * authentication request frames.
 *
 * This does a couple of things:
 *
 * + If the frame transmitted was a success, it schedules a future
 *   event which will transition the interface to scan.
 *   If a state transition _then_ occurs before that event occurs,
 *   said state transition will cancel this callout.
 *
 * + If the frame transmit was a failure, it immediately schedules
 *   the transition back to scan.
 */
static void
ieee80211_tx_mgt_cb(struct ieee80211_node *ni, void *arg, int status)
{
        struct ieee80211vap *vap = ni->ni_vap;
        enum ieee80211_state ostate = (enum ieee80211_state)(uintptr_t)arg;

        /*
         * Frame transmit completed; arrange timer callback.  If
         * transmit was successfully we wait for response.  Otherwise
         * we arrange an immediate callback instead of doing the
         * callback directly since we don't know what state the driver
         * is in (e.g. what locks it is holding).  This work should
         * not be too time-critical and not happen too often so the
         * added overhead is acceptable.
         *
         * XXX what happens if !acked but response shows up before callback?
         */
        if (vap->iv_state == ostate) {
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_STATE | IEEE80211_MSG_DEBUG,
                    "ni %p mode %s state %s arg %p status %d\n", ni,
                    ieee80211_opmode_name[vap->iv_opmode],
                    ieee80211_state_name[vap->iv_state], arg, status);

                callout_reset(&vap->iv_mgtsend,
                        status == 0 ? IEEE80211_TRANS_WAIT*hz : 0,
                        ieee80211_tx_mgt_timeout, vap);
        }
}

static void
ieee80211_beacon_construct(struct mbuf *m, uint8_t *frm,
        struct ieee80211_node *ni)
{
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211_beacon_offsets *bo = &vap->iv_bcn_off;
        struct ieee80211com *ic = ni->ni_ic;
        struct ieee80211_rateset *rs = &ni->ni_rates;
        uint16_t capinfo;

        /*
         * beacon frame format
         *
         * TODO: update to 802.11-2012; a lot of stuff has changed;
         * vendor extensions should be at the end, etc.
         *
         *      [8] time stamp
         *      [2] beacon interval
         *      [2] cabability information
         *      [tlv] ssid
         *      [tlv] supported rates
         *      [3] parameter set (DS)
         *      [8] CF parameter set (optional)
         *      [tlv] parameter set (IBSS/TIM)
         *      [tlv] country (optional)
         *      [3] power control (optional)
         *      [5] channel switch announcement (CSA) (optional)
         * XXX TODO: Quiet
         * XXX TODO: IBSS DFS
         * XXX TODO: TPC report
         *      [tlv] extended rate phy (ERP)
         *      [tlv] extended supported rates
         *      [tlv] RSN parameters
         * XXX TODO: BSSLOAD
         * (XXX EDCA parameter set, QoS capability?)
         * XXX TODO: AP channel report
         *
         *      [tlv] HT capabilities
         *      [tlv] HT information
         *      XXX TODO: 20/40 BSS coexistence
         * Mesh:
         * XXX TODO: Meshid
         * XXX TODO: mesh config
         * XXX TODO: mesh awake window
         * XXX TODO: beacon timing (mesh, etc)
         * XXX TODO: MCCAOP Advertisement Overview
         * XXX TODO: MCCAOP Advertisement
         * XXX TODO: Mesh channel switch parameters
         * VHT:
         * XXX TODO: VHT capabilities
         * XXX TODO: VHT operation
         * XXX TODO: VHT transmit power envelope
         * XXX TODO: channel switch wrapper element
         * XXX TODO: extended BSS load element
         *
         * XXX Vendor-specific OIDs (e.g. Atheros)
         *      [tlv] WPA parameters
         *      [tlv] WME parameters
         *      [tlv] Vendor OUI HT capabilities (optional)
         *      [tlv] Vendor OUI HT information (optional)
         *      [tlv] Atheros capabilities (optional)
         *      [tlv] TDMA parameters (optional)
         *      [tlv] Mesh ID (MBSS)
         *      [tlv] Mesh Conf (MBSS)
         *      [tlv] application data (optional)
         */

        memset(bo, 0, sizeof(*bo));

        memset(frm, 0, 8);      /* XXX timestamp is set by hardware/driver */
        frm += 8;
        *(uint16_t *)frm = htole16(ni->ni_intval);
        frm += 2;
        capinfo = ieee80211_getcapinfo(vap, ni->ni_chan);
        bo->bo_caps = (uint16_t *)frm;
        *(uint16_t *)frm = htole16(capinfo);
        frm += 2;
        *frm++ = IEEE80211_ELEMID_SSID;
        if ((vap->iv_flags & IEEE80211_F_HIDESSID) == 0) {
                *frm++ = ni->ni_esslen;
                memcpy(frm, ni->ni_essid, ni->ni_esslen);
                frm += ni->ni_esslen;
        } else
                *frm++ = 0;
        frm = ieee80211_add_rates(frm, rs);
        if (!IEEE80211_IS_CHAN_FHSS(ni->ni_chan)) {
                *frm++ = IEEE80211_ELEMID_DSPARMS;
                *frm++ = 1;
                *frm++ = ieee80211_chan2ieee(ic, ni->ni_chan);
        }
        if (ic->ic_flags & IEEE80211_F_PCF) {
                bo->bo_cfp = frm;
                frm = ieee80211_add_cfparms(frm, ic);
        }
        bo->bo_tim = frm;
        if (vap->iv_opmode == IEEE80211_M_IBSS) {
                *frm++ = IEEE80211_ELEMID_IBSSPARMS;
                *frm++ = 2;
                *frm++ = 0; *frm++ = 0;         /* TODO: ATIM window */
                bo->bo_tim_len = 0;
        } else if (vap->iv_opmode == IEEE80211_M_HOSTAP ||
            vap->iv_opmode == IEEE80211_M_MBSS) {
                /* TIM IE is the same for Mesh and Hostap */
                struct ieee80211_tim_ie *tie = (struct ieee80211_tim_ie *) frm;

                tie->tim_ie = IEEE80211_ELEMID_TIM;
                tie->tim_len = 4;       /* length */
                tie->tim_count = 0;     /* DTIM count */ 
                tie->tim_period = vap->iv_dtim_period;  /* DTIM period */
                tie->tim_bitctl = 0;    /* bitmap control */
                tie->tim_bitmap[0] = 0; /* Partial Virtual Bitmap */
                frm += sizeof(struct ieee80211_tim_ie);
                bo->bo_tim_len = 1;
        }
        bo->bo_tim_trailer = frm;
        if ((vap->iv_flags & IEEE80211_F_DOTH) ||
            (vap->iv_flags_ext & IEEE80211_FEXT_DOTD))
                frm = ieee80211_add_countryie(frm, ic);
        if (vap->iv_flags & IEEE80211_F_DOTH) {
                if (IEEE80211_IS_CHAN_5GHZ(ni->ni_chan))
                        frm = ieee80211_add_powerconstraint(frm, vap);
                bo->bo_csa = frm;
                if (ic->ic_flags & IEEE80211_F_CSAPENDING)
                        frm = ieee80211_add_csa(frm, vap);      
        } else
                bo->bo_csa = frm;

        bo->bo_quiet = NULL;
        if (vap->iv_flags & IEEE80211_F_DOTH) {
                if (IEEE80211_IS_CHAN_DFS(ic->ic_bsschan) &&
                    (vap->iv_flags_ext & IEEE80211_FEXT_DFS) &&
                    (vap->iv_quiet == 1)) {
                        /*
                         * We only insert the quiet IE offset if
                         * the quiet IE is enabled.  Otherwise don't
                         * put it here or we'll just overwrite
                         * some other beacon contents.
                         */
                        if (vap->iv_quiet) {
                                bo->bo_quiet = frm;
                                frm = ieee80211_add_quiet(frm,vap, 0);
                        }
                }
        }

        if (IEEE80211_IS_CHAN_ANYG(ni->ni_chan)) {
                bo->bo_erp = frm;
                frm = ieee80211_add_erp(frm, vap);
        }
        frm = ieee80211_add_xrates(frm, rs);
        frm = ieee80211_add_rsn(frm, vap);
        if (IEEE80211_IS_CHAN_HT(ni->ni_chan)) {
                frm = ieee80211_add_htcap(frm, ni);
                bo->bo_htinfo = frm;
                frm = ieee80211_add_htinfo(frm, ni);
        }

        if (IEEE80211_IS_CHAN_VHT(ni->ni_chan)) {
                frm = ieee80211_add_vhtcap(frm, ni);
                bo->bo_vhtinfo = frm;
                frm = ieee80211_add_vhtinfo(frm, ni);
                /* Transmit power envelope */
                /* Channel switch wrapper element */
                /* Extended bss load element */
        }

        frm = ieee80211_add_wpa(frm, vap);
        if (vap->iv_flags & IEEE80211_F_WME) {
                bo->bo_wme = frm;
                frm = ieee80211_add_wme_param(frm, &ic->ic_wme,
                    !! (vap->iv_flags_ext & IEEE80211_FEXT_UAPSD));
        }
        if (IEEE80211_IS_CHAN_HT(ni->ni_chan) &&
            (vap->iv_flags_ht & IEEE80211_FHT_HTCOMPAT)) {
                frm = ieee80211_add_htcap_vendor(frm, ni);
                frm = ieee80211_add_htinfo_vendor(frm, ni);
        }

#ifdef IEEE80211_SUPPORT_SUPERG
        if (vap->iv_flags & IEEE80211_F_ATHEROS) {
                bo->bo_ath = frm;
                frm = ieee80211_add_athcaps(frm, ni);
        }
#endif
#ifdef IEEE80211_SUPPORT_TDMA
        if (vap->iv_caps & IEEE80211_C_TDMA) {
                bo->bo_tdma = frm;
                frm = ieee80211_add_tdma(frm, vap);
        }
#endif
        if (vap->iv_appie_beacon != NULL) {
                bo->bo_appie = frm;
                bo->bo_appie_len = vap->iv_appie_beacon->ie_len;
                frm = add_appie(frm, vap->iv_appie_beacon);
        }

        /* XXX TODO: move meshid/meshconf up to before vendor extensions? */
#ifdef IEEE80211_SUPPORT_MESH
        if (vap->iv_opmode == IEEE80211_M_MBSS) {
                frm = ieee80211_add_meshid(frm, vap);
                bo->bo_meshconf = frm;
                frm = ieee80211_add_meshconf(frm, vap);
        }
#endif
        bo->bo_tim_trailer_len = frm - bo->bo_tim_trailer;
        bo->bo_csa_trailer_len = frm - bo->bo_csa;
        m->m_pkthdr.len = m->m_len = frm - mtod(m, uint8_t *);
}

/*
 * Allocate a beacon frame and fillin the appropriate bits.
 */
struct mbuf *
ieee80211_beacon_alloc(struct ieee80211_node *ni)
{
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211com *ic = ni->ni_ic;
        struct ieee80211_frame *wh;
        struct mbuf *m;
        int pktlen;
        uint8_t *frm;

        /*
         * Update the "We're putting the quiet IE in the beacon" state.
         */
        if (vap->iv_quiet == 1)
                vap->iv_flags_ext |= IEEE80211_FEXT_QUIET_IE;
        else if (vap->iv_quiet == 0)
                vap->iv_flags_ext &= ~IEEE80211_FEXT_QUIET_IE;

        /*
         * beacon frame format
         *
         * Note: This needs updating for 802.11-2012.
         *
         *      [8] time stamp
         *      [2] beacon interval
         *      [2] cabability information
         *      [tlv] ssid
         *      [tlv] supported rates
         *      [3] parameter set (DS)
         *      [8] CF parameter set (optional)
         *      [tlv] parameter set (IBSS/TIM)
         *      [tlv] country (optional)
         *      [3] power control (optional)
         *      [5] channel switch announcement (CSA) (optional)
         *      [tlv] extended rate phy (ERP)
         *      [tlv] extended supported rates
         *      [tlv] RSN parameters
         *      [tlv] HT capabilities
         *      [tlv] HT information
         *      [tlv] VHT capabilities
         *      [tlv] VHT operation
         *      [tlv] Vendor OUI HT capabilities (optional)
         *      [tlv] Vendor OUI HT information (optional)
         * XXX Vendor-specific OIDs (e.g. Atheros)
         *      [tlv] WPA parameters
         *      [tlv] WME parameters
         *      [tlv] TDMA parameters (optional)
         *      [tlv] Mesh ID (MBSS)
         *      [tlv] Mesh Conf (MBSS)
         *      [tlv] application data (optional)
         * NB: we allocate the max space required for the TIM bitmap.
         * XXX how big is this?
         */
        pktlen =   8                                    /* time stamp */
                 + sizeof(uint16_t)                     /* beacon interval */
                 + sizeof(uint16_t)                     /* capabilities */
                 + 2 + ni->ni_esslen                    /* ssid */
                 + 2 + IEEE80211_RATE_SIZE              /* supported rates */
                 + 2 + 1                                /* DS parameters */
                 + 2 + 6                                /* CF parameters */
                 + 2 + 4 + vap->iv_tim_len              /* DTIM/IBSSPARMS */
                 + IEEE80211_COUNTRY_MAX_SIZE           /* country */
                 + 2 + 1                                /* power control */
                 + sizeof(struct ieee80211_csa_ie)      /* CSA */
                 + sizeof(struct ieee80211_quiet_ie)    /* Quiet */
                 + 2 + 1                                /* ERP */
                 + 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE)
                 + (vap->iv_caps & IEEE80211_C_WPA ?    /* WPA 1+2 */
                        2*sizeof(struct ieee80211_ie_wpa) : 0)
                 /* XXX conditional? */
                 + 4+2*sizeof(struct ieee80211_ie_htcap)/* HT caps */
                 + 4+2*sizeof(struct ieee80211_ie_htinfo)/* HT info */
                 + 2 + sizeof(struct ieee80211_vht_cap)/* VHT caps */
                 + 2 + sizeof(struct ieee80211_vht_operation)/* VHT info */
                 + (vap->iv_caps & IEEE80211_C_WME ?    /* WME */
                        sizeof(struct ieee80211_wme_param) : 0)
#ifdef IEEE80211_SUPPORT_SUPERG
                 + sizeof(struct ieee80211_ath_ie)      /* ATH */
#endif
#ifdef IEEE80211_SUPPORT_TDMA
                 + (vap->iv_caps & IEEE80211_C_TDMA ?   /* TDMA */
                        sizeof(struct ieee80211_tdma_param) : 0)
#endif
#ifdef IEEE80211_SUPPORT_MESH
                 + 2 + ni->ni_meshidlen
                 + sizeof(struct ieee80211_meshconf_ie)
#endif
                 + IEEE80211_MAX_APPIE
                 ;
        m = ieee80211_getmgtframe(&frm,
                ic->ic_headroom + sizeof(struct ieee80211_frame), pktlen);
        if (m == NULL) {
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_ANY,
                        "%s: cannot get buf; size %u\n", __func__, pktlen);
                vap->iv_stats.is_tx_nobuf++;
                return NULL;
        }
        ieee80211_beacon_construct(m, frm, ni);

        M_PREPEND(m, sizeof(struct ieee80211_frame), IEEE80211_M_NOWAIT);
        KASSERT(m != NULL, ("no space for 802.11 header?"));
        wh = mtod(m, struct ieee80211_frame *);
        wh->i_fc[0] = IEEE80211_FC0_VERSION_0 | IEEE80211_FC0_TYPE_MGT |
            IEEE80211_FC0_SUBTYPE_BEACON;
        wh->i_fc[1] = IEEE80211_FC1_DIR_NODS;
        *(uint16_t *)wh->i_dur = 0;
        IEEE80211_ADDR_COPY(wh->i_addr1,
            ieee80211_vap_get_broadcast_address(vap));
        IEEE80211_ADDR_COPY(wh->i_addr2, vap->iv_myaddr);
        IEEE80211_ADDR_COPY(wh->i_addr3, ni->ni_bssid);
        *(uint16_t *)wh->i_seq = 0;

        return m;
}

/*
 * Update the dynamic parts of a beacon frame based on the current state.
 */
int
ieee80211_beacon_update(struct ieee80211_node *ni, struct mbuf *m, int mcast)
{
        struct ieee80211vap *vap = ni->ni_vap;
        struct ieee80211_beacon_offsets *bo = &vap->iv_bcn_off;
        struct ieee80211com *ic = ni->ni_ic;
        int len_changed = 0;
        uint16_t capinfo;

        IEEE80211_LOCK(ic);
        /*
         * Handle 11h channel change when we've reached the count.
         * We must recalculate the beacon frame contents to account
         * for the new channel.  Note we do this only for the first
         * vap that reaches this point; subsequent vaps just update
         * their beacon state to reflect the recalculated channel.
         */
        if (isset(bo->bo_flags, IEEE80211_BEACON_CSA) &&
            vap->iv_csa_count == ic->ic_csa_count) {
                vap->iv_csa_count = 0;
                /*
                 * Effect channel change before reconstructing the beacon
                 * frame contents as many places reference ni_chan.
                 */
                if (ic->ic_csa_newchan != NULL)
                        ieee80211_csa_completeswitch(ic);
                /*
                 * NB: ieee80211_beacon_construct clears all pending
                 * updates in bo_flags so we don't need to explicitly
                 * clear IEEE80211_BEACON_CSA.
                 */
                ieee80211_beacon_construct(m,
                    mtod(m, uint8_t*) + sizeof(struct ieee80211_frame), ni);

                /* XXX do WME aggressive mode processing? */
                IEEE80211_UNLOCK(ic);
                return 1;               /* just assume length changed */
        }

        /*
         * Handle the quiet time element being added and removed.
         * Again, for now we just cheat and reconstruct the whole
         * beacon - that way the gap is provided as appropriate.
         *
         * So, track whether we have already added the IE versus
         * whether we want to be adding the IE.
         */
        if ((vap->iv_flags_ext & IEEE80211_FEXT_QUIET_IE) &&
            (vap->iv_quiet == 0)) {
                /*
                 * Quiet time beacon IE enabled, but it's disabled;
                 * recalc
                 */
                vap->iv_flags_ext &= ~IEEE80211_FEXT_QUIET_IE;
                ieee80211_beacon_construct(m,
                    mtod(m, uint8_t*) + sizeof(struct ieee80211_frame), ni);
                /* XXX do WME aggressive mode processing? */
                IEEE80211_UNLOCK(ic);
                return 1;               /* just assume length changed */
        }

        if (((vap->iv_flags_ext & IEEE80211_FEXT_QUIET_IE) == 0) &&
            (vap->iv_quiet == 1)) {
                /*
                 * Quiet time beacon IE disabled, but it's now enabled;
                 * recalc
                 */
                vap->iv_flags_ext |= IEEE80211_FEXT_QUIET_IE;
                ieee80211_beacon_construct(m,
                    mtod(m, uint8_t*) + sizeof(struct ieee80211_frame), ni);
                /* XXX do WME aggressive mode processing? */
                IEEE80211_UNLOCK(ic);
                return 1;               /* just assume length changed */
        }

        /*
         * XXX TODO Strictly speaking this should be incremented with the TX
         * lock held so as to serialise access to the non-qos TID sequence
         * number space.
         *
         * If the driver identifies it does its own TX seqno management then
         * we can skip this (and still not do the TX seqno.)
         */

        /* TODO: IEEE80211_CONF_SEQNO_OFFLOAD() */
        ieee80211_output_beacon_seqno_assign(ni, m);

        /* XXX faster to recalculate entirely or just changes? */
        capinfo = ieee80211_getcapinfo(vap, ni->ni_chan);
        *bo->bo_caps = htole16(capinfo);

        if (vap->iv_flags & IEEE80211_F_WME) {
                struct ieee80211_wme_state *wme = &ic->ic_wme;

                /*
                 * Check for aggressive mode change.  When there is
                 * significant high priority traffic in the BSS
                 * throttle back BE traffic by using conservative
                 * parameters.  Otherwise BE uses aggressive params
                 * to optimize performance of legacy/non-QoS traffic.
                 */
                if (wme->wme_flags & WME_F_AGGRMODE) {
                        if (wme->wme_hipri_traffic >
                            wme->wme_hipri_switch_thresh) {
                                IEEE80211_DPRINTF(vap, IEEE80211_MSG_WME,
                                    "%s: traffic %u, disable aggressive mode\n",
                                    __func__, wme->wme_hipri_traffic);
                                wme->wme_flags &= ~WME_F_AGGRMODE;
                                ieee80211_wme_updateparams_locked(vap);
                                wme->wme_hipri_traffic =
                                        wme->wme_hipri_switch_hysteresis;
                        } else
                                wme->wme_hipri_traffic = 0;
                } else {
                        if (wme->wme_hipri_traffic <=
                            wme->wme_hipri_switch_thresh) {
                                IEEE80211_DPRINTF(vap, IEEE80211_MSG_WME,
                                    "%s: traffic %u, enable aggressive mode\n",
                                    __func__, wme->wme_hipri_traffic);
                                wme->wme_flags |= WME_F_AGGRMODE;
                                ieee80211_wme_updateparams_locked(vap);
                                wme->wme_hipri_traffic = 0;
                        } else
                                wme->wme_hipri_traffic =
                                        wme->wme_hipri_switch_hysteresis;
                }
                if (isset(bo->bo_flags, IEEE80211_BEACON_WME)) {
                        (void) ieee80211_add_wme_param(bo->bo_wme, wme,
                          vap->iv_flags_ext & IEEE80211_FEXT_UAPSD);
                        clrbit(bo->bo_flags, IEEE80211_BEACON_WME);
                }
        }

        if (isset(bo->bo_flags,  IEEE80211_BEACON_HTINFO)) {
                ieee80211_ht_update_beacon(vap, bo);
                clrbit(bo->bo_flags, IEEE80211_BEACON_HTINFO);
        }
#ifdef IEEE80211_SUPPORT_TDMA
        if (vap->iv_caps & IEEE80211_C_TDMA) {
                /*
                 * NB: the beacon is potentially updated every TBTT.
                 */
                ieee80211_tdma_update_beacon(vap, bo);
        }
#endif
#ifdef IEEE80211_SUPPORT_MESH
        if (vap->iv_opmode == IEEE80211_M_MBSS)
                ieee80211_mesh_update_beacon(vap, bo);
#endif

        if (vap->iv_opmode == IEEE80211_M_HOSTAP ||
            vap->iv_opmode == IEEE80211_M_MBSS) {       /* NB: no IBSS support*/
                struct ieee80211_tim_ie *tie =
                        (struct ieee80211_tim_ie *) bo->bo_tim;
                if (isset(bo->bo_flags, IEEE80211_BEACON_TIM)) {
                        u_int timlen, timoff, i;
                        /* 
                         * ATIM/DTIM needs updating.  If it fits in the
                         * current space allocated then just copy in the
                         * new bits.  Otherwise we need to move any trailing
                         * data to make room.  Note that we know there is
                         * contiguous space because ieee80211_beacon_allocate
                         * insures there is space in the mbuf to write a
                         * maximal-size virtual bitmap (based on iv_max_aid).
                         */
                        /*
                         * Calculate the bitmap size and offset, copy any
                         * trailer out of the way, and then copy in the
                         * new bitmap and update the information element.
                         * Note that the tim bitmap must contain at least
                         * one byte and any offset must be even.
                         */
                        if (vap->iv_ps_pending != 0) {
                                timoff = 128;           /* impossibly large */
                                for (i = 0; i < vap->iv_tim_len; i++)
                                        if (vap->iv_tim_bitmap[i]) {
                                                timoff = i &~ 1;
                                                break;
                                        }
                                KASSERT(timoff != 128, ("tim bitmap empty!"));
                                for (i = vap->iv_tim_len-1; i >= timoff; i--)
                                        if (vap->iv_tim_bitmap[i])
                                                break;
                                timlen = 1 + (i - timoff);
                        } else {
                                timoff = 0;
                                timlen = 1;
                        }

                        /*
                         * TODO: validate this!
                         */
                        if (timlen != bo->bo_tim_len) {
                                /* copy up/down trailer */
                                int adjust = tie->tim_bitmap+timlen
                                           - bo->bo_tim_trailer;
                                ovbcopy(bo->bo_tim_trailer,
                                    bo->bo_tim_trailer+adjust,
                                    bo->bo_tim_trailer_len);
                                bo->bo_tim_trailer += adjust;
                                bo->bo_erp += adjust;
                                bo->bo_htinfo += adjust;
                                bo->bo_vhtinfo += adjust;
#ifdef IEEE80211_SUPPORT_SUPERG
                                bo->bo_ath += adjust;
#endif
#ifdef IEEE80211_SUPPORT_TDMA
                                bo->bo_tdma += adjust;
#endif
#ifdef IEEE80211_SUPPORT_MESH
                                bo->bo_meshconf += adjust;
#endif
                                bo->bo_appie += adjust;
                                bo->bo_wme += adjust;
                                bo->bo_csa += adjust;
                                bo->bo_quiet += adjust;
                                bo->bo_tim_len = timlen;

                                /* update information element */
                                tie->tim_len = 3 + timlen;
                                tie->tim_bitctl = timoff;
                                len_changed = 1;
                        }
                        memcpy(tie->tim_bitmap, vap->iv_tim_bitmap + timoff,
                                bo->bo_tim_len);

                        clrbit(bo->bo_flags, IEEE80211_BEACON_TIM);

                        IEEE80211_DPRINTF(vap, IEEE80211_MSG_POWER,
                                "%s: TIM updated, pending %u, off %u, len %u\n",
                                __func__, vap->iv_ps_pending, timoff, timlen);
                }
                /* count down DTIM period */
                if (tie->tim_count == 0)
                        tie->tim_count = tie->tim_period - 1;
                else
                        tie->tim_count--;
                /* update state for buffered multicast frames on DTIM */
                if (mcast && tie->tim_count == 0)
                        tie->tim_bitctl |= 1;
                else
                        tie->tim_bitctl &= ~1;
                if (isset(bo->bo_flags, IEEE80211_BEACON_CSA)) {
                        struct ieee80211_csa_ie *csa =
                            (struct ieee80211_csa_ie *) bo->bo_csa;

                        /*
                         * Insert or update CSA ie.  If we're just starting
                         * to count down to the channel switch then we need
                         * to insert the CSA ie.  Otherwise we just need to
                         * drop the count.  The actual change happens above
                         * when the vap's count reaches the target count.
                         */
                        if (vap->iv_csa_count == 0) {
                                memmove(&csa[1], csa, bo->bo_csa_trailer_len);
                                bo->bo_erp += sizeof(*csa);
                                bo->bo_htinfo += sizeof(*csa);
                                bo->bo_vhtinfo += sizeof(*csa);
                                bo->bo_wme += sizeof(*csa);
#ifdef IEEE80211_SUPPORT_SUPERG
                                bo->bo_ath += sizeof(*csa);
#endif
#ifdef IEEE80211_SUPPORT_TDMA
                                bo->bo_tdma += sizeof(*csa);
#endif
#ifdef IEEE80211_SUPPORT_MESH
                                bo->bo_meshconf += sizeof(*csa);
#endif
                                bo->bo_appie += sizeof(*csa);
                                bo->bo_csa_trailer_len += sizeof(*csa);
                                bo->bo_quiet += sizeof(*csa);
                                bo->bo_tim_trailer_len += sizeof(*csa);
                                m->m_len += sizeof(*csa);
                                m->m_pkthdr.len += sizeof(*csa);

                                ieee80211_add_csa(bo->bo_csa, vap);
                        } else
                                csa->csa_count--;
                        vap->iv_csa_count++;
                        /* NB: don't clear IEEE80211_BEACON_CSA */
                }

                /*
                 * Only add the quiet time IE if we've enabled it
                 * as appropriate.
                 */
                if (IEEE80211_IS_CHAN_DFS(ic->ic_bsschan) &&
                    (vap->iv_flags_ext & IEEE80211_FEXT_DFS)) {
                        if (vap->iv_quiet &&
                            (vap->iv_flags_ext & IEEE80211_FEXT_QUIET_IE)) {
                                ieee80211_add_quiet(bo->bo_quiet, vap, 1);
                        }
                }
                if (isset(bo->bo_flags, IEEE80211_BEACON_ERP)) {
                        /*
                         * ERP element needs updating.
                         */
                        (void) ieee80211_add_erp(bo->bo_erp, vap);
                        clrbit(bo->bo_flags, IEEE80211_BEACON_ERP);
                }
#ifdef IEEE80211_SUPPORT_SUPERG
                if (isset(bo->bo_flags,  IEEE80211_BEACON_ATH)) {
                        ieee80211_add_athcaps(bo->bo_ath, ni);
                        clrbit(bo->bo_flags, IEEE80211_BEACON_ATH);
                }
#endif
        }
        if (isset(bo->bo_flags, IEEE80211_BEACON_APPIE)) {
                const struct ieee80211_appie *aie = vap->iv_appie_beacon;
                int aielen;
                uint8_t *frm;

                aielen = 0;
                if (aie != NULL)
                        aielen += aie->ie_len;
                if (aielen != bo->bo_appie_len) {
                        /* copy up/down trailer */
                        int adjust = aielen - bo->bo_appie_len;
                        ovbcopy(bo->bo_tim_trailer, bo->bo_tim_trailer+adjust,
                                bo->bo_tim_trailer_len);
                        bo->bo_tim_trailer += adjust;
                        bo->bo_appie += adjust;
                        bo->bo_appie_len = aielen;

                        len_changed = 1;
                }
                frm = bo->bo_appie;
                if (aie != NULL)
                        frm  = add_appie(frm, aie);
                clrbit(bo->bo_flags, IEEE80211_BEACON_APPIE);
        }
        IEEE80211_UNLOCK(ic);

        return len_changed;
}

/*
 * Do Ethernet-LLC encapsulation for each payload in a fast frame
 * tunnel encapsulation.  The frame is assumed to have an Ethernet
 * header at the front that must be stripped before prepending the
 * LLC followed by the Ethernet header passed in (with an Ethernet
 * type that specifies the payload size).
 */
struct mbuf *
ieee80211_ff_encap1(struct ieee80211vap *vap, struct mbuf *m,
        const struct ether_header *eh)
{
        struct llc *llc;
        uint16_t payload;

        /* XXX optimize by combining m_adj+M_PREPEND */
        m_adj(m, sizeof(struct ether_header) - sizeof(struct llc));
        llc = mtod(m, struct llc *);
        llc->llc_dsap = llc->llc_ssap = LLC_SNAP_LSAP;
        llc->llc_control = LLC_UI;
        llc->llc_snap.org_code[0] = 0;
        llc->llc_snap.org_code[1] = 0;
        llc->llc_snap.org_code[2] = 0;
        llc->llc_snap.ether_type = eh->ether_type;
        payload = m->m_pkthdr.len;              /* NB: w/o Ethernet header */

        M_PREPEND(m, sizeof(struct ether_header), IEEE80211_M_NOWAIT);
        if (m == NULL) {                /* XXX cannot happen */
                IEEE80211_DPRINTF(vap, IEEE80211_MSG_SUPERG,
                        "%s: no space for ether_header\n", __func__);
                vap->iv_stats.is_tx_nobuf++;
                return NULL;
        }
        ETHER_HEADER_COPY(mtod(m, void *), eh);
        mtod(m, struct ether_header *)->ether_type = htons(payload);
        return m;
}

/*
 * Complete an mbuf transmission.
 *
 * For now, this simply processes a completed frame after the
 * driver has completed it's transmission and/or retransmission.
 * It assumes the frame is an 802.11 encapsulated frame.
 *
 * Later on it will grow to become the exit path for a given frame
 * from the driver and, depending upon how it's been encapsulated
 * and already transmitted, it may end up doing A-MPDU retransmission,
 * power save requeuing, etc.
 *
 * In order for the above to work, the driver entry point to this
 * must not hold any driver locks.  Thus, the driver needs to delay
 * any actual mbuf completion until it can release said locks.
 *
 * This frees the mbuf and if the mbuf has a node reference,
 * the node reference will be freed.
 */
void
ieee80211_tx_complete(struct ieee80211_node *ni, struct mbuf *m, int status)
{

        if (ni != NULL) {
                struct ifnet *ifp = ni->ni_vap->iv_ifp;

                if (status == 0) {
                        if_inc_counter(ifp, IFCOUNTER_OBYTES, m->m_pkthdr.len);
                        if_inc_counter(ifp, IFCOUNTER_OPACKETS, 1);
                        if (m->m_flags & M_MCAST)
                                if_inc_counter(ifp, IFCOUNTER_OMCASTS, 1);
                } else
                        if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
                if (m->m_flags & M_TXCB) {
                        IEEE80211_DPRINTF(ni->ni_vap, IEEE80211_MSG_STATE | IEEE80211_MSG_DEBUG,
                           "ni %p vap %p mode %s state %s m %p status %d\n", ni, ni->ni_vap,
                           ieee80211_opmode_name[ni->ni_vap->iv_opmode],
                           ieee80211_state_name[ni->ni_vap->iv_state], m, status);
                        ieee80211_process_callback(ni, m, status);
                }
                ieee80211_free_node(ni);
        }
        m_freem(m);
}

/**
 * @brief Assign a sequence number to the given frame.
 *
 * Check the frame type and TID and assign a suitable sequence number
 * from the correct sequence number space.
 *
 * This implements the components of 802.11-2020 10.3.2.14.2
 * (Transmitter Requirements) that net80211 currently supports.
 *
 * It assumes the mbuf has been encapsulated, and has the TID assigned
 * if it is a QoS frame.
 *
 * Note this also clears any existing fragment ID in the header, so it
 * must be called first before assigning fragment IDs.
 *
 * @param ni    ieee80211_node this frame will be transmitted to
 * @param arg_tid       A temporary check, existing callers may set
 *    this to a TID variable they were using, and this routine
 *    will verify it against what's in the frame and complain if
 *    they don't match.  For new callers, use -1.
 * @param m     mbuf to populate the sequence number into
 */
void
ieee80211_output_seqno_assign(struct ieee80211_node *ni, int arg_tid,
    struct mbuf *m)
{
        struct ieee80211_frame *wh;
        ieee80211_seq seqno;
        uint8_t tid, type, subtype;

        wh = mtod(m, struct ieee80211_frame *);
        tid = ieee80211_gettid(wh);
        type = wh->i_fc[0] & IEEE80211_FC0_TYPE_MASK;
        subtype = wh->i_fc[0] & IEEE80211_FC0_SUBTYPE_MASK;

        /*
         * Find places where the passed in TID doesn't match gettid()
         * and log.  I'll have to then go and chase those down.
         *
         * If the caller knows its already setup the TID in the frame
         * correctly then it can pass in -1 and this check will be
         * skipped.
         */
        if (arg_tid != -1 && tid != arg_tid)
                ic_printf(ni->ni_vap->iv_ic,
                    "%s: called; TID mismatch; tid=%u, arg_tid=%d\n",
                    __func__, tid, arg_tid);


        /* 802.11-2020 10.3.2.14.2 (Transmitter Requirements) sections */

        /* SNS7 - unicast PV1 management frame */

        /* SNS6 - unicast PV1 data frame */

        /* SNS5 - QoS NULL frames */
        if (IEEE80211_QOS_HAS_SEQ(wh) && IEEE80211_IS_QOS_NULL(wh))
                seqno = ieee80211_tx_seqno_fetch_incr(ni, IEEE80211_NONQOS_TID);

        /* SNS4 - QMF STA transmitting a QMF */

        /* SNS3 - QoS STA; Time Priority Management frame */

        /* SNS2 - unicast QoS STA, data frame, excluding SNS5 */
        else if (IEEE80211_QOS_HAS_SEQ(wh) &&
            !IEEE80211_IS_MULTICAST(wh->i_addr1))
                seqno = ieee80211_tx_seqno_fetch_incr(ni, tid);

        /* SNS1 - Baseline (everything else) */
        else if (IEEE80211_HAS_SEQ(type, subtype))
                seqno = ieee80211_tx_seqno_fetch_incr(ni, IEEE80211_NONQOS_TID);
        else
                seqno = 0;

        /*
         * Assign the sequence number, clearing out any existing
         * sequence and fragment numbers.
         */
        *(uint16_t *)&wh->i_seq[0] =
            htole16(seqno << IEEE80211_SEQ_SEQ_SHIFT);
        M_SEQNO_SET(m, seqno);
}

/**
 * @brief Assign a sequence number to the given beacon frame.
 *
 * TODO: update to 802.11-2020 10.3.2.14.2 (Transmitter Requirements)
 *
 * @param ni    ieee80211_node this frame will be transmitted to
 * @param m             mbuf to populate the sequence number into
 */
void
ieee80211_output_beacon_seqno_assign(struct ieee80211_node *ni, struct mbuf *m)
{
        struct ieee80211_frame *wh;
        ieee80211_seq seqno;

        wh = mtod(m, struct ieee80211_frame *);

        seqno = ieee80211_tx_seqno_fetch_incr(ni, IEEE80211_NONQOS_TID);
        *(uint16_t *)&wh->i_seq[0] =
                htole16(seqno << IEEE80211_SEQ_SEQ_SHIFT);
        M_SEQNO_SET(m, seqno);
}