/*      $NetBSD: ieee80211_output.c,v 1.68 2024/07/05 04:31:53 rin Exp $        */

/*
 * Copyright (c) 2001 Atsushi Onoe
 * Copyright (c) 2002-2005 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.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * 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>
#ifdef __FreeBSD__
__FBSDID("$FreeBSD: src/sys/net80211/ieee80211_output.c,v 1.34 2005/08/10 16:22:29 sam Exp $");
#endif
#ifdef __NetBSD__
__KERNEL_RCSID(0, "$NetBSD: ieee80211_output.c,v 1.68 2024/07/05 04:31:53 rin Exp $");
#endif

#ifdef _KERNEL_OPT
#include "opt_inet.h"
#endif

#include <sys/param.h>
#include <sys/systm.h> 
#include <sys/mbuf.h>   
#include <sys/kernel.h>
#include <sys/endian.h>
#include <sys/errno.h>
#include <sys/proc.h>
#include <sys/sysctl.h>

#include <net/if.h>
#include <net/if_llc.h>
#include <net/if_media.h>
#include <net/if_arp.h>
#include <net/if_ether.h>
#include <net/if_llc.h>
#include <net/if_vlanvar.h>

#include <net80211/ieee80211_netbsd.h>
#include <net80211/ieee80211_var.h>

#include <net/bpf.h>

#ifdef INET
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <net/if_ether.h>
#endif

static int ieee80211_fragment(struct ieee80211com *, struct mbuf *,
        u_int hdrsize, u_int ciphdrsize, u_int mtu);

#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 ieee80211com *ic, int subtype)
{
        switch (subtype) {
        case IEEE80211_FC0_SUBTYPE_PROBE_RESP:
                return (ic->ic_opmode == IEEE80211_M_IBSS);
        }
        return 1;
}
#endif

/*
 * Set the direction field and address fields of an outgoing
 * non-QoS 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.
 */
static void
ieee80211_send_setup(struct ieee80211com *ic,
        struct ieee80211_node *ni,
        struct ieee80211_frame *wh,
        int type,
        const u_int8_t sa[IEEE80211_ADDR_LEN],
        const u_int8_t da[IEEE80211_ADDR_LEN],
        const u_int8_t bssid[IEEE80211_ADDR_LEN])
{
#define WH4(wh) ((struct ieee80211_frame_addr4 *)wh)

        wh->i_fc[0] = IEEE80211_FC0_VERSION_0 | type;

        if ((type & IEEE80211_FC0_TYPE_MASK) == IEEE80211_FC0_TYPE_DATA) {
                switch (ic->ic_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_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);
                IEEE80211_ADDR_COPY(wh->i_addr3, bssid);
        }

        *(u_int16_t *)&wh->i_dur[0] = 0;
        /* NB: use non-QoS tid */
        *(u_int16_t *)&wh->i_seq[0] =
            htole16(ni->ni_txseqs[0] << IEEE80211_SEQ_SEQ_SHIFT);
        ni->ni_txseqs[0]++;
#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).
 */
static int
ieee80211_mgmt_output(struct ieee80211com *ic, struct ieee80211_node *ni,
    struct mbuf *m, int type, int timer)
{
        struct ifnet *ifp = ic->ic_ifp;
        struct ieee80211_frame *wh;

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

        /*
         * Yech, hack alert!  We want to pass the node down to the
         * driver's start routine.  If we don't do so then the start
         * routine must immediately look it up again and that can
         * cause a lock order reversal if, for example, this frame
         * is being sent because the station is being timedout and
         * the frame being sent is a DEAUTH message.  We could stick
         * this in an m_tag and tack that on to the mbuf.  However
         * that's rather expensive to do for every frame so instead
         * we stuff it in the rcvif field since outbound frames do
         * not (presently) use this.
         */
        M_PREPEND(m, sizeof(struct ieee80211_frame), M_DONTWAIT);
        if (m == NULL)
                return ENOMEM;
        M_SETCTX(m, ni);

        wh = mtod(m, struct ieee80211_frame *);
        ieee80211_send_setup(ic, ni, wh, IEEE80211_FC0_TYPE_MGT | type,
            ic->ic_myaddr, ni->ni_macaddr, ni->ni_bssid);

        if ((m->m_flags & M_LINK0) != 0 && ni->ni_challenge != NULL) {
                m->m_flags &= ~M_LINK0;
                IEEE80211_DPRINTF(ic, IEEE80211_MSG_AUTH,
                        "[%s] encrypting frame (%s)\n",
                        ether_sprintf(wh->i_addr1), __func__);
                wh->i_fc[1] |= IEEE80211_FC1_WEP;
        }

#ifdef IEEE80211_DEBUG
        /* avoid printing too many frames */
        if ((ieee80211_msg_debug(ic) && doprint(ic, type)) ||
            ieee80211_msg_dumppkts(ic)) {
                printf("[%s] send %s on channel %u\n",
                    ether_sprintf(wh->i_addr1),
                    ieee80211_mgt_subtype_name[
                        (type & IEEE80211_FC0_SUBTYPE_MASK) >>
                                IEEE80211_FC0_SUBTYPE_SHIFT],
                    ieee80211_chan2ieee(ic, ic->ic_curchan));
        }
#endif

        IEEE80211_NODE_STAT(ni, tx_mgmt);
        IF_ENQUEUE(&ic->ic_mgtq, m);
        if (timer) {
                /*
                 * Set the mgt frame timeout.
                 */
                ic->ic_mgt_timer = timer;
                ifp->if_timer = 1;
        }
        if_start_lock(ifp);
        return 0;
}

/*
 * Send a null data frame to the specified node.
 *
 * 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.
 */
int
ieee80211_send_nulldata(struct ieee80211_node *ni)
{
        struct ieee80211com *ic = ni->ni_ic;
        struct ifnet *ifp = ic->ic_ifp;
        struct mbuf *m;
        struct ieee80211_frame *wh;

        MGETHDR(m, M_NOWAIT, MT_HEADER);
        if (m == NULL) {
                ic->ic_stats.is_tx_nobuf++;
                ieee80211_unref_node(&ni);
                return ENOMEM;
        }
        M_SETCTX(m, ni);

        wh = mtod(m, struct ieee80211_frame *);

        ieee80211_send_setup(ic, ni, wh,
            IEEE80211_FC0_TYPE_DATA | IEEE80211_FC0_SUBTYPE_NODATA,
            ic->ic_myaddr, ni->ni_macaddr, ni->ni_bssid);

        /* NB: power management bit is never sent by an AP */
        if ((ni->ni_flags & IEEE80211_NODE_PWR_MGT) &&
            ic->ic_opmode != IEEE80211_M_HOSTAP) {
                wh->i_fc[1] |= IEEE80211_FC1_PWR_MGT;
        }

        m->m_len = m->m_pkthdr.len = sizeof(struct ieee80211_frame);

        IEEE80211_NODE_STAT(ni, tx_data);

        IEEE80211_DPRINTF(ic, IEEE80211_MSG_DEBUG | IEEE80211_MSG_DUMPPKTS,
            "[%s] send null data frame on channel %u, pwr mgt %s\n",
            ether_sprintf(ni->ni_macaddr),
            ieee80211_chan2ieee(ic, ic->ic_curchan),
            wh->i_fc[1] & IEEE80211_FC1_PWR_MGT ? "ena" : "dis");

        IF_ENQUEUE(&ic->ic_mgtq, m);            /* cheat */
        if_start_lock(ifp);

        return 0;
}

/* 
 * 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 ieee80211com *ic, struct mbuf *m,
    struct ieee80211_node *ni)
{
        int v_wme_ac, d_wme_ac, ac;
#ifdef INET
        struct ether_header *eh;
#endif

        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) {
                /* XXX used to check ec_nvlans. */
                if (!vlan_has_tag(m)) {
                        IEEE80211_NODE_STAT(ni, tx_novlantag);
                        return 1;
                }
                if (EVL_VLANOFTAG(vlan_get_tag(m)) !=
                    EVL_VLANOFTAG(ni->ni_vlan)) {
                        IEEE80211_NODE_STAT(ni, tx_vlanmismatch);
                        return 1;
                }
                /* map vlan priority to AC */
                switch (EVL_PRIOFTAG(ni->ni_vlan)) {
                case 1:
                case 2:
                        v_wme_ac = WME_AC_BK;
                        break;
                case 0:
                case 3:
                        v_wme_ac = WME_AC_BE;
                        break;
                case 4:
                case 5:
                        v_wme_ac = WME_AC_VI;
                        break;
                case 6:
                case 7:
                        v_wme_ac = WME_AC_VO;
                        break;
                }
        }

#ifdef INET
        eh = mtod(m, struct ether_header *);
        if (eh->ether_type == htons(ETHERTYPE_IP)) {
                const struct ip *ip = (struct ip *)
                        (mtod(m, u_int8_t *) + sizeof (*eh));
                /*
                 * IP frame, map the TOS field.
                 */
                switch (ip->ip_tos) {
                case 0x08:
                case 0x20:
                        d_wme_ac = WME_AC_BK;   /* background */
                        break;
                case 0x28:
                case 0xa0:
                        d_wme_ac = WME_AC_VI;   /* video */
                        break;
                case 0x30:                      /* voice */
                case 0xe0:
                case 0x88:                      /* XXX UPSD */
                case 0xb8:
                        d_wme_ac = WME_AC_VO;
                        break;
                default:
                        d_wme_ac = WME_AC_BE;
                        break;
                }
        } else {
#endif /* INET */
                d_wme_ac = WME_AC_BE;
#ifdef INET
        }
#endif
        /*
         * Use highest priority AC.
         */
        if (v_wme_ac > d_wme_ac)
                ac = v_wme_ac;
        else
                ac = d_wme_ac;

        /*
         * Apply ACM policy.
         */
        if (ic->ic_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 */
                };
                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.
 *
 * Basically, we are trying to make sure that the several M_PREPENDs
 * called after this function do not fail.
 */
static struct mbuf *
ieee80211_mbuf_adjust(struct ieee80211com *ic, int hdrsize,
        struct ieee80211_key *key, struct mbuf *m)
{
#define TO_BE_RECLAIMED (sizeof(struct ether_header) - sizeof(struct llc))
        int needed_space = hdrsize;
        int wlen = 0;

        if (key != NULL) {
                /* XXX belongs in crypto code? */
                needed_space += key->wk_cipher->ic_header;
                /* XXX frags */
        }

        /*
         * 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(M_NOWAIT, m->m_type);
                if (n == NULL) {
                        ic->ic_stats.is_tx_nobuf++;
                        m_freem(m);
                        return NULL;
                }

                IASSERT(needed_space <= MHLEN,
                    ("not enough room, need %u got %lu\n", needed_space, (u_long)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).
                 */
                m_move_pkthdr(n, m);
                n->m_len = 0;
                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.
                 */
                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;
        } else {
                /*
                 * We will overwrite the ethernet header in the
                 * 802.11 encapsulation stage.  Make sure that it
                 * is writable.
                 */
                wlen = sizeof(struct ether_header);
        }

        /*
         * If we're going to s/w encrypt the mbuf chain make sure it is
         * writable.
         */
        if (key != NULL && (key->wk_flags & IEEE80211_KEY_SWCRYPT) != 0) {
                wlen = M_COPYALL;
        }
        if (wlen != 0 && m_makewritable(&m, 0, wlen, M_DONTWAIT) != 0) {
                m_freem(m);
                return NULL;
        }

        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 ieee80211com *ic, struct ieee80211_node *ni)
{
        if (IEEE80211_KEY_UNDEFINED(ni->ni_ucastkey)) {
                if (ic->ic_def_txkey == IEEE80211_KEYIX_NONE ||
                    IEEE80211_KEY_UNDEFINED(ic->ic_nw_keys[ic->ic_def_txkey]))
                        return NULL;
                return &ic->ic_nw_keys[ic->ic_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 ieee80211com *ic,
    struct ieee80211_node *ni)
{
        if (ic->ic_def_txkey == IEEE80211_KEYIX_NONE ||
            IEEE80211_KEY_UNDEFINED(ic->ic_nw_keys[ic->ic_def_txkey]))
                return NULL;
        return &ic->ic_nw_keys[ic->ic_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.
 */
struct mbuf *
ieee80211_encap(struct ieee80211com *ic, struct mbuf *m,
        struct ieee80211_node *ni)
{
        struct ether_header eh;
        struct ieee80211_frame *wh;
        struct ieee80211_key *key;
        struct llc *llc;
        int hdrsize, datalen, addqos, txfrag;

        IASSERT(m->m_len >= sizeof(eh), ("no ethernet header!"));
        memcpy(&eh, mtod(m, void *), sizeof(struct ether_header));

        /*
         * 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 (ic->ic_flags & IEEE80211_F_PRIVACY) {
                if (ic->ic_opmode == IEEE80211_M_STA ||
                    !IEEE80211_IS_MULTICAST(eh.ether_dhost)) {
                        key = ieee80211_crypto_getucastkey(ic, ni);
                } else {
                        key = ieee80211_crypto_getmcastkey(ic, ni);
                }
                if (key == NULL && eh.ether_type != htons(ETHERTYPE_PAE)) {
                        IEEE80211_DPRINTF(ic, IEEE80211_MSG_CRYPTO,
                            "[%s] no default transmit key (%s) deftxkey %u\n",
                            ether_sprintf(eh.ether_dhost), __func__,
                            ic->ic_def_txkey);
                        ic->ic_stats.is_tx_nodefkey++;
                }
        } else {
                key = NULL;
        }

        /*
         * XXX 4-address format.
         *
         * 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.
         */
        addqos = (ni->ni_flags & IEEE80211_NODE_QOS) &&
            eh.ether_type != htons(ETHERTYPE_PAE);
        if (addqos)
                hdrsize = sizeof(struct ieee80211_qosframe);
        else
                hdrsize = sizeof(struct ieee80211_frame);
        if (ic->ic_flags & IEEE80211_F_DATAPAD)
                hdrsize = roundup(hdrsize, sizeof(u_int32_t));

        m = ieee80211_mbuf_adjust(ic, hdrsize, key, m);
        if (m == NULL) {
                /* NB: ieee80211_mbuf_adjust handles msgs+statistics */
                goto bad;
        }

        /* NB: this could be optimized because 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;
        datalen = m->m_pkthdr.len;              /* NB: w/o 802.11 header */

        M_PREPEND(m, hdrsize, M_DONTWAIT);
        if (m == NULL) {
                ic->ic_stats.is_tx_nobuf++;
                goto bad;
        }

        wh = mtod(m, struct ieee80211_frame *);
        wh->i_fc[0] = IEEE80211_FC0_VERSION_0 | IEEE80211_FC0_TYPE_DATA;
        *(u_int16_t *)wh->i_dur = 0;

        switch (ic->ic_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 ic_bss as the
                 *     neighbor's may be stale after an ibss merge
                 */
                IEEE80211_ADDR_COPY(wh->i_addr3, ic->ic_bss->ni_bssid);
                break;

        case IEEE80211_M_HOSTAP:
#ifndef IEEE80211_NO_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);
#endif
                break;

        case IEEE80211_M_MONITOR:
                goto bad;
        }

        if (m->m_flags & M_MORE_DATA)
                wh->i_fc[1] |= IEEE80211_FC1_MORE_DATA;

        if (addqos) {
                struct ieee80211_qosframe *qwh =
                        (struct ieee80211_qosframe *)wh;
                int ac, tid;

                ac = M_WME_GETAC(m);
                /* map from access class/queue to 11e header priorty value */
                tid = WME_AC_TO_TID(ac);
                qwh->i_qos[0] = tid & IEEE80211_QOS_TID;
                if (ic->ic_wme.wme_wmeChanParams.cap_wmeParams[ac].wmep_noackPolicy)
                        qwh->i_qos[0] |= 1 << IEEE80211_QOS_ACKPOLICY_S;
                qwh->i_qos[1] = 0;
                qwh->i_fc[0] |= IEEE80211_FC0_SUBTYPE_QOS;

                *(u_int16_t *)wh->i_seq =
                    htole16(ni->ni_txseqs[tid] << IEEE80211_SEQ_SEQ_SHIFT);
                ni->ni_txseqs[tid]++;
        } else {
                *(u_int16_t *)wh->i_seq =
                    htole16(ni->ni_txseqs[0] << IEEE80211_SEQ_SEQ_SHIFT);
                ni->ni_txseqs[0]++;
        }

        /* check if xmit fragmentation is required */
        txfrag = (m->m_pkthdr.len > ic->ic_fragthreshold &&
            !IEEE80211_IS_MULTICAST(wh->i_addr1) &&
            (m->m_flags & M_FF) == 0);          /* NB: don't fragment ff's */

        if (key != NULL) {
                /*
                 * IEEE 802.1X: send EAPOL frames always in the clear.
                 * WPA/WPA2: encrypt EAPOL keys when pairwise keys are set.
                 */
                if (eh.ether_type != htons(ETHERTYPE_PAE) ||
                    ((ic->ic_flags & IEEE80211_F_WPA) &&
                     (ic->ic_opmode == IEEE80211_M_STA ?
                      !IEEE80211_KEY_UNDEFINED(*key) :
                      !IEEE80211_KEY_UNDEFINED(ni->ni_ucastkey)))) {
                        wh->i_fc[1] |= IEEE80211_FC1_WEP;
                        if (!ieee80211_crypto_enmic(ic, key, m, txfrag)) {
                                IEEE80211_DPRINTF(ic, IEEE80211_MSG_OUTPUT,
                                    "[%s] enmic failed, discard frame\n",
                                    ether_sprintf(eh.ether_dhost));
                                ic->ic_stats.is_crypto_enmicfail++;
                                goto bad;
                        }
                }
        }

        if (txfrag && !ieee80211_fragment(ic, m, hdrsize,
            key != NULL ? key->wk_cipher->ic_header : 0, ic->ic_fragthreshold))
                goto bad;

        IEEE80211_NODE_STAT(ni, tx_data);
        IEEE80211_NODE_STAT_ADD(ni, tx_bytes, datalen);

        return m;

bad:
        m_freem(m);
        return NULL;
}

/*
 * Arguments in:
 *
 * paylen:  payload length (no FCS, no WEP header)
 *
 * hdrlen:  header length
 *
 * rate:    MSDU speed, units 500kb/s
 *
 * flags:   IEEE80211_F_SHPREAMBLE (use short preamble),
 *          IEEE80211_F_SHSLOT (use short slot length)
 *
 * Arguments out:
 *
 * d:       802.11 Duration field for RTS,
 *          802.11 Duration field for data frame,
 *          PLCP Length for data frame,
 *          residual octets at end of data slot
 */
static int
ieee80211_compute_duration1(int len, int use_ack, uint32_t icflags, int rate,
    struct ieee80211_duration *d)
{
        int pre, ctsrate;
        int ack, bitlen, data_dur, remainder;

        /* RTS reserves medium for SIFS | CTS | SIFS | (DATA) | SIFS | ACK
         * DATA reserves medium for SIFS | ACK,
         *
         * (XXX or SIFS | ACK | SIFS | DATA | SIFS | ACK, if more fragments)
         *
         * XXXMYC: no ACK on multicast/broadcast or control packets
         */

        bitlen = len * 8;

        pre = IEEE80211_DUR_DS_SIFS;
        if ((icflags & IEEE80211_F_SHPREAMBLE) != 0)
                pre += IEEE80211_DUR_DS_SHORT_PREAMBLE + IEEE80211_DUR_DS_FAST_PLCPHDR;
        else
                pre += IEEE80211_DUR_DS_LONG_PREAMBLE + IEEE80211_DUR_DS_SLOW_PLCPHDR;

        d->d_residue = 0;
        data_dur = (bitlen * 2) / rate;
        remainder = (bitlen * 2) % rate;
        if (remainder != 0) {
                d->d_residue = (rate - remainder) / 16;
                data_dur++;
        }

        switch (rate) {
        case 2:         /* 1 Mb/s */
        case 4:         /* 2 Mb/s */
                /* 1 - 2 Mb/s WLAN: send ACK/CTS at 1 Mb/s */
                ctsrate = 2;
                break;
        case 11:        /* 5.5 Mb/s */
        case 22:        /* 11  Mb/s */
        case 44:        /* 22  Mb/s */
                /* 5.5 - 11 Mb/s WLAN: send ACK/CTS at 2 Mb/s */
                ctsrate = 4;
                break;
        default:
                /* TBD */
                return -1;
        }

        d->d_plcp_len = data_dur;

        ack = (use_ack) ? pre + (IEEE80211_DUR_DS_SLOW_ACK * 2) / ctsrate : 0;

        d->d_rts_dur =
            pre + (IEEE80211_DUR_DS_SLOW_CTS * 2) / ctsrate +
            pre + data_dur +
            ack;

        d->d_data_dur = ack;

        return 0;
}

/*
 * Arguments in:
 *
 * wh:      802.11 header
 *
 * paylen:  payload length (no FCS, no WEP header)
 *
 * rate:    MSDU speed, units 500kb/s
 *
 * fraglen: fragment length, set to maximum (or higher) for no
 *          fragmentation
 *
 * flags:   IEEE80211_F_PRIVACY (hardware adds WEP),
 *          IEEE80211_F_SHPREAMBLE (use short preamble),
 *          IEEE80211_F_SHSLOT (use short slot length)
 *
 * Arguments out:
 *
 * d0: 802.11 Duration fields (RTS/Data), PLCP Length, Service fields
 *     of first/only fragment
 *
 * dn: 802.11 Duration fields (RTS/Data), PLCP Length, Service fields
 *     of last fragment
 *
 * ieee80211_compute_duration assumes crypto-encapsulation, if any,
 * has already taken place.
 */
int
ieee80211_compute_duration(const struct ieee80211_frame_min *wh,
    const struct ieee80211_key *wk, int len,
    uint32_t icflags, int fraglen, int rate, struct ieee80211_duration *d0,
    struct ieee80211_duration *dn, int *npktp, int debug)
{
        int ack, rc;
        int cryptolen,  /* crypto overhead: header+trailer */
            firstlen,   /* first fragment's payload + overhead length */
            hdrlen,     /* header length w/o driver padding */
            lastlen,    /* last fragment's payload length w/ overhead */
            lastlen0,   /* last fragment's payload length w/o overhead */
            npkt,       /* number of fragments */
            overlen,    /* non-802.11 header overhead per fragment */
            paylen;     /* payload length w/o overhead */

        hdrlen = ieee80211_anyhdrsize((const void *)wh);

        /* Account for padding required by the driver. */
        if (icflags & IEEE80211_F_DATAPAD) {
                paylen = len - roundup(hdrlen, sizeof(u_int32_t));
                if (paylen < 0) {
                        panic("%s: paylen < 0", __func__);
                }
        } else {
                paylen = len - hdrlen;
        }

        overlen = IEEE80211_CRC_LEN;

        if (wk != NULL) {
                cryptolen = wk->wk_cipher->ic_header +
                            wk->wk_cipher->ic_trailer;
                paylen -= cryptolen;
                overlen += cryptolen;
        }

        npkt = paylen / fraglen;
        lastlen0 = paylen % fraglen;

        if (npkt == 0)                  /* no fragments */
                lastlen = paylen + overlen;
        else if (lastlen0 != 0) {       /* a short "tail" fragment */
                lastlen = lastlen0 + overlen;
                npkt++;
        } else                          /* full-length "tail" fragment */
                lastlen = fraglen + overlen;

        if (npktp != NULL)
                *npktp = npkt;

        if (npkt > 1)
                firstlen = fraglen + overlen;
        else
                firstlen = paylen + overlen;

        if (debug) {
                printf("%s: npkt %d firstlen %d lastlen0 %d lastlen %d "
                    "fraglen %d overlen %d len %d rate %d icflags %08x\n",
                    __func__, npkt, firstlen, lastlen0, lastlen, fraglen,
                    overlen, len, rate, icflags);
        }

        ack = !IEEE80211_IS_MULTICAST(wh->i_addr1) &&
            (wh->i_fc[1] & IEEE80211_FC0_TYPE_MASK) != IEEE80211_FC0_TYPE_CTL;

        rc = ieee80211_compute_duration1(firstlen + hdrlen,
            ack, icflags, rate, d0);
        if (rc == -1)
                return rc;

        if (npkt <= 1) {
                *dn = *d0;
                return 0;
        }
        return ieee80211_compute_duration1(lastlen + hdrlen, ack, icflags, rate,
            dn);
}

/*
 * Fragment the frame according to the specified mtu.
 * 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.
 */
static int
ieee80211_fragment(struct ieee80211com *ic, struct mbuf *m0,
        u_int hdrsize, u_int ciphdrsize, u_int mtu)
{
        struct ieee80211_frame *wh, *whf;
        struct mbuf *m, *prev, *next;
        const u_int totalhdrsize = hdrsize + ciphdrsize;
        u_int fragno, fragsize, off, remainder, payload;

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

        wh = mtod(m0, struct ieee80211_frame *);
        /* NB: mark the first frag; it will be propagated below */
        wh->i_fc[1] |= IEEE80211_FC1_MORE_FRAG;

        fragno = 1;
        off = mtu - ciphdrsize;
        remainder = m0->m_pkthdr.len - off;
        prev = m0;
        do {
                fragsize = totalhdrsize + remainder;
                if (fragsize > mtu)
                        fragsize = mtu;
                IASSERT(fragsize < MCLBYTES,
                        ("fragment size %u too big!", fragsize));
                if (fragsize > MHLEN)
                        m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
                else
                        m = m_gethdr(M_DONTWAIT, MT_DATA);
                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).
                 */
                whf = mtod(m, struct ieee80211_frame *);
                memcpy(whf, wh, hdrsize);
                *(u_int16_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, u_int8_t *) + hdrsize);
                m->m_len = hdrsize + payload;
                m->m_pkthdr.len = hdrsize + 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);

        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;

        ic->ic_stats.is_tx_fragframes++;
        ic->ic_stats.is_tx_frags += fragno-1;

        return 1;

bad:
        /* reclaim fragments but leave original frame for caller to free */
        for (m = m0->m_nextpkt; m != NULL; m = next) {
                next = m->m_nextpkt;
                m->m_nextpkt = NULL;
                m_freem(m);
        }
        m0->m_nextpkt = NULL;

        return 0;
}

/*
 * Add a supported rates element id to a frame.
 */
u_int8_t *
ieee80211_add_rates(u_int8_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.
 */
u_int8_t *
ieee80211_add_xrates(u_int8_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 elemet to a frame.
 */
u_int8_t *
ieee80211_add_ssid(u_int8_t *frm, const u_int8_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 u_int8_t *
ieee80211_add_erp(u_int8_t *frm, struct ieee80211com *ic)
{
        u_int8_t erp;

        *frm++ = IEEE80211_ELEMID_ERP;
        *frm++ = 1;
        erp = 0;
        if (ic->ic_nonerpsta != 0)
                erp |= IEEE80211_ERP_NON_ERP_PRESENT;
        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;
}

static u_int8_t *
ieee80211_setup_wpa_ie(struct ieee80211com *ic, u_int8_t *ie)
{
#define WPA_OUI_BYTES           0x00, 0x50, 0xf2
#define ADDSHORT(frm, v) do {                   \
        frm[0] = (v) & 0xff;                    \
        frm[1] = (v) >> 8;                      \
        frm += 2;                               \
} while (0)
#define ADDSELECTOR(frm, sel) do {              \
        memcpy(frm, sel, 4);                    \
        frm += 4;                               \
} while (0)
        static const u_int8_t oui[4] = { WPA_OUI_BYTES, WPA_OUI_TYPE };
        static const u_int8_t cipher_suite[][4] = {
                { WPA_OUI_BYTES, WPA_CSE_WEP40 },       /* NB: 40-bit */
                { WPA_OUI_BYTES, WPA_CSE_TKIP },
                { 0x00, 0x00, 0x00, 0x00 },             /* XXX WRAP */
                { WPA_OUI_BYTES, WPA_CSE_CCMP },
                { 0x00, 0x00, 0x00, 0x00 },             /* XXX CKIP */
                { WPA_OUI_BYTES, WPA_CSE_NULL },
        };
        static const u_int8_t wep104_suite[4] =
                { WPA_OUI_BYTES, WPA_CSE_WEP104 };
        static const u_int8_t key_mgt_unspec[4] =
                { WPA_OUI_BYTES, WPA_ASE_8021X_UNSPEC };
        static const u_int8_t key_mgt_psk[4] =
                { WPA_OUI_BYTES, WPA_ASE_8021X_PSK };
        const struct ieee80211_rsnparms *rsn = &ic->ic_bss->ni_rsn;
        u_int8_t *frm = ie;
        u_int8_t *selcnt;

        *frm++ = IEEE80211_ELEMID_VENDOR;
        *frm++ = 0;                             /* length filled in below */
        memcpy(frm, oui, sizeof(oui));          /* WPA OUI */
        frm += sizeof(oui);
        ADDSHORT(frm, WPA_VERSION);

        /* XXX filter out CKIP */

        /* multicast cipher */
        if (rsn->rsn_mcastcipher == IEEE80211_CIPHER_WEP &&
            rsn->rsn_mcastkeylen >= 13)
                ADDSELECTOR(frm, wep104_suite);
        else
                ADDSELECTOR(frm, cipher_suite[rsn->rsn_mcastcipher]);

        /* unicast cipher list */
        selcnt = frm;
        ADDSHORT(frm, 0);                       /* selector count */
        if (rsn->rsn_ucastcipherset & (1 << IEEE80211_CIPHER_AES_CCM)) {
                selcnt[0]++;
                ADDSELECTOR(frm, cipher_suite[IEEE80211_CIPHER_AES_CCM]);
        }
        if (rsn->rsn_ucastcipherset & (1 << IEEE80211_CIPHER_TKIP)) {
                selcnt[0]++;
                ADDSELECTOR(frm, cipher_suite[IEEE80211_CIPHER_TKIP]);
        }

        /* authenticator selector list */
        selcnt = frm;
        ADDSHORT(frm, 0);                       /* selector count */
        if (rsn->rsn_keymgmtset & WPA_ASE_8021X_UNSPEC) {
                selcnt[0]++;
                ADDSELECTOR(frm, key_mgt_unspec);
        }
        if (rsn->rsn_keymgmtset & WPA_ASE_8021X_PSK) {
                selcnt[0]++;
                ADDSELECTOR(frm, key_mgt_psk);
        }

        /* optional capabilities */
        if (rsn->rsn_caps != 0 && rsn->rsn_caps != RSN_CAP_PREAUTH)
                ADDSHORT(frm, rsn->rsn_caps);

        /* calculate element length */
        ie[1] = frm - ie - 2;
        IASSERT(ie[1]+2 <= sizeof(struct ieee80211_ie_wpa),
                ("WPA IE too big, %u > %zu",
                ie[1]+2, sizeof(struct ieee80211_ie_wpa)));
        return frm;
#undef ADDSHORT
#undef ADDSELECTOR
#undef WPA_OUI_BYTES
}

static u_int8_t *
ieee80211_setup_rsn_ie(struct ieee80211com *ic, u_int8_t *ie)
{
#define RSN_OUI_BYTES           0x00, 0x0f, 0xac
#define ADDSHORT(frm, v) do {                   \
        frm[0] = (v) & 0xff;                    \
        frm[1] = (v) >> 8;                      \
        frm += 2;                               \
} while (0)
#define ADDSELECTOR(frm, sel) do {              \
        memcpy(frm, sel, 4);                    \
        frm += 4;                               \
} while (0)
        static const u_int8_t cipher_suite[][4] = {
                { RSN_OUI_BYTES, RSN_CSE_WEP40 },       /* NB: 40-bit */
                { RSN_OUI_BYTES, RSN_CSE_TKIP },
                { RSN_OUI_BYTES, RSN_CSE_WRAP },
                { RSN_OUI_BYTES, RSN_CSE_CCMP },
                { 0x00, 0x00, 0x00, 0x00 },             /* XXX CKIP */
                { RSN_OUI_BYTES, RSN_CSE_NULL },
        };
        static const u_int8_t wep104_suite[4] =
                { RSN_OUI_BYTES, RSN_CSE_WEP104 };
        static const u_int8_t key_mgt_unspec[4] =
                { RSN_OUI_BYTES, RSN_ASE_8021X_UNSPEC };
        static const u_int8_t key_mgt_psk[4] =
                { RSN_OUI_BYTES, RSN_ASE_8021X_PSK };
        const struct ieee80211_rsnparms *rsn = &ic->ic_bss->ni_rsn;
        u_int8_t *frm = ie;
        u_int8_t *selcnt;

        *frm++ = IEEE80211_ELEMID_RSN;
        *frm++ = 0;                             /* length filled in below */
        ADDSHORT(frm, RSN_VERSION);

        /* XXX filter out CKIP */

        /* multicast cipher */
        if (rsn->rsn_mcastcipher == IEEE80211_CIPHER_WEP &&
            rsn->rsn_mcastkeylen >= 13)
                ADDSELECTOR(frm, wep104_suite);
        else
                ADDSELECTOR(frm, cipher_suite[rsn->rsn_mcastcipher]);

        /* unicast cipher list */
        selcnt = frm;
        ADDSHORT(frm, 0);                       /* selector count */
        if (rsn->rsn_ucastcipherset & (1 << IEEE80211_CIPHER_AES_CCM)) {
                selcnt[0]++;
                ADDSELECTOR(frm, cipher_suite[IEEE80211_CIPHER_AES_CCM]);
        }
        if (rsn->rsn_ucastcipherset & (1 << IEEE80211_CIPHER_TKIP)) {
                selcnt[0]++;
                ADDSELECTOR(frm, cipher_suite[IEEE80211_CIPHER_TKIP]);
        }

        /* authenticator selector list */
        selcnt = frm;
        ADDSHORT(frm, 0);                       /* selector count */
        if (rsn->rsn_keymgmtset & WPA_ASE_8021X_UNSPEC) {
                selcnt[0]++;
                ADDSELECTOR(frm, key_mgt_unspec);
        }
        if (rsn->rsn_keymgmtset & WPA_ASE_8021X_PSK) {
                selcnt[0]++;
                ADDSELECTOR(frm, key_mgt_psk);
        }

        /* optional capabilities */
        ADDSHORT(frm, rsn->rsn_caps);
        /* XXX PMKID */

        /* calculate element length */
        ie[1] = frm - ie - 2;
        IASSERT(ie[1]+2 <= sizeof(struct ieee80211_ie_wpa),
                ("RSN IE too big, %u > %zu",
                ie[1]+2, sizeof(struct ieee80211_ie_wpa)));
        return frm;
#undef ADDSELECTOR
#undef ADDSHORT
#undef RSN_OUI_BYTES
}

/*
 * Add a WPA/RSN element to a frame.
 */
u_int8_t *
ieee80211_add_wpa(u_int8_t *frm, struct ieee80211com *ic)
{

        IASSERT(ic->ic_flags & IEEE80211_F_WPA, ("no WPA/RSN!"));
        if (ic->ic_flags & IEEE80211_F_WPA2)
                frm = ieee80211_setup_rsn_ie(ic, frm);
        if (ic->ic_flags & IEEE80211_F_WPA1)
                frm = ieee80211_setup_wpa_ie(ic, frm);
        return frm;
}

#define WME_OUI_BYTES           0x00, 0x50, 0xf2
/*
 * Add a WME information element to a frame.
 */
u_int8_t *
ieee80211_add_wme_info(u_int8_t *frm, struct ieee80211_wme_state *wme)
{
        static const struct ieee80211_wme_info info = {
                .wme_id         = IEEE80211_ELEMID_VENDOR,
                .wme_len        = sizeof(struct ieee80211_wme_info) - 2,
                .wme_oui        = { WME_OUI_BYTES },
                .wme_type       = WME_OUI_TYPE,
                .wme_subtype    = WME_INFO_OUI_SUBTYPE,
                .wme_version    = WME_VERSION,
                .wme_info       = 0,
        };
        memcpy(frm, &info, sizeof(info));
        return frm + sizeof(info);
}

/*
 * Add a WME parameters element to a frame.
 */
static u_int8_t *
ieee80211_add_wme_param(u_int8_t *frm, struct ieee80211_wme_state *wme)
{
#define SM(_v, _f)      (((_v) << _f##_S) & _f)
#define ADDSHORT(frm, v) do {                   \
        frm[0] = (v) & 0xff;                    \
        frm[1] = (v) >> 8;                      \
        frm += 2;                               \
} while (0)
        /* NB: this works because 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 */
        *frm++ = 0;                                     /* reserved field */
        for (i = 0; i < WME_NUM_AC; i++) {
                const struct wmeParams *ac =
                       &wme->wme_bssChanParams.cap_wmeParams[i];
                *frm++ = SM(i, WME_PARAM_ACI) |
                    SM(ac->wmep_acm, WME_PARAM_ACM) |
                    SM(ac->wmep_aifsn, WME_PARAM_AIFSN);
                *frm++ = SM(ac->wmep_logcwmax, WME_PARAM_LOGCWMAX) |
                    SM(ac->wmep_logcwmin, WME_PARAM_LOGCWMIN);
                ADDSHORT(frm, ac->wmep_txopLimit);
        }

        return frm;
#undef SM
#undef ADDSHORT
}
#undef WME_OUI_BYTES

/*
 * Send a probe request frame with the specified ssid
 * and any optional information element data.
 */
int
ieee80211_send_probereq(struct ieee80211_node *ni,
        const u_int8_t sa[IEEE80211_ADDR_LEN],
        const u_int8_t da[IEEE80211_ADDR_LEN],
        const u_int8_t bssid[IEEE80211_ADDR_LEN],
        const u_int8_t *ssid, size_t ssidlen,
        const void *optie, size_t optielen)
{
        struct ieee80211com *ic = ni->ni_ic;
        enum ieee80211_phymode mode;
        struct ieee80211_frame *wh;
        struct mbuf *m;
        u_int8_t *frm;

        /*
         * 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(ic, 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);

        /*
         * prreq frame format
         *      [tlv] ssid
         *      [tlv] supported rates
         *      [tlv] extended supported rates
         *      [tlv] user-specified ie's
         */
        m = ieee80211_getmgtframe(&frm,
                 2 + IEEE80211_NWID_LEN
               + 2 + IEEE80211_RATE_SIZE
               + 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE)
               + (optie != NULL ? optielen : 0)
        );
        if (m == NULL) {
                ic->ic_stats.is_tx_nobuf++;
                ieee80211_free_node(ni);
                return ENOMEM;
        }

        frm = ieee80211_add_ssid(frm, ssid, ssidlen);
        mode = ieee80211_chan2mode(ic, ic->ic_curchan);
        frm = ieee80211_add_rates(frm, &ic->ic_sup_rates[mode]);
        frm = ieee80211_add_xrates(frm, &ic->ic_sup_rates[mode]);

        if (optie != NULL) {
                memcpy(frm, optie, optielen);
                frm += optielen;
        }
        m->m_pkthdr.len = m->m_len = frm - mtod(m, u_int8_t *);

        M_PREPEND(m, sizeof(struct ieee80211_frame), M_DONTWAIT);
        if (m == NULL) {
                ic->ic_stats.is_tx_nobuf++;
                ieee80211_free_node(ni);
                return ENOMEM;
        }
        M_SETCTX(m, ni);

        wh = mtod(m, struct ieee80211_frame *);
        ieee80211_send_setup(ic, ni, wh,
            IEEE80211_FC0_TYPE_MGT | IEEE80211_FC0_SUBTYPE_PROBE_REQ,
            sa, da, bssid);
        /* XXX power management? */

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

        IEEE80211_DPRINTF(ic, IEEE80211_MSG_DEBUG | IEEE80211_MSG_DUMPPKTS,
            "[%s] send probe req on channel %u\n",
            ether_sprintf(wh->i_addr1),
            ieee80211_chan2ieee(ic, ic->ic_curchan));

        IF_ENQUEUE(&ic->ic_mgtq, m);
        if_start_lock(ic->ic_ifp);
        return 0;
}

/*
 * 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 ieee80211com *ic, struct ieee80211_node *ni,
        int type, int arg)
{
#define senderr(_x, _v) do { ic->ic_stats._v++; ret = _x; goto bad; } while (0)
        struct mbuf *m;
        u_int8_t *frm;
        u_int16_t capinfo;
        int ret, timer, status;

        IASSERT(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(ic, 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);

        timer = 0;
        switch (type) {
        case IEEE80211_FC0_SUBTYPE_PROBE_RESP: {
                const bool has_wpa = (ic->ic_flags & IEEE80211_F_WPA) != 0;

                /*
                 * 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] extended rate phy (ERP)
                 *      [tlv] extended supported rates
                 *      [tlv] WPA
                 *      [tlv] WME (optional)
                 */
                m = ieee80211_getmgtframe(&frm,
                         8 /* timestamp */
                       + sizeof(u_int16_t) /* interval */
                       + sizeof(u_int16_t) /* capinfo */
                       + 2 + IEEE80211_NWID_LEN /* ssid */
                       + 2 + IEEE80211_RATE_SIZE /* rates */
                       + 7 /* max(7,3) */
                       + 6 /* ibss (XXX could be 4?) */
                       + 3 /* erp */
                       + 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE)
                       /* XXX !WPA1+WPA2 fits w/o a cluster */
                       + (has_wpa ? (2 * sizeof(struct ieee80211_ie_wpa)) : 0)
                       + sizeof(struct ieee80211_wme_param)
                );
                if (m == NULL)
                        senderr(ENOMEM, is_tx_nobuf);

                /* timestamp (should be filled later) */
                memset(frm, 0, 8);
                frm += 8;

                /* interval */
                *(u_int16_t *)frm = htole16(ic->ic_bss->ni_intval);
                frm += 2;

                /* capinfo */
                if (ic->ic_opmode == IEEE80211_M_IBSS)
                        capinfo = IEEE80211_CAPINFO_IBSS;
                else
                        capinfo = IEEE80211_CAPINFO_ESS;
                if (ic->ic_flags & IEEE80211_F_PRIVACY)
                        capinfo |= IEEE80211_CAPINFO_PRIVACY;
                if ((ic->ic_flags & IEEE80211_F_SHPREAMBLE) &&
                    IEEE80211_IS_CHAN_2GHZ(ic->ic_curchan))
                        capinfo |= IEEE80211_CAPINFO_SHORT_PREAMBLE;
                if (ic->ic_flags & IEEE80211_F_SHSLOT)
                        capinfo |= IEEE80211_CAPINFO_SHORT_SLOTTIME;
                *(u_int16_t *)frm = htole16(capinfo);
                frm += 2;

                /* ssid */
                frm = ieee80211_add_ssid(frm, ic->ic_bss->ni_essid,
                    ic->ic_bss->ni_esslen);

                /* rates */
                frm = ieee80211_add_rates(frm, &ni->ni_rates);

                /* variable */
                if (ic->ic_phytype == IEEE80211_T_FH) {
                        *frm++ = IEEE80211_ELEMID_FHPARMS;
                        *frm++ = 5;
                        *frm++ = ni->ni_fhdwell & 0x00ff;
                        *frm++ = (ni->ni_fhdwell >> 8) & 0x00ff;
                        *frm++ = IEEE80211_FH_CHANSET(
                            ieee80211_chan2ieee(ic, ic->ic_curchan));
                        *frm++ = IEEE80211_FH_CHANPAT(
                            ieee80211_chan2ieee(ic, ic->ic_curchan));
                        *frm++ = ni->ni_fhindex;
                } else {
                        *frm++ = IEEE80211_ELEMID_DSPARMS;
                        *frm++ = 1;
                        *frm++ = ieee80211_chan2ieee(ic, ic->ic_curchan);
                }

                /* ibss */
                if (ic->ic_opmode == IEEE80211_M_IBSS) {
                        *frm++ = IEEE80211_ELEMID_IBSSPARMS;
                        *frm++ = 2;
                        *frm++ = 0; *frm++ = 0; /* TODO: ATIM window */
                }

                /* wpa */
                if (has_wpa)
                        frm = ieee80211_add_wpa(frm, ic);

                /* erp */
                if (ic->ic_curmode == IEEE80211_MODE_11G)
                        frm = ieee80211_add_erp(frm, ic);

                /* xrates */
                frm = ieee80211_add_xrates(frm, &ni->ni_rates);

                /* wme */
                if (ic->ic_flags & IEEE80211_F_WME)
                        frm = ieee80211_add_wme_param(frm, &ic->ic_wme);

                m->m_pkthdr.len = m->m_len = frm - mtod(m, u_int8_t *);
                break;
        }

        case IEEE80211_FC0_SUBTYPE_AUTH: {
                status = arg >> 16;
                arg &= 0xffff;
                const bool 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.
                 */
                const bool is_shared_key = has_challenge ||
                    (arg >= IEEE80211_AUTH_SHARED_RESPONSE) ||
                    (arg == IEEE80211_AUTH_SHARED_REQUEST &&
                     ic->ic_bss->ni_authmode == IEEE80211_AUTH_SHARED);

                const bool need_challenge =
                    has_challenge && (status == IEEE80211_STATUS_SUCCESS);

                const int frm_size = 3 * sizeof(u_int16_t)
                        + (need_challenge ?
                                sizeof(u_int16_t)+IEEE80211_CHALLENGE_LEN : 0);

                m = ieee80211_getmgtframe(&frm, frm_size);
                if (m == NULL)
                        senderr(ENOMEM, is_tx_nobuf);

                ((u_int16_t *)frm)[0] =
                      is_shared_key ? htole16(IEEE80211_AUTH_ALG_SHARED)
                                    : htole16(IEEE80211_AUTH_ALG_OPEN);
                ((u_int16_t *)frm)[1] = htole16(arg);   /* sequence number */
                ((u_int16_t *)frm)[2] = htole16(status);/* status */

                if (need_challenge) {
                        ((u_int16_t *)frm)[3] =
                            htole16((IEEE80211_CHALLENGE_LEN << 8) |
                            IEEE80211_ELEMID_CHALLENGE);
                        memcpy(&((u_int16_t *)frm)[4], ni->ni_challenge,
                            IEEE80211_CHALLENGE_LEN);

                        if (arg == IEEE80211_AUTH_SHARED_RESPONSE) {
                                IEEE80211_DPRINTF(ic, IEEE80211_MSG_AUTH,
                                    "[%s] request encrypt frame (%s)\n",
                                    ether_sprintf(ni->ni_macaddr), __func__);
                                m->m_flags |= M_LINK0; /* WEP-encrypt, please */
                        }
                }

                m->m_pkthdr.len = m->m_len = frm_size;

                /* 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 (ic->ic_opmode == IEEE80211_M_STA)
                        timer = IEEE80211_TRANS_WAIT;
                break;
        }

        case IEEE80211_FC0_SUBTYPE_DEAUTH:
                IEEE80211_DPRINTF(ic, IEEE80211_MSG_AUTH,
                        "[%s] send station deauthenticate (reason %d)\n",
                        ether_sprintf(ni->ni_macaddr), arg);
                m = ieee80211_getmgtframe(&frm, sizeof(u_int16_t));
                if (m == NULL)
                        senderr(ENOMEM, is_tx_nobuf);
                *(u_int16_t *)frm = htole16(arg);       /* reason */
                m->m_pkthdr.len = m->m_len = sizeof(u_int16_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
                 *      [tlv] WME
                 *      [tlv] user-specified ie's
                 */
                m = ieee80211_getmgtframe(&frm,
                         sizeof(u_int16_t)
                       + sizeof(u_int16_t)
                       + IEEE80211_ADDR_LEN
                       + 2 + IEEE80211_NWID_LEN
                       + 2 + IEEE80211_RATE_SIZE
                       + 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE)
                       + sizeof(struct ieee80211_wme_info)
                       + (ic->ic_opt_ie != NULL ? ic->ic_opt_ie_len : 0)
                );
                if (m == NULL)
                        senderr(ENOMEM, is_tx_nobuf);

                capinfo = 0;
                if (ic->ic_opmode == IEEE80211_M_IBSS)
                        capinfo |= IEEE80211_CAPINFO_IBSS;
                else /* IEEE80211_M_STA */
                        capinfo |= IEEE80211_CAPINFO_ESS;
                if (ic->ic_flags & IEEE80211_F_PRIVACY)
                        capinfo |= IEEE80211_CAPINFO_PRIVACY;
                /*
                 * NB: Some 11a AP's reject the request when
                 *     short premable is set.
                 */
                if ((ic->ic_flags & IEEE80211_F_SHPREAMBLE) &&
                    IEEE80211_IS_CHAN_2GHZ(ic->ic_curchan))
                        capinfo |= IEEE80211_CAPINFO_SHORT_PREAMBLE;
                if ((ni->ni_capinfo & IEEE80211_CAPINFO_SHORT_SLOTTIME) &&
                    (ic->ic_caps & IEEE80211_C_SHSLOT))
                        capinfo |= IEEE80211_CAPINFO_SHORT_SLOTTIME;
                *(u_int16_t *)frm = htole16(capinfo);
                frm += 2;

                *(u_int16_t *)frm = htole16(ic->ic_lintval);
                frm += 2;

                if (type == IEEE80211_FC0_SUBTYPE_REASSOC_REQ) {
                        IEEE80211_ADDR_COPY(frm, ic->ic_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_xrates(frm, &ni->ni_rates);
                if ((ic->ic_flags & IEEE80211_F_WME) && ni->ni_wme_ie != NULL)
                        frm = ieee80211_add_wme_info(frm, &ic->ic_wme);
                if (ic->ic_opt_ie != NULL) {
                        memcpy(frm, ic->ic_opt_ie, ic->ic_opt_ie_len);
                        frm += ic->ic_opt_ie_len;
                }
                m->m_pkthdr.len = m->m_len = frm - mtod(m, u_int8_t *);

                timer = IEEE80211_TRANS_WAIT;
                break;

        case IEEE80211_FC0_SUBTYPE_ASSOC_RESP:
        case IEEE80211_FC0_SUBTYPE_REASSOC_RESP:
                /*
                 * asreq frame format
                 *      [2] capability information
                 *      [2] status
                 *      [2] association ID
                 *      [tlv] supported rates
                 *      [tlv] extended supported rates
                 *      [tlv] WME (if enabled and STA enabled)
                 */
                m = ieee80211_getmgtframe(&frm,
                         sizeof(u_int16_t)
                       + sizeof(u_int16_t)
                       + sizeof(u_int16_t)
                       + 2 + IEEE80211_RATE_SIZE
                       + 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE)
                       + sizeof(struct ieee80211_wme_param)
                );
                if (m == NULL)
                        senderr(ENOMEM, is_tx_nobuf);

                capinfo = IEEE80211_CAPINFO_ESS;
                if (ic->ic_flags & IEEE80211_F_PRIVACY)
                        capinfo |= IEEE80211_CAPINFO_PRIVACY;
                if ((ic->ic_flags & IEEE80211_F_SHPREAMBLE) &&
                    IEEE80211_IS_CHAN_2GHZ(ic->ic_curchan))
                        capinfo |= IEEE80211_CAPINFO_SHORT_PREAMBLE;
                if (ic->ic_flags & IEEE80211_F_SHSLOT)
                        capinfo |= IEEE80211_CAPINFO_SHORT_SLOTTIME;
                *(u_int16_t *)frm = htole16(capinfo);
                frm += 2;

                *(u_int16_t *)frm = htole16(arg);       /* status */
                frm += 2;

                if (arg == IEEE80211_STATUS_SUCCESS) {
                        *(u_int16_t *)frm = htole16(ni->ni_associd);
                        IEEE80211_NODE_STAT(ni, tx_assoc);
                } else {
                        *(u_int16_t *)frm = 0;
                        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);
                if ((ic->ic_flags & IEEE80211_F_WME) && ni->ni_wme_ie != NULL)
                        frm = ieee80211_add_wme_param(frm, &ic->ic_wme);
                m->m_pkthdr.len = m->m_len = frm - mtod(m, u_int8_t *);
                break;

        case IEEE80211_FC0_SUBTYPE_DISASSOC:
                IEEE80211_DPRINTF(ic, IEEE80211_MSG_ASSOC,
                        "[%s] send station disassociate (reason %d)\n",
                        ether_sprintf(ni->ni_macaddr), arg);
                m = ieee80211_getmgtframe(&frm, sizeof(u_int16_t));
                if (m == NULL)
                        senderr(ENOMEM, is_tx_nobuf);
                *(u_int16_t *)frm = htole16(arg);       /* reason */
                m->m_pkthdr.len = m->m_len = sizeof(u_int16_t);

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

        default:
                IEEE80211_DPRINTF(ic, IEEE80211_MSG_ANY,
                        "[%s] invalid mgmt frame type %u\n",
                        ether_sprintf(ni->ni_macaddr), type);
                senderr(EINVAL, is_tx_unknownmgt);
                /* NOTREACHED */
        }
        ret = ieee80211_mgmt_output(ic, ni, m, type, timer);
        if (ret != 0) {
bad:
                ieee80211_free_node(ni);
        }
        return ret;
#undef senderr
}

/*
 * Build a RTS (Request To Send) control frame.
 */
struct mbuf *
ieee80211_get_rts(struct ieee80211com *ic, const struct ieee80211_frame *wh,
    uint16_t dur)
{
        struct ieee80211_frame_rts *rts;
        struct mbuf *m;

        MGETHDR(m, M_DONTWAIT, MT_DATA);
        if (m == NULL)
                return NULL;

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

        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;
        *(uint16_t *)rts->i_dur = htole16(dur);
        IEEE80211_ADDR_COPY(rts->i_ra, wh->i_addr1);
        IEEE80211_ADDR_COPY(rts->i_ta, wh->i_addr2);

        return m;
}

/*
 * Build a CTS-to-self (Clear To Send) control frame.
 */
struct mbuf *
ieee80211_get_cts_to_self(struct ieee80211com *ic, uint16_t dur)
{
        struct ieee80211_frame_cts *cts;
        struct mbuf *m;

        MGETHDR(m, M_DONTWAIT, MT_DATA);
        if (m == NULL)
                return NULL;

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

        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;
        *(uint16_t *)cts->i_dur = htole16(dur);
        IEEE80211_ADDR_COPY(cts->i_ra, ic->ic_myaddr);

        return m;
}

/*
 * Allocate a beacon frame and fill in the appropriate bits.
 */
struct mbuf *
ieee80211_beacon_alloc(struct ieee80211com *ic, struct ieee80211_node *ni,
        struct ieee80211_beacon_offsets *bo)
{
        struct ifnet *ifp = ic->ic_ifp;
        struct ieee80211_frame *wh;
        struct mbuf *m;
        int pktlen;
        u_int8_t *frm, *efrm;
        u_int16_t capinfo;
        struct ieee80211_rateset *rs;

        rs = &ni->ni_rates;

        /*
         * beacon frame format
         *      [8] time stamp
         *      [2] beacon interval
         *      [2] cabability information
         *      [tlv] ssid
         *      [tlv] supported rates
         *      [3] parameter set (DS)
         *      [tlv] parameter set (IBSS/TIM)
         *      [tlv] extended rate phy (ERP)
         *      [tlv] extended supported rates
         *      [tlv] WME parameters
         *      [tlv] WPA/RSN parameters
         * XXX Vendor-specific OIDs (e.g. Atheros)
         *
         * NB: we allocate the max space required for the TIM bitmap
         * (ic_tim_len).
         */
        pktlen =   8                                    /* time stamp */
                 + sizeof(u_int16_t)                    /* beacon interval */
                 + sizeof(u_int16_t)                    /* capabilities */
                 + 2 + ni->ni_esslen                    /* ssid */
                 + 2 + IEEE80211_RATE_SIZE              /* supported rates */
                 + 2 + 1                                /* DS parameters */
                 + 2 + 4 + ic->ic_tim_len               /* DTIM/IBSSPARMS */
                 + 2 + 1                                /* ERP */
                 + 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE)
                 + (ic->ic_caps & IEEE80211_C_WME ?     /* WME */
                        sizeof(struct ieee80211_wme_param) : 0)
                 + (ic->ic_caps & IEEE80211_C_WPA ?     /* WPA 1+2 */
                        2*sizeof(struct ieee80211_ie_wpa) : 0)
                 ;
        m = ieee80211_getmgtframe(&frm, pktlen);
        if (m == NULL) {
                IEEE80211_DPRINTF(ic, IEEE80211_MSG_ANY,
                        "%s: cannot get buf; size %u\n", __func__, pktlen);
                ic->ic_stats.is_tx_nobuf++;
                return NULL;
        }

        memset(frm, 0, 8);      /* XXX timestamp is set by hardware/driver */
        frm += 8;

        *(u_int16_t *)frm = htole16(ni->ni_intval);
        frm += 2;

        if (ic->ic_opmode == IEEE80211_M_IBSS)
                capinfo = IEEE80211_CAPINFO_IBSS;
        else
                capinfo = IEEE80211_CAPINFO_ESS;
        if (ic->ic_flags & IEEE80211_F_PRIVACY)
                capinfo |= IEEE80211_CAPINFO_PRIVACY;
        if ((ic->ic_flags & IEEE80211_F_SHPREAMBLE) &&
            IEEE80211_IS_CHAN_2GHZ(ni->ni_chan))
                capinfo |= IEEE80211_CAPINFO_SHORT_PREAMBLE;
        if (ic->ic_flags & IEEE80211_F_SHSLOT)
                capinfo |= IEEE80211_CAPINFO_SHORT_SLOTTIME;
        bo->bo_caps = (u_int16_t *)frm;
        *(u_int16_t *)frm = htole16(capinfo);
        frm += 2;

        *frm++ = IEEE80211_ELEMID_SSID;
        if ((ic->ic_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 (ic->ic_curmode != IEEE80211_MODE_FH) {
                *frm++ = IEEE80211_ELEMID_DSPARMS;
                *frm++ = 1;
                *frm++ = ieee80211_chan2ieee(ic, ni->ni_chan);
        }

        bo->bo_tim = frm;
        if (ic->ic_opmode == IEEE80211_M_IBSS) {
                *frm++ = IEEE80211_ELEMID_IBSSPARMS;
                *frm++ = 2;
                *frm++ = 0; *frm++ = 0;         /* TODO: ATIM window */
                bo->bo_tim_len = 0;
        } else {
                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 = ic->ic_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_trailer = frm;
        if (ic->ic_flags & IEEE80211_F_WME) {
                bo->bo_wme = frm;
                frm = ieee80211_add_wme_param(frm, &ic->ic_wme);
                ic->ic_flags &= ~IEEE80211_F_WMEUPDATE;
        }

        if (ic->ic_flags & IEEE80211_F_WPA)
                frm = ieee80211_add_wpa(frm, ic);

        if (ic->ic_curmode == IEEE80211_MODE_11G)
                frm = ieee80211_add_erp(frm, ic);

        efrm = ieee80211_add_xrates(frm, rs);

        bo->bo_trailer_len = efrm - bo->bo_trailer;
        m->m_pkthdr.len = m->m_len = efrm - mtod(m, u_int8_t *);

        M_PREPEND(m, sizeof(struct ieee80211_frame), M_DONTWAIT);
        IASSERT(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;
        *(u_int16_t *)wh->i_dur = 0;
        IEEE80211_ADDR_COPY(wh->i_addr1, ifp->if_broadcastaddr);
        IEEE80211_ADDR_COPY(wh->i_addr2, ic->ic_myaddr);
        IEEE80211_ADDR_COPY(wh->i_addr3, ni->ni_bssid);
        *(u_int16_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 ieee80211com *ic, struct ieee80211_node *ni,
    struct ieee80211_beacon_offsets *bo, struct mbuf *m, int mcast)
{
        int len_changed = 0;
        u_int16_t capinfo;

        IEEE80211_BEACON_LOCK(ic);

        /* XXX faster to recalculate entirely or just changes? */
        if (ic->ic_opmode == IEEE80211_M_IBSS)
                capinfo = IEEE80211_CAPINFO_IBSS;
        else
                capinfo = IEEE80211_CAPINFO_ESS;
        if (ic->ic_flags & IEEE80211_F_PRIVACY)
                capinfo |= IEEE80211_CAPINFO_PRIVACY;
        if ((ic->ic_flags & IEEE80211_F_SHPREAMBLE) &&
            IEEE80211_IS_CHAN_2GHZ(ni->ni_chan))
                capinfo |= IEEE80211_CAPINFO_SHORT_PREAMBLE;
        if (ic->ic_flags & IEEE80211_F_SHSLOT)
                capinfo |= IEEE80211_CAPINFO_SHORT_SLOTTIME;
        *bo->bo_caps = htole16(capinfo);

        if (ic->ic_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(ic, 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(ic);
                                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(ic, 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(ic);
                                wme->wme_hipri_traffic = 0;
                        } else
                                wme->wme_hipri_traffic =
                                        wme->wme_hipri_switch_hysteresis;
                }
                if (ic->ic_flags & IEEE80211_F_WMEUPDATE) {
                        (void)ieee80211_add_wme_param(bo->bo_wme, wme);
                        ic->ic_flags &= ~IEEE80211_F_WMEUPDATE;
                }
        }

#ifndef IEEE80211_NO_HOSTAP
        if (ic->ic_opmode == IEEE80211_M_HOSTAP) {      /* NB: no IBSS support*/
                struct ieee80211_tim_ie *tie =
                        (struct ieee80211_tim_ie *)bo->bo_tim;
                if (ic->ic_flags & IEEE80211_F_TIMUPDATE) {
                        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 ic_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 (ic->ic_ps_pending != 0) {
                                timoff = 128;           /* impossibly large */
                                for (i = 0; i < ic->ic_tim_len; i++)
                                        if (ic->ic_tim_bitmap[i]) {
                                                timoff = i &~ 1;
                                                break;
                                        }
                                IASSERT(timoff != 128, ("tim bitmap empty!"));
                                for (i = ic->ic_tim_len-1; i >= timoff; i--)
                                        if (ic->ic_tim_bitmap[i])
                                                break;
                                timlen = 1 + (i - timoff);
                        } else {
                                timoff = 0;
                                timlen = 1;
                        }
                        if (timlen != bo->bo_tim_len) {
                                /* copy up/down trailer */
                                memmove(tie->tim_bitmap+timlen, bo->bo_trailer,
                                        bo->bo_trailer_len);
                                bo->bo_trailer = tie->tim_bitmap+timlen;
                                bo->bo_wme = bo->bo_trailer;
                                bo->bo_tim_len = timlen;

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

                        ic->ic_flags &= ~IEEE80211_F_TIMUPDATE;

                        IEEE80211_DPRINTF(ic, IEEE80211_MSG_POWER,
                                "%s: TIM updated, pending %u, off %u, len %u\n",
                                __func__, ic->ic_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 == 1 || tie->tim_period == 1))
                        tie->tim_bitctl |= 1;
                else
                        tie->tim_bitctl &= ~1;
        }
#endif /* !IEEE80211_NO_HOSTAP */

        IEEE80211_BEACON_UNLOCK(ic);

        return len_changed;
}

/*
 * Save an outbound packet for a node in power-save sleep state.
 * The new packet is placed on the node's saved queue, and the TIM
 * is changed, if necessary.
 */
void
ieee80211_pwrsave(struct ieee80211com *ic, struct ieee80211_node *ni, 
    struct mbuf *m)
{
        int qlen, age;

        IEEE80211_NODE_SAVEQ_LOCK(ni);
        if (IF_QFULL(&ni->ni_savedq)) {
                IF_DROP(&ni->ni_savedq);
                IEEE80211_NODE_SAVEQ_UNLOCK(ni);

                IEEE80211_DPRINTF(ic, IEEE80211_MSG_ANY,
                    "[%s] pwr save q overflow, drops %" PRIu64
                    " (size %d)\n",
                    ether_sprintf(ni->ni_macaddr), 
                    ni->ni_savedq.ifq_drops, IEEE80211_PS_MAX_QUEUE);
#ifdef IEEE80211_DEBUG
                if (ieee80211_msg_dumppkts(ic))
                        ieee80211_dump_pkt(mtod(m, void *), m->m_len, -1, -1);
#endif

                m_freem(m);
                return;
        }

        /*
         * Tag the frame with its expiry time and insert
         * it in the queue.  The aging interval is 4 times
         * the listen interval specified by the station. 
         * Frames that sit around too long are reclaimed
         * using this information.
         */
        /* XXX handle overflow? */
        age = ((ni->ni_intval * ic->ic_bintval) << 2) / 1024; /* TU -> secs */
        _IEEE80211_NODE_SAVEQ_ENQUEUE(ni, m, qlen, age);
        IEEE80211_NODE_SAVEQ_UNLOCK(ni);

        IEEE80211_DPRINTF(ic, IEEE80211_MSG_POWER,
                "[%s] save frame with age %d, %u now queued\n",
                ether_sprintf(ni->ni_macaddr), age, qlen);

        if (qlen == 1)
                ic->ic_set_tim(ni, 1);
}