ieee80211_output.c revision 121178
1/*-
2 * Copyright (c) 2001 Atsushi Onoe
3 * Copyright (c) 2002, 2003 Sam Leffler, Errno Consulting
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. The name of the author may not be used to endorse or promote products
15 *    derived from this software without specific prior written permission.
16 *
17 * Alternatively, this software may be distributed under the terms of the
18 * GNU General Public License ("GPL") version 2 as published by the Free
19 * Software Foundation.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33#include <sys/cdefs.h>
34__FBSDID("$FreeBSD: head/sys/net80211/ieee80211_output.c 121178 2003-10-17 22:09:20Z sam $");
35
36#include "opt_inet.h"
37
38#include <sys/param.h>
39#include <sys/systm.h>
40#include <sys/mbuf.h>
41#include <sys/malloc.h>
42#include <sys/kernel.h>
43#include <sys/socket.h>
44#include <sys/sockio.h>
45#include <sys/endian.h>
46#include <sys/errno.h>
47#include <sys/bus.h>
48#include <sys/proc.h>
49#include <sys/sysctl.h>
50
51#include <machine/atomic.h>
52
53#include <net/if.h>
54#include <net/if_dl.h>
55#include <net/if_media.h>
56#include <net/if_arp.h>
57#include <net/ethernet.h>
58#include <net/if_llc.h>
59
60#include <net80211/ieee80211_var.h>
61
62#include <net/bpf.h>
63
64#ifdef INET
65#include <netinet/in.h>
66#include <netinet/if_ether.h>
67#endif
68
69/*
70 * Send a management frame to the specified node.  The node pointer
71 * must have a reference as the pointer will be passed to the driver
72 * and potentially held for a long time.  If the frame is successfully
73 * dispatched to the driver, then it is responsible for freeing the
74 * reference (and potentially free'ing up any associated storage).
75 */
76static int
77ieee80211_mgmt_output(struct ifnet *ifp, struct ieee80211_node *ni,
78    struct mbuf *m, int type)
79{
80	struct ieee80211com *ic = (void *)ifp;
81	struct ieee80211_frame *wh;
82
83	KASSERT(ni != NULL, ("null node"));
84	ni->ni_inact = 0;
85
86	/*
87	 * Yech, hack alert!  We want to pass the node down to the
88	 * driver's start routine.  If we don't do so then the start
89	 * routine must immediately look it up again and that can
90	 * cause a lock order reversal if, for example, this frame
91	 * is being sent because the station is being timedout and
92	 * the frame being sent is a DEAUTH message.  We could stick
93	 * this in an m_tag and tack that on to the mbuf.  However
94	 * that's rather expensive to do for every frame so instead
95	 * we stuff it in the rcvif field since outbound frames do
96	 * not (presently) use this.
97	 */
98	M_PREPEND(m, sizeof(struct ieee80211_frame), M_DONTWAIT);
99	if (m == NULL)
100		return ENOMEM;
101	KASSERT(m->m_pkthdr.rcvif == NULL, ("rcvif not null"));
102	m->m_pkthdr.rcvif = (void *)ni;
103
104	wh = mtod(m, struct ieee80211_frame *);
105	wh->i_fc[0] = IEEE80211_FC0_VERSION_0 | IEEE80211_FC0_TYPE_MGT | type;
106	wh->i_fc[1] = IEEE80211_FC1_DIR_NODS;
107	*(u_int16_t *)wh->i_dur = 0;
108	*(u_int16_t *)wh->i_seq =
109	    htole16(ni->ni_txseq << IEEE80211_SEQ_SEQ_SHIFT);
110	ni->ni_txseq++;
111	IEEE80211_ADDR_COPY(wh->i_addr1, ni->ni_macaddr);
112	IEEE80211_ADDR_COPY(wh->i_addr2, ic->ic_myaddr);
113	IEEE80211_ADDR_COPY(wh->i_addr3, ni->ni_bssid);
114
115	if (ifp->if_flags & IFF_DEBUG) {
116		/* avoid to print too many frames */
117		if (ic->ic_opmode == IEEE80211_M_IBSS ||
118#ifdef IEEE80211_DEBUG
119		    ieee80211_debug > 1 ||
120#endif
121		    (type & IEEE80211_FC0_SUBTYPE_MASK) !=
122		    IEEE80211_FC0_SUBTYPE_PROBE_RESP)
123			if_printf(ifp, "sending %s to %s on channel %u\n",
124			    ieee80211_mgt_subtype_name[
125			    (type & IEEE80211_FC0_SUBTYPE_MASK)
126			    >> IEEE80211_FC0_SUBTYPE_SHIFT],
127			    ether_sprintf(ni->ni_macaddr),
128			    ieee80211_chan2ieee(ic, ni->ni_chan));
129	}
130
131	IF_ENQUEUE(&ic->ic_mgtq, m);
132	ifp->if_timer = 1;
133	(*ifp->if_start)(ifp);
134	return 0;
135}
136
137/*
138 * Encapsulate an outbound data frame.  The mbuf chain is updated and
139 * a reference to the destination node is returned.  If an error is
140 * encountered NULL is returned and the node reference will also be NULL.
141 *
142 * NB: The caller is responsible for free'ing a returned node reference.
143 *     The convention is ic_bss is not reference counted; the caller must
144 *     maintain that.
145 */
146struct mbuf *
147ieee80211_encap(struct ifnet *ifp, struct mbuf *m, struct ieee80211_node **pni)
148{
149	struct ieee80211com *ic = (void *)ifp;
150	struct ether_header eh;
151	struct ieee80211_frame *wh;
152	struct ieee80211_node *ni = NULL;
153	struct llc *llc;
154
155	if (m->m_len < sizeof(struct ether_header)) {
156		m = m_pullup(m, sizeof(struct ether_header));
157		if (m == NULL) {
158			/* XXX statistic */
159			goto bad;
160		}
161	}
162	memcpy(&eh, mtod(m, caddr_t), sizeof(struct ether_header));
163
164	if (ic->ic_opmode != IEEE80211_M_STA) {
165		ni = ieee80211_find_node(ic, eh.ether_dhost);
166		if (ni == NULL) {
167			/*
168			 * When not in station mode the destination
169			 * address should always be in the node table
170			 * if the device sends management frames to us;
171			 * unless this is a multicast/broadcast frame.
172			 * For devices that don't send management frames
173			 * to the host we have to cheat; use the bss
174			 * node instead; the card will/should clobber
175			 * the bssid address as necessary.
176			 *
177			 * XXX this handles AHDEMO because all devices
178			 *     that support it don't send mgmt frames;
179			 *     but it might be better to test explicitly
180			 */
181			if (!IEEE80211_IS_MULTICAST(eh.ether_dhost) &&
182			    (ic->ic_caps & IEEE80211_C_RCVMGT)) {
183				IEEE80211_DPRINTF(("%s: no node for dst %s, "
184					"discard frame\n", __func__,
185					ether_sprintf(eh.ether_dhost)));
186				goto bad;
187			}
188			ni = ic->ic_bss;
189		}
190	} else
191		ni = ic->ic_bss;
192	ni->ni_inact = 0;
193
194	m_adj(m, sizeof(struct ether_header) - sizeof(struct llc));
195	llc = mtod(m, struct llc *);
196	llc->llc_dsap = llc->llc_ssap = LLC_SNAP_LSAP;
197	llc->llc_control = LLC_UI;
198	llc->llc_snap.org_code[0] = 0;
199	llc->llc_snap.org_code[1] = 0;
200	llc->llc_snap.org_code[2] = 0;
201	llc->llc_snap.ether_type = eh.ether_type;
202	M_PREPEND(m, sizeof(struct ieee80211_frame), M_DONTWAIT);
203	if (m == NULL)
204		goto bad;
205	wh = mtod(m, struct ieee80211_frame *);
206	wh->i_fc[0] = IEEE80211_FC0_VERSION_0 | IEEE80211_FC0_TYPE_DATA;
207	*(u_int16_t *)wh->i_dur = 0;
208	*(u_int16_t *)wh->i_seq =
209	    htole16(ni->ni_txseq << IEEE80211_SEQ_SEQ_SHIFT);
210	ni->ni_txseq++;
211	switch (ic->ic_opmode) {
212	case IEEE80211_M_STA:
213		wh->i_fc[1] = IEEE80211_FC1_DIR_TODS;
214		IEEE80211_ADDR_COPY(wh->i_addr1, ni->ni_bssid);
215		IEEE80211_ADDR_COPY(wh->i_addr2, eh.ether_shost);
216		IEEE80211_ADDR_COPY(wh->i_addr3, eh.ether_dhost);
217		break;
218	case IEEE80211_M_IBSS:
219	case IEEE80211_M_AHDEMO:
220		wh->i_fc[1] = IEEE80211_FC1_DIR_NODS;
221		IEEE80211_ADDR_COPY(wh->i_addr1, eh.ether_dhost);
222		IEEE80211_ADDR_COPY(wh->i_addr2, eh.ether_shost);
223		IEEE80211_ADDR_COPY(wh->i_addr3, ni->ni_bssid);
224		break;
225	case IEEE80211_M_HOSTAP:
226		wh->i_fc[1] = IEEE80211_FC1_DIR_FROMDS;
227		IEEE80211_ADDR_COPY(wh->i_addr1, eh.ether_dhost);
228		IEEE80211_ADDR_COPY(wh->i_addr2, ni->ni_bssid);
229		IEEE80211_ADDR_COPY(wh->i_addr3, eh.ether_shost);
230		break;
231	case IEEE80211_M_MONITOR:
232		goto bad;
233	}
234	*pni = ni;
235	return m;
236bad:
237	if (m != NULL)
238		m_freem(m);
239	if (ni && ni != ic->ic_bss)
240		ieee80211_free_node(ic, ni);
241	*pni = NULL;
242	return NULL;
243}
244
245/*
246 * Add a supported rates element id to a frame.
247 */
248u_int8_t *
249ieee80211_add_rates(u_int8_t *frm, const struct ieee80211_rateset *rs)
250{
251	int nrates;
252
253	*frm++ = IEEE80211_ELEMID_RATES;
254	nrates = rs->rs_nrates;
255	if (nrates > IEEE80211_RATE_SIZE)
256		nrates = IEEE80211_RATE_SIZE;
257	*frm++ = nrates;
258	memcpy(frm, rs->rs_rates, nrates);
259	return frm + nrates;
260}
261
262/*
263 * Add an extended supported rates element id to a frame.
264 */
265u_int8_t *
266ieee80211_add_xrates(u_int8_t *frm, const struct ieee80211_rateset *rs)
267{
268	/*
269	 * Add an extended supported rates element if operating in 11g mode.
270	 */
271	if (rs->rs_nrates > IEEE80211_RATE_SIZE) {
272		int nrates = rs->rs_nrates - IEEE80211_RATE_SIZE;
273		*frm++ = IEEE80211_ELEMID_XRATES;
274		*frm++ = nrates;
275		memcpy(frm, rs->rs_rates + IEEE80211_RATE_SIZE, nrates);
276		frm += nrates;
277	}
278	return frm;
279}
280
281/*
282 * Add an ssid elemet to a frame.
283 */
284static u_int8_t *
285ieee80211_add_ssid(u_int8_t *frm, const u_int8_t *ssid, u_int len)
286{
287	*frm++ = IEEE80211_ELEMID_SSID;
288	*frm++ = len;
289	memcpy(frm, ssid, len);
290	return frm + len;
291}
292
293static struct mbuf *
294ieee80211_getmbuf(int flags, int type, u_int pktlen)
295{
296	struct mbuf *m;
297
298	KASSERT(pktlen <= MCLBYTES, ("802.11 packet too large: %u", pktlen));
299	if (pktlen <= MHLEN)
300		MGETHDR(m, flags, type);
301	else
302		m = m_getcl(flags, type, M_PKTHDR);
303	return m;
304}
305
306/*
307 * Send a management frame.  The node is for the destination (or ic_bss
308 * when in station mode).  Nodes other than ic_bss have their reference
309 * count bumped to reflect our use for an indeterminant time.
310 */
311int
312ieee80211_send_mgmt(struct ieee80211com *ic, struct ieee80211_node *ni,
313	int type, int arg)
314{
315#define	senderr(_x)	do { ret = _x; goto bad; } while (0)
316	struct ifnet *ifp = &ic->ic_if;
317	struct mbuf *m;
318	u_int8_t *frm;
319	enum ieee80211_phymode mode;
320	u_int16_t capinfo;
321	int ret, timer;
322
323	KASSERT(ni != NULL, ("null node"));
324
325	/*
326	 * Hold a reference on the node so it doesn't go away until after
327	 * the xmit is complete all the way in the driver.  On error we
328	 * will remove our reference.
329	 */
330	if (ni != ic->ic_bss)
331		ieee80211_ref_node(ni);
332	timer = 0;
333	switch (type) {
334	case IEEE80211_FC0_SUBTYPE_PROBE_REQ:
335		/*
336		 * prreq frame format
337		 *	[tlv] ssid
338		 *	[tlv] supported rates
339		 *	[tlv] extended supported rates
340		 */
341		m = ieee80211_getmbuf(M_DONTWAIT, MT_DATA,
342			 2 + ic->ic_des_esslen
343		       + 2 + IEEE80211_RATE_SIZE
344		       + 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE));
345		if (m == NULL)
346			senderr(ENOMEM);
347		m->m_data += sizeof(struct ieee80211_frame);
348		frm = mtod(m, u_int8_t *);
349		frm = ieee80211_add_ssid(frm, ic->ic_des_essid, ic->ic_des_esslen);
350		mode = ieee80211_chan2mode(ic, ni->ni_chan);
351		frm = ieee80211_add_rates(frm, &ic->ic_sup_rates[mode]);
352		frm = ieee80211_add_xrates(frm, &ic->ic_sup_rates[mode]);
353		m->m_pkthdr.len = m->m_len = frm - mtod(m, u_int8_t *);
354
355		timer = IEEE80211_TRANS_WAIT;
356		break;
357
358	case IEEE80211_FC0_SUBTYPE_PROBE_RESP:
359		/*
360		 * probe response frame format
361		 *	[8] time stamp
362		 *	[2] beacon interval
363		 *	[2] cabability information
364		 *	[tlv] ssid
365		 *	[tlv] supported rates
366		 *	[tlv] parameter set (FH/DS)
367		 *	[tlv] parameter set (IBSS)
368		 *	[tlv] extended supported rates
369		 */
370		m = ieee80211_getmbuf(M_DONTWAIT, MT_DATA,
371			 8 + 2 + 2 + 2
372		       + 2 + ni->ni_esslen
373		       + 2 + IEEE80211_RATE_SIZE
374		       + (ic->ic_phytype == IEEE80211_T_FH ? 7 : 3)
375		       + 6
376		       + 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE));
377		if (m == NULL)
378			senderr(ENOMEM);
379		m->m_data += sizeof(struct ieee80211_frame);
380		frm = mtod(m, u_int8_t *);
381
382		memset(frm, 0, 8);	/* timestamp should be filled later */
383		frm += 8;
384		*(u_int16_t *)frm = htole16(ic->ic_bss->ni_intval);
385		frm += 2;
386		if (ic->ic_opmode == IEEE80211_M_IBSS)
387			capinfo = IEEE80211_CAPINFO_IBSS;
388		else
389			capinfo = IEEE80211_CAPINFO_ESS;
390		if (ic->ic_flags & IEEE80211_F_WEPON)
391			capinfo |= IEEE80211_CAPINFO_PRIVACY;
392		if ((ic->ic_flags & IEEE80211_F_SHPREAMBLE) &&
393		    IEEE80211_IS_CHAN_2GHZ(ni->ni_chan))
394			capinfo |= IEEE80211_CAPINFO_SHORT_PREAMBLE;
395		*(u_int16_t *)frm = htole16(capinfo);
396		frm += 2;
397
398		frm = ieee80211_add_ssid(frm, ic->ic_bss->ni_essid,
399				ic->ic_bss->ni_esslen);
400		frm = ieee80211_add_rates(frm, &ic->ic_bss->ni_rates);
401
402		if (ic->ic_phytype == IEEE80211_T_FH) {
403                        *frm++ = IEEE80211_ELEMID_FHPARMS;
404                        *frm++ = 5;
405                        *frm++ = ni->ni_fhdwell & 0x00ff;
406                        *frm++ = (ni->ni_fhdwell >> 8) & 0x00ff;
407                        *frm++ = IEEE80211_FH_CHANSET(
408			    ieee80211_chan2ieee(ic, ni->ni_chan));
409                        *frm++ = IEEE80211_FH_CHANPAT(
410			    ieee80211_chan2ieee(ic, ni->ni_chan));
411                        *frm++ = ni->ni_fhindex;
412		} else {
413			*frm++ = IEEE80211_ELEMID_DSPARMS;
414			*frm++ = 1;
415			*frm++ = ieee80211_chan2ieee(ic, ni->ni_chan);
416		}
417
418		if (ic->ic_opmode == IEEE80211_M_IBSS) {
419			*frm++ = IEEE80211_ELEMID_IBSSPARMS;
420			*frm++ = 2;
421			*frm++ = 0; *frm++ = 0;		/* TODO: ATIM window */
422		} else {	/* IEEE80211_M_HOSTAP */
423			/* TODO: TIM */
424			*frm++ = IEEE80211_ELEMID_TIM;
425			*frm++ = 4;	/* length */
426			*frm++ = 0;	/* DTIM count */
427			*frm++ = 1;	/* DTIM period */
428			*frm++ = 0;	/* bitmap control */
429			*frm++ = 0;	/* Partial Virtual Bitmap (variable length) */
430		}
431		frm = ieee80211_add_xrates(frm, &ic->ic_bss->ni_rates);
432		m->m_pkthdr.len = m->m_len = frm - mtod(m, u_int8_t *);
433		break;
434
435	case IEEE80211_FC0_SUBTYPE_AUTH:
436		MGETHDR(m, M_DONTWAIT, MT_DATA);
437		if (m == NULL)
438			senderr(ENOMEM);
439		MH_ALIGN(m, 2 * 3);
440		m->m_pkthdr.len = m->m_len = 6;
441		frm = mtod(m, u_int8_t *);
442		/* TODO: shared key auth */
443		((u_int16_t *)frm)[0] = htole16(IEEE80211_AUTH_ALG_OPEN);
444		((u_int16_t *)frm)[1] = htole16(arg);	/* sequence number */
445		((u_int16_t *)frm)[2] = 0;		/* status */
446		if (ic->ic_opmode == IEEE80211_M_STA)
447			timer = IEEE80211_TRANS_WAIT;
448		break;
449
450	case IEEE80211_FC0_SUBTYPE_DEAUTH:
451		if (ifp->if_flags & IFF_DEBUG)
452			if_printf(ifp, "station %s deauthenticate (reason %d)\n",
453			    ether_sprintf(ni->ni_macaddr), arg);
454		MGETHDR(m, M_DONTWAIT, MT_DATA);
455		if (m == NULL)
456			senderr(ENOMEM);
457		MH_ALIGN(m, 2);
458		m->m_pkthdr.len = m->m_len = 2;
459		*mtod(m, u_int16_t *) = htole16(arg);	/* reason */
460		break;
461
462	case IEEE80211_FC0_SUBTYPE_ASSOC_REQ:
463	case IEEE80211_FC0_SUBTYPE_REASSOC_REQ:
464		/*
465		 * asreq frame format
466		 *	[2] capability information
467		 *	[2] listen interval
468		 *	[6*] current AP address (reassoc only)
469		 *	[tlv] ssid
470		 *	[tlv] supported rates
471		 *	[tlv] extended supported rates
472		 */
473		m = ieee80211_getmbuf(M_DONTWAIT, MT_DATA,
474			 sizeof(capinfo)
475		       + sizeof(u_int16_t)
476		       + IEEE80211_ADDR_LEN
477		       + 2 + ni->ni_esslen
478		       + 2 + IEEE80211_RATE_SIZE
479		       + 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE));
480		if (m == NULL)
481			senderr(ENOMEM);
482		m->m_data += sizeof(struct ieee80211_frame);
483		frm = mtod(m, u_int8_t *);
484
485		capinfo = 0;
486		if (ic->ic_opmode == IEEE80211_M_IBSS)
487			capinfo |= IEEE80211_CAPINFO_IBSS;
488		else		/* IEEE80211_M_STA */
489			capinfo |= IEEE80211_CAPINFO_ESS;
490		if (ic->ic_flags & IEEE80211_F_WEPON)
491			capinfo |= IEEE80211_CAPINFO_PRIVACY;
492		/*
493		 * NB: Some 11a AP's reject the request when
494		 *     short premable is set.
495		 */
496		if ((ic->ic_flags & IEEE80211_F_SHPREAMBLE) &&
497		    IEEE80211_IS_CHAN_2GHZ(ni->ni_chan))
498			capinfo |= IEEE80211_CAPINFO_SHORT_PREAMBLE;
499		if (ic->ic_flags & IEEE80211_F_SHSLOT)
500			capinfo |= IEEE80211_CAPINFO_SHORT_SLOTTIME;
501		*(u_int16_t *)frm = htole16(capinfo);
502		frm += 2;
503
504		*(u_int16_t *)frm = htole16(ic->ic_lintval);
505		frm += 2;
506
507		if (type == IEEE80211_FC0_SUBTYPE_REASSOC_REQ) {
508			IEEE80211_ADDR_COPY(frm, ic->ic_bss->ni_bssid);
509			frm += IEEE80211_ADDR_LEN;
510		}
511
512		frm = ieee80211_add_ssid(frm, ni->ni_essid, ni->ni_esslen);
513		frm = ieee80211_add_rates(frm, &ni->ni_rates);
514		frm = ieee80211_add_xrates(frm, &ni->ni_rates);
515		m->m_pkthdr.len = m->m_len = frm - mtod(m, u_int8_t *);
516
517		timer = IEEE80211_TRANS_WAIT;
518		break;
519
520	case IEEE80211_FC0_SUBTYPE_ASSOC_RESP:
521	case IEEE80211_FC0_SUBTYPE_REASSOC_RESP:
522		/*
523		 * asreq frame format
524		 *	[2] capability information
525		 *	[2] status
526		 *	[2] association ID
527		 *	[tlv] supported rates
528		 *	[tlv] extended supported rates
529		 */
530		m = ieee80211_getmbuf(M_DONTWAIT, MT_DATA,
531			 sizeof(capinfo)
532		       + sizeof(u_int16_t)
533		       + sizeof(u_int16_t)
534		       + 2 + IEEE80211_RATE_SIZE
535		       + 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE));
536		if (m == NULL)
537			senderr(ENOMEM);
538		m->m_data += sizeof(struct ieee80211_frame);
539		frm = mtod(m, u_int8_t *);
540
541		capinfo = IEEE80211_CAPINFO_ESS;
542		if (ic->ic_flags & IEEE80211_F_WEPON)
543			capinfo |= IEEE80211_CAPINFO_PRIVACY;
544		if ((ic->ic_flags & IEEE80211_F_SHPREAMBLE) &&
545		    IEEE80211_IS_CHAN_2GHZ(ni->ni_chan))
546			capinfo |= IEEE80211_CAPINFO_SHORT_PREAMBLE;
547		*(u_int16_t *)frm = htole16(capinfo);
548		frm += 2;
549
550		*(u_int16_t *)frm = htole16(arg);	/* status */
551		frm += 2;
552
553		if (arg == IEEE80211_STATUS_SUCCESS)
554			*(u_int16_t *)frm = htole16(ni->ni_associd);
555		frm += 2;
556
557		frm = ieee80211_add_rates(frm, &ni->ni_rates);
558		frm = ieee80211_add_xrates(frm, &ni->ni_rates);
559		m->m_pkthdr.len = m->m_len = frm - mtod(m, u_int8_t *);
560		break;
561
562	case IEEE80211_FC0_SUBTYPE_DISASSOC:
563		if (ifp->if_flags & IFF_DEBUG)
564			if_printf(ifp, "station %s disassociate (reason %d)\n",
565			    ether_sprintf(ni->ni_macaddr), arg);
566		MGETHDR(m, M_DONTWAIT, MT_DATA);
567		if (m == NULL)
568			senderr(ENOMEM);
569		MH_ALIGN(m, 2);
570		m->m_pkthdr.len = m->m_len = 2;
571		*mtod(m, u_int16_t *) = htole16(arg);	/* reason */
572		break;
573
574	default:
575		IEEE80211_DPRINTF(("%s: invalid mgmt frame type %u\n",
576			__func__, type));
577		senderr(EINVAL);
578		/* NOTREACHED */
579	}
580
581	ret = ieee80211_mgmt_output(ifp, ni, m, type);
582	if (ret == 0) {
583		if (timer)
584			ic->ic_mgt_timer = timer;
585	} else {
586bad:
587		if (ni != ic->ic_bss)		/* remove ref we added */
588			ieee80211_free_node(ic, ni);
589	}
590	return ret;
591#undef senderr
592}
593