xref: /freebsd/sys/net80211/ieee80211_output.c (revision f0adf7f5cdd241db2f2c817683191a6ef64a4e95)
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("$FreeBSD$");
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  */
76 static int
77 ieee80211_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  */
146 struct mbuf *
147 ieee80211_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 			ic->ic_stats.is_tx_nombuf++;
159 			goto bad;
160 		}
161 	}
162 	memcpy(&eh, mtod(m, caddr_t), sizeof(struct ether_header));
163 
164 	ni = ieee80211_find_txnode(ic, eh.ether_dhost);
165 	if (ni == NULL) {
166 		IEEE80211_DPRINTF(("%s: no node for dst %s, discard frame\n",
167 			__func__, ether_sprintf(eh.ether_dhost)));
168 		ic->ic_stats.is_tx_nonode++;
169 		goto bad;
170 	}
171 	ni->ni_inact = 0;
172 
173 	m_adj(m, sizeof(struct ether_header) - sizeof(struct llc));
174 	llc = mtod(m, struct llc *);
175 	llc->llc_dsap = llc->llc_ssap = LLC_SNAP_LSAP;
176 	llc->llc_control = LLC_UI;
177 	llc->llc_snap.org_code[0] = 0;
178 	llc->llc_snap.org_code[1] = 0;
179 	llc->llc_snap.org_code[2] = 0;
180 	llc->llc_snap.ether_type = eh.ether_type;
181 	M_PREPEND(m, sizeof(struct ieee80211_frame), M_DONTWAIT);
182 	if (m == NULL) {
183 		ic->ic_stats.is_tx_nombuf++;
184 		goto bad;
185 	}
186 	wh = mtod(m, struct ieee80211_frame *);
187 	wh->i_fc[0] = IEEE80211_FC0_VERSION_0 | IEEE80211_FC0_TYPE_DATA;
188 	*(u_int16_t *)wh->i_dur = 0;
189 	*(u_int16_t *)wh->i_seq =
190 	    htole16(ni->ni_txseq << IEEE80211_SEQ_SEQ_SHIFT);
191 	ni->ni_txseq++;
192 	switch (ic->ic_opmode) {
193 	case IEEE80211_M_STA:
194 		wh->i_fc[1] = IEEE80211_FC1_DIR_TODS;
195 		IEEE80211_ADDR_COPY(wh->i_addr1, ni->ni_bssid);
196 		IEEE80211_ADDR_COPY(wh->i_addr2, eh.ether_shost);
197 		IEEE80211_ADDR_COPY(wh->i_addr3, eh.ether_dhost);
198 		break;
199 	case IEEE80211_M_IBSS:
200 	case IEEE80211_M_AHDEMO:
201 		wh->i_fc[1] = IEEE80211_FC1_DIR_NODS;
202 		IEEE80211_ADDR_COPY(wh->i_addr1, eh.ether_dhost);
203 		IEEE80211_ADDR_COPY(wh->i_addr2, eh.ether_shost);
204 		IEEE80211_ADDR_COPY(wh->i_addr3, ni->ni_bssid);
205 		break;
206 	case IEEE80211_M_HOSTAP:
207 		wh->i_fc[1] = IEEE80211_FC1_DIR_FROMDS;
208 		IEEE80211_ADDR_COPY(wh->i_addr1, eh.ether_dhost);
209 		IEEE80211_ADDR_COPY(wh->i_addr2, ni->ni_bssid);
210 		IEEE80211_ADDR_COPY(wh->i_addr3, eh.ether_shost);
211 		break;
212 	case IEEE80211_M_MONITOR:
213 		goto bad;
214 	}
215 	*pni = ni;
216 	return m;
217 bad:
218 	if (m != NULL)
219 		m_freem(m);
220 	if (ni && ni != ic->ic_bss)
221 		ieee80211_free_node(ic, ni);
222 	*pni = NULL;
223 	return NULL;
224 }
225 
226 /*
227  * Add a supported rates element id to a frame.
228  */
229 u_int8_t *
230 ieee80211_add_rates(u_int8_t *frm, const struct ieee80211_rateset *rs)
231 {
232 	int nrates;
233 
234 	*frm++ = IEEE80211_ELEMID_RATES;
235 	nrates = rs->rs_nrates;
236 	if (nrates > IEEE80211_RATE_SIZE)
237 		nrates = IEEE80211_RATE_SIZE;
238 	*frm++ = nrates;
239 	memcpy(frm, rs->rs_rates, nrates);
240 	return frm + nrates;
241 }
242 
243 /*
244  * Add an extended supported rates element id to a frame.
245  */
246 u_int8_t *
247 ieee80211_add_xrates(u_int8_t *frm, const struct ieee80211_rateset *rs)
248 {
249 	/*
250 	 * Add an extended supported rates element if operating in 11g mode.
251 	 */
252 	if (rs->rs_nrates > IEEE80211_RATE_SIZE) {
253 		int nrates = rs->rs_nrates - IEEE80211_RATE_SIZE;
254 		*frm++ = IEEE80211_ELEMID_XRATES;
255 		*frm++ = nrates;
256 		memcpy(frm, rs->rs_rates + IEEE80211_RATE_SIZE, nrates);
257 		frm += nrates;
258 	}
259 	return frm;
260 }
261 
262 /*
263  * Add an ssid elemet to a frame.
264  */
265 static u_int8_t *
266 ieee80211_add_ssid(u_int8_t *frm, const u_int8_t *ssid, u_int len)
267 {
268 	*frm++ = IEEE80211_ELEMID_SSID;
269 	*frm++ = len;
270 	memcpy(frm, ssid, len);
271 	return frm + len;
272 }
273 
274 static struct mbuf *
275 ieee80211_getmbuf(int flags, int type, u_int pktlen)
276 {
277 	struct mbuf *m;
278 
279 	KASSERT(pktlen <= MCLBYTES, ("802.11 packet too large: %u", pktlen));
280 	if (pktlen <= MHLEN)
281 		MGETHDR(m, flags, type);
282 	else
283 		m = m_getcl(flags, type, M_PKTHDR);
284 	return m;
285 }
286 
287 /*
288  * Send a management frame.  The node is for the destination (or ic_bss
289  * when in station mode).  Nodes other than ic_bss have their reference
290  * count bumped to reflect our use for an indeterminant time.
291  */
292 int
293 ieee80211_send_mgmt(struct ieee80211com *ic, struct ieee80211_node *ni,
294 	int type, int arg)
295 {
296 #define	senderr(_x, _v)	do { ic->ic_stats._v++; ret = _x; goto bad; } while (0)
297 	struct ifnet *ifp = &ic->ic_if;
298 	struct mbuf *m;
299 	u_int8_t *frm;
300 	enum ieee80211_phymode mode;
301 	u_int16_t capinfo;
302 	int ret, timer;
303 
304 	KASSERT(ni != NULL, ("null node"));
305 
306 	/*
307 	 * Hold a reference on the node so it doesn't go away until after
308 	 * the xmit is complete all the way in the driver.  On error we
309 	 * will remove our reference.
310 	 */
311 	if (ni != ic->ic_bss)
312 		ieee80211_ref_node(ni);
313 	timer = 0;
314 	switch (type) {
315 	case IEEE80211_FC0_SUBTYPE_PROBE_REQ:
316 		/*
317 		 * prreq frame format
318 		 *	[tlv] ssid
319 		 *	[tlv] supported rates
320 		 *	[tlv] extended supported rates
321 		 */
322 		m = ieee80211_getmbuf(M_DONTWAIT, MT_DATA,
323 			 2 + ic->ic_des_esslen
324 		       + 2 + IEEE80211_RATE_SIZE
325 		       + 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE));
326 		if (m == NULL)
327 			senderr(ENOMEM, is_tx_nombuf);
328 		m->m_data += sizeof(struct ieee80211_frame);
329 		frm = mtod(m, u_int8_t *);
330 		frm = ieee80211_add_ssid(frm, ic->ic_des_essid, ic->ic_des_esslen);
331 		mode = ieee80211_chan2mode(ic, ni->ni_chan);
332 		frm = ieee80211_add_rates(frm, &ic->ic_sup_rates[mode]);
333 		frm = ieee80211_add_xrates(frm, &ic->ic_sup_rates[mode]);
334 		m->m_pkthdr.len = m->m_len = frm - mtod(m, u_int8_t *);
335 
336 		timer = IEEE80211_TRANS_WAIT;
337 		break;
338 
339 	case IEEE80211_FC0_SUBTYPE_PROBE_RESP:
340 		/*
341 		 * probe response frame format
342 		 *	[8] time stamp
343 		 *	[2] beacon interval
344 		 *	[2] cabability information
345 		 *	[tlv] ssid
346 		 *	[tlv] supported rates
347 		 *	[tlv] parameter set (FH/DS)
348 		 *	[tlv] parameter set (IBSS)
349 		 *	[tlv] extended supported rates
350 		 */
351 		m = ieee80211_getmbuf(M_DONTWAIT, MT_DATA,
352 			 8 + 2 + 2 + 2
353 		       + 2 + ni->ni_esslen
354 		       + 2 + IEEE80211_RATE_SIZE
355 		       + (ic->ic_phytype == IEEE80211_T_FH ? 7 : 3)
356 		       + 6
357 		       + 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE));
358 		if (m == NULL)
359 			senderr(ENOMEM, is_tx_nombuf);
360 		m->m_data += sizeof(struct ieee80211_frame);
361 		frm = mtod(m, u_int8_t *);
362 
363 		memset(frm, 0, 8);	/* timestamp should be filled later */
364 		frm += 8;
365 		*(u_int16_t *)frm = htole16(ic->ic_bss->ni_intval);
366 		frm += 2;
367 		if (ic->ic_opmode == IEEE80211_M_IBSS)
368 			capinfo = IEEE80211_CAPINFO_IBSS;
369 		else
370 			capinfo = IEEE80211_CAPINFO_ESS;
371 		if (ic->ic_flags & IEEE80211_F_WEPON)
372 			capinfo |= IEEE80211_CAPINFO_PRIVACY;
373 		if ((ic->ic_flags & IEEE80211_F_SHPREAMBLE) &&
374 		    IEEE80211_IS_CHAN_2GHZ(ni->ni_chan))
375 			capinfo |= IEEE80211_CAPINFO_SHORT_PREAMBLE;
376 		*(u_int16_t *)frm = htole16(capinfo);
377 		frm += 2;
378 
379 		frm = ieee80211_add_ssid(frm, ic->ic_bss->ni_essid,
380 				ic->ic_bss->ni_esslen);
381 		frm = ieee80211_add_rates(frm, &ic->ic_bss->ni_rates);
382 
383 		if (ic->ic_phytype == IEEE80211_T_FH) {
384                         *frm++ = IEEE80211_ELEMID_FHPARMS;
385                         *frm++ = 5;
386                         *frm++ = ni->ni_fhdwell & 0x00ff;
387                         *frm++ = (ni->ni_fhdwell >> 8) & 0x00ff;
388                         *frm++ = IEEE80211_FH_CHANSET(
389 			    ieee80211_chan2ieee(ic, ni->ni_chan));
390                         *frm++ = IEEE80211_FH_CHANPAT(
391 			    ieee80211_chan2ieee(ic, ni->ni_chan));
392                         *frm++ = ni->ni_fhindex;
393 		} else {
394 			*frm++ = IEEE80211_ELEMID_DSPARMS;
395 			*frm++ = 1;
396 			*frm++ = ieee80211_chan2ieee(ic, ni->ni_chan);
397 		}
398 
399 		if (ic->ic_opmode == IEEE80211_M_IBSS) {
400 			*frm++ = IEEE80211_ELEMID_IBSSPARMS;
401 			*frm++ = 2;
402 			*frm++ = 0; *frm++ = 0;		/* TODO: ATIM window */
403 		} else {	/* IEEE80211_M_HOSTAP */
404 			/* TODO: TIM */
405 			*frm++ = IEEE80211_ELEMID_TIM;
406 			*frm++ = 4;	/* length */
407 			*frm++ = 0;	/* DTIM count */
408 			*frm++ = 1;	/* DTIM period */
409 			*frm++ = 0;	/* bitmap control */
410 			*frm++ = 0;	/* Partial Virtual Bitmap (variable length) */
411 		}
412 		frm = ieee80211_add_xrates(frm, &ic->ic_bss->ni_rates);
413 		m->m_pkthdr.len = m->m_len = frm - mtod(m, u_int8_t *);
414 		break;
415 
416 	case IEEE80211_FC0_SUBTYPE_AUTH:
417 		MGETHDR(m, M_DONTWAIT, MT_DATA);
418 		if (m == NULL)
419 			senderr(ENOMEM, is_tx_nombuf);
420 		MH_ALIGN(m, 2 * 3);
421 		m->m_pkthdr.len = m->m_len = 6;
422 		frm = mtod(m, u_int8_t *);
423 		/* TODO: shared key auth */
424 		((u_int16_t *)frm)[0] = htole16(IEEE80211_AUTH_ALG_OPEN);
425 		((u_int16_t *)frm)[1] = htole16(arg);	/* sequence number */
426 		((u_int16_t *)frm)[2] = 0;		/* status */
427 		if (ic->ic_opmode == IEEE80211_M_STA)
428 			timer = IEEE80211_TRANS_WAIT;
429 		break;
430 
431 	case IEEE80211_FC0_SUBTYPE_DEAUTH:
432 		if (ifp->if_flags & IFF_DEBUG)
433 			if_printf(ifp, "station %s deauthenticate (reason %d)\n",
434 			    ether_sprintf(ni->ni_macaddr), arg);
435 		MGETHDR(m, M_DONTWAIT, MT_DATA);
436 		if (m == NULL)
437 			senderr(ENOMEM, is_tx_nombuf);
438 		MH_ALIGN(m, 2);
439 		m->m_pkthdr.len = m->m_len = 2;
440 		*mtod(m, u_int16_t *) = htole16(arg);	/* reason */
441 		break;
442 
443 	case IEEE80211_FC0_SUBTYPE_ASSOC_REQ:
444 	case IEEE80211_FC0_SUBTYPE_REASSOC_REQ:
445 		/*
446 		 * asreq frame format
447 		 *	[2] capability information
448 		 *	[2] listen interval
449 		 *	[6*] current AP address (reassoc only)
450 		 *	[tlv] ssid
451 		 *	[tlv] supported rates
452 		 *	[tlv] extended supported rates
453 		 */
454 		m = ieee80211_getmbuf(M_DONTWAIT, MT_DATA,
455 			 sizeof(capinfo)
456 		       + sizeof(u_int16_t)
457 		       + IEEE80211_ADDR_LEN
458 		       + 2 + ni->ni_esslen
459 		       + 2 + IEEE80211_RATE_SIZE
460 		       + 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE));
461 		if (m == NULL)
462 			senderr(ENOMEM, is_tx_nombuf);
463 		m->m_data += sizeof(struct ieee80211_frame);
464 		frm = mtod(m, u_int8_t *);
465 
466 		capinfo = 0;
467 		if (ic->ic_opmode == IEEE80211_M_IBSS)
468 			capinfo |= IEEE80211_CAPINFO_IBSS;
469 		else		/* IEEE80211_M_STA */
470 			capinfo |= IEEE80211_CAPINFO_ESS;
471 		if (ic->ic_flags & IEEE80211_F_WEPON)
472 			capinfo |= IEEE80211_CAPINFO_PRIVACY;
473 		/*
474 		 * NB: Some 11a AP's reject the request when
475 		 *     short premable is set.
476 		 */
477 		if ((ic->ic_flags & IEEE80211_F_SHPREAMBLE) &&
478 		    IEEE80211_IS_CHAN_2GHZ(ni->ni_chan))
479 			capinfo |= IEEE80211_CAPINFO_SHORT_PREAMBLE;
480 		if (ic->ic_flags & IEEE80211_F_SHSLOT)
481 			capinfo |= IEEE80211_CAPINFO_SHORT_SLOTTIME;
482 		*(u_int16_t *)frm = htole16(capinfo);
483 		frm += 2;
484 
485 		*(u_int16_t *)frm = htole16(ic->ic_lintval);
486 		frm += 2;
487 
488 		if (type == IEEE80211_FC0_SUBTYPE_REASSOC_REQ) {
489 			IEEE80211_ADDR_COPY(frm, ic->ic_bss->ni_bssid);
490 			frm += IEEE80211_ADDR_LEN;
491 		}
492 
493 		frm = ieee80211_add_ssid(frm, ni->ni_essid, ni->ni_esslen);
494 		frm = ieee80211_add_rates(frm, &ni->ni_rates);
495 		frm = ieee80211_add_xrates(frm, &ni->ni_rates);
496 		m->m_pkthdr.len = m->m_len = frm - mtod(m, u_int8_t *);
497 
498 		timer = IEEE80211_TRANS_WAIT;
499 		break;
500 
501 	case IEEE80211_FC0_SUBTYPE_ASSOC_RESP:
502 	case IEEE80211_FC0_SUBTYPE_REASSOC_RESP:
503 		/*
504 		 * asreq frame format
505 		 *	[2] capability information
506 		 *	[2] status
507 		 *	[2] association ID
508 		 *	[tlv] supported rates
509 		 *	[tlv] extended supported rates
510 		 */
511 		m = ieee80211_getmbuf(M_DONTWAIT, MT_DATA,
512 			 sizeof(capinfo)
513 		       + sizeof(u_int16_t)
514 		       + sizeof(u_int16_t)
515 		       + 2 + IEEE80211_RATE_SIZE
516 		       + 2 + (IEEE80211_RATE_MAXSIZE - IEEE80211_RATE_SIZE));
517 		if (m == NULL)
518 			senderr(ENOMEM, is_tx_nombuf);
519 		m->m_data += sizeof(struct ieee80211_frame);
520 		frm = mtod(m, u_int8_t *);
521 
522 		capinfo = IEEE80211_CAPINFO_ESS;
523 		if (ic->ic_flags & IEEE80211_F_WEPON)
524 			capinfo |= IEEE80211_CAPINFO_PRIVACY;
525 		if ((ic->ic_flags & IEEE80211_F_SHPREAMBLE) &&
526 		    IEEE80211_IS_CHAN_2GHZ(ni->ni_chan))
527 			capinfo |= IEEE80211_CAPINFO_SHORT_PREAMBLE;
528 		*(u_int16_t *)frm = htole16(capinfo);
529 		frm += 2;
530 
531 		*(u_int16_t *)frm = htole16(arg);	/* status */
532 		frm += 2;
533 
534 		if (arg == IEEE80211_STATUS_SUCCESS)
535 			*(u_int16_t *)frm = htole16(ni->ni_associd);
536 		frm += 2;
537 
538 		frm = ieee80211_add_rates(frm, &ni->ni_rates);
539 		frm = ieee80211_add_xrates(frm, &ni->ni_rates);
540 		m->m_pkthdr.len = m->m_len = frm - mtod(m, u_int8_t *);
541 		break;
542 
543 	case IEEE80211_FC0_SUBTYPE_DISASSOC:
544 		if (ifp->if_flags & IFF_DEBUG)
545 			if_printf(ifp, "station %s disassociate (reason %d)\n",
546 			    ether_sprintf(ni->ni_macaddr), arg);
547 		MGETHDR(m, M_DONTWAIT, MT_DATA);
548 		if (m == NULL)
549 			senderr(ENOMEM, is_tx_nombuf);
550 		MH_ALIGN(m, 2);
551 		m->m_pkthdr.len = m->m_len = 2;
552 		*mtod(m, u_int16_t *) = htole16(arg);	/* reason */
553 		break;
554 
555 	default:
556 		IEEE80211_DPRINTF(("%s: invalid mgmt frame type %u\n",
557 			__func__, type));
558 		senderr(EINVAL, is_tx_unknownmgt);
559 		/* NOTREACHED */
560 	}
561 
562 	ret = ieee80211_mgmt_output(ifp, ni, m, type);
563 	if (ret == 0) {
564 		if (timer)
565 			ic->ic_mgt_timer = timer;
566 	} else {
567 bad:
568 		if (ni != ic->ic_bss)		/* remove ref we added */
569 			ieee80211_free_node(ic, ni);
570 	}
571 	return ret;
572 #undef senderr
573 }
574