ieee80211_scan_sta.c revision 219601
1/*-
2 * Copyright (c) 2002-2009 Sam Leffler, Errno Consulting
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include <sys/cdefs.h>
27__FBSDID("$FreeBSD: head/sys/net80211/ieee80211_scan_sta.c 219601 2011-03-13 11:58:40Z bschmidt $");
28
29/*
30 * IEEE 802.11 station scanning support.
31 */
32#include "opt_wlan.h"
33
34#include <sys/param.h>
35#include <sys/systm.h>
36#include <sys/kernel.h>
37#include <sys/module.h>
38
39#include <sys/socket.h>
40
41#include <net/if.h>
42#include <net/if_media.h>
43#include <net/ethernet.h>
44
45#include <net80211/ieee80211_var.h>
46#include <net80211/ieee80211_input.h>
47#include <net80211/ieee80211_regdomain.h>
48#ifdef IEEE80211_SUPPORT_TDMA
49#include <net80211/ieee80211_tdma.h>
50#endif
51#ifdef IEEE80211_SUPPORT_MESH
52#include <net80211/ieee80211_mesh.h>
53#endif
54
55#include <net/bpf.h>
56
57/*
58 * Parameters for managing cache entries:
59 *
60 * o a station with STA_FAILS_MAX failures is not considered
61 *   when picking a candidate
62 * o a station that hasn't had an update in STA_PURGE_SCANS
63 *   (background) scans is discarded
64 * o after STA_FAILS_AGE seconds we clear the failure count
65 */
66#define	STA_FAILS_MAX	2		/* assoc failures before ignored */
67#define	STA_FAILS_AGE	(2*60)		/* time before clearing fails (secs) */
68#define	STA_PURGE_SCANS	2		/* age for purging entries (scans) */
69
70/* XXX tunable */
71#define	STA_RSSI_MIN	8		/* min acceptable rssi */
72#define	STA_RSSI_MAX	40		/* max rssi for comparison */
73
74struct sta_entry {
75	struct ieee80211_scan_entry base;
76	TAILQ_ENTRY(sta_entry) se_list;
77	LIST_ENTRY(sta_entry) se_hash;
78	uint8_t		se_fails;		/* failure to associate count */
79	uint8_t		se_seen;		/* seen during current scan */
80	uint8_t		se_notseen;		/* not seen in previous scans */
81	uint8_t		se_flags;
82#define	STA_DEMOTE11B	0x01			/* match w/ demoted 11b chan */
83	uint32_t	se_avgrssi;		/* LPF rssi state */
84	unsigned long	se_lastupdate;		/* time of last update */
85	unsigned long	se_lastfail;		/* time of last failure */
86	unsigned long	se_lastassoc;		/* time of last association */
87	u_int		se_scangen;		/* iterator scan gen# */
88	u_int		se_countrygen;		/* gen# of last cc notify */
89};
90
91#define	STA_HASHSIZE	32
92/* simple hash is enough for variation of macaddr */
93#define	STA_HASH(addr)	\
94	(((const uint8_t *)(addr))[IEEE80211_ADDR_LEN - 1] % STA_HASHSIZE)
95
96#define	MAX_IEEE_CHAN	256			/* max acceptable IEEE chan # */
97CTASSERT(MAX_IEEE_CHAN >= 256);
98
99struct sta_table {
100	ieee80211_scan_table_lock_t st_lock;	/* on scan table */
101	TAILQ_HEAD(, sta_entry) st_entry;	/* all entries */
102	LIST_HEAD(, sta_entry) st_hash[STA_HASHSIZE];
103	struct mtx	st_scanlock;		/* on st_scaniter */
104	u_int		st_scaniter;		/* gen# for iterator */
105	u_int		st_scangen;		/* scan generation # */
106	int		st_newscan;
107	/* ap-related state */
108	int		st_maxrssi[MAX_IEEE_CHAN];
109};
110
111static void sta_flush_table(struct sta_table *);
112/*
113 * match_bss returns a bitmask describing if an entry is suitable
114 * for use.  If non-zero the entry was deemed not suitable and it's
115 * contents explains why.  The following flags are or'd to to this
116 * mask and can be used to figure out why the entry was rejected.
117 */
118#define	MATCH_CHANNEL		0x00001	/* channel mismatch */
119#define	MATCH_CAPINFO		0x00002	/* capabilities mismatch, e.g. no ess */
120#define	MATCH_PRIVACY		0x00004	/* privacy mismatch */
121#define	MATCH_RATE		0x00008	/* rate set mismatch */
122#define	MATCH_SSID		0x00010	/* ssid mismatch */
123#define	MATCH_BSSID		0x00020	/* bssid mismatch */
124#define	MATCH_FAILS		0x00040	/* too many failed auth attempts */
125#define	MATCH_NOTSEEN		0x00080	/* not seen in recent scans */
126#define	MATCH_RSSI		0x00100	/* rssi deemed too low to use */
127#define	MATCH_CC		0x00200	/* country code mismatch */
128#define	MATCH_TDMA_NOIE		0x00400	/* no TDMA ie */
129#define	MATCH_TDMA_NOTMASTER	0x00800	/* not TDMA master */
130#define	MATCH_TDMA_NOSLOT	0x01000	/* all TDMA slots occupied */
131#define	MATCH_TDMA_LOCAL	0x02000	/* local address */
132#define	MATCH_TDMA_VERSION	0x04000	/* protocol version mismatch */
133#define	MATCH_MESH_NOID		0x10000	/* no MESHID ie */
134#define	MATCH_MESHID		0x20000	/* meshid mismatch */
135static int match_bss(struct ieee80211vap *,
136	const struct ieee80211_scan_state *, struct sta_entry *, int);
137static void adhoc_age(struct ieee80211_scan_state *);
138
139static __inline int
140isocmp(const uint8_t cc1[], const uint8_t cc2[])
141{
142     return (cc1[0] == cc2[0] && cc1[1] == cc2[1]);
143}
144
145/* number of references from net80211 layer */
146static	int nrefs = 0;
147/*
148 * Module glue.
149 */
150IEEE80211_SCANNER_MODULE(sta, 1);
151
152/*
153 * Attach prior to any scanning work.
154 */
155static int
156sta_attach(struct ieee80211_scan_state *ss)
157{
158	struct sta_table *st;
159
160	st = (struct sta_table *) malloc(sizeof(struct sta_table),
161		M_80211_SCAN, M_NOWAIT | M_ZERO);
162	if (st == NULL)
163		return 0;
164	IEEE80211_SCAN_TABLE_LOCK_INIT(st, "scantable");
165	mtx_init(&st->st_scanlock, "scangen", "802.11 scangen", MTX_DEF);
166	TAILQ_INIT(&st->st_entry);
167	ss->ss_priv = st;
168	nrefs++;			/* NB: we assume caller locking */
169	return 1;
170}
171
172/*
173 * Cleanup any private state.
174 */
175static int
176sta_detach(struct ieee80211_scan_state *ss)
177{
178	struct sta_table *st = ss->ss_priv;
179
180	if (st != NULL) {
181		sta_flush_table(st);
182		IEEE80211_SCAN_TABLE_LOCK_DESTROY(st);
183		mtx_destroy(&st->st_scanlock);
184		free(st, M_80211_SCAN);
185		KASSERT(nrefs > 0, ("imbalanced attach/detach"));
186		nrefs--;		/* NB: we assume caller locking */
187	}
188	return 1;
189}
190
191/*
192 * Flush all per-scan state.
193 */
194static int
195sta_flush(struct ieee80211_scan_state *ss)
196{
197	struct sta_table *st = ss->ss_priv;
198
199	IEEE80211_SCAN_TABLE_LOCK(st);
200	sta_flush_table(st);
201	IEEE80211_SCAN_TABLE_UNLOCK(st);
202	ss->ss_last = 0;
203	return 0;
204}
205
206/*
207 * Flush all entries in the scan cache.
208 */
209static void
210sta_flush_table(struct sta_table *st)
211{
212	struct sta_entry *se, *next;
213
214	TAILQ_FOREACH_SAFE(se, &st->st_entry, se_list, next) {
215		TAILQ_REMOVE(&st->st_entry, se, se_list);
216		LIST_REMOVE(se, se_hash);
217		ieee80211_ies_cleanup(&se->base.se_ies);
218		free(se, M_80211_SCAN);
219	}
220	memset(st->st_maxrssi, 0, sizeof(st->st_maxrssi));
221}
222
223/*
224 * Process a beacon or probe response frame; create an
225 * entry in the scan cache or update any previous entry.
226 */
227static int
228sta_add(struct ieee80211_scan_state *ss,
229	const struct ieee80211_scanparams *sp,
230	const struct ieee80211_frame *wh,
231	int subtype, int rssi, int noise)
232{
233#define	ISPROBE(_st)	((_st) == IEEE80211_FC0_SUBTYPE_PROBE_RESP)
234#define	PICK1ST(_ss) \
235	((ss->ss_flags & (IEEE80211_SCAN_PICK1ST | IEEE80211_SCAN_GOTPICK)) == \
236	IEEE80211_SCAN_PICK1ST)
237	struct sta_table *st = ss->ss_priv;
238	const uint8_t *macaddr = wh->i_addr2;
239	struct ieee80211vap *vap = ss->ss_vap;
240	struct ieee80211com *ic = vap->iv_ic;
241	struct sta_entry *se;
242	struct ieee80211_scan_entry *ise;
243	int hash;
244
245	hash = STA_HASH(macaddr);
246
247	IEEE80211_SCAN_TABLE_LOCK(st);
248	LIST_FOREACH(se, &st->st_hash[hash], se_hash)
249		if (IEEE80211_ADDR_EQ(se->base.se_macaddr, macaddr))
250			goto found;
251	se = (struct sta_entry *) malloc(sizeof(struct sta_entry),
252		M_80211_SCAN, M_NOWAIT | M_ZERO);
253	if (se == NULL) {
254		IEEE80211_SCAN_TABLE_UNLOCK(st);
255		return 0;
256	}
257	se->se_scangen = st->st_scaniter-1;
258	se->se_avgrssi = IEEE80211_RSSI_DUMMY_MARKER;
259	IEEE80211_ADDR_COPY(se->base.se_macaddr, macaddr);
260	TAILQ_INSERT_TAIL(&st->st_entry, se, se_list);
261	LIST_INSERT_HEAD(&st->st_hash[hash], se, se_hash);
262found:
263	ise = &se->base;
264	/* XXX ap beaconing multiple ssid w/ same bssid */
265	if (sp->ssid[1] != 0 &&
266	    (ISPROBE(subtype) || ise->se_ssid[1] == 0))
267		memcpy(ise->se_ssid, sp->ssid, 2+sp->ssid[1]);
268	KASSERT(sp->rates[1] <= IEEE80211_RATE_MAXSIZE,
269		("rate set too large: %u", sp->rates[1]));
270	memcpy(ise->se_rates, sp->rates, 2+sp->rates[1]);
271	if (sp->xrates != NULL) {
272		/* XXX validate xrates[1] */
273		KASSERT(sp->xrates[1] <= IEEE80211_RATE_MAXSIZE,
274			("xrate set too large: %u", sp->xrates[1]));
275		memcpy(ise->se_xrates, sp->xrates, 2+sp->xrates[1]);
276	} else
277		ise->se_xrates[1] = 0;
278	IEEE80211_ADDR_COPY(ise->se_bssid, wh->i_addr3);
279	if ((sp->status & IEEE80211_BPARSE_OFFCHAN) == 0) {
280		/*
281		 * Record rssi data using extended precision LPF filter.
282		 *
283		 * NB: use only on-channel data to insure we get a good
284		 *     estimate of the signal we'll see when associated.
285		 */
286		IEEE80211_RSSI_LPF(se->se_avgrssi, rssi);
287		ise->se_rssi = IEEE80211_RSSI_GET(se->se_avgrssi);
288		ise->se_noise = noise;
289	}
290	memcpy(ise->se_tstamp.data, sp->tstamp, sizeof(ise->se_tstamp));
291	ise->se_intval = sp->bintval;
292	ise->se_capinfo = sp->capinfo;
293#ifdef IEEE80211_SUPPORT_MESH
294	if (sp->meshid != NULL && sp->meshid[1] != 0)
295		memcpy(ise->se_meshid, sp->meshid, 2+sp->meshid[1]);
296#endif
297	/*
298	 * Beware of overriding se_chan for frames seen
299	 * off-channel; this can cause us to attempt an
300	 * association on the wrong channel.
301	 */
302	if (sp->status & IEEE80211_BPARSE_OFFCHAN) {
303		struct ieee80211_channel *c;
304		/*
305		 * Off-channel, locate the home/bss channel for the sta
306		 * using the value broadcast in the DSPARMS ie.  We know
307		 * sp->chan has this value because it's used to calculate
308		 * IEEE80211_BPARSE_OFFCHAN.
309		 */
310		c = ieee80211_find_channel_byieee(ic, sp->chan,
311		    ic->ic_curchan->ic_flags);
312		if (c != NULL) {
313			ise->se_chan = c;
314		} else if (ise->se_chan == NULL) {
315			/* should not happen, pick something */
316			ise->se_chan = ic->ic_curchan;
317		}
318	} else
319		ise->se_chan = ic->ic_curchan;
320	ise->se_fhdwell = sp->fhdwell;
321	ise->se_fhindex = sp->fhindex;
322	ise->se_erp = sp->erp;
323	ise->se_timoff = sp->timoff;
324	if (sp->tim != NULL) {
325		const struct ieee80211_tim_ie *tim =
326		    (const struct ieee80211_tim_ie *) sp->tim;
327		ise->se_dtimperiod = tim->tim_period;
328	}
329	if (sp->country != NULL) {
330		const struct ieee80211_country_ie *cie =
331		    (const struct ieee80211_country_ie *) sp->country;
332		/*
333		 * If 11d is enabled and we're attempting to join a bss
334		 * that advertises it's country code then compare our
335		 * current settings to what we fetched from the country ie.
336		 * If our country code is unspecified or different then
337		 * dispatch an event to user space that identifies the
338		 * country code so our regdomain config can be changed.
339		 */
340		/* XXX only for STA mode? */
341		if ((IEEE80211_IS_CHAN_11D(ise->se_chan) ||
342		    (vap->iv_flags_ext & IEEE80211_FEXT_DOTD)) &&
343		    (ic->ic_regdomain.country == CTRY_DEFAULT ||
344		     !isocmp(cie->cc, ic->ic_regdomain.isocc))) {
345			/* only issue one notify event per scan */
346			if (se->se_countrygen != st->st_scangen) {
347				ieee80211_notify_country(vap, ise->se_bssid,
348				    cie->cc);
349				se->se_countrygen = st->st_scangen;
350			}
351		}
352		ise->se_cc[0] = cie->cc[0];
353		ise->se_cc[1] = cie->cc[1];
354	}
355	/* NB: no need to setup ie ptrs; they are not (currently) used */
356	(void) ieee80211_ies_init(&ise->se_ies, sp->ies, sp->ies_len);
357
358	/* clear failure count after STA_FAIL_AGE passes */
359	if (se->se_fails && (ticks - se->se_lastfail) > STA_FAILS_AGE*hz) {
360		se->se_fails = 0;
361		IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_SCAN, macaddr,
362		    "%s: fails %u", __func__, se->se_fails);
363	}
364
365	se->se_lastupdate = ticks;		/* update time */
366	se->se_seen = 1;
367	se->se_notseen = 0;
368
369	KASSERT(sizeof(sp->bchan) == 1, ("bchan size"));
370	if (rssi > st->st_maxrssi[sp->bchan])
371		st->st_maxrssi[sp->bchan] = rssi;
372
373	IEEE80211_SCAN_TABLE_UNLOCK(st);
374
375	/*
376	 * If looking for a quick choice and nothing's
377	 * been found check here.
378	 */
379	if (PICK1ST(ss) && match_bss(vap, ss, se, IEEE80211_MSG_SCAN) == 0)
380		ss->ss_flags |= IEEE80211_SCAN_GOTPICK;
381
382	return 1;
383#undef PICK1ST
384#undef ISPROBE
385}
386
387/*
388 * Check if a channel is excluded by user request.
389 */
390static int
391isexcluded(struct ieee80211vap *vap, const struct ieee80211_channel *c)
392{
393	return (isclr(vap->iv_ic->ic_chan_active, c->ic_ieee) ||
394	    (vap->iv_des_chan != IEEE80211_CHAN_ANYC &&
395	     c->ic_freq != vap->iv_des_chan->ic_freq));
396}
397
398static struct ieee80211_channel *
399find11gchannel(struct ieee80211com *ic, int i, int freq)
400{
401	struct ieee80211_channel *c;
402	int j;
403
404	/*
405	 * The normal ordering in the channel list is b channel
406	 * immediately followed by g so optimize the search for
407	 * this.  We'll still do a full search just in case.
408	 */
409	for (j = i+1; j < ic->ic_nchans; j++) {
410		c = &ic->ic_channels[j];
411		if (c->ic_freq == freq && IEEE80211_IS_CHAN_G(c))
412			return c;
413	}
414	for (j = 0; j < i; j++) {
415		c = &ic->ic_channels[j];
416		if (c->ic_freq == freq && IEEE80211_IS_CHAN_G(c))
417			return c;
418	}
419	return NULL;
420}
421
422static const u_int chanflags[IEEE80211_MODE_MAX] = {
423	[IEEE80211_MODE_AUTO]	  = IEEE80211_CHAN_B,
424	[IEEE80211_MODE_11A]	  = IEEE80211_CHAN_A,
425	[IEEE80211_MODE_11B]	  = IEEE80211_CHAN_B,
426	[IEEE80211_MODE_11G]	  = IEEE80211_CHAN_G,
427	[IEEE80211_MODE_FH]	  = IEEE80211_CHAN_FHSS,
428	/* check base channel */
429	[IEEE80211_MODE_TURBO_A]  = IEEE80211_CHAN_A,
430	[IEEE80211_MODE_TURBO_G]  = IEEE80211_CHAN_G,
431	[IEEE80211_MODE_STURBO_A] = IEEE80211_CHAN_ST,
432	[IEEE80211_MODE_HALF]	  = IEEE80211_CHAN_HALF,
433	[IEEE80211_MODE_QUARTER]  = IEEE80211_CHAN_QUARTER,
434	/* check legacy */
435	[IEEE80211_MODE_11NA]	  = IEEE80211_CHAN_A,
436	[IEEE80211_MODE_11NG]	  = IEEE80211_CHAN_G,
437};
438
439static void
440add_channels(struct ieee80211vap *vap,
441	struct ieee80211_scan_state *ss,
442	enum ieee80211_phymode mode, const uint16_t freq[], int nfreq)
443{
444#define	N(a)	(sizeof(a) / sizeof(a[0]))
445	struct ieee80211com *ic = vap->iv_ic;
446	struct ieee80211_channel *c, *cg;
447	u_int modeflags;
448	int i;
449
450	KASSERT(mode < N(chanflags), ("Unexpected mode %u", mode));
451	modeflags = chanflags[mode];
452	for (i = 0; i < nfreq; i++) {
453		if (ss->ss_last >= IEEE80211_SCAN_MAX)
454			break;
455
456		c = ieee80211_find_channel(ic, freq[i], modeflags);
457		if (c == NULL || isexcluded(vap, c))
458			continue;
459		if (mode == IEEE80211_MODE_AUTO) {
460			/*
461			 * XXX special-case 11b/g channels so we select
462			 *     the g channel if both are present.
463			 */
464			if (IEEE80211_IS_CHAN_B(c) &&
465			    (cg = find11gchannel(ic, i, c->ic_freq)) != NULL)
466				c = cg;
467		}
468		ss->ss_chans[ss->ss_last++] = c;
469	}
470#undef N
471}
472
473struct scanlist {
474	uint16_t	mode;
475	uint16_t	count;
476	const uint16_t	*list;
477};
478
479static int
480checktable(const struct scanlist *scan, const struct ieee80211_channel *c)
481{
482	int i;
483
484	for (; scan->list != NULL; scan++) {
485		for (i = 0; i < scan->count; i++)
486			if (scan->list[i] == c->ic_freq)
487				return 1;
488	}
489	return 0;
490}
491
492static int
493onscanlist(const struct ieee80211_scan_state *ss,
494	const struct ieee80211_channel *c)
495{
496	int i;
497
498	for (i = 0; i < ss->ss_last; i++)
499		if (ss->ss_chans[i] == c)
500			return 1;
501	return 0;
502}
503
504static void
505sweepchannels(struct ieee80211_scan_state *ss, struct ieee80211vap *vap,
506	const struct scanlist table[])
507{
508	struct ieee80211com *ic = vap->iv_ic;
509	struct ieee80211_channel *c;
510	int i;
511
512	for (i = 0; i < ic->ic_nchans; i++) {
513		if (ss->ss_last >= IEEE80211_SCAN_MAX)
514			break;
515
516		c = &ic->ic_channels[i];
517		/*
518		 * Ignore dynamic turbo channels; we scan them
519		 * in normal mode (i.e. not boosted).  Likewise
520		 * for HT channels, they get scanned using
521		 * legacy rates.
522		 */
523		if (IEEE80211_IS_CHAN_DTURBO(c) || IEEE80211_IS_CHAN_HT(c))
524			continue;
525
526		/*
527		 * If a desired mode was specified, scan only
528		 * channels that satisfy that constraint.
529		 */
530		if (vap->iv_des_mode != IEEE80211_MODE_AUTO &&
531		    vap->iv_des_mode != ieee80211_chan2mode(c))
532			continue;
533
534		/*
535		 * Skip channels excluded by user request.
536		 */
537		if (isexcluded(vap, c))
538			continue;
539
540		/*
541		 * Add the channel unless it is listed in the
542		 * fixed scan order tables.  This insures we
543		 * don't sweep back in channels we filtered out
544		 * above.
545		 */
546		if (checktable(table, c))
547			continue;
548
549		/* Add channel to scanning list. */
550		ss->ss_chans[ss->ss_last++] = c;
551	}
552	/*
553	 * Explicitly add any desired channel if:
554	 * - not already on the scan list
555	 * - allowed by any desired mode constraint
556	 * - there is space in the scan list
557	 * This allows the channel to be used when the filtering
558	 * mechanisms would otherwise elide it (e.g HT, turbo).
559	 */
560	c = vap->iv_des_chan;
561	if (c != IEEE80211_CHAN_ANYC &&
562	    !onscanlist(ss, c) &&
563	    (vap->iv_des_mode == IEEE80211_MODE_AUTO ||
564	     vap->iv_des_mode == ieee80211_chan2mode(c)) &&
565	    ss->ss_last < IEEE80211_SCAN_MAX)
566		ss->ss_chans[ss->ss_last++] = c;
567}
568
569static void
570makescanlist(struct ieee80211_scan_state *ss, struct ieee80211vap *vap,
571	const struct scanlist table[])
572{
573	const struct scanlist *scan;
574	enum ieee80211_phymode mode;
575
576	ss->ss_last = 0;
577	/*
578	 * Use the table of ordered channels to construct the list
579	 * of channels for scanning.  Any channels in the ordered
580	 * list not in the master list will be discarded.
581	 */
582	for (scan = table; scan->list != NULL; scan++) {
583		mode = scan->mode;
584		if (vap->iv_des_mode != IEEE80211_MODE_AUTO) {
585			/*
586			 * If a desired mode was specified, scan only
587			 * channels that satisfy that constraint.
588			 */
589			if (vap->iv_des_mode != mode) {
590				/*
591				 * The scan table marks 2.4Ghz channels as b
592				 * so if the desired mode is 11g, then use
593				 * the 11b channel list but upgrade the mode.
594				 */
595				if (vap->iv_des_mode != IEEE80211_MODE_11G ||
596				    mode != IEEE80211_MODE_11B)
597					continue;
598				mode = IEEE80211_MODE_11G;	/* upgrade */
599			}
600		} else {
601			/*
602			 * This lets add_channels upgrade an 11b channel
603			 * to 11g if available.
604			 */
605			if (mode == IEEE80211_MODE_11B)
606				mode = IEEE80211_MODE_AUTO;
607		}
608#ifdef IEEE80211_F_XR
609		/* XR does not operate on turbo channels */
610		if ((vap->iv_flags & IEEE80211_F_XR) &&
611		    (mode == IEEE80211_MODE_TURBO_A ||
612		     mode == IEEE80211_MODE_TURBO_G ||
613		     mode == IEEE80211_MODE_STURBO_A))
614			continue;
615#endif
616		/*
617		 * Add the list of the channels; any that are not
618		 * in the master channel list will be discarded.
619		 */
620		add_channels(vap, ss, mode, scan->list, scan->count);
621	}
622
623	/*
624	 * Add the channels from the ic that are not present
625	 * in the table.
626	 */
627	sweepchannels(ss, vap, table);
628}
629
630static const uint16_t rcl1[] =		/* 8 FCC channel: 52, 56, 60, 64, 36, 40, 44, 48 */
631{ 5260, 5280, 5300, 5320, 5180, 5200, 5220, 5240 };
632static const uint16_t rcl2[] =		/* 4 MKK channels: 34, 38, 42, 46 */
633{ 5170, 5190, 5210, 5230 };
634static const uint16_t rcl3[] =		/* 2.4Ghz ch: 1,6,11,7,13 */
635{ 2412, 2437, 2462, 2442, 2472 };
636static const uint16_t rcl4[] =		/* 5 FCC channel: 149, 153, 161, 165 */
637{ 5745, 5765, 5785, 5805, 5825 };
638static const uint16_t rcl7[] =		/* 11 ETSI channel: 100,104,108,112,116,120,124,128,132,136,140 */
639{ 5500, 5520, 5540, 5560, 5580, 5600, 5620, 5640, 5660, 5680, 5700 };
640static const uint16_t rcl8[] =		/* 2.4Ghz ch: 2,3,4,5,8,9,10,12 */
641{ 2417, 2422, 2427, 2432, 2447, 2452, 2457, 2467 };
642static const uint16_t rcl9[] =		/* 2.4Ghz ch: 14 */
643{ 2484 };
644static const uint16_t rcl10[] =	/* Added Korean channels 2312-2372 */
645{ 2312, 2317, 2322, 2327, 2332, 2337, 2342, 2347, 2352, 2357, 2362, 2367, 2372 };
646static const uint16_t rcl11[] =	/* Added Japan channels in 4.9/5.0 spectrum */
647{ 5040, 5060, 5080, 4920, 4940, 4960, 4980 };
648#ifdef ATH_TURBO_SCAN
649static const uint16_t rcl5[] =		/* 3 static turbo channels */
650{ 5210, 5250, 5290 };
651static const uint16_t rcl6[] =		/* 2 static turbo channels */
652{ 5760, 5800 };
653static const uint16_t rcl6x[] =	/* 4 FCC3 turbo channels */
654{ 5540, 5580, 5620, 5660 };
655static const uint16_t rcl12[] =	/* 2.4Ghz Turbo channel 6 */
656{ 2437 };
657static const uint16_t rcl13[] =	/* dynamic Turbo channels */
658{ 5200, 5240, 5280, 5765, 5805 };
659#endif /* ATH_TURBO_SCAN */
660
661#define	X(a)	.count = sizeof(a)/sizeof(a[0]), .list = a
662
663static const struct scanlist staScanTable[] = {
664	{ IEEE80211_MODE_11B,   	X(rcl3) },
665	{ IEEE80211_MODE_11A,   	X(rcl1) },
666	{ IEEE80211_MODE_11A,   	X(rcl2) },
667	{ IEEE80211_MODE_11B,   	X(rcl8) },
668	{ IEEE80211_MODE_11B,   	X(rcl9) },
669	{ IEEE80211_MODE_11A,   	X(rcl4) },
670#ifdef ATH_TURBO_SCAN
671	{ IEEE80211_MODE_STURBO_A,	X(rcl5) },
672	{ IEEE80211_MODE_STURBO_A,	X(rcl6) },
673	{ IEEE80211_MODE_TURBO_A,	X(rcl6x) },
674	{ IEEE80211_MODE_TURBO_A,	X(rcl13) },
675#endif /* ATH_TURBO_SCAN */
676	{ IEEE80211_MODE_11A,		X(rcl7) },
677	{ IEEE80211_MODE_11B,		X(rcl10) },
678	{ IEEE80211_MODE_11A,		X(rcl11) },
679#ifdef ATH_TURBO_SCAN
680	{ IEEE80211_MODE_TURBO_G,	X(rcl12) },
681#endif /* ATH_TURBO_SCAN */
682	{ .list = NULL }
683};
684
685/*
686 * Start a station-mode scan by populating the channel list.
687 */
688static int
689sta_start(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
690{
691	struct sta_table *st = ss->ss_priv;
692
693	makescanlist(ss, vap, staScanTable);
694
695	if (ss->ss_mindwell == 0)
696		ss->ss_mindwell = msecs_to_ticks(20);	/* 20ms */
697	if (ss->ss_maxdwell == 0)
698		ss->ss_maxdwell = msecs_to_ticks(200);	/* 200ms */
699
700	st->st_scangen++;
701	st->st_newscan = 1;
702
703	return 0;
704}
705
706/*
707 * Restart a scan, typically a bg scan but can
708 * also be a fg scan that came up empty.
709 */
710static int
711sta_restart(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
712{
713	struct sta_table *st = ss->ss_priv;
714
715	st->st_newscan = 1;
716	return 0;
717}
718
719/*
720 * Cancel an ongoing scan.
721 */
722static int
723sta_cancel(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
724{
725	return 0;
726}
727
728/* unalligned little endian access */
729#define LE_READ_2(p)					\
730	((uint16_t)					\
731	 ((((const uint8_t *)(p))[0]      ) |		\
732	  (((const uint8_t *)(p))[1] <<  8)))
733
734/*
735 * Demote any supplied 11g channel to 11b.  There should
736 * always be an 11b channel but we check anyway...
737 */
738static struct ieee80211_channel *
739demote11b(struct ieee80211vap *vap, struct ieee80211_channel *chan)
740{
741	struct ieee80211_channel *c;
742
743	if (IEEE80211_IS_CHAN_ANYG(chan) &&
744	    vap->iv_des_mode == IEEE80211_MODE_AUTO) {
745		c = ieee80211_find_channel(vap->iv_ic, chan->ic_freq,
746		    (chan->ic_flags &~ (IEEE80211_CHAN_PUREG | IEEE80211_CHAN_G)) |
747		    IEEE80211_CHAN_B);
748		if (c != NULL)
749			chan = c;
750	}
751	return chan;
752}
753
754static int
755maxrate(const struct ieee80211_scan_entry *se)
756{
757	const struct ieee80211_ie_htcap *htcap =
758	    (const struct ieee80211_ie_htcap *) se->se_ies.htcap_ie;
759	int rmax, r, i, txstream;
760	uint16_t caps;
761	uint8_t txparams;
762
763	rmax = 0;
764	if (htcap != NULL) {
765		/*
766		 * HT station; inspect supported MCS and then adjust
767		 * rate by channel width.
768		 */
769		txparams = htcap->hc_mcsset[12];
770		if (txparams & 0x3) {
771			/*
772			 * TX MCS parameters defined and not equal to RX,
773			 * extract the number of spartial streams and
774			 * map it to the highest MCS rate.
775			 */
776			txstream = ((txparams & 0xc) >> 2) + 1;
777			i = txstream * 8 - 1;
778		} else
779			for (i = 31; i >= 0 && isclr(htcap->hc_mcsset, i); i--);
780		if (i >= 0) {
781			caps = LE_READ_2(&htcap->hc_cap);
782			if ((caps & IEEE80211_HTCAP_CHWIDTH40) &&
783			    (caps & IEEE80211_HTCAP_SHORTGI40))
784				rmax = ieee80211_htrates[i].ht40_rate_400ns;
785			else if (caps & IEEE80211_HTCAP_CHWIDTH40)
786				rmax = ieee80211_htrates[i].ht40_rate_800ns;
787			else if (caps & IEEE80211_HTCAP_SHORTGI20)
788				rmax = ieee80211_htrates[i].ht20_rate_400ns;
789			else
790				rmax = ieee80211_htrates[i].ht20_rate_800ns;
791		}
792	}
793	for (i = 0; i < se->se_rates[1]; i++) {
794		r = se->se_rates[2+i] & IEEE80211_RATE_VAL;
795		if (r > rmax)
796			rmax = r;
797	}
798	for (i = 0; i < se->se_xrates[1]; i++) {
799		r = se->se_xrates[2+i] & IEEE80211_RATE_VAL;
800		if (r > rmax)
801			rmax = r;
802	}
803	return rmax;
804}
805
806/*
807 * Compare the capabilities of two entries and decide which is
808 * more desirable (return >0 if a is considered better).  Note
809 * that we assume compatibility/usability has already been checked
810 * so we don't need to (e.g. validate whether privacy is supported).
811 * Used to select the best scan candidate for association in a BSS.
812 */
813static int
814sta_compare(const struct sta_entry *a, const struct sta_entry *b)
815{
816#define	PREFER(_a,_b,_what) do {			\
817	if (((_a) ^ (_b)) & (_what))			\
818		return ((_a) & (_what)) ? 1 : -1;	\
819} while (0)
820	int maxa, maxb;
821	int8_t rssia, rssib;
822	int weight;
823
824	/* privacy support */
825	PREFER(a->base.se_capinfo, b->base.se_capinfo,
826		IEEE80211_CAPINFO_PRIVACY);
827
828	/* compare count of previous failures */
829	weight = b->se_fails - a->se_fails;
830	if (abs(weight) > 1)
831		return weight;
832
833	/*
834	 * Compare rssi.  If the two are considered equivalent
835	 * then fallback to other criteria.  We threshold the
836	 * comparisons to avoid selecting an ap purely by rssi
837	 * when both values may be good but one ap is otherwise
838	 * more desirable (e.g. an 11b-only ap with stronger
839	 * signal than an 11g ap).
840	 */
841	rssia = MIN(a->base.se_rssi, STA_RSSI_MAX);
842	rssib = MIN(b->base.se_rssi, STA_RSSI_MAX);
843	if (abs(rssib - rssia) < 5) {
844		/* best/max rate preferred if signal level close enough XXX */
845		maxa = maxrate(&a->base);
846		maxb = maxrate(&b->base);
847		if (maxa != maxb)
848			return maxa - maxb;
849		/* XXX use freq for channel preference */
850		/* for now just prefer 5Ghz band to all other bands */
851		PREFER(IEEE80211_IS_CHAN_5GHZ(a->base.se_chan),
852		       IEEE80211_IS_CHAN_5GHZ(b->base.se_chan), 1);
853	}
854	/* all things being equal, use signal level */
855	return a->base.se_rssi - b->base.se_rssi;
856#undef PREFER
857}
858
859/*
860 * Check rate set suitability and return the best supported rate.
861 * XXX inspect MCS for HT
862 */
863static int
864check_rate(struct ieee80211vap *vap, const struct ieee80211_channel *chan,
865    const struct ieee80211_scan_entry *se)
866{
867#define	RV(v)	((v) & IEEE80211_RATE_VAL)
868	const struct ieee80211_rateset *srs;
869	int i, j, nrs, r, okrate, badrate, fixedrate, ucastrate;
870	const uint8_t *rs;
871
872	okrate = badrate = 0;
873
874	srs = ieee80211_get_suprates(vap->iv_ic, chan);
875	nrs = se->se_rates[1];
876	rs = se->se_rates+2;
877	/* XXX MCS */
878	ucastrate = vap->iv_txparms[ieee80211_chan2mode(chan)].ucastrate;
879	fixedrate = IEEE80211_FIXED_RATE_NONE;
880again:
881	for (i = 0; i < nrs; i++) {
882		r = RV(rs[i]);
883		badrate = r;
884		/*
885		 * Check any fixed rate is included.
886		 */
887		if (r == ucastrate)
888			fixedrate = r;
889		/*
890		 * Check against our supported rates.
891		 */
892		for (j = 0; j < srs->rs_nrates; j++)
893			if (r == RV(srs->rs_rates[j])) {
894				if (r > okrate)		/* NB: track max */
895					okrate = r;
896				break;
897			}
898
899		if (j == srs->rs_nrates && (rs[i] & IEEE80211_RATE_BASIC)) {
900			/*
901			 * Don't try joining a BSS, if we don't support
902			 * one of its basic rates.
903			 */
904			okrate = 0;
905			goto back;
906		}
907	}
908	if (rs == se->se_rates+2) {
909		/* scan xrates too; sort of an algol68-style for loop */
910		nrs = se->se_xrates[1];
911		rs = se->se_xrates+2;
912		goto again;
913	}
914
915back:
916	if (okrate == 0 || ucastrate != fixedrate)
917		return badrate | IEEE80211_RATE_BASIC;
918	else
919		return RV(okrate);
920#undef RV
921}
922
923static __inline int
924match_id(const uint8_t *ie, const uint8_t *val, int len)
925{
926	return (ie[1] == len && memcmp(ie+2, val, len) == 0);
927}
928
929static int
930match_ssid(const uint8_t *ie,
931	int nssid, const struct ieee80211_scan_ssid ssids[])
932{
933	int i;
934
935	for (i = 0; i < nssid; i++) {
936		if (match_id(ie, ssids[i].ssid, ssids[i].len))
937			return 1;
938	}
939	return 0;
940}
941
942#ifdef IEEE80211_SUPPORT_TDMA
943static int
944tdma_isfull(const struct ieee80211_tdma_param *tdma)
945{
946	int slot, slotcnt;
947
948	slotcnt = tdma->tdma_slotcnt;
949	for (slot = slotcnt-1; slot >= 0; slot--)
950		if (isclr(tdma->tdma_inuse, slot))
951			return 0;
952	return 1;
953}
954#endif /* IEEE80211_SUPPORT_TDMA */
955
956/*
957 * Test a scan candidate for suitability/compatibility.
958 */
959static int
960match_bss(struct ieee80211vap *vap,
961	const struct ieee80211_scan_state *ss, struct sta_entry *se0,
962	int debug)
963{
964	struct ieee80211com *ic = vap->iv_ic;
965	struct ieee80211_scan_entry *se = &se0->base;
966        uint8_t rate;
967        int fail;
968
969	fail = 0;
970	if (isclr(ic->ic_chan_active, ieee80211_chan2ieee(ic, se->se_chan)))
971		fail |= MATCH_CHANNEL;
972	/*
973	 * NB: normally the desired mode is used to construct
974	 * the channel list, but it's possible for the scan
975	 * cache to include entries for stations outside this
976	 * list so we check the desired mode here to weed them
977	 * out.
978	 */
979	if (vap->iv_des_mode != IEEE80211_MODE_AUTO &&
980	    (se->se_chan->ic_flags & IEEE80211_CHAN_ALLTURBO) !=
981	    chanflags[vap->iv_des_mode])
982		fail |= MATCH_CHANNEL;
983	if (vap->iv_opmode == IEEE80211_M_IBSS) {
984		if ((se->se_capinfo & IEEE80211_CAPINFO_IBSS) == 0)
985			fail |= MATCH_CAPINFO;
986#ifdef IEEE80211_SUPPORT_TDMA
987	} else if (vap->iv_opmode == IEEE80211_M_AHDEMO) {
988		/*
989		 * Adhoc demo network setup shouldn't really be scanning
990		 * but just in case skip stations operating in IBSS or
991		 * BSS mode.
992		 */
993		if (se->se_capinfo & (IEEE80211_CAPINFO_IBSS|IEEE80211_CAPINFO_ESS))
994			fail |= MATCH_CAPINFO;
995		/*
996		 * TDMA operation cannot coexist with a normal 802.11 network;
997		 * skip if IBSS or ESS capabilities are marked and require
998		 * the beacon have a TDMA ie present.
999		 */
1000		if (vap->iv_caps & IEEE80211_C_TDMA) {
1001			const struct ieee80211_tdma_param *tdma =
1002			    (const struct ieee80211_tdma_param *)se->se_ies.tdma_ie;
1003			const struct ieee80211_tdma_state *ts = vap->iv_tdma;
1004
1005			if (tdma == NULL)
1006				fail |= MATCH_TDMA_NOIE;
1007			else if (tdma->tdma_version != ts->tdma_version)
1008				fail |= MATCH_TDMA_VERSION;
1009			else if (tdma->tdma_slot != 0)
1010				fail |= MATCH_TDMA_NOTMASTER;
1011			else if (tdma_isfull(tdma))
1012				fail |= MATCH_TDMA_NOSLOT;
1013#if 0
1014			else if (ieee80211_local_address(se->se_macaddr))
1015				fail |= MATCH_TDMA_LOCAL;
1016#endif
1017		}
1018#endif /* IEEE80211_SUPPORT_TDMA */
1019#ifdef IEEE80211_SUPPORT_MESH
1020	} else if (vap->iv_opmode == IEEE80211_M_MBSS) {
1021		const struct ieee80211_mesh_state *ms = vap->iv_mesh;
1022		/*
1023		 * Mesh nodes have IBSS & ESS bits in capinfo turned off
1024		 * and two special ie's that must be present.
1025		 */
1026		if (se->se_capinfo & (IEEE80211_CAPINFO_IBSS|IEEE80211_CAPINFO_ESS))
1027			fail |= MATCH_CAPINFO;
1028		else if (se->se_meshid[0] != IEEE80211_ELEMID_MESHID)
1029			fail |= MATCH_MESH_NOID;
1030		else if (ms->ms_idlen != 0 &&
1031		    match_id(se->se_meshid, ms->ms_id, ms->ms_idlen))
1032			fail |= MATCH_MESHID;
1033#endif
1034	} else {
1035		if ((se->se_capinfo & IEEE80211_CAPINFO_ESS) == 0)
1036			fail |= MATCH_CAPINFO;
1037		/*
1038		 * If 11d is enabled and we're attempting to join a bss
1039		 * that advertises it's country code then compare our
1040		 * current settings to what we fetched from the country ie.
1041		 * If our country code is unspecified or different then do
1042		 * not attempt to join the bss.  We should have already
1043		 * dispatched an event to user space that identifies the
1044		 * new country code so our regdomain config should match.
1045		 */
1046		if ((IEEE80211_IS_CHAN_11D(se->se_chan) ||
1047		    (vap->iv_flags_ext & IEEE80211_FEXT_DOTD)) &&
1048		    se->se_cc[0] != 0 &&
1049		    (ic->ic_regdomain.country == CTRY_DEFAULT ||
1050		     !isocmp(se->se_cc, ic->ic_regdomain.isocc)))
1051			fail |= MATCH_CC;
1052	}
1053	if (vap->iv_flags & IEEE80211_F_PRIVACY) {
1054		if ((se->se_capinfo & IEEE80211_CAPINFO_PRIVACY) == 0)
1055			fail |= MATCH_PRIVACY;
1056	} else {
1057		/* XXX does this mean privacy is supported or required? */
1058		if (se->se_capinfo & IEEE80211_CAPINFO_PRIVACY)
1059			fail |= MATCH_PRIVACY;
1060	}
1061	se0->se_flags &= ~STA_DEMOTE11B;
1062	rate = check_rate(vap, se->se_chan, se);
1063	if (rate & IEEE80211_RATE_BASIC) {
1064		fail |= MATCH_RATE;
1065		/*
1066		 * An 11b-only ap will give a rate mismatch if there is an
1067		 * OFDM fixed tx rate for 11g.  Try downgrading the channel
1068		 * in the scan list to 11b and retry the rate check.
1069		 */
1070		if (IEEE80211_IS_CHAN_ANYG(se->se_chan)) {
1071			rate = check_rate(vap, demote11b(vap, se->se_chan), se);
1072			if ((rate & IEEE80211_RATE_BASIC) == 0) {
1073				fail &= ~MATCH_RATE;
1074				se0->se_flags |= STA_DEMOTE11B;
1075			}
1076		}
1077	} else if (rate < 2*24) {
1078		/*
1079		 * This is an 11b-only ap.  Check the desired mode in
1080		 * case that needs to be honored (mode 11g filters out
1081		 * 11b-only ap's).  Otherwise force any 11g channel used
1082		 * in scanning to be demoted.
1083		 *
1084		 * NB: we cheat a bit here by looking at the max rate;
1085		 *     we could/should check the rates.
1086		 */
1087		if (!(vap->iv_des_mode == IEEE80211_MODE_AUTO ||
1088		      vap->iv_des_mode == IEEE80211_MODE_11B))
1089			fail |= MATCH_RATE;
1090		else
1091			se0->se_flags |= STA_DEMOTE11B;
1092	}
1093	if (ss->ss_nssid != 0 &&
1094	    !match_ssid(se->se_ssid, ss->ss_nssid, ss->ss_ssid))
1095		fail |= MATCH_SSID;
1096	if ((vap->iv_flags & IEEE80211_F_DESBSSID) &&
1097	    !IEEE80211_ADDR_EQ(vap->iv_des_bssid, se->se_bssid))
1098		fail |= MATCH_BSSID;
1099	if (se0->se_fails >= STA_FAILS_MAX)
1100		fail |= MATCH_FAILS;
1101	if (se0->se_notseen >= STA_PURGE_SCANS)
1102		fail |= MATCH_NOTSEEN;
1103	if (se->se_rssi < STA_RSSI_MIN)
1104		fail |= MATCH_RSSI;
1105#ifdef IEEE80211_DEBUG
1106	if (ieee80211_msg(vap, debug)) {
1107		printf(" %c %s",
1108		    fail & MATCH_FAILS ? '=' :
1109		    fail & MATCH_NOTSEEN ? '^' :
1110		    fail & MATCH_CC ? '$' :
1111#ifdef IEEE80211_SUPPORT_TDMA
1112		    fail & MATCH_TDMA_NOIE ? '&' :
1113		    fail & MATCH_TDMA_VERSION ? 'v' :
1114		    fail & MATCH_TDMA_NOTMASTER ? 's' :
1115		    fail & MATCH_TDMA_NOSLOT ? 'f' :
1116		    fail & MATCH_TDMA_LOCAL ? 'l' :
1117#endif
1118		    fail & MATCH_MESH_NOID ? 'm' :
1119		    fail ? '-' : '+', ether_sprintf(se->se_macaddr));
1120		printf(" %s%c", ether_sprintf(se->se_bssid),
1121		    fail & MATCH_BSSID ? '!' : ' ');
1122		printf(" %3d%c", ieee80211_chan2ieee(ic, se->se_chan),
1123			fail & MATCH_CHANNEL ? '!' : ' ');
1124		printf(" %+4d%c", se->se_rssi, fail & MATCH_RSSI ? '!' : ' ');
1125		printf(" %2dM%c", (rate & IEEE80211_RATE_VAL) / 2,
1126		    fail & MATCH_RATE ? '!' : ' ');
1127		printf(" %4s%c",
1128		    (se->se_capinfo & IEEE80211_CAPINFO_ESS) ? "ess" :
1129		    (se->se_capinfo & IEEE80211_CAPINFO_IBSS) ? "ibss" : "",
1130		    fail & MATCH_CAPINFO ? '!' : ' ');
1131		printf(" %3s%c ",
1132		    (se->se_capinfo & IEEE80211_CAPINFO_PRIVACY) ?
1133		    "wep" : "no",
1134		    fail & MATCH_PRIVACY ? '!' : ' ');
1135		ieee80211_print_essid(se->se_ssid+2, se->se_ssid[1]);
1136		printf("%s\n", fail & (MATCH_SSID | MATCH_MESHID) ? "!" : "");
1137	}
1138#endif
1139	return fail;
1140}
1141
1142static void
1143sta_update_notseen(struct sta_table *st)
1144{
1145	struct sta_entry *se;
1146
1147	IEEE80211_SCAN_TABLE_LOCK(st);
1148	TAILQ_FOREACH(se, &st->st_entry, se_list) {
1149		/*
1150		 * If seen the reset and don't bump the count;
1151		 * otherwise bump the ``not seen'' count.  Note
1152		 * that this insures that stations for which we
1153		 * see frames while not scanning but not during
1154		 * this scan will not be penalized.
1155		 */
1156		if (se->se_seen)
1157			se->se_seen = 0;
1158		else
1159			se->se_notseen++;
1160	}
1161	IEEE80211_SCAN_TABLE_UNLOCK(st);
1162}
1163
1164static void
1165sta_dec_fails(struct sta_table *st)
1166{
1167	struct sta_entry *se;
1168
1169	IEEE80211_SCAN_TABLE_LOCK(st);
1170	TAILQ_FOREACH(se, &st->st_entry, se_list)
1171		if (se->se_fails)
1172			se->se_fails--;
1173	IEEE80211_SCAN_TABLE_UNLOCK(st);
1174}
1175
1176static struct sta_entry *
1177select_bss(struct ieee80211_scan_state *ss, struct ieee80211vap *vap, int debug)
1178{
1179	struct sta_table *st = ss->ss_priv;
1180	struct sta_entry *se, *selbs = NULL;
1181
1182	IEEE80211_DPRINTF(vap, debug, " %s\n",
1183	    "macaddr          bssid         chan  rssi  rate flag  wep  essid");
1184	IEEE80211_SCAN_TABLE_LOCK(st);
1185	TAILQ_FOREACH(se, &st->st_entry, se_list) {
1186		ieee80211_ies_expand(&se->base.se_ies);
1187		if (match_bss(vap, ss, se, debug) == 0) {
1188			if (selbs == NULL)
1189				selbs = se;
1190			else if (sta_compare(se, selbs) > 0)
1191				selbs = se;
1192		}
1193	}
1194	IEEE80211_SCAN_TABLE_UNLOCK(st);
1195
1196	return selbs;
1197}
1198
1199/*
1200 * Pick an ap or ibss network to join or find a channel
1201 * to use to start an ibss network.
1202 */
1203static int
1204sta_pick_bss(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
1205{
1206	struct sta_table *st = ss->ss_priv;
1207	struct sta_entry *selbs;
1208	struct ieee80211_channel *chan;
1209
1210	KASSERT(vap->iv_opmode == IEEE80211_M_STA,
1211		("wrong mode %u", vap->iv_opmode));
1212
1213	if (st->st_newscan) {
1214		sta_update_notseen(st);
1215		st->st_newscan = 0;
1216	}
1217	if (ss->ss_flags & IEEE80211_SCAN_NOPICK) {
1218		/*
1219		 * Manual/background scan, don't select+join the
1220		 * bss, just return.  The scanning framework will
1221		 * handle notification that this has completed.
1222		 */
1223		ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
1224		return 1;
1225	}
1226	/*
1227	 * Automatic sequencing; look for a candidate and
1228	 * if found join the network.
1229	 */
1230	/* NB: unlocked read should be ok */
1231	if (TAILQ_FIRST(&st->st_entry) == NULL) {
1232		IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
1233			"%s: no scan candidate\n", __func__);
1234		if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
1235			return 0;
1236notfound:
1237		/*
1238		 * If nothing suitable was found decrement
1239		 * the failure counts so entries will be
1240		 * reconsidered the next time around.  We
1241		 * really want to do this only for sta's
1242		 * where we've previously had some success.
1243		 */
1244		sta_dec_fails(st);
1245		st->st_newscan = 1;
1246		return 0;			/* restart scan */
1247	}
1248	selbs = select_bss(ss, vap, IEEE80211_MSG_SCAN);
1249	if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
1250		return (selbs != NULL);
1251	if (selbs == NULL)
1252		goto notfound;
1253	chan = selbs->base.se_chan;
1254	if (selbs->se_flags & STA_DEMOTE11B)
1255		chan = demote11b(vap, chan);
1256	if (!ieee80211_sta_join(vap, chan, &selbs->base))
1257		goto notfound;
1258	return 1;				/* terminate scan */
1259}
1260
1261/*
1262 * Lookup an entry in the scan cache.  We assume we're
1263 * called from the bottom half or such that we don't need
1264 * to block the bottom half so that it's safe to return
1265 * a reference to an entry w/o holding the lock on the table.
1266 */
1267static struct sta_entry *
1268sta_lookup(struct sta_table *st, const uint8_t macaddr[IEEE80211_ADDR_LEN])
1269{
1270	struct sta_entry *se;
1271	int hash = STA_HASH(macaddr);
1272
1273	IEEE80211_SCAN_TABLE_LOCK(st);
1274	LIST_FOREACH(se, &st->st_hash[hash], se_hash)
1275		if (IEEE80211_ADDR_EQ(se->base.se_macaddr, macaddr))
1276			break;
1277	IEEE80211_SCAN_TABLE_UNLOCK(st);
1278
1279	return se;		/* NB: unlocked */
1280}
1281
1282static void
1283sta_roam_check(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
1284{
1285	struct ieee80211com *ic = vap->iv_ic;
1286	struct ieee80211_node *ni = vap->iv_bss;
1287	struct sta_table *st = ss->ss_priv;
1288	enum ieee80211_phymode mode;
1289	struct sta_entry *se, *selbs;
1290	uint8_t roamRate, curRate, ucastRate;
1291	int8_t roamRssi, curRssi;
1292
1293	se = sta_lookup(st, ni->ni_macaddr);
1294	if (se == NULL) {
1295		/* XXX something is wrong */
1296		return;
1297	}
1298
1299	mode = ieee80211_chan2mode(ic->ic_bsschan);
1300	roamRate = vap->iv_roamparms[mode].rate;
1301	roamRssi = vap->iv_roamparms[mode].rssi;
1302	ucastRate = vap->iv_txparms[mode].ucastrate;
1303	/* NB: the most up to date rssi is in the node, not the scan cache */
1304	curRssi = ic->ic_node_getrssi(ni);
1305	if (ucastRate == IEEE80211_FIXED_RATE_NONE) {
1306		curRate = ni->ni_txrate;
1307		roamRate &= IEEE80211_RATE_VAL;
1308		IEEE80211_DPRINTF(vap, IEEE80211_MSG_ROAM,
1309		    "%s: currssi %d currate %u roamrssi %d roamrate %u\n",
1310		    __func__, curRssi, curRate, roamRssi, roamRate);
1311	} else {
1312		curRate = roamRate;	/* NB: insure compare below fails */
1313		IEEE80211_DPRINTF(vap, IEEE80211_MSG_ROAM,
1314		    "%s: currssi %d roamrssi %d\n", __func__, curRssi, roamRssi);
1315	}
1316	/*
1317	 * Check if a new ap should be used and switch.
1318	 * XXX deauth current ap
1319	 */
1320	if (curRate < roamRate || curRssi < roamRssi) {
1321		if (time_after(ticks, ic->ic_lastscan + vap->iv_scanvalid)) {
1322			/*
1323			 * Scan cache contents are too old; force a scan now
1324			 * if possible so we have current state to make a
1325			 * decision with.  We don't kick off a bg scan if
1326			 * we're using dynamic turbo and boosted or if the
1327			 * channel is busy.
1328			 * XXX force immediate switch on scan complete
1329			 */
1330			if (!IEEE80211_IS_CHAN_DTURBO(ic->ic_curchan) &&
1331			    time_after(ticks, ic->ic_lastdata + vap->iv_bgscanidle))
1332				ieee80211_bg_scan(vap, 0);
1333			return;
1334		}
1335		se->base.se_rssi = curRssi;
1336		selbs = select_bss(ss, vap, IEEE80211_MSG_ROAM);
1337		if (selbs != NULL && selbs != se) {
1338			struct ieee80211_channel *chan;
1339
1340			IEEE80211_DPRINTF(vap,
1341			    IEEE80211_MSG_ROAM | IEEE80211_MSG_DEBUG,
1342			    "%s: ROAM: curRate %u, roamRate %u, "
1343			    "curRssi %d, roamRssi %d\n", __func__,
1344			    curRate, roamRate, curRssi, roamRssi);
1345
1346			chan = selbs->base.se_chan;
1347			if (selbs->se_flags & STA_DEMOTE11B)
1348				chan = demote11b(vap, chan);
1349			(void) ieee80211_sta_join(vap, chan, &selbs->base);
1350		}
1351	}
1352}
1353
1354/*
1355 * Age entries in the scan cache.
1356 * XXX also do roaming since it's convenient
1357 */
1358static void
1359sta_age(struct ieee80211_scan_state *ss)
1360{
1361	struct ieee80211vap *vap = ss->ss_vap;
1362
1363	adhoc_age(ss);
1364	/*
1365	 * If rate control is enabled check periodically to see if
1366	 * we should roam from our current connection to one that
1367	 * might be better.  This only applies when we're operating
1368	 * in sta mode and automatic roaming is set.
1369	 * XXX defer if busy
1370	 * XXX repeater station
1371	 * XXX do when !bgscan?
1372	 */
1373	KASSERT(vap->iv_opmode == IEEE80211_M_STA,
1374		("wrong mode %u", vap->iv_opmode));
1375	if (vap->iv_roaming == IEEE80211_ROAMING_AUTO &&
1376	    (vap->iv_flags & IEEE80211_F_BGSCAN) &&
1377	    vap->iv_state >= IEEE80211_S_RUN)
1378		/* XXX vap is implicit */
1379		sta_roam_check(ss, vap);
1380}
1381
1382/*
1383 * Iterate over the entries in the scan cache, invoking
1384 * the callback function on each one.
1385 */
1386static void
1387sta_iterate(struct ieee80211_scan_state *ss,
1388	ieee80211_scan_iter_func *f, void *arg)
1389{
1390	struct sta_table *st = ss->ss_priv;
1391	struct sta_entry *se;
1392	u_int gen;
1393
1394	mtx_lock(&st->st_scanlock);
1395	gen = st->st_scaniter++;
1396restart:
1397	IEEE80211_SCAN_TABLE_LOCK(st);
1398	TAILQ_FOREACH(se, &st->st_entry, se_list) {
1399		if (se->se_scangen != gen) {
1400			se->se_scangen = gen;
1401			/* update public state */
1402			se->base.se_age = ticks - se->se_lastupdate;
1403			IEEE80211_SCAN_TABLE_UNLOCK(st);
1404			(*f)(arg, &se->base);
1405			goto restart;
1406		}
1407	}
1408	IEEE80211_SCAN_TABLE_UNLOCK(st);
1409
1410	mtx_unlock(&st->st_scanlock);
1411}
1412
1413static void
1414sta_assoc_fail(struct ieee80211_scan_state *ss,
1415	const uint8_t macaddr[IEEE80211_ADDR_LEN], int reason)
1416{
1417	struct sta_table *st = ss->ss_priv;
1418	struct sta_entry *se;
1419
1420	se = sta_lookup(st, macaddr);
1421	if (se != NULL) {
1422		se->se_fails++;
1423		se->se_lastfail = ticks;
1424		IEEE80211_NOTE_MAC(ss->ss_vap, IEEE80211_MSG_SCAN,
1425		    macaddr, "%s: reason %u fails %u",
1426		    __func__, reason, se->se_fails);
1427	}
1428}
1429
1430static void
1431sta_assoc_success(struct ieee80211_scan_state *ss,
1432	const uint8_t macaddr[IEEE80211_ADDR_LEN])
1433{
1434	struct sta_table *st = ss->ss_priv;
1435	struct sta_entry *se;
1436
1437	se = sta_lookup(st, macaddr);
1438	if (se != NULL) {
1439#if 0
1440		se->se_fails = 0;
1441		IEEE80211_NOTE_MAC(ss->ss_vap, IEEE80211_MSG_SCAN,
1442		    macaddr, "%s: fails %u",
1443		    __func__, se->se_fails);
1444#endif
1445		se->se_lastassoc = ticks;
1446	}
1447}
1448
1449static const struct ieee80211_scanner sta_default = {
1450	.scan_name		= "default",
1451	.scan_attach		= sta_attach,
1452	.scan_detach		= sta_detach,
1453	.scan_start		= sta_start,
1454	.scan_restart		= sta_restart,
1455	.scan_cancel		= sta_cancel,
1456	.scan_end		= sta_pick_bss,
1457	.scan_flush		= sta_flush,
1458	.scan_add		= sta_add,
1459	.scan_age		= sta_age,
1460	.scan_iterate		= sta_iterate,
1461	.scan_assoc_fail	= sta_assoc_fail,
1462	.scan_assoc_success	= sta_assoc_success,
1463};
1464IEEE80211_SCANNER_ALG(sta, IEEE80211_M_STA, sta_default);
1465
1466/*
1467 * Adhoc mode-specific support.
1468 */
1469
1470static const uint16_t adhocWorld[] =		/* 36, 40, 44, 48 */
1471{ 5180, 5200, 5220, 5240 };
1472static const uint16_t adhocFcc3[] =		/* 36, 40, 44, 48 145, 149, 153, 157, 161, 165 */
1473{ 5180, 5200, 5220, 5240, 5725, 5745, 5765, 5785, 5805, 5825 };
1474static const uint16_t adhocMkk[] =		/* 34, 38, 42, 46 */
1475{ 5170, 5190, 5210, 5230 };
1476static const uint16_t adhoc11b[] =		/* 10, 11 */
1477{ 2457, 2462 };
1478
1479static const struct scanlist adhocScanTable[] = {
1480	{ IEEE80211_MODE_11B,   	X(adhoc11b) },
1481	{ IEEE80211_MODE_11A,   	X(adhocWorld) },
1482	{ IEEE80211_MODE_11A,   	X(adhocFcc3) },
1483	{ IEEE80211_MODE_11B,   	X(adhocMkk) },
1484	{ .list = NULL }
1485};
1486#undef X
1487
1488/*
1489 * Start an adhoc-mode scan by populating the channel list.
1490 */
1491static int
1492adhoc_start(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
1493{
1494	struct sta_table *st = ss->ss_priv;
1495
1496	makescanlist(ss, vap, adhocScanTable);
1497
1498	if (ss->ss_mindwell == 0)
1499		ss->ss_mindwell = msecs_to_ticks(200);	/* 200ms */
1500	if (ss->ss_maxdwell == 0)
1501		ss->ss_maxdwell = msecs_to_ticks(200);	/* 200ms */
1502
1503	st->st_scangen++;
1504	st->st_newscan = 1;
1505
1506	return 0;
1507}
1508
1509/*
1510 * Select a channel to start an adhoc network on.
1511 * The channel list was populated with appropriate
1512 * channels so select one that looks least occupied.
1513 */
1514static struct ieee80211_channel *
1515adhoc_pick_channel(struct ieee80211_scan_state *ss, int flags)
1516{
1517	struct sta_table *st = ss->ss_priv;
1518	struct sta_entry *se;
1519	struct ieee80211_channel *c, *bestchan;
1520	int i, bestrssi, maxrssi;
1521
1522	bestchan = NULL;
1523	bestrssi = -1;
1524
1525	IEEE80211_SCAN_TABLE_LOCK(st);
1526	for (i = 0; i < ss->ss_last; i++) {
1527		c = ss->ss_chans[i];
1528		/* never consider a channel with radar */
1529		if (IEEE80211_IS_CHAN_RADAR(c))
1530			continue;
1531		/* skip channels disallowed by regulatory settings */
1532		if (IEEE80211_IS_CHAN_NOADHOC(c))
1533			continue;
1534		/* check channel attributes for band compatibility */
1535		if (flags != 0 && (c->ic_flags & flags) != flags)
1536			continue;
1537		maxrssi = 0;
1538		TAILQ_FOREACH(se, &st->st_entry, se_list) {
1539			if (se->base.se_chan != c)
1540				continue;
1541			if (se->base.se_rssi > maxrssi)
1542				maxrssi = se->base.se_rssi;
1543		}
1544		if (bestchan == NULL || maxrssi < bestrssi)
1545			bestchan = c;
1546	}
1547	IEEE80211_SCAN_TABLE_UNLOCK(st);
1548
1549	return bestchan;
1550}
1551
1552/*
1553 * Pick an ibss network to join or find a channel
1554 * to use to start an ibss network.
1555 */
1556static int
1557adhoc_pick_bss(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
1558{
1559	struct sta_table *st = ss->ss_priv;
1560	struct sta_entry *selbs;
1561	struct ieee80211_channel *chan;
1562
1563	KASSERT(vap->iv_opmode == IEEE80211_M_IBSS ||
1564		vap->iv_opmode == IEEE80211_M_AHDEMO ||
1565		vap->iv_opmode == IEEE80211_M_MBSS,
1566		("wrong opmode %u", vap->iv_opmode));
1567
1568	if (st->st_newscan) {
1569		sta_update_notseen(st);
1570		st->st_newscan = 0;
1571	}
1572	if (ss->ss_flags & IEEE80211_SCAN_NOPICK) {
1573		/*
1574		 * Manual/background scan, don't select+join the
1575		 * bss, just return.  The scanning framework will
1576		 * handle notification that this has completed.
1577		 */
1578		ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
1579		return 1;
1580	}
1581	/*
1582	 * Automatic sequencing; look for a candidate and
1583	 * if found join the network.
1584	 */
1585	/* NB: unlocked read should be ok */
1586	if (TAILQ_FIRST(&st->st_entry) == NULL) {
1587		IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
1588			"%s: no scan candidate\n", __func__);
1589		if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
1590			return 0;
1591notfound:
1592		/* NB: never auto-start a tdma network for slot !0 */
1593#ifdef IEEE80211_SUPPORT_TDMA
1594		if (vap->iv_des_nssid &&
1595		    ((vap->iv_caps & IEEE80211_C_TDMA) == 0 ||
1596		     ieee80211_tdma_getslot(vap) == 0)) {
1597#else
1598		if (vap->iv_des_nssid) {
1599#endif
1600			/*
1601			 * No existing adhoc network to join and we have
1602			 * an ssid; start one up.  If no channel was
1603			 * specified, try to select a channel.
1604			 */
1605			if (vap->iv_des_chan == IEEE80211_CHAN_ANYC ||
1606			    IEEE80211_IS_CHAN_RADAR(vap->iv_des_chan)) {
1607				struct ieee80211com *ic = vap->iv_ic;
1608
1609				chan = adhoc_pick_channel(ss, 0);
1610				if (chan != NULL)
1611					chan = ieee80211_ht_adjust_channel(ic,
1612					    chan, vap->iv_flags_ht);
1613			} else
1614				chan = vap->iv_des_chan;
1615			if (chan != NULL) {
1616				ieee80211_create_ibss(vap, chan);
1617				return 1;
1618			}
1619		}
1620		/*
1621		 * If nothing suitable was found decrement
1622		 * the failure counts so entries will be
1623		 * reconsidered the next time around.  We
1624		 * really want to do this only for sta's
1625		 * where we've previously had some success.
1626		 */
1627		sta_dec_fails(st);
1628		st->st_newscan = 1;
1629		return 0;			/* restart scan */
1630	}
1631	selbs = select_bss(ss, vap, IEEE80211_MSG_SCAN);
1632	if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
1633		return (selbs != NULL);
1634	if (selbs == NULL)
1635		goto notfound;
1636	chan = selbs->base.se_chan;
1637	if (selbs->se_flags & STA_DEMOTE11B)
1638		chan = demote11b(vap, chan);
1639	if (!ieee80211_sta_join(vap, chan, &selbs->base))
1640		goto notfound;
1641	return 1;				/* terminate scan */
1642}
1643
1644/*
1645 * Age entries in the scan cache.
1646 */
1647static void
1648adhoc_age(struct ieee80211_scan_state *ss)
1649{
1650	struct sta_table *st = ss->ss_priv;
1651	struct sta_entry *se, *next;
1652
1653	IEEE80211_SCAN_TABLE_LOCK(st);
1654	TAILQ_FOREACH_SAFE(se, &st->st_entry, se_list, next) {
1655		if (se->se_notseen > STA_PURGE_SCANS) {
1656			TAILQ_REMOVE(&st->st_entry, se, se_list);
1657			LIST_REMOVE(se, se_hash);
1658			ieee80211_ies_cleanup(&se->base.se_ies);
1659			free(se, M_80211_SCAN);
1660		}
1661	}
1662	IEEE80211_SCAN_TABLE_UNLOCK(st);
1663}
1664
1665static const struct ieee80211_scanner adhoc_default = {
1666	.scan_name		= "default",
1667	.scan_attach		= sta_attach,
1668	.scan_detach		= sta_detach,
1669	.scan_start		= adhoc_start,
1670	.scan_restart		= sta_restart,
1671	.scan_cancel		= sta_cancel,
1672	.scan_end		= adhoc_pick_bss,
1673	.scan_flush		= sta_flush,
1674	.scan_pickchan		= adhoc_pick_channel,
1675	.scan_add		= sta_add,
1676	.scan_age		= adhoc_age,
1677	.scan_iterate		= sta_iterate,
1678	.scan_assoc_fail	= sta_assoc_fail,
1679	.scan_assoc_success	= sta_assoc_success,
1680};
1681IEEE80211_SCANNER_ALG(ibss, IEEE80211_M_IBSS, adhoc_default);
1682IEEE80211_SCANNER_ALG(ahdemo, IEEE80211_M_AHDEMO, adhoc_default);
1683
1684static void
1685ap_force_promisc(struct ieee80211com *ic)
1686{
1687	struct ifnet *ifp = ic->ic_ifp;
1688
1689	IEEE80211_LOCK(ic);
1690	/* set interface into promiscuous mode */
1691	ifp->if_flags |= IFF_PROMISC;
1692	ieee80211_runtask(ic, &ic->ic_promisc_task);
1693	IEEE80211_UNLOCK(ic);
1694}
1695
1696static void
1697ap_reset_promisc(struct ieee80211com *ic)
1698{
1699	IEEE80211_LOCK(ic);
1700	ieee80211_syncifflag_locked(ic, IFF_PROMISC);
1701	IEEE80211_UNLOCK(ic);
1702}
1703
1704static int
1705ap_start(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
1706{
1707	struct sta_table *st = ss->ss_priv;
1708
1709	makescanlist(ss, vap, staScanTable);
1710
1711	if (ss->ss_mindwell == 0)
1712		ss->ss_mindwell = msecs_to_ticks(200);	/* 200ms */
1713	if (ss->ss_maxdwell == 0)
1714		ss->ss_maxdwell = msecs_to_ticks(200);	/* 200ms */
1715
1716	st->st_scangen++;
1717	st->st_newscan = 1;
1718
1719	ap_force_promisc(vap->iv_ic);
1720	return 0;
1721}
1722
1723/*
1724 * Cancel an ongoing scan.
1725 */
1726static int
1727ap_cancel(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
1728{
1729	ap_reset_promisc(vap->iv_ic);
1730	return 0;
1731}
1732
1733/*
1734 * Pick a quiet channel to use for ap operation.
1735 */
1736static struct ieee80211_channel *
1737ap_pick_channel(struct ieee80211_scan_state *ss, int flags)
1738{
1739	struct sta_table *st = ss->ss_priv;
1740	struct ieee80211_channel *bestchan = NULL;
1741	int i;
1742
1743	/* XXX select channel more intelligently, e.g. channel spread, power */
1744	/* NB: use scan list order to preserve channel preference */
1745	for (i = 0; i < ss->ss_last; i++) {
1746		struct ieee80211_channel *chan = ss->ss_chans[i];
1747		/*
1748		 * If the channel is unoccupied the max rssi
1749		 * should be zero; just take it.  Otherwise
1750		 * track the channel with the lowest rssi and
1751		 * use that when all channels appear occupied.
1752		 */
1753		if (IEEE80211_IS_CHAN_RADAR(chan))
1754			continue;
1755		if (IEEE80211_IS_CHAN_NOHOSTAP(chan))
1756			continue;
1757		/* check channel attributes for band compatibility */
1758		if (flags != 0 && (chan->ic_flags & flags) != flags)
1759			continue;
1760		KASSERT(sizeof(chan->ic_ieee) == 1, ("ic_chan size"));
1761		/* XXX channel have interference */
1762		if (st->st_maxrssi[chan->ic_ieee] == 0) {
1763			/* XXX use other considerations */
1764			return chan;
1765		}
1766		if (bestchan == NULL ||
1767		    st->st_maxrssi[chan->ic_ieee] < st->st_maxrssi[bestchan->ic_ieee])
1768			bestchan = chan;
1769	}
1770	return bestchan;
1771}
1772
1773/*
1774 * Pick a quiet channel to use for ap operation.
1775 */
1776static int
1777ap_end(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
1778{
1779	struct ieee80211com *ic = vap->iv_ic;
1780	struct ieee80211_channel *bestchan;
1781
1782	KASSERT(vap->iv_opmode == IEEE80211_M_HOSTAP,
1783		("wrong opmode %u", vap->iv_opmode));
1784	bestchan = ap_pick_channel(ss, 0);
1785	if (bestchan == NULL) {
1786		/* no suitable channel, should not happen */
1787		IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
1788		    "%s: no suitable channel! (should not happen)\n", __func__);
1789		/* XXX print something? */
1790		return 0;			/* restart scan */
1791	}
1792	/*
1793	 * If this is a dynamic turbo channel, start with the unboosted one.
1794	 */
1795	if (IEEE80211_IS_CHAN_TURBO(bestchan)) {
1796		bestchan = ieee80211_find_channel(ic, bestchan->ic_freq,
1797			bestchan->ic_flags & ~IEEE80211_CHAN_TURBO);
1798		if (bestchan == NULL) {
1799			/* should never happen ?? */
1800			return 0;
1801		}
1802	}
1803	ap_reset_promisc(ic);
1804	if (ss->ss_flags & (IEEE80211_SCAN_NOPICK | IEEE80211_SCAN_NOJOIN)) {
1805		/*
1806		 * Manual/background scan, don't select+join the
1807		 * bss, just return.  The scanning framework will
1808		 * handle notification that this has completed.
1809		 */
1810		ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
1811		return 1;
1812	}
1813	ieee80211_create_ibss(vap,
1814	    ieee80211_ht_adjust_channel(ic, bestchan, vap->iv_flags_ht));
1815	return 1;
1816}
1817
1818static const struct ieee80211_scanner ap_default = {
1819	.scan_name		= "default",
1820	.scan_attach		= sta_attach,
1821	.scan_detach		= sta_detach,
1822	.scan_start		= ap_start,
1823	.scan_restart		= sta_restart,
1824	.scan_cancel		= ap_cancel,
1825	.scan_end		= ap_end,
1826	.scan_flush		= sta_flush,
1827	.scan_pickchan		= ap_pick_channel,
1828	.scan_add		= sta_add,
1829	.scan_age		= adhoc_age,
1830	.scan_iterate		= sta_iterate,
1831	.scan_assoc_success	= sta_assoc_success,
1832	.scan_assoc_fail	= sta_assoc_fail,
1833};
1834IEEE80211_SCANNER_ALG(ap, IEEE80211_M_HOSTAP, ap_default);
1835
1836#ifdef IEEE80211_SUPPORT_MESH
1837/*
1838 * Pick an mbss network to join or find a channel
1839 * to use to start an mbss network.
1840 */
1841static int
1842mesh_pick_bss(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
1843{
1844	struct sta_table *st = ss->ss_priv;
1845	struct ieee80211_mesh_state *ms = vap->iv_mesh;
1846	struct sta_entry *selbs;
1847	struct ieee80211_channel *chan;
1848
1849	KASSERT(vap->iv_opmode == IEEE80211_M_MBSS,
1850		("wrong opmode %u", vap->iv_opmode));
1851
1852	if (st->st_newscan) {
1853		sta_update_notseen(st);
1854		st->st_newscan = 0;
1855	}
1856	if (ss->ss_flags & IEEE80211_SCAN_NOPICK) {
1857		/*
1858		 * Manual/background scan, don't select+join the
1859		 * bss, just return.  The scanning framework will
1860		 * handle notification that this has completed.
1861		 */
1862		ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
1863		return 1;
1864	}
1865	/*
1866	 * Automatic sequencing; look for a candidate and
1867	 * if found join the network.
1868	 */
1869	/* NB: unlocked read should be ok */
1870	if (TAILQ_FIRST(&st->st_entry) == NULL) {
1871		IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
1872			"%s: no scan candidate\n", __func__);
1873		if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
1874			return 0;
1875notfound:
1876		if (ms->ms_idlen != 0) {
1877			/*
1878			 * No existing mbss network to join and we have
1879			 * a meshid; start one up.  If no channel was
1880			 * specified, try to select a channel.
1881			 */
1882			if (vap->iv_des_chan == IEEE80211_CHAN_ANYC ||
1883			    IEEE80211_IS_CHAN_RADAR(vap->iv_des_chan)) {
1884				struct ieee80211com *ic = vap->iv_ic;
1885
1886				chan = adhoc_pick_channel(ss, 0);
1887				if (chan != NULL)
1888					chan = ieee80211_ht_adjust_channel(ic,
1889					    chan, vap->iv_flags_ht);
1890			} else
1891				chan = vap->iv_des_chan;
1892			if (chan != NULL) {
1893				ieee80211_create_ibss(vap, chan);
1894				return 1;
1895			}
1896		}
1897		/*
1898		 * If nothing suitable was found decrement
1899		 * the failure counts so entries will be
1900		 * reconsidered the next time around.  We
1901		 * really want to do this only for sta's
1902		 * where we've previously had some success.
1903		 */
1904		sta_dec_fails(st);
1905		st->st_newscan = 1;
1906		return 0;			/* restart scan */
1907	}
1908	selbs = select_bss(ss, vap, IEEE80211_MSG_SCAN);
1909	if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
1910		return (selbs != NULL);
1911	if (selbs == NULL)
1912		goto notfound;
1913	chan = selbs->base.se_chan;
1914	if (selbs->se_flags & STA_DEMOTE11B)
1915		chan = demote11b(vap, chan);
1916	if (!ieee80211_sta_join(vap, chan, &selbs->base))
1917		goto notfound;
1918	return 1;				/* terminate scan */
1919}
1920
1921static const struct ieee80211_scanner mesh_default = {
1922	.scan_name		= "default",
1923	.scan_attach		= sta_attach,
1924	.scan_detach		= sta_detach,
1925	.scan_start		= adhoc_start,
1926	.scan_restart		= sta_restart,
1927	.scan_cancel		= sta_cancel,
1928	.scan_end		= mesh_pick_bss,
1929	.scan_flush		= sta_flush,
1930	.scan_pickchan		= adhoc_pick_channel,
1931	.scan_add		= sta_add,
1932	.scan_age		= adhoc_age,
1933	.scan_iterate		= sta_iterate,
1934	.scan_assoc_fail	= sta_assoc_fail,
1935	.scan_assoc_success	= sta_assoc_success,
1936};
1937IEEE80211_SCANNER_ALG(mesh, IEEE80211_M_MBSS, mesh_default);
1938#endif /* IEEE80211_SUPPORT_MESH */
1939