xref: /linux/net/mac80211/scan.c (revision a5766f11cfd3a0c03450d99c8fe548c2940be884)
1 /*
2  * Scanning implementation
3  *
4  * Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
5  * Copyright 2004, Instant802 Networks, Inc.
6  * Copyright 2005, Devicescape Software, Inc.
7  * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
8  * Copyright 2007, Michael Wu <flamingice@sourmilk.net>
9  *
10  * This program is free software; you can redistribute it and/or modify
11  * it under the terms of the GNU General Public License version 2 as
12  * published by the Free Software Foundation.
13  */
14 
15 /* TODO:
16  * order BSS list by RSSI(?) ("quality of AP")
17  * scan result table filtering (by capability (privacy, IBSS/BSS, WPA/RSN IE,
18  *    SSID)
19  */
20 
21 #include <linux/wireless.h>
22 #include <linux/if_arp.h>
23 #include <net/mac80211.h>
24 #include <net/iw_handler.h>
25 
26 #include "ieee80211_i.h"
27 #include "mesh.h"
28 
29 #define IEEE80211_PROBE_DELAY (HZ / 33)
30 #define IEEE80211_CHANNEL_TIME (HZ / 33)
31 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 5)
32 
33 void ieee80211_rx_bss_list_init(struct ieee80211_local *local)
34 {
35 	spin_lock_init(&local->bss_lock);
36 	INIT_LIST_HEAD(&local->bss_list);
37 }
38 
39 void ieee80211_rx_bss_list_deinit(struct ieee80211_local *local)
40 {
41 	struct ieee80211_bss *bss, *tmp;
42 
43 	list_for_each_entry_safe(bss, tmp, &local->bss_list, list)
44 		ieee80211_rx_bss_put(local, bss);
45 }
46 
47 struct ieee80211_bss *
48 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
49 		     u8 *ssid, u8 ssid_len)
50 {
51 	struct ieee80211_bss *bss;
52 
53 	spin_lock_bh(&local->bss_lock);
54 	bss = local->bss_hash[STA_HASH(bssid)];
55 	while (bss) {
56 		if (!bss_mesh_cfg(bss) &&
57 		    !memcmp(bss->bssid, bssid, ETH_ALEN) &&
58 		    bss->freq == freq &&
59 		    bss->ssid_len == ssid_len &&
60 		    (ssid_len == 0 || !memcmp(bss->ssid, ssid, ssid_len))) {
61 			atomic_inc(&bss->users);
62 			break;
63 		}
64 		bss = bss->hnext;
65 	}
66 	spin_unlock_bh(&local->bss_lock);
67 	return bss;
68 }
69 
70 /* Caller must hold local->bss_lock */
71 static void __ieee80211_rx_bss_hash_add(struct ieee80211_local *local,
72 					struct ieee80211_bss *bss)
73 {
74 	u8 hash_idx;
75 
76 	if (bss_mesh_cfg(bss))
77 		hash_idx = mesh_id_hash(bss_mesh_id(bss),
78 					bss_mesh_id_len(bss));
79 	else
80 		hash_idx = STA_HASH(bss->bssid);
81 
82 	bss->hnext = local->bss_hash[hash_idx];
83 	local->bss_hash[hash_idx] = bss;
84 }
85 
86 /* Caller must hold local->bss_lock */
87 static void __ieee80211_rx_bss_hash_del(struct ieee80211_local *local,
88 					struct ieee80211_bss *bss)
89 {
90 	struct ieee80211_bss *b, *prev = NULL;
91 	b = local->bss_hash[STA_HASH(bss->bssid)];
92 	while (b) {
93 		if (b == bss) {
94 			if (!prev)
95 				local->bss_hash[STA_HASH(bss->bssid)] =
96 					bss->hnext;
97 			else
98 				prev->hnext = bss->hnext;
99 			break;
100 		}
101 		prev = b;
102 		b = b->hnext;
103 	}
104 }
105 
106 struct ieee80211_bss *
107 ieee80211_rx_bss_add(struct ieee80211_local *local, u8 *bssid, int freq,
108 		     u8 *ssid, u8 ssid_len)
109 {
110 	struct ieee80211_bss *bss;
111 
112 	bss = kzalloc(sizeof(*bss), GFP_ATOMIC);
113 	if (!bss)
114 		return NULL;
115 	atomic_set(&bss->users, 2);
116 	memcpy(bss->bssid, bssid, ETH_ALEN);
117 	bss->freq = freq;
118 	if (ssid && ssid_len <= IEEE80211_MAX_SSID_LEN) {
119 		memcpy(bss->ssid, ssid, ssid_len);
120 		bss->ssid_len = ssid_len;
121 	}
122 
123 	spin_lock_bh(&local->bss_lock);
124 	/* TODO: order by RSSI? */
125 	list_add_tail(&bss->list, &local->bss_list);
126 	__ieee80211_rx_bss_hash_add(local, bss);
127 	spin_unlock_bh(&local->bss_lock);
128 	return bss;
129 }
130 
131 #ifdef CONFIG_MAC80211_MESH
132 static struct ieee80211_bss *
133 ieee80211_rx_mesh_bss_get(struct ieee80211_local *local, u8 *mesh_id, int mesh_id_len,
134 			  u8 *mesh_cfg, int freq)
135 {
136 	struct ieee80211_bss *bss;
137 
138 	spin_lock_bh(&local->bss_lock);
139 	bss = local->bss_hash[mesh_id_hash(mesh_id, mesh_id_len)];
140 	while (bss) {
141 		if (bss_mesh_cfg(bss) &&
142 		    !memcmp(bss_mesh_cfg(bss), mesh_cfg, MESH_CFG_CMP_LEN) &&
143 		    bss->freq == freq &&
144 		    mesh_id_len == bss->mesh_id_len &&
145 		    (mesh_id_len == 0 || !memcmp(bss->mesh_id, mesh_id,
146 						 mesh_id_len))) {
147 			atomic_inc(&bss->users);
148 			break;
149 		}
150 		bss = bss->hnext;
151 	}
152 	spin_unlock_bh(&local->bss_lock);
153 	return bss;
154 }
155 
156 static struct ieee80211_bss *
157 ieee80211_rx_mesh_bss_add(struct ieee80211_local *local, u8 *mesh_id, int mesh_id_len,
158 			  u8 *mesh_cfg, int mesh_config_len, int freq)
159 {
160 	struct ieee80211_bss *bss;
161 
162 	if (mesh_config_len != MESH_CFG_LEN)
163 		return NULL;
164 
165 	bss = kzalloc(sizeof(*bss), GFP_ATOMIC);
166 	if (!bss)
167 		return NULL;
168 
169 	bss->mesh_cfg = kmalloc(MESH_CFG_CMP_LEN, GFP_ATOMIC);
170 	if (!bss->mesh_cfg) {
171 		kfree(bss);
172 		return NULL;
173 	}
174 
175 	if (mesh_id_len && mesh_id_len <= IEEE80211_MAX_MESH_ID_LEN) {
176 		bss->mesh_id = kmalloc(mesh_id_len, GFP_ATOMIC);
177 		if (!bss->mesh_id) {
178 			kfree(bss->mesh_cfg);
179 			kfree(bss);
180 			return NULL;
181 		}
182 		memcpy(bss->mesh_id, mesh_id, mesh_id_len);
183 	}
184 
185 	atomic_set(&bss->users, 2);
186 	memcpy(bss->mesh_cfg, mesh_cfg, MESH_CFG_CMP_LEN);
187 	bss->mesh_id_len = mesh_id_len;
188 	bss->freq = freq;
189 	spin_lock_bh(&local->bss_lock);
190 	/* TODO: order by RSSI? */
191 	list_add_tail(&bss->list, &local->bss_list);
192 	__ieee80211_rx_bss_hash_add(local, bss);
193 	spin_unlock_bh(&local->bss_lock);
194 	return bss;
195 }
196 #endif
197 
198 static void ieee80211_rx_bss_free(struct ieee80211_bss *bss)
199 {
200 	kfree(bss->ies);
201 	kfree(bss_mesh_id(bss));
202 	kfree(bss_mesh_cfg(bss));
203 	kfree(bss);
204 }
205 
206 void ieee80211_rx_bss_put(struct ieee80211_local *local,
207 			  struct ieee80211_bss *bss)
208 {
209 	local_bh_disable();
210 	if (!atomic_dec_and_lock(&bss->users, &local->bss_lock)) {
211 		local_bh_enable();
212 		return;
213 	}
214 
215 	__ieee80211_rx_bss_hash_del(local, bss);
216 	list_del(&bss->list);
217 	spin_unlock_bh(&local->bss_lock);
218 	ieee80211_rx_bss_free(bss);
219 }
220 
221 struct ieee80211_bss *
222 ieee80211_bss_info_update(struct ieee80211_local *local,
223 			  struct ieee80211_rx_status *rx_status,
224 			  struct ieee80211_mgmt *mgmt,
225 			  size_t len,
226 			  struct ieee802_11_elems *elems,
227 			  int freq, bool beacon)
228 {
229 	struct ieee80211_bss *bss;
230 	int clen;
231 
232 #ifdef CONFIG_MAC80211_MESH
233 	if (elems->mesh_config)
234 		bss = ieee80211_rx_mesh_bss_get(local, elems->mesh_id,
235 				elems->mesh_id_len, elems->mesh_config, freq);
236 	else
237 #endif
238 		bss = ieee80211_rx_bss_get(local, mgmt->bssid, freq,
239 					   elems->ssid, elems->ssid_len);
240 	if (!bss) {
241 #ifdef CONFIG_MAC80211_MESH
242 		if (elems->mesh_config)
243 			bss = ieee80211_rx_mesh_bss_add(local, elems->mesh_id,
244 				elems->mesh_id_len, elems->mesh_config,
245 				elems->mesh_config_len, freq);
246 		else
247 #endif
248 			bss = ieee80211_rx_bss_add(local, mgmt->bssid, freq,
249 						  elems->ssid, elems->ssid_len);
250 		if (!bss)
251 			return NULL;
252 	} else {
253 #if 0
254 		/* TODO: order by RSSI? */
255 		spin_lock_bh(&local->bss_lock);
256 		list_move_tail(&bss->list, &local->bss_list);
257 		spin_unlock_bh(&local->bss_lock);
258 #endif
259 	}
260 
261 	/* save the ERP value so that it is available at association time */
262 	if (elems->erp_info && elems->erp_info_len >= 1) {
263 		bss->erp_value = elems->erp_info[0];
264 		bss->has_erp_value = 1;
265 	}
266 
267 	bss->beacon_int = le16_to_cpu(mgmt->u.beacon.beacon_int);
268 	bss->capability = le16_to_cpu(mgmt->u.beacon.capab_info);
269 
270 	if (elems->tim) {
271 		struct ieee80211_tim_ie *tim_ie =
272 			(struct ieee80211_tim_ie *)elems->tim;
273 		bss->dtim_period = tim_ie->dtim_period;
274 	}
275 
276 	/* set default value for buggy APs */
277 	if (!elems->tim || bss->dtim_period == 0)
278 		bss->dtim_period = 1;
279 
280 	bss->supp_rates_len = 0;
281 	if (elems->supp_rates) {
282 		clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
283 		if (clen > elems->supp_rates_len)
284 			clen = elems->supp_rates_len;
285 		memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
286 		       clen);
287 		bss->supp_rates_len += clen;
288 	}
289 	if (elems->ext_supp_rates) {
290 		clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
291 		if (clen > elems->ext_supp_rates_len)
292 			clen = elems->ext_supp_rates_len;
293 		memcpy(&bss->supp_rates[bss->supp_rates_len],
294 		       elems->ext_supp_rates, clen);
295 		bss->supp_rates_len += clen;
296 	}
297 
298 	bss->band = rx_status->band;
299 
300 	bss->timestamp = le64_to_cpu(mgmt->u.beacon.timestamp);
301 	bss->last_update = jiffies;
302 	bss->signal = rx_status->signal;
303 	bss->noise = rx_status->noise;
304 	bss->qual = rx_status->qual;
305 	bss->wmm_used = elems->wmm_param || elems->wmm_info;
306 
307 	if (!beacon)
308 		bss->last_probe_resp = jiffies;
309 
310 	/*
311 	 * For probe responses, or if we don't have any information yet,
312 	 * use the IEs from the beacon.
313 	 */
314 	if (!bss->ies || !beacon) {
315 		if (bss->ies == NULL || bss->ies_len < elems->total_len) {
316 			kfree(bss->ies);
317 			bss->ies = kmalloc(elems->total_len, GFP_ATOMIC);
318 		}
319 		if (bss->ies) {
320 			memcpy(bss->ies, elems->ie_start, elems->total_len);
321 			bss->ies_len = elems->total_len;
322 		} else
323 			bss->ies_len = 0;
324 	}
325 
326 	return bss;
327 }
328 
329 ieee80211_rx_result
330 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb,
331 		  struct ieee80211_rx_status *rx_status)
332 {
333 	struct ieee80211_mgmt *mgmt;
334 	struct ieee80211_bss *bss;
335 	u8 *elements;
336 	struct ieee80211_channel *channel;
337 	size_t baselen;
338 	int freq;
339 	__le16 fc;
340 	bool presp, beacon = false;
341 	struct ieee802_11_elems elems;
342 
343 	if (skb->len < 2)
344 		return RX_DROP_UNUSABLE;
345 
346 	mgmt = (struct ieee80211_mgmt *) skb->data;
347 	fc = mgmt->frame_control;
348 
349 	if (ieee80211_is_ctl(fc))
350 		return RX_CONTINUE;
351 
352 	if (skb->len < 24)
353 		return RX_DROP_MONITOR;
354 
355 	presp = ieee80211_is_probe_resp(fc);
356 	if (presp) {
357 		/* ignore ProbeResp to foreign address */
358 		if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
359 			return RX_DROP_MONITOR;
360 
361 		presp = true;
362 		elements = mgmt->u.probe_resp.variable;
363 		baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
364 	} else {
365 		beacon = ieee80211_is_beacon(fc);
366 		baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
367 		elements = mgmt->u.beacon.variable;
368 	}
369 
370 	if (!presp && !beacon)
371 		return RX_CONTINUE;
372 
373 	if (baselen > skb->len)
374 		return RX_DROP_MONITOR;
375 
376 	ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
377 
378 	if (elems.ds_params && elems.ds_params_len == 1)
379 		freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
380 	else
381 		freq = rx_status->freq;
382 
383 	channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
384 
385 	if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
386 		return RX_DROP_MONITOR;
387 
388 	bss = ieee80211_bss_info_update(sdata->local, rx_status,
389 					mgmt, skb->len, &elems,
390 					freq, beacon);
391 	ieee80211_rx_bss_put(sdata->local, bss);
392 
393 	dev_kfree_skb(skb);
394 	return RX_QUEUED;
395 }
396 
397 static void ieee80211_send_nullfunc(struct ieee80211_local *local,
398 				    struct ieee80211_sub_if_data *sdata,
399 				    int powersave)
400 {
401 	struct sk_buff *skb;
402 	struct ieee80211_hdr *nullfunc;
403 	__le16 fc;
404 
405 	skb = dev_alloc_skb(local->hw.extra_tx_headroom + 24);
406 	if (!skb) {
407 		printk(KERN_DEBUG "%s: failed to allocate buffer for nullfunc "
408 		       "frame\n", sdata->dev->name);
409 		return;
410 	}
411 	skb_reserve(skb, local->hw.extra_tx_headroom);
412 
413 	nullfunc = (struct ieee80211_hdr *) skb_put(skb, 24);
414 	memset(nullfunc, 0, 24);
415 	fc = cpu_to_le16(IEEE80211_FTYPE_DATA | IEEE80211_STYPE_NULLFUNC |
416 			 IEEE80211_FCTL_TODS);
417 	if (powersave)
418 		fc |= cpu_to_le16(IEEE80211_FCTL_PM);
419 	nullfunc->frame_control = fc;
420 	memcpy(nullfunc->addr1, sdata->u.sta.bssid, ETH_ALEN);
421 	memcpy(nullfunc->addr2, sdata->dev->dev_addr, ETH_ALEN);
422 	memcpy(nullfunc->addr3, sdata->u.sta.bssid, ETH_ALEN);
423 
424 	ieee80211_tx_skb(sdata, skb, 0);
425 }
426 
427 void ieee80211_scan_completed(struct ieee80211_hw *hw)
428 {
429 	struct ieee80211_local *local = hw_to_local(hw);
430 	struct ieee80211_sub_if_data *sdata;
431 	union iwreq_data wrqu;
432 
433 	if (WARN_ON(!local->hw_scanning && !local->sw_scanning))
434 		return;
435 
436 	local->last_scan_completed = jiffies;
437 	memset(&wrqu, 0, sizeof(wrqu));
438 
439 	/*
440 	 * local->scan_sdata could have been NULLed by the interface
441 	 * down code in case we were scanning on an interface that is
442 	 * being taken down.
443 	 */
444 	sdata = local->scan_sdata;
445 	if (sdata)
446 		wireless_send_event(sdata->dev, SIOCGIWSCAN, &wrqu, NULL);
447 
448 	if (local->hw_scanning) {
449 		local->hw_scanning = false;
450 		if (ieee80211_hw_config(local))
451 			printk(KERN_DEBUG "%s: failed to restore operational "
452 			       "channel after scan\n", wiphy_name(local->hw.wiphy));
453 
454 		goto done;
455 	}
456 
457 	local->sw_scanning = false;
458 	if (ieee80211_hw_config(local))
459 		printk(KERN_DEBUG "%s: failed to restore operational "
460 		       "channel after scan\n", wiphy_name(local->hw.wiphy));
461 
462 
463 	netif_tx_lock_bh(local->mdev);
464 	netif_addr_lock(local->mdev);
465 	local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
466 	local->ops->configure_filter(local_to_hw(local),
467 				     FIF_BCN_PRBRESP_PROMISC,
468 				     &local->filter_flags,
469 				     local->mdev->mc_count,
470 				     local->mdev->mc_list);
471 
472 	netif_addr_unlock(local->mdev);
473 	netif_tx_unlock_bh(local->mdev);
474 
475 	rcu_read_lock();
476 	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
477 		/* Tell AP we're back */
478 		if (sdata->vif.type == NL80211_IFTYPE_STATION) {
479 			if (sdata->u.sta.flags & IEEE80211_STA_ASSOCIATED) {
480 				ieee80211_send_nullfunc(local, sdata, 0);
481 				netif_tx_wake_all_queues(sdata->dev);
482 			}
483 		} else
484 			netif_tx_wake_all_queues(sdata->dev);
485 	}
486 	rcu_read_unlock();
487 
488  done:
489 	ieee80211_mlme_notify_scan_completed(local);
490 	ieee80211_mesh_notify_scan_completed(local);
491 }
492 EXPORT_SYMBOL(ieee80211_scan_completed);
493 
494 
495 void ieee80211_scan_work(struct work_struct *work)
496 {
497 	struct ieee80211_local *local =
498 		container_of(work, struct ieee80211_local, scan_work.work);
499 	struct ieee80211_sub_if_data *sdata = local->scan_sdata;
500 	struct ieee80211_supported_band *sband;
501 	struct ieee80211_channel *chan;
502 	int skip;
503 	unsigned long next_delay = 0;
504 
505 	/*
506 	 * Avoid re-scheduling when the sdata is going away.
507 	 */
508 	if (!netif_running(sdata->dev))
509 		return;
510 
511 	switch (local->scan_state) {
512 	case SCAN_SET_CHANNEL:
513 		/*
514 		 * Get current scan band. scan_band may be IEEE80211_NUM_BANDS
515 		 * after we successfully scanned the last channel of the last
516 		 * band (and the last band is supported by the hw)
517 		 */
518 		if (local->scan_band < IEEE80211_NUM_BANDS)
519 			sband = local->hw.wiphy->bands[local->scan_band];
520 		else
521 			sband = NULL;
522 
523 		/*
524 		 * If we are at an unsupported band and have more bands
525 		 * left to scan, advance to the next supported one.
526 		 */
527 		while (!sband && local->scan_band < IEEE80211_NUM_BANDS - 1) {
528 			local->scan_band++;
529 			sband = local->hw.wiphy->bands[local->scan_band];
530 			local->scan_channel_idx = 0;
531 		}
532 
533 		/* if no more bands/channels left, complete scan */
534 		if (!sband || local->scan_channel_idx >= sband->n_channels) {
535 			ieee80211_scan_completed(local_to_hw(local));
536 			return;
537 		}
538 		skip = 0;
539 		chan = &sband->channels[local->scan_channel_idx];
540 
541 		if (chan->flags & IEEE80211_CHAN_DISABLED ||
542 		    (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
543 		     chan->flags & IEEE80211_CHAN_NO_IBSS))
544 			skip = 1;
545 
546 		if (!skip) {
547 			local->scan_channel = chan;
548 			if (ieee80211_hw_config(local)) {
549 				printk(KERN_DEBUG "%s: failed to set freq to "
550 				       "%d MHz for scan\n", wiphy_name(local->hw.wiphy),
551 				       chan->center_freq);
552 				skip = 1;
553 			}
554 		}
555 
556 		/* advance state machine to next channel/band */
557 		local->scan_channel_idx++;
558 		if (local->scan_channel_idx >= sband->n_channels) {
559 			/*
560 			 * scan_band may end up == IEEE80211_NUM_BANDS, but
561 			 * we'll catch that case above and complete the scan
562 			 * if that is the case.
563 			 */
564 			local->scan_band++;
565 			local->scan_channel_idx = 0;
566 		}
567 
568 		if (skip)
569 			break;
570 
571 		next_delay = IEEE80211_PROBE_DELAY +
572 			     usecs_to_jiffies(local->hw.channel_change_time);
573 		local->scan_state = SCAN_SEND_PROBE;
574 		break;
575 	case SCAN_SEND_PROBE:
576 		next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
577 		local->scan_state = SCAN_SET_CHANNEL;
578 
579 		if (local->scan_channel->flags & IEEE80211_CHAN_PASSIVE_SCAN)
580 			break;
581 		ieee80211_send_probe_req(sdata, NULL, local->scan_ssid,
582 					 local->scan_ssid_len);
583 		next_delay = IEEE80211_CHANNEL_TIME;
584 		break;
585 	}
586 
587 	queue_delayed_work(local->hw.workqueue, &local->scan_work,
588 			   next_delay);
589 }
590 
591 
592 int ieee80211_start_scan(struct ieee80211_sub_if_data *scan_sdata,
593 			 u8 *ssid, size_t ssid_len)
594 {
595 	struct ieee80211_local *local = scan_sdata->local;
596 	struct ieee80211_sub_if_data *sdata;
597 
598 	if (ssid_len > IEEE80211_MAX_SSID_LEN)
599 		return -EINVAL;
600 
601 	/* MLME-SCAN.request (page 118)  page 144 (11.1.3.1)
602 	 * BSSType: INFRASTRUCTURE, INDEPENDENT, ANY_BSS
603 	 * BSSID: MACAddress
604 	 * SSID
605 	 * ScanType: ACTIVE, PASSIVE
606 	 * ProbeDelay: delay (in microseconds) to be used prior to transmitting
607 	 *    a Probe frame during active scanning
608 	 * ChannelList
609 	 * MinChannelTime (>= ProbeDelay), in TU
610 	 * MaxChannelTime: (>= MinChannelTime), in TU
611 	 */
612 
613 	 /* MLME-SCAN.confirm
614 	  * BSSDescriptionSet
615 	  * ResultCode: SUCCESS, INVALID_PARAMETERS
616 	 */
617 
618 	if (local->sw_scanning || local->hw_scanning) {
619 		if (local->scan_sdata == scan_sdata)
620 			return 0;
621 		return -EBUSY;
622 	}
623 
624 	if (local->ops->hw_scan) {
625 		int rc;
626 
627 		local->hw_scanning = true;
628 		rc = local->ops->hw_scan(local_to_hw(local), ssid, ssid_len);
629 		if (rc) {
630 			local->hw_scanning = false;
631 			return rc;
632 		}
633 		local->scan_sdata = scan_sdata;
634 		return 0;
635 	}
636 
637 	local->sw_scanning = true;
638 
639 	rcu_read_lock();
640 	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
641 		if (sdata->vif.type == NL80211_IFTYPE_STATION) {
642 			if (sdata->u.sta.flags & IEEE80211_STA_ASSOCIATED) {
643 				netif_tx_stop_all_queues(sdata->dev);
644 				ieee80211_send_nullfunc(local, sdata, 1);
645 			}
646 		} else
647 			netif_tx_stop_all_queues(sdata->dev);
648 	}
649 	rcu_read_unlock();
650 
651 	if (ssid) {
652 		local->scan_ssid_len = ssid_len;
653 		memcpy(local->scan_ssid, ssid, ssid_len);
654 	} else
655 		local->scan_ssid_len = 0;
656 	local->scan_state = SCAN_SET_CHANNEL;
657 	local->scan_channel_idx = 0;
658 	local->scan_band = IEEE80211_BAND_2GHZ;
659 	local->scan_sdata = scan_sdata;
660 
661 	netif_addr_lock_bh(local->mdev);
662 	local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
663 	local->ops->configure_filter(local_to_hw(local),
664 				     FIF_BCN_PRBRESP_PROMISC,
665 				     &local->filter_flags,
666 				     local->mdev->mc_count,
667 				     local->mdev->mc_list);
668 	netif_addr_unlock_bh(local->mdev);
669 
670 	/* TODO: start scan as soon as all nullfunc frames are ACKed */
671 	queue_delayed_work(local->hw.workqueue, &local->scan_work,
672 			   IEEE80211_CHANNEL_TIME);
673 
674 	return 0;
675 }
676 
677 
678 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
679 			   u8 *ssid, size_t ssid_len)
680 {
681 	struct ieee80211_local *local = sdata->local;
682 	struct ieee80211_if_sta *ifsta;
683 
684 	if (sdata->vif.type != NL80211_IFTYPE_STATION)
685 		return ieee80211_start_scan(sdata, ssid, ssid_len);
686 
687 	/*
688 	 * STA has a state machine that might need to defer scanning
689 	 * while it's trying to associate/authenticate, therefore we
690 	 * queue it up to the state machine in that case.
691 	 */
692 
693 	if (local->sw_scanning || local->hw_scanning) {
694 		if (local->scan_sdata == sdata)
695 			return 0;
696 		return -EBUSY;
697 	}
698 
699 	ifsta = &sdata->u.sta;
700 
701 	ifsta->scan_ssid_len = ssid_len;
702 	if (ssid_len)
703 		memcpy(ifsta->scan_ssid, ssid, ssid_len);
704 	set_bit(IEEE80211_STA_REQ_SCAN, &ifsta->request);
705 	queue_work(local->hw.workqueue, &ifsta->work);
706 
707 	return 0;
708 }
709 
710 
711 static void ieee80211_scan_add_ies(struct iw_request_info *info,
712 				   struct ieee80211_bss *bss,
713 				   char **current_ev, char *end_buf)
714 {
715 	u8 *pos, *end, *next;
716 	struct iw_event iwe;
717 
718 	if (bss == NULL || bss->ies == NULL)
719 		return;
720 
721 	/*
722 	 * If needed, fragment the IEs buffer (at IE boundaries) into short
723 	 * enough fragments to fit into IW_GENERIC_IE_MAX octet messages.
724 	 */
725 	pos = bss->ies;
726 	end = pos + bss->ies_len;
727 
728 	while (end - pos > IW_GENERIC_IE_MAX) {
729 		next = pos + 2 + pos[1];
730 		while (next + 2 + next[1] - pos < IW_GENERIC_IE_MAX)
731 			next = next + 2 + next[1];
732 
733 		memset(&iwe, 0, sizeof(iwe));
734 		iwe.cmd = IWEVGENIE;
735 		iwe.u.data.length = next - pos;
736 		*current_ev = iwe_stream_add_point(info, *current_ev,
737 						   end_buf, &iwe, pos);
738 
739 		pos = next;
740 	}
741 
742 	if (end > pos) {
743 		memset(&iwe, 0, sizeof(iwe));
744 		iwe.cmd = IWEVGENIE;
745 		iwe.u.data.length = end - pos;
746 		*current_ev = iwe_stream_add_point(info, *current_ev,
747 						   end_buf, &iwe, pos);
748 	}
749 }
750 
751 
752 static char *
753 ieee80211_scan_result(struct ieee80211_local *local,
754 		      struct iw_request_info *info,
755 		      struct ieee80211_bss *bss,
756 		      char *current_ev, char *end_buf)
757 {
758 	struct iw_event iwe;
759 	char *buf;
760 
761 	if (time_after(jiffies,
762 		       bss->last_update + IEEE80211_SCAN_RESULT_EXPIRE))
763 		return current_ev;
764 
765 	memset(&iwe, 0, sizeof(iwe));
766 	iwe.cmd = SIOCGIWAP;
767 	iwe.u.ap_addr.sa_family = ARPHRD_ETHER;
768 	memcpy(iwe.u.ap_addr.sa_data, bss->bssid, ETH_ALEN);
769 	current_ev = iwe_stream_add_event(info, current_ev, end_buf, &iwe,
770 					  IW_EV_ADDR_LEN);
771 
772 	memset(&iwe, 0, sizeof(iwe));
773 	iwe.cmd = SIOCGIWESSID;
774 	if (bss_mesh_cfg(bss)) {
775 		iwe.u.data.length = bss_mesh_id_len(bss);
776 		iwe.u.data.flags = 1;
777 		current_ev = iwe_stream_add_point(info, current_ev, end_buf,
778 						  &iwe, bss_mesh_id(bss));
779 	} else {
780 		iwe.u.data.length = bss->ssid_len;
781 		iwe.u.data.flags = 1;
782 		current_ev = iwe_stream_add_point(info, current_ev, end_buf,
783 						  &iwe, bss->ssid);
784 	}
785 
786 	if (bss->capability & (WLAN_CAPABILITY_ESS | WLAN_CAPABILITY_IBSS)
787 	    || bss_mesh_cfg(bss)) {
788 		memset(&iwe, 0, sizeof(iwe));
789 		iwe.cmd = SIOCGIWMODE;
790 		if (bss_mesh_cfg(bss))
791 			iwe.u.mode = IW_MODE_MESH;
792 		else if (bss->capability & WLAN_CAPABILITY_ESS)
793 			iwe.u.mode = IW_MODE_MASTER;
794 		else
795 			iwe.u.mode = IW_MODE_ADHOC;
796 		current_ev = iwe_stream_add_event(info, current_ev, end_buf,
797 						  &iwe, IW_EV_UINT_LEN);
798 	}
799 
800 	memset(&iwe, 0, sizeof(iwe));
801 	iwe.cmd = SIOCGIWFREQ;
802 	iwe.u.freq.m = ieee80211_frequency_to_channel(bss->freq);
803 	iwe.u.freq.e = 0;
804 	current_ev = iwe_stream_add_event(info, current_ev, end_buf, &iwe,
805 					  IW_EV_FREQ_LEN);
806 
807 	memset(&iwe, 0, sizeof(iwe));
808 	iwe.cmd = SIOCGIWFREQ;
809 	iwe.u.freq.m = bss->freq;
810 	iwe.u.freq.e = 6;
811 	current_ev = iwe_stream_add_event(info, current_ev, end_buf, &iwe,
812 					  IW_EV_FREQ_LEN);
813 	memset(&iwe, 0, sizeof(iwe));
814 	iwe.cmd = IWEVQUAL;
815 	iwe.u.qual.qual = bss->qual;
816 	iwe.u.qual.level = bss->signal;
817 	iwe.u.qual.noise = bss->noise;
818 	iwe.u.qual.updated = local->wstats_flags;
819 	current_ev = iwe_stream_add_event(info, current_ev, end_buf, &iwe,
820 					  IW_EV_QUAL_LEN);
821 
822 	memset(&iwe, 0, sizeof(iwe));
823 	iwe.cmd = SIOCGIWENCODE;
824 	if (bss->capability & WLAN_CAPABILITY_PRIVACY)
825 		iwe.u.data.flags = IW_ENCODE_ENABLED | IW_ENCODE_NOKEY;
826 	else
827 		iwe.u.data.flags = IW_ENCODE_DISABLED;
828 	iwe.u.data.length = 0;
829 	current_ev = iwe_stream_add_point(info, current_ev, end_buf,
830 					  &iwe, "");
831 
832 	ieee80211_scan_add_ies(info, bss, &current_ev, end_buf);
833 
834 	if (bss->supp_rates_len > 0) {
835 		/* display all supported rates in readable format */
836 		char *p = current_ev + iwe_stream_lcp_len(info);
837 		int i;
838 
839 		memset(&iwe, 0, sizeof(iwe));
840 		iwe.cmd = SIOCGIWRATE;
841 		/* Those two flags are ignored... */
842 		iwe.u.bitrate.fixed = iwe.u.bitrate.disabled = 0;
843 
844 		for (i = 0; i < bss->supp_rates_len; i++) {
845 			iwe.u.bitrate.value = ((bss->supp_rates[i] &
846 							0x7f) * 500000);
847 			p = iwe_stream_add_value(info, current_ev, p,
848 					end_buf, &iwe, IW_EV_PARAM_LEN);
849 		}
850 		current_ev = p;
851 	}
852 
853 	buf = kmalloc(30, GFP_ATOMIC);
854 	if (buf) {
855 		memset(&iwe, 0, sizeof(iwe));
856 		iwe.cmd = IWEVCUSTOM;
857 		sprintf(buf, "tsf=%016llx", (unsigned long long)(bss->timestamp));
858 		iwe.u.data.length = strlen(buf);
859 		current_ev = iwe_stream_add_point(info, current_ev, end_buf,
860 						  &iwe, buf);
861 		memset(&iwe, 0, sizeof(iwe));
862 		iwe.cmd = IWEVCUSTOM;
863 		sprintf(buf, " Last beacon: %dms ago",
864 			jiffies_to_msecs(jiffies - bss->last_update));
865 		iwe.u.data.length = strlen(buf);
866 		current_ev = iwe_stream_add_point(info, current_ev,
867 						  end_buf, &iwe, buf);
868 		kfree(buf);
869 	}
870 
871 	if (bss_mesh_cfg(bss)) {
872 		u8 *cfg = bss_mesh_cfg(bss);
873 		buf = kmalloc(50, GFP_ATOMIC);
874 		if (buf) {
875 			memset(&iwe, 0, sizeof(iwe));
876 			iwe.cmd = IWEVCUSTOM;
877 			sprintf(buf, "Mesh network (version %d)", cfg[0]);
878 			iwe.u.data.length = strlen(buf);
879 			current_ev = iwe_stream_add_point(info, current_ev,
880 							  end_buf,
881 							  &iwe, buf);
882 			sprintf(buf, "Path Selection Protocol ID: "
883 				"0x%02X%02X%02X%02X", cfg[1], cfg[2], cfg[3],
884 							cfg[4]);
885 			iwe.u.data.length = strlen(buf);
886 			current_ev = iwe_stream_add_point(info, current_ev,
887 							  end_buf,
888 							  &iwe, buf);
889 			sprintf(buf, "Path Selection Metric ID: "
890 				"0x%02X%02X%02X%02X", cfg[5], cfg[6], cfg[7],
891 							cfg[8]);
892 			iwe.u.data.length = strlen(buf);
893 			current_ev = iwe_stream_add_point(info, current_ev,
894 							  end_buf,
895 							  &iwe, buf);
896 			sprintf(buf, "Congestion Control Mode ID: "
897 				"0x%02X%02X%02X%02X", cfg[9], cfg[10],
898 							cfg[11], cfg[12]);
899 			iwe.u.data.length = strlen(buf);
900 			current_ev = iwe_stream_add_point(info, current_ev,
901 							  end_buf,
902 							  &iwe, buf);
903 			sprintf(buf, "Channel Precedence: "
904 				"0x%02X%02X%02X%02X", cfg[13], cfg[14],
905 							cfg[15], cfg[16]);
906 			iwe.u.data.length = strlen(buf);
907 			current_ev = iwe_stream_add_point(info, current_ev,
908 							  end_buf,
909 							  &iwe, buf);
910 			kfree(buf);
911 		}
912 	}
913 
914 	return current_ev;
915 }
916 
917 
918 int ieee80211_scan_results(struct ieee80211_local *local,
919 			   struct iw_request_info *info,
920 			   char *buf, size_t len)
921 {
922 	char *current_ev = buf;
923 	char *end_buf = buf + len;
924 	struct ieee80211_bss *bss;
925 
926 	spin_lock_bh(&local->bss_lock);
927 	list_for_each_entry(bss, &local->bss_list, list) {
928 		if (buf + len - current_ev <= IW_EV_ADDR_LEN) {
929 			spin_unlock_bh(&local->bss_lock);
930 			return -E2BIG;
931 		}
932 		current_ev = ieee80211_scan_result(local, info, bss,
933 						       current_ev, end_buf);
934 	}
935 	spin_unlock_bh(&local->bss_lock);
936 	return current_ev - buf;
937 }
938