mac80211: Replace {sw, hw}_scanning variables with a bitfield
[linux-2.6.git] / net / mac80211 / scan.c
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: figure out how to avoid that the "current BSS" expires */
16
17 #include <linux/wireless.h>
18 #include <linux/if_arp.h>
19 #include <linux/rtnetlink.h>
20 #include <net/mac80211.h>
21 #include <net/iw_handler.h>
22
23 #include "ieee80211_i.h"
24 #include "driver-ops.h"
25 #include "mesh.h"
26
27 #define IEEE80211_PROBE_DELAY (HZ / 33)
28 #define IEEE80211_CHANNEL_TIME (HZ / 33)
29 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
30
31 struct ieee80211_bss *
32 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
33                      u8 *ssid, u8 ssid_len)
34 {
35         return (void *)cfg80211_get_bss(local->hw.wiphy,
36                                         ieee80211_get_channel(local->hw.wiphy,
37                                                               freq),
38                                         bssid, ssid, ssid_len,
39                                         0, 0);
40 }
41
42 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
43 {
44         struct ieee80211_bss *bss = (void *)cbss;
45
46         kfree(bss_mesh_id(bss));
47         kfree(bss_mesh_cfg(bss));
48 }
49
50 void ieee80211_rx_bss_put(struct ieee80211_local *local,
51                           struct ieee80211_bss *bss)
52 {
53         cfg80211_put_bss((struct cfg80211_bss *)bss);
54 }
55
56 struct ieee80211_bss *
57 ieee80211_bss_info_update(struct ieee80211_local *local,
58                           struct ieee80211_rx_status *rx_status,
59                           struct ieee80211_mgmt *mgmt,
60                           size_t len,
61                           struct ieee802_11_elems *elems,
62                           struct ieee80211_channel *channel,
63                           bool beacon)
64 {
65         struct ieee80211_bss *bss;
66         int clen;
67         s32 signal = 0;
68
69         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
70                 signal = rx_status->signal * 100;
71         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
72                 signal = (rx_status->signal * 100) / local->hw.max_signal;
73
74         bss = (void *)cfg80211_inform_bss_frame(local->hw.wiphy, channel,
75                                                 mgmt, len, signal, GFP_ATOMIC);
76
77         if (!bss)
78                 return NULL;
79
80         bss->cbss.free_priv = ieee80211_rx_bss_free;
81
82         /* save the ERP value so that it is available at association time */
83         if (elems->erp_info && elems->erp_info_len >= 1) {
84                 bss->erp_value = elems->erp_info[0];
85                 bss->has_erp_value = 1;
86         }
87
88         if (elems->tim) {
89                 struct ieee80211_tim_ie *tim_ie =
90                         (struct ieee80211_tim_ie *)elems->tim;
91                 bss->dtim_period = tim_ie->dtim_period;
92         }
93
94         /* set default value for buggy APs */
95         if (!elems->tim || bss->dtim_period == 0)
96                 bss->dtim_period = 1;
97
98         bss->supp_rates_len = 0;
99         if (elems->supp_rates) {
100                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
101                 if (clen > elems->supp_rates_len)
102                         clen = elems->supp_rates_len;
103                 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
104                        clen);
105                 bss->supp_rates_len += clen;
106         }
107         if (elems->ext_supp_rates) {
108                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
109                 if (clen > elems->ext_supp_rates_len)
110                         clen = elems->ext_supp_rates_len;
111                 memcpy(&bss->supp_rates[bss->supp_rates_len],
112                        elems->ext_supp_rates, clen);
113                 bss->supp_rates_len += clen;
114         }
115
116         bss->wmm_used = elems->wmm_param || elems->wmm_info;
117
118         if (!beacon)
119                 bss->last_probe_resp = jiffies;
120
121         return bss;
122 }
123
124 ieee80211_rx_result
125 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
126 {
127         struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
128         struct ieee80211_mgmt *mgmt;
129         struct ieee80211_bss *bss;
130         u8 *elements;
131         struct ieee80211_channel *channel;
132         size_t baselen;
133         int freq;
134         __le16 fc;
135         bool presp, beacon = false;
136         struct ieee802_11_elems elems;
137
138         if (skb->len < 2)
139                 return RX_DROP_UNUSABLE;
140
141         mgmt = (struct ieee80211_mgmt *) skb->data;
142         fc = mgmt->frame_control;
143
144         if (ieee80211_is_ctl(fc))
145                 return RX_CONTINUE;
146
147         if (skb->len < 24)
148                 return RX_DROP_MONITOR;
149
150         presp = ieee80211_is_probe_resp(fc);
151         if (presp) {
152                 /* ignore ProbeResp to foreign address */
153                 if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
154                         return RX_DROP_MONITOR;
155
156                 presp = true;
157                 elements = mgmt->u.probe_resp.variable;
158                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
159         } else {
160                 beacon = ieee80211_is_beacon(fc);
161                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
162                 elements = mgmt->u.beacon.variable;
163         }
164
165         if (!presp && !beacon)
166                 return RX_CONTINUE;
167
168         if (baselen > skb->len)
169                 return RX_DROP_MONITOR;
170
171         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
172
173         if (elems.ds_params && elems.ds_params_len == 1)
174                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
175         else
176                 freq = rx_status->freq;
177
178         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
179
180         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
181                 return RX_DROP_MONITOR;
182
183         bss = ieee80211_bss_info_update(sdata->local, rx_status,
184                                         mgmt, skb->len, &elems,
185                                         channel, beacon);
186         if (bss)
187                 ieee80211_rx_bss_put(sdata->local, bss);
188
189         dev_kfree_skb(skb);
190         return RX_QUEUED;
191 }
192
193 /*
194  * inform AP that we will go to sleep so that it will buffer the frames
195  * while we scan
196  */
197 static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata)
198 {
199         struct ieee80211_local *local = sdata->local;
200         bool ps = false;
201
202         /* FIXME: what to do when local->pspolling is true? */
203
204         del_timer_sync(&local->dynamic_ps_timer);
205         cancel_work_sync(&local->dynamic_ps_enable_work);
206
207         if (local->hw.conf.flags & IEEE80211_CONF_PS) {
208                 ps = true;
209                 local->hw.conf.flags &= ~IEEE80211_CONF_PS;
210                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
211         }
212
213         if (!ps || !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
214                 /*
215                  * If power save was enabled, no need to send a nullfunc
216                  * frame because AP knows that we are sleeping. But if the
217                  * hardware is creating the nullfunc frame for power save
218                  * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
219                  * enabled) and power save was enabled, the firmware just
220                  * sent a null frame with power save disabled. So we need
221                  * to send a new nullfunc frame to inform the AP that we
222                  * are again sleeping.
223                  */
224                 ieee80211_send_nullfunc(local, sdata, 1);
225 }
226
227 /* inform AP that we are awake again, unless power save is enabled */
228 static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
229 {
230         struct ieee80211_local *local = sdata->local;
231
232         if (!local->ps_sdata)
233                 ieee80211_send_nullfunc(local, sdata, 0);
234         else {
235                 /*
236                  * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
237                  * will send a nullfunc frame with the powersave bit set
238                  * even though the AP already knows that we are sleeping.
239                  * This could be avoided by sending a null frame with power
240                  * save bit disabled before enabling the power save, but
241                  * this doesn't gain anything.
242                  *
243                  * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
244                  * to send a nullfunc frame because AP already knows that
245                  * we are sleeping, let's just enable power save mode in
246                  * hardware.
247                  */
248                 local->hw.conf.flags |= IEEE80211_CONF_PS;
249                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
250         }
251 }
252
253 static void ieee80211_restore_scan_ies(struct ieee80211_local *local)
254 {
255         kfree(local->scan_req->ie);
256         local->scan_req->ie = local->orig_ies;
257         local->scan_req->ie_len = local->orig_ies_len;
258 }
259
260 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
261 {
262         struct ieee80211_local *local = hw_to_local(hw);
263         struct ieee80211_sub_if_data *sdata;
264         bool was_hw_scan;
265
266         mutex_lock(&local->scan_mtx);
267
268         if (WARN_ON(!local->scanning)) {
269                 mutex_unlock(&local->scan_mtx);
270                 return;
271         }
272
273         if (WARN_ON(!local->scan_req)) {
274                 mutex_unlock(&local->scan_mtx);
275                 return;
276         }
277
278         if (test_bit(SCAN_HW_SCANNING, &local->scanning))
279                 ieee80211_restore_scan_ies(local);
280
281         if (local->scan_req != &local->int_scan_req)
282                 cfg80211_scan_done(local->scan_req, aborted);
283         local->scan_req = NULL;
284
285         was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
286         local->scanning = 0;
287         local->scan_channel = NULL;
288
289         /* we only have to protect scan_req and hw/sw scan */
290         mutex_unlock(&local->scan_mtx);
291
292         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
293         if (was_hw_scan)
294                 goto done;
295
296         spin_lock_bh(&local->filter_lock);
297         local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
298         drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
299                              &local->filter_flags,
300                              local->mc_count,
301                              local->mc_list);
302         spin_unlock_bh(&local->filter_lock);
303
304         drv_sw_scan_complete(local);
305
306         mutex_lock(&local->iflist_mtx);
307         list_for_each_entry(sdata, &local->interfaces, list) {
308                 if (!netif_running(sdata->dev))
309                         continue;
310
311                 /* Tell AP we're back */
312                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
313                         if (sdata->u.mgd.associated) {
314                                 ieee80211_scan_ps_disable(sdata);
315                                 netif_tx_wake_all_queues(sdata->dev);
316                         }
317                 } else
318                         netif_tx_wake_all_queues(sdata->dev);
319
320                 /* re-enable beaconing */
321                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
322                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
323                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
324                         ieee80211_bss_info_change_notify(
325                                 sdata, BSS_CHANGED_BEACON_ENABLED);
326         }
327         mutex_unlock(&local->iflist_mtx);
328
329  done:
330         ieee80211_recalc_idle(local);
331         ieee80211_mlme_notify_scan_completed(local);
332         ieee80211_ibss_notify_scan_completed(local);
333         ieee80211_mesh_notify_scan_completed(local);
334 }
335 EXPORT_SYMBOL(ieee80211_scan_completed);
336
337 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
338 {
339         struct ieee80211_sub_if_data *sdata;
340
341         /*
342          * Hardware/driver doesn't support hw_scan, so use software
343          * scanning instead. First send a nullfunc frame with power save
344          * bit on so that AP will buffer the frames for us while we are not
345          * listening, then send probe requests to each channel and wait for
346          * the responses. After all channels are scanned, tune back to the
347          * original channel and send a nullfunc frame with power save bit
348          * off to trigger the AP to send us all the buffered frames.
349          *
350          * Note that while local->sw_scanning is true everything else but
351          * nullfunc frames and probe requests will be dropped in
352          * ieee80211_tx_h_check_assoc().
353          */
354         drv_sw_scan_start(local);
355
356         mutex_lock(&local->iflist_mtx);
357         list_for_each_entry(sdata, &local->interfaces, list) {
358                 if (!netif_running(sdata->dev))
359                         continue;
360
361                 /* disable beaconing */
362                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
363                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
364                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
365                         ieee80211_bss_info_change_notify(
366                                 sdata, BSS_CHANGED_BEACON_ENABLED);
367
368                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
369                         if (sdata->u.mgd.associated) {
370                                 netif_tx_stop_all_queues(sdata->dev);
371                                 ieee80211_scan_ps_enable(sdata);
372                         }
373                 } else
374                         netif_tx_stop_all_queues(sdata->dev);
375         }
376         mutex_unlock(&local->iflist_mtx);
377
378         local->scan_state = SCAN_DECISION;
379         local->scan_channel_idx = 0;
380
381         spin_lock_bh(&local->filter_lock);
382         local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
383         drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
384                              &local->filter_flags,
385                              local->mc_count,
386                              local->mc_list);
387         spin_unlock_bh(&local->filter_lock);
388
389         /* TODO: start scan as soon as all nullfunc frames are ACKed */
390         queue_delayed_work(local->hw.workqueue, &local->scan_work,
391                            IEEE80211_CHANNEL_TIME);
392
393         return 0;
394 }
395
396
397 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
398                                   struct cfg80211_scan_request *req)
399 {
400         struct ieee80211_local *local = sdata->local;
401         struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
402         int rc;
403
404         if (local->scan_req)
405                 return -EBUSY;
406
407         if (local->ops->hw_scan) {
408                 u8 *ies;
409                 int ielen;
410
411                 ies = kmalloc(2 + IEEE80211_MAX_SSID_LEN +
412                               local->scan_ies_len + req->ie_len, GFP_KERNEL);
413                 if (!ies)
414                         return -ENOMEM;
415
416                 ielen = ieee80211_build_preq_ies(local, ies,
417                                                  req->ie, req->ie_len);
418                 local->orig_ies = req->ie;
419                 local->orig_ies_len = req->ie_len;
420                 req->ie = ies;
421                 req->ie_len = ielen;
422         }
423
424         local->scan_req = req;
425         local->scan_sdata = sdata;
426
427         if (req != &local->int_scan_req &&
428             sdata->vif.type == NL80211_IFTYPE_STATION &&
429             !list_empty(&ifmgd->work_list)) {
430                 /* actually wait for the work it's doing to finish/time out */
431                 set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request);
432                 return 0;
433         }
434
435         if (local->ops->hw_scan)
436                 __set_bit(SCAN_HW_SCANNING, &local->scanning);
437         else
438                 __set_bit(SCAN_SW_SCANNING, &local->scanning);
439         /*
440          * Kicking off the scan need not be protected,
441          * only the scan variable stuff, since now
442          * local->scan_req is assigned and other callers
443          * will abort their scan attempts.
444          *
445          * This avoids getting a scan_mtx -> iflist_mtx
446          * dependency, so that the scan completed calls
447          * have more locking freedom.
448          */
449
450         ieee80211_recalc_idle(local);
451         mutex_unlock(&local->scan_mtx);
452
453         if (local->ops->hw_scan)
454                 rc = drv_hw_scan(local, local->scan_req);
455         else
456                 rc = ieee80211_start_sw_scan(local);
457
458         mutex_lock(&local->scan_mtx);
459
460         if (rc) {
461                 if (local->ops->hw_scan)
462                         ieee80211_restore_scan_ies(local);
463                 local->scanning = 0;
464
465                 ieee80211_recalc_idle(local);
466
467                 local->scan_req = NULL;
468                 local->scan_sdata = NULL;
469         }
470
471         return rc;
472 }
473
474 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
475                                          unsigned long *next_delay)
476 {
477         /* if no more bands/channels left, complete scan */
478         if (local->scan_channel_idx >= local->scan_req->n_channels) {
479                 ieee80211_scan_completed(&local->hw, false);
480                 return 1;
481         }
482
483         *next_delay = 0;
484         local->scan_state = SCAN_SET_CHANNEL;
485         return 0;
486 }
487
488 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
489                                              unsigned long *next_delay)
490 {
491         int skip;
492         struct ieee80211_channel *chan;
493         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
494
495         skip = 0;
496         chan = local->scan_req->channels[local->scan_channel_idx];
497
498         if (chan->flags & IEEE80211_CHAN_DISABLED ||
499             (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
500              chan->flags & IEEE80211_CHAN_NO_IBSS))
501                 skip = 1;
502
503         if (!skip) {
504                 local->scan_channel = chan;
505                 if (ieee80211_hw_config(local,
506                                         IEEE80211_CONF_CHANGE_CHANNEL))
507                         skip = 1;
508         }
509
510         /* advance state machine to next channel/band */
511         local->scan_channel_idx++;
512
513         if (skip)
514                 return;
515
516         /*
517          * Probe delay is used to update the NAV, cf. 11.1.3.2.2
518          * (which unfortunately doesn't say _why_ step a) is done,
519          * but it waits for the probe delay or until a frame is
520          * received - and the received frame would update the NAV).
521          * For now, we do not support waiting until a frame is
522          * received.
523          *
524          * In any case, it is not necessary for a passive scan.
525          */
526         if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
527             !local->scan_req->n_ssids) {
528                 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
529                 local->scan_state = SCAN_DECISION;
530                 return;
531         }
532
533         /* active scan, send probes */
534         *next_delay = IEEE80211_PROBE_DELAY;
535         local->scan_state = SCAN_SEND_PROBE;
536 }
537
538 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
539                                             unsigned long *next_delay)
540 {
541         int i;
542         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
543
544         for (i = 0; i < local->scan_req->n_ssids; i++)
545                 ieee80211_send_probe_req(
546                         sdata, NULL,
547                         local->scan_req->ssids[i].ssid,
548                         local->scan_req->ssids[i].ssid_len,
549                         local->scan_req->ie, local->scan_req->ie_len);
550
551         /*
552          * After sending probe requests, wait for probe responses
553          * on the channel.
554          */
555         *next_delay = IEEE80211_CHANNEL_TIME;
556         local->scan_state = SCAN_DECISION;
557 }
558
559 void ieee80211_scan_work(struct work_struct *work)
560 {
561         struct ieee80211_local *local =
562                 container_of(work, struct ieee80211_local, scan_work.work);
563         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
564         unsigned long next_delay = 0;
565
566         mutex_lock(&local->scan_mtx);
567         if (!sdata || !local->scan_req) {
568                 mutex_unlock(&local->scan_mtx);
569                 return;
570         }
571
572         if (local->scan_req && !local->scanning) {
573                 struct cfg80211_scan_request *req = local->scan_req;
574                 int rc;
575
576                 local->scan_req = NULL;
577
578                 rc = __ieee80211_start_scan(sdata, req);
579                 mutex_unlock(&local->scan_mtx);
580
581                 if (rc)
582                         ieee80211_scan_completed(&local->hw, true);
583                 return;
584         }
585
586         mutex_unlock(&local->scan_mtx);
587
588         /*
589          * Avoid re-scheduling when the sdata is going away.
590          */
591         if (!netif_running(sdata->dev)) {
592                 ieee80211_scan_completed(&local->hw, true);
593                 return;
594         }
595
596         /*
597          * as long as no delay is required advance immediately
598          * without scheduling a new work
599          */
600         do {
601                 switch (local->scan_state) {
602                 case SCAN_DECISION:
603                         if (ieee80211_scan_state_decision(local, &next_delay))
604                                 return;
605                         break;
606                 case SCAN_SET_CHANNEL:
607                         ieee80211_scan_state_set_channel(local, &next_delay);
608                         break;
609                 case SCAN_SEND_PROBE:
610                         ieee80211_scan_state_send_probe(local, &next_delay);
611                         break;
612                 }
613         } while (next_delay == 0);
614
615         queue_delayed_work(local->hw.workqueue, &local->scan_work,
616                            next_delay);
617 }
618
619 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
620                            struct cfg80211_scan_request *req)
621 {
622         int res;
623
624         mutex_lock(&sdata->local->scan_mtx);
625         res = __ieee80211_start_scan(sdata, req);
626         mutex_unlock(&sdata->local->scan_mtx);
627
628         return res;
629 }
630
631 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
632                                     const u8 *ssid, u8 ssid_len)
633 {
634         struct ieee80211_local *local = sdata->local;
635         int ret = -EBUSY;
636
637         mutex_lock(&local->scan_mtx);
638
639         /* busy scanning */
640         if (local->scan_req)
641                 goto unlock;
642
643         memcpy(local->int_scan_req.ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
644         local->int_scan_req.ssids[0].ssid_len = ssid_len;
645
646         ret = __ieee80211_start_scan(sdata, &sdata->local->int_scan_req);
647  unlock:
648         mutex_unlock(&local->scan_mtx);
649         return ret;
650 }
651
652 void ieee80211_scan_cancel(struct ieee80211_local *local)
653 {
654         bool swscan;
655
656         cancel_delayed_work_sync(&local->scan_work);
657
658         /*
659          * Only call this function when a scan can't be
660          * queued -- mostly at suspend under RTNL.
661          */
662         mutex_lock(&local->scan_mtx);
663         swscan = test_bit(SCAN_SW_SCANNING, &local->scanning);
664         mutex_unlock(&local->scan_mtx);
665
666         if (swscan)
667                 ieee80211_scan_completed(&local->hw, true);
668 }