mac80211: tell driver when idle
[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 / 5)
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 void ieee80211_rx_bss_remove(struct ieee80211_sub_if_data *sdata, u8 *bssid,
125                              int freq, u8 *ssid, u8 ssid_len)
126 {
127         struct ieee80211_bss *bss;
128         struct ieee80211_local *local = sdata->local;
129
130         bss = ieee80211_rx_bss_get(local, bssid, freq, ssid, ssid_len);
131         if (bss) {
132                 cfg80211_unlink_bss(local->hw.wiphy, (void *)bss);
133                 ieee80211_rx_bss_put(local, bss);
134         }
135 }
136
137 ieee80211_rx_result
138 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb,
139                   struct ieee80211_rx_status *rx_status)
140 {
141         struct ieee80211_mgmt *mgmt;
142         struct ieee80211_bss *bss;
143         u8 *elements;
144         struct ieee80211_channel *channel;
145         size_t baselen;
146         int freq;
147         __le16 fc;
148         bool presp, beacon = false;
149         struct ieee802_11_elems elems;
150
151         if (skb->len < 2)
152                 return RX_DROP_UNUSABLE;
153
154         mgmt = (struct ieee80211_mgmt *) skb->data;
155         fc = mgmt->frame_control;
156
157         if (ieee80211_is_ctl(fc))
158                 return RX_CONTINUE;
159
160         if (skb->len < 24)
161                 return RX_DROP_MONITOR;
162
163         presp = ieee80211_is_probe_resp(fc);
164         if (presp) {
165                 /* ignore ProbeResp to foreign address */
166                 if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
167                         return RX_DROP_MONITOR;
168
169                 presp = true;
170                 elements = mgmt->u.probe_resp.variable;
171                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
172         } else {
173                 beacon = ieee80211_is_beacon(fc);
174                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
175                 elements = mgmt->u.beacon.variable;
176         }
177
178         if (!presp && !beacon)
179                 return RX_CONTINUE;
180
181         if (baselen > skb->len)
182                 return RX_DROP_MONITOR;
183
184         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
185
186         if (elems.ds_params && elems.ds_params_len == 1)
187                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
188         else
189                 freq = rx_status->freq;
190
191         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
192
193         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
194                 return RX_DROP_MONITOR;
195
196         bss = ieee80211_bss_info_update(sdata->local, rx_status,
197                                         mgmt, skb->len, &elems,
198                                         channel, beacon);
199         if (bss)
200                 ieee80211_rx_bss_put(sdata->local, bss);
201
202         dev_kfree_skb(skb);
203         return RX_QUEUED;
204 }
205
206 /*
207  * inform AP that we will go to sleep so that it will buffer the frames
208  * while we scan
209  */
210 static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata)
211 {
212         struct ieee80211_local *local = sdata->local;
213         bool ps = false;
214
215         /* FIXME: what to do when local->pspolling is true? */
216
217         del_timer_sync(&local->dynamic_ps_timer);
218         cancel_work_sync(&local->dynamic_ps_enable_work);
219
220         if (local->hw.conf.flags & IEEE80211_CONF_PS) {
221                 ps = true;
222                 local->hw.conf.flags &= ~IEEE80211_CONF_PS;
223                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
224         }
225
226         if (!ps || !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
227                 /*
228                  * If power save was enabled, no need to send a nullfunc
229                  * frame because AP knows that we are sleeping. But if the
230                  * hardware is creating the nullfunc frame for power save
231                  * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
232                  * enabled) and power save was enabled, the firmware just
233                  * sent a null frame with power save disabled. So we need
234                  * to send a new nullfunc frame to inform the AP that we
235                  * are again sleeping.
236                  */
237                 ieee80211_send_nullfunc(local, sdata, 1);
238 }
239
240 /* inform AP that we are awake again, unless power save is enabled */
241 static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
242 {
243         struct ieee80211_local *local = sdata->local;
244
245         if (!local->ps_sdata)
246                 ieee80211_send_nullfunc(local, sdata, 0);
247         else {
248                 /*
249                  * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
250                  * will send a nullfunc frame with the powersave bit set
251                  * even though the AP already knows that we are sleeping.
252                  * This could be avoided by sending a null frame with power
253                  * save bit disabled before enabling the power save, but
254                  * this doesn't gain anything.
255                  *
256                  * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
257                  * to send a nullfunc frame because AP already knows that
258                  * we are sleeping, let's just enable power save mode in
259                  * hardware.
260                  */
261                 local->hw.conf.flags |= IEEE80211_CONF_PS;
262                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
263         }
264 }
265
266 static void ieee80211_restore_scan_ies(struct ieee80211_local *local)
267 {
268         kfree(local->scan_req->ie);
269         local->scan_req->ie = local->orig_ies;
270         local->scan_req->ie_len = local->orig_ies_len;
271 }
272
273 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
274 {
275         struct ieee80211_local *local = hw_to_local(hw);
276         struct ieee80211_sub_if_data *sdata;
277         bool was_hw_scan;
278
279         mutex_lock(&local->scan_mtx);
280
281         if (WARN_ON(!local->hw_scanning && !local->sw_scanning)) {
282                 mutex_unlock(&local->scan_mtx);
283                 return;
284         }
285
286         if (WARN_ON(!local->scan_req)) {
287                 mutex_unlock(&local->scan_mtx);
288                 return;
289         }
290
291         if (local->hw_scanning)
292                 ieee80211_restore_scan_ies(local);
293
294         if (local->scan_req != &local->int_scan_req)
295                 cfg80211_scan_done(local->scan_req, aborted);
296         local->scan_req = NULL;
297
298         was_hw_scan = local->hw_scanning;
299         local->hw_scanning = false;
300         local->sw_scanning = false;
301
302         /* we only have to protect scan_req and hw/sw scan */
303         mutex_unlock(&local->scan_mtx);
304
305         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
306         if (was_hw_scan)
307                 goto done;
308
309         netif_tx_lock_bh(local->mdev);
310         netif_addr_lock(local->mdev);
311         local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
312         drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
313                              &local->filter_flags,
314                              local->mdev->mc_count,
315                              local->mdev->mc_list);
316
317         netif_addr_unlock(local->mdev);
318         netif_tx_unlock_bh(local->mdev);
319
320         drv_sw_scan_complete(local);
321
322         mutex_lock(&local->iflist_mtx);
323         list_for_each_entry(sdata, &local->interfaces, list) {
324                 if (!netif_running(sdata->dev))
325                         continue;
326
327                 /* Tell AP we're back */
328                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
329                         if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) {
330                                 ieee80211_scan_ps_disable(sdata);
331                                 netif_tx_wake_all_queues(sdata->dev);
332                         }
333                 } else
334                         netif_tx_wake_all_queues(sdata->dev);
335
336                 /* re-enable beaconing */
337                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
338                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
339                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
340                         ieee80211_bss_info_change_notify(
341                                 sdata, BSS_CHANGED_BEACON_ENABLED);
342         }
343         mutex_unlock(&local->iflist_mtx);
344
345  done:
346         ieee80211_recalc_idle(local);
347         ieee80211_mlme_notify_scan_completed(local);
348         ieee80211_ibss_notify_scan_completed(local);
349         ieee80211_mesh_notify_scan_completed(local);
350 }
351 EXPORT_SYMBOL(ieee80211_scan_completed);
352
353 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
354 {
355         struct ieee80211_sub_if_data *sdata;
356
357         /*
358          * Hardware/driver doesn't support hw_scan, so use software
359          * scanning instead. First send a nullfunc frame with power save
360          * bit on so that AP will buffer the frames for us while we are not
361          * listening, then send probe requests to each channel and wait for
362          * the responses. After all channels are scanned, tune back to the
363          * original channel and send a nullfunc frame with power save bit
364          * off to trigger the AP to send us all the buffered frames.
365          *
366          * Note that while local->sw_scanning is true everything else but
367          * nullfunc frames and probe requests will be dropped in
368          * ieee80211_tx_h_check_assoc().
369          */
370         drv_sw_scan_start(local);
371
372         mutex_lock(&local->iflist_mtx);
373         list_for_each_entry(sdata, &local->interfaces, list) {
374                 if (!netif_running(sdata->dev))
375                         continue;
376
377                 /* disable beaconing */
378                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
379                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
380                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
381                         ieee80211_bss_info_change_notify(
382                                 sdata, BSS_CHANGED_BEACON_ENABLED);
383
384                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
385                         if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) {
386                                 netif_tx_stop_all_queues(sdata->dev);
387                                 ieee80211_scan_ps_enable(sdata);
388                         }
389                 } else
390                         netif_tx_stop_all_queues(sdata->dev);
391         }
392         mutex_unlock(&local->iflist_mtx);
393
394         local->scan_state = SCAN_SET_CHANNEL;
395         local->scan_channel_idx = 0;
396
397         netif_addr_lock_bh(local->mdev);
398         local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
399         drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
400                              &local->filter_flags,
401                              local->mdev->mc_count,
402                              local->mdev->mc_list);
403         netif_addr_unlock_bh(local->mdev);
404
405         /* TODO: start scan as soon as all nullfunc frames are ACKed */
406         queue_delayed_work(local->hw.workqueue, &local->scan_work,
407                            IEEE80211_CHANNEL_TIME);
408
409         return 0;
410 }
411
412
413 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
414                                   struct cfg80211_scan_request *req)
415 {
416         struct ieee80211_local *local = sdata->local;
417         struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
418         int rc;
419
420         if (local->scan_req)
421                 return -EBUSY;
422
423         if (local->ops->hw_scan) {
424                 u8 *ies;
425                 int ielen;
426
427                 ies = kmalloc(2 + IEEE80211_MAX_SSID_LEN +
428                               local->scan_ies_len + req->ie_len, GFP_KERNEL);
429                 if (!ies)
430                         return -ENOMEM;
431
432                 ielen = ieee80211_build_preq_ies(local, ies,
433                                                  req->ie, req->ie_len);
434                 local->orig_ies = req->ie;
435                 local->orig_ies_len = req->ie_len;
436                 req->ie = ies;
437                 req->ie_len = ielen;
438         }
439
440         local->scan_req = req;
441         local->scan_sdata = sdata;
442
443         if (req != &local->int_scan_req &&
444             sdata->vif.type == NL80211_IFTYPE_STATION &&
445             (ifmgd->state == IEEE80211_STA_MLME_DIRECT_PROBE ||
446              ifmgd->state == IEEE80211_STA_MLME_AUTHENTICATE ||
447              ifmgd->state == IEEE80211_STA_MLME_ASSOCIATE)) {
448                 /* actually wait for the assoc to finish/time out */
449                 set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request);
450                 return 0;
451         }
452
453         if (local->ops->hw_scan)
454                 local->hw_scanning = true;
455         else
456                 local->sw_scanning = true;
457         /*
458          * Kicking off the scan need not be protected,
459          * only the scan variable stuff, since now
460          * local->scan_req is assigned and other callers
461          * will abort their scan attempts.
462          *
463          * This avoids getting a scan_mtx -> iflist_mtx
464          * dependency, so that the scan completed calls
465          * have more locking freedom.
466          */
467
468         ieee80211_recalc_idle(local);
469         mutex_unlock(&local->scan_mtx);
470
471         if (local->ops->hw_scan)
472                 rc = drv_hw_scan(local, local->scan_req);
473         else
474                 rc = ieee80211_start_sw_scan(local);
475
476         mutex_lock(&local->scan_mtx);
477
478         if (rc) {
479                 if (local->ops->hw_scan) {
480                         local->hw_scanning = false;
481                         ieee80211_restore_scan_ies(local);
482                 } else
483                         local->sw_scanning = false;
484
485                 ieee80211_recalc_idle(local);
486
487                 local->scan_req = NULL;
488                 local->scan_sdata = NULL;
489         }
490
491         return rc;
492 }
493
494 void ieee80211_scan_work(struct work_struct *work)
495 {
496         struct ieee80211_local *local =
497                 container_of(work, struct ieee80211_local, scan_work.work);
498         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
499         struct ieee80211_channel *chan;
500         int skip, i;
501         unsigned long next_delay = 0;
502
503         mutex_lock(&local->scan_mtx);
504         if (!sdata || !local->scan_req) {
505                 mutex_unlock(&local->scan_mtx);
506                 return;
507         }
508
509         if (local->scan_req && !(local->sw_scanning || local->hw_scanning)) {
510                 struct cfg80211_scan_request *req = local->scan_req;
511                 int rc;
512
513                 local->scan_req = NULL;
514
515                 rc = __ieee80211_start_scan(sdata, req);
516                 mutex_unlock(&local->scan_mtx);
517
518                 if (rc)
519                         ieee80211_scan_completed(&local->hw, true);
520                 return;
521         }
522
523         mutex_unlock(&local->scan_mtx);
524
525         /*
526          * Avoid re-scheduling when the sdata is going away.
527          */
528         if (!netif_running(sdata->dev)) {
529                 ieee80211_scan_completed(&local->hw, true);
530                 return;
531         }
532
533         switch (local->scan_state) {
534         case SCAN_SET_CHANNEL:
535                 /* if no more bands/channels left, complete scan */
536                 if (local->scan_channel_idx >= local->scan_req->n_channels) {
537                         ieee80211_scan_completed(&local->hw, false);
538                         return;
539                 }
540                 skip = 0;
541                 chan = local->scan_req->channels[local->scan_channel_idx];
542
543                 if (chan->flags & IEEE80211_CHAN_DISABLED ||
544                     (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
545                      chan->flags & IEEE80211_CHAN_NO_IBSS))
546                         skip = 1;
547
548                 if (!skip) {
549                         local->scan_channel = chan;
550                         if (ieee80211_hw_config(local,
551                                                 IEEE80211_CONF_CHANGE_CHANNEL))
552                                 skip = 1;
553                 }
554
555                 /* advance state machine to next channel/band */
556                 local->scan_channel_idx++;
557
558                 if (skip)
559                         break;
560
561                 next_delay = IEEE80211_PROBE_DELAY +
562                              usecs_to_jiffies(local->hw.channel_change_time);
563                 local->scan_state = SCAN_SEND_PROBE;
564                 break;
565         case SCAN_SEND_PROBE:
566                 next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
567                 local->scan_state = SCAN_SET_CHANNEL;
568
569                 if (local->scan_channel->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
570                     !local->scan_req->n_ssids)
571                         break;
572                 for (i = 0; i < local->scan_req->n_ssids; i++)
573                         ieee80211_send_probe_req(
574                                 sdata, NULL,
575                                 local->scan_req->ssids[i].ssid,
576                                 local->scan_req->ssids[i].ssid_len,
577                                 local->scan_req->ie, local->scan_req->ie_len);
578                 next_delay = IEEE80211_CHANNEL_TIME;
579                 break;
580         }
581
582         queue_delayed_work(local->hw.workqueue, &local->scan_work,
583                            next_delay);
584 }
585
586 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
587                            struct cfg80211_scan_request *req)
588 {
589         int res;
590
591         mutex_lock(&sdata->local->scan_mtx);
592         res = __ieee80211_start_scan(sdata, req);
593         mutex_unlock(&sdata->local->scan_mtx);
594
595         return res;
596 }
597
598 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
599                                     const u8 *ssid, u8 ssid_len)
600 {
601         struct ieee80211_local *local = sdata->local;
602         int ret = -EBUSY;
603
604         mutex_lock(&local->scan_mtx);
605
606         /* busy scanning */
607         if (local->scan_req)
608                 goto unlock;
609
610         memcpy(local->int_scan_req.ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
611         local->int_scan_req.ssids[0].ssid_len = ssid_len;
612
613         ret = __ieee80211_start_scan(sdata, &sdata->local->int_scan_req);
614  unlock:
615         mutex_unlock(&local->scan_mtx);
616         return ret;
617 }