mac80211: improve powersave implementation
[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 "mesh.h"
25
26 #define IEEE80211_PROBE_DELAY (HZ / 33)
27 #define IEEE80211_CHANNEL_TIME (HZ / 33)
28 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 5)
29
30 struct ieee80211_bss *
31 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
32                      u8 *ssid, u8 ssid_len)
33 {
34         return (void *)cfg80211_get_bss(local->hw.wiphy,
35                                         ieee80211_get_channel(local->hw.wiphy,
36                                                               freq),
37                                         bssid, ssid, ssid_len,
38                                         0, 0);
39 }
40
41 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
42 {
43         struct ieee80211_bss *bss = (void *)cbss;
44
45         kfree(bss_mesh_id(bss));
46         kfree(bss_mesh_cfg(bss));
47 }
48
49 void ieee80211_rx_bss_put(struct ieee80211_local *local,
50                           struct ieee80211_bss *bss)
51 {
52         cfg80211_put_bss((struct cfg80211_bss *)bss);
53 }
54
55 struct ieee80211_bss *
56 ieee80211_bss_info_update(struct ieee80211_local *local,
57                           struct ieee80211_rx_status *rx_status,
58                           struct ieee80211_mgmt *mgmt,
59                           size_t len,
60                           struct ieee802_11_elems *elems,
61                           struct ieee80211_channel *channel,
62                           bool beacon)
63 {
64         struct ieee80211_bss *bss;
65         int clen;
66         s32 signal = 0;
67
68         if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
69                 signal = rx_status->signal * 100;
70         else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
71                 signal = (rx_status->signal * 100) / local->hw.max_signal;
72
73         bss = (void *)cfg80211_inform_bss_frame(local->hw.wiphy, channel,
74                                                 mgmt, len, signal, GFP_ATOMIC);
75
76         if (!bss)
77                 return NULL;
78
79         bss->cbss.free_priv = ieee80211_rx_bss_free;
80
81         /* save the ERP value so that it is available at association time */
82         if (elems->erp_info && elems->erp_info_len >= 1) {
83                 bss->erp_value = elems->erp_info[0];
84                 bss->has_erp_value = 1;
85         }
86
87         if (elems->tim) {
88                 struct ieee80211_tim_ie *tim_ie =
89                         (struct ieee80211_tim_ie *)elems->tim;
90                 bss->dtim_period = tim_ie->dtim_period;
91         }
92
93         /* set default value for buggy APs */
94         if (!elems->tim || bss->dtim_period == 0)
95                 bss->dtim_period = 1;
96
97         bss->supp_rates_len = 0;
98         if (elems->supp_rates) {
99                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
100                 if (clen > elems->supp_rates_len)
101                         clen = elems->supp_rates_len;
102                 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
103                        clen);
104                 bss->supp_rates_len += clen;
105         }
106         if (elems->ext_supp_rates) {
107                 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
108                 if (clen > elems->ext_supp_rates_len)
109                         clen = elems->ext_supp_rates_len;
110                 memcpy(&bss->supp_rates[bss->supp_rates_len],
111                        elems->ext_supp_rates, clen);
112                 bss->supp_rates_len += clen;
113         }
114
115         bss->wmm_used = elems->wmm_param || elems->wmm_info;
116
117         if (!beacon)
118                 bss->last_probe_resp = jiffies;
119
120         return bss;
121 }
122
123 void ieee80211_rx_bss_remove(struct ieee80211_sub_if_data *sdata, u8 *bssid,
124                              int freq, u8 *ssid, u8 ssid_len)
125 {
126         struct ieee80211_bss *bss;
127         struct ieee80211_local *local = sdata->local;
128
129         bss = ieee80211_rx_bss_get(local, bssid, freq, ssid, ssid_len);
130         if (bss) {
131                 cfg80211_unlink_bss(local->hw.wiphy, (void *)bss);
132                 ieee80211_rx_bss_put(local, bss);
133         }
134 }
135
136 ieee80211_rx_result
137 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb,
138                   struct ieee80211_rx_status *rx_status)
139 {
140         struct ieee80211_mgmt *mgmt;
141         struct ieee80211_bss *bss;
142         u8 *elements;
143         struct ieee80211_channel *channel;
144         size_t baselen;
145         int freq;
146         __le16 fc;
147         bool presp, beacon = false;
148         struct ieee802_11_elems elems;
149
150         if (skb->len < 2)
151                 return RX_DROP_UNUSABLE;
152
153         mgmt = (struct ieee80211_mgmt *) skb->data;
154         fc = mgmt->frame_control;
155
156         if (ieee80211_is_ctl(fc))
157                 return RX_CONTINUE;
158
159         if (skb->len < 24)
160                 return RX_DROP_MONITOR;
161
162         presp = ieee80211_is_probe_resp(fc);
163         if (presp) {
164                 /* ignore ProbeResp to foreign address */
165                 if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
166                         return RX_DROP_MONITOR;
167
168                 presp = true;
169                 elements = mgmt->u.probe_resp.variable;
170                 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
171         } else {
172                 beacon = ieee80211_is_beacon(fc);
173                 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
174                 elements = mgmt->u.beacon.variable;
175         }
176
177         if (!presp && !beacon)
178                 return RX_CONTINUE;
179
180         if (baselen > skb->len)
181                 return RX_DROP_MONITOR;
182
183         ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
184
185         if (elems.ds_params && elems.ds_params_len == 1)
186                 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
187         else
188                 freq = rx_status->freq;
189
190         channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
191
192         if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
193                 return RX_DROP_MONITOR;
194
195         bss = ieee80211_bss_info_update(sdata->local, rx_status,
196                                         mgmt, skb->len, &elems,
197                                         channel, beacon);
198         if (bss)
199                 ieee80211_rx_bss_put(sdata->local, bss);
200
201         dev_kfree_skb(skb);
202         return RX_QUEUED;
203 }
204
205 void ieee80211_scan_failed(struct ieee80211_local *local)
206 {
207         if (WARN_ON(!local->scan_req))
208                 return;
209
210         /* notify cfg80211 about the failed scan */
211         if (local->scan_req != &local->int_scan_req)
212                 cfg80211_scan_done(local->scan_req, true);
213
214         local->scan_req = NULL;
215 }
216
217 /*
218  * inform AP that we will go to sleep so that it will buffer the frames
219  * while we scan
220  */
221 static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata)
222 {
223         struct ieee80211_local *local = sdata->local;
224         bool ps = false;
225
226         /* FIXME: what to do when local->pspolling is true? */
227
228         del_timer_sync(&local->dynamic_ps_timer);
229         cancel_work_sync(&local->dynamic_ps_enable_work);
230
231         if (local->hw.conf.flags & IEEE80211_CONF_PS) {
232                 ps = true;
233                 local->hw.conf.flags &= ~IEEE80211_CONF_PS;
234                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
235         }
236
237         if (!ps || !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
238                 /*
239                  * If power save was enabled, no need to send a nullfunc
240                  * frame because AP knows that we are sleeping. But if the
241                  * hardware is creating the nullfunc frame for power save
242                  * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
243                  * enabled) and power save was enabled, the firmware just
244                  * sent a null frame with power save disabled. So we need
245                  * to send a new nullfunc frame to inform the AP that we
246                  * are again sleeping.
247                  */
248                 ieee80211_send_nullfunc(local, sdata, 1);
249 }
250
251 /* inform AP that we are awake again, unless power save is enabled */
252 static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
253 {
254         struct ieee80211_local *local = sdata->local;
255
256         if (!local->ps_sdata)
257                 ieee80211_send_nullfunc(local, sdata, 0);
258         else {
259                 /*
260                  * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
261                  * will send a nullfunc frame with the powersave bit set
262                  * even though the AP already knows that we are sleeping.
263                  * This could be avoided by sending a null frame with power
264                  * save bit disabled before enabling the power save, but
265                  * this doesn't gain anything.
266                  *
267                  * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
268                  * to send a nullfunc frame because AP already knows that
269                  * we are sleeping, let's just enable power save mode in
270                  * hardware.
271                  */
272                 local->hw.conf.flags |= IEEE80211_CONF_PS;
273                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
274         }
275 }
276
277 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
278 {
279         struct ieee80211_local *local = hw_to_local(hw);
280         struct ieee80211_sub_if_data *sdata;
281
282         if (WARN_ON(!local->hw_scanning && !local->sw_scanning))
283                 return;
284
285         if (WARN_ON(!local->scan_req))
286                 return;
287
288         if (local->hw_scanning) {
289                 kfree(local->scan_req->ie);
290                 local->scan_req->ie = local->orig_ies;
291                 local->scan_req->ie_len = local->orig_ies_len;
292         }
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         local->last_scan_completed = jiffies;
299
300         if (local->hw_scanning) {
301                 local->hw_scanning = false;
302                 /*
303                  * Somebody might have requested channel change during scan
304                  * that we won't have acted upon, try now. ieee80211_hw_config
305                  * will set the flag based on actual changes.
306                  */
307                 ieee80211_hw_config(local, 0);
308                 goto done;
309         }
310
311         local->sw_scanning = false;
312         ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
313
314         netif_tx_lock_bh(local->mdev);
315         netif_addr_lock(local->mdev);
316         local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
317         local->ops->configure_filter(local_to_hw(local),
318                                      FIF_BCN_PRBRESP_PROMISC,
319                                      &local->filter_flags,
320                                      local->mdev->mc_count,
321                                      local->mdev->mc_list);
322
323         netif_addr_unlock(local->mdev);
324         netif_tx_unlock_bh(local->mdev);
325
326         if (local->ops->sw_scan_complete)
327                 local->ops->sw_scan_complete(local_to_hw(local));
328
329         mutex_lock(&local->iflist_mtx);
330         list_for_each_entry(sdata, &local->interfaces, list) {
331                 if (!netif_running(sdata->dev))
332                         continue;
333
334                 /* Tell AP we're back */
335                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
336                         if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) {
337                                 ieee80211_scan_ps_disable(sdata);
338                                 netif_tx_wake_all_queues(sdata->dev);
339                         }
340                 } else
341                         netif_tx_wake_all_queues(sdata->dev);
342
343                 /* re-enable beaconing */
344                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
345                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
346                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
347                         ieee80211_if_config(sdata,
348                                             IEEE80211_IFCC_BEACON_ENABLED);
349         }
350         mutex_unlock(&local->iflist_mtx);
351
352  done:
353         ieee80211_mlme_notify_scan_completed(local);
354         ieee80211_ibss_notify_scan_completed(local);
355         ieee80211_mesh_notify_scan_completed(local);
356 }
357 EXPORT_SYMBOL(ieee80211_scan_completed);
358
359 void ieee80211_scan_work(struct work_struct *work)
360 {
361         struct ieee80211_local *local =
362                 container_of(work, struct ieee80211_local, scan_work.work);
363         struct ieee80211_sub_if_data *sdata = local->scan_sdata;
364         struct ieee80211_channel *chan;
365         int skip, i;
366         unsigned long next_delay = 0;
367
368         /*
369          * Avoid re-scheduling when the sdata is going away.
370          */
371         if (!netif_running(sdata->dev))
372                 return;
373
374         switch (local->scan_state) {
375         case SCAN_SET_CHANNEL:
376                 /* if no more bands/channels left, complete scan */
377                 if (local->scan_channel_idx >= local->scan_req->n_channels) {
378                         ieee80211_scan_completed(local_to_hw(local), false);
379                         return;
380                 }
381                 skip = 0;
382                 chan = local->scan_req->channels[local->scan_channel_idx];
383
384                 if (chan->flags & IEEE80211_CHAN_DISABLED ||
385                     (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
386                      chan->flags & IEEE80211_CHAN_NO_IBSS))
387                         skip = 1;
388
389                 if (!skip) {
390                         local->scan_channel = chan;
391                         if (ieee80211_hw_config(local,
392                                                 IEEE80211_CONF_CHANGE_CHANNEL))
393                                 skip = 1;
394                 }
395
396                 /* advance state machine to next channel/band */
397                 local->scan_channel_idx++;
398
399                 if (skip)
400                         break;
401
402                 next_delay = IEEE80211_PROBE_DELAY +
403                              usecs_to_jiffies(local->hw.channel_change_time);
404                 local->scan_state = SCAN_SEND_PROBE;
405                 break;
406         case SCAN_SEND_PROBE:
407                 next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
408                 local->scan_state = SCAN_SET_CHANNEL;
409
410                 if (local->scan_channel->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
411                     !local->scan_req->n_ssids)
412                         break;
413                 for (i = 0; i < local->scan_req->n_ssids; i++)
414                         ieee80211_send_probe_req(
415                                 sdata, NULL,
416                                 local->scan_req->ssids[i].ssid,
417                                 local->scan_req->ssids[i].ssid_len,
418                                 local->scan_req->ie, local->scan_req->ie_len);
419                 next_delay = IEEE80211_CHANNEL_TIME;
420                 break;
421         }
422
423         queue_delayed_work(local->hw.workqueue, &local->scan_work,
424                            next_delay);
425 }
426
427
428 int ieee80211_start_scan(struct ieee80211_sub_if_data *scan_sdata,
429                          struct cfg80211_scan_request *req)
430 {
431         struct ieee80211_local *local = scan_sdata->local;
432         struct ieee80211_sub_if_data *sdata;
433
434         if (!req)
435                 return -EINVAL;
436
437         if (local->scan_req && local->scan_req != req)
438                 return -EBUSY;
439
440         local->scan_req = req;
441
442         /* MLME-SCAN.request (page 118)  page 144 (11.1.3.1)
443          * BSSType: INFRASTRUCTURE, INDEPENDENT, ANY_BSS
444          * BSSID: MACAddress
445          * SSID
446          * ScanType: ACTIVE, PASSIVE
447          * ProbeDelay: delay (in microseconds) to be used prior to transmitting
448          *    a Probe frame during active scanning
449          * ChannelList
450          * MinChannelTime (>= ProbeDelay), in TU
451          * MaxChannelTime: (>= MinChannelTime), in TU
452          */
453
454          /* MLME-SCAN.confirm
455           * BSSDescriptionSet
456           * ResultCode: SUCCESS, INVALID_PARAMETERS
457          */
458
459         if (local->sw_scanning || local->hw_scanning) {
460                 if (local->scan_sdata == scan_sdata)
461                         return 0;
462                 return -EBUSY;
463         }
464
465         if (local->ops->hw_scan) {
466                 u8 *ies;
467                 int rc, ielen;
468
469                 ies = kmalloc(2 + IEEE80211_MAX_SSID_LEN +
470                               local->scan_ies_len + req->ie_len, GFP_KERNEL);
471                 if (!ies)
472                         return -ENOMEM;
473
474                 ielen = ieee80211_build_preq_ies(local, ies,
475                                                  req->ie, req->ie_len);
476                 local->orig_ies = req->ie;
477                 local->orig_ies_len = req->ie_len;
478                 req->ie = ies;
479                 req->ie_len = ielen;
480
481                 local->hw_scanning = true;
482                 rc = local->ops->hw_scan(local_to_hw(local), req);
483                 if (rc) {
484                         local->hw_scanning = false;
485                         kfree(ies);
486                         req->ie_len = local->orig_ies_len;
487                         req->ie = local->orig_ies;
488                         return rc;
489                 }
490                 local->scan_sdata = scan_sdata;
491                 return 0;
492         }
493
494         /*
495          * Hardware/driver doesn't support hw_scan, so use software
496          * scanning instead. First send a nullfunc frame with power save
497          * bit on so that AP will buffer the frames for us while we are not
498          * listening, then send probe requests to each channel and wait for
499          * the responses. After all channels are scanned, tune back to the
500          * original channel and send a nullfunc frame with power save bit
501          * off to trigger the AP to send us all the buffered frames.
502          *
503          * Note that while local->sw_scanning is true everything else but
504          * nullfunc frames and probe requests will be dropped in
505          * ieee80211_tx_h_check_assoc().
506          */
507         local->sw_scanning = true;
508         if (local->ops->sw_scan_start)
509                 local->ops->sw_scan_start(local_to_hw(local));
510
511         mutex_lock(&local->iflist_mtx);
512         list_for_each_entry(sdata, &local->interfaces, list) {
513                 if (!netif_running(sdata->dev))
514                         continue;
515
516                 /* disable beaconing */
517                 if (sdata->vif.type == NL80211_IFTYPE_AP ||
518                     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
519                     sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
520                         ieee80211_if_config(sdata,
521                                             IEEE80211_IFCC_BEACON_ENABLED);
522
523                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
524                         if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) {
525                                 netif_tx_stop_all_queues(sdata->dev);
526                                 ieee80211_scan_ps_enable(sdata);
527                         }
528                 } else
529                         netif_tx_stop_all_queues(sdata->dev);
530         }
531         mutex_unlock(&local->iflist_mtx);
532
533         local->scan_state = SCAN_SET_CHANNEL;
534         local->scan_channel_idx = 0;
535         local->scan_sdata = scan_sdata;
536         local->scan_req = req;
537
538         netif_addr_lock_bh(local->mdev);
539         local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
540         local->ops->configure_filter(local_to_hw(local),
541                                      FIF_BCN_PRBRESP_PROMISC,
542                                      &local->filter_flags,
543                                      local->mdev->mc_count,
544                                      local->mdev->mc_list);
545         netif_addr_unlock_bh(local->mdev);
546
547         /* TODO: start scan as soon as all nullfunc frames are ACKed */
548         queue_delayed_work(local->hw.workqueue, &local->scan_work,
549                            IEEE80211_CHANNEL_TIME);
550
551         return 0;
552 }
553
554
555 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
556                            struct cfg80211_scan_request *req)
557 {
558         struct ieee80211_local *local = sdata->local;
559         struct ieee80211_if_managed *ifmgd;
560
561         if (!req)
562                 return -EINVAL;
563
564         if (local->scan_req && local->scan_req != req)
565                 return -EBUSY;
566
567         local->scan_req = req;
568
569         if (sdata->vif.type != NL80211_IFTYPE_STATION)
570                 return ieee80211_start_scan(sdata, req);
571
572         /*
573          * STA has a state machine that might need to defer scanning
574          * while it's trying to associate/authenticate, therefore we
575          * queue it up to the state machine in that case.
576          */
577
578         if (local->sw_scanning || local->hw_scanning) {
579                 if (local->scan_sdata == sdata)
580                         return 0;
581                 return -EBUSY;
582         }
583
584         ifmgd = &sdata->u.mgd;
585         set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request);
586         queue_work(local->hw.workqueue, &ifmgd->work);
587
588         return 0;
589 }