2 * Scanning implementation
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>
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.
15 /* TODO: figure out how to avoid that the "current BSS" expires */
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>
23 #include "ieee80211_i.h"
24 #include "driver-ops.h"
27 #define IEEE80211_PROBE_DELAY (HZ / 33)
28 #define IEEE80211_CHANNEL_TIME (HZ / 33)
29 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
31 struct ieee80211_bss
*
32 ieee80211_rx_bss_get(struct ieee80211_local
*local
, u8
*bssid
, int freq
,
33 u8
*ssid
, u8 ssid_len
)
35 return (void *)cfg80211_get_bss(local
->hw
.wiphy
,
36 ieee80211_get_channel(local
->hw
.wiphy
,
38 bssid
, ssid
, ssid_len
,
42 static void ieee80211_rx_bss_free(struct cfg80211_bss
*cbss
)
44 struct ieee80211_bss
*bss
= (void *)cbss
;
46 kfree(bss_mesh_id(bss
));
47 kfree(bss_mesh_cfg(bss
));
50 void ieee80211_rx_bss_put(struct ieee80211_local
*local
,
51 struct ieee80211_bss
*bss
)
53 cfg80211_put_bss((struct cfg80211_bss
*)bss
);
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
,
61 struct ieee802_11_elems
*elems
,
62 struct ieee80211_channel
*channel
,
65 struct ieee80211_bss
*bss
;
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
;
74 bss
= (void *)cfg80211_inform_bss_frame(local
->hw
.wiphy
, channel
,
75 mgmt
, len
, signal
, GFP_ATOMIC
);
80 bss
->cbss
.free_priv
= ieee80211_rx_bss_free
;
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;
89 struct ieee80211_tim_ie
*tim_ie
=
90 (struct ieee80211_tim_ie
*)elems
->tim
;
91 bss
->dtim_period
= tim_ie
->dtim_period
;
94 /* set default value for buggy APs */
95 if (!elems
->tim
|| bss
->dtim_period
== 0)
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
,
105 bss
->supp_rates_len
+= clen
;
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
;
116 bss
->wmm_used
= elems
->wmm_param
|| elems
->wmm_info
;
119 bss
->last_probe_resp
= jiffies
;
125 ieee80211_scan_rx(struct ieee80211_sub_if_data
*sdata
, struct sk_buff
*skb
)
127 struct ieee80211_rx_status
*rx_status
= IEEE80211_SKB_RXCB(skb
);
128 struct ieee80211_mgmt
*mgmt
;
129 struct ieee80211_bss
*bss
;
131 struct ieee80211_channel
*channel
;
135 bool presp
, beacon
= false;
136 struct ieee802_11_elems elems
;
139 return RX_DROP_UNUSABLE
;
141 mgmt
= (struct ieee80211_mgmt
*) skb
->data
;
142 fc
= mgmt
->frame_control
;
144 if (ieee80211_is_ctl(fc
))
148 return RX_DROP_MONITOR
;
150 presp
= ieee80211_is_probe_resp(fc
);
152 /* ignore ProbeResp to foreign address */
153 if (memcmp(mgmt
->da
, sdata
->dev
->dev_addr
, ETH_ALEN
))
154 return RX_DROP_MONITOR
;
157 elements
= mgmt
->u
.probe_resp
.variable
;
158 baselen
= offsetof(struct ieee80211_mgmt
, u
.probe_resp
.variable
);
160 beacon
= ieee80211_is_beacon(fc
);
161 baselen
= offsetof(struct ieee80211_mgmt
, u
.beacon
.variable
);
162 elements
= mgmt
->u
.beacon
.variable
;
165 if (!presp
&& !beacon
)
168 if (baselen
> skb
->len
)
169 return RX_DROP_MONITOR
;
171 ieee802_11_parse_elems(elements
, skb
->len
- baselen
, &elems
);
173 if (elems
.ds_params
&& elems
.ds_params_len
== 1)
174 freq
= ieee80211_channel_to_frequency(elems
.ds_params
[0]);
176 freq
= rx_status
->freq
;
178 channel
= ieee80211_get_channel(sdata
->local
->hw
.wiphy
, freq
);
180 if (!channel
|| channel
->flags
& IEEE80211_CHAN_DISABLED
)
181 return RX_DROP_MONITOR
;
183 bss
= ieee80211_bss_info_update(sdata
->local
, rx_status
,
184 mgmt
, skb
->len
, &elems
,
187 ieee80211_rx_bss_put(sdata
->local
, bss
);
194 * inform AP that we will go to sleep so that it will buffer the frames
197 static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data
*sdata
)
199 struct ieee80211_local
*local
= sdata
->local
;
202 /* FIXME: what to do when local->pspolling is true? */
204 del_timer_sync(&local
->dynamic_ps_timer
);
205 cancel_work_sync(&local
->dynamic_ps_enable_work
);
207 if (local
->hw
.conf
.flags
& IEEE80211_CONF_PS
) {
209 local
->hw
.conf
.flags
&= ~IEEE80211_CONF_PS
;
210 ieee80211_hw_config(local
, IEEE80211_CONF_CHANGE_PS
);
213 if (!ps
|| !(local
->hw
.flags
& IEEE80211_HW_PS_NULLFUNC_STACK
))
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.
224 ieee80211_send_nullfunc(local
, sdata
, 1);
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
)
230 struct ieee80211_local
*local
= sdata
->local
;
232 if (!local
->ps_sdata
)
233 ieee80211_send_nullfunc(local
, sdata
, 0);
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.
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
248 local
->hw
.conf
.flags
|= IEEE80211_CONF_PS
;
249 ieee80211_hw_config(local
, IEEE80211_CONF_CHANGE_PS
);
253 static void ieee80211_restore_scan_ies(struct ieee80211_local
*local
)
255 kfree(local
->scan_req
->ie
);
256 local
->scan_req
->ie
= local
->orig_ies
;
257 local
->scan_req
->ie_len
= local
->orig_ies_len
;
260 void ieee80211_scan_completed(struct ieee80211_hw
*hw
, bool aborted
)
262 struct ieee80211_local
*local
= hw_to_local(hw
);
263 struct ieee80211_sub_if_data
*sdata
;
266 mutex_lock(&local
->scan_mtx
);
268 if (WARN_ON(!local
->scanning
)) {
269 mutex_unlock(&local
->scan_mtx
);
273 if (WARN_ON(!local
->scan_req
)) {
274 mutex_unlock(&local
->scan_mtx
);
278 if (test_bit(SCAN_HW_SCANNING
, &local
->scanning
))
279 ieee80211_restore_scan_ies(local
);
281 if (local
->scan_req
!= &local
->int_scan_req
)
282 cfg80211_scan_done(local
->scan_req
, aborted
);
283 local
->scan_req
= NULL
;
285 was_hw_scan
= test_bit(SCAN_HW_SCANNING
, &local
->scanning
);
287 local
->scan_channel
= NULL
;
289 /* we only have to protect scan_req and hw/sw scan */
290 mutex_unlock(&local
->scan_mtx
);
292 ieee80211_hw_config(local
, IEEE80211_CONF_CHANGE_CHANNEL
);
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
,
302 spin_unlock_bh(&local
->filter_lock
);
304 drv_sw_scan_complete(local
);
306 mutex_lock(&local
->iflist_mtx
);
307 list_for_each_entry(sdata
, &local
->interfaces
, list
) {
308 if (!netif_running(sdata
->dev
))
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
);
318 netif_tx_wake_all_queues(sdata
->dev
);
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
);
327 mutex_unlock(&local
->iflist_mtx
);
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
);
335 EXPORT_SYMBOL(ieee80211_scan_completed
);
337 static int ieee80211_start_sw_scan(struct ieee80211_local
*local
)
339 struct ieee80211_sub_if_data
*sdata
;
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.
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().
354 drv_sw_scan_start(local
);
356 mutex_lock(&local
->iflist_mtx
);
357 list_for_each_entry(sdata
, &local
->interfaces
, list
) {
358 if (!netif_running(sdata
->dev
))
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
);
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
);
374 netif_tx_stop_all_queues(sdata
->dev
);
376 mutex_unlock(&local
->iflist_mtx
);
378 local
->scan_state
= SCAN_DECISION
;
379 local
->scan_channel_idx
= 0;
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
,
387 spin_unlock_bh(&local
->filter_lock
);
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
);
397 static int __ieee80211_start_scan(struct ieee80211_sub_if_data
*sdata
,
398 struct cfg80211_scan_request
*req
)
400 struct ieee80211_local
*local
= sdata
->local
;
401 struct ieee80211_if_managed
*ifmgd
= &sdata
->u
.mgd
;
407 if (local
->ops
->hw_scan
) {
411 ies
= kmalloc(2 + IEEE80211_MAX_SSID_LEN
+
412 local
->scan_ies_len
+ req
->ie_len
, GFP_KERNEL
);
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
;
424 local
->scan_req
= req
;
425 local
->scan_sdata
= sdata
;
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
);
435 if (local
->ops
->hw_scan
)
436 __set_bit(SCAN_HW_SCANNING
, &local
->scanning
);
438 __set_bit(SCAN_SW_SCANNING
, &local
->scanning
);
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.
445 * This avoids getting a scan_mtx -> iflist_mtx
446 * dependency, so that the scan completed calls
447 * have more locking freedom.
450 ieee80211_recalc_idle(local
);
451 mutex_unlock(&local
->scan_mtx
);
453 if (local
->ops
->hw_scan
)
454 rc
= drv_hw_scan(local
, local
->scan_req
);
456 rc
= ieee80211_start_sw_scan(local
);
458 mutex_lock(&local
->scan_mtx
);
461 if (local
->ops
->hw_scan
)
462 ieee80211_restore_scan_ies(local
);
465 ieee80211_recalc_idle(local
);
467 local
->scan_req
= NULL
;
468 local
->scan_sdata
= NULL
;
474 static int ieee80211_scan_state_decision(struct ieee80211_local
*local
,
475 unsigned long *next_delay
)
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);
484 local
->scan_state
= SCAN_SET_CHANNEL
;
488 static void ieee80211_scan_state_set_channel(struct ieee80211_local
*local
,
489 unsigned long *next_delay
)
492 struct ieee80211_channel
*chan
;
493 struct ieee80211_sub_if_data
*sdata
= local
->scan_sdata
;
496 chan
= local
->scan_req
->channels
[local
->scan_channel_idx
];
498 if (chan
->flags
& IEEE80211_CHAN_DISABLED
||
499 (sdata
->vif
.type
== NL80211_IFTYPE_ADHOC
&&
500 chan
->flags
& IEEE80211_CHAN_NO_IBSS
))
504 local
->scan_channel
= chan
;
505 if (ieee80211_hw_config(local
,
506 IEEE80211_CONF_CHANGE_CHANNEL
))
510 /* advance state machine to next channel/band */
511 local
->scan_channel_idx
++;
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
524 * In any case, it is not necessary for a passive scan.
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
;
533 /* active scan, send probes */
534 *next_delay
= IEEE80211_PROBE_DELAY
;
535 local
->scan_state
= SCAN_SEND_PROBE
;
538 static void ieee80211_scan_state_send_probe(struct ieee80211_local
*local
,
539 unsigned long *next_delay
)
542 struct ieee80211_sub_if_data
*sdata
= local
->scan_sdata
;
544 for (i
= 0; i
< local
->scan_req
->n_ssids
; i
++)
545 ieee80211_send_probe_req(
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
);
552 * After sending probe requests, wait for probe responses
555 *next_delay
= IEEE80211_CHANNEL_TIME
;
556 local
->scan_state
= SCAN_DECISION
;
559 void ieee80211_scan_work(struct work_struct
*work
)
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;
566 mutex_lock(&local
->scan_mtx
);
567 if (!sdata
|| !local
->scan_req
) {
568 mutex_unlock(&local
->scan_mtx
);
572 if (local
->scan_req
&& !local
->scanning
) {
573 struct cfg80211_scan_request
*req
= local
->scan_req
;
576 local
->scan_req
= NULL
;
578 rc
= __ieee80211_start_scan(sdata
, req
);
579 mutex_unlock(&local
->scan_mtx
);
582 ieee80211_scan_completed(&local
->hw
, true);
586 mutex_unlock(&local
->scan_mtx
);
589 * Avoid re-scheduling when the sdata is going away.
591 if (!netif_running(sdata
->dev
)) {
592 ieee80211_scan_completed(&local
->hw
, true);
597 * as long as no delay is required advance immediately
598 * without scheduling a new work
601 switch (local
->scan_state
) {
603 if (ieee80211_scan_state_decision(local
, &next_delay
))
606 case SCAN_SET_CHANNEL
:
607 ieee80211_scan_state_set_channel(local
, &next_delay
);
609 case SCAN_SEND_PROBE
:
610 ieee80211_scan_state_send_probe(local
, &next_delay
);
613 } while (next_delay
== 0);
615 queue_delayed_work(local
->hw
.workqueue
, &local
->scan_work
,
619 int ieee80211_request_scan(struct ieee80211_sub_if_data
*sdata
,
620 struct cfg80211_scan_request
*req
)
624 mutex_lock(&sdata
->local
->scan_mtx
);
625 res
= __ieee80211_start_scan(sdata
, req
);
626 mutex_unlock(&sdata
->local
->scan_mtx
);
631 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data
*sdata
,
632 const u8
*ssid
, u8 ssid_len
)
634 struct ieee80211_local
*local
= sdata
->local
;
637 mutex_lock(&local
->scan_mtx
);
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
;
646 ret
= __ieee80211_start_scan(sdata
, &sdata
->local
->int_scan_req
);
648 mutex_unlock(&local
->scan_mtx
);
652 void ieee80211_scan_cancel(struct ieee80211_local
*local
)
656 cancel_delayed_work_sync(&local
->scan_work
);
659 * Only call this function when a scan can't be
660 * queued -- mostly at suspend under RTNL.
662 mutex_lock(&local
->scan_mtx
);
663 swscan
= test_bit(SCAN_SW_SCANNING
, &local
->scanning
);
664 mutex_unlock(&local
->scan_mtx
);
667 ieee80211_scan_completed(&local
->hw
, true);