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 #include <linux/if_arp.h>
16 #include <linux/rtnetlink.h>
17 #include <linux/pm_qos_params.h>
18 #include <net/sch_generic.h>
19 #include <net/mac80211.h>
21 #include "ieee80211_i.h"
22 #include "driver-ops.h"
25 #define IEEE80211_PROBE_DELAY (HZ / 33)
26 #define IEEE80211_CHANNEL_TIME (HZ / 33)
27 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
29 struct ieee80211_bss
*
30 ieee80211_rx_bss_get(struct ieee80211_local
*local
, u8
*bssid
, int freq
,
31 u8
*ssid
, u8 ssid_len
)
33 struct cfg80211_bss
*cbss
;
35 cbss
= cfg80211_get_bss(local
->hw
.wiphy
,
36 ieee80211_get_channel(local
->hw
.wiphy
, freq
),
37 bssid
, ssid
, ssid_len
, 0, 0);
40 return (void *)cbss
->priv
;
43 static void ieee80211_rx_bss_free(struct cfg80211_bss
*cbss
)
45 struct ieee80211_bss
*bss
= (void *)cbss
->priv
;
47 kfree(bss_mesh_id(bss
));
48 kfree(bss_mesh_cfg(bss
));
51 void ieee80211_rx_bss_put(struct ieee80211_local
*local
,
52 struct ieee80211_bss
*bss
)
56 cfg80211_put_bss(container_of((void *)bss
, struct cfg80211_bss
, priv
));
59 static bool is_uapsd_supported(struct ieee802_11_elems
*elems
)
63 if (elems
->wmm_info
&& elems
->wmm_info_len
== 7
64 && elems
->wmm_info
[5] == 1)
65 qos_info
= elems
->wmm_info
[6];
66 else if (elems
->wmm_param
&& elems
->wmm_param_len
== 24
67 && elems
->wmm_param
[5] == 1)
68 qos_info
= elems
->wmm_param
[6];
70 /* no valid wmm information or parameter element found */
73 return qos_info
& IEEE80211_WMM_IE_AP_QOSINFO_UAPSD
;
76 struct ieee80211_bss
*
77 ieee80211_bss_info_update(struct ieee80211_local
*local
,
78 struct ieee80211_rx_status
*rx_status
,
79 struct ieee80211_mgmt
*mgmt
,
81 struct ieee802_11_elems
*elems
,
82 struct ieee80211_channel
*channel
,
85 struct cfg80211_bss
*cbss
;
86 struct ieee80211_bss
*bss
;
90 if (local
->hw
.flags
& IEEE80211_HW_SIGNAL_DBM
)
91 signal
= rx_status
->signal
* 100;
92 else if (local
->hw
.flags
& IEEE80211_HW_SIGNAL_UNSPEC
)
93 signal
= (rx_status
->signal
* 100) / local
->hw
.max_signal
;
95 cbss
= cfg80211_inform_bss_frame(local
->hw
.wiphy
, channel
,
96 mgmt
, len
, signal
, GFP_ATOMIC
);
101 cbss
->free_priv
= ieee80211_rx_bss_free
;
102 bss
= (void *)cbss
->priv
;
104 /* save the ERP value so that it is available at association time */
105 if (elems
->erp_info
&& elems
->erp_info_len
>= 1) {
106 bss
->erp_value
= elems
->erp_info
[0];
107 bss
->has_erp_value
= 1;
111 struct ieee80211_tim_ie
*tim_ie
=
112 (struct ieee80211_tim_ie
*)elems
->tim
;
113 bss
->dtim_period
= tim_ie
->dtim_period
;
116 bss
->supp_rates_len
= 0;
117 if (elems
->supp_rates
) {
118 clen
= IEEE80211_MAX_SUPP_RATES
- bss
->supp_rates_len
;
119 if (clen
> elems
->supp_rates_len
)
120 clen
= elems
->supp_rates_len
;
121 memcpy(&bss
->supp_rates
[bss
->supp_rates_len
], elems
->supp_rates
,
123 bss
->supp_rates_len
+= clen
;
125 if (elems
->ext_supp_rates
) {
126 clen
= IEEE80211_MAX_SUPP_RATES
- bss
->supp_rates_len
;
127 if (clen
> elems
->ext_supp_rates_len
)
128 clen
= elems
->ext_supp_rates_len
;
129 memcpy(&bss
->supp_rates
[bss
->supp_rates_len
],
130 elems
->ext_supp_rates
, clen
);
131 bss
->supp_rates_len
+= clen
;
134 bss
->wmm_used
= elems
->wmm_param
|| elems
->wmm_info
;
135 bss
->uapsd_supported
= is_uapsd_supported(elems
);
138 bss
->last_probe_resp
= jiffies
;
144 ieee80211_scan_rx(struct ieee80211_sub_if_data
*sdata
, struct sk_buff
*skb
)
146 struct ieee80211_rx_status
*rx_status
= IEEE80211_SKB_RXCB(skb
);
147 struct ieee80211_mgmt
*mgmt
;
148 struct ieee80211_bss
*bss
;
150 struct ieee80211_channel
*channel
;
154 bool presp
, beacon
= false;
155 struct ieee802_11_elems elems
;
158 return RX_DROP_UNUSABLE
;
160 mgmt
= (struct ieee80211_mgmt
*) skb
->data
;
161 fc
= mgmt
->frame_control
;
163 if (ieee80211_is_ctl(fc
))
167 return RX_DROP_MONITOR
;
169 presp
= ieee80211_is_probe_resp(fc
);
171 /* ignore ProbeResp to foreign address */
172 if (memcmp(mgmt
->da
, sdata
->vif
.addr
, ETH_ALEN
))
173 return RX_DROP_MONITOR
;
176 elements
= mgmt
->u
.probe_resp
.variable
;
177 baselen
= offsetof(struct ieee80211_mgmt
, u
.probe_resp
.variable
);
179 beacon
= ieee80211_is_beacon(fc
);
180 baselen
= offsetof(struct ieee80211_mgmt
, u
.beacon
.variable
);
181 elements
= mgmt
->u
.beacon
.variable
;
184 if (!presp
&& !beacon
)
187 if (baselen
> skb
->len
)
188 return RX_DROP_MONITOR
;
190 ieee802_11_parse_elems(elements
, skb
->len
- baselen
, &elems
);
192 if (elems
.ds_params
&& elems
.ds_params_len
== 1)
193 freq
= ieee80211_channel_to_frequency(elems
.ds_params
[0]);
195 freq
= rx_status
->freq
;
197 channel
= ieee80211_get_channel(sdata
->local
->hw
.wiphy
, freq
);
199 if (!channel
|| channel
->flags
& IEEE80211_CHAN_DISABLED
)
200 return RX_DROP_MONITOR
;
202 bss
= ieee80211_bss_info_update(sdata
->local
, rx_status
,
203 mgmt
, skb
->len
, &elems
,
206 ieee80211_rx_bss_put(sdata
->local
, bss
);
212 /* return false if no more work */
213 static bool ieee80211_prep_hw_scan(struct ieee80211_local
*local
)
215 struct cfg80211_scan_request
*req
= local
->scan_req
;
216 enum ieee80211_band band
;
217 int i
, ielen
, n_chans
;
220 if (local
->hw_scan_band
== IEEE80211_NUM_BANDS
)
223 band
= local
->hw_scan_band
;
225 for (i
= 0; i
< req
->n_channels
; i
++) {
226 if (req
->channels
[i
]->band
== band
) {
227 local
->hw_scan_req
->channels
[n_chans
] =
233 local
->hw_scan_band
++;
236 local
->hw_scan_req
->n_channels
= n_chans
;
238 ielen
= ieee80211_build_preq_ies(local
, (u8
*)local
->hw_scan_req
->ie
,
239 req
->ie
, req
->ie_len
, band
);
240 local
->hw_scan_req
->ie_len
= ielen
;
245 void ieee80211_scan_completed(struct ieee80211_hw
*hw
, bool aborted
)
247 struct ieee80211_local
*local
= hw_to_local(hw
);
250 trace_api_scan_completed(local
, aborted
);
252 mutex_lock(&local
->scan_mtx
);
255 * It's ok to abort a not-yet-running scan (that
256 * we have one at all will be verified by checking
257 * local->scan_req next), but not to complete it
260 if (WARN_ON(!local
->scanning
&& !aborted
))
263 if (WARN_ON(!local
->scan_req
)) {
264 mutex_unlock(&local
->scan_mtx
);
268 was_hw_scan
= test_bit(SCAN_HW_SCANNING
, &local
->scanning
);
269 if (was_hw_scan
&& !aborted
&& ieee80211_prep_hw_scan(local
)) {
270 ieee80211_queue_delayed_work(&local
->hw
,
271 &local
->scan_work
, 0);
272 mutex_unlock(&local
->scan_mtx
);
276 kfree(local
->hw_scan_req
);
277 local
->hw_scan_req
= NULL
;
279 if (local
->scan_req
!= local
->int_scan_req
)
280 cfg80211_scan_done(local
->scan_req
, aborted
);
281 local
->scan_req
= NULL
;
282 local
->scan_sdata
= NULL
;
285 local
->scan_channel
= NULL
;
287 /* we only have to protect scan_req and hw/sw scan */
288 mutex_unlock(&local
->scan_mtx
);
290 ieee80211_hw_config(local
, IEEE80211_CONF_CHANGE_CHANNEL
);
294 ieee80211_configure_filter(local
);
296 drv_sw_scan_complete(local
);
298 ieee80211_offchannel_return(local
, true);
301 ieee80211_recalc_idle(local
);
302 ieee80211_mlme_notify_scan_completed(local
);
303 ieee80211_ibss_notify_scan_completed(local
);
304 ieee80211_mesh_notify_scan_completed(local
);
305 ieee80211_queue_work(&local
->hw
, &local
->work_work
);
307 EXPORT_SYMBOL(ieee80211_scan_completed
);
309 static int ieee80211_start_sw_scan(struct ieee80211_local
*local
)
312 * Hardware/driver doesn't support hw_scan, so use software
313 * scanning instead. First send a nullfunc frame with power save
314 * bit on so that AP will buffer the frames for us while we are not
315 * listening, then send probe requests to each channel and wait for
316 * the responses. After all channels are scanned, tune back to the
317 * original channel and send a nullfunc frame with power save bit
318 * off to trigger the AP to send us all the buffered frames.
320 * Note that while local->sw_scanning is true everything else but
321 * nullfunc frames and probe requests will be dropped in
322 * ieee80211_tx_h_check_assoc().
324 drv_sw_scan_start(local
);
326 ieee80211_offchannel_stop_beaconing(local
);
328 local
->leave_oper_channel_time
= 0;
329 local
->next_scan_state
= SCAN_DECISION
;
330 local
->scan_channel_idx
= 0;
332 drv_flush(local
, false);
334 ieee80211_configure_filter(local
);
336 ieee80211_queue_delayed_work(&local
->hw
,
338 IEEE80211_CHANNEL_TIME
);
344 static int __ieee80211_start_scan(struct ieee80211_sub_if_data
*sdata
,
345 struct cfg80211_scan_request
*req
)
347 struct ieee80211_local
*local
= sdata
->local
;
353 if (!list_empty(&local
->work_list
)) {
354 /* wait for the work to finish/time out */
355 local
->scan_req
= req
;
356 local
->scan_sdata
= sdata
;
360 if (local
->ops
->hw_scan
) {
363 local
->hw_scan_req
= kmalloc(
364 sizeof(*local
->hw_scan_req
) +
365 req
->n_channels
* sizeof(req
->channels
[0]) +
366 2 + IEEE80211_MAX_SSID_LEN
+ local
->scan_ies_len
+
367 req
->ie_len
, GFP_KERNEL
);
368 if (!local
->hw_scan_req
)
371 local
->hw_scan_req
->ssids
= req
->ssids
;
372 local
->hw_scan_req
->n_ssids
= req
->n_ssids
;
373 ies
= (u8
*)local
->hw_scan_req
+
374 sizeof(*local
->hw_scan_req
) +
375 req
->n_channels
* sizeof(req
->channels
[0]);
376 local
->hw_scan_req
->ie
= ies
;
378 local
->hw_scan_band
= 0;
381 * After allocating local->hw_scan_req, we must
382 * go through until ieee80211_prep_hw_scan(), so
383 * anything that might be changed here and leave
384 * this function early must not go after this
389 local
->scan_req
= req
;
390 local
->scan_sdata
= sdata
;
392 if (local
->ops
->hw_scan
)
393 __set_bit(SCAN_HW_SCANNING
, &local
->scanning
);
395 __set_bit(SCAN_SW_SCANNING
, &local
->scanning
);
398 * Kicking off the scan need not be protected,
399 * only the scan variable stuff, since now
400 * local->scan_req is assigned and other callers
401 * will abort their scan attempts.
403 * This avoids too many locking dependencies
404 * so that the scan completed calls have more
408 ieee80211_recalc_idle(local
);
409 mutex_unlock(&local
->scan_mtx
);
411 if (local
->ops
->hw_scan
) {
412 WARN_ON(!ieee80211_prep_hw_scan(local
));
413 rc
= drv_hw_scan(local
, local
->hw_scan_req
);
415 rc
= ieee80211_start_sw_scan(local
);
417 mutex_lock(&local
->scan_mtx
);
420 kfree(local
->hw_scan_req
);
421 local
->hw_scan_req
= NULL
;
424 ieee80211_recalc_idle(local
);
426 local
->scan_req
= NULL
;
427 local
->scan_sdata
= NULL
;
434 ieee80211_scan_get_channel_time(struct ieee80211_channel
*chan
)
437 * TODO: channel switching also consumes quite some time,
438 * add that delay as well to get a better estimation
440 if (chan
->flags
& IEEE80211_CHAN_PASSIVE_SCAN
)
441 return IEEE80211_PASSIVE_CHANNEL_TIME
;
442 return IEEE80211_PROBE_DELAY
+ IEEE80211_CHANNEL_TIME
;
445 static int ieee80211_scan_state_decision(struct ieee80211_local
*local
,
446 unsigned long *next_delay
)
448 bool associated
= false;
449 bool tx_empty
= true;
451 bool listen_int_exceeded
;
452 unsigned long min_beacon_int
= 0;
453 struct ieee80211_sub_if_data
*sdata
;
454 struct ieee80211_channel
*next_chan
;
456 /* if no more bands/channels left, complete scan and advance to the idle state */
457 if (local
->scan_channel_idx
>= local
->scan_req
->n_channels
) {
458 ieee80211_scan_completed(&local
->hw
, false);
463 * check if at least one STA interface is associated,
464 * check if at least one STA interface has pending tx frames
465 * and grab the lowest used beacon interval
467 mutex_lock(&local
->iflist_mtx
);
468 list_for_each_entry(sdata
, &local
->interfaces
, list
) {
469 if (!ieee80211_sdata_running(sdata
))
472 if (sdata
->vif
.type
== NL80211_IFTYPE_STATION
) {
473 if (sdata
->u
.mgd
.associated
) {
476 if (sdata
->vif
.bss_conf
.beacon_int
<
477 min_beacon_int
|| min_beacon_int
== 0)
479 sdata
->vif
.bss_conf
.beacon_int
;
481 if (!qdisc_all_tx_empty(sdata
->dev
)) {
488 mutex_unlock(&local
->iflist_mtx
);
490 if (local
->scan_channel
) {
492 * we're currently scanning a different channel, let's
493 * see if we can scan another channel without interfering
494 * with the current traffic situation.
496 * Since we don't know if the AP has pending frames for us
497 * we can only check for our tx queues and use the current
498 * pm_qos requirements for rx. Hence, if no tx traffic occurs
499 * at all we will scan as many channels in a row as the pm_qos
500 * latency allows us to. Additionally we also check for the
501 * currently negotiated listen interval to prevent losing
502 * frames unnecessarily.
504 * Otherwise switch back to the operating channel.
506 next_chan
= local
->scan_req
->channels
[local
->scan_channel_idx
];
508 bad_latency
= time_after(jiffies
+
509 ieee80211_scan_get_channel_time(next_chan
),
510 local
->leave_oper_channel_time
+
511 usecs_to_jiffies(pm_qos_requirement(PM_QOS_NETWORK_LATENCY
)));
513 listen_int_exceeded
= time_after(jiffies
+
514 ieee80211_scan_get_channel_time(next_chan
),
515 local
->leave_oper_channel_time
+
516 usecs_to_jiffies(min_beacon_int
* 1024) *
517 local
->hw
.conf
.listen_interval
);
519 if (associated
&& ( !tx_empty
|| bad_latency
||
520 listen_int_exceeded
))
521 local
->next_scan_state
= SCAN_ENTER_OPER_CHANNEL
;
523 local
->next_scan_state
= SCAN_SET_CHANNEL
;
526 * we're on the operating channel currently, let's
527 * leave that channel now to scan another one
529 local
->next_scan_state
= SCAN_LEAVE_OPER_CHANNEL
;
536 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local
*local
,
537 unsigned long *next_delay
)
539 ieee80211_offchannel_stop_station(local
);
541 __set_bit(SCAN_OFF_CHANNEL
, &local
->scanning
);
544 * What if the nullfunc frames didn't arrive?
546 drv_flush(local
, false);
547 if (local
->ops
->flush
)
550 *next_delay
= HZ
/ 10;
552 /* remember when we left the operating channel */
553 local
->leave_oper_channel_time
= jiffies
;
555 /* advance to the next channel to be scanned */
556 local
->next_scan_state
= SCAN_SET_CHANNEL
;
559 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local
*local
,
560 unsigned long *next_delay
)
562 /* switch back to the operating channel */
563 local
->scan_channel
= NULL
;
564 ieee80211_hw_config(local
, IEEE80211_CONF_CHANGE_CHANNEL
);
567 * Only re-enable station mode interface now; beaconing will be
568 * re-enabled once the full scan has been completed.
570 ieee80211_offchannel_return(local
, false);
572 __clear_bit(SCAN_OFF_CHANNEL
, &local
->scanning
);
574 *next_delay
= HZ
/ 5;
575 local
->next_scan_state
= SCAN_DECISION
;
578 static void ieee80211_scan_state_set_channel(struct ieee80211_local
*local
,
579 unsigned long *next_delay
)
582 struct ieee80211_channel
*chan
;
585 chan
= local
->scan_req
->channels
[local
->scan_channel_idx
];
587 local
->scan_channel
= chan
;
588 if (ieee80211_hw_config(local
, IEEE80211_CONF_CHANGE_CHANNEL
))
591 /* advance state machine to next channel/band */
592 local
->scan_channel_idx
++;
595 /* if we skip this channel return to the decision state */
596 local
->next_scan_state
= SCAN_DECISION
;
601 * Probe delay is used to update the NAV, cf. 11.1.3.2.2
602 * (which unfortunately doesn't say _why_ step a) is done,
603 * but it waits for the probe delay or until a frame is
604 * received - and the received frame would update the NAV).
605 * For now, we do not support waiting until a frame is
608 * In any case, it is not necessary for a passive scan.
610 if (chan
->flags
& IEEE80211_CHAN_PASSIVE_SCAN
||
611 !local
->scan_req
->n_ssids
) {
612 *next_delay
= IEEE80211_PASSIVE_CHANNEL_TIME
;
613 local
->next_scan_state
= SCAN_DECISION
;
617 /* active scan, send probes */
618 *next_delay
= IEEE80211_PROBE_DELAY
;
619 local
->next_scan_state
= SCAN_SEND_PROBE
;
622 static void ieee80211_scan_state_send_probe(struct ieee80211_local
*local
,
623 unsigned long *next_delay
)
626 struct ieee80211_sub_if_data
*sdata
= local
->scan_sdata
;
628 for (i
= 0; i
< local
->scan_req
->n_ssids
; i
++)
629 ieee80211_send_probe_req(
631 local
->scan_req
->ssids
[i
].ssid
,
632 local
->scan_req
->ssids
[i
].ssid_len
,
633 local
->scan_req
->ie
, local
->scan_req
->ie_len
);
636 * After sending probe requests, wait for probe responses
639 *next_delay
= IEEE80211_CHANNEL_TIME
;
640 local
->next_scan_state
= SCAN_DECISION
;
643 void ieee80211_scan_work(struct work_struct
*work
)
645 struct ieee80211_local
*local
=
646 container_of(work
, struct ieee80211_local
, scan_work
.work
);
647 struct ieee80211_sub_if_data
*sdata
= local
->scan_sdata
;
648 unsigned long next_delay
= 0;
650 mutex_lock(&local
->scan_mtx
);
651 if (!sdata
|| !local
->scan_req
) {
652 mutex_unlock(&local
->scan_mtx
);
656 if (local
->hw_scan_req
) {
657 int rc
= drv_hw_scan(local
, local
->hw_scan_req
);
658 mutex_unlock(&local
->scan_mtx
);
660 ieee80211_scan_completed(&local
->hw
, true);
664 if (local
->scan_req
&& !local
->scanning
) {
665 struct cfg80211_scan_request
*req
= local
->scan_req
;
668 local
->scan_req
= NULL
;
669 local
->scan_sdata
= NULL
;
671 rc
= __ieee80211_start_scan(sdata
, req
);
672 mutex_unlock(&local
->scan_mtx
);
675 ieee80211_scan_completed(&local
->hw
, true);
679 mutex_unlock(&local
->scan_mtx
);
682 * Avoid re-scheduling when the sdata is going away.
684 if (!ieee80211_sdata_running(sdata
)) {
685 ieee80211_scan_completed(&local
->hw
, true);
690 * as long as no delay is required advance immediately
691 * without scheduling a new work
694 switch (local
->next_scan_state
) {
696 if (ieee80211_scan_state_decision(local
, &next_delay
))
699 case SCAN_SET_CHANNEL
:
700 ieee80211_scan_state_set_channel(local
, &next_delay
);
702 case SCAN_SEND_PROBE
:
703 ieee80211_scan_state_send_probe(local
, &next_delay
);
705 case SCAN_LEAVE_OPER_CHANNEL
:
706 ieee80211_scan_state_leave_oper_channel(local
, &next_delay
);
708 case SCAN_ENTER_OPER_CHANNEL
:
709 ieee80211_scan_state_enter_oper_channel(local
, &next_delay
);
712 } while (next_delay
== 0);
714 ieee80211_queue_delayed_work(&local
->hw
, &local
->scan_work
, next_delay
);
717 int ieee80211_request_scan(struct ieee80211_sub_if_data
*sdata
,
718 struct cfg80211_scan_request
*req
)
722 mutex_lock(&sdata
->local
->scan_mtx
);
723 res
= __ieee80211_start_scan(sdata
, req
);
724 mutex_unlock(&sdata
->local
->scan_mtx
);
729 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data
*sdata
,
730 const u8
*ssid
, u8 ssid_len
)
732 struct ieee80211_local
*local
= sdata
->local
;
735 mutex_lock(&local
->scan_mtx
);
741 memcpy(local
->int_scan_req
->ssids
[0].ssid
, ssid
, IEEE80211_MAX_SSID_LEN
);
742 local
->int_scan_req
->ssids
[0].ssid_len
= ssid_len
;
744 ret
= __ieee80211_start_scan(sdata
, sdata
->local
->int_scan_req
);
746 mutex_unlock(&local
->scan_mtx
);
750 void ieee80211_scan_cancel(struct ieee80211_local
*local
)
754 cancel_delayed_work_sync(&local
->scan_work
);
757 * Only call this function when a scan can't be
758 * queued -- mostly at suspend under RTNL.
760 mutex_lock(&local
->scan_mtx
);
761 abortscan
= test_bit(SCAN_SW_SCANNING
, &local
->scanning
) ||
762 (!local
->scanning
&& local
->scan_req
);
763 mutex_unlock(&local
->scan_mtx
);
766 ieee80211_scan_completed(&local
->hw
, true);