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/slab.h>
18 #include <net/mac80211.h>
20 #include "ieee80211_i.h"
21 #include "driver-ops.h"
24 #define IEEE80211_PROBE_DELAY (HZ / 33)
25 #define IEEE80211_CHANNEL_TIME (HZ / 33)
26 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
28 struct ieee80211_bss
*
29 ieee80211_rx_bss_get(struct ieee80211_local
*local
, u8
*bssid
, int freq
,
30 u8
*ssid
, u8 ssid_len
)
32 struct cfg80211_bss
*cbss
;
34 cbss
= cfg80211_get_bss(local
->hw
.wiphy
,
35 ieee80211_get_channel(local
->hw
.wiphy
, freq
),
36 bssid
, ssid
, ssid_len
, 0, 0);
39 return (void *)cbss
->priv
;
42 static void ieee80211_rx_bss_free(struct cfg80211_bss
*cbss
)
44 struct ieee80211_bss
*bss
= (void *)cbss
->priv
;
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
)
55 cfg80211_put_bss(container_of((void *)bss
, struct cfg80211_bss
, priv
));
58 static bool is_uapsd_supported(struct ieee802_11_elems
*elems
)
62 if (elems
->wmm_info
&& elems
->wmm_info_len
== 7
63 && elems
->wmm_info
[5] == 1)
64 qos_info
= elems
->wmm_info
[6];
65 else if (elems
->wmm_param
&& elems
->wmm_param_len
== 24
66 && elems
->wmm_param
[5] == 1)
67 qos_info
= elems
->wmm_param
[6];
69 /* no valid wmm information or parameter element found */
72 return qos_info
& IEEE80211_WMM_IE_AP_QOSINFO_UAPSD
;
75 struct ieee80211_bss
*
76 ieee80211_bss_info_update(struct ieee80211_local
*local
,
77 struct ieee80211_rx_status
*rx_status
,
78 struct ieee80211_mgmt
*mgmt
,
80 struct ieee802_11_elems
*elems
,
81 struct ieee80211_channel
*channel
,
84 struct cfg80211_bss
*cbss
;
85 struct ieee80211_bss
*bss
;
89 if (local
->hw
.flags
& IEEE80211_HW_SIGNAL_DBM
)
90 signal
= rx_status
->signal
* 100;
91 else if (local
->hw
.flags
& IEEE80211_HW_SIGNAL_UNSPEC
)
92 signal
= (rx_status
->signal
* 100) / local
->hw
.max_signal
;
94 cbss
= cfg80211_inform_bss_frame(local
->hw
.wiphy
, channel
,
95 mgmt
, len
, signal
, GFP_ATOMIC
);
100 cbss
->free_priv
= ieee80211_rx_bss_free
;
101 bss
= (void *)cbss
->priv
;
103 /* save the ERP value so that it is available at association time */
104 if (elems
->erp_info
&& elems
->erp_info_len
>= 1) {
105 bss
->erp_value
= elems
->erp_info
[0];
106 bss
->has_erp_value
= 1;
110 struct ieee80211_tim_ie
*tim_ie
=
111 (struct ieee80211_tim_ie
*)elems
->tim
;
112 bss
->dtim_period
= tim_ie
->dtim_period
;
115 /* replace old supported rates if we get new values */
117 if (elems
->supp_rates
) {
118 clen
= IEEE80211_MAX_SUPP_RATES
;
119 if (clen
> elems
->supp_rates_len
)
120 clen
= elems
->supp_rates_len
;
121 memcpy(bss
->supp_rates
, elems
->supp_rates
, clen
);
124 if (elems
->ext_supp_rates
) {
125 clen
= IEEE80211_MAX_SUPP_RATES
- srlen
;
126 if (clen
> elems
->ext_supp_rates_len
)
127 clen
= elems
->ext_supp_rates_len
;
128 memcpy(bss
->supp_rates
+ srlen
, elems
->ext_supp_rates
, clen
);
132 bss
->supp_rates_len
= srlen
;
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 mutex_lock(&local
->scan_mtx
);
253 * It's ok to abort a not-yet-running scan (that
254 * we have one at all will be verified by checking
255 * local->scan_req next), but not to complete it
258 if (WARN_ON(!local
->scanning
&& !aborted
))
261 if (WARN_ON(!local
->scan_req
)) {
262 mutex_unlock(&local
->scan_mtx
);
266 was_hw_scan
= test_bit(SCAN_HW_SCANNING
, &local
->scanning
);
267 if (was_hw_scan
&& !aborted
&& ieee80211_prep_hw_scan(local
)) {
268 ieee80211_queue_delayed_work(&local
->hw
,
269 &local
->scan_work
, 0);
270 mutex_unlock(&local
->scan_mtx
);
274 kfree(local
->hw_scan_req
);
275 local
->hw_scan_req
= NULL
;
277 if (local
->scan_req
!= local
->int_scan_req
)
278 cfg80211_scan_done(local
->scan_req
, aborted
);
279 local
->scan_req
= NULL
;
280 local
->scan_sdata
= NULL
;
283 local
->scan_channel
= NULL
;
285 /* we only have to protect scan_req and hw/sw scan */
286 mutex_unlock(&local
->scan_mtx
);
288 ieee80211_hw_config(local
, IEEE80211_CONF_CHANGE_CHANNEL
);
292 ieee80211_configure_filter(local
);
294 drv_sw_scan_complete(local
);
296 ieee80211_offchannel_return(local
, true);
299 ieee80211_recalc_idle(local
);
300 ieee80211_mlme_notify_scan_completed(local
);
301 ieee80211_ibss_notify_scan_completed(local
);
302 ieee80211_mesh_notify_scan_completed(local
);
303 ieee80211_queue_work(&local
->hw
, &local
->work_work
);
305 EXPORT_SYMBOL(ieee80211_scan_completed
);
307 static int ieee80211_start_sw_scan(struct ieee80211_local
*local
)
310 * Hardware/driver doesn't support hw_scan, so use software
311 * scanning instead. First send a nullfunc frame with power save
312 * bit on so that AP will buffer the frames for us while we are not
313 * listening, then send probe requests to each channel and wait for
314 * the responses. After all channels are scanned, tune back to the
315 * original channel and send a nullfunc frame with power save bit
316 * off to trigger the AP to send us all the buffered frames.
318 * Note that while local->sw_scanning is true everything else but
319 * nullfunc frames and probe requests will be dropped in
320 * ieee80211_tx_h_check_assoc().
322 drv_sw_scan_start(local
);
324 ieee80211_offchannel_stop_beaconing(local
);
326 local
->next_scan_state
= SCAN_DECISION
;
327 local
->scan_channel_idx
= 0;
329 drv_flush(local
, false);
331 ieee80211_configure_filter(local
);
333 ieee80211_queue_delayed_work(&local
->hw
,
335 IEEE80211_CHANNEL_TIME
);
341 static int __ieee80211_start_scan(struct ieee80211_sub_if_data
*sdata
,
342 struct cfg80211_scan_request
*req
)
344 struct ieee80211_local
*local
= sdata
->local
;
350 if (!list_empty(&local
->work_list
)) {
351 /* wait for the work to finish/time out */
352 local
->scan_req
= req
;
353 local
->scan_sdata
= sdata
;
357 if (local
->ops
->hw_scan
) {
360 local
->hw_scan_req
= kmalloc(
361 sizeof(*local
->hw_scan_req
) +
362 req
->n_channels
* sizeof(req
->channels
[0]) +
363 2 + IEEE80211_MAX_SSID_LEN
+ local
->scan_ies_len
+
364 req
->ie_len
, GFP_KERNEL
);
365 if (!local
->hw_scan_req
)
368 local
->hw_scan_req
->ssids
= req
->ssids
;
369 local
->hw_scan_req
->n_ssids
= req
->n_ssids
;
370 ies
= (u8
*)local
->hw_scan_req
+
371 sizeof(*local
->hw_scan_req
) +
372 req
->n_channels
* sizeof(req
->channels
[0]);
373 local
->hw_scan_req
->ie
= ies
;
375 local
->hw_scan_band
= 0;
378 * After allocating local->hw_scan_req, we must
379 * go through until ieee80211_prep_hw_scan(), so
380 * anything that might be changed here and leave
381 * this function early must not go after this
386 local
->scan_req
= req
;
387 local
->scan_sdata
= sdata
;
389 if (local
->ops
->hw_scan
)
390 __set_bit(SCAN_HW_SCANNING
, &local
->scanning
);
392 __set_bit(SCAN_SW_SCANNING
, &local
->scanning
);
395 * Kicking off the scan need not be protected,
396 * only the scan variable stuff, since now
397 * local->scan_req is assigned and other callers
398 * will abort their scan attempts.
400 * This avoids too many locking dependencies
401 * so that the scan completed calls have more
405 ieee80211_recalc_idle(local
);
406 mutex_unlock(&local
->scan_mtx
);
408 if (local
->ops
->hw_scan
) {
409 WARN_ON(!ieee80211_prep_hw_scan(local
));
410 rc
= drv_hw_scan(local
, local
->hw_scan_req
);
412 rc
= ieee80211_start_sw_scan(local
);
414 mutex_lock(&local
->scan_mtx
);
417 kfree(local
->hw_scan_req
);
418 local
->hw_scan_req
= NULL
;
421 ieee80211_recalc_idle(local
);
423 local
->scan_req
= NULL
;
424 local
->scan_sdata
= NULL
;
430 static int ieee80211_scan_state_decision(struct ieee80211_local
*local
,
431 unsigned long *next_delay
)
433 bool associated
= false;
434 struct ieee80211_sub_if_data
*sdata
;
436 /* if no more bands/channels left, complete scan and advance to the idle state */
437 if (local
->scan_channel_idx
>= local
->scan_req
->n_channels
) {
438 ieee80211_scan_completed(&local
->hw
, false);
442 /* check if at least one STA interface is associated */
443 mutex_lock(&local
->iflist_mtx
);
444 list_for_each_entry(sdata
, &local
->interfaces
, list
) {
445 if (!ieee80211_sdata_running(sdata
))
448 if (sdata
->vif
.type
== NL80211_IFTYPE_STATION
) {
449 if (sdata
->u
.mgd
.associated
) {
455 mutex_unlock(&local
->iflist_mtx
);
457 if (local
->scan_channel
) {
459 * we're currently scanning a different channel, let's
460 * switch back to the operating channel now if at least
461 * one interface is associated. Otherwise just scan the
465 local
->next_scan_state
= SCAN_ENTER_OPER_CHANNEL
;
467 local
->next_scan_state
= SCAN_SET_CHANNEL
;
470 * we're on the operating channel currently, let's
471 * leave that channel now to scan another one
473 local
->next_scan_state
= SCAN_LEAVE_OPER_CHANNEL
;
480 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local
*local
,
481 unsigned long *next_delay
)
483 ieee80211_offchannel_stop_station(local
);
485 __set_bit(SCAN_OFF_CHANNEL
, &local
->scanning
);
488 * What if the nullfunc frames didn't arrive?
490 drv_flush(local
, false);
491 if (local
->ops
->flush
)
494 *next_delay
= HZ
/ 10;
496 /* advance to the next channel to be scanned */
497 local
->next_scan_state
= SCAN_SET_CHANNEL
;
500 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local
*local
,
501 unsigned long *next_delay
)
503 /* switch back to the operating channel */
504 local
->scan_channel
= NULL
;
505 ieee80211_hw_config(local
, IEEE80211_CONF_CHANGE_CHANNEL
);
508 * Only re-enable station mode interface now; beaconing will be
509 * re-enabled once the full scan has been completed.
511 ieee80211_offchannel_return(local
, false);
513 __clear_bit(SCAN_OFF_CHANNEL
, &local
->scanning
);
515 *next_delay
= HZ
/ 5;
516 local
->next_scan_state
= SCAN_DECISION
;
519 static void ieee80211_scan_state_set_channel(struct ieee80211_local
*local
,
520 unsigned long *next_delay
)
523 struct ieee80211_channel
*chan
;
526 chan
= local
->scan_req
->channels
[local
->scan_channel_idx
];
528 local
->scan_channel
= chan
;
529 if (ieee80211_hw_config(local
, IEEE80211_CONF_CHANGE_CHANNEL
))
532 /* advance state machine to next channel/band */
533 local
->scan_channel_idx
++;
536 /* if we skip this channel return to the decision state */
537 local
->next_scan_state
= SCAN_DECISION
;
542 * Probe delay is used to update the NAV, cf. 11.1.3.2.2
543 * (which unfortunately doesn't say _why_ step a) is done,
544 * but it waits for the probe delay or until a frame is
545 * received - and the received frame would update the NAV).
546 * For now, we do not support waiting until a frame is
549 * In any case, it is not necessary for a passive scan.
551 if (chan
->flags
& IEEE80211_CHAN_PASSIVE_SCAN
||
552 !local
->scan_req
->n_ssids
) {
553 *next_delay
= IEEE80211_PASSIVE_CHANNEL_TIME
;
554 local
->next_scan_state
= SCAN_DECISION
;
558 /* active scan, send probes */
559 *next_delay
= IEEE80211_PROBE_DELAY
;
560 local
->next_scan_state
= SCAN_SEND_PROBE
;
563 static void ieee80211_scan_state_send_probe(struct ieee80211_local
*local
,
564 unsigned long *next_delay
)
567 struct ieee80211_sub_if_data
*sdata
= local
->scan_sdata
;
569 for (i
= 0; i
< local
->scan_req
->n_ssids
; i
++)
570 ieee80211_send_probe_req(
572 local
->scan_req
->ssids
[i
].ssid
,
573 local
->scan_req
->ssids
[i
].ssid_len
,
574 local
->scan_req
->ie
, local
->scan_req
->ie_len
);
577 * After sending probe requests, wait for probe responses
580 *next_delay
= IEEE80211_CHANNEL_TIME
;
581 local
->next_scan_state
= SCAN_DECISION
;
584 void ieee80211_scan_work(struct work_struct
*work
)
586 struct ieee80211_local
*local
=
587 container_of(work
, struct ieee80211_local
, scan_work
.work
);
588 struct ieee80211_sub_if_data
*sdata
= local
->scan_sdata
;
589 unsigned long next_delay
= 0;
591 mutex_lock(&local
->scan_mtx
);
592 if (!sdata
|| !local
->scan_req
) {
593 mutex_unlock(&local
->scan_mtx
);
597 if (local
->hw_scan_req
) {
598 int rc
= drv_hw_scan(local
, local
->hw_scan_req
);
599 mutex_unlock(&local
->scan_mtx
);
601 ieee80211_scan_completed(&local
->hw
, true);
605 if (local
->scan_req
&& !local
->scanning
) {
606 struct cfg80211_scan_request
*req
= local
->scan_req
;
609 local
->scan_req
= NULL
;
610 local
->scan_sdata
= NULL
;
612 rc
= __ieee80211_start_scan(sdata
, req
);
613 mutex_unlock(&local
->scan_mtx
);
616 ieee80211_scan_completed(&local
->hw
, true);
620 mutex_unlock(&local
->scan_mtx
);
623 * Avoid re-scheduling when the sdata is going away.
625 if (!ieee80211_sdata_running(sdata
)) {
626 ieee80211_scan_completed(&local
->hw
, true);
631 * as long as no delay is required advance immediately
632 * without scheduling a new work
635 switch (local
->next_scan_state
) {
637 if (ieee80211_scan_state_decision(local
, &next_delay
))
640 case SCAN_SET_CHANNEL
:
641 ieee80211_scan_state_set_channel(local
, &next_delay
);
643 case SCAN_SEND_PROBE
:
644 ieee80211_scan_state_send_probe(local
, &next_delay
);
646 case SCAN_LEAVE_OPER_CHANNEL
:
647 ieee80211_scan_state_leave_oper_channel(local
, &next_delay
);
649 case SCAN_ENTER_OPER_CHANNEL
:
650 ieee80211_scan_state_enter_oper_channel(local
, &next_delay
);
653 } while (next_delay
== 0);
655 ieee80211_queue_delayed_work(&local
->hw
, &local
->scan_work
, next_delay
);
658 int ieee80211_request_scan(struct ieee80211_sub_if_data
*sdata
,
659 struct cfg80211_scan_request
*req
)
663 mutex_lock(&sdata
->local
->scan_mtx
);
664 res
= __ieee80211_start_scan(sdata
, req
);
665 mutex_unlock(&sdata
->local
->scan_mtx
);
670 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data
*sdata
,
671 const u8
*ssid
, u8 ssid_len
)
673 struct ieee80211_local
*local
= sdata
->local
;
676 mutex_lock(&local
->scan_mtx
);
682 memcpy(local
->int_scan_req
->ssids
[0].ssid
, ssid
, IEEE80211_MAX_SSID_LEN
);
683 local
->int_scan_req
->ssids
[0].ssid_len
= ssid_len
;
685 ret
= __ieee80211_start_scan(sdata
, sdata
->local
->int_scan_req
);
687 mutex_unlock(&local
->scan_mtx
);
691 void ieee80211_scan_cancel(struct ieee80211_local
*local
)
695 cancel_delayed_work_sync(&local
->scan_work
);
698 * Only call this function when a scan can't be
699 * queued -- mostly at suspend under RTNL.
701 mutex_lock(&local
->scan_mtx
);
702 abortscan
= test_bit(SCAN_SW_SCANNING
, &local
->scanning
) ||
703 (!local
->scanning
&& local
->scan_req
);
704 mutex_unlock(&local
->scan_mtx
);
707 ieee80211_scan_completed(&local
->hw
, true);