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/wireless.h>
16 #include <linux/if_arp.h>
17 #include <linux/rtnetlink.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 return (void *)cfg80211_get_bss(local->hw.wiphy,
33 ieee80211_get_channel(local->hw.wiphy,
35 bssid, ssid, ssid_len,
39 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
41 struct ieee80211_bss *bss = (void *)cbss;
43 kfree(bss_mesh_id(bss));
44 kfree(bss_mesh_cfg(bss));
47 void ieee80211_rx_bss_put(struct ieee80211_local *local,
48 struct ieee80211_bss *bss)
50 cfg80211_put_bss((struct cfg80211_bss *)bss);
53 struct ieee80211_bss *
54 ieee80211_bss_info_update(struct ieee80211_local *local,
55 struct ieee80211_rx_status *rx_status,
56 struct ieee80211_mgmt *mgmt,
58 struct ieee802_11_elems *elems,
59 struct ieee80211_channel *channel,
62 struct ieee80211_bss *bss;
66 if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
67 signal = rx_status->signal * 100;
68 else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
69 signal = (rx_status->signal * 100) / local->hw.max_signal;
71 bss = (void *)cfg80211_inform_bss_frame(local->hw.wiphy, channel,
72 mgmt, len, signal, GFP_ATOMIC);
77 bss->cbss.free_priv = ieee80211_rx_bss_free;
79 /* save the ERP value so that it is available at association time */
80 if (elems->erp_info && elems->erp_info_len >= 1) {
81 bss->erp_value = elems->erp_info[0];
82 bss->has_erp_value = 1;
86 struct ieee80211_tim_ie *tim_ie =
87 (struct ieee80211_tim_ie *)elems->tim;
88 bss->dtim_period = tim_ie->dtim_period;
91 /* set default value for buggy AP/no TIM element */
92 if (bss->dtim_period == 0)
95 bss->supp_rates_len = 0;
96 if (elems->supp_rates) {
97 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
98 if (clen > elems->supp_rates_len)
99 clen = elems->supp_rates_len;
100 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
102 bss->supp_rates_len += clen;
104 if (elems->ext_supp_rates) {
105 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
106 if (clen > elems->ext_supp_rates_len)
107 clen = elems->ext_supp_rates_len;
108 memcpy(&bss->supp_rates[bss->supp_rates_len],
109 elems->ext_supp_rates, clen);
110 bss->supp_rates_len += clen;
113 bss->wmm_used = elems->wmm_param || elems->wmm_info;
116 bss->last_probe_resp = jiffies;
122 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
124 struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
125 struct ieee80211_mgmt *mgmt;
126 struct ieee80211_bss *bss;
128 struct ieee80211_channel *channel;
132 bool presp, beacon = false;
133 struct ieee802_11_elems elems;
136 return RX_DROP_UNUSABLE;
138 mgmt = (struct ieee80211_mgmt *) skb->data;
139 fc = mgmt->frame_control;
141 if (ieee80211_is_ctl(fc))
145 return RX_DROP_MONITOR;
147 presp = ieee80211_is_probe_resp(fc);
149 /* ignore ProbeResp to foreign address */
150 if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
151 return RX_DROP_MONITOR;
154 elements = mgmt->u.probe_resp.variable;
155 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
157 beacon = ieee80211_is_beacon(fc);
158 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
159 elements = mgmt->u.beacon.variable;
162 if (!presp && !beacon)
165 if (baselen > skb->len)
166 return RX_DROP_MONITOR;
168 ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
170 if (elems.ds_params && elems.ds_params_len == 1)
171 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
173 freq = rx_status->freq;
175 channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
177 if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
178 return RX_DROP_MONITOR;
180 bss = ieee80211_bss_info_update(sdata->local, rx_status,
181 mgmt, skb->len, &elems,
184 ieee80211_rx_bss_put(sdata->local, bss);
190 /* return false if no more work */
191 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
193 struct cfg80211_scan_request *req = local->scan_req;
194 enum ieee80211_band band;
195 int i, ielen, n_chans;
198 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
201 band = local->hw_scan_band;
203 for (i = 0; i < req->n_channels; i++) {
204 if (req->channels[i]->band == band) {
205 local->hw_scan_req->channels[n_chans] =
211 local->hw_scan_band++;
214 local->hw_scan_req->n_channels = n_chans;
216 ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
217 req->ie, req->ie_len, band);
218 local->hw_scan_req->ie_len = ielen;
224 * inform AP that we will go to sleep so that it will buffer the frames
227 static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata)
229 struct ieee80211_local *local = sdata->local;
232 /* FIXME: what to do when local->pspolling is true? */
234 del_timer_sync(&local->dynamic_ps_timer);
235 cancel_work_sync(&local->dynamic_ps_enable_work);
237 if (local->hw.conf.flags & IEEE80211_CONF_PS) {
239 local->hw.conf.flags &= ~IEEE80211_CONF_PS;
240 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
243 if (!ps || !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
245 * If power save was enabled, no need to send a nullfunc
246 * frame because AP knows that we are sleeping. But if the
247 * hardware is creating the nullfunc frame for power save
248 * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
249 * enabled) and power save was enabled, the firmware just
250 * sent a null frame with power save disabled. So we need
251 * to send a new nullfunc frame to inform the AP that we
252 * are again sleeping.
254 ieee80211_send_nullfunc(local, sdata, 1);
257 /* inform AP that we are awake again, unless power save is enabled */
258 static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
260 struct ieee80211_local *local = sdata->local;
262 if (!local->ps_sdata)
263 ieee80211_send_nullfunc(local, sdata, 0);
266 * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
267 * will send a nullfunc frame with the powersave bit set
268 * even though the AP already knows that we are sleeping.
269 * This could be avoided by sending a null frame with power
270 * save bit disabled before enabling the power save, but
271 * this doesn't gain anything.
273 * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
274 * to send a nullfunc frame because AP already knows that
275 * we are sleeping, let's just enable power save mode in
278 local->hw.conf.flags |= IEEE80211_CONF_PS;
279 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
283 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
285 struct ieee80211_local *local = hw_to_local(hw);
286 struct ieee80211_sub_if_data *sdata;
289 mutex_lock(&local->scan_mtx);
292 * It's ok to abort a not-yet-running scan (that
293 * we have one at all will be verified by checking
294 * local->scan_req next), but not to complete it
297 if (WARN_ON(!local->scanning && !aborted))
300 if (WARN_ON(!local->scan_req)) {
301 mutex_unlock(&local->scan_mtx);
305 was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
306 if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
307 ieee80211_queue_delayed_work(&local->hw,
308 &local->scan_work, 0);
309 mutex_unlock(&local->scan_mtx);
313 kfree(local->hw_scan_req);
314 local->hw_scan_req = NULL;
316 if (local->scan_req != local->int_scan_req)
317 cfg80211_scan_done(local->scan_req, aborted);
318 local->scan_req = NULL;
319 local->scan_sdata = NULL;
322 local->scan_channel = NULL;
324 /* we only have to protect scan_req and hw/sw scan */
325 mutex_unlock(&local->scan_mtx);
327 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
331 ieee80211_configure_filter(local);
333 drv_sw_scan_complete(local);
335 mutex_lock(&local->iflist_mtx);
336 list_for_each_entry(sdata, &local->interfaces, list) {
337 if (!netif_running(sdata->dev))
340 /* Tell AP we're back */
341 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
342 if (sdata->u.mgd.associated) {
343 ieee80211_scan_ps_disable(sdata);
344 netif_wake_queue(sdata->dev);
347 netif_wake_queue(sdata->dev);
349 /* re-enable beaconing */
350 if (sdata->vif.type == NL80211_IFTYPE_AP ||
351 sdata->vif.type == NL80211_IFTYPE_ADHOC ||
352 sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
353 ieee80211_bss_info_change_notify(
354 sdata, BSS_CHANGED_BEACON_ENABLED);
356 mutex_unlock(&local->iflist_mtx);
359 ieee80211_recalc_idle(local);
360 ieee80211_mlme_notify_scan_completed(local);
361 ieee80211_ibss_notify_scan_completed(local);
362 ieee80211_mesh_notify_scan_completed(local);
364 EXPORT_SYMBOL(ieee80211_scan_completed);
366 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
368 struct ieee80211_sub_if_data *sdata;
371 * Hardware/driver doesn't support hw_scan, so use software
372 * scanning instead. First send a nullfunc frame with power save
373 * bit on so that AP will buffer the frames for us while we are not
374 * listening, then send probe requests to each channel and wait for
375 * the responses. After all channels are scanned, tune back to the
376 * original channel and send a nullfunc frame with power save bit
377 * off to trigger the AP to send us all the buffered frames.
379 * Note that while local->sw_scanning is true everything else but
380 * nullfunc frames and probe requests will be dropped in
381 * ieee80211_tx_h_check_assoc().
383 drv_sw_scan_start(local);
385 mutex_lock(&local->iflist_mtx);
386 list_for_each_entry(sdata, &local->interfaces, list) {
387 if (!netif_running(sdata->dev))
390 /* disable beaconing */
391 if (sdata->vif.type == NL80211_IFTYPE_AP ||
392 sdata->vif.type == NL80211_IFTYPE_ADHOC ||
393 sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
394 ieee80211_bss_info_change_notify(
395 sdata, BSS_CHANGED_BEACON_ENABLED);
398 * only handle non-STA interfaces here, STA interfaces
399 * are handled in the scan state machine
401 if (sdata->vif.type != NL80211_IFTYPE_STATION)
402 netif_stop_queue(sdata->dev);
404 mutex_unlock(&local->iflist_mtx);
406 local->next_scan_state = SCAN_DECISION;
407 local->scan_channel_idx = 0;
409 ieee80211_configure_filter(local);
411 /* TODO: start scan as soon as all nullfunc frames are ACKed */
412 ieee80211_queue_delayed_work(&local->hw,
414 IEEE80211_CHANNEL_TIME);
420 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
421 struct cfg80211_scan_request *req)
423 struct ieee80211_local *local = sdata->local;
424 struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
430 if (local->ops->hw_scan) {
433 local->hw_scan_req = kmalloc(
434 sizeof(*local->hw_scan_req) +
435 req->n_channels * sizeof(req->channels[0]) +
436 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
437 req->ie_len, GFP_KERNEL);
438 if (!local->hw_scan_req)
441 local->hw_scan_req->ssids = req->ssids;
442 local->hw_scan_req->n_ssids = req->n_ssids;
443 ies = (u8 *)local->hw_scan_req +
444 sizeof(*local->hw_scan_req) +
445 req->n_channels * sizeof(req->channels[0]);
446 local->hw_scan_req->ie = ies;
448 local->hw_scan_band = 0;
451 local->scan_req = req;
452 local->scan_sdata = sdata;
454 if (req != local->int_scan_req &&
455 sdata->vif.type == NL80211_IFTYPE_STATION &&
456 !list_empty(&ifmgd->work_list)) {
457 /* actually wait for the work it's doing to finish/time out */
458 set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request);
462 if (local->ops->hw_scan)
463 __set_bit(SCAN_HW_SCANNING, &local->scanning);
465 __set_bit(SCAN_SW_SCANNING, &local->scanning);
467 * Kicking off the scan need not be protected,
468 * only the scan variable stuff, since now
469 * local->scan_req is assigned and other callers
470 * will abort their scan attempts.
472 * This avoids getting a scan_mtx -> iflist_mtx
473 * dependency, so that the scan completed calls
474 * have more locking freedom.
477 ieee80211_recalc_idle(local);
478 mutex_unlock(&local->scan_mtx);
480 if (local->ops->hw_scan) {
481 WARN_ON(!ieee80211_prep_hw_scan(local));
482 rc = drv_hw_scan(local, local->hw_scan_req);
484 rc = ieee80211_start_sw_scan(local);
486 mutex_lock(&local->scan_mtx);
489 kfree(local->hw_scan_req);
490 local->hw_scan_req = NULL;
493 ieee80211_recalc_idle(local);
495 local->scan_req = NULL;
496 local->scan_sdata = NULL;
502 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
503 unsigned long *next_delay)
505 bool associated = false;
506 struct ieee80211_sub_if_data *sdata;
508 /* if no more bands/channels left, complete scan and advance to the idle state */
509 if (local->scan_channel_idx >= local->scan_req->n_channels) {
510 ieee80211_scan_completed(&local->hw, false);
514 /* check if at least one STA interface is associated */
515 mutex_lock(&local->iflist_mtx);
516 list_for_each_entry(sdata, &local->interfaces, list) {
517 if (!netif_running(sdata->dev))
520 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
521 if (sdata->u.mgd.associated) {
527 mutex_unlock(&local->iflist_mtx);
529 if (local->scan_channel) {
531 * we're currently scanning a different channel, let's
532 * switch back to the operating channel now if at least
533 * one interface is associated. Otherwise just scan the
537 local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
539 local->next_scan_state = SCAN_SET_CHANNEL;
542 * we're on the operating channel currently, let's
543 * leave that channel now to scan another one
545 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
552 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
553 unsigned long *next_delay)
555 struct ieee80211_sub_if_data *sdata;
558 * notify the AP about us leaving the channel and stop all STA interfaces
560 mutex_lock(&local->iflist_mtx);
561 list_for_each_entry(sdata, &local->interfaces, list) {
562 if (!netif_running(sdata->dev))
565 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
566 netif_stop_queue(sdata->dev);
567 if (sdata->u.mgd.associated)
568 ieee80211_scan_ps_enable(sdata);
571 mutex_unlock(&local->iflist_mtx);
573 __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
575 /* advance to the next channel to be scanned */
576 *next_delay = HZ / 10;
577 local->next_scan_state = SCAN_SET_CHANNEL;
580 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
581 unsigned long *next_delay)
583 struct ieee80211_sub_if_data *sdata = local->scan_sdata;
585 /* switch back to the operating channel */
586 local->scan_channel = NULL;
587 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
590 * notify the AP about us being back and restart all STA interfaces
592 mutex_lock(&local->iflist_mtx);
593 list_for_each_entry(sdata, &local->interfaces, list) {
594 if (!netif_running(sdata->dev))
597 /* Tell AP we're back */
598 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
599 if (sdata->u.mgd.associated)
600 ieee80211_scan_ps_disable(sdata);
601 netif_wake_queue(sdata->dev);
604 mutex_unlock(&local->iflist_mtx);
606 __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
608 *next_delay = HZ / 5;
609 local->next_scan_state = SCAN_DECISION;
612 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
613 unsigned long *next_delay)
616 struct ieee80211_channel *chan;
619 chan = local->scan_req->channels[local->scan_channel_idx];
621 local->scan_channel = chan;
622 if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
625 /* advance state machine to next channel/band */
626 local->scan_channel_idx++;
629 /* if we skip this channel return to the decision state */
630 local->next_scan_state = SCAN_DECISION;
635 * Probe delay is used to update the NAV, cf. 11.1.3.2.2
636 * (which unfortunately doesn't say _why_ step a) is done,
637 * but it waits for the probe delay or until a frame is
638 * received - and the received frame would update the NAV).
639 * For now, we do not support waiting until a frame is
642 * In any case, it is not necessary for a passive scan.
644 if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
645 !local->scan_req->n_ssids) {
646 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
647 local->next_scan_state = SCAN_DECISION;
651 /* active scan, send probes */
652 *next_delay = IEEE80211_PROBE_DELAY;
653 local->next_scan_state = SCAN_SEND_PROBE;
656 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
657 unsigned long *next_delay)
660 struct ieee80211_sub_if_data *sdata = local->scan_sdata;
662 for (i = 0; i < local->scan_req->n_ssids; i++)
663 ieee80211_send_probe_req(
665 local->scan_req->ssids[i].ssid,
666 local->scan_req->ssids[i].ssid_len,
667 local->scan_req->ie, local->scan_req->ie_len);
670 * After sending probe requests, wait for probe responses
673 *next_delay = IEEE80211_CHANNEL_TIME;
674 local->next_scan_state = SCAN_DECISION;
677 void ieee80211_scan_work(struct work_struct *work)
679 struct ieee80211_local *local =
680 container_of(work, struct ieee80211_local, scan_work.work);
681 struct ieee80211_sub_if_data *sdata = local->scan_sdata;
682 unsigned long next_delay = 0;
684 mutex_lock(&local->scan_mtx);
685 if (!sdata || !local->scan_req) {
686 mutex_unlock(&local->scan_mtx);
690 if (local->hw_scan_req) {
691 int rc = drv_hw_scan(local, local->hw_scan_req);
692 mutex_unlock(&local->scan_mtx);
694 ieee80211_scan_completed(&local->hw, true);
698 if (local->scan_req && !local->scanning) {
699 struct cfg80211_scan_request *req = local->scan_req;
702 local->scan_req = NULL;
703 local->scan_sdata = NULL;
705 rc = __ieee80211_start_scan(sdata, req);
706 mutex_unlock(&local->scan_mtx);
709 ieee80211_scan_completed(&local->hw, true);
713 mutex_unlock(&local->scan_mtx);
716 * Avoid re-scheduling when the sdata is going away.
718 if (!netif_running(sdata->dev)) {
719 ieee80211_scan_completed(&local->hw, true);
724 * as long as no delay is required advance immediately
725 * without scheduling a new work
728 switch (local->next_scan_state) {
730 if (ieee80211_scan_state_decision(local, &next_delay))
733 case SCAN_SET_CHANNEL:
734 ieee80211_scan_state_set_channel(local, &next_delay);
736 case SCAN_SEND_PROBE:
737 ieee80211_scan_state_send_probe(local, &next_delay);
739 case SCAN_LEAVE_OPER_CHANNEL:
740 ieee80211_scan_state_leave_oper_channel(local, &next_delay);
742 case SCAN_ENTER_OPER_CHANNEL:
743 ieee80211_scan_state_enter_oper_channel(local, &next_delay);
746 } while (next_delay == 0);
748 ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
751 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
752 struct cfg80211_scan_request *req)
756 mutex_lock(&sdata->local->scan_mtx);
757 res = __ieee80211_start_scan(sdata, req);
758 mutex_unlock(&sdata->local->scan_mtx);
763 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
764 const u8 *ssid, u8 ssid_len)
766 struct ieee80211_local *local = sdata->local;
769 mutex_lock(&local->scan_mtx);
775 memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
776 local->int_scan_req->ssids[0].ssid_len = ssid_len;
778 ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
780 mutex_unlock(&local->scan_mtx);
784 void ieee80211_scan_cancel(struct ieee80211_local *local)
788 cancel_delayed_work_sync(&local->scan_work);
791 * Only call this function when a scan can't be
792 * queued -- mostly at suspend under RTNL.
794 mutex_lock(&local->scan_mtx);
795 abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
796 (!local->scanning && local->scan_req);
797 mutex_unlock(&local->scan_mtx);
800 ieee80211_scan_completed(&local->hw, true);