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);
291 if (WARN_ON(!local->scanning)) {
292 mutex_unlock(&local->scan_mtx);
296 if (WARN_ON(!local->scan_req)) {
297 mutex_unlock(&local->scan_mtx);
301 was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
302 if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
303 ieee80211_queue_delayed_work(&local->hw,
304 &local->scan_work, 0);
305 mutex_unlock(&local->scan_mtx);
309 kfree(local->hw_scan_req);
310 local->hw_scan_req = NULL;
312 if (local->scan_req != local->int_scan_req)
313 cfg80211_scan_done(local->scan_req, aborted);
314 local->scan_req = NULL;
315 local->scan_sdata = NULL;
318 local->scan_channel = NULL;
320 /* we only have to protect scan_req and hw/sw scan */
321 mutex_unlock(&local->scan_mtx);
323 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
327 ieee80211_configure_filter(local);
329 drv_sw_scan_complete(local);
331 mutex_lock(&local->iflist_mtx);
332 list_for_each_entry(sdata, &local->interfaces, list) {
333 if (!netif_running(sdata->dev))
336 /* Tell AP we're back */
337 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
338 if (sdata->u.mgd.associated) {
339 ieee80211_scan_ps_disable(sdata);
340 netif_wake_queue(sdata->dev);
343 netif_wake_queue(sdata->dev);
345 /* re-enable beaconing */
346 if (sdata->vif.type == NL80211_IFTYPE_AP ||
347 sdata->vif.type == NL80211_IFTYPE_ADHOC ||
348 sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
349 ieee80211_bss_info_change_notify(
350 sdata, BSS_CHANGED_BEACON_ENABLED);
352 mutex_unlock(&local->iflist_mtx);
355 ieee80211_recalc_idle(local);
356 ieee80211_mlme_notify_scan_completed(local);
357 ieee80211_ibss_notify_scan_completed(local);
358 ieee80211_mesh_notify_scan_completed(local);
360 EXPORT_SYMBOL(ieee80211_scan_completed);
362 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
364 struct ieee80211_sub_if_data *sdata;
367 * Hardware/driver doesn't support hw_scan, so use software
368 * scanning instead. First send a nullfunc frame with power save
369 * bit on so that AP will buffer the frames for us while we are not
370 * listening, then send probe requests to each channel and wait for
371 * the responses. After all channels are scanned, tune back to the
372 * original channel and send a nullfunc frame with power save bit
373 * off to trigger the AP to send us all the buffered frames.
375 * Note that while local->sw_scanning is true everything else but
376 * nullfunc frames and probe requests will be dropped in
377 * ieee80211_tx_h_check_assoc().
379 drv_sw_scan_start(local);
381 mutex_lock(&local->iflist_mtx);
382 list_for_each_entry(sdata, &local->interfaces, list) {
383 if (!netif_running(sdata->dev))
386 /* disable beaconing */
387 if (sdata->vif.type == NL80211_IFTYPE_AP ||
388 sdata->vif.type == NL80211_IFTYPE_ADHOC ||
389 sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
390 ieee80211_bss_info_change_notify(
391 sdata, BSS_CHANGED_BEACON_ENABLED);
394 * only handle non-STA interfaces here, STA interfaces
395 * are handled in the scan state machine
397 if (sdata->vif.type != NL80211_IFTYPE_STATION)
398 netif_stop_queue(sdata->dev);
400 mutex_unlock(&local->iflist_mtx);
402 local->next_scan_state = SCAN_DECISION;
403 local->scan_channel_idx = 0;
405 ieee80211_configure_filter(local);
407 /* TODO: start scan as soon as all nullfunc frames are ACKed */
408 ieee80211_queue_delayed_work(&local->hw,
410 IEEE80211_CHANNEL_TIME);
416 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
417 struct cfg80211_scan_request *req)
419 struct ieee80211_local *local = sdata->local;
420 struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
426 if (local->ops->hw_scan) {
429 local->hw_scan_req = kmalloc(
430 sizeof(*local->hw_scan_req) +
431 req->n_channels * sizeof(req->channels[0]) +
432 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
433 req->ie_len, GFP_KERNEL);
434 if (!local->hw_scan_req)
437 local->hw_scan_req->ssids = req->ssids;
438 local->hw_scan_req->n_ssids = req->n_ssids;
439 ies = (u8 *)local->hw_scan_req +
440 sizeof(*local->hw_scan_req) +
441 req->n_channels * sizeof(req->channels[0]);
442 local->hw_scan_req->ie = ies;
444 local->hw_scan_band = 0;
447 local->scan_req = req;
448 local->scan_sdata = sdata;
450 if (req != local->int_scan_req &&
451 sdata->vif.type == NL80211_IFTYPE_STATION &&
452 !list_empty(&ifmgd->work_list)) {
453 /* actually wait for the work it's doing to finish/time out */
454 set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request);
458 if (local->ops->hw_scan)
459 __set_bit(SCAN_HW_SCANNING, &local->scanning);
461 __set_bit(SCAN_SW_SCANNING, &local->scanning);
463 * Kicking off the scan need not be protected,
464 * only the scan variable stuff, since now
465 * local->scan_req is assigned and other callers
466 * will abort their scan attempts.
468 * This avoids getting a scan_mtx -> iflist_mtx
469 * dependency, so that the scan completed calls
470 * have more locking freedom.
473 ieee80211_recalc_idle(local);
474 mutex_unlock(&local->scan_mtx);
476 if (local->ops->hw_scan) {
477 WARN_ON(!ieee80211_prep_hw_scan(local));
478 rc = drv_hw_scan(local, local->hw_scan_req);
480 rc = ieee80211_start_sw_scan(local);
482 mutex_lock(&local->scan_mtx);
485 kfree(local->hw_scan_req);
486 local->hw_scan_req = NULL;
489 ieee80211_recalc_idle(local);
491 local->scan_req = NULL;
492 local->scan_sdata = NULL;
498 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
499 unsigned long *next_delay)
501 bool associated = false;
502 struct ieee80211_sub_if_data *sdata;
504 /* if no more bands/channels left, complete scan and advance to the idle state */
505 if (local->scan_channel_idx >= local->scan_req->n_channels) {
506 ieee80211_scan_completed(&local->hw, false);
510 /* check if at least one STA interface is associated */
511 mutex_lock(&local->iflist_mtx);
512 list_for_each_entry(sdata, &local->interfaces, list) {
513 if (!netif_running(sdata->dev))
516 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
517 if (sdata->u.mgd.associated) {
523 mutex_unlock(&local->iflist_mtx);
525 if (local->scan_channel) {
527 * we're currently scanning a different channel, let's
528 * switch back to the operating channel now if at least
529 * one interface is associated. Otherwise just scan the
533 local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
535 local->next_scan_state = SCAN_SET_CHANNEL;
538 * we're on the operating channel currently, let's
539 * leave that channel now to scan another one
541 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
548 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
549 unsigned long *next_delay)
551 struct ieee80211_sub_if_data *sdata;
554 * notify the AP about us leaving the channel and stop all STA interfaces
556 mutex_lock(&local->iflist_mtx);
557 list_for_each_entry(sdata, &local->interfaces, list) {
558 if (!netif_running(sdata->dev))
561 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
562 netif_stop_queue(sdata->dev);
563 if (sdata->u.mgd.associated)
564 ieee80211_scan_ps_enable(sdata);
567 mutex_unlock(&local->iflist_mtx);
569 __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
571 /* advance to the next channel to be scanned */
572 *next_delay = HZ / 10;
573 local->next_scan_state = SCAN_SET_CHANNEL;
576 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
577 unsigned long *next_delay)
579 struct ieee80211_sub_if_data *sdata = local->scan_sdata;
581 /* switch back to the operating channel */
582 local->scan_channel = NULL;
583 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
586 * notify the AP about us being back and restart all STA interfaces
588 mutex_lock(&local->iflist_mtx);
589 list_for_each_entry(sdata, &local->interfaces, list) {
590 if (!netif_running(sdata->dev))
593 /* Tell AP we're back */
594 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
595 if (sdata->u.mgd.associated)
596 ieee80211_scan_ps_disable(sdata);
597 netif_wake_queue(sdata->dev);
600 mutex_unlock(&local->iflist_mtx);
602 __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
604 *next_delay = HZ / 5;
605 local->next_scan_state = SCAN_DECISION;
608 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
609 unsigned long *next_delay)
612 struct ieee80211_channel *chan;
613 struct ieee80211_sub_if_data *sdata = local->scan_sdata;
616 chan = local->scan_req->channels[local->scan_channel_idx];
618 if (chan->flags & IEEE80211_CHAN_DISABLED ||
619 (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
620 chan->flags & IEEE80211_CHAN_NO_IBSS))
624 local->scan_channel = chan;
625 if (ieee80211_hw_config(local,
626 IEEE80211_CONF_CHANGE_CHANNEL))
630 /* advance state machine to next channel/band */
631 local->scan_channel_idx++;
634 /* if we skip this channel return to the decision state */
635 local->next_scan_state = SCAN_DECISION;
640 * Probe delay is used to update the NAV, cf. 11.1.3.2.2
641 * (which unfortunately doesn't say _why_ step a) is done,
642 * but it waits for the probe delay or until a frame is
643 * received - and the received frame would update the NAV).
644 * For now, we do not support waiting until a frame is
647 * In any case, it is not necessary for a passive scan.
649 if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
650 !local->scan_req->n_ssids) {
651 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
652 local->next_scan_state = SCAN_DECISION;
656 /* active scan, send probes */
657 *next_delay = IEEE80211_PROBE_DELAY;
658 local->next_scan_state = SCAN_SEND_PROBE;
661 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
662 unsigned long *next_delay)
665 struct ieee80211_sub_if_data *sdata = local->scan_sdata;
667 for (i = 0; i < local->scan_req->n_ssids; i++)
668 ieee80211_send_probe_req(
670 local->scan_req->ssids[i].ssid,
671 local->scan_req->ssids[i].ssid_len,
672 local->scan_req->ie, local->scan_req->ie_len);
675 * After sending probe requests, wait for probe responses
678 *next_delay = IEEE80211_CHANNEL_TIME;
679 local->next_scan_state = SCAN_DECISION;
682 void ieee80211_scan_work(struct work_struct *work)
684 struct ieee80211_local *local =
685 container_of(work, struct ieee80211_local, scan_work.work);
686 struct ieee80211_sub_if_data *sdata = local->scan_sdata;
687 unsigned long next_delay = 0;
689 mutex_lock(&local->scan_mtx);
690 if (!sdata || !local->scan_req) {
691 mutex_unlock(&local->scan_mtx);
695 if (local->hw_scan_req) {
696 int rc = drv_hw_scan(local, local->hw_scan_req);
697 mutex_unlock(&local->scan_mtx);
699 ieee80211_scan_completed(&local->hw, true);
703 if (local->scan_req && !local->scanning) {
704 struct cfg80211_scan_request *req = local->scan_req;
707 local->scan_req = NULL;
708 local->scan_sdata = NULL;
710 rc = __ieee80211_start_scan(sdata, req);
711 mutex_unlock(&local->scan_mtx);
714 ieee80211_scan_completed(&local->hw, true);
718 mutex_unlock(&local->scan_mtx);
721 * Avoid re-scheduling when the sdata is going away.
723 if (!netif_running(sdata->dev)) {
724 ieee80211_scan_completed(&local->hw, true);
729 * as long as no delay is required advance immediately
730 * without scheduling a new work
733 switch (local->next_scan_state) {
735 if (ieee80211_scan_state_decision(local, &next_delay))
738 case SCAN_SET_CHANNEL:
739 ieee80211_scan_state_set_channel(local, &next_delay);
741 case SCAN_SEND_PROBE:
742 ieee80211_scan_state_send_probe(local, &next_delay);
744 case SCAN_LEAVE_OPER_CHANNEL:
745 ieee80211_scan_state_leave_oper_channel(local, &next_delay);
747 case SCAN_ENTER_OPER_CHANNEL:
748 ieee80211_scan_state_enter_oper_channel(local, &next_delay);
751 } while (next_delay == 0);
753 ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
756 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
757 struct cfg80211_scan_request *req)
761 mutex_lock(&sdata->local->scan_mtx);
762 res = __ieee80211_start_scan(sdata, req);
763 mutex_unlock(&sdata->local->scan_mtx);
768 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
769 const u8 *ssid, u8 ssid_len)
771 struct ieee80211_local *local = sdata->local;
774 mutex_lock(&local->scan_mtx);
780 memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
781 local->int_scan_req->ssids[0].ssid_len = ssid_len;
783 ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
785 mutex_unlock(&local->scan_mtx);
789 void ieee80211_scan_cancel(struct ieee80211_local *local)
793 cancel_delayed_work_sync(&local->scan_work);
796 * Only call this function when a scan can't be
797 * queued -- mostly at suspend under RTNL.
799 mutex_lock(&local->scan_mtx);
800 abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
801 (!local->scanning && local->scan_req);
802 mutex_unlock(&local->scan_mtx);
805 ieee80211_scan_completed(&local->hw, true);