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 <linux/slab.h>
20 #include <net/mac80211.h>
22 #include "ieee80211_i.h"
23 #include "driver-ops.h"
26 #define IEEE80211_PROBE_DELAY (HZ / 33)
27 #define IEEE80211_CHANNEL_TIME (HZ / 33)
28 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
30 struct ieee80211_bss *
31 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
32 u8 *ssid, u8 ssid_len)
34 struct cfg80211_bss *cbss;
36 cbss = cfg80211_get_bss(local->hw.wiphy,
37 ieee80211_get_channel(local->hw.wiphy, freq),
38 bssid, ssid, ssid_len, 0, 0);
41 return (void *)cbss->priv;
44 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
46 struct ieee80211_bss *bss = (void *)cbss->priv;
48 kfree(bss_mesh_id(bss));
49 kfree(bss_mesh_cfg(bss));
52 void ieee80211_rx_bss_put(struct ieee80211_local *local,
53 struct ieee80211_bss *bss)
57 cfg80211_put_bss(container_of((void *)bss, struct cfg80211_bss, priv));
60 static bool is_uapsd_supported(struct ieee802_11_elems *elems)
64 if (elems->wmm_info && elems->wmm_info_len == 7
65 && elems->wmm_info[5] == 1)
66 qos_info = elems->wmm_info[6];
67 else if (elems->wmm_param && elems->wmm_param_len == 24
68 && elems->wmm_param[5] == 1)
69 qos_info = elems->wmm_param[6];
71 /* no valid wmm information or parameter element found */
74 return qos_info & IEEE80211_WMM_IE_AP_QOSINFO_UAPSD;
77 struct ieee80211_bss *
78 ieee80211_bss_info_update(struct ieee80211_local *local,
79 struct ieee80211_rx_status *rx_status,
80 struct ieee80211_mgmt *mgmt,
82 struct ieee802_11_elems *elems,
83 struct ieee80211_channel *channel,
86 struct cfg80211_bss *cbss;
87 struct ieee80211_bss *bss;
91 if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
92 signal = rx_status->signal * 100;
93 else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
94 signal = (rx_status->signal * 100) / local->hw.max_signal;
96 cbss = cfg80211_inform_bss_frame(local->hw.wiphy, channel,
97 mgmt, len, signal, GFP_ATOMIC);
102 cbss->free_priv = ieee80211_rx_bss_free;
103 bss = (void *)cbss->priv;
105 /* save the ERP value so that it is available at association time */
106 if (elems->erp_info && elems->erp_info_len >= 1) {
107 bss->erp_value = elems->erp_info[0];
108 bss->has_erp_value = 1;
112 struct ieee80211_tim_ie *tim_ie =
113 (struct ieee80211_tim_ie *)elems->tim;
114 bss->dtim_period = tim_ie->dtim_period;
117 /* If the beacon had no TIM IE, or it was invalid, use 1 */
118 if (beacon && !bss->dtim_period)
119 bss->dtim_period = 1;
121 /* replace old supported rates if we get new values */
123 if (elems->supp_rates) {
124 clen = IEEE80211_MAX_SUPP_RATES;
125 if (clen > elems->supp_rates_len)
126 clen = elems->supp_rates_len;
127 memcpy(bss->supp_rates, elems->supp_rates, clen);
130 if (elems->ext_supp_rates) {
131 clen = IEEE80211_MAX_SUPP_RATES - srlen;
132 if (clen > elems->ext_supp_rates_len)
133 clen = elems->ext_supp_rates_len;
134 memcpy(bss->supp_rates + srlen, elems->ext_supp_rates, clen);
138 bss->supp_rates_len = srlen;
140 bss->wmm_used = elems->wmm_param || elems->wmm_info;
141 bss->uapsd_supported = is_uapsd_supported(elems);
144 bss->last_probe_resp = jiffies;
150 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
152 struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
153 struct ieee80211_mgmt *mgmt;
154 struct ieee80211_bss *bss;
156 struct ieee80211_channel *channel;
160 bool presp, beacon = false;
161 struct ieee802_11_elems elems;
164 return RX_DROP_UNUSABLE;
166 mgmt = (struct ieee80211_mgmt *) skb->data;
167 fc = mgmt->frame_control;
169 if (ieee80211_is_ctl(fc))
173 return RX_DROP_MONITOR;
175 presp = ieee80211_is_probe_resp(fc);
177 /* ignore ProbeResp to foreign address */
178 if (memcmp(mgmt->da, sdata->vif.addr, ETH_ALEN))
179 return RX_DROP_MONITOR;
182 elements = mgmt->u.probe_resp.variable;
183 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
185 beacon = ieee80211_is_beacon(fc);
186 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
187 elements = mgmt->u.beacon.variable;
190 if (!presp && !beacon)
193 if (baselen > skb->len)
194 return RX_DROP_MONITOR;
196 ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
198 if (elems.ds_params && elems.ds_params_len == 1)
199 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
201 freq = rx_status->freq;
203 channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
205 if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
206 return RX_DROP_MONITOR;
208 bss = ieee80211_bss_info_update(sdata->local, rx_status,
209 mgmt, skb->len, &elems,
212 ieee80211_rx_bss_put(sdata->local, bss);
218 /* return false if no more work */
219 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
221 struct cfg80211_scan_request *req = local->scan_req;
222 enum ieee80211_band band;
223 int i, ielen, n_chans;
226 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
229 band = local->hw_scan_band;
231 for (i = 0; i < req->n_channels; i++) {
232 if (req->channels[i]->band == band) {
233 local->hw_scan_req->channels[n_chans] =
239 local->hw_scan_band++;
242 local->hw_scan_req->n_channels = n_chans;
244 ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
245 req->ie, req->ie_len, band);
246 local->hw_scan_req->ie_len = ielen;
251 static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
253 struct ieee80211_local *local = hw_to_local(hw);
256 mutex_lock(&local->mtx);
259 * It's ok to abort a not-yet-running scan (that
260 * we have one at all will be verified by checking
261 * local->scan_req next), but not to complete it
264 if (WARN_ON(!local->scanning && !aborted))
267 if (WARN_ON(!local->scan_req)) {
268 mutex_unlock(&local->mtx);
272 was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
273 if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
274 ieee80211_queue_delayed_work(&local->hw,
275 &local->scan_work, 0);
276 mutex_unlock(&local->mtx);
280 kfree(local->hw_scan_req);
281 local->hw_scan_req = NULL;
283 if (local->scan_req != local->int_scan_req)
284 cfg80211_scan_done(local->scan_req, aborted);
285 local->scan_req = NULL;
286 local->scan_sdata = NULL;
289 local->scan_channel = NULL;
291 /* we only have to protect scan_req and hw/sw scan */
292 mutex_unlock(&local->mtx);
294 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
298 ieee80211_configure_filter(local);
300 drv_sw_scan_complete(local);
302 ieee80211_offchannel_return(local, true);
305 mutex_lock(&local->mtx);
306 ieee80211_recalc_idle(local);
307 mutex_unlock(&local->mtx);
308 ieee80211_mlme_notify_scan_completed(local);
309 ieee80211_ibss_notify_scan_completed(local);
310 ieee80211_mesh_notify_scan_completed(local);
311 ieee80211_queue_work(&local->hw, &local->work_work);
314 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
316 struct ieee80211_local *local = hw_to_local(hw);
318 trace_api_scan_completed(local, aborted);
320 set_bit(SCAN_COMPLETED, &local->scanning);
322 set_bit(SCAN_ABORTED, &local->scanning);
323 ieee80211_queue_delayed_work(&local->hw, &local->scan_work, 0);
325 EXPORT_SYMBOL(ieee80211_scan_completed);
327 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
330 * Hardware/driver doesn't support hw_scan, so use software
331 * scanning instead. First send a nullfunc frame with power save
332 * bit on so that AP will buffer the frames for us while we are not
333 * listening, then send probe requests to each channel and wait for
334 * the responses. After all channels are scanned, tune back to the
335 * original channel and send a nullfunc frame with power save bit
336 * off to trigger the AP to send us all the buffered frames.
338 * Note that while local->sw_scanning is true everything else but
339 * nullfunc frames and probe requests will be dropped in
340 * ieee80211_tx_h_check_assoc().
342 drv_sw_scan_start(local);
344 ieee80211_offchannel_stop_beaconing(local);
346 local->leave_oper_channel_time = 0;
347 local->next_scan_state = SCAN_DECISION;
348 local->scan_channel_idx = 0;
350 drv_flush(local, false);
352 ieee80211_configure_filter(local);
354 ieee80211_queue_delayed_work(&local->hw,
356 IEEE80211_CHANNEL_TIME);
362 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
363 struct cfg80211_scan_request *req)
365 struct ieee80211_local *local = sdata->local;
371 if (!list_empty(&local->work_list)) {
372 /* wait for the work to finish/time out */
373 local->scan_req = req;
374 local->scan_sdata = sdata;
378 if (local->ops->hw_scan) {
381 local->hw_scan_req = kmalloc(
382 sizeof(*local->hw_scan_req) +
383 req->n_channels * sizeof(req->channels[0]) +
384 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
385 req->ie_len, GFP_KERNEL);
386 if (!local->hw_scan_req)
389 local->hw_scan_req->ssids = req->ssids;
390 local->hw_scan_req->n_ssids = req->n_ssids;
391 ies = (u8 *)local->hw_scan_req +
392 sizeof(*local->hw_scan_req) +
393 req->n_channels * sizeof(req->channels[0]);
394 local->hw_scan_req->ie = ies;
396 local->hw_scan_band = 0;
399 * After allocating local->hw_scan_req, we must
400 * go through until ieee80211_prep_hw_scan(), so
401 * anything that might be changed here and leave
402 * this function early must not go after this
407 local->scan_req = req;
408 local->scan_sdata = sdata;
410 if (local->ops->hw_scan)
411 __set_bit(SCAN_HW_SCANNING, &local->scanning);
413 __set_bit(SCAN_SW_SCANNING, &local->scanning);
415 ieee80211_recalc_idle(local);
417 if (local->ops->hw_scan) {
418 WARN_ON(!ieee80211_prep_hw_scan(local));
419 rc = drv_hw_scan(local, sdata, local->hw_scan_req);
421 rc = ieee80211_start_sw_scan(local);
424 kfree(local->hw_scan_req);
425 local->hw_scan_req = NULL;
428 ieee80211_recalc_idle(local);
430 local->scan_req = NULL;
431 local->scan_sdata = NULL;
438 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
441 * TODO: channel switching also consumes quite some time,
442 * add that delay as well to get a better estimation
444 if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN)
445 return IEEE80211_PASSIVE_CHANNEL_TIME;
446 return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
449 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
450 unsigned long *next_delay)
452 bool associated = false;
453 bool tx_empty = true;
455 bool listen_int_exceeded;
456 unsigned long min_beacon_int = 0;
457 struct ieee80211_sub_if_data *sdata;
458 struct ieee80211_channel *next_chan;
460 /* if no more bands/channels left, complete scan and advance to the idle state */
461 if (local->scan_channel_idx >= local->scan_req->n_channels) {
462 __ieee80211_scan_completed(&local->hw, false);
467 * check if at least one STA interface is associated,
468 * check if at least one STA interface has pending tx frames
469 * and grab the lowest used beacon interval
471 mutex_lock(&local->iflist_mtx);
472 list_for_each_entry(sdata, &local->interfaces, list) {
473 if (!ieee80211_sdata_running(sdata))
476 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
477 if (sdata->u.mgd.associated) {
480 if (sdata->vif.bss_conf.beacon_int <
481 min_beacon_int || min_beacon_int == 0)
483 sdata->vif.bss_conf.beacon_int;
485 if (!qdisc_all_tx_empty(sdata->dev)) {
492 mutex_unlock(&local->iflist_mtx);
494 if (local->scan_channel) {
496 * we're currently scanning a different channel, let's
497 * see if we can scan another channel without interfering
498 * with the current traffic situation.
500 * Since we don't know if the AP has pending frames for us
501 * we can only check for our tx queues and use the current
502 * pm_qos requirements for rx. Hence, if no tx traffic occurs
503 * at all we will scan as many channels in a row as the pm_qos
504 * latency allows us to. Additionally we also check for the
505 * currently negotiated listen interval to prevent losing
506 * frames unnecessarily.
508 * Otherwise switch back to the operating channel.
510 next_chan = local->scan_req->channels[local->scan_channel_idx];
512 bad_latency = time_after(jiffies +
513 ieee80211_scan_get_channel_time(next_chan),
514 local->leave_oper_channel_time +
515 usecs_to_jiffies(pm_qos_request(PM_QOS_NETWORK_LATENCY)));
517 listen_int_exceeded = time_after(jiffies +
518 ieee80211_scan_get_channel_time(next_chan),
519 local->leave_oper_channel_time +
520 usecs_to_jiffies(min_beacon_int * 1024) *
521 local->hw.conf.listen_interval);
523 if (associated && ( !tx_empty || bad_latency ||
524 listen_int_exceeded))
525 local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
527 local->next_scan_state = SCAN_SET_CHANNEL;
530 * we're on the operating channel currently, let's
531 * leave that channel now to scan another one
533 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
540 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
541 unsigned long *next_delay)
543 ieee80211_offchannel_stop_station(local);
545 __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
548 * What if the nullfunc frames didn't arrive?
550 drv_flush(local, false);
551 if (local->ops->flush)
554 *next_delay = HZ / 10;
556 /* remember when we left the operating channel */
557 local->leave_oper_channel_time = jiffies;
559 /* advance to the next channel to be scanned */
560 local->next_scan_state = SCAN_SET_CHANNEL;
563 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
564 unsigned long *next_delay)
566 /* switch back to the operating channel */
567 local->scan_channel = NULL;
568 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
571 * Only re-enable station mode interface now; beaconing will be
572 * re-enabled once the full scan has been completed.
574 ieee80211_offchannel_return(local, false);
576 __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
578 *next_delay = HZ / 5;
579 local->next_scan_state = SCAN_DECISION;
582 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
583 unsigned long *next_delay)
586 struct ieee80211_channel *chan;
589 chan = local->scan_req->channels[local->scan_channel_idx];
591 local->scan_channel = chan;
592 if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
595 /* advance state machine to next channel/band */
596 local->scan_channel_idx++;
599 /* if we skip this channel return to the decision state */
600 local->next_scan_state = SCAN_DECISION;
605 * Probe delay is used to update the NAV, cf. 11.1.3.2.2
606 * (which unfortunately doesn't say _why_ step a) is done,
607 * but it waits for the probe delay or until a frame is
608 * received - and the received frame would update the NAV).
609 * For now, we do not support waiting until a frame is
612 * In any case, it is not necessary for a passive scan.
614 if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
615 !local->scan_req->n_ssids) {
616 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
617 local->next_scan_state = SCAN_DECISION;
621 /* active scan, send probes */
622 *next_delay = IEEE80211_PROBE_DELAY;
623 local->next_scan_state = SCAN_SEND_PROBE;
626 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
627 unsigned long *next_delay)
630 struct ieee80211_sub_if_data *sdata = local->scan_sdata;
632 for (i = 0; i < local->scan_req->n_ssids; i++)
633 ieee80211_send_probe_req(
635 local->scan_req->ssids[i].ssid,
636 local->scan_req->ssids[i].ssid_len,
637 local->scan_req->ie, local->scan_req->ie_len);
640 * After sending probe requests, wait for probe responses
643 *next_delay = IEEE80211_CHANNEL_TIME;
644 local->next_scan_state = SCAN_DECISION;
647 void ieee80211_scan_work(struct work_struct *work)
649 struct ieee80211_local *local =
650 container_of(work, struct ieee80211_local, scan_work.work);
651 struct ieee80211_sub_if_data *sdata = local->scan_sdata;
652 unsigned long next_delay = 0;
654 if (test_and_clear_bit(SCAN_COMPLETED, &local->scanning)) {
657 aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
658 __ieee80211_scan_completed(&local->hw, aborted);
662 mutex_lock(&local->mtx);
663 if (!sdata || !local->scan_req) {
664 mutex_unlock(&local->mtx);
668 if (local->hw_scan_req) {
669 int rc = drv_hw_scan(local, sdata, local->hw_scan_req);
670 mutex_unlock(&local->mtx);
672 __ieee80211_scan_completed(&local->hw, true);
676 if (local->scan_req && !local->scanning) {
677 struct cfg80211_scan_request *req = local->scan_req;
680 local->scan_req = NULL;
681 local->scan_sdata = NULL;
683 rc = __ieee80211_start_scan(sdata, req);
684 mutex_unlock(&local->mtx);
687 __ieee80211_scan_completed(&local->hw, true);
691 mutex_unlock(&local->mtx);
694 * Avoid re-scheduling when the sdata is going away.
696 if (!ieee80211_sdata_running(sdata)) {
697 __ieee80211_scan_completed(&local->hw, true);
702 * as long as no delay is required advance immediately
703 * without scheduling a new work
706 switch (local->next_scan_state) {
708 if (ieee80211_scan_state_decision(local, &next_delay))
711 case SCAN_SET_CHANNEL:
712 ieee80211_scan_state_set_channel(local, &next_delay);
714 case SCAN_SEND_PROBE:
715 ieee80211_scan_state_send_probe(local, &next_delay);
717 case SCAN_LEAVE_OPER_CHANNEL:
718 ieee80211_scan_state_leave_oper_channel(local, &next_delay);
720 case SCAN_ENTER_OPER_CHANNEL:
721 ieee80211_scan_state_enter_oper_channel(local, &next_delay);
724 } while (next_delay == 0);
726 ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
729 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
730 struct cfg80211_scan_request *req)
734 mutex_lock(&sdata->local->mtx);
735 res = __ieee80211_start_scan(sdata, req);
736 mutex_unlock(&sdata->local->mtx);
741 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
742 const u8 *ssid, u8 ssid_len,
743 struct ieee80211_channel *chan)
745 struct ieee80211_local *local = sdata->local;
747 enum ieee80211_band band;
749 mutex_lock(&local->mtx);
755 /* fill internal scan request */
759 for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
760 if (!local->hw.wiphy->bands[band])
763 i < local->hw.wiphy->bands[band]->n_channels;
765 local->int_scan_req->channels[nchan] =
766 &local->hw.wiphy->bands[band]->channels[i];
771 local->int_scan_req->n_channels = nchan;
773 local->int_scan_req->channels[0] = chan;
774 local->int_scan_req->n_channels = 1;
777 local->int_scan_req->ssids = &local->scan_ssid;
778 local->int_scan_req->n_ssids = 1;
779 memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
780 local->int_scan_req->ssids[0].ssid_len = ssid_len;
782 ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
784 mutex_unlock(&local->mtx);
788 void ieee80211_scan_cancel(struct ieee80211_local *local)
792 cancel_delayed_work_sync(&local->scan_work);
795 * Only call this function when a scan can't be
796 * queued -- mostly at suspend under RTNL.
798 mutex_lock(&local->mtx);
799 abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
800 (!local->scanning && local->scan_req);
801 mutex_unlock(&local->mtx);
804 __ieee80211_scan_completed(&local->hw, true);