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 /* replace old supported rates if we get new values */
118 if (elems->supp_rates) {
119 clen = IEEE80211_MAX_SUPP_RATES;
120 if (clen > elems->supp_rates_len)
121 clen = elems->supp_rates_len;
122 memcpy(bss->supp_rates, elems->supp_rates, clen);
125 if (elems->ext_supp_rates) {
126 clen = IEEE80211_MAX_SUPP_RATES - srlen;
127 if (clen > elems->ext_supp_rates_len)
128 clen = elems->ext_supp_rates_len;
129 memcpy(bss->supp_rates + srlen, elems->ext_supp_rates, clen);
133 bss->supp_rates_len = srlen;
135 bss->wmm_used = elems->wmm_param || elems->wmm_info;
136 bss->uapsd_supported = is_uapsd_supported(elems);
139 bss->last_probe_resp = jiffies;
145 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
147 struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
148 struct ieee80211_mgmt *mgmt;
149 struct ieee80211_bss *bss;
151 struct ieee80211_channel *channel;
155 bool presp, beacon = false;
156 struct ieee802_11_elems elems;
159 return RX_DROP_UNUSABLE;
161 mgmt = (struct ieee80211_mgmt *) skb->data;
162 fc = mgmt->frame_control;
164 if (ieee80211_is_ctl(fc))
168 return RX_DROP_MONITOR;
170 presp = ieee80211_is_probe_resp(fc);
172 /* ignore ProbeResp to foreign address */
173 if (memcmp(mgmt->da, sdata->vif.addr, ETH_ALEN))
174 return RX_DROP_MONITOR;
177 elements = mgmt->u.probe_resp.variable;
178 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
180 beacon = ieee80211_is_beacon(fc);
181 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
182 elements = mgmt->u.beacon.variable;
185 if (!presp && !beacon)
188 if (baselen > skb->len)
189 return RX_DROP_MONITOR;
191 ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
193 if (elems.ds_params && elems.ds_params_len == 1)
194 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
196 freq = rx_status->freq;
198 channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
200 if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
201 return RX_DROP_MONITOR;
203 bss = ieee80211_bss_info_update(sdata->local, rx_status,
204 mgmt, skb->len, &elems,
207 ieee80211_rx_bss_put(sdata->local, bss);
213 /* return false if no more work */
214 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
216 struct cfg80211_scan_request *req = local->scan_req;
217 enum ieee80211_band band;
218 int i, ielen, n_chans;
221 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
224 band = local->hw_scan_band;
226 for (i = 0; i < req->n_channels; i++) {
227 if (req->channels[i]->band == band) {
228 local->hw_scan_req->channels[n_chans] =
234 local->hw_scan_band++;
237 local->hw_scan_req->n_channels = n_chans;
239 ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
240 req->ie, req->ie_len, band);
241 local->hw_scan_req->ie_len = ielen;
246 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
248 struct ieee80211_local *local = hw_to_local(hw);
251 trace_api_scan_completed(local, aborted);
253 mutex_lock(&local->scan_mtx);
256 * It's ok to abort a not-yet-running scan (that
257 * we have one at all will be verified by checking
258 * local->scan_req next), but not to complete it
261 if (WARN_ON(!local->scanning && !aborted))
264 if (WARN_ON(!local->scan_req)) {
265 mutex_unlock(&local->scan_mtx);
269 was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
270 if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
271 ieee80211_queue_delayed_work(&local->hw,
272 &local->scan_work, 0);
273 mutex_unlock(&local->scan_mtx);
277 kfree(local->hw_scan_req);
278 local->hw_scan_req = NULL;
280 if (local->scan_req != local->int_scan_req)
281 cfg80211_scan_done(local->scan_req, aborted);
282 local->scan_req = NULL;
283 local->scan_sdata = NULL;
286 local->scan_channel = NULL;
288 /* we only have to protect scan_req and hw/sw scan */
289 mutex_unlock(&local->scan_mtx);
291 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
295 ieee80211_configure_filter(local);
297 drv_sw_scan_complete(local);
299 ieee80211_offchannel_return(local, true);
302 ieee80211_recalc_idle(local);
303 ieee80211_mlme_notify_scan_completed(local);
304 ieee80211_ibss_notify_scan_completed(local);
305 ieee80211_mesh_notify_scan_completed(local);
306 ieee80211_queue_work(&local->hw, &local->work_work);
308 EXPORT_SYMBOL(ieee80211_scan_completed);
310 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
313 * Hardware/driver doesn't support hw_scan, so use software
314 * scanning instead. First send a nullfunc frame with power save
315 * bit on so that AP will buffer the frames for us while we are not
316 * listening, then send probe requests to each channel and wait for
317 * the responses. After all channels are scanned, tune back to the
318 * original channel and send a nullfunc frame with power save bit
319 * off to trigger the AP to send us all the buffered frames.
321 * Note that while local->sw_scanning is true everything else but
322 * nullfunc frames and probe requests will be dropped in
323 * ieee80211_tx_h_check_assoc().
325 drv_sw_scan_start(local);
327 ieee80211_offchannel_stop_beaconing(local);
329 local->leave_oper_channel_time = 0;
330 local->next_scan_state = SCAN_DECISION;
331 local->scan_channel_idx = 0;
333 drv_flush(local, false);
335 ieee80211_configure_filter(local);
337 ieee80211_queue_delayed_work(&local->hw,
339 IEEE80211_CHANNEL_TIME);
345 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
346 struct cfg80211_scan_request *req)
348 struct ieee80211_local *local = sdata->local;
354 if (!list_empty(&local->work_list)) {
355 /* wait for the work to finish/time out */
356 local->scan_req = req;
357 local->scan_sdata = sdata;
361 if (local->ops->hw_scan) {
364 local->hw_scan_req = kmalloc(
365 sizeof(*local->hw_scan_req) +
366 req->n_channels * sizeof(req->channels[0]) +
367 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
368 req->ie_len, GFP_KERNEL);
369 if (!local->hw_scan_req)
372 local->hw_scan_req->ssids = req->ssids;
373 local->hw_scan_req->n_ssids = req->n_ssids;
374 ies = (u8 *)local->hw_scan_req +
375 sizeof(*local->hw_scan_req) +
376 req->n_channels * sizeof(req->channels[0]);
377 local->hw_scan_req->ie = ies;
379 local->hw_scan_band = 0;
382 * After allocating local->hw_scan_req, we must
383 * go through until ieee80211_prep_hw_scan(), so
384 * anything that might be changed here and leave
385 * this function early must not go after this
390 local->scan_req = req;
391 local->scan_sdata = sdata;
393 if (local->ops->hw_scan)
394 __set_bit(SCAN_HW_SCANNING, &local->scanning);
396 __set_bit(SCAN_SW_SCANNING, &local->scanning);
399 * Kicking off the scan need not be protected,
400 * only the scan variable stuff, since now
401 * local->scan_req is assigned and other callers
402 * will abort their scan attempts.
404 * This avoids too many locking dependencies
405 * so that the scan completed calls have more
409 ieee80211_recalc_idle(local);
410 mutex_unlock(&local->scan_mtx);
412 if (local->ops->hw_scan) {
413 WARN_ON(!ieee80211_prep_hw_scan(local));
414 rc = drv_hw_scan(local, sdata, local->hw_scan_req);
416 rc = ieee80211_start_sw_scan(local);
418 mutex_lock(&local->scan_mtx);
421 kfree(local->hw_scan_req);
422 local->hw_scan_req = NULL;
425 ieee80211_recalc_idle(local);
427 local->scan_req = NULL;
428 local->scan_sdata = NULL;
435 ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
438 * TODO: channel switching also consumes quite some time,
439 * add that delay as well to get a better estimation
441 if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN)
442 return IEEE80211_PASSIVE_CHANNEL_TIME;
443 return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
446 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
447 unsigned long *next_delay)
449 bool associated = false;
450 bool tx_empty = true;
452 bool listen_int_exceeded;
453 unsigned long min_beacon_int = 0;
454 struct ieee80211_sub_if_data *sdata;
455 struct ieee80211_channel *next_chan;
457 /* if no more bands/channels left, complete scan and advance to the idle state */
458 if (local->scan_channel_idx >= local->scan_req->n_channels) {
459 ieee80211_scan_completed(&local->hw, false);
464 * check if at least one STA interface is associated,
465 * check if at least one STA interface has pending tx frames
466 * and grab the lowest used beacon interval
468 mutex_lock(&local->iflist_mtx);
469 list_for_each_entry(sdata, &local->interfaces, list) {
470 if (!ieee80211_sdata_running(sdata))
473 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
474 if (sdata->u.mgd.associated) {
477 if (sdata->vif.bss_conf.beacon_int <
478 min_beacon_int || min_beacon_int == 0)
480 sdata->vif.bss_conf.beacon_int;
482 if (!qdisc_all_tx_empty(sdata->dev)) {
489 mutex_unlock(&local->iflist_mtx);
491 if (local->scan_channel) {
493 * we're currently scanning a different channel, let's
494 * see if we can scan another channel without interfering
495 * with the current traffic situation.
497 * Since we don't know if the AP has pending frames for us
498 * we can only check for our tx queues and use the current
499 * pm_qos requirements for rx. Hence, if no tx traffic occurs
500 * at all we will scan as many channels in a row as the pm_qos
501 * latency allows us to. Additionally we also check for the
502 * currently negotiated listen interval to prevent losing
503 * frames unnecessarily.
505 * Otherwise switch back to the operating channel.
507 next_chan = local->scan_req->channels[local->scan_channel_idx];
509 bad_latency = time_after(jiffies +
510 ieee80211_scan_get_channel_time(next_chan),
511 local->leave_oper_channel_time +
512 usecs_to_jiffies(pm_qos_requirement(PM_QOS_NETWORK_LATENCY)));
514 listen_int_exceeded = time_after(jiffies +
515 ieee80211_scan_get_channel_time(next_chan),
516 local->leave_oper_channel_time +
517 usecs_to_jiffies(min_beacon_int * 1024) *
518 local->hw.conf.listen_interval);
520 if (associated && ( !tx_empty || bad_latency ||
521 listen_int_exceeded))
522 local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
524 local->next_scan_state = SCAN_SET_CHANNEL;
527 * we're on the operating channel currently, let's
528 * leave that channel now to scan another one
530 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
537 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
538 unsigned long *next_delay)
540 ieee80211_offchannel_stop_station(local);
542 __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
545 * What if the nullfunc frames didn't arrive?
547 drv_flush(local, false);
548 if (local->ops->flush)
551 *next_delay = HZ / 10;
553 /* remember when we left the operating channel */
554 local->leave_oper_channel_time = jiffies;
556 /* advance to the next channel to be scanned */
557 local->next_scan_state = SCAN_SET_CHANNEL;
560 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
561 unsigned long *next_delay)
563 /* switch back to the operating channel */
564 local->scan_channel = NULL;
565 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
568 * Only re-enable station mode interface now; beaconing will be
569 * re-enabled once the full scan has been completed.
571 ieee80211_offchannel_return(local, false);
573 __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
575 *next_delay = HZ / 5;
576 local->next_scan_state = SCAN_DECISION;
579 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
580 unsigned long *next_delay)
583 struct ieee80211_channel *chan;
586 chan = local->scan_req->channels[local->scan_channel_idx];
588 local->scan_channel = chan;
589 if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
592 /* advance state machine to next channel/band */
593 local->scan_channel_idx++;
596 /* if we skip this channel return to the decision state */
597 local->next_scan_state = SCAN_DECISION;
602 * Probe delay is used to update the NAV, cf. 11.1.3.2.2
603 * (which unfortunately doesn't say _why_ step a) is done,
604 * but it waits for the probe delay or until a frame is
605 * received - and the received frame would update the NAV).
606 * For now, we do not support waiting until a frame is
609 * In any case, it is not necessary for a passive scan.
611 if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
612 !local->scan_req->n_ssids) {
613 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
614 local->next_scan_state = SCAN_DECISION;
618 /* active scan, send probes */
619 *next_delay = IEEE80211_PROBE_DELAY;
620 local->next_scan_state = SCAN_SEND_PROBE;
623 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
624 unsigned long *next_delay)
627 struct ieee80211_sub_if_data *sdata = local->scan_sdata;
629 for (i = 0; i < local->scan_req->n_ssids; i++)
630 ieee80211_send_probe_req(
632 local->scan_req->ssids[i].ssid,
633 local->scan_req->ssids[i].ssid_len,
634 local->scan_req->ie, local->scan_req->ie_len);
637 * After sending probe requests, wait for probe responses
640 *next_delay = IEEE80211_CHANNEL_TIME;
641 local->next_scan_state = SCAN_DECISION;
644 void ieee80211_scan_work(struct work_struct *work)
646 struct ieee80211_local *local =
647 container_of(work, struct ieee80211_local, scan_work.work);
648 struct ieee80211_sub_if_data *sdata = local->scan_sdata;
649 unsigned long next_delay = 0;
651 mutex_lock(&local->scan_mtx);
652 if (!sdata || !local->scan_req) {
653 mutex_unlock(&local->scan_mtx);
657 if (local->hw_scan_req) {
658 int rc = drv_hw_scan(local, sdata, local->hw_scan_req);
659 mutex_unlock(&local->scan_mtx);
661 ieee80211_scan_completed(&local->hw, true);
665 if (local->scan_req && !local->scanning) {
666 struct cfg80211_scan_request *req = local->scan_req;
669 local->scan_req = NULL;
670 local->scan_sdata = NULL;
672 rc = __ieee80211_start_scan(sdata, req);
673 mutex_unlock(&local->scan_mtx);
676 ieee80211_scan_completed(&local->hw, true);
680 mutex_unlock(&local->scan_mtx);
683 * Avoid re-scheduling when the sdata is going away.
685 if (!ieee80211_sdata_running(sdata)) {
686 ieee80211_scan_completed(&local->hw, true);
691 * as long as no delay is required advance immediately
692 * without scheduling a new work
695 switch (local->next_scan_state) {
697 if (ieee80211_scan_state_decision(local, &next_delay))
700 case SCAN_SET_CHANNEL:
701 ieee80211_scan_state_set_channel(local, &next_delay);
703 case SCAN_SEND_PROBE:
704 ieee80211_scan_state_send_probe(local, &next_delay);
706 case SCAN_LEAVE_OPER_CHANNEL:
707 ieee80211_scan_state_leave_oper_channel(local, &next_delay);
709 case SCAN_ENTER_OPER_CHANNEL:
710 ieee80211_scan_state_enter_oper_channel(local, &next_delay);
713 } while (next_delay == 0);
715 ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
718 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
719 struct cfg80211_scan_request *req)
723 mutex_lock(&sdata->local->scan_mtx);
724 res = __ieee80211_start_scan(sdata, req);
725 mutex_unlock(&sdata->local->scan_mtx);
730 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
731 const u8 *ssid, u8 ssid_len,
732 struct ieee80211_channel *chan)
734 struct ieee80211_local *local = sdata->local;
736 enum nl80211_band band;
738 mutex_lock(&local->scan_mtx);
744 /* fill internal scan request */
748 for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
749 if (!local->hw.wiphy->bands[band])
752 i < local->hw.wiphy->bands[band]->n_channels;
754 local->int_scan_req->channels[nchan] =
755 &local->hw.wiphy->bands[band]->channels[i];
760 local->int_scan_req->n_channels = nchan;
762 local->int_scan_req->channels[0] = chan;
763 local->int_scan_req->n_channels = 1;
766 local->int_scan_req->ssids = &local->scan_ssid;
767 local->int_scan_req->n_ssids = 1;
768 memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
769 local->int_scan_req->ssids[0].ssid_len = ssid_len;
771 ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
773 mutex_unlock(&local->scan_mtx);
777 void ieee80211_scan_cancel(struct ieee80211_local *local)
781 cancel_delayed_work_sync(&local->scan_work);
784 * Only call this function when a scan can't be
785 * queued -- mostly at suspend under RTNL.
787 mutex_lock(&local->scan_mtx);
788 abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
789 (!local->scanning && local->scan_req);
790 mutex_unlock(&local->scan_mtx);
793 ieee80211_scan_completed(&local->hw, true);