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 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 struct ieee80211_bss *
59 ieee80211_bss_info_update(struct ieee80211_local *local,
60 struct ieee80211_rx_status *rx_status,
61 struct ieee80211_mgmt *mgmt,
63 struct ieee802_11_elems *elems,
64 struct ieee80211_channel *channel,
67 struct cfg80211_bss *cbss;
68 struct ieee80211_bss *bss;
72 if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
73 signal = rx_status->signal * 100;
74 else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
75 signal = (rx_status->signal * 100) / local->hw.max_signal;
77 cbss = cfg80211_inform_bss_frame(local->hw.wiphy, channel,
78 mgmt, len, signal, GFP_ATOMIC);
83 cbss->free_priv = ieee80211_rx_bss_free;
84 bss = (void *)cbss->priv;
86 /* save the ERP value so that it is available at association time */
87 if (elems->erp_info && elems->erp_info_len >= 1) {
88 bss->erp_value = elems->erp_info[0];
89 bss->has_erp_value = 1;
93 struct ieee80211_tim_ie *tim_ie =
94 (struct ieee80211_tim_ie *)elems->tim;
95 bss->dtim_period = tim_ie->dtim_period;
98 /* set default value for buggy AP/no TIM element */
99 if (bss->dtim_period == 0)
100 bss->dtim_period = 1;
102 bss->supp_rates_len = 0;
103 if (elems->supp_rates) {
104 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
105 if (clen > elems->supp_rates_len)
106 clen = elems->supp_rates_len;
107 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
109 bss->supp_rates_len += clen;
111 if (elems->ext_supp_rates) {
112 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
113 if (clen > elems->ext_supp_rates_len)
114 clen = elems->ext_supp_rates_len;
115 memcpy(&bss->supp_rates[bss->supp_rates_len],
116 elems->ext_supp_rates, clen);
117 bss->supp_rates_len += clen;
120 bss->wmm_used = elems->wmm_param || elems->wmm_info;
123 bss->last_probe_resp = jiffies;
129 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
131 struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
132 struct ieee80211_mgmt *mgmt;
133 struct ieee80211_bss *bss;
135 struct ieee80211_channel *channel;
139 bool presp, beacon = false;
140 struct ieee802_11_elems elems;
143 return RX_DROP_UNUSABLE;
145 mgmt = (struct ieee80211_mgmt *) skb->data;
146 fc = mgmt->frame_control;
148 if (ieee80211_is_ctl(fc))
152 return RX_DROP_MONITOR;
154 presp = ieee80211_is_probe_resp(fc);
156 /* ignore ProbeResp to foreign address */
157 if (memcmp(mgmt->da, sdata->vif.addr, ETH_ALEN))
158 return RX_DROP_MONITOR;
161 elements = mgmt->u.probe_resp.variable;
162 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
164 beacon = ieee80211_is_beacon(fc);
165 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
166 elements = mgmt->u.beacon.variable;
169 if (!presp && !beacon)
172 if (baselen > skb->len)
173 return RX_DROP_MONITOR;
175 ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
177 if (elems.ds_params && elems.ds_params_len == 1)
178 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
180 freq = rx_status->freq;
182 channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
184 if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
185 return RX_DROP_MONITOR;
187 bss = ieee80211_bss_info_update(sdata->local, rx_status,
188 mgmt, skb->len, &elems,
191 ieee80211_rx_bss_put(sdata->local, bss);
197 /* return false if no more work */
198 static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
200 struct cfg80211_scan_request *req = local->scan_req;
201 enum ieee80211_band band;
202 int i, ielen, n_chans;
205 if (local->hw_scan_band == IEEE80211_NUM_BANDS)
208 band = local->hw_scan_band;
210 for (i = 0; i < req->n_channels; i++) {
211 if (req->channels[i]->band == band) {
212 local->hw_scan_req->channels[n_chans] =
218 local->hw_scan_band++;
221 local->hw_scan_req->n_channels = n_chans;
223 ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
224 req->ie, req->ie_len, band);
225 local->hw_scan_req->ie_len = ielen;
230 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
232 struct ieee80211_local *local = hw_to_local(hw);
235 mutex_lock(&local->scan_mtx);
238 * It's ok to abort a not-yet-running scan (that
239 * we have one at all will be verified by checking
240 * local->scan_req next), but not to complete it
243 if (WARN_ON(!local->scanning && !aborted))
246 if (WARN_ON(!local->scan_req)) {
247 mutex_unlock(&local->scan_mtx);
251 was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
252 if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
253 ieee80211_queue_delayed_work(&local->hw,
254 &local->scan_work, 0);
255 mutex_unlock(&local->scan_mtx);
259 kfree(local->hw_scan_req);
260 local->hw_scan_req = NULL;
262 if (local->scan_req != local->int_scan_req)
263 cfg80211_scan_done(local->scan_req, aborted);
264 local->scan_req = NULL;
265 local->scan_sdata = NULL;
268 local->scan_channel = NULL;
270 /* we only have to protect scan_req and hw/sw scan */
271 mutex_unlock(&local->scan_mtx);
273 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
277 ieee80211_configure_filter(local);
279 drv_sw_scan_complete(local);
281 ieee80211_offchannel_return(local, true);
284 ieee80211_recalc_idle(local);
285 ieee80211_mlme_notify_scan_completed(local);
286 ieee80211_ibss_notify_scan_completed(local);
287 ieee80211_mesh_notify_scan_completed(local);
289 EXPORT_SYMBOL(ieee80211_scan_completed);
291 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
294 * Hardware/driver doesn't support hw_scan, so use software
295 * scanning instead. First send a nullfunc frame with power save
296 * bit on so that AP will buffer the frames for us while we are not
297 * listening, then send probe requests to each channel and wait for
298 * the responses. After all channels are scanned, tune back to the
299 * original channel and send a nullfunc frame with power save bit
300 * off to trigger the AP to send us all the buffered frames.
302 * Note that while local->sw_scanning is true everything else but
303 * nullfunc frames and probe requests will be dropped in
304 * ieee80211_tx_h_check_assoc().
306 drv_sw_scan_start(local);
308 ieee80211_offchannel_stop_beaconing(local);
310 local->next_scan_state = SCAN_DECISION;
311 local->scan_channel_idx = 0;
313 drv_flush(local, false);
315 ieee80211_configure_filter(local);
317 ieee80211_queue_delayed_work(&local->hw,
319 IEEE80211_CHANNEL_TIME);
325 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
326 struct cfg80211_scan_request *req)
328 struct ieee80211_local *local = sdata->local;
334 if (local->ops->hw_scan) {
337 local->hw_scan_req = kmalloc(
338 sizeof(*local->hw_scan_req) +
339 req->n_channels * sizeof(req->channels[0]) +
340 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
341 req->ie_len, GFP_KERNEL);
342 if (!local->hw_scan_req)
345 local->hw_scan_req->ssids = req->ssids;
346 local->hw_scan_req->n_ssids = req->n_ssids;
347 ies = (u8 *)local->hw_scan_req +
348 sizeof(*local->hw_scan_req) +
349 req->n_channels * sizeof(req->channels[0]);
350 local->hw_scan_req->ie = ies;
352 local->hw_scan_band = 0;
355 local->scan_req = req;
356 local->scan_sdata = sdata;
358 if (!list_empty(&local->work_list)) {
359 /* wait for the work to finish/time out */
363 if (local->ops->hw_scan)
364 __set_bit(SCAN_HW_SCANNING, &local->scanning);
366 __set_bit(SCAN_SW_SCANNING, &local->scanning);
368 * Kicking off the scan need not be protected,
369 * only the scan variable stuff, since now
370 * local->scan_req is assigned and other callers
371 * will abort their scan attempts.
373 * This avoids getting a scan_mtx -> iflist_mtx
374 * dependency, so that the scan completed calls
375 * have more locking freedom.
378 ieee80211_recalc_idle(local);
379 mutex_unlock(&local->scan_mtx);
381 if (local->ops->hw_scan) {
382 WARN_ON(!ieee80211_prep_hw_scan(local));
383 rc = drv_hw_scan(local, local->hw_scan_req);
385 rc = ieee80211_start_sw_scan(local);
387 mutex_lock(&local->scan_mtx);
390 kfree(local->hw_scan_req);
391 local->hw_scan_req = NULL;
394 ieee80211_recalc_idle(local);
396 local->scan_req = NULL;
397 local->scan_sdata = NULL;
403 static int ieee80211_scan_state_decision(struct ieee80211_local *local,
404 unsigned long *next_delay)
406 bool associated = false;
407 struct ieee80211_sub_if_data *sdata;
409 /* if no more bands/channels left, complete scan and advance to the idle state */
410 if (local->scan_channel_idx >= local->scan_req->n_channels) {
411 ieee80211_scan_completed(&local->hw, false);
415 /* check if at least one STA interface is associated */
416 mutex_lock(&local->iflist_mtx);
417 list_for_each_entry(sdata, &local->interfaces, list) {
418 if (!ieee80211_sdata_running(sdata))
421 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
422 if (sdata->u.mgd.associated) {
428 mutex_unlock(&local->iflist_mtx);
430 if (local->scan_channel) {
432 * we're currently scanning a different channel, let's
433 * switch back to the operating channel now if at least
434 * one interface is associated. Otherwise just scan the
438 local->next_scan_state = SCAN_ENTER_OPER_CHANNEL;
440 local->next_scan_state = SCAN_SET_CHANNEL;
443 * we're on the operating channel currently, let's
444 * leave that channel now to scan another one
446 local->next_scan_state = SCAN_LEAVE_OPER_CHANNEL;
453 static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
454 unsigned long *next_delay)
456 ieee80211_offchannel_stop_station(local);
458 __set_bit(SCAN_OFF_CHANNEL, &local->scanning);
461 * What if the nullfunc frames didn't arrive?
463 drv_flush(local, false);
464 if (local->ops->flush)
467 *next_delay = HZ / 10;
469 /* advance to the next channel to be scanned */
470 local->next_scan_state = SCAN_SET_CHANNEL;
473 static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
474 unsigned long *next_delay)
476 /* switch back to the operating channel */
477 local->scan_channel = NULL;
478 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
481 * Only re-enable station mode interface now; beaconing will be
482 * re-enabled once the full scan has been completed.
484 ieee80211_offchannel_return(local, false);
486 __clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
488 *next_delay = HZ / 5;
489 local->next_scan_state = SCAN_DECISION;
492 static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
493 unsigned long *next_delay)
496 struct ieee80211_channel *chan;
499 chan = local->scan_req->channels[local->scan_channel_idx];
501 local->scan_channel = chan;
502 if (ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL))
505 /* advance state machine to next channel/band */
506 local->scan_channel_idx++;
509 /* if we skip this channel return to the decision state */
510 local->next_scan_state = SCAN_DECISION;
515 * Probe delay is used to update the NAV, cf. 11.1.3.2.2
516 * (which unfortunately doesn't say _why_ step a) is done,
517 * but it waits for the probe delay or until a frame is
518 * received - and the received frame would update the NAV).
519 * For now, we do not support waiting until a frame is
522 * In any case, it is not necessary for a passive scan.
524 if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
525 !local->scan_req->n_ssids) {
526 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
527 local->next_scan_state = SCAN_DECISION;
531 /* active scan, send probes */
532 *next_delay = IEEE80211_PROBE_DELAY;
533 local->next_scan_state = SCAN_SEND_PROBE;
536 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
537 unsigned long *next_delay)
540 struct ieee80211_sub_if_data *sdata = local->scan_sdata;
542 for (i = 0; i < local->scan_req->n_ssids; i++)
543 ieee80211_send_probe_req(
545 local->scan_req->ssids[i].ssid,
546 local->scan_req->ssids[i].ssid_len,
547 local->scan_req->ie, local->scan_req->ie_len);
550 * After sending probe requests, wait for probe responses
553 *next_delay = IEEE80211_CHANNEL_TIME;
554 local->next_scan_state = SCAN_DECISION;
557 void ieee80211_scan_work(struct work_struct *work)
559 struct ieee80211_local *local =
560 container_of(work, struct ieee80211_local, scan_work.work);
561 struct ieee80211_sub_if_data *sdata = local->scan_sdata;
562 unsigned long next_delay = 0;
564 mutex_lock(&local->scan_mtx);
565 if (!sdata || !local->scan_req) {
566 mutex_unlock(&local->scan_mtx);
570 if (local->hw_scan_req) {
571 int rc = drv_hw_scan(local, local->hw_scan_req);
572 mutex_unlock(&local->scan_mtx);
574 ieee80211_scan_completed(&local->hw, true);
578 if (local->scan_req && !local->scanning) {
579 struct cfg80211_scan_request *req = local->scan_req;
582 local->scan_req = NULL;
583 local->scan_sdata = NULL;
585 rc = __ieee80211_start_scan(sdata, req);
586 mutex_unlock(&local->scan_mtx);
589 ieee80211_scan_completed(&local->hw, true);
593 mutex_unlock(&local->scan_mtx);
596 * Avoid re-scheduling when the sdata is going away.
598 if (!ieee80211_sdata_running(sdata)) {
599 ieee80211_scan_completed(&local->hw, true);
604 * as long as no delay is required advance immediately
605 * without scheduling a new work
608 switch (local->next_scan_state) {
610 if (ieee80211_scan_state_decision(local, &next_delay))
613 case SCAN_SET_CHANNEL:
614 ieee80211_scan_state_set_channel(local, &next_delay);
616 case SCAN_SEND_PROBE:
617 ieee80211_scan_state_send_probe(local, &next_delay);
619 case SCAN_LEAVE_OPER_CHANNEL:
620 ieee80211_scan_state_leave_oper_channel(local, &next_delay);
622 case SCAN_ENTER_OPER_CHANNEL:
623 ieee80211_scan_state_enter_oper_channel(local, &next_delay);
626 } while (next_delay == 0);
628 ieee80211_queue_delayed_work(&local->hw, &local->scan_work, next_delay);
631 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
632 struct cfg80211_scan_request *req)
636 mutex_lock(&sdata->local->scan_mtx);
637 res = __ieee80211_start_scan(sdata, req);
638 mutex_unlock(&sdata->local->scan_mtx);
643 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
644 const u8 *ssid, u8 ssid_len)
646 struct ieee80211_local *local = sdata->local;
649 mutex_lock(&local->scan_mtx);
655 memcpy(local->int_scan_req->ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
656 local->int_scan_req->ssids[0].ssid_len = ssid_len;
658 ret = __ieee80211_start_scan(sdata, sdata->local->int_scan_req);
660 mutex_unlock(&local->scan_mtx);
664 void ieee80211_scan_cancel(struct ieee80211_local *local)
668 cancel_delayed_work_sync(&local->scan_work);
671 * Only call this function when a scan can't be
672 * queued -- mostly at suspend under RTNL.
674 mutex_lock(&local->scan_mtx);
675 abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
676 (!local->scanning && local->scan_req);
677 mutex_unlock(&local->scan_mtx);
680 ieee80211_scan_completed(&local->hw, true);