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 /* TODO: figure out how to avoid that the "current BSS" expires */
17 #include <linux/wireless.h>
18 #include <linux/if_arp.h>
19 #include <linux/rtnetlink.h>
20 #include <net/mac80211.h>
21 #include <net/iw_handler.h>
23 #include "ieee80211_i.h"
24 #include "driver-ops.h"
27 #define IEEE80211_PROBE_DELAY (HZ / 33)
28 #define IEEE80211_CHANNEL_TIME (HZ / 33)
29 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 8)
31 struct ieee80211_bss *
32 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
33 u8 *ssid, u8 ssid_len)
35 return (void *)cfg80211_get_bss(local->hw.wiphy,
36 ieee80211_get_channel(local->hw.wiphy,
38 bssid, ssid, ssid_len,
42 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
44 struct ieee80211_bss *bss = (void *)cbss;
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)
53 cfg80211_put_bss((struct cfg80211_bss *)bss);
56 struct ieee80211_bss *
57 ieee80211_bss_info_update(struct ieee80211_local *local,
58 struct ieee80211_rx_status *rx_status,
59 struct ieee80211_mgmt *mgmt,
61 struct ieee802_11_elems *elems,
62 struct ieee80211_channel *channel,
65 struct ieee80211_bss *bss;
69 if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
70 signal = rx_status->signal * 100;
71 else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
72 signal = (rx_status->signal * 100) / local->hw.max_signal;
74 bss = (void *)cfg80211_inform_bss_frame(local->hw.wiphy, channel,
75 mgmt, len, signal, GFP_ATOMIC);
80 bss->cbss.free_priv = ieee80211_rx_bss_free;
82 /* save the ERP value so that it is available at association time */
83 if (elems->erp_info && elems->erp_info_len >= 1) {
84 bss->erp_value = elems->erp_info[0];
85 bss->has_erp_value = 1;
89 struct ieee80211_tim_ie *tim_ie =
90 (struct ieee80211_tim_ie *)elems->tim;
91 bss->dtim_period = tim_ie->dtim_period;
94 /* set default value for buggy APs */
95 if (!elems->tim || bss->dtim_period == 0)
98 bss->supp_rates_len = 0;
99 if (elems->supp_rates) {
100 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
101 if (clen > elems->supp_rates_len)
102 clen = elems->supp_rates_len;
103 memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
105 bss->supp_rates_len += clen;
107 if (elems->ext_supp_rates) {
108 clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
109 if (clen > elems->ext_supp_rates_len)
110 clen = elems->ext_supp_rates_len;
111 memcpy(&bss->supp_rates[bss->supp_rates_len],
112 elems->ext_supp_rates, clen);
113 bss->supp_rates_len += clen;
116 bss->wmm_used = elems->wmm_param || elems->wmm_info;
119 bss->last_probe_resp = jiffies;
125 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
127 struct ieee80211_rx_status *rx_status = IEEE80211_SKB_RXCB(skb);
128 struct ieee80211_mgmt *mgmt;
129 struct ieee80211_bss *bss;
131 struct ieee80211_channel *channel;
135 bool presp, beacon = false;
136 struct ieee802_11_elems elems;
139 return RX_DROP_UNUSABLE;
141 mgmt = (struct ieee80211_mgmt *) skb->data;
142 fc = mgmt->frame_control;
144 if (ieee80211_is_ctl(fc))
148 return RX_DROP_MONITOR;
150 presp = ieee80211_is_probe_resp(fc);
152 /* ignore ProbeResp to foreign address */
153 if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
154 return RX_DROP_MONITOR;
157 elements = mgmt->u.probe_resp.variable;
158 baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
160 beacon = ieee80211_is_beacon(fc);
161 baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
162 elements = mgmt->u.beacon.variable;
165 if (!presp && !beacon)
168 if (baselen > skb->len)
169 return RX_DROP_MONITOR;
171 ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
173 if (elems.ds_params && elems.ds_params_len == 1)
174 freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
176 freq = rx_status->freq;
178 channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
180 if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
181 return RX_DROP_MONITOR;
183 bss = ieee80211_bss_info_update(sdata->local, rx_status,
184 mgmt, skb->len, &elems,
187 ieee80211_rx_bss_put(sdata->local, bss);
194 * inform AP that we will go to sleep so that it will buffer the frames
197 static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata)
199 struct ieee80211_local *local = sdata->local;
202 /* FIXME: what to do when local->pspolling is true? */
204 del_timer_sync(&local->dynamic_ps_timer);
205 cancel_work_sync(&local->dynamic_ps_enable_work);
207 if (local->hw.conf.flags & IEEE80211_CONF_PS) {
209 local->hw.conf.flags &= ~IEEE80211_CONF_PS;
210 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
213 if (!ps || !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
215 * If power save was enabled, no need to send a nullfunc
216 * frame because AP knows that we are sleeping. But if the
217 * hardware is creating the nullfunc frame for power save
218 * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
219 * enabled) and power save was enabled, the firmware just
220 * sent a null frame with power save disabled. So we need
221 * to send a new nullfunc frame to inform the AP that we
222 * are again sleeping.
224 ieee80211_send_nullfunc(local, sdata, 1);
227 /* inform AP that we are awake again, unless power save is enabled */
228 static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
230 struct ieee80211_local *local = sdata->local;
232 if (!local->ps_sdata)
233 ieee80211_send_nullfunc(local, sdata, 0);
236 * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
237 * will send a nullfunc frame with the powersave bit set
238 * even though the AP already knows that we are sleeping.
239 * This could be avoided by sending a null frame with power
240 * save bit disabled before enabling the power save, but
241 * this doesn't gain anything.
243 * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
244 * to send a nullfunc frame because AP already knows that
245 * we are sleeping, let's just enable power save mode in
248 local->hw.conf.flags |= IEEE80211_CONF_PS;
249 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
253 static void ieee80211_restore_scan_ies(struct ieee80211_local *local)
255 kfree(local->scan_req->ie);
256 local->scan_req->ie = local->orig_ies;
257 local->scan_req->ie_len = local->orig_ies_len;
260 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
262 struct ieee80211_local *local = hw_to_local(hw);
263 struct ieee80211_sub_if_data *sdata;
266 mutex_lock(&local->scan_mtx);
268 if (WARN_ON(!local->hw_scanning && !local->sw_scanning)) {
269 mutex_unlock(&local->scan_mtx);
273 if (WARN_ON(!local->scan_req)) {
274 mutex_unlock(&local->scan_mtx);
278 if (local->hw_scanning)
279 ieee80211_restore_scan_ies(local);
281 if (local->scan_req != &local->int_scan_req)
282 cfg80211_scan_done(local->scan_req, aborted);
283 local->scan_req = NULL;
285 was_hw_scan = local->hw_scanning;
286 local->hw_scanning = false;
287 local->sw_scanning = false;
288 local->scan_channel = NULL;
290 /* we only have to protect scan_req and hw/sw scan */
291 mutex_unlock(&local->scan_mtx);
293 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
297 spin_lock_bh(&local->filter_lock);
298 local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
299 drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
300 &local->filter_flags,
303 spin_unlock_bh(&local->filter_lock);
305 drv_sw_scan_complete(local);
307 mutex_lock(&local->iflist_mtx);
308 list_for_each_entry(sdata, &local->interfaces, list) {
309 if (!netif_running(sdata->dev))
312 /* Tell AP we're back */
313 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
314 if (sdata->u.mgd.associated) {
315 ieee80211_scan_ps_disable(sdata);
316 netif_tx_wake_all_queues(sdata->dev);
319 netif_tx_wake_all_queues(sdata->dev);
321 /* re-enable beaconing */
322 if (sdata->vif.type == NL80211_IFTYPE_AP ||
323 sdata->vif.type == NL80211_IFTYPE_ADHOC ||
324 sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
325 ieee80211_bss_info_change_notify(
326 sdata, BSS_CHANGED_BEACON_ENABLED);
328 mutex_unlock(&local->iflist_mtx);
331 ieee80211_recalc_idle(local);
332 ieee80211_mlme_notify_scan_completed(local);
333 ieee80211_ibss_notify_scan_completed(local);
334 ieee80211_mesh_notify_scan_completed(local);
336 EXPORT_SYMBOL(ieee80211_scan_completed);
338 static int ieee80211_start_sw_scan(struct ieee80211_local *local)
340 struct ieee80211_sub_if_data *sdata;
343 * Hardware/driver doesn't support hw_scan, so use software
344 * scanning instead. First send a nullfunc frame with power save
345 * bit on so that AP will buffer the frames for us while we are not
346 * listening, then send probe requests to each channel and wait for
347 * the responses. After all channels are scanned, tune back to the
348 * original channel and send a nullfunc frame with power save bit
349 * off to trigger the AP to send us all the buffered frames.
351 * Note that while local->sw_scanning is true everything else but
352 * nullfunc frames and probe requests will be dropped in
353 * ieee80211_tx_h_check_assoc().
355 drv_sw_scan_start(local);
357 mutex_lock(&local->iflist_mtx);
358 list_for_each_entry(sdata, &local->interfaces, list) {
359 if (!netif_running(sdata->dev))
362 /* disable beaconing */
363 if (sdata->vif.type == NL80211_IFTYPE_AP ||
364 sdata->vif.type == NL80211_IFTYPE_ADHOC ||
365 sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
366 ieee80211_bss_info_change_notify(
367 sdata, BSS_CHANGED_BEACON_ENABLED);
369 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
370 if (sdata->u.mgd.associated) {
371 netif_tx_stop_all_queues(sdata->dev);
372 ieee80211_scan_ps_enable(sdata);
375 netif_tx_stop_all_queues(sdata->dev);
377 mutex_unlock(&local->iflist_mtx);
379 local->scan_state = SCAN_SET_CHANNEL;
380 local->scan_channel_idx = 0;
382 spin_lock_bh(&local->filter_lock);
383 local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
384 drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
385 &local->filter_flags,
388 spin_unlock_bh(&local->filter_lock);
390 /* TODO: start scan as soon as all nullfunc frames are ACKed */
391 queue_delayed_work(local->hw.workqueue, &local->scan_work,
392 IEEE80211_CHANNEL_TIME);
398 static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
399 struct cfg80211_scan_request *req)
401 struct ieee80211_local *local = sdata->local;
402 struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
408 if (local->ops->hw_scan) {
412 ies = kmalloc(2 + IEEE80211_MAX_SSID_LEN +
413 local->scan_ies_len + req->ie_len, GFP_KERNEL);
417 ielen = ieee80211_build_preq_ies(local, ies,
418 req->ie, req->ie_len);
419 local->orig_ies = req->ie;
420 local->orig_ies_len = req->ie_len;
425 local->scan_req = req;
426 local->scan_sdata = sdata;
428 if (req != &local->int_scan_req &&
429 sdata->vif.type == NL80211_IFTYPE_STATION &&
430 !list_empty(&ifmgd->work_list)) {
431 /* actually wait for the work it's doing to finish/time out */
432 set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request);
436 if (local->ops->hw_scan)
437 local->hw_scanning = true;
439 local->sw_scanning = true;
441 * Kicking off the scan need not be protected,
442 * only the scan variable stuff, since now
443 * local->scan_req is assigned and other callers
444 * will abort their scan attempts.
446 * This avoids getting a scan_mtx -> iflist_mtx
447 * dependency, so that the scan completed calls
448 * have more locking freedom.
451 ieee80211_recalc_idle(local);
452 mutex_unlock(&local->scan_mtx);
454 if (local->ops->hw_scan)
455 rc = drv_hw_scan(local, local->scan_req);
457 rc = ieee80211_start_sw_scan(local);
459 mutex_lock(&local->scan_mtx);
462 if (local->ops->hw_scan) {
463 local->hw_scanning = false;
464 ieee80211_restore_scan_ies(local);
466 local->sw_scanning = false;
468 ieee80211_recalc_idle(local);
470 local->scan_req = NULL;
471 local->scan_sdata = NULL;
477 static int ieee80211_scan_state_set_channel(struct ieee80211_local *local,
478 unsigned long *next_delay)
481 struct ieee80211_channel *chan;
482 struct ieee80211_sub_if_data *sdata = local->scan_sdata;
484 /* if no more bands/channels left, complete scan */
485 if (local->scan_channel_idx >= local->scan_req->n_channels) {
486 ieee80211_scan_completed(&local->hw, false);
490 chan = local->scan_req->channels[local->scan_channel_idx];
492 if (chan->flags & IEEE80211_CHAN_DISABLED ||
493 (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
494 chan->flags & IEEE80211_CHAN_NO_IBSS))
498 local->scan_channel = chan;
499 if (ieee80211_hw_config(local,
500 IEEE80211_CONF_CHANGE_CHANNEL))
504 /* advance state machine to next channel/band */
505 local->scan_channel_idx++;
511 * Probe delay is used to update the NAV, cf. 11.1.3.2.2
512 * (which unfortunately doesn't say _why_ step a) is done,
513 * but it waits for the probe delay or until a frame is
514 * received - and the received frame would update the NAV).
515 * For now, we do not support waiting until a frame is
518 * In any case, it is not necessary for a passive scan.
520 if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
521 !local->scan_req->n_ssids) {
522 *next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
526 *next_delay = IEEE80211_PROBE_DELAY;
527 local->scan_state = SCAN_SEND_PROBE;
532 static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
533 unsigned long *next_delay)
536 struct ieee80211_sub_if_data *sdata = local->scan_sdata;
538 for (i = 0; i < local->scan_req->n_ssids; i++)
539 ieee80211_send_probe_req(
541 local->scan_req->ssids[i].ssid,
542 local->scan_req->ssids[i].ssid_len,
543 local->scan_req->ie, local->scan_req->ie_len);
546 * After sending probe requests, wait for probe responses
549 *next_delay = IEEE80211_CHANNEL_TIME;
550 local->scan_state = SCAN_SET_CHANNEL;
553 void ieee80211_scan_work(struct work_struct *work)
555 struct ieee80211_local *local =
556 container_of(work, struct ieee80211_local, scan_work.work);
557 struct ieee80211_sub_if_data *sdata = local->scan_sdata;
558 unsigned long next_delay = 0;
560 mutex_lock(&local->scan_mtx);
561 if (!sdata || !local->scan_req) {
562 mutex_unlock(&local->scan_mtx);
566 if (local->scan_req && !(local->sw_scanning || local->hw_scanning)) {
567 struct cfg80211_scan_request *req = local->scan_req;
570 local->scan_req = NULL;
572 rc = __ieee80211_start_scan(sdata, req);
573 mutex_unlock(&local->scan_mtx);
576 ieee80211_scan_completed(&local->hw, true);
580 mutex_unlock(&local->scan_mtx);
583 * Avoid re-scheduling when the sdata is going away.
585 if (!netif_running(sdata->dev)) {
586 ieee80211_scan_completed(&local->hw, true);
590 switch (local->scan_state) {
591 case SCAN_SET_CHANNEL:
592 if (ieee80211_scan_state_set_channel(local, &next_delay))
595 case SCAN_SEND_PROBE:
596 ieee80211_scan_state_send_probe(local, &next_delay);
600 queue_delayed_work(local->hw.workqueue, &local->scan_work,
604 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
605 struct cfg80211_scan_request *req)
609 mutex_lock(&sdata->local->scan_mtx);
610 res = __ieee80211_start_scan(sdata, req);
611 mutex_unlock(&sdata->local->scan_mtx);
616 int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
617 const u8 *ssid, u8 ssid_len)
619 struct ieee80211_local *local = sdata->local;
622 mutex_lock(&local->scan_mtx);
628 memcpy(local->int_scan_req.ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
629 local->int_scan_req.ssids[0].ssid_len = ssid_len;
631 ret = __ieee80211_start_scan(sdata, &sdata->local->int_scan_req);
633 mutex_unlock(&local->scan_mtx);
637 void ieee80211_scan_cancel(struct ieee80211_local *local)
641 cancel_delayed_work_sync(&local->scan_work);
644 * Only call this function when a scan can't be
645 * queued -- mostly at suspend under RTNL.
647 mutex_lock(&local->scan_mtx);
648 swscan = local->sw_scanning;
649 mutex_unlock(&local->scan_mtx);
652 ieee80211_scan_completed(&local->hw, true);