Disconnect hostapd from building in base
[dragonfly.git] / contrib / hostapd / src / ap / acs.c
CommitLineData
4781064b
JM
1/*
2 * ACS - Automatic Channel Selection module
3 * Copyright (c) 2011, Atheros Communications
4 * Copyright (c) 2013, Qualcomm Atheros, Inc.
5 *
6 * This software may be distributed under the terms of the BSD license.
7 * See README for more details.
8 */
9
10#include "utils/includes.h"
11#include <math.h>
12
13#include "utils/common.h"
14#include "utils/list.h"
15#include "common/ieee802_11_defs.h"
16#include "common/wpa_ctrl.h"
17#include "drivers/driver.h"
18#include "hostapd.h"
19#include "ap_drv_ops.h"
20#include "ap_config.h"
21#include "hw_features.h"
22#include "acs.h"
23
24/*
25 * Automatic Channel Selection
26 * ===========================
27 *
28 * More info at
29 * ------------
30 * http://wireless.kernel.org/en/users/Documentation/acs
31 *
32 * How to use
33 * ----------
34 * - make sure you have CONFIG_ACS=y in hostapd's .config
35 * - use channel=0 or channel=acs to enable ACS
36 *
37 * How does it work
38 * ----------------
39 * 1. passive scans are used to collect survey data
40 * (it is assumed that scan trigger collection of survey data in driver)
41 * 2. interference factor is calculated for each channel
42 * 3. ideal channel is picked depending on channel width by using adjacent
43 * channel interference factors
44 *
45 * Known limitations
46 * -----------------
47 * - Current implementation depends heavily on the amount of time willing to
48 * spend gathering survey data during hostapd startup. Short traffic bursts
49 * may be missed and a suboptimal channel may be picked.
50 * - Ideal channel may end up overlapping a channel with 40 MHz intolerant BSS
51 *
52 * Todo / Ideas
53 * ------------
54 * - implement other interference computation methods
55 * - BSS/RSSI based
56 * - spectral scan based
57 * (should be possibly to hook this up with current ACS scans)
58 * - add wpa_supplicant support (for P2P)
59 * - collect a histogram of interference over time allowing more educated
60 * guess about an ideal channel (perhaps CSA could be used to migrate AP to a
61 * new "better" channel while running)
62 * - include neighboring BSS scan to avoid conflicts with 40 MHz intolerant BSSs
63 * when choosing the ideal channel
64 *
65 * Survey interference factor implementation details
66 * -------------------------------------------------
67 * Generic interference_factor in struct hostapd_channel_data is used.
68 *
69 * The survey interference factor is defined as the ratio of the
70 * observed busy time over the time we spent on the channel,
71 * this value is then amplified by the observed noise floor on
72 * the channel in comparison to the lowest noise floor observed
73 * on the entire band.
74 *
75 * This corresponds to:
76 * ---
77 * (busy time - tx time) / (active time - tx time) * 2^(chan_nf + band_min_nf)
78 * ---
79 *
80 * The coefficient of 2 reflects the way power in "far-field"
81 * radiation decreases as the square of distance from the antenna [1].
82 * What this does is it decreases the observed busy time ratio if the
83 * noise observed was low but increases it if the noise was high,
84 * proportionally to the way "far field" radiation changes over
85 * distance.
86 *
87 * If channel busy time is not available the fallback is to use channel RX time.
88 *
89 * Since noise floor is in dBm it is necessary to convert it into Watts so that
90 * combined channel interference (e.g., HT40, which uses two channels) can be
91 * calculated easily.
92 * ---
93 * (busy time - tx time) / (active time - tx time) *
94 * 2^(10^(chan_nf/10) + 10^(band_min_nf/10))
95 * ---
96 *
97 * However to account for cases where busy/rx time is 0 (channel load is then
98 * 0%) channel noise floor signal power is combined into the equation so a
99 * channel with lower noise floor is preferred. The equation becomes:
100 * ---
101 * 10^(chan_nf/5) + (busy time - tx time) / (active time - tx time) *
102 * 2^(10^(chan_nf/10) + 10^(band_min_nf/10))
103 * ---
104 *
105 * All this "interference factor" is purely subjective and only time
106 * will tell how usable this is. By using the minimum noise floor we
107 * remove any possible issues due to card calibration. The computation
108 * of the interference factor then is dependent on what the card itself
109 * picks up as the minimum noise, not an actual real possible card
110 * noise value.
111 *
112 * Total interference computation details
113 * --------------------------------------
114 * The above channel interference factor is calculated with no respect to
115 * target operational bandwidth.
116 *
117 * To find an ideal channel the above data is combined by taking into account
118 * the target operational bandwidth and selected band. E.g., on 2.4 GHz channels
119 * overlap with 20 MHz bandwidth, but there is no overlap for 20 MHz bandwidth
120 * on 5 GHz.
121 *
122 * Each valid and possible channel spec (i.e., channel + width) is taken and its
123 * interference factor is computed by summing up interferences of each channel
124 * it overlaps. The one with least total interference is picked up.
125 *
126 * Note: This implies base channel interference factor must be non-negative
127 * allowing easy summing up.
128 *
129 * Example ACS analysis printout
130 * -----------------------------
131 *
132 * ACS: Trying survey-based ACS
133 * ACS: Survey analysis for channel 1 (2412 MHz)
134 * ACS: 1: min_nf=-113 interference_factor=0.0802469 nf=-113 time=162 busy=0 rx=13
135 * ACS: 2: min_nf=-113 interference_factor=0.0745342 nf=-113 time=161 busy=0 rx=12
136 * ACS: 3: min_nf=-113 interference_factor=0.0679012 nf=-113 time=162 busy=0 rx=11
137 * ACS: 4: min_nf=-113 interference_factor=0.0310559 nf=-113 time=161 busy=0 rx=5
138 * ACS: 5: min_nf=-113 interference_factor=0.0248447 nf=-113 time=161 busy=0 rx=4
139 * ACS: * interference factor average: 0.0557166
140 * ACS: Survey analysis for channel 2 (2417 MHz)
141 * ACS: 1: min_nf=-113 interference_factor=0.0185185 nf=-113 time=162 busy=0 rx=3
142 * ACS: 2: min_nf=-113 interference_factor=0.0246914 nf=-113 time=162 busy=0 rx=4
143 * ACS: 3: min_nf=-113 interference_factor=0.037037 nf=-113 time=162 busy=0 rx=6
144 * ACS: 4: min_nf=-113 interference_factor=0.149068 nf=-113 time=161 busy=0 rx=24
145 * ACS: 5: min_nf=-113 interference_factor=0.0248447 nf=-113 time=161 busy=0 rx=4
146 * ACS: * interference factor average: 0.050832
147 * ACS: Survey analysis for channel 3 (2422 MHz)
148 * ACS: 1: min_nf=-113 interference_factor=2.51189e-23 nf=-113 time=162 busy=0 rx=0
149 * ACS: 2: min_nf=-113 interference_factor=0.0185185 nf=-113 time=162 busy=0 rx=3
150 * ACS: 3: min_nf=-113 interference_factor=0.0186335 nf=-113 time=161 busy=0 rx=3
151 * ACS: 4: min_nf=-113 interference_factor=0.0186335 nf=-113 time=161 busy=0 rx=3
152 * ACS: 5: min_nf=-113 interference_factor=0.0186335 nf=-113 time=161 busy=0 rx=3
153 * ACS: * interference factor average: 0.0148838
154 * ACS: Survey analysis for channel 4 (2427 MHz)
155 * ACS: 1: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0
156 * ACS: 2: min_nf=-114 interference_factor=0.0555556 nf=-114 time=162 busy=0 rx=9
157 * ACS: 3: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=161 busy=0 rx=0
158 * ACS: 4: min_nf=-114 interference_factor=0.0186335 nf=-114 time=161 busy=0 rx=3
159 * ACS: 5: min_nf=-114 interference_factor=0.00621118 nf=-114 time=161 busy=0 rx=1
160 * ACS: * interference factor average: 0.0160801
161 * ACS: Survey analysis for channel 5 (2432 MHz)
162 * ACS: 1: min_nf=-114 interference_factor=0.409938 nf=-113 time=161 busy=0 rx=66
163 * ACS: 2: min_nf=-114 interference_factor=0.0432099 nf=-113 time=162 busy=0 rx=7
164 * ACS: 3: min_nf=-114 interference_factor=0.0124224 nf=-113 time=161 busy=0 rx=2
165 * ACS: 4: min_nf=-114 interference_factor=0.677019 nf=-113 time=161 busy=0 rx=109
166 * ACS: 5: min_nf=-114 interference_factor=0.0186335 nf=-114 time=161 busy=0 rx=3
167 * ACS: * interference factor average: 0.232244
168 * ACS: Survey analysis for channel 6 (2437 MHz)
169 * ACS: 1: min_nf=-113 interference_factor=0.552795 nf=-113 time=161 busy=0 rx=89
170 * ACS: 2: min_nf=-113 interference_factor=0.0807453 nf=-112 time=161 busy=0 rx=13
171 * ACS: 3: min_nf=-113 interference_factor=0.0310559 nf=-113 time=161 busy=0 rx=5
172 * ACS: 4: min_nf=-113 interference_factor=0.434783 nf=-112 time=161 busy=0 rx=70
173 * ACS: 5: min_nf=-113 interference_factor=0.0621118 nf=-113 time=161 busy=0 rx=10
174 * ACS: * interference factor average: 0.232298
175 * ACS: Survey analysis for channel 7 (2442 MHz)
176 * ACS: 1: min_nf=-113 interference_factor=0.440994 nf=-112 time=161 busy=0 rx=71
177 * ACS: 2: min_nf=-113 interference_factor=0.385093 nf=-113 time=161 busy=0 rx=62
178 * ACS: 3: min_nf=-113 interference_factor=0.0372671 nf=-113 time=161 busy=0 rx=6
179 * ACS: 4: min_nf=-113 interference_factor=0.0372671 nf=-113 time=161 busy=0 rx=6
180 * ACS: 5: min_nf=-113 interference_factor=0.0745342 nf=-113 time=161 busy=0 rx=12
181 * ACS: * interference factor average: 0.195031
182 * ACS: Survey analysis for channel 8 (2447 MHz)
183 * ACS: 1: min_nf=-114 interference_factor=0.0496894 nf=-112 time=161 busy=0 rx=8
184 * ACS: 2: min_nf=-114 interference_factor=0.0496894 nf=-114 time=161 busy=0 rx=8
185 * ACS: 3: min_nf=-114 interference_factor=0.0372671 nf=-113 time=161 busy=0 rx=6
186 * ACS: 4: min_nf=-114 interference_factor=0.12963 nf=-113 time=162 busy=0 rx=21
187 * ACS: 5: min_nf=-114 interference_factor=0.166667 nf=-114 time=162 busy=0 rx=27
188 * ACS: * interference factor average: 0.0865885
189 * ACS: Survey analysis for channel 9 (2452 MHz)
190 * ACS: 1: min_nf=-114 interference_factor=0.0124224 nf=-114 time=161 busy=0 rx=2
191 * ACS: 2: min_nf=-114 interference_factor=0.0310559 nf=-114 time=161 busy=0 rx=5
192 * ACS: 3: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=161 busy=0 rx=0
193 * ACS: 4: min_nf=-114 interference_factor=0.00617284 nf=-114 time=162 busy=0 rx=1
194 * ACS: 5: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0
195 * ACS: * interference factor average: 0.00993022
196 * ACS: Survey analysis for channel 10 (2457 MHz)
197 * ACS: 1: min_nf=-114 interference_factor=0.00621118 nf=-114 time=161 busy=0 rx=1
198 * ACS: 2: min_nf=-114 interference_factor=0.00621118 nf=-114 time=161 busy=0 rx=1
199 * ACS: 3: min_nf=-114 interference_factor=0.00621118 nf=-114 time=161 busy=0 rx=1
200 * ACS: 4: min_nf=-114 interference_factor=0.0493827 nf=-114 time=162 busy=0 rx=8
201 * ACS: 5: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0
202 * ACS: * interference factor average: 0.0136033
203 * ACS: Survey analysis for channel 11 (2462 MHz)
204 * ACS: 1: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=161 busy=0 rx=0
205 * ACS: 2: min_nf=-114 interference_factor=2.51189e-23 nf=-113 time=161 busy=0 rx=0
206 * ACS: 3: min_nf=-114 interference_factor=2.51189e-23 nf=-113 time=161 busy=0 rx=0
207 * ACS: 4: min_nf=-114 interference_factor=0.0432099 nf=-114 time=162 busy=0 rx=7
208 * ACS: 5: min_nf=-114 interference_factor=0.0925926 nf=-114 time=162 busy=0 rx=15
209 * ACS: * interference factor average: 0.0271605
210 * ACS: Survey analysis for channel 12 (2467 MHz)
211 * ACS: 1: min_nf=-114 interference_factor=0.0621118 nf=-113 time=161 busy=0 rx=10
212 * ACS: 2: min_nf=-114 interference_factor=0.00621118 nf=-114 time=161 busy=0 rx=1
213 * ACS: 3: min_nf=-114 interference_factor=2.51189e-23 nf=-113 time=162 busy=0 rx=0
214 * ACS: 4: min_nf=-114 interference_factor=2.51189e-23 nf=-113 time=162 busy=0 rx=0
215 * ACS: 5: min_nf=-114 interference_factor=0.00617284 nf=-113 time=162 busy=0 rx=1
216 * ACS: * interference factor average: 0.0148992
217 * ACS: Survey analysis for channel 13 (2472 MHz)
218 * ACS: 1: min_nf=-114 interference_factor=0.0745342 nf=-114 time=161 busy=0 rx=12
219 * ACS: 2: min_nf=-114 interference_factor=0.0555556 nf=-114 time=162 busy=0 rx=9
220 * ACS: 3: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0
221 * ACS: 4: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0
222 * ACS: 5: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0
223 * ACS: * interference factor average: 0.0260179
224 * ACS: Survey analysis for selected bandwidth 20MHz
225 * ACS: * channel 1: total interference = 0.121432
226 * ACS: * channel 2: total interference = 0.137512
227 * ACS: * channel 3: total interference = 0.369757
228 * ACS: * channel 4: total interference = 0.546338
229 * ACS: * channel 5: total interference = 0.690538
230 * ACS: * channel 6: total interference = 0.762242
231 * ACS: * channel 7: total interference = 0.756092
232 * ACS: * channel 8: total interference = 0.537451
233 * ACS: * channel 9: total interference = 0.332313
234 * ACS: * channel 10: total interference = 0.152182
235 * ACS: * channel 11: total interference = 0.0916111
236 * ACS: * channel 12: total interference = 0.0816809
237 * ACS: * channel 13: total interference = 0.0680776
238 * ACS: Ideal channel is 13 (2472 MHz) with total interference factor of 0.0680776
239 *
240 * [1] http://en.wikipedia.org/wiki/Near_and_far_field
241 */
242
243
244static int acs_request_scan(struct hostapd_iface *iface);
245
246
247static void acs_clean_chan_surveys(struct hostapd_channel_data *chan)
248{
249 struct freq_survey *survey, *tmp;
250
251 if (dl_list_empty(&chan->survey_list))
252 return;
253
254 dl_list_for_each_safe(survey, tmp, &chan->survey_list,
255 struct freq_survey, list) {
256 dl_list_del(&survey->list);
257 os_free(survey);
258 }
259}
260
261
262static void acs_cleanup(struct hostapd_iface *iface)
263{
264 int i;
265 struct hostapd_channel_data *chan;
266
267 for (i = 0; i < iface->current_mode->num_channels; i++) {
268 chan = &iface->current_mode->channels[i];
269
270 if (chan->flag & HOSTAPD_CHAN_SURVEY_LIST_INITIALIZED)
271 acs_clean_chan_surveys(chan);
272
273 dl_list_init(&chan->survey_list);
274 chan->flag |= HOSTAPD_CHAN_SURVEY_LIST_INITIALIZED;
275 chan->min_nf = 0;
276 }
277
278 iface->chans_surveyed = 0;
279 iface->acs_num_completed_scans = 0;
280}
281
282
283static void acs_fail(struct hostapd_iface *iface)
284{
285 wpa_printf(MSG_ERROR, "ACS: Failed to start");
286 acs_cleanup(iface);
287}
288
289
290static long double
291acs_survey_interference_factor(struct freq_survey *survey, s8 min_nf)
292{
293 long double factor, busy, total;
294
295 if (survey->filled & SURVEY_HAS_CHAN_TIME_BUSY)
296 busy = survey->channel_time_busy;
297 else if (survey->filled & SURVEY_HAS_CHAN_TIME_RX)
298 busy = survey->channel_time_rx;
299 else {
300 /* This shouldn't really happen as survey data is checked in
301 * acs_sanity_check() */
302 wpa_printf(MSG_ERROR, "ACS: Survey data missing");
303 return 0;
304 }
305
306 total = survey->channel_time;
307
308 if (survey->filled & SURVEY_HAS_CHAN_TIME_TX) {
309 busy -= survey->channel_time_tx;
310 total -= survey->channel_time_tx;
311 }
312
313 /* TODO: figure out the best multiplier for noise floor base */
314 factor = pow(10, survey->nf / 5.0L) +
315 (busy / total) *
316 pow(2, pow(10, (long double) survey->nf / 10.0L) -
317 pow(10, (long double) min_nf / 10.0L));
318
319 return factor;
320}
321
322
323static void
324acs_survey_chan_interference_factor(struct hostapd_iface *iface,
325 struct hostapd_channel_data *chan)
326{
327 struct freq_survey *survey;
328 unsigned int i = 0;
329 long double int_factor = 0;
330
331 if (dl_list_empty(&chan->survey_list))
332 return;
333
334 if (chan->flag & HOSTAPD_CHAN_DISABLED)
335 return;
336
337 chan->interference_factor = 0;
338
339 dl_list_for_each(survey, &chan->survey_list, struct freq_survey, list)
340 {
341 int_factor = acs_survey_interference_factor(survey,
342 iface->lowest_nf);
343 chan->interference_factor += int_factor;
344 wpa_printf(MSG_DEBUG, "ACS: %d: min_nf=%d interference_factor=%Lg nf=%d time=%lu busy=%lu rx=%lu",
345 ++i, chan->min_nf, int_factor,
346 survey->nf, (unsigned long) survey->channel_time,
347 (unsigned long) survey->channel_time_busy,
348 (unsigned long) survey->channel_time_rx);
349 }
350
351 chan->interference_factor = chan->interference_factor /
352 dl_list_len(&chan->survey_list);
353}
354
355
356static int acs_usable_ht40_chan(struct hostapd_channel_data *chan)
357{
358 const int allowed[] = { 36, 44, 52, 60, 100, 108, 116, 124, 132, 149,
359 157, 184, 192 };
360 unsigned int i;
361
362 for (i = 0; i < ARRAY_SIZE(allowed); i++)
363 if (chan->chan == allowed[i])
364 return 1;
365
366 return 0;
367}
368
369
370static int acs_survey_is_sufficient(struct freq_survey *survey)
371{
372 if (!(survey->filled & SURVEY_HAS_NF)) {
373 wpa_printf(MSG_ERROR, "ACS: Survey is missing noise floor");
374 return 0;
375 }
376
377 if (!(survey->filled & SURVEY_HAS_CHAN_TIME)) {
378 wpa_printf(MSG_ERROR, "ACS: Survey is missing channel time");
379 return 0;
380 }
381
382 if (!(survey->filled & SURVEY_HAS_CHAN_TIME_BUSY) &&
383 !(survey->filled & SURVEY_HAS_CHAN_TIME_RX)) {
384 wpa_printf(MSG_ERROR, "ACS: Survey is missing RX and busy time (at least one is required)");
385 return 0;
386 }
387
388 return 1;
389}
390
391
392static int acs_survey_list_is_sufficient(struct hostapd_channel_data *chan)
393{
394 struct freq_survey *survey;
395
396 dl_list_for_each(survey, &chan->survey_list, struct freq_survey, list)
397 {
398 if (!acs_survey_is_sufficient(survey)) {
399 wpa_printf(MSG_ERROR, "ACS: Channel %d has insufficient survey data",
400 chan->chan);
401 return 0;
402 }
403 }
404
405 return 1;
406
407}
408
409
410static int acs_surveys_are_sufficient(struct hostapd_iface *iface)
411{
412 int i;
413 struct hostapd_channel_data *chan;
414 int valid = 0;
415
416 for (i = 0; i < iface->current_mode->num_channels; i++) {
417 chan = &iface->current_mode->channels[i];
418 if (chan->flag & HOSTAPD_CHAN_DISABLED)
419 continue;
420
421 if (!acs_survey_list_is_sufficient(chan))
422 continue;
423
424 valid++;
425 }
426
427 /* We need at least survey data for one channel */
428 return !!valid;
429}
430
431
432static int acs_usable_chan(struct hostapd_channel_data *chan)
433{
434 if (dl_list_empty(&chan->survey_list))
435 return 0;
436 if (chan->flag & HOSTAPD_CHAN_DISABLED)
437 return 0;
438 if (!acs_survey_list_is_sufficient(chan))
439 return 0;
440 return 1;
441}
442
443
444static void acs_survey_all_chans_intereference_factor(
445 struct hostapd_iface *iface)
446{
447 int i;
448 struct hostapd_channel_data *chan;
449
450 for (i = 0; i < iface->current_mode->num_channels; i++) {
451 chan = &iface->current_mode->channels[i];
452
453 if (!acs_usable_chan(chan))
454 continue;
455
456 wpa_printf(MSG_DEBUG, "ACS: Survey analysis for channel %d (%d MHz)",
457 chan->chan, chan->freq);
458
459 acs_survey_chan_interference_factor(iface, chan);
460
461 wpa_printf(MSG_DEBUG, "ACS: * interference factor average: %Lg",
462 chan->interference_factor);
463 }
464}
465
466
467static struct hostapd_channel_data *acs_find_chan(struct hostapd_iface *iface,
468 int freq)
469{
470 struct hostapd_channel_data *chan;
471 int i;
472
473 for (i = 0; i < iface->current_mode->num_channels; i++) {
474 chan = &iface->current_mode->channels[i];
475
476 if (chan->flag & HOSTAPD_CHAN_DISABLED)
477 continue;
478
479 if (chan->freq == freq)
480 return chan;
481 }
482
483 return NULL;
484}
485
486
487/*
488 * At this point it's assumed chan->interface_factor has been computed.
489 * This function should be reusable regardless of interference computation
490 * option (survey, BSS, spectral, ...). chan->interference factor must be
491 * summable (i.e., must be always greater than zero).
492 */
493static struct hostapd_channel_data *
494acs_find_ideal_chan(struct hostapd_iface *iface)
495{
496 struct hostapd_channel_data *chan, *adj_chan, *ideal_chan = NULL,
497 *rand_chan = NULL;
498 long double factor, ideal_factor = 0;
499 int i, j;
500 int n_chans = 1;
501
502 /* TODO: HT40- support */
503
504 if (iface->conf->ieee80211n &&
505 iface->conf->secondary_channel == -1) {
506 wpa_printf(MSG_ERROR, "ACS: HT40- is not supported yet. Please try HT40+");
507 return NULL;
508 }
509
510 if (iface->conf->ieee80211n &&
511 iface->conf->secondary_channel)
512 n_chans = 2;
513
514 if (iface->conf->ieee80211ac &&
515 iface->conf->vht_oper_chwidth == 1)
516 n_chans = 4;
517
518 /* TODO: VHT80+80, VHT160. Update acs_adjust_vht_center_freq() too. */
519
520 wpa_printf(MSG_DEBUG, "ACS: Survey analysis for selected bandwidth %d MHz",
521 n_chans == 1 ? 20 :
522 n_chans == 2 ? 40 :
523 n_chans == 4 ? 80 :
524 -1);
525
526 for (i = 0; i < iface->current_mode->num_channels; i++) {
527 chan = &iface->current_mode->channels[i];
528
529 if (chan->flag & HOSTAPD_CHAN_DISABLED)
530 continue;
531
532
533 /* HT40 on 5 GHz has a limited set of primary channels as per
534 * 11n Annex J */
535 if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211A &&
536 iface->conf->ieee80211n &&
537 iface->conf->secondary_channel &&
538 !acs_usable_ht40_chan(chan)) {
539 wpa_printf(MSG_DEBUG, "ACS: Channel %d: not allowed as primary channel for HT40",
540 chan->chan);
541 continue;
542 }
543
544 factor = 0;
545 if (acs_usable_chan(chan))
546 factor = chan->interference_factor;
547
548 for (j = 1; j < n_chans; j++) {
549 adj_chan = acs_find_chan(iface, chan->freq + (j * 20));
550 if (!adj_chan)
551 break;
552
553 if (acs_usable_chan(adj_chan))
554 factor += adj_chan->interference_factor;
555 }
556
557 if (j != n_chans) {
558 wpa_printf(MSG_DEBUG, "ACS: Channel %d: not enough bandwidth",
559 chan->chan);
560 continue;
561 }
562
563 /* 2.4 GHz has overlapping 20 MHz channels. Include adjacent
564 * channel interference factor. */
565 if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211B ||
566 iface->current_mode->mode == HOSTAPD_MODE_IEEE80211G) {
567 for (j = 0; j < n_chans; j++) {
568 /* TODO: perhaps a multiplier should be used
569 * here? */
570
571 adj_chan = acs_find_chan(iface, chan->freq +
572 (j * 20) - 5);
573 if (adj_chan && acs_usable_chan(adj_chan))
574 factor += adj_chan->interference_factor;
575
576 adj_chan = acs_find_chan(iface, chan->freq +
577 (j * 20) - 10);
578 if (adj_chan && acs_usable_chan(adj_chan))
579 factor += adj_chan->interference_factor;
580
581 adj_chan = acs_find_chan(iface, chan->freq +
582 (j * 20) + 5);
583 if (adj_chan && acs_usable_chan(adj_chan))
584 factor += adj_chan->interference_factor;
585
586 adj_chan = acs_find_chan(iface, chan->freq +
587 (j * 20) + 10);
588 if (adj_chan && acs_usable_chan(adj_chan))
589 factor += adj_chan->interference_factor;
590 }
591 }
592
593 wpa_printf(MSG_DEBUG, "ACS: * channel %d: total interference = %Lg",
594 chan->chan, factor);
595
596 if (acs_usable_chan(chan) &&
597 (!ideal_chan || factor < ideal_factor)) {
598 ideal_factor = factor;
599 ideal_chan = chan;
600 }
601
602 /* This channel would at least be usable */
603 if (!rand_chan)
604 rand_chan = chan;
605 }
606
607 if (ideal_chan) {
608 wpa_printf(MSG_DEBUG, "ACS: Ideal channel is %d (%d MHz) with total interference factor of %Lg",
609 ideal_chan->chan, ideal_chan->freq, ideal_factor);
610 return ideal_chan;
611 }
612
613 return rand_chan;
614}
615
616
617static void acs_adjust_vht_center_freq(struct hostapd_iface *iface)
618{
619 wpa_printf(MSG_DEBUG, "ACS: Adjusting VHT center frequency");
620
621 switch (iface->conf->vht_oper_chwidth) {
622 case VHT_CHANWIDTH_USE_HT:
623 iface->conf->vht_oper_centr_freq_seg0_idx =
624 iface->conf->channel + 2;
625 break;
626 case VHT_CHANWIDTH_80MHZ:
627 iface->conf->vht_oper_centr_freq_seg0_idx =
628 iface->conf->channel + 6;
629 break;
630 default:
631 /* TODO: How can this be calculated? Adjust
632 * acs_find_ideal_chan() */
633 wpa_printf(MSG_INFO, "ACS: Only VHT20/40/80 is supported now");
634 break;
635 }
636}
637
638
639static int acs_study_survey_based(struct hostapd_iface *iface)
640{
641 wpa_printf(MSG_DEBUG, "ACS: Trying survey-based ACS");
642
643 if (!iface->chans_surveyed) {
644 wpa_printf(MSG_ERROR, "ACS: Unable to collect survey data");
645 return -1;
646 }
647
648 if (!acs_surveys_are_sufficient(iface)) {
649 wpa_printf(MSG_ERROR, "ACS: Surveys have insufficient data");
650 return -1;
651 }
652
653 acs_survey_all_chans_intereference_factor(iface);
654 return 0;
655}
656
657
658static int acs_study_options(struct hostapd_iface *iface)
659{
660 int err;
661
662 err = acs_study_survey_based(iface);
663 if (err == 0)
664 return 0;
665
666 /* TODO: If no surveys are available/sufficient this is a good
667 * place to fallback to BSS-based ACS */
668
669 return -1;
670}
671
672
673static void acs_study(struct hostapd_iface *iface)
674{
675 struct hostapd_channel_data *ideal_chan;
676 int err;
677
678 err = acs_study_options(iface);
679 if (err < 0) {
680 wpa_printf(MSG_ERROR, "ACS: All study options have failed");
681 goto fail;
682 }
683
684 ideal_chan = acs_find_ideal_chan(iface);
685 if (!ideal_chan) {
686 wpa_printf(MSG_ERROR, "ACS: Failed to compute ideal channel");
687 err = -1;
688 goto fail;
689 }
690
691 iface->conf->channel = ideal_chan->chan;
692
693 if (iface->conf->ieee80211ac)
694 acs_adjust_vht_center_freq(iface);
695
696 err = 0;
697fail:
698 /*
699 * hostapd_setup_interface_complete() will return -1 on failure,
700 * 0 on success and 0 is HOSTAPD_CHAN_VALID :)
701 */
702 if (hostapd_acs_completed(iface, err) == HOSTAPD_CHAN_VALID) {
703 acs_cleanup(iface);
704 return;
705 }
706
707 /* This can possibly happen if channel parameters (secondary
708 * channel, center frequencies) are misconfigured */
709 wpa_printf(MSG_ERROR, "ACS: Possibly channel configuration is invalid, please report this along with your config file.");
710 acs_fail(iface);
711}
712
713
714static void acs_scan_complete(struct hostapd_iface *iface)
715{
716 int err;
717
718 iface->scan_cb = NULL;
719
720 wpa_printf(MSG_DEBUG, "ACS: Using survey based algorithm (acs_num_scans=%d)",
721 iface->conf->acs_num_scans);
722
723 err = hostapd_drv_get_survey(iface->bss[0], 0);
724 if (err) {
725 wpa_printf(MSG_ERROR, "ACS: Failed to get survey data");
726 acs_fail(iface);
727 }
728
729 if (++iface->acs_num_completed_scans < iface->conf->acs_num_scans) {
730 err = acs_request_scan(iface);
731 if (err) {
732 wpa_printf(MSG_ERROR, "ACS: Failed to request scan");
733 goto fail;
734 }
735
736 return;
737 }
738
739 acs_study(iface);
740 return;
741fail:
742 hostapd_acs_completed(iface, 1);
743 acs_fail(iface);
744}
745
746
747static int acs_request_scan(struct hostapd_iface *iface)
748{
749 struct wpa_driver_scan_params params;
750 struct hostapd_channel_data *chan;
751 int i, *freq;
752
753 os_memset(&params, 0, sizeof(params));
754 params.freqs = os_calloc(iface->current_mode->num_channels + 1,
755 sizeof(params.freqs[0]));
756 if (params.freqs == NULL)
757 return -1;
758
759 freq = params.freqs;
760 for (i = 0; i < iface->current_mode->num_channels; i++) {
761 chan = &iface->current_mode->channels[i];
762 if (chan->flag & HOSTAPD_CHAN_DISABLED)
763 continue;
764
765 *freq++ = chan->freq;
766 }
767 *freq = 0;
768
769 iface->scan_cb = acs_scan_complete;
770
771 wpa_printf(MSG_DEBUG, "ACS: Scanning %d / %d",
772 iface->acs_num_completed_scans + 1,
773 iface->conf->acs_num_scans);
774
775 if (hostapd_driver_scan(iface->bss[0], &params) < 0) {
776 wpa_printf(MSG_ERROR, "ACS: Failed to request initial scan");
777 acs_cleanup(iface);
778 return -1;
779 }
780
781 os_free(params.freqs);
782 return 0;
783}
784
785
786enum hostapd_chan_status acs_init(struct hostapd_iface *iface)
787{
788 int err;
789
790 wpa_printf(MSG_INFO, "ACS: Automatic channel selection started, this may take a bit");
791
792 acs_cleanup(iface);
793
794 err = acs_request_scan(iface);
795 if (err < 0)
796 return HOSTAPD_CHAN_INVALID;
797
798 hostapd_set_state(iface, HAPD_IFACE_ACS);
799 wpa_msg(iface->bss[0]->msg_ctx, MSG_INFO, ACS_EVENT_STARTED);
800
801 return HOSTAPD_CHAN_ACS;
802}