Line data Source code
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 :
244 : static int acs_request_scan(struct hostapd_iface *iface);
245 :
246 :
247 128 : static void acs_clean_chan_surveys(struct hostapd_channel_data *chan)
248 : {
249 : struct freq_survey *survey, *tmp;
250 :
251 128 : if (dl_list_empty(&chan->survey_list))
252 252 : return;
253 :
254 24 : dl_list_for_each_safe(survey, tmp, &chan->survey_list,
255 : struct freq_survey, list) {
256 20 : dl_list_del(&survey->list);
257 20 : os_free(survey);
258 : }
259 : }
260 :
261 :
262 16 : static void acs_cleanup(struct hostapd_iface *iface)
263 : {
264 : int i;
265 : struct hostapd_channel_data *chan;
266 :
267 300 : for (i = 0; i < iface->current_mode->num_channels; i++) {
268 284 : chan = &iface->current_mode->channels[i];
269 :
270 284 : if (chan->flag & HOSTAPD_CHAN_SURVEY_LIST_INITIALIZED)
271 128 : acs_clean_chan_surveys(chan);
272 :
273 284 : dl_list_init(&chan->survey_list);
274 284 : chan->flag |= HOSTAPD_CHAN_SURVEY_LIST_INITIALIZED;
275 284 : chan->min_nf = 0;
276 : }
277 :
278 16 : iface->chans_surveyed = 0;
279 16 : iface->acs_num_completed_scans = 0;
280 16 : }
281 :
282 :
283 3 : static void acs_fail(struct hostapd_iface *iface)
284 : {
285 3 : wpa_printf(MSG_ERROR, "ACS: Failed to start");
286 3 : acs_cleanup(iface);
287 3 : hostapd_disable_iface(iface);
288 3 : }
289 :
290 :
291 : static long double
292 0 : acs_survey_interference_factor(struct freq_survey *survey, s8 min_nf)
293 : {
294 : long double factor, busy, total;
295 :
296 0 : if (survey->filled & SURVEY_HAS_CHAN_TIME_BUSY)
297 0 : busy = survey->channel_time_busy;
298 0 : else if (survey->filled & SURVEY_HAS_CHAN_TIME_RX)
299 0 : busy = survey->channel_time_rx;
300 : else {
301 : /* This shouldn't really happen as survey data is checked in
302 : * acs_sanity_check() */
303 0 : wpa_printf(MSG_ERROR, "ACS: Survey data missing");
304 0 : return 0;
305 : }
306 :
307 0 : total = survey->channel_time;
308 :
309 0 : if (survey->filled & SURVEY_HAS_CHAN_TIME_TX) {
310 0 : busy -= survey->channel_time_tx;
311 0 : total -= survey->channel_time_tx;
312 : }
313 :
314 : /* TODO: figure out the best multiplier for noise floor base */
315 0 : factor = pow(10, survey->nf / 5.0L) +
316 0 : (busy / total) *
317 0 : pow(2, pow(10, (long double) survey->nf / 10.0L) -
318 0 : pow(10, (long double) min_nf / 10.0L));
319 :
320 0 : return factor;
321 : }
322 :
323 :
324 : static void
325 0 : acs_survey_chan_interference_factor(struct hostapd_iface *iface,
326 : struct hostapd_channel_data *chan)
327 : {
328 : struct freq_survey *survey;
329 0 : unsigned int i = 0;
330 0 : long double int_factor = 0;
331 :
332 0 : if (dl_list_empty(&chan->survey_list))
333 0 : return;
334 :
335 0 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
336 0 : return;
337 :
338 0 : chan->interference_factor = 0;
339 :
340 0 : dl_list_for_each(survey, &chan->survey_list, struct freq_survey, list)
341 : {
342 0 : int_factor = acs_survey_interference_factor(survey,
343 0 : iface->lowest_nf);
344 0 : chan->interference_factor += int_factor;
345 0 : wpa_printf(MSG_DEBUG, "ACS: %d: min_nf=%d interference_factor=%Lg nf=%d time=%lu busy=%lu rx=%lu",
346 0 : ++i, chan->min_nf, int_factor,
347 0 : survey->nf, (unsigned long) survey->channel_time,
348 : (unsigned long) survey->channel_time_busy,
349 : (unsigned long) survey->channel_time_rx);
350 : }
351 :
352 0 : chan->interference_factor = chan->interference_factor /
353 0 : dl_list_len(&chan->survey_list);
354 : }
355 :
356 :
357 0 : static int acs_usable_ht40_chan(struct hostapd_channel_data *chan)
358 : {
359 0 : const int allowed[] = { 36, 44, 52, 60, 100, 108, 116, 124, 132, 149,
360 : 157, 184, 192 };
361 : unsigned int i;
362 :
363 0 : for (i = 0; i < ARRAY_SIZE(allowed); i++)
364 0 : if (chan->chan == allowed[i])
365 0 : return 1;
366 :
367 0 : return 0;
368 : }
369 :
370 :
371 0 : static int acs_usable_vht80_chan(struct hostapd_channel_data *chan)
372 : {
373 0 : const int allowed[] = { 36, 52, 100, 116, 132, 149 };
374 : unsigned int i;
375 :
376 0 : for (i = 0; i < ARRAY_SIZE(allowed); i++)
377 0 : if (chan->chan == allowed[i])
378 0 : return 1;
379 :
380 0 : return 0;
381 : }
382 :
383 :
384 24 : static int acs_survey_is_sufficient(struct freq_survey *survey)
385 : {
386 24 : if (!(survey->filled & SURVEY_HAS_NF)) {
387 0 : wpa_printf(MSG_ERROR, "ACS: Survey is missing noise floor");
388 0 : return 0;
389 : }
390 :
391 24 : if (!(survey->filled & SURVEY_HAS_CHAN_TIME)) {
392 24 : wpa_printf(MSG_ERROR, "ACS: Survey is missing channel time");
393 24 : return 0;
394 : }
395 :
396 0 : if (!(survey->filled & SURVEY_HAS_CHAN_TIME_BUSY) &&
397 0 : !(survey->filled & SURVEY_HAS_CHAN_TIME_RX)) {
398 0 : wpa_printf(MSG_ERROR, "ACS: Survey is missing RX and busy time (at least one is required)");
399 0 : return 0;
400 : }
401 :
402 0 : return 1;
403 : }
404 :
405 :
406 68 : static int acs_survey_list_is_sufficient(struct hostapd_channel_data *chan)
407 : {
408 : struct freq_survey *survey;
409 :
410 68 : dl_list_for_each(survey, &chan->survey_list, struct freq_survey, list)
411 : {
412 24 : if (!acs_survey_is_sufficient(survey)) {
413 24 : wpa_printf(MSG_ERROR, "ACS: Channel %d has insufficient survey data",
414 24 : chan->chan);
415 24 : return 0;
416 : }
417 : }
418 :
419 44 : return 1;
420 :
421 : }
422 :
423 :
424 4 : static int acs_surveys_are_sufficient(struct hostapd_iface *iface)
425 : {
426 : int i;
427 : struct hostapd_channel_data *chan;
428 4 : int valid = 0;
429 :
430 60 : for (i = 0; i < iface->current_mode->num_channels; i++) {
431 56 : chan = &iface->current_mode->channels[i];
432 56 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
433 8 : continue;
434 :
435 48 : if (!acs_survey_list_is_sufficient(chan))
436 4 : continue;
437 :
438 44 : valid++;
439 : }
440 :
441 : /* We need at least survey data for one channel */
442 4 : return !!valid;
443 : }
444 :
445 :
446 340 : static int acs_usable_chan(struct hostapd_channel_data *chan)
447 : {
448 340 : if (dl_list_empty(&chan->survey_list))
449 320 : return 0;
450 20 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
451 0 : return 0;
452 20 : if (!acs_survey_list_is_sufficient(chan))
453 20 : return 0;
454 0 : return 1;
455 : }
456 :
457 :
458 4 : static void acs_survey_all_chans_intereference_factor(
459 : struct hostapd_iface *iface)
460 : {
461 : int i;
462 : struct hostapd_channel_data *chan;
463 :
464 60 : for (i = 0; i < iface->current_mode->num_channels; i++) {
465 56 : chan = &iface->current_mode->channels[i];
466 :
467 56 : if (!acs_usable_chan(chan))
468 56 : continue;
469 :
470 0 : wpa_printf(MSG_DEBUG, "ACS: Survey analysis for channel %d (%d MHz)",
471 0 : chan->chan, chan->freq);
472 :
473 0 : acs_survey_chan_interference_factor(iface, chan);
474 :
475 0 : wpa_printf(MSG_DEBUG, "ACS: * interference factor average: %Lg",
476 : chan->interference_factor);
477 : }
478 4 : }
479 :
480 :
481 220 : static struct hostapd_channel_data *acs_find_chan(struct hostapd_iface *iface,
482 : int freq)
483 : {
484 : struct hostapd_channel_data *chan;
485 : int i;
486 :
487 1684 : for (i = 0; i < iface->current_mode->num_channels; i++) {
488 1656 : chan = &iface->current_mode->channels[i];
489 :
490 1656 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
491 56 : continue;
492 :
493 1600 : if (chan->freq == freq)
494 192 : return chan;
495 : }
496 :
497 28 : return NULL;
498 : }
499 :
500 :
501 : /*
502 : * At this point it's assumed chan->interface_factor has been computed.
503 : * This function should be reusable regardless of interference computation
504 : * option (survey, BSS, spectral, ...). chan->interference factor must be
505 : * summable (i.e., must be always greater than zero).
506 : */
507 : static struct hostapd_channel_data *
508 4 : acs_find_ideal_chan(struct hostapd_iface *iface)
509 : {
510 4 : struct hostapd_channel_data *chan, *adj_chan, *ideal_chan = NULL,
511 4 : *rand_chan = NULL;
512 4 : long double factor, ideal_factor = 0;
513 : int i, j;
514 4 : int n_chans = 1;
515 :
516 : /* TODO: HT40- support */
517 :
518 8 : if (iface->conf->ieee80211n &&
519 4 : iface->conf->secondary_channel == -1) {
520 0 : wpa_printf(MSG_ERROR, "ACS: HT40- is not supported yet. Please try HT40+");
521 0 : return NULL;
522 : }
523 :
524 8 : if (iface->conf->ieee80211n &&
525 4 : iface->conf->secondary_channel)
526 1 : n_chans = 2;
527 :
528 4 : if (iface->conf->ieee80211ac &&
529 0 : iface->conf->vht_oper_chwidth == 1)
530 0 : n_chans = 4;
531 :
532 : /* TODO: VHT80+80, VHT160. Update acs_adjust_vht_center_freq() too. */
533 :
534 5 : wpa_printf(MSG_DEBUG, "ACS: Survey analysis for selected bandwidth %d MHz",
535 : n_chans == 1 ? 20 :
536 1 : n_chans == 2 ? 40 :
537 0 : n_chans == 4 ? 80 :
538 : -1);
539 :
540 60 : for (i = 0; i < iface->current_mode->num_channels; i++) {
541 56 : chan = &iface->current_mode->channels[i];
542 :
543 56 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
544 8 : continue;
545 :
546 :
547 : /* HT40 on 5 GHz has a limited set of primary channels as per
548 : * 11n Annex J */
549 48 : if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211A &&
550 0 : iface->conf->ieee80211n &&
551 0 : iface->conf->secondary_channel &&
552 0 : !acs_usable_ht40_chan(chan)) {
553 0 : wpa_printf(MSG_DEBUG, "ACS: Channel %d: not allowed as primary channel for HT40",
554 0 : chan->chan);
555 0 : continue;
556 : }
557 :
558 48 : if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211A &&
559 0 : iface->conf->ieee80211ac &&
560 0 : iface->conf->vht_oper_chwidth == 1 &&
561 0 : !acs_usable_vht80_chan(chan)) {
562 0 : wpa_printf(MSG_DEBUG, "ACS: Channel %d: not allowed as primary channel for VHT80",
563 0 : chan->chan);
564 0 : continue;
565 : }
566 :
567 48 : factor = 0;
568 48 : if (acs_usable_chan(chan))
569 0 : factor = chan->interference_factor;
570 :
571 56 : for (j = 1; j < n_chans; j++) {
572 12 : adj_chan = acs_find_chan(iface, chan->freq + (j * 20));
573 12 : if (!adj_chan)
574 4 : break;
575 :
576 8 : if (acs_usable_chan(adj_chan))
577 0 : factor += adj_chan->interference_factor;
578 : }
579 :
580 48 : if (j != n_chans) {
581 4 : wpa_printf(MSG_DEBUG, "ACS: Channel %d: not enough bandwidth",
582 4 : chan->chan);
583 4 : continue;
584 : }
585 :
586 : /* 2.4 GHz has overlapping 20 MHz channels. Include adjacent
587 : * channel interference factor. */
588 88 : if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211B ||
589 44 : iface->current_mode->mode == HOSTAPD_MODE_IEEE80211G) {
590 96 : for (j = 0; j < n_chans; j++) {
591 : /* TODO: perhaps a multiplier should be used
592 : * here? */
593 :
594 104 : adj_chan = acs_find_chan(iface, chan->freq +
595 52 : (j * 20) - 5);
596 52 : if (adj_chan && acs_usable_chan(adj_chan))
597 0 : factor += adj_chan->interference_factor;
598 :
599 104 : adj_chan = acs_find_chan(iface, chan->freq +
600 52 : (j * 20) - 10);
601 52 : if (adj_chan && acs_usable_chan(adj_chan))
602 0 : factor += adj_chan->interference_factor;
603 :
604 104 : adj_chan = acs_find_chan(iface, chan->freq +
605 52 : (j * 20) + 5);
606 52 : if (adj_chan && acs_usable_chan(adj_chan))
607 0 : factor += adj_chan->interference_factor;
608 :
609 104 : adj_chan = acs_find_chan(iface, chan->freq +
610 52 : (j * 20) + 10);
611 52 : if (adj_chan && acs_usable_chan(adj_chan))
612 0 : factor += adj_chan->interference_factor;
613 : }
614 : }
615 :
616 44 : wpa_printf(MSG_DEBUG, "ACS: * channel %d: total interference = %Lg",
617 44 : chan->chan, factor);
618 :
619 44 : if (acs_usable_chan(chan) &&
620 0 : (!ideal_chan || factor < ideal_factor)) {
621 0 : ideal_factor = factor;
622 0 : ideal_chan = chan;
623 : }
624 :
625 : /* This channel would at least be usable */
626 44 : if (!rand_chan)
627 4 : rand_chan = chan;
628 : }
629 :
630 4 : if (ideal_chan) {
631 0 : wpa_printf(MSG_DEBUG, "ACS: Ideal channel is %d (%d MHz) with total interference factor of %Lg",
632 0 : ideal_chan->chan, ideal_chan->freq, ideal_factor);
633 0 : return ideal_chan;
634 : }
635 :
636 4 : return rand_chan;
637 : }
638 :
639 :
640 0 : static void acs_adjust_vht_center_freq(struct hostapd_iface *iface)
641 : {
642 : int offset;
643 :
644 0 : wpa_printf(MSG_DEBUG, "ACS: Adjusting VHT center frequency");
645 :
646 0 : switch (iface->conf->vht_oper_chwidth) {
647 : case VHT_CHANWIDTH_USE_HT:
648 0 : offset = 2 * iface->conf->secondary_channel;
649 0 : break;
650 : case VHT_CHANWIDTH_80MHZ:
651 0 : offset = 6;
652 0 : break;
653 : default:
654 : /* TODO: How can this be calculated? Adjust
655 : * acs_find_ideal_chan() */
656 0 : wpa_printf(MSG_INFO, "ACS: Only VHT20/40/80 is supported now");
657 0 : return;
658 : }
659 :
660 0 : iface->conf->vht_oper_centr_freq_seg0_idx =
661 0 : iface->conf->channel + offset;
662 : }
663 :
664 :
665 7 : static int acs_study_survey_based(struct hostapd_iface *iface)
666 : {
667 7 : wpa_printf(MSG_DEBUG, "ACS: Trying survey-based ACS");
668 :
669 7 : if (!iface->chans_surveyed) {
670 3 : wpa_printf(MSG_ERROR, "ACS: Unable to collect survey data");
671 3 : return -1;
672 : }
673 :
674 4 : if (!acs_surveys_are_sufficient(iface)) {
675 0 : wpa_printf(MSG_ERROR, "ACS: Surveys have insufficient data");
676 0 : return -1;
677 : }
678 :
679 4 : acs_survey_all_chans_intereference_factor(iface);
680 4 : return 0;
681 : }
682 :
683 :
684 7 : static int acs_study_options(struct hostapd_iface *iface)
685 : {
686 : int err;
687 :
688 7 : err = acs_study_survey_based(iface);
689 7 : if (err == 0)
690 4 : return 0;
691 :
692 : /* TODO: If no surveys are available/sufficient this is a good
693 : * place to fallback to BSS-based ACS */
694 :
695 3 : return -1;
696 : }
697 :
698 :
699 7 : static void acs_study(struct hostapd_iface *iface)
700 : {
701 : struct hostapd_channel_data *ideal_chan;
702 : int err;
703 :
704 7 : err = acs_study_options(iface);
705 7 : if (err < 0) {
706 3 : wpa_printf(MSG_ERROR, "ACS: All study options have failed");
707 3 : goto fail;
708 : }
709 :
710 4 : ideal_chan = acs_find_ideal_chan(iface);
711 4 : if (!ideal_chan) {
712 0 : wpa_printf(MSG_ERROR, "ACS: Failed to compute ideal channel");
713 0 : err = -1;
714 0 : goto fail;
715 : }
716 :
717 4 : iface->conf->channel = ideal_chan->chan;
718 :
719 4 : if (iface->conf->ieee80211ac)
720 0 : acs_adjust_vht_center_freq(iface);
721 :
722 4 : err = 0;
723 : fail:
724 : /*
725 : * hostapd_setup_interface_complete() will return -1 on failure,
726 : * 0 on success and 0 is HOSTAPD_CHAN_VALID :)
727 : */
728 7 : if (hostapd_acs_completed(iface, err) == HOSTAPD_CHAN_VALID) {
729 4 : acs_cleanup(iface);
730 11 : return;
731 : }
732 :
733 : /* This can possibly happen if channel parameters (secondary
734 : * channel, center frequencies) are misconfigured */
735 3 : wpa_printf(MSG_ERROR, "ACS: Possibly channel configuration is invalid, please report this along with your config file.");
736 3 : acs_fail(iface);
737 : }
738 :
739 :
740 35 : static void acs_scan_complete(struct hostapd_iface *iface)
741 : {
742 : int err;
743 :
744 35 : iface->scan_cb = NULL;
745 :
746 35 : wpa_printf(MSG_DEBUG, "ACS: Using survey based algorithm (acs_num_scans=%d)",
747 35 : iface->conf->acs_num_scans);
748 :
749 35 : err = hostapd_drv_get_survey(iface->bss[0], 0);
750 35 : if (err) {
751 0 : wpa_printf(MSG_ERROR, "ACS: Failed to get survey data");
752 0 : goto fail;
753 : }
754 :
755 35 : if (++iface->acs_num_completed_scans < iface->conf->acs_num_scans) {
756 28 : err = acs_request_scan(iface);
757 28 : if (err) {
758 0 : wpa_printf(MSG_ERROR, "ACS: Failed to request scan");
759 0 : goto fail;
760 : }
761 :
762 28 : return;
763 : }
764 :
765 7 : acs_study(iface);
766 7 : return;
767 : fail:
768 0 : hostapd_acs_completed(iface, 1);
769 0 : acs_fail(iface);
770 : }
771 :
772 :
773 37 : static int acs_request_scan(struct hostapd_iface *iface)
774 : {
775 : struct wpa_driver_scan_params params;
776 : struct hostapd_channel_data *chan;
777 : int i, *freq;
778 :
779 37 : os_memset(¶ms, 0, sizeof(params));
780 37 : params.freqs = os_calloc(iface->current_mode->num_channels + 1,
781 : sizeof(params.freqs[0]));
782 37 : if (params.freqs == NULL)
783 0 : return -1;
784 :
785 37 : freq = params.freqs;
786 705 : for (i = 0; i < iface->current_mode->num_channels; i++) {
787 668 : chan = &iface->current_mode->channels[i];
788 668 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
789 269 : continue;
790 :
791 399 : *freq++ = chan->freq;
792 : }
793 37 : *freq = 0;
794 :
795 37 : iface->scan_cb = acs_scan_complete;
796 :
797 74 : wpa_printf(MSG_DEBUG, "ACS: Scanning %d / %d",
798 37 : iface->acs_num_completed_scans + 1,
799 37 : iface->conf->acs_num_scans);
800 :
801 37 : if (hostapd_driver_scan(iface->bss[0], ¶ms) < 0) {
802 0 : wpa_printf(MSG_ERROR, "ACS: Failed to request initial scan");
803 0 : acs_cleanup(iface);
804 0 : os_free(params.freqs);
805 0 : return -1;
806 : }
807 :
808 37 : os_free(params.freqs);
809 37 : return 0;
810 : }
811 :
812 :
813 9 : enum hostapd_chan_status acs_init(struct hostapd_iface *iface)
814 : {
815 : int err;
816 :
817 9 : wpa_printf(MSG_INFO, "ACS: Automatic channel selection started, this may take a bit");
818 :
819 9 : acs_cleanup(iface);
820 :
821 9 : err = acs_request_scan(iface);
822 9 : if (err < 0)
823 0 : return HOSTAPD_CHAN_INVALID;
824 :
825 9 : hostapd_set_state(iface, HAPD_IFACE_ACS);
826 9 : wpa_msg(iface->bss[0]->msg_ctx, MSG_INFO, ACS_EVENT_STARTED);
827 :
828 9 : return HOSTAPD_CHAN_ACS;
829 : }
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