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 : static int acs_survey_is_sufficient(struct freq_survey *survey);
246 :
247 :
248 156 : static void acs_clean_chan_surveys(struct hostapd_channel_data *chan)
249 : {
250 : struct freq_survey *survey, *tmp;
251 :
252 156 : if (dl_list_empty(&chan->survey_list))
253 303 : return;
254 :
255 54 : dl_list_for_each_safe(survey, tmp, &chan->survey_list,
256 : struct freq_survey, list) {
257 45 : dl_list_del(&survey->list);
258 45 : os_free(survey);
259 : }
260 : }
261 :
262 :
263 20 : static void acs_cleanup(struct hostapd_iface *iface)
264 : {
265 : int i;
266 : struct hostapd_channel_data *chan;
267 :
268 360 : for (i = 0; i < iface->current_mode->num_channels; i++) {
269 340 : chan = &iface->current_mode->channels[i];
270 :
271 340 : if (chan->flag & HOSTAPD_CHAN_SURVEY_LIST_INITIALIZED)
272 156 : acs_clean_chan_surveys(chan);
273 :
274 340 : dl_list_init(&chan->survey_list);
275 340 : chan->flag |= HOSTAPD_CHAN_SURVEY_LIST_INITIALIZED;
276 340 : chan->min_nf = 0;
277 : }
278 :
279 20 : iface->chans_surveyed = 0;
280 20 : iface->acs_num_completed_scans = 0;
281 20 : }
282 :
283 :
284 0 : static void acs_fail(struct hostapd_iface *iface)
285 : {
286 0 : wpa_printf(MSG_ERROR, "ACS: Failed to start");
287 0 : acs_cleanup(iface);
288 0 : hostapd_disable_iface(iface);
289 0 : }
290 :
291 :
292 : static long double
293 0 : acs_survey_interference_factor(struct freq_survey *survey, s8 min_nf)
294 : {
295 : long double factor, busy, total;
296 :
297 0 : if (survey->filled & SURVEY_HAS_CHAN_TIME_BUSY)
298 0 : busy = survey->channel_time_busy;
299 0 : else if (survey->filled & SURVEY_HAS_CHAN_TIME_RX)
300 0 : busy = survey->channel_time_rx;
301 : else {
302 : /* This shouldn't really happen as survey data is checked in
303 : * acs_sanity_check() */
304 0 : wpa_printf(MSG_ERROR, "ACS: Survey data missing");
305 0 : return 0;
306 : }
307 :
308 0 : total = survey->channel_time;
309 :
310 0 : if (survey->filled & SURVEY_HAS_CHAN_TIME_TX) {
311 0 : busy -= survey->channel_time_tx;
312 0 : total -= survey->channel_time_tx;
313 : }
314 :
315 : /* TODO: figure out the best multiplier for noise floor base */
316 0 : factor = pow(10, survey->nf / 5.0L) +
317 0 : (busy / total) *
318 0 : pow(2, pow(10, (long double) survey->nf / 10.0L) -
319 0 : pow(10, (long double) min_nf / 10.0L));
320 :
321 0 : return factor;
322 : }
323 :
324 :
325 : static void
326 0 : acs_survey_chan_interference_factor(struct hostapd_iface *iface,
327 : struct hostapd_channel_data *chan)
328 : {
329 : struct freq_survey *survey;
330 0 : unsigned int i = 0;
331 0 : long double int_factor = 0;
332 0 : unsigned count = 0;
333 :
334 0 : if (dl_list_empty(&chan->survey_list))
335 0 : return;
336 :
337 0 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
338 0 : return;
339 :
340 0 : chan->interference_factor = 0;
341 :
342 0 : dl_list_for_each(survey, &chan->survey_list, struct freq_survey, list)
343 : {
344 0 : i++;
345 :
346 0 : if (!acs_survey_is_sufficient(survey)) {
347 0 : wpa_printf(MSG_DEBUG, "ACS: %d: insufficient data", i);
348 0 : continue;
349 : }
350 :
351 0 : count++;
352 0 : int_factor = acs_survey_interference_factor(survey,
353 0 : iface->lowest_nf);
354 0 : chan->interference_factor += int_factor;
355 0 : wpa_printf(MSG_DEBUG, "ACS: %d: min_nf=%d interference_factor=%Lg nf=%d time=%lu busy=%lu rx=%lu",
356 0 : i, chan->min_nf, int_factor,
357 0 : survey->nf, (unsigned long) survey->channel_time,
358 : (unsigned long) survey->channel_time_busy,
359 : (unsigned long) survey->channel_time_rx);
360 : }
361 :
362 0 : if (!count)
363 0 : return;
364 0 : chan->interference_factor /= count;
365 : }
366 :
367 :
368 18 : static int acs_usable_ht40_chan(struct hostapd_channel_data *chan)
369 : {
370 18 : const int allowed[] = { 36, 44, 52, 60, 100, 108, 116, 124, 132, 149,
371 : 157, 184, 192 };
372 : unsigned int i;
373 :
374 188 : for (i = 0; i < ARRAY_SIZE(allowed); i++)
375 178 : if (chan->chan == allowed[i])
376 8 : return 1;
377 :
378 10 : return 0;
379 : }
380 :
381 :
382 4 : static int acs_usable_vht80_chan(struct hostapd_channel_data *chan)
383 : {
384 4 : const int allowed[] = { 36, 52, 100, 116, 132, 149 };
385 : unsigned int i;
386 :
387 21 : for (i = 0; i < ARRAY_SIZE(allowed); i++)
388 19 : if (chan->chan == allowed[i])
389 2 : return 1;
390 :
391 2 : return 0;
392 : }
393 :
394 :
395 230 : static int acs_survey_is_sufficient(struct freq_survey *survey)
396 : {
397 230 : if (!(survey->filled & SURVEY_HAS_NF)) {
398 0 : wpa_printf(MSG_INFO, "ACS: Survey is missing noise floor");
399 0 : return 0;
400 : }
401 :
402 230 : if (!(survey->filled & SURVEY_HAS_CHAN_TIME)) {
403 230 : wpa_printf(MSG_INFO, "ACS: Survey is missing channel time");
404 230 : return 0;
405 : }
406 :
407 0 : if (!(survey->filled & SURVEY_HAS_CHAN_TIME_BUSY) &&
408 0 : !(survey->filled & SURVEY_HAS_CHAN_TIME_RX)) {
409 0 : wpa_printf(MSG_INFO,
410 : "ACS: Survey is missing RX and busy time (at least one is required)");
411 0 : return 0;
412 : }
413 :
414 0 : return 1;
415 : }
416 :
417 :
418 130 : static int acs_survey_list_is_sufficient(struct hostapd_channel_data *chan)
419 : {
420 : struct freq_survey *survey;
421 130 : int ret = -1;
422 :
423 360 : dl_list_for_each(survey, &chan->survey_list, struct freq_survey, list)
424 : {
425 230 : if (acs_survey_is_sufficient(survey)) {
426 0 : ret = 1;
427 0 : break;
428 : }
429 230 : ret = 0;
430 : }
431 :
432 130 : if (ret == -1)
433 84 : ret = 1; /* no survey list entries */
434 :
435 130 : if (!ret) {
436 46 : wpa_printf(MSG_INFO,
437 : "ACS: Channel %d has insufficient survey data",
438 46 : chan->chan);
439 : }
440 :
441 130 : return ret;
442 : }
443 :
444 :
445 9 : static int acs_surveys_are_sufficient(struct hostapd_iface *iface)
446 : {
447 : int i;
448 : struct hostapd_channel_data *chan;
449 9 : int valid = 0;
450 :
451 165 : for (i = 0; i < iface->current_mode->num_channels; i++) {
452 156 : chan = &iface->current_mode->channels[i];
453 156 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
454 63 : continue;
455 :
456 93 : if (!acs_survey_list_is_sufficient(chan))
457 9 : continue;
458 :
459 84 : valid++;
460 : }
461 :
462 : /* We need at least survey data for one channel */
463 9 : return !!valid;
464 : }
465 :
466 :
467 525 : static int acs_usable_chan(struct hostapd_channel_data *chan)
468 : {
469 525 : if (dl_list_empty(&chan->survey_list))
470 488 : return 0;
471 37 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
472 0 : return 0;
473 37 : if (!acs_survey_list_is_sufficient(chan))
474 37 : return 0;
475 0 : return 1;
476 : }
477 :
478 :
479 580 : static int is_in_chanlist(struct hostapd_iface *iface,
480 : struct hostapd_channel_data *chan)
481 : {
482 580 : if (!iface->conf->acs_ch_list.num)
483 514 : return 1;
484 :
485 66 : return freq_range_list_includes(&iface->conf->acs_ch_list, chan->chan);
486 : }
487 :
488 :
489 9 : static void acs_survey_all_chans_intereference_factor(
490 : struct hostapd_iface *iface)
491 : {
492 : int i;
493 : struct hostapd_channel_data *chan;
494 :
495 165 : for (i = 0; i < iface->current_mode->num_channels; i++) {
496 156 : chan = &iface->current_mode->channels[i];
497 :
498 156 : if (!acs_usable_chan(chan))
499 156 : continue;
500 :
501 0 : if (!is_in_chanlist(iface, chan))
502 0 : continue;
503 :
504 0 : wpa_printf(MSG_DEBUG, "ACS: Survey analysis for channel %d (%d MHz)",
505 0 : chan->chan, chan->freq);
506 :
507 0 : acs_survey_chan_interference_factor(iface, chan);
508 :
509 0 : wpa_printf(MSG_DEBUG, "ACS: * interference factor average: %Lg",
510 : chan->interference_factor);
511 : }
512 9 : }
513 :
514 :
515 265 : static struct hostapd_channel_data *acs_find_chan(struct hostapd_iface *iface,
516 : int freq)
517 : {
518 : struct hostapd_channel_data *chan;
519 : int i;
520 :
521 2011 : for (i = 0; i < iface->current_mode->num_channels; i++) {
522 1973 : chan = &iface->current_mode->channels[i];
523 :
524 1973 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
525 189 : continue;
526 :
527 1784 : if (chan->freq == freq)
528 227 : return chan;
529 : }
530 :
531 38 : return NULL;
532 : }
533 :
534 :
535 127 : static int is_24ghz_mode(enum hostapd_hw_mode mode)
536 : {
537 127 : return mode == HOSTAPD_MODE_IEEE80211B ||
538 : mode == HOSTAPD_MODE_IEEE80211G;
539 : }
540 :
541 :
542 43 : static int is_common_24ghz_chan(int chan)
543 : {
544 43 : return chan == 1 || chan == 6 || chan == 11;
545 : }
546 :
547 :
548 : #ifndef ACS_ADJ_WEIGHT
549 : #define ACS_ADJ_WEIGHT 0.85
550 : #endif /* ACS_ADJ_WEIGHT */
551 :
552 : #ifndef ACS_NEXT_ADJ_WEIGHT
553 : #define ACS_NEXT_ADJ_WEIGHT 0.55
554 : #endif /* ACS_NEXT_ADJ_WEIGHT */
555 :
556 : #ifndef ACS_24GHZ_PREFER_1_6_11
557 : /*
558 : * Select commonly used channels 1, 6, 11 by default even if a neighboring
559 : * channel has a smaller interference factor as long as it is not better by more
560 : * than this multiplier.
561 : */
562 : #define ACS_24GHZ_PREFER_1_6_11 0.8
563 : #endif /* ACS_24GHZ_PREFER_1_6_11 */
564 :
565 : /*
566 : * At this point it's assumed chan->interface_factor has been computed.
567 : * This function should be reusable regardless of interference computation
568 : * option (survey, BSS, spectral, ...). chan->interference factor must be
569 : * summable (i.e., must be always greater than zero).
570 : */
571 : static struct hostapd_channel_data *
572 9 : acs_find_ideal_chan(struct hostapd_iface *iface)
573 : {
574 9 : struct hostapd_channel_data *chan, *adj_chan, *ideal_chan = NULL,
575 9 : *rand_chan = NULL;
576 9 : long double factor, ideal_factor = 0;
577 : int i, j;
578 9 : int n_chans = 1;
579 : unsigned int k;
580 :
581 : /* TODO: HT40- support */
582 :
583 18 : if (iface->conf->ieee80211n &&
584 9 : iface->conf->secondary_channel == -1) {
585 0 : wpa_printf(MSG_ERROR, "ACS: HT40- is not supported yet. Please try HT40+");
586 0 : return NULL;
587 : }
588 :
589 18 : if (iface->conf->ieee80211n &&
590 9 : iface->conf->secondary_channel)
591 3 : n_chans = 2;
592 :
593 10 : if (iface->conf->ieee80211ac &&
594 1 : iface->conf->vht_oper_chwidth == 1)
595 1 : n_chans = 4;
596 :
597 : /* TODO: VHT80+80, VHT160. Update acs_adjust_vht_center_freq() too. */
598 :
599 12 : wpa_printf(MSG_DEBUG, "ACS: Survey analysis for selected bandwidth %d MHz",
600 : n_chans == 1 ? 20 :
601 4 : n_chans == 2 ? 40 :
602 1 : n_chans == 4 ? 80 :
603 : -1);
604 :
605 165 : for (i = 0; i < iface->current_mode->num_channels; i++) {
606 : double total_weight;
607 : struct acs_bias *bias, tmp_bias;
608 :
609 156 : chan = &iface->current_mode->channels[i];
610 :
611 156 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
612 150 : continue;
613 :
614 93 : if (!is_in_chanlist(iface, chan))
615 8 : continue;
616 :
617 : /* HT40 on 5 GHz has a limited set of primary channels as per
618 : * 11n Annex J */
619 112 : if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211A &&
620 54 : iface->conf->ieee80211n &&
621 45 : iface->conf->secondary_channel &&
622 18 : !acs_usable_ht40_chan(chan)) {
623 10 : wpa_printf(MSG_DEBUG, "ACS: Channel %d: not allowed as primary channel for HT40",
624 10 : chan->chan);
625 10 : continue;
626 : }
627 :
628 92 : if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211A &&
629 21 : iface->conf->ieee80211ac &&
630 8 : iface->conf->vht_oper_chwidth == 1 &&
631 4 : !acs_usable_vht80_chan(chan)) {
632 2 : wpa_printf(MSG_DEBUG, "ACS: Channel %d: not allowed as primary channel for VHT80",
633 2 : chan->chan);
634 2 : continue;
635 : }
636 :
637 73 : factor = 0;
638 73 : if (acs_usable_chan(chan))
639 0 : factor = chan->interference_factor;
640 73 : total_weight = 1;
641 :
642 90 : for (j = 1; j < n_chans; j++) {
643 21 : adj_chan = acs_find_chan(iface, chan->freq + (j * 20));
644 21 : if (!adj_chan)
645 4 : break;
646 :
647 17 : if (acs_usable_chan(adj_chan)) {
648 0 : factor += adj_chan->interference_factor;
649 0 : total_weight += 1;
650 : }
651 : }
652 :
653 73 : if (j != n_chans) {
654 4 : wpa_printf(MSG_DEBUG, "ACS: Channel %d: not enough bandwidth",
655 4 : chan->chan);
656 4 : continue;
657 : }
658 :
659 : /* 2.4 GHz has overlapping 20 MHz channels. Include adjacent
660 : * channel interference factor. */
661 69 : if (is_24ghz_mode(iface->current_mode->mode)) {
662 115 : for (j = 0; j < n_chans; j++) {
663 122 : adj_chan = acs_find_chan(iface, chan->freq +
664 61 : (j * 20) - 5);
665 61 : if (adj_chan && acs_usable_chan(adj_chan)) {
666 0 : factor += ACS_ADJ_WEIGHT *
667 0 : adj_chan->interference_factor;
668 0 : total_weight += ACS_ADJ_WEIGHT;
669 : }
670 :
671 122 : adj_chan = acs_find_chan(iface, chan->freq +
672 61 : (j * 20) - 10);
673 61 : if (adj_chan && acs_usable_chan(adj_chan)) {
674 0 : factor += ACS_NEXT_ADJ_WEIGHT *
675 0 : adj_chan->interference_factor;
676 0 : total_weight += ACS_NEXT_ADJ_WEIGHT;
677 : }
678 :
679 122 : adj_chan = acs_find_chan(iface, chan->freq +
680 61 : (j * 20) + 5);
681 61 : if (adj_chan && acs_usable_chan(adj_chan)) {
682 0 : factor += ACS_ADJ_WEIGHT *
683 0 : adj_chan->interference_factor;
684 0 : total_weight += ACS_ADJ_WEIGHT;
685 : }
686 :
687 122 : adj_chan = acs_find_chan(iface, chan->freq +
688 61 : (j * 20) + 10);
689 61 : if (adj_chan && acs_usable_chan(adj_chan)) {
690 0 : factor += ACS_NEXT_ADJ_WEIGHT *
691 0 : adj_chan->interference_factor;
692 0 : total_weight += ACS_NEXT_ADJ_WEIGHT;
693 : }
694 : }
695 : }
696 :
697 69 : factor /= total_weight;
698 :
699 69 : bias = NULL;
700 69 : if (iface->conf->acs_chan_bias) {
701 45 : for (k = 0; k < iface->conf->num_acs_chan_bias; k++) {
702 38 : bias = &iface->conf->acs_chan_bias[k];
703 38 : if (bias->channel == chan->chan)
704 4 : break;
705 34 : bias = NULL;
706 : }
707 101 : } else if (is_24ghz_mode(iface->current_mode->mode) &&
708 43 : is_common_24ghz_chan(chan->chan)) {
709 14 : tmp_bias.channel = chan->chan;
710 14 : tmp_bias.bias = ACS_24GHZ_PREFER_1_6_11;
711 14 : bias = &tmp_bias;
712 : }
713 :
714 69 : if (bias) {
715 18 : factor *= bias->bias;
716 36 : wpa_printf(MSG_DEBUG,
717 : "ACS: * channel %d: total interference = %Lg (%f bias)",
718 18 : chan->chan, factor, bias->bias);
719 : } else {
720 51 : wpa_printf(MSG_DEBUG,
721 : "ACS: * channel %d: total interference = %Lg",
722 51 : chan->chan, factor);
723 : }
724 :
725 69 : if (acs_usable_chan(chan) &&
726 0 : (!ideal_chan || factor < ideal_factor)) {
727 0 : ideal_factor = factor;
728 0 : ideal_chan = chan;
729 : }
730 :
731 : /* This channel would at least be usable */
732 69 : if (!rand_chan)
733 9 : rand_chan = chan;
734 : }
735 :
736 9 : if (ideal_chan) {
737 0 : wpa_printf(MSG_DEBUG, "ACS: Ideal channel is %d (%d MHz) with total interference factor of %Lg",
738 0 : ideal_chan->chan, ideal_chan->freq, ideal_factor);
739 0 : return ideal_chan;
740 : }
741 :
742 9 : return rand_chan;
743 : }
744 :
745 :
746 1 : static void acs_adjust_vht_center_freq(struct hostapd_iface *iface)
747 : {
748 : int offset;
749 :
750 1 : wpa_printf(MSG_DEBUG, "ACS: Adjusting VHT center frequency");
751 :
752 1 : switch (iface->conf->vht_oper_chwidth) {
753 : case VHT_CHANWIDTH_USE_HT:
754 0 : offset = 2 * iface->conf->secondary_channel;
755 0 : break;
756 : case VHT_CHANWIDTH_80MHZ:
757 1 : offset = 6;
758 1 : break;
759 : default:
760 : /* TODO: How can this be calculated? Adjust
761 : * acs_find_ideal_chan() */
762 0 : wpa_printf(MSG_INFO, "ACS: Only VHT20/40/80 is supported now");
763 1 : return;
764 : }
765 :
766 2 : iface->conf->vht_oper_centr_freq_seg0_idx =
767 1 : iface->conf->channel + offset;
768 : }
769 :
770 :
771 9 : static int acs_study_survey_based(struct hostapd_iface *iface)
772 : {
773 9 : wpa_printf(MSG_DEBUG, "ACS: Trying survey-based ACS");
774 :
775 9 : if (!iface->chans_surveyed) {
776 0 : wpa_printf(MSG_ERROR, "ACS: Unable to collect survey data");
777 0 : return -1;
778 : }
779 :
780 9 : if (!acs_surveys_are_sufficient(iface)) {
781 0 : wpa_printf(MSG_ERROR, "ACS: Surveys have insufficient data");
782 0 : return -1;
783 : }
784 :
785 9 : acs_survey_all_chans_intereference_factor(iface);
786 9 : return 0;
787 : }
788 :
789 :
790 9 : static int acs_study_options(struct hostapd_iface *iface)
791 : {
792 : int err;
793 :
794 9 : err = acs_study_survey_based(iface);
795 9 : if (err == 0)
796 9 : return 0;
797 :
798 : /* TODO: If no surveys are available/sufficient this is a good
799 : * place to fallback to BSS-based ACS */
800 :
801 0 : return -1;
802 : }
803 :
804 :
805 9 : static void acs_study(struct hostapd_iface *iface)
806 : {
807 : struct hostapd_channel_data *ideal_chan;
808 : int err;
809 :
810 9 : err = acs_study_options(iface);
811 9 : if (err < 0) {
812 0 : wpa_printf(MSG_ERROR, "ACS: All study options have failed");
813 0 : goto fail;
814 : }
815 :
816 9 : ideal_chan = acs_find_ideal_chan(iface);
817 9 : if (!ideal_chan) {
818 0 : wpa_printf(MSG_ERROR, "ACS: Failed to compute ideal channel");
819 0 : err = -1;
820 0 : goto fail;
821 : }
822 :
823 9 : iface->conf->channel = ideal_chan->chan;
824 :
825 9 : if (iface->conf->ieee80211ac)
826 1 : acs_adjust_vht_center_freq(iface);
827 :
828 9 : err = 0;
829 : fail:
830 : /*
831 : * hostapd_setup_interface_complete() will return -1 on failure,
832 : * 0 on success and 0 is HOSTAPD_CHAN_VALID :)
833 : */
834 9 : if (hostapd_acs_completed(iface, err) == HOSTAPD_CHAN_VALID) {
835 9 : acs_cleanup(iface);
836 18 : return;
837 : }
838 :
839 : /* This can possibly happen if channel parameters (secondary
840 : * channel, center frequencies) are misconfigured */
841 0 : wpa_printf(MSG_ERROR, "ACS: Possibly channel configuration is invalid, please report this along with your config file.");
842 0 : acs_fail(iface);
843 : }
844 :
845 :
846 45 : static void acs_scan_complete(struct hostapd_iface *iface)
847 : {
848 : int err;
849 :
850 45 : iface->scan_cb = NULL;
851 :
852 45 : wpa_printf(MSG_DEBUG, "ACS: Using survey based algorithm (acs_num_scans=%d)",
853 45 : iface->conf->acs_num_scans);
854 :
855 45 : err = hostapd_drv_get_survey(iface->bss[0], 0);
856 45 : if (err) {
857 0 : wpa_printf(MSG_ERROR, "ACS: Failed to get survey data");
858 0 : goto fail;
859 : }
860 :
861 45 : if (++iface->acs_num_completed_scans < iface->conf->acs_num_scans) {
862 36 : err = acs_request_scan(iface);
863 36 : if (err) {
864 0 : wpa_printf(MSG_ERROR, "ACS: Failed to request scan");
865 0 : goto fail;
866 : }
867 :
868 36 : return;
869 : }
870 :
871 9 : acs_study(iface);
872 9 : return;
873 : fail:
874 0 : hostapd_acs_completed(iface, 1);
875 0 : acs_fail(iface);
876 : }
877 :
878 :
879 47 : static int acs_request_scan(struct hostapd_iface *iface)
880 : {
881 : struct wpa_driver_scan_params params;
882 : struct hostapd_channel_data *chan;
883 : int i, *freq;
884 :
885 47 : os_memset(¶ms, 0, sizeof(params));
886 47 : params.freqs = os_calloc(iface->current_mode->num_channels + 1,
887 : sizeof(params.freqs[0]));
888 47 : if (params.freqs == NULL)
889 0 : return -1;
890 :
891 47 : freq = params.freqs;
892 855 : for (i = 0; i < iface->current_mode->num_channels; i++) {
893 808 : chan = &iface->current_mode->channels[i];
894 808 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
895 321 : continue;
896 :
897 487 : if (!is_in_chanlist(iface, chan))
898 40 : continue;
899 :
900 447 : *freq++ = chan->freq;
901 : }
902 47 : *freq = 0;
903 :
904 47 : iface->scan_cb = acs_scan_complete;
905 :
906 94 : wpa_printf(MSG_DEBUG, "ACS: Scanning %d / %d",
907 47 : iface->acs_num_completed_scans + 1,
908 47 : iface->conf->acs_num_scans);
909 :
910 47 : if (hostapd_driver_scan(iface->bss[0], ¶ms) < 0) {
911 0 : wpa_printf(MSG_ERROR, "ACS: Failed to request initial scan");
912 0 : acs_cleanup(iface);
913 0 : os_free(params.freqs);
914 0 : return -1;
915 : }
916 :
917 47 : os_free(params.freqs);
918 47 : return 0;
919 : }
920 :
921 :
922 11 : enum hostapd_chan_status acs_init(struct hostapd_iface *iface)
923 : {
924 : int err;
925 :
926 11 : wpa_printf(MSG_INFO, "ACS: Automatic channel selection started, this may take a bit");
927 :
928 11 : if (iface->drv_flags & WPA_DRIVER_FLAGS_ACS_OFFLOAD) {
929 0 : wpa_printf(MSG_INFO, "ACS: Offloading to driver");
930 0 : err = hostapd_drv_do_acs(iface->bss[0]);
931 0 : if (err)
932 0 : return HOSTAPD_CHAN_INVALID;
933 0 : return HOSTAPD_CHAN_ACS;
934 : }
935 :
936 11 : acs_cleanup(iface);
937 :
938 11 : err = acs_request_scan(iface);
939 11 : if (err < 0)
940 0 : return HOSTAPD_CHAN_INVALID;
941 :
942 11 : hostapd_set_state(iface, HAPD_IFACE_ACS);
943 11 : wpa_msg(iface->bss[0]->msg_ctx, MSG_INFO, ACS_EVENT_STARTED);
944 :
945 11 : return HOSTAPD_CHAN_ACS;
946 : }
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