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 :
248 142 : static void acs_clean_chan_surveys(struct hostapd_channel_data *chan)
249 : {
250 : struct freq_survey *survey, *tmp;
251 :
252 142 : if (dl_list_empty(&chan->survey_list))
253 276 : return;
254 :
255 48 : dl_list_for_each_safe(survey, tmp, &chan->survey_list,
256 : struct freq_survey, list) {
257 40 : dl_list_del(&survey->list);
258 40 : os_free(survey);
259 : }
260 : }
261 :
262 :
263 18 : static void acs_cleanup(struct hostapd_iface *iface)
264 : {
265 : int i;
266 : struct hostapd_channel_data *chan;
267 :
268 330 : for (i = 0; i < iface->current_mode->num_channels; i++) {
269 312 : chan = &iface->current_mode->channels[i];
270 :
271 312 : if (chan->flag & HOSTAPD_CHAN_SURVEY_LIST_INITIALIZED)
272 142 : acs_clean_chan_surveys(chan);
273 :
274 312 : dl_list_init(&chan->survey_list);
275 312 : chan->flag |= HOSTAPD_CHAN_SURVEY_LIST_INITIALIZED;
276 312 : chan->min_nf = 0;
277 : }
278 :
279 18 : iface->chans_surveyed = 0;
280 18 : iface->acs_num_completed_scans = 0;
281 18 : }
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 :
395 210 : static int acs_survey_is_sufficient(struct freq_survey *survey)
396 : {
397 210 : if (!(survey->filled & SURVEY_HAS_NF)) {
398 0 : wpa_printf(MSG_INFO, "ACS: Survey is missing noise floor");
399 0 : return 0;
400 : }
401 :
402 210 : if (!(survey->filled & SURVEY_HAS_CHAN_TIME)) {
403 210 : wpa_printf(MSG_INFO, "ACS: Survey is missing channel time");
404 210 : 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 :
418 116 : static int acs_survey_list_is_sufficient(struct hostapd_channel_data *chan)
419 : {
420 : struct freq_survey *survey;
421 116 : int ret = -1;
422 :
423 326 : dl_list_for_each(survey, &chan->survey_list, struct freq_survey, list)
424 : {
425 210 : if (acs_survey_is_sufficient(survey)) {
426 0 : ret = 1;
427 0 : break;
428 : }
429 210 : ret = 0;
430 : }
431 :
432 116 : if (ret == -1)
433 74 : ret = 1; /* no survey list entries */
434 :
435 116 : if (!ret) {
436 42 : wpa_printf(MSG_INFO,
437 : "ACS: Channel %d has insufficient survey data",
438 42 : chan->chan);
439 : }
440 :
441 116 : return ret;
442 : }
443 :
444 :
445 8 : static int acs_surveys_are_sufficient(struct hostapd_iface *iface)
446 : {
447 : int i;
448 : struct hostapd_channel_data *chan;
449 8 : int valid = 0;
450 :
451 150 : for (i = 0; i < iface->current_mode->num_channels; i++) {
452 142 : chan = &iface->current_mode->channels[i];
453 142 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
454 60 : continue;
455 :
456 82 : if (!acs_survey_list_is_sufficient(chan))
457 8 : continue;
458 :
459 74 : valid++;
460 : }
461 :
462 : /* We need at least survey data for one channel */
463 8 : return !!valid;
464 : }
465 :
466 :
467 497 : static int acs_usable_chan(struct hostapd_channel_data *chan)
468 : {
469 497 : if (dl_list_empty(&chan->survey_list))
470 463 : return 0;
471 34 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
472 0 : return 0;
473 34 : if (!acs_survey_list_is_sufficient(chan))
474 34 : return 0;
475 0 : return 1;
476 : }
477 :
478 :
479 82 : static int is_in_chanlist(struct hostapd_iface *iface,
480 : struct hostapd_channel_data *chan)
481 : {
482 : int *entry;
483 :
484 82 : if (!iface->conf->chanlist)
485 82 : return 1;
486 :
487 0 : for (entry = iface->conf->chanlist; *entry != -1; entry++) {
488 0 : if (*entry == chan->chan)
489 0 : return 1;
490 : }
491 0 : return 0;
492 : }
493 :
494 :
495 8 : static void acs_survey_all_chans_intereference_factor(
496 : struct hostapd_iface *iface)
497 : {
498 : int i;
499 : struct hostapd_channel_data *chan;
500 :
501 150 : for (i = 0; i < iface->current_mode->num_channels; i++) {
502 142 : chan = &iface->current_mode->channels[i];
503 :
504 142 : if (!acs_usable_chan(chan))
505 142 : continue;
506 :
507 0 : if (!is_in_chanlist(iface, chan))
508 0 : continue;
509 :
510 0 : wpa_printf(MSG_DEBUG, "ACS: Survey analysis for channel %d (%d MHz)",
511 0 : chan->chan, chan->freq);
512 :
513 0 : acs_survey_chan_interference_factor(iface, chan);
514 :
515 0 : wpa_printf(MSG_DEBUG, "ACS: * interference factor average: %Lg",
516 : chan->interference_factor);
517 : }
518 8 : }
519 :
520 :
521 253 : static struct hostapd_channel_data *acs_find_chan(struct hostapd_iface *iface,
522 : int freq)
523 : {
524 : struct hostapd_channel_data *chan;
525 : int i;
526 :
527 1903 : for (i = 0; i < iface->current_mode->num_channels; i++) {
528 1869 : chan = &iface->current_mode->channels[i];
529 :
530 1869 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
531 177 : continue;
532 :
533 1692 : if (chan->freq == freq)
534 219 : return chan;
535 : }
536 :
537 34 : return NULL;
538 : }
539 :
540 :
541 121 : static int is_24ghz_mode(enum hostapd_hw_mode mode)
542 : {
543 121 : return mode == HOSTAPD_MODE_IEEE80211B ||
544 : mode == HOSTAPD_MODE_IEEE80211G;
545 : }
546 :
547 :
548 40 : static int is_common_24ghz_chan(int chan)
549 : {
550 40 : return chan == 1 || chan == 6 || chan == 11;
551 : }
552 :
553 :
554 : #ifndef ACS_ADJ_WEIGHT
555 : #define ACS_ADJ_WEIGHT 0.85
556 : #endif /* ACS_ADJ_WEIGHT */
557 :
558 : #ifndef ACS_NEXT_ADJ_WEIGHT
559 : #define ACS_NEXT_ADJ_WEIGHT 0.55
560 : #endif /* ACS_NEXT_ADJ_WEIGHT */
561 :
562 : #ifndef ACS_24GHZ_PREFER_1_6_11
563 : /*
564 : * Select commonly used channels 1, 6, 11 by default even if a neighboring
565 : * channel has a smaller interference factor as long as it is not better by more
566 : * than this multiplier.
567 : */
568 : #define ACS_24GHZ_PREFER_1_6_11 0.8
569 : #endif /* ACS_24GHZ_PREFER_1_6_11 */
570 :
571 : /*
572 : * At this point it's assumed chan->interface_factor has been computed.
573 : * This function should be reusable regardless of interference computation
574 : * option (survey, BSS, spectral, ...). chan->interference factor must be
575 : * summable (i.e., must be always greater than zero).
576 : */
577 : static struct hostapd_channel_data *
578 8 : acs_find_ideal_chan(struct hostapd_iface *iface)
579 : {
580 8 : struct hostapd_channel_data *chan, *adj_chan, *ideal_chan = NULL,
581 8 : *rand_chan = NULL;
582 8 : long double factor, ideal_factor = 0;
583 : int i, j;
584 8 : int n_chans = 1;
585 : unsigned int k;
586 :
587 : /* TODO: HT40- support */
588 :
589 16 : if (iface->conf->ieee80211n &&
590 8 : iface->conf->secondary_channel == -1) {
591 0 : wpa_printf(MSG_ERROR, "ACS: HT40- is not supported yet. Please try HT40+");
592 0 : return NULL;
593 : }
594 :
595 16 : if (iface->conf->ieee80211n &&
596 8 : iface->conf->secondary_channel)
597 3 : n_chans = 2;
598 :
599 9 : if (iface->conf->ieee80211ac &&
600 1 : iface->conf->vht_oper_chwidth == 1)
601 1 : n_chans = 4;
602 :
603 : /* TODO: VHT80+80, VHT160. Update acs_adjust_vht_center_freq() too. */
604 :
605 11 : wpa_printf(MSG_DEBUG, "ACS: Survey analysis for selected bandwidth %d MHz",
606 : n_chans == 1 ? 20 :
607 4 : n_chans == 2 ? 40 :
608 1 : n_chans == 4 ? 80 :
609 : -1);
610 :
611 150 : for (i = 0; i < iface->current_mode->num_channels; i++) {
612 : double total_weight;
613 : struct acs_bias *bias, tmp_bias;
614 :
615 142 : chan = &iface->current_mode->channels[i];
616 :
617 142 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
618 136 : continue;
619 :
620 82 : if (!is_in_chanlist(iface, chan))
621 0 : continue;
622 :
623 : /* HT40 on 5 GHz has a limited set of primary channels as per
624 : * 11n Annex J */
625 109 : if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211A &&
626 54 : iface->conf->ieee80211n &&
627 45 : iface->conf->secondary_channel &&
628 18 : !acs_usable_ht40_chan(chan)) {
629 10 : wpa_printf(MSG_DEBUG, "ACS: Channel %d: not allowed as primary channel for HT40",
630 10 : chan->chan);
631 10 : continue;
632 : }
633 :
634 89 : if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211A &&
635 21 : iface->conf->ieee80211ac &&
636 8 : iface->conf->vht_oper_chwidth == 1 &&
637 4 : !acs_usable_vht80_chan(chan)) {
638 2 : wpa_printf(MSG_DEBUG, "ACS: Channel %d: not allowed as primary channel for VHT80",
639 2 : chan->chan);
640 2 : continue;
641 : }
642 :
643 70 : factor = 0;
644 70 : if (acs_usable_chan(chan))
645 0 : factor = chan->interference_factor;
646 70 : total_weight = 1;
647 :
648 87 : for (j = 1; j < n_chans; j++) {
649 21 : adj_chan = acs_find_chan(iface, chan->freq + (j * 20));
650 21 : if (!adj_chan)
651 4 : break;
652 :
653 17 : if (acs_usable_chan(adj_chan)) {
654 0 : factor += adj_chan->interference_factor;
655 0 : total_weight += 1;
656 : }
657 : }
658 :
659 70 : if (j != n_chans) {
660 4 : wpa_printf(MSG_DEBUG, "ACS: Channel %d: not enough bandwidth",
661 4 : chan->chan);
662 4 : continue;
663 : }
664 :
665 : /* 2.4 GHz has overlapping 20 MHz channels. Include adjacent
666 : * channel interference factor. */
667 66 : if (is_24ghz_mode(iface->current_mode->mode)) {
668 109 : for (j = 0; j < n_chans; j++) {
669 116 : adj_chan = acs_find_chan(iface, chan->freq +
670 58 : (j * 20) - 5);
671 58 : if (adj_chan && acs_usable_chan(adj_chan)) {
672 0 : factor += ACS_ADJ_WEIGHT *
673 0 : adj_chan->interference_factor;
674 0 : total_weight += ACS_ADJ_WEIGHT;
675 : }
676 :
677 116 : adj_chan = acs_find_chan(iface, chan->freq +
678 58 : (j * 20) - 10);
679 58 : if (adj_chan && acs_usable_chan(adj_chan)) {
680 0 : factor += ACS_NEXT_ADJ_WEIGHT *
681 0 : adj_chan->interference_factor;
682 0 : total_weight += ACS_NEXT_ADJ_WEIGHT;
683 : }
684 :
685 116 : adj_chan = acs_find_chan(iface, chan->freq +
686 58 : (j * 20) + 5);
687 58 : if (adj_chan && acs_usable_chan(adj_chan)) {
688 0 : factor += ACS_ADJ_WEIGHT *
689 0 : adj_chan->interference_factor;
690 0 : total_weight += ACS_ADJ_WEIGHT;
691 : }
692 :
693 116 : adj_chan = acs_find_chan(iface, chan->freq +
694 58 : (j * 20) + 10);
695 58 : if (adj_chan && acs_usable_chan(adj_chan)) {
696 0 : factor += ACS_NEXT_ADJ_WEIGHT *
697 0 : adj_chan->interference_factor;
698 0 : total_weight += ACS_NEXT_ADJ_WEIGHT;
699 : }
700 : }
701 : }
702 :
703 66 : factor /= total_weight;
704 :
705 66 : bias = NULL;
706 66 : if (iface->conf->acs_chan_bias) {
707 45 : for (k = 0; k < iface->conf->num_acs_chan_bias; k++) {
708 38 : bias = &iface->conf->acs_chan_bias[k];
709 38 : if (bias->channel == chan->chan)
710 4 : break;
711 34 : bias = NULL;
712 : }
713 95 : } else if (is_24ghz_mode(iface->current_mode->mode) &&
714 40 : is_common_24ghz_chan(chan->chan)) {
715 11 : tmp_bias.channel = chan->chan;
716 11 : tmp_bias.bias = ACS_24GHZ_PREFER_1_6_11;
717 11 : bias = &tmp_bias;
718 : }
719 :
720 66 : if (bias) {
721 15 : factor *= bias->bias;
722 30 : wpa_printf(MSG_DEBUG,
723 : "ACS: * channel %d: total interference = %Lg (%f bias)",
724 15 : chan->chan, factor, bias->bias);
725 : } else {
726 51 : wpa_printf(MSG_DEBUG,
727 : "ACS: * channel %d: total interference = %Lg",
728 51 : chan->chan, factor);
729 : }
730 :
731 66 : if (acs_usable_chan(chan) &&
732 0 : (!ideal_chan || factor < ideal_factor)) {
733 0 : ideal_factor = factor;
734 0 : ideal_chan = chan;
735 : }
736 :
737 : /* This channel would at least be usable */
738 66 : if (!rand_chan)
739 8 : rand_chan = chan;
740 : }
741 :
742 8 : if (ideal_chan) {
743 0 : wpa_printf(MSG_DEBUG, "ACS: Ideal channel is %d (%d MHz) with total interference factor of %Lg",
744 0 : ideal_chan->chan, ideal_chan->freq, ideal_factor);
745 0 : return ideal_chan;
746 : }
747 :
748 8 : return rand_chan;
749 : }
750 :
751 :
752 1 : static void acs_adjust_vht_center_freq(struct hostapd_iface *iface)
753 : {
754 : int offset;
755 :
756 1 : wpa_printf(MSG_DEBUG, "ACS: Adjusting VHT center frequency");
757 :
758 1 : switch (iface->conf->vht_oper_chwidth) {
759 : case VHT_CHANWIDTH_USE_HT:
760 0 : offset = 2 * iface->conf->secondary_channel;
761 0 : break;
762 : case VHT_CHANWIDTH_80MHZ:
763 1 : offset = 6;
764 1 : break;
765 : default:
766 : /* TODO: How can this be calculated? Adjust
767 : * acs_find_ideal_chan() */
768 0 : wpa_printf(MSG_INFO, "ACS: Only VHT20/40/80 is supported now");
769 1 : return;
770 : }
771 :
772 2 : iface->conf->vht_oper_centr_freq_seg0_idx =
773 1 : iface->conf->channel + offset;
774 : }
775 :
776 :
777 8 : static int acs_study_survey_based(struct hostapd_iface *iface)
778 : {
779 8 : wpa_printf(MSG_DEBUG, "ACS: Trying survey-based ACS");
780 :
781 8 : if (!iface->chans_surveyed) {
782 0 : wpa_printf(MSG_ERROR, "ACS: Unable to collect survey data");
783 0 : return -1;
784 : }
785 :
786 8 : if (!acs_surveys_are_sufficient(iface)) {
787 0 : wpa_printf(MSG_ERROR, "ACS: Surveys have insufficient data");
788 0 : return -1;
789 : }
790 :
791 8 : acs_survey_all_chans_intereference_factor(iface);
792 8 : return 0;
793 : }
794 :
795 :
796 8 : static int acs_study_options(struct hostapd_iface *iface)
797 : {
798 : int err;
799 :
800 8 : err = acs_study_survey_based(iface);
801 8 : if (err == 0)
802 8 : return 0;
803 :
804 : /* TODO: If no surveys are available/sufficient this is a good
805 : * place to fallback to BSS-based ACS */
806 :
807 0 : return -1;
808 : }
809 :
810 :
811 8 : static void acs_study(struct hostapd_iface *iface)
812 : {
813 : struct hostapd_channel_data *ideal_chan;
814 : int err;
815 :
816 8 : err = acs_study_options(iface);
817 8 : if (err < 0) {
818 0 : wpa_printf(MSG_ERROR, "ACS: All study options have failed");
819 0 : goto fail;
820 : }
821 :
822 8 : ideal_chan = acs_find_ideal_chan(iface);
823 8 : if (!ideal_chan) {
824 0 : wpa_printf(MSG_ERROR, "ACS: Failed to compute ideal channel");
825 0 : err = -1;
826 0 : goto fail;
827 : }
828 :
829 8 : iface->conf->channel = ideal_chan->chan;
830 :
831 8 : if (iface->conf->ieee80211ac)
832 1 : acs_adjust_vht_center_freq(iface);
833 :
834 8 : err = 0;
835 : fail:
836 : /*
837 : * hostapd_setup_interface_complete() will return -1 on failure,
838 : * 0 on success and 0 is HOSTAPD_CHAN_VALID :)
839 : */
840 8 : if (hostapd_acs_completed(iface, err) == HOSTAPD_CHAN_VALID) {
841 8 : acs_cleanup(iface);
842 16 : return;
843 : }
844 :
845 : /* This can possibly happen if channel parameters (secondary
846 : * channel, center frequencies) are misconfigured */
847 0 : wpa_printf(MSG_ERROR, "ACS: Possibly channel configuration is invalid, please report this along with your config file.");
848 0 : acs_fail(iface);
849 : }
850 :
851 :
852 40 : static void acs_scan_complete(struct hostapd_iface *iface)
853 : {
854 : int err;
855 :
856 40 : iface->scan_cb = NULL;
857 :
858 40 : wpa_printf(MSG_DEBUG, "ACS: Using survey based algorithm (acs_num_scans=%d)",
859 40 : iface->conf->acs_num_scans);
860 :
861 40 : err = hostapd_drv_get_survey(iface->bss[0], 0);
862 40 : if (err) {
863 0 : wpa_printf(MSG_ERROR, "ACS: Failed to get survey data");
864 0 : goto fail;
865 : }
866 :
867 40 : if (++iface->acs_num_completed_scans < iface->conf->acs_num_scans) {
868 32 : err = acs_request_scan(iface);
869 32 : if (err) {
870 0 : wpa_printf(MSG_ERROR, "ACS: Failed to request scan");
871 0 : goto fail;
872 : }
873 :
874 32 : return;
875 : }
876 :
877 8 : acs_study(iface);
878 8 : return;
879 : fail:
880 0 : hostapd_acs_completed(iface, 1);
881 0 : acs_fail(iface);
882 : }
883 :
884 :
885 42 : static int acs_request_scan(struct hostapd_iface *iface)
886 : {
887 : struct wpa_driver_scan_params params;
888 : struct hostapd_channel_data *chan;
889 : int i, *freq;
890 :
891 42 : os_memset(¶ms, 0, sizeof(params));
892 42 : params.freqs = os_calloc(iface->current_mode->num_channels + 1,
893 : sizeof(params.freqs[0]));
894 42 : if (params.freqs == NULL)
895 0 : return -1;
896 :
897 42 : freq = params.freqs;
898 780 : for (i = 0; i < iface->current_mode->num_channels; i++) {
899 738 : chan = &iface->current_mode->channels[i];
900 738 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
901 306 : continue;
902 :
903 432 : *freq++ = chan->freq;
904 : }
905 42 : *freq = 0;
906 :
907 42 : iface->scan_cb = acs_scan_complete;
908 :
909 84 : wpa_printf(MSG_DEBUG, "ACS: Scanning %d / %d",
910 42 : iface->acs_num_completed_scans + 1,
911 42 : iface->conf->acs_num_scans);
912 :
913 42 : if (hostapd_driver_scan(iface->bss[0], ¶ms) < 0) {
914 0 : wpa_printf(MSG_ERROR, "ACS: Failed to request initial scan");
915 0 : acs_cleanup(iface);
916 0 : os_free(params.freqs);
917 0 : return -1;
918 : }
919 :
920 42 : os_free(params.freqs);
921 42 : return 0;
922 : }
923 :
924 :
925 10 : enum hostapd_chan_status acs_init(struct hostapd_iface *iface)
926 : {
927 : int err;
928 :
929 10 : wpa_printf(MSG_INFO, "ACS: Automatic channel selection started, this may take a bit");
930 :
931 10 : if (iface->drv_flags & WPA_DRIVER_FLAGS_ACS_OFFLOAD) {
932 0 : wpa_printf(MSG_INFO, "ACS: Offloading to driver");
933 0 : err = hostapd_drv_do_acs(iface->bss[0]);
934 0 : if (err)
935 0 : return HOSTAPD_CHAN_INVALID;
936 0 : return HOSTAPD_CHAN_ACS;
937 : }
938 :
939 10 : acs_cleanup(iface);
940 :
941 10 : err = acs_request_scan(iface);
942 10 : if (err < 0)
943 0 : return HOSTAPD_CHAN_INVALID;
944 :
945 10 : hostapd_set_state(iface, HAPD_IFACE_ACS);
946 10 : wpa_msg(iface->bss[0]->msg_ctx, MSG_INFO, ACS_EVENT_STARTED);
947 :
948 10 : return HOSTAPD_CHAN_ACS;
949 : }
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