Branch data 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 : 42 : static void acs_clean_chan_surveys(struct hostapd_channel_data *chan)
248 : : {
249 : : struct freq_survey *survey, *tmp;
250 : :
251 [ + + ]: 42 : if (dl_list_empty(&chan->survey_list))
252 : 42 : return;
253 : :
254 [ + + ]: 18 : dl_list_for_each_safe(survey, tmp, &chan->survey_list,
255 : : struct freq_survey, list) {
256 : 15 : dl_list_del(&survey->list);
257 : 15 : os_free(survey);
258 : : }
259 : : }
260 : :
261 : :
262 : 8 : static void acs_cleanup(struct hostapd_iface *iface)
263 : : {
264 : : int i;
265 : : struct hostapd_channel_data *chan;
266 : :
267 [ + + ]: 120 : for (i = 0; i < iface->current_mode->num_channels; i++) {
268 : 112 : chan = &iface->current_mode->channels[i];
269 : :
270 [ + + ]: 112 : if (chan->flag & HOSTAPD_CHAN_SURVEY_LIST_INITIALIZED)
271 : 42 : acs_clean_chan_surveys(chan);
272 : :
273 : 112 : dl_list_init(&chan->survey_list);
274 : 112 : chan->flag |= HOSTAPD_CHAN_SURVEY_LIST_INITIALIZED;
275 : 112 : chan->min_nf = 0;
276 : : }
277 : :
278 : 8 : iface->chans_surveyed = 0;
279 : 8 : iface->acs_num_completed_scans = 0;
280 : 8 : }
281 : :
282 : :
283 : 0 : static void acs_fail(struct hostapd_iface *iface)
284 : : {
285 : 0 : wpa_printf(MSG_ERROR, "ACS: Failed to start");
286 : 0 : acs_cleanup(iface);
287 : 0 : }
288 : :
289 : :
290 : : static long double
291 : 0 : acs_survey_interference_factor(struct freq_survey *survey, s8 min_nf)
292 : : {
293 : : long double factor, busy, total;
294 : :
295 [ # # ]: 0 : if (survey->filled & SURVEY_HAS_CHAN_TIME_BUSY)
296 : 0 : busy = survey->channel_time_busy;
297 [ # # ]: 0 : else if (survey->filled & SURVEY_HAS_CHAN_TIME_RX)
298 : 0 : busy = survey->channel_time_rx;
299 : : else {
300 : : /* This shouldn't really happen as survey data is checked in
301 : : * acs_sanity_check() */
302 : 0 : wpa_printf(MSG_ERROR, "ACS: Survey data missing");
303 : 0 : return 0;
304 : : }
305 : :
306 : 0 : total = survey->channel_time;
307 : :
308 [ # # ]: 0 : if (survey->filled & SURVEY_HAS_CHAN_TIME_TX) {
309 : 0 : busy -= survey->channel_time_tx;
310 : 0 : total -= survey->channel_time_tx;
311 : : }
312 : :
313 : : /* TODO: figure out the best multiplier for noise floor base */
314 : 0 : factor = pow(10, survey->nf / 5.0L) +
315 : 0 : (busy / total) *
316 : 0 : pow(2, pow(10, (long double) survey->nf / 10.0L) -
317 : 0 : pow(10, (long double) min_nf / 10.0L));
318 : :
319 : 0 : return factor;
320 : : }
321 : :
322 : :
323 : : static void
324 : 0 : acs_survey_chan_interference_factor(struct hostapd_iface *iface,
325 : : struct hostapd_channel_data *chan)
326 : : {
327 : : struct freq_survey *survey;
328 : 0 : unsigned int i = 0;
329 : 0 : long double int_factor = 0;
330 : :
331 [ # # ]: 0 : if (dl_list_empty(&chan->survey_list))
332 : 0 : return;
333 : :
334 [ # # ]: 0 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
335 : 0 : return;
336 : :
337 : 0 : chan->interference_factor = 0;
338 : :
339 [ # # ]: 0 : dl_list_for_each(survey, &chan->survey_list, struct freq_survey, list)
340 : : {
341 : 0 : int_factor = acs_survey_interference_factor(survey,
342 : 0 : iface->lowest_nf);
343 : 0 : chan->interference_factor += int_factor;
344 : 0 : wpa_printf(MSG_DEBUG, "ACS: %d: min_nf=%d interference_factor=%Lg nf=%d time=%lu busy=%lu rx=%lu",
345 : 0 : ++i, chan->min_nf, int_factor,
346 : 0 : survey->nf, (unsigned long) survey->channel_time,
347 : : (unsigned long) survey->channel_time_busy,
348 : : (unsigned long) survey->channel_time_rx);
349 : : }
350 : :
351 : 0 : chan->interference_factor = chan->interference_factor /
352 : 0 : dl_list_len(&chan->survey_list);
353 : : }
354 : :
355 : :
356 : 0 : static int acs_usable_ht40_chan(struct hostapd_channel_data *chan)
357 : : {
358 : 0 : const int allowed[] = { 36, 44, 52, 60, 100, 108, 116, 124, 132, 149,
359 : : 157, 184, 192 };
360 : : unsigned int i;
361 : :
362 [ # # ]: 0 : for (i = 0; i < ARRAY_SIZE(allowed); i++)
363 [ # # ]: 0 : if (chan->chan == allowed[i])
364 : 0 : return 1;
365 : :
366 : 0 : return 0;
367 : : }
368 : :
369 : :
370 : 18 : static int acs_survey_is_sufficient(struct freq_survey *survey)
371 : : {
372 [ - + ]: 18 : if (!(survey->filled & SURVEY_HAS_NF)) {
373 : 0 : wpa_printf(MSG_ERROR, "ACS: Survey is missing noise floor");
374 : 0 : return 0;
375 : : }
376 : :
377 [ + - ]: 18 : if (!(survey->filled & SURVEY_HAS_CHAN_TIME)) {
378 : 18 : wpa_printf(MSG_ERROR, "ACS: Survey is missing channel time");
379 : 18 : return 0;
380 : : }
381 : :
382 [ # # ][ # # ]: 0 : if (!(survey->filled & SURVEY_HAS_CHAN_TIME_BUSY) &&
383 : 0 : !(survey->filled & SURVEY_HAS_CHAN_TIME_RX)) {
384 : 0 : wpa_printf(MSG_ERROR, "ACS: Survey is missing RX and busy time (at least one is required)");
385 : 0 : return 0;
386 : : }
387 : :
388 : 18 : return 1;
389 : : }
390 : :
391 : :
392 : 48 : static int acs_survey_list_is_sufficient(struct hostapd_channel_data *chan)
393 : : {
394 : : struct freq_survey *survey;
395 : :
396 [ + + ]: 48 : dl_list_for_each(survey, &chan->survey_list, struct freq_survey, list)
397 : : {
398 [ + - ]: 18 : if (!acs_survey_is_sufficient(survey)) {
399 : 18 : wpa_printf(MSG_ERROR, "ACS: Channel %d has insufficient survey data",
400 : 18 : chan->chan);
401 : 18 : return 0;
402 : : }
403 : : }
404 : :
405 : 48 : return 1;
406 : :
407 : : }
408 : :
409 : :
410 : 3 : static int acs_surveys_are_sufficient(struct hostapd_iface *iface)
411 : : {
412 : : int i;
413 : : struct hostapd_channel_data *chan;
414 : 3 : int valid = 0;
415 : :
416 [ + + ]: 45 : for (i = 0; i < iface->current_mode->num_channels; i++) {
417 : 42 : chan = &iface->current_mode->channels[i];
418 [ + + ]: 42 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
419 : 9 : continue;
420 : :
421 [ + + ]: 33 : if (!acs_survey_list_is_sufficient(chan))
422 : 3 : continue;
423 : :
424 : 30 : valid++;
425 : : }
426 : :
427 : : /* We need at least survey data for one channel */
428 : 3 : return !!valid;
429 : : }
430 : :
431 : :
432 : 222 : static int acs_usable_chan(struct hostapd_channel_data *chan)
433 : : {
434 [ + + ]: 222 : if (dl_list_empty(&chan->survey_list))
435 : 207 : return 0;
436 [ - + ]: 15 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
437 : 0 : return 0;
438 [ + - ]: 15 : if (!acs_survey_list_is_sufficient(chan))
439 : 15 : return 0;
440 : 222 : return 1;
441 : : }
442 : :
443 : :
444 : 3 : static void acs_survey_all_chans_intereference_factor(
445 : : struct hostapd_iface *iface)
446 : : {
447 : : int i;
448 : : struct hostapd_channel_data *chan;
449 : :
450 [ + + ]: 45 : for (i = 0; i < iface->current_mode->num_channels; i++) {
451 : 42 : chan = &iface->current_mode->channels[i];
452 : :
453 [ + - ]: 42 : if (!acs_usable_chan(chan))
454 : 42 : continue;
455 : :
456 : 0 : wpa_printf(MSG_DEBUG, "ACS: Survey analysis for channel %d (%d MHz)",
457 : 0 : chan->chan, chan->freq);
458 : :
459 : 0 : acs_survey_chan_interference_factor(iface, chan);
460 : :
461 : 0 : wpa_printf(MSG_DEBUG, "ACS: * interference factor average: %Lg",
462 : : chan->interference_factor);
463 : : }
464 : 3 : }
465 : :
466 : :
467 : 132 : static struct hostapd_channel_data *acs_find_chan(struct hostapd_iface *iface,
468 : : int freq)
469 : : {
470 : : struct hostapd_channel_data *chan;
471 : : int i;
472 : :
473 [ + + ]: 954 : for (i = 0; i < iface->current_mode->num_channels; i++) {
474 : 936 : chan = &iface->current_mode->channels[i];
475 : :
476 [ + + ]: 936 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
477 : 54 : continue;
478 : :
479 [ + + ]: 882 : if (chan->freq == freq)
480 : 114 : return chan;
481 : : }
482 : :
483 : 132 : return NULL;
484 : : }
485 : :
486 : :
487 : : /*
488 : : * At this point it's assumed chan->interface_factor has been computed.
489 : : * This function should be reusable regardless of interference computation
490 : : * option (survey, BSS, spectral, ...). chan->interference factor must be
491 : : * summable (i.e., must be always greater than zero).
492 : : */
493 : : static struct hostapd_channel_data *
494 : 3 : acs_find_ideal_chan(struct hostapd_iface *iface)
495 : : {
496 : 3 : struct hostapd_channel_data *chan, *adj_chan, *ideal_chan = NULL,
497 : 3 : *rand_chan = NULL;
498 : 3 : long double factor, ideal_factor = 0;
499 : : int i, j;
500 : 3 : int n_chans = 1;
501 : :
502 : : /* TODO: HT40- support */
503 : :
504 [ + - ][ - + ]: 3 : if (iface->conf->ieee80211n &&
505 : 3 : iface->conf->secondary_channel == -1) {
506 : 0 : wpa_printf(MSG_ERROR, "ACS: HT40- is not supported yet. Please try HT40+");
507 : 0 : return NULL;
508 : : }
509 : :
510 [ + - ][ - + ]: 3 : if (iface->conf->ieee80211n &&
511 : 3 : iface->conf->secondary_channel)
512 : 0 : n_chans = 2;
513 : :
514 [ - + ][ # # ]: 3 : if (iface->conf->ieee80211ac &&
515 : 0 : iface->conf->vht_oper_chwidth == 1)
516 : 0 : n_chans = 4;
517 : :
518 : : /* TODO: VHT80+80, VHT160. Update acs_adjust_vht_center_freq() too. */
519 : :
520 [ - + ]: 3 : wpa_printf(MSG_DEBUG, "ACS: Survey analysis for selected bandwidth %d MHz",
521 : : n_chans == 1 ? 20 :
522 [ # # ]: 0 : n_chans == 2 ? 40 :
523 [ # # ]: 0 : n_chans == 4 ? 80 :
524 : : -1);
525 : :
526 [ + + ]: 45 : for (i = 0; i < iface->current_mode->num_channels; i++) {
527 : 42 : chan = &iface->current_mode->channels[i];
528 : :
529 [ + + ]: 42 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
530 : 9 : continue;
531 : :
532 : :
533 : : /* HT40 on 5 GHz has a limited set of primary channels as per
534 : : * 11n Annex J */
535 [ - + ][ # # ]: 33 : if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211A &&
536 [ # # ]: 0 : iface->conf->ieee80211n &&
537 [ # # ]: 0 : iface->conf->secondary_channel &&
538 : 0 : !acs_usable_ht40_chan(chan)) {
539 : 0 : wpa_printf(MSG_DEBUG, "ACS: Channel %d: not allowed as primary channel for HT40",
540 : 0 : chan->chan);
541 : 0 : continue;
542 : : }
543 : :
544 : 33 : factor = 0;
545 [ - + ]: 33 : if (acs_usable_chan(chan))
546 : 0 : factor = chan->interference_factor;
547 : :
548 [ - + ]: 33 : for (j = 1; j < n_chans; j++) {
549 : 0 : adj_chan = acs_find_chan(iface, chan->freq + (j * 20));
550 [ # # ]: 0 : if (!adj_chan)
551 : 0 : break;
552 : :
553 [ # # ]: 0 : if (acs_usable_chan(adj_chan))
554 : 0 : factor += adj_chan->interference_factor;
555 : : }
556 : :
557 [ - + ]: 33 : if (j != n_chans) {
558 : 0 : wpa_printf(MSG_DEBUG, "ACS: Channel %d: not enough bandwidth",
559 : 0 : chan->chan);
560 : 0 : continue;
561 : : }
562 : :
563 : : /* 2.4 GHz has overlapping 20 MHz channels. Include adjacent
564 : : * channel interference factor. */
565 [ + - ][ + - ]: 33 : if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211B ||
566 : 33 : iface->current_mode->mode == HOSTAPD_MODE_IEEE80211G) {
567 [ + + ]: 66 : for (j = 0; j < n_chans; j++) {
568 : : /* TODO: perhaps a multiplier should be used
569 : : * here? */
570 : :
571 : 33 : adj_chan = acs_find_chan(iface, chan->freq +
572 : 33 : (j * 20) - 5);
573 [ - + ][ + + ]: 33 : if (adj_chan && acs_usable_chan(adj_chan))
574 : 0 : factor += adj_chan->interference_factor;
575 : :
576 : 33 : adj_chan = acs_find_chan(iface, chan->freq +
577 : 33 : (j * 20) - 10);
578 [ - + ][ + + ]: 33 : if (adj_chan && acs_usable_chan(adj_chan))
579 : 0 : factor += adj_chan->interference_factor;
580 : :
581 : 33 : adj_chan = acs_find_chan(iface, chan->freq +
582 : 33 : (j * 20) + 5);
583 [ - + ][ + + ]: 33 : if (adj_chan && acs_usable_chan(adj_chan))
584 : 0 : factor += adj_chan->interference_factor;
585 : :
586 : 33 : adj_chan = acs_find_chan(iface, chan->freq +
587 : 33 : (j * 20) + 10);
588 [ - + ][ + + ]: 33 : if (adj_chan && acs_usable_chan(adj_chan))
589 : 0 : factor += adj_chan->interference_factor;
590 : : }
591 : : }
592 : :
593 : 33 : wpa_printf(MSG_DEBUG, "ACS: * channel %d: total interference = %Lg",
594 : 33 : chan->chan, factor);
595 : :
596 [ # # ][ - + ]: 33 : if (acs_usable_chan(chan) &&
597 [ # # ]: 0 : (!ideal_chan || factor < ideal_factor)) {
598 : 0 : ideal_factor = factor;
599 : 0 : ideal_chan = chan;
600 : : }
601 : :
602 : : /* This channel would at least be usable */
603 [ + + ]: 33 : if (!rand_chan)
604 : 3 : rand_chan = chan;
605 : : }
606 : :
607 [ - + ]: 3 : if (ideal_chan) {
608 : 0 : wpa_printf(MSG_DEBUG, "ACS: Ideal channel is %d (%d MHz) with total interference factor of %Lg",
609 : 0 : ideal_chan->chan, ideal_chan->freq, ideal_factor);
610 : 0 : return ideal_chan;
611 : : }
612 : :
613 : 3 : return rand_chan;
614 : : }
615 : :
616 : :
617 : 0 : static void acs_adjust_vht_center_freq(struct hostapd_iface *iface)
618 : : {
619 : 0 : wpa_printf(MSG_DEBUG, "ACS: Adjusting VHT center frequency");
620 : :
621 [ # # # ]: 0 : switch (iface->conf->vht_oper_chwidth) {
622 : : case VHT_CHANWIDTH_USE_HT:
623 : 0 : iface->conf->vht_oper_centr_freq_seg0_idx =
624 : 0 : iface->conf->channel + 2;
625 : 0 : break;
626 : : case VHT_CHANWIDTH_80MHZ:
627 : 0 : iface->conf->vht_oper_centr_freq_seg0_idx =
628 : 0 : iface->conf->channel + 6;
629 : 0 : break;
630 : : default:
631 : : /* TODO: How can this be calculated? Adjust
632 : : * acs_find_ideal_chan() */
633 : 0 : wpa_printf(MSG_INFO, "ACS: Only VHT20/40/80 is supported now");
634 : 0 : break;
635 : : }
636 : 0 : }
637 : :
638 : :
639 : 3 : static int acs_study_survey_based(struct hostapd_iface *iface)
640 : : {
641 : 3 : wpa_printf(MSG_DEBUG, "ACS: Trying survey-based ACS");
642 : :
643 [ - + ]: 3 : if (!iface->chans_surveyed) {
644 : 0 : wpa_printf(MSG_ERROR, "ACS: Unable to collect survey data");
645 : 0 : return -1;
646 : : }
647 : :
648 [ - + ]: 3 : if (!acs_surveys_are_sufficient(iface)) {
649 : 0 : wpa_printf(MSG_ERROR, "ACS: Surveys have insufficient data");
650 : 0 : return -1;
651 : : }
652 : :
653 : 3 : acs_survey_all_chans_intereference_factor(iface);
654 : 3 : return 0;
655 : : }
656 : :
657 : :
658 : 3 : static int acs_study_options(struct hostapd_iface *iface)
659 : : {
660 : : int err;
661 : :
662 : 3 : err = acs_study_survey_based(iface);
663 [ + - ]: 3 : if (err == 0)
664 : 3 : return 0;
665 : :
666 : : /* TODO: If no surveys are available/sufficient this is a good
667 : : * place to fallback to BSS-based ACS */
668 : :
669 : 3 : return -1;
670 : : }
671 : :
672 : :
673 : 3 : static void acs_study(struct hostapd_iface *iface)
674 : : {
675 : : struct hostapd_channel_data *ideal_chan;
676 : : int err;
677 : :
678 : 3 : err = acs_study_options(iface);
679 [ - + ]: 3 : if (err < 0) {
680 : 0 : wpa_printf(MSG_ERROR, "ACS: All study options have failed");
681 : 0 : goto fail;
682 : : }
683 : :
684 : 3 : ideal_chan = acs_find_ideal_chan(iface);
685 [ - + ]: 3 : if (!ideal_chan) {
686 : 0 : wpa_printf(MSG_ERROR, "ACS: Failed to compute ideal channel");
687 : 0 : err = -1;
688 : 0 : goto fail;
689 : : }
690 : :
691 : 3 : iface->conf->channel = ideal_chan->chan;
692 : :
693 [ - + ]: 3 : if (iface->conf->ieee80211ac)
694 : 0 : acs_adjust_vht_center_freq(iface);
695 : :
696 : 3 : err = 0;
697 : : fail:
698 : : /*
699 : : * hostapd_setup_interface_complete() will return -1 on failure,
700 : : * 0 on success and 0 is HOSTAPD_CHAN_VALID :)
701 : : */
702 [ + - ]: 3 : if (hostapd_acs_completed(iface, err) == HOSTAPD_CHAN_VALID) {
703 : 3 : acs_cleanup(iface);
704 : 3 : return;
705 : : }
706 : :
707 : : /* This can possibly happen if channel parameters (secondary
708 : : * channel, center frequencies) are misconfigured */
709 : 0 : wpa_printf(MSG_ERROR, "ACS: Possibly channel configuration is invalid, please report this along with your config file.");
710 : 0 : acs_fail(iface);
711 : : }
712 : :
713 : :
714 : 15 : static void acs_scan_complete(struct hostapd_iface *iface)
715 : : {
716 : : int err;
717 : :
718 : 15 : iface->scan_cb = NULL;
719 : :
720 : 15 : wpa_printf(MSG_DEBUG, "ACS: Using survey based algorithm (acs_num_scans=%d)",
721 : 15 : iface->conf->acs_num_scans);
722 : :
723 : 15 : err = hostapd_drv_get_survey(iface->bss[0], 0);
724 [ - + ]: 15 : if (err) {
725 : 0 : wpa_printf(MSG_ERROR, "ACS: Failed to get survey data");
726 : 0 : acs_fail(iface);
727 : : }
728 : :
729 [ + + ]: 15 : if (++iface->acs_num_completed_scans < iface->conf->acs_num_scans) {
730 : 12 : err = acs_request_scan(iface);
731 [ - + ]: 12 : if (err) {
732 : 0 : wpa_printf(MSG_ERROR, "ACS: Failed to request scan");
733 : 0 : goto fail;
734 : : }
735 : :
736 : 12 : return;
737 : : }
738 : :
739 : 3 : acs_study(iface);
740 : 3 : return;
741 : : fail:
742 : 0 : hostapd_acs_completed(iface, 1);
743 : 15 : acs_fail(iface);
744 : : }
745 : :
746 : :
747 : 17 : static int acs_request_scan(struct hostapd_iface *iface)
748 : : {
749 : : struct wpa_driver_scan_params params;
750 : : struct hostapd_channel_data *chan;
751 : : int i, *freq;
752 : :
753 : 17 : os_memset(¶ms, 0, sizeof(params));
754 : 17 : params.freqs = os_calloc(iface->current_mode->num_channels + 1,
755 : : sizeof(params.freqs[0]));
756 [ - + ]: 17 : if (params.freqs == NULL)
757 : 0 : return -1;
758 : :
759 : 17 : freq = params.freqs;
760 [ + + ]: 255 : for (i = 0; i < iface->current_mode->num_channels; i++) {
761 : 238 : chan = &iface->current_mode->channels[i];
762 [ + + ]: 238 : if (chan->flag & HOSTAPD_CHAN_DISABLED)
763 : 51 : continue;
764 : :
765 : 187 : *freq++ = chan->freq;
766 : : }
767 : 17 : *freq = 0;
768 : :
769 : 17 : iface->scan_cb = acs_scan_complete;
770 : :
771 : 17 : wpa_printf(MSG_DEBUG, "ACS: Scanning %d / %d",
772 : 17 : iface->acs_num_completed_scans + 1,
773 : 17 : iface->conf->acs_num_scans);
774 : :
775 [ - + ]: 17 : if (hostapd_driver_scan(iface->bss[0], ¶ms) < 0) {
776 : 0 : wpa_printf(MSG_ERROR, "ACS: Failed to request initial scan");
777 : 0 : acs_cleanup(iface);
778 : 0 : return -1;
779 : : }
780 : :
781 : 17 : os_free(params.freqs);
782 : 17 : return 0;
783 : : }
784 : :
785 : :
786 : 5 : enum hostapd_chan_status acs_init(struct hostapd_iface *iface)
787 : : {
788 : : int err;
789 : :
790 : 5 : wpa_printf(MSG_INFO, "ACS: Automatic channel selection started, this may take a bit");
791 : :
792 : 5 : acs_cleanup(iface);
793 : :
794 : 5 : err = acs_request_scan(iface);
795 [ - + ]: 5 : if (err < 0)
796 : 0 : return HOSTAPD_CHAN_INVALID;
797 : :
798 : 5 : hostapd_set_state(iface, HAPD_IFACE_ACS);
799 : 5 : wpa_msg(iface->bss[0]->msg_ctx, MSG_INFO, ACS_EVENT_STARTED);
800 : :
801 : 5 : return HOSTAPD_CHAN_ACS;
802 : : }
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