Line data Source code
1 : /*
2 : * WPA Supplicant - background scan and roaming module: learn
3 : * Copyright (c) 2009-2010, Jouni Malinen <j@w1.fi>
4 : *
5 : * This software may be distributed under the terms of the BSD license.
6 : * See README for more details.
7 : */
8 :
9 : #include "includes.h"
10 :
11 : #include "common.h"
12 : #include "eloop.h"
13 : #include "list.h"
14 : #include "common/ieee802_11_defs.h"
15 : #include "drivers/driver.h"
16 : #include "config_ssid.h"
17 : #include "wpa_supplicant_i.h"
18 : #include "driver_i.h"
19 : #include "scan.h"
20 : #include "bgscan.h"
21 :
22 : struct bgscan_learn_bss {
23 : struct dl_list list;
24 : u8 bssid[ETH_ALEN];
25 : int freq;
26 : u8 *neigh; /* num_neigh * ETH_ALEN buffer */
27 : size_t num_neigh;
28 : };
29 :
30 : struct bgscan_learn_data {
31 : struct wpa_supplicant *wpa_s;
32 : const struct wpa_ssid *ssid;
33 : int scan_interval;
34 : int signal_threshold;
35 : int short_interval; /* use if signal < threshold */
36 : int long_interval; /* use if signal > threshold */
37 : struct os_reltime last_bgscan;
38 : char *fname;
39 : struct dl_list bss;
40 : int *supp_freqs;
41 : int probe_idx;
42 : };
43 :
44 :
45 4 : static void bss_free(struct bgscan_learn_bss *bss)
46 : {
47 4 : os_free(bss->neigh);
48 4 : os_free(bss);
49 4 : }
50 :
51 :
52 10 : static int bssid_in_array(u8 *array, size_t array_len, const u8 *bssid)
53 : {
54 : size_t i;
55 :
56 10 : if (array == NULL || array_len == 0)
57 4 : return 0;
58 :
59 6 : for (i = 0; i < array_len; i++) {
60 6 : if (os_memcmp(array + i * ETH_ALEN, bssid, ETH_ALEN) == 0)
61 6 : return 1;
62 : }
63 :
64 0 : return 0;
65 : }
66 :
67 :
68 20 : static void bgscan_learn_add_neighbor(struct bgscan_learn_bss *bss,
69 : const u8 *bssid)
70 : {
71 : u8 *n;
72 :
73 20 : if (os_memcmp(bss->bssid, bssid, ETH_ALEN) == 0)
74 10 : return;
75 10 : if (bssid_in_array(bss->neigh, bss->num_neigh, bssid))
76 6 : return;
77 :
78 4 : n = os_realloc_array(bss->neigh, bss->num_neigh + 1, ETH_ALEN);
79 4 : if (n == NULL)
80 0 : return;
81 :
82 4 : os_memcpy(n + bss->num_neigh * ETH_ALEN, bssid, ETH_ALEN);
83 4 : bss->neigh = n;
84 4 : bss->num_neigh++;
85 : }
86 :
87 :
88 10 : static struct bgscan_learn_bss * bgscan_learn_get_bss(
89 : struct bgscan_learn_data *data, const u8 *bssid)
90 : {
91 : struct bgscan_learn_bss *bss;
92 :
93 15 : dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) {
94 11 : if (os_memcmp(bss->bssid, bssid, ETH_ALEN) == 0)
95 6 : return bss;
96 : }
97 4 : return NULL;
98 : }
99 :
100 :
101 2 : static int bgscan_learn_load(struct bgscan_learn_data *data)
102 : {
103 : FILE *f;
104 : char buf[128];
105 : struct bgscan_learn_bss *bss;
106 :
107 2 : if (data->fname == NULL)
108 1 : return 0;
109 :
110 1 : f = fopen(data->fname, "r");
111 1 : if (f == NULL)
112 1 : return 0;
113 :
114 0 : wpa_printf(MSG_DEBUG, "bgscan learn: Loading data from %s",
115 : data->fname);
116 :
117 0 : if (fgets(buf, sizeof(buf), f) == NULL ||
118 0 : os_strncmp(buf, "wpa_supplicant-bgscan-learn\n", 28) != 0) {
119 0 : wpa_printf(MSG_INFO, "bgscan learn: Invalid data file %s",
120 : data->fname);
121 0 : fclose(f);
122 0 : return -1;
123 : }
124 :
125 0 : while (fgets(buf, sizeof(buf), f)) {
126 0 : if (os_strncmp(buf, "BSS ", 4) == 0) {
127 0 : bss = os_zalloc(sizeof(*bss));
128 0 : if (!bss)
129 0 : continue;
130 0 : if (hwaddr_aton(buf + 4, bss->bssid) < 0) {
131 0 : bss_free(bss);
132 0 : continue;
133 : }
134 0 : bss->freq = atoi(buf + 4 + 18);
135 0 : dl_list_add(&data->bss, &bss->list);
136 0 : wpa_printf(MSG_DEBUG, "bgscan learn: Loaded BSS "
137 : "entry: " MACSTR " freq=%d",
138 0 : MAC2STR(bss->bssid), bss->freq);
139 : }
140 :
141 0 : if (os_strncmp(buf, "NEIGHBOR ", 9) == 0) {
142 : u8 addr[ETH_ALEN];
143 :
144 0 : if (hwaddr_aton(buf + 9, addr) < 0)
145 0 : continue;
146 0 : bss = bgscan_learn_get_bss(data, addr);
147 0 : if (bss == NULL)
148 0 : continue;
149 0 : if (hwaddr_aton(buf + 9 + 18, addr) < 0)
150 0 : continue;
151 :
152 0 : bgscan_learn_add_neighbor(bss, addr);
153 : }
154 : }
155 :
156 0 : fclose(f);
157 0 : return 0;
158 : }
159 :
160 :
161 2 : static void bgscan_learn_save(struct bgscan_learn_data *data)
162 : {
163 : FILE *f;
164 : struct bgscan_learn_bss *bss;
165 :
166 2 : if (data->fname == NULL)
167 1 : return;
168 :
169 1 : wpa_printf(MSG_DEBUG, "bgscan learn: Saving data to %s",
170 : data->fname);
171 :
172 1 : f = fopen(data->fname, "w");
173 1 : if (f == NULL)
174 0 : return;
175 1 : fprintf(f, "wpa_supplicant-bgscan-learn\n");
176 :
177 3 : dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) {
178 14 : fprintf(f, "BSS " MACSTR " %d\n",
179 12 : MAC2STR(bss->bssid), bss->freq);
180 : }
181 :
182 3 : dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) {
183 : size_t i;
184 4 : for (i = 0; i < bss->num_neigh; i++) {
185 24 : fprintf(f, "NEIGHBOR " MACSTR " " MACSTR "\n",
186 12 : MAC2STR(bss->bssid),
187 12 : MAC2STR(bss->neigh + i * ETH_ALEN));
188 : }
189 : }
190 :
191 1 : fclose(f);
192 : }
193 :
194 :
195 74 : static int in_array(int *array, int val)
196 : {
197 : int i;
198 :
199 74 : if (array == NULL)
200 2 : return 0;
201 :
202 760 : for (i = 0; array[i]; i++) {
203 716 : if (array[i] == val)
204 28 : return 1;
205 : }
206 :
207 44 : return 0;
208 : }
209 :
210 :
211 0 : static int * bgscan_learn_get_freqs(struct bgscan_learn_data *data,
212 : size_t *count)
213 : {
214 : struct bgscan_learn_bss *bss;
215 0 : int *freqs = NULL, *n;
216 :
217 0 : *count = 0;
218 :
219 0 : dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) {
220 0 : if (in_array(freqs, bss->freq))
221 0 : continue;
222 0 : n = os_realloc_array(freqs, *count + 2, sizeof(int));
223 0 : if (n == NULL)
224 0 : return freqs;
225 0 : freqs = n;
226 0 : freqs[*count] = bss->freq;
227 0 : (*count)++;
228 0 : freqs[*count] = 0;
229 : }
230 :
231 0 : return freqs;
232 : }
233 :
234 :
235 0 : static int * bgscan_learn_get_probe_freq(struct bgscan_learn_data *data,
236 : int *freqs, size_t count)
237 : {
238 : int idx, *n;
239 :
240 0 : if (data->supp_freqs == NULL)
241 0 : return freqs;
242 :
243 0 : idx = data->probe_idx;
244 : do {
245 0 : if (!in_array(freqs, data->supp_freqs[idx])) {
246 0 : wpa_printf(MSG_DEBUG, "bgscan learn: Probe new freq "
247 0 : "%u", data->supp_freqs[idx]);
248 0 : data->probe_idx = idx + 1;
249 0 : if (data->supp_freqs[data->probe_idx] == 0)
250 0 : data->probe_idx = 0;
251 0 : n = os_realloc_array(freqs, count + 2, sizeof(int));
252 0 : if (n == NULL)
253 0 : return freqs;
254 0 : freqs = n;
255 0 : freqs[count] = data->supp_freqs[idx];
256 0 : count++;
257 0 : freqs[count] = 0;
258 0 : break;
259 : }
260 :
261 0 : idx++;
262 0 : if (data->supp_freqs[idx] == 0)
263 0 : idx = 0;
264 0 : } while (idx != data->probe_idx);
265 :
266 0 : return freqs;
267 : }
268 :
269 :
270 3 : static void bgscan_learn_timeout(void *eloop_ctx, void *timeout_ctx)
271 : {
272 3 : struct bgscan_learn_data *data = eloop_ctx;
273 3 : struct wpa_supplicant *wpa_s = data->wpa_s;
274 : struct wpa_driver_scan_params params;
275 3 : int *freqs = NULL;
276 : size_t count, i;
277 : char msg[100], *pos;
278 :
279 3 : os_memset(¶ms, 0, sizeof(params));
280 3 : params.num_ssids = 1;
281 3 : params.ssids[0].ssid = data->ssid->ssid;
282 3 : params.ssids[0].ssid_len = data->ssid->ssid_len;
283 3 : if (data->ssid->scan_freq)
284 3 : params.freqs = data->ssid->scan_freq;
285 : else {
286 0 : freqs = bgscan_learn_get_freqs(data, &count);
287 0 : wpa_printf(MSG_DEBUG, "bgscan learn: BSSes in this ESS have "
288 : "been seen on %u channels", (unsigned int) count);
289 0 : freqs = bgscan_learn_get_probe_freq(data, freqs, count);
290 :
291 0 : msg[0] = '\0';
292 0 : pos = msg;
293 0 : for (i = 0; freqs && freqs[i]; i++) {
294 : int ret;
295 0 : ret = os_snprintf(pos, msg + sizeof(msg) - pos, " %d",
296 0 : freqs[i]);
297 0 : if (ret < 0 || ret >= msg + sizeof(msg) - pos)
298 : break;
299 0 : pos += ret;
300 : }
301 0 : pos[0] = '\0';
302 0 : wpa_printf(MSG_DEBUG, "bgscan learn: Scanning frequencies:%s",
303 : msg);
304 0 : params.freqs = freqs;
305 : }
306 :
307 3 : wpa_printf(MSG_DEBUG, "bgscan learn: Request a background scan");
308 3 : if (wpa_supplicant_trigger_scan(wpa_s, ¶ms)) {
309 0 : wpa_printf(MSG_DEBUG, "bgscan learn: Failed to trigger scan");
310 0 : eloop_register_timeout(data->scan_interval, 0,
311 : bgscan_learn_timeout, data, NULL);
312 : } else
313 3 : os_get_reltime(&data->last_bgscan);
314 3 : os_free(freqs);
315 3 : }
316 :
317 :
318 2 : static int bgscan_learn_get_params(struct bgscan_learn_data *data,
319 : const char *params)
320 : {
321 : const char *pos;
322 :
323 2 : if (params == NULL)
324 0 : return 0;
325 :
326 2 : data->short_interval = atoi(params);
327 :
328 2 : pos = os_strchr(params, ':');
329 2 : if (pos == NULL)
330 0 : return 0;
331 2 : pos++;
332 2 : data->signal_threshold = atoi(pos);
333 2 : pos = os_strchr(pos, ':');
334 2 : if (pos == NULL) {
335 0 : wpa_printf(MSG_ERROR, "bgscan learn: Missing scan interval "
336 : "for high signal");
337 0 : return -1;
338 : }
339 2 : pos++;
340 2 : data->long_interval = atoi(pos);
341 2 : pos = os_strchr(pos, ':');
342 2 : if (pos) {
343 1 : pos++;
344 1 : data->fname = os_strdup(pos);
345 : }
346 :
347 2 : return 0;
348 : }
349 :
350 :
351 2 : static int * bgscan_learn_get_supp_freqs(struct wpa_supplicant *wpa_s)
352 : {
353 : struct hostapd_hw_modes *modes;
354 2 : int i, j, *freqs = NULL, *n;
355 2 : size_t count = 0;
356 :
357 2 : modes = wpa_s->hw.modes;
358 2 : if (modes == NULL)
359 0 : return NULL;
360 :
361 8 : for (i = 0; i < wpa_s->hw.num_modes; i++) {
362 110 : for (j = 0; j < modes[i].num_channels; j++) {
363 104 : if (modes[i].channels[j].flag & HOSTAPD_CHAN_DISABLED)
364 30 : continue;
365 : /* some hw modes (e.g. 11b & 11g) contain same freqs */
366 74 : if (in_array(freqs, modes[i].channels[j].freq))
367 28 : continue;
368 46 : n = os_realloc_array(freqs, count + 2, sizeof(int));
369 46 : if (n == NULL)
370 0 : continue;
371 :
372 46 : freqs = n;
373 46 : freqs[count] = modes[i].channels[j].freq;
374 46 : count++;
375 46 : freqs[count] = 0;
376 : }
377 : }
378 :
379 2 : return freqs;
380 : }
381 :
382 :
383 2 : static void * bgscan_learn_init(struct wpa_supplicant *wpa_s,
384 : const char *params,
385 : const struct wpa_ssid *ssid)
386 : {
387 : struct bgscan_learn_data *data;
388 :
389 2 : data = os_zalloc(sizeof(*data));
390 2 : if (data == NULL)
391 0 : return NULL;
392 2 : dl_list_init(&data->bss);
393 2 : data->wpa_s = wpa_s;
394 2 : data->ssid = ssid;
395 2 : if (bgscan_learn_get_params(data, params) < 0) {
396 0 : os_free(data->fname);
397 0 : os_free(data);
398 0 : return NULL;
399 : }
400 2 : if (data->short_interval <= 0)
401 0 : data->short_interval = 30;
402 2 : if (data->long_interval <= 0)
403 0 : data->long_interval = 30;
404 :
405 2 : if (bgscan_learn_load(data) < 0) {
406 0 : os_free(data->fname);
407 0 : os_free(data);
408 0 : return NULL;
409 : }
410 :
411 2 : wpa_printf(MSG_DEBUG, "bgscan learn: Signal strength threshold %d "
412 : "Short bgscan interval %d Long bgscan interval %d",
413 : data->signal_threshold, data->short_interval,
414 : data->long_interval);
415 :
416 4 : if (data->signal_threshold &&
417 2 : wpa_drv_signal_monitor(wpa_s, data->signal_threshold, 4) < 0) {
418 0 : wpa_printf(MSG_ERROR, "bgscan learn: Failed to enable "
419 : "signal strength monitoring");
420 : }
421 :
422 2 : data->supp_freqs = bgscan_learn_get_supp_freqs(wpa_s);
423 2 : data->scan_interval = data->short_interval;
424 2 : if (data->signal_threshold) {
425 : /* Poll for signal info to set initial scan interval */
426 : struct wpa_signal_info siginfo;
427 4 : if (wpa_drv_signal_poll(wpa_s, &siginfo) == 0 &&
428 2 : siginfo.current_signal >= data->signal_threshold)
429 1 : data->scan_interval = data->long_interval;
430 : }
431 :
432 2 : eloop_register_timeout(data->scan_interval, 0, bgscan_learn_timeout,
433 : data, NULL);
434 :
435 : /*
436 : * This function is called immediately after an association, so it is
437 : * reasonable to assume that a scan was completed recently. This makes
438 : * us skip an immediate new scan in cases where the current signal
439 : * level is below the bgscan threshold.
440 : */
441 2 : os_get_reltime(&data->last_bgscan);
442 :
443 2 : return data;
444 : }
445 :
446 :
447 2 : static void bgscan_learn_deinit(void *priv)
448 : {
449 2 : struct bgscan_learn_data *data = priv;
450 : struct bgscan_learn_bss *bss, *n;
451 :
452 2 : bgscan_learn_save(data);
453 2 : eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
454 2 : if (data->signal_threshold)
455 2 : wpa_drv_signal_monitor(data->wpa_s, 0, 0);
456 2 : os_free(data->fname);
457 6 : dl_list_for_each_safe(bss, n, &data->bss, struct bgscan_learn_bss,
458 : list) {
459 4 : dl_list_del(&bss->list);
460 4 : bss_free(bss);
461 : }
462 2 : os_free(data->supp_freqs);
463 2 : os_free(data);
464 2 : }
465 :
466 :
467 20 : static int bgscan_learn_bss_match(struct bgscan_learn_data *data,
468 : struct wpa_scan_res *bss)
469 : {
470 : const u8 *ie;
471 :
472 20 : ie = wpa_scan_get_ie(bss, WLAN_EID_SSID);
473 20 : if (ie == NULL)
474 0 : return 0;
475 :
476 40 : if (data->ssid->ssid_len != ie[1] ||
477 20 : os_memcmp(data->ssid->ssid, ie + 2, ie[1]) != 0)
478 0 : return 0; /* SSID mismatch */
479 :
480 20 : return 1;
481 : }
482 :
483 :
484 5 : static int bgscan_learn_notify_scan(void *priv,
485 : struct wpa_scan_results *scan_res)
486 : {
487 5 : struct bgscan_learn_data *data = priv;
488 : size_t i, j;
489 : #define MAX_BSS 50
490 : u8 bssid[MAX_BSS * ETH_ALEN];
491 5 : size_t num_bssid = 0;
492 :
493 5 : wpa_printf(MSG_DEBUG, "bgscan learn: scan result notification");
494 :
495 5 : eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
496 5 : eloop_register_timeout(data->scan_interval, 0, bgscan_learn_timeout,
497 : data, NULL);
498 :
499 15 : for (i = 0; i < scan_res->num; i++) {
500 10 : struct wpa_scan_res *res = scan_res->res[i];
501 10 : if (!bgscan_learn_bss_match(data, res))
502 0 : continue;
503 :
504 10 : if (num_bssid < MAX_BSS) {
505 10 : os_memcpy(bssid + num_bssid * ETH_ALEN, res->bssid,
506 : ETH_ALEN);
507 10 : num_bssid++;
508 : }
509 : }
510 5 : wpa_printf(MSG_DEBUG, "bgscan learn: %u matching BSSes in scan "
511 : "results", (unsigned int) num_bssid);
512 :
513 15 : for (i = 0; i < scan_res->num; i++) {
514 10 : struct wpa_scan_res *res = scan_res->res[i];
515 : struct bgscan_learn_bss *bss;
516 :
517 10 : if (!bgscan_learn_bss_match(data, res))
518 0 : continue;
519 :
520 10 : bss = bgscan_learn_get_bss(data, res->bssid);
521 10 : if (bss && bss->freq != res->freq) {
522 0 : wpa_printf(MSG_DEBUG, "bgscan learn: Update BSS "
523 : MACSTR " freq %d -> %d",
524 0 : MAC2STR(res->bssid), bss->freq, res->freq);
525 0 : bss->freq = res->freq;
526 10 : } else if (!bss) {
527 28 : wpa_printf(MSG_DEBUG, "bgscan learn: Add BSS " MACSTR
528 24 : " freq=%d", MAC2STR(res->bssid), res->freq);
529 4 : bss = os_zalloc(sizeof(*bss));
530 4 : if (!bss)
531 0 : continue;
532 4 : os_memcpy(bss->bssid, res->bssid, ETH_ALEN);
533 4 : bss->freq = res->freq;
534 4 : dl_list_add(&data->bss, &bss->list);
535 : }
536 :
537 30 : for (j = 0; j < num_bssid; j++) {
538 20 : u8 *addr = bssid + j * ETH_ALEN;
539 20 : bgscan_learn_add_neighbor(bss, addr);
540 : }
541 : }
542 :
543 : /*
544 : * A more advanced bgscan could process scan results internally, select
545 : * the BSS and request roam if needed. This sample uses the existing
546 : * BSS/ESS selection routine. Change this to return 1 if selection is
547 : * done inside the bgscan module.
548 : */
549 :
550 5 : return 0;
551 : }
552 :
553 :
554 0 : static void bgscan_learn_notify_beacon_loss(void *priv)
555 : {
556 0 : wpa_printf(MSG_DEBUG, "bgscan learn: beacon loss");
557 : /* TODO: speed up background scanning */
558 0 : }
559 :
560 :
561 2 : static void bgscan_learn_notify_signal_change(void *priv, int above,
562 : int current_signal,
563 : int current_noise,
564 : int current_txrate)
565 : {
566 2 : struct bgscan_learn_data *data = priv;
567 2 : int scan = 0;
568 : struct os_reltime now;
569 :
570 4 : if (data->short_interval == data->long_interval ||
571 2 : data->signal_threshold == 0)
572 2 : return;
573 :
574 2 : wpa_printf(MSG_DEBUG, "bgscan learn: signal level changed "
575 : "(above=%d current_signal=%d current_noise=%d "
576 : "current_txrate=%d)", above, current_signal,
577 : current_noise, current_txrate);
578 2 : if (data->scan_interval == data->long_interval && !above) {
579 0 : wpa_printf(MSG_DEBUG, "bgscan learn: Start using short bgscan "
580 : "interval");
581 0 : data->scan_interval = data->short_interval;
582 0 : os_get_reltime(&now);
583 0 : if (now.sec > data->last_bgscan.sec + 1)
584 0 : scan = 1;
585 2 : } else if (data->scan_interval == data->short_interval && above) {
586 0 : wpa_printf(MSG_DEBUG, "bgscan learn: Start using long bgscan "
587 : "interval");
588 0 : data->scan_interval = data->long_interval;
589 0 : eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
590 0 : eloop_register_timeout(data->scan_interval, 0,
591 : bgscan_learn_timeout, data, NULL);
592 2 : } else if (!above) {
593 : /*
594 : * Signal dropped further 4 dB. Request a new scan if we have
595 : * not yet scanned in a while.
596 : */
597 1 : os_get_reltime(&now);
598 1 : if (now.sec > data->last_bgscan.sec + 10)
599 0 : scan = 1;
600 : }
601 :
602 2 : if (scan) {
603 0 : wpa_printf(MSG_DEBUG, "bgscan learn: Trigger immediate scan");
604 0 : eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
605 0 : eloop_register_timeout(0, 0, bgscan_learn_timeout, data, NULL);
606 : }
607 : }
608 :
609 :
610 : const struct bgscan_ops bgscan_learn_ops = {
611 : .name = "learn",
612 : .init = bgscan_learn_init,
613 : .deinit = bgscan_learn_deinit,
614 : .notify_scan = bgscan_learn_notify_scan,
615 : .notify_beacon_loss = bgscan_learn_notify_beacon_loss,
616 : .notify_signal_change = bgscan_learn_notify_signal_change,
617 : };
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