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