2 * WPA Supplicant - background scan and roaming module: learn
3 * Copyright (c) 2009-2010, Jouni Malinen <j@w1.fi>
5 * This software may be distributed under the terms of the BSD license.
6 * See README for more details.
14 #include "common/ieee802_11_defs.h"
15 #include "drivers/driver.h"
16 #include "config_ssid.h"
17 #include "wpa_supplicant_i.h"
22 struct bgscan_learn_bss {
26 u8 *neigh; /* num_neigh * ETH_ALEN buffer */
30 struct bgscan_learn_data {
31 struct wpa_supplicant *wpa_s;
32 const struct wpa_ssid *ssid;
35 int short_interval; /* use if signal < threshold */
36 int long_interval; /* use if signal > threshold */
37 struct os_reltime last_bgscan;
45 static void bss_free(struct bgscan_learn_bss *bss)
52 static int bssid_in_array(u8 *array, size_t array_len, const u8 *bssid)
56 if (array == NULL || array_len == 0)
59 for (i = 0; i < array_len; i++) {
60 if (os_memcmp(array + i * ETH_ALEN, bssid, ETH_ALEN) == 0)
68 static void bgscan_learn_add_neighbor(struct bgscan_learn_bss *bss,
73 if (os_memcmp(bss->bssid, bssid, ETH_ALEN) == 0)
75 if (bssid_in_array(bss->neigh, bss->num_neigh, bssid))
78 n = os_realloc_array(bss->neigh, bss->num_neigh + 1, ETH_ALEN);
82 os_memcpy(n + bss->num_neigh * ETH_ALEN, bssid, ETH_ALEN);
88 static struct bgscan_learn_bss * bgscan_learn_get_bss(
89 struct bgscan_learn_data *data, const u8 *bssid)
91 struct bgscan_learn_bss *bss;
93 dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) {
94 if (os_memcmp(bss->bssid, bssid, ETH_ALEN) == 0)
101 static int bgscan_learn_load(struct bgscan_learn_data *data)
105 struct bgscan_learn_bss *bss;
107 if (data->fname == NULL)
110 f = fopen(data->fname, "r");
114 wpa_printf(MSG_DEBUG, "bgscan learn: Loading data from %s",
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",
125 while (fgets(buf, sizeof(buf), f)) {
126 if (os_strncmp(buf, "BSS ", 4) == 0) {
127 bss = os_zalloc(sizeof(*bss));
130 if (hwaddr_aton(buf + 4, bss->bssid) < 0) {
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);
141 if (os_strncmp(buf, "NEIGHBOR ", 9) == 0) {
144 if (hwaddr_aton(buf + 9, addr) < 0)
146 bss = bgscan_learn_get_bss(data, addr);
149 if (hwaddr_aton(buf + 9 + 18, addr) < 0)
152 bgscan_learn_add_neighbor(bss, addr);
161 static void bgscan_learn_save(struct bgscan_learn_data *data)
164 struct bgscan_learn_bss *bss;
166 if (data->fname == NULL)
169 wpa_printf(MSG_DEBUG, "bgscan learn: Saving data to %s",
172 f = fopen(data->fname, "w");
175 fprintf(f, "wpa_supplicant-bgscan-learn\n");
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);
182 dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) {
184 for (i = 0; i < bss->num_neigh; i++) {
185 fprintf(f, "NEIGHBOR " MACSTR " " MACSTR "\n",
187 MAC2STR(bss->neigh + i * ETH_ALEN));
195 static int in_array(int *array, int val)
202 for (i = 0; array[i]; i++) {
211 static int * bgscan_learn_get_freqs(struct bgscan_learn_data *data,
214 struct bgscan_learn_bss *bss;
215 int *freqs = NULL, *n;
219 dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) {
220 if (in_array(freqs, bss->freq))
222 n = os_realloc_array(freqs, *count + 2, sizeof(int));
226 freqs[*count] = bss->freq;
235 static int * bgscan_learn_get_probe_freq(struct bgscan_learn_data *data,
236 int *freqs, size_t count)
240 if (data->supp_freqs == NULL)
243 idx = data->probe_idx;
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)
251 n = os_realloc_array(freqs, count + 2, sizeof(int));
255 freqs[count] = data->supp_freqs[idx];
262 if (data->supp_freqs[idx] == 0)
264 } while (idx != data->probe_idx);
270 static void bgscan_learn_timeout(void *eloop_ctx, void *timeout_ctx)
272 struct bgscan_learn_data *data = eloop_ctx;
273 struct wpa_supplicant *wpa_s = data->wpa_s;
274 struct wpa_driver_scan_params params;
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;
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);
293 for (i = 0; freqs && freqs[i]; i++) {
295 ret = os_snprintf(pos, msg + sizeof(msg) - pos, " %d",
297 if (ret < 0 || ret >= msg + sizeof(msg) - pos)
302 wpa_printf(MSG_DEBUG, "bgscan learn: Scanning frequencies:%s",
304 params.freqs = freqs;
307 wpa_printf(MSG_DEBUG, "bgscan learn: Request a background scan");
308 if (wpa_supplicant_trigger_scan(wpa_s, ¶ms)) {
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);
313 os_get_reltime(&data->last_bgscan);
318 static int bgscan_learn_get_params(struct bgscan_learn_data *data,
326 data->short_interval = atoi(params);
328 pos = os_strchr(params, ':');
332 data->signal_threshold = atoi(pos);
333 pos = os_strchr(pos, ':');
335 wpa_printf(MSG_ERROR, "bgscan learn: Missing scan interval "
340 data->long_interval = atoi(pos);
341 pos = os_strchr(pos, ':');
344 data->fname = os_strdup(pos);
351 static int * bgscan_learn_get_supp_freqs(struct wpa_supplicant *wpa_s)
353 struct hostapd_hw_modes *modes;
354 int i, j, *freqs = NULL, *n;
357 modes = wpa_s->hw.modes;
361 for (i = 0; i < wpa_s->hw.num_modes; i++) {
362 for (j = 0; j < modes[i].num_channels; j++) {
363 if (modes[i].channels[j].flag & HOSTAPD_CHAN_DISABLED)
365 /* some hw modes (e.g. 11b & 11g) contain same freqs */
366 if (in_array(freqs, modes[i].channels[j].freq))
368 n = os_realloc_array(freqs, count + 2, sizeof(int));
373 freqs[count] = modes[i].channels[j].freq;
383 static void * bgscan_learn_init(struct wpa_supplicant *wpa_s,
385 const struct wpa_ssid *ssid)
387 struct bgscan_learn_data *data;
389 data = os_zalloc(sizeof(*data));
392 dl_list_init(&data->bss);
395 if (bgscan_learn_get_params(data, params) < 0) {
396 os_free(data->fname);
400 if (data->short_interval <= 0)
401 data->short_interval = 30;
402 if (data->long_interval <= 0)
403 data->long_interval = 30;
405 if (bgscan_learn_load(data) < 0) {
406 os_free(data->fname);
411 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);
416 if (data->signal_threshold &&
417 wpa_drv_signal_monitor(wpa_s, data->signal_threshold, 4) < 0) {
418 wpa_printf(MSG_ERROR, "bgscan learn: Failed to enable "
419 "signal strength monitoring");
422 data->supp_freqs = bgscan_learn_get_supp_freqs(wpa_s);
423 data->scan_interval = data->short_interval;
424 if (data->signal_threshold) {
425 /* Poll for signal info to set initial scan interval */
426 struct wpa_signal_info siginfo;
427 if (wpa_drv_signal_poll(wpa_s, &siginfo) == 0 &&
428 siginfo.current_signal >= data->signal_threshold)
429 data->scan_interval = data->long_interval;
432 eloop_register_timeout(data->scan_interval, 0, bgscan_learn_timeout,
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.
441 os_get_reltime(&data->last_bgscan);
447 static void bgscan_learn_deinit(void *priv)
449 struct bgscan_learn_data *data = priv;
450 struct bgscan_learn_bss *bss, *n;
452 bgscan_learn_save(data);
453 eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
454 if (data->signal_threshold)
455 wpa_drv_signal_monitor(data->wpa_s, 0, 0);
456 os_free(data->fname);
457 dl_list_for_each_safe(bss, n, &data->bss, struct bgscan_learn_bss,
459 dl_list_del(&bss->list);
462 os_free(data->supp_freqs);
467 static int bgscan_learn_bss_match(struct bgscan_learn_data *data,
468 struct wpa_scan_res *bss)
472 ie = wpa_scan_get_ie(bss, WLAN_EID_SSID);
476 if (data->ssid->ssid_len != ie[1] ||
477 os_memcmp(data->ssid->ssid, ie + 2, ie[1]) != 0)
478 return 0; /* SSID mismatch */
484 static int bgscan_learn_notify_scan(void *priv,
485 struct wpa_scan_results *scan_res)
487 struct bgscan_learn_data *data = priv;
490 u8 bssid[MAX_BSS * ETH_ALEN];
491 size_t num_bssid = 0;
493 wpa_printf(MSG_DEBUG, "bgscan learn: scan result notification");
495 eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
496 eloop_register_timeout(data->scan_interval, 0, bgscan_learn_timeout,
499 for (i = 0; i < scan_res->num; i++) {
500 struct wpa_scan_res *res = scan_res->res[i];
501 if (!bgscan_learn_bss_match(data, res))
504 if (num_bssid < MAX_BSS) {
505 os_memcpy(bssid + num_bssid * ETH_ALEN, res->bssid,
510 wpa_printf(MSG_DEBUG, "bgscan learn: %u matching BSSes in scan "
511 "results", (unsigned int) num_bssid);
513 for (i = 0; i < scan_res->num; i++) {
514 struct wpa_scan_res *res = scan_res->res[i];
515 struct bgscan_learn_bss *bss;
517 if (!bgscan_learn_bss_match(data, res))
520 bss = bgscan_learn_get_bss(data, res->bssid);
521 if (bss && bss->freq != res->freq) {
522 wpa_printf(MSG_DEBUG, "bgscan learn: Update BSS "
523 MACSTR " freq %d -> %d",
524 MAC2STR(res->bssid), bss->freq, res->freq);
525 bss->freq = res->freq;
527 wpa_printf(MSG_DEBUG, "bgscan learn: Add BSS " MACSTR
528 " freq=%d", MAC2STR(res->bssid), res->freq);
529 bss = os_zalloc(sizeof(*bss));
532 os_memcpy(bss->bssid, res->bssid, ETH_ALEN);
533 bss->freq = res->freq;
534 dl_list_add(&data->bss, &bss->list);
537 for (j = 0; j < num_bssid; j++) {
538 u8 *addr = bssid + j * ETH_ALEN;
539 bgscan_learn_add_neighbor(bss, addr);
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.
554 static void bgscan_learn_notify_beacon_loss(void *priv)
556 wpa_printf(MSG_DEBUG, "bgscan learn: beacon loss");
557 /* TODO: speed up background scanning */
561 static void bgscan_learn_notify_signal_change(void *priv, int above,
566 struct bgscan_learn_data *data = priv;
568 struct os_reltime now;
570 if (data->short_interval == data->long_interval ||
571 data->signal_threshold == 0)
574 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 if (data->scan_interval == data->long_interval && !above) {
579 wpa_printf(MSG_DEBUG, "bgscan learn: Start using short bgscan "
581 data->scan_interval = data->short_interval;
582 os_get_reltime(&now);
583 if (now.sec > data->last_bgscan.sec + 1)
585 } else if (data->scan_interval == data->short_interval && above) {
586 wpa_printf(MSG_DEBUG, "bgscan learn: Start using long bgscan "
588 data->scan_interval = data->long_interval;
589 eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
590 eloop_register_timeout(data->scan_interval, 0,
591 bgscan_learn_timeout, data, NULL);
594 * Signal dropped further 4 dB. Request a new scan if we have
595 * not yet scanned in a while.
597 os_get_reltime(&now);
598 if (now.sec > data->last_bgscan.sec + 10)
603 wpa_printf(MSG_DEBUG, "bgscan learn: Trigger immediate scan");
604 eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
605 eloop_register_timeout(0, 0, bgscan_learn_timeout, data, NULL);
610 const struct bgscan_ops bgscan_learn_ops = {
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,