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 (os_snprintf_error(msg
+ sizeof(msg
) - pos
, ret
))
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
,