2 * WPA Supplicant - background scan and roaming module: simple
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.
13 #include "drivers/driver.h"
14 #include "config_ssid.h"
15 #include "wpa_supplicant_i.h"
20 struct bgscan_simple_data
{
21 struct wpa_supplicant
*wpa_s
;
22 const struct wpa_ssid
*ssid
;
25 int short_scan_count
; /* counter for scans using short scan interval */
26 int max_short_scans
; /* maximum times we short-scan before back-off */
27 int short_interval
; /* use if signal < threshold */
28 int long_interval
; /* use if signal > threshold */
29 struct os_reltime last_bgscan
;
33 static void bgscan_simple_timeout(void *eloop_ctx
, void *timeout_ctx
)
35 struct bgscan_simple_data
*data
= eloop_ctx
;
36 struct wpa_supplicant
*wpa_s
= data
->wpa_s
;
37 struct wpa_driver_scan_params params
;
39 os_memset(¶ms
, 0, sizeof(params
));
41 params
.ssids
[0].ssid
= data
->ssid
->ssid
;
42 params
.ssids
[0].ssid_len
= data
->ssid
->ssid_len
;
43 params
.freqs
= data
->ssid
->scan_freq
;
46 * A more advanced bgscan module would learn about most like channels
47 * over time and request scans only for some channels (probing others
48 * every now and then) to reduce effect on the data connection.
51 wpa_printf(MSG_DEBUG
, "bgscan simple: Request a background scan");
52 if (wpa_supplicant_trigger_scan(wpa_s
, ¶ms
)) {
53 wpa_printf(MSG_DEBUG
, "bgscan simple: Failed to trigger scan");
54 eloop_register_timeout(data
->scan_interval
, 0,
55 bgscan_simple_timeout
, data
, NULL
);
57 if (data
->scan_interval
== data
->short_interval
) {
58 data
->short_scan_count
++;
59 if (data
->short_scan_count
>= data
->max_short_scans
) {
60 data
->scan_interval
= data
->long_interval
;
61 wpa_printf(MSG_DEBUG
, "bgscan simple: Backing "
62 "off to long scan interval");
64 } else if (data
->short_scan_count
> 0) {
66 * If we lasted a long scan interval without any
67 * CQM triggers, decrease the short-scan count,
68 * which allows 1 more short-scan interval to
69 * occur in the future when CQM triggers.
71 data
->short_scan_count
--;
73 os_get_reltime(&data
->last_bgscan
);
78 static int bgscan_simple_get_params(struct bgscan_simple_data
*data
,
83 data
->short_interval
= atoi(params
);
85 pos
= os_strchr(params
, ':');
89 data
->signal_threshold
= atoi(pos
);
90 pos
= os_strchr(pos
, ':');
92 wpa_printf(MSG_ERROR
, "bgscan simple: Missing scan interval "
97 data
->long_interval
= atoi(pos
);
103 static void * bgscan_simple_init(struct wpa_supplicant
*wpa_s
,
105 const struct wpa_ssid
*ssid
)
107 struct bgscan_simple_data
*data
;
109 data
= os_zalloc(sizeof(*data
));
114 if (bgscan_simple_get_params(data
, params
) < 0) {
118 if (data
->short_interval
<= 0)
119 data
->short_interval
= 30;
120 if (data
->long_interval
<= 0)
121 data
->long_interval
= 30;
123 wpa_printf(MSG_DEBUG
, "bgscan simple: Signal strength threshold %d "
124 "Short bgscan interval %d Long bgscan interval %d",
125 data
->signal_threshold
, data
->short_interval
,
126 data
->long_interval
);
128 if (data
->signal_threshold
&&
129 wpa_drv_signal_monitor(wpa_s
, data
->signal_threshold
, 4) < 0) {
130 wpa_printf(MSG_ERROR
, "bgscan simple: Failed to enable "
131 "signal strength monitoring");
134 data
->scan_interval
= data
->short_interval
;
135 data
->max_short_scans
= data
->long_interval
/ data
->short_interval
+ 1;
136 if (data
->signal_threshold
) {
137 /* Poll for signal info to set initial scan interval */
138 struct wpa_signal_info siginfo
;
139 if (wpa_drv_signal_poll(wpa_s
, &siginfo
) == 0 &&
140 siginfo
.current_signal
>= data
->signal_threshold
)
141 data
->scan_interval
= data
->long_interval
;
143 wpa_printf(MSG_DEBUG
, "bgscan simple: Init scan interval: %d",
144 data
->scan_interval
);
145 eloop_register_timeout(data
->scan_interval
, 0, bgscan_simple_timeout
,
149 * This function is called immediately after an association, so it is
150 * reasonable to assume that a scan was completed recently. This makes
151 * us skip an immediate new scan in cases where the current signal
152 * level is below the bgscan threshold.
154 os_get_reltime(&data
->last_bgscan
);
160 static void bgscan_simple_deinit(void *priv
)
162 struct bgscan_simple_data
*data
= priv
;
163 eloop_cancel_timeout(bgscan_simple_timeout
, data
, NULL
);
164 if (data
->signal_threshold
)
165 wpa_drv_signal_monitor(data
->wpa_s
, 0, 0);
170 static int bgscan_simple_notify_scan(void *priv
,
171 struct wpa_scan_results
*scan_res
)
173 struct bgscan_simple_data
*data
= priv
;
175 wpa_printf(MSG_DEBUG
, "bgscan simple: scan result notification");
177 eloop_cancel_timeout(bgscan_simple_timeout
, data
, NULL
);
178 eloop_register_timeout(data
->scan_interval
, 0, bgscan_simple_timeout
,
182 * A more advanced bgscan could process scan results internally, select
183 * the BSS and request roam if needed. This sample uses the existing
184 * BSS/ESS selection routine. Change this to return 1 if selection is
185 * done inside the bgscan module.
192 static void bgscan_simple_notify_beacon_loss(void *priv
)
194 wpa_printf(MSG_DEBUG
, "bgscan simple: beacon loss");
195 /* TODO: speed up background scanning */
199 static void bgscan_simple_notify_signal_change(void *priv
, int above
,
204 struct bgscan_simple_data
*data
= priv
;
206 struct os_reltime now
;
208 if (data
->short_interval
== data
->long_interval
||
209 data
->signal_threshold
== 0)
212 wpa_printf(MSG_DEBUG
, "bgscan simple: signal level changed "
213 "(above=%d current_signal=%d current_noise=%d "
214 "current_txrate=%d))", above
, current_signal
,
215 current_noise
, current_txrate
);
216 if (data
->scan_interval
== data
->long_interval
&& !above
) {
217 wpa_printf(MSG_DEBUG
, "bgscan simple: Start using short "
219 data
->scan_interval
= data
->short_interval
;
220 os_get_reltime(&now
);
221 if (now
.sec
> data
->last_bgscan
.sec
+ 1 &&
222 data
->short_scan_count
<= data
->max_short_scans
)
224 * If we haven't just previously (<1 second ago)
225 * performed a scan, and we haven't depleted our
226 * budget for short-scans, perform a scan
230 else if (data
->last_bgscan
.sec
+ data
->long_interval
>
231 now
.sec
+ data
->scan_interval
) {
233 * Restart scan interval timer if currently scheduled
234 * scan is too far in the future.
236 eloop_cancel_timeout(bgscan_simple_timeout
, data
,
238 eloop_register_timeout(data
->scan_interval
, 0,
239 bgscan_simple_timeout
, data
,
242 } else if (data
->scan_interval
== data
->short_interval
&& above
) {
243 wpa_printf(MSG_DEBUG
, "bgscan simple: Start using long bgscan "
245 data
->scan_interval
= data
->long_interval
;
246 eloop_cancel_timeout(bgscan_simple_timeout
, data
, NULL
);
247 eloop_register_timeout(data
->scan_interval
, 0,
248 bgscan_simple_timeout
, data
, NULL
);
251 * Signal dropped further 4 dB. Request a new scan if we have
252 * not yet scanned in a while.
254 os_get_reltime(&now
);
255 if (now
.sec
> data
->last_bgscan
.sec
+ 10)
260 wpa_printf(MSG_DEBUG
, "bgscan simple: Trigger immediate scan");
261 eloop_cancel_timeout(bgscan_simple_timeout
, data
, NULL
);
262 eloop_register_timeout(0, 0, bgscan_simple_timeout
, data
,
268 const struct bgscan_ops bgscan_simple_ops
= {
270 .init
= bgscan_simple_init
,
271 .deinit
= bgscan_simple_deinit
,
272 .notify_scan
= bgscan_simple_notify_scan
,
273 .notify_beacon_loss
= bgscan_simple_notify_beacon_loss
,
274 .notify_signal_change
= bgscan_simple_notify_signal_change
,