1e28a4053SRui Paulo /*
2e28a4053SRui Paulo * WPA Supplicant - background scan and roaming module: simple
3e28a4053SRui Paulo * Copyright (c) 2009-2010, Jouni Malinen <j@w1.fi>
4e28a4053SRui Paulo *
5f05cddf9SRui Paulo * This software may be distributed under the terms of the BSD license.
6f05cddf9SRui Paulo * See README for more details.
7e28a4053SRui Paulo */
8e28a4053SRui Paulo
9e28a4053SRui Paulo #include "includes.h"
10e28a4053SRui Paulo
11e28a4053SRui Paulo #include "common.h"
12e28a4053SRui Paulo #include "eloop.h"
13e28a4053SRui Paulo #include "drivers/driver.h"
14e28a4053SRui Paulo #include "config_ssid.h"
15e28a4053SRui Paulo #include "wpa_supplicant_i.h"
16e28a4053SRui Paulo #include "driver_i.h"
17e28a4053SRui Paulo #include "scan.h"
18e28a4053SRui Paulo #include "bgscan.h"
19e28a4053SRui Paulo
20e28a4053SRui Paulo struct bgscan_simple_data {
21e28a4053SRui Paulo struct wpa_supplicant *wpa_s;
22e28a4053SRui Paulo const struct wpa_ssid *ssid;
23e28a4053SRui Paulo int scan_interval;
24e28a4053SRui Paulo int signal_threshold;
25f05cddf9SRui Paulo int short_scan_count; /* counter for scans using short scan interval */
26f05cddf9SRui Paulo int max_short_scans; /* maximum times we short-scan before back-off */
27e28a4053SRui Paulo int short_interval; /* use if signal < threshold */
28e28a4053SRui Paulo int long_interval; /* use if signal > threshold */
295b9c547cSRui Paulo struct os_reltime last_bgscan;
30e28a4053SRui Paulo };
31e28a4053SRui Paulo
32e28a4053SRui Paulo
bgscan_simple_timeout(void * eloop_ctx,void * timeout_ctx)33e28a4053SRui Paulo static void bgscan_simple_timeout(void *eloop_ctx, void *timeout_ctx)
34e28a4053SRui Paulo {
35e28a4053SRui Paulo struct bgscan_simple_data *data = eloop_ctx;
36e28a4053SRui Paulo struct wpa_supplicant *wpa_s = data->wpa_s;
37e28a4053SRui Paulo struct wpa_driver_scan_params params;
38e28a4053SRui Paulo
39e28a4053SRui Paulo os_memset(¶ms, 0, sizeof(params));
40e28a4053SRui Paulo params.num_ssids = 1;
41e28a4053SRui Paulo params.ssids[0].ssid = data->ssid->ssid;
42e28a4053SRui Paulo params.ssids[0].ssid_len = data->ssid->ssid_len;
43e28a4053SRui Paulo params.freqs = data->ssid->scan_freq;
44e28a4053SRui Paulo
45e28a4053SRui Paulo /*
46e28a4053SRui Paulo * A more advanced bgscan module would learn about most like channels
47e28a4053SRui Paulo * over time and request scans only for some channels (probing others
48e28a4053SRui Paulo * every now and then) to reduce effect on the data connection.
49e28a4053SRui Paulo */
50e28a4053SRui Paulo
51e28a4053SRui Paulo wpa_printf(MSG_DEBUG, "bgscan simple: Request a background scan");
52e28a4053SRui Paulo if (wpa_supplicant_trigger_scan(wpa_s, ¶ms)) {
53e28a4053SRui Paulo wpa_printf(MSG_DEBUG, "bgscan simple: Failed to trigger scan");
54e28a4053SRui Paulo eloop_register_timeout(data->scan_interval, 0,
55e28a4053SRui Paulo bgscan_simple_timeout, data, NULL);
56f05cddf9SRui Paulo } else {
57f05cddf9SRui Paulo if (data->scan_interval == data->short_interval) {
58f05cddf9SRui Paulo data->short_scan_count++;
59*85732ac8SCy Schubert if (data->short_scan_count >= data->max_short_scans) {
60f05cddf9SRui Paulo data->scan_interval = data->long_interval;
61f05cddf9SRui Paulo wpa_printf(MSG_DEBUG, "bgscan simple: Backing "
62f05cddf9SRui Paulo "off to long scan interval");
63f05cddf9SRui Paulo }
64f05cddf9SRui Paulo } else if (data->short_scan_count > 0) {
65f05cddf9SRui Paulo /*
66f05cddf9SRui Paulo * If we lasted a long scan interval without any
67f05cddf9SRui Paulo * CQM triggers, decrease the short-scan count,
68f05cddf9SRui Paulo * which allows 1 more short-scan interval to
69f05cddf9SRui Paulo * occur in the future when CQM triggers.
70f05cddf9SRui Paulo */
71f05cddf9SRui Paulo data->short_scan_count--;
72f05cddf9SRui Paulo }
735b9c547cSRui Paulo os_get_reltime(&data->last_bgscan);
74e28a4053SRui Paulo }
75f05cddf9SRui Paulo }
76e28a4053SRui Paulo
77e28a4053SRui Paulo
bgscan_simple_get_params(struct bgscan_simple_data * data,const char * params)78e28a4053SRui Paulo static int bgscan_simple_get_params(struct bgscan_simple_data *data,
79e28a4053SRui Paulo const char *params)
80e28a4053SRui Paulo {
81e28a4053SRui Paulo const char *pos;
82e28a4053SRui Paulo
83e28a4053SRui Paulo data->short_interval = atoi(params);
84e28a4053SRui Paulo
85e28a4053SRui Paulo pos = os_strchr(params, ':');
86e28a4053SRui Paulo if (pos == NULL)
87e28a4053SRui Paulo return 0;
88e28a4053SRui Paulo pos++;
89e28a4053SRui Paulo data->signal_threshold = atoi(pos);
90e28a4053SRui Paulo pos = os_strchr(pos, ':');
91e28a4053SRui Paulo if (pos == NULL) {
92e28a4053SRui Paulo wpa_printf(MSG_ERROR, "bgscan simple: Missing scan interval "
93e28a4053SRui Paulo "for high signal");
94e28a4053SRui Paulo return -1;
95e28a4053SRui Paulo }
96e28a4053SRui Paulo pos++;
97e28a4053SRui Paulo data->long_interval = atoi(pos);
98e28a4053SRui Paulo
99e28a4053SRui Paulo return 0;
100e28a4053SRui Paulo }
101e28a4053SRui Paulo
102e28a4053SRui Paulo
bgscan_simple_init(struct wpa_supplicant * wpa_s,const char * params,const struct wpa_ssid * ssid)103e28a4053SRui Paulo static void * bgscan_simple_init(struct wpa_supplicant *wpa_s,
104e28a4053SRui Paulo const char *params,
105e28a4053SRui Paulo const struct wpa_ssid *ssid)
106e28a4053SRui Paulo {
107e28a4053SRui Paulo struct bgscan_simple_data *data;
108e28a4053SRui Paulo
109e28a4053SRui Paulo data = os_zalloc(sizeof(*data));
110e28a4053SRui Paulo if (data == NULL)
111e28a4053SRui Paulo return NULL;
112e28a4053SRui Paulo data->wpa_s = wpa_s;
113e28a4053SRui Paulo data->ssid = ssid;
114e28a4053SRui Paulo if (bgscan_simple_get_params(data, params) < 0) {
115e28a4053SRui Paulo os_free(data);
116e28a4053SRui Paulo return NULL;
117e28a4053SRui Paulo }
118e28a4053SRui Paulo if (data->short_interval <= 0)
119e28a4053SRui Paulo data->short_interval = 30;
120e28a4053SRui Paulo if (data->long_interval <= 0)
121e28a4053SRui Paulo data->long_interval = 30;
122e28a4053SRui Paulo
123e28a4053SRui Paulo wpa_printf(MSG_DEBUG, "bgscan simple: Signal strength threshold %d "
124e28a4053SRui Paulo "Short bgscan interval %d Long bgscan interval %d",
125e28a4053SRui Paulo data->signal_threshold, data->short_interval,
126e28a4053SRui Paulo data->long_interval);
127e28a4053SRui Paulo
128e28a4053SRui Paulo if (data->signal_threshold &&
129e28a4053SRui Paulo wpa_drv_signal_monitor(wpa_s, data->signal_threshold, 4) < 0) {
130e28a4053SRui Paulo wpa_printf(MSG_ERROR, "bgscan simple: Failed to enable "
131e28a4053SRui Paulo "signal strength monitoring");
132e28a4053SRui Paulo }
133e28a4053SRui Paulo
134e28a4053SRui Paulo data->scan_interval = data->short_interval;
135f05cddf9SRui Paulo data->max_short_scans = data->long_interval / data->short_interval + 1;
136f05cddf9SRui Paulo if (data->signal_threshold) {
137f05cddf9SRui Paulo /* Poll for signal info to set initial scan interval */
138f05cddf9SRui Paulo struct wpa_signal_info siginfo;
139f05cddf9SRui Paulo if (wpa_drv_signal_poll(wpa_s, &siginfo) == 0 &&
140f05cddf9SRui Paulo siginfo.current_signal >= data->signal_threshold)
141f05cddf9SRui Paulo data->scan_interval = data->long_interval;
142f05cddf9SRui Paulo }
143f05cddf9SRui Paulo wpa_printf(MSG_DEBUG, "bgscan simple: Init scan interval: %d",
144f05cddf9SRui Paulo data->scan_interval);
145e28a4053SRui Paulo eloop_register_timeout(data->scan_interval, 0, bgscan_simple_timeout,
146e28a4053SRui Paulo data, NULL);
147e28a4053SRui Paulo
148e28a4053SRui Paulo /*
149e28a4053SRui Paulo * This function is called immediately after an association, so it is
150e28a4053SRui Paulo * reasonable to assume that a scan was completed recently. This makes
151e28a4053SRui Paulo * us skip an immediate new scan in cases where the current signal
152e28a4053SRui Paulo * level is below the bgscan threshold.
153e28a4053SRui Paulo */
1545b9c547cSRui Paulo os_get_reltime(&data->last_bgscan);
155e28a4053SRui Paulo
156e28a4053SRui Paulo return data;
157e28a4053SRui Paulo }
158e28a4053SRui Paulo
159e28a4053SRui Paulo
bgscan_simple_deinit(void * priv)160e28a4053SRui Paulo static void bgscan_simple_deinit(void *priv)
161e28a4053SRui Paulo {
162e28a4053SRui Paulo struct bgscan_simple_data *data = priv;
163e28a4053SRui Paulo eloop_cancel_timeout(bgscan_simple_timeout, data, NULL);
164e28a4053SRui Paulo if (data->signal_threshold)
165e28a4053SRui Paulo wpa_drv_signal_monitor(data->wpa_s, 0, 0);
166e28a4053SRui Paulo os_free(data);
167e28a4053SRui Paulo }
168e28a4053SRui Paulo
169e28a4053SRui Paulo
bgscan_simple_notify_scan(void * priv,struct wpa_scan_results * scan_res)170f05cddf9SRui Paulo static int bgscan_simple_notify_scan(void *priv,
171f05cddf9SRui Paulo struct wpa_scan_results *scan_res)
172e28a4053SRui Paulo {
173e28a4053SRui Paulo struct bgscan_simple_data *data = priv;
174e28a4053SRui Paulo
175e28a4053SRui Paulo wpa_printf(MSG_DEBUG, "bgscan simple: scan result notification");
176e28a4053SRui Paulo
177e28a4053SRui Paulo eloop_cancel_timeout(bgscan_simple_timeout, data, NULL);
178e28a4053SRui Paulo eloop_register_timeout(data->scan_interval, 0, bgscan_simple_timeout,
179e28a4053SRui Paulo data, NULL);
180e28a4053SRui Paulo
181e28a4053SRui Paulo /*
182e28a4053SRui Paulo * A more advanced bgscan could process scan results internally, select
183e28a4053SRui Paulo * the BSS and request roam if needed. This sample uses the existing
184e28a4053SRui Paulo * BSS/ESS selection routine. Change this to return 1 if selection is
185e28a4053SRui Paulo * done inside the bgscan module.
186e28a4053SRui Paulo */
187e28a4053SRui Paulo
188e28a4053SRui Paulo return 0;
189e28a4053SRui Paulo }
190e28a4053SRui Paulo
191e28a4053SRui Paulo
bgscan_simple_notify_beacon_loss(void * priv)192e28a4053SRui Paulo static void bgscan_simple_notify_beacon_loss(void *priv)
193e28a4053SRui Paulo {
194e28a4053SRui Paulo wpa_printf(MSG_DEBUG, "bgscan simple: beacon loss");
195e28a4053SRui Paulo /* TODO: speed up background scanning */
196e28a4053SRui Paulo }
197e28a4053SRui Paulo
198e28a4053SRui Paulo
bgscan_simple_notify_signal_change(void * priv,int above,int current_signal,int current_noise,int current_txrate)199f05cddf9SRui Paulo static void bgscan_simple_notify_signal_change(void *priv, int above,
200f05cddf9SRui Paulo int current_signal,
201f05cddf9SRui Paulo int current_noise,
202f05cddf9SRui Paulo int current_txrate)
203e28a4053SRui Paulo {
204e28a4053SRui Paulo struct bgscan_simple_data *data = priv;
205e28a4053SRui Paulo int scan = 0;
2065b9c547cSRui Paulo struct os_reltime now;
207e28a4053SRui Paulo
208e28a4053SRui Paulo if (data->short_interval == data->long_interval ||
209e28a4053SRui Paulo data->signal_threshold == 0)
210e28a4053SRui Paulo return;
211e28a4053SRui Paulo
212e28a4053SRui Paulo wpa_printf(MSG_DEBUG, "bgscan simple: signal level changed "
213f05cddf9SRui Paulo "(above=%d current_signal=%d current_noise=%d "
214f05cddf9SRui Paulo "current_txrate=%d))", above, current_signal,
215f05cddf9SRui Paulo current_noise, current_txrate);
216e28a4053SRui Paulo if (data->scan_interval == data->long_interval && !above) {
217e28a4053SRui Paulo wpa_printf(MSG_DEBUG, "bgscan simple: Start using short "
218e28a4053SRui Paulo "bgscan interval");
219e28a4053SRui Paulo data->scan_interval = data->short_interval;
2205b9c547cSRui Paulo os_get_reltime(&now);
221f05cddf9SRui Paulo if (now.sec > data->last_bgscan.sec + 1 &&
222f05cddf9SRui Paulo data->short_scan_count <= data->max_short_scans)
223f05cddf9SRui Paulo /*
224f05cddf9SRui Paulo * If we haven't just previously (<1 second ago)
225f05cddf9SRui Paulo * performed a scan, and we haven't depleted our
226f05cddf9SRui Paulo * budget for short-scans, perform a scan
227f05cddf9SRui Paulo * immediately.
228f05cddf9SRui Paulo */
229e28a4053SRui Paulo scan = 1;
230f05cddf9SRui Paulo else if (data->last_bgscan.sec + data->long_interval >
231f05cddf9SRui Paulo now.sec + data->scan_interval) {
232f05cddf9SRui Paulo /*
233f05cddf9SRui Paulo * Restart scan interval timer if currently scheduled
234f05cddf9SRui Paulo * scan is too far in the future.
235f05cddf9SRui Paulo */
236f05cddf9SRui Paulo eloop_cancel_timeout(bgscan_simple_timeout, data,
237f05cddf9SRui Paulo NULL);
238f05cddf9SRui Paulo eloop_register_timeout(data->scan_interval, 0,
239f05cddf9SRui Paulo bgscan_simple_timeout, data,
240f05cddf9SRui Paulo NULL);
241f05cddf9SRui Paulo }
242e28a4053SRui Paulo } else if (data->scan_interval == data->short_interval && above) {
243e28a4053SRui Paulo wpa_printf(MSG_DEBUG, "bgscan simple: Start using long bgscan "
244e28a4053SRui Paulo "interval");
245e28a4053SRui Paulo data->scan_interval = data->long_interval;
246e28a4053SRui Paulo eloop_cancel_timeout(bgscan_simple_timeout, data, NULL);
247e28a4053SRui Paulo eloop_register_timeout(data->scan_interval, 0,
248e28a4053SRui Paulo bgscan_simple_timeout, data, NULL);
249e28a4053SRui Paulo } else if (!above) {
250e28a4053SRui Paulo /*
251e28a4053SRui Paulo * Signal dropped further 4 dB. Request a new scan if we have
252e28a4053SRui Paulo * not yet scanned in a while.
253e28a4053SRui Paulo */
2545b9c547cSRui Paulo os_get_reltime(&now);
255e28a4053SRui Paulo if (now.sec > data->last_bgscan.sec + 10)
256e28a4053SRui Paulo scan = 1;
257e28a4053SRui Paulo }
258e28a4053SRui Paulo
259e28a4053SRui Paulo if (scan) {
260e28a4053SRui Paulo wpa_printf(MSG_DEBUG, "bgscan simple: Trigger immediate scan");
261e28a4053SRui Paulo eloop_cancel_timeout(bgscan_simple_timeout, data, NULL);
262e28a4053SRui Paulo eloop_register_timeout(0, 0, bgscan_simple_timeout, data,
263e28a4053SRui Paulo NULL);
264e28a4053SRui Paulo }
265e28a4053SRui Paulo }
266e28a4053SRui Paulo
267e28a4053SRui Paulo
268e28a4053SRui Paulo const struct bgscan_ops bgscan_simple_ops = {
269e28a4053SRui Paulo .name = "simple",
270e28a4053SRui Paulo .init = bgscan_simple_init,
271e28a4053SRui Paulo .deinit = bgscan_simple_deinit,
272e28a4053SRui Paulo .notify_scan = bgscan_simple_notify_scan,
273e28a4053SRui Paulo .notify_beacon_loss = bgscan_simple_notify_beacon_loss,
274e28a4053SRui Paulo .notify_signal_change = bgscan_simple_notify_signal_change,
275e28a4053SRui Paulo };
276