2 * WPA Supplicant - background scan and roaming module: simple
3 * Copyright (c) 2009-2010, Jouni Malinen <j@w1.fi>
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
9 * Alternatively, this software may be distributed under the terms of BSD
12 * See README and COPYING for more details.
19 #include "drivers/driver.h"
20 #include "config_ssid.h"
21 #include "wpa_supplicant_i.h"
26 struct bgscan_simple_data {
27 struct wpa_supplicant *wpa_s;
28 const struct wpa_ssid *ssid;
31 int short_interval; /* use if signal < threshold */
32 int long_interval; /* use if signal > threshold */
33 struct os_time last_bgscan;
37 static void bgscan_simple_timeout(void *eloop_ctx, void *timeout_ctx)
39 struct bgscan_simple_data *data = eloop_ctx;
40 struct wpa_supplicant *wpa_s = data->wpa_s;
41 struct wpa_driver_scan_params params;
43 os_memset(¶ms, 0, sizeof(params));
45 params.ssids[0].ssid = data->ssid->ssid;
46 params.ssids[0].ssid_len = data->ssid->ssid_len;
47 params.freqs = data->ssid->scan_freq;
50 * A more advanced bgscan module would learn about most like channels
51 * over time and request scans only for some channels (probing others
52 * every now and then) to reduce effect on the data connection.
55 wpa_printf(MSG_DEBUG, "bgscan simple: Request a background scan");
56 if (wpa_supplicant_trigger_scan(wpa_s, ¶ms)) {
57 wpa_printf(MSG_DEBUG, "bgscan simple: Failed to trigger scan");
58 eloop_register_timeout(data->scan_interval, 0,
59 bgscan_simple_timeout, data, NULL);
61 os_get_time(&data->last_bgscan);
65 static int bgscan_simple_get_params(struct bgscan_simple_data *data,
73 data->short_interval = atoi(params);
75 pos = os_strchr(params, ':');
79 data->signal_threshold = atoi(pos);
80 pos = os_strchr(pos, ':');
82 wpa_printf(MSG_ERROR, "bgscan simple: Missing scan interval "
87 data->long_interval = atoi(pos);
93 static void * bgscan_simple_init(struct wpa_supplicant *wpa_s,
95 const struct wpa_ssid *ssid)
97 struct bgscan_simple_data *data;
99 data = os_zalloc(sizeof(*data));
104 if (bgscan_simple_get_params(data, params) < 0) {
108 if (data->short_interval <= 0)
109 data->short_interval = 30;
110 if (data->long_interval <= 0)
111 data->long_interval = 30;
113 wpa_printf(MSG_DEBUG, "bgscan simple: Signal strength threshold %d "
114 "Short bgscan interval %d Long bgscan interval %d",
115 data->signal_threshold, data->short_interval,
116 data->long_interval);
118 if (data->signal_threshold &&
119 wpa_drv_signal_monitor(wpa_s, data->signal_threshold, 4) < 0) {
120 wpa_printf(MSG_ERROR, "bgscan simple: Failed to enable "
121 "signal strength monitoring");
124 data->scan_interval = data->short_interval;
125 eloop_register_timeout(data->scan_interval, 0, bgscan_simple_timeout,
129 * This function is called immediately after an association, so it is
130 * reasonable to assume that a scan was completed recently. This makes
131 * us skip an immediate new scan in cases where the current signal
132 * level is below the bgscan threshold.
134 os_get_time(&data->last_bgscan);
140 static void bgscan_simple_deinit(void *priv)
142 struct bgscan_simple_data *data = priv;
143 eloop_cancel_timeout(bgscan_simple_timeout, data, NULL);
144 if (data->signal_threshold)
145 wpa_drv_signal_monitor(data->wpa_s, 0, 0);
150 static int bgscan_simple_notify_scan(void *priv,
151 struct wpa_scan_results *scan_res)
153 struct bgscan_simple_data *data = priv;
155 wpa_printf(MSG_DEBUG, "bgscan simple: scan result notification");
157 eloop_cancel_timeout(bgscan_simple_timeout, data, NULL);
158 eloop_register_timeout(data->scan_interval, 0, bgscan_simple_timeout,
162 * A more advanced bgscan could process scan results internally, select
163 * the BSS and request roam if needed. This sample uses the existing
164 * BSS/ESS selection routine. Change this to return 1 if selection is
165 * done inside the bgscan module.
172 static void bgscan_simple_notify_beacon_loss(void *priv)
174 wpa_printf(MSG_DEBUG, "bgscan simple: beacon loss");
175 /* TODO: speed up background scanning */
179 static void bgscan_simple_notify_signal_change(void *priv, int above,
182 struct bgscan_simple_data *data = priv;
186 if (data->short_interval == data->long_interval ||
187 data->signal_threshold == 0)
190 wpa_printf(MSG_DEBUG, "bgscan simple: signal level changed "
191 "(above=%d current_signal=%d)", above, current_signal);
192 if (data->scan_interval == data->long_interval && !above) {
193 wpa_printf(MSG_DEBUG, "bgscan simple: Start using short "
195 data->scan_interval = data->short_interval;
197 if (now.sec > data->last_bgscan.sec + 1)
199 } else if (data->scan_interval == data->short_interval && above) {
200 wpa_printf(MSG_DEBUG, "bgscan simple: Start using long bgscan "
202 data->scan_interval = data->long_interval;
203 eloop_cancel_timeout(bgscan_simple_timeout, data, NULL);
204 eloop_register_timeout(data->scan_interval, 0,
205 bgscan_simple_timeout, data, NULL);
208 * Signal dropped further 4 dB. Request a new scan if we have
209 * not yet scanned in a while.
212 if (now.sec > data->last_bgscan.sec + 10)
217 wpa_printf(MSG_DEBUG, "bgscan simple: Trigger immediate scan");
218 eloop_cancel_timeout(bgscan_simple_timeout, data, NULL);
219 eloop_register_timeout(0, 0, bgscan_simple_timeout, data,
225 const struct bgscan_ops bgscan_simple_ops = {
227 .init = bgscan_simple_init,
228 .deinit = bgscan_simple_deinit,
229 .notify_scan = bgscan_simple_notify_scan,
230 .notify_beacon_loss = bgscan_simple_notify_beacon_loss,
231 .notify_signal_change = bgscan_simple_notify_signal_change,