/*
* WPA Supplicant - background scan and roaming module: simple
- * Copyright (c) 2009, Jouni Malinen <j@w1.fi>
+ * Copyright (c) 2009-2010, Jouni Malinen <j@w1.fi>
*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- * Alternatively, this software may be distributed under the terms of BSD
- * license.
- *
- * See README and COPYING for more details.
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
*/
#include "includes.h"
#include "drivers/driver.h"
#include "config_ssid.h"
#include "wpa_supplicant_i.h"
+#include "driver_i.h"
#include "scan.h"
#include "bgscan.h"
struct wpa_supplicant *wpa_s;
const struct wpa_ssid *ssid;
int scan_interval;
+ int signal_threshold;
+ int short_scan_count; /* counter for scans using short scan interval */
+ int max_short_scans; /* maximum times we short-scan before back-off */
+ int short_interval; /* use if signal < threshold */
+ int long_interval; /* use if signal > threshold */
+ struct os_reltime last_bgscan;
};
wpa_printf(MSG_DEBUG, "bgscan simple: Failed to trigger scan");
eloop_register_timeout(data->scan_interval, 0,
bgscan_simple_timeout, data, NULL);
+ } else {
+ if (data->scan_interval == data->short_interval) {
+ data->short_scan_count++;
+ /*
+ * Spend at most the duration of a long scan interval
+ * scanning at the short scan interval. After that,
+ * revert to the long scan interval.
+ */
+ if (data->short_scan_count > data->max_short_scans) {
+ data->scan_interval = data->long_interval;
+ wpa_printf(MSG_DEBUG, "bgscan simple: Backing "
+ "off to long scan interval");
+ }
+ } else if (data->short_scan_count > 0) {
+ /*
+ * If we lasted a long scan interval without any
+ * CQM triggers, decrease the short-scan count,
+ * which allows 1 more short-scan interval to
+ * occur in the future when CQM triggers.
+ */
+ data->short_scan_count--;
+ }
+ os_get_reltime(&data->last_bgscan);
+ }
+}
+
+
+static int bgscan_simple_get_params(struct bgscan_simple_data *data,
+ const char *params)
+{
+ const char *pos;
+
+ if (params == NULL)
+ return 0;
+
+ data->short_interval = atoi(params);
+
+ pos = os_strchr(params, ':');
+ if (pos == NULL)
+ return 0;
+ pos++;
+ data->signal_threshold = atoi(pos);
+ pos = os_strchr(pos, ':');
+ if (pos == NULL) {
+ wpa_printf(MSG_ERROR, "bgscan simple: Missing scan interval "
+ "for high signal");
+ return -1;
}
+ pos++;
+ data->long_interval = atoi(pos);
+
+ return 0;
}
return NULL;
data->wpa_s = wpa_s;
data->ssid = ssid;
- if (params)
- data->scan_interval = atoi(params);
- if (data->scan_interval <= 0)
- data->scan_interval = 30;
+ if (bgscan_simple_get_params(data, params) < 0) {
+ os_free(data);
+ return NULL;
+ }
+ if (data->short_interval <= 0)
+ data->short_interval = 30;
+ if (data->long_interval <= 0)
+ data->long_interval = 30;
+
+ wpa_printf(MSG_DEBUG, "bgscan simple: Signal strength threshold %d "
+ "Short bgscan interval %d Long bgscan interval %d",
+ data->signal_threshold, data->short_interval,
+ data->long_interval);
+
+ if (data->signal_threshold &&
+ wpa_drv_signal_monitor(wpa_s, data->signal_threshold, 4) < 0) {
+ wpa_printf(MSG_ERROR, "bgscan simple: Failed to enable "
+ "signal strength monitoring");
+ }
+
+ data->scan_interval = data->short_interval;
+ data->max_short_scans = data->long_interval / data->short_interval + 1;
+ if (data->signal_threshold) {
+ /* Poll for signal info to set initial scan interval */
+ struct wpa_signal_info siginfo;
+ if (wpa_drv_signal_poll(wpa_s, &siginfo) == 0 &&
+ siginfo.current_signal >= data->signal_threshold)
+ data->scan_interval = data->long_interval;
+ }
+ wpa_printf(MSG_DEBUG, "bgscan simple: Init scan interval: %d",
+ data->scan_interval);
eloop_register_timeout(data->scan_interval, 0, bgscan_simple_timeout,
data, NULL);
+
+ /*
+ * This function is called immediately after an association, so it is
+ * reasonable to assume that a scan was completed recently. This makes
+ * us skip an immediate new scan in cases where the current signal
+ * level is below the bgscan threshold.
+ */
+ os_get_reltime(&data->last_bgscan);
+
return data;
}
{
struct bgscan_simple_data *data = priv;
eloop_cancel_timeout(bgscan_simple_timeout, data, NULL);
+ if (data->signal_threshold)
+ wpa_drv_signal_monitor(data->wpa_s, 0, 0);
os_free(data);
}
-static int bgscan_simple_notify_scan(void *priv)
+static int bgscan_simple_notify_scan(void *priv,
+ struct wpa_scan_results *scan_res)
{
struct bgscan_simple_data *data = priv;
}
-static void bgscan_simple_notify_signal_change(void *priv)
+static void bgscan_simple_notify_signal_change(void *priv, int above,
+ int current_signal,
+ int current_noise,
+ int current_txrate)
{
- wpa_printf(MSG_DEBUG, "bgscan simple: signal level changed");
- /* TODO: if signal strength dropped enough, speed up background
- * scanning */
+ struct bgscan_simple_data *data = priv;
+ int scan = 0;
+ struct os_reltime now;
+
+ if (data->short_interval == data->long_interval ||
+ data->signal_threshold == 0)
+ return;
+
+ wpa_printf(MSG_DEBUG, "bgscan simple: signal level changed "
+ "(above=%d current_signal=%d current_noise=%d "
+ "current_txrate=%d))", above, current_signal,
+ current_noise, current_txrate);
+ if (data->scan_interval == data->long_interval && !above) {
+ wpa_printf(MSG_DEBUG, "bgscan simple: Start using short "
+ "bgscan interval");
+ data->scan_interval = data->short_interval;
+ os_get_reltime(&now);
+ if (now.sec > data->last_bgscan.sec + 1 &&
+ data->short_scan_count <= data->max_short_scans)
+ /*
+ * If we haven't just previously (<1 second ago)
+ * performed a scan, and we haven't depleted our
+ * budget for short-scans, perform a scan
+ * immediately.
+ */
+ scan = 1;
+ else if (data->last_bgscan.sec + data->long_interval >
+ now.sec + data->scan_interval) {
+ /*
+ * Restart scan interval timer if currently scheduled
+ * scan is too far in the future.
+ */
+ eloop_cancel_timeout(bgscan_simple_timeout, data,
+ NULL);
+ eloop_register_timeout(data->scan_interval, 0,
+ bgscan_simple_timeout, data,
+ NULL);
+ }
+ } else if (data->scan_interval == data->short_interval && above) {
+ wpa_printf(MSG_DEBUG, "bgscan simple: Start using long bgscan "
+ "interval");
+ data->scan_interval = data->long_interval;
+ eloop_cancel_timeout(bgscan_simple_timeout, data, NULL);
+ eloop_register_timeout(data->scan_interval, 0,
+ bgscan_simple_timeout, data, NULL);
+ } else if (!above) {
+ /*
+ * Signal dropped further 4 dB. Request a new scan if we have
+ * not yet scanned in a while.
+ */
+ os_get_reltime(&now);
+ if (now.sec > data->last_bgscan.sec + 10)
+ scan = 1;
+ }
+
+ if (scan) {
+ wpa_printf(MSG_DEBUG, "bgscan simple: Trigger immediate scan");
+ eloop_cancel_timeout(bgscan_simple_timeout, data, NULL);
+ eloop_register_timeout(0, 0, bgscan_simple_timeout, data,
+ NULL);
+ }
}
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