hostap/wpa_supplicant/bgscan_simple.c
Jouni Malinen e2f74005f5 bgscan: Add signal strength change events
This allows bgscan modules to use more information to decide on when
to perform background scans. bgscan_simple can now change between
short and long background scan intervals based on signal strength
and in addition, it can trigger immediate scans when the signal
strength is detected to be dropping.

bgscan_simple takes following parameters now:
short interval:signal strength threshold:long interval
For example:
	bgscan="simple:30:-45:300"
2010-03-28 15:32:34 -07:00

219 lines
6 KiB
C

/*
* WPA Supplicant - background scan and roaming module: simple
* 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.
*/
#include "includes.h"
#include "common.h"
#include "eloop.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 bgscan_simple_data {
struct wpa_supplicant *wpa_s;
const struct wpa_ssid *ssid;
int scan_interval;
int signal_threshold;
int short_interval; /* use if signal < threshold */
int long_interval; /* use if signal > threshold */
struct os_time last_bgscan;
};
static void bgscan_simple_timeout(void *eloop_ctx, void *timeout_ctx)
{
struct bgscan_simple_data *data = eloop_ctx;
struct wpa_supplicant *wpa_s = data->wpa_s;
struct wpa_driver_scan_params params;
os_memset(&params, 0, sizeof(params));
params.num_ssids = 1;
params.ssids[0].ssid = data->ssid->ssid;
params.ssids[0].ssid_len = data->ssid->ssid_len;
params.freqs = data->ssid->scan_freq;
/*
* A more advanced bgscan module would learn about most like channels
* over time and request scans only for some channels (probing others
* every now and then) to reduce effect on the data connection.
*/
wpa_printf(MSG_DEBUG, "bgscan simple: Request a background scan");
if (wpa_supplicant_trigger_scan(wpa_s, &params)) {
wpa_printf(MSG_DEBUG, "bgscan simple: Failed to trigger scan");
eloop_register_timeout(data->scan_interval, 0,
bgscan_simple_timeout, data, NULL);
} else
os_get_time(&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;
}
static void * bgscan_simple_init(struct wpa_supplicant *wpa_s,
const char *params,
const struct wpa_ssid *ssid)
{
struct bgscan_simple_data *data;
data = os_zalloc(sizeof(*data));
if (data == NULL)
return NULL;
data->wpa_s = wpa_s;
data->ssid = ssid;
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;
eloop_register_timeout(data->scan_interval, 0, bgscan_simple_timeout,
data, NULL);
return data;
}
static void bgscan_simple_deinit(void *priv)
{
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)
{
struct bgscan_simple_data *data = priv;
wpa_printf(MSG_DEBUG, "bgscan simple: scan result notification");
eloop_cancel_timeout(bgscan_simple_timeout, data, NULL);
eloop_register_timeout(data->scan_interval, 0, bgscan_simple_timeout,
data, NULL);
/*
* A more advanced bgscan could process scan results internally, select
* the BSS and request roam if needed. This sample uses the existing
* BSS/ESS selection routine. Change this to return 1 if selection is
* done inside the bgscan module.
*/
return 0;
}
static void bgscan_simple_notify_beacon_loss(void *priv)
{
wpa_printf(MSG_DEBUG, "bgscan simple: beacon loss");
/* TODO: speed up background scanning */
}
static void bgscan_simple_notify_signal_change(void *priv, int above)
{
struct bgscan_simple_data *data = priv;
if (data->short_interval == data->long_interval ||
data->signal_threshold == 0)
return;
wpa_printf(MSG_DEBUG, "bgscan simple: signal level changed "
"(above=%d)", above);
if (data->scan_interval == data->long_interval && !above) {
wpa_printf(MSG_DEBUG, "bgscan simple: Trigger immediate scan "
"and start using short bgscan interval");
data->scan_interval = data->short_interval;
eloop_cancel_timeout(bgscan_simple_timeout, data, NULL);
eloop_register_timeout(0, 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) {
struct os_time now;
/*
* Signal dropped further 4 dB. Request a new scan if we have
* not yet scanned in a while.
*/
os_get_time(&now);
if (now.sec > data->last_bgscan.sec + 10) {
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);
}
}
}
const struct bgscan_ops bgscan_simple_ops = {
.name = "simple",
.init = bgscan_simple_init,
.deinit = bgscan_simple_deinit,
.notify_scan = bgscan_simple_notify_scan,
.notify_beacon_loss = bgscan_simple_notify_beacon_loss,
.notify_signal_change = bgscan_simple_notify_signal_change,
};