hostapd/wpa_supplicant/bgscan_simple.c

/*
 * WPA Supplicant - background scan and roaming module: simple
 * Copyright (c) 2009, 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 "bgscan.h"

struct bgscan_simple_data {
	struct wpa_supplicant *wpa_s;
	const struct wpa_ssid *ssid;
	int scan_interval;
};


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);
	}
}


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 (params)
		data->scan_interval = atoi(params);
	if (data->scan_interval <= 0)
		data->scan_interval = 30;
	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);
	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)
{
	wpa_printf(MSG_DEBUG, "bgscan simple: signal level changed");
	/* TODO: if signal strength dropped enough, speed up background
	 * scanning */
}


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,
};