wpa_supplicant/bgscan_simple.c - vendor/opensource/hostap - Git at Google

 /*
  * WPA Supplicant - background scan and roaming module: simple
  * Copyright (c) 2009-2010, Jouni Malinen <j@w1.fi>
  *
  * This software may be distributed under the terms of the BSD license.
  * See README 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_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;
 };


 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 {
 		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;
 }


 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;
 	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;
 }


 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 wpa_scan_results *scan_res)
 {
 	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,
 					       int current_signal,
 					       int current_noise,
 					       int current_txrate)
 {
 	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);
 	}
 }


 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,
 };
	/*
	* WPA Supplicant - background scan and roaming module: simple
	* Copyright (c) 2009-2010, Jouni Malinen <j@w1.fi>
	*
	* This software may be distributed under the terms of the BSD license.
	* See README 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_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;
	};


	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 {
	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;
	}


	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;
	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;
	}


	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 wpa_scan_results *scan_res)
	{
	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,
	int current_signal,
	int current_noise,
	int current_txrate)
	{
	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);
	}
	}


	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,
	};