Add autoscan module named exponential

This module will compute the interval on a base exponential. Thus,
params to this module are following this format: <base>:<limit>

Signed-hostap: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>

wpa_supplicant/Android.mk

@@ -1304,6 +1304,12 @@ L_CFLAGS += -DCONFIG_BGSCAN
 OBJS += bgscan.c
 endif
 
+ifdef CONFIG_AUTOSCAN_EXPONENTIAL
+L_CFLAGS += -DCONFIG_AUTOSCAN_EXPONENTIAL
+OBJS += autoscan_exponential.c
+NEED_AUTOSCAN=y
+endif
+
 ifdef NEED_AUTOSCAN
 L_CFLAGS += -DCONFIG_AUTOSCAN
 OBJS += autoscan.c

wpa_supplicant/Makefile

@@ -1321,6 +1321,12 @@ CFLAGS += -DCONFIG_BGSCAN
 OBJS += bgscan.o
 endif
 
+ifdef CONFIG_AUTOSCAN_EXPONENTIAL
+CFLAGS += -DCONFIG_AUTOSCAN_EXPONENTIAL
+OBJS += autoscan_exponential.o
+NEED_AUTOSCAN=y
+endif
+
 ifdef NEED_AUTOSCAN
 CFLAGS += -DCONFIG_AUTOSCAN
 OBJS += autoscan.o

wpa_supplicant/autoscan.c

@@ -15,7 +15,14 @@
 #include "scan.h"
 #include "autoscan.h"
 
+#ifdef CONFIG_AUTOSCAN_EXPONENTIAL
+extern const struct autoscan_ops autoscan_exponential_ops;
+#endif /* CONFIG_AUTOSCAN_EXPONENTIAL */
+
 static const struct autoscan_ops * autoscan_modules[] = {
+#ifdef CONFIG_AUTOSCAN_EXPONENTIAL
+	&autoscan_exponential_ops,
+#endif /* CONFIG_AUTOSCAN_EXPONENTIAL */
 	NULL
 };
 

wpa_supplicant/autoscan_exponential.c

@@ -0,0 +1,101 @@
+/*
+ * WPA Supplicant - auto scan exponential module
+ * Copyright (c) 2012, Intel Corporation. All rights reserved.
+ *
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
+ */
+
+#include "includes.h"
+
+#include "common.h"
+#include "wpa_supplicant_i.h"
+#include "autoscan.h"
+
+struct autoscan_exponential_data {
+	struct wpa_supplicant *wpa_s;
+	int base;
+	int limit;
+	int interval;
+};
+
+
+static int
+autoscan_exponential_get_params(struct autoscan_exponential_data *data,
+				const char *params)
+{
+	const char *pos;
+
+	if (params == NULL)
+		return -1;
+
+	data->base = atoi(params);
+
+	pos = os_strchr(params, ':');
+	if (pos == NULL)
+		return -1;
+
+	pos++;
+	data->limit = atoi(pos);
+
+	return 0;
+}
+
+
+static void * autoscan_exponential_init(struct wpa_supplicant *wpa_s,
+					const char *params)
+{
+	struct autoscan_exponential_data *data;
+
+	data = os_zalloc(sizeof(struct autoscan_exponential_data));
+	if (data == NULL)
+		return NULL;
+
+	if (autoscan_exponential_get_params(data, params) < 0) {
+		os_free(data);
+		return NULL;
+	}
+
+	wpa_printf(MSG_DEBUG, "autoscan exponential: base exponential is %d "
+		   "and limit is %d", data->base, data->limit);
+
+	data->wpa_s = wpa_s;
+
+	return data;
+}
+
+
+static void autoscan_exponential_deinit(void *priv)
+{
+	struct autoscan_exponential_data *data = priv;
+
+	os_free(data);
+}
+
+
+static int autoscan_exponential_notify_scan(void *priv,
+					    struct wpa_scan_results *scan_res)
+{
+	struct autoscan_exponential_data *data = priv;
+
+	wpa_printf(MSG_DEBUG, "autoscan exponential: scan result "
+		   "notification");
+
+	if (data->interval >= data->limit)
+		return data->limit;
+
+	if (data->interval <= 0)
+		data->interval = data->base;
+
+	data->interval = data->interval * data->base;
+
+	return data->interval;
+}
+
+
+const struct autoscan_ops autoscan_exponential_ops = {
+	.name = "exponential",
+	.init = autoscan_exponential_init,
+	.deinit = autoscan_exponential_deinit,
+	.notify_scan = autoscan_exponential_notify_scan,
+};

wpa_supplicant/defconfig

@@ -504,4 +504,7 @@ CONFIG_PEERKEY=y
 # Autoscan
 # This can be used to enable automatic scan support in wpa_supplicant.
 # See wpa_supplicant.conf for more information on autoscan usage.
-#CONFIG_AUTOSCAN=y
+#
+# Enabling directly a module will enable autoscan support.
+# For exponential module:
+#CONFIG_AUTOSCAN_EXPONENTIAL=y

wpa_supplicant/wpa_supplicant.conf

@@ -230,6 +230,10 @@ fast_reauth=1
 # within an interface in following format:
 #autoscan=<autoscan module name>:<module parameters>
 # autoscan is like bgscan but on disconnected or inactive state.
+# For instance, on exponential module parameters would be <base>:<limit>
+#autoscan=exponential:3:300
+# Which means a delay between scans on a base exponential of 3,
+# up to the limit of 300 seconds (3, 9, 27 ... 300)
 
 # filter_ssids - SSID-based scan result filtering
 # 0 = do not filter scan results (default)