wpa-supplicant applicant: Scan Method

Posted on Edited on In Views:
记录wpa-supplicant applicant的扫描方法的调用。

实现

代码过程：

  • 注册信号回调函数
  • 创建gdbus连接
  • 创建gdbus事件循环
  • 获取wlan0的对象路径（这一步比较关键，后面Scan方法需要wlan0的对象路径作为参数传入）
  • 分别订阅ScanDone 信号、BSSAdded 信号、BSSRemoved 信号、PropertiesChanged 信号
  • 调用Scan方法
  • 启动gdbus事件循环
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/*
gcc src/main.c -o wpa-ctl \
	`pkg-config --cflags --libs gio-2.0`\
	`pkg-config --cflags --libs glib-2.0`\
	`pkg-config --cflags --libs dbus-1`
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <ctype.h>
#include <unistd.h>
#include <signal.h>
#include <pthread.h>

#include <glib.h>
#include <gio/gio.h>
#include <glib/gprintf.h>

GMainLoop *g_loop;
GDBusConnection *g_gdbus_con;

guint g_prop_changed;
guint g_scan_done;
guint g_bss_removed;
guint g_bss_added;

static void wpa_property_value(const gchar *key, GVariant *value)
{
	const gchar *type = g_variant_get_type_string(value);
	// g_printf("type: %s\n", type);
	g_printf("\t%s(%s) : ", key, type);
	switch(*type) 
	{
		case 'o': // object_path
			g_printf("%s\n", g_variant_get_string(value, NULL));
			break;
		case 's': // string
			g_printf("%s\n", g_variant_get_string(value, NULL));
			break;
		case 'b': // boolean
			g_printf("%s\n", g_variant_get_boolean(value)? "true":"false");
			break;
		case 'y':
			g_printf("%#x\n", g_variant_get_byte(value));
			break;
		case 'u': // uint32
			g_printf("%d\n", g_variant_get_uint32(value));
			break;
		case 'n': // int16
			g_printf("%hd\n", g_variant_get_int16(value));
			break;
		case 'q': // uint16
			g_printf("%u\n", g_variant_get_uint16(value));
			break;
		case 'i': // int32
			g_printf("%d\n", g_variant_get_int32(value));
			break;
		case 'a': // array,[]
		/* TODO Handling only 'as', but not array of dicts */
			if(!g_strcmp0(type, "as"))
			{
				g_printf("\n");
				gchar *uuid;
				GVariantIter i;
				g_variant_iter_init(&i, value);
				while(g_variant_iter_next(&i, "s", &uuid))
				{
					g_printf("\t\t%s\n", uuid);
					g_free(uuid);
				}
			}
			else if (!g_strcmp0(type, "ay"))
			{
				guint8 byte;
				GVariantIter i;
				g_variant_iter_init(&i, value);
				gsize size = g_variant_iter_n_children(&i);
				if (!g_strcmp0("SSID", key))
				{
					while(g_variant_iter_next(&i, "y", &byte))
						g_printf("%c", byte);
				}
				else if (!g_strcmp0("BSSID", key))
				{
					guint8 cnt = 0;
					while(g_variant_iter_next(&i, "y", &byte))
					{
						if (cnt == size -1)
							g_printf("%02X", byte);
						else
							g_printf("%02X-", byte);
						cnt++;
					}
				}
				else
				{
					while(g_variant_iter_next(&i, "y", &byte))
						g_printf("0x%x ", byte);
				}
				g_printf("\n");
			}
			else if (!g_strcmp0(type, "ao"))
			{
				g_printf("\n");
				gchar *opath;
				GVariantIter i;
				g_variant_iter_init(&i, value);
				while(g_variant_iter_next(&i, "o", &opath))
				{
					g_printf("\t\t%s\n", opath);
					g_free(opath);
				}
			}
			else if (!g_strcmp0(type, "au"))
			{
				guint32 rate = 0;
				GVariantIter i;
				g_variant_iter_init(&i, value);
				while(g_variant_iter_next(&i, "u", &rate))
					g_printf("%u ", rate);
				g_printf("\n");
			}
			else if (!g_strcmp0(type, "a{sv}"))
			{
				g_printf("\n");
				GVariantIter iter;
    			GVariant *prop_val;
				gchar *prop_name;
				g_variant_iter_init(&iter, value);
				while (g_variant_iter_next (&iter, "{sv}", &prop_name, &prop_val))
				{
					g_printf("\t\t%s: ", prop_name);
					if (g_variant_is_of_type(prop_val, G_VARIANT_TYPE_STRING))
					{
						g_printf("%s\n", g_variant_get_string(prop_val, NULL));
					}
					else if (g_variant_is_of_type(prop_val, G_VARIANT_TYPE_STRING_ARRAY))
					{
						gchar *str;
						GVariantIter i;
						g_variant_iter_init(&i, prop_val);
						while (g_variant_iter_next(&i, "s", &str))
						{
							g_printf("%s ", str);
							g_free(str);
						}
						g_printf("\n");
					}
					g_free(prop_name);
					g_variant_unref(prop_val);
				}
			}
			else
			{
				g_printf("\n");
			}
			break;
		default:
			g_printf("Other\n");
			break;
	}
}

static void wpa_signal_scan_done_cb(GDBusConnection *sig,
									const gchar *sender_name,
									const gchar *object_path,
									const gchar *interface,
									const gchar *signal_name,
									GVariant *parameters,
									gpointer user_data)
{
	// parameters data type: (b)
	(void)sig;
	(void)sender_name;
	(void)object_path;
	(void)interface;
	(void)signal_name;
	(void)user_data;

	const gchar *type = g_variant_get_type_string(parameters);
	g_printf("ScanDone signal data type: %s\n", type);
	g_printf("%s\n", g_variant_print(parameters, true));

	gboolean val;
	g_variant_get(parameters, "(b)", &val);
	g_printf("ScanDone: %s\n", val ? "true":"false");
	g_printf("\n");

	return;
}

static void wpa_signal_bss_added_cb(GDBusConnection *sig,
									const gchar *sender_name,
									const gchar *object_path,
									const gchar *interface,
									const gchar *signal_name,
									GVariant *parameters,
									gpointer user_data)
{
	// parameters data type: (oa{sv})
	(void)sig;
	(void)sender_name;
	(void)object_path;
	(void)interface;
	(void)signal_name;
	(void)user_data;

	GVariantIter *iter;
	const char *object;
	gchar *interface_name;
	GVariant *properties;

	const gchar *type = g_variant_get_type_string(parameters);
	g_printf("BssAdded data type: %s\n", type);
	g_printf("%s\n", g_variant_print(parameters, true));

	g_variant_get(parameters, "(oa{sv})", &object, &iter);
	g_printf("object_path: %s\n", object);
	while (g_variant_iter_next(iter, "{sv}", &interface_name, &properties))
	{
		wpa_property_value(interface_name, properties);
		g_free(interface_name);
		g_variant_unref(properties);
	}
	
	g_printf("\n");
	g_variant_iter_free(iter);

	return;
}

static void wpa_signal_bss_removed_cb(GDBusConnection *sig,
									const gchar *sender_name,
									const gchar *object_path,
									const gchar *interface,
									const gchar *signal_name,
									GVariant *parameters,
									gpointer user_data)
{
	// parameters data type: (o)
	(void)sig;
	(void)sender_name;
	(void)object_path;
	(void)interface;
	(void)signal_name;
	(void)user_data;

	const gchar *type = g_variant_get_type_string(parameters);
	g_printf("BssRemoved data type: %s\n", type);
	g_printf("%s\n", g_variant_print(parameters, true));

	const gchar *val = NULL;
	g_variant_get(parameters, "(o)", &val);
	g_printf("BssRemoved: %s\n", val);
	g_printf("\n");
	
	return;
}

static void wpa_signal_properties_changed_cb(GDBusConnection *sig,
									const gchar *sender_name,
									const gchar *object_path,
									const gchar *interface,
									const gchar *signal_name,
									GVariant *parameters,
									gpointer user_data)
{
	// parameters data type: (a{sv})
	(void)sig;
	(void)sender_name;
	(void)object_path;
	(void)interface;
	(void)signal_name;
	(void)user_data;

	GVariantIter *iter;
	gchar *property_name;
	GVariant *prop_val;

	const gchar *type = g_variant_get_type_string(parameters);
	g_printf("PropertiesChanged data type: %s\n", type);
	g_printf("%s\n", g_variant_print(parameters, true));
	
	g_variant_get(parameters, "(a{sv})", &iter);
	// while (g_variant_iter_loop(iter, "{sv}", &property_name, &prop_val))
	while (g_variant_iter_next(iter, "{sv}", &property_name, &prop_val))
	{
		wpa_property_value(property_name, prop_val);
		g_free(property_name);
		g_variant_unref(prop_val);
	}
	g_printf("\n");

	g_variant_iter_free(iter);
	return;
}

static void main_loop_stop(int sig)
{
	struct sigaction sigact = { .sa_handler = SIG_DFL };
	sigaction(sig, &sigact, NULL);
	g_main_loop_quit(g_loop);
}

int main(int argc, char *argv[])
{
	// 注册信号回调
	struct sigaction sigact = { .sa_handler = main_loop_stop };
	sigaction(SIGTERM, &sigact, NULL);
	sigaction(SIGINT, &sigact, NULL);

	// 创建gdbus连接
	g_gdbus_con = g_bus_get_sync(G_BUS_TYPE_SYSTEM, NULL, NULL);
	if(g_gdbus_con == NULL) 
	{
		g_printf("Not able to get connection to system bus\n");
		return 1;
	}

    // 创建主循环
	g_loop = g_main_loop_new(NULL, FALSE);

    // 同步调用，获取wlan0的对象路径
	GVariant *result;
	GError *error = NULL;
	result = g_dbus_connection_call_sync(
				g_gdbus_con,
				"fi.w1.wpa_supplicant1",
				"/fi/w1/wpa_supplicant1",
				"fi.w1.wpa_supplicant1",
				"GetInterface",
				g_variant_new("(s)", "wlan0"),
				G_VARIANT_TYPE("(o)"),
				G_DBUS_CALL_FLAGS_NONE,
				-1,
				NULL,
				&error);
	if (NULL != error)
	{
		g_printf("Error GetInterface: %s\n", error->message);
		g_error_free(error);
		goto fail;
	}
	// g_printf("%s\n", g_variant_print(result, true));

    // 解析object path
    const gchar *object_path = NULL;
    g_variant_get(result, "(o)", &object_path);
    g_variant_unref(result);
    if (object_path == NULL) 
    {
        g_print("Failed to parse object path from the result.\n");
        goto fail;
    }
    g_printf("Received object path from wlan0: %s\n\n", object_path);

	// 订阅 ScanDone 信号
	g_scan_done = g_dbus_connection_signal_subscribe(
						g_gdbus_con, 						// connection
						"fi.w1.wpa_supplicant1", 			// sender
						"fi.w1.wpa_supplicant1.Interface",  // interface_name
						"ScanDone",							// member：method or signal
						object_path, 								// object path
						NULL, 								// arg0
						G_DBUS_SIGNAL_FLAGS_NONE, 			// flags
						wpa_signal_scan_done_cb, 			// callback
						NULL, 								// user_data
						NULL);
	// 订阅 BSSAdded 信号
	g_bss_added = g_dbus_connection_signal_subscribe(
						g_gdbus_con,
						"fi.w1.wpa_supplicant1",
						"fi.w1.wpa_supplicant1.Interface",
						"BSSAdded",
						object_path,
						NULL,
						G_DBUS_SIGNAL_FLAGS_NONE,
						wpa_signal_bss_added_cb,
						NULL,
						NULL);
	// 订阅 BSSRemoved 信号
	g_bss_removed = g_dbus_connection_signal_subscribe(
						g_gdbus_con,
						"fi.w1.wpa_supplicant1",
						"fi.w1.wpa_supplicant1.Interface",
						"BSSRemoved",
						object_path,
						NULL,
						G_DBUS_SIGNAL_FLAGS_NONE,
						wpa_signal_bss_removed_cb,
						NULL,
						NULL);
	// 订阅 PropertiesChanged 信号
	g_prop_changed = g_dbus_connection_signal_subscribe(
						g_gdbus_con,
						"fi.w1.wpa_supplicant1",
						"fi.w1.wpa_supplicant1.Interface",
						"PropertiesChanged",
						object_path,
						NULL,
						G_DBUS_SIGNAL_FLAGS_NONE,
						wpa_signal_properties_changed_cb,
						NULL,
						NULL);

	/* 扫描 */ 
	GVariantBuilder *builder = g_variant_builder_new(G_VARIANT_TYPE("a{sv}"));
	g_variant_builder_add(builder, "{sv}", "Type", g_variant_new_string("active"));
	GVariant *variant = g_variant_builder_end(builder);
	g_variant_builder_unref(builder);

	g_dbus_connection_call(g_gdbus_con,
				"fi.w1.wpa_supplicant1",
				object_path,
				"fi.w1.wpa_supplicant1.Interface",
				"Scan",
				g_variant_new_tuple(&variant, 1),
				NULL,
				G_DBUS_CALL_FLAGS_NONE,
				-1,
				NULL,
				NULL,
				NULL);
	

fail:
    g_main_loop_run(g_loop);

	// 释放gdbus连接
	g_object_unref(g_gdbus_con);
	printf("@@@@@@ App Stop @@@@@@");

    return 0;
}

难点

难点1：

这里实现过程的逻辑参考了wpa_supplicant dbus api example using python ，通过python编程实现。

难点2：

订阅各种信号的返回值类型以及如何对它进行解析也是一个问题。这需要参考官方文档：wpa_supplicant 官方dbus接口文档 ，为了方便查询，我把它转换成了表格形式，具体查看这篇文章 {% post_link wpa-supplicant application %}

这里对各种信号原始数据进行记录：

主要涉及各种信号：ScanDone、BSSAdded、BssRemoved、PropertiesChanged

ScanDone

data type: (b)

1
(true,)

BSSAdded

data type: (oa{sv}) 

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(
    objectpath '/fi/w1/wpa_supplicant1/Interfaces/0/BSSs/257', 
    {
        'SSID': <[byte 0x43, 0x6f, 0x6f, 0x6c, 0x4b, 0x69, 0x74, 0x5f, 0x35, 0x47]>, 
        'BSSID': <[byte 0x60, 0xdb, 0x15, 0xfa, 0x8b, 0x05]>, 
        'Privacy': <true>, 
        'Mode': <'infrastructure'>, 
        'Signal': <int16 -70>, 
        'Frequency': <uint16 5805>,
        'Rates': <[uint32 54000000, 48000000, 36000000, 24000000, 18000000, 12000000, 9000000, 6000000]>, 
        'WPA': <{
            'KeyMgmt': <['wpa-psk']>, 
            'Group': <'tkip'>, 
            'Pairwise': <['tkip', 'ccmp']>
         }>, 
        'RSN': <{
            'KeyMgmt': <['wpa-psk']>, 
            'Group': <'tkip'>, 
            'Pairwise': <['tkip', 'ccmp']>, 
            'MgmtGroup': <'aes128cmac'>
        }>, 
        'WPS': <@a{sv} {}>, 
        'IEs': <[byte 0x00, 0x0a, 0x43, 0x6f, 0x6f, 0x6c, 0x4b, 0x69, 0x74, 0x5f, 0x35, 0x47, 0x01, 0x08, 0x8c, 0x12, 0x98, 0x24, 0xb0, 0x48, 0x60, 0x6c, 0x03, 0x01, 0xa1, 0xdd, 0x1a, 0x00, 0x50, 0xf2, 0x01, 0x01, 0x00, 0x00, 0x50, 0xf2, 0x02, 0x02, 0x00, 0x00, 0x50, 0xf2, 0x02, 0x00, 0x50, 0xf2, 0x04, 0x01, 0x00, 0x00, 0x50, 0xf2, 0x02, 0x30, 0x18, 0x01, 0x00, 0x00, 0x0f, 0xac, 0x02, 0x02, 0x00, 0x00, 0x0f, 0xac, 0x02, 0x00, 0x0f, 0xac, 0x04, 0x01, 0x00, 0x00, 0x0f, 0xac, 0x02, 0x00, 0x00, 0x2d, 0x1a, 0xef, 0x09, 0x17, 0xff, 0xff, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x18, 0x04, 0x87, 0x09, 0x00, 0x3d, 0x16, 0xa1, 0x07, 0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x7f, 0x08, 0x00, 0x00, 0x08, 0x80, 0x00, 0x00, 0x00, 0x40, 0x0b, 0x05, 0x0f, 0x00, 0xca, 0x12, 0x7a, 0xdd, 0x18, 0x00, 0x50, 0xf2, 0x02, 0x01, 0x01, 0x00, 0x00, 0x03, 0xa4, 0x00, 0x00, 0x27, 0xa4, 0x00, 0x00, 0x42, 0x43, 0x5e, 0x00, 0x62, 0x32, 0x2f, 0x00, 0x20, 0x01, 0x00, 0x23, 0x02, 0x3f, 0x00, 0xc3, 0x04, 0x02, 0x2f, 0x2f, 0x2f, 0x07, 0x0a, 0x43, 0x4e, 0x04, 0x24, 0x08, 0x1e, 0x95, 0x05, 0x1e, 0x00, 0xbf, 0x0c, 0xb1, 0x79, 0xc9, 0x33, 0xfa, 0xff, 0x0c, 0x03, 0xfa, 0xff, 0x0c, 0x03, 0xc0, 0x05, 0x01, 0x9b, 0x00, 0xfc, 0xff, 0xff, 0x1c, 0x23, 0x01, 0x00, 0x08, 0x1a, 0x44, 0x10, 0x04, 0x20, 0x0e, 0x92, 0x6f, 0x09, 0x8f, 0x08, 0x00, 0x00, 0x00, 0xfa, 0xff, 0xfa, 0xff, 0x39, 0x1c, 0xc7, 0x71, 0x1c, 0x07, 0xff, 0x07, 0x24, 0xf4, 0x3f, 0x00, 0x26, 0xfc, 0xff, 0xff, 0x02, 0x27, 0x03, 0xff, 0x0e, 0x26, 0x00, 0x00, 0xff, 0x00, 0x20, 0xff, 0x00, 0x40, 0xff, 0x00, 0x60, 0xff, 0x00, 0xdd, 0x07, 0x00, 0x0c, 0x43, 0x00, 0x00, 0x00, 0x00, 0xdd, 0x21, 0x00, 0x0c, 0xe7, 0x00, 0x00, 0x00, 0x00, 0xbf, 0x0c, 0xb1, 0x01, 0xc0, 0x33, 0x2a, 0xff, 0x92, 0x04, 0x2a, 0xff, 0x92, 0x04, 0xc0, 0x05, 0x00, 0x00, 0x00, 0x2a, 0xff, 0xc3, 0x03, 0x01, 0x02, 0x02, 0xf0, 0x02, 0x00, 0x00]>, 
        'Age': <uint32 0>
    }
)

BSSRemoved

data type: (o)

1
(objectpath '/fi/w1/wpa_supplicant1/Interfaces/0/BSSs/519',)

PropertiesChanged

data type: (a{sv})

数据1：

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(
    {
        'Scanning': <false>, 
        'BSSs': <[objectpath 
            '/fi/w1/wpa_supplicant1/Interfaces/0/BSSs/2', 
            '/fi/w1/wpa_supplicant1/Interfaces/0/BSSs/423', 
            '/fi/w1/wpa_supplicant1/Interfaces/0/BSSs/424', 
            '/fi/w1/wpa_supplicant1/Interfaces/0/BSSs/425', 
            '/fi/w1/wpa_supplicant1/Interfaces/0/BSSs/426']>
    },
)

数据2：

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(
    {
        'BSSs': <[objectpath 
            '/fi/w1/wpa_supplicant1/Interfaces/0/BSSs/2', 
            '/fi/w1/wpa_supplicant1/Interfaces/0/BSSs/1363', 
            '/fi/w1/wpa_supplicant1/Interfaces/0/BSSs/1364', 
            '/fi/w1/wpa_supplicant1/Interfaces/0/BSSs/1365', 
            '/fi/w1/wpa_supplicant1/Interfaces/0/BSSs/1366', 
            '/fi/w1/wpa_supplicant1/Interfaces/0/BSSs/1367', 
            '/fi/w1/wpa_supplicant1/Interfaces/0/BSSs/1369', 
            '/fi/w1/wpa_supplicant1/Interfaces/0/BSSs/1372', 
            '/fi/w1/wpa_supplicant1/Interfaces/0/BSSs/1374', 
            '/fi/w1/wpa_supplicant1/Interfaces/0/BSSs/1375', 
            '/fi/w1/wpa_supplicant1/Interfaces/0/BSSs/1376', 
            '/fi/w1/wpa_supplicant1/Interfaces/0/BSSs/1377', 
            '/fi/w1/wpa_supplicant1/Interfaces/0/BSSs/1378']>
	},
)