Linux下,使用C语言开发一个简单的GATT Server,我的Ubuntu上跑的BlueZ版本是5.79,使用的GLib库版本是2.85.2,这里我直接使用GLib里的D‑Bus来实现与BlueZ通信。BlueZ 官方推荐通过 D-Bus 进行通信和控制,如果是要使用原始的hci接口来实现,可以参考BlueZ源码目录下的
tools/btgatt-server.c 文件。
我这里是使用的usb蓝牙,支持经典蓝牙和BLE(低功耗蓝牙)模式,我直接通过bluez工具来开启BLE功能和BLE广播,常用的一些控制命令如下,做下记录:
### 经典蓝牙 ###bluetoothctl # 运行 bluetoothctl
power on # 打开蓝牙适配器(开启蓝牙功能)
agent on # 启用配对助手(允许输入或确认配对码等操作)
scan on # 开始扫描附近的蓝牙设备
scan off # 停止扫描
pair 94:87:E0:8C:D5:94 # 与指定MAC地址的设备进行配对
connect 94:87:E0:8C:D5:94 # 连接到已配对的指定设备
trust 94:87:E0:8C:D5:94 # 设置信任该设备(以后自动连接无需确认)sudo systemctl restart bluetooth # 重启蓝牙服务
remove 94:87:E0:8C:D5:94 # 清除旧配对信息### BLE ###通过 bluetoothctl 控制bluetoothctl power on # 开启蓝牙适配器
bluetoothctl discoverable on # 让本设备对其他设备可见
bluetoothctl pairable on # 允许其他设备与本设备配对
bluetoothctl advertise on # 开启BLE广播(让本设备可以被BLE客户端发现)通过 btmgmt 控制sudo btmgmt power on # 开启蓝牙
sudo btmgmt le on # 开启BLE(低功耗蓝牙)功能
sudo btmgmt advertising on # 开启BLE广播
sudo btmgmt connectable on # 允许连接
sudo btmgmt info # 查看适配器支持和当前状态
源码如下 gatt-server.c:
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>
#include <locale.h>#include "gio/gio.h"// ================== 蓝牙 GATT 应用的一些常量定义 ==================
#define BLUEZ_BUS_NAME "org.bluez" // BlueZ 的 DBus 服务名
#define ADAPTER_PATH "/org/bluez/hci0" // 默认蓝牙适配器路径(hci0)
#define APP_PATH "/org/example" // 应用根路径
#define SERVICE_PATH APP_PATH "/service0" // 自定义 GATT 服务路径
#define CHAR_READ_PATH SERVICE_PATH "/char0" // 自定义 "只读" 特征路径
#define CHAR_WRITE_PATH SERVICE_PATH "/char1" // 自定义 "可写" 特征路径// UUID 定义(随便写的示例 UUID)
static const gchar *SERVICE_UUID = "12345678-1234-5678-1234-56789abcdef0";
static const gchar *CHAR_READ_UUID = "12345678-1234-5678-1234-56789abcdef1";
static const gchar *CHAR_WRITE_UUID = "12345678-1234-5678-1234-56789abcdef2";// 特征的访问权限标志
static const gchar *flags_read[] = {"read", NULL};
static const gchar *flags_write[] = {"write", NULL};// ================== Introspection XML 定义 ==================
// 这些 XML 定义了 DBus 接口(ObjectManager、Service、Characteristic)// ObjectManager 接口(用于告诉 BlueZ 我们有哪些对象)
static const gchar *object_manager_xml ="<node>"" <interface name='org.freedesktop.DBus.ObjectManager'>"" <method name='GetManagedObjects'>"" <arg name='objects' type='a{oa{sa{sv}}}' direction='out'/>"" </method>"" </interface>""</node>";// GATT Service 接口
static const gchar *service_xml ="<node>"" <interface name='org.bluez.GattService1'>"" <property name='UUID' type='s' access='read'/>"" <property name='Primary' type='b' access='read'/>"" </interface>""</node>";// GATT Characteristic 接口(包含读写方法)
static const gchar *char_xml ="<node>"" <interface name='org.bluez.GattCharacteristic1'>"" <property name='UUID' type='s' access='read'/>"" <property name='Service' type='o' access='read'/>"" <property name='Flags' type='as' access='read'/>"" <method name='ReadValue'>"" <arg name='options' type='a{sv}' direction='in'/>"" <arg name='value' type='ay' direction='out'/>"" </method>"" <method name='WriteValue'>"" <arg name='value' type='ay' direction='in'/>"" <arg name='options' type='a{sv}' direction='in'/>"" </method>"" </interface>""</node>";// ================== 全局只读特征的内容 ==================
#define READ_VALUE_MAX_LEN 256
static guint8 read_value_buffer[READ_VALUE_MAX_LEN] = "Hello"; // 初始内容
static gsize read_value_len = 5; // 当前长度
static pthread_mutex_t read_value_mutex = PTHREAD_MUTEX_INITIALIZER;// 一个线程,用来从终端输入更新 "只读特征" 的内容
void *stdin_input_thread(void *arg)
{char input[READ_VALUE_MAX_LEN];while (1){printf("请输入新的只读特征内容(按回车确认):\n");if (fgets(input, sizeof(input), stdin)){size_t len = strlen(input);if (len > 0 && input[len - 1] == '\n')input[len - 1] = '\0'; // 去掉换行pthread_mutex_lock(&read_value_mutex);read_value_len = strlen(input);if (read_value_len > READ_VALUE_MAX_LEN)read_value_len = READ_VALUE_MAX_LEN;memcpy(read_value_buffer, input, read_value_len);pthread_mutex_unlock(&read_value_mutex);printf("已更新只读特征内容:%s\n", input);}}return NULL;
}// ================== DBus 方法调用处理 ==================
static void on_method_call(GDBusConnection *conn,const gchar *sender,const gchar *object_path,const gchar *interface_name,const gchar *method_name,GVariant *parameters,GDBusMethodInvocation *invocation,gpointer user_data)
{// 打印调试信息g_print("\n*** METHOD CALL RECEIVED ***\n");g_print("Sender: %s\n", sender);g_print("Object Path: %s\n", object_path);g_print("Interface: %s\n", interface_name);g_print("Method: %s\n", method_name);g_print("*****************************\n");// ============= 处理 GetManagedObjects(告诉 BlueZ 我们有哪些对象)=============if (g_strcmp0(interface_name, "org.freedesktop.DBus.ObjectManager") == 0 &&g_strcmp0(method_name, "GetManagedObjects") == 0){g_print("*** HANDLING GetManagedObjects ***\n");GVariantBuilder objects_builder;g_variant_builder_init(&objects_builder, G_VARIANT_TYPE("a{oa{sa{sv}}}"));// 添加 GATT Service 对象{GVariantBuilder service_props;g_variant_builder_init(&service_props, G_VARIANT_TYPE("a{sv}"));g_variant_builder_add(&service_props, "{sv}", "UUID", g_variant_new_string(SERVICE_UUID));g_variant_builder_add(&service_props, "{sv}", "Primary", g_variant_new_boolean(TRUE));GVariantBuilder service_interfaces;g_variant_builder_init(&service_interfaces, G_VARIANT_TYPE("a{sa{sv}}"));g_variant_builder_add(&service_interfaces, "{s@a{sv}}", "org.bluez.GattService1",g_variant_builder_end(&service_props));g_variant_builder_add(&objects_builder, "{o@a{sa{sv}}}", SERVICE_PATH,g_variant_builder_end(&service_interfaces));}// 添加 "只读特征" 对象{GVariantBuilder char_read_props;g_variant_builder_init(&char_read_props, G_VARIANT_TYPE("a{sv}"));g_variant_builder_add(&char_read_props, "{sv}", "UUID", g_variant_new_string(CHAR_READ_UUID));g_variant_builder_add(&char_read_props, "{sv}", "Service", g_variant_new_object_path(SERVICE_PATH));g_variant_builder_add(&char_read_props, "{sv}", "Flags", g_variant_new_strv(flags_read, -1));GVariantBuilder char_read_interfaces;g_variant_builder_init(&char_read_interfaces, G_VARIANT_TYPE("a{sa{sv}}"));g_variant_builder_add(&char_read_interfaces, "{s@a{sv}}", "org.bluez.GattCharacteristic1",g_variant_builder_end(&char_read_props));g_variant_builder_add(&objects_builder, "{o@a{sa{sv}}}", CHAR_READ_PATH,g_variant_builder_end(&char_read_interfaces));}// 添加 "可写特征" 对象{GVariantBuilder char_write_props;g_variant_builder_init(&char_write_props, G_VARIANT_TYPE("a{sv}"));g_variant_builder_add(&char_write_props, "{sv}", "UUID", g_variant_new_string(CHAR_WRITE_UUID));g_variant_builder_add(&char_write_props, "{sv}", "Service", g_variant_new_object_path(SERVICE_PATH));g_variant_builder_add(&char_write_props, "{sv}", "Flags", g_variant_new_strv(flags_write, -1));GVariantBuilder char_write_interfaces;g_variant_builder_init(&char_write_interfaces, G_VARIANT_TYPE("a{sa{sv}}"));g_variant_builder_add(&char_write_interfaces, "{s@a{sv}}", "org.bluez.GattCharacteristic1",g_variant_builder_end(&char_write_props));g_variant_builder_add(&objects_builder, "{o@a{sa{sv}}}", CHAR_WRITE_PATH,g_variant_builder_end(&char_write_interfaces));}// 返回对象列表GVariant *result = g_variant_new("(@a{oa{sa{sv}}})", g_variant_builder_end(&objects_builder));g_dbus_method_invocation_return_value(invocation, result);g_print("*** GetManagedObjects completed ***\n");return;}// ============= 处理 ReadValue 请求(读取只读特征的值)=============if (g_strcmp0(interface_name, "org.bluez.GattCharacteristic1") == 0 &&g_strcmp0(method_name, "ReadValue") == 0){g_print("ReadValue called on %s\n", object_path);GVariant *value;pthread_mutex_lock(&read_value_mutex);value = g_variant_new_fixed_array(G_VARIANT_TYPE_BYTE,read_value_buffer, read_value_len, sizeof(guint8));pthread_mutex_unlock(&read_value_mutex);g_dbus_method_invocation_return_value(invocation, g_variant_new("(@ay)", value));return;}// ============= 处理 WriteValue 请求(写入数据到可写特征)=============if (g_strcmp0(interface_name, "org.bluez.GattCharacteristic1") == 0 &&g_strcmp0(method_name, "WriteValue") == 0){GVariant *value_variant;GVariant *options_variant;g_variant_get(parameters, "(@ay@a{sv})", &value_variant, &options_variant);gsize len;const guint8 *data = g_variant_get_fixed_array(value_variant, &len, sizeof(guint8));g_print("WriteValue called on %s, data: ", object_path);for (gsize i = 0; i < len; i++){g_print("%02X ", data[i]);}g_print(" string: %.*s\n", (int)len, (const char *)data);g_variant_unref(value_variant);g_variant_unref(options_variant);g_dbus_method_invocation_return_value(invocation, NULL);return;}// 未知方法g_dbus_method_invocation_return_error(invocation, G_DBUS_ERROR,G_DBUS_ERROR_UNKNOWN_METHOD,"Unknown method: %s", method_name);
}// ================== 属性读取处理 ==================
static GVariant *on_get_property(GDBusConnection *conn,const gchar *sender,const gchar *object_path,const gchar *interface_name,const gchar *property_name,GError **error,gpointer user_data)
{g_print("Get property: %s.%s on %s\n", interface_name, property_name, object_path);// 处理 Service 属性if (g_strcmp0(interface_name, "org.bluez.GattService1") == 0){if (g_strcmp0(property_name, "UUID") == 0)return g_variant_new_string(SERVICE_UUID);if (g_strcmp0(property_name, "Primary") == 0)return g_variant_new_boolean(TRUE);}// 处理 Characteristic 属性if (g_strcmp0(interface_name, "org.bluez.GattCharacteristic1") == 0){if (g_strcmp0(object_path, CHAR_READ_PATH) == 0){if (g_strcmp0(property_name, "UUID") == 0)return g_variant_new_string(CHAR_READ_UUID);if (g_strcmp0(property_name, "Service") == 0)return g_variant_new_object_path(SERVICE_PATH);if (g_strcmp0(property_name, "Flags") == 0)return g_variant_new_strv(flags_read, -1);}if (g_strcmp0(object_path, CHAR_WRITE_PATH) == 0){if (g_strcmp0(property_name, "UUID") == 0)return g_variant_new_string(CHAR_WRITE_UUID);if (g_strcmp0(property_name, "Service") == 0)return g_variant_new_object_path(SERVICE_PATH);if (g_strcmp0(property_name, "Flags") == 0)return g_variant_new_strv(flags_write, -1);}}// 未知属性g_set_error(error, G_DBUS_ERROR, G_DBUS_ERROR_UNKNOWN_PROPERTY,"Unknown property: %s", property_name);return NULL;
}// ================== 注册回调 ==================
static GMainLoop *main_loop = NULL;
static gboolean registration_success = FALSE;static void on_register_application_done(GObject *source_object,GAsyncResult *res,gpointer user_data)
{GError *error = NULL;GVariant *result = g_dbus_proxy_call_finish(G_DBUS_PROXY(source_object), res, &error);if (result){g_print("SUCCESS: GATT Application registered!\n");g_variant_unref(result);registration_success = TRUE;}else{g_printerr("RegisterApplication failed: %s\n", error->message);g_error_free(error);registration_success = FALSE;}
}// ================== 主函数 ==================
int main(int argc, char *argv[])
{GError *error = NULL;// 设置本地化环境,不然 g_print 输出中文时乱码setlocale(LC_ALL, "");g_print("Connecting to system bus...\n");// 连接到系统总线GDBusConnection *connection = g_bus_get_sync(G_BUS_TYPE_SYSTEM, NULL, &error);if (!connection){g_printerr("Failed to connect to system bus: %s\n", error->message);return 1;}g_print("Parsing introspection XML...\n");GDBusNodeInfo *object_manager_info = g_dbus_node_info_new_for_xml(object_manager_xml, NULL);GDBusNodeInfo *service_info = g_dbus_node_info_new_for_xml(service_xml, NULL);GDBusNodeInfo *char_info = g_dbus_node_info_new_for_xml(char_xml, NULL);// 定义虚表(方法回调 + 属性回调)static const GDBusInterfaceVTable interface_vtable = {.method_call = on_method_call,.get_property = on_get_property,.set_property = NULL};// 注册 ObjectManagerg_print("Registering ObjectManager at %s\n", APP_PATH);guint reg_id1 = g_dbus_connection_register_object(connection, APP_PATH,object_manager_info->interfaces[0],&interface_vtable, NULL, NULL, &error);if (!reg_id1){g_printerr("Failed to register ObjectManager: %s\n", error->message);return 1;}// 注册 Serviceg_print("Registering Service at %s\n", SERVICE_PATH);guint reg_id2 = g_dbus_connection_register_object(connection, SERVICE_PATH,service_info->interfaces[0],&interface_vtable, NULL, NULL, &error);if (!reg_id2){g_printerr("Failed to register Service: %s\n", error->message);return 1;}// 注册 Read Characteristicg_print("Registering Read Characteristic at %s\n", CHAR_READ_PATH);guint reg_id3 = g_dbus_connection_register_object(connection, CHAR_READ_PATH,char_info->interfaces[0],&interface_vtable, NULL, NULL, &error);if (!reg_id3){g_printerr("Failed to register Read Characteristic: %s\n", error->message);return 1;}// 注册 Write Characteristicg_print("Registering Write Characteristic at %s\n", CHAR_WRITE_PATH);guint reg_id4 = g_dbus_connection_register_object(connection, CHAR_WRITE_PATH,char_info->interfaces[0],&interface_vtable, NULL, NULL, &error);if (!reg_id4){g_printerr("Failed to register Write Characteristic: %s\n", error->message);return 1;}// 创建 GATT Manager 的代理GDBusProxy *manager_proxy = g_dbus_proxy_new_sync(connection,G_DBUS_PROXY_FLAGS_NONE,NULL,BLUEZ_BUS_NAME,ADAPTER_PATH,"org.bluez.GattManager1",NULL,&error);if (!manager_proxy){g_printerr("Failed to create GattManager1 proxy: %s\n", error->message);return 1;}g_print("Attempting to register GATT application...\n");// 启动输入线程(用于动态修改只读特征内容)pthread_t tid;pthread_create(&tid, NULL, stdin_input_thread, NULL);// 创建主循环main_loop = g_main_loop_new(NULL, FALSE);// 异步调用 RegisterApplicationg_dbus_proxy_call(manager_proxy, "RegisterApplication",g_variant_new("(oa{sv})", APP_PATH, NULL),G_DBUS_CALL_FLAGS_NONE,-1,NULL,on_register_application_done,NULL);// 运行主循环(等待 DBus 事件)g_main_loop_run(main_loop);// 程序退出时的清理g_object_unref(manager_proxy);g_dbus_connection_unregister_object(connection, reg_id1);g_dbus_connection_unregister_object(connection, reg_id2);g_dbus_connection_unregister_object(connection, reg_id3);g_dbus_connection_unregister_object(connection, reg_id4);g_object_unref(connection);g_print("Program finished.\n");return registration_success ? 0 : 1;
}