lib: Create API for GATT characteristic notifications

2 files changed, 141 insertions, 2 deletions

diff --git a/lib/ble.c b/lib/ble.c
index 369047c..5e71355 100644
--- a/lib/ble.c
+++ b/lib/ble.c
@@ -695,6 +695,82 @@ int ble_gatt_write_req_desc(int conn_id, int desc_id, int auth,
     return ble_gatt_op(6, conn_id, desc_id, auth, value, len);
 }
 
+/* Called when the registration for notifications on a char finishes */
+static void register_for_notification_cb(int conn_id, int registered,
+                                         int status,
+                                         btgatt_srvc_id_t *srvc_id,
+                                         btgatt_char_id_t *char_id) {
+    int id = 0;
+
+    if (data.cbs.char_notification_register_cb)
+        data.cbs.char_notification_register_cb(conn_id, id, registered, status);
+}
+
+/* Called when notifications of a characteristic are received */
+void notify_cb(int conn_id, btgatt_notify_params_t *p_data) {
+    int id = 0;
+
+    if (data.cbs.char_notification_cb)
+        data.cbs.char_notification_cb(conn_id, id, p_data->value, p_data->len,
+                                      !p_data->is_notify);
+}
+
+static int ble_gatt_char_notification(uint8_t operation, int conn_id,
+                                      int char_id) {
+    ble_device_t *dev;
+    bt_status_t s = BT_STATUS_UNSUPPORTED;
+    btgatt_srvc_id_t *srvc;
+    btgatt_char_id_t *ch;
+
+    if (char_id < 0)
+        return -1;
+
+    if (!data.client)
+        return -1;
+
+    if (!data.gattiface)
+        return -1;
+
+    if (!data.adapter_state)
+        return -1;
+
+    dev = find_device_by_conn_id(conn_id);
+    if (!dev)
+        return -1;
+
+    if (dev->char_count <= 0 || char_id >= dev->char_count)
+        return -1;
+
+    srvc = &dev->chars[char_id].s;
+    ch = &dev->chars[char_id].c;
+
+    switch (operation) {
+        case 0:
+            s = data.gattiface->client->register_for_notification(data.client,
+                                                                  &dev->bda,
+                                                                  srvc, ch);
+            break;
+        case 1:
+            s = data.gattiface->client->deregister_for_notification(data.client,
+                                                                    &dev->bda,
+                                                                    srvc, ch);
+            break;
+    }
+
+    if (s != BT_STATUS_SUCCESS)
+        return -s;
+
+    return 0;
+}
+
+int ble_gatt_register_char_notification(int conn_id, int char_id) {
+    return ble_gatt_char_notification(0, conn_id, char_id);
+}
+
+int ble_gatt_unregister_char_notification(int conn_id, int char_id) {
+    return ble_gatt_char_notification(1, conn_id, char_id);
+}
+
 /* Called when the client registration is finished */
 static void register_client_cb(int status, int client_if, bt_uuid_t *app_uuid) {
     if (status == BT_STATUS_SUCCESS) {
@@ -716,8 +792,8 @@ static const btgatt_client_callbacks_t gattccbs = {
     characteristic_discovery_cb,
     descriptor_discovery_cb,
     NULL, /* get_included_service_cb */
-    NULL, /* register_for_notification_cb */
-    NULL, /* notify_cb */
+    register_for_notification_cb,
+    notify_cb,
     read_characteristic_cb,
     write_characteristic_cb,
     read_descriptor_cb,
diff --git a/lib/ble.h b/lib/ble.h
index 5580a22..8d072ad 100644
--- a/lib/ble.h
+++ b/lib/ble.h
@@ -147,6 +147,35 @@ typedef void (*ble_gatt_response_cb_t)(int conn_id, int id,
                                        uint16_t value_type, int status);
 
 /**
+ * Type that represents a callback function to notify that a registration for
+ * characteristic notification has finished.
+ *
+ * @param conn_id The identifier of the connected remote device.
+ * @param char_id ID of the characteristic to register for notifications.
+ * @param registered Whether notifications for the characteristic has been
+ *                   successfully registered: 1 yes, 0 no.
+ * @param status The response status of the registration operation.
+ */
+typedef void (*ble_gatt_notification_register_cb_t)(int conn_id, int char_id,
+                                                    int registered, int status);
+
+/**
+ * Type that represents a callback function to forward a GATT notification or
+ * indication.
+ *
+ * @param conn_id The identifier of the connected remote device.
+ * @param char_id ID of the characteristic that the notification refers to.
+ * @param value The new value of the characteristic.
+ * @param value_len The length of the data pointed by the value parameter.
+ * @param is_indication Whether the received packed is a notification or an
+ *                      indication: 0 notification, 1 indication.
+ */
+typedef void (*ble_gatt_notification_cb_t)(int conn_id, int char_id,
+                                           const uint8_t *value,
+                                           uint16_t value_len,
+                                           uint8_t is_indication);
+
+/**
  * List of callbacks for BLE operations.
  */
 typedef struct ble_cbs {
@@ -166,6 +195,8 @@ typedef struct ble_cbs {
     ble_gatt_response_cb_t desc_read_cb;
     ble_gatt_response_cb_t char_write_cb;
     ble_gatt_response_cb_t desc_write_cb;
+    ble_gatt_notification_register_cb_t char_notification_register_cb;
+    ble_gatt_notification_cb_t char_notification_cb;
 } ble_cbs_t;
 
 /**
@@ -418,4 +449,36 @@ int ble_gatt_write_cmd_desc(int conn_id, int desc_id, int auth,
  */
 int ble_gatt_write_req_desc(int conn_id, int desc_id, int auth,
                             const char *value, int len);
+
+/**
+ * Register for notifications of changes in the value of a characteristic.
+ *
+ * There should be an active connection with the device.
+ *
+ * @param conn_id The identifier of the connected remote device.
+ * @param char_id The identifier of the characteristic to register for
+ *                notifications.
+ *
+ * @return 0 if registration for characteristic notifications have been
+ *           successfully requested.
+ * @return -1 if failed to request registration for characteristic
+ *            notifications.
+ */
+int ble_gatt_register_char_notification(int conn_id, int char_id);
+
+/**
+ * Unregister for notifications of changes in the value of a characteristic.
+ *
+ * There should be an active connection with the device.
+ *
+ * @param conn_id The identifier of the connected remote device.
+ * @param char_id The identifier of the characteristic to unregister for
+ *                notifications.
+ *
+ * @return 0 if deregistration for characteristic notifications have been
+ *           successfully requested.
+ * @return -1 if failed to request deregistration for characteristic
+ *            notifications.
+ */
+int ble_gatt_unregister_char_notification(int conn_id, int char_id);
 #endif