add onMtuChanged to BLEServerCallbacks (#5222)

* add onMtuChanged to BLEServerCallbacks

Add method onMtuChanged to the BLEServerCallbacks so the application can be notified if the MTU size changes.

* Correct missing semicolon and misspelled method.

Correct missing semicolon and misspelled method.

libraries/BLE/src/BLEServer.cpp

@@ -157,6 +157,7 @@ void BLEServer::handleGATTServerEvent(esp_gatts_cb_event_t event, esp_gatt_if_t
 
 		case ESP_GATTS_MTU_EVT:
 			updatePeerMTU(param->mtu.conn_id, param->mtu.mtu);
+			m_pServerCallbacks->onMtuChanged(this, param);
 			break;
 
 		// ESP_GATTS_CONNECT_EVT
@@ -371,6 +372,12 @@ void BLEServerCallbacks::onDisconnect(BLEServer* pServer) {
 	log_d("BLEServerCallbacks", "<< onDisconnect()");
 } // onDisconnect
 
+void BLEServerCallbacks::onMtuChanged(BLEServer* pServer, esp_ble_gatts_cb_param_t* param) {
+	log_d("BLEServerCallbacks", ">> onMtuChanged(): Default");
+	log_d("BLEServerCallbacks", "Device: %s MTU: %d", BLEDevice::toString().c_str(), param->mtu.mtu);
+	log_d("BLEServerCallbacks", "<< onMtuChanged()");
+} // onMtuChanged
+
 /* multi connect support */
 /* TODO do some more tweaks */
 void BLEServer::updatePeerMTU(uint16_t conn_id, uint16_t mtu) {

libraries/BLE/src/BLEServer.h

@@ -134,6 +134,16 @@ class BLEServerCallbacks {
 	 * @param [in] pServer A reference to the %BLE server that received the existing client disconnection.
 	 */
 	virtual void onDisconnect(BLEServer* pServer);
+
+	/**
+	 * @brief Handle a new client connection.
+	 *
+	 * When the MTU changes this method is invoked.
+	 *
+	 * @param [in] pServer A reference to the %BLE server that received the client connection.
+	 * @param [in] param A reference to esp_ble_gatts_cb_param_t.
+	 */
+	virtual void onMtuChanged(BLEServer* pServer, esp_ble_gatts_cb_param_t* param);
 }; // BLEServerCallbacks