Fix for issue #4158: BLEAdvertising - Crash with stack trace originating in Bluedroid (#4182)

* Fix for issue #4158: Crash with stack trace originating in Bluedroid
Improved configuration of scan response data in 'BLEAdvertising' avoids the crash:
- Added member variable 'm_scanRespData' to configure scan response differently from advertising data
- Initialization of 'm_scanRespData' in BLEAdvertising constructor
- Use of 'm_scanRespData' within BLEAdvertising::start() to configure the scan response
- 'Flags' and 'Appearance' are cleared in the scan response data
- With this fix, device names of up to 29 characters can be used without causing a crash.

Author: esikora

Diff for: libraries/BLE/src/BLEAdvertising.cpp

@@ -28,7 +28,9 @@
  * @brief Construct a default advertising object.
  *
  */
-BLEAdvertising::BLEAdvertising() {
+BLEAdvertising::BLEAdvertising()
+: m_scanRespData{}
+{
 	m_advData.set_scan_rsp        = false;
 	m_advData.include_name        = true;
 	m_advData.include_txpower     = true;
@@ -215,10 +217,15 @@ void BLEAdvertising::start() {
 	}
 
 	if (!m_customScanResponseData && m_scanResp) {
-		m_advData.set_scan_rsp = true;
-		m_advData.include_name = m_scanResp;
-		m_advData.include_txpower = m_scanResp;
-		errRc = ::esp_ble_gap_config_adv_data(&m_advData);
+		// Set the configuration for scan response.
+		memcpy(&m_scanRespData, &m_advData, sizeof(esp_ble_adv_data_t)); // Copy the content of m_advData.
+		m_scanRespData.set_scan_rsp = true; // Define this struct as scan response data
+		m_scanRespData.include_name = true; // Caution: This may lead to a crash if the device name has more than 29 characters
+		m_scanRespData.include_txpower = true;
+		m_scanRespData.appearance = 0; // If defined the 'Appearance' attribute is already included in the advertising data
+		m_scanRespData.flag = 0; // 'Flags' attribute should no be included in the scan response
+
+		errRc = ::esp_ble_gap_config_adv_data(&m_scanRespData);
 		if (errRc != ESP_OK) {
 			log_e("<< esp_ble_gap_config_adv_data (Scan response): rc=%d %s", errRc, GeneralUtils::errorToString(errRc));
 			return;

Diff for: libraries/BLE/src/BLEAdvertising.h

@@ -30,7 +30,7 @@ class BLEAdvertisementData {
 	void setPartialServices(BLEUUID uuid);
 	void setServiceData(BLEUUID uuid, std::string data);
 	void setShortName(std::string name);
-	void        addData(std::string data);  // Add data to the payload.
+	void addData(std::string data);         // Add data to the payload.
 	std::string getPayload();               // Retrieve the current advert payload.
 
 private:
@@ -68,12 +68,13 @@ class BLEAdvertising {
 
 private:
 	esp_ble_adv_data_t   m_advData;
+	esp_ble_adv_data_t   m_scanRespData; // Used for configuration of scan response data when m_scanResp is true
 	esp_ble_adv_params_t m_advParams;
 	std::vector<BLEUUID> m_serviceUUIDs;
 	bool                 m_customAdvData = false;  // Are we using custom advertising data?
 	bool                 m_customScanResponseData = false;  // Are we using custom scan response data?
 	FreeRTOS::Semaphore  m_semaphoreSetAdv = FreeRTOS::Semaphore("startAdvert");
-	bool				m_scanResp = true;
+	bool                 m_scanResp = true;
 
 };
 #endif /* CONFIG_BT_ENABLED */