Refactor 'readDeviceId' to have a boolean return value like 'reconstructCertificate' which allows for a similiar check/control flow in 'ArduinoIoTCloud::begin'

Author: aentinger

src/ArduinoIoTCloudTCP.cpp

@@ -76,8 +76,7 @@ int ArduinoIoTCloudTCP::begin(String brokerAddress, uint16_t brokerPort) {
   #ifdef BOARD_HAS_ECCX08
   if (!ECCX08.begin()) { Debug.print(DBG_ERROR, "Cryptography processor failure. Make sure you have a compatible board."); return 0; }
 
-  _device_id = CryptoUtil::readDeviceId(ECCX08, ECCX08Slot::DeviceId);
-  if(_device_id.length() == 0) { Debug.print(DBG_ERROR, "Cryptography processor read failure."); return 0; }
+  if (!CryptoUtil::readDeviceId(ECCX08, _device_id, ECCX08Slot::DeviceId)) { Debug.print(DBG_ERROR, "Cryptography processor read failure."); return 0; }
 
   if (!CryptoUtil::reconstructCertificate(ECCX08Cert, _device_id, ECCX08Slot::Key, ECCX08Slot::CompressedCertificate, ECCX08Slot::SerialNumberAndAuthorityKeyIdentifier)) { Debug.print(DBG_ERROR, "Cryptography certificate reconstruction failure."); return 0; }
 

src/utility/crypto/CryptoUtil.cpp

@@ -27,14 +27,17 @@
    PUBLIC MEMBER FUNCTIONS
  ******************************************************************************/
 
-String CryptoUtil::readDeviceId(ECCX08Class & eccx08, ECCX08Slot const slot)
+bool CryptoUtil::readDeviceId(ECCX08Class & eccx08, String & device_id, ECCX08Slot const device_id_slot)
 {
   byte device_id_bytes[72] = {0};
 
-  if (eccx08.readSlot(static_cast<int>(slot), device_id_bytes, sizeof(device_id_bytes))) {
-   return String(reinterpret_cast<char *>(device_id_bytes));
-  } else {
-   return String("");
+  if (eccx08.readSlot(static_cast<int>(device_id_slot), device_id_bytes, sizeof(device_id_bytes))) {
+   device_id = String(reinterpret_cast<char *>(device_id_bytes));
+   return true;
+  }
+  else
+  {
+   return false;
   }
 }
 

src/utility/crypto/CryptoUtil.h

@@ -50,8 +50,8 @@ class CryptoUtil
 {
 public:
 
-  static String readDeviceId(ECCX08Class & eccx08, ECCX08Slot const slot);
-  static bool   reconstructCertificate(ECCX08CertClass & cert, String const & device_id, ECCX08Slot const key, ECCX08Slot const compressed_certificate, ECCX08Slot const serial_number_and_authority_key);
+  static bool readDeviceId(ECCX08Class & eccx08, String & device_id, ECCX08Slot const device_id_slot);
+  static bool reconstructCertificate(ECCX08CertClass & cert, String const & device_id, ECCX08Slot const key, ECCX08Slot const compressed_certificate, ECCX08Slot const serial_number_and_authority_key);
 
 
 private: