Refactor JWTHelper base64 URL encoding to modify output in-place and improve memory efficiency. Enhance MQTTBridge cleanup process to prevent memory leaks by properly deleting queued packets and timezone objects.

src/helpers/JWTHelper.cpp

@@ -172,22 +172,22 @@ size_t JWTHelper::base64UrlEncode(const uint8_t* input, size_t inputLen, char* o
   
   Serial.printf("JWTHelper: mbedtls_base64_encode result: %s (outlen: %d)\n", output, (int)outlen);
   
-  // Convert to base64 URL format (replace + with -, / with _, remove padding =)
-  String encoded(output);
-  encoded.replace('+', '-');
-  encoded.replace('/', '_');
-  encoded.replace("=", "");
-  
-  // Copy back to output buffer
-  size_t len = encoded.length();
-  if (len >= outputSize) {
-    Serial.printf("JWTHelper: base64UrlEncode output too large: %d >= %d\n", (int)len, (int)outputSize);
-    return 0;
+  // Convert to base64 URL format in-place (replace + with -, / with _, remove padding =)
+  for (size_t i = 0; i < outlen; i++) {
+    if (output[i] == '+') {
+      output[i] = '-';
+    } else if (output[i] == '/') {
+      output[i] = '_';
+    }
   }
   
-  strcpy(output, encoded.c_str());
-  Serial.printf("JWTHelper: base64UrlEncode completed, outputLen: %d\n", (int)len);
-  return len;
+  // Remove padding '=' characters
+  while (outlen > 0 && output[outlen-1] == '=') {
+    outlen--;
+  }
+  output[outlen] = '\0';
+  Serial.printf("JWTHelper: base64UrlEncode completed, outputLen: %d\n", (int)outlen);
+  return outlen;
 }
 
 size_t JWTHelper::createHeader(char* output, size_t outputSize) {

src/helpers/bridges/MQTTBridge.cpp

@@ -228,11 +228,26 @@ void MQTTBridge::end() {
     _analyzer_eu_client = nullptr;
   }
   
+  // Clean up queued packets to prevent memory leaks
+  for (int i = 0; i < _queue_count; i++) {
+    int index = (_queue_head + i) % MAX_QUEUE_SIZE;
+    if (_packet_queue[index].packet) {
+      _mgr->free(_packet_queue[index].packet);
+      _packet_queue[index].packet = nullptr;
+    }
+  }
+  
   // Clear packet queue
   _queue_count = 0;
   _queue_head = 0;
   _queue_tail = 0;
   
+  // Clean up timezone object to prevent memory leak
+  if (_timezone) {
+    delete _timezone;
+    _timezone = nullptr;
+  }
+  
   // Clean up resources
   if (_mqtt_client) {
     delete _mqtt_client;
@@ -1045,6 +1060,12 @@ void MQTTBridge::syncTimeWithNTP() {
       // Set timezone from string (with DST support)
       MQTT_DEBUG_PRINTLN("Setting timezone: %s", _prefs->timezone_string);
       
+      // Clean up old timezone object to prevent memory leak
+      if (_timezone) {
+        delete _timezone;
+        _timezone = nullptr;
+      }
+      
       // Create timezone object based on timezone string
       Timezone* tz = createTimezoneFromString(_prefs->timezone_string);
       if (tz) {