checking string property size during encoding

Author: andreagilardoni

src/property/types/CloudWrapperString.h

@@ -23,6 +23,7 @@
  ******************************************************************************/
 
 #include <Arduino.h>
+#include "AIoTC_Config.h"
 #include "CloudWrapperBase.h"
 
 /******************************************************************************
@@ -50,7 +51,32 @@ class CloudWrapperString : public CloudWrapperBase {
       _cloud_value = _primitive_value;
     }
     virtual CborError appendAttributesToCloud(CborEncoder *encoder) {
-      return appendAttribute(_primitive_value, "", encoder);
+      // check that the string fits mqtt tx buffer
+      if(_name.length() > STRING_PROPERTY_MAX_SIZE) {
+        Serial.print(__FILE__); Serial.print(__LINE__);
+        Serial.println("[WARNING] String property name exceedes transmit buffer size, unable to send property");
+
+        /*
+         * If your reached this line it means that you set a preperty name that exceeded the current maximum capabilities
+         * of transmission buffer size. You can either change the buiffer size or the property name can be shortened.
+         * Look below for raising the buffer size
+         */
+
+        return CborErrorOutOfMemory;
+      } else if(_primitive_value.length() + _name.length() > STRING_PROPERTY_MAX_SIZE) {
+        Serial.print(__FILE__); Serial.print(__LINE__);
+        Serial.println("[WARNING] String property exceedes transmit buffer size");
+
+        /*
+         * If your reached this line it means that the value and the property name exceed the current maximum capabilities
+         * of transmission buffer size. to fix this you can raise the size of the buffer.
+         * you can raise the size of the buffer by setting #define MQTT_TX_BUFFER_SIZE <VALUE> at the beginning of the file
+         */
+
+        return appendAttribute("ERROR_PROPERTY_TOO_LONG", "", encoder);
+      } else {
+        return appendAttribute(_primitive_value, "", encoder);
+      }
     }
     virtual void setAttributesFromCloud() {
       setAttribute(_cloud_value, "");