Feature/zeroing rx buffer remain (#90)

* Added zeroing rx buffer remain

* Added zeroing rx buffer remain

* Added safety margin for the rx-buffer in the different ports.

* Added safety margin for the receive buffer.

* Added DoxyGen comments.

* Fixed checking return value when calculating distance between opening and closing tag on multiple properties.

ports/esp32/src/main.c

@@ -48,7 +48,15 @@ wifi_config_t wifi_config = {
 #define BACNET_LED 5
 
 uint8_t Handler_Transmit_Buffer[MAX_PDU] = { 0 };
-uint8_t Rx_Buf[MAX_MPDU] = { 0 };
+
+/** Static receive buffer, initialized with zeros by the C Library Startup Code. */
+
+uint8_t Rx_Buf[MAX_MPDU + 16 /* Add a little safety margin to the buffer,
+                              * so that in the rare case, the message
+                              * would be filled up to MAX_MPDU and some
+                              * decoding functions would overrun, these
+                              * decoding functions will just end up in
+                              * a safe field of static zeros. */] = { 0 };
 
 EventGroupHandle_t wifi_event_group;
 const static int CONNECTED_BIT = BIT0;
@@ -207,4 +215,4 @@ void app_main()
         NULL, /* Task input parameter */
         20, /* Priority of the task */
         NULL); /* Task handle. */
-}
+}