Bugfix/service request refactor size check (#553)

* refactor service requests from service header

* add APDU size checking and length feature

* add unit tests to check for length when passing NULL buffer

---------

Co-authored-by: Steve Karg <skarg@users.sourceforge.net>

test/bacnet/rd/src/main.c

@@ -30,21 +30,21 @@ static int rd_decode_apdu(uint8_t *apdu,
     int apdu_len = 0;
 
     if (!apdu) {
-        return -1;
+        return BACNET_STATUS_ERROR;
     }
     if (apdu_size <= 4) {
-        return -1;
+        return BACNET_STATUS_ERROR;
     }
     /* optional checking - most likely was already done prior to this call */
     if (apdu[0] != PDU_TYPE_CONFIRMED_SERVICE_REQUEST) {
-        return -1;
+        return BACNET_STATUS_ERROR;
     }
     /*  apdu[1] = encode_max_segs_max_apdu(0, MAX_APDU); */
     if (invoke_id) {
         *invoke_id = apdu[2]; /* invoke id - filled in by net layer */
     }
     if (apdu[3] != SERVICE_CONFIRMED_REINITIALIZE_DEVICE) {
-        return -1;
+        return BACNET_STATUS_ERROR;
     }
     apdu_len = 4;
     if (apdu_len < apdu_size) {