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>

src/bacnet/create_object.c

@@ -95,6 +95,28 @@ int create_object_encode_service_request(
     return apdu_len;
 }
 
+/**
+ * @brief Encode the CreateObject service request
+ * @param apdu  Pointer to the buffer for encoding into
+ * @param apdu_size number of bytes available in the buffer
+ * @param data  Pointer to the service data used for encoding values
+ * @return number of bytes encoded, or zero if unable to encode or too large
+ */
+size_t create_object_service_request_encode(
+    uint8_t *apdu, size_t apdu_size, BACNET_CREATE_OBJECT_DATA *data)
+{
+    size_t apdu_len = 0; /* total length of the apdu, return value */
+
+    apdu_len = create_object_encode_service_request(NULL, data);
+    if (apdu_len > apdu_size) {
+        apdu_len = 0;
+    } else {
+        apdu_len = create_object_encode_service_request(apdu, data);
+    }
+
+    return apdu_len;
+}
+
 /**
  * @brief Decode the CreateObject service request
  *
@@ -351,7 +373,6 @@ int create_object_error_ack_encode(
     return len;
 }
 
-#if !BACNET_SVC_SERVER
 /**
  * @brief Decode a CreateObject-Error ACK APDU
  *
@@ -420,4 +441,3 @@ int create_object_error_ack_service_decode(
 
     return apdu_len;
 }
-#endif