dnp3: activate unidirectional TX flag

By implementing the no inspection flag we can now set
the unidirectional TX flag. Which means that the alstate
progress function can now be simplified to always return
1 f the transaction is complete.

Ticket: #5799

src/app-layer-dnp3.c

@@ -499,6 +499,11 @@ static DNP3Transaction *DNP3TxAlloc(DNP3State *dnp3, bool request)
     tx->dnp3 = dnp3;
     tx->tx_num = dnp3->transaction_max;
     tx->is_request = request;
+    if (tx->is_request) {
+        tx->tx_data.detect_flags_tc |= APP_LAYER_TX_SKIP_INSPECT_FLAG;
+    } else {
+        tx->tx_data.detect_flags_ts |= APP_LAYER_TX_SKIP_INSPECT_FLAG;
+    }
     TAILQ_INIT(&tx->objects);
     TAILQ_INSERT_TAIL(&dnp3->tx_list, tx, next);
 
@@ -1423,31 +1428,8 @@ static int DNP3GetAlstateProgress(void *tx, uint8_t direction)
         SCReturnInt(1);
     }
 
-    /* This is a unidirectional protocol.
-     *
-     * If progress is being checked in the TOSERVER (request)
-     * direction, always return complete if the message is not a
-     * request, as there will never be replies on transactions created
-     * in the TOSERVER direction.
-     *
-     * Like wise, if progress is being checked in the TOCLIENT
-     * direction, requests will never be seen. So always return
-     * complete if the transaction is not a reply.
-     *
-     * Otherwise, if TOSERVER and transaction is a request, return
-     * complete if the transaction is complete. And if TOCLIENT and
-     * transaction is a response, return complete if the transaction
-     * is complete.
-     */
-    if (direction & STREAM_TOSERVER) {
-        if (!dnp3tx->is_request || dnp3tx->complete) {
-            retval = 1;
-        }
-    } else if (direction & STREAM_TOCLIENT) {
-        if (dnp3tx->is_request || dnp3tx->complete) {
-            retval = 1;
-        }
-    }
+    if (dnp3tx->complete)
+        retval = 1;
 
     SCReturnInt(retval);
 }
@@ -1614,12 +1596,9 @@ void RegisterDNP3Parsers(void)
         AppLayerParserRegisterTxDataFunc(IPPROTO_TCP, ALPROTO_DNP3,
             DNP3GetTxData);
         AppLayerParserRegisterStateDataFunc(IPPROTO_TCP, ALPROTO_DNP3, DNP3GetStateData);
-#if 0
-        /* While this parser is now fully unidirectional. setting this
-         * flag breaks detection at this time. */
+
         AppLayerParserRegisterOptionFlags(
                 IPPROTO_TCP, ALPROTO_DNP3, APP_LAYER_PARSER_OPT_UNIDIR_TXS);
-#endif
     }
     else {
         SCLogConfig("Parser disabled for protocol %s. "