app-layer: don't switch dir if proto already known

src/app-layer.c

@@ -399,10 +399,13 @@ static int TCPProtoDetect(ThreadVars *tv,
         TcpSessionSetReassemblyDepth(ssn,
                 AppLayerParserGetStreamDepth(f));
         FlagPacketFlow(p, f, flags);
+
         /* if protocol detection indicated that we need to reverse
          * the direction of the flow, do it now. We flip the flow,
          * packet and the direction flags */
         if (reverse_flow && (ssn->flags & STREAMTCP_FLAG_MIDSTREAM)) {
+            /* but only if we didn't already detect it on the other side. */
+            if (*alproto_otherdir == ALPROTO_UNKNOWN) {
                 SCLogDebug("reversing flow after proto detect told us so");
                 PacketSwap(p);
                 FlowSwap(f);
@@ -413,6 +416,9 @@ static int TCPProtoDetect(ThreadVars *tv,
                     *stream = &ssn->client;
                 }
                 direction = 1 - direction;
+            } else {
+                // TODO event, error?
+            }
         }
 
         /* account flow if we have both sides */