app-layer: fix gap handling in protocol detection

A GAP during protocol detection would lead to all reassembly
getting disabled, so also the raw reassembly. In addition, it
could prevent the opposing side from doing protocol detection.

This patch remove the 'disable reassembly' logic. Stream engine
will take the stream with GAP and app-layer will make the proto
detection as complete.

src/app-layer.c

@@ -560,7 +560,6 @@ int AppLayerHandleTCPData(ThreadVars *tv, TcpReassemblyThreadCtx *ra_ctx,
 
     AppLayerThreadCtx *app_tctx = ra_ctx->app_tctx;
     AppProto alproto;
-    uint8_t dir;
     int r = 0;
 
     SCLogDebug("data_len %u flags %02X", data_len, flags);
@@ -571,10 +570,8 @@ int AppLayerHandleTCPData(ThreadVars *tv, TcpReassemblyThreadCtx *ra_ctx,
 
     if (flags & STREAM_TOSERVER) {
         alproto = f->alproto_ts;
-        dir = 0;
     } else {
         alproto = f->alproto_tc;
-        dir = 1;
     }
 
     /* if we don't know the proto yet and we have received a stream
@@ -583,7 +580,6 @@ int AppLayerHandleTCPData(ThreadVars *tv, TcpReassemblyThreadCtx *ra_ctx,
      * only run the proto detection once. */
     if (alproto == ALPROTO_UNKNOWN && (flags & STREAM_GAP)) {
         StreamTcpSetStreamFlagAppProtoDetectionCompleted(stream);
-        StreamTcpSetSessionNoReassemblyFlag(ssn, dir);
         SCLogDebug("ALPROTO_UNKNOWN flow %p, due to GAP in stream start", f);
 
     } else if (alproto == ALPROTO_UNKNOWN && (flags & STREAM_START)) {

src/stream-tcp-reassemble.c

@@ -2903,7 +2903,7 @@ int StreamTcpReassembleAppLayer (ThreadVars *tv, TcpReassemblyThreadCtx *ra_ctx,
 
     /* this function can be directly called by app layer protocol
      * detection. */
-    if (stream->flags & STREAMTCP_STREAM_FLAG_NOREASSEMBLY) {
+    if (stream->flags & (STREAMTCP_STREAM_FLAG_NOREASSEMBLY|STREAMTCP_STREAM_FLAG_GAP)) {
         SCLogDebug("stream no reassembly flag set.  Mostly called via "
                    "app proto detection.");
         SCReturnInt(0);