app-layer-parser: don't overwrite stream_depth value

When an app-layer parser is enabled, it could set its
own stream_depth value calling the API AppLayerParserSetStreamDepth.

Then, the function AppLayerParserPostStreamSetup will replace
the stream_depth value already set with stream_config.reassembly_depth.

To avoid overwriting, in AppLayerParserSetStreamDepth API a flag
will be set internally to specify that a value is already set.

src/app-layer-parser.c

@@ -209,11 +209,14 @@ void AppLayerParserPostStreamSetup(void)
     /* lets set a default value for stream_depth */
     for (flow_proto = 0; flow_proto < FLOW_PROTO_DEFAULT; flow_proto++) {
         for (alproto = 0; alproto < ALPROTO_MAX; alproto++) {
+            if (!(alp_ctx.ctxs[flow_proto][alproto].flags &
+                APP_LAYER_PARSER_OPT_STREAM_DEPTH_SET)) {
                 alp_ctx.ctxs[flow_proto][alproto].stream_depth =
                     stream_config.reassembly_depth;
             }
         }
     }
+}
 
 int AppLayerParserDeSetup(void)
 {
@@ -1315,6 +1318,8 @@ void AppLayerParserSetStreamDepth(uint8_t ipproto, AppProto alproto, uint32_t st
     SCEnter();
 
     alp_ctx.ctxs[FlowGetProtoMapping(ipproto)][alproto].stream_depth = stream_depth;
+    alp_ctx.ctxs[FlowGetProtoMapping(ipproto)][alproto].flags |=
+        APP_LAYER_PARSER_OPT_STREAM_DEPTH_SET;
 
     SCReturn;
 }

src/app-layer-parser.h

@@ -39,6 +39,7 @@
 
 /* Flags for AppLayerParserProtoCtx. */
 #define APP_LAYER_PARSER_OPT_ACCEPT_GAPS        BIT_U64(0)
+#define APP_LAYER_PARSER_OPT_STREAM_DEPTH_SET   BIT_U64(1)
 
 /* applies to DetectFlags uint64_t field */