detect: http_stat_msg supported for HTTP2

By providing a constant empty buffer

Ticket: #4067

src/detect-http-stat-msg.c

@@ -72,6 +72,19 @@ static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
         const uint8_t _flow_flags, void *txv, const int list_id);
 static int DetectHttpStatMsgSetupSticky(DetectEngineCtx *de_ctx, Signature *s, const char *str);
 
+static InspectionBuffer *GetData2(DetectEngineThreadCtx *det_ctx,
+        const DetectEngineTransforms *transforms, Flow *_f, const uint8_t _flow_flags, void *txv,
+        const int list_id)
+{
+    InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
+    if (buffer->inspect == NULL) {
+        InspectionBufferSetup(det_ctx, list_id, buffer, (const uint8_t *)"", 0);
+        InspectionBufferApplyTransforms(buffer, transforms);
+    }
+
+    return buffer;
+}
+
 /**
  * \brief Registration function for keyword: http_stat_msg
  */
@@ -101,6 +114,11 @@ void DetectHttpStatMsgRegister (void)
     DetectAppLayerMpmRegister2("http_stat_msg", SIG_FLAG_TOCLIENT, 3, PrefilterGenericMpmRegister,
             GetData, ALPROTO_HTTP1, HTP_RESPONSE_LINE);
 
+    DetectAppLayerInspectEngineRegister2("http_stat_msg", ALPROTO_HTTP2, SIG_FLAG_TOCLIENT,
+            HTTP2StateDataServer, DetectEngineInspectBufferGeneric, GetData2);
+    DetectAppLayerMpmRegister2("http_stat_msg", SIG_FLAG_TOCLIENT, 2, PrefilterGenericMpmRegister,
+            GetData2, ALPROTO_HTTP2, HTTP2StateDataServer);
+
     DetectBufferTypeSetDescriptionByName("http_stat_msg",
             "http response status message");
 
@@ -137,7 +155,7 @@ static int DetectHttpStatMsgSetupSticky(DetectEngineCtx *de_ctx, Signature *s, c
 {
     if (DetectBufferSetActiveList(de_ctx, s, g_http_stat_msg_buffer_id) < 0)
         return -1;
-    if (DetectSignatureSetAppProto(s, ALPROTO_HTTP1) < 0)
+    if (DetectSignatureSetAppProto(s, ALPROTO_HTTP) < 0)
         return -1;
     return 0;
 }