From 0a47f745cc87f967f0d8513b4178321e21a02efc Mon Sep 17 00:00:00 2001
From: Ivan Nardi <12729895+IvanNardi@users.noreply.github.com>
Date: Mon, 5 Sep 2022 13:59:51 +0200
Subject: Avoid useless host automa lookup (#1724)

The host automa is used for two tasks:
* protocol sub-classification (obviously);
* DGA evaluation: the idea is that if a domain is present in this
automa, it can't be a DGA, regardless of its format/name.

In most dissectors both checks are executed, i.e. the code is something
like:

```
ndpi_match_host_subprotocol(..., flow->host_server_name, ...);
ndpi_check_dga_name(..., flow->host_server_name,...);

```

In that common case, we can perform only one automa lookup: if we check the
sub-classification before the DGA, we can avoid the second lookup in
the DGA function itself.
---
 src/lib/protocols/http.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

(limited to 'src/lib/protocols/http.c')

diff --git a/src/lib/protocols/http.c b/src/lib/protocols/http.c
index 6fe6cab33..f9d6abd90 100644
--- a/src/lib/protocols/http.c
+++ b/src/lib/protocols/http.c
@@ -722,8 +722,6 @@ static void check_content_type_and_change_protocol(struct ndpi_detection_module_
     ndpi_hostname_sni_set(flow, packet->host_line.ptr, packet->host_line.len);
 
     if(strlen(flow->host_server_name) > 0) {
-      ndpi_check_dga_name(ndpi_struct, flow, flow->host_server_name, 1);
-
       if(ndpi_is_valid_hostname(flow->host_server_name,
 				strlen(flow->host_server_name)) == 0) {
 	char str[128];
@@ -749,6 +747,10 @@ static void check_content_type_and_change_protocol(struct ndpi_detection_module_
 
     ndpi_http_parse_subprotocol(ndpi_struct, flow);
 
+    if(strlen(flow->host_server_name) > 0) {
+      ndpi_check_dga_name(ndpi_struct, flow, flow->host_server_name, 1, 0);
+    }
+
     /**
        check result of host subprotocol detection
 
-- 
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