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/dns.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

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

diff --git a/src/lib/protocols/dns.c b/src/lib/protocols/dns.c
index ecf283a77..e12ece12c 100644
--- a/src/lib/protocols/dns.c
+++ b/src/lib/protocols/dns.c
@@ -529,8 +529,6 @@ static void ndpi_search_dns(struct ndpi_detection_module_struct *ndpi_struct, st
     if(j > 0) {
       ndpi_protocol_match_result ret_match;
 
-      ndpi_check_dga_name(ndpi_struct, flow, flow->host_server_name, 1);
-
       ret.app_protocol = ndpi_match_host_subprotocol(ndpi_struct, flow,
 						     flow->host_server_name,
 						     strlen(flow->host_server_name),
@@ -544,6 +542,8 @@ static void ndpi_search_dns(struct ndpi_detection_module_struct *ndpi_struct, st
 	ret.master_protocol = checkDNSSubprotocol(s_port, d_port);
       else
 	ret.master_protocol = NDPI_PROTOCOL_DNS;
+
+      ndpi_check_dga_name(ndpi_struct, flow, flow->host_server_name, 1, 0);
     }
 
     /* Report if this is a DNS query or reply */
-- 
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