management: stop bytecount on client disconnection

When a management interface client requests periodic bytecount
notifications, openvpn continues to emit them even after the client has
disconnected. Additionally, upon reconnecting, the client starts
receiving these notifications without having issued a new bytecount
command.

Stop the periodic bytecount operation when the management interface
client disconnects, preventing unnecessary stats polling when using DCO
and ensuring that clients only receive notifications they have
explicitly requested.

Change-Id: I6bdded6c70596b69428e6a00a405ac3cedc405fa
Signed-off-by: Ralf Lici <ralf@mandelbit.com>
Acked-by: Arne Schwabe <arne-openvpn@rfc2549.org>
Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1533
Message-Id: <20260302163557.18358-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg35825.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry-picked from fccdb21733)

src/openvpn/manage.c

@@ -470,6 +470,13 @@ man_status(struct management *man, const int version, struct status_output *so)
     }
 }
 
+static void
+man_bytecount_stop(struct management *man)
+{
+    man->connection.bytecount_update_seconds = 0;
+    event_timeout_clear(&man->connection.bytecount_update_interval);
+}
+
 static void
 man_bytecount(struct management *man, const int update_seconds)
 {
@@ -482,8 +489,7 @@ man_bytecount(struct management *man, const int update_seconds)
     }
     else
     {
-        man->connection.bytecount_update_seconds = 0;
-        event_timeout_clear(&man->connection.bytecount_update_interval);
+        man_bytecount_stop(man);
     }
     msg(M_CLIENT, "SUCCESS: bytecount interval changed");
 }
@@ -1992,6 +1998,7 @@ man_reset_client_socket(struct management *man, const bool exiting)
 {
     if (socket_defined(man->connection.sd_cli))
     {
+        man_bytecount_stop(man);
 #ifdef _WIN32
         man_stop_ne32(man);
 #endif