tunnel_server(): close correct inotify fd

On a full SIGUSR1 restart of a p2mp server compiled with
--enable-async-push, tunnel_server() will try to close and reopen
the "inotify" control file descriptor.  For whatever reason, the
original code referenced the wrong context, always closing fd 0.

As a consequence of this, on the second SIGUSR1 restart, the server
will close() the first active socket file descriptor, and if there
are active DCO clients, the resulting event confusion will lead to
an ASSERT(!mi->halt).

Fix by closing the correct FD. Add logging.

Github: fixes OpenVPN/openvpn#966

Change-Id: Iabc117848ad7b67d240c392f1a6aa2d7531fd5bb
Signed-off-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Arne Schwabe <arne-openvpn@rfc2549.org>
Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1497
Message-Id: <20260128110425.24350-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg35478.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>

src/openvpn/multi.c

@@ -4244,7 +4244,9 @@ tunnel_server(struct context *top)
     tunnel_server_loop(&multi);
 
 #ifdef ENABLE_ASYNC_PUSH
-    close(top->c2.inotify_fd);
+    msg(D_LOW, "%s: close multi.top.c2.inotify_fd (%d)",
+        __func__, multi.top.c2.inotify_fd);
+    close(multi.top.c2.inotify_fd);
 #endif
 
     /* shut down management interface */