Harden interactive service pipe

Harden interactive service pipe

- Append a version 4 uuid to ovpn_pipe_name to make it less
  predictable
- Do not allow remote access to the pipe

This greatly reduces the possibility of a rogue process racing to
open the pipe before CreateFile() is called in the worker thread.

Reported-by: Marc Heuse <marc@srlabs.de>
Change-Id: Ie66a142751354e421d48b273784fc79bcb9f7208
Signed-off-by: Selva Nair <selva.nair@gmail.com>
Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1396
Message-Id: <20251124165311.14859-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg34638.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>