Preserve --dhcp-option values from local config

Preserve --dhcp-option values from local config

Commit

  2dfc4f8 ("dns: deal with --dhcp-options when --dns is active")

has changed the way how --dhcp-option values are stored. Instead of
storing them directly in tuntap_options, they are now stored in
dns_options->from_dhcp.

Before connect, we save options before --pull is applied, and for that
we call clone_dns_options(). However, this was missing to clone the
"from_dhcp" struct, and as a result, the values of --dhcp-option from
the local config have been lost.

Fix by adding shallow-copying of dhcp_options to clone_dns_options(). It
is safe to do because it only contains fixed-size arrays, scalar types
and pointers to the strings which this struct doesn't own.

Github: closes OpenVPN/openvpn#839
Github: closes OpenVPN/openvpn#840

Change-Id: I815e68dd5d365743faff2b80783b776d9e8a645c
Signed-off-by: Lev Stipakov <lev@openvpn.net>
Acked-by: Frank Lichtenheld <frank@lichtenheld.com>
Message-Id: <20250912132235.44304-1-frank@lichtenheld.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg32879.html
URL: https://gerrit.openvpn.net/c/openvpn/+/1181
Signed-off-by: Gert Doering <gert@greenie.muc.de>