openvpn: fix build with linux-headers 6.16

pkgs/tools/networking/openvpn/dco.patch

@@ -0,0 +1,25 @@
+diff --git a/src/openvpn/ovpn_dco_linux.h b/src/openvpn/ovpn_dco_linux.h
+index 73e19b5..46c2786 100644
+--- a/src/openvpn/ovpn_dco_linux.h
++++ b/src/openvpn/ovpn_dco_linux.h
+@@ -237,20 +237,4 @@ enum ovpn_netlink_packet_attrs {
+ 	OVPN_PACKET_ATTR_MAX = __OVPN_PACKET_ATTR_AFTER_LAST - 1,
+ };
+ 
+-enum ovpn_ifla_attrs {
+-	IFLA_OVPN_UNSPEC = 0,
+-	IFLA_OVPN_MODE,
+-
+-	__IFLA_OVPN_AFTER_LAST,
+-	IFLA_OVPN_MAX = __IFLA_OVPN_AFTER_LAST - 1,
+-};
+-
+-enum ovpn_mode {
+-	__OVPN_MODE_FIRST = 0,
+-	OVPN_MODE_P2P = __OVPN_MODE_FIRST,
+-	OVPN_MODE_MP,
+-
+-	__OVPN_MODE_AFTER_LAST,
+-};
+-
+ #endif /* _UAPI_LINUX_OVPN_DCO_H_ */

pkgs/tools/networking/openvpn/default.nix

@@ -30,6 +30,13 @@ stdenv.mkDerivation (finalAttrs: {
     hash = "sha256-nramYYNS+ee3canTiuFjG17f7tbUAjPiQ+YC3fIZXno=";
   };
 
+  # Effectively a backport of https://github.com/OpenVPN/openvpn/commit/1d3c2b67a73a0aa011c13e62f876d24e49d41df0
+  # to fix build on linux-headers 6.16.
+  # FIXME: remove in next update
+  patches = [
+    ./dco.patch
+  ];
+
   nativeBuildInputs = [
     pkg-config
   ]