dco linux: avoid redefining ovpn enums

Starting with Linux kernel version 6.16, a couple of ovpn-related enum
definitions were introduced in the `include/uapi/linux/if_link.h`
header. Redefining them in openvpn when they are already present in the
system headers can lead to conflicts or build issues.

This commit ensures that enum redefinitions are avoided by conditionally
using the existing definitions from the system header when available.

Change-Id: I4fa2d578f9c0a5a8aa24ca1d396102ef2ed9a425
Signed-off-by: Ralf Lici <ralf@mandelbit.com>
Message-Id: <20250623140748.13960-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg31961.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>

diff --git a/src/openvpn/dco_linux.h b/src/openvpn/dco_linux.h
index 273a6ada1291d2f281597c35612d3036c9ad27fe..4e441ec774904bde3ce1efa85c263cce684782b1 100644 (file)
--- a/src/openvpn/dco_linux.h
+++ b/src/openvpn/dco_linux.h
@@ -40,6 +40,8 @@ typedef enum ovpn_cipher_alg dco_cipher_t;
 
 /* OVPN section */
 
+#ifndef IFLA_OVPN_MAX
+
 enum ovpn_mode {
     OVPN_MODE_P2P,
     OVPN_MODE_MP,
@@ -49,10 +51,13 @@ enum ovpn_ifla_attrs {
     IFLA_OVPN_UNSPEC = 0,
     IFLA_OVPN_MODE,
 
-    __IFLA_OVPN_AFTER_LAST,
-    IFLA_OVPN_MAX = __IFLA_OVPN_AFTER_LAST - 1,
+    __IFLA_OVPN_MAX,
 };
 
+#define IFLA_OVPN_MAX (__IFLA_OVPN_MAX - 1)
+
+#endif /* ifndef IFLA_OVPN_MAX */
+
 typedef struct
 {
     struct nl_sock *nl_sock;