FreeBSD DCO: repair incoming 'delete peer' notifications in p2p client mode

commit 4a48841da2 introduced a workaround for spurious DCO notifications
"with no useful content" on Linux - namely, ignoring dco_message_type==0
in forward.c, process_incoming_dco(), "because Linux has no message
type 0 anyway".

Each DCO platform uses its own enum for these notification messages
*inside* OpenVPN (which might not have the best design decision ever),
and FreeBSD had OVPN_CMD_DEL_PEER in the enum on "position 0"...

Fix by changing the enum to start with 1.  Tested with DEL_PEER in p2p
client and DEL_PEER & FLOAT in p2mp server mode.

v2:
  introduce OVPN_CMD_NO_MESSAGE in position 0, and a comment explaining why.
  A future commit can then clean up forward.c and dco_linux.c to use the
  constant, and not "magic 0 which happens to be in there after CLEAR()".

Github: fixes OpenVPN/openvpn#881

Change-Id: I991d6053776efed771bc1a3880acb80b55959cbc
Signed-off-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Frank Lichtenheld <frank@lichtenheld.com>
Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1353
Message-Id: <20251107141333.12056-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg34237.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>

diff --git a/src/openvpn/dco_freebsd.h b/src/openvpn/dco_freebsd.h
index 0797b823fcce2fb76461ae5531536b9b79ad77d9..5e2a55258a6d4184ebe744eb7ff882099be97bd1 100644 (file)
--- a/src/openvpn/dco_freebsd.h
+++ b/src/openvpn/dco_freebsd.h
@@ -33,6 +33,8 @@ typedef enum ovpn_key_cipher dco_cipher_t;
 
 enum ovpn_message_type_t
 {
+    /* message type #0 is treated as magic number by process_incoming_dco() */
+    OVPN_CMD_NO_MESSAGE = 0,
     OVPN_CMD_DEL_PEER,
     OVPN_CMD_PACKET,
     OVPN_CMD_SWAP_KEYS,