Hi,
I tested this patch and it does make --data-ciphers and
--data-ciphers-fallback behave in their intended "fashion".
Unfortunately, the commit message is grammatically incorrect and also
logically misleading.
The intended fashion is for --data-ciphers to recognise that the correct
cipher *has* been chosen and use it accordingly.
And for --data-ciphers-fallback to *not*
be used in situations other than no OCC cipher.
Reported-by: Richard Bonhomme <tincantek...@gmail.com>
Tested-by: Richard Bonhomme <tincantek...@gmail.com>
On 14/08/2020 09:06, Arne Schwabe wrote:
OpenVPN 2.5 clients do not correctly do a fallback to the server server.
This commit fixes that logic and also fixes --data-ciphers-fallback to
be used in situations other than no OCC cipher.
To reproduce the error use a client with only --data-ciphers set against
a server without NCP.
OPTIONS ERROR: failed to negotiate cipher with server.
Add the server's cipher ('AES-256-CBC') to --data-ciphers
(currently 'AES-256-CBC') if you want to connect to this server.
Reported by: Richard Bonhomme <tincantek...@gmail.com>
Signed-off-by: Arne Schwabe <a...@rfc2549.org>
---
src/openvpn/ssl_ncp.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/src/openvpn/ssl_ncp.c b/src/openvpn/ssl_ncp.c
index f522b8f0..c9ab85ce 100644
--- a/src/openvpn/ssl_ncp.c
+++ b/src/openvpn/ssl_ncp.c
@@ -296,13 +296,14 @@ check_pull_client_ncp(struct context *c, const int found)
}
/* If the server did not push a --cipher, we will switch to the
* remote cipher if it is in our ncp-ciphers list */
- bool useremotecipher = tls_poor_mans_ncp(&c->options,
-
c->c2.tls_multi->remote_ciphername);
-
+ if(tls_poor_mans_ncp(&c->options, c->c2.tls_multi->remote_ciphername))
+ {
+ return true;
+ }
/* We could not figure out the peer's cipher but we have fallback
* enabled */
- if (!useremotecipher && c->options.enable_ncp_fallback)
+ if (!c->c2.tls_multi->remote_ciphername && c->options.enable_ncp_fallback)
{
return true;
}
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