Good find.
I tested this as instructed in gerrit, also enabling the #if 0 debug code -
this is a p2p setup with --topology subnet, to actually have a subnet to
check against.
Test 1, "--local" in the "--ifconfig" subnet:
2024-09-17 11:25:45 CHECK_ADDR_CLASH type=2 public=10.204.8.7 local=10.204.8.2,
remote_netmask=255.255.255.0
2024-09-17 11:25:45 WARNING: potential conflict between --local address
[10.204.8.7] and --ifconfig address pair [10.204.8.2, 255.255.255.0] -- this is
a warning only that is triggered when local/remote addresses exist within the
same /24 subnet as --ifconfig endpoints. (silence this warning with
--ifconfig-nowarn)
"works".
Test 2, "--remote" in the "--ifconfig" subnet:
2024-09-17 11:27:03 CHECK_ADDR_CLASH type=2 public=10.204.8.8 local=10.204.8.2,
remote_netmask=255.255.255.0
2024-09-17 11:27:03 WARNING: potential conflict between --remote address
[10.204.8.8] and --ifconfig address pair [10.204.8.2, 255.255.255.0] -- this is
a warning only that is triggered when local/remote addresses exist within the
same /24 subnet as --ifconfig endpoints. (silence this warning with
--ifconfig-nowarn)
Test 3, no "--topology subnet":
2024-09-17 11:36:28 CHECK_ADDR_CLASH type=2 public=10.204.8.250
local=10.204.8.2, remote_netmask=10.204.8.1
2024-09-17 11:36:28 WARNING: potential conflict between --local address
[10.204.8.250] and --ifconfig address pair [10.204.8.2, 10.204.8.1] -- this is
a warning only that is triggered when local/remote addresses exist within the
same /24 subnet as --ifconfig endpoints. (silence this warning with
--ifconfig-nowarn)
2024-09-17 11:36:28 CHECK_ADDR_CLASH type=2 public=10.204.8.220
local=10.204.8.2, remote_netmask=10.204.8.1
2024-09-17 11:36:28 WARNING: potential conflict between --remote address
[10.204.8.220] and --ifconfig address pair [10.204.8.2, 10.204.8.1] -- this is
a warning only that is triggered when local/remote addresses exist within the
same /24 subnet as --ifconfig endpoints. (silence this warning with
--ifconfig-nowarn)
.. it "works as designed", but does raise questions... see below.
So, while this patch is actually fixing the first problem with this
code, I have some ideas how to improve things further ;-)
- the line wrapping "one function argument per line" is not how we do
things today, so a future (master-only) patch could improve that
- the check as implemented today checks "within the same /24", so if
I do "--ifconfig 10.204.8.2 255.255.255.128 --remote 10.204.8.220"
(which is perfectly sane) I get
2024-09-17 11:30:44 CHECK_ADDR_CLASH type=2 public=10.204.8.220
local=10.204.8.2, remote_netmask=255.255.255.128
2024-09-17 11:30:44 WARNING: potential conflict between --remote address
[10.204.8.220] and --ifconfig address pair [10.204.8.2, 255.255.255.128] --
this is a warning only that is triggered when local/remote addresses exist
within the same /24 subnet as --ifconfig endpoints. (silence this warning with
--ifconfig-nowarn)
... which is not making any sense. Computers can do math, AND the
code actually knows the netmask there, but uses /24 always
(the TAP check code actually uses the netmask...).
So I think this code needs to be taught about "--topology subnet",
and only does the /24 heuristic for p2p/net30 (if at all).
Your patch has been applied to the master and release/26 branch
(bugfix).
commit 7d345b19e20f30cb2ecbea71682b5a41e6cff454 (master)
commit 7e6723aa7096bee80eb42a473fbfde7de4362b0f (release/2.6)
Author: Ralf Lici
Date: Tue Sep 17 11:14:33 2024 +0200
Fix check_addr_clash argument order
Signed-off-by: Ralf Lici <r...@mandelbit.com>
Acked-by: Frank Lichtenheld <fr...@lichtenheld.com>
Message-Id: <20240917091433.24092-1-g...@greenie.muc.de>
URL:
https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg29261.html
Signed-off-by: Gert Doering <g...@greenie.muc.de>
--
kind regards,
Gert Doering
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