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[Openvpn-devel,S] Change in openvpn[master]: Use a more robust way to get dco-win version

Message ID d3686dbfd1dc7146290ba833711675f3b974a97c-HTML@gerrit.openvpn.net
State Superseded
Headers show
Series [Openvpn-devel,S] Change in openvpn[master]: Use a more robust way to get dco-win version | expand

Commit Message

plaisthos (Code Review) Aug. 9, 2024, 12:03 p.m. UTC 
Attention is currently required from: flichtenheld, plaisthos.

Hello plaisthos, flichtenheld,

I'd like you to do a code review.
Please visit

    http://gerrit.openvpn.net/c/openvpn/+/723?usp=email

to review the following change.


Change subject: Use a more robust way to get dco-win version
......................................................................

Use a more robust way to get dco-win version

The current way doesn't work if the device is already in use.

Starting from 1.3.0, dco-win creates a non-exclusive
control device \\.\ovpn-dco-ver which can be opened by
multiple apps and supports a single IOCTL to get
a version number.

https://github.com/OpenVPN/ovpn-dco-win/pull/76

This will be expecially handy later when checking which
features driver supports.

Change-Id: Ieb6f3a9d14d76000c1caf8ee1e959c6d0de832bf
Signed-off-by: Lev Stipakov <lev@openvpn.net>
---
M src/openvpn/dco_win.c
1 file changed, 10 insertions(+), 3 deletions(-)



  git pull ssh://gerrit.openvpn.net:29418/openvpn refs/changes/23/723/1
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Patch

diff --git a/src/openvpn/dco_win.c b/src/openvpn/dco_win.c
index e3ada76..3ec946f 100644
--- a/src/openvpn/dco_win.c
+++ b/src/openvpn/dco_win.c
@@ -389,9 +389,16 @@ 
     OVPN_VERSION version;
     ZeroMemory(&version, sizeof(OVPN_VERSION));
 
-    /* try to open device by symbolic name */
-    HANDLE h = CreateFile("\\\\.\\ovpn-dco", GENERIC_READ | GENERIC_WRITE,
-                          0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_SYSTEM | FILE_FLAG_OVERLAPPED, NULL);
+    /* first, try a non-exclusive control device, available from 1.3.0 */
+    HANDLE h = CreateFile("\\\\.\\ovpn-dco-ver", GENERIC_READ,
+                          0, NULL, OPEN_EXISTING, 0, NULL);
+
+    if (h == INVALID_HANDLE_VALUE)
+    {
+        /* fallback to a "normal" device, this will fail if device is already in use */
+        h = CreateFile("\\\\.\\ovpn-dco", GENERIC_READ,
+                       0, NULL, OPEN_EXISTING, 0, NULL);
+    }
 
     if (h == INVALID_HANDLE_VALUE)
     {