Format Windows error message in Unicode

- We assume that all text passed to the management interface
  and written to log file are in Unicode (UTF-8). This is broken by
  the use of the ANSI version of FormatMessage() for Windows error
  messages. Fix by using FormatMessageW() and converting the UTF-16
  result to UTF-8.

v2: assign return value of FormatMessageW() to DWORD, not int

Github: fixes OpenVPN/openvpn#319

Signed-off-by: Selva Nair <selva.nair@gmail.com>
Acked-by: Frank Lichtenheld <frank@lichtenheld.com>
Message-Id: <20230418141446.1755363-1-selva.nair@gmail.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg26598.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>

diff --git a/src/openvpn/error.c b/src/openvpn/error.c
index a2c9aa4c95afe354bd65f65a09c1dc0f0c85dc2b..9a234e679645c85b6b0130778d55c56ef9147625 100644 (file)
--- a/src/openvpn/error.c
+++ b/src/openvpn/error.c
@@ -970,19 +970,24 @@ strerror_win32(DWORD errnum, struct gc_arena *gc)
 
     /* format a windows error message */
     {
-        char message[256];
+        wchar_t wmessage[256];
+        char *message = NULL;
         struct buffer out = alloc_buf_gc(256, gc);
-        const int status =  FormatMessage(
+        const DWORD status =  FormatMessageW(
             FORMAT_MESSAGE_IGNORE_INSERTS
             | FORMAT_MESSAGE_FROM_SYSTEM
             | FORMAT_MESSAGE_ARGUMENT_ARRAY,
             NULL,
             errnum,
             0,
-            message,
-            sizeof(message),
+            wmessage,
+            SIZE(wmessage),
             NULL);
-        if (!status)
+        if (status)
+        {
+            message = utf16to8(wmessage, gc);
+        }
+        if (!status || !message)
         {
             buf_printf(&out, "[Unknown Win32 Error]");
         }