wintun: allow retrieving DLL version

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/tun/wintun/dll_windows.go b/tun/wintun/dll_windows.go
index c96e4a7..3832c1e 100644
--- a/tun/wintun/dll_windows.go
+++ b/tun/wintun/dll_windows.go
@@ -96,3 +96,33 @@ func (d *lazyDLL) Load() error {
 func (p *lazyProc) nameToAddr() (uintptr, error) {
 	return windows.GetProcAddress(p.dll.module, p.Name)
 }
+
+// Version returns the version of the Wintun DLL.
+func Version() string {
+	if modwintun.Load() != nil {
+		return "unknown"
+	}
+	resInfo, err := windows.FindResource(modwintun.module, windows.ResourceID(1), windows.RT_VERSION)
+	if err != nil {
+		return "unknown"
+	}
+	data, err := windows.LoadResourceData(modwintun.module, resInfo)
+	if err != nil {
+		return "unknown"
+	}
+
+	var fixedInfo *windows.VS_FIXEDFILEINFO
+	fixedInfoLen := uint32(unsafe.Sizeof(*fixedInfo))
+	err = windows.VerQueryValue(unsafe.Pointer(&data[0]), `\`, unsafe.Pointer(&fixedInfo), &fixedInfoLen)
+	if err != nil {
+		return "unknown"
+	}
+	version := fmt.Sprintf("%d.%d", (fixedInfo.FileVersionMS>>16)&0xff, (fixedInfo.FileVersionMS>>0)&0xff)
+	if nextNibble := (fixedInfo.FileVersionLS >> 16) & 0xff; nextNibble != 0 {
+		version += fmt.Sprintf(".%d", nextNibble)
+	}
+	if nextNibble := (fixedInfo.FileVersionLS >> 0) & 0xff; nextNibble != 0 {
+		version += fmt.Sprintf(".%d", nextNibble)
+	}
+	return version
+}