wintun: allow retrieving DLL version

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

go.mod

@@ -4,6 +4,6 @@ go 1.17
 
 require (
 	golang.org/x/crypto v0.0.0-20210921155107-089bfa567519
-	golang.org/x/net v0.0.0-20210927181540-4e4d966f7476
+	golang.org/x/net v0.0.0-20211020060615-d418f374d309
-	golang.org/x/sys v0.0.0-20210927094055-39ccf1dd6fa6
+	golang.org/x/sys v0.0.0-20211020174200-9d6173849985
 )

go.sum

@@ -1,13 +1,13 @@
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519 h1:7I4JAnoQBe7ZtJcBaYHi5UtiO8tQHbUSXxL+pnGRANg=
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
 golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
-golang.org/x/net v0.0.0-20210927181540-4e4d966f7476 h1:s5hu7bTnLKswvidgtqc4GwsW83m9LZu8UAqzmWOZtI4=
+golang.org/x/net v0.0.0-20211020060615-d418f374d309 h1:A0lJIi+hcTR6aajJH4YqKWwohY4aW9RO7oRMcdv+HKI=
-golang.org/x/net v0.0.0-20210927181540-4e4d966f7476/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/net v0.0.0-20211020060615-d418f374d309/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20210927094055-39ccf1dd6fa6 h1:foEbQz/B0Oz6YIqu/69kfXPYeFQAuuMYFkjaqXzl5Wo=
+golang.org/x/sys v0.0.0-20211020174200-9d6173849985 h1:LOlKVhfDyahgmqa97awczplwkjzNaELFg3zRIJ13RYo=
-golang.org/x/sys v0.0.0-20210927094055-39ccf1dd6fa6/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20211020174200-9d6173849985/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=

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
+}

tun/wintun/wintun_windows.go

@@ -129,7 +129,7 @@ func Uninstall() (err error) {
 	return
 }
 
-// RunningVersion returns the version of the running Wintun driver.
+// RunningVersion returns the version of the loaded driver.
 func RunningVersion() (version uint32, err error) {
 	r0, _, e1 := syscall.Syscall(procWintunGetRunningDriverVersion.Addr(), 0, 0, 0, 0)
 	version = uint32(r0)