Implement machine fingerprint hashing (T-501)

app-win7/platform/windows/machine_hash_windows.go

@@ -0,0 +1,58 @@
+//go:build windows
+
+package windows
+
+import (
+	"errors"
+	"path/filepath"
+
+	"golang.org/x/sys/windows"
+	"golang.org/x/sys/windows/registry"
+)
+
+const machineGUIDRegistryPath = `SOFTWARE\Microsoft\Cryptography`
+
+// MachineHash reads the two required Windows identifiers only for the duration
+// of this call and returns their derived licensing hash.
+func MachineHash() (string, error) {
+	return machineHashFrom(readMachineGUID, readSystemVolumeSerial)
+}
+
+func readMachineGUID() (string, error) {
+	key, err := registry.OpenKey(registry.LOCAL_MACHINE, machineGUIDRegistryPath, registry.QUERY_VALUE)
+	if err != nil {
+		return "", err
+	}
+	defer key.Close()
+
+	value, _, err := key.GetStringValue("MachineGuid")
+	if err != nil {
+		return "", err
+	}
+	return value, nil
+}
+
+func readSystemVolumeSerial() (uint32, error) {
+	windowsDirectory, err := windows.GetWindowsDirectory()
+	if err != nil {
+		return 0, err
+	}
+	volumeName := filepath.VolumeName(windowsDirectory)
+	if len(volumeName) != 2 || volumeName[1] != ':' || !isASCIIAlpha(volumeName[0]) {
+		return 0, errors.New("windows directory is not on a drive volume")
+	}
+
+	root, err := windows.UTF16PtrFromString(volumeName + `\`)
+	if err != nil {
+		return 0, err
+	}
+	var serial uint32
+	if err := windows.GetVolumeInformation(root, nil, 0, &serial, nil, nil, nil, 0); err != nil {
+		return 0, err
+	}
+	return serial, nil
+}
+
+func isASCIIAlpha(character byte) bool {
+	return character >= 'a' && character <= 'z' || character >= 'A' && character <= 'Z'
+}