Reorg working windows

Former-commit-id: ec5d1ef1d1

dns/platform/detect_windows.go

@@ -5,17 +5,17 @@ package dns
 import "fmt"
 
 // DetectBestConfigurator returns the Windows DNS configurator
-// guid is the network interface GUID
-func DetectBestConfigurator(guid string) (DNSConfigurator, error) {
-	if guid == "" {
+// ifaceName should be the network interface GUID on Windows
+func DetectBestConfigurator(ifaceName string) (DNSConfigurator, error) {
+	if ifaceName == "" {
 		return nil, fmt.Errorf("interface GUID is required for Windows")
 	}
-	return NewWindowsDNSConfigurator(guid)
+	return newWindowsDNSConfiguratorFromGUID(ifaceName)
 }
 
 // GetSystemDNS returns the current system DNS servers for the given interface
-func GetSystemDNS(guid string) ([]string, error) {
-	configurator, err := NewWindowsDNSConfigurator(guid)
+func GetSystemDNS(ifaceName string) ([]string, error) {
+	configurator, err := newWindowsDNSConfiguratorFromGUID(ifaceName)
 	if err != nil {
 		return nil, fmt.Errorf("create configurator: %w", err)
 	}

dns/platform/windows.go

@@ -8,8 +8,11 @@ import (
 	"io"
 	"net/netip"
 	"syscall"
+	"unsafe"
 
+	"golang.org/x/sys/windows"
 	"golang.org/x/sys/windows/registry"
+	"golang.zx2c4.com/wireguard/tun"
 )
 
 var (
@@ -30,8 +33,25 @@ type WindowsDNSConfigurator struct {
 }
 
 // NewWindowsDNSConfigurator creates a new Windows DNS configurator
-// guid is the network interface GUID
-func NewWindowsDNSConfigurator(guid string) (*WindowsDNSConfigurator, error) {
+// Accepts a TUN device and extracts the GUID internally
+func NewWindowsDNSConfigurator(tunDevice tun.Device) (*WindowsDNSConfigurator, error) {
+	if tunDevice == nil {
+		return nil, fmt.Errorf("TUN device is required")
+	}
+
+	guid, err := getInterfaceGUIDString(tunDevice)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get interface GUID: %w", err)
+	}
+
+	return &WindowsDNSConfigurator{
+		guid: guid,
+	}, nil
+}
+
+// newWindowsDNSConfiguratorFromGUID creates a configurator from a GUID string
+// This is an internal function for use by DetectBestConfigurator
+func newWindowsDNSConfiguratorFromGUID(guid string) (*WindowsDNSConfigurator, error) {
 	if guid == "" {
 		return nil, fmt.Errorf("interface GUID is required")
 	}
@@ -245,3 +265,61 @@ func closeKey(closer io.Closer) {
 		fmt.Printf("warning: failed to close registry key: %v\n", err)
 	}
 }
+
+// getInterfaceGUIDString retrieves the GUID string for a Windows TUN interface
+// This is required for registry-based DNS configuration on Windows
+func getInterfaceGUIDString(tunDevice tun.Device) (string, error) {
+	if tunDevice == nil {
+		return "", fmt.Errorf("TUN device is nil")
+	}
+
+	// The wireguard-go Windows TUN device has a LUID() method
+	// We need to use type assertion to access it
+	type nativeTun interface {
+		LUID() uint64
+	}
+
+	nativeDev, ok := tunDevice.(nativeTun)
+	if !ok {
+		return "", fmt.Errorf("TUN device does not support LUID retrieval (not a native Windows TUN device)")
+	}
+
+	luid := nativeDev.LUID()
+
+	// Convert LUID to GUID using Windows API
+	guid, err := luidToGUID(luid)
+	if err != nil {
+		return "", fmt.Errorf("failed to convert LUID to GUID: %w", err)
+	}
+
+	return guid, nil
+}
+
+// luidToGUID converts a Windows LUID (Locally Unique Identifier) to a GUID string
+// using the Windows ConvertInterface* APIs
+func luidToGUID(luid uint64) (string, error) {
+	var guid windows.GUID
+
+	// Load the iphlpapi.dll and get the ConvertInterfaceLuidToGuid function
+	iphlpapi := windows.NewLazySystemDLL("iphlpapi.dll")
+	convertLuidToGuid := iphlpapi.NewProc("ConvertInterfaceLuidToGuid")
+
+	// Call the Windows API
+	// NET_LUID is a 64-bit value on Windows
+	ret, _, err := convertLuidToGuid.Call(
+		uintptr(unsafe.Pointer(&luid)),
+		uintptr(unsafe.Pointer(&guid)),
+	)
+
+	if ret != 0 {
+		return "", fmt.Errorf("ConvertInterfaceLuidToGuid failed with code %d: %w", ret, err)
+	}
+
+	// Format the GUID as a string with curly braces
+	guidStr := fmt.Sprintf("{%08X-%04X-%04X-%02X%02X-%02X%02X%02X%02X%02X%02X}",
+		guid.Data1, guid.Data2, guid.Data3,
+		guid.Data4[0], guid.Data4[1], guid.Data4[2], guid.Data4[3],
+		guid.Data4[4], guid.Data4[5], guid.Data4[6], guid.Data4[7])
+
+	return guidStr, nil
+}