Refactor

dns/override/dns_override_darwin.go

@@ -11,6 +11,8 @@ import (
 	platform "github.com/fosrl/olm/dns/platform"
 )
 
+var configurator platform.DNSConfigurator
+
 // SetupDNSOverride configures the system DNS to use the DNS proxy on macOS
 // Uses scutil for DNS configuration
 func SetupDNSOverride(interfaceName string, dnsProxy *dns.DNSProxy) error {

dns/override/dns_override_unix.go

@@ -11,6 +11,8 @@ import (
 	platform "github.com/fosrl/olm/dns/platform"
 )
 
+var configurator platform.DNSConfigurator
+
 // SetupDNSOverride configures the system DNS to use the DNS proxy on Linux/FreeBSD
 // Tries systemd-resolved, NetworkManager, resolvconf, or falls back to /etc/resolv.conf
 func SetupDNSOverride(interfaceName string, dnsProxy *dns.DNSProxy) error {

dns/override/dns_override_windows.go

@@ -11,6 +11,8 @@ import (
 	platform "github.com/fosrl/olm/dns/platform"
 )
 
+var configurator platform.DNSConfigurator
+
 // SetupDNSOverride configures the system DNS to use the DNS proxy on Windows
 // Uses registry-based configuration (automatically extracts interface GUID)
 func SetupDNSOverride(interfaceName string, dnsProxy *dns.DNSProxy) error {
@@ -18,12 +20,8 @@ func SetupDNSOverride(interfaceName string, dnsProxy *dns.DNSProxy) error {
 		return fmt.Errorf("DNS proxy is nil")
 	}
 
-	if tdev == nil {
-		return fmt.Errorf("TUN device is not available")
-	}
-
 	var err error
-	configurator, err = platform.NewWindowsDNSConfigurator(tdev)
+	configurator, err = platform.NewWindowsDNSConfigurator(interfaceName)
 	if err != nil {
 		return fmt.Errorf("failed to create Windows DNS configurator: %w", err)
 	}

dns/platform/windows.go

@@ -6,13 +6,13 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"net"
 	"net/netip"
 	"syscall"
 	"unsafe"
 
 	"golang.org/x/sys/windows"
 	"golang.org/x/sys/windows/registry"
-	"golang.zx2c4.com/wireguard/tun"
 )
 
 var (
@@ -33,13 +33,13 @@ type WindowsDNSConfigurator struct {
 }
 
 // NewWindowsDNSConfigurator creates a new Windows DNS configurator
-// 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")
+// Accepts an interface name and extracts the GUID internally
+func NewWindowsDNSConfigurator(interfaceName string) (*WindowsDNSConfigurator, error) {
+	if interfaceName == "" {
+		return nil, fmt.Errorf("interface name is required")
 	}
 
-	guid, err := getInterfaceGUIDString(tunDevice)
+	guid, err := getInterfaceGUIDString(interfaceName)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get interface GUID: %w", err)
 	}
@@ -268,24 +268,21 @@ func closeKey(closer io.Closer) {
 
 // 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")
+func getInterfaceGUIDString(interfaceName string) (string, error) {
+	if interfaceName == "" {
+		return "", fmt.Errorf("interface name is required")
 	}
 
-	// The wireguard-go Windows TUN device has a LUID() method
-	// We need to use type assertion to access it
-	type nativeTun interface {
-		LUID() uint64
+	iface, err := net.InterfaceByName(interfaceName)
+	if err != nil {
+		return "", fmt.Errorf("failed to get interface %s: %w", interfaceName, err)
 	}
 
-	nativeDev, ok := tunDevice.(nativeTun)
-	if !ok {
-		return "", fmt.Errorf("TUN device does not support LUID retrieval (not a native Windows TUN device)")
+	luid, err := indexToLUID(uint32(iface.Index))
+	if err != nil {
+		return "", fmt.Errorf("failed to convert index to LUID: %w", err)
 	}
 
-	luid := nativeDev.LUID()
-
 	// Convert LUID to GUID using Windows API
 	guid, err := luidToGUID(luid)
 	if err != nil {
@@ -295,6 +292,27 @@ func getInterfaceGUIDString(tunDevice tun.Device) (string, error) {
 	return guid, nil
 }
 
+// indexToLUID converts a Windows interface index to a LUID
+func indexToLUID(index uint32) (uint64, error) {
+	var luid uint64
+
+	// Load the iphlpapi.dll and get the ConvertInterfaceIndexToLuid function
+	iphlpapi := windows.NewLazySystemDLL("iphlpapi.dll")
+	convertInterfaceIndexToLuid := iphlpapi.NewProc("ConvertInterfaceIndexToLuid")
+
+	// Call the Windows API
+	ret, _, err := convertInterfaceIndexToLuid.Call(
+		uintptr(index),
+		uintptr(unsafe.Pointer(&luid)),
+	)
+
+	if ret != 0 {
+		return 0, fmt.Errorf("ConvertInterfaceIndexToLuid failed with code %d: %w", ret, err)
+	}
+
+	return luid, nil
+}
+
 // luidToGUID converts a Windows LUID (Locally Unique Identifier) to a GUID string
 // using the Windows ConvertInterface* APIs
 func luidToGUID(luid uint64) (string, error) {

olm/olm.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
-	"log"
 	"net"
 	"runtime"
 	"strings"
@@ -17,7 +16,7 @@ import (
 	"github.com/fosrl/olm/api"
 	middleDevice "github.com/fosrl/olm/device"
 	"github.com/fosrl/olm/dns"
-	platform "github.com/fosrl/olm/dns/platform"
+	dnsOverride "github.com/fosrl/olm/dns/override"
 	"github.com/fosrl/olm/network"
 	"github.com/fosrl/olm/peermonitor"
 	"github.com/fosrl/olm/websocket"
@@ -93,7 +92,6 @@ var (
 	globalCtx        context.Context
 	stopRegister     func()
 	stopPing         chan struct{}
-	configurator     platform.DNSConfigurator
 )
 
 func Init(ctx context.Context, config GlobalConfig) {
@@ -577,7 +575,7 @@ func StartTunnel(config TunnelConfig) {
 		peerMonitor.Start()
 
 		// Set up DNS override to use our DNS proxy
-		if err := SetupDNSOverride(interfaceName, dnsProxy); err != nil {
+		if err := dnsOverride.SetupDNSOverride(interfaceName, dnsProxy); err != nil {
 			logger.Error("Failed to setup DNS override: %v", err)
 			return
 		}
@@ -1122,13 +1120,13 @@ func Close() {
 		middleDev = nil
 	}
 
-	// Restore original DNS
-	if configurator != nil {
-		fmt.Println("Restoring original DNS servers...")
-		if err := configurator.RestoreDNS(); err != nil {
-			log.Fatalf("Failed to restore DNS: %v", err)
-		}
-	}
+	// // Restore original DNS
+	// if configurator != nil {
+	// 	fmt.Println("Restoring original DNS servers...")
+	// 	if err := configurator.RestoreDNS(); err != nil {
+	// 		log.Fatalf("Failed to restore DNS: %v", err)
+	// 	}
+	// }
 
 	// Stop DNS proxy
 	logger.Debug("Stopping DNS proxy")
@@ -1177,7 +1175,7 @@ func StopTunnel() {
 	Close()
 
 	// Restore original DNS configuration
-	if err := RestoreDNSOverride(); err != nil {
+	if err := dnsOverride.RestoreDNSOverride(); err != nil {
 		logger.Error("Failed to restore DNS: %v", err)
 	}