[client] Use static requested GUID when creating Windows interface (#2479)

RequestedGUID is the GUID of the created network adapter, which then influences NLA generation deterministically.

With this change, NetBird should not generate multiple interfaces in every restart on Windows.

client/internal/engine_test.go

@@ -13,6 +13,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/google/uuid"
 	"github.com/pion/transport/v3/stdnet"
 	log "github.com/sirupsen/logrus"
 	"github.com/stretchr/testify/assert"
@@ -845,6 +846,8 @@ func TestEngine_MultiplePeers(t *testing.T) {
 			engine.dnsServer = &dns.MockServer{}
 			mu.Lock()
 			defer mu.Unlock()
+			guid := fmt.Sprintf("{%s}", uuid.New().String())
+			iface.CustomWindowsGUIDString = strings.ToLower(guid)
 			err = engine.Start()
 			if err != nil {
 				t.Errorf("unable to start engine for peer %d with error %v", j, err)

iface/iface_test.go

@@ -4,9 +4,11 @@ import (
 	"fmt"
 	"net"
 	"net/netip"
+	"strings"
 	"testing"
 	"time"
 
+	"github.com/google/uuid"
 	"github.com/pion/transport/v3/stdnet"
 	log "github.com/sirupsen/logrus"
 	"github.com/stretchr/testify/assert"
@@ -345,6 +347,9 @@ func Test_ConnectPeers(t *testing.T) {
 		t.Fatal(err)
 	}
 
+	guid := fmt.Sprintf("{%s}", uuid.New().String())
+	CustomWindowsGUIDString = strings.ToLower(guid)
+
 	iface1, err := NewWGIFace(peer1ifaceName, peer1wgIP, peer1wgPort, peer1Key.String(), DefaultMTU, newNet, nil, nil)
 	if err != nil {
 		t.Fatal(err)
@@ -364,6 +369,9 @@ func Test_ConnectPeers(t *testing.T) {
 		t.Fatal(err)
 	}
 
+	guid = fmt.Sprintf("{%s}", uuid.New().String())
+	CustomWindowsGUIDString = strings.ToLower(guid)
+
 	newNet, err = stdnet.NewNet()
 	if err != nil {
 		t.Fatal(err)

iface/tun.go

@@ -7,6 +7,9 @@ import (
 	"github.com/netbirdio/netbird/iface/bind"
 )
 
+// CustomWindowsGUIDString is a custom GUID string for the interface
+var CustomWindowsGUIDString string
+
 type wgTunDevice interface {
 	Create() (wgConfigurer, error)
 	Up() (*bind.UniversalUDPMuxDefault, error)

iface/tun_windows.go

@@ -14,6 +14,8 @@ import (
 	"github.com/netbirdio/netbird/iface/bind"
 )
 
+const defaultWindowsGUIDSTring = "{f2f29e61-d91f-4d76-8151-119b20c4bdeb}"
+
 type tunDevice struct {
 	name    string
 	address WGAddress
@@ -40,9 +42,22 @@ func newTunDevice(name string, address WGAddress, port int, key string, mtu int,
 	}
 }
 
+func getGUID() (windows.GUID, error) {
+	guidString := defaultWindowsGUIDSTring
+	if CustomWindowsGUIDString != "" {
+		guidString = CustomWindowsGUIDString
+	}
+	return windows.GUIDFromString(guidString)
+}
+
 func (t *tunDevice) Create() (wgConfigurer, error) {
+	guid, err := getGUID()
+	if err != nil {
+		log.Errorf("failed to get GUID: %s", err)
+		return nil, err
+	}
 	log.Info("create tun interface")
-	tunDevice, err := tun.CreateTUN(t.name, t.mtu)
+	tunDevice, err := tun.CreateTUNWithRequestedGUID(t.name, &guid, t.mtu)
 	if err != nil {
 		return nil, err
 	}