Extract applyRouteAll helper and reorder package declarations

client/internal/dns/dnsfw/config.go

@@ -21,16 +21,16 @@ const (
 	EnvStrict = "NB_DNS_FIREWALL_STRICT"
 )
 
+// defaultBlockedPorts are the well-known DNS ports we block for non-netbird
+// processes: 53 (plain DNS) and 853 (DNS-over-TLS).
+var defaultBlockedPorts = []uint16{53, 853}
+
 // strictMode reports whether strict mode is enabled via env.
 func strictMode() bool {
 	v, _ := strconv.ParseBool(os.Getenv(EnvStrict))
 	return v
 }
 
-// defaultBlockedPorts are the well-known DNS ports we block for non-netbird
-// processes: 53 (plain DNS) and 853 (DNS-over-TLS).
-var defaultBlockedPorts = []uint16{53, 853}
-
 // blockedPorts returns the effective port list, honoring env overrides.
 // A nil return means the firewall should not be installed.
 func blockedPorts() []uint16 {

client/internal/dns/dnsfw/dnsfw_other.go

@@ -4,12 +4,12 @@ package dnsfw
 
 import "net/netip"
 
-// New returns a no-op manager on non-Windows platforms.
-func New() Manager {
-	return noopManager{}
-}
-
 type noopManager struct{}
 
 func (noopManager) Enable(string, netip.Addr) error { return nil }
 func (noopManager) Disable() error                  { return nil }
+
+// New returns a no-op manager on non-Windows platforms.
+func New() Manager {
+	return noopManager{}
+}

client/internal/dns/dnsfw/dnsfw_windows.go

@@ -13,10 +13,10 @@ import (
 	"golang.org/x/sys/windows"
 )
 
-// New returns a Windows DNS firewall manager backed by WFP.
-func New() Manager {
-	return &windowsManager{}
-}
+var (
+	modIphlpapi                    = windows.NewLazyDLL("iphlpapi.dll")
+	procConvertInterfaceGuidToLuid = modIphlpapi.NewProc("ConvertInterfaceGuidToLuid")
+)
 
 type windowsManager struct {
 	mu sync.Mutex
@@ -80,6 +80,24 @@ func (m *windowsManager) Enable(ifaceGUID string, virtualDNSIP netip.Addr) error
 	return nil
 }
 
+func (m *windowsManager) Disable() error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	return m.disableLocked()
+}
+
+func (m *windowsManager) disableLocked() error {
+	if m.session == 0 {
+		return nil
+	}
+	if err := closeSession(m.session); err != nil {
+		return fmt.Errorf("close wfp session: %w", err)
+	}
+	m.session = 0
+	log.Info("dns firewall removed")
+	return nil
+}
+
 // failOrLog returns err unchanged in strict mode. In non-strict mode the
 // error is logged and nil is returned.
 func (m *windowsManager) failOrLog(strict bool, err error) error {
@@ -90,6 +108,11 @@ func (m *windowsManager) failOrLog(strict bool, err error) error {
 	return nil
 }
 
+// New returns a Windows DNS firewall manager backed by WFP.
+func New() Manager {
+	return &windowsManager{}
+}
+
 // luidFromGUID converts a Windows interface GUID string to its LUID.
 func luidFromGUID(ifaceGUID string) (luid uint64, err error) {
 	defer func() {
@@ -111,26 +134,3 @@ func luidFromGUID(ifaceGUID string) (luid uint64, err error) {
 	}
 	return luid, nil
 }
-
-var (
-	modIphlpapi                    = windows.NewLazyDLL("iphlpapi.dll")
-	procConvertInterfaceGuidToLuid = modIphlpapi.NewProc("ConvertInterfaceGuidToLuid")
-)
-
-func (m *windowsManager) Disable() error {
-	m.mu.Lock()
-	defer m.mu.Unlock()
-	return m.disableLocked()
-}
-
-func (m *windowsManager) disableLocked() error {
-	if m.session == 0 {
-		return nil
-	}
-	if err := closeSession(m.session); err != nil {
-		return fmt.Errorf("close wfp session: %w", err)
-	}
-	m.session = 0
-	log.Info("dns firewall removed")
-	return nil
-}

client/internal/dns/host_windows.go

@@ -172,24 +172,8 @@ func (r *registryConfigurator) disableWINSForInterface() error {
 }
 
 func (r *registryConfigurator) applyDNSConfig(config HostDNSConfig, stateManager *statemanager.Manager) error {
-	if config.RouteAll {
-		if err := r.dnsFirewall.Enable(r.guid, config.ServerIP); err != nil {
-			return fmt.Errorf("dns firewall: %w", err)
-		}
-		if err := r.addDNSSetupForAll(config.ServerIP); err != nil {
-			return fmt.Errorf("add dns setup: %w", err)
-		}
-	} else {
-		if err := r.dnsFirewall.Disable(); err != nil {
-			log.Errorf("disable dns firewall: %v", err)
-		}
-		if r.routingAll {
-			if err := r.deleteInterfaceRegistryKeyProperty(interfaceConfigNameServerKey); err != nil {
-				return fmt.Errorf("delete interface registry key property: %w", err)
-			}
-			r.routingAll = false
-			log.Infof("removed %s as main DNS forwarder for this peer", config.ServerIP)
-		}
+	if err := r.applyRouteAll(config); err != nil {
+		return err
 	}
 
 	r.updateState(stateManager)
@@ -231,6 +215,31 @@ func (r *registryConfigurator) applyDNSConfig(config HostDNSConfig, stateManager
 	return nil
 }
 
+func (r *registryConfigurator) applyRouteAll(config HostDNSConfig) error {
+	if config.RouteAll {
+		if err := r.dnsFirewall.Enable(r.guid, config.ServerIP); err != nil {
+			return fmt.Errorf("dns firewall: %w", err)
+		}
+		if err := r.addDNSSetupForAll(config.ServerIP); err != nil {
+			return fmt.Errorf("add dns setup: %w", err)
+		}
+		return nil
+	}
+
+	if err := r.dnsFirewall.Disable(); err != nil {
+		log.Errorf("disable dns firewall: %v", err)
+	}
+	if !r.routingAll {
+		return nil
+	}
+	if err := r.deleteInterfaceRegistryKeyProperty(interfaceConfigNameServerKey); err != nil {
+		return fmt.Errorf("delete interface registry key property: %w", err)
+	}
+	r.routingAll = false
+	log.Infof("removed %s as main DNS forwarder for this peer", config.ServerIP)
+	return nil
+}
+
 func (r *registryConfigurator) updateState(stateManager *statemanager.Manager) {
 	if err := stateManager.UpdateState(&ShutdownState{
 		Guid:           r.guid,