[client] Run registerdns before flushing (#3926)

* Run registerdns before flushing

* Disable WINS, dynamic updates and registration

client/internal/dns/host_windows.go

@@ -1,11 +1,14 @@
 package dns
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"io"
+	"os/exec"
 	"strings"
 	"syscall"
+	"time"
 
 	"github.com/hashicorp/go-multierror"
 	log "github.com/sirupsen/logrus"
@@ -41,6 +44,20 @@ const (
 	interfaceConfigNameServerKey = "NameServer"
 	interfaceConfigSearchListKey = "SearchList"
 
+	// Network interface DNS registration settings
+	disableDynamicUpdateKey           = "DisableDynamicUpdate"
+	registrationEnabledKey            = "RegistrationEnabled"
+	maxNumberOfAddressesToRegisterKey = "MaxNumberOfAddressesToRegister"
+
+	// NetBIOS/WINS settings
+	netbtInterfacePath = `SYSTEM\CurrentControlSet\Services\NetBT\Parameters\Interfaces`
+	netbiosOptionsKey  = "NetbiosOptions"
+
+	// NetBIOS option values: 0 = from DHCP, 1 = enabled, 2 = disabled
+	netbiosFromDHCP = 0
+	netbiosEnabled  = 1
+	netbiosDisabled = 2
+
 	// RP_FORCE: Reapply all policies even if no policy change was detected
 	rpForce = 0x1
 )
@@ -67,16 +84,85 @@ func newHostManager(wgInterface WGIface) (*registryConfigurator, error) {
 		log.Infof("detected GPO DNS policy configuration, using policy store")
 	}
 
-	return &registryConfigurator{
+	configurator := &registryConfigurator{
 		guid: guid,
 		gpo:  useGPO,
-	}, nil
+	}
+
+	if err := configurator.configureInterface(); err != nil {
+		log.Errorf("failed to configure interface settings: %v", err)
+	}
+
+	return configurator, nil
 }
 
 func (r *registryConfigurator) supportCustomPort() bool {
 	return false
 }
 
+func (r *registryConfigurator) configureInterface() error {
+	var merr *multierror.Error
+
+	if err := r.disableDNSRegistrationForInterface(); err != nil {
+		merr = multierror.Append(merr, fmt.Errorf("disable DNS registration: %w", err))
+	}
+
+	if err := r.disableWINSForInterface(); err != nil {
+		merr = multierror.Append(merr, fmt.Errorf("disable WINS: %w", err))
+	}
+
+	return nberrors.FormatErrorOrNil(merr)
+}
+
+func (r *registryConfigurator) disableDNSRegistrationForInterface() error {
+	regKey, err := r.getInterfaceRegistryKey()
+	if err != nil {
+		return fmt.Errorf("get interface registry key: %w", err)
+	}
+	defer closer(regKey)
+
+	var merr *multierror.Error
+
+	if err := regKey.SetDWordValue(disableDynamicUpdateKey, 1); err != nil {
+		merr = multierror.Append(merr, fmt.Errorf("set %s: %w", disableDynamicUpdateKey, err))
+	}
+
+	if err := regKey.SetDWordValue(registrationEnabledKey, 0); err != nil {
+		merr = multierror.Append(merr, fmt.Errorf("set %s: %w", registrationEnabledKey, err))
+	}
+
+	if err := regKey.SetDWordValue(maxNumberOfAddressesToRegisterKey, 0); err != nil {
+		merr = multierror.Append(merr, fmt.Errorf("set %s: %w", maxNumberOfAddressesToRegisterKey, err))
+	}
+
+	if merr == nil || len(merr.Errors) == 0 {
+		log.Infof("disabled DNS registration for interface %s", r.guid)
+	}
+
+	return nberrors.FormatErrorOrNil(merr)
+}
+
+func (r *registryConfigurator) disableWINSForInterface() error {
+	netbtKeyPath := fmt.Sprintf(`%s\Tcpip_%s`, netbtInterfacePath, r.guid)
+
+	regKey, err := registry.OpenKey(registry.LOCAL_MACHINE, netbtKeyPath, registry.SET_VALUE)
+	if err != nil {
+		regKey, _, err = registry.CreateKey(registry.LOCAL_MACHINE, netbtKeyPath, registry.SET_VALUE)
+		if err != nil {
+			return fmt.Errorf("create NetBT interface key %s: %w", netbtKeyPath, err)
+		}
+	}
+	defer closer(regKey)
+
+	// NetbiosOptions: 2 = disabled
+	if err := regKey.SetDWordValue(netbiosOptionsKey, netbiosDisabled); err != nil {
+		return fmt.Errorf("set %s: %w", netbiosOptionsKey, err)
+	}
+
+	log.Infof("disabled WINS/NetBIOS for interface %s", r.guid)
+	return nil
+}
+
 func (r *registryConfigurator) applyDNSConfig(config HostDNSConfig, stateManager *statemanager.Manager) error {
 	if config.RouteAll {
 		if err := r.addDNSSetupForAll(config.ServerIP); err != nil {
@@ -119,9 +205,7 @@ func (r *registryConfigurator) applyDNSConfig(config HostDNSConfig, stateManager
 		return fmt.Errorf("update search domains: %w", err)
 	}
 
-	if err := r.flushDNSCache(); err != nil {
-		log.Errorf("failed to flush DNS cache: %v", err)
-	}
+	go r.flushDNSCache()
 
 	return nil
 }
@@ -191,7 +275,25 @@ func (r *registryConfigurator) string() string {
 	return "registry"
 }
 
-func (r *registryConfigurator) flushDNSCache() error {
+func (r *registryConfigurator) registerDNS() {
+	ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
+	defer cancel()
+
+	// nolint:misspell
+	cmd := exec.CommandContext(ctx, "ipconfig", "/registerdns")
+	out, err := cmd.CombinedOutput()
+
+	if err != nil {
+		log.Errorf("failed to register DNS: %v, output: %s", err, out)
+		return
+	}
+
+	log.Info("registered DNS names")
+}
+
+func (r *registryConfigurator) flushDNSCache() {
+	r.registerDNS()
+
 	// dnsFlushResolverCacheFn.Call() may panic if the func is not found
 	defer func() {
 		if rec := recover(); rec != nil {
@@ -202,13 +304,14 @@ func (r *registryConfigurator) flushDNSCache() error {
 	ret, _, err := dnsFlushResolverCacheFn.Call()
 	if ret == 0 {
 		if err != nil && !errors.Is(err, syscall.Errno(0)) {
-			return fmt.Errorf("DnsFlushResolverCache failed: %w", err)
+			log.Errorf("DnsFlushResolverCache failed: %v", err)
+			return
 		}
-		return fmt.Errorf("DnsFlushResolverCache failed")
+		log.Errorf("DnsFlushResolverCache failed")
+		return
 	}
 
 	log.Info("flushed DNS cache")
-	return nil
 }
 
 func (r *registryConfigurator) updateSearchDomains(domains []string) error {
@@ -263,9 +366,7 @@ func (r *registryConfigurator) restoreHostDNS() error {
 		return fmt.Errorf("remove interface registry key: %w", err)
 	}
 
-	if err := r.flushDNSCache(); err != nil {
-		log.Errorf("failed to flush DNS cache: %v", err)
-	}
+	go r.flushDNSCache()
 
 	return nil
 }