wgengine/router/dns: use wireguard winipcfg package

This change replaces existing DNS setting code with

golang.zx2c4.com/wireguard/windows/tunnel/winipcfg.LUID.SetDNS
and LUID.SetDNSDomain

As suggested by Jason at

https://github.com/tailscale/tailscale/issues/1050#issuecomment-749196854

Updates #1050

Signed-off-by: Alex Brainman <alex.brainman@gmail.com>

cmd/tailscale/depaware.txt

@@ -63,7 +63,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         tailscale.com/paths                                          from tailscale.com/cmd/tailscale/cli
         tailscale.com/portlist                                       from tailscale.com/ipn
         tailscale.com/safesocket                                     from tailscale.com/cmd/tailscale/cli
-     💣 tailscale.com/syncs                                          from tailscale.com/net/interfaces+
+        tailscale.com/syncs                                          from tailscale.com/net/interfaces+
         tailscale.com/tailcfg                                        from tailscale.com/cmd/tailscale/cli+
    W    tailscale.com/tsconst                                        from tailscale.com/net/interfaces
         tailscale.com/types/empty                                    from tailscale.com/control/controlclient+
@@ -119,7 +119,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         golang.org/x/sys/cpu                                         from golang.org/x/crypto/blake2b+
   LD    golang.org/x/sys/unix                                        from github.com/jsimonetti/rtnetlink/internal/unix+
    W    golang.org/x/sys/windows                                     from github.com/apenwarr/fixconsole+
-   W    golang.org/x/sys/windows/registry                            from golang.zx2c4.com/wireguard/windows/tunnel/winipcfg+
+   W    golang.org/x/sys/windows/registry                            from golang.zx2c4.com/wireguard/windows/tunnel/winipcfg
         golang.org/x/text/secure/bidirule                            from golang.org/x/net/idna
         golang.org/x/text/transform                                  from golang.org/x/text/secure/bidirule+
         golang.org/x/text/unicode/bidi                               from golang.org/x/net/idna+
@@ -174,7 +174,8 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         hash/maphash                                                 from go4.org/mem
         html                                                         from tailscale.com/ipn/ipnstate
         io                                                           from bufio+
-        io/ioutil                                                    from crypto/tls+
+        io/fs                                                        from crypto/rand+
+        io/ioutil                                                    from github.com/godbus/dbus/v5+
         log                                                          from expvar+
         math                                                         from compress/flate+
         math/big                                                     from crypto/dsa+

cmd/tailscaled/depaware.txt

@@ -100,7 +100,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/portlist                                       from tailscale.com/ipn
         tailscale.com/safesocket                                     from tailscale.com/ipn/ipnserver
         tailscale.com/smallzstd                                      from tailscale.com/ipn/ipnserver+
-     💣 tailscale.com/syncs                                          from tailscale.com/net/interfaces+
+        tailscale.com/syncs                                          from tailscale.com/net/interfaces+
         tailscale.com/tailcfg                                        from tailscale.com/control/controlclient+
    W    tailscale.com/tsconst                                        from tailscale.com/net/interfaces
         tailscale.com/types/empty                                    from tailscale.com/control/controlclient+
@@ -160,7 +160,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         golang.org/x/sys/cpu                                         from golang.org/x/crypto/blake2b+
   LD    golang.org/x/sys/unix                                        from github.com/jsimonetti/rtnetlink/internal/unix+
    W    golang.org/x/sys/windows                                     from github.com/apenwarr/fixconsole+
-   W    golang.org/x/sys/windows/registry                            from golang.zx2c4.com/wireguard/windows/tunnel/winipcfg+
+   W    golang.org/x/sys/windows/registry                            from golang.zx2c4.com/wireguard/windows/tunnel/winipcfg
         golang.org/x/term                                            from tailscale.com/logpolicy
         golang.org/x/text/secure/bidirule                            from golang.org/x/net/idna
         golang.org/x/text/transform                                  from golang.org/x/text/secure/bidirule+
@@ -215,10 +215,10 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         hash/crc32                                                   from compress/gzip+
         hash/fnv                                                     from tailscale.com/wgengine/magicsock
         hash/maphash                                                 from go4.org/mem
-        html                                                         from html/template+
+        html                                                         from net/http/pprof+
-        html/template                                                from net/http/pprof
         io                                                           from bufio+
-        io/ioutil                                                    from crypto/tls+
+        io/fs                                                        from crypto/rand+
+        io/ioutil                                                    from github.com/godbus/dbus/v5+
         log                                                          from expvar+
         math                                                         from compress/flate+
         math/big                                                     from crypto/dsa+
@@ -253,8 +253,6 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         sync/atomic                                                  from context+
         syscall                                                      from crypto/rand+
         text/tabwriter                                               from runtime/pprof
-        text/template                                                from html/template
-        text/template/parse                                          from html/template+
         time                                                         from compress/gzip+
         unicode                                                      from bytes+
         unicode/utf16                                                from encoding/asn1+

wgengine/router/dns/manager_windows.go

@@ -5,111 +5,57 @@
 package dns
 
 import (
-	"fmt"
+	"net"
-	"os/exec"
-	"strings"
-	"syscall"
-	"time"
 
-	"golang.org/x/sys/windows/registry"
+	"golang.org/x/sys/windows"
+	"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
 	"tailscale.com/types/logger"
 )
 
-const (
-	ipv4RegBase = `SYSTEM\CurrentControlSet\Services\Tcpip\Parameters`
-	ipv6RegBase = `SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters`
-)
-
 type windowsManager struct {
 	logf    logger.Logf
-	guid string
+	luid    winipcfg.LUID
+	initerr error
 }
 
 func newManager(mconfig ManagerConfig) managerImpl {
-	return windowsManager{
+	m := windowsManager{
 		logf: mconfig.Logf,
-		guid: mconfig.InterfaceName,
 	}
-}
+	var guid windows.GUID
-
+	guid, m.initerr = windows.GUIDFromString(mconfig.InterfaceName)
-// keyOpenTimeout is how long we wait for a registry key to
+	if m.initerr != nil {
-// appear. For some reason, registry keys tied to ephemeral interfaces
+		return m
-// can take a long while to appear after interface creation, and we
-// can end up racing with that.
-const keyOpenTimeout = 20 * time.Second
-
-func setRegistryString(path, name, value string) error {
-	key, err := openKeyWait(registry.LOCAL_MACHINE, path, registry.SET_VALUE, keyOpenTimeout)
-	if err != nil {
-		return fmt.Errorf("opening %s: %w", path, err)
 	}
-	defer key.Close()
+	m.luid, m.initerr = winipcfg.LUIDFromGUID(&guid)
-
+	return m
-	err = key.SetStringValue(name, value)
-	if err != nil {
-		return fmt.Errorf("setting %s[%s]: %w", path, name, err)
-	}
-	return nil
-}
-
-func (m windowsManager) setNameservers(basePath string, nameservers []string) error {
-	path := fmt.Sprintf(`%s\Interfaces\%s`, basePath, m.guid)
-	value := strings.Join(nameservers, ",")
-	return setRegistryString(path, "NameServer", value)
-}
-
-func (m windowsManager) setDomains(basePath string, domains []string) error {
-	path := fmt.Sprintf(`%s\Interfaces\%s`, basePath, m.guid)
-	value := strings.Join(domains, ",")
-	return setRegistryString(path, "SearchList", value)
 }
 
 func (m windowsManager) Up(config Config) error {
-	var ipsv4 []string
+	if m.initerr != nil {
-	var ipsv6 []string
+		return m.initerr
+	}
 
+	var ips []net.IP
 	for _, ip := range config.Nameservers {
-		if ip.Is4() {
+		ips = append(ips, ip.IPAddr().IP)
-			ipsv4 = append(ipsv4, ip.String())
-		} else {
-			ipsv6 = append(ipsv6, ip.String())
 	}
-	}
+	err := m.luid.SetDNS(ips)
-
+	if err != nil {
-	if err := m.setNameservers(ipv4RegBase, ipsv4); err != nil {
-		return err
-	}
-	if err := m.setDomains(ipv4RegBase, config.Domains); err != nil {
 		return err
 	}
 
-	if err := m.setNameservers(ipv6RegBase, ipsv6); err != nil {
+	dnsSearch := ""
-		return err
+	if len(config.Domains) > 0 {
+		dnsSearch = config.Domains[0]
 	}
-	if err := m.setDomains(ipv6RegBase, config.Domains); err != nil {
+	err = m.luid.SetDNSDomain(dnsSearch)
-		return err
+	if err != nil {
+		return nil
 	}
-
+	if len(config.Domains) > 1 {
-	// Force DNS re-registration in Active Directory. What we actually
+		m.logf("%d DNS search domains were specified, but only one is supported, so the first one (%s) was used.", len(config.Domains), dnsSearch)
-	// care about is that this command invokes the undocumented hidden
-	// function that forces Windows to notice that adapter settings
-	// have changed, which makes the DNS settings actually take
-	// effect.
-	//
-	// This command can take a few seconds to run, so run it async, best effort.
-	go func() {
-		t0 := time.Now()
-		m.logf("running ipconfig /registerdns ...")
-		cmd := exec.Command("ipconfig", "/registerdns")
-		cmd.SysProcAttr = &syscall.SysProcAttr{HideWindow: true}
-		d := time.Since(t0).Round(time.Millisecond)
-		if err := cmd.Run(); err != nil {
-			m.logf("error running ipconfig /registerdns after %v: %v", d, err)
-		} else {
-			m.logf("ran ipconfig /registerdns in %v", d)
 	}
-	}()
-
 	return nil
 }
 

wgengine/router/dns/registry_windows.go

@@ -1,76 +0,0 @@
-// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-//
-// The code in this file originates from https://git.zx2c4.com/wireguard-go:
-// Copyright (C) 2017-2020 WireGuard LLC. All Rights Reserved.
-// Copying license: https://git.zx2c4.com/wireguard-go/tree/COPYING
-
-package dns
-
-import (
-	"fmt"
-	"runtime"
-	"strings"
-	"time"
-
-	"golang.org/x/sys/windows"
-	"golang.org/x/sys/windows/registry"
-)
-
-func openKeyWait(k registry.Key, path string, access uint32, timeout time.Duration) (registry.Key, error) {
-	runtime.LockOSThread()
-	defer runtime.UnlockOSThread()
-
-	deadline := time.Now().Add(timeout)
-	pathSpl := strings.Split(path, "\\")
-	for i := 0; ; i++ {
-		keyName := pathSpl[i]
-		isLast := i+1 == len(pathSpl)
-
-		event, err := windows.CreateEvent(nil, 0, 0, nil)
-		if err != nil {
-			return 0, fmt.Errorf("windows.CreateEvent: %v", err)
-		}
-		defer windows.CloseHandle(event)
-
-		var key registry.Key
-		for {
-			err = windows.RegNotifyChangeKeyValue(windows.Handle(k), false, windows.REG_NOTIFY_CHANGE_NAME, event, true)
-			if err != nil {
-				return 0, fmt.Errorf("windows.RegNotifyChangeKeyValue: %v", err)
-			}
-
-			var accessFlags uint32
-			if isLast {
-				accessFlags = access
-			} else {
-				accessFlags = registry.NOTIFY
-			}
-			key, err = registry.OpenKey(k, keyName, accessFlags)
-			if err == windows.ERROR_FILE_NOT_FOUND || err == windows.ERROR_PATH_NOT_FOUND {
-				timeout := time.Until(deadline) / time.Millisecond
-				if timeout < 0 {
-					timeout = 0
-				}
-				s, err := windows.WaitForSingleObject(event, uint32(timeout))
-				if err != nil {
-					return 0, fmt.Errorf("windows.WaitForSingleObject: %v", err)
-				}
-				if s == uint32(windows.WAIT_TIMEOUT) { // windows.WAIT_TIMEOUT status const is misclassified as error in golang.org/x/sys/windows
-					return 0, fmt.Errorf("timeout waiting for registry key")
-				}
-			} else if err != nil {
-				return 0, fmt.Errorf("registry.OpenKey(%v): %v", path, err)
-			} else {
-				if isLast {
-					return key, nil
-				}
-				defer key.Close()
-				break
-			}
-		}
-
-		k = key
-	}
-}