mirror of
https://github.com/tailscale/tailscale.git
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123 lines
3.2 KiB
Go
123 lines
3.2 KiB
Go
// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package dns
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import (
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"fmt"
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"os/exec"
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"strings"
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"syscall"
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"time"
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"golang.org/x/sys/windows/registry"
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"tailscale.com/types/logger"
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)
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const (
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ipv4RegBase = `SYSTEM\CurrentControlSet\Services\Tcpip\Parameters`
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ipv6RegBase = `SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters`
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)
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type windowsManager struct {
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logf logger.Logf
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guid string
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}
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func NewOSConfigurator(logf logger.Logf, interfaceName string) OSConfigurator {
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return windowsManager{
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logf: logf,
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guid: interfaceName,
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}
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}
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// keyOpenTimeout is how long we wait for a registry key to
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// appear. For some reason, registry keys tied to ephemeral interfaces
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// can take a long while to appear after interface creation, and we
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// can end up racing with that.
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const keyOpenTimeout = 20 * time.Second
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func setRegistryString(path, name, value string) error {
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key, err := openKeyWait(registry.LOCAL_MACHINE, path, registry.SET_VALUE, keyOpenTimeout)
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if err != nil {
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return fmt.Errorf("opening %s: %w", path, err)
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}
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defer key.Close()
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err = key.SetStringValue(name, value)
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if err != nil {
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return fmt.Errorf("setting %s[%s]: %w", path, name, err)
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}
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return nil
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}
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func (m windowsManager) setNameservers(basePath string, nameservers []string) error {
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path := fmt.Sprintf(`%s\Interfaces\%s`, basePath, m.guid)
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value := strings.Join(nameservers, ",")
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return setRegistryString(path, "NameServer", value)
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}
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func (m windowsManager) setDomains(basePath string, domains []string) error {
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path := fmt.Sprintf(`%s\Interfaces\%s`, basePath, m.guid)
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value := strings.Join(domains, ",")
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return setRegistryString(path, "SearchList", value)
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}
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func (m windowsManager) SetDNS(config OSConfig) error {
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var ipsv4 []string
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var ipsv6 []string
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for _, ip := range config.Nameservers {
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if ip.Is4() {
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ipsv4 = append(ipsv4, ip.String())
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} else {
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ipsv6 = append(ipsv6, ip.String())
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}
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}
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if err := m.setNameservers(ipv4RegBase, ipsv4); err != nil {
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return err
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}
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if err := m.setDomains(ipv4RegBase, config.Domains); err != nil {
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return err
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}
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if err := m.setNameservers(ipv6RegBase, ipsv6); err != nil {
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return err
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}
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if err := m.setDomains(ipv6RegBase, config.Domains); err != nil {
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return err
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}
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// Force DNS re-registration in Active Directory. What we actually
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// care about is that this command invokes the undocumented hidden
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// function that forces Windows to notice that adapter settings
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// have changed, which makes the DNS settings actually take
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// effect.
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//
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// This command can take a few seconds to run, so run it async, best effort.
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go func() {
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t0 := time.Now()
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m.logf("running ipconfig /registerdns ...")
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cmd := exec.Command("ipconfig", "/registerdns")
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cmd.SysProcAttr = &syscall.SysProcAttr{HideWindow: true}
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d := time.Since(t0).Round(time.Millisecond)
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if err := cmd.Run(); err != nil {
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m.logf("error running ipconfig /registerdns after %v: %v", d, err)
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} else {
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m.logf("ran ipconfig /registerdns in %v", d)
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}
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}()
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return nil
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}
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func (m windowsManager) SupportsSplitDNS() bool {
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return false
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}
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func (m windowsManager) Close() error {
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return m.SetDNS(OSConfig{})
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}
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