mirror of
https://github.com/tailscale/tailscale.git
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90 lines
2.2 KiB
Go
90 lines
2.2 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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"time"
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"tailscale.com/types/logger"
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)
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// We use file-ignore below instead of ignore because on some platforms,
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// the lint exception is necessary and on others it is not,
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// and plain ignore complains if the exception is unnecessary.
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//lint:file-ignore U1000 reconfigTimeout is used on some platforms but not others
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// reconfigTimeout is the time interval within which Manager.{Up,Down} should complete.
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//
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// This is particularly useful because certain conditions can cause indefinite hangs
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// (such as improper dbus auth followed by contextless dbus.Object.Call).
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// Such operations should be wrapped in a timeout context.
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const reconfigTimeout = time.Second
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// Manager manages system DNS settings.
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type Manager struct {
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logf logger.Logf
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os OSConfigurator
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config OSConfig
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}
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// NewManagers created a new manager from the given config.
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func NewManager(logf logger.Logf, oscfg OSConfigurator) *Manager {
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logf = logger.WithPrefix(logf, "dns: ")
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m := &Manager{
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logf: logf,
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os: oscfg,
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}
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m.logf("using %T", m.os)
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return m
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}
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func (m *Manager) Set(config OSConfig) error {
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if config.Equal(m.config) {
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return nil
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}
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m.logf("Set: %+v", config)
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if len(config.Nameservers) == 0 {
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err := m.os.Set(OSConfig{})
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// If we save the config, we will not retry next time. Only do this on success.
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if err == nil {
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m.config = config
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}
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return err
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}
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err := m.os.Set(config)
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// If we save the config, we will not retry next time. Only do this on success.
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if err == nil {
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m.config = config
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}
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return err
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}
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func (m *Manager) Up() error {
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return m.os.Set(m.config)
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}
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func (m *Manager) Down() error {
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return m.os.Close()
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}
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// Cleanup restores the system DNS configuration to its original state
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// in case the Tailscale daemon terminated without closing the router.
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// No other state needs to be instantiated before this runs.
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func Cleanup(logf logger.Logf, interfaceName string) {
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oscfg := NewOSConfigurator(logf, interfaceName)
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dns := NewManager(logf, oscfg)
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if err := dns.Down(); err != nil {
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logf("dns down: %v", err)
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}
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}
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