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95470c3448
It's only use to skip some optional initialization during cleanup, but that work is very minor anyway, and about to change drastically. Signed-off-by: David Anderson <danderson@tailscale.com>
103 lines
2.5 KiB
Go
103 lines
2.5 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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type managerImpl interface {
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// Up updates system DNS settings to match the given configuration.
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Up(Config) error
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// Down undoes the effects of Up.
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// It is idempotent and performs no action if Up has never been called.
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Down() error
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}
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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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impl managerImpl
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config Config
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mconfig ManagerConfig
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}
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// NewManagers created a new manager from the given config.
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func NewManager(mconfig ManagerConfig) *Manager {
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mconfig.Logf = logger.WithPrefix(mconfig.Logf, "dns: ")
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m := &Manager{
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logf: mconfig.Logf,
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impl: newManager(mconfig),
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mconfig: mconfig,
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}
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m.logf("using %T", m.impl)
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return m
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}
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func (m *Manager) Set(config Config) 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.impl.Down()
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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.impl.Up(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.impl.Up(m.config)
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}
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func (m *Manager) Down() error {
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return m.impl.Down()
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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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mconfig := ManagerConfig{
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Logf: logf,
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InterfaceName: interfaceName,
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}
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dns := NewManager(mconfig)
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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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