mirror of https://github.com/tailscale/tailscale/
all: dns refactor, add Proxied and PerDomain flags from control (#615)
Signed-off-by: Dmytro Shynkevych <dmytro@tailscale.com>reviewable/pr630/r1
Dmytro Shynkevych
4 years ago
committed by
GitHub
parent
43b271cb26
commit
28e52a0492
@ -1,74 +0,0 @@
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// 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 router
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import (
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"inet.af/netaddr"
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)
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// DNSConfig is the subset of Config that contains DNS parameters.
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type DNSConfig struct {
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// Nameservers are the IP addresses of the nameservers to use.
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Nameservers []netaddr.IP
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// Domains are the search domains to use.
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Domains []string
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}
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// EquivalentTo determines whether its argument and receiver
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// represent equivalent DNS configurations (then DNS reconfig is a no-op).
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func (lhs DNSConfig) EquivalentTo(rhs DNSConfig) bool {
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if len(lhs.Nameservers) != len(rhs.Nameservers) {
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return false
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}
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if len(lhs.Domains) != len(rhs.Domains) {
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return false
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}
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// With how we perform resolution order shouldn't matter,
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// but it is unlikely that we will encounter different orders.
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for i, server := range lhs.Nameservers {
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if rhs.Nameservers[i] != server {
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return false
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}
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}
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for i, domain := range lhs.Domains {
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if rhs.Domains[i] != domain {
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return false
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}
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}
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return true
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}
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// dnsMode determines how DNS settings are managed.
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type dnsMode uint8
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const (
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// dnsDirect indicates that /etc/resolv.conf is edited directly.
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dnsDirect dnsMode = iota
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// dnsResolvconf indicates that a resolvconf binary is used.
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dnsResolvconf
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// dnsNetworkManager indicates that the NetworkManaer DBus API is used.
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dnsNetworkManager
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// dnsResolved indicates that the systemd-resolved DBus API is used.
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dnsResolved
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)
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func (m dnsMode) String() string {
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switch m {
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case dnsDirect:
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return "direct"
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case dnsResolvconf:
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return "resolvconf"
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case dnsNetworkManager:
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return "networkmanager"
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case dnsResolved:
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return "resolved"
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default:
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return "???"
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}
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}
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@ -0,0 +1,75 @@
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// 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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"inet.af/netaddr"
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"tailscale.com/types/logger"
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)
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// Config is the set of parameters that uniquely determine
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// the state to which a manager should bring system DNS settings.
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type Config struct {
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// Nameservers are the IP addresses of the nameservers to use.
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Nameservers []netaddr.IP
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// Domains are the search domains to use.
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Domains []string
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// PerDomain indicates whether it is preferred to use Nameservers
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// only for DNS queries for subdomains of Domains.
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// Note that Nameservers may still be applied to all queries
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// if the manager does not support per-domain settings.
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PerDomain bool
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// Proxied indicates whether DNS requests are proxied through a tsdns.Resolver.
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Proxied bool
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}
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// Equal determines whether its argument and receiver
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// represent equivalent DNS configurations (then DNS reconfig is a no-op).
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func (lhs Config) Equal(rhs Config) bool {
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if lhs.Proxied != rhs.Proxied || lhs.PerDomain != rhs.PerDomain {
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return false
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}
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if len(lhs.Nameservers) != len(rhs.Nameservers) {
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return false
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}
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if len(lhs.Domains) != len(rhs.Domains) {
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return false
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}
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// With how we perform resolution order shouldn't matter,
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// but it is unlikely that we will encounter different orders.
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for i, server := range lhs.Nameservers {
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if rhs.Nameservers[i] != server {
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return false
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}
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}
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// The order of domains, on the other hand, is significant.
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for i, domain := range lhs.Domains {
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if rhs.Domains[i] != domain {
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return false
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}
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}
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return true
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}
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// ManagerConfig is the set of parameters from which
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// a manager implementation is chosen and initialized.
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type ManagerConfig struct {
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// logf is the logger for the manager to use.
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Logf logger.Logf
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// InterfaceNAme is the name of the interface with which DNS settings should be associated.
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InterfaceName string
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// Cleanup indicates that the manager is created for cleanup only.
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// A no-op manager will be instantiated if the system needs no cleanup.
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Cleanup bool
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// PerDomain indicates that a manager capable of per-domain configuration is preferred.
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// Certain managers are per-domain only; they will not be considered if this is false.
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PerDomain bool
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}
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@ -0,0 +1,94 @@
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// 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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// 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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config: Config{PerDomain: mconfig.PerDomain},
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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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// Switching to and from per-domain mode may require a change of manager.
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if config.PerDomain != m.config.PerDomain {
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if err := m.impl.Down(); err != nil {
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return err
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}
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m.mconfig.PerDomain = config.PerDomain
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m.impl = newManager(m.mconfig)
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m.logf("switched to %T", m.impl)
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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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@ -0,0 +1,14 @@
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// 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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// +build !linux,!freebsd,!openbsd,!windows
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package dns
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func newManager(mconfig ManagerConfig) managerImpl {
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// TODO(dmytro): on darwin, we should use a macOS-specific method such as scutil.
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// This is currently not implemented. Editing /etc/resolv.conf does not work,
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// as most applications use the system resolver, which disregards it.
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return newNoopManager(mconfig)
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}
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@ -0,0 +1,14 @@
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// 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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func newManager(mconfig ManagerConfig) managerImpl {
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switch {
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case isResolvconfActive():
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return newResolvconfManager(mconfig)
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default:
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return newDirectManager(mconfig)
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}
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}
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@ -0,0 +1,27 @@
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// 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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func newManager(mconfig ManagerConfig) managerImpl {
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switch {
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// systemd-resolved should only activate per-domain.
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case isResolvedActive() && mconfig.PerDomain:
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if mconfig.Cleanup {
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return newNoopManager(mconfig)
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} else {
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return newResolvedManager(mconfig)
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}
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case isNMActive():
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if mconfig.Cleanup {
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return newNoopManager(mconfig)
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} else {
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return newNMManager(mconfig)
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}
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case isResolvconfActive():
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return newResolvconfManager(mconfig)
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default:
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return newDirectManager(mconfig)
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}
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}
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@ -0,0 +1,9 @@
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// 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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func newManager(mconfig ManagerConfig) managerImpl {
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return newDirectManager(mconfig)
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}
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@ -0,0 +1,83 @@
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// 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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"strings"
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"github.com/tailscale/wireguard-go/tun"
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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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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 newManager(mconfig ManagerConfig) managerImpl {
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return windowsManager{
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logf: mconfig.Logf,
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guid: tun.WintunGUID,
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}
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}
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func setRegistry(path, nameservers, domains string) error {
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key, err := registry.OpenKey(registry.LOCAL_MACHINE, path, registry.READ|registry.SET_VALUE)
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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("NameServer", nameservers)
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if err != nil {
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return fmt.Errorf("setting %s/NameServer: %w", path, err)
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}
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err = key.SetStringValue("Domain", domains)
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if err != nil {
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return fmt.Errorf("setting %s/Domain: %w", path, err)
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}
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return nil
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}
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func (m windowsManager) Up(config Config) 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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nsv4 := strings.Join(ipsv4, ",")
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nsv6 := strings.Join(ipsv6, ",")
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var domains string
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if len(config.Domains) > 0 {
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if len(config.Domains) > 1 {
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m.logf("only a single search domain is supported")
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}
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domains = config.Domains[0]
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}
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v4Path := `SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\` + m.guid
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if err := setRegistry(v4Path, nsv4, domains); err != nil {
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return err
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}
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v6Path := `SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters\Interfaces\` + m.guid
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if err := setRegistry(v6Path, nsv6, domains); err != nil {
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return err
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}
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return nil
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}
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func (m windowsManager) Down() error {
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return m.Up(Config{Nameservers: nil, Domains: nil})
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}
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@ -0,0 +1,17 @@
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// 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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type noopManager struct{}
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// Up implements managerImpl.
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func (m noopManager) Up(Config) error { return nil }
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// Down implements managerImpl.
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func (m noopManager) Down() error { return nil }
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func newNoopManager(mconfig ManagerConfig) managerImpl {
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return noopManager{}
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}
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