136 lines
4.1 KiB
Go
136 lines
4.1 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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// Package tsd (short for "Tailscale Daemon") contains a System type that
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// containing all the subsystems a Tailscale node (tailscaled or platform
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// equivalent) uses.
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//
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// The goal of this package (as of 2023-05-03) is to eventually unify
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// initialization across tailscaled, tailscaled as a Windows services, the mac
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// GUI, tsnet, wasm, tests, and other places that wire up all the subsystems.
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// And doing so without weird optional interface accessors on some subsystems
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// that return other subsystems. It's all a work in progress.
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//
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// This package depends on nearly all parts of Tailscale, so it should not be
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// imported by (or thus passed to) any package that does not want to depend on
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// the world. In practice this means that only things like cmd/tailscaled,
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// ipn/ipnlocal, and ipn/ipnserver should import this package.
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package tsd
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import (
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"fmt"
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"reflect"
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"tailscale.com/ipn"
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"tailscale.com/net/dns"
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"tailscale.com/net/netmon"
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"tailscale.com/net/tsdial"
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"tailscale.com/net/tstun"
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"tailscale.com/wgengine"
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"tailscale.com/wgengine/magicsock"
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"tailscale.com/wgengine/router"
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)
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// System contains all the subsystems of a Tailscale node (tailscaled, etc.)
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type System struct {
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Dialer SubSystem[*tsdial.Dialer]
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DNSManager SubSystem[*dns.Manager] // can get its *resolver.Resolver from DNSManager.Resolver
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Engine SubSystem[wgengine.Engine]
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NetMon SubSystem[*netmon.Monitor]
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MagicSock SubSystem[*magicsock.Conn]
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NetstackRouter SubSystem[bool] // using Netstack at all (either entirely or at least for subnets)
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Router SubSystem[router.Router]
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Tun SubSystem[*tstun.Wrapper]
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StateStore SubSystem[ipn.StateStore]
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}
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// Set is a convenience method to set a subsystem value.
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// It panics if the type is unknown or has that type
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// has already been set.
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func (s *System) Set(v any) {
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switch v := v.(type) {
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case *netmon.Monitor:
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s.NetMon.Set(v)
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case *dns.Manager:
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s.DNSManager.Set(v)
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case *tsdial.Dialer:
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s.Dialer.Set(v)
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case wgengine.Engine:
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s.Engine.Set(v)
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case router.Router:
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s.Router.Set(v)
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case *tstun.Wrapper:
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s.Tun.Set(v)
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case *magicsock.Conn:
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s.MagicSock.Set(v)
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case ipn.StateStore:
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s.StateStore.Set(v)
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default:
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panic(fmt.Sprintf("unknown type %T", v))
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}
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}
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// IsNetstackRouter reports whether Tailscale is either fully netstack based
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// (without TUN) or is at least using netstack for routing.
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func (s *System) IsNetstackRouter() bool {
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if v, ok := s.NetstackRouter.GetOK(); ok && v {
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return true
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}
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return s.IsNetstack()
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}
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// IsNetstack reports whether Tailscale is running as a netstack-based TUN-free engine.
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func (s *System) IsNetstack() bool {
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name, _ := s.Tun.Get().Name()
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return name == tstun.FakeTUNName
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}
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// SubSystem represents some subsystem of the Tailscale node daemon.
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//
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// A subsystem can be set to a value, and then later retrieved. A subsystem
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// value tracks whether it's been set and, once set, doesn't allow the value to
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// change.
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type SubSystem[T any] struct {
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set bool
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v T
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}
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// Set sets p to v.
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//
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// It panics if p is already set to a different value.
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//
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// Set must not be called concurrently with other Sets or Gets.
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func (p *SubSystem[T]) Set(v T) {
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if p.set {
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var oldVal any = p.v
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var newVal any = v
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if oldVal == newVal {
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// Allow setting to the same value.
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// Note we had to box them through "any" to force them to be comparable.
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// We can't set the type constraint T to be "comparable" because the interfaces
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// aren't comparable. (See https://github.com/golang/go/issues/52531 and
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// https://github.com/golang/go/issues/52614 for some background)
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return
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}
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var z *T
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panic(fmt.Sprintf("%v is already set", reflect.TypeOf(z).Elem().String()))
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}
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p.v = v
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p.set = true
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}
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// Get returns the value of p, panicking if it hasn't been set.
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func (p *SubSystem[T]) Get() T {
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if !p.set {
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var z *T
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panic(fmt.Sprintf("%v is not set", reflect.TypeOf(z).Elem().String()))
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}
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return p.v
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}
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// GetOK returns the value of p (if any) and whether it's been set.
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func (p *SubSystem[T]) GetOK() (_ T, ok bool) {
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return p.v, p.set
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}
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