mirror of https://github.com/tailscale/tailscale/
tsd: add package with System type to unify subsystem init, discovery
This is part of an effort to clean up tailscaled initialization between tailscaled, tailscaled Windows service, tsnet, and the mac GUI. Updates #8036 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>pull/8064/head
Brad Fitzpatrick
1 year ago
committed by
Brad Fitzpatrick
parent
0d7303b798
commit
6e967446e4
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// 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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