tailscale/tsd/tsd.go

136 lines
4.1 KiB
Go

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