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>

ipn/ipnlocal/local.go

@@ -60,6 +60,7 @@ import (
 	"tailscale.com/syncs"
 	"tailscale.com/tailcfg"
 	"tailscale.com/tka"
+	"tailscale.com/tsd"
 	"tailscale.com/types/dnstype"
 	"tailscale.com/types/empty"
 	"tailscale.com/types/key"
@@ -137,10 +138,11 @@ type LocalBackend struct {
 	logf                  logger.Logf        // general logging
 	keyLogf               logger.Logf        // for printing list of peers on change
 	statsLogf             logger.Logf        // for printing peers stats on change
-	e                     wgengine.Engine
+	sys                   *tsd.System
+	e                     wgengine.Engine // non-nil; TODO(bradfitz): remove; use sys
 	pm                    *profileManager
-	store                 ipn.StateStore
-	dialer                *tsdial.Dialer // non-nil
+	store                 ipn.StateStore // non-nil; TODO(bradfitz): remove; use sys
+	dialer                *tsdial.Dialer // non-nil; TODO(bradfitz): remove; use sys
 	backendLogID          logid.PublicID
 	unregisterNetMon      func()
 	unregisterHealthWatch func()
@@ -267,10 +269,10 @@ type clientGen func(controlclient.Options) (controlclient.Client, error)
 // but is not actually running.
 //
 // If dialer is nil, a new one is made.
-func NewLocalBackend(logf logger.Logf, logID logid.PublicID, store ipn.StateStore, dialer *tsdial.Dialer, e wgengine.Engine, loginFlags controlclient.LoginFlags) (*LocalBackend, error) {
-	if e == nil {
-		panic("ipn.NewLocalBackend: engine must not be nil")
-	}
+func NewLocalBackend(logf logger.Logf, logID logid.PublicID, sys *tsd.System, loginFlags controlclient.LoginFlags) (*LocalBackend, error) {
+	e := sys.Engine.Get()
+	store := sys.StateStore.Get()
+	dialer := sys.Dialer.Get()
 
 	pm, err := newProfileManager(store, logf)
 	if err != nil {
@@ -301,10 +303,11 @@ func NewLocalBackend(logf logger.Logf, logID logid.PublicID, store ipn.StateStor
 		logf:           logf,
 		keyLogf:        logger.LogOnChange(logf, 5*time.Minute, time.Now),
 		statsLogf:      logger.LogOnChange(logf, 5*time.Minute, time.Now),
+		sys:            sys,
 		e:              e,
-		pm:             pm,
-		store:          store,
 		dialer:         dialer,
+		store:          store,
+		pm:             pm,
 		backendLogID:   logID,
 		state:          ipn.NoState,
 		portpoll:       portpoll,
@@ -313,7 +316,8 @@ func NewLocalBackend(logf logger.Logf, logID logid.PublicID, store ipn.StateStor
 		loginFlags:     loginFlags,
 	}
 
-	b.sockstatLogger, err = sockstatlog.NewLogger(logpolicy.LogsDir(logf), logf, logID, e.GetNetMon())
+	netMon := sys.NetMon.Get()
+	b.sockstatLogger, err = sockstatlog.NewLogger(logpolicy.LogsDir(logf), logf, logID, netMon)
 	if err != nil {
 		log.Printf("error setting up sockstat logger: %v", err)
 	}
@@ -330,7 +334,6 @@ func NewLocalBackend(logf logger.Logf, logID logid.PublicID, store ipn.StateStor
 	b.statusChanged = sync.NewCond(&b.statusLock)
 	b.e.SetStatusCallback(b.setWgengineStatus)
 
-	netMon := e.GetNetMon()
 	b.prevIfState = netMon.InterfaceState()
 	// Call our linkChange code once with the current state, and
 	// then also whenever it changes:
@@ -339,14 +342,9 @@ func NewLocalBackend(logf logger.Logf, logID logid.PublicID, store ipn.StateStor
 
 	b.unregisterHealthWatch = health.RegisterWatcher(b.onHealthChange)
 
-	wiredPeerAPIPort := false
-	if ig, ok := e.(wgengine.InternalsGetter); ok {
-		if tunWrap, _, _, ok := ig.GetInternals(); ok {
-			tunWrap.PeerAPIPort = b.GetPeerAPIPort
-			wiredPeerAPIPort = true
-		}
-	}
-	if !wiredPeerAPIPort {
+	if tunWrap, ok := b.sys.Tun.GetOK(); ok {
+		tunWrap.PeerAPIPort = b.GetPeerAPIPort
+	} else {
 		b.logf("[unexpected] failed to wire up PeerAPI port for engine %T", e)
 	}
 
@@ -464,6 +462,7 @@ func (b *LocalBackend) GetComponentDebugLogging(component string) time.Time {
 }
 
 // Dialer returns the backend's dialer.
+// It is always non-nil.
 func (b *LocalBackend) Dialer() *tsdial.Dialer {
 	return b.dialer
 }
@@ -644,7 +643,7 @@ func (b *LocalBackend) updateStatus(sb *ipnstate.StatusBuilder, extraLocked func
 	defer b.mu.Unlock()
 	sb.MutateStatus(func(s *ipnstate.Status) {
 		s.Version = version.Long()
-		s.TUN = !wgengine.IsNetstack(b.e)
+		s.TUN = !b.sys.IsNetstack()
 		s.BackendState = b.state.String()
 		s.AuthURL = b.authURLSticky
 		if err := health.OverallError(); err != nil {
@@ -1315,8 +1314,8 @@ func (b *LocalBackend) Start(opts ipn.Options) error {
 	hostinfo := hostinfo.New()
 	hostinfo.BackendLogID = b.backendLogID.String()
 	hostinfo.FrontendLogID = opts.FrontendLogID
-	hostinfo.Userspace.Set(wgengine.IsNetstack(b.e))
-	hostinfo.UserspaceRouter.Set(wgengine.IsNetstackRouter(b.e))
+	hostinfo.Userspace.Set(b.sys.IsNetstack())
+	hostinfo.UserspaceRouter.Set(b.sys.IsNetstackRouter())
 
 	if b.cc != nil {
 		// TODO(apenwarr): avoid the need to reinit controlclient.
@@ -1401,7 +1400,7 @@ func (b *LocalBackend) Start(opts ipn.Options) error {
 
 	var err error
 
-	isNetstack := wgengine.IsNetstackRouter(b.e)
+	isNetstack := b.sys.IsNetstackRouter()
 	debugFlags := controlDebugFlags
 	if isNetstack {
 		debugFlags = append([]string{"netstack"}, debugFlags...)
@@ -1423,7 +1422,7 @@ func (b *LocalBackend) Start(opts ipn.Options) error {
 		HTTPTestClient:       httpTestClient,
 		DiscoPublicKey:       discoPublic,
 		DebugFlags:           debugFlags,
-		NetMon:               b.e.GetNetMon(),
+		NetMon:               b.sys.NetMon.Get(),
 		Pinger:               b,
 		PopBrowserURL:        b.tellClientToBrowseToURL,
 		OnClientVersion:      b.onClientVersion,
@@ -3317,14 +3316,12 @@ func (b *LocalBackend) initPeerAPIListener() {
 		directFileMode:          b.directFileRoot != "",
 		directFileDoFinalRename: b.directFileDoFinalRename,
 	}
-	if re, ok := b.e.(wgengine.ResolvingEngine); ok {
-		if r, ok := re.GetResolver(); ok {
-			ps.resolver = r
-		}
+	if dm, ok := b.sys.DNSManager.GetOK(); ok {
+		ps.resolver = dm.Resolver()
 	}
 	b.peerAPIServer = ps
 
-	isNetstack := wgengine.IsNetstack(b.e)
+	isNetstack := b.sys.IsNetstack()
 	for i, a := range b.netMap.Addresses {
 		var ln net.Listener
 		var err error
@@ -4040,7 +4037,7 @@ func (b *LocalBackend) setTCPPortsInterceptedFromNetmapAndPrefsLocked(prefs ipn.
 		b.setServeProxyHandlersLocked()
 
 		// don't listen on netmap addresses if we're in userspace mode
-		if !wgengine.IsNetstack(b.e) {
+		if !b.sys.IsNetstack() {
 			b.updateServeTCPPortNetMapAddrListenersLocked(servePorts)
 		}
 	}
@@ -4391,7 +4388,7 @@ func nodeIP(n *tailcfg.Node, pred func(netip.Addr) bool) netip.Addr {
 }
 
 func (b *LocalBackend) CheckIPForwarding() error {
-	if wgengine.IsNetstackRouter(b.e) {
+	if b.sys.IsNetstackRouter() {
 		return nil
 	}
 
@@ -4537,13 +4534,9 @@ func (b *LocalBackend) DebugReSTUN() error {
 }
 
 func (b *LocalBackend) magicConn() (*magicsock.Conn, error) {
-	ig, ok := b.e.(wgengine.InternalsGetter)
+	mc, ok := b.sys.MagicSock.GetOK()
 	if !ok {
-		return nil, errors.New("engine isn't InternalsGetter")
-	}
-	_, mc, _, ok := ig.GetInternals()
-	if !ok {
-		return nil, errors.New("failed to get internals")
+		return nil, errors.New("failed to get magicsock from sys")
 	}
 	return mc, nil
 }

ipn/ipnlocal/local_test.go

@@ -20,6 +20,7 @@ import (
 	"tailscale.com/net/interfaces"
 	"tailscale.com/net/tsaddr"
 	"tailscale.com/tailcfg"
+	"tailscale.com/tsd"
 	"tailscale.com/tstest"
 	"tailscale.com/types/key"
 	"tailscale.com/types/logger"
@@ -501,13 +502,16 @@ func TestLazyMachineKeyGeneration(t *testing.T) {
 	tstest.Replace(t, &panicOnMachineKeyGeneration, func() bool { return true })
 
 	var logf logger.Logf = logger.Discard
+	sys := new(tsd.System)
 	store := new(mem.Store)
-	eng, err := wgengine.NewFakeUserspaceEngine(logf, 0)
+	sys.Set(store)
+	eng, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set)
 	if err != nil {
 		t.Fatalf("NewFakeUserspaceEngine: %v", err)
 	}
 	t.Cleanup(eng.Close)
-	lb, err := NewLocalBackend(logf, logid.PublicID{}, store, nil, eng, 0)
+	sys.Set(eng)
+	lb, err := NewLocalBackend(logf, logid.PublicID{}, sys, 0)
 	if err != nil {
 		t.Fatalf("NewLocalBackend: %v", err)
 	}
@@ -765,13 +769,16 @@ func TestPacketFilterPermitsUnlockedNodes(t *testing.T) {
 func TestStatusWithoutPeers(t *testing.T) {
 	logf := tstest.WhileTestRunningLogger(t)
 	store := new(testStateStorage)
-	e, err := wgengine.NewFakeUserspaceEngine(logf, 0)
+	sys := new(tsd.System)
+	sys.Set(store)
+	e, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set)
 	if err != nil {
 		t.Fatalf("NewFakeUserspaceEngine: %v", err)
 	}
+	sys.Set(e)
 	t.Cleanup(e.Close)
 
-	b, err := NewLocalBackend(logf, logid.PublicID{}, store, nil, e, 0)
+	b, err := NewLocalBackend(logf, logid.PublicID{}, sys, 0)
 	if err != nil {
 		t.Fatalf("NewLocalBackend: %v", err)
 	}

ipn/ipnlocal/loglines_test.go

@@ -12,6 +12,7 @@ import (
 	"tailscale.com/ipn/ipnstate"
 	"tailscale.com/ipn/store/mem"
 	"tailscale.com/tailcfg"
+	"tailscale.com/tsd"
 	"tailscale.com/tstest"
 	"tailscale.com/types/key"
 	"tailscale.com/types/logger"
@@ -47,14 +48,17 @@ func TestLocalLogLines(t *testing.T) {
 	idA := logid(0xaa)
 
 	// set up a LocalBackend, super bare bones. No functional data.
+	sys := new(tsd.System)
 	store := new(mem.Store)
-	e, err := wgengine.NewFakeUserspaceEngine(logf, 0)
+	sys.Set(store)
+	e, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set)
 	if err != nil {
 		t.Fatal(err)
 	}
 	t.Cleanup(e.Close)
+	sys.Set(e)
 
-	lb, err := NewLocalBackend(logf, idA, store, nil, e, 0)
+	lb, err := NewLocalBackend(logf, idA, sys, 0)
 	if err != nil {
 		t.Fatal(err)
 	}

ipn/ipnlocal/peerapi.go

@@ -50,7 +50,6 @@ import (
 	"tailscale.com/util/clientmetric"
 	"tailscale.com/util/multierr"
 	"tailscale.com/version/distro"
-	"tailscale.com/wgengine"
 	"tailscale.com/wgengine/filter"
 )
 
@@ -469,7 +468,7 @@ func (s *peerAPIServer) listen(ip netip.Addr, ifState *interfaces.State) (ln net
 		}
 	}
 
-	if wgengine.IsNetstack(s.b.e) {
+	if s.b.sys.IsNetstack() {
 		ipStr = ""
 	}
 
@@ -1239,12 +1238,9 @@ func (h *peerAPIHandler) handleServeMagicsock(w http.ResponseWriter, r *http.Req
 		http.Error(w, "denied; no debug access", http.StatusForbidden)
 		return
 	}
-	eng := h.ps.b.e
-	if ig, ok := eng.(wgengine.InternalsGetter); ok {
-		if _, mc, _, ok := ig.GetInternals(); ok {
-			mc.ServeHTTPDebug(w, r)
-			return
-		}
+	if mc, ok := h.ps.b.sys.MagicSock.GetOK(); ok {
+		mc.ServeHTTPDebug(w, r)
+		return
 	}
 	http.Error(w, "miswired", 500)
 }

ipn/ipnlocal/serve.go

@@ -143,7 +143,7 @@ func (s *serveListener) Run() {
 }
 
 func (s *serveListener) shouldWarnAboutListenError(err error) bool {
-	if !s.b.e.GetNetMon().InterfaceState().HasIP(s.ap.Addr()) {
+	if !s.b.sys.NetMon.Get().InterfaceState().HasIP(s.ap.Addr()) {
 		// Machine likely doesn't have IPv6 enabled (or the IP is still being
 		// assigned). No need to warn. Notably, WSL2 (Issue 6303).
 		return false

ipn/ipnlocal/state_test.go

@@ -17,6 +17,7 @@ import (
 	"tailscale.com/ipn"
 	"tailscale.com/ipn/store/mem"
 	"tailscale.com/tailcfg"
+	"tailscale.com/tsd"
 	"tailscale.com/tstest"
 	"tailscale.com/types/empty"
 	"tailscale.com/types/key"
@@ -297,14 +298,17 @@ func TestStateMachine(t *testing.T) {
 	c := qt.New(t)
 
 	logf := tstest.WhileTestRunningLogger(t)
+	sys := new(tsd.System)
 	store := new(testStateStorage)
-	e, err := wgengine.NewFakeUserspaceEngine(logf, 0)
+	sys.Set(store)
+	e, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set)
 	if err != nil {
 		t.Fatalf("NewFakeUserspaceEngine: %v", err)
 	}
 	t.Cleanup(e.Close)
+	sys.Set(e)
 
-	b, err := NewLocalBackend(logf, logid.PublicID{}, store, nil, e, 0)
+	b, err := NewLocalBackend(logf, logid.PublicID{}, sys, 0)
 	if err != nil {
 		t.Fatalf("NewLocalBackend: %v", err)
 	}
@@ -941,13 +945,16 @@ func TestStateMachine(t *testing.T) {
 
 func TestEditPrefsHasNoKeys(t *testing.T) {
 	logf := tstest.WhileTestRunningLogger(t)
-	e, err := wgengine.NewFakeUserspaceEngine(logf, 0)
+	sys := new(tsd.System)
+	sys.Set(new(mem.Store))
+	e, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set)
 	if err != nil {
 		t.Fatalf("NewFakeUserspaceEngine: %v", err)
 	}
 	t.Cleanup(e.Close)
+	sys.Set(e)
 
-	b, err := NewLocalBackend(logf, logid.PublicID{}, new(mem.Store), nil, e, 0)
+	b, err := NewLocalBackend(logf, logid.PublicID{}, sys, 0)
 	if err != nil {
 		t.Fatalf("NewLocalBackend: %v", err)
 	}
@@ -1023,10 +1030,14 @@ func TestWGEngineStatusRace(t *testing.T) {
 	t.Skip("test fails")
 	c := qt.New(t)
 	logf := tstest.WhileTestRunningLogger(t)
-	eng, err := wgengine.NewFakeUserspaceEngine(logf, 0)
+	sys := new(tsd.System)
+	sys.Set(new(mem.Store))
+
+	eng, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set)
 	c.Assert(err, qt.IsNil)
 	t.Cleanup(eng.Close)
-	b, err := NewLocalBackend(logf, logid.PublicID{}, new(mem.Store), nil, eng, 0)
+	sys.Set(eng)
+	b, err := NewLocalBackend(logf, logid.PublicID{}, sys, 0)
 	c.Assert(err, qt.IsNil)
 
 	var cc *mockControl

ipn/ipnserver/server.go

@@ -37,7 +37,7 @@ import (
 type Server struct {
 	lb           atomic.Pointer[ipnlocal.LocalBackend]
 	logf         logger.Logf
-	netMon       *netmon.Monitor // optional; nil means interfaces will be looked up on-demand
+	netMon       *netmon.Monitor // must be non-nil
 	backendLogID logid.PublicID
 	// resetOnZero is whether to call bs.Reset on transition from
 	// 1->0 active HTTP requests. That is, this is whether the backend is
@@ -410,14 +410,15 @@ func (s *Server) addActiveHTTPRequest(req *http.Request, ci *ipnauth.ConnIdentit
 }
 
 // New returns a new Server.
-// The netMon parameter is optional; if non-nil it's used to do faster interface
-// lookups.
 //
 // To start it, use the Server.Run method.
 //
 // At some point, either before or after Run, the Server's SetLocalBackend
 // method must also be called before Server can do anything useful.
 func New(logf logger.Logf, logID logid.PublicID, netMon *netmon.Monitor) *Server {
+	if netMon == nil {
+		panic("nil netMon")
+	}
 	return &Server{
 		backendLogID: logID,
 		logf:         logf,