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>

cmd/tailscaled/depaware.txt

@@ -282,6 +282,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
   LD    tailscale.com/tempfork/gliderlabs/ssh                        from tailscale.com/ssh/tailssh
         tailscale.com/tka                                            from tailscale.com/ipn/ipnlocal+
    W    tailscale.com/tsconst                                        from tailscale.com/net/interfaces
+        tailscale.com/tsd                                            from tailscale.com/cmd/tailscaled+
         tailscale.com/tstime                                         from tailscale.com/wgengine/magicsock
      💣 tailscale.com/tstime/mono                                    from tailscale.com/net/tstun+
         tailscale.com/tstime/rate                                    from tailscale.com/wgengine/filter+

cmd/tailscaled/tailscaled.go

@@ -50,6 +50,7 @@ import (
 	"tailscale.com/safesocket"
 	"tailscale.com/smallzstd"
 	"tailscale.com/syncs"
+	"tailscale.com/tsd"
 	"tailscale.com/tsweb/varz"
 	"tailscale.com/types/flagtype"
 	"tailscale.com/types/logger"
@@ -330,12 +331,16 @@ var debugMux *http.ServeMux
 
 func run() error {
 	var logf logger.Logf = log.Printf
+
+	sys := new(tsd.System)
+
 	netMon, err := netmon.New(func(format string, args ...any) {
 		logf(format, args...)
 	})
 	if err != nil {
 		return fmt.Errorf("netmon.New: %w", err)
 	}
+	sys.Set(netMon)
 
 	pol := logpolicy.New(logtail.CollectionNode, netMon)
 	pol.SetVerbosityLevel(args.verbose)
@@ -386,10 +391,10 @@ func run() error {
 		debugMux = newDebugMux()
 	}
 
-	return startIPNServer(context.Background(), logf, pol.PublicID, netMon)
+	return startIPNServer(context.Background(), logf, pol.PublicID, sys)
 }
 
-func startIPNServer(ctx context.Context, logf logger.Logf, logID logid.PublicID, netMon *netmon.Monitor) error {
+func startIPNServer(ctx context.Context, logf logger.Logf, logID logid.PublicID, sys *tsd.System) error {
 	ln, err := safesocket.Listen(args.socketpath)
 	if err != nil {
 		return fmt.Errorf("safesocket.Listen: %v", err)
@@ -415,7 +420,7 @@ func startIPNServer(ctx context.Context, logf logger.Logf, logID logid.PublicID,
 		}
 	}()
 
-	srv := ipnserver.New(logf, logID, netMon)
+	srv := ipnserver.New(logf, logID, sys.NetMon.Get())
 	if debugMux != nil {
 		debugMux.HandleFunc("/debug/ipn", srv.ServeHTMLStatus)
 	}
@@ -433,7 +438,7 @@ func startIPNServer(ctx context.Context, logf logger.Logf, logID logid.PublicID,
 				return
 			}
 		}
-		lb, err := getLocalBackend(ctx, logf, logID, netMon)
+		lb, err := getLocalBackend(ctx, logf, logID, sys)
 		if err == nil {
 			logf("got LocalBackend in %v", time.Since(t0).Round(time.Millisecond))
 			srv.SetLocalBackend(lb)
@@ -457,31 +462,28 @@ func startIPNServer(ctx context.Context, logf logger.Logf, logID logid.PublicID,
 	return nil
 }
 
-func getLocalBackend(ctx context.Context, logf logger.Logf, logID logid.PublicID, netMon *netmon.Monitor) (_ *ipnlocal.LocalBackend, retErr error) {
+func getLocalBackend(ctx context.Context, logf logger.Logf, logID logid.PublicID, sys *tsd.System) (_ *ipnlocal.LocalBackend, retErr error) {
 	if logPol != nil {
-		logPol.Logtail.SetNetMon(netMon)
+		logPol.Logtail.SetNetMon(sys.NetMon.Get())
 	}
 
 	socksListener, httpProxyListener := mustStartProxyListeners(args.socksAddr, args.httpProxyAddr)
 
 	dialer := &tsdial.Dialer{Logf: logf} // mutated below (before used)
-	e, onlyNetstack, err := createEngine(logf, netMon, dialer)
+	sys.Set(dialer)
+
+	onlyNetstack, err := createEngine(logf, sys)
 	if err != nil {
 		return nil, fmt.Errorf("createEngine: %w", err)
 	}
-	if _, ok := e.(wgengine.ResolvingEngine).GetResolver(); !ok {
-		panic("internal error: exit node resolver not wired up")
-	}
 	if debugMux != nil {
-		if ig, ok := e.(wgengine.InternalsGetter); ok {
-			if _, mc, _, ok := ig.GetInternals(); ok {
-				debugMux.HandleFunc("/debug/magicsock", mc.ServeHTTPDebug)
-			}
+		if ms, ok := sys.MagicSock.GetOK(); ok {
+			debugMux.HandleFunc("/debug/magicsock", ms.ServeHTTPDebug)
 		}
 		go runDebugServer(debugMux, args.debug)
 	}
 
-	ns, err := newNetstack(logf, dialer, e)
+	ns, err := newNetstack(logf, sys)
 	if err != nil {
 		return nil, fmt.Errorf("newNetstack: %w", err)
 	}
@@ -489,6 +491,7 @@ func getLocalBackend(ctx context.Context, logf logger.Logf, logID logid.PublicID
 	ns.ProcessSubnets = onlyNetstack || handleSubnetsInNetstack()
 
 	if onlyNetstack {
+		e := sys.Engine.Get()
 		dialer.UseNetstackForIP = func(ip netip.Addr) bool {
 			_, ok := e.PeerForIP(ip)
 			return ok
@@ -519,16 +522,15 @@ func getLocalBackend(ctx context.Context, logf logger.Logf, logID logid.PublicID
 		tshttpproxy.SetSelfProxy(addrs...)
 	}
 
-	e = wgengine.NewWatchdog(e)
-
 	opts := ipnServerOpts()
 
 	store, err := store.New(logf, statePathOrDefault())
 	if err != nil {
 		return nil, fmt.Errorf("store.New: %w", err)
 	}
+	sys.Set(store)
 
-	lb, err := ipnlocal.NewLocalBackend(logf, logID, store, dialer, e, opts.LoginFlags)
+	lb, err := ipnlocal.NewLocalBackend(logf, logID, sys, opts.LoginFlags)
 	if err != nil {
 		return nil, fmt.Errorf("ipnlocal.NewLocalBackend: %w", err)
 	}
@@ -554,21 +556,21 @@ func getLocalBackend(ctx context.Context, logf logger.Logf, logID logid.PublicID
 //
 // onlyNetstack is true if the user has explicitly requested that we use netstack
 // for all networking.
-func createEngine(logf logger.Logf, netMon *netmon.Monitor, dialer *tsdial.Dialer) (e wgengine.Engine, onlyNetstack bool, err error) {
+func createEngine(logf logger.Logf, sys *tsd.System) (onlyNetstack bool, err error) {
 	if args.tunname == "" {
-		return nil, false, errors.New("no --tun value specified")
+		return false, errors.New("no --tun value specified")
 	}
 	var errs []error
 	for _, name := range strings.Split(args.tunname, ",") {
 		logf("wgengine.NewUserspaceEngine(tun %q) ...", name)
-		e, onlyNetstack, err = tryEngine(logf, netMon, dialer, name)
+		onlyNetstack, err = tryEngine(logf, sys, name)
 		if err == nil {
-			return e, onlyNetstack, nil
+			return onlyNetstack, nil
 		}
 		logf("wgengine.NewUserspaceEngine(tun %q) error: %v", name, err)
 		errs = append(errs, err)
 	}
-	return nil, false, multierr.New(errs...)
+	return false, multierr.New(errs...)
 }
 
 // handleSubnetsInNetstack reports whether netstack should handle subnet routers
@@ -593,21 +595,23 @@ func handleSubnetsInNetstack() bool {
 
 var tstunNew = tstun.New
 
-func tryEngine(logf logger.Logf, netMon *netmon.Monitor, dialer *tsdial.Dialer, name string) (e wgengine.Engine, onlyNetstack bool, err error) {
+func tryEngine(logf logger.Logf, sys *tsd.System, name string) (onlyNetstack bool, err error) {
 	conf := wgengine.Config{
-		ListenPort: args.port,
-		NetMon:     netMon,
-		Dialer:     dialer,
+		ListenPort:   args.port,
+		NetMon:       sys.NetMon.Get(),
+		Dialer:       sys.Dialer.Get(),
+		SetSubsystem: sys.Set,
 	}
 
 	onlyNetstack = name == "userspace-networking"
+	netstackSubnetRouter := onlyNetstack // but mutated later on some platforms
 	netns.SetEnabled(!onlyNetstack)
 
 	if args.birdSocketPath != "" && createBIRDClient != nil {
 		log.Printf("Connecting to BIRD at %s ...", args.birdSocketPath)
 		conf.BIRDClient, err = createBIRDClient(args.birdSocketPath)
 		if err != nil {
-			return nil, false, fmt.Errorf("createBIRDClient: %w", err)
+			return false, fmt.Errorf("createBIRDClient: %w", err)
 		}
 	}
 	if onlyNetstack {
@@ -620,44 +624,55 @@ func tryEngine(logf logger.Logf, netMon *netmon.Monitor, dialer *tsdial.Dialer,
 			// TODO(bradfitz): add a Synology-specific DNS manager.
 			conf.DNS, err = dns.NewOSConfigurator(logf, "") // empty interface name
 			if err != nil {
-				return nil, false, fmt.Errorf("dns.NewOSConfigurator: %w", err)
+				return false, fmt.Errorf("dns.NewOSConfigurator: %w", err)
 			}
 		}
 	} else {
 		dev, devName, err := tstunNew(logf, name)
 		if err != nil {
 			tstun.Diagnose(logf, name, err)
-			return nil, false, fmt.Errorf("tstun.New(%q): %w", name, err)
+			return false, fmt.Errorf("tstun.New(%q): %w", name, err)
 		}
 		conf.Tun = dev
 		if strings.HasPrefix(name, "tap:") {
 			conf.IsTAP = true
 			e, err := wgengine.NewUserspaceEngine(logf, conf)
-			return e, false, err
+			if err != nil {
+				return false, err
+			}
+			sys.Set(e)
+			return false, err
 		}
 
-		r, err := router.New(logf, dev, netMon)
+		r, err := router.New(logf, dev, sys.NetMon.Get())
 		if err != nil {
 			dev.Close()
-			return nil, false, fmt.Errorf("creating router: %w", err)
+			return false, fmt.Errorf("creating router: %w", err)
 		}
+		sys.Set(r)
+
 		d, err := dns.NewOSConfigurator(logf, devName)
 		if err != nil {
 			dev.Close()
 			r.Close()
-			return nil, false, fmt.Errorf("dns.NewOSConfigurator: %w", err)
+			return false, fmt.Errorf("dns.NewOSConfigurator: %w", err)
 		}
 		conf.DNS = d
 		conf.Router = r
 		if handleSubnetsInNetstack() {
 			conf.Router = netstack.NewSubnetRouterWrapper(conf.Router)
+			netstackSubnetRouter = true
 		}
 	}
-	e, err = wgengine.NewUserspaceEngine(logf, conf)
+	e, err := wgengine.NewUserspaceEngine(logf, conf)
 	if err != nil {
-		return nil, onlyNetstack, err
+		return onlyNetstack, err
 	}
-	return e, onlyNetstack, nil
+	e = wgengine.NewWatchdog(e)
+	sys.Set(e)
+	sys.NetstackRouter.Set(netstackSubnetRouter)
+
+	return onlyNetstack, nil
 }
 
 func newDebugMux() *http.ServeMux {
@@ -687,12 +702,8 @@ func runDebugServer(mux *http.ServeMux, addr string) {
 	}
 }
 
-func newNetstack(logf logger.Logf, dialer *tsdial.Dialer, e wgengine.Engine) (*netstack.Impl, error) {
-	tunDev, magicConn, dns, ok := e.(wgengine.InternalsGetter).GetInternals()
-	if !ok {
-		return nil, fmt.Errorf("%T is not a wgengine.InternalsGetter", e)
-	}
-	return netstack.Create(logf, tunDev, e, magicConn, dialer, dns)
+func newNetstack(logf logger.Logf, sys *tsd.System) (*netstack.Impl, error) {
+	return netstack.Create(logf, sys.Tun.Get(), sys.Engine.Get(), sys.MagicSock.Get(), sys.Dialer.Get(), sys.DNSManager.Get())
 }
 
 // mustStartProxyListeners creates listeners for local SOCKS and HTTP

cmd/tailscaled/tailscaled_windows.go

@@ -47,6 +47,7 @@ import (
 	"tailscale.com/net/dns"
 	"tailscale.com/net/netmon"
 	"tailscale.com/net/tstun"
+	"tailscale.com/tsd"
 	"tailscale.com/types/logger"
 	"tailscale.com/types/logid"
 	"tailscale.com/util/winutil"
@@ -292,13 +293,15 @@ func beWindowsSubprocess() bool {
 		}
 	}()
 
+	sys := new(tsd.System)
 	netMon, err := netmon.New(log.Printf)
 	if err != nil {
-		log.Printf("Could not create netMon: %v", err)
-		netMon = nil
+		log.Fatalf("Could not create netMon: %v", err)
 	}
+	sys.Set(netMon)
+
 	publicLogID, _ := logid.ParsePublicID(logID)
-	err = startIPNServer(ctx, log.Printf, publicLogID, netMon)
+	err = startIPNServer(ctx, log.Printf, publicLogID, sys)
 	if err != nil {
 		log.Fatalf("ipnserver: %v", err)
 	}

cmd/tsconnect/wasm/wasm_js.go

@@ -37,6 +37,7 @@ import (
 	"tailscale.com/safesocket"
 	"tailscale.com/smallzstd"
 	"tailscale.com/tailcfg"
+	"tailscale.com/tsd"
 	"tailscale.com/wgengine"
 	"tailscale.com/wgengine/netstack"
 	"tailscale.com/words"
@@ -96,6 +97,8 @@ func newIPN(jsConfig js.Value) map[string]any {
 	logtail := logtail.NewLogger(c, log.Printf)
 	logf := logtail.Logf
 
+	sys := new(tsd.System)
+	sys.Set(store)
 	dialer := &tsdial.Dialer{Logf: logf}
 	eng, err := wgengine.NewUserspaceEngine(logf, wgengine.Config{
 		Dialer: dialer,
@@ -103,12 +106,9 @@ func newIPN(jsConfig js.Value) map[string]any {
 	if err != nil {
 		log.Fatal(err)
 	}
+	sys.Set(eng)
 
-	tunDev, magicConn, dnsManager, ok := eng.(wgengine.InternalsGetter).GetInternals()
-	if !ok {
-		log.Fatalf("%T is not a wgengine.InternalsGetter", eng)
-	}
-	ns, err := netstack.Create(logf, tunDev, eng, magicConn, dialer, dnsManager)
+	ns, err := netstack.Create(logf, sys.Tun.Get(), eng, sys.MagicSock.Get(), dialer, sys.DNSManager.Get())
 	if err != nil {
 		log.Fatalf("netstack.Create: %v", err)
 	}
@@ -121,10 +121,11 @@ func newIPN(jsConfig js.Value) map[string]any {
 	dialer.NetstackDialTCP = func(ctx context.Context, dst netip.AddrPort) (net.Conn, error) {
 		return ns.DialContextTCP(ctx, dst)
 	}
+	sys.NetstackRouter.Set(true)
 
 	logid := lpc.PublicID
 	srv := ipnserver.New(logf, logid, nil /* no netMon */)
-	lb, err := ipnlocal.NewLocalBackend(logf, logid, store, dialer, eng, controlclient.LoginEphemeral)
+	lb, err := ipnlocal.NewLocalBackend(logf, logid, sys, controlclient.LoginEphemeral)
 	if err != nil {
 		log.Fatalf("ipnlocal.NewLocalBackend: %v", err)
 	}