net/netmon: publish events to event bus

Updates #15160

Signed-off-by: David Anderson <dave@tailscale.com>

cmd/derper/depaware.txt

@@ -155,6 +155,7 @@ tailscale.com/cmd/derper dependencies: (generated by github.com/tailscale/depawa
      💣 tailscale.com/util/deephash                                  from tailscale.com/util/syspolicy/setting
    L 💣 tailscale.com/util/dirwalk                                   from tailscale.com/metrics
         tailscale.com/util/dnsname                                   from tailscale.com/hostinfo+
+        tailscale.com/util/eventbus                                  from tailscale.com/net/netmon
      💣 tailscale.com/util/hashx                                     from tailscale.com/util/deephash
         tailscale.com/util/httpm                                     from tailscale.com/client/tailscale
         tailscale.com/util/lineiter                                  from tailscale.com/hostinfo+
@@ -308,7 +309,7 @@ tailscale.com/cmd/derper dependencies: (generated by github.com/tailscale/depawa
         hash/fnv                                                     from google.golang.org/protobuf/internal/detrand
         hash/maphash                                                 from go4.org/mem
         html                                                         from net/http/pprof+
-        html/template                                                from tailscale.com/cmd/derper
+        html/template                                                from tailscale.com/cmd/derper+
         internal/abi                                                 from crypto/x509/internal/macos+
         internal/asan                                                from internal/runtime/maps+
         internal/bisect                                              from internal/godebug

cmd/tailscale/cli/debug.go

@@ -43,6 +43,7 @@ import (
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/key"
 	"tailscale.com/types/logger"
+	"tailscale.com/util/eventbus"
 	"tailscale.com/util/must"
 )
 
@@ -956,7 +957,10 @@ func runTS2021(ctx context.Context, args []string) error {
 		logf = log.Printf
 	}
 
-	netMon, err := netmon.New(logger.WithPrefix(logf, "netmon: "))
+	bus := eventbus.New()
+	defer bus.Close()
+
+	netMon, err := netmon.New(bus, logger.WithPrefix(logf, "netmon: "))
 	if err != nil {
 		return fmt.Errorf("creating netmon: %w", err)
 	}

cmd/tailscale/cli/netcheck.go

@@ -24,6 +24,7 @@ import (
 	"tailscale.com/net/tlsdial"
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/logger"
+	"tailscale.com/util/eventbus"
 )
 
 var netcheckCmd = &ffcli.Command{
@@ -48,7 +49,9 @@ var netcheckArgs struct {
 
 func runNetcheck(ctx context.Context, args []string) error {
 	logf := logger.WithPrefix(log.Printf, "portmap: ")
-	netMon, err := netmon.New(logf)
+	bus := eventbus.New()
+	defer bus.Close()
+	netMon, err := netmon.New(bus, logf)
 	if err != nil {
 		return err
 	}

cmd/tailscale/depaware.txt

@@ -162,7 +162,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
      💣 tailscale.com/util/deephash                                  from tailscale.com/util/syspolicy/setting
    L 💣 tailscale.com/util/dirwalk                                   from tailscale.com/metrics
         tailscale.com/util/dnsname                                   from tailscale.com/cmd/tailscale/cli+
-        tailscale.com/util/eventbus                                  from tailscale.com/net/portmapper
+        tailscale.com/util/eventbus                                  from tailscale.com/net/portmapper+
         tailscale.com/util/groupmember                               from tailscale.com/client/web
      💣 tailscale.com/util/hashx                                     from tailscale.com/util/deephash
         tailscale.com/util/httpm                                     from tailscale.com/client/tailscale+

cmd/tailscaled/debug.go

@@ -27,6 +27,7 @@ import (
 	"tailscale.com/net/tshttpproxy"
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/key"
+	"tailscale.com/util/eventbus"
 )
 
 var debugArgs struct {
@@ -72,11 +73,14 @@ func debugMode(args []string) error {
 }
 
 func runMonitor(ctx context.Context, loop bool) error {
+	b := eventbus.New()
+	defer b.Close()
+
 	dump := func(st *netmon.State) {
 		j, _ := json.MarshalIndent(st, "", "    ")
 		os.Stderr.Write(j)
 	}
-	mon, err := netmon.New(log.Printf)
+	mon, err := netmon.New(b, log.Printf)
 	if err != nil {
 		return err
 	}

cmd/tailscaled/tailscaled.go

@@ -356,7 +356,7 @@ func run() (err error) {
 	var netMon *netmon.Monitor
 	isWinSvc := isWindowsService()
 	if !isWinSvc {
-		netMon, err = netmon.New(logf)
+		netMon, err = netmon.New(sys.Bus.Get(), logf)
 		if err != nil {
 			return fmt.Errorf("netmon.New: %w", err)
 		}

cmd/tailscaled/tailscaled_windows.go

@@ -328,7 +328,7 @@ func beWindowsSubprocess() bool {
 	}
 
 	sys := tsd.NewSystem()
-	netMon, err := netmon.New(log.Printf)
+	netMon, err := netmon.New(sys.Bus.Get(), log.Printf)
 	if err != nil {
 		log.Fatalf("Could not create netMon: %v", err)
 	}

ipn/ipnlocal/local_test.go

@@ -448,7 +448,7 @@ func newTestLocalBackendWithSys(t testing.TB, sys *tsd.System) *LocalBackend {
 		sys.Set(new(mem.Store))
 	}
 	if _, ok := sys.Engine.GetOK(); !ok {
-		eng, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set, sys.HealthTracker(), sys.UserMetricsRegistry())
+		eng, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set, sys.HealthTracker(), sys.UserMetricsRegistry(), sys.Bus.Get())
 		if err != nil {
 			t.Fatalf("NewFakeUserspaceEngine: %v", err)
 		}
@@ -4414,7 +4414,7 @@ func newLocalBackendWithTestControl(t *testing.T, enableLogging bool, newControl
 	sys := tsd.NewSystem()
 	store := new(mem.Store)
 	sys.Set(store)
-	e, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set, sys.HealthTracker(), sys.UserMetricsRegistry())
+	e, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set, sys.HealthTracker(), sys.UserMetricsRegistry(), sys.Bus.Get())
 	if err != nil {
 		t.Fatalf("NewFakeUserspaceEngine: %v", err)
 	}

ipn/ipnlocal/loglines_test.go

@@ -50,7 +50,7 @@ func TestLocalLogLines(t *testing.T) {
 	sys := tsd.NewSystem()
 	store := new(mem.Store)
 	sys.Set(store)
-	e, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set, sys.HealthTracker(), sys.UserMetricsRegistry())
+	e, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set, sys.HealthTracker(), sys.UserMetricsRegistry(), sys.Bus.Get())
 	if err != nil {
 		t.Fatal(err)
 	}

ipn/ipnlocal/peerapi_test.go

@@ -34,6 +34,7 @@ import (
 	"tailscale.com/tstest"
 	"tailscale.com/types/logger"
 	"tailscale.com/types/netmap"
+	"tailscale.com/util/eventbus"
 	"tailscale.com/util/must"
 	"tailscale.com/util/usermetric"
 	"tailscale.com/wgengine"
@@ -643,9 +644,12 @@ func TestPeerAPIReplyToDNSQueries(t *testing.T) {
 	h.isSelf = false
 	h.remoteAddr = netip.MustParseAddrPort("100.150.151.152:12345")
 
+	bus := eventbus.New()
+	defer bus.Close()
+
 	ht := new(health.Tracker)
 	reg := new(usermetric.Registry)
-	eng, _ := wgengine.NewFakeUserspaceEngine(logger.Discard, 0, ht, reg)
+	eng, _ := wgengine.NewFakeUserspaceEngine(logger.Discard, 0, ht, reg, bus)
 	pm := must.Get(newProfileManager(new(mem.Store), t.Logf, ht))
 	h.ps = &peerAPIServer{
 		b: &LocalBackend{
@@ -695,9 +699,12 @@ func TestPeerAPIPrettyReplyCNAME(t *testing.T) {
 		var h peerAPIHandler
 		h.remoteAddr = netip.MustParseAddrPort("100.150.151.152:12345")
 
+		bus := eventbus.New()
+		defer bus.Close()
+
 		ht := new(health.Tracker)
 		reg := new(usermetric.Registry)
-		eng, _ := wgengine.NewFakeUserspaceEngine(logger.Discard, 0, ht, reg)
+		eng, _ := wgengine.NewFakeUserspaceEngine(logger.Discard, 0, ht, reg, bus)
 		pm := must.Get(newProfileManager(new(mem.Store), t.Logf, ht))
 		var a *appc.AppConnector
 		if shouldStore {
@@ -768,10 +775,12 @@ func TestPeerAPIReplyToDNSQueriesAreObserved(t *testing.T) {
 		var h peerAPIHandler
 		h.remoteAddr = netip.MustParseAddrPort("100.150.151.152:12345")
 
+		bus := eventbus.New()
+		defer bus.Close()
 		rc := &appctest.RouteCollector{}
 		ht := new(health.Tracker)
 		reg := new(usermetric.Registry)
-		eng, _ := wgengine.NewFakeUserspaceEngine(logger.Discard, 0, ht, reg)
+		eng, _ := wgengine.NewFakeUserspaceEngine(logger.Discard, 0, ht, reg, bus)
 		pm := must.Get(newProfileManager(new(mem.Store), t.Logf, ht))
 		var a *appc.AppConnector
 		if shouldStore {
@@ -833,10 +842,12 @@ func TestPeerAPIReplyToDNSQueriesAreObservedWithCNAMEFlattening(t *testing.T) {
 		var h peerAPIHandler
 		h.remoteAddr = netip.MustParseAddrPort("100.150.151.152:12345")
 
+		bus := eventbus.New()
+		defer bus.Close()
 		ht := new(health.Tracker)
 		reg := new(usermetric.Registry)
 		rc := &appctest.RouteCollector{}
-		eng, _ := wgengine.NewFakeUserspaceEngine(logger.Discard, 0, ht, reg)
+		eng, _ := wgengine.NewFakeUserspaceEngine(logger.Discard, 0, ht, reg, bus)
 		pm := must.Get(newProfileManager(new(mem.Store), t.Logf, ht))
 		var a *appc.AppConnector
 		if shouldStore {

ipn/ipnlocal/serve_test.go

@@ -882,6 +882,7 @@ func newTestBackend(t *testing.T) *LocalBackend {
 		SetSubsystem:  sys.Set,
 		HealthTracker: sys.HealthTracker(),
 		Metrics:       sys.UserMetricsRegistry(),
+		EventBus:      sys.Bus.Get(),
 	})
 	if err != nil {
 		t.Fatal(err)

ipn/ipnlocal/state_test.go

@@ -298,7 +298,7 @@ func TestStateMachine(t *testing.T) {
 	sys := tsd.NewSystem()
 	store := new(testStateStorage)
 	sys.Set(store)
-	e, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set, sys.HealthTracker(), sys.UserMetricsRegistry())
+	e, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set, sys.HealthTracker(), sys.UserMetricsRegistry(), sys.Bus.Get())
 	if err != nil {
 		t.Fatalf("NewFakeUserspaceEngine: %v", err)
 	}
@@ -936,7 +936,7 @@ func TestEditPrefsHasNoKeys(t *testing.T) {
 	logf := tstest.WhileTestRunningLogger(t)
 	sys := tsd.NewSystem()
 	sys.Set(new(mem.Store))
-	e, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set, sys.HealthTracker(), sys.UserMetricsRegistry())
+	e, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set, sys.HealthTracker(), sys.UserMetricsRegistry(), sys.Bus.Get())
 	if err != nil {
 		t.Fatalf("NewFakeUserspaceEngine: %v", err)
 	}
@@ -1017,7 +1017,7 @@ func TestWGEngineStatusRace(t *testing.T) {
 	sys := tsd.NewSystem()
 	sys.Set(new(mem.Store))
 
-	eng, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set)
+	eng, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set, sys.Bus.Get())
 	c.Assert(err, qt.IsNil)
 	t.Cleanup(eng.Close)
 	sys.Set(eng)

ipn/ipnserver/server_test.go

@@ -522,7 +522,7 @@ func newLocalBackendWithTestControl(tb testing.TB, newControl newControlClientFn
 	sys.Set(store)
 
 	logf := testLogger(tb, enableLogging)
-	e, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set, sys.HealthTracker(), sys.UserMetricsRegistry())
+	e, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set, sys.HealthTracker(), sys.UserMetricsRegistry(), sys.Bus.Get())
 	if err != nil {
 		tb.Fatalf("NewFakeUserspaceEngine: %v", err)
 	}

ipn/localapi/localapi.go

@@ -56,6 +56,7 @@ import (
 	"tailscale.com/types/ptr"
 	"tailscale.com/types/tkatype"
 	"tailscale.com/util/clientmetric"
+	"tailscale.com/util/eventbus"
 	"tailscale.com/util/httphdr"
 	"tailscale.com/util/httpm"
 	"tailscale.com/util/mak"
@@ -840,7 +841,9 @@ func (h *Handler) serveDebugPortmap(w http.ResponseWriter, r *http.Request) {
 	})
 	defer c.Close()
 
-	netMon, err := netmon.New(logger.WithPrefix(logf, "monitor: "))
+	bus := eventbus.New()
+	defer bus.Close()
+	netMon, err := netmon.New(bus, logger.WithPrefix(logf, "monitor: "))
 	if err != nil {
 		logf("error creating monitor: %v", err)
 		return

ipn/localapi/localapi_test.go

@@ -339,7 +339,7 @@ func newTestLocalBackend(t testing.TB) *ipnlocal.LocalBackend {
 	sys := tsd.NewSystem()
 	store := new(mem.Store)
 	sys.Set(store)
-	eng, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set, sys.HealthTracker(), sys.UserMetricsRegistry())
+	eng, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set, sys.HealthTracker(), sys.UserMetricsRegistry(), sys.Bus.Get())
 	if err != nil {
 		t.Fatalf("NewFakeUserspaceEngine: %v", err)
 	}

net/dns/resolver/forwarder_test.go

@@ -29,6 +29,7 @@ import (
 	"tailscale.com/net/tsdial"
 	"tailscale.com/tstest"
 	"tailscale.com/types/dnstype"
+	"tailscale.com/util/eventbus"
 )
 
 func (rr resolverAndDelay) String() string {
@@ -454,7 +455,9 @@ func makeLargeResponse(tb testing.TB, domain string) (request, response []byte)
 
 func runTestQuery(tb testing.TB, request []byte, modify func(*forwarder), ports ...uint16) ([]byte, error) {
 	logf := tstest.WhileTestRunningLogger(tb)
-	netMon, err := netmon.New(logf)
+	bus := eventbus.New()
+	defer bus.Close()
+	netMon, err := netmon.New(bus, logf)
 	if err != nil {
 		tb.Fatal(err)
 	}

net/dns/resolver/tsdns_test.go

@@ -31,6 +31,7 @@ import (
 	"tailscale.com/types/dnstype"
 	"tailscale.com/types/logger"
 	"tailscale.com/util/dnsname"
+	"tailscale.com/util/eventbus"
 )
 
 var (
@@ -1059,7 +1060,10 @@ func TestForwardLinkSelection(t *testing.T) {
 	// routes differently.
 	specialIP := netaddr.IPv4(1, 2, 3, 4)
 
-	netMon, err := netmon.New(logger.WithPrefix(t.Logf, ".... netmon: "))
+	bus := eventbus.New()
+	defer bus.Close()
+
+	netMon, err := netmon.New(bus, logger.WithPrefix(t.Logf, ".... netmon: "))
 	if err != nil {
 		t.Fatal(err)
 	}

net/dnsfallback/dnsfallback_test.go

@@ -15,6 +15,7 @@ import (
 	"tailscale.com/net/netmon"
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/logger"
+	"tailscale.com/util/eventbus"
 )
 
 func TestGetDERPMap(t *testing.T) {
@@ -185,7 +186,10 @@ func TestLookup(t *testing.T) {
 	logf, closeLogf := logger.LogfCloser(t.Logf)
 	defer closeLogf()
 
-	netMon, err := netmon.New(logf)
+	bus := eventbus.New()
+	defer bus.Close()
+
+	netMon, err := netmon.New(bus, logf)
 	if err != nil {
 		t.Fatal(err)
 	}

net/netmon/loghelper_test.go

@@ -7,10 +7,14 @@ import (
 	"bytes"
 	"fmt"
 	"testing"
+
+	"tailscale.com/util/eventbus"
 )
 
 func TestLinkChangeLogLimiter(t *testing.T) {
-	mon, err := New(t.Logf)
+	bus := eventbus.New()
+	defer bus.Close()
+	mon, err := New(bus, t.Logf)
 	if err != nil {
 		t.Fatal(err)
 	}

net/netmon/netmon.go

@@ -16,6 +16,7 @@ import (
 
 	"tailscale.com/types/logger"
 	"tailscale.com/util/clientmetric"
+	"tailscale.com/util/eventbus"
 	"tailscale.com/util/set"
 )
 
@@ -50,7 +51,10 @@ type osMon interface {
 
 // Monitor represents a monitoring instance.
 type Monitor struct {
-	logf   logger.Logf
+	logf    logger.Logf
+	b       *eventbus.Client
+	changed *eventbus.Publisher[*ChangeDelta]
+
 	om     osMon         // nil means not supported on this platform
 	change chan bool     // send false to wake poller, true to also force ChangeDeltas be sent
 	stop   chan struct{} // closed on Stop
@@ -114,21 +118,23 @@ type ChangeDelta struct {
 // New instantiates and starts a monitoring instance.
 // The returned monitor is inactive until it's started by the Start method.
 // Use RegisterChangeCallback to get notified of network changes.
-func New(logf logger.Logf) (*Monitor, error) {
+func New(bus *eventbus.Bus, logf logger.Logf) (*Monitor, error) {
 	logf = logger.WithPrefix(logf, "monitor: ")
 	m := &Monitor{
 		logf:     logf,
+		b:        bus.Client("netmon"),
 		change:   make(chan bool, 1),
 		stop:     make(chan struct{}),
 		lastWall: wallTime(),
 	}
+	m.changed = eventbus.Publish[*ChangeDelta](m.b)
 	st, err := m.interfaceStateUncached()
 	if err != nil {
 		return nil, err
 	}
 	m.ifState = st
 
-	m.om, err = newOSMon(logf, m)
+	m.om, err = newOSMon(bus, logf, m)
 	if err != nil {
 		return nil, err
 	}
@@ -465,6 +471,7 @@ func (m *Monitor) handlePotentialChange(newState *State, forceCallbacks bool) {
 	if delta.TimeJumped {
 		metricChangeTimeJump.Add(1)
 	}
+	m.changed.Publish(delta)
 	for _, cb := range m.cbs {
 		go cb(delta)
 	}

net/netmon/netmon_darwin.go

@@ -13,6 +13,7 @@ import (
 	"golang.org/x/sys/unix"
 	"tailscale.com/net/netaddr"
 	"tailscale.com/types/logger"
+	"tailscale.com/util/eventbus"
 )
 
 const debugRouteMessages = false
@@ -24,7 +25,7 @@ type unspecifiedMessage struct{}
 
 func (unspecifiedMessage) ignore() bool { return false }
 
-func newOSMon(logf logger.Logf, _ *Monitor) (osMon, error) {
+func newOSMon(_ *eventbus.Bus, logf logger.Logf, _ *Monitor) (osMon, error) {
 	fd, err := unix.Socket(unix.AF_ROUTE, unix.SOCK_RAW, 0)
 	if err != nil {
 		return nil, err

net/netmon/netmon_freebsd.go

@@ -10,6 +10,7 @@ import (
 	"strings"
 
 	"tailscale.com/types/logger"
+	"tailscale.com/util/eventbus"
 )
 
 // unspecifiedMessage is a minimal message implementation that should not
@@ -24,7 +25,7 @@ type devdConn struct {
 	conn net.Conn
 }
 
-func newOSMon(logf logger.Logf, m *Monitor) (osMon, error) {
+func newOSMon(_ *eventbus.Bus, logf logger.Logf, m *Monitor) (osMon, error) {
 	conn, err := net.Dial("unixpacket", "/var/run/devd.seqpacket.pipe")
 	if err != nil {
 		logf("devd dial error: %v, falling back to polling method", err)

net/netmon/netmon_linux.go

@@ -16,6 +16,7 @@ import (
 	"tailscale.com/envknob"
 	"tailscale.com/net/tsaddr"
 	"tailscale.com/types/logger"
+	"tailscale.com/util/eventbus"
 )
 
 var debugNetlinkMessages = envknob.RegisterBool("TS_DEBUG_NETLINK")
@@ -27,15 +28,26 @@ type unspecifiedMessage struct{}
 
 func (unspecifiedMessage) ignore() bool { return false }
 
+// RuleDeleted reports that one of Tailscale's policy routing rules
+// was deleted.
+type RuleDeleted struct {
+	// Table is the table number that the deleted rule referenced.
+	Table uint8
+	// Priority is the lookup priority of the deleted rule.
+	Priority uint32
+}
+
 // nlConn wraps a *netlink.Conn and returns a monitor.Message
 // instead of a netlink.Message. Currently, messages are discarded,
 // but down the line, when messages trigger different logic depending
 // on the type of event, this provides the capability of handling
 // each architecture-specific message in a generic fashion.
 type nlConn struct {
-	logf     logger.Logf
+	busClient    *eventbus.Client
-	conn     *netlink.Conn
+	rulesDeleted *eventbus.Publisher[RuleDeleted]
-	buffered []netlink.Message
+	logf         logger.Logf
+	conn         *netlink.Conn
+	buffered     []netlink.Message
 
 	// addrCache maps interface indices to a set of addresses, and is
 	// used to suppress duplicate RTM_NEWADDR messages. It is populated
@@ -44,7 +56,7 @@ type nlConn struct {
 	addrCache map[uint32]map[netip.Addr]bool
 }
 
-func newOSMon(logf logger.Logf, m *Monitor) (osMon, error) {
+func newOSMon(bus *eventbus.Bus, logf logger.Logf, m *Monitor) (osMon, error) {
 	conn, err := netlink.Dial(unix.NETLINK_ROUTE, &netlink.Config{
 		// Routes get us most of the events of interest, but we need
 		// address as well to cover things like DHCP deciding to give
@@ -59,12 +71,22 @@ func newOSMon(logf logger.Logf, m *Monitor) (osMon, error) {
 		logf("monitor_linux: AF_NETLINK RTMGRP failed, falling back to polling")
 		return newPollingMon(logf, m)
 	}
-	return &nlConn{logf: logf, conn: conn, addrCache: make(map[uint32]map[netip.Addr]bool)}, nil
+	client := bus.Client("netmon-iprules")
+	return &nlConn{
+		busClient:    client,
+		rulesDeleted: eventbus.Publish[RuleDeleted](client),
+		logf:         logf,
+		conn:         conn,
+		addrCache:    make(map[uint32]map[netip.Addr]bool),
+	}, nil
 }
 
 func (c *nlConn) IsInterestingInterface(iface string) bool { return true }
 
-func (c *nlConn) Close() error { return c.conn.Close() }
+func (c *nlConn) Close() error {
+	c.busClient.Close()
+	return c.conn.Close()
+}
 
 func (c *nlConn) Receive() (message, error) {
 	if len(c.buffered) == 0 {
@@ -219,6 +241,10 @@ func (c *nlConn) Receive() (message, error) {
 			// On `ip -4 rule del pref 5210 table main`, logs:
 			// monitor: ip rule deleted: {Family:2 DstLength:0 SrcLength:0 Tos:0 Table:254 Protocol:0 Scope:0 Type:1 Flags:0 Attributes:{Dst:<nil> Src:<nil> Gateway:<nil> OutIface:0 Priority:5210 Table:254 Mark:4294967295 Expires:<nil> Metrics:<nil> Multipath:[]}}
 		}
+		c.rulesDeleted.Publish(RuleDeleted{
+			Table:    rmsg.Table,
+			Priority: rmsg.Attributes.Priority,
+		})
 		rdm := ipRuleDeletedMessage{
 			table:    rmsg.Table,
 			priority: rmsg.Attributes.Priority,

net/netmon/netmon_polling.go

@@ -7,9 +7,10 @@ package netmon
 
 import (
 	"tailscale.com/types/logger"
+	"tailscale.com/util/eventbus"
 )
 
-func newOSMon(logf logger.Logf, m *Monitor) (osMon, error) {
+func newOSMon(_ *eventbus.Bus, logf logger.Logf, m *Monitor) (osMon, error) {
 	return newPollingMon(logf, m)
 }
 

net/netmon/netmon_test.go

@@ -11,11 +11,15 @@ import (
 	"testing"
 	"time"
 
+	"tailscale.com/util/eventbus"
 	"tailscale.com/util/mak"
 )
 
 func TestMonitorStartClose(t *testing.T) {
-	mon, err := New(t.Logf)
+	bus := eventbus.New()
+	defer bus.Close()
+
+	mon, err := New(bus, t.Logf)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -26,7 +30,10 @@ func TestMonitorStartClose(t *testing.T) {
 }
 
 func TestMonitorJustClose(t *testing.T) {
-	mon, err := New(t.Logf)
+	bus := eventbus.New()
+	defer bus.Close()
+
+	mon, err := New(bus, t.Logf)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -36,7 +43,10 @@ func TestMonitorJustClose(t *testing.T) {
 }
 
 func TestMonitorInjectEvent(t *testing.T) {
-	mon, err := New(t.Logf)
+	bus := eventbus.New()
+	defer bus.Close()
+
+	mon, err := New(bus, t.Logf)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -71,7 +81,11 @@ func TestMonitorMode(t *testing.T) {
 	default:
 		t.Skipf(`invalid --monitor value: must be "raw" or "callback"`)
 	}
-	mon, err := New(t.Logf)
+
+	bus := eventbus.New()
+	defer bus.Close()
+
+	mon, err := New(bus, t.Logf)
 	if err != nil {
 		t.Fatal(err)
 	}

net/netmon/netmon_windows.go

@@ -13,6 +13,7 @@ import (
 	"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
 	"tailscale.com/net/tsaddr"
 	"tailscale.com/types/logger"
+	"tailscale.com/util/eventbus"
 )
 
 var (
@@ -45,7 +46,7 @@ type winMon struct {
 	noDeadlockTicker *time.Ticker
 }
 
-func newOSMon(logf logger.Logf, pm *Monitor) (osMon, error) {
+func newOSMon(_ *eventbus.Bus, logf logger.Logf, pm *Monitor) (osMon, error) {
 	m := &winMon{
 		logf:             logf,
 		isActive:         pm.isActive,

net/netutil/netutil_test.go

@@ -10,6 +10,7 @@ import (
 	"testing"
 
 	"tailscale.com/net/netmon"
+	"tailscale.com/util/eventbus"
 )
 
 type conn struct {
@@ -72,7 +73,10 @@ func TestCheckReversePathFiltering(t *testing.T) {
 	if runtime.GOOS != "linux" {
 		t.Skipf("skipping on %s", runtime.GOOS)
 	}
-	netMon, err := netmon.New(t.Logf)
+	bus := eventbus.New()
+	defer bus.Close()
+
+	netMon, err := netmon.New(bus, t.Logf)
 	if err != nil {
 		t.Fatal(err)
 	}

ssh/tailssh/tailssh_test.go

@@ -1038,7 +1038,7 @@ func TestSSHAuthFlow(t *testing.T) {
 func TestSSH(t *testing.T) {
 	var logf logger.Logf = t.Logf
 	sys := tsd.NewSystem()
-	eng, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set, sys.HealthTracker(), sys.UserMetricsRegistry())
+	eng, err := wgengine.NewFakeUserspaceEngine(logf, sys.Set, sys.HealthTracker(), sys.UserMetricsRegistry(), sys.Bus.Get())
 	if err != nil {
 		t.Fatal(err)
 	}

tsnet/tsnet.go

@@ -562,7 +562,7 @@ func (s *Server) start() (reterr error) {
 		return err
 	}
 
-	s.netMon, err = netmon.New(tsLogf)
+	s.netMon, err = netmon.New(sys.Bus.Get(), tsLogf)
 	if err != nil {
 		return err
 	}

tstest/integration/tailscaled_deps_test_darwin.go

@@ -48,6 +48,7 @@ import (
 	_ "tailscale.com/types/logger"
 	_ "tailscale.com/types/logid"
 	_ "tailscale.com/util/clientmetric"
+	_ "tailscale.com/util/eventbus"
 	_ "tailscale.com/util/multierr"
 	_ "tailscale.com/util/osshare"
 	_ "tailscale.com/version"

tstest/integration/tailscaled_deps_test_freebsd.go

@@ -48,6 +48,7 @@ import (
 	_ "tailscale.com/types/logger"
 	_ "tailscale.com/types/logid"
 	_ "tailscale.com/util/clientmetric"
+	_ "tailscale.com/util/eventbus"
 	_ "tailscale.com/util/multierr"
 	_ "tailscale.com/util/osshare"
 	_ "tailscale.com/version"

tstest/integration/tailscaled_deps_test_linux.go

@@ -48,6 +48,7 @@ import (
 	_ "tailscale.com/types/logger"
 	_ "tailscale.com/types/logid"
 	_ "tailscale.com/util/clientmetric"
+	_ "tailscale.com/util/eventbus"
 	_ "tailscale.com/util/multierr"
 	_ "tailscale.com/util/osshare"
 	_ "tailscale.com/version"

tstest/integration/tailscaled_deps_test_openbsd.go

@@ -48,6 +48,7 @@ import (
 	_ "tailscale.com/types/logger"
 	_ "tailscale.com/types/logid"
 	_ "tailscale.com/util/clientmetric"
+	_ "tailscale.com/util/eventbus"
 	_ "tailscale.com/util/multierr"
 	_ "tailscale.com/util/osshare"
 	_ "tailscale.com/version"

tstest/integration/tailscaled_deps_test_windows.go

@@ -56,6 +56,7 @@ import (
 	_ "tailscale.com/types/logger"
 	_ "tailscale.com/types/logid"
 	_ "tailscale.com/util/clientmetric"
+	_ "tailscale.com/util/eventbus"
 	_ "tailscale.com/util/multierr"
 	_ "tailscale.com/util/osdiag"
 	_ "tailscale.com/util/osshare"

wgengine/magicsock/magicsock_test.go

@@ -62,6 +62,7 @@ import (
 	"tailscale.com/types/nettype"
 	"tailscale.com/types/ptr"
 	"tailscale.com/util/cibuild"
+	"tailscale.com/util/eventbus"
 	"tailscale.com/util/must"
 	"tailscale.com/util/racebuild"
 	"tailscale.com/util/set"
@@ -173,7 +174,10 @@ func newMagicStack(t testing.TB, logf logger.Logf, l nettype.PacketListener, der
 func newMagicStackWithKey(t testing.TB, logf logger.Logf, l nettype.PacketListener, derpMap *tailcfg.DERPMap, privateKey key.NodePrivate) *magicStack {
 	t.Helper()
 
-	netMon, err := netmon.New(logf)
+	bus := eventbus.New()
+	defer bus.Close()
+
+	netMon, err := netmon.New(bus, logf)
 	if err != nil {
 		t.Fatalf("netmon.New: %v", err)
 	}
@@ -390,7 +394,10 @@ func TestNewConn(t *testing.T) {
 		}
 	}
 
-	netMon, err := netmon.New(logger.WithPrefix(t.Logf, "... netmon: "))
+	bus := eventbus.New()
+	defer bus.Close()
+
+	netMon, err := netmon.New(bus, logger.WithPrefix(t.Logf, "... netmon: "))
 	if err != nil {
 		t.Fatalf("netmon.New: %v", err)
 	}
@@ -523,7 +530,10 @@ func TestDeviceStartStop(t *testing.T) {
 	tstest.PanicOnLog()
 	tstest.ResourceCheck(t)
 
-	netMon, err := netmon.New(logger.WithPrefix(t.Logf, "... netmon: "))
+	bus := eventbus.New()
+	defer bus.Close()
+
+	netMon, err := netmon.New(bus, logger.WithPrefix(t.Logf, "... netmon: "))
 	if err != nil {
 		t.Fatalf("netmon.New: %v", err)
 	}
@@ -1362,7 +1372,10 @@ func newTestConn(t testing.TB) *Conn {
 	t.Helper()
 	port := pickPort(t)
 
-	netMon, err := netmon.New(logger.WithPrefix(t.Logf, "... netmon: "))
+	bus := eventbus.New()
+	defer bus.Close()
+
+	netMon, err := netmon.New(bus, logger.WithPrefix(t.Logf, "... netmon: "))
 	if err != nil {
 		t.Fatalf("netmon.New: %v", err)
 	}
@@ -3117,7 +3130,10 @@ func TestMaybeRebindOnError(t *testing.T) {
 }
 
 func TestNetworkDownSendErrors(t *testing.T) {
-	netMon := must.Get(netmon.New(t.Logf))
+	bus := eventbus.New()
+	defer bus.Close()
+
+	netMon := must.Get(netmon.New(bus, t.Logf))
 	defer netMon.Close()
 
 	reg := new(usermetric.Registry)

wgengine/netstack/netstack_test.go

@@ -51,6 +51,7 @@ func TestInjectInboundLeak(t *testing.T) {
 		SetSubsystem:  sys.Set,
 		HealthTracker: sys.HealthTracker(),
 		Metrics:       sys.UserMetricsRegistry(),
+		EventBus:      sys.Bus.Get(),
 	})
 	if err != nil {
 		t.Fatal(err)
@@ -110,6 +111,7 @@ func makeNetstack(tb testing.TB, config func(*Impl)) *Impl {
 		SetSubsystem:  sys.Set,
 		HealthTracker: sys.HealthTracker(),
 		Metrics:       sys.UserMetricsRegistry(),
+		EventBus:      sys.Bus.Get(),
 	})
 	if err != nil {
 		tb.Fatal(err)

wgengine/router/router_linux_test.go

@@ -27,6 +27,7 @@ import (
 	"tailscale.com/net/tsaddr"
 	"tailscale.com/tstest"
 	"tailscale.com/types/logger"
+	"tailscale.com/util/eventbus"
 	"tailscale.com/util/linuxfw"
 	"tailscale.com/version/distro"
 )
@@ -363,7 +364,9 @@ ip route add throw 192.168.0.0/24 table 52` + basic,
 		},
 	}
 
-	mon, err := netmon.New(logger.Discard)
+	bus := eventbus.New()
+	defer bus.Close()
+	mon, err := netmon.New(bus, logger.Discard)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -973,7 +976,10 @@ func newLinuxRootTest(t *testing.T) *linuxTest {
 
 	logf := lt.logOutput.Logf
 
-	mon, err := netmon.New(logger.Discard)
+	bus := eventbus.New()
+	defer bus.Close()
+
+	mon, err := netmon.New(bus, logger.Discard)
 	if err != nil {
 		lt.Close()
 		t.Fatal(err)

wgengine/userspace.go

@@ -363,7 +363,7 @@ func NewUserspaceEngine(logf logger.Logf, conf Config) (_ Engine, reterr error)
 	if conf.NetMon != nil {
 		e.netMon = conf.NetMon
 	} else {
-		mon, err := netmon.New(logf)
+		mon, err := netmon.New(conf.EventBus, logf)
 		if err != nil {
 			return nil, err
 		}

wgengine/userspace_ext_test.go

@@ -23,6 +23,7 @@ func TestIsNetstack(t *testing.T) {
 			SetSubsystem:  sys.Set,
 			HealthTracker: sys.HealthTracker(),
 			Metrics:       sys.UserMetricsRegistry(),
+			EventBus:      sys.Bus.Get(),
 		},
 	)
 	if err != nil {
@@ -74,6 +75,7 @@ func TestIsNetstackRouter(t *testing.T) {
 			conf.SetSubsystem = sys.Set
 			conf.HealthTracker = sys.HealthTracker()
 			conf.Metrics = sys.UserMetricsRegistry()
+			conf.EventBus = sys.Bus.Get()
 			e, err := wgengine.NewUserspaceEngine(logger.Discard, conf)
 			if err != nil {
 				t.Fatal(err)

wgengine/userspace_test.go

@@ -25,6 +25,7 @@ import (
 	"tailscale.com/types/key"
 	"tailscale.com/types/netmap"
 	"tailscale.com/types/opt"
+	"tailscale.com/util/eventbus"
 	"tailscale.com/util/usermetric"
 	"tailscale.com/wgengine/router"
 	"tailscale.com/wgengine/wgcfg"
@@ -100,9 +101,12 @@ func nodeViews(v []*tailcfg.Node) []tailcfg.NodeView {
 }
 
 func TestUserspaceEngineReconfig(t *testing.T) {
+	bus := eventbus.New()
+	defer bus.Close()
+
 	ht := new(health.Tracker)
 	reg := new(usermetric.Registry)
-	e, err := NewFakeUserspaceEngine(t.Logf, 0, ht, reg)
+	e, err := NewFakeUserspaceEngine(t.Logf, 0, ht, reg, bus)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -166,13 +170,16 @@ func TestUserspaceEnginePortReconfig(t *testing.T) {
 
 	var knobs controlknobs.Knobs
 
+	bus := eventbus.New()
+	defer bus.Close()
+
 	// Keep making a wgengine until we find an unused port
 	var ue *userspaceEngine
 	ht := new(health.Tracker)
 	reg := new(usermetric.Registry)
 	for i := range 100 {
 		attempt := uint16(defaultPort + i)
-		e, err := NewFakeUserspaceEngine(t.Logf, attempt, &knobs, ht, reg)
+		e, err := NewFakeUserspaceEngine(t.Logf, attempt, &knobs, ht, reg, bus)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -251,9 +258,11 @@ func TestUserspaceEnginePeerMTUReconfig(t *testing.T) {
 
 	var knobs controlknobs.Knobs
 
+	bus := eventbus.New()
+	defer bus.Close()
 	ht := new(health.Tracker)
 	reg := new(usermetric.Registry)
-	e, err := NewFakeUserspaceEngine(t.Logf, 0, &knobs, ht, reg)
+	e, err := NewFakeUserspaceEngine(t.Logf, 0, &knobs, ht, reg, bus)
 	if err != nil {
 		t.Fatal(err)
 	}

wgengine/watchdog_test.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"tailscale.com/health"
+	"tailscale.com/util/eventbus"
 	"tailscale.com/util/usermetric"
 )
 
@@ -24,9 +25,11 @@ func TestWatchdog(t *testing.T) {
 
 	t.Run("default watchdog does not fire", func(t *testing.T) {
 		t.Parallel()
+		bus := eventbus.New()
+		defer bus.Close()
 		ht := new(health.Tracker)
 		reg := new(usermetric.Registry)
-		e, err := NewFakeUserspaceEngine(t.Logf, 0, ht, reg)
+		e, err := NewFakeUserspaceEngine(t.Logf, 0, ht, reg, bus)
 		if err != nil {
 			t.Fatal(err)
 		}