Merge 36194a037e into 4dece0c359

I'm working on moving all network state queries to be on
netmon.Monitor, removing old APIs.

Updates tailscale/corp#10910
Updates tailscale/corp#18960
Updates #7967
Updates #3299

Change-Id: If0de137e0e2e145520f69e258597fb89cf39a2a3
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

appc/appconnector.go

@@ -23,6 +23,7 @@ import (
 	"tailscale.com/util/dnsname"
 	"tailscale.com/util/execqueue"
 	"tailscale.com/util/mak"
+	"tailscale.com/util/slicesx"
 )
 
 // RouteAdvertiser is an interface that allows the AppConnector to advertise
@@ -36,6 +37,19 @@ type RouteAdvertiser interface {
 	UnadvertiseRoute(...netip.Prefix) error
 }
 
+// RouteInfo is a data structure used to persist the in memory state of an AppConnector
+// so that we can know, even after a restart, which routes came from ACLs and which were
+// learned from domains.
+type RouteInfo struct {
+	// Control is the routes from the 'routes' section of an app connector acl.
+	Control []netip.Prefix `json:",omitempty"`
+	// Domains are the routes discovered by observing DNS lookups for configured domains.
+	Domains map[string][]netip.Addr `json:",omitempty"`
+	// Wildcards are the configured DNS lookup domains to observe. When a DNS query matches Wildcards,
+	// its result is added to Domains.
+	Wildcards []string `json:",omitempty"`
+}
+
 // AppConnector is an implementation of an AppConnector that performs
 // its function as a subsystem inside of a tailscale node. At the control plane
 // side App Connector routing is configured in terms of domains rather than IP
@@ -49,6 +63,9 @@ type AppConnector struct {
 	logf            logger.Logf
 	routeAdvertiser RouteAdvertiser
 
+	// storeRoutesFunc will be called to persist routes if it is not nil.
+	storeRoutesFunc func(*RouteInfo) error
+
 	// mu guards the fields that follow
 	mu sync.Mutex
 
@@ -67,11 +84,46 @@ type AppConnector struct {
 }
 
 // NewAppConnector creates a new AppConnector.
-func NewAppConnector(logf logger.Logf, routeAdvertiser RouteAdvertiser) *AppConnector {
-	return &AppConnector{
+func NewAppConnector(logf logger.Logf, routeAdvertiser RouteAdvertiser, routeInfo *RouteInfo, storeRoutesFunc func(*RouteInfo) error) *AppConnector {
+	ac := &AppConnector{
 		logf:            logger.WithPrefix(logf, "appc: "),
 		routeAdvertiser: routeAdvertiser,
+		storeRoutesFunc: storeRoutesFunc,
 	}
+	if routeInfo != nil {
+		ac.domains = routeInfo.Domains
+		ac.wildcards = routeInfo.Wildcards
+		ac.controlRoutes = routeInfo.Control
+	}
+	return ac
+}
+
+// ShouldStoreRoutes returns true if the appconnector was created with the controlknob on
+// and is storing its discovered routes persistently.
+func (e *AppConnector) ShouldStoreRoutes() bool {
+	return e.storeRoutesFunc != nil
+}
+
+// storeRoutesLocked takes the current state of the AppConnector and persists it
+func (e *AppConnector) storeRoutesLocked() error {
+	if !e.ShouldStoreRoutes() {
+		return nil
+	}
+	return e.storeRoutesFunc(&RouteInfo{
+		Control:   e.controlRoutes,
+		Domains:   e.domains,
+		Wildcards: e.wildcards,
+	})
+}
+
+// ClearRoutes removes all route state from the AppConnector.
+func (e *AppConnector) ClearRoutes() error {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	e.controlRoutes = nil
+	e.domains = nil
+	e.wildcards = nil
+	return e.storeRoutesLocked()
 }
 
 // UpdateDomainsAndRoutes starts an asynchronous update of the configuration
@@ -125,10 +177,26 @@ func (e *AppConnector) updateDomains(domains []string) {
 		for _, wc := range e.wildcards {
 			if dnsname.HasSuffix(d, wc) {
 				e.domains[d] = addrs
+				delete(oldDomains, d)
 				break
 			}
 		}
 	}
+
+	// Everything left in oldDomains is a domain we're no longer tracking
+	// and if we are storing route info we can unadvertise the routes
+	if e.ShouldStoreRoutes() {
+		toRemove := []netip.Prefix{}
+		for _, addrs := range oldDomains {
+			for _, a := range addrs {
+				toRemove = append(toRemove, netip.PrefixFrom(a, a.BitLen()))
+			}
+		}
+		if err := e.routeAdvertiser.UnadvertiseRoute(toRemove...); err != nil {
+			e.logf("failed to unadvertise routes on domain removal: %v: %v: %v", xmaps.Keys(oldDomains), toRemove, err)
+		}
+	}
+
 	e.logf("handling domains: %v and wildcards: %v", xmaps.Keys(e.domains), e.wildcards)
 }
 
@@ -152,6 +220,14 @@ func (e *AppConnector) updateRoutes(routes []netip.Prefix) {
 
 	var toRemove []netip.Prefix
 
+	// If we're storing routes and know e.controlRoutes is a good
+	// representation of what should be in AdvertisedRoutes we can stop
+	// advertising routes that used to be in e.controlRoutes but are not
+	// in routes.
+	if e.ShouldStoreRoutes() {
+		toRemove = routesWithout(e.controlRoutes, routes)
+	}
+
 nextRoute:
 	for _, r := range routes {
 		for _, addr := range e.domains {
@@ -170,6 +246,9 @@ nextRoute:
 	}
 
 	e.controlRoutes = routes
+	if err := e.storeRoutesLocked(); err != nil {
+		e.logf("failed to store route info: %v", err)
+	}
 }
 
 // Domains returns the currently configured domain list.
@@ -380,6 +459,9 @@ func (e *AppConnector) scheduleAdvertisement(domain string, routes ...netip.Pref
 				e.logf("[v2] advertised route for %v: %v", domain, addr)
 			}
 		}
+		if err := e.storeRoutesLocked(); err != nil {
+			e.logf("failed to store route info: %v", err)
+		}
 	})
 }
 
@@ -400,3 +482,15 @@ func (e *AppConnector) addDomainAddrLocked(domain string, addr netip.Addr) {
 func compareAddr(l, r netip.Addr) int {
 	return l.Compare(r)
 }
+
+// routesWithout returns a without b where a and b
+// are unsorted slices of netip.Prefix
+func routesWithout(a, b []netip.Prefix) []netip.Prefix {
+	m := make(map[netip.Prefix]bool, len(b))
+	for _, p := range b {
+		m[p] = true
+	}
+	return slicesx.Filter(make([]netip.Prefix, 0, len(a)), a, func(p netip.Prefix) bool {
+		return !m[p]
+	})
+}

appc/appconnector_test.go

@@ -17,194 +17,238 @@ import (
 	"tailscale.com/util/must"
 )
 
+func fakeStoreRoutes(*RouteInfo) error { return nil }
+
 func TestUpdateDomains(t *testing.T) {
-	ctx := context.Background()
-	a := NewAppConnector(t.Logf, nil)
-	a.UpdateDomains([]string{"example.com"})
+	for _, shouldStore := range []bool{false, true} {
+		ctx := context.Background()
+		var a *AppConnector
+		if shouldStore {
+			a = NewAppConnector(t.Logf, &appctest.RouteCollector{}, &RouteInfo{}, fakeStoreRoutes)
+		} else {
+			a = NewAppConnector(t.Logf, &appctest.RouteCollector{}, nil, nil)
+		}
+		a.UpdateDomains([]string{"example.com"})
 
-	a.Wait(ctx)
-	if got, want := a.Domains().AsSlice(), []string{"example.com"}; !slices.Equal(got, want) {
-		t.Errorf("got %v; want %v", got, want)
-	}
+		a.Wait(ctx)
+		if got, want := a.Domains().AsSlice(), []string{"example.com"}; !slices.Equal(got, want) {
+			t.Errorf("got %v; want %v", got, want)
+		}
 
-	addr := netip.MustParseAddr("192.0.0.8")
-	a.domains["example.com"] = append(a.domains["example.com"], addr)
-	a.UpdateDomains([]string{"example.com"})
-	a.Wait(ctx)
+		addr := netip.MustParseAddr("192.0.0.8")
+		a.domains["example.com"] = append(a.domains["example.com"], addr)
+		a.UpdateDomains([]string{"example.com"})
+		a.Wait(ctx)
 
-	if got, want := a.domains["example.com"], []netip.Addr{addr}; !slices.Equal(got, want) {
-		t.Errorf("got %v; want %v", got, want)
-	}
+		if got, want := a.domains["example.com"], []netip.Addr{addr}; !slices.Equal(got, want) {
+			t.Errorf("got %v; want %v", got, want)
+		}
 
-	// domains are explicitly downcased on set.
-	a.UpdateDomains([]string{"UP.EXAMPLE.COM"})
-	a.Wait(ctx)
-	if got, want := xmaps.Keys(a.domains), []string{"up.example.com"}; !slices.Equal(got, want) {
-		t.Errorf("got %v; want %v", got, want)
+		// domains are explicitly downcased on set.
+		a.UpdateDomains([]string{"UP.EXAMPLE.COM"})
+		a.Wait(ctx)
+		if got, want := xmaps.Keys(a.domains), []string{"up.example.com"}; !slices.Equal(got, want) {
+			t.Errorf("got %v; want %v", got, want)
+		}
 	}
 }
 
 func TestUpdateRoutes(t *testing.T) {
-	ctx := context.Background()
-	rc := &appctest.RouteCollector{}
-	a := NewAppConnector(t.Logf, rc)
-	a.updateDomains([]string{"*.example.com"})
+	for _, shouldStore := range []bool{false, true} {
+		ctx := context.Background()
+		rc := &appctest.RouteCollector{}
+		var a *AppConnector
+		if shouldStore {
+			a = NewAppConnector(t.Logf, rc, &RouteInfo{}, fakeStoreRoutes)
+		} else {
+			a = NewAppConnector(t.Logf, rc, nil, nil)
+		}
+		a.updateDomains([]string{"*.example.com"})
 
-	// This route should be collapsed into the range
-	a.ObserveDNSResponse(dnsResponse("a.example.com.", "192.0.2.1"))
-	a.Wait(ctx)
+		// This route should be collapsed into the range
+		a.ObserveDNSResponse(dnsResponse("a.example.com.", "192.0.2.1"))
+		a.Wait(ctx)
 
-	if !slices.Equal(rc.Routes(), []netip.Prefix{netip.MustParsePrefix("192.0.2.1/32")}) {
-		t.Fatalf("got %v, want %v", rc.Routes(), []netip.Prefix{netip.MustParsePrefix("192.0.2.1/32")})
-	}
+		if !slices.Equal(rc.Routes(), []netip.Prefix{netip.MustParsePrefix("192.0.2.1/32")}) {
+			t.Fatalf("got %v, want %v", rc.Routes(), []netip.Prefix{netip.MustParsePrefix("192.0.2.1/32")})
+		}
 
-	// This route should not be collapsed or removed
-	a.ObserveDNSResponse(dnsResponse("b.example.com.", "192.0.0.1"))
-	a.Wait(ctx)
+		// This route should not be collapsed or removed
+		a.ObserveDNSResponse(dnsResponse("b.example.com.", "192.0.0.1"))
+		a.Wait(ctx)
 
-	routes := []netip.Prefix{netip.MustParsePrefix("192.0.2.0/24"), netip.MustParsePrefix("192.0.0.1/32")}
-	a.updateRoutes(routes)
+		routes := []netip.Prefix{netip.MustParsePrefix("192.0.2.0/24"), netip.MustParsePrefix("192.0.0.1/32")}
+		a.updateRoutes(routes)
 
-	slices.SortFunc(rc.Routes(), prefixCompare)
-	rc.SetRoutes(slices.Compact(rc.Routes()))
-	slices.SortFunc(routes, prefixCompare)
+		slices.SortFunc(rc.Routes(), prefixCompare)
+		rc.SetRoutes(slices.Compact(rc.Routes()))
+		slices.SortFunc(routes, prefixCompare)
 
-	// Ensure that the non-matching /32 is preserved, even though it's in the domains table.
-	if !slices.EqualFunc(routes, rc.Routes(), prefixEqual) {
-		t.Errorf("added routes: got %v, want %v", rc.Routes(), routes)
-	}
+		// Ensure that the non-matching /32 is preserved, even though it's in the domains table.
+		if !slices.EqualFunc(routes, rc.Routes(), prefixEqual) {
+			t.Errorf("added routes: got %v, want %v", rc.Routes(), routes)
+		}
 
-	// Ensure that the contained /32 is removed, replaced by the /24.
-	wantRemoved := []netip.Prefix{netip.MustParsePrefix("192.0.2.1/32")}
-	if !slices.EqualFunc(rc.RemovedRoutes(), wantRemoved, prefixEqual) {
-		t.Fatalf("unexpected removed routes: %v", rc.RemovedRoutes())
+		// Ensure that the contained /32 is removed, replaced by the /24.
+		wantRemoved := []netip.Prefix{netip.MustParsePrefix("192.0.2.1/32")}
+		if !slices.EqualFunc(rc.RemovedRoutes(), wantRemoved, prefixEqual) {
+			t.Fatalf("unexpected removed routes: %v", rc.RemovedRoutes())
+		}
 	}
 }
 
 func TestUpdateRoutesUnadvertisesContainedRoutes(t *testing.T) {
-	rc := &appctest.RouteCollector{}
-	a := NewAppConnector(t.Logf, rc)
-	mak.Set(&a.domains, "example.com", []netip.Addr{netip.MustParseAddr("192.0.2.1")})
-	rc.SetRoutes([]netip.Prefix{netip.MustParsePrefix("192.0.2.1/32")})
-	routes := []netip.Prefix{netip.MustParsePrefix("192.0.2.0/24")}
-	a.updateRoutes(routes)
+	for _, shouldStore := range []bool{false, true} {
+		rc := &appctest.RouteCollector{}
+		var a *AppConnector
+		if shouldStore {
+			a = NewAppConnector(t.Logf, rc, &RouteInfo{}, fakeStoreRoutes)
+		} else {
+			a = NewAppConnector(t.Logf, rc, nil, nil)
+		}
+		mak.Set(&a.domains, "example.com", []netip.Addr{netip.MustParseAddr("192.0.2.1")})
+		rc.SetRoutes([]netip.Prefix{netip.MustParsePrefix("192.0.2.1/32")})
+		routes := []netip.Prefix{netip.MustParsePrefix("192.0.2.0/24")}
+		a.updateRoutes(routes)
 
-	if !slices.EqualFunc(routes, rc.Routes(), prefixEqual) {
-		t.Fatalf("got %v, want %v", rc.Routes(), routes)
+		if !slices.EqualFunc(routes, rc.Routes(), prefixEqual) {
+			t.Fatalf("got %v, want %v", rc.Routes(), routes)
+		}
 	}
 }
 
 func TestDomainRoutes(t *testing.T) {
-	rc := &appctest.RouteCollector{}
-	a := NewAppConnector(t.Logf, rc)
-	a.updateDomains([]string{"example.com"})
-	a.ObserveDNSResponse(dnsResponse("example.com.", "192.0.0.8"))
-	a.Wait(context.Background())
+	for _, shouldStore := range []bool{false, true} {
+		rc := &appctest.RouteCollector{}
+		var a *AppConnector
+		if shouldStore {
+			a = NewAppConnector(t.Logf, rc, &RouteInfo{}, fakeStoreRoutes)
+		} else {
+			a = NewAppConnector(t.Logf, rc, nil, nil)
+		}
+		a.updateDomains([]string{"example.com"})
+		a.ObserveDNSResponse(dnsResponse("example.com.", "192.0.0.8"))
+		a.Wait(context.Background())
 
-	want := map[string][]netip.Addr{
-		"example.com": {netip.MustParseAddr("192.0.0.8")},
-	}
+		want := map[string][]netip.Addr{
+			"example.com": {netip.MustParseAddr("192.0.0.8")},
+		}
 
-	if got := a.DomainRoutes(); !reflect.DeepEqual(got, want) {
-		t.Fatalf("DomainRoutes: got %v, want %v", got, want)
+		if got := a.DomainRoutes(); !reflect.DeepEqual(got, want) {
+			t.Fatalf("DomainRoutes: got %v, want %v", got, want)
+		}
 	}
 }
 
 func TestObserveDNSResponse(t *testing.T) {
-	ctx := context.Background()
-	rc := &appctest.RouteCollector{}
-	a := NewAppConnector(t.Logf, rc)
+	for _, shouldStore := range []bool{false, true} {
+		ctx := context.Background()
+		rc := &appctest.RouteCollector{}
+		var a *AppConnector
+		if shouldStore {
+			a = NewAppConnector(t.Logf, rc, &RouteInfo{}, fakeStoreRoutes)
+		} else {
+			a = NewAppConnector(t.Logf, rc, nil, nil)
+		}
 
-	// a has no domains configured, so it should not advertise any routes
-	a.ObserveDNSResponse(dnsResponse("example.com.", "192.0.0.8"))
-	if got, want := rc.Routes(), ([]netip.Prefix)(nil); !slices.Equal(got, want) {
-		t.Errorf("got %v; want %v", got, want)
-	}
+		// a has no domains configured, so it should not advertise any routes
+		a.ObserveDNSResponse(dnsResponse("example.com.", "192.0.0.8"))
+		if got, want := rc.Routes(), ([]netip.Prefix)(nil); !slices.Equal(got, want) {
+			t.Errorf("got %v; want %v", got, want)
+		}
 
-	wantRoutes := []netip.Prefix{netip.MustParsePrefix("192.0.0.8/32")}
+		wantRoutes := []netip.Prefix{netip.MustParsePrefix("192.0.0.8/32")}
 
-	a.updateDomains([]string{"example.com"})
-	a.ObserveDNSResponse(dnsResponse("example.com.", "192.0.0.8"))
-	a.Wait(ctx)
-	if got, want := rc.Routes(), wantRoutes; !slices.Equal(got, want) {
-		t.Errorf("got %v; want %v", got, want)
-	}
+		a.updateDomains([]string{"example.com"})
+		a.ObserveDNSResponse(dnsResponse("example.com.", "192.0.0.8"))
+		a.Wait(ctx)
+		if got, want := rc.Routes(), wantRoutes; !slices.Equal(got, want) {
+			t.Errorf("got %v; want %v", got, want)
+		}
 
-	// a CNAME record chain should result in a route being added if the chain
-	// matches a routed domain.
-	a.updateDomains([]string{"www.example.com", "example.com"})
-	a.ObserveDNSResponse(dnsCNAMEResponse("192.0.0.9", "www.example.com.", "chain.example.com.", "example.com."))
-	a.Wait(ctx)
-	wantRoutes = append(wantRoutes, netip.MustParsePrefix("192.0.0.9/32"))
-	if got, want := rc.Routes(), wantRoutes; !slices.Equal(got, want) {
-		t.Errorf("got %v; want %v", got, want)
-	}
+		// a CNAME record chain should result in a route being added if the chain
+		// matches a routed domain.
+		a.updateDomains([]string{"www.example.com", "example.com"})
+		a.ObserveDNSResponse(dnsCNAMEResponse("192.0.0.9", "www.example.com.", "chain.example.com.", "example.com."))
+		a.Wait(ctx)
+		wantRoutes = append(wantRoutes, netip.MustParsePrefix("192.0.0.9/32"))
+		if got, want := rc.Routes(), wantRoutes; !slices.Equal(got, want) {
+			t.Errorf("got %v; want %v", got, want)
+		}
 
-	// a CNAME record chain should result in a route being added if the chain
-	// even if only found in the middle of the chain
-	a.ObserveDNSResponse(dnsCNAMEResponse("192.0.0.10", "outside.example.org.", "www.example.com.", "example.org."))
-	a.Wait(ctx)
-	wantRoutes = append(wantRoutes, netip.MustParsePrefix("192.0.0.10/32"))
-	if got, want := rc.Routes(), wantRoutes; !slices.Equal(got, want) {
-		t.Errorf("got %v; want %v", got, want)
-	}
+		// a CNAME record chain should result in a route being added if the chain
+		// even if only found in the middle of the chain
+		a.ObserveDNSResponse(dnsCNAMEResponse("192.0.0.10", "outside.example.org.", "www.example.com.", "example.org."))
+		a.Wait(ctx)
+		wantRoutes = append(wantRoutes, netip.MustParsePrefix("192.0.0.10/32"))
+		if got, want := rc.Routes(), wantRoutes; !slices.Equal(got, want) {
+			t.Errorf("got %v; want %v", got, want)
+		}
 
-	wantRoutes = append(wantRoutes, netip.MustParsePrefix("2001:db8::1/128"))
+		wantRoutes = append(wantRoutes, netip.MustParsePrefix("2001:db8::1/128"))
 
-	a.ObserveDNSResponse(dnsResponse("example.com.", "2001:db8::1"))
-	a.Wait(ctx)
-	if got, want := rc.Routes(), wantRoutes; !slices.Equal(got, want) {
-		t.Errorf("got %v; want %v", got, want)
-	}
+		a.ObserveDNSResponse(dnsResponse("example.com.", "2001:db8::1"))
+		a.Wait(ctx)
+		if got, want := rc.Routes(), wantRoutes; !slices.Equal(got, want) {
+			t.Errorf("got %v; want %v", got, want)
+		}
 
-	// don't re-advertise routes that have already been advertised
-	a.ObserveDNSResponse(dnsResponse("example.com.", "2001:db8::1"))
-	a.Wait(ctx)
-	if !slices.Equal(rc.Routes(), wantRoutes) {
-		t.Errorf("rc.Routes(): got %v; want %v", rc.Routes(), wantRoutes)
-	}
+		// don't re-advertise routes that have already been advertised
+		a.ObserveDNSResponse(dnsResponse("example.com.", "2001:db8::1"))
+		a.Wait(ctx)
+		if !slices.Equal(rc.Routes(), wantRoutes) {
+			t.Errorf("rc.Routes(): got %v; want %v", rc.Routes(), wantRoutes)
+		}
 
-	// don't advertise addresses that are already in a control provided route
-	pfx := netip.MustParsePrefix("192.0.2.0/24")
-	a.updateRoutes([]netip.Prefix{pfx})
-	wantRoutes = append(wantRoutes, pfx)
-	a.ObserveDNSResponse(dnsResponse("example.com.", "192.0.2.1"))
-	a.Wait(ctx)
-	if !slices.Equal(rc.Routes(), wantRoutes) {
-		t.Errorf("rc.Routes(): got %v; want %v", rc.Routes(), wantRoutes)
-	}
-	if !slices.Contains(a.domains["example.com"], netip.MustParseAddr("192.0.2.1")) {
-		t.Errorf("missing %v from %v", "192.0.2.1", a.domains["exmaple.com"])
+		// don't advertise addresses that are already in a control provided route
+		pfx := netip.MustParsePrefix("192.0.2.0/24")
+		a.updateRoutes([]netip.Prefix{pfx})
+		wantRoutes = append(wantRoutes, pfx)
+		a.ObserveDNSResponse(dnsResponse("example.com.", "192.0.2.1"))
+		a.Wait(ctx)
+		if !slices.Equal(rc.Routes(), wantRoutes) {
+			t.Errorf("rc.Routes(): got %v; want %v", rc.Routes(), wantRoutes)
+		}
+		if !slices.Contains(a.domains["example.com"], netip.MustParseAddr("192.0.2.1")) {
+			t.Errorf("missing %v from %v", "192.0.2.1", a.domains["exmaple.com"])
+		}
 	}
 }
 
 func TestWildcardDomains(t *testing.T) {
-	ctx := context.Background()
-	rc := &appctest.RouteCollector{}
-	a := NewAppConnector(t.Logf, rc)
+	for _, shouldStore := range []bool{false, true} {
+		ctx := context.Background()
+		rc := &appctest.RouteCollector{}
+		var a *AppConnector
+		if shouldStore {
+			a = NewAppConnector(t.Logf, rc, &RouteInfo{}, fakeStoreRoutes)
+		} else {
+			a = NewAppConnector(t.Logf, rc, nil, nil)
+		}
 
-	a.updateDomains([]string{"*.example.com"})
-	a.ObserveDNSResponse(dnsResponse("foo.example.com.", "192.0.0.8"))
-	a.Wait(ctx)
-	if got, want := rc.Routes(), []netip.Prefix{netip.MustParsePrefix("192.0.0.8/32")}; !slices.Equal(got, want) {
-		t.Errorf("routes: got %v; want %v", got, want)
-	}
-	if got, want := a.wildcards, []string{"example.com"}; !slices.Equal(got, want) {
-		t.Errorf("wildcards: got %v; want %v", got, want)
-	}
+		a.updateDomains([]string{"*.example.com"})
+		a.ObserveDNSResponse(dnsResponse("foo.example.com.", "192.0.0.8"))
+		a.Wait(ctx)
+		if got, want := rc.Routes(), []netip.Prefix{netip.MustParsePrefix("192.0.0.8/32")}; !slices.Equal(got, want) {
+			t.Errorf("routes: got %v; want %v", got, want)
+		}
+		if got, want := a.wildcards, []string{"example.com"}; !slices.Equal(got, want) {
+			t.Errorf("wildcards: got %v; want %v", got, want)
+		}
 
-	a.updateDomains([]string{"*.example.com", "example.com"})
-	if _, ok := a.domains["foo.example.com"]; !ok {
-		t.Errorf("expected foo.example.com to be preserved in domains due to wildcard")
-	}
-	if got, want := a.wildcards, []string{"example.com"}; !slices.Equal(got, want) {
-		t.Errorf("wildcards: got %v; want %v", got, want)
-	}
+		a.updateDomains([]string{"*.example.com", "example.com"})
+		if _, ok := a.domains["foo.example.com"]; !ok {
+			t.Errorf("expected foo.example.com to be preserved in domains due to wildcard")
+		}
+		if got, want := a.wildcards, []string{"example.com"}; !slices.Equal(got, want) {
+			t.Errorf("wildcards: got %v; want %v", got, want)
+		}
 
-	// There was an early regression where the wildcard domain was added repeatedly, this guards against that.
-	a.updateDomains([]string{"*.example.com", "example.com"})
-	if len(a.wildcards) != 1 {
-		t.Errorf("expected only one wildcard domain, got %v", a.wildcards)
+		// There was an early regression where the wildcard domain was added repeatedly, this guards against that.
+		a.updateDomains([]string{"*.example.com", "example.com"})
+		if len(a.wildcards) != 1 {
+			t.Errorf("expected only one wildcard domain, got %v", a.wildcards)
+		}
 	}
 }
 
@@ -310,3 +354,169 @@ func prefixCompare(a, b netip.Prefix) int {
 	}
 	return a.Addr().Compare(b.Addr())
 }
+
+func prefixes(in ...string) []netip.Prefix {
+	toRet := make([]netip.Prefix, len(in))
+	for i, s := range in {
+		toRet[i] = netip.MustParsePrefix(s)
+	}
+	return toRet
+}
+
+func TestUpdateRouteRouteRemoval(t *testing.T) {
+	for _, shouldStore := range []bool{false, true} {
+		ctx := context.Background()
+		rc := &appctest.RouteCollector{}
+
+		assertRoutes := func(prefix string, routes, removedRoutes []netip.Prefix) {
+			if !slices.Equal(routes, rc.Routes()) {
+				t.Fatalf("%s: (shouldStore=%t) routes want %v, got %v", prefix, shouldStore, routes, rc.Routes())
+			}
+			if !slices.Equal(removedRoutes, rc.RemovedRoutes()) {
+				t.Fatalf("%s: (shouldStore=%t) removedRoutes want %v, got %v", prefix, shouldStore, removedRoutes, rc.RemovedRoutes())
+			}
+		}
+
+		var a *AppConnector
+		if shouldStore {
+			a = NewAppConnector(t.Logf, rc, &RouteInfo{}, fakeStoreRoutes)
+		} else {
+			a = NewAppConnector(t.Logf, rc, nil, nil)
+		}
+		// nothing has yet been advertised
+		assertRoutes("appc init", []netip.Prefix{}, []netip.Prefix{})
+
+		a.UpdateDomainsAndRoutes([]string{}, prefixes("1.2.3.1/32", "1.2.3.2/32"))
+		a.Wait(ctx)
+		// the routes passed to UpdateDomainsAndRoutes have been advertised
+		assertRoutes("simple update", prefixes("1.2.3.1/32", "1.2.3.2/32"), []netip.Prefix{})
+
+		// one route the same, one different
+		a.UpdateDomainsAndRoutes([]string{}, prefixes("1.2.3.1/32", "1.2.3.3/32"))
+		a.Wait(ctx)
+		// old behavior: routes are not removed, resulting routes are both old and new
+		// (we have dupe 1.2.3.1 routes because the test RouteAdvertiser doesn't have the deduplication
+		// the real one does)
+		wantRoutes := prefixes("1.2.3.1/32", "1.2.3.2/32", "1.2.3.1/32", "1.2.3.3/32")
+		wantRemovedRoutes := []netip.Prefix{}
+		if shouldStore {
+			// new behavior: routes are removed, resulting routes are new only
+			wantRoutes = prefixes("1.2.3.1/32", "1.2.3.1/32", "1.2.3.3/32")
+			wantRemovedRoutes = prefixes("1.2.3.2/32")
+		}
+		assertRoutes("removal", wantRoutes, wantRemovedRoutes)
+	}
+}
+
+func TestUpdateDomainRouteRemoval(t *testing.T) {
+	for _, shouldStore := range []bool{false, true} {
+		ctx := context.Background()
+		rc := &appctest.RouteCollector{}
+
+		assertRoutes := func(prefix string, routes, removedRoutes []netip.Prefix) {
+			if !slices.Equal(routes, rc.Routes()) {
+				t.Fatalf("%s: (shouldStore=%t) routes want %v, got %v", prefix, shouldStore, routes, rc.Routes())
+			}
+			if !slices.Equal(removedRoutes, rc.RemovedRoutes()) {
+				t.Fatalf("%s: (shouldStore=%t) removedRoutes want %v, got %v", prefix, shouldStore, removedRoutes, rc.RemovedRoutes())
+			}
+		}
+
+		var a *AppConnector
+		if shouldStore {
+			a = NewAppConnector(t.Logf, rc, &RouteInfo{}, fakeStoreRoutes)
+		} else {
+			a = NewAppConnector(t.Logf, rc, nil, nil)
+		}
+		assertRoutes("appc init", []netip.Prefix{}, []netip.Prefix{})
+
+		a.UpdateDomainsAndRoutes([]string{"a.example.com", "b.example.com"}, []netip.Prefix{})
+		a.Wait(ctx)
+		// adding domains doesn't immediately cause any routes to be advertised
+		assertRoutes("update domains", []netip.Prefix{}, []netip.Prefix{})
+
+		a.ObserveDNSResponse(dnsResponse("a.example.com.", "1.2.3.1"))
+		a.ObserveDNSResponse(dnsResponse("a.example.com.", "1.2.3.2"))
+		a.ObserveDNSResponse(dnsResponse("b.example.com.", "1.2.3.3"))
+		a.ObserveDNSResponse(dnsResponse("b.example.com.", "1.2.3.4"))
+		a.Wait(ctx)
+		// observing dns responses causes routes to be advertised
+		assertRoutes("observed dns", prefixes("1.2.3.1/32", "1.2.3.2/32", "1.2.3.3/32", "1.2.3.4/32"), []netip.Prefix{})
+
+		a.UpdateDomainsAndRoutes([]string{"a.example.com"}, []netip.Prefix{})
+		a.Wait(ctx)
+		// old behavior, routes are not removed
+		wantRoutes := prefixes("1.2.3.1/32", "1.2.3.2/32", "1.2.3.3/32", "1.2.3.4/32")
+		wantRemovedRoutes := []netip.Prefix{}
+		if shouldStore {
+			// new behavior, routes are removed for b.example.com
+			wantRoutes = prefixes("1.2.3.1/32", "1.2.3.2/32")
+			wantRemovedRoutes = prefixes("1.2.3.3/32", "1.2.3.4/32")
+		}
+		assertRoutes("removal", wantRoutes, wantRemovedRoutes)
+	}
+}
+
+func TestUpdateWildcardRouteRemoval(t *testing.T) {
+	for _, shouldStore := range []bool{false, true} {
+		ctx := context.Background()
+		rc := &appctest.RouteCollector{}
+
+		assertRoutes := func(prefix string, routes, removedRoutes []netip.Prefix) {
+			if !slices.Equal(routes, rc.Routes()) {
+				t.Fatalf("%s: (shouldStore=%t) routes want %v, got %v", prefix, shouldStore, routes, rc.Routes())
+			}
+			if !slices.Equal(removedRoutes, rc.RemovedRoutes()) {
+				t.Fatalf("%s: (shouldStore=%t) removedRoutes want %v, got %v", prefix, shouldStore, removedRoutes, rc.RemovedRoutes())
+			}
+		}
+
+		var a *AppConnector
+		if shouldStore {
+			a = NewAppConnector(t.Logf, rc, &RouteInfo{}, fakeStoreRoutes)
+		} else {
+			a = NewAppConnector(t.Logf, rc, nil, nil)
+		}
+		assertRoutes("appc init", []netip.Prefix{}, []netip.Prefix{})
+
+		a.UpdateDomainsAndRoutes([]string{"a.example.com", "*.b.example.com"}, []netip.Prefix{})
+		a.Wait(ctx)
+		// adding domains doesn't immediately cause any routes to be advertised
+		assertRoutes("update domains", []netip.Prefix{}, []netip.Prefix{})
+
+		a.ObserveDNSResponse(dnsResponse("a.example.com.", "1.2.3.1"))
+		a.ObserveDNSResponse(dnsResponse("a.example.com.", "1.2.3.2"))
+		a.ObserveDNSResponse(dnsResponse("1.b.example.com.", "1.2.3.3"))
+		a.ObserveDNSResponse(dnsResponse("2.b.example.com.", "1.2.3.4"))
+		a.Wait(ctx)
+		// observing dns responses causes routes to be advertised
+		assertRoutes("observed dns", prefixes("1.2.3.1/32", "1.2.3.2/32", "1.2.3.3/32", "1.2.3.4/32"), []netip.Prefix{})
+
+		a.UpdateDomainsAndRoutes([]string{"a.example.com"}, []netip.Prefix{})
+		a.Wait(ctx)
+		// old behavior, routes are not removed
+		wantRoutes := prefixes("1.2.3.1/32", "1.2.3.2/32", "1.2.3.3/32", "1.2.3.4/32")
+		wantRemovedRoutes := []netip.Prefix{}
+		if shouldStore {
+			// new behavior, routes are removed for *.b.example.com
+			wantRoutes = prefixes("1.2.3.1/32", "1.2.3.2/32")
+			wantRemovedRoutes = prefixes("1.2.3.3/32", "1.2.3.4/32")
+		}
+		assertRoutes("removal", wantRoutes, wantRemovedRoutes)
+	}
+}
+
+func TestRoutesWithout(t *testing.T) {
+	assert := func(msg string, got, want []netip.Prefix) {
+		if !slices.Equal(want, got) {
+			t.Errorf("%s: want %v, got %v", msg, want, got)
+		}
+	}
+
+	assert("empty routes", routesWithout([]netip.Prefix{}, []netip.Prefix{}), []netip.Prefix{})
+	assert("a empty", routesWithout([]netip.Prefix{}, prefixes("1.1.1.1/32", "1.1.1.2/32")), []netip.Prefix{})
+	assert("b empty", routesWithout(prefixes("1.1.1.1/32", "1.1.1.2/32"), []netip.Prefix{}), prefixes("1.1.1.1/32", "1.1.1.2/32"))
+	assert("no overlap", routesWithout(prefixes("1.1.1.1/32", "1.1.1.2/32"), prefixes("1.1.1.3/32", "1.1.1.4/32")), prefixes("1.1.1.1/32", "1.1.1.2/32"))
+	assert("a has fewer", routesWithout(prefixes("1.1.1.1/32", "1.1.1.2/32"), prefixes("1.1.1.1/32", "1.1.1.2/32", "1.1.1.3/32", "1.1.1.4/32")), []netip.Prefix{})
+	assert("a has more", routesWithout(prefixes("1.1.1.1/32", "1.1.1.2/32", "1.1.1.3/32", "1.1.1.4/32"), prefixes("1.1.1.1/32", "1.1.1.3/32")), prefixes("1.1.1.2/32", "1.1.1.4/32"))
+}

cmd/derper/depaware.txt

@@ -89,7 +89,7 @@ tailscale.com/cmd/derper dependencies: (generated by github.com/tailscale/depawa
         tailscale.com/disco                                          from tailscale.com/derp
         tailscale.com/drive                                          from tailscale.com/client/tailscale+
         tailscale.com/envknob                                        from tailscale.com/client/tailscale+
-        tailscale.com/health                                         from tailscale.com/net/tlsdial
+        tailscale.com/health                                         from tailscale.com/net/tlsdial+
         tailscale.com/hostinfo                                       from tailscale.com/net/interfaces+
         tailscale.com/ipn                                            from tailscale.com/client/tailscale
         tailscale.com/ipn/ipnstate                                   from tailscale.com/client/tailscale+
@@ -138,6 +138,7 @@ tailscale.com/cmd/derper dependencies: (generated by github.com/tailscale/depawa
         tailscale.com/types/structs                                  from tailscale.com/ipn+
         tailscale.com/types/tkatype                                  from tailscale.com/client/tailscale+
         tailscale.com/types/views                                    from tailscale.com/ipn+
+        tailscale.com/util/cibuild                                   from tailscale.com/health
         tailscale.com/util/clientmetric                              from tailscale.com/net/netmon+
         tailscale.com/util/cloudenv                                  from tailscale.com/hostinfo+
    W    tailscale.com/util/cmpver                                    from tailscale.com/net/tshttpproxy

cmd/k8s-operator/deploy/crds/tailscale.com_proxyclasses.yaml

@@ -37,9 +37,16 @@ spec:
             spec:
               description: Specification of the desired state of the ProxyClass resource. https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status
               type: object
-              required:
-                - statefulSet
               properties:
+                metrics:
+                  description: Configuration for proxy metrics. Metrics are currently not supported for egress proxies and for Ingress proxies that have been configured with tailscale.com/experimental-forward-cluster-traffic-via-ingress annotation.
+                  type: object
+                  required:
+                    - enable
+                  properties:
+                    enable:
+                      description: Setting enable to true will make the proxy serve Tailscale metrics at <pod-ip>:9001/debug/metrics. Defaults to false.
+                      type: boolean
                 statefulSet:
                   description: Configuration parameters for the proxy's StatefulSet. Tailscale Kubernetes operator deploys a StatefulSet for each of the user configured proxies (Tailscale Ingress, Tailscale Service, Connector).
                   type: object

cmd/k8s-operator/deploy/examples/proxyclass.yaml

@@ -3,13 +3,15 @@ kind: ProxyClass
 metadata:
   name: prod
 spec:
+  metrics:
+    enable: true
   statefulSet:
     annotations:
-      platform-component: infra 
+      platform-component: infra
     pod:
       labels:
         team: eng
       nodeSelector:
-        beta.kubernetes.io/os: "linux"
+        kubernetes.io/os: "linux"
       imagePullSecrets:
       - name: "foo"

cmd/k8s-operator/deploy/manifests/operator.yaml

@@ -193,6 +193,15 @@ spec:
                     spec:
                         description: Specification of the desired state of the ProxyClass resource. https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status
                         properties:
+                            metrics:
+                                description: Configuration for proxy metrics. Metrics are currently not supported for egress proxies and for Ingress proxies that have been configured with tailscale.com/experimental-forward-cluster-traffic-via-ingress annotation.
+                                properties:
+                                    enable:
+                                        description: Setting enable to true will make the proxy serve Tailscale metrics at <pod-ip>:9001/debug/metrics. Defaults to false.
+                                        type: boolean
+                                required:
+                                    - enable
+                                type: object
                             statefulSet:
                                 description: Configuration parameters for the proxy's StatefulSet. Tailscale Kubernetes operator deploys a StatefulSet for each of the user configured proxies (Tailscale Ingress, Tailscale Service, Connector).
                                 properties:
@@ -1157,8 +1166,6 @@ spec:
                                                 type: array
                                         type: object
                                 type: object
-                        required:
-                            - statefulSet
                         type: object
                     status:
                         description: Status of the ProxyClass. This is set and managed automatically. https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status

cmd/k8s-operator/deploy/manifests/userspace-proxy.yaml

@@ -20,3 +20,7 @@ spec:
           env:
             - name: TS_USERSPACE
               value: "true"
+            - name: POD_IP
+              valueFrom:
+                fieldRef:
+                  fieldPath: status.podIP

cmd/k8s-operator/sts.go

@@ -582,7 +582,7 @@ func (a *tailscaleSTSReconciler) reconcileSTS(ctx context.Context, logger *zap.S
 	logger.Debugf("reconciling statefulset %s/%s", ss.GetNamespace(), ss.GetName())
 	if sts.ProxyClass != "" {
 		logger.Debugf("configuring proxy resources with ProxyClass %s", sts.ProxyClass)
-		ss = applyProxyClassToStatefulSet(proxyClass, ss)
+		ss = applyProxyClassToStatefulSet(proxyClass, ss, sts, logger)
 	}
 	updateSS := func(s *appsv1.StatefulSet) {
 		s.Spec = ss.Spec
@@ -613,8 +613,28 @@ func mergeStatefulSetLabelsOrAnnots(current, custom map[string]string, managed [
 	return custom
 }
 
-func applyProxyClassToStatefulSet(pc *tsapi.ProxyClass, ss *appsv1.StatefulSet) *appsv1.StatefulSet {
-	if pc == nil || ss == nil || pc.Spec.StatefulSet == nil {
+func applyProxyClassToStatefulSet(pc *tsapi.ProxyClass, ss *appsv1.StatefulSet, stsCfg *tailscaleSTSConfig, logger *zap.SugaredLogger) *appsv1.StatefulSet {
+	if pc == nil || ss == nil {
+		return ss
+	}
+	if pc.Spec.Metrics != nil && pc.Spec.Metrics.Enable {
+		if stsCfg.TailnetTargetFQDN == "" && stsCfg.TailnetTargetIP == "" && !stsCfg.ForwardClusterTrafficViaL7IngressProxy {
+			enableMetrics(ss, pc)
+		} else if stsCfg.ForwardClusterTrafficViaL7IngressProxy {
+			// TODO (irbekrm): fix this
+			// For Ingress proxies that have been configured with
+			// tailscale.com/experimental-forward-cluster-traffic-via-ingress
+			// annotation, all cluster traffic is forwarded to the
+			// Ingress backend(s).
+			logger.Info("ProxyClass specifies that metrics should be enabled, but this is currently not supported for Ingress proxies that accept cluster traffic.")
+		} else {
+			// TODO (irbekrm): fix this
+			// For egress proxies, currently all cluster traffic is forwarded to the tailnet target.
+			logger.Info("ProxyClass specifies that metrics should be enabled, but this is currently not supported for Ingress proxies that accept cluster traffic.")
+		}
+	}
+
+	if pc.Spec.StatefulSet == nil {
 		return ss
 	}
 
@@ -681,6 +701,21 @@ func applyProxyClassToStatefulSet(pc *tsapi.ProxyClass, ss *appsv1.StatefulSet)
 	return ss
 }
 
+func enableMetrics(ss *appsv1.StatefulSet, pc *tsapi.ProxyClass) {
+	for i, c := range ss.Spec.Template.Spec.Containers {
+		if c.Name == "tailscale" {
+			// Serve metrics on on <pod-ip>:9001/debug/metrics. If
+			// we didn't specify Pod IP here, the proxy would, in
+			// some cases, also listen to its Tailscale IP- we don't
+			// want folks to start relying on this side-effect as a
+			// feature.
+			ss.Spec.Template.Spec.Containers[i].Env = append(ss.Spec.Template.Spec.Containers[i].Env, corev1.EnvVar{Name: "TS_TAILSCALED_EXTRA_ARGS", Value: "--debug=$(POD_IP):9001"})
+			ss.Spec.Template.Spec.Containers[i].Ports = append(ss.Spec.Template.Spec.Containers[i].Ports, corev1.ContainerPort{Name: "metrics", Protocol: "TCP", HostPort: 9001, ContainerPort: 9001})
+			break
+		}
+	}
+}
+
 // tailscaledConfig takes a proxy config, a newly generated auth key if
 // generated and a Secret with the previous proxy state and auth key and
 // produces returns tailscaled configuration and a hash of that configuration.

cmd/k8s-operator/sts_test.go

@@ -14,6 +14,7 @@ import (
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
+	"go.uber.org/zap"
 	appsv1 "k8s.io/api/apps/v1"
 	corev1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/resource"
@@ -51,6 +52,10 @@ func Test_statefulSetNameBase(t *testing.T) {
 }
 
 func Test_applyProxyClassToStatefulSet(t *testing.T) {
+	zl, err := zap.NewDevelopment()
+	if err != nil {
+		t.Fatal(err)
+	}
 	// Setup
 	proxyClassAllOpts := &tsapi.ProxyClass{
 		Spec: tsapi.ProxyClassSpec{
@@ -105,6 +110,12 @@ func Test_applyProxyClassToStatefulSet(t *testing.T) {
 			},
 		},
 	}
+	proxyClassMetrics := &tsapi.ProxyClass{
+		Spec: tsapi.ProxyClassSpec{
+			Metrics: &tsapi.Metrics{Enable: true},
+		},
+	}
+
 	var userspaceProxySS, nonUserspaceProxySS appsv1.StatefulSet
 	if err := yaml.Unmarshal(userspaceProxyYaml, &userspaceProxySS); err != nil {
 		t.Fatalf("unmarshaling userspace proxy template: %v", err)
@@ -149,7 +160,7 @@ func Test_applyProxyClassToStatefulSet(t *testing.T) {
 	wantSS.Spec.Template.Spec.InitContainers[0].Env = append(wantSS.Spec.Template.Spec.InitContainers[0].Env, []corev1.EnvVar{{Name: "foo", Value: "bar"}, {Name: "TS_USERSPACE", Value: "true"}, {Name: "bar"}}...)
 	wantSS.Spec.Template.Spec.Containers[0].Env = append(wantSS.Spec.Template.Spec.Containers[0].Env, []corev1.EnvVar{{Name: "foo", Value: "bar"}, {Name: "TS_USERSPACE", Value: "true"}, {Name: "bar"}}...)
 
-	gotSS := applyProxyClassToStatefulSet(proxyClassAllOpts, nonUserspaceProxySS.DeepCopy())
+	gotSS := applyProxyClassToStatefulSet(proxyClassAllOpts, nonUserspaceProxySS.DeepCopy(), new(tailscaleSTSConfig), zl.Sugar())
 	if diff := cmp.Diff(gotSS, wantSS); diff != "" {
 		t.Fatalf("Unexpected result applying ProxyClass with all fields set to a StatefulSet for non-userspace proxy (-got +want):\n%s", diff)
 	}
@@ -162,7 +173,7 @@ func Test_applyProxyClassToStatefulSet(t *testing.T) {
 	wantSS.ObjectMeta.Annotations = mergeMapKeys(wantSS.ObjectMeta.Annotations, proxyClassJustLabels.Spec.StatefulSet.Annotations)
 	wantSS.Spec.Template.Labels = proxyClassJustLabels.Spec.StatefulSet.Pod.Labels
 	wantSS.Spec.Template.Annotations = proxyClassJustLabels.Spec.StatefulSet.Pod.Annotations
-	gotSS = applyProxyClassToStatefulSet(proxyClassJustLabels, nonUserspaceProxySS.DeepCopy())
+	gotSS = applyProxyClassToStatefulSet(proxyClassJustLabels, nonUserspaceProxySS.DeepCopy(), new(tailscaleSTSConfig), zl.Sugar())
 	if diff := cmp.Diff(gotSS, wantSS); diff != "" {
 		t.Fatalf("Unexpected result applying ProxyClass with custom labels and annotations to a StatefulSet for non-userspace proxy (-got +want):\n%s", diff)
 	}
@@ -183,7 +194,7 @@ func Test_applyProxyClassToStatefulSet(t *testing.T) {
 	wantSS.Spec.Template.Spec.Containers[0].SecurityContext = proxyClassAllOpts.Spec.StatefulSet.Pod.TailscaleContainer.SecurityContext
 	wantSS.Spec.Template.Spec.Containers[0].Resources = proxyClassAllOpts.Spec.StatefulSet.Pod.TailscaleContainer.Resources
 	wantSS.Spec.Template.Spec.Containers[0].Env = append(wantSS.Spec.Template.Spec.Containers[0].Env, []corev1.EnvVar{{Name: "foo", Value: "bar"}, {Name: "TS_USERSPACE", Value: "true"}, {Name: "bar"}}...)
-	gotSS = applyProxyClassToStatefulSet(proxyClassAllOpts, userspaceProxySS.DeepCopy())
+	gotSS = applyProxyClassToStatefulSet(proxyClassAllOpts, userspaceProxySS.DeepCopy(), new(tailscaleSTSConfig), zl.Sugar())
 	if diff := cmp.Diff(gotSS, wantSS); diff != "" {
 		t.Fatalf("Unexpected result applying ProxyClass with custom labels and annotations to a StatefulSet for a userspace proxy (-got +want):\n%s", diff)
 	}
@@ -195,10 +206,19 @@ func Test_applyProxyClassToStatefulSet(t *testing.T) {
 	wantSS.ObjectMeta.Annotations = mergeMapKeys(wantSS.ObjectMeta.Annotations, proxyClassJustLabels.Spec.StatefulSet.Annotations)
 	wantSS.Spec.Template.Labels = proxyClassJustLabels.Spec.StatefulSet.Pod.Labels
 	wantSS.Spec.Template.Annotations = proxyClassJustLabels.Spec.StatefulSet.Pod.Annotations
-	gotSS = applyProxyClassToStatefulSet(proxyClassJustLabels, userspaceProxySS.DeepCopy())
+	gotSS = applyProxyClassToStatefulSet(proxyClassJustLabels, userspaceProxySS.DeepCopy(), new(tailscaleSTSConfig), zl.Sugar())
 	if diff := cmp.Diff(gotSS, wantSS); diff != "" {
 		t.Fatalf("Unexpected result applying ProxyClass with custom labels and annotations to a StatefulSet for a userspace proxy (-got +want):\n%s", diff)
 	}
+
+	// 5. Test that a ProxyClass with metrics enabled gets correctly applied to a StatefulSet.
+	wantSS = nonUserspaceProxySS.DeepCopy()
+	wantSS.Spec.Template.Spec.Containers[0].Env = append(wantSS.Spec.Template.Spec.Containers[0].Env, corev1.EnvVar{Name: "TS_TAILSCALED_EXTRA_ARGS", Value: "--debug=$(POD_IP):9001"})
+	wantSS.Spec.Template.Spec.Containers[0].Ports = []corev1.ContainerPort{{Name: "metrics", Protocol: "TCP", ContainerPort: 9001, HostPort: 9001}}
+	gotSS = applyProxyClassToStatefulSet(proxyClassMetrics, nonUserspaceProxySS.DeepCopy(), new(tailscaleSTSConfig), zl.Sugar())
+	if diff := cmp.Diff(gotSS, wantSS); diff != "" {
+		t.Fatalf("Unexpected result applying ProxyClass with metrics enabled to a StatefulSet (-got +want):\n%s", diff)
+	}
 }
 
 func mergeMapKeys(a, b map[string]string) map[string]string {

cmd/k8s-operator/testutils_test.go

@@ -15,6 +15,7 @@ import (
 	"time"
 
 	"github.com/google/go-cmp/cmp"
+	"go.uber.org/zap"
 	appsv1 "k8s.io/api/apps/v1"
 	corev1 "k8s.io/api/core/v1"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
@@ -54,6 +55,10 @@ type configOpts struct {
 
 func expectedSTS(t *testing.T, cl client.Client, opts configOpts) *appsv1.StatefulSet {
 	t.Helper()
+	zl, err := zap.NewDevelopment()
+	if err != nil {
+		t.Fatal(err)
+	}
 	tsContainer := corev1.Container{
 		Name:  "tailscale",
 		Image: "tailscale/tailscale",
@@ -205,18 +210,23 @@ func expectedSTS(t *testing.T, cl client.Client, opts configOpts) *appsv1.Statef
 		if err := cl.Get(context.Background(), types.NamespacedName{Name: opts.proxyClass}, proxyClass); err != nil {
 			t.Fatalf("error getting ProxyClass: %v", err)
 		}
-		return applyProxyClassToStatefulSet(proxyClass, ss)
+		return applyProxyClassToStatefulSet(proxyClass, ss, new(tailscaleSTSConfig), zl.Sugar())
 	}
 	return ss
 }
 
 func expectedSTSUserspace(t *testing.T, cl client.Client, opts configOpts) *appsv1.StatefulSet {
 	t.Helper()
+	zl, err := zap.NewDevelopment()
+	if err != nil {
+		t.Fatal(err)
+	}
 	tsContainer := corev1.Container{
 		Name:  "tailscale",
 		Image: "tailscale/tailscale",
 		Env: []corev1.EnvVar{
 			{Name: "TS_USERSPACE", Value: "true"},
+			{Name: "POD_IP", ValueFrom: &corev1.EnvVarSource{FieldRef: &corev1.ObjectFieldSelector{APIVersion: "", FieldPath: "status.podIP"}, ResourceFieldRef: nil, ConfigMapKeyRef: nil, SecretKeyRef: nil}},
 			{Name: "TS_KUBE_SECRET", Value: opts.secretName},
 			{Name: "EXPERIMENTAL_TS_CONFIGFILE_PATH", Value: "/etc/tsconfig/tailscaled"},
 			{Name: "TS_SERVE_CONFIG", Value: "/etc/tailscaled/serve-config"},
@@ -301,7 +311,7 @@ func expectedSTSUserspace(t *testing.T, cl client.Client, opts configOpts) *apps
 		if err := cl.Get(context.Background(), types.NamespacedName{Name: opts.proxyClass}, proxyClass); err != nil {
 			t.Fatalf("error getting ProxyClass: %v", err)
 		}
-		return applyProxyClassToStatefulSet(proxyClass, ss)
+		return applyProxyClassToStatefulSet(proxyClass, ss, new(tailscaleSTSConfig), zl.Sugar())
 	}
 	return ss
 }

cmd/tailscale/depaware.txt

@@ -88,7 +88,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         tailscale.com/disco                                          from tailscale.com/derp
         tailscale.com/drive                                          from tailscale.com/client/tailscale+
         tailscale.com/envknob                                        from tailscale.com/client/tailscale+
-        tailscale.com/health                                         from tailscale.com/net/tlsdial
+        tailscale.com/health                                         from tailscale.com/net/tlsdial+
         tailscale.com/health/healthmsg                               from tailscale.com/cmd/tailscale/cli
         tailscale.com/hostinfo                                       from tailscale.com/client/web+
         tailscale.com/ipn                                            from tailscale.com/client/tailscale+
@@ -142,6 +142,7 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         tailscale.com/types/structs                                  from tailscale.com/ipn+
         tailscale.com/types/tkatype                                  from tailscale.com/types/key+
         tailscale.com/types/views                                    from tailscale.com/tailcfg+
+        tailscale.com/util/cibuild                                   from tailscale.com/health
         tailscale.com/util/clientmetric                              from tailscale.com/net/netcheck+
         tailscale.com/util/cloudenv                                  from tailscale.com/net/dnscache+
         tailscale.com/util/cmpver                                    from tailscale.com/net/tshttpproxy+

cmd/tailscaled/debug.go

@@ -21,6 +21,7 @@ import (
 	"time"
 
 	"tailscale.com/derp/derphttp"
+	"tailscale.com/health"
 	"tailscale.com/ipn"
 	"tailscale.com/net/interfaces"
 	"tailscale.com/net/netmon"
@@ -157,6 +158,7 @@ func getURL(ctx context.Context, urlStr string) error {
 }
 
 func checkDerp(ctx context.Context, derpRegion string) (err error) {
+	ht := new(health.Tracker)
 	req, err := http.NewRequestWithContext(ctx, "GET", ipn.DefaultControlURL+"/derpmap/default", nil)
 	if err != nil {
 		return fmt.Errorf("create derp map request: %w", err)
@@ -195,6 +197,8 @@ func checkDerp(ctx context.Context, derpRegion string) (err error) {
 
 	c1 := derphttp.NewRegionClient(priv1, log.Printf, nil, getRegion)
 	c2 := derphttp.NewRegionClient(priv2, log.Printf, nil, getRegion)
+	c1.HealthTracker = ht
+	c2.HealthTracker = ht
 	defer func() {
 		if err != nil {
 			c1.Close()

cmd/tailscaled/depaware.txt

@@ -358,6 +358,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/types/structs                                  from tailscale.com/control/controlclient+
         tailscale.com/types/tkatype                                  from tailscale.com/tka+
         tailscale.com/types/views                                    from tailscale.com/ipn/ipnlocal+
+        tailscale.com/util/cibuild                                   from tailscale.com/health
         tailscale.com/util/clientmetric                              from tailscale.com/control/controlclient+
         tailscale.com/util/cloudenv                                  from tailscale.com/net/dns/resolver+
         tailscale.com/util/cmpver                                    from tailscale.com/net/dns+

cmd/tailscaled/tailscaled.go

@@ -358,7 +358,7 @@ func run() (err error) {
 		sys.Set(netMon)
 	}
 
-	pol := logpolicy.New(logtail.CollectionNode, netMon, nil /* use log.Printf */)
+	pol := logpolicy.New(logtail.CollectionNode, netMon, sys.HealthTracker(), nil /* use log.Printf */)
 	pol.SetVerbosityLevel(args.verbose)
 	logPol = pol
 	defer func() {
@@ -651,6 +651,7 @@ func tryEngine(logf logger.Logf, sys *tsd.System, name string) (onlyNetstack boo
 	conf := wgengine.Config{
 		ListenPort:    args.port,
 		NetMon:        sys.NetMon.Get(),
+		HealthTracker: sys.HealthTracker(),
 		Dialer:        sys.Dialer.Get(),
 		SetSubsystem:  sys.Set,
 		ControlKnobs:  sys.ControlKnobs(),
@@ -676,7 +677,7 @@ func tryEngine(logf logger.Logf, sys *tsd.System, name string) (onlyNetstack boo
 			// configuration being unavailable (from the noop
 			// manager). More in Issue 4017.
 			// TODO(bradfitz): add a Synology-specific DNS manager.
-			conf.DNS, err = dns.NewOSConfigurator(logf, "") // empty interface name
+			conf.DNS, err = dns.NewOSConfigurator(logf, sys.HealthTracker(), "") // empty interface name
 			if err != nil {
 				return false, fmt.Errorf("dns.NewOSConfigurator: %w", err)
 			}
@@ -698,13 +699,13 @@ func tryEngine(logf logger.Logf, sys *tsd.System, name string) (onlyNetstack boo
 			return false, err
 		}
 
-		r, err := router.New(logf, dev, sys.NetMon.Get())
+		r, err := router.New(logf, dev, sys.NetMon.Get(), sys.HealthTracker())
 		if err != nil {
 			dev.Close()
 			return false, fmt.Errorf("creating router: %w", err)
 		}
 
-		d, err := dns.NewOSConfigurator(logf, devName)
+		d, err := dns.NewOSConfigurator(logf, sys.HealthTracker(), devName)
 		if err != nil {
 			dev.Close()
 			r.Close()

cmd/tsconnect/wasm/wasm_js.go

@@ -104,9 +104,10 @@ func newIPN(jsConfig js.Value) map[string]any {
 	sys.Set(store)
 	dialer := &tsdial.Dialer{Logf: logf}
 	eng, err := wgengine.NewUserspaceEngine(logf, wgengine.Config{
-		Dialer:       dialer,
-		SetSubsystem: sys.Set,
-		ControlKnobs: sys.ControlKnobs(),
+		Dialer:        dialer,
+		SetSubsystem:  sys.Set,
+		ControlKnobs:  sys.ControlKnobs(),
+		HealthTracker: sys.HealthTracker(),
 	})
 	if err != nil {
 		log.Fatal(err)

control/controlclient/auto.go

@@ -12,7 +12,6 @@ import (
 	"sync/atomic"
 	"time"
 
-	"tailscale.com/health"
 	"tailscale.com/logtail/backoff"
 	"tailscale.com/net/sockstats"
 	"tailscale.com/tailcfg"
@@ -195,7 +194,7 @@ func NewNoStart(opts Options) (_ *Auto, err error) {
 	c.mapCtx, c.mapCancel = context.WithCancel(context.Background())
 	c.mapCtx = sockstats.WithSockStats(c.mapCtx, sockstats.LabelControlClientAuto, opts.Logf)
 
-	c.unregisterHealthWatch = health.RegisterWatcher(direct.ReportHealthChange)
+	c.unregisterHealthWatch = opts.HealthTracker.RegisterWatcher(direct.ReportHealthChange)
 	return c, nil
 
 }
@@ -316,7 +315,7 @@ func (c *Auto) authRoutine() {
 		}
 
 		if goal == nil {
-			health.SetAuthRoutineInError(nil)
+			c.direct.health.SetAuthRoutineInError(nil)
 			// Wait for user to Login or Logout.
 			<-ctx.Done()
 			c.logf("[v1] authRoutine: context done.")
@@ -343,7 +342,7 @@ func (c *Auto) authRoutine() {
 			f = "TryLogin"
 		}
 		if err != nil {
-			health.SetAuthRoutineInError(err)
+			c.direct.health.SetAuthRoutineInError(err)
 			report(err, f)
 			bo.BackOff(ctx, err)
 			continue
@@ -373,7 +372,7 @@ func (c *Auto) authRoutine() {
 		}
 
 		// success
-		health.SetAuthRoutineInError(nil)
+		c.direct.health.SetAuthRoutineInError(nil)
 		c.mu.Lock()
 		c.urlToVisit = ""
 		c.loggedIn = true
@@ -503,11 +502,11 @@ func (c *Auto) mapRoutine() {
 			c.logf("[v1] mapRoutine: context done.")
 			continue
 		}
-		health.SetOutOfPollNetMap()
+		c.direct.health.SetOutOfPollNetMap()
 
 		err := c.direct.PollNetMap(ctx, mrs)
 
-		health.SetOutOfPollNetMap()
+		c.direct.health.SetOutOfPollNetMap()
 		c.mu.Lock()
 		c.inMapPoll = false
 		if c.state == StateSynchronized {

control/controlclient/direct.go

@@ -69,6 +69,7 @@ type Direct struct {
 	clock                      tstime.Clock
 	logf                       logger.Logf
 	netMon                     *netmon.Monitor // or nil
+	health                     *health.Tracker
 	discoPubKey                key.DiscoPublic
 	getMachinePrivKey          func() (key.MachinePrivate, error)
 	debugFlags                 []string
@@ -119,10 +120,11 @@ type Options struct {
 	Hostinfo                   *tailcfg.Hostinfo // non-nil passes ownership, nil means to use default using os.Hostname, etc
 	DiscoPublicKey             key.DiscoPublic
 	Logf                       logger.Logf
-	HTTPTestClient             *http.Client                 // optional HTTP client to use (for tests only)
-	NoiseTestClient            *http.Client                 // optional HTTP client to use for noise RPCs (tests only)
-	DebugFlags                 []string                     // debug settings to send to control
-	NetMon                     *netmon.Monitor              // optional network monitor
+	HTTPTestClient             *http.Client    // optional HTTP client to use (for tests only)
+	NoiseTestClient            *http.Client    // optional HTTP client to use for noise RPCs (tests only)
+	DebugFlags                 []string        // debug settings to send to control
+	NetMon                     *netmon.Monitor // optional network monitor
+	HealthTracker              *health.Tracker
 	PopBrowserURL              func(url string)             // optional func to open browser
 	OnClientVersion            func(*tailcfg.ClientVersion) // optional func to inform GUI of client version status
 	OnControlTime              func(time.Time)              // optional func to notify callers of new time from control
@@ -248,7 +250,7 @@ func NewDirect(opts Options) (*Direct, error) {
 		tr := http.DefaultTransport.(*http.Transport).Clone()
 		tr.Proxy = tshttpproxy.ProxyFromEnvironment
 		tshttpproxy.SetTransportGetProxyConnectHeader(tr)
-		tr.TLSClientConfig = tlsdial.Config(serverURL.Hostname(), tr.TLSClientConfig)
+		tr.TLSClientConfig = tlsdial.Config(serverURL.Hostname(), opts.HealthTracker, tr.TLSClientConfig)
 		tr.DialContext = dnscache.Dialer(opts.Dialer.SystemDial, dnsCache)
 		tr.DialTLSContext = dnscache.TLSDialer(opts.Dialer.SystemDial, dnsCache, tr.TLSClientConfig)
 		tr.ForceAttemptHTTP2 = true
@@ -271,6 +273,7 @@ func NewDirect(opts Options) (*Direct, error) {
 		discoPubKey:                opts.DiscoPublicKey,
 		debugFlags:                 opts.DebugFlags,
 		netMon:                     opts.NetMon,
+		health:                     opts.HealthTracker,
 		skipIPForwardingCheck:      opts.SkipIPForwardingCheck,
 		pinger:                     opts.Pinger,
 		popBrowser:                 opts.PopBrowserURL,
@@ -894,10 +897,10 @@ func (c *Direct) sendMapRequest(ctx context.Context, isStreaming bool, nu Netmap
 		ipForwardingBroken(hi.RoutableIPs, c.netMon.InterfaceState()) {
 		extraDebugFlags = append(extraDebugFlags, "warn-ip-forwarding-off")
 	}
-	if health.RouterHealth() != nil {
+	if c.health.RouterHealth() != nil {
 		extraDebugFlags = append(extraDebugFlags, "warn-router-unhealthy")
 	}
-	extraDebugFlags = health.AppendWarnableDebugFlags(extraDebugFlags)
+	extraDebugFlags = c.health.AppendWarnableDebugFlags(extraDebugFlags)
 	if hostinfo.DisabledEtcAptSource() {
 		extraDebugFlags = append(extraDebugFlags, "warn-etc-apt-source-disabled")
 	}
@@ -970,7 +973,7 @@ func (c *Direct) sendMapRequest(ctx context.Context, isStreaming bool, nu Netmap
 	}
 	defer res.Body.Close()
 
-	health.NoteMapRequestHeard(request)
+	c.health.NoteMapRequestHeard(request)
 	watchdogTimer.Reset(watchdogTimeout)
 
 	if nu == nil {
@@ -1041,7 +1044,7 @@ func (c *Direct) sendMapRequest(ctx context.Context, isStreaming bool, nu Netmap
 		metricMapResponseMessages.Add(1)
 
 		if isStreaming {
-			health.GotStreamedMapResponse()
+			c.health.GotStreamedMapResponse()
 		}
 
 		if pr := resp.PingRequest; pr != nil && c.isUniquePingRequest(pr) {
@@ -1450,14 +1453,15 @@ func (c *Direct) getNoiseClient() (*NoiseClient, error) {
 		}
 		c.logf("[v1] creating new noise client")
 		nc, err := NewNoiseClient(NoiseOpts{
-			PrivKey:      k,
-			ServerPubKey: serverNoiseKey,
-			ServerURL:    c.serverURL,
-			Dialer:       c.dialer,
-			DNSCache:     c.dnsCache,
-			Logf:         c.logf,
-			NetMon:       c.netMon,
-			DialPlan:     dp,
+			PrivKey:       k,
+			ServerPubKey:  serverNoiseKey,
+			ServerURL:     c.serverURL,
+			Dialer:        c.dialer,
+			DNSCache:      c.dnsCache,
+			Logf:          c.logf,
+			NetMon:        c.netMon,
+			HealthTracker: c.health,
+			DialPlan:      dp,
 		})
 		if err != nil {
 			return nil, err

control/controlclient/noise.go

@@ -19,6 +19,7 @@ import (
 	"golang.org/x/net/http2"
 	"tailscale.com/control/controlbase"
 	"tailscale.com/control/controlhttp"
+	"tailscale.com/health"
 	"tailscale.com/net/dnscache"
 	"tailscale.com/net/netmon"
 	"tailscale.com/net/tsdial"
@@ -174,6 +175,7 @@ type NoiseClient struct {
 
 	logf   logger.Logf
 	netMon *netmon.Monitor
+	health *health.Tracker
 
 	// mu only protects the following variables.
 	mu       sync.Mutex
@@ -204,6 +206,8 @@ type NoiseOpts struct {
 	// network interface state. This field can be nil; if so, the current
 	// state will be looked up dynamically.
 	NetMon *netmon.Monitor
+	// HealthTracker, if non-nil, is the health tracker to use.
+	HealthTracker *health.Tracker
 	// DialPlan, if set, is a function that should return an explicit plan
 	// on how to connect to the server.
 	DialPlan func() *tailcfg.ControlDialPlan
@@ -247,6 +251,7 @@ func NewNoiseClient(opts NoiseOpts) (*NoiseClient, error) {
 		dialPlan:     opts.DialPlan,
 		logf:         opts.Logf,
 		netMon:       opts.NetMon,
+		health:       opts.HealthTracker,
 	}
 
 	// Create the HTTP/2 Transport using a net/http.Transport
@@ -453,6 +458,7 @@ func (nc *NoiseClient) dial(ctx context.Context) (*noiseConn, error) {
 		DialPlan:        dialPlan,
 		Logf:            nc.logf,
 		NetMon:          nc.netMon,
+		HealthTracker:   nc.health,
 		Clock:           tstime.StdClock{},
 	}).Dial(ctx)
 	if err != nil {

control/controlhttp/client.go

@@ -433,7 +433,7 @@ func (a *Dialer) tryURLUpgrade(ctx context.Context, u *url.URL, addr netip.Addr,
 	// Disable HTTP2, since h2 can't do protocol switching.
 	tr.TLSClientConfig.NextProtos = []string{}
 	tr.TLSNextProto = map[string]func(string, *tls.Conn) http.RoundTripper{}
-	tr.TLSClientConfig = tlsdial.Config(a.Hostname, tr.TLSClientConfig)
+	tr.TLSClientConfig = tlsdial.Config(a.Hostname, a.HealthTracker, tr.TLSClientConfig)
 	if !tr.TLSClientConfig.InsecureSkipVerify {
 		panic("unexpected") // should be set by tlsdial.Config
 	}

control/controlhttp/constants.go

@@ -8,6 +8,7 @@ import (
 	"net/url"
 	"time"
 
+	"tailscale.com/health"
 	"tailscale.com/net/dnscache"
 	"tailscale.com/net/netmon"
 	"tailscale.com/tailcfg"
@@ -79,6 +80,9 @@ type Dialer struct {
 
 	NetMon *netmon.Monitor
 
+	// HealthTracker, if non-nil, is the health tracker to use.
+	HealthTracker *health.Tracker
+
 	// DialPlan, if set, contains instructions from the control server on
 	// how to connect to it. If present, we will try the methods in this
 	// plan before falling back to DNS.

control/controlknobs/controlknobs.go

@@ -72,6 +72,10 @@ type Knobs struct {
 	// ProbeUDPLifetime is whether the node should probe UDP path lifetime on
 	// the tail end of an active direct connection in magicsock.
 	ProbeUDPLifetime atomic.Bool
+
+	// AppCStoreRoutes is whether the node should store RouteInfo to StateStore
+	// if it's an app connector.
+	AppCStoreRoutes atomic.Bool
 }
 
 // UpdateFromNodeAttributes updates k (if non-nil) based on the provided self
@@ -96,6 +100,7 @@ func (k *Knobs) UpdateFromNodeAttributes(capMap tailcfg.NodeCapMap) {
 		forceNfTables                 = has(tailcfg.NodeAttrLinuxMustUseNfTables)
 		seamlessKeyRenewal            = has(tailcfg.NodeAttrSeamlessKeyRenewal)
 		probeUDPLifetime              = has(tailcfg.NodeAttrProbeUDPLifetime)
+		appCStoreRoutes               = has(tailcfg.NodeAttrStoreAppCRoutes)
 	)
 
 	if has(tailcfg.NodeAttrOneCGNATEnable) {
@@ -118,6 +123,7 @@ func (k *Knobs) UpdateFromNodeAttributes(capMap tailcfg.NodeCapMap) {
 	k.LinuxForceNfTables.Store(forceNfTables)
 	k.SeamlessKeyRenewal.Store(seamlessKeyRenewal)
 	k.ProbeUDPLifetime.Store(probeUDPLifetime)
+	k.AppCStoreRoutes.Store(appCStoreRoutes)
 }
 
 // AsDebugJSON returns k as something that can be marshalled with json.Marshal
@@ -141,5 +147,6 @@ func (k *Knobs) AsDebugJSON() map[string]any {
 		"LinuxForceNfTables":            k.LinuxForceNfTables.Load(),
 		"SeamlessKeyRenewal":            k.SeamlessKeyRenewal.Load(),
 		"ProbeUDPLifetime":              k.ProbeUDPLifetime.Load(),
+		"AppCStoreRoutes":               k.AppCStoreRoutes.Load(),
 	}
 }

derp/derphttp/derphttp_client.go

@@ -31,6 +31,7 @@ import (
 	"go4.org/mem"
 	"tailscale.com/derp"
 	"tailscale.com/envknob"
+	"tailscale.com/health"
 	"tailscale.com/net/dnscache"
 	"tailscale.com/net/netmon"
 	"tailscale.com/net/netns"
@@ -51,10 +52,11 @@ import (
 // Send/Recv will completely re-establish the connection (unless Close
 // has been called).
 type Client struct {
-	TLSConfig *tls.Config        // optional; nil means default
-	DNSCache  *dnscache.Resolver // optional; nil means no caching
-	MeshKey   string             // optional; for trusted clients
-	IsProber  bool               // optional; for probers to optional declare themselves as such
+	TLSConfig     *tls.Config        // optional; nil means default
+	HealthTracker *health.Tracker    // optional; used if non-nil only
+	DNSCache      *dnscache.Resolver // optional; nil means no caching
+	MeshKey       string             // optional; for trusted clients
+	IsProber      bool               // optional; for probers to optional declare themselves as such
 
 	// WatchConnectionChanges is whether the client wishes to subscribe to
 	// notifications about clients connecting & disconnecting.
@@ -115,6 +117,7 @@ func (c *Client) String() string {
 // NewRegionClient returns a new DERP-over-HTTP client. It connects lazily.
 // To trigger a connection, use Connect.
 // The netMon parameter is optional; if non-nil it's used to do faster interface lookups.
+// The healthTracker parameter is also optional.
 func NewRegionClient(privateKey key.NodePrivate, logf logger.Logf, netMon *netmon.Monitor, getRegion func() *tailcfg.DERPRegion) *Client {
 	ctx, cancel := context.WithCancel(context.Background())
 	c := &Client{
@@ -612,7 +615,7 @@ func (c *Client) dialRegion(ctx context.Context, reg *tailcfg.DERPRegion) (net.C
 }
 
 func (c *Client) tlsClient(nc net.Conn, node *tailcfg.DERPNode) *tls.Conn {
-	tlsConf := tlsdial.Config(c.tlsServerName(node), c.TLSConfig)
+	tlsConf := tlsdial.Config(c.tlsServerName(node), c.HealthTracker, c.TLSConfig)
 	if node != nil {
 		if node.InsecureForTests {
 			tlsConf.InsecureSkipVerify = true

health/health.go

@@ -9,6 +9,7 @@ import (
 	"errors"
 	"fmt"
 	"net/http"
+	"os"
 	"runtime"
 	"sort"
 	"sync"
@@ -17,20 +18,59 @@ import (
 
 	"tailscale.com/envknob"
 	"tailscale.com/tailcfg"
+	"tailscale.com/types/opt"
+	"tailscale.com/util/cibuild"
+	"tailscale.com/util/mak"
 	"tailscale.com/util/multierr"
 	"tailscale.com/util/set"
 )
 
 var (
-	// mu guards everything in this var block.
+	mu           sync.Mutex
+	debugHandler map[string]http.Handler
+)
+
+// ReceiveFunc is one of the three magicsock Receive funcs (IPv4, IPv6, or
+// DERP).
+type ReceiveFunc int
+
+// ReceiveFunc indices for Tracker.MagicSockReceiveFuncs.
+const (
+	ReceiveIPv4 ReceiveFunc = 0
+	ReceiveIPv6 ReceiveFunc = 1
+	ReceiveDERP ReceiveFunc = 2
+)
+
+func (f ReceiveFunc) String() string {
+	if f < 0 || int(f) >= len(receiveNames) {
+		return fmt.Sprintf("ReceiveFunc(%d)", f)
+	}
+	return receiveNames[f]
+}
+
+var receiveNames = []string{
+	ReceiveIPv4: "ReceiveIPv4",
+	ReceiveIPv6: "ReceiveIPv6",
+	ReceiveDERP: "ReceiveDERP",
+}
+
+// Tracker tracks the health of various Tailscale subsystems,
+// comparing each subsystems' state with each other to make sure
+// they're consistent based on the user's intended state.
+type Tracker struct {
+	// MagicSockReceiveFuncs tracks the state of the three
+	// magicsock receive functions: IPv4, IPv6, and DERP.
+	MagicSockReceiveFuncs [3]ReceiveFuncStats // indexed by ReceiveFunc values
+
+	// mu guards everything that follows.
 	mu sync.Mutex
 
-	sysErr    = map[Subsystem]error{}                   // error key => err (or nil for no error)
-	watchers  = set.HandleSet[func(Subsystem, error)]{} // opt func to run if error state changes
-	warnables = set.Set[*Warnable]{}
-	timer     *time.Timer
+	warnables   []*Warnable // keys ever set
+	warnableVal map[*Warnable]error
 
-	debugHandler = map[string]http.Handler{}
+	sysErr   map[Subsystem]error                   // subsystem => err (or nil for no error)
+	watchers set.HandleSet[func(Subsystem, error)] // opt func to run if error state changes
+	timer    *time.Timer
 
 	inMapPoll               bool
 	inMapPollSince          time.Time
@@ -38,19 +78,19 @@ var (
 	lastStreamedMapResponse time.Time
 	derpHomeRegion          int
 	derpHomeless            bool
-	derpRegionConnected     = map[int]bool{}
-	derpRegionHealthProblem = map[int]string{}
-	derpRegionLastFrame     = map[int]time.Time{}
+	derpRegionConnected     map[int]bool
+	derpRegionHealthProblem map[int]string
+	derpRegionLastFrame     map[int]time.Time
 	lastMapRequestHeard     time.Time // time we got a 200 from control for a MapRequest
 	ipnState                string
 	ipnWantRunning          bool
-	anyInterfaceUp          = true // until told otherwise
+	anyInterfaceUp          opt.Bool // empty means unknown (assume true)
 	udp4Unbound             bool
 	controlHealth           []string
 	lastLoginErr            error
 	localLogConfigErr       error
-	tlsConnectionErrors     = map[string]error{} // map[ServerName]error
-)
+	tlsConnectionErrors     map[string]error // map[ServerName]error
+}
 
 // Subsystem is the name of a subsystem whose health can be monitored.
 type Subsystem string
@@ -76,16 +116,16 @@ const (
 	SysTKA = Subsystem("tailnet-lock")
 )
 
-// NewWarnable returns a new warnable item that the caller can mark
-// as health or in warning state.
+// NewWarnable returns a new warnable item that the caller can mark as health or
+// in warning state via Tracker.SetWarnable.
+//
+// NewWarnable is generally called in init and stored in a package global. It
+// can be used by multiple Trackers.
 func NewWarnable(opts ...WarnableOpt) *Warnable {
 	w := new(Warnable)
 	for _, o := range opts {
 		o.mod(w)
 	}
-	mu.Lock()
-	defer mu.Unlock()
-	warnables.Add(w)
 	return w
 }
 
@@ -118,49 +158,66 @@ type warnOptFunc func(*Warnable)
 func (f warnOptFunc) mod(w *Warnable) { f(w) }
 
 // Warnable is a health check item that may or may not be in a bad warning state.
-// The caller of NewWarnable is responsible for calling Set to update the state.
+// The caller of NewWarnable is responsible for calling Tracker.SetWarnable to update the state.
 type Warnable struct {
 	debugFlag string // optional MapRequest.DebugFlag to send when unhealthy
 
 	// If true, this warning is related to configuration of networking stack
 	// on the machine that impacts connectivity.
 	hasConnectivityImpact bool
+}
 
-	isSet atomic.Bool
-	mu    sync.Mutex
-	err   error
+// nil reports whether t is nil.
+// It exists to accept nil *Tracker receivers on all methods
+// to at least not crash. But because a nil receiver indicates
+// some lost Tracker plumbing, we want to capture stack trace
+// samples when it occurs.
+func (t *Tracker) nil() bool {
+	if t != nil {
+		return false
+	}
+	if cibuild.On() {
+		stack := make([]byte, 1<<10)
+		stack = stack[:runtime.Stack(stack, false)]
+		fmt.Fprintf(os.Stderr, "## WARNING: (non-fatal) nil health.Tracker (being strict in CI):\n%s\n", stack)
+	}
+	// TODO(bradfitz): open source our "unexpected" package
+	// and use it here to capture samples of stacks where
+	// t is nil.
+	return true
 }
 
 // Set updates the Warnable's state.
 // If non-nil, it's considered unhealthy.
-func (w *Warnable) Set(err error) {
-	w.mu.Lock()
-	defer w.mu.Unlock()
-	w.err = err
-	w.isSet.Store(err != nil)
-}
-
-func (w *Warnable) get() error {
-	if !w.isSet.Load() {
-		return nil
+func (t *Tracker) SetWarnable(w *Warnable, err error) {
+	if t.nil() {
+		return
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	l0 := len(t.warnableVal)
+	mak.Set(&t.warnableVal, w, err)
+	if len(t.warnableVal) != l0 {
+		t.warnables = append(t.warnables, w)
 	}
-	w.mu.Lock()
-	defer w.mu.Unlock()
-	return w.err
 }
 
 // AppendWarnableDebugFlags appends to base any health items that are currently in failed
 // state and were created with MapDebugFlag.
-func AppendWarnableDebugFlags(base []string) []string {
+func (t *Tracker) AppendWarnableDebugFlags(base []string) []string {
+	if t.nil() {
+		return base
+	}
+
 	ret := base
 
-	mu.Lock()
-	defer mu.Unlock()
-	for w := range warnables {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	for w, err := range t.warnableVal {
 		if w.debugFlag == "" {
 			continue
 		}
-		if err := w.get(); err != nil {
+		if err != nil {
 			ret = append(ret, w.debugFlag)
 		}
 	}
@@ -172,75 +229,87 @@ func AppendWarnableDebugFlags(base []string) []string {
 // error changes state either to unhealthy or from unhealthy. It is
 // not called on transition from unknown to healthy. It must be non-nil
 // and is run in its own goroutine. The returned func unregisters it.
-func RegisterWatcher(cb func(key Subsystem, err error)) (unregister func()) {
-	mu.Lock()
-	defer mu.Unlock()
-	handle := watchers.Add(cb)
-	if timer == nil {
-		timer = time.AfterFunc(time.Minute, timerSelfCheck)
+func (t *Tracker) RegisterWatcher(cb func(key Subsystem, err error)) (unregister func()) {
+	if t.nil() {
+		return func() {}
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	if t.watchers == nil {
+		t.watchers = set.HandleSet[func(Subsystem, error)]{}
+	}
+	handle := t.watchers.Add(cb)
+	if t.timer == nil {
+		t.timer = time.AfterFunc(time.Minute, t.timerSelfCheck)
 	}
 	return func() {
-		mu.Lock()
-		defer mu.Unlock()
-		delete(watchers, handle)
-		if len(watchers) == 0 && timer != nil {
-			timer.Stop()
-			timer = nil
+		t.mu.Lock()
+		defer t.mu.Unlock()
+		delete(t.watchers, handle)
+		if len(t.watchers) == 0 && t.timer != nil {
+			t.timer.Stop()
+			t.timer = nil
 		}
 	}
 }
 
 // SetRouterHealth sets the state of the wgengine/router.Router.
-func SetRouterHealth(err error) { setErr(SysRouter, err) }
+func (t *Tracker) SetRouterHealth(err error) { t.setErr(SysRouter, err) }
 
 // RouterHealth returns the wgengine/router.Router error state.
-func RouterHealth() error { return get(SysRouter) }
+func (t *Tracker) RouterHealth() error { return t.get(SysRouter) }
 
 // SetDNSHealth sets the state of the net/dns.Manager
-func SetDNSHealth(err error) { setErr(SysDNS, err) }
+func (t *Tracker) SetDNSHealth(err error) { t.setErr(SysDNS, err) }
 
 // DNSHealth returns the net/dns.Manager error state.
-func DNSHealth() error { return get(SysDNS) }
+func (t *Tracker) DNSHealth() error { return t.get(SysDNS) }
 
 // SetDNSOSHealth sets the state of the net/dns.OSConfigurator
-func SetDNSOSHealth(err error) { setErr(SysDNSOS, err) }
+func (t *Tracker) SetDNSOSHealth(err error) { t.setErr(SysDNSOS, err) }
 
 // SetDNSManagerHealth sets the state of the Linux net/dns manager's
 // discovery of the /etc/resolv.conf situation.
-func SetDNSManagerHealth(err error) { setErr(SysDNSManager, err) }
+func (t *Tracker) SetDNSManagerHealth(err error) { t.setErr(SysDNSManager, err) }
 
 // DNSOSHealth returns the net/dns.OSConfigurator error state.
-func DNSOSHealth() error { return get(SysDNSOS) }
+func (t *Tracker) DNSOSHealth() error { return t.get(SysDNSOS) }
 
 // SetTKAHealth sets the health of the tailnet key authority.
-func SetTKAHealth(err error) { setErr(SysTKA, err) }
+func (t *Tracker) SetTKAHealth(err error) { t.setErr(SysTKA, err) }
 
 // TKAHealth returns the tailnet key authority error state.
-func TKAHealth() error { return get(SysTKA) }
+func (t *Tracker) TKAHealth() error { return t.get(SysTKA) }
 
 // SetLocalLogConfigHealth sets the error state of this client's local log configuration.
-func SetLocalLogConfigHealth(err error) {
-	mu.Lock()
-	defer mu.Unlock()
-	localLogConfigErr = err
+func (t *Tracker) SetLocalLogConfigHealth(err error) {
+	if t.nil() {
+		return
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.localLogConfigErr = err
 }
 
 // SetTLSConnectionError sets the error state for connections to a specific
 // host. Setting the error to nil will clear any previously-set error.
-func SetTLSConnectionError(host string, err error) {
-	mu.Lock()
-	defer mu.Unlock()
+func (t *Tracker) SetTLSConnectionError(host string, err error) {
+	if t.nil() {
+		return
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
 	if err == nil {
-		delete(tlsConnectionErrors, host)
+		delete(t.tlsConnectionErrors, host)
 	} else {
-		tlsConnectionErrors[host] = err
+		mak.Set(&t.tlsConnectionErrors, host, err)
 	}
 }
 
 func RegisterDebugHandler(typ string, h http.Handler) {
 	mu.Lock()
 	defer mu.Unlock()
-	debugHandler[typ] = h
+	mak.Set(&debugHandler, typ, h)
 }
 
 func DebugHandler(typ string) http.Handler {
@@ -249,24 +318,33 @@ func DebugHandler(typ string) http.Handler {
 	return debugHandler[typ]
 }
 
-func get(key Subsystem) error {
-	mu.Lock()
-	defer mu.Unlock()
-	return sysErr[key]
+func (t *Tracker) get(key Subsystem) error {
+	if t.nil() {
+		return nil
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	return t.sysErr[key]
 }
 
-func setErr(key Subsystem, err error) {
-	mu.Lock()
-	defer mu.Unlock()
-	setLocked(key, err)
+func (t *Tracker) setErr(key Subsystem, err error) {
+	if t.nil() {
+		return
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.setLocked(key, err)
 }
 
-func setLocked(key Subsystem, err error) {
-	old, ok := sysErr[key]
+func (t *Tracker) setLocked(key Subsystem, err error) {
+	if t.sysErr == nil {
+		t.sysErr = map[Subsystem]error{}
+	}
+	old, ok := t.sysErr[key]
 	if !ok && err == nil {
 		// Initial happy path.
-		sysErr[key] = nil
-		selfCheckLocked()
+		t.sysErr[key] = nil
+		t.selfCheckLocked()
 		return
 	}
 	if ok && (old == nil) == (err == nil) {
@@ -274,22 +352,25 @@ func setLocked(key Subsystem, err error) {
 		// don't run callbacks, but exact error might've
 		// changed, so note it.
 		if err != nil {
-			sysErr[key] = err
+			t.sysErr[key] = err
 		}
 		return
 	}
-	sysErr[key] = err
-	selfCheckLocked()
-	for _, cb := range watchers {
+	t.sysErr[key] = err
+	t.selfCheckLocked()
+	for _, cb := range t.watchers {
 		go cb(key, err)
 	}
 }
 
-func SetControlHealth(problems []string) {
-	mu.Lock()
-	defer mu.Unlock()
-	controlHealth = problems
-	selfCheckLocked()
+func (t *Tracker) SetControlHealth(problems []string) {
+	if t.nil() {
+		return
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.controlHealth = problems
+	t.selfCheckLocked()
 }
 
 // GotStreamedMapResponse notes that we got a tailcfg.MapResponse
@@ -297,177 +378,224 @@ func SetControlHealth(problems []string) {
 //
 // This also notes that a map poll is in progress. To unset that, call
 // SetOutOfPollNetMap().
-func GotStreamedMapResponse() {
-	mu.Lock()
-	defer mu.Unlock()
-	lastStreamedMapResponse = time.Now()
-	if !inMapPoll {
-		inMapPoll = true
-		inMapPollSince = time.Now()
+func (t *Tracker) GotStreamedMapResponse() {
+	if t.nil() {
+		return
 	}
-	selfCheckLocked()
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.lastStreamedMapResponse = time.Now()
+	if !t.inMapPoll {
+		t.inMapPoll = true
+		t.inMapPollSince = time.Now()
+	}
+	t.selfCheckLocked()
 }
 
 // SetOutOfPollNetMap records that the client is no longer in
 // an HTTP map request long poll to the control plane.
-func SetOutOfPollNetMap() {
-	mu.Lock()
-	defer mu.Unlock()
-	if !inMapPoll {
+func (t *Tracker) SetOutOfPollNetMap() {
+	if t.nil() {
 		return
 	}
-	inMapPoll = false
-	lastMapPollEndedAt = time.Now()
-	selfCheckLocked()
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	if !t.inMapPoll {
+		return
+	}
+	t.inMapPoll = false
+	t.lastMapPollEndedAt = time.Now()
+	t.selfCheckLocked()
 }
 
 // GetInPollNetMap reports whether the client has an open
 // HTTP long poll open to the control plane.
-func GetInPollNetMap() bool {
-	mu.Lock()
-	defer mu.Unlock()
-	return inMapPoll
+func (t *Tracker) GetInPollNetMap() bool {
+	if t.nil() {
+		return false
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	return t.inMapPoll
 }
 
 // SetMagicSockDERPHome notes what magicsock's view of its home DERP is.
 //
 // The homeless parameter is whether magicsock is running in DERP-disconnected
 // mode, without discovering and maintaining a connection to its home DERP.
-func SetMagicSockDERPHome(region int, homeless bool) {
-	mu.Lock()
-	defer mu.Unlock()
-	derpHomeRegion = region
-	derpHomeless = homeless
-	selfCheckLocked()
+func (t *Tracker) SetMagicSockDERPHome(region int, homeless bool) {
+	if t.nil() {
+		return
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.derpHomeRegion = region
+	t.derpHomeless = homeless
+	t.selfCheckLocked()
 }
 
 // NoteMapRequestHeard notes whenever we successfully sent a map request
 // to control for which we received a 200 response.
-func NoteMapRequestHeard(mr *tailcfg.MapRequest) {
-	mu.Lock()
-	defer mu.Unlock()
+func (t *Tracker) NoteMapRequestHeard(mr *tailcfg.MapRequest) {
+	if t.nil() {
+		return
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
 	// TODO: extract mr.HostInfo.NetInfo.PreferredDERP, compare
 	// against SetMagicSockDERPHome and
 	// SetDERPRegionConnectedState
 
-	lastMapRequestHeard = time.Now()
-	selfCheckLocked()
+	t.lastMapRequestHeard = time.Now()
+	t.selfCheckLocked()
 }
 
-func SetDERPRegionConnectedState(region int, connected bool) {
-	mu.Lock()
-	defer mu.Unlock()
-	derpRegionConnected[region] = connected
-	selfCheckLocked()
+func (t *Tracker) SetDERPRegionConnectedState(region int, connected bool) {
+	if t.nil() {
+		return
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	mak.Set(&t.derpRegionConnected, region, connected)
+	t.selfCheckLocked()
 }
 
 // SetDERPRegionHealth sets or clears any problem associated with the
 // provided DERP region.
-func SetDERPRegionHealth(region int, problem string) {
-	mu.Lock()
-	defer mu.Unlock()
-	if problem == "" {
-		delete(derpRegionHealthProblem, region)
-	} else {
-		derpRegionHealthProblem[region] = problem
+func (t *Tracker) SetDERPRegionHealth(region int, problem string) {
+	if t.nil() {
+		return
 	}
-	selfCheckLocked()
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	if problem == "" {
+		delete(t.derpRegionHealthProblem, region)
+	} else {
+		mak.Set(&t.derpRegionHealthProblem, region, problem)
+	}
+	t.selfCheckLocked()
 }
 
 // NoteDERPRegionReceivedFrame is called to note that a frame was received from
 // the given DERP region at the current time.
-func NoteDERPRegionReceivedFrame(region int) {
-	mu.Lock()
-	defer mu.Unlock()
-	derpRegionLastFrame[region] = time.Now()
-	selfCheckLocked()
+func (t *Tracker) NoteDERPRegionReceivedFrame(region int) {
+	if t.nil() {
+		return
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	mak.Set(&t.derpRegionLastFrame, region, time.Now())
+	t.selfCheckLocked()
 }
 
 // GetDERPRegionReceivedTime returns the last time that a frame was received
 // from the given DERP region, or the zero time if no communication with that
 // region has occurred.
-func GetDERPRegionReceivedTime(region int) time.Time {
-	mu.Lock()
-	defer mu.Unlock()
-	return derpRegionLastFrame[region]
+func (t *Tracker) GetDERPRegionReceivedTime(region int) time.Time {
+	if t.nil() {
+		return time.Time{}
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	return t.derpRegionLastFrame[region]
 }
 
 // state is an ipn.State.String() value: "Running", "Stopped", "NeedsLogin", etc.
-func SetIPNState(state string, wantRunning bool) {
-	mu.Lock()
-	defer mu.Unlock()
-	ipnState = state
-	ipnWantRunning = wantRunning
-	selfCheckLocked()
+func (t *Tracker) SetIPNState(state string, wantRunning bool) {
+	if t.nil() {
+		return
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.ipnState = state
+	t.ipnWantRunning = wantRunning
+	t.selfCheckLocked()
 }
 
 // SetAnyInterfaceUp sets whether any network interface is up.
-func SetAnyInterfaceUp(up bool) {
-	mu.Lock()
-	defer mu.Unlock()
-	anyInterfaceUp = up
-	selfCheckLocked()
+func (t *Tracker) SetAnyInterfaceUp(up bool) {
+	if t.nil() {
+		return
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.anyInterfaceUp.Set(up)
+	t.selfCheckLocked()
 }
 
 // SetUDP4Unbound sets whether the udp4 bind failed completely.
-func SetUDP4Unbound(unbound bool) {
-	mu.Lock()
-	defer mu.Unlock()
-	udp4Unbound = unbound
-	selfCheckLocked()
+func (t *Tracker) SetUDP4Unbound(unbound bool) {
+	if t.nil() {
+		return
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.udp4Unbound = unbound
+	t.selfCheckLocked()
 }
 
 // SetAuthRoutineInError records the latest error encountered as a result of a
 // login attempt. Providing a nil error indicates successful login, or that
 // being logged in w/coordination is not currently desired.
-func SetAuthRoutineInError(err error) {
-	mu.Lock()
-	defer mu.Unlock()
-	lastLoginErr = err
+func (t *Tracker) SetAuthRoutineInError(err error) {
+	if t.nil() {
+		return
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.lastLoginErr = err
 }
 
-func timerSelfCheck() {
-	mu.Lock()
-	defer mu.Unlock()
-	checkReceiveFuncs()
-	selfCheckLocked()
-	if timer != nil {
-		timer.Reset(time.Minute)
+func (t *Tracker) timerSelfCheck() {
+	if t.nil() {
+		return
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.checkReceiveFuncsLocked()
+	t.selfCheckLocked()
+	if t.timer != nil {
+		t.timer.Reset(time.Minute)
 	}
 }
 
-func selfCheckLocked() {
-	if ipnState == "" {
+func (t *Tracker) selfCheckLocked() {
+	if t.ipnState == "" {
 		// Don't check yet.
 		return
 	}
-	setLocked(SysOverall, overallErrorLocked())
+	t.setLocked(SysOverall, t.overallErrorLocked())
 }
 
 // OverallError returns a summary of the health state.
 //
 // If there are multiple problems, the error will be of type
 // multierr.Error.
-func OverallError() error {
-	mu.Lock()
-	defer mu.Unlock()
-	return overallErrorLocked()
+func (t *Tracker) OverallError() error {
+	if t.nil() {
+		return nil
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	return t.overallErrorLocked()
 }
 
 var fakeErrForTesting = envknob.RegisterString("TS_DEBUG_FAKE_HEALTH_ERROR")
 
-// networkErrorf creates an error that indicates issues with outgoing network
+// networkErrorfLocked creates an error that indicates issues with outgoing network
 // connectivity. Any active warnings related to network connectivity will
 // automatically be appended to it.
-func networkErrorf(format string, a ...any) error {
+//
+// t.mu must be held.
+func (t *Tracker) networkErrorfLocked(format string, a ...any) error {
 	errs := []error{
 		fmt.Errorf(format, a...),
 	}
-	for w := range warnables {
+	for _, w := range t.warnables {
 		if !w.hasConnectivityImpact {
 			continue
 		}
-		if err := w.get(); err != nil {
+		if err := t.warnableVal[w]; err != nil {
 			errs = append(errs, err)
 		}
 	}
@@ -477,81 +605,82 @@ func networkErrorf(format string, a ...any) error {
 	return multierr.New(errs...)
 }
 
-var errNetworkDown = networkErrorf("network down")
-var errNotInMapPoll = networkErrorf("not in map poll")
+var errNetworkDown = errors.New("network down")
+var errNotInMapPoll = errors.New("not in map poll")
 var errNoDERPHome = errors.New("no DERP home")
-var errNoUDP4Bind = networkErrorf("no udp4 bind")
+var errNoUDP4Bind = errors.New("no udp4 bind")
 
-func overallErrorLocked() error {
-	if !anyInterfaceUp {
+func (t *Tracker) overallErrorLocked() error {
+	if v, ok := t.anyInterfaceUp.Get(); ok && !v {
 		return errNetworkDown
 	}
-	if localLogConfigErr != nil {
-		return localLogConfigErr
+	if t.localLogConfigErr != nil {
+		return t.localLogConfigErr
 	}
-	if !ipnWantRunning {
-		return fmt.Errorf("state=%v, wantRunning=%v", ipnState, ipnWantRunning)
+	if !t.ipnWantRunning {
+		return fmt.Errorf("state=%v, wantRunning=%v", t.ipnState, t.ipnWantRunning)
 	}
-	if lastLoginErr != nil {
-		return fmt.Errorf("not logged in, last login error=%v", lastLoginErr)
+	if t.lastLoginErr != nil {
+		return fmt.Errorf("not logged in, last login error=%v", t.lastLoginErr)
 	}
 	now := time.Now()
-	if !inMapPoll && (lastMapPollEndedAt.IsZero() || now.Sub(lastMapPollEndedAt) > 10*time.Second) {
+	if !t.inMapPoll && (t.lastMapPollEndedAt.IsZero() || now.Sub(t.lastMapPollEndedAt) > 10*time.Second) {
 		return errNotInMapPoll
 	}
 	const tooIdle = 2*time.Minute + 5*time.Second
-	if d := now.Sub(lastStreamedMapResponse).Round(time.Second); d > tooIdle {
-		return networkErrorf("no map response in %v", d)
+	if d := now.Sub(t.lastStreamedMapResponse).Round(time.Second); d > tooIdle {
+		return t.networkErrorfLocked("no map response in %v", d)
 	}
-	if !derpHomeless {
-		rid := derpHomeRegion
+	if !t.derpHomeless {
+		rid := t.derpHomeRegion
 		if rid == 0 {
 			return errNoDERPHome
 		}
-		if !derpRegionConnected[rid] {
-			return networkErrorf("not connected to home DERP region %v", rid)
+		if !t.derpRegionConnected[rid] {
+			return t.networkErrorfLocked("not connected to home DERP region %v", rid)
 		}
-		if d := now.Sub(derpRegionLastFrame[rid]).Round(time.Second); d > tooIdle {
-			return networkErrorf("haven't heard from home DERP region %v in %v", rid, d)
+		if d := now.Sub(t.derpRegionLastFrame[rid]).Round(time.Second); d > tooIdle {
+			return t.networkErrorfLocked("haven't heard from home DERP region %v in %v", rid, d)
 		}
 	}
-	if udp4Unbound {
+	if t.udp4Unbound {
 		return errNoUDP4Bind
 	}
 
 	// TODO: use
-	_ = inMapPollSince
-	_ = lastMapPollEndedAt
-	_ = lastStreamedMapResponse
-	_ = lastMapRequestHeard
+	_ = t.inMapPollSince
+	_ = t.lastMapPollEndedAt
+	_ = t.lastStreamedMapResponse
+	_ = t.lastMapRequestHeard
 
 	var errs []error
-	for _, recv := range receiveFuncs {
-		if recv.missing {
-			errs = append(errs, fmt.Errorf("%s is not running", recv.name))
+	for i := range t.MagicSockReceiveFuncs {
+		f := &t.MagicSockReceiveFuncs[i]
+		if f.missing {
+			errs = append(errs, fmt.Errorf("%s is not running", f.name))
 		}
 	}
-	for sys, err := range sysErr {
+	for sys, err := range t.sysErr {
 		if err == nil || sys == SysOverall {
 			continue
 		}
 		errs = append(errs, fmt.Errorf("%v: %w", sys, err))
 	}
-	for w := range warnables {
-		if err := w.get(); err != nil {
+	for _, w := range t.warnables {
+		if err := t.warnableVal[w]; err != nil {
 			errs = append(errs, err)
 		}
 	}
-	for regionID, problem := range derpRegionHealthProblem {
+	for regionID, problem := range t.derpRegionHealthProblem {
 		errs = append(errs, fmt.Errorf("derp%d: %v", regionID, problem))
 	}
-	for _, s := range controlHealth {
+	for _, s := range t.controlHealth {
 		errs = append(errs, errors.New(s))
 	}
 	if err := envknob.ApplyDiskConfigError(); err != nil {
 		errs = append(errs, err)
 	}
-	for serverName, err := range tlsConnectionErrors {
+	for serverName, err := range t.tlsConnectionErrors {
 		errs = append(errs, fmt.Errorf("TLS connection error for %q: %w", serverName, err))
 	}
 	if e := fakeErrForTesting(); len(errs) == 0 && e != "" {
@@ -564,63 +693,69 @@ func overallErrorLocked() error {
 	return multierr.New(errs...)
 }
 
-var (
-	ReceiveIPv4 = ReceiveFuncStats{name: "ReceiveIPv4"}
-	ReceiveIPv6 = ReceiveFuncStats{name: "ReceiveIPv6"}
-	ReceiveDERP = ReceiveFuncStats{name: "ReceiveDERP"}
-
-	receiveFuncs = []*ReceiveFuncStats{&ReceiveIPv4, &ReceiveIPv6, &ReceiveDERP}
-)
-
-func init() {
-	if runtime.GOOS == "js" {
-		receiveFuncs = receiveFuncs[2:] // ignore IPv4 and IPv6
-	}
-}
-
 // ReceiveFuncStats tracks the calls made to a wireguard-go receive func.
 type ReceiveFuncStats struct {
 	// name is the name of the receive func.
+	// It's lazily populated.
 	name string
 	// numCalls is the number of times the receive func has ever been called.
 	// It is required because it is possible for a receive func's wireguard-go goroutine
 	// to be active even though the receive func isn't.
 	// The wireguard-go goroutine alternates between calling the receive func and
 	// processing what the func returned.
-	numCalls uint64 // accessed atomically
+	numCalls atomic.Uint64
 	// prevNumCalls is the value of numCalls last time the health check examined it.
 	prevNumCalls uint64
 	// inCall indicates whether the receive func is currently running.
-	inCall uint32 // bool, accessed atomically
+	inCall atomic.Bool
 	// missing indicates whether the receive func is not running.
 	missing bool
 }
 
 func (s *ReceiveFuncStats) Enter() {
-	atomic.AddUint64(&s.numCalls, 1)
-	atomic.StoreUint32(&s.inCall, 1)
+	s.numCalls.Add(1)
+	s.inCall.Store(true)
 }
 
 func (s *ReceiveFuncStats) Exit() {
-	atomic.StoreUint32(&s.inCall, 0)
+	s.inCall.Store(false)
 }
 
-func checkReceiveFuncs() {
-	for _, recv := range receiveFuncs {
-		recv.missing = false
-		prev := recv.prevNumCalls
-		numCalls := atomic.LoadUint64(&recv.numCalls)
-		recv.prevNumCalls = numCalls
+// ReceiveFuncStats returns the ReceiveFuncStats tracker for the given func
+// type.
+//
+// If t is nil, it returns nil.
+func (t *Tracker) ReceiveFuncStats(which ReceiveFunc) *ReceiveFuncStats {
+	if t == nil {
+		return nil
+	}
+	return &t.MagicSockReceiveFuncs[which]
+}
+
+func (t *Tracker) checkReceiveFuncsLocked() {
+	for i := range t.MagicSockReceiveFuncs {
+		f := &t.MagicSockReceiveFuncs[i]
+		if f.name == "" {
+			f.name = (ReceiveFunc(i)).String()
+		}
+		if runtime.GOOS == "js" && i < 2 {
+			// Skip IPv4 and IPv6 on js.
+			continue
+		}
+		f.missing = false
+		prev := f.prevNumCalls
+		numCalls := f.numCalls.Load()
+		f.prevNumCalls = numCalls
 		if numCalls > prev {
 			// OK: the function has gotten called since last we checked
 			continue
 		}
-		if atomic.LoadUint32(&recv.inCall) == 1 {
+		if f.inCall.Load() {
 			// OK: the function is active, probably blocked due to inactivity
 			continue
 		}
 		// Not OK: The function is not active, and not accumulating new calls.
 		// It is probably MIA.
-		recv.missing = true
+		f.missing = true
 	}
 }

health/health_test.go

@@ -8,17 +8,15 @@ import (
 	"fmt"
 	"reflect"
 	"testing"
-
-	"tailscale.com/util/set"
 )
 
 func TestAppendWarnableDebugFlags(t *testing.T) {
-	resetWarnables()
+	var tr Tracker
 
 	for i := range 10 {
 		w := NewWarnable(WithMapDebugFlag(fmt.Sprint(i)))
 		if i%2 == 0 {
-			w.Set(errors.New("boom"))
+			tr.SetWarnable(w, errors.New("boom"))
 		}
 	}
 
@@ -27,15 +25,27 @@ func TestAppendWarnableDebugFlags(t *testing.T) {
 	var got []string
 	for range 20 {
 		got = append(got[:0], "z", "y")
-		got = AppendWarnableDebugFlags(got)
+		got = tr.AppendWarnableDebugFlags(got)
 		if !reflect.DeepEqual(got, want) {
 			t.Fatalf("AppendWarnableDebugFlags = %q; want %q", got, want)
 		}
 	}
 }
 
-func resetWarnables() {
-	mu.Lock()
-	defer mu.Unlock()
-	warnables = set.Set[*Warnable]{}
+// Test that all exported methods on *Tracker don't panic with a nil receiver.
+func TestNilMethodsDontCrash(t *testing.T) {
+	var nilt *Tracker
+	rv := reflect.ValueOf(nilt)
+	for i := 0; i < rv.NumMethod(); i++ {
+		mt := rv.Type().Method(i)
+		t.Logf("calling Tracker.%s ...", mt.Name)
+		var args []reflect.Value
+		for j := 0; j < mt.Type.NumIn(); j++ {
+			if j == 0 && mt.Type.In(j) == reflect.TypeFor[*Tracker]() {
+				continue
+			}
+			args = append(args, reflect.Zero(mt.Type.In(j)))
+		}
+		rv.Method(i).Call(args)
+	}
 }

ipn/ipnlocal/local.go

@@ -170,6 +170,7 @@ type LocalBackend struct {
 	keyLogf               logger.Logf        // for printing list of peers on change
 	statsLogf             logger.Logf        // for printing peers stats on change
 	sys                   *tsd.System
+	health                *health.Tracker // always non-nil
 	e                     wgengine.Engine // non-nil; TODO(bradfitz): remove; use sys
 	store                 ipn.StateStore  // non-nil; TODO(bradfitz): remove; use sys
 	dialer                *tsdial.Dialer  // non-nil; TODO(bradfitz): remove; use sys
@@ -326,6 +327,16 @@ type LocalBackend struct {
 	outgoingFiles map[string]*ipn.OutgoingFile
 }
 
+// HealthTracker returns the health tracker for the backend.
+func (b *LocalBackend) HealthTracker() *health.Tracker {
+	return b.health
+}
+
+// NetMon returns the network monitor for the backend.
+func (b *LocalBackend) NetMon() *netmon.Monitor {
+	return b.sys.NetMon.Get()
+}
+
 type updateStatus struct {
 	started bool
 }
@@ -386,6 +397,7 @@ func NewLocalBackend(logf logger.Logf, logID logid.PublicID, sys *tsd.System, lo
 		keyLogf:             logger.LogOnChange(logf, 5*time.Minute, clock.Now),
 		statsLogf:           logger.LogOnChange(logf, 5*time.Minute, clock.Now),
 		sys:                 sys,
+		health:              sys.HealthTracker(),
 		conf:                sys.InitialConfig,
 		e:                   e,
 		dialer:              dialer,
@@ -403,7 +415,7 @@ func NewLocalBackend(logf logger.Logf, logID logid.PublicID, sys *tsd.System, lo
 	}
 
 	netMon := sys.NetMon.Get()
-	b.sockstatLogger, err = sockstatlog.NewLogger(logpolicy.LogsDir(logf), logf, logID, netMon)
+	b.sockstatLogger, err = sockstatlog.NewLogger(logpolicy.LogsDir(logf), logf, logID, netMon, sys.HealthTracker())
 	if err != nil {
 		log.Printf("error setting up sockstat logger: %v", err)
 	}
@@ -426,7 +438,7 @@ func NewLocalBackend(logf logger.Logf, logID logid.PublicID, sys *tsd.System, lo
 	b.linkChange(&netmon.ChangeDelta{New: netMon.InterfaceState()})
 	b.unregisterNetMon = netMon.RegisterChangeCallback(b.linkChange)
 
-	b.unregisterHealthWatch = health.RegisterWatcher(b.onHealthChange)
+	b.unregisterHealthWatch = b.health.RegisterWatcher(b.onHealthChange)
 
 	if tunWrap, ok := b.sys.Tun.GetOK(); ok {
 		tunWrap.PeerAPIPort = b.GetPeerAPIPort
@@ -625,7 +637,7 @@ func (b *LocalBackend) linkChange(delta *netmon.ChangeDelta) {
 	// If the local network configuration has changed, our filter may
 	// need updating to tweak default routes.
 	b.updateFilterLocked(b.netMap, b.pm.CurrentPrefs())
-	updateExitNodeUsageWarning(b.pm.CurrentPrefs(), delta.New)
+	updateExitNodeUsageWarning(b.pm.CurrentPrefs(), delta.New, b.health)
 
 	if peerAPIListenAsync && b.netMap != nil && b.state == ipn.Running {
 		want := b.netMap.GetAddresses().Len()
@@ -761,7 +773,7 @@ func (b *LocalBackend) UpdateStatus(sb *ipnstate.StatusBuilder) {
 				}
 			}
 		}
-		if err := health.OverallError(); err != nil {
+		if err := b.health.OverallError(); err != nil {
 			switch e := err.(type) {
 			case multierr.Error:
 				for _, err := range e.Errors() {
@@ -820,7 +832,7 @@ func (b *LocalBackend) UpdateStatus(sb *ipnstate.StatusBuilder) {
 
 	sb.MutateSelfStatus(func(ss *ipnstate.PeerStatus) {
 		ss.OS = version.OS()
-		ss.Online = health.GetInPollNetMap()
+		ss.Online = b.health.GetInPollNetMap()
 		if b.netMap != nil {
 			ss.InNetworkMap = true
 			if hi := b.netMap.SelfNode.Hostinfo(); hi.Valid() {
@@ -1221,7 +1233,7 @@ func (b *LocalBackend) SetControlClientStatus(c controlclient.Client, st control
 	if st.NetMap != nil {
 		if envknob.NoLogsNoSupport() && st.NetMap.HasCap(tailcfg.CapabilityDataPlaneAuditLogs) {
 			msg := "tailnet requires logging to be enabled. Remove --no-logs-no-support from tailscaled command line."
-			health.SetLocalLogConfigHealth(errors.New(msg))
+			b.health.SetLocalLogConfigHealth(errors.New(msg))
 			// Connecting to this tailnet without logging is forbidden; boot us outta here.
 			b.mu.Lock()
 			prefs.WantRunning = false
@@ -1751,6 +1763,7 @@ func (b *LocalBackend) Start(opts ipn.Options) error {
 		DiscoPublicKey:             discoPublic,
 		DebugFlags:                 debugFlags,
 		NetMon:                     b.sys.NetMon.Get(),
+		HealthTracker:              b.health,
 		Pinger:                     b,
 		PopBrowserURL:              b.tellClientToBrowseToURL,
 		OnClientVersion:            b.onClientVersion,
@@ -1851,10 +1864,10 @@ func (b *LocalBackend) updateFilterLocked(netMap *netmap.NetworkMap, prefs ipn.P
 
 		if packetFilterPermitsUnlockedNodes(b.peers, packetFilter) {
 			err := errors.New("server sent invalid packet filter permitting traffic to unlocked nodes; rejecting all packets for safety")
-			warnInvalidUnsignedNodes.Set(err)
+			b.health.SetWarnable(warnInvalidUnsignedNodes, err)
 			packetFilter = nil
 		} else {
-			warnInvalidUnsignedNodes.Set(nil)
+			b.health.SetWarnable(warnInvalidUnsignedNodes, nil)
 		}
 	}
 	if prefs.Valid() {
@@ -3048,7 +3061,7 @@ var warnExitNodeUsage = health.NewWarnable(health.WithConnectivityImpact())
 
 // updateExitNodeUsageWarning updates a warnable meant to notify users of
 // configuration issues that could break exit node usage.
-func updateExitNodeUsageWarning(p ipn.PrefsView, state *interfaces.State) {
+func updateExitNodeUsageWarning(p ipn.PrefsView, state *interfaces.State, health *health.Tracker) {
 	var result error
 	if p.ExitNodeIP().IsValid() || p.ExitNodeID() != "" {
 		warn, _ := netutil.CheckReversePathFiltering(state)
@@ -3057,7 +3070,7 @@ func updateExitNodeUsageWarning(p ipn.PrefsView, state *interfaces.State) {
 			result = fmt.Errorf("%s: %v, %s", healthmsg.WarnExitNodeUsage, warn, comment)
 		}
 	}
-	warnExitNodeUsage.Set(result)
+	health.SetWarnable(warnExitNodeUsage, result)
 }
 
 func (b *LocalBackend) checkExitNodePrefsLocked(p *ipn.Prefs) error {
@@ -3121,6 +3134,19 @@ func (b *LocalBackend) SetUseExitNodeEnabled(v bool) (ipn.PrefsView, error) {
 	return b.editPrefsLockedOnEntry(mp, unlock)
 }
 
+// MaybeClearAppConnector clears the routes from any AppConnector if
+// AdvertiseRoutes has been set in the MaskedPrefs.
+func (b *LocalBackend) MaybeClearAppConnector(mp *ipn.MaskedPrefs) error {
+	var err error
+	if b.appConnector != nil && mp.AdvertiseRoutesSet {
+		err = b.appConnector.ClearRoutes()
+		if err != nil {
+			b.logf("appc: clear routes error: %v", err)
+		}
+	}
+	return err
+}
+
 func (b *LocalBackend) EditPrefs(mp *ipn.MaskedPrefs) (ipn.PrefsView, error) {
 	if mp.SetsInternal() {
 		return ipn.PrefsView{}, errors.New("can't set Internal fields")
@@ -3499,8 +3525,22 @@ func (b *LocalBackend) reconfigAppConnectorLocked(nm *netmap.NetworkMap, prefs i
 		return
 	}
 
-	if b.appConnector == nil {
-		b.appConnector = appc.NewAppConnector(b.logf, b)
+	shouldAppCStoreRoutes := b.ControlKnobs().AppCStoreRoutes.Load()
+	if b.appConnector == nil || b.appConnector.ShouldStoreRoutes() != shouldAppCStoreRoutes {
+		var ri *appc.RouteInfo
+		var storeFunc func(*appc.RouteInfo) error
+		if shouldAppCStoreRoutes {
+			var err error
+			ri, err = b.readRouteInfoLocked()
+			if err != nil {
+				ri = &appc.RouteInfo{}
+				if err != ipn.ErrStateNotExist {
+					b.logf("Unsuccessful Read RouteInfo: ", err)
+				}
+			}
+			storeFunc = b.storeRouteInfo
+		}
+		b.appConnector = appc.NewAppConnector(b.logf, b, ri, storeFunc)
 	}
 	if nm == nil {
 		return
@@ -4254,7 +4294,7 @@ func (b *LocalBackend) enterStateLockedOnEntry(newState ipn.State, unlock unlock
 
 	// prefs may change irrespective of state; WantRunning should be explicitly
 	// set before potential early return even if the state is unchanged.
-	health.SetIPNState(newState.String(), prefs.Valid() && prefs.WantRunning())
+	b.health.SetIPNState(newState.String(), prefs.Valid() && prefs.WantRunning())
 	if oldState == newState {
 		return
 	}
@@ -4692,9 +4732,9 @@ func (b *LocalBackend) setNetMapLocked(nm *netmap.NetworkMap) {
 	b.pauseOrResumeControlClientLocked()
 
 	if nm != nil {
-		health.SetControlHealth(nm.ControlHealth)
+		b.health.SetControlHealth(nm.ControlHealth)
 	} else {
-		health.SetControlHealth(nil)
+		b.health.SetControlHealth(nil)
 	}
 
 	// Determine if file sharing is enabled
@@ -5679,9 +5719,9 @@ var warnSSHSELinux = health.NewWarnable()
 
 func (b *LocalBackend) updateSELinuxHealthWarning() {
 	if hostinfo.IsSELinuxEnforcing() {
-		warnSSHSELinux.Set(errors.New("SELinux is enabled; Tailscale SSH may not work. See https://tailscale.com/s/ssh-selinux"))
+		b.health.SetWarnable(warnSSHSELinux, errors.New("SELinux is enabled; Tailscale SSH may not work. See https://tailscale.com/s/ssh-selinux"))
 	} else {
-		warnSSHSELinux.Set(nil)
+		b.health.SetWarnable(warnSSHSELinux, nil)
 	}
 }
 
@@ -5908,7 +5948,7 @@ func (b *LocalBackend) resetForProfileChangeLockedOnEntry(unlock unlockOnce) err
 	b.lastServeConfJSON = mem.B(nil)
 	b.serveConfig = ipn.ServeConfigView{}
 	b.enterStateLockedOnEntry(ipn.NoState, unlock) // Reset state; releases b.mu
-	health.SetLocalLogConfigHealth(nil)
+	b.health.SetLocalLogConfigHealth(nil)
 	return b.Start(ipn.Options{})
 }
 
@@ -6193,6 +6233,43 @@ func (b *LocalBackend) UnadvertiseRoute(toRemove ...netip.Prefix) error {
 	return err
 }
 
+// namespace a key with the profile manager's current profile key, if any
+func namespaceKeyForCurrentProfile(pm *profileManager, key ipn.StateKey) ipn.StateKey {
+	return pm.CurrentProfile().Key + "||" + key
+}
+
+const routeInfoStateStoreKey ipn.StateKey = "_routeInfo"
+
+func (b *LocalBackend) storeRouteInfo(ri *appc.RouteInfo) error {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	if b.pm.CurrentProfile().ID == "" {
+		return nil
+	}
+	key := namespaceKeyForCurrentProfile(b.pm, routeInfoStateStoreKey)
+	bs, err := json.Marshal(ri)
+	if err != nil {
+		return err
+	}
+	return b.pm.WriteState(key, bs)
+}
+
+func (b *LocalBackend) readRouteInfoLocked() (*appc.RouteInfo, error) {
+	if b.pm.CurrentProfile().ID == "" {
+		return &appc.RouteInfo{}, nil
+	}
+	key := namespaceKeyForCurrentProfile(b.pm, routeInfoStateStoreKey)
+	bs, err := b.pm.Store().ReadState(key)
+	ri := &appc.RouteInfo{}
+	if err != nil {
+		return nil, err
+	}
+	if err := json.Unmarshal(bs, ri); err != nil {
+		return nil, err
+	}
+	return ri, nil
+}
+
 // seamlessRenewalEnabled reports whether seamless key renewals are enabled
 // (i.e. we saw our self node with the SeamlessKeyRenewal attr in a netmap).
 // This enables beta functionality of renewing node keys without breaking
@@ -6240,6 +6317,7 @@ func mayDeref[T any](p *T) (v T) {
 }
 
 var ErrNoPreferredDERP = errors.New("no preferred DERP, try again later")
+var ErrCannotSuggestExitNode = errors.New("unable to suggest an exit node, try again later")
 
 // SuggestExitNode computes a suggestion based on the current netmap and last netcheck report. If
 // there are multiple equally good options, one is selected at random, so the result is not stable. To be
@@ -6253,6 +6331,9 @@ func (b *LocalBackend) SuggestExitNode() (response apitype.ExitNodeSuggestionRes
 	lastReport := b.MagicConn().GetLastNetcheckReport(b.ctx)
 	netMap := b.netMap
 	b.mu.Unlock()
+	if lastReport == nil || netMap == nil {
+		return response, ErrCannotSuggestExitNode
+	}
 	seed := time.Now().UnixNano()
 	r := rand.New(rand.NewSource(seed))
 	return suggestExitNode(lastReport, netMap, r)

ipn/ipnlocal/local_test.go

@@ -54,6 +54,8 @@ import (
 	"tailscale.com/wgengine/wgcfg"
 )
 
+func fakeStoreRoutes(*appc.RouteInfo) error { return nil }
+
 func inRemove(ip netip.Addr) bool {
 	for _, pfx := range removeFromDefaultRoute {
 		if pfx.Contains(ip) {
@@ -1290,13 +1292,19 @@ func TestDNSConfigForNetmapForExitNodeConfigs(t *testing.T) {
 }
 
 func TestOfferingAppConnector(t *testing.T) {
-	b := newTestBackend(t)
-	if b.OfferingAppConnector() {
-		t.Fatal("unexpected offering app connector")
-	}
-	b.appConnector = appc.NewAppConnector(t.Logf, nil)
-	if !b.OfferingAppConnector() {
-		t.Fatal("unexpected not offering app connector")
+	for _, shouldStore := range []bool{false, true} {
+		b := newTestBackend(t)
+		if b.OfferingAppConnector() {
+			t.Fatal("unexpected offering app connector")
+		}
+		if shouldStore {
+			b.appConnector = appc.NewAppConnector(t.Logf, nil, &appc.RouteInfo{}, fakeStoreRoutes)
+		} else {
+			b.appConnector = appc.NewAppConnector(t.Logf, nil, nil, nil)
+		}
+		if !b.OfferingAppConnector() {
+			t.Fatal("unexpected not offering app connector")
+		}
 	}
 }
 
@@ -1341,21 +1349,27 @@ func TestRouterAdvertiserIgnoresContainedRoutes(t *testing.T) {
 }
 
 func TestObserveDNSResponse(t *testing.T) {
-	b := newTestBackend(t)
+	for _, shouldStore := range []bool{false, true} {
+		b := newTestBackend(t)
 
-	// ensure no error when no app connector is configured
-	b.ObserveDNSResponse(dnsResponse("example.com.", "192.0.0.8"))
+		// ensure no error when no app connector is configured
+		b.ObserveDNSResponse(dnsResponse("example.com.", "192.0.0.8"))
 
-	rc := &appctest.RouteCollector{}
-	b.appConnector = appc.NewAppConnector(t.Logf, rc)
-	b.appConnector.UpdateDomains([]string{"example.com"})
-	b.appConnector.Wait(context.Background())
+		rc := &appctest.RouteCollector{}
+		if shouldStore {
+			b.appConnector = appc.NewAppConnector(t.Logf, rc, &appc.RouteInfo{}, fakeStoreRoutes)
+		} else {
+			b.appConnector = appc.NewAppConnector(t.Logf, rc, nil, nil)
+		}
+		b.appConnector.UpdateDomains([]string{"example.com"})
+		b.appConnector.Wait(context.Background())
 
-	b.ObserveDNSResponse(dnsResponse("example.com.", "192.0.0.8"))
-	b.appConnector.Wait(context.Background())
-	wantRoutes := []netip.Prefix{netip.MustParsePrefix("192.0.0.8/32")}
-	if !slices.Equal(rc.Routes(), wantRoutes) {
-		t.Fatalf("got routes %v, want %v", rc.Routes(), wantRoutes)
+		b.ObserveDNSResponse(dnsResponse("example.com.", "192.0.0.8"))
+		b.appConnector.Wait(context.Background())
+		wantRoutes := []netip.Prefix{netip.MustParsePrefix("192.0.0.8/32")}
+		if !slices.Equal(rc.Routes(), wantRoutes) {
+			t.Fatalf("got routes %v, want %v", rc.Routes(), wantRoutes)
+		}
 	}
 }
 
@@ -3451,3 +3465,66 @@ func TestEnableAutoUpdates(t *testing.T) {
 		t.Fatalf("disabling auto-updates: got error: %v", err)
 	}
 }
+
+func TestReadWriteRouteInfo(t *testing.T) {
+	// set up a backend with more than one profile
+	b := newTestBackend(t)
+	prof1 := ipn.LoginProfile{ID: "id1", Key: "key1"}
+	prof2 := ipn.LoginProfile{ID: "id2", Key: "key2"}
+	b.pm.knownProfiles["id1"] = &prof1
+	b.pm.knownProfiles["id2"] = &prof2
+	b.pm.currentProfile = &prof1
+
+	// set up routeInfo
+	ri1 := &appc.RouteInfo{}
+	ri1.Wildcards = []string{"1"}
+
+	ri2 := &appc.RouteInfo{}
+	ri2.Wildcards = []string{"2"}
+
+	// read before write
+	readRi, err := b.readRouteInfoLocked()
+	if readRi != nil {
+		t.Fatalf("read before writing: want nil, got %v", readRi)
+	}
+	if err != ipn.ErrStateNotExist {
+		t.Fatalf("read before writing: want %v, got %v", ipn.ErrStateNotExist, err)
+	}
+
+	// write the first routeInfo
+	if err := b.storeRouteInfo(ri1); err != nil {
+		t.Fatal(err)
+	}
+
+	// write the other routeInfo as the other profile
+	if err := b.pm.SwitchProfile("id2"); err != nil {
+		t.Fatal(err)
+	}
+	if err := b.storeRouteInfo(ri2); err != nil {
+		t.Fatal(err)
+	}
+
+	// read the routeInfo of the first profile
+	if err := b.pm.SwitchProfile("id1"); err != nil {
+		t.Fatal(err)
+	}
+	readRi, err = b.readRouteInfoLocked()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !slices.Equal(readRi.Wildcards, ri1.Wildcards) {
+		t.Fatalf("read prof1 routeInfo wildcards:  want %v, got %v", ri1.Wildcards, readRi.Wildcards)
+	}
+
+	// read the routeInfo of the second profile
+	if err := b.pm.SwitchProfile("id2"); err != nil {
+		t.Fatal(err)
+	}
+	readRi, err = b.readRouteInfoLocked()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !slices.Equal(readRi.Wildcards, ri2.Wildcards) {
+		t.Fatalf("read prof2 routeInfo wildcards:  want %v, got %v", ri2.Wildcards, readRi.Wildcards)
+	}
+}

ipn/ipnlocal/network-lock.go

@@ -20,7 +20,6 @@ import (
 	"path/filepath"
 	"time"
 
-	"tailscale.com/health"
 	"tailscale.com/health/healthmsg"
 	"tailscale.com/ipn"
 	"tailscale.com/ipn/ipnstate"
@@ -59,11 +58,11 @@ type tkaState struct {
 // b.mu must be held.
 func (b *LocalBackend) tkaFilterNetmapLocked(nm *netmap.NetworkMap) {
 	if b.tka == nil && !b.capTailnetLock {
-		health.SetTKAHealth(nil)
+		b.health.SetTKAHealth(nil)
 		return
 	}
 	if b.tka == nil {
-		health.SetTKAHealth(nil)
+		b.health.SetTKAHealth(nil)
 		return // TKA not enabled.
 	}
 
@@ -117,9 +116,9 @@ func (b *LocalBackend) tkaFilterNetmapLocked(nm *netmap.NetworkMap) {
 
 	// Check that we ourselves are not locked out, report a health issue if so.
 	if nm.SelfNode.Valid() && b.tka.authority.NodeKeyAuthorized(nm.SelfNode.Key(), nm.SelfNode.KeySignature().AsSlice()) != nil {
-		health.SetTKAHealth(errors.New(healthmsg.LockedOut))
+		b.health.SetTKAHealth(errors.New(healthmsg.LockedOut))
 	} else {
-		health.SetTKAHealth(nil)
+		b.health.SetTKAHealth(nil)
 	}
 }
 
@@ -188,7 +187,7 @@ func (b *LocalBackend) tkaSyncIfNeeded(nm *netmap.NetworkMap, prefs ipn.PrefsVie
 				b.logf("Disablement failed, leaving TKA enabled. Error: %v", err)
 			} else {
 				isEnabled = false
-				health.SetTKAHealth(nil)
+				b.health.SetTKAHealth(nil)
 			}
 		} else {
 			return fmt.Errorf("[bug] unreachable invariant of wantEnabled w/ isEnabled")

ipn/ipnlocal/peerapi_test.go

@@ -687,185 +687,209 @@ func TestPeerAPIReplyToDNSQueries(t *testing.T) {
 }
 
 func TestPeerAPIPrettyReplyCNAME(t *testing.T) {
-	var h peerAPIHandler
-	h.remoteAddr = netip.MustParseAddrPort("100.150.151.152:12345")
+	for _, shouldStore := range []bool{false, true} {
+		var h peerAPIHandler
+		h.remoteAddr = netip.MustParseAddrPort("100.150.151.152:12345")
 
-	eng, _ := wgengine.NewFakeUserspaceEngine(logger.Discard, 0)
-	pm := must.Get(newProfileManager(new(mem.Store), t.Logf))
-	h.ps = &peerAPIServer{
-		b: &LocalBackend{
-			e:     eng,
-			pm:    pm,
-			store: pm.Store(),
-			// configure as an app connector just to enable the API.
-			appConnector: appc.NewAppConnector(t.Logf, &appctest.RouteCollector{}),
-		},
-	}
+		eng, _ := wgengine.NewFakeUserspaceEngine(logger.Discard, 0)
+		pm := must.Get(newProfileManager(new(mem.Store), t.Logf))
+		var a *appc.AppConnector
+		if shouldStore {
+			a = appc.NewAppConnector(t.Logf, &appctest.RouteCollector{}, &appc.RouteInfo{}, fakeStoreRoutes)
+		} else {
+			a = appc.NewAppConnector(t.Logf, &appctest.RouteCollector{}, nil, nil)
+		}
+		h.ps = &peerAPIServer{
+			b: &LocalBackend{
+				e:     eng,
+				pm:    pm,
+				store: pm.Store(),
+				// configure as an app connector just to enable the API.
+				appConnector: a,
+			},
+		}
 
-	h.ps.resolver = &fakeResolver{build: func(b *dnsmessage.Builder) {
-		b.CNAMEResource(
-			dnsmessage.ResourceHeader{
-				Name:  dnsmessage.MustNewName("www.example.com."),
-				Type:  dnsmessage.TypeCNAME,
-				Class: dnsmessage.ClassINET,
-				TTL:   0,
-			},
-			dnsmessage.CNAMEResource{
-				CNAME: dnsmessage.MustNewName("example.com."),
-			},
-		)
-		b.AResource(
-			dnsmessage.ResourceHeader{
-				Name:  dnsmessage.MustNewName("example.com."),
-				Type:  dnsmessage.TypeA,
-				Class: dnsmessage.ClassINET,
-				TTL:   0,
-			},
-			dnsmessage.AResource{
-				A: [4]byte{192, 0, 0, 8},
-			},
-		)
-	}}
-	f := filter.NewAllowAllForTest(logger.Discard)
-	h.ps.b.setFilter(f)
+		h.ps.resolver = &fakeResolver{build: func(b *dnsmessage.Builder) {
+			b.CNAMEResource(
+				dnsmessage.ResourceHeader{
+					Name:  dnsmessage.MustNewName("www.example.com."),
+					Type:  dnsmessage.TypeCNAME,
+					Class: dnsmessage.ClassINET,
+					TTL:   0,
+				},
+				dnsmessage.CNAMEResource{
+					CNAME: dnsmessage.MustNewName("example.com."),
+				},
+			)
+			b.AResource(
+				dnsmessage.ResourceHeader{
+					Name:  dnsmessage.MustNewName("example.com."),
+					Type:  dnsmessage.TypeA,
+					Class: dnsmessage.ClassINET,
+					TTL:   0,
+				},
+				dnsmessage.AResource{
+					A: [4]byte{192, 0, 0, 8},
+				},
+			)
+		}}
+		f := filter.NewAllowAllForTest(logger.Discard)
+		h.ps.b.setFilter(f)
 
-	if !h.replyToDNSQueries() {
-		t.Errorf("unexpectedly deny; wanted to be a DNS server")
-	}
+		if !h.replyToDNSQueries() {
+			t.Errorf("unexpectedly deny; wanted to be a DNS server")
+		}
 
-	w := httptest.NewRecorder()
-	h.handleDNSQuery(w, httptest.NewRequest("GET", "/dns-query?q=www.example.com.", nil))
-	if w.Code != http.StatusOK {
-		t.Errorf("unexpected status code: %v", w.Code)
-	}
-	var addrs []string
-	json.NewDecoder(w.Body).Decode(&addrs)
-	if len(addrs) == 0 {
-		t.Fatalf("no addresses returned")
-	}
-	for _, addr := range addrs {
-		netip.MustParseAddr(addr)
+		w := httptest.NewRecorder()
+		h.handleDNSQuery(w, httptest.NewRequest("GET", "/dns-query?q=www.example.com.", nil))
+		if w.Code != http.StatusOK {
+			t.Errorf("unexpected status code: %v", w.Code)
+		}
+		var addrs []string
+		json.NewDecoder(w.Body).Decode(&addrs)
+		if len(addrs) == 0 {
+			t.Fatalf("no addresses returned")
+		}
+		for _, addr := range addrs {
+			netip.MustParseAddr(addr)
+		}
 	}
 }
 
 func TestPeerAPIReplyToDNSQueriesAreObserved(t *testing.T) {
-	ctx := context.Background()
-	var h peerAPIHandler
-	h.remoteAddr = netip.MustParseAddrPort("100.150.151.152:12345")
+	for _, shouldStore := range []bool{false, true} {
+		ctx := context.Background()
+		var h peerAPIHandler
+		h.remoteAddr = netip.MustParseAddrPort("100.150.151.152:12345")
 
-	rc := &appctest.RouteCollector{}
-	eng, _ := wgengine.NewFakeUserspaceEngine(logger.Discard, 0)
-	pm := must.Get(newProfileManager(new(mem.Store), t.Logf))
-	h.ps = &peerAPIServer{
-		b: &LocalBackend{
-			e:            eng,
-			pm:           pm,
-			store:        pm.Store(),
-			appConnector: appc.NewAppConnector(t.Logf, rc),
-		},
-	}
-	h.ps.b.appConnector.UpdateDomains([]string{"example.com"})
-	h.ps.b.appConnector.Wait(ctx)
-
-	h.ps.resolver = &fakeResolver{build: func(b *dnsmessage.Builder) {
-		b.AResource(
-			dnsmessage.ResourceHeader{
-				Name:  dnsmessage.MustNewName("example.com."),
-				Type:  dnsmessage.TypeA,
-				Class: dnsmessage.ClassINET,
-				TTL:   0,
+		rc := &appctest.RouteCollector{}
+		eng, _ := wgengine.NewFakeUserspaceEngine(logger.Discard, 0)
+		pm := must.Get(newProfileManager(new(mem.Store), t.Logf))
+		var a *appc.AppConnector
+		if shouldStore {
+			a = appc.NewAppConnector(t.Logf, rc, &appc.RouteInfo{}, fakeStoreRoutes)
+		} else {
+			a = appc.NewAppConnector(t.Logf, rc, nil, nil)
+		}
+		h.ps = &peerAPIServer{
+			b: &LocalBackend{
+				e:            eng,
+				pm:           pm,
+				store:        pm.Store(),
+				appConnector: a,
 			},
-			dnsmessage.AResource{
-				A: [4]byte{192, 0, 0, 8},
-			},
-		)
-	}}
-	f := filter.NewAllowAllForTest(logger.Discard)
-	h.ps.b.setFilter(f)
+		}
+		h.ps.b.appConnector.UpdateDomains([]string{"example.com"})
+		h.ps.b.appConnector.Wait(ctx)
 
-	if !h.ps.b.OfferingAppConnector() {
-		t.Fatal("expecting to be offering app connector")
-	}
-	if !h.replyToDNSQueries() {
-		t.Errorf("unexpectedly deny; wanted to be a DNS server")
-	}
+		h.ps.resolver = &fakeResolver{build: func(b *dnsmessage.Builder) {
+			b.AResource(
+				dnsmessage.ResourceHeader{
+					Name:  dnsmessage.MustNewName("example.com."),
+					Type:  dnsmessage.TypeA,
+					Class: dnsmessage.ClassINET,
+					TTL:   0,
+				},
+				dnsmessage.AResource{
+					A: [4]byte{192, 0, 0, 8},
+				},
+			)
+		}}
+		f := filter.NewAllowAllForTest(logger.Discard)
+		h.ps.b.setFilter(f)
 
-	w := httptest.NewRecorder()
-	h.handleDNSQuery(w, httptest.NewRequest("GET", "/dns-query?q=example.com.", nil))
-	if w.Code != http.StatusOK {
-		t.Errorf("unexpected status code: %v", w.Code)
-	}
-	h.ps.b.appConnector.Wait(ctx)
+		if !h.ps.b.OfferingAppConnector() {
+			t.Fatal("expecting to be offering app connector")
+		}
+		if !h.replyToDNSQueries() {
+			t.Errorf("unexpectedly deny; wanted to be a DNS server")
+		}
 
-	wantRoutes := []netip.Prefix{netip.MustParsePrefix("192.0.0.8/32")}
-	if !slices.Equal(rc.Routes(), wantRoutes) {
-		t.Errorf("got %v; want %v", rc.Routes(), wantRoutes)
+		w := httptest.NewRecorder()
+		h.handleDNSQuery(w, httptest.NewRequest("GET", "/dns-query?q=example.com.", nil))
+		if w.Code != http.StatusOK {
+			t.Errorf("unexpected status code: %v", w.Code)
+		}
+		h.ps.b.appConnector.Wait(ctx)
+
+		wantRoutes := []netip.Prefix{netip.MustParsePrefix("192.0.0.8/32")}
+		if !slices.Equal(rc.Routes(), wantRoutes) {
+			t.Errorf("got %v; want %v", rc.Routes(), wantRoutes)
+		}
 	}
 }
 
 func TestPeerAPIReplyToDNSQueriesAreObservedWithCNAMEFlattening(t *testing.T) {
-	ctx := context.Background()
-	var h peerAPIHandler
-	h.remoteAddr = netip.MustParseAddrPort("100.150.151.152:12345")
+	for _, shouldStore := range []bool{false, true} {
+		ctx := context.Background()
+		var h peerAPIHandler
+		h.remoteAddr = netip.MustParseAddrPort("100.150.151.152:12345")
 
-	rc := &appctest.RouteCollector{}
-	eng, _ := wgengine.NewFakeUserspaceEngine(logger.Discard, 0)
-	pm := must.Get(newProfileManager(new(mem.Store), t.Logf))
-	h.ps = &peerAPIServer{
-		b: &LocalBackend{
-			e:            eng,
-			pm:           pm,
-			store:        pm.Store(),
-			appConnector: appc.NewAppConnector(t.Logf, rc),
-		},
-	}
-	h.ps.b.appConnector.UpdateDomains([]string{"www.example.com"})
-	h.ps.b.appConnector.Wait(ctx)
-
-	h.ps.resolver = &fakeResolver{build: func(b *dnsmessage.Builder) {
-		b.CNAMEResource(
-			dnsmessage.ResourceHeader{
-				Name:  dnsmessage.MustNewName("www.example.com."),
-				Type:  dnsmessage.TypeCNAME,
-				Class: dnsmessage.ClassINET,
-				TTL:   0,
+		rc := &appctest.RouteCollector{}
+		eng, _ := wgengine.NewFakeUserspaceEngine(logger.Discard, 0)
+		pm := must.Get(newProfileManager(new(mem.Store), t.Logf))
+		var a *appc.AppConnector
+		if shouldStore {
+			a = appc.NewAppConnector(t.Logf, rc, &appc.RouteInfo{}, fakeStoreRoutes)
+		} else {
+			a = appc.NewAppConnector(t.Logf, rc, nil, nil)
+		}
+		h.ps = &peerAPIServer{
+			b: &LocalBackend{
+				e:            eng,
+				pm:           pm,
+				store:        pm.Store(),
+				appConnector: a,
 			},
-			dnsmessage.CNAMEResource{
-				CNAME: dnsmessage.MustNewName("example.com."),
-			},
-		)
-		b.AResource(
-			dnsmessage.ResourceHeader{
-				Name:  dnsmessage.MustNewName("example.com."),
-				Type:  dnsmessage.TypeA,
-				Class: dnsmessage.ClassINET,
-				TTL:   0,
-			},
-			dnsmessage.AResource{
-				A: [4]byte{192, 0, 0, 8},
-			},
-		)
-	}}
-	f := filter.NewAllowAllForTest(logger.Discard)
-	h.ps.b.setFilter(f)
+		}
+		h.ps.b.appConnector.UpdateDomains([]string{"www.example.com"})
+		h.ps.b.appConnector.Wait(ctx)
 
-	if !h.ps.b.OfferingAppConnector() {
-		t.Fatal("expecting to be offering app connector")
-	}
-	if !h.replyToDNSQueries() {
-		t.Errorf("unexpectedly deny; wanted to be a DNS server")
-	}
+		h.ps.resolver = &fakeResolver{build: func(b *dnsmessage.Builder) {
+			b.CNAMEResource(
+				dnsmessage.ResourceHeader{
+					Name:  dnsmessage.MustNewName("www.example.com."),
+					Type:  dnsmessage.TypeCNAME,
+					Class: dnsmessage.ClassINET,
+					TTL:   0,
+				},
+				dnsmessage.CNAMEResource{
+					CNAME: dnsmessage.MustNewName("example.com."),
+				},
+			)
+			b.AResource(
+				dnsmessage.ResourceHeader{
+					Name:  dnsmessage.MustNewName("example.com."),
+					Type:  dnsmessage.TypeA,
+					Class: dnsmessage.ClassINET,
+					TTL:   0,
+				},
+				dnsmessage.AResource{
+					A: [4]byte{192, 0, 0, 8},
+				},
+			)
+		}}
+		f := filter.NewAllowAllForTest(logger.Discard)
+		h.ps.b.setFilter(f)
 
-	w := httptest.NewRecorder()
-	h.handleDNSQuery(w, httptest.NewRequest("GET", "/dns-query?q=www.example.com.", nil))
-	if w.Code != http.StatusOK {
-		t.Errorf("unexpected status code: %v", w.Code)
-	}
-	h.ps.b.appConnector.Wait(ctx)
+		if !h.ps.b.OfferingAppConnector() {
+			t.Fatal("expecting to be offering app connector")
+		}
+		if !h.replyToDNSQueries() {
+			t.Errorf("unexpectedly deny; wanted to be a DNS server")
+		}
 
-	wantRoutes := []netip.Prefix{netip.MustParsePrefix("192.0.0.8/32")}
-	if !slices.Equal(rc.Routes(), wantRoutes) {
-		t.Errorf("got %v; want %v", rc.Routes(), wantRoutes)
+		w := httptest.NewRecorder()
+		h.handleDNSQuery(w, httptest.NewRequest("GET", "/dns-query?q=www.example.com.", nil))
+		if w.Code != http.StatusOK {
+			t.Errorf("unexpected status code: %v", w.Code)
+		}
+		h.ps.b.appConnector.Wait(ctx)
+
+		wantRoutes := []netip.Prefix{netip.MustParsePrefix("192.0.0.8/32")}
+		if !slices.Equal(rc.Routes(), wantRoutes) {
+			t.Errorf("got %v; want %v", rc.Routes(), wantRoutes)
+		}
 	}
 }
 

ipn/ipnserver/server.go

@@ -199,7 +199,7 @@ func (s *Server) serveHTTP(w http.ResponseWriter, r *http.Request) {
 	defer onDone()
 
 	if strings.HasPrefix(r.URL.Path, "/localapi/") {
-		lah := localapi.NewHandler(lb, s.logf, s.netMon, s.backendLogID)
+		lah := localapi.NewHandler(lb, s.logf, s.backendLogID)
 		lah.PermitRead, lah.PermitWrite = s.localAPIPermissions(ci)
 		lah.PermitCert = s.connCanFetchCerts(ci)
 		lah.ConnIdentity = ci

ipn/localapi/debugderp.go

@@ -140,7 +140,7 @@ func (h *Handler) serveDebugDERPRegion(w http.ResponseWriter, r *http.Request) {
 	}
 
 	checkSTUN4 := func(derpNode *tailcfg.DERPNode) {
-		u4, err := nettype.MakePacketListenerWithNetIP(netns.Listener(h.logf, h.netMon)).ListenPacket(ctx, "udp4", ":0")
+		u4, err := nettype.MakePacketListenerWithNetIP(netns.Listener(h.logf, h.b.NetMon())).ListenPacket(ctx, "udp4", ":0")
 		if err != nil {
 			st.Errors = append(st.Errors, fmt.Sprintf("Error creating IPv4 STUN listener: %v", err))
 			return
@@ -249,7 +249,7 @@ func (h *Handler) serveDebugDERPRegion(w http.ResponseWriter, r *http.Request) {
 		serverPubKeys := make(map[key.NodePublic]bool)
 		for i := range 5 {
 			func() {
-				rc := derphttp.NewRegionClient(fakePrivKey, h.logf, h.netMon, func() *tailcfg.DERPRegion {
+				rc := derphttp.NewRegionClient(fakePrivKey, h.logf, h.b.NetMon(), func() *tailcfg.DERPRegion {
 					return &tailcfg.DERPRegion{
 						RegionID:   reg.RegionID,
 						RegionCode: reg.RegionCode,

ipn/localapi/localapi.go

@@ -36,7 +36,6 @@ import (
 	"tailscale.com/clientupdate"
 	"tailscale.com/drive"
 	"tailscale.com/envknob"
-	"tailscale.com/health"
 	"tailscale.com/hostinfo"
 	"tailscale.com/ipn"
 	"tailscale.com/ipn/ipnauth"
@@ -156,8 +155,8 @@ var (
 
 // NewHandler creates a new LocalAPI HTTP handler. All parameters except netMon
 // are required (if non-nil it's used to do faster interface lookups).
-func NewHandler(b *ipnlocal.LocalBackend, logf logger.Logf, netMon *netmon.Monitor, logID logid.PublicID) *Handler {
-	return &Handler{b: b, logf: logf, netMon: netMon, backendLogID: logID, clock: tstime.StdClock{}}
+func NewHandler(b *ipnlocal.LocalBackend, logf logger.Logf, logID logid.PublicID) *Handler {
+	return &Handler{b: b, logf: logf, backendLogID: logID, clock: tstime.StdClock{}}
 }
 
 type Handler struct {
@@ -188,7 +187,6 @@ type Handler struct {
 
 	b            *ipnlocal.LocalBackend
 	logf         logger.Logf
-	netMon       *netmon.Monitor // optional; nil means interfaces will be looked up on-demand
 	backendLogID logid.PublicID
 	clock        tstime.Clock
 }
@@ -358,7 +356,7 @@ func (h *Handler) serveBugReport(w http.ResponseWriter, r *http.Request) {
 	}
 	hi, _ := json.Marshal(hostinfo.New())
 	h.logf("user bugreport hostinfo: %s", hi)
-	if err := health.OverallError(); err != nil {
+	if err := h.b.HealthTracker().OverallError(); err != nil {
 		h.logf("user bugreport health: %s", err.Error())
 	} else {
 		h.logf("user bugreport health: ok")
@@ -748,7 +746,7 @@ func (h *Handler) serveDebugPortmap(w http.ResponseWriter, r *http.Request) {
 	done := make(chan bool, 1)
 
 	var c *portmapper.Client
-	c = portmapper.NewClient(logger.WithPrefix(logf, "portmapper: "), h.netMon, debugKnobs, h.b.ControlKnobs(), func() {
+	c = portmapper.NewClient(logger.WithPrefix(logf, "portmapper: "), h.b.NetMon(), debugKnobs, h.b.ControlKnobs(), func() {
 		logf("portmapping changed.")
 		logf("have mapping: %v", c.HaveMapping())
 
@@ -1368,6 +1366,12 @@ func (h *Handler) servePrefs(w http.ResponseWriter, r *http.Request) {
 			http.Error(w, err.Error(), http.StatusBadRequest)
 			return
 		}
+		if err := h.b.MaybeClearAppConnector(mp); err != nil {
+			w.Header().Set("Content-Type", "application/json")
+			w.WriteHeader(http.StatusInternalServerError)
+			json.NewEncoder(w).Encode(resJSON{Error: err.Error()})
+			return
+		}
 		var err error
 		prefs, err = h.b.EditPrefs(mp)
 		if err != nil {

k8s-operator/api.md

@@ -330,11 +330,45 @@ Specification of the desired state of the ProxyClass resource. https://git.k8s.i
         </tr>
     </thead>
     <tbody><tr>
+        <td><b><a href="#proxyclassspecmetrics">metrics</a></b></td>
+        <td>object</td>
+        <td>
+          Configuration for proxy metrics. Metrics are currently not supported for egress proxies and for Ingress proxies that have been configured with tailscale.com/experimental-forward-cluster-traffic-via-ingress annotation.<br/>
+        </td>
+        <td>false</td>
+      </tr><tr>
         <td><b><a href="#proxyclassspecstatefulset">statefulSet</a></b></td>
         <td>object</td>
         <td>
           Configuration parameters for the proxy's StatefulSet. Tailscale Kubernetes operator deploys a StatefulSet for each of the user configured proxies (Tailscale Ingress, Tailscale Service, Connector).<br/>
         </td>
+        <td>false</td>
+      </tr></tbody>
+</table>
+
+
+### ProxyClass.spec.metrics
+<sup><sup>[↩ Parent](#proxyclassspec)</sup></sup>
+
+
+
+Configuration for proxy metrics. Metrics are currently not supported for egress proxies and for Ingress proxies that have been configured with tailscale.com/experimental-forward-cluster-traffic-via-ingress annotation.
+
+<table>
+    <thead>
+        <tr>
+            <th>Name</th>
+            <th>Type</th>
+            <th>Description</th>
+            <th>Required</th>
+        </tr>
+    </thead>
+    <tbody><tr>
+        <td><b>enable</b></td>
+        <td>boolean</td>
+        <td>
+          Setting enable to true will make the proxy serve Tailscale metrics at <pod-ip>:9001/debug/metrics. Defaults to false.<br/>
+        </td>
         <td>true</td>
       </tr></tbody>
 </table>

k8s-operator/apis/v1alpha1/types_proxyclass.go

@@ -52,7 +52,14 @@ type ProxyClassSpec struct {
 	// Configuration parameters for the proxy's StatefulSet. Tailscale
 	// Kubernetes operator deploys a StatefulSet for each of the user
 	// configured proxies (Tailscale Ingress, Tailscale Service, Connector).
+	// +optional
 	StatefulSet *StatefulSet `json:"statefulSet"`
+	// Configuration for proxy metrics. Metrics are currently not supported
+	// for egress proxies and for Ingress proxies that have been configured
+	// with tailscale.com/experimental-forward-cluster-traffic-via-ingress
+	// annotation.
+	// +optional
+	Metrics *Metrics `json:"metrics,omitempty"`
 }
 
 type StatefulSet struct {
@@ -131,6 +138,14 @@ type Pod struct {
 	// https://kubernetes.io/docs/reference/kubernetes-api/workload-resources/pod-v1/#scheduling
 	// +optional
 	Tolerations []corev1.Toleration `json:"tolerations,omitempty"`
+	// +optional
+}
+
+type Metrics struct {
+	// Setting enable to true will make the proxy serve Tailscale metrics
+	// at <pod-ip>:9001/debug/metrics.
+	// Defaults to false.
+	Enable bool `json:"enable"`
 }
 
 type Container struct {

k8s-operator/apis/v1alpha1/zz_generated.deepcopy.go

@@ -178,6 +178,21 @@ func (in *Env) DeepCopy() *Env {
 	return out
 }
 
+// DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
+func (in *Metrics) DeepCopyInto(out *Metrics) {
+	*out = *in
+}
+
+// DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new Metrics.
+func (in *Metrics) DeepCopy() *Metrics {
+	if in == nil {
+		return nil
+	}
+	out := new(Metrics)
+	in.DeepCopyInto(out)
+	return out
+}
+
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
 func (in *Pod) DeepCopyInto(out *Pod) {
 	*out = *in
@@ -313,6 +328,11 @@ func (in *ProxyClassSpec) DeepCopyInto(out *ProxyClassSpec) {
 		*out = new(StatefulSet)
 		(*in).DeepCopyInto(*out)
 	}
+	if in.Metrics != nil {
+		in, out := &in.Metrics, &out.Metrics
+		*out = new(Metrics)
+		**out = **in
+	}
 }
 
 // DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new ProxyClassSpec.

log/sockstatlog/logger.go

@@ -17,6 +17,7 @@ import (
 	"sync/atomic"
 	"time"
 
+	"tailscale.com/health"
 	"tailscale.com/logpolicy"
 	"tailscale.com/logtail"
 	"tailscale.com/logtail/filch"
@@ -93,7 +94,7 @@ func SockstatLogID(logID logid.PublicID) logid.PrivateID {
 // The returned Logger is not yet enabled, and must be shut down with Shutdown when it is no longer needed.
 // Logs will be uploaded to the log server using a new log ID derived from the provided backend logID.
 // The netMon parameter is optional; if non-nil it's used to do faster interface lookups.
-func NewLogger(logdir string, logf logger.Logf, logID logid.PublicID, netMon *netmon.Monitor) (*Logger, error) {
+func NewLogger(logdir string, logf logger.Logf, logID logid.PublicID, netMon *netmon.Monitor, health *health.Tracker) (*Logger, error) {
 	if !sockstats.IsAvailable {
 		return nil, nil
 	}
@@ -113,7 +114,7 @@ func NewLogger(logdir string, logf logger.Logf, logID logid.PublicID, netMon *ne
 	logger := &Logger{
 		logf:  logf,
 		filch: filch,
-		tr:    logpolicy.NewLogtailTransport(logtail.DefaultHost, netMon, logf),
+		tr:    logpolicy.NewLogtailTransport(logtail.DefaultHost, netMon, health, logf),
 	}
 	logger.logger = logtail.NewLogger(logtail.Config{
 		BaseURL:      logpolicy.LogURL(),

log/sockstatlog/logger_test.go

@@ -23,7 +23,7 @@ func TestResourceCleanup(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	lg, err := NewLogger(td, logger.Discard, id.Public(), nil)
+	lg, err := NewLogger(td, logger.Discard, id.Public(), nil, nil)
 	if err != nil {
 		t.Fatal(err)
 	}

logpolicy/logpolicy.go

@@ -30,6 +30,7 @@ import (
 	"golang.org/x/term"
 	"tailscale.com/atomicfile"
 	"tailscale.com/envknob"
+	"tailscale.com/health"
 	"tailscale.com/log/filelogger"
 	"tailscale.com/logtail"
 	"tailscale.com/logtail/filch"
@@ -452,13 +453,13 @@ func tryFixLogStateLocation(dir, cmdname string, logf logger.Logf) {
 // The logf parameter is optional; if non-nil, information logs (e.g. when
 // migrating state) are sent to that logger, and global changes to the log
 // package are avoided. If nil, logs will be printed using log.Printf.
-func New(collection string, netMon *netmon.Monitor, logf logger.Logf) *Policy {
-	return NewWithConfigPath(collection, "", "", netMon, logf)
+func New(collection string, netMon *netmon.Monitor, health *health.Tracker, logf logger.Logf) *Policy {
+	return NewWithConfigPath(collection, "", "", netMon, health, logf)
 }
 
 // NewWithConfigPath is identical to New, but uses the specified directory and
 // command name. If either is empty, it derives them automatically.
-func NewWithConfigPath(collection, dir, cmdName string, netMon *netmon.Monitor, logf logger.Logf) *Policy {
+func NewWithConfigPath(collection, dir, cmdName string, netMon *netmon.Monitor, health *health.Tracker, logf logger.Logf) *Policy {
 	var lflags int
 	if term.IsTerminal(2) || runtime.GOOS == "windows" {
 		lflags = 0
@@ -554,7 +555,7 @@ func NewWithConfigPath(collection, dir, cmdName string, netMon *netmon.Monitor,
 		PrivateID:    newc.PrivateID,
 		Stderr:       logWriter{console},
 		CompressLogs: true,
-		HTTPC:        &http.Client{Transport: NewLogtailTransport(logtail.DefaultHost, netMon, logf)},
+		HTTPC:        &http.Client{Transport: NewLogtailTransport(logtail.DefaultHost, netMon, health, logf)},
 	}
 	if collection == logtail.CollectionNode {
 		conf.MetricsDelta = clientmetric.EncodeLogTailMetricsDelta
@@ -569,7 +570,7 @@ func NewWithConfigPath(collection, dir, cmdName string, netMon *netmon.Monitor,
 		logf("You have enabled a non-default log target. Doing without being told to by Tailscale staff or your network administrator will make getting support difficult.")
 		conf.BaseURL = val
 		u, _ := url.Parse(val)
-		conf.HTTPC = &http.Client{Transport: NewLogtailTransport(u.Host, netMon, logf)}
+		conf.HTTPC = &http.Client{Transport: NewLogtailTransport(u.Host, netMon, health, logf)}
 	}
 
 	filchOptions := filch.Options{
@@ -741,7 +742,7 @@ func dialContext(ctx context.Context, netw, addr string, netMon *netmon.Monitor,
 //
 // The logf parameter is optional; if non-nil, logs are printed using the
 // provided function; if nil, log.Printf will be used instead.
-func NewLogtailTransport(host string, netMon *netmon.Monitor, logf logger.Logf) http.RoundTripper {
+func NewLogtailTransport(host string, netMon *netmon.Monitor, health *health.Tracker, logf logger.Logf) http.RoundTripper {
 	if testenv.InTest() {
 		return noopPretendSuccessTransport{}
 	}
@@ -782,7 +783,7 @@ func NewLogtailTransport(host string, netMon *netmon.Monitor, logf logger.Logf)
 		tr.TLSNextProto = map[string]func(authority string, c *tls.Conn) http.RoundTripper{}
 	}
 
-	tr.TLSClientConfig = tlsdial.Config(host, tr.TLSClientConfig)
+	tr.TLSClientConfig = tlsdial.Config(host, health, tr.TLSClientConfig)
 
 	return tr
 }

net/dns/direct.go

@@ -21,6 +21,7 @@ import (
 	"sync"
 	"time"
 
+	"tailscale.com/health"
 	"tailscale.com/net/dns/resolvconffile"
 	"tailscale.com/net/tsaddr"
 	"tailscale.com/types/logger"
@@ -116,8 +117,9 @@ func restartResolved() error {
 // The caller must call Down before program shutdown
 // or as cleanup if the program terminates unexpectedly.
 type directManager struct {
-	logf logger.Logf
-	fs   wholeFileFS
+	logf   logger.Logf
+	health *health.Tracker
+	fs     wholeFileFS
 	// renameBroken is set if fs.Rename to or from /etc/resolv.conf
 	// fails. This can happen in some container runtimes, where
 	// /etc/resolv.conf is bind-mounted from outside the container,
@@ -140,14 +142,15 @@ type directManager struct {
 }
 
 //lint:ignore U1000 used in manager_{freebsd,openbsd}.go
-func newDirectManager(logf logger.Logf) *directManager {
-	return newDirectManagerOnFS(logf, directFS{})
+func newDirectManager(logf logger.Logf, health *health.Tracker) *directManager {
+	return newDirectManagerOnFS(logf, health, directFS{})
 }
 
-func newDirectManagerOnFS(logf logger.Logf, fs wholeFileFS) *directManager {
+func newDirectManagerOnFS(logf logger.Logf, health *health.Tracker, fs wholeFileFS) *directManager {
 	ctx, cancel := context.WithCancel(context.Background())
 	m := &directManager{
 		logf:     logf,
+		health:   health,
 		fs:       fs,
 		ctx:      ctx,
 		ctxClose: cancel,

net/dns/direct_linux.go

@@ -78,7 +78,7 @@ func (m *directManager) checkForFileTrample() {
 		return
 	}
 	if bytes.Equal(cur, want) {
-		warnTrample.Set(nil)
+		m.health.SetWarnable(warnTrample, nil)
 		if lastWarn != nil {
 			m.mu.Lock()
 			m.lastWarnContents = nil
@@ -101,7 +101,7 @@ func (m *directManager) checkForFileTrample() {
 		show = show[:1024]
 	}
 	m.logf("trample: resolv.conf changed from what we expected. did some other program interfere? current contents: %q", show)
-	warnTrample.Set(errors.New("Linux DNS config not ideal. /etc/resolv.conf overwritten. See https://tailscale.com/s/dns-fight"))
+	m.health.SetWarnable(warnTrample, errors.New("Linux DNS config not ideal. /etc/resolv.conf overwritten. See https://tailscale.com/s/dns-fight"))
 }
 
 func (m *directManager) closeInotifyOnDone(ctx context.Context, in *gonotify.Inotify) {

net/dns/manager.go

@@ -42,7 +42,8 @@ const maxActiveQueries = 256
 
 // Manager manages system DNS settings.
 type Manager struct {
-	logf logger.Logf
+	logf   logger.Logf
+	health *health.Tracker
 
 	activeQueriesAtomic int32
 
@@ -55,7 +56,7 @@ type Manager struct {
 
 // NewManagers created a new manager from the given config.
 // The netMon parameter is optional; if non-nil it's used to do faster interface lookups.
-func NewManager(logf logger.Logf, oscfg OSConfigurator, netMon *netmon.Monitor, dialer *tsdial.Dialer, linkSel resolver.ForwardLinkSelector, knobs *controlknobs.Knobs) *Manager {
+func NewManager(logf logger.Logf, oscfg OSConfigurator, netMon *netmon.Monitor, health *health.Tracker, dialer *tsdial.Dialer, linkSel resolver.ForwardLinkSelector, knobs *controlknobs.Knobs) *Manager {
 	if dialer == nil {
 		panic("nil Dialer")
 	}
@@ -64,6 +65,7 @@ func NewManager(logf logger.Logf, oscfg OSConfigurator, netMon *netmon.Monitor,
 		logf:     logf,
 		resolver: resolver.New(logf, netMon, linkSel, dialer, knobs),
 		os:       oscfg,
+		health:   health,
 	}
 	m.ctx, m.ctxCancel = context.WithCancel(context.Background())
 	m.logf("using %T", m.os)
@@ -94,10 +96,10 @@ func (m *Manager) Set(cfg Config) error {
 		return err
 	}
 	if err := m.os.SetDNS(ocfg); err != nil {
-		health.SetDNSOSHealth(err)
+		m.health.SetDNSOSHealth(err)
 		return err
 	}
-	health.SetDNSOSHealth(nil)
+	m.health.SetDNSOSHealth(nil)
 
 	return nil
 }
@@ -248,7 +250,7 @@ func (m *Manager) compileConfig(cfg Config) (rcfg resolver.Config, ocfg OSConfig
 			// This is currently (2022-10-13) expected on certain iOS and macOS
 			// builds.
 		} else {
-			health.SetDNSOSHealth(err)
+			m.health.SetDNSOSHealth(err)
 			return resolver.Config{}, OSConfig{}, err
 		}
 	}
@@ -453,12 +455,12 @@ func (m *Manager) FlushCaches() error {
 // in case the Tailscale daemon terminated without closing the router.
 // No other state needs to be instantiated before this runs.
 func CleanUp(logf logger.Logf, interfaceName string) {
-	oscfg, err := NewOSConfigurator(logf, interfaceName)
+	oscfg, err := NewOSConfigurator(logf, nil, interfaceName)
 	if err != nil {
 		logf("creating dns cleanup: %v", err)
 		return
 	}
-	dns := NewManager(logf, oscfg, nil, &tsdial.Dialer{Logf: logf}, nil, nil)
+	dns := NewManager(logf, oscfg, nil, nil, &tsdial.Dialer{Logf: logf}, nil, nil)
 	if err := dns.Down(); err != nil {
 		logf("dns down: %v", err)
 	}

net/dns/manager_darwin.go

@@ -8,11 +8,12 @@ import (
 	"os"
 
 	"go4.org/mem"
+	"tailscale.com/health"
 	"tailscale.com/types/logger"
 	"tailscale.com/util/mak"
 )
 
-func NewOSConfigurator(logf logger.Logf, ifName string) (OSConfigurator, error) {
+func NewOSConfigurator(logf logger.Logf, health *health.Tracker, ifName string) (OSConfigurator, error) {
 	return &darwinConfigurator{logf: logf, ifName: ifName}, nil
 }
 

net/dns/manager_default.go

@@ -5,11 +5,11 @@
 
 package dns
 
-import "tailscale.com/types/logger"
+import (
+	"tailscale.com/health"
+	"tailscale.com/types/logger"
+)
 
-func NewOSConfigurator(logger.Logf, string) (OSConfigurator, error) {
-	// TODO(dmytro): on darwin, we should use a macOS-specific method such as scutil.
-	// This is currently not implemented. Editing /etc/resolv.conf does not work,
-	// as most applications use the system resolver, which disregards it.
+func NewOSConfigurator(logger.Logf, *health.Tracker, string) (OSConfigurator, error) {
 	return NewNoopManager()
 }

net/dns/manager_freebsd.go

@@ -7,13 +7,14 @@ import (
 	"fmt"
 	"os"
 
+	"tailscale.com/health"
 	"tailscale.com/types/logger"
 )
 
-func NewOSConfigurator(logf logger.Logf, _ string) (OSConfigurator, error) {
+func NewOSConfigurator(logf logger.Logf, health *health.Tracker, _ string) (OSConfigurator, error) {
 	bs, err := os.ReadFile("/etc/resolv.conf")
 	if os.IsNotExist(err) {
-		return newDirectManager(logf), nil
+		return newDirectManager(logf, health), nil
 	}
 	if err != nil {
 		return nil, fmt.Errorf("reading /etc/resolv.conf: %w", err)
@@ -23,16 +24,16 @@ func NewOSConfigurator(logf logger.Logf, _ string) (OSConfigurator, error) {
 	case "resolvconf":
 		switch resolvconfStyle() {
 		case "":
-			return newDirectManager(logf), nil
+			return newDirectManager(logf, health), nil
 		case "debian":
 			return newDebianResolvconfManager(logf)
 		case "openresolv":
 			return newOpenresolvManager(logf)
 		default:
 			logf("[unexpected] got unknown flavor of resolvconf %q, falling back to direct manager", resolvconfStyle())
-			return newDirectManager(logf), nil
+			return newDirectManager(logf, health), nil
 		}
 	default:
-		return newDirectManager(logf), nil
+		return newDirectManager(logf, health), nil
 	}
 }

net/dns/manager_linux.go

@@ -31,7 +31,7 @@ func (kv kv) String() string {
 
 var publishOnce sync.Once
 
-func NewOSConfigurator(logf logger.Logf, interfaceName string) (ret OSConfigurator, err error) {
+func NewOSConfigurator(logf logger.Logf, health *health.Tracker, interfaceName string) (ret OSConfigurator, err error) {
 	env := newOSConfigEnv{
 		fs:                directFS{},
 		dbusPing:          dbusPing,
@@ -40,7 +40,7 @@ func NewOSConfigurator(logf logger.Logf, interfaceName string) (ret OSConfigurat
 		nmVersionBetween:  nmVersionBetween,
 		resolvconfStyle:   resolvconfStyle,
 	}
-	mode, err := dnsMode(logf, env)
+	mode, err := dnsMode(logf, health, env)
 	if err != nil {
 		return nil, err
 	}
@@ -52,9 +52,9 @@ func NewOSConfigurator(logf logger.Logf, interfaceName string) (ret OSConfigurat
 	logf("dns: using %q mode", mode)
 	switch mode {
 	case "direct":
-		return newDirectManagerOnFS(logf, env.fs), nil
+		return newDirectManagerOnFS(logf, health, env.fs), nil
 	case "systemd-resolved":
-		return newResolvedManager(logf, interfaceName)
+		return newResolvedManager(logf, health, interfaceName)
 	case "network-manager":
 		return newNMManager(interfaceName)
 	case "debian-resolvconf":
@@ -63,7 +63,7 @@ func NewOSConfigurator(logf logger.Logf, interfaceName string) (ret OSConfigurat
 		return newOpenresolvManager(logf)
 	default:
 		logf("[unexpected] detected unknown DNS mode %q, using direct manager as last resort", mode)
-		return newDirectManagerOnFS(logf, env.fs), nil
+		return newDirectManagerOnFS(logf, health, env.fs), nil
 	}
 }
 
@@ -77,7 +77,7 @@ type newOSConfigEnv struct {
 	resolvconfStyle   func() string
 }
 
-func dnsMode(logf logger.Logf, env newOSConfigEnv) (ret string, err error) {
+func dnsMode(logf logger.Logf, health *health.Tracker, env newOSConfigEnv) (ret string, err error) {
 	var debug []kv
 	dbg := func(k, v string) {
 		debug = append(debug, kv{k, v})

net/dns/manager_linux_test.go

@@ -286,7 +286,7 @@ func TestLinuxDNSMode(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			var logBuf tstest.MemLogger
-			got, err := dnsMode(logBuf.Logf, tt.env)
+			got, err := dnsMode(logBuf.Logf, nil, tt.env)
 			if err != nil {
 				t.Fatal(err)
 			}

net/dns/manager_openbsd.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"os"
 
+	"tailscale.com/health"
 	"tailscale.com/types/logger"
 )
 
@@ -19,8 +20,8 @@ func (kv kv) String() string {
 	return fmt.Sprintf("%s=%s", kv.k, kv.v)
 }
 
-func NewOSConfigurator(logf logger.Logf, interfaceName string) (OSConfigurator, error) {
-	return newOSConfigurator(logf, interfaceName,
+func NewOSConfigurator(logf logger.Logf, health *health.Tracker, interfaceName string) (OSConfigurator, error) {
+	return newOSConfigurator(logf, health, interfaceName,
 		newOSConfigEnv{
 			rcIsResolvd: rcIsResolvd,
 			fs:          directFS{},
@@ -33,7 +34,7 @@ type newOSConfigEnv struct {
 	rcIsResolvd func(resolvConfContents []byte) bool
 }
 
-func newOSConfigurator(logf logger.Logf, interfaceName string, env newOSConfigEnv) (ret OSConfigurator, err error) {
+func newOSConfigurator(logf logger.Logf, health *health.Tracker, interfaceName string, env newOSConfigEnv) (ret OSConfigurator, err error) {
 	var debug []kv
 	dbg := func(k, v string) {
 		debug = append(debug, kv{k, v})
@@ -48,7 +49,7 @@ func newOSConfigurator(logf logger.Logf, interfaceName string, env newOSConfigEn
 	bs, err := env.fs.ReadFile(resolvConf)
 	if os.IsNotExist(err) {
 		dbg("rc", "missing")
-		return newDirectManager(logf), nil
+		return newDirectManager(logf, health), nil
 	}
 	if err != nil {
 		return nil, fmt.Errorf("reading /etc/resolv.conf: %w", err)
@@ -60,7 +61,7 @@ func newOSConfigurator(logf logger.Logf, interfaceName string, env newOSConfigEn
 	}
 
 	dbg("resolvd", "missing")
-	return newDirectManager(logf), nil
+	return newDirectManager(logf, health), nil
 }
 
 func rcIsResolvd(resolvConfContents []byte) bool {

net/dns/manager_tcp_test.go

@@ -87,7 +87,7 @@ func TestDNSOverTCP(t *testing.T) {
 			SearchDomains: fqdns("coffee.shop"),
 		},
 	}
-	m := NewManager(t.Logf, &f, nil, new(tsdial.Dialer), nil, nil)
+	m := NewManager(t.Logf, &f, nil, nil, new(tsdial.Dialer), nil, nil)
 	m.resolver.TestOnlySetHook(f.SetResolver)
 	m.Set(Config{
 		Hosts: hosts(
@@ -172,7 +172,7 @@ func TestDNSOverTCP_TooLarge(t *testing.T) {
 			SearchDomains: fqdns("coffee.shop"),
 		},
 	}
-	m := NewManager(log, &f, nil, new(tsdial.Dialer), nil, nil)
+	m := NewManager(log, &f, nil, nil, new(tsdial.Dialer), nil, nil)
 	m.resolver.TestOnlySetHook(f.SetResolver)
 	m.Set(Config{
 		Hosts:         hosts("andrew.ts.com.", "1.2.3.4"),

net/dns/manager_test.go

@@ -613,7 +613,7 @@ func TestManager(t *testing.T) {
 				SplitDNS:   test.split,
 				BaseConfig: test.bs,
 			}
-			m := NewManager(t.Logf, &f, nil, new(tsdial.Dialer), nil, nil)
+			m := NewManager(t.Logf, &f, nil, nil, new(tsdial.Dialer), nil, nil)
 			m.resolver.TestOnlySetHook(f.SetResolver)
 
 			if err := m.Set(test.in); err != nil {

net/dns/manager_windows.go

@@ -23,6 +23,7 @@ import (
 	"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
 	"tailscale.com/atomicfile"
 	"tailscale.com/envknob"
+	"tailscale.com/health"
 	"tailscale.com/types/logger"
 	"tailscale.com/util/dnsname"
 	"tailscale.com/util/winutil"
@@ -44,11 +45,11 @@ type windowsManager struct {
 	closing bool
 }
 
-func NewOSConfigurator(logf logger.Logf, interfaceName string) (OSConfigurator, error) {
+func NewOSConfigurator(logf logger.Logf, health *health.Tracker, interfaceName string) (OSConfigurator, error) {
 	ret := &windowsManager{
 		logf:       logf,
 		guid:       interfaceName,
-		wslManager: newWSLManager(logf),
+		wslManager: newWSLManager(logf, health),
 	}
 
 	if isWindows10OrBetter() {

net/dns/manager_windows_test.go

@@ -84,7 +84,7 @@ func TestManagerWindowsGPCopy(t *testing.T) {
 	}
 	defer delIfKey()
 
-	cfg, err := NewOSConfigurator(logf, fakeInterface.String())
+	cfg, err := NewOSConfigurator(logf, nil, fakeInterface.String())
 	if err != nil {
 		t.Fatalf("NewOSConfigurator: %v\n", err)
 	}
@@ -213,7 +213,7 @@ func runTest(t *testing.T, isLocal bool) {
 	}
 	defer delIfKey()
 
-	cfg, err := NewOSConfigurator(logf, fakeInterface.String())
+	cfg, err := NewOSConfigurator(logf, nil, fakeInterface.String())
 	if err != nil {
 		t.Fatalf("NewOSConfigurator: %v\n", err)
 	}

net/dns/resolved.go

@@ -63,13 +63,14 @@ type resolvedManager struct {
 	ctx    context.Context
 	cancel func() // terminate the context, for close
 
-	logf  logger.Logf
-	ifidx int
+	logf   logger.Logf
+	health *health.Tracker
+	ifidx  int
 
 	configCR chan changeRequest // tracks OSConfigs changes and error responses
 }
 
-func newResolvedManager(logf logger.Logf, interfaceName string) (*resolvedManager, error) {
+func newResolvedManager(logf logger.Logf, health *health.Tracker, interfaceName string) (*resolvedManager, error) {
 	iface, err := net.InterfaceByName(interfaceName)
 	if err != nil {
 		return nil, err
@@ -82,8 +83,9 @@ func newResolvedManager(logf logger.Logf, interfaceName string) (*resolvedManage
 		ctx:    ctx,
 		cancel: cancel,
 
-		logf:  logf,
-		ifidx: iface.Index,
+		logf:   logf,
+		health: health,
+		ifidx:  iface.Index,
 
 		configCR: make(chan changeRequest),
 	}
@@ -163,7 +165,7 @@ func (m *resolvedManager) run(ctx context.Context) {
 
 		// Reset backoff and SetNSOSHealth after successful on reconnect.
 		bo.BackOff(ctx, nil)
-		health.SetDNSOSHealth(nil)
+		m.health.SetDNSOSHealth(nil)
 		return nil
 	}
 
@@ -241,7 +243,7 @@ func (m *resolvedManager) run(ctx context.Context) {
 			// Set health while holding the lock, because this will
 			// graciously serialize the resync's health outcome with a
 			// concurrent SetDNS call.
-			health.SetDNSOSHealth(err)
+			m.health.SetDNSOSHealth(err)
 			if err != nil {
 				m.logf("failed to configure systemd-resolved: %v", err)
 			}

net/dns/wsl_windows.go

@@ -16,6 +16,7 @@ import (
 	"time"
 
 	"golang.org/x/sys/windows"
+	"tailscale.com/health"
 	"tailscale.com/types/logger"
 	"tailscale.com/util/winutil"
 )
@@ -54,12 +55,14 @@ func wslDistros() ([]string, error) {
 // wslManager is a DNS manager for WSL2 linux distributions.
 // It configures /etc/wsl.conf and /etc/resolv.conf.
 type wslManager struct {
-	logf logger.Logf
+	logf   logger.Logf
+	health *health.Tracker
 }
 
-func newWSLManager(logf logger.Logf) *wslManager {
+func newWSLManager(logf logger.Logf, health *health.Tracker) *wslManager {
 	m := &wslManager{
-		logf: logf,
+		logf:   logf,
+		health: health,
 	}
 	return m
 }
@@ -73,7 +76,7 @@ func (wm *wslManager) SetDNS(cfg OSConfig) error {
 	}
 	managers := make(map[string]*directManager)
 	for _, distro := range distros {
-		managers[distro] = newDirectManagerOnFS(wm.logf, wslFS{
+		managers[distro] = newDirectManagerOnFS(wm.logf, wm.health, wslFS{
 			user:   "root",
 			distro: distro,
 		})

net/dnsfallback/dnsfallback.go

@@ -28,6 +28,7 @@ import (
 
 	"tailscale.com/atomicfile"
 	"tailscale.com/envknob"
+	"tailscale.com/health"
 	"tailscale.com/net/dns/recursive"
 	"tailscale.com/net/netmon"
 	"tailscale.com/net/netns"
@@ -64,9 +65,10 @@ func MakeLookupFunc(logf logger.Logf, netMon *netmon.Monitor) func(ctx context.C
 // fallbackResolver contains the state and configuration for a DNS resolution
 // function.
 type fallbackResolver struct {
-	logf   logger.Logf
-	netMon *netmon.Monitor // or nil
-	sf     singleflight.Group[string, resolveResult]
+	logf          logger.Logf
+	netMon        *netmon.Monitor // or nil
+	healthTracker *health.Tracker // or nil
+	sf            singleflight.Group[string, resolveResult]
 
 	// for tests
 	waitForCompare bool
@@ -79,7 +81,7 @@ func (fr *fallbackResolver) Lookup(ctx context.Context, host string) ([]netip.Ad
 	// recursive resolver. (tailscale/corp#15261) In the future, we might
 	// change the default (the opt.Bool being unset) to mean enabled.
 	if disableRecursiveResolver() || !optRecursiveResolver().EqualBool(true) {
-		return lookup(ctx, host, fr.logf, fr.netMon)
+		return lookup(ctx, host, fr.logf, fr.healthTracker, fr.netMon)
 	}
 
 	addrsCh := make(chan []netip.Addr, 1)
@@ -99,7 +101,7 @@ func (fr *fallbackResolver) Lookup(ctx context.Context, host string) ([]netip.Ad
 		go fr.compareWithRecursive(ctx, addrsCh, host)
 	}
 
-	addrs, err := lookup(ctx, host, fr.logf, fr.netMon)
+	addrs, err := lookup(ctx, host, fr.logf, fr.healthTracker, fr.netMon)
 	if err != nil {
 		addrsCh <- nil
 		return nil, err
@@ -207,7 +209,7 @@ func (fr *fallbackResolver) compareWithRecursive(
 	}
 }
 
-func lookup(ctx context.Context, host string, logf logger.Logf, netMon *netmon.Monitor) ([]netip.Addr, error) {
+func lookup(ctx context.Context, host string, logf logger.Logf, ht *health.Tracker, netMon *netmon.Monitor) ([]netip.Addr, error) {
 	if ip, err := netip.ParseAddr(host); err == nil && ip.IsValid() {
 		return []netip.Addr{ip}, nil
 	}
@@ -255,7 +257,7 @@ func lookup(ctx context.Context, host string, logf logger.Logf, netMon *netmon.M
 		logf("trying bootstrapDNS(%q, %q) for %q ...", cand.dnsName, cand.ip, host)
 		ctx, cancel := context.WithTimeout(ctx, 3*time.Second)
 		defer cancel()
-		dm, err := bootstrapDNSMap(ctx, cand.dnsName, cand.ip, host, logf, netMon)
+		dm, err := bootstrapDNSMap(ctx, cand.dnsName, cand.ip, host, logf, ht, netMon)
 		if err != nil {
 			logf("bootstrapDNS(%q, %q) for %q error: %v", cand.dnsName, cand.ip, host, err)
 			continue
@@ -274,14 +276,16 @@ func lookup(ctx context.Context, host string, logf logger.Logf, netMon *netmon.M
 
 // serverName and serverIP of are, say, "derpN.tailscale.com".
 // queryName is the name being sought (e.g. "controlplane.tailscale.com"), passed as hint.
-func bootstrapDNSMap(ctx context.Context, serverName string, serverIP netip.Addr, queryName string, logf logger.Logf, netMon *netmon.Monitor) (dnsMap, error) {
+//
+// ht may be nil.
+func bootstrapDNSMap(ctx context.Context, serverName string, serverIP netip.Addr, queryName string, logf logger.Logf, ht *health.Tracker, netMon *netmon.Monitor) (dnsMap, error) {
 	dialer := netns.NewDialer(logf, netMon)
 	tr := http.DefaultTransport.(*http.Transport).Clone()
 	tr.Proxy = tshttpproxy.ProxyFromEnvironment
 	tr.DialContext = func(ctx context.Context, netw, addr string) (net.Conn, error) {
 		return dialer.DialContext(ctx, "tcp", net.JoinHostPort(serverIP.String(), "443"))
 	}
-	tr.TLSClientConfig = tlsdial.Config(serverName, tr.TLSClientConfig)
+	tr.TLSClientConfig = tlsdial.Config(serverName, ht, tr.TLSClientConfig)
 	c := &http.Client{Transport: tr}
 	req, err := http.NewRequestWithContext(ctx, "GET", "https://"+serverName+"/bootstrap-dns?q="+url.QueryEscape(queryName), nil)
 	if err != nil {

net/netutil/ip_forward.go

@@ -6,6 +6,7 @@ package netutil
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"net/netip"
 	"os"
@@ -145,8 +146,6 @@ func CheckIPForwarding(routes []netip.Prefix, state *interfaces.State) (warn, er
 // disabled or set to 'loose' mode for exit node functionality on any
 // interface.
 //
-// The state param can be nil, in which case interfaces.GetState is used.
-//
 // The routes should only be advertised routes, and should not contain the
 // node's Tailscale IPs.
 //
@@ -159,11 +158,7 @@ func CheckReversePathFiltering(state *interfaces.State) (warn []string, err erro
 	}
 
 	if state == nil {
-		var err error
-		state, err = interfaces.GetState()
-		if err != nil {
-			return nil, err
-		}
+		return nil, errors.New("no link state")
 	}
 
 	// The kernel uses the maximum value for rp_filter between the 'all'

net/netutil/netutil_test.go

@@ -8,6 +8,8 @@ import (
 	"net"
 	"runtime"
 	"testing"
+
+	"tailscale.com/net/netmon"
 )
 
 type conn struct {
@@ -70,7 +72,13 @@ func TestCheckReversePathFiltering(t *testing.T) {
 	if runtime.GOOS != "linux" {
 		t.Skipf("skipping on %s", runtime.GOOS)
 	}
-	warn, err := CheckReversePathFiltering(nil)
+	netMon, err := netmon.New(t.Logf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer netMon.Close()
+
+	warn, err := CheckReversePathFiltering(netMon.InterfaceState())
 	t.Logf("err: %v", err)
 	t.Logf("warnings: %v", warn)
 }

net/tlsdial/tlsdial.go

@@ -46,7 +46,8 @@ var tlsdialWarningPrinted sync.Map // map[string]bool
 // Config returns a tls.Config for connecting to a server.
 // If base is non-nil, it's cloned as the base config before
 // being configured and returned.
-func Config(host string, base *tls.Config) *tls.Config {
+// If ht is non-nil, it's used to report health errors.
+func Config(host string, ht *health.Tracker, base *tls.Config) *tls.Config {
 	var conf *tls.Config
 	if base == nil {
 		conf = new(tls.Config)
@@ -78,12 +79,14 @@ func Config(host string, base *tls.Config) *tls.Config {
 	conf.VerifyConnection = func(cs tls.ConnectionState) error {
 		// Perform some health checks on this certificate before we do
 		// any verification.
-		if certIsSelfSigned(cs.PeerCertificates[0]) {
-			// Self-signed certs are never valid.
-			health.SetTLSConnectionError(cs.ServerName, fmt.Errorf("certificate is self-signed"))
-		} else {
-			// Ensure we clear any error state for this ServerName.
-			health.SetTLSConnectionError(cs.ServerName, nil)
+		if ht != nil {
+			if certIsSelfSigned(cs.PeerCertificates[0]) {
+				// Self-signed certs are never valid.
+				ht.SetTLSConnectionError(cs.ServerName, fmt.Errorf("certificate is self-signed"))
+			} else {
+				// Ensure we clear any error state for this ServerName.
+				ht.SetTLSConnectionError(cs.ServerName, nil)
+			}
 		}
 
 		// First try doing x509 verification with the system's
@@ -204,7 +207,7 @@ func NewTransport() *http.Transport {
 				return nil, err
 			}
 			var d tls.Dialer
-			d.Config = Config(host, nil)
+			d.Config = Config(host, nil, nil)
 			return d.DialContext(ctx, network, addr)
 		},
 	}

net/tlsdial/tlsdial_test.go

@@ -15,6 +15,8 @@ import (
 	"runtime"
 	"sync/atomic"
 	"testing"
+
+	"tailscale.com/health"
 )
 
 func resetOnce() {
@@ -105,7 +107,8 @@ func TestFallbackRootWorks(t *testing.T) {
 		},
 		DisableKeepAlives: true, // for test cleanup ease
 	}
-	tr.TLSClientConfig = Config("tlsdial.test", tr.TLSClientConfig)
+	ht := new(health.Tracker)
+	tr.TLSClientConfig = Config("tlsdial.test", ht, tr.TLSClientConfig)
 	c := &http.Client{Transport: tr}
 
 	ctr0 := atomic.LoadInt32(&counterFallbackOK)

safeweb/http.go

@@ -70,12 +70,14 @@
 package safeweb
 
 import (
+	"cmp"
 	crand "crypto/rand"
 	"fmt"
 	"log"
 	"net"
 	"net/http"
 	"net/url"
+	"path"
 	"strings"
 
 	"github.com/gorilla/csrf"
@@ -195,6 +197,30 @@ func NewServer(config Config) (*Server, error) {
 	return s, nil
 }
 
+type handlerType int
+
+const (
+	unknownHandler handlerType = iota
+	apiHandler
+	browserHandler
+)
+
+// checkHandlerType returns either apiHandler or browserHandler, depending on
+// whether apiPattern or browserPattern is more specific (i.e. which pattern
+// contains more pathname components). If they are equally specific, it returns
+// unknownHandler.
+func checkHandlerType(apiPattern, browserPattern string) handlerType {
+	c := cmp.Compare(strings.Count(path.Clean(apiPattern), "/"), strings.Count(path.Clean(browserPattern), "/"))
+	switch {
+	case c > 0:
+		return apiHandler
+	case c < 0:
+		return browserHandler
+	default:
+		return unknownHandler
+	}
+}
+
 func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	_, bp := s.BrowserMux.Handler(r)
 	_, ap := s.APIMux.Handler(r)
@@ -206,24 +232,25 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	case bp == "" && ap == "": // neither match
 		http.NotFound(w, r)
 	case bp != "" && ap != "":
-		// Both muxes match the path. This can be because:
-		//  * one of them registers a wildcard "/" handler
-		//  * there are overlapping specific handlers
+		// Both muxes match the path. Route to the more-specific handler (as
+		// determined by the number of components in the path). If it somehow
+		// happens that both patterns are equally specific, something strange
+		// has happened; say so.
 		//
-		// If it's the former, route to the more-specific handler. If it's the
-		// latter - that's a bug so return an error to avoid mis-routing the
-		// request.
-		//
-		// TODO(awly): match the longest path instead of only special-casing
-		// "/".
-		switch {
-		case bp == "/":
+		// NOTE: checkHandlerType does not know about what the serve* handlers
+		// will do — including, possibly, redirecting to more specific patterns.
+		// If you have a less-specific pattern that redirects to something more
+		// specific, this logic will not do what you wanted.
+		handler := checkHandlerType(ap, bp)
+		switch handler {
+		case apiHandler:
 			s.serveAPI(w, r)
-		case ap == "/":
+		case browserHandler:
 			s.serveBrowser(w, r)
 		default:
-			log.Printf("conflicting mux paths in safeweb: request %q matches browser mux pattern %q and API mux patter %q; returning 500", r.URL.Path, bp, ap)
-			http.Error(w, "multiple handlers match this request", http.StatusInternalServerError)
+			s := http.StatusInternalServerError
+			log.Printf("conflicting mux paths in safeweb: request %q matches browser mux pattern %q and API mux pattern %q; returning %d", r.URL.Path, bp, ap, s)
+			http.Error(w, "multiple handlers match this request", s)
 		}
 	}
 }

safeweb/http_test.go

@@ -447,7 +447,7 @@ func TestRouting(t *testing.T) {
 			browserPatterns: []string{"/foo/"},
 			apiPatterns:     []string{"/foo/bar/"},
 			requestPath:     "/foo/bar/baz",
-			want:            "multiple handlers match this request",
+			want:            "api",
 		},
 		{
 			desc:            "no match",
@@ -488,3 +488,68 @@ func TestRouting(t *testing.T) {
 		})
 	}
 }
+
+func TestGetMoreSpecificPattern(t *testing.T) {
+	for _, tt := range []struct {
+		desc string
+		a    string
+		b    string
+		want handlerType
+	}{
+		{
+			desc: "identical",
+			a:    "/foo/bar",
+			b:    "/foo/bar",
+			want: unknownHandler,
+		},
+		{
+			desc: "identical prefix",
+			a:    "/foo/bar/",
+			b:    "/foo/bar/",
+			want: unknownHandler,
+		},
+		{
+			desc: "trailing slash",
+			a:    "/foo",
+			b:    "/foo/", // path.Clean will strip the trailing slash.
+			want: unknownHandler,
+		},
+		{
+			desc: "same prefix",
+			a:    "/foo/bar/quux",
+			b:    "/foo/bar/",
+			want: apiHandler,
+		},
+		{
+			desc: "almost same prefix, but not a path component",
+			a:    "/goat/sheep/cheese",
+			b:    "/goat/sheepcheese/",
+			want: apiHandler,
+		},
+		{
+			desc: "attempt to make less-specific pattern look more specific",
+			a:    "/goat/cat/buddy",
+			b:    "/goat/../../../../../../../cat", // path.Clean catches this foolishness
+			want: apiHandler,
+		},
+		{
+			desc: "2 names for / (1)",
+			a:    "/",
+			b:    "/../../../../../../",
+			want: unknownHandler,
+		},
+		{
+			desc: "2 names for / (2)",
+			a:    "/",
+			b:    "///////",
+			want: unknownHandler,
+		},
+	} {
+		t.Run(tt.desc, func(t *testing.T) {
+			got := checkHandlerType(tt.a, tt.b)
+			if got != tt.want {
+				t.Errorf("got %q, want %q", got, tt.want)
+			}
+		})
+	}
+}

tailcfg/tailcfg.go

@@ -2250,6 +2250,12 @@ const (
 
 	// NodeAttrLogExitFlows enables exit node destinations in network flow logs.
 	NodeAttrLogExitFlows NodeCapability = "log-exit-flows"
+
+	// NodeAttrAutoExitNode permits the automatic exit nodes feature.
+	NodeAttrAutoExitNode NodeCapability = "auto-exit-node"
+
+	// NodeAttrStoreAppCRoutes enables storing app connector routes persistently.
+	NodeAttrStoreAppCRoutes NodeCapability = "store-appc-routes"
 )
 
 // SetDNSRequest is a request to add a DNS record.

tsd/tsd.go

@@ -23,6 +23,7 @@ import (
 
 	"tailscale.com/control/controlknobs"
 	"tailscale.com/drive"
+	"tailscale.com/health"
 	"tailscale.com/ipn"
 	"tailscale.com/ipn/conffile"
 	"tailscale.com/net/dns"
@@ -63,6 +64,8 @@ type System struct {
 
 	controlKnobs controlknobs.Knobs
 	proxyMap     proxymap.Mapper
+
+	healthTracker health.Tracker
 }
 
 // NetstackImpl is the interface that *netstack.Impl implements.
@@ -134,6 +137,11 @@ func (s *System) ProxyMapper() *proxymap.Mapper {
 	return &s.proxyMap
 }
 
+// HealthTracker returns the system health tracker.
+func (s *System) HealthTracker() *health.Tracker {
+	return &s.healthTracker
+}
+
 // SubSystem represents some subsystem of the Tailscale node daemon.
 //
 // A subsystem can be set to a value, and then later retrieved. A subsystem

tsnet/tsnet.go

@@ -31,6 +31,7 @@ import (
 	"tailscale.com/client/tailscale"
 	"tailscale.com/control/controlclient"
 	"tailscale.com/envknob"
+	"tailscale.com/health"
 	"tailscale.com/hostinfo"
 	"tailscale.com/ipn"
 	"tailscale.com/ipn/ipnlocal"
@@ -233,7 +234,7 @@ func (s *Server) Loopback() (addr string, proxyCred, localAPICred string, err er
 		// out the CONNECT code from tailscaled/proxy.go that uses
 		// httputil.ReverseProxy and adding auth support.
 		go func() {
-			lah := localapi.NewHandler(s.lb, s.logf, s.netMon, s.logid)
+			lah := localapi.NewHandler(s.lb, s.logf, s.logid)
 			lah.PermitWrite = true
 			lah.PermitRead = true
 			lah.RequiredPassword = s.localAPICred
@@ -504,7 +505,8 @@ func (s *Server) start() (reterr error) {
 		return fmt.Errorf("%v is not a directory", s.rootPath)
 	}
 
-	if err := s.startLogger(&closePool); err != nil {
+	sys := new(tsd.System)
+	if err := s.startLogger(&closePool, sys.HealthTracker()); err != nil {
 		return err
 	}
 
@@ -514,14 +516,14 @@ func (s *Server) start() (reterr error) {
 	}
 	closePool.add(s.netMon)
 
-	sys := new(tsd.System)
 	s.dialer = &tsdial.Dialer{Logf: logf} // mutated below (before used)
 	eng, err := wgengine.NewUserspaceEngine(logf, wgengine.Config{
-		ListenPort:   s.Port,
-		NetMon:       s.netMon,
-		Dialer:       s.dialer,
-		SetSubsystem: sys.Set,
-		ControlKnobs: sys.ControlKnobs(),
+		ListenPort:    s.Port,
+		NetMon:        s.netMon,
+		Dialer:        s.dialer,
+		SetSubsystem:  sys.Set,
+		ControlKnobs:  sys.ControlKnobs(),
+		HealthTracker: sys.HealthTracker(),
 	})
 	if err != nil {
 		return err
@@ -606,7 +608,7 @@ func (s *Server) start() (reterr error) {
 	go s.printAuthURLLoop()
 
 	// Run the localapi handler, to allow fetching LetsEncrypt certs.
-	lah := localapi.NewHandler(lb, logf, s.netMon, s.logid)
+	lah := localapi.NewHandler(lb, logf, s.logid)
 	lah.PermitWrite = true
 	lah.PermitRead = true
 
@@ -626,7 +628,7 @@ func (s *Server) start() (reterr error) {
 	return nil
 }
 
-func (s *Server) startLogger(closePool *closeOnErrorPool) error {
+func (s *Server) startLogger(closePool *closeOnErrorPool, health *health.Tracker) error {
 	if testenv.InTest() {
 		return nil
 	}
@@ -657,7 +659,7 @@ func (s *Server) startLogger(closePool *closeOnErrorPool) error {
 		Stderr:       io.Discard, // log everything to Buffer
 		Buffer:       s.logbuffer,
 		CompressLogs: true,
-		HTTPC:        &http.Client{Transport: logpolicy.NewLogtailTransport(logtail.DefaultHost, s.netMon, s.logf)},
+		HTTPC:        &http.Client{Transport: logpolicy.NewLogtailTransport(logtail.DefaultHost, s.netMon, health, s.logf)},
 		MetricsDelta: clientmetric.EncodeLogTailMetricsDelta,
 	}
 	s.logtail = logtail.NewLogger(c, s.logf)

tstest/integration/tailscaled_deps_test_darwin.go

@@ -17,6 +17,7 @@ import (
 	_ "tailscale.com/derp/derphttp"
 	_ "tailscale.com/drive/driveimpl"
 	_ "tailscale.com/envknob"
+	_ "tailscale.com/health"
 	_ "tailscale.com/ipn"
 	_ "tailscale.com/ipn/conffile"
 	_ "tailscale.com/ipn/ipnlocal"

tstest/integration/tailscaled_deps_test_freebsd.go

@@ -17,6 +17,7 @@ import (
 	_ "tailscale.com/derp/derphttp"
 	_ "tailscale.com/drive/driveimpl"
 	_ "tailscale.com/envknob"
+	_ "tailscale.com/health"
 	_ "tailscale.com/ipn"
 	_ "tailscale.com/ipn/conffile"
 	_ "tailscale.com/ipn/ipnlocal"

tstest/integration/tailscaled_deps_test_linux.go

@@ -17,6 +17,7 @@ import (
 	_ "tailscale.com/derp/derphttp"
 	_ "tailscale.com/drive/driveimpl"
 	_ "tailscale.com/envknob"
+	_ "tailscale.com/health"
 	_ "tailscale.com/ipn"
 	_ "tailscale.com/ipn/conffile"
 	_ "tailscale.com/ipn/ipnlocal"

tstest/integration/tailscaled_deps_test_openbsd.go

@@ -17,6 +17,7 @@ import (
 	_ "tailscale.com/derp/derphttp"
 	_ "tailscale.com/drive/driveimpl"
 	_ "tailscale.com/envknob"
+	_ "tailscale.com/health"
 	_ "tailscale.com/ipn"
 	_ "tailscale.com/ipn/conffile"
 	_ "tailscale.com/ipn/ipnlocal"

tstest/integration/tailscaled_deps_test_windows.go

@@ -24,6 +24,7 @@ import (
 	_ "tailscale.com/derp/derphttp"
 	_ "tailscale.com/drive/driveimpl"
 	_ "tailscale.com/envknob"
+	_ "tailscale.com/health"
 	_ "tailscale.com/ipn"
 	_ "tailscale.com/ipn/conffile"
 	_ "tailscale.com/ipn/ipnlocal"

wgengine/magicsock/derp.go

@@ -165,7 +165,7 @@ func (c *Conn) maybeSetNearestDERP(report *netcheck.Report) (preferredDERP int)
 	if testenv.InTest() && !checkControlHealthDuringNearestDERPInTests {
 		connectedToControl = true
 	} else {
-		connectedToControl = health.GetInPollNetMap()
+		connectedToControl = c.health.GetInPollNetMap()
 	}
 	if !connectedToControl {
 		c.mu.Lock()
@@ -201,12 +201,12 @@ func (c *Conn) setNearestDERP(derpNum int) (wantDERP bool) {
 	defer c.mu.Unlock()
 	if !c.wantDerpLocked() {
 		c.myDerp = 0
-		health.SetMagicSockDERPHome(0, c.homeless)
+		c.health.SetMagicSockDERPHome(0, c.homeless)
 		return false
 	}
 	if c.homeless {
 		c.myDerp = 0
-		health.SetMagicSockDERPHome(0, c.homeless)
+		c.health.SetMagicSockDERPHome(0, c.homeless)
 		return false
 	}
 	if derpNum == c.myDerp {
@@ -217,7 +217,7 @@ func (c *Conn) setNearestDERP(derpNum int) (wantDERP bool) {
 		metricDERPHomeChange.Add(1)
 	}
 	c.myDerp = derpNum
-	health.SetMagicSockDERPHome(derpNum, c.homeless)
+	c.health.SetMagicSockDERPHome(derpNum, c.homeless)
 
 	if c.privateKey.IsZero() {
 		// No private key yet, so DERP connections won't come up anyway.
@@ -400,6 +400,7 @@ func (c *Conn) derpWriteChanOfAddr(addr netip.AddrPort, peer key.NodePublic) cha
 		}
 		return derpMap.Regions[regionID]
 	})
+	dc.HealthTracker = c.health
 
 	dc.SetCanAckPings(true)
 	dc.NotePreferred(c.myDerp == regionID)
@@ -525,8 +526,8 @@ func (c *Conn) runDerpReader(ctx context.Context, derpFakeAddr netip.AddrPort, d
 		return n
 	}
 
-	defer health.SetDERPRegionConnectedState(regionID, false)
-	defer health.SetDERPRegionHealth(regionID, "")
+	defer c.health.SetDERPRegionConnectedState(regionID, false)
+	defer c.health.SetDERPRegionHealth(regionID, "")
 
 	// peerPresent is the set of senders we know are present on this
 	// connection, based on messages we've received from the server.
@@ -538,7 +539,7 @@ func (c *Conn) runDerpReader(ctx context.Context, derpFakeAddr netip.AddrPort, d
 	for {
 		msg, connGen, err := dc.RecvDetail()
 		if err != nil {
-			health.SetDERPRegionConnectedState(regionID, false)
+			c.health.SetDERPRegionConnectedState(regionID, false)
 			// Forget that all these peers have routes.
 			for peer := range peerPresent {
 				delete(peerPresent, peer)
@@ -576,14 +577,14 @@ func (c *Conn) runDerpReader(ctx context.Context, derpFakeAddr netip.AddrPort, d
 
 		now := time.Now()
 		if lastPacketTime.IsZero() || now.Sub(lastPacketTime) > frameReceiveRecordRate {
-			health.NoteDERPRegionReceivedFrame(regionID)
+			c.health.NoteDERPRegionReceivedFrame(regionID)
 			lastPacketTime = now
 		}
 
 		switch m := msg.(type) {
 		case derp.ServerInfoMessage:
-			health.SetDERPRegionConnectedState(regionID, true)
-			health.SetDERPRegionHealth(regionID, "") // until declared otherwise
+			c.health.SetDERPRegionConnectedState(regionID, true)
+			c.health.SetDERPRegionHealth(regionID, "") // until declared otherwise
 			c.logf("magicsock: derp-%d connected; connGen=%v", regionID, connGen)
 			continue
 		case derp.ReceivedPacket:
@@ -623,7 +624,7 @@ func (c *Conn) runDerpReader(ctx context.Context, derpFakeAddr netip.AddrPort, d
 			}()
 			continue
 		case derp.HealthMessage:
-			health.SetDERPRegionHealth(regionID, m.Problem)
+			c.health.SetDERPRegionHealth(regionID, m.Problem)
 			continue
 		case derp.PeerGoneMessage:
 			switch m.Reason {
@@ -680,8 +681,10 @@ func (c *Conn) runDerpWriter(ctx context.Context, dc *derphttp.Client, ch <-chan
 }
 
 func (c *connBind) receiveDERP(buffs [][]byte, sizes []int, eps []conn.Endpoint) (int, error) {
-	health.ReceiveDERP.Enter()
-	defer health.ReceiveDERP.Exit()
+	if s := c.Conn.health.ReceiveFuncStats(health.ReceiveDERP); s != nil {
+		s.Enter()
+		defer s.Exit()
+	}
 
 	for dm := range c.derpRecvCh {
 		if c.isClosed() {

wgengine/magicsock/magicsock.go

@@ -91,6 +91,7 @@ type Conn struct {
 	testOnlyPacketListener nettype.PacketListener
 	noteRecvActivity       func(key.NodePublic) // or nil, see Options.NoteRecvActivity
 	netMon                 *netmon.Monitor      // or nil
+	health                 *health.Tracker      // or nil
 	controlKnobs           *controlknobs.Knobs  // or nil
 
 	// ================================================================
@@ -369,9 +370,13 @@ type Options struct {
 	NoteRecvActivity func(key.NodePublic)
 
 	// NetMon is the network monitor to use.
-	// With one, the portmapper won't be used.
+	// If nil, the portmapper won't be used.
 	NetMon *netmon.Monitor
 
+	// HealthTracker optionally specifies the health tracker to
+	// report errors and warnings to.
+	HealthTracker *health.Tracker
+
 	// ControlKnobs are the set of control knobs to use.
 	// If nil, they're ignored and not updated.
 	ControlKnobs *controlknobs.Knobs
@@ -463,6 +468,7 @@ func NewConn(opts Options) (*Conn, error) {
 		c.portMapper.SetGatewayLookupFunc(opts.NetMon.GatewayAndSelfIP)
 	}
 	c.netMon = opts.NetMon
+	c.health = opts.HealthTracker
 	c.onPortUpdate = opts.OnPortUpdate
 	c.getPeerByKey = opts.PeerByKeyFunc
 
@@ -666,7 +672,7 @@ func (c *Conn) updateNetInfo(ctx context.Context) (*netcheck.Report, error) {
 		// NOTE(andrew-d): I don't love that we're depending on the
 		// health package here, but I'd rather do that and not store
 		// the exact same state in two different places.
-		GetLastDERPActivity: health.GetDERPRegionReceivedTime,
+		GetLastDERPActivity: c.health.GetDERPRegionReceivedTime,
 	})
 	if err != nil {
 		return nil, err
@@ -1197,12 +1203,12 @@ func (c *Conn) putReceiveBatch(batch *receiveBatch) {
 
 // receiveIPv4 creates an IPv4 ReceiveFunc reading from c.pconn4.
 func (c *Conn) receiveIPv4() conn.ReceiveFunc {
-	return c.mkReceiveFunc(&c.pconn4, &health.ReceiveIPv4, metricRecvDataIPv4)
+	return c.mkReceiveFunc(&c.pconn4, c.health.ReceiveFuncStats(health.ReceiveIPv4), metricRecvDataIPv4)
 }
 
 // receiveIPv6 creates an IPv6 ReceiveFunc reading from c.pconn6.
 func (c *Conn) receiveIPv6() conn.ReceiveFunc {
-	return c.mkReceiveFunc(&c.pconn6, &health.ReceiveIPv6, metricRecvDataIPv6)
+	return c.mkReceiveFunc(&c.pconn6, c.health.ReceiveFuncStats(health.ReceiveIPv6), metricRecvDataIPv6)
 }
 
 // mkReceiveFunc creates a ReceiveFunc reading from ruc.
@@ -2471,7 +2477,7 @@ func (c *Conn) bindSocket(ruc *RebindingUDPConn, network string, curPortFate cur
 		}
 		ruc.setConnLocked(pconn, network, c.bind.BatchSize())
 		if network == "udp4" {
-			health.SetUDP4Unbound(false)
+			c.health.SetUDP4Unbound(false)
 		}
 		return nil
 	}
@@ -2482,7 +2488,7 @@ func (c *Conn) bindSocket(ruc *RebindingUDPConn, network string, curPortFate cur
 	// we get a link change and we can try binding again.
 	ruc.setConnLocked(newBlockForeverConn(), "", c.bind.BatchSize())
 	if network == "udp4" {
-		health.SetUDP4Unbound(true)
+		c.health.SetUDP4Unbound(true)
 	}
 	return fmt.Errorf("failed to bind any ports (tried %v)", ports)
 }

wgengine/magicsock/magicsock_test.go

@@ -3113,21 +3113,23 @@ func TestMaybeSetNearestDERP(t *testing.T) {
 	}
 	for _, tt := range testCases {
 		t.Run(tt.name, func(t *testing.T) {
+			ht := new(health.Tracker)
 			c := newConn()
 			c.logf = t.Logf
 			c.myDerp = tt.old
 			c.derpMap = derpMap
+			c.health = ht
 
 			report := &netcheck.Report{PreferredDERP: tt.reportDERP}
 
-			oldConnected := health.GetInPollNetMap()
+			oldConnected := ht.GetInPollNetMap()
 			if tt.connectedToControl != oldConnected {
 				if tt.connectedToControl {
-					health.GotStreamedMapResponse()
-					t.Cleanup(health.SetOutOfPollNetMap)
+					ht.GotStreamedMapResponse()
+					t.Cleanup(ht.SetOutOfPollNetMap)
 				} else {
-					health.SetOutOfPollNetMap()
-					t.Cleanup(health.GotStreamedMapResponse)
+					ht.SetOutOfPollNetMap()
+					t.Cleanup(ht.GotStreamedMapResponse)
 				}
 			}
 

wgengine/netlog/logger.go

@@ -16,6 +16,7 @@ import (
 	"sync"
 	"time"
 
+	"tailscale.com/health"
 	"tailscale.com/logpolicy"
 	"tailscale.com/logtail"
 	"tailscale.com/net/connstats"
@@ -92,7 +93,7 @@ var testClient *http.Client
 // The IP protocol and source port are always zero.
 // The sock is used to populated the PhysicalTraffic field in Message.
 // The netMon parameter is optional; if non-nil it's used to do faster interface lookups.
-func (nl *Logger) Startup(nodeID tailcfg.StableNodeID, nodeLogID, domainLogID logid.PrivateID, tun, sock Device, netMon *netmon.Monitor) error {
+func (nl *Logger) Startup(nodeID tailcfg.StableNodeID, nodeLogID, domainLogID logid.PrivateID, tun, sock Device, netMon *netmon.Monitor, health *health.Tracker) error {
 	nl.mu.Lock()
 	defer nl.mu.Unlock()
 	if nl.logger != nil {
@@ -101,7 +102,7 @@ func (nl *Logger) Startup(nodeID tailcfg.StableNodeID, nodeLogID, domainLogID lo
 
 	// Startup a log stream to Tailscale's logging service.
 	logf := log.Printf
-	httpc := &http.Client{Transport: logpolicy.NewLogtailTransport(logtail.DefaultHost, netMon, logf)}
+	httpc := &http.Client{Transport: logpolicy.NewLogtailTransport(logtail.DefaultHost, netMon, health, logf)}
 	if testClient != nil {
 		httpc = testClient
 	}

wgengine/router/ifconfig_windows.go

@@ -237,7 +237,7 @@ func interfaceFromLUID(luid winipcfg.LUID, flags winipcfg.GAAFlags) (*winipcfg.I
 
 var networkCategoryWarning = health.NewWarnable(health.WithMapDebugFlag("warn-network-category-unhealthy"))
 
-func configureInterface(cfg *Config, tun *tun.NativeTun) (retErr error) {
+func configureInterface(cfg *Config, tun *tun.NativeTun, health *health.Tracker) (retErr error) {
 	var mtu = tstun.DefaultTUNMTU()
 	luid := winipcfg.LUID(tun.LUID())
 	iface, err := interfaceFromLUID(luid,
@@ -268,10 +268,10 @@ func configureInterface(cfg *Config, tun *tun.NativeTun) (retErr error) {
 		for i := range tries {
 			found, err := setPrivateNetwork(luid)
 			if err != nil {
-				networkCategoryWarning.Set(fmt.Errorf("set-network-category: %w", err))
+				health.SetWarnable(networkCategoryWarning, fmt.Errorf("set-network-category: %w", err))
 				log.Printf("setPrivateNetwork(try=%d): %v", i, err)
 			} else {
-				networkCategoryWarning.Set(nil)
+				health.SetWarnable(networkCategoryWarning, nil)
 				if found {
 					if i > 0 {
 						log.Printf("setPrivateNetwork(try=%d): success", i)

wgengine/router/router.go

@@ -10,6 +10,7 @@ import (
 	"reflect"
 
 	"github.com/tailscale/wireguard-go/tun"
+	"tailscale.com/health"
 	"tailscale.com/net/netmon"
 	"tailscale.com/types/logger"
 	"tailscale.com/types/preftype"
@@ -44,9 +45,9 @@ type Router interface {
 //
 // If netMon is nil, it's not used. It's currently (2021-07-20) only
 // used on Linux in some situations.
-func New(logf logger.Logf, tundev tun.Device, netMon *netmon.Monitor) (Router, error) {
+func New(logf logger.Logf, tundev tun.Device, netMon *netmon.Monitor, health *health.Tracker) (Router, error) {
 	logf = logger.WithPrefix(logf, "router: ")
-	return newUserspaceRouter(logf, tundev, netMon)
+	return newUserspaceRouter(logf, tundev, netMon, health)
 }
 
 // CleanUp restores the system network configuration to its original state

wgengine/router/router_darwin.go

@@ -5,12 +5,13 @@ package router
 
 import (
 	"github.com/tailscale/wireguard-go/tun"
+	"tailscale.com/health"
 	"tailscale.com/net/netmon"
 	"tailscale.com/types/logger"
 )
 
-func newUserspaceRouter(logf logger.Logf, tundev tun.Device, netMon *netmon.Monitor) (Router, error) {
-	return newUserspaceBSDRouter(logf, tundev, netMon)
+func newUserspaceRouter(logf logger.Logf, tundev tun.Device, netMon *netmon.Monitor, health *health.Tracker) (Router, error) {
+	return newUserspaceBSDRouter(logf, tundev, netMon, health)
 }
 
 func cleanUp(logger.Logf, string) {

wgengine/router/router_default.go

@@ -10,11 +10,12 @@ import (
 	"runtime"
 
 	"github.com/tailscale/wireguard-go/tun"
+	"tailscale.com/health"
 	"tailscale.com/net/netmon"
 	"tailscale.com/types/logger"
 )
 
-func newUserspaceRouter(logf logger.Logf, tunDev tun.Device, netMon *netmon.Monitor) (Router, error) {
+func newUserspaceRouter(logf logger.Logf, tunDev tun.Device, netMon *netmon.Monitor, health *health.Tracker) (Router, error) {
 	return nil, fmt.Errorf("unsupported OS %q", runtime.GOOS)
 }
 

wgengine/router/router_freebsd.go

@@ -5,6 +5,7 @@ package router
 
 import (
 	"github.com/tailscale/wireguard-go/tun"
+	"tailscale.com/health"
 	"tailscale.com/net/netmon"
 	"tailscale.com/types/logger"
 )
@@ -14,8 +15,8 @@ import (
 // Work is currently underway for an in-kernel FreeBSD implementation of wireguard
 // https://svnweb.freebsd.org/base?view=revision&revision=357986
 
-func newUserspaceRouter(logf logger.Logf, tundev tun.Device, netMon *netmon.Monitor) (Router, error) {
-	return newUserspaceBSDRouter(logf, tundev, netMon)
+func newUserspaceRouter(logf logger.Logf, tundev tun.Device, netMon *netmon.Monitor, health *health.Tracker) (Router, error) {
+	return newUserspaceBSDRouter(logf, tundev, netMon, health)
 }
 
 func cleanUp(logf logger.Logf, interfaceName string) {

wgengine/router/router_linux.go

@@ -22,6 +22,7 @@ import (
 	"golang.org/x/sys/unix"
 	"golang.org/x/time/rate"
 	"tailscale.com/envknob"
+	"tailscale.com/health"
 	"tailscale.com/net/netmon"
 	"tailscale.com/types/logger"
 	"tailscale.com/types/preftype"
@@ -69,7 +70,7 @@ type linuxRouter struct {
 	magicsockPortV6 uint16
 }
 
-func newUserspaceRouter(logf logger.Logf, tunDev tun.Device, netMon *netmon.Monitor) (Router, error) {
+func newUserspaceRouter(logf logger.Logf, tunDev tun.Device, netMon *netmon.Monitor, health *health.Tracker) (Router, error) {
 	tunname, err := tunDev.Name()
 	if err != nil {
 		return nil, err

wgengine/router/router_linux_test.go

@@ -886,7 +886,7 @@ func newLinuxRootTest(t *testing.T) *linuxTest {
 	mon.Start()
 	lt.mon = mon
 
-	r, err := newUserspaceRouter(logf, lt.tun, mon)
+	r, err := newUserspaceRouter(logf, lt.tun, mon, nil)
 	if err != nil {
 		lt.Close()
 		t.Fatal(err)

wgengine/router/router_openbsd.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/tailscale/wireguard-go/tun"
 	"go4.org/netipx"
+	"tailscale.com/health"
 	"tailscale.com/net/netmon"
 	"tailscale.com/types/logger"
 	"tailscale.com/util/set"
@@ -30,7 +31,7 @@ type openbsdRouter struct {
 	routes  set.Set[netip.Prefix]
 }
 
-func newUserspaceRouter(logf logger.Logf, tundev tun.Device, netMon *netmon.Monitor) (Router, error) {
+func newUserspaceRouter(logf logger.Logf, tundev tun.Device, netMon *netmon.Monitor, health *health.Tracker) (Router, error) {
 	tunname, err := tundev.Name()
 	if err != nil {
 		return nil, err

wgengine/router/router_userspace_bsd.go

@@ -14,6 +14,7 @@ import (
 
 	"github.com/tailscale/wireguard-go/tun"
 	"go4.org/netipx"
+	"tailscale.com/health"
 	"tailscale.com/net/netmon"
 	"tailscale.com/net/tsaddr"
 	"tailscale.com/types/logger"
@@ -23,12 +24,13 @@ import (
 type userspaceBSDRouter struct {
 	logf    logger.Logf
 	netMon  *netmon.Monitor
+	health  *health.Tracker
 	tunname string
 	local   []netip.Prefix
 	routes  map[netip.Prefix]bool
 }
 
-func newUserspaceBSDRouter(logf logger.Logf, tundev tun.Device, netMon *netmon.Monitor) (Router, error) {
+func newUserspaceBSDRouter(logf logger.Logf, tundev tun.Device, netMon *netmon.Monitor, health *health.Tracker) (Router, error) {
 	tunname, err := tundev.Name()
 	if err != nil {
 		return nil, err
@@ -37,6 +39,7 @@ func newUserspaceBSDRouter(logf logger.Logf, tundev tun.Device, netMon *netmon.M
 	return &userspaceBSDRouter{
 		logf:    logf,
 		netMon:  netMon,
+		health:  health,
 		tunname: tunname,
 	}, nil
 }

wgengine/router/router_windows.go

@@ -22,6 +22,7 @@ import (
 	"github.com/tailscale/wireguard-go/tun"
 	"golang.org/x/sys/windows"
 	"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
+	"tailscale.com/health"
 	"tailscale.com/logtail/backoff"
 	"tailscale.com/net/dns"
 	"tailscale.com/net/netmon"
@@ -31,12 +32,13 @@ import (
 type winRouter struct {
 	logf                func(fmt string, args ...any)
 	netMon              *netmon.Monitor // may be nil
+	health              *health.Tracker
 	nativeTun           *tun.NativeTun
 	routeChangeCallback *winipcfg.RouteChangeCallback
 	firewall            *firewallTweaker
 }
 
-func newUserspaceRouter(logf logger.Logf, tundev tun.Device, netMon *netmon.Monitor) (Router, error) {
+func newUserspaceRouter(logf logger.Logf, tundev tun.Device, netMon *netmon.Monitor, health *health.Tracker) (Router, error) {
 	nativeTun := tundev.(*tun.NativeTun)
 	luid := winipcfg.LUID(nativeTun.LUID())
 	guid, err := luid.GUID()
@@ -47,6 +49,7 @@ func newUserspaceRouter(logf logger.Logf, tundev tun.Device, netMon *netmon.Moni
 	return &winRouter{
 		logf:      logf,
 		netMon:    netMon,
+		health:    health,
 		nativeTun: nativeTun,
 		firewall: &firewallTweaker{
 			logf:    logger.WithPrefix(logf, "firewall: "),
@@ -80,7 +83,7 @@ func (r *winRouter) Set(cfg *Config) error {
 	}
 	r.firewall.set(localAddrs, cfg.Routes, cfg.LocalRoutes)
 
-	err := configureInterface(cfg, r.nativeTun)
+	err := configureInterface(cfg, r.nativeTun, r.health)
 	if err != nil {
 		r.logf("ConfigureInterface: %v", err)
 		return err

wgengine/userspace.go

@@ -98,6 +98,7 @@ type userspaceEngine struct {
 	dns              *dns.Manager
 	magicConn        *magicsock.Conn
 	netMon           *netmon.Monitor
+	health           *health.Tracker
 	netMonOwned      bool                // whether we created netMon (and thus need to close it)
 	netMonUnregister func()              // unsubscribes from changes; used regardless of netMonOwned
 	birdClient       BIRDClient          // or nil
@@ -188,6 +189,9 @@ type Config struct {
 	// If nil, a new network monitor is created.
 	NetMon *netmon.Monitor
 
+	// HealthTracker, if non-nil, is the health tracker to use.
+	HealthTracker *health.Tracker
+
 	// Dialer is the dialer to use for outbound connections.
 	// If nil, a new Dialer is created
 	Dialer *tsdial.Dialer
@@ -310,6 +314,7 @@ func NewUserspaceEngine(logf logger.Logf, conf Config) (_ Engine, reterr error)
 		birdClient:     conf.BIRDClient,
 		controlKnobs:   conf.ControlKnobs,
 		reconfigureVPN: conf.ReconfigureVPN,
+		health:         conf.HealthTracker,
 	}
 
 	if e.birdClient != nil {
@@ -336,7 +341,7 @@ func NewUserspaceEngine(logf logger.Logf, conf Config) (_ Engine, reterr error)
 	tunName, _ := conf.Tun.Name()
 	conf.Dialer.SetTUNName(tunName)
 	conf.Dialer.SetNetMon(e.netMon)
-	e.dns = dns.NewManager(logf, conf.DNS, e.netMon, conf.Dialer, fwdDNSLinkSelector{e, tunName}, conf.ControlKnobs)
+	e.dns = dns.NewManager(logf, conf.DNS, e.netMon, e.health, conf.Dialer, fwdDNSLinkSelector{e, tunName}, conf.ControlKnobs)
 
 	// TODO: there's probably a better place for this
 	sockstats.SetNetMon(e.netMon)
@@ -372,6 +377,7 @@ func NewUserspaceEngine(logf logger.Logf, conf Config) (_ Engine, reterr error)
 		IdleFunc:         e.tundev.IdleDuration,
 		NoteRecvActivity: e.noteRecvActivity,
 		NetMon:           e.netMon,
+		HealthTracker:    e.health,
 		ControlKnobs:     conf.ControlKnobs,
 		OnPortUpdate:     onPortUpdate,
 		PeerByKeyFunc:    e.PeerByKey,
@@ -960,7 +966,7 @@ func (e *userspaceEngine) Reconfig(cfg *wgcfg.Config, routerCfg *router.Config,
 		nid := cfg.NetworkLogging.NodeID
 		tid := cfg.NetworkLogging.DomainID
 		e.logf("wgengine: Reconfig: starting up network logger (node:%s tailnet:%s)", nid.Public(), tid.Public())
-		if err := e.networkLogger.Startup(cfg.NodeID, nid, tid, e.tundev, e.magicConn, e.netMon); err != nil {
+		if err := e.networkLogger.Startup(cfg.NodeID, nid, tid, e.tundev, e.magicConn, e.netMon, e.health); err != nil {
 			e.logf("wgengine: Reconfig: error starting up network logger: %v", err)
 		}
 		e.networkLogger.ReconfigRoutes(routerCfg)
@@ -970,7 +976,7 @@ func (e *userspaceEngine) Reconfig(cfg *wgcfg.Config, routerCfg *router.Config,
 		e.logf("wgengine: Reconfig: configuring router")
 		e.networkLogger.ReconfigRoutes(routerCfg)
 		err := e.router.Set(routerCfg)
-		health.SetRouterHealth(err)
+		e.health.SetRouterHealth(err)
 		if err != nil {
 			return err
 		}
@@ -979,7 +985,7 @@ func (e *userspaceEngine) Reconfig(cfg *wgcfg.Config, routerCfg *router.Config,
 		// assigned address.
 		e.logf("wgengine: Reconfig: configuring DNS")
 		err = e.dns.Set(*dnsCfg)
-		health.SetDNSHealth(err)
+		e.health.SetDNSHealth(err)
 		if err != nil {
 			return err
 		}
@@ -1183,7 +1189,7 @@ func (e *userspaceEngine) linkChange(delta *netmon.ChangeDelta) {
 		e.logf("[v1] LinkChange: minor")
 	}
 
-	health.SetAnyInterfaceUp(up)
+	e.health.SetAnyInterfaceUp(up)
 	e.magicConn.SetNetworkUp(up)
 	if !up || changed {
 		if err := e.dns.FlushCaches(); err != nil {