wgengine/netstack: store values from lb to avoid acquiring a lock

Signed-off-by: KevinLiang10 <37811973+KevinLiang10@users.noreply.github.com>

ipn/ipnlocal/local.go

@@ -927,6 +927,9 @@ func (b *LocalBackend) SetIPServiceMappingsForTesting(m netmap.IPServiceMappings
 	b.mu.Lock()
 	defer b.mu.Unlock()
 	b.ipVIPServiceMap = m
+	if ns, ok := b.sys.Netstack.GetOK(); ok {
+		ns.UpdateIPServiceMappings(m)
+	}
 }
 
 // setConfigLocked uses the provided config to update the backend's prefs
@@ -4509,6 +4512,12 @@ func (b *LocalBackend) onEditPrefsLocked(_ ipnauth.Actor, mp *ipn.MaskedPrefs, o
 		}
 	}
 
+	if mp.AdvertiseServicesSet {
+		if ns, ok := b.sys.Netstack.GetOK(); ok {
+			ns.UpdateActiveVIPServices(newPrefs.AdvertiseServices().AsSlice())
+		}
+	}
+
 	// This is recorded here in the EditPrefs path, not the setPrefs path on purpose.
 	// recordForEdit records metrics related to edits and changes, not the final state.
 	// If, in the future, we want to record gauge-metrics related to the state of prefs,
@@ -6238,7 +6247,12 @@ func (b *LocalBackend) setNetMapLocked(nm *netmap.NetworkMap) {
 
 	b.setTCPPortsInterceptedFromNetmapAndPrefsLocked(b.pm.CurrentPrefs())
 	if buildfeatures.HasServe {
-		b.ipVIPServiceMap = nm.GetIPVIPServiceMap()
+		ipsvMap := nm.GetIPVIPServiceMap()
+		b.ipVIPServiceMap = ipsvMap
+		if ns, ok := b.sys.Netstack.GetOK(); ok {
+			ns.UpdateIPServiceMappings(ipsvMap)
+		}
+
 	}
 
 	if !oldSelf.Equal(nm.SelfNodeOrZero()) {

tsd/tsd.go

@@ -111,6 +111,8 @@ type LocalBackend = any
 type NetstackImpl interface {
 	Start(LocalBackend) error
 	UpdateNetstackIPs(*netmap.NetworkMap)
+	UpdateIPServiceMappings(netmap.IPServiceMappings)
+	UpdateActiveVIPServices([]string)
 }
 
 // Set is a convenience method to set a subsystem value.

wgengine/netstack/netstack.go

@@ -209,6 +209,10 @@ type Impl struct {
 
 	atomicIsVIPServiceIPFunc syncs.AtomicValue[func(netip.Addr) bool]
 
+	atomicIpVIPServiceMap syncs.AtomicValue[netmap.IPServiceMappings]
+	// make this a set of strings for faster lookup
+	atomicActiveVIPServices syncs.AtomicValue[set.Set[string]]
+
 	// forwardDialFunc, if non-nil, is the net.Dialer.DialContext-style
 	// function that is used to make outgoing connections when forwarding a
 	// TCP connection to another host (e.g. in subnet router mode).
@@ -761,6 +765,22 @@ func (ns *Impl) UpdateNetstackIPs(nm *netmap.NetworkMap) {
 	}
 }
 
+// UpdateIPServiceMappings updates the IPServiceMappings when there is a change
+// in this value in localbackend. This is usually triggered from a netmap update.
+func (ns *Impl) UpdateIPServiceMappings(mappings netmap.IPServiceMappings) {
+	ns.mu.Lock()
+	defer ns.mu.Unlock()
+	ns.atomicIpVIPServiceMap.Store(mappings)
+}
+
+// UpdateActiveVIPServices updates the set of active VIP services names.
+func (ns *Impl) UpdateActiveVIPServices(activeServices []string) {
+	ns.mu.Lock()
+	defer ns.mu.Unlock()
+	activeServicesSet := set.SetOf(activeServices)
+	ns.atomicActiveVIPServices.Store(activeServicesSet)
+}
+
 func (ns *Impl) isLoopbackPort(port uint16) bool {
 	if ns.loopbackPort != nil && int(port) == *ns.loopbackPort {
 		return true
@@ -780,9 +800,7 @@ func (ns *Impl) handleLocalPackets(p *packet.Parsed, t *tstun.Wrapper, gro *gro.
 	// Determine if we care about this local packet.
 	dst := p.Dst.Addr()
 	var IPServiceMappings netmap.IPServiceMappings
-	if ns.lb != nil {
-		IPServiceMappings = ns.lb.IPServiceMappings()
-	}
+	IPServiceMappings = ns.atomicIpVIPServiceMap.Load()
 	serviceName, isVIPServiceIP := IPServiceMappings[dst]
 	switch {
 	case dst == serviceIP || dst == serviceIPv6:
@@ -804,19 +822,11 @@ func (ns *Impl) handleLocalPackets(p *packet.Parsed, t *tstun.Wrapper, gro *gro.
 		if p.IPProto != ipproto.TCP {
 			return filter.Accept, gro
 		}
-		// returns all configured VIP services, since the IPServiceMappings contains
-		// inactive service IPs when node hosts the service, we need to check the
-		// service is active or not before dropping the packet.
-		VIPServices := ns.lb.VIPServices()
-		serviceActive := false
-		for _, svc := range VIPServices {
-			// Even though control only send service IP down when there is a config
-			// for the service, we want to still check that the config still exists
-			// before passing the packet to netstack.
-			if svc.Name == serviceName {
-				serviceActive = svc.Active
-			}
-		}
+		// returns all active VIP services in a set, since the IPServiceMappings
+		// contains inactive service IPs when node hosts the service, we need to
+		// check the service is active or not before dropping the packet.
+		activeServices := ns.atomicActiveVIPServices.Load()
+		_, serviceActive := activeServices[serviceName.String()]
 		if !serviceActive {
 			return filter.Accept, gro
 		}

wgengine/netstack/netstack_test.go

@@ -126,6 +126,7 @@ func makeNetstack(tb testing.TB, config func(*Impl)) *Impl {
 		tb.Fatal(err)
 	}
 	tb.Cleanup(func() { ns.Close() })
+	sys.Set(ns)
 
 	lb, err := ipnlocal.NewLocalBackend(logf, logid.PublicID{}, sys, 0)
 	if err != nil {