[client] Fix state manager race conditions (#2890)

client/internal/dns/server.go

@@ -7,7 +7,6 @@ import (
 	"runtime"
 	"strings"
 	"sync"
-	"time"
 
 	"github.com/miekg/dns"
 	"github.com/mitchellh/hashstructure/v2"
@@ -323,13 +322,9 @@ func (s *DefaultServer) applyConfiguration(update nbdns.Config) error {
 		log.Error(err)
 	}
 
-	// persist dns state right away
-	ctx, cancel := context.WithTimeout(s.ctx, 3*time.Second)
-	defer cancel()
-
-	// don't block
 	go func() {
-		if err := s.stateManager.PersistState(ctx); err != nil {
+		// persist dns state right away
+		if err := s.stateManager.PersistState(s.ctx); err != nil {
 			log.Errorf("Failed to persist dns state: %v", err)
 		}
 	}()
@@ -537,12 +532,11 @@ func (s *DefaultServer) upstreamCallbacks(
 			l.Errorf("Failed to apply nameserver deactivation on the host: %v", err)
 		}
 
-		// persist dns state right away
-		ctx, cancel := context.WithTimeout(s.ctx, 3*time.Second)
-		defer cancel()
-		if err := s.stateManager.PersistState(ctx); err != nil {
-			l.Errorf("Failed to persist dns state: %v", err)
-		}
+		go func() {
+			if err := s.stateManager.PersistState(s.ctx); err != nil {
+				l.Errorf("Failed to persist dns state: %v", err)
+			}
+		}()
 
 		if runtime.GOOS == "android" && nsGroup.Primary && len(s.hostsDNSHolder.get()) > 0 {
 			s.addHostRootZone()

client/internal/engine.go

@@ -297,7 +297,7 @@ func (e *Engine) Stop() error {
 	if err := e.stateManager.Stop(ctx); err != nil {
 		return fmt.Errorf("failed to stop state manager: %w", err)
 	}
-	if err := e.stateManager.PersistState(ctx); err != nil {
+	if err := e.stateManager.PersistState(context.Background()); err != nil {
 		log.Errorf("failed to persist state: %v", err)
 	}
 

client/internal/routemanager/refcounter/refcounter.go

@@ -47,10 +47,9 @@ type RemoveFunc[Key, O any] func(key Key, out O) error
 type Counter[Key comparable, I, O any] struct {
 	// refCountMap keeps track of the reference Ref for keys
 	refCountMap map[Key]Ref[O]
-	refCountMu  sync.Mutex
+	mu          sync.Mutex
 	// idMap keeps track of the keys associated with an ID for removal
 	idMap  map[string][]Key
-	idMu   sync.Mutex
 	add    AddFunc[Key, I, O]
 	remove RemoveFunc[Key, O]
 }
@@ -75,10 +74,8 @@ func New[Key comparable, I, O any](add AddFunc[Key, I, O], remove RemoveFunc[Key
 func (rm *Counter[Key, I, O]) LoadData(
 	existingCounter *Counter[Key, I, O],
 ) {
-	rm.refCountMu.Lock()
-	defer rm.refCountMu.Unlock()
-	rm.idMu.Lock()
-	defer rm.idMu.Unlock()
+	rm.mu.Lock()
+	defer rm.mu.Unlock()
 
 	rm.refCountMap = existingCounter.refCountMap
 	rm.idMap = existingCounter.idMap
@@ -87,8 +84,8 @@ func (rm *Counter[Key, I, O]) LoadData(
 // Get retrieves the current reference count and associated data for a key.
 // If the key doesn't exist, it returns a zero value Ref and false.
 func (rm *Counter[Key, I, O]) Get(key Key) (Ref[O], bool) {
-	rm.refCountMu.Lock()
-	defer rm.refCountMu.Unlock()
+	rm.mu.Lock()
+	defer rm.mu.Unlock()
 
 	ref, ok := rm.refCountMap[key]
 	return ref, ok
@@ -97,9 +94,13 @@ func (rm *Counter[Key, I, O]) Get(key Key) (Ref[O], bool) {
 // Increment increments the reference count for the given key.
 // If this is the first reference to the key, the AddFunc is called.
 func (rm *Counter[Key, I, O]) Increment(key Key, in I) (Ref[O], error) {
-	rm.refCountMu.Lock()
-	defer rm.refCountMu.Unlock()
+	rm.mu.Lock()
+	defer rm.mu.Unlock()
 
+	return rm.increment(key, in)
+}
+
+func (rm *Counter[Key, I, O]) increment(key Key, in I) (Ref[O], error) {
 	ref := rm.refCountMap[key]
 	logCallerF("Increasing ref count [%d -> %d] for key %v with In [%v] Out [%v]", ref.Count, ref.Count+1, key, in, ref.Out)
 
@@ -126,10 +127,10 @@ func (rm *Counter[Key, I, O]) Increment(key Key, in I) (Ref[O], error) {
 // IncrementWithID increments the reference count for the given key and groups it under the given ID.
 // If this is the first reference to the key, the AddFunc is called.
 func (rm *Counter[Key, I, O]) IncrementWithID(id string, key Key, in I) (Ref[O], error) {
-	rm.idMu.Lock()
-	defer rm.idMu.Unlock()
+	rm.mu.Lock()
+	defer rm.mu.Unlock()
 
-	ref, err := rm.Increment(key, in)
+	ref, err := rm.increment(key, in)
 	if err != nil {
 		return ref, fmt.Errorf("with ID: %w", err)
 	}
@@ -141,9 +142,12 @@ func (rm *Counter[Key, I, O]) IncrementWithID(id string, key Key, in I) (Ref[O],
 // Decrement decrements the reference count for the given key.
 // If the reference count reaches 0, the RemoveFunc is called.
 func (rm *Counter[Key, I, O]) Decrement(key Key) (Ref[O], error) {
-	rm.refCountMu.Lock()
-	defer rm.refCountMu.Unlock()
+	rm.mu.Lock()
+	defer rm.mu.Unlock()
+	return rm.decrement(key)
+}
 
+func (rm *Counter[Key, I, O]) decrement(key Key) (Ref[O], error) {
 	ref, ok := rm.refCountMap[key]
 	if !ok {
 		logCallerF("No reference found for key %v", key)
@@ -168,12 +172,12 @@ func (rm *Counter[Key, I, O]) Decrement(key Key) (Ref[O], error) {
 // DecrementWithID decrements the reference count for all keys associated with the given ID.
 // If the reference count reaches 0, the RemoveFunc is called.
 func (rm *Counter[Key, I, O]) DecrementWithID(id string) error {
-	rm.idMu.Lock()
-	defer rm.idMu.Unlock()
+	rm.mu.Lock()
+	defer rm.mu.Unlock()
 
 	var merr *multierror.Error
 	for _, key := range rm.idMap[id] {
-		if _, err := rm.Decrement(key); err != nil {
+		if _, err := rm.decrement(key); err != nil {
 			merr = multierror.Append(merr, err)
 		}
 	}
@@ -184,10 +188,8 @@ func (rm *Counter[Key, I, O]) DecrementWithID(id string) error {
 
 // Flush removes all references and calls RemoveFunc for each key.
 func (rm *Counter[Key, I, O]) Flush() error {
-	rm.refCountMu.Lock()
-	defer rm.refCountMu.Unlock()
-	rm.idMu.Lock()
-	defer rm.idMu.Unlock()
+	rm.mu.Lock()
+	defer rm.mu.Unlock()
 
 	var merr *multierror.Error
 	for key := range rm.refCountMap {
@@ -206,21 +208,17 @@ func (rm *Counter[Key, I, O]) Flush() error {
 
 // Clear removes all references without calling RemoveFunc.
 func (rm *Counter[Key, I, O]) Clear() {
-	rm.refCountMu.Lock()
-	defer rm.refCountMu.Unlock()
-	rm.idMu.Lock()
-	defer rm.idMu.Unlock()
+	rm.mu.Lock()
+	defer rm.mu.Unlock()
 
 	clear(rm.refCountMap)
 	clear(rm.idMap)
 }
 
 // MarshalJSON implements the json.Marshaler interface for Counter.
 func (rm *Counter[Key, I, O]) MarshalJSON() ([]byte, error) {
-	rm.refCountMu.Lock()
-	defer rm.refCountMu.Unlock()
-	rm.idMu.Lock()
-	defer rm.idMu.Unlock()
+	rm.mu.Lock()
+	defer rm.mu.Unlock()
 
 	return json.Marshal(struct {
 		RefCountMap map[Key]Ref[O]   `json:"refCountMap"`

client/internal/routemanager/systemops/state.go

@@ -2,31 +2,28 @@ package systemops
 
 import (
 	"net/netip"
-	"sync"
 
 	"github.com/netbirdio/netbird/client/internal/routemanager/refcounter"
 )
 
-type ShutdownState struct {
-	Counter *ExclusionCounter `json:"counter,omitempty"`
-	mu      sync.RWMutex
-}
+type ShutdownState ExclusionCounter
 
 func (s *ShutdownState) Name() string {
 	return "route_state"
 }
 
 func (s *ShutdownState) Cleanup() error {
-	s.mu.RLock()
-	defer s.mu.RUnlock()
-
-	if s.Counter == nil {
-		return nil
-	}
-
 	sysops := NewSysOps(nil, nil)
 	sysops.refCounter = refcounter.New[netip.Prefix, struct{}, Nexthop](nil, sysops.removeFromRouteTable)
-	sysops.refCounter.LoadData(s.Counter)
+	sysops.refCounter.LoadData((*ExclusionCounter)(s))
 
 	return sysops.refCounter.Flush()
 }
+
+func (s *ShutdownState) MarshalJSON() ([]byte, error) {
+	return (*ExclusionCounter)(s).MarshalJSON()
+}
+
+func (s *ShutdownState) UnmarshalJSON(data []byte) error {
+	return (*ExclusionCounter)(s).UnmarshalJSON(data)
+}

client/internal/routemanager/systemops/systemops_generic.go

@@ -62,7 +62,7 @@ func (r *SysOps) setupRefCounter(initAddresses []net.IP, stateManager *statemana
 			return nexthop, err
 		},
 		func(prefix netip.Prefix, nexthop Nexthop) error {
-			// remove from state even if we have trouble removing it from the route table
+			// update state even if we have trouble removing it from the route table
 			// it could be already gone
 			r.updateState(stateManager)
 
@@ -75,12 +75,9 @@ func (r *SysOps) setupRefCounter(initAddresses []net.IP, stateManager *statemana
 	return r.setupHooks(initAddresses)
 }
 
+// updateState updates state on every change so it will be persisted regularly
 func (r *SysOps) updateState(stateManager *statemanager.Manager) {
-	state := getState(stateManager)
-
-	state.Counter = r.refCounter
-
-	if err := stateManager.UpdateState(state); err != nil {
+	if err := stateManager.UpdateState((*ShutdownState)(r.refCounter)); err != nil {
 		log.Errorf("failed to update state: %v", err)
 	}
 }
@@ -532,14 +529,3 @@ func isVpnRoute(addr netip.Addr, vpnRoutes []netip.Prefix, localRoutes []netip.P
 	// Return true if the longest matching prefix is from vpnRoutes
 	return isVpn, longestPrefix
 }
-
-func getState(stateManager *statemanager.Manager) *ShutdownState {
-	var shutdownState *ShutdownState
-	if state := stateManager.GetState(shutdownState); state != nil {
-		shutdownState = state.(*ShutdownState)
-	} else {
-		shutdownState = &ShutdownState{}
-	}
-
-	return shutdownState
-}

client/internal/statemanager/manager.go

@@ -74,15 +74,15 @@ func (m *Manager) Stop(ctx context.Context) error {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
-	if m.cancel != nil {
-		m.cancel()
+	if m.cancel == nil {
+		return nil
+	}
+	m.cancel()
 
-		select {
-		case <-ctx.Done():
-			return ctx.Err()
-		case <-m.done:
-			return nil
-		}
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case <-m.done:
 	}
 
 	return nil
@@ -179,14 +179,18 @@ func (m *Manager) PersistState(ctx context.Context) error {
 		return nil
 	}
 
+	bs, err := marshalWithPanicRecovery(m.states)
+	if err != nil {
+		return fmt.Errorf("marshal states: %w", err)
+	}
+
 	ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
 	defer cancel()
 
 	done := make(chan error, 1)
-
 	start := time.Now()
 	go func() {
-		done <- util.WriteJsonWithRestrictedPermission(ctx, m.filePath, m.states)
+		done <- util.WriteBytesWithRestrictedPermission(ctx, m.filePath, bs)
 	}()
 
 	select {
@@ -286,3 +290,19 @@ func (m *Manager) PerformCleanup() error {
 
 	return nberrors.FormatErrorOrNil(merr)
 }
+
+func marshalWithPanicRecovery(v any) ([]byte, error) {
+	var bs []byte
+	var err error
+
+	func() {
+		defer func() {
+			if r := recover(); r != nil {
+				err = fmt.Errorf("panic during marshal: %v", r)
+			}
+		}()
+		bs, err = json.Marshal(v)
+	}()
+
+	return bs, err
+}