[client] Fix/nil relayed address (#4153)

Fix nil pointer in Relay conn address

Meanwhile, we create a relayed net.Conn struct instance, it is possible to set the relayedURL to nil.

panic: value method github.com/netbirdio/netbird/relay/client.RelayAddr.String called using nil *RelayAddr pointer

Fix relayed URL variable protection
Protect the channel closing

relay/client/client.go

@@ -181,13 +181,17 @@ func (c *Client) Connect(ctx context.Context) error {
 		return nil
 	}
 
-	if err := c.connect(ctx); err != nil {
+	instanceURL, err := c.connect(ctx)
+	if err != nil {
 		return err
 	}
+	c.muInstanceURL.Lock()
+	c.instanceURL = instanceURL
+	c.muInstanceURL.Unlock()
 
 	c.stateSubscription = NewPeersStateSubscription(c.log, c.relayConn, c.closeConnsByPeerID)
 
-	c.log = c.log.WithField("relay", c.instanceURL.String())
+	c.log = c.log.WithField("relay", instanceURL.String())
 	c.log.Infof("relay connection established")
 
 	c.serviceIsRunning = true
@@ -229,9 +233,18 @@ func (c *Client) OpenConn(ctx context.Context, dstPeerID string) (net.Conn, erro
 
 	c.log.Infof("remote peer is available, prepare the relayed connection: %s", peerID)
 	msgChannel := make(chan Msg, 100)
-	conn := NewConn(c, peerID, msgChannel, c.instanceURL)
 
 	c.mu.Lock()
+	if !c.serviceIsRunning {
+		c.mu.Unlock()
+		return nil, fmt.Errorf("relay connection is not established")
+	}
+
+	c.muInstanceURL.Lock()
+	instanceURL := c.instanceURL
+	c.muInstanceURL.Unlock()
+	conn := NewConn(c, peerID, msgChannel, instanceURL)
+
 	_, ok = c.conns[peerID]
 	if ok {
 		c.mu.Unlock()
@@ -278,69 +291,67 @@ func (c *Client) Close() error {
 	return c.close(true)
 }
 
-func (c *Client) connect(ctx context.Context) error {
+func (c *Client) connect(ctx context.Context) (*RelayAddr, error) {
 	rd := dialer.NewRaceDial(c.log, c.connectionURL, quic.Dialer{}, ws.Dialer{})
 	conn, err := rd.Dial()
 	if err != nil {
-		return err
+		return nil, err
 	}
 	c.relayConn = conn
 
-	if err = c.handShake(ctx); err != nil {
+	instanceURL, err := c.handShake(ctx)
+	if err != nil {
 		cErr := conn.Close()
 		if cErr != nil {
 			c.log.Errorf("failed to close connection: %s", cErr)
 		}
-		return err
+		return nil, err
 	}
 
-	return nil
+	return instanceURL, nil
 }
 
-func (c *Client) handShake(ctx context.Context) error {
+func (c *Client) handShake(ctx context.Context) (*RelayAddr, error) {
 	msg, err := messages.MarshalAuthMsg(c.hashedID, c.authTokenStore.TokenBinary())
 	if err != nil {
 		c.log.Errorf("failed to marshal auth message: %s", err)
-		return err
+		return nil, err
 	}
 
 	_, err = c.relayConn.Write(msg)
 	if err != nil {
 		c.log.Errorf("failed to send auth message: %s", err)
-		return err
+		return nil, err
 	}
 	buf := make([]byte, messages.MaxHandshakeRespSize)
 	n, err := c.readWithTimeout(ctx, buf)
 	if err != nil {
 		c.log.Errorf("failed to read auth response: %s", err)
-		return err
+		return nil, err
 	}
 
 	_, err = messages.ValidateVersion(buf[:n])
 	if err != nil {
-		return fmt.Errorf("validate version: %w", err)
+		return nil, fmt.Errorf("validate version: %w", err)
 	}
 
 	msgType, err := messages.DetermineServerMessageType(buf[:n])
 	if err != nil {
 		c.log.Errorf("failed to determine message type: %s", err)
-		return err
+		return nil, err
 	}
 
 	if msgType != messages.MsgTypeAuthResponse {
 		c.log.Errorf("unexpected message type: %s", msgType)
-		return fmt.Errorf("unexpected message type")
+		return nil, fmt.Errorf("unexpected message type")
 	}
 
 	addr, err := messages.UnmarshalAuthResponse(buf[:n])
 	if err != nil {
-		return err
+		return nil, err
 	}
 
-	c.muInstanceURL.Lock()
-	c.instanceURL = &RelayAddr{addr: addr}
-	c.muInstanceURL.Unlock()
-	return nil
+	return &RelayAddr{addr: addr}, nil
 }
 
 func (c *Client) readLoop(hc *healthcheck.Receiver, relayConn net.Conn, internallyStoppedFlag *internalStopFlag) {
@@ -386,10 +397,6 @@ func (c *Client) readLoop(hc *healthcheck.Receiver, relayConn net.Conn, internal
 
 	hc.Stop()
 
-	c.muInstanceURL.Lock()
-	c.instanceURL = nil
-	c.muInstanceURL.Unlock()
-
 	c.stateSubscription.Cleanup()
 	c.wgReadLoop.Done()
 	_ = c.close(false)
@@ -578,8 +585,12 @@ func (c *Client) close(gracefullyExit bool) error {
 		c.log.Warn("relay connection was already marked as not running")
 		return nil
 	}
-
 	c.serviceIsRunning = false
+
+	c.muInstanceURL.Lock()
+	c.instanceURL = nil
+	c.muInstanceURL.Unlock()
+
 	c.log.Infof("closing all peer connections")
 	c.closeAllConns()
 	if gracefullyExit {

relay/client/manager_test.go

@@ -229,16 +229,14 @@ func TestForeginAutoClose(t *testing.T) {
 	errChan := make(chan error, 1)
 	go func() {
 		t.Log("binding server 1.")
-		err := srv1.Listen(srvCfg1)
-		if err != nil {
+		if err := srv1.Listen(srvCfg1); err != nil {
 			errChan <- err
 		}
 	}()
 
 	defer func() {
 		t.Logf("closing server 1.")
-		err := srv1.Shutdown(ctx)
-		if err != nil {
+		if err := srv1.Shutdown(ctx); err != nil {
 			t.Errorf("failed to close server: %s", err)
 		}
 		t.Logf("server 1. closed")
@@ -287,15 +285,8 @@ func TestForeginAutoClose(t *testing.T) {
 	}
 
 	t.Log("open connection to another peer")
-	conn, err := mgr.OpenConn(ctx, toURL(srvCfg2)[0], "anotherpeer")
-	if err != nil {
-		t.Fatalf("failed to bind channel: %s", err)
-	}
-
-	t.Log("close conn")
-	err = conn.Close()
-	if err != nil {
-		t.Fatalf("failed to close connection: %s", err)
+	if _, err = mgr.OpenConn(ctx, toURL(srvCfg2)[0], "anotherpeer"); err == nil {
+		t.Fatalf("should have failed to open connection to another peer")
 	}
 
 	timeout := relayCleanupInterval + keepUnusedServerTime + 1*time.Second

relay/client/peer_subscription.go

@@ -3,6 +3,8 @@ package client
 import (
 	"context"
 	"errors"
+	"fmt"
+	"sync"
 	"time"
 
 	log "github.com/sirupsen/logrus"
@@ -28,6 +30,7 @@ type PeersStateSubscription struct {
 
 	listenForOfflinePeers map[messages.PeerID]struct{}
 	waitingPeers          map[messages.PeerID]chan struct{}
+	mu                    sync.Mutex // Mutex to protect access to waitingPeers and listenForOfflinePeers
 }
 
 func NewPeersStateSubscription(log *log.Entry, relayConn relayedConnWriter, offlineCallback func(peerIDs []messages.PeerID)) *PeersStateSubscription {
@@ -43,24 +46,31 @@ func NewPeersStateSubscription(log *log.Entry, relayConn relayedConnWriter, offl
 // OnPeersOnline should be called when a notification is received that certain peers have come online.
 // It checks if any of the peers are being waited on and signals their availability.
 func (s *PeersStateSubscription) OnPeersOnline(peersID []messages.PeerID) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
 	for _, peerID := range peersID {
 		waitCh, ok := s.waitingPeers[peerID]
 		if !ok {
+			// If meanwhile the peer was unsubscribed, we don't need to signal it
 			continue
 		}
 
-		close(waitCh)
+		waitCh <- struct{}{}
 		delete(s.waitingPeers, peerID)
+		close(waitCh)
 	}
 }
 
 func (s *PeersStateSubscription) OnPeersWentOffline(peersID []messages.PeerID) {
+	s.mu.Lock()
 	relevantPeers := make([]messages.PeerID, 0, len(peersID))
 	for _, peerID := range peersID {
 		if _, ok := s.listenForOfflinePeers[peerID]; ok {
 			relevantPeers = append(relevantPeers, peerID)
 		}
 	}
+	s.mu.Unlock()
 
 	if len(relevantPeers) > 0 {
 		s.offlineCallback(relevantPeers)
@@ -68,36 +78,41 @@ func (s *PeersStateSubscription) OnPeersWentOffline(peersID []messages.PeerID) {
 }
 
 // WaitToBeOnlineAndSubscribe waits for a specific peer to come online and subscribes to its state changes.
-// todo: when we unsubscribe while this is running, this will not return with error
 func (s *PeersStateSubscription) WaitToBeOnlineAndSubscribe(ctx context.Context, peerID messages.PeerID) error {
 	// Check if already waiting for this peer
+	s.mu.Lock()
 	if _, exists := s.waitingPeers[peerID]; exists {
+		s.mu.Unlock()
 		return errors.New("already waiting for peer to come online")
 	}
 
 	// Create a channel to wait for the peer to come online
-	waitCh := make(chan struct{})
+	waitCh := make(chan struct{}, 1)
 	s.waitingPeers[peerID] = waitCh
+	s.listenForOfflinePeers[peerID] = struct{}{}
+	s.mu.Unlock()
 
-	if err := s.subscribeStateChange([]messages.PeerID{peerID}); err != nil {
+	if err := s.subscribeStateChange(peerID); err != nil {
 		s.log.Errorf("failed to subscribe to peer state: %s", err)
-		close(waitCh)
-		delete(s.waitingPeers, peerID)
-		return err
-	}
-
-	defer func() {
+		s.mu.Lock()
 		if ch, exists := s.waitingPeers[peerID]; exists && ch == waitCh {
 			close(waitCh)
 			delete(s.waitingPeers, peerID)
+			delete(s.listenForOfflinePeers, peerID)
 		}
-	}()
+		s.mu.Unlock()
+		return err
+	}
 
 	// Wait for peer to come online or context to be cancelled
 	timeoutCtx, cancel := context.WithTimeout(ctx, OpenConnectionTimeout)
 	defer cancel()
 	select {
-	case <-waitCh:
+	case _, ok := <-waitCh:
+		if !ok {
+			return fmt.Errorf("wait for peer to come online has been cancelled")
+		}
+
 		s.log.Debugf("peer %s is now online", peerID)
 		return nil
 	case <-timeoutCtx.Done():
@@ -105,6 +120,13 @@ func (s *PeersStateSubscription) WaitToBeOnlineAndSubscribe(ctx context.Context,
 		if err := s.unsubscribeStateChange([]messages.PeerID{peerID}); err != nil {
 			s.log.Errorf("failed to unsubscribe from peer state: %s", err)
 		}
+		s.mu.Lock()
+		if ch, exists := s.waitingPeers[peerID]; exists && ch == waitCh {
+			close(waitCh)
+			delete(s.waitingPeers, peerID)
+			delete(s.listenForOfflinePeers, peerID)
+		}
+		s.mu.Unlock()
 		return timeoutCtx.Err()
 	}
 }
@@ -112,6 +134,7 @@ func (s *PeersStateSubscription) WaitToBeOnlineAndSubscribe(ctx context.Context,
 func (s *PeersStateSubscription) UnsubscribeStateChange(peerIDs []messages.PeerID) error {
 	msgErr := s.unsubscribeStateChange(peerIDs)
 
+	s.mu.Lock()
 	for _, peerID := range peerIDs {
 		if wch, ok := s.waitingPeers[peerID]; ok {
 			close(wch)
@@ -120,11 +143,15 @@ func (s *PeersStateSubscription) UnsubscribeStateChange(peerIDs []messages.PeerI
 
 		delete(s.listenForOfflinePeers, peerID)
 	}
+	s.mu.Unlock()
 
 	return msgErr
 }
 
 func (s *PeersStateSubscription) Cleanup() {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
 	for _, waitCh := range s.waitingPeers {
 		close(waitCh)
 	}
@@ -133,16 +160,12 @@ func (s *PeersStateSubscription) Cleanup() {
 	s.listenForOfflinePeers = make(map[messages.PeerID]struct{})
 }
 
-func (s *PeersStateSubscription) subscribeStateChange(peerIDs []messages.PeerID) error {
-	msgs, err := messages.MarshalSubPeerStateMsg(peerIDs)
+func (s *PeersStateSubscription) subscribeStateChange(peerID messages.PeerID) error {
+	msgs, err := messages.MarshalSubPeerStateMsg([]messages.PeerID{peerID})
 	if err != nil {
 		return err
 	}
 
-	for _, peer := range peerIDs {
-		s.listenForOfflinePeers[peer] = struct{}{}
-	}
-
 	for _, msg := range msgs {
 		if _, err := s.relayConn.Write(msg); err != nil {
 			return err

relay/server/store/listener.go

@@ -8,6 +8,7 @@ import (
 )
 
 type Listener struct {
+	ctx   context.Context
 	store *Store
 
 	onlineChan                chan messages.PeerID
@@ -15,12 +16,11 @@ type Listener struct {
 	interestedPeersForOffline map[messages.PeerID]struct{}
 	interestedPeersForOnline  map[messages.PeerID]struct{}
 	mu                        sync.RWMutex
-
-	listenerCtx context.Context
 }
 
-func newListener(store *Store) *Listener {
+func newListener(ctx context.Context, store *Store) *Listener {
 	l := &Listener{
+		ctx:   ctx,
 		store: store,
 
 		onlineChan:                make(chan messages.PeerID, 244), //244 is the message size limit in the relay protocol
@@ -65,11 +65,10 @@ func (l *Listener) RemoveInterestedPeer(peerIDs []messages.PeerID) {
 	}
 }
 
-func (l *Listener) listenForEvents(ctx context.Context, onPeersComeOnline, onPeersWentOffline func([]messages.PeerID)) {
-	l.listenerCtx = ctx
+func (l *Listener) listenForEvents(onPeersComeOnline, onPeersWentOffline func([]messages.PeerID)) {
 	for {
 		select {
-		case <-ctx.Done():
+		case <-l.ctx.Done():
 			return
 		case pID := <-l.onlineChan:
 			peers := make([]messages.PeerID, 0)
@@ -102,7 +101,7 @@ func (l *Listener) peerWentOffline(peerID messages.PeerID) {
 	if _, ok := l.interestedPeersForOffline[peerID]; ok {
 		select {
 		case l.offlineChan <- peerID:
-		case <-l.listenerCtx.Done():
+		case <-l.ctx.Done():
 		}
 	}
 }
@@ -114,7 +113,7 @@ func (l *Listener) peerComeOnline(peerID messages.PeerID) {
 	if _, ok := l.interestedPeersForOnline[peerID]; ok {
 		select {
 		case l.onlineChan <- peerID:
-		case <-l.listenerCtx.Done():
+		case <-l.ctx.Done():
 		}
 		delete(l.interestedPeersForOnline, peerID)
 	}

relay/server/store/notifier.go

@@ -24,8 +24,8 @@ func NewPeerNotifier(store *Store) *PeerNotifier {
 
 func (pn *PeerNotifier) NewListener(onPeersComeOnline, onPeersWentOffline func([]messages.PeerID)) *Listener {
 	ctx, cancel := context.WithCancel(context.Background())
-	listener := newListener(pn.store)
-	go listener.listenForEvents(ctx, onPeersComeOnline, onPeersWentOffline)
+	listener := newListener(ctx, pn.store)
+	go listener.listenForEvents(onPeersComeOnline, onPeersWentOffline)
 
 	pn.listenersMutex.Lock()
 	pn.listeners[listener] = cancel