[client] Fix controller re-connection (#2758)

Rethink the peer reconnection implementation

.github/workflows/golang-test-linux.yml

@@ -79,9 +79,6 @@ jobs:
       - name: check git status
         run: git --no-pager diff --exit-code
 
-      - name: Generate Iface Test bin
-        run: CGO_ENABLED=0 go test -c -o iface-testing.bin ./client/iface/
-
       - name: Generate Shared Sock Test bin
         run: CGO_ENABLED=0 go test -c -o sharedsock-testing.bin ./sharedsock
 
@@ -98,7 +95,7 @@ jobs:
         run: CGO_ENABLED=1 go test -c -o engine-testing.bin ./client/internal
 
       - name: Generate Peer Test bin
-        run: CGO_ENABLED=0 go test -c -o peer-testing.bin ./client/internal/peer/...
+        run: CGO_ENABLED=0 go test -c -o peer-testing.bin ./client/internal/peer/
 
       - run: chmod +x *testing.bin
 
@@ -106,7 +103,7 @@ jobs:
         run: docker run -t --cap-add=NET_ADMIN --privileged --rm -v $PWD:/ci -w /ci/sharedsock --entrypoint /busybox/sh gcr.io/distroless/base:debug -c /ci/sharedsock-testing.bin -test.timeout 5m -test.parallel 1
 
       - name: Run Iface tests in docker
-        run: docker run -t --cap-add=NET_ADMIN --privileged --rm -v $PWD:/ci -w /ci/iface --entrypoint /busybox/sh gcr.io/distroless/base:debug -c /ci/iface-testing.bin -test.timeout 5m -test.parallel 1
+        run: docker run -t --cap-add=NET_ADMIN --privileged --rm -v $PWD:/netbird -v /tmp/cache:/tmp/cache -v /tmp/modcache:/tmp/modcache -w /netbird -e GOCACHE=/tmp/cache -e GOMODCACHE=/tmp/modcache -e CGO_ENABLED=0 golang:1.23-alpine go test  -test.timeout 5m -test.parallel 1 ./client/iface/...
 
       - name: Run RouteManager tests in docker
         run: docker run -t --cap-add=NET_ADMIN --privileged --rm -v $PWD:/ci -w /ci/client/internal/routemanager --entrypoint /busybox/sh gcr.io/distroless/base:debug -c /ci/routemanager-testing.bin  -test.timeout 5m -test.parallel 1

client/iface/bind/ice_bind.go

@@ -143,7 +143,6 @@ func (b *ICEBind) Send(bufs [][]byte, ep wgConn.Endpoint) error {
 	conn, ok := b.endpoints[ep.DstIP()]
 	b.endpointsMu.Unlock()
 	if !ok {
-		log.Infof("failed to find endpoint for %s", ep.DstIP())
 		return b.StdNetBind.Send(bufs, ep)
 	}
 

client/iface/wgproxy/ebpf/portlookup.go

@@ -5,9 +5,9 @@ import (
 	"net"
 )
 
-const (
+var (
 	portRangeStart = 3128
-	portRangeEnd   = 3228
+	portRangeEnd   = portRangeStart + 100
 )
 
 type portLookup struct {

client/iface/wgproxy/ebpf/portlookup_test.go

@@ -17,6 +17,9 @@ func Test_portLookup_searchFreePort(t *testing.T) {
 func Test_portLookup_on_allocated(t *testing.T) {
 	pl := portLookup{}
 
+	portRangeStart = 4128
+	portRangeEnd = portRangeStart + 100
+
 	allocatedPort, err := allocatePort(portRangeStart)
 	if err != nil {
 		t.Fatal(err)

client/iface/wgproxy/factory_kernel.go

@@ -22,9 +22,11 @@ func NewKernelFactory(wgPort int) *KernelFactory {
 
 	ebpfProxy := ebpf.NewWGEBPFProxy(wgPort)
 	if err := ebpfProxy.Listen(); err != nil {
+		log.Infof("WireGuard Proxy Factory will produce UDP proxy")
 		log.Warnf("failed to initialize ebpf proxy, fallback to user space proxy: %s", err)
 		return f
 	}
+	log.Infof("WireGuard Proxy Factory will produce eBPF proxy")
 	f.ebpfProxy = ebpfProxy
 	return f
 }

client/iface/wgproxy/factory_kernel_freebsd.go

@@ -1,6 +1,8 @@
 package wgproxy
 
 import (
+	log "github.com/sirupsen/logrus"
+
 	udpProxy "github.com/netbirdio/netbird/client/iface/wgproxy/udp"
 )
 
@@ -10,6 +12,7 @@ type KernelFactory struct {
 }
 
 func NewKernelFactory(wgPort int) *KernelFactory {
+	log.Infof("WireGuard Proxy Factory will produce UDP proxy")
 	f := &KernelFactory{
 		wgPort: wgPort,
 	}

client/iface/wgproxy/factory_usp.go

@@ -1,6 +1,8 @@
 package wgproxy
 
 import (
+	log "github.com/sirupsen/logrus"
+
 	"github.com/netbirdio/netbird/client/iface/bind"
 	proxyBind "github.com/netbirdio/netbird/client/iface/wgproxy/bind"
 )
@@ -10,6 +12,7 @@ type USPFactory struct {
 }
 
 func NewUSPFactory(iceBind *bind.ICEBind) *USPFactory {
+	log.Infof("WireGuard Proxy Factory will produce bind proxy")
 	f := &USPFactory{
 		bind: iceBind,
 	}

client/iface/wgproxy/udp/proxy.go

@@ -2,14 +2,16 @@ package udp
 
 import (
 	"context"
+	"errors"
 	"fmt"
+	"io"
 	"net"
 	"sync"
 
 	"github.com/hashicorp/go-multierror"
 	log "github.com/sirupsen/logrus"
 
-	"github.com/netbirdio/netbird/client/errors"
+	cerrors "github.com/netbirdio/netbird/client/errors"
 )
 
 // WGUDPProxy proxies
@@ -121,7 +123,7 @@ func (p *WGUDPProxy) close() error {
 	if err := p.localConn.Close(); err != nil {
 		result = multierror.Append(result, fmt.Errorf("local conn: %s", err))
 	}
-	return errors.FormatErrorOrNil(result)
+	return cerrors.FormatErrorOrNil(result)
 }
 
 // proxyToRemote proxies from Wireguard to the RemoteKey
@@ -160,18 +162,16 @@ func (p *WGUDPProxy) proxyToRemote(ctx context.Context) {
 func (p *WGUDPProxy) proxyToLocal(ctx context.Context) {
 	defer func() {
 		if err := p.close(); err != nil {
+			if !errors.Is(err, io.EOF) {
 				log.Warnf("error in proxy to local loop: %s", err)
 			}
+		}
 	}()
 
 	buf := make([]byte, 1500)
 	for {
-		n, err := p.remoteConn.Read(buf)
+		n, err := p.remoteConnRead(ctx, buf)
 		if err != nil {
-			if ctx.Err() != nil {
-				return
-			}
-			log.Errorf("failed to read from remote conn: %s, %s", p.remoteConn.RemoteAddr(), err)
 			return
 		}
 
@@ -193,3 +193,15 @@ func (p *WGUDPProxy) proxyToLocal(ctx context.Context) {
 		}
 	}
 }
+
+func (p *WGUDPProxy) remoteConnRead(ctx context.Context, buf []byte) (n int, err error) {
+	n, err = p.remoteConn.Read(buf)
+	if err != nil {
+		if ctx.Err() != nil {
+			return
+		}
+		log.Errorf("failed to read from remote conn: %s, %s", p.remoteConn.LocalAddr(), err)
+		return
+	}
+	return
+}

client/internal/engine.go

@@ -30,6 +30,8 @@ import (
 	"github.com/netbirdio/netbird/client/internal/dns"
 	"github.com/netbirdio/netbird/client/internal/networkmonitor"
 	"github.com/netbirdio/netbird/client/internal/peer"
+	"github.com/netbirdio/netbird/client/internal/peer/guard"
+	icemaker "github.com/netbirdio/netbird/client/internal/peer/ice"
 	"github.com/netbirdio/netbird/client/internal/relay"
 	"github.com/netbirdio/netbird/client/internal/rosenpass"
 	"github.com/netbirdio/netbird/client/internal/routemanager"
@@ -168,6 +170,7 @@ type Engine struct {
 
 	relayManager *relayClient.Manager
 	stateManager *statemanager.Manager
+	srWatcher *guard.SRWatcher
 }
 
 // Peer is an instance of the Connection Peer
@@ -263,6 +266,10 @@ func (e *Engine) Stop() error {
 		e.routeManager.Stop(e.stateManager)
 	}
 
+	if e.srWatcher != nil {
+		e.srWatcher.Close()
+	}
+
 	err := e.removeAllPeers()
 	if err != nil {
 		return fmt.Errorf("failed to remove all peers: %s", err)
@@ -389,6 +396,18 @@ func (e *Engine) Start() error {
 		return fmt.Errorf("initialize dns server: %w", err)
 	}
 
+	iceCfg := icemaker.Config{
+		StunTurn:             &e.stunTurn,
+		InterfaceBlackList:   e.config.IFaceBlackList,
+		DisableIPv6Discovery: e.config.DisableIPv6Discovery,
+		UDPMux:               e.udpMux.UDPMuxDefault,
+		UDPMuxSrflx:          e.udpMux,
+		NATExternalIPs:       e.parseNATExternalIPMappings(),
+	}
+
+	e.srWatcher = guard.NewSRWatcher(e.signal, e.relayManager, e.mobileDep.IFaceDiscover, iceCfg)
+	e.srWatcher.Start()
+
 	e.receiveSignalEvents()
 	e.receiveManagementEvents()
 	e.receiveProbeEvents()
@@ -971,7 +990,7 @@ func (e *Engine) createPeerConn(pubKey string, allowedIPs string) (*peer.Conn, e
 		LocalWgPort:     e.config.WgPort,
 		RosenpassPubKey: e.getRosenpassPubKey(),
 		RosenpassAddr:   e.getRosenpassAddr(),
-		ICEConfig: peer.ICEConfig{
+		ICEConfig: icemaker.Config{
 			StunTurn:             &e.stunTurn,
 			InterfaceBlackList:   e.config.IFaceBlackList,
 			DisableIPv6Discovery: e.config.DisableIPv6Discovery,
@@ -981,7 +1000,7 @@ func (e *Engine) createPeerConn(pubKey string, allowedIPs string) (*peer.Conn, e
 		},
 	}
 
-	peerConn, err := peer.NewConn(e.ctx, config, e.statusRecorder, e.signaler, e.mobileDep.IFaceDiscover, e.relayManager)
+	peerConn, err := peer.NewConn(e.ctx, config, e.statusRecorder, e.signaler, e.mobileDep.IFaceDiscover, e.relayManager, e.srWatcher)
 	if err != nil {
 		return nil, err
 	}

client/internal/engine_test.go

@@ -29,6 +29,8 @@ import (
 	"github.com/netbirdio/netbird/client/iface/device"
 	"github.com/netbirdio/netbird/client/internal/dns"
 	"github.com/netbirdio/netbird/client/internal/peer"
+	"github.com/netbirdio/netbird/client/internal/peer/guard"
+	icemaker "github.com/netbirdio/netbird/client/internal/peer/ice"
 	"github.com/netbirdio/netbird/client/internal/routemanager"
 	"github.com/netbirdio/netbird/client/ssh"
 	"github.com/netbirdio/netbird/client/system"
@@ -258,6 +260,7 @@ func TestEngine_UpdateNetworkMap(t *testing.T) {
 	}
 	engine.udpMux = bind.NewUniversalUDPMuxDefault(bind.UniversalUDPMuxParams{UDPConn: conn})
 	engine.ctx = ctx
+	engine.srWatcher = guard.NewSRWatcher(nil, nil, nil, icemaker.Config{})
 
 	type testCase struct {
 		name       string

client/internal/peer/conn.go

@@ -10,7 +10,6 @@ import (
 	"sync"
 	"time"
 
-	"github.com/cenkalti/backoff/v4"
 	"github.com/pion/ice/v3"
 	log "github.com/sirupsen/logrus"
 	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
@@ -18,6 +17,8 @@ import (
 	"github.com/netbirdio/netbird/client/iface"
 	"github.com/netbirdio/netbird/client/iface/configurer"
 	"github.com/netbirdio/netbird/client/iface/wgproxy"
+	"github.com/netbirdio/netbird/client/internal/peer/guard"
+	icemaker "github.com/netbirdio/netbird/client/internal/peer/ice"
 	"github.com/netbirdio/netbird/client/internal/stdnet"
 	relayClient "github.com/netbirdio/netbird/relay/client"
 	"github.com/netbirdio/netbird/route"
@@ -32,8 +33,6 @@ const (
 	connPriorityRelay   ConnPriority = 1
 	connPriorityICETurn ConnPriority = 1
 	connPriorityICEP2P  ConnPriority = 2
-
-	reconnectMaxElapsedTime = 30 * time.Minute
 )
 
 type WgConfig struct {
@@ -63,7 +62,7 @@ type ConnConfig struct {
 	RosenpassAddr string
 
 	// ICEConfig ICE protocol configuration
-	ICEConfig ICEConfig
+	ICEConfig icemaker.Config
 }
 
 type WorkerCallbacks struct {
@@ -106,16 +105,12 @@ type Conn struct {
 	wgProxyICE   wgproxy.Proxy
 	wgProxyRelay wgproxy.Proxy
 
-	// for reconnection operations
+	guard *guard.Guard
-	iCEDisconnected   chan bool
-	relayDisconnected chan bool
-	connMonitor       *ConnMonitor
-	reconnectCh       <-chan struct{}
 }
 
 // NewConn creates a new not opened Conn to the remote peer.
 // To establish a connection run Conn.Open
-func NewConn(engineCtx context.Context, config ConnConfig, statusRecorder *Status, signaler *Signaler, iFaceDiscover stdnet.ExternalIFaceDiscover, relayManager *relayClient.Manager) (*Conn, error) {
+func NewConn(engineCtx context.Context, config ConnConfig, statusRecorder *Status, signaler *Signaler, iFaceDiscover stdnet.ExternalIFaceDiscover, relayManager *relayClient.Manager, srWatcher *guard.SRWatcher) (*Conn, error) {
 	allowedIP, allowedNet, err := net.ParseCIDR(config.WgConfig.AllowedIps)
 	if err != nil {
 		log.Errorf("failed to parse allowedIPS: %v", err)
@@ -137,18 +132,8 @@ func NewConn(engineCtx context.Context, config ConnConfig, statusRecorder *Statu
 		allowedNet:     allowedNet.String(),
 		statusRelay:    NewAtomicConnStatus(),
 		statusICE:      NewAtomicConnStatus(),
-		iCEDisconnected:   make(chan bool, 1),
-		relayDisconnected: make(chan bool, 1),
 	}
 
-	conn.connMonitor, conn.reconnectCh = NewConnMonitor(
-		signaler,
-		iFaceDiscover,
-		config,
-		conn.relayDisconnected,
-		conn.iCEDisconnected,
-	)
-
 	rFns := WorkerRelayCallbacks{
 		OnConnReady:    conn.relayConnectionIsReady,
 		OnDisconnected: conn.onWorkerRelayStateDisconnected,
@@ -159,7 +144,8 @@ func NewConn(engineCtx context.Context, config ConnConfig, statusRecorder *Statu
 		OnStatusChanged: conn.onWorkerICEStateDisconnected,
 	}
 
-	conn.workerRelay = NewWorkerRelay(connLog, config, relayManager, rFns)
+	ctrl := isController(config)
+	conn.workerRelay = NewWorkerRelay(connLog, ctrl, config, relayManager, rFns)
 
 	relayIsSupportedLocally := conn.workerRelay.RelayIsSupportedLocally()
 	conn.workerICE, err = NewWorkerICE(ctx, connLog, config, signaler, iFaceDiscover, statusRecorder, relayIsSupportedLocally, wFns)
@@ -174,6 +160,8 @@ func NewConn(engineCtx context.Context, config ConnConfig, statusRecorder *Statu
 		conn.handshaker.AddOnNewOfferListener(conn.workerICE.OnNewOffer)
 	}
 
+	conn.guard = guard.NewGuard(connLog, ctrl, conn.isConnectedOnAllWay, config.Timeout, srWatcher)
+
 	go conn.handshaker.Listen()
 
 	return conn, nil
@@ -184,6 +172,7 @@ func NewConn(engineCtx context.Context, config ConnConfig, statusRecorder *Statu
 // be used.
 func (conn *Conn) Open() {
 	conn.log.Debugf("open connection to peer")
+
 	conn.mu.Lock()
 	defer conn.mu.Unlock()
 	conn.opened = true
@@ -200,24 +189,19 @@ func (conn *Conn) Open() {
 		conn.log.Warnf("error while updating the state err: %v", err)
 	}
 
-	go conn.startHandshakeAndReconnect()
+	go conn.startHandshakeAndReconnect(conn.ctx)
 }
 
-func (conn *Conn) startHandshakeAndReconnect() {
+func (conn *Conn) startHandshakeAndReconnect(ctx context.Context) {
-	conn.waitInitialRandomSleepTime()
+	conn.waitInitialRandomSleepTime(ctx)
 
 	err := conn.handshaker.sendOffer()
 	if err != nil {
 		conn.log.Errorf("failed to send initial offer: %v", err)
 	}
 
-	go conn.connMonitor.Start(conn.ctx)
+	go conn.guard.Start(ctx)
-
+	go conn.listenGuardEvent(ctx)
-	if conn.workerRelay.IsController() {
-		conn.reconnectLoopWithRetry()
-	} else {
-		conn.reconnectLoopForOnDisconnectedEvent()
-	}
 }
 
 // Close closes this peer Conn issuing a close event to the Conn closeCh
@@ -316,104 +300,6 @@ func (conn *Conn) GetKey() string {
 	return conn.config.Key
 }
 
-func (conn *Conn) reconnectLoopWithRetry() {
-	// Give chance to the peer to establish the initial connection.
-	// With it, we can decrease to send necessary offer
-	select {
-	case <-conn.ctx.Done():
-		return
-	case <-time.After(3 * time.Second):
-	}
-
-	ticker := conn.prepareExponentTicker()
-	defer ticker.Stop()
-	time.Sleep(1 * time.Second)
-
-	for {
-		select {
-		case t := <-ticker.C:
-			if t.IsZero() {
-				// in case if the ticker has been canceled by context then avoid the temporary loop
-				return
-			}
-
-			if conn.workerRelay.IsRelayConnectionSupportedWithPeer() {
-				if conn.statusRelay.Get() == StatusDisconnected || conn.statusICE.Get() == StatusDisconnected {
-					conn.log.Tracef("connectivity guard timedout, relay state: %s, ice state: %s", conn.statusRelay, conn.statusICE)
-				}
-			} else {
-				if conn.statusICE.Get() == StatusDisconnected {
-					conn.log.Tracef("connectivity guard timedout, ice state: %s", conn.statusICE)
-				}
-			}
-
-			// checks if there is peer connection is established via relay or ice
-			if conn.isConnected() {
-				continue
-			}
-
-			err := conn.handshaker.sendOffer()
-			if err != nil {
-				conn.log.Errorf("failed to do handshake: %v", err)
-			}
-
-		case <-conn.reconnectCh:
-			ticker.Stop()
-			ticker = conn.prepareExponentTicker()
-
-		case <-conn.ctx.Done():
-			conn.log.Debugf("context is done, stop reconnect loop")
-			return
-		}
-	}
-}
-
-func (conn *Conn) prepareExponentTicker() *backoff.Ticker {
-	bo := backoff.WithContext(&backoff.ExponentialBackOff{
-		InitialInterval:     800 * time.Millisecond,
-		RandomizationFactor: 0.1,
-		Multiplier:          2,
-		MaxInterval:         conn.config.Timeout,
-		MaxElapsedTime:      reconnectMaxElapsedTime,
-		Stop:                backoff.Stop,
-		Clock:               backoff.SystemClock,
-	}, conn.ctx)
-
-	ticker := backoff.NewTicker(bo)
-	<-ticker.C // consume the initial tick what is happening right after the ticker has been created
-
-	return ticker
-}
-
-// reconnectLoopForOnDisconnectedEvent is used when the peer is not a controller and it should reconnect to the peer
-// when the connection is lost. It will try to establish a connection only once time if before the connection was established
-// It track separately the ice and relay connection status. Just because a lover priority connection reestablished it does not
-// mean that to switch to it. We always force to use the higher priority connection.
-func (conn *Conn) reconnectLoopForOnDisconnectedEvent() {
-	for {
-		select {
-		case changed := <-conn.relayDisconnected:
-			if !changed {
-				continue
-			}
-			conn.log.Debugf("Relay state changed, try to send new offer")
-		case changed := <-conn.iCEDisconnected:
-			if !changed {
-				continue
-			}
-			conn.log.Debugf("ICE state changed, try to send new offer")
-		case <-conn.ctx.Done():
-			conn.log.Debugf("context is done, stop reconnect loop")
-			return
-		}
-
-		err := conn.handshaker.SendOffer()
-		if err != nil {
-			conn.log.Errorf("failed to do handshake: %v", err)
-		}
-	}
-}
-
 // configureConnection starts proxying traffic from/to local Wireguard and sets connection status to StatusConnected
 func (conn *Conn) iCEConnectionIsReady(priority ConnPriority, iceConnInfo ICEConnInfo) {
 	conn.mu.Lock()
@@ -513,7 +399,7 @@ func (conn *Conn) onWorkerICEStateDisconnected(newState ConnStatus) {
 	changed := conn.statusICE.Get() != newState && newState != StatusConnecting
 	conn.statusICE.Set(newState)
 
-	conn.notifyReconnectLoopICEDisconnected(changed)
+	conn.guard.SetICEConnDisconnected(changed)
 
 	peerState := State{
 		PubKey:           conn.config.Key,
@@ -604,7 +490,7 @@ func (conn *Conn) onWorkerRelayStateDisconnected() {
 
 	changed := conn.statusRelay.Get() != StatusDisconnected
 	conn.statusRelay.Set(StatusDisconnected)
-	conn.notifyReconnectLoopRelayDisconnected(changed)
+	conn.guard.SetRelayedConnDisconnected(changed)
 
 	peerState := State{
 		PubKey:           conn.config.Key,
@@ -617,6 +503,20 @@ func (conn *Conn) onWorkerRelayStateDisconnected() {
 	}
 }
 
+func (conn *Conn) listenGuardEvent(ctx context.Context) {
+	for {
+		select {
+		case <-conn.guard.Reconnect:
+			conn.log.Debugf("send offer to peer")
+			if err := conn.handshaker.SendOffer(); err != nil {
+				conn.log.Errorf("failed to send offer: %v", err)
+			}
+		case <-ctx.Done():
+			return
+		}
+	}
+}
+
 func (conn *Conn) configureWGEndpoint(addr *net.UDPAddr) error {
 	return conn.config.WgConfig.WgInterface.UpdatePeer(
 		conn.config.WgConfig.RemoteKey,
@@ -693,7 +593,7 @@ func (conn *Conn) doOnConnected(remoteRosenpassPubKey []byte, remoteRosenpassAdd
 	}
 }
 
-func (conn *Conn) waitInitialRandomSleepTime() {
+func (conn *Conn) waitInitialRandomSleepTime(ctx context.Context) {
 	minWait := 100
 	maxWait := 800
 	duration := time.Duration(rand.Intn(maxWait-minWait)+minWait) * time.Millisecond
@@ -702,7 +602,7 @@ func (conn *Conn) waitInitialRandomSleepTime() {
 	defer timeout.Stop()
 
 	select {
-	case <-conn.ctx.Done():
+	case <-ctx.Done():
 	case <-timeout.C:
 	}
 }
@@ -731,11 +631,17 @@ func (conn *Conn) evalStatus() ConnStatus {
 	return StatusDisconnected
 }
 
-func (conn *Conn) isConnected() bool {
+func (conn *Conn) isConnectedOnAllWay() (connected bool) {
 	conn.mu.Lock()
 	defer conn.mu.Unlock()
 
-	if conn.statusICE.Get() != StatusConnected && conn.statusICE.Get() != StatusConnecting {
+	defer func() {
+		if !connected {
+			conn.logTraceConnState()
+		}
+	}()
+
+	if conn.statusICE.Get() == StatusDisconnected {
 		return false
 	}
 
@@ -805,20 +711,6 @@ func (conn *Conn) removeWgPeer() error {
 	return conn.config.WgConfig.WgInterface.RemovePeer(conn.config.WgConfig.RemoteKey)
 }
 
-func (conn *Conn) notifyReconnectLoopRelayDisconnected(changed bool) {
-	select {
-	case conn.relayDisconnected <- changed:
-	default:
-	}
-}
-
-func (conn *Conn) notifyReconnectLoopICEDisconnected(changed bool) {
-	select {
-	case conn.iCEDisconnected <- changed:
-	default:
-	}
-}
-
 func (conn *Conn) handleConfigurationFailure(err error, wgProxy wgproxy.Proxy) {
 	conn.log.Warnf("Failed to update wg peer configuration: %v", err)
 	if wgProxy != nil {
@@ -831,6 +723,18 @@ func (conn *Conn) handleConfigurationFailure(err error, wgProxy wgproxy.Proxy) {
 	}
 }
 
+func (conn *Conn) logTraceConnState() {
+	if conn.workerRelay.IsRelayConnectionSupportedWithPeer() {
+		conn.log.Tracef("connectivity guard check, relay state: %s, ice state: %s", conn.statusRelay, conn.statusICE)
+	} else {
+		conn.log.Tracef("connectivity guard check, ice state: %s", conn.statusICE)
+	}
+}
+
+func isController(config ConnConfig) bool {
+	return config.LocalKey > config.Key
+}
+
 func isRosenpassEnabled(remoteRosenpassPubKey []byte) bool {
 	return remoteRosenpassPubKey != nil
 }

client/internal/peer/conn_monitor.go

@@ -1,212 +0,0 @@
-package peer
-
-import (
-	"context"
-	"fmt"
-	"sync"
-	"time"
-
-	"github.com/pion/ice/v3"
-	log "github.com/sirupsen/logrus"
-
-	"github.com/netbirdio/netbird/client/internal/stdnet"
-)
-
-const (
-	signalerMonitorPeriod     = 5 * time.Second
-	candidatesMonitorPeriod   = 5 * time.Minute
-	candidateGatheringTimeout = 5 * time.Second
-)
-
-type ConnMonitor struct {
-	signaler          *Signaler
-	iFaceDiscover     stdnet.ExternalIFaceDiscover
-	config            ConnConfig
-	relayDisconnected chan bool
-	iCEDisconnected   chan bool
-	reconnectCh       chan struct{}
-	currentCandidates []ice.Candidate
-	candidatesMu      sync.Mutex
-}
-
-func NewConnMonitor(signaler *Signaler, iFaceDiscover stdnet.ExternalIFaceDiscover, config ConnConfig, relayDisconnected, iCEDisconnected chan bool) (*ConnMonitor, <-chan struct{}) {
-	reconnectCh := make(chan struct{}, 1)
-	cm := &ConnMonitor{
-		signaler:          signaler,
-		iFaceDiscover:     iFaceDiscover,
-		config:            config,
-		relayDisconnected: relayDisconnected,
-		iCEDisconnected:   iCEDisconnected,
-		reconnectCh:       reconnectCh,
-	}
-	return cm, reconnectCh
-}
-
-func (cm *ConnMonitor) Start(ctx context.Context) {
-	signalerReady := make(chan struct{}, 1)
-	go cm.monitorSignalerReady(ctx, signalerReady)
-
-	localCandidatesChanged := make(chan struct{}, 1)
-	go cm.monitorLocalCandidatesChanged(ctx, localCandidatesChanged)
-
-	for {
-		select {
-		case changed := <-cm.relayDisconnected:
-			if !changed {
-				continue
-			}
-			log.Debugf("Relay state changed, triggering reconnect")
-			cm.triggerReconnect()
-
-		case changed := <-cm.iCEDisconnected:
-			if !changed {
-				continue
-			}
-			log.Debugf("ICE state changed, triggering reconnect")
-			cm.triggerReconnect()
-
-		case <-signalerReady:
-			log.Debugf("Signaler became ready, triggering reconnect")
-			cm.triggerReconnect()
-
-		case <-localCandidatesChanged:
-			log.Debugf("Local candidates changed, triggering reconnect")
-			cm.triggerReconnect()
-
-		case <-ctx.Done():
-			return
-		}
-	}
-}
-
-func (cm *ConnMonitor) monitorSignalerReady(ctx context.Context, signalerReady chan<- struct{}) {
-	if cm.signaler == nil {
-		return
-	}
-
-	ticker := time.NewTicker(signalerMonitorPeriod)
-	defer ticker.Stop()
-
-	lastReady := true
-	for {
-		select {
-		case <-ticker.C:
-			currentReady := cm.signaler.Ready()
-			if !lastReady && currentReady {
-				select {
-				case signalerReady <- struct{}{}:
-				default:
-				}
-			}
-			lastReady = currentReady
-		case <-ctx.Done():
-			return
-		}
-	}
-}
-
-func (cm *ConnMonitor) monitorLocalCandidatesChanged(ctx context.Context, localCandidatesChanged chan<- struct{}) {
-	ufrag, pwd, err := generateICECredentials()
-	if err != nil {
-		log.Warnf("Failed to generate ICE credentials: %v", err)
-		return
-	}
-
-	ticker := time.NewTicker(candidatesMonitorPeriod)
-	defer ticker.Stop()
-
-	for {
-		select {
-		case <-ticker.C:
-			if err := cm.handleCandidateTick(ctx, localCandidatesChanged, ufrag, pwd); err != nil {
-				log.Warnf("Failed to handle candidate tick: %v", err)
-			}
-		case <-ctx.Done():
-			return
-		}
-	}
-}
-
-func (cm *ConnMonitor) handleCandidateTick(ctx context.Context, localCandidatesChanged chan<- struct{}, ufrag string, pwd string) error {
-	log.Debugf("Gathering ICE candidates")
-
-	transportNet, err := newStdNet(cm.iFaceDiscover, cm.config.ICEConfig.InterfaceBlackList)
-	if err != nil {
-		log.Errorf("failed to create pion's stdnet: %s", err)
-	}
-
-	agent, err := newAgent(cm.config, transportNet, candidateTypesP2P(), ufrag, pwd)
-	if err != nil {
-		return fmt.Errorf("create ICE agent: %w", err)
-	}
-	defer func() {
-		if err := agent.Close(); err != nil {
-			log.Warnf("Failed to close ICE agent: %v", err)
-		}
-	}()
-
-	gatherDone := make(chan struct{})
-	err = agent.OnCandidate(func(c ice.Candidate) {
-		log.Tracef("Got candidate: %v", c)
-		if c == nil {
-			close(gatherDone)
-		}
-	})
-	if err != nil {
-		return fmt.Errorf("set ICE candidate handler: %w", err)
-	}
-
-	if err := agent.GatherCandidates(); err != nil {
-		return fmt.Errorf("gather ICE candidates: %w", err)
-	}
-
-	ctx, cancel := context.WithTimeout(ctx, candidateGatheringTimeout)
-	defer cancel()
-
-	select {
-	case <-ctx.Done():
-		return fmt.Errorf("wait for gathering: %w", ctx.Err())
-	case <-gatherDone:
-	}
-
-	candidates, err := agent.GetLocalCandidates()
-	if err != nil {
-		return fmt.Errorf("get local candidates: %w", err)
-	}
-	log.Tracef("Got candidates: %v", candidates)
-
-	if changed := cm.updateCandidates(candidates); changed {
-		select {
-		case localCandidatesChanged <- struct{}{}:
-		default:
-		}
-	}
-
-	return nil
-}
-
-func (cm *ConnMonitor) updateCandidates(newCandidates []ice.Candidate) bool {
-	cm.candidatesMu.Lock()
-	defer cm.candidatesMu.Unlock()
-
-	if len(cm.currentCandidates) != len(newCandidates) {
-		cm.currentCandidates = newCandidates
-		return true
-	}
-
-	for i, candidate := range cm.currentCandidates {
-		if candidate.Address() != newCandidates[i].Address() {
-			cm.currentCandidates = newCandidates
-			return true
-		}
-	}
-
-	return false
-}
-
-func (cm *ConnMonitor) triggerReconnect() {
-	select {
-	case cm.reconnectCh <- struct{}{}:
-	default:
-	}
-}

client/internal/peer/conn_test.go

@@ -10,6 +10,8 @@ import (
 	"github.com/magiconair/properties/assert"
 
 	"github.com/netbirdio/netbird/client/iface"
+	"github.com/netbirdio/netbird/client/internal/peer/guard"
+	"github.com/netbirdio/netbird/client/internal/peer/ice"
 	"github.com/netbirdio/netbird/client/internal/stdnet"
 	"github.com/netbirdio/netbird/util"
 )
@@ -19,7 +21,7 @@ var connConf = ConnConfig{
 	LocalKey:    "RRHf3Ma6z6mdLbriAJbqhX7+nM/B71lgw2+91q3LfhU=",
 	Timeout:     time.Second,
 	LocalWgPort: 51820,
-	ICEConfig: ICEConfig{
+	ICEConfig: ice.Config{
 		InterfaceBlackList: nil,
 	},
 }
@@ -43,7 +45,8 @@ func TestNewConn_interfaceFilter(t *testing.T) {
 }
 
 func TestConn_GetKey(t *testing.T) {
-	conn, err := NewConn(context.Background(), connConf, nil, nil, nil, nil)
+	swWatcher := guard.NewSRWatcher(nil, nil, nil, connConf.ICEConfig)
+	conn, err := NewConn(context.Background(), connConf, nil, nil, nil, nil, swWatcher)
 	if err != nil {
 		return
 	}
@@ -54,7 +57,8 @@ func TestConn_GetKey(t *testing.T) {
 }
 
 func TestConn_OnRemoteOffer(t *testing.T) {
-	conn, err := NewConn(context.Background(), connConf, NewRecorder("https://mgm"), nil, nil, nil)
+	swWatcher := guard.NewSRWatcher(nil, nil, nil, connConf.ICEConfig)
+	conn, err := NewConn(context.Background(), connConf, NewRecorder("https://mgm"), nil, nil, nil, swWatcher)
 	if err != nil {
 		return
 	}
@@ -87,7 +91,8 @@ func TestConn_OnRemoteOffer(t *testing.T) {
 }
 
 func TestConn_OnRemoteAnswer(t *testing.T) {
-	conn, err := NewConn(context.Background(), connConf, NewRecorder("https://mgm"), nil, nil, nil)
+	swWatcher := guard.NewSRWatcher(nil, nil, nil, connConf.ICEConfig)
+	conn, err := NewConn(context.Background(), connConf, NewRecorder("https://mgm"), nil, nil, nil, swWatcher)
 	if err != nil {
 		return
 	}
@@ -119,7 +124,8 @@ func TestConn_OnRemoteAnswer(t *testing.T) {
 	wg.Wait()
 }
 func TestConn_Status(t *testing.T) {
-	conn, err := NewConn(context.Background(), connConf, NewRecorder("https://mgm"), nil, nil, nil)
+	swWatcher := guard.NewSRWatcher(nil, nil, nil, connConf.ICEConfig)
+	conn, err := NewConn(context.Background(), connConf, NewRecorder("https://mgm"), nil, nil, nil, swWatcher)
 	if err != nil {
 		return
 	}

client/internal/peer/guard/guard.go

@@ -0,0 +1,194 @@
+package guard
+
+import (
+	"context"
+	"time"
+
+	"github.com/cenkalti/backoff/v4"
+	log "github.com/sirupsen/logrus"
+)
+
+const (
+	reconnectMaxElapsedTime = 30 * time.Minute
+)
+
+type isConnectedFunc func() bool
+
+// Guard is responsible for the reconnection logic.
+// It will trigger to send an offer to the peer then has connection issues.
+// Watch these events:
+// - Relay client reconnected to home server
+// - Signal server connection state changed
+// - ICE connection disconnected
+// - Relayed connection disconnected
+// - ICE candidate changes
+type Guard struct {
+	Reconnect               chan struct{}
+	log                     *log.Entry
+	isController            bool
+	isConnectedOnAllWay     isConnectedFunc
+	timeout                 time.Duration
+	srWatcher               *SRWatcher
+	relayedConnDisconnected chan bool
+	iCEConnDisconnected     chan bool
+}
+
+func NewGuard(log *log.Entry, isController bool, isConnectedFn isConnectedFunc, timeout time.Duration, srWatcher *SRWatcher) *Guard {
+	return &Guard{
+		Reconnect:               make(chan struct{}, 1),
+		log:                     log,
+		isController:            isController,
+		isConnectedOnAllWay:     isConnectedFn,
+		timeout:                 timeout,
+		srWatcher:               srWatcher,
+		relayedConnDisconnected: make(chan bool, 1),
+		iCEConnDisconnected:     make(chan bool, 1),
+	}
+}
+
+func (g *Guard) Start(ctx context.Context) {
+	if g.isController {
+		g.reconnectLoopWithRetry(ctx)
+	} else {
+		g.listenForDisconnectEvents(ctx)
+	}
+}
+
+func (g *Guard) SetRelayedConnDisconnected(changed bool) {
+	select {
+	case g.relayedConnDisconnected <- changed:
+	default:
+	}
+}
+
+func (g *Guard) SetICEConnDisconnected(changed bool) {
+	select {
+	case g.iCEConnDisconnected <- changed:
+	default:
+	}
+}
+
+// reconnectLoopWithRetry periodically check (max 30 min) the connection status.
+// Try to send offer while the P2P is not established or while the Relay is not connected if is it supported
+func (g *Guard) reconnectLoopWithRetry(ctx context.Context) {
+	waitForInitialConnectionTry(ctx)
+
+	srReconnectedChan := g.srWatcher.NewListener()
+	defer g.srWatcher.RemoveListener(srReconnectedChan)
+
+	ticker := g.prepareExponentTicker(ctx)
+	defer ticker.Stop()
+
+	tickerChannel := ticker.C
+
+	g.log.Infof("start reconnect loop...")
+	for {
+		select {
+		case t := <-tickerChannel:
+			if t.IsZero() {
+				g.log.Infof("retry timed out, stop periodic offer sending")
+				// after backoff timeout the ticker.C will be closed. We need to a dummy channel to avoid loop
+				tickerChannel = make(<-chan time.Time)
+				continue
+			}
+
+			if !g.isConnectedOnAllWay() {
+				g.triggerOfferSending()
+			}
+
+		case changed := <-g.relayedConnDisconnected:
+			if !changed {
+				continue
+			}
+			g.log.Debugf("Relay connection changed, reset reconnection ticker")
+			ticker.Stop()
+			ticker = g.prepareExponentTicker(ctx)
+			tickerChannel = ticker.C
+
+		case changed := <-g.iCEConnDisconnected:
+			if !changed {
+				continue
+			}
+			g.log.Debugf("ICE connection changed, reset reconnection ticker")
+			ticker.Stop()
+			ticker = g.prepareExponentTicker(ctx)
+			tickerChannel = ticker.C
+
+		case <-srReconnectedChan:
+			g.log.Debugf("has network changes, reset reconnection ticker")
+			ticker.Stop()
+			ticker = g.prepareExponentTicker(ctx)
+			tickerChannel = ticker.C
+
+		case <-ctx.Done():
+			g.log.Debugf("context is done, stop reconnect loop")
+			return
+		}
+	}
+}
+
+// listenForDisconnectEvents is used when the peer is not a controller and it should reconnect to the peer
+// when the connection is lost. It will try to establish a connection only once time if before the connection was established
+// It track separately the ice and relay connection status. Just because a lower priority connection reestablished it does not
+// mean that to switch to it. We always force to use the higher priority connection.
+func (g *Guard) listenForDisconnectEvents(ctx context.Context) {
+	srReconnectedChan := g.srWatcher.NewListener()
+	defer g.srWatcher.RemoveListener(srReconnectedChan)
+
+	g.log.Infof("start listen for reconnect events...")
+	for {
+		select {
+		case changed := <-g.relayedConnDisconnected:
+			if !changed {
+				continue
+			}
+			g.log.Debugf("Relay connection changed, triggering reconnect")
+			g.triggerOfferSending()
+		case changed := <-g.iCEConnDisconnected:
+			if !changed {
+				continue
+			}
+			g.log.Debugf("ICE state changed, try to send new offer")
+			g.triggerOfferSending()
+		case <-srReconnectedChan:
+			g.triggerOfferSending()
+		case <-ctx.Done():
+			g.log.Debugf("context is done, stop reconnect loop")
+			return
+		}
+	}
+}
+
+func (g *Guard) prepareExponentTicker(ctx context.Context) *backoff.Ticker {
+	bo := backoff.WithContext(&backoff.ExponentialBackOff{
+		InitialInterval:     800 * time.Millisecond,
+		RandomizationFactor: 0.1,
+		Multiplier:          2,
+		MaxInterval:         g.timeout,
+		MaxElapsedTime:      reconnectMaxElapsedTime,
+		Stop:                backoff.Stop,
+		Clock:               backoff.SystemClock,
+	}, ctx)
+
+	ticker := backoff.NewTicker(bo)
+	<-ticker.C // consume the initial tick what is happening right after the ticker has been created
+
+	return ticker
+}
+
+func (g *Guard) triggerOfferSending() {
+	select {
+	case g.Reconnect <- struct{}{}:
+	default:
+	}
+}
+
+// Give chance to the peer to establish the initial connection.
+// With it, we can decrease to send necessary offer
+func waitForInitialConnectionTry(ctx context.Context) {
+	select {
+	case <-ctx.Done():
+		return
+	case <-time.After(3 * time.Second):
+	}
+}

client/internal/peer/guard/ice_monitor.go

@@ -0,0 +1,135 @@
+package guard
+
+import (
+	"context"
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/pion/ice/v3"
+	log "github.com/sirupsen/logrus"
+
+	icemaker "github.com/netbirdio/netbird/client/internal/peer/ice"
+	"github.com/netbirdio/netbird/client/internal/stdnet"
+)
+
+const (
+	candidatesMonitorPeriod   = 5 * time.Minute
+	candidateGatheringTimeout = 5 * time.Second
+)
+
+type ICEMonitor struct {
+	ReconnectCh chan struct{}
+
+	iFaceDiscover stdnet.ExternalIFaceDiscover
+	iceConfig     icemaker.Config
+
+	currentCandidates []ice.Candidate
+	candidatesMu      sync.Mutex
+}
+
+func NewICEMonitor(iFaceDiscover stdnet.ExternalIFaceDiscover, config icemaker.Config) *ICEMonitor {
+	cm := &ICEMonitor{
+		ReconnectCh:   make(chan struct{}, 1),
+		iFaceDiscover: iFaceDiscover,
+		iceConfig:     config,
+	}
+	return cm
+}
+
+func (cm *ICEMonitor) Start(ctx context.Context, onChanged func()) {
+	ufrag, pwd, err := icemaker.GenerateICECredentials()
+	if err != nil {
+		log.Warnf("Failed to generate ICE credentials: %v", err)
+		return
+	}
+
+	ticker := time.NewTicker(candidatesMonitorPeriod)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ticker.C:
+			changed, err := cm.handleCandidateTick(ctx, ufrag, pwd)
+			if err != nil {
+				log.Warnf("Failed to check ICE changes: %v", err)
+				continue
+			}
+
+			if changed {
+				onChanged()
+			}
+		case <-ctx.Done():
+			return
+		}
+	}
+}
+
+func (cm *ICEMonitor) handleCandidateTick(ctx context.Context, ufrag string, pwd string) (bool, error) {
+	log.Debugf("Gathering ICE candidates")
+
+	agent, err := icemaker.NewAgent(cm.iFaceDiscover, cm.iceConfig, candidateTypesP2P(), ufrag, pwd)
+	if err != nil {
+		return false, fmt.Errorf("create ICE agent: %w", err)
+	}
+	defer func() {
+		if err := agent.Close(); err != nil {
+			log.Warnf("Failed to close ICE agent: %v", err)
+		}
+	}()
+
+	gatherDone := make(chan struct{})
+	err = agent.OnCandidate(func(c ice.Candidate) {
+		log.Tracef("Got candidate: %v", c)
+		if c == nil {
+			close(gatherDone)
+		}
+	})
+	if err != nil {
+		return false, fmt.Errorf("set ICE candidate handler: %w", err)
+	}
+
+	if err := agent.GatherCandidates(); err != nil {
+		return false, fmt.Errorf("gather ICE candidates: %w", err)
+	}
+
+	ctx, cancel := context.WithTimeout(ctx, candidateGatheringTimeout)
+	defer cancel()
+
+	select {
+	case <-ctx.Done():
+		return false, fmt.Errorf("wait for gathering timed out")
+	case <-gatherDone:
+	}
+
+	candidates, err := agent.GetLocalCandidates()
+	if err != nil {
+		return false, fmt.Errorf("get local candidates: %w", err)
+	}
+	log.Tracef("Got candidates: %v", candidates)
+
+	return cm.updateCandidates(candidates), nil
+}
+
+func (cm *ICEMonitor) updateCandidates(newCandidates []ice.Candidate) bool {
+	cm.candidatesMu.Lock()
+	defer cm.candidatesMu.Unlock()
+
+	if len(cm.currentCandidates) != len(newCandidates) {
+		cm.currentCandidates = newCandidates
+		return true
+	}
+
+	for i, candidate := range cm.currentCandidates {
+		if candidate.Address() != newCandidates[i].Address() {
+			cm.currentCandidates = newCandidates
+			return true
+		}
+	}
+
+	return false
+}
+
+func candidateTypesP2P() []ice.CandidateType {
+	return []ice.CandidateType{ice.CandidateTypeHost, ice.CandidateTypeServerReflexive}
+}

client/internal/peer/guard/sr_watcher.go

@@ -0,0 +1,119 @@
+package guard
+
+import (
+	"context"
+	"sync"
+
+	log "github.com/sirupsen/logrus"
+
+	"github.com/netbirdio/netbird/client/internal/peer/ice"
+	"github.com/netbirdio/netbird/client/internal/stdnet"
+)
+
+type chNotifier interface {
+	SetOnReconnectedListener(func())
+	Ready() bool
+}
+
+type SRWatcher struct {
+	signalClient chNotifier
+	relayManager chNotifier
+
+	listeners     map[chan struct{}]struct{}
+	mu            sync.Mutex
+	iFaceDiscover stdnet.ExternalIFaceDiscover
+	iceConfig     ice.Config
+
+	cancelIceMonitor context.CancelFunc
+}
+
+// NewSRWatcher creates a new SRWatcher. This watcher will notify the listeners when the ICE candidates change or the
+// Relay connection is reconnected or the Signal client reconnected.
+func NewSRWatcher(signalClient chNotifier, relayManager chNotifier, iFaceDiscover stdnet.ExternalIFaceDiscover, iceConfig ice.Config) *SRWatcher {
+	srw := &SRWatcher{
+		signalClient:  signalClient,
+		relayManager:  relayManager,
+		iFaceDiscover: iFaceDiscover,
+		iceConfig:     iceConfig,
+		listeners:     make(map[chan struct{}]struct{}),
+	}
+	return srw
+}
+
+func (w *SRWatcher) Start() {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+
+	if w.cancelIceMonitor != nil {
+		return
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	w.cancelIceMonitor = cancel
+
+	iceMonitor := NewICEMonitor(w.iFaceDiscover, w.iceConfig)
+	go iceMonitor.Start(ctx, w.onICEChanged)
+	w.signalClient.SetOnReconnectedListener(w.onReconnected)
+	w.relayManager.SetOnReconnectedListener(w.onReconnected)
+
+}
+
+func (w *SRWatcher) Close() {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+
+	if w.cancelIceMonitor == nil {
+		return
+	}
+	w.cancelIceMonitor()
+	w.signalClient.SetOnReconnectedListener(nil)
+	w.relayManager.SetOnReconnectedListener(nil)
+}
+
+func (w *SRWatcher) NewListener() chan struct{} {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+
+	listenerChan := make(chan struct{}, 1)
+	w.listeners[listenerChan] = struct{}{}
+	return listenerChan
+}
+
+func (w *SRWatcher) RemoveListener(listenerChan chan struct{}) {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	delete(w.listeners, listenerChan)
+	close(listenerChan)
+}
+
+func (w *SRWatcher) onICEChanged() {
+	if !w.signalClient.Ready() {
+		return
+	}
+
+	log.Infof("network changes detected by ICE agent")
+	w.notify()
+}
+
+func (w *SRWatcher) onReconnected() {
+	if !w.signalClient.Ready() {
+		return
+	}
+	if !w.relayManager.Ready() {
+		return
+	}
+
+	log.Infof("reconnected to Signal or Relay server")
+	w.notify()
+}
+
+func (w *SRWatcher) notify() {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	for listener := range w.listeners {
+		select {
+		case listener <- struct{}{}:
+		default:
+		}
+	}
+}

client/internal/peer/ice/agent.go

@@ -0,0 +1,89 @@
+package ice
+
+import (
+	"github.com/netbirdio/netbird/client/internal/stdnet"
+	"github.com/pion/ice/v3"
+	"github.com/pion/randutil"
+	"github.com/pion/stun/v2"
+	log "github.com/sirupsen/logrus"
+	"runtime"
+	"time"
+)
+
+const (
+	lenUFrag   = 16
+	lenPwd     = 32
+	runesAlpha = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+
+	iceKeepAliveDefault           = 4 * time.Second
+	iceDisconnectedTimeoutDefault = 6 * time.Second
+	// iceRelayAcceptanceMinWaitDefault is the same as in the Pion ICE package
+	iceRelayAcceptanceMinWaitDefault = 2 * time.Second
+)
+
+var (
+	failedTimeout = 6 * time.Second
+)
+
+func NewAgent(iFaceDiscover stdnet.ExternalIFaceDiscover, config Config, candidateTypes []ice.CandidateType, ufrag string, pwd string) (*ice.Agent, error) {
+	iceKeepAlive := iceKeepAlive()
+	iceDisconnectedTimeout := iceDisconnectedTimeout()
+	iceRelayAcceptanceMinWait := iceRelayAcceptanceMinWait()
+
+	transportNet, err := newStdNet(iFaceDiscover, config.InterfaceBlackList)
+	if err != nil {
+		log.Errorf("failed to create pion's stdnet: %s", err)
+	}
+
+	agentConfig := &ice.AgentConfig{
+		MulticastDNSMode:       ice.MulticastDNSModeDisabled,
+		NetworkTypes:           []ice.NetworkType{ice.NetworkTypeUDP4, ice.NetworkTypeUDP6},
+		Urls:                   config.StunTurn.Load().([]*stun.URI),
+		CandidateTypes:         candidateTypes,
+		InterfaceFilter:        stdnet.InterfaceFilter(config.InterfaceBlackList),
+		UDPMux:                 config.UDPMux,
+		UDPMuxSrflx:            config.UDPMuxSrflx,
+		NAT1To1IPs:             config.NATExternalIPs,
+		Net:                    transportNet,
+		FailedTimeout:          &failedTimeout,
+		DisconnectedTimeout:    &iceDisconnectedTimeout,
+		KeepaliveInterval:      &iceKeepAlive,
+		RelayAcceptanceMinWait: &iceRelayAcceptanceMinWait,
+		LocalUfrag:             ufrag,
+		LocalPwd:               pwd,
+	}
+
+	if config.DisableIPv6Discovery {
+		agentConfig.NetworkTypes = []ice.NetworkType{ice.NetworkTypeUDP4}
+	}
+
+	return ice.NewAgent(agentConfig)
+}
+
+func GenerateICECredentials() (string, string, error) {
+	ufrag, err := randutil.GenerateCryptoRandomString(lenUFrag, runesAlpha)
+	if err != nil {
+		return "", "", err
+	}
+
+	pwd, err := randutil.GenerateCryptoRandomString(lenPwd, runesAlpha)
+	if err != nil {
+		return "", "", err
+	}
+	return ufrag, pwd, nil
+}
+
+func CandidateTypes() []ice.CandidateType {
+	if hasICEForceRelayConn() {
+		return []ice.CandidateType{ice.CandidateTypeRelay}
+	}
+	// TODO: remove this once we have refactored userspace proxy into the bind package
+	if runtime.GOOS == "ios" {
+		return []ice.CandidateType{ice.CandidateTypeHost, ice.CandidateTypeServerReflexive}
+	}
+	return []ice.CandidateType{ice.CandidateTypeHost, ice.CandidateTypeServerReflexive, ice.CandidateTypeRelay}
+}
+
+func CandidateTypesP2P() []ice.CandidateType {
+	return []ice.CandidateType{ice.CandidateTypeHost, ice.CandidateTypeServerReflexive}
+}

client/internal/peer/ice/config.go

@@ -0,0 +1,22 @@
+package ice
+
+import (
+	"sync/atomic"
+
+	"github.com/pion/ice/v3"
+)
+
+type Config struct {
+	// StunTurn is a list of STUN and TURN URLs
+	StunTurn *atomic.Value // []*stun.URI
+
+	// InterfaceBlackList is a list of machine interfaces that should be filtered out by ICE Candidate gathering
+	// (e.g. if eth0 is in the list, host candidate of this interface won't be used)
+	InterfaceBlackList   []string
+	DisableIPv6Discovery bool
+
+	UDPMux      ice.UDPMux
+	UDPMuxSrflx ice.UniversalUDPMux
+
+	NATExternalIPs []string
+}

client/internal/peer/ice/env.go

@@ -1,4 +1,4 @@
-package peer
+package ice
 
 import (
 	"os"
@@ -10,12 +10,19 @@ import (
 )
 
 const (
+	envICEForceRelayConn            = "NB_ICE_FORCE_RELAY_CONN"
 	envICEKeepAliveIntervalSec      = "NB_ICE_KEEP_ALIVE_INTERVAL_SEC"
 	envICEDisconnectedTimeoutSec    = "NB_ICE_DISCONNECTED_TIMEOUT_SEC"
 	envICERelayAcceptanceMinWaitSec = "NB_ICE_RELAY_ACCEPTANCE_MIN_WAIT_SEC"
-	envICEForceRelayConn            = "NB_ICE_FORCE_RELAY_CONN"
+
+	msgWarnInvalidValue = "invalid value %s set for %s, using default %v"
 )
 
+func hasICEForceRelayConn() bool {
+	disconnectedTimeoutEnv := os.Getenv(envICEForceRelayConn)
+	return strings.ToLower(disconnectedTimeoutEnv) == "true"
+}
+
 func iceKeepAlive() time.Duration {
 	keepAliveEnv := os.Getenv(envICEKeepAliveIntervalSec)
 	if keepAliveEnv == "" {
@@ -25,7 +32,7 @@ func iceKeepAlive() time.Duration {
 	log.Infof("setting ICE keep alive interval to %s seconds", keepAliveEnv)
 	keepAliveEnvSec, err := strconv.Atoi(keepAliveEnv)
 	if err != nil {
-		log.Warnf("invalid value %s set for %s, using default %v", keepAliveEnv, envICEKeepAliveIntervalSec, iceKeepAliveDefault)
+		log.Warnf(msgWarnInvalidValue, keepAliveEnv, envICEKeepAliveIntervalSec, iceKeepAliveDefault)
 		return iceKeepAliveDefault
 	}
 
@@ -41,7 +48,7 @@ func iceDisconnectedTimeout() time.Duration {
 	log.Infof("setting ICE disconnected timeout to %s seconds", disconnectedTimeoutEnv)
 	disconnectedTimeoutSec, err := strconv.Atoi(disconnectedTimeoutEnv)
 	if err != nil {
-		log.Warnf("invalid value %s set for %s, using default %v", disconnectedTimeoutEnv, envICEDisconnectedTimeoutSec, iceDisconnectedTimeoutDefault)
+		log.Warnf(msgWarnInvalidValue, disconnectedTimeoutEnv, envICEDisconnectedTimeoutSec, iceDisconnectedTimeoutDefault)
 		return iceDisconnectedTimeoutDefault
 	}
 
@@ -57,14 +64,9 @@ func iceRelayAcceptanceMinWait() time.Duration {
 	log.Infof("setting ICE relay acceptance min wait to %s seconds", iceRelayAcceptanceMinWaitEnv)
 	disconnectedTimeoutSec, err := strconv.Atoi(iceRelayAcceptanceMinWaitEnv)
 	if err != nil {
-		log.Warnf("invalid value %s set for %s, using default %v", iceRelayAcceptanceMinWaitEnv, envICERelayAcceptanceMinWaitSec, iceRelayAcceptanceMinWaitDefault)
+		log.Warnf(msgWarnInvalidValue, iceRelayAcceptanceMinWaitEnv, envICERelayAcceptanceMinWaitSec, iceRelayAcceptanceMinWaitDefault)
 		return iceRelayAcceptanceMinWaitDefault
 	}
 
 	return time.Duration(disconnectedTimeoutSec) * time.Second
 }
-
-func hasICEForceRelayConn() bool {
-	disconnectedTimeoutEnv := os.Getenv(envICEForceRelayConn)
-	return strings.ToLower(disconnectedTimeoutEnv) == "true"
-}

client/internal/peer/ice/stdnet.go

@@ -1,6 +1,6 @@
 //go:build !android
 
-package peer
+package ice
 
 import (
 	"github.com/netbirdio/netbird/client/internal/stdnet"

client/internal/peer/ice/stdnet_android.go

@@ -1,4 +1,4 @@
-package peer
+package ice
 
 import "github.com/netbirdio/netbird/client/internal/stdnet"
 

client/internal/peer/worker_ice.go

@@ -5,52 +5,20 @@ import (
 	"fmt"
 	"net"
 	"net/netip"
-	"runtime"
 	"sync"
-	"sync/atomic"
 	"time"
 
 	"github.com/pion/ice/v3"
-	"github.com/pion/randutil"
 	"github.com/pion/stun/v2"
 	log "github.com/sirupsen/logrus"
 
 	"github.com/netbirdio/netbird/client/iface"
 	"github.com/netbirdio/netbird/client/iface/bind"
+	icemaker "github.com/netbirdio/netbird/client/internal/peer/ice"
 	"github.com/netbirdio/netbird/client/internal/stdnet"
 	"github.com/netbirdio/netbird/route"
 )
 
-const (
-	iceKeepAliveDefault           = 4 * time.Second
-	iceDisconnectedTimeoutDefault = 6 * time.Second
-	// iceRelayAcceptanceMinWaitDefault is the same as in the Pion ICE package
-	iceRelayAcceptanceMinWaitDefault = 2 * time.Second
-
-	lenUFrag   = 16
-	lenPwd     = 32
-	runesAlpha = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
-)
-
-var (
-	failedTimeout = 6 * time.Second
-)
-
-type ICEConfig struct {
-	// StunTurn is a list of STUN and TURN URLs
-	StunTurn *atomic.Value // []*stun.URI
-
-	// InterfaceBlackList is a list of machine interfaces that should be filtered out by ICE Candidate gathering
-	// (e.g. if eth0 is in the list, host candidate of this interface won't be used)
-	InterfaceBlackList   []string
-	DisableIPv6Discovery bool
-
-	UDPMux      ice.UDPMux
-	UDPMuxSrflx ice.UniversalUDPMux
-
-	NATExternalIPs []string
-}
-
 type ICEConnInfo struct {
 	RemoteConn                 net.Conn
 	RosenpassPubKey            []byte
@@ -103,7 +71,7 @@ func NewWorkerICE(ctx context.Context, log *log.Entry, config ConnConfig, signal
 		conn:              callBacks,
 	}
 
-	localUfrag, localPwd, err := generateICECredentials()
+	localUfrag, localPwd, err := icemaker.GenerateICECredentials()
 	if err != nil {
 		return nil, err
 	}
@@ -125,10 +93,10 @@ func (w *WorkerICE) OnNewOffer(remoteOfferAnswer *OfferAnswer) {
 	var preferredCandidateTypes []ice.CandidateType
 	if w.hasRelayOnLocally && remoteOfferAnswer.RelaySrvAddress != "" {
 		w.selectedPriority = connPriorityICEP2P
-		preferredCandidateTypes = candidateTypesP2P()
+		preferredCandidateTypes = icemaker.CandidateTypesP2P()
 	} else {
 		w.selectedPriority = connPriorityICETurn
-		preferredCandidateTypes = candidateTypes()
+		preferredCandidateTypes = icemaker.CandidateTypes()
 	}
 
 	w.log.Debugf("recreate ICE agent")
@@ -232,15 +200,10 @@ func (w *WorkerICE) Close() {
 	}
 }
 
-func (w *WorkerICE) reCreateAgent(agentCancel context.CancelFunc, relaySupport []ice.CandidateType) (*ice.Agent, error) {
+func (w *WorkerICE) reCreateAgent(agentCancel context.CancelFunc, candidates []ice.CandidateType) (*ice.Agent, error) {
-	transportNet, err := newStdNet(w.iFaceDiscover, w.config.ICEConfig.InterfaceBlackList)
-	if err != nil {
-		w.log.Errorf("failed to create pion's stdnet: %s", err)
-	}
-
 	w.sentExtraSrflx = false
 
-	agent, err := newAgent(w.config, transportNet, relaySupport, w.localUfrag, w.localPwd)
+	agent, err := icemaker.NewAgent(w.iFaceDiscover, w.config.ICEConfig, candidates, w.localUfrag, w.localPwd)
 	if err != nil {
 		return nil, fmt.Errorf("create agent: %w", err)
 	}
@@ -365,36 +328,6 @@ func (w *WorkerICE) turnAgentDial(ctx context.Context, remoteOfferAnswer *OfferA
 	}
 }
 
-func newAgent(config ConnConfig, transportNet *stdnet.Net, candidateTypes []ice.CandidateType, ufrag string, pwd string) (*ice.Agent, error) {
-	iceKeepAlive := iceKeepAlive()
-	iceDisconnectedTimeout := iceDisconnectedTimeout()
-	iceRelayAcceptanceMinWait := iceRelayAcceptanceMinWait()
-
-	agentConfig := &ice.AgentConfig{
-		MulticastDNSMode:       ice.MulticastDNSModeDisabled,
-		NetworkTypes:           []ice.NetworkType{ice.NetworkTypeUDP4, ice.NetworkTypeUDP6},
-		Urls:                   config.ICEConfig.StunTurn.Load().([]*stun.URI),
-		CandidateTypes:         candidateTypes,
-		InterfaceFilter:        stdnet.InterfaceFilter(config.ICEConfig.InterfaceBlackList),
-		UDPMux:                 config.ICEConfig.UDPMux,
-		UDPMuxSrflx:            config.ICEConfig.UDPMuxSrflx,
-		NAT1To1IPs:             config.ICEConfig.NATExternalIPs,
-		Net:                    transportNet,
-		FailedTimeout:          &failedTimeout,
-		DisconnectedTimeout:    &iceDisconnectedTimeout,
-		KeepaliveInterval:      &iceKeepAlive,
-		RelayAcceptanceMinWait: &iceRelayAcceptanceMinWait,
-		LocalUfrag:             ufrag,
-		LocalPwd:               pwd,
-	}
-
-	if config.ICEConfig.DisableIPv6Discovery {
-		agentConfig.NetworkTypes = []ice.NetworkType{ice.NetworkTypeUDP4}
-	}
-
-	return ice.NewAgent(agentConfig)
-}
-
 func extraSrflxCandidate(candidate ice.Candidate) (*ice.CandidateServerReflexive, error) {
 	relatedAdd := candidate.RelatedAddress()
 	return ice.NewCandidateServerReflexive(&ice.CandidateServerReflexiveConfig{
@@ -435,21 +368,6 @@ func candidateViaRoutes(candidate ice.Candidate, clientRoutes route.HAMap) bool
 	return false
 }
 
-func candidateTypes() []ice.CandidateType {
-	if hasICEForceRelayConn() {
-		return []ice.CandidateType{ice.CandidateTypeRelay}
-	}
-	// TODO: remove this once we have refactored userspace proxy into the bind package
-	if runtime.GOOS == "ios" {
-		return []ice.CandidateType{ice.CandidateTypeHost, ice.CandidateTypeServerReflexive}
-	}
-	return []ice.CandidateType{ice.CandidateTypeHost, ice.CandidateTypeServerReflexive, ice.CandidateTypeRelay}
-}
-
-func candidateTypesP2P() []ice.CandidateType {
-	return []ice.CandidateType{ice.CandidateTypeHost, ice.CandidateTypeServerReflexive}
-}
-
 func isRelayCandidate(candidate ice.Candidate) bool {
 	return candidate.Type() == ice.CandidateTypeRelay
 }
@@ -460,16 +378,3 @@ func isRelayed(pair *ice.CandidatePair) bool {
 	}
 	return false
 }
-
-func generateICECredentials() (string, string, error) {
-	ufrag, err := randutil.GenerateCryptoRandomString(lenUFrag, runesAlpha)
-	if err != nil {
-		return "", "", err
-	}
-
-	pwd, err := randutil.GenerateCryptoRandomString(lenPwd, runesAlpha)
-	if err != nil {
-		return "", "", err
-	}
-	return ufrag, pwd, nil
-}

client/internal/peer/worker_relay.go

@@ -31,6 +31,7 @@ type WorkerRelayCallbacks struct {
 
 type WorkerRelay struct {
 	log          *log.Entry
+	isController bool
 	config       ConnConfig
 	relayManager relayClient.ManagerService
 	callBacks    WorkerRelayCallbacks
@@ -44,9 +45,10 @@ type WorkerRelay struct {
 	relaySupportedOnRemotePeer atomic.Bool
 }
 
-func NewWorkerRelay(log *log.Entry, config ConnConfig, relayManager relayClient.ManagerService, callbacks WorkerRelayCallbacks) *WorkerRelay {
+func NewWorkerRelay(log *log.Entry, ctrl bool, config ConnConfig, relayManager relayClient.ManagerService, callbacks WorkerRelayCallbacks) *WorkerRelay {
 	r := &WorkerRelay{
 		log:          log,
+		isController: ctrl,
 		config:       config,
 		relayManager: relayManager,
 		callBacks:    callbacks,
@@ -80,6 +82,7 @@ func (w *WorkerRelay) OnNewOffer(remoteOfferAnswer *OfferAnswer) {
 		w.log.Errorf("failed to open connection via Relay: %s", err)
 		return
 	}
+
 	w.relayLock.Lock()
 	w.relayedConn = relayedConn
 	w.relayLock.Unlock()
@@ -136,10 +139,6 @@ func (w *WorkerRelay) IsRelayConnectionSupportedWithPeer() bool {
 	return w.relaySupportedOnRemotePeer.Load() && w.RelayIsSupportedLocally()
 }
 
-func (w *WorkerRelay) IsController() bool {
-	return w.config.LocalKey > w.config.Key
-}
-
 func (w *WorkerRelay) RelayIsSupportedLocally() bool {
 	return w.relayManager.HasRelayAddress()
 }
@@ -212,7 +211,7 @@ func (w *WorkerRelay) isRelaySupported(answer *OfferAnswer) bool {
 }
 
 func (w *WorkerRelay) preferredRelayServer(myRelayAddress, remoteRelayAddress string) string {
-	if w.IsController() {
+	if w.isController {
 		return myRelayAddress
 	}
 	return remoteRelayAddress

relay/client/client.go

@@ -142,6 +142,7 @@ type Client struct {
 	muInstanceURL    sync.Mutex
 
 	onDisconnectListener func()
+	onConnectedListener  func()
 	listenerMutex        sync.Mutex
 }
 
@@ -191,6 +192,7 @@ func (c *Client) Connect() error {
 
 	c.wgReadLoop.Add(1)
 	go c.readLoop(c.relayConn)
+	go c.notifyConnected()
 
 	return nil
 }
@@ -238,6 +240,12 @@ func (c *Client) SetOnDisconnectListener(fn func()) {
 	c.onDisconnectListener = fn
 }
 
+func (c *Client) SetOnConnectedListener(fn func()) {
+	c.listenerMutex.Lock()
+	defer c.listenerMutex.Unlock()
+	c.onConnectedListener = fn
+}
+
 // HasConns returns true if there are connections.
 func (c *Client) HasConns() bool {
 	c.mu.Lock()
@@ -245,6 +253,12 @@ func (c *Client) HasConns() bool {
 	return len(c.conns) > 0
 }
 
+func (c *Client) Ready() bool {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.serviceIsRunning
+}
+
 // Close closes the connection to the relay server and all connections to other peers.
 func (c *Client) Close() error {
 	return c.close(true)
@@ -363,9 +377,9 @@ func (c *Client) readLoop(relayConn net.Conn) {
 	c.instanceURL = nil
 	c.muInstanceURL.Unlock()
 
-	c.notifyDisconnected()
 	c.wgReadLoop.Done()
 	_ = c.close(false)
+	c.notifyDisconnected()
 }
 
 func (c *Client) handleMsg(msgType messages.MsgType, buf []byte, bufPtr *[]byte, hc *healthcheck.Receiver, internallyStoppedFlag *internalStopFlag) (continueLoop bool) {
@@ -544,6 +558,16 @@ func (c *Client) notifyDisconnected() {
 	go c.onDisconnectListener()
 }
 
+func (c *Client) notifyConnected() {
+	c.listenerMutex.Lock()
+	defer c.listenerMutex.Unlock()
+
+	if c.onConnectedListener == nil {
+		return
+	}
+	go c.onConnectedListener()
+}
+
 func (c *Client) writeCloseMsg() {
 	msg := messages.MarshalCloseMsg()
 	_, err := c.relayConn.Write(msg)

relay/client/guard.go

@@ -29,6 +29,10 @@ func NewGuard(context context.Context, relayClient *Client) *Guard {
 // OnDisconnected is called when the relay client is disconnected from the relay server. It will trigger the reconnection
 // todo prevent multiple reconnection instances. In the current usage it should not happen, but it is better to prevent
 func (g *Guard) OnDisconnected() {
+	if g.quickReconnect() {
+		return
+	}
+
 	ticker := time.NewTicker(reconnectingTimeout)
 	defer ticker.Stop()
 
@@ -46,3 +50,19 @@ func (g *Guard) OnDisconnected() {
 		}
 	}
 }
+
+func (g *Guard) quickReconnect() bool {
+	ctx, cancel := context.WithTimeout(g.ctx, 1500*time.Millisecond)
+	defer cancel()
+	<-ctx.Done()
+
+	if g.ctx.Err() != nil {
+		return false
+	}
+
+	if err := g.relayClient.Connect(); err != nil {
+		log.Errorf("failed to reconnect to relay server: %s", err)
+		return false
+	}
+	return true
+}

relay/client/manager.go

@@ -65,6 +65,7 @@ type Manager struct {
 	relayClientsMutex sync.RWMutex
 
 	onDisconnectedListeners map[string]*list.List
+	onReconnectedListenerFn func()
 	listenerLock            sync.Mutex
 }
 
@@ -101,6 +102,7 @@ func (m *Manager) Serve() error {
 	m.relayClient = client
 
 	m.reconnectGuard = NewGuard(m.ctx, m.relayClient)
+	m.relayClient.SetOnConnectedListener(m.onServerConnected)
 	m.relayClient.SetOnDisconnectListener(func() {
 		m.onServerDisconnected(client.connectionURL)
 	})
@@ -138,6 +140,18 @@ func (m *Manager) OpenConn(serverAddress, peerKey string) (net.Conn, error) {
 	return netConn, err
 }
 
+// Ready returns true if the home Relay client is connected to the relay server.
+func (m *Manager) Ready() bool {
+	if m.relayClient == nil {
+		return false
+	}
+	return m.relayClient.Ready()
+}
+
+func (m *Manager) SetOnReconnectedListener(f func()) {
+	m.onReconnectedListenerFn = f
+}
+
 // AddCloseListener adds a listener to the given server instance address. The listener will be called if the connection
 // closed.
 func (m *Manager) AddCloseListener(serverAddress string, onClosedListener OnServerCloseListener) error {
@@ -240,6 +254,13 @@ func (m *Manager) openConnVia(serverAddress, peerKey string) (net.Conn, error) {
 	return conn, nil
 }
 
+func (m *Manager) onServerConnected() {
+	if m.onReconnectedListenerFn == nil {
+		return
+	}
+	go m.onReconnectedListenerFn()
+}
+
 func (m *Manager) onServerDisconnected(serverAddress string) {
 	if serverAddress == m.relayClient.connectionURL {
 		go m.reconnectGuard.OnDisconnected()

signal/client/client.go

@@ -35,6 +35,7 @@ type Client interface {
 	WaitStreamConnected()
 	SendToStream(msg *proto.EncryptedMessage) error
 	Send(msg *proto.Message) error
+	SetOnReconnectedListener(func())
 }
 
 // UnMarshalCredential parses the credentials from the message and returns a Credential instance

signal/client/grpc.go

@@ -43,6 +43,8 @@ type GrpcClient struct {
 
 	connStateCallback     ConnStateNotifier
 	connStateCallbackLock sync.RWMutex
+
+	onReconnectedListenerFn func()
 }
 
 func (c *GrpcClient) StreamConnected() bool {
@@ -181,12 +183,17 @@ func (c *GrpcClient) notifyStreamDisconnected() {
 func (c *GrpcClient) notifyStreamConnected() {
 	c.mux.Lock()
 	defer c.mux.Unlock()
+
 	c.status = StreamConnected
 	if c.connectedCh != nil {
 		// there are goroutines waiting on this channel -> release them
 		close(c.connectedCh)
 		c.connectedCh = nil
 	}
+
+	if c.onReconnectedListenerFn != nil {
+		c.onReconnectedListenerFn()
+	}
 }
 
 func (c *GrpcClient) getStreamStatusChan() <-chan struct{} {
@@ -271,6 +278,13 @@ func (c *GrpcClient) WaitStreamConnected() {
 	}
 }
 
+func (c *GrpcClient) SetOnReconnectedListener(fn func()) {
+	c.mux.Lock()
+	defer c.mux.Unlock()
+
+	c.onReconnectedListenerFn = fn
+}
+
 // SendToStream sends a message to the remote Peer through the Signal Exchange using established stream connection to the Signal Server
 // The GrpcClient.Receive method must be called before sending messages to establish initial connection to the Signal Exchange
 // GrpcClient.connWg can be used to wait

signal/client/mock.go

@@ -15,6 +15,12 @@ type MockClient struct {
 	ReceiveFunc                  func(ctx context.Context, msgHandler func(msg *proto.Message) error) error
 	SendToStreamFunc             func(msg *proto.EncryptedMessage) error
 	SendFunc                     func(msg *proto.Message) error
+	SetOnReconnectedListenerFunc func(f func())
+}
+
+// SetOnReconnectedListener sets the function to be called when the client reconnects.
+func (sm *MockClient) SetOnReconnectedListener(_ func()) {
+	// Do nothing
 }
 
 func (sm *MockClient) IsHealthy() bool {