[client, relay-server] Feature/relay notification (#4083)

- Clients now subscribe to peer status changes.
- The server manages and maintains these subscriptions.
- Replaced raw string peer IDs with a custom peer ID type for better type safety and clarity.

client/iface/wgproxy/bind/proxy.go

@@ -12,6 +12,7 @@ import (
 	log "github.com/sirupsen/logrus"
 
 	"github.com/netbirdio/netbird/client/iface/bind"
+	"github.com/netbirdio/netbird/client/iface/wgproxy/listener"
 )
 
 type ProxyBind struct {
@@ -28,6 +29,17 @@ type ProxyBind struct {
 	pausedMu  sync.Mutex
 	paused    bool
 	isStarted bool
+
+	closeListener *listener.CloseListener
+}
+
+func NewProxyBind(bind *bind.ICEBind) *ProxyBind {
+	p := &ProxyBind{
+		Bind:          bind,
+		closeListener: listener.NewCloseListener(),
+	}
+
+	return p
 }
 
 // AddTurnConn adds a new connection to the bind.
@@ -54,6 +66,10 @@ func (p *ProxyBind) EndpointAddr() *net.UDPAddr {
 	}
 }
 
+func (p *ProxyBind) SetDisconnectListener(disconnected func()) {
+	p.closeListener.SetCloseListener(disconnected)
+}
+
 func (p *ProxyBind) Work() {
 	if p.remoteConn == nil {
 		return
@@ -96,6 +112,9 @@ func (p *ProxyBind) close() error {
 	if p.closed {
 		return nil
 	}
+
+	p.closeListener.SetCloseListener(nil)
+
 	p.closed = true
 
 	p.cancel()
@@ -122,6 +141,7 @@ func (p *ProxyBind) proxyToLocal(ctx context.Context) {
 			if ctx.Err() != nil {
 				return
 			}
+			p.closeListener.Notify()
 			log.Errorf("failed to read from remote conn: %s, %s", p.remoteConn.RemoteAddr(), err)
 			return
 		}

client/iface/wgproxy/ebpf/wrapper.go

@@ -11,6 +11,8 @@ import (
 	"sync"
 
 	log "github.com/sirupsen/logrus"
+
+	"github.com/netbirdio/netbird/client/iface/wgproxy/listener"
 )
 
 // ProxyWrapper help to keep the remoteConn instance for net.Conn.Close function call
@@ -26,6 +28,15 @@ type ProxyWrapper struct {
 	pausedMu  sync.Mutex
 	paused    bool
 	isStarted bool
+
+	closeListener *listener.CloseListener
+}
+
+func NewProxyWrapper(WgeBPFProxy *WGEBPFProxy) *ProxyWrapper {
+	return &ProxyWrapper{
+		WgeBPFProxy:   WgeBPFProxy,
+		closeListener: listener.NewCloseListener(),
+	}
 }
 
 func (p *ProxyWrapper) AddTurnConn(ctx context.Context, endpoint *net.UDPAddr, remoteConn net.Conn) error {
@@ -43,6 +54,10 @@ func (p *ProxyWrapper) EndpointAddr() *net.UDPAddr {
 	return p.wgEndpointAddr
 }
 
+func (p *ProxyWrapper) SetDisconnectListener(disconnected func()) {
+	p.closeListener.SetCloseListener(disconnected)
+}
+
 func (p *ProxyWrapper) Work() {
 	if p.remoteConn == nil {
 		return
@@ -77,6 +92,8 @@ func (e *ProxyWrapper) CloseConn() error {
 
 	e.cancel()
 
+	e.closeListener.SetCloseListener(nil)
+
 	if err := e.remoteConn.Close(); err != nil && !errors.Is(err, net.ErrClosed) {
 		return fmt.Errorf("failed to close remote conn: %w", err)
 	}
@@ -117,6 +134,7 @@ func (p *ProxyWrapper) readFromRemote(ctx context.Context, buf []byte) (int, err
 		if ctx.Err() != nil {
 			return 0, ctx.Err()
 		}
+		p.closeListener.Notify()
 		if !errors.Is(err, io.EOF) {
 			log.Errorf("failed to read from turn conn (endpoint: :%d): %s", p.wgEndpointAddr.Port, err)
 		}

client/iface/wgproxy/factory_kernel.go

@@ -36,9 +36,8 @@ func (w *KernelFactory) GetProxy() Proxy {
 		return udpProxy.NewWGUDPProxy(w.wgPort)
 	}
 
-	return &ebpf.ProxyWrapper{
-		WgeBPFProxy: w.ebpfProxy,
-	}
+	return ebpf.NewProxyWrapper(w.ebpfProxy)
+
 }
 
 func (w *KernelFactory) Free() error {

client/iface/wgproxy/factory_usp.go

@@ -20,9 +20,7 @@ func NewUSPFactory(iceBind *bind.ICEBind) *USPFactory {
 }
 
 func (w *USPFactory) GetProxy() Proxy {
-	return &proxyBind.ProxyBind{
-		Bind: w.bind,
-	}
+	return proxyBind.NewProxyBind(w.bind)
 }
 
 func (w *USPFactory) Free() error {

client/iface/wgproxy/listener/listener.go

@@ -0,0 +1,19 @@
+package listener
+
+type CloseListener struct {
+	listener func()
+}
+
+func NewCloseListener() *CloseListener {
+	return &CloseListener{}
+}
+
+func (c *CloseListener) SetCloseListener(listener func()) {
+	c.listener = listener
+}
+
+func (c *CloseListener) Notify() {
+	if c.listener != nil {
+		c.listener()
+	}
+}

client/iface/wgproxy/proxy.go

@@ -12,4 +12,5 @@ type Proxy interface {
 	Work()                      // Work start or resume the proxy
 	Pause()                     // Pause to forward the packages from remote connection to WireGuard. The opposite way still works.
 	CloseConn() error
+	SetDisconnectListener(disconnected func())
 }

client/iface/wgproxy/proxy_test.go

@@ -98,9 +98,7 @@ func TestProxyCloseByRemoteConn(t *testing.T) {
 				t.Errorf("failed to free ebpf proxy: %s", err)
 			}
 		}()
-		proxyWrapper := &ebpf.ProxyWrapper{
-			WgeBPFProxy: ebpfProxy,
-		}
+		proxyWrapper := ebpf.NewProxyWrapper(ebpfProxy)
 
 		tests = append(tests, struct {
 			name  string

client/iface/wgproxy/udp/proxy.go

@@ -12,6 +12,7 @@ import (
 	log "github.com/sirupsen/logrus"
 
 	cerrors "github.com/netbirdio/netbird/client/errors"
+	"github.com/netbirdio/netbird/client/iface/wgproxy/listener"
 )
 
 // WGUDPProxy proxies
@@ -28,6 +29,8 @@ type WGUDPProxy struct {
 	pausedMu  sync.Mutex
 	paused    bool
 	isStarted bool
+
+	closeListener *listener.CloseListener
 }
 
 // NewWGUDPProxy instantiate a UDP based WireGuard proxy. This is not a thread safe implementation
@@ -35,6 +38,7 @@ func NewWGUDPProxy(wgPort int) *WGUDPProxy {
 	log.Debugf("Initializing new user space proxy with port %d", wgPort)
 	p := &WGUDPProxy{
 		localWGListenPort: wgPort,
+		closeListener:     listener.NewCloseListener(),
 	}
 	return p
 }
@@ -67,6 +71,10 @@ func (p *WGUDPProxy) EndpointAddr() *net.UDPAddr {
 	return endpointUdpAddr
 }
 
+func (p *WGUDPProxy) SetDisconnectListener(disconnected func()) {
+	p.closeListener.SetCloseListener(disconnected)
+}
+
 // Work starts the proxy or resumes it if it was paused
 func (p *WGUDPProxy) Work() {
 	if p.remoteConn == nil {
@@ -111,6 +119,8 @@ func (p *WGUDPProxy) close() error {
 	if p.closed {
 		return nil
 	}
+
+	p.closeListener.SetCloseListener(nil)
 	p.closed = true
 
 	p.cancel()
@@ -141,6 +151,7 @@ func (p *WGUDPProxy) proxyToRemote(ctx context.Context) {
 			if ctx.Err() != nil {
 				return
 			}
+			p.closeListener.Notify()
 			log.Debugf("failed to read from wg interface conn: %s", err)
 			return
 		}

client/internal/peer/conn.go

@@ -167,7 +167,7 @@ func (conn *Conn) Open(engineCtx context.Context) error {
 
 	conn.ctx, conn.ctxCancel = context.WithCancel(engineCtx)
 
-	conn.workerRelay = NewWorkerRelay(conn.Log, isController(conn.config), conn.config, conn, conn.relayManager, conn.dumpState)
+	conn.workerRelay = NewWorkerRelay(conn.ctx, conn.Log, isController(conn.config), conn.config, conn, conn.relayManager, conn.dumpState)
 
 	relayIsSupportedLocally := conn.workerRelay.RelayIsSupportedLocally()
 	workerICE, err := NewWorkerICE(conn.ctx, conn.Log, conn.config, conn, conn.signaler, conn.iFaceDiscover, conn.statusRecorder, relayIsSupportedLocally)
@@ -489,6 +489,8 @@ func (conn *Conn) onRelayConnectionIsReady(rci RelayConnInfo) {
 		conn.Log.Errorf("failed to add relayed net.Conn to local proxy: %v", err)
 		return
 	}
+	wgProxy.SetDisconnectListener(conn.onRelayDisconnected)
+
 	conn.dumpState.NewLocalProxy()
 
 	conn.Log.Infof("created new wgProxy for relay connection: %s", wgProxy.EndpointAddr().String())

client/internal/peer/worker_relay.go

@@ -19,6 +19,7 @@ type RelayConnInfo struct {
 }
 
 type WorkerRelay struct {
+	peerCtx      context.Context
 	log          *log.Entry
 	isController bool
 	config       ConnConfig
@@ -33,8 +34,9 @@ type WorkerRelay struct {
 	wgWatcher *WGWatcher
 }
 
-func NewWorkerRelay(log *log.Entry, ctrl bool, config ConnConfig, conn *Conn, relayManager relayClient.ManagerService, stateDump *stateDump) *WorkerRelay {
+func NewWorkerRelay(ctx context.Context, log *log.Entry, ctrl bool, config ConnConfig, conn *Conn, relayManager relayClient.ManagerService, stateDump *stateDump) *WorkerRelay {
 	r := &WorkerRelay{
+		peerCtx:      ctx,
 		log:          log,
 		isController: ctrl,
 		config:       config,
@@ -62,7 +64,7 @@ func (w *WorkerRelay) OnNewOffer(remoteOfferAnswer *OfferAnswer) {
 
 	srv := w.preferredRelayServer(currentRelayAddress, remoteOfferAnswer.RelaySrvAddress)
 
-	relayedConn, err := w.relayManager.OpenConn(srv, w.config.Key)
+	relayedConn, err := w.relayManager.OpenConn(w.peerCtx, srv, w.config.Key)
 	if err != nil {
 		if errors.Is(err, relayClient.ErrConnAlreadyExists) {
 			w.log.Debugf("handled offer by reusing existing relay connection")