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

Rethink the peer reconnection implementation

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:
+		}
+	}
+}