Initial concept

client/internal/lazyconn/watcher/watcher.go

@@ -0,0 +1,103 @@
+package watcher
+
+import (
+	"context"
+	"sync"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
+
+	"github.com/netbirdio/netbird/client/iface/configurer"
+	"github.com/netbirdio/netbird/client/internal/lazyconn"
+)
+
+const (
+	checkPeriod       = 75 * time.Second // 3 * keep alive time (25s)
+	expectedMinimumRx = 90 * 2           // 2x keep alive packets
+)
+
+type rxHistory struct {
+	received int64
+}
+
+type Watcher struct {
+	PeerTimedOutChan chan wgtypes.Key
+
+	wgIface lazyconn.WGIface
+
+	peers   map[wgtypes.Key]*rxHistory
+	peersMu sync.Mutex
+}
+
+func NewWatcher(wgIface lazyconn.WGIface) *Watcher {
+	return &Watcher{
+		PeerTimedOutChan: make(chan wgtypes.Key, 1),
+		wgIface:          wgIface,
+		peers:            make(map[wgtypes.Key]*rxHistory),
+	}
+}
+
+func (m *Watcher) Watch(ctx context.Context) {
+	timer := time.NewTimer(checkPeriod)
+	defer timer.Stop()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-timer.C:
+			stats, err := m.wgIface.Transfers()
+			if err != nil {
+				log.Errorf("failed to get peer stats: %s", err)
+				continue
+			}
+			m.checkTimeouts(ctx, stats)
+		}
+	}
+}
+
+func (m *Watcher) AddPeer(peerID wgtypes.Key) {
+	m.peersMu.Lock()
+	defer m.peersMu.Unlock()
+
+	m.peers[peerID] = &rxHistory{}
+}
+
+func (m *Watcher) RemovePeer(id wgtypes.Key) {
+	m.peersMu.Lock()
+	defer m.peersMu.Unlock()
+
+	delete(m.peers, id)
+}
+
+// Todo: this is a naive implementation, we must to finish it
+func (m *Watcher) checkTimeouts(ctx context.Context, allPeersStats map[wgtypes.Key]configurer.WGStats) {
+	m.peersMu.Lock()
+	defer m.peersMu.Unlock()
+
+	for p, rxh := range m.peers {
+		s, ok := allPeersStats[p]
+		if !ok {
+			log.Warnf("no stats for peer %s", p)
+		}
+
+		// received bytes since last check
+		received := s.RxBytes - rxh.received
+		if received >= expectedMinimumRx {
+			rxh.received = s.RxBytes
+			continue
+		}
+
+		// todo handle that case when swtich from P2P to Relay and the endpoint has been reseted.
+
+		// peer timed out
+		delete(m.peers, p)
+
+		select {
+		case <-ctx.Done():
+			return
+		case m.PeerTimedOutChan <- p:
+		}
+	}
+}