Tear down connections on prolonged loss of UDP heartbeat

router/connection.go

@@ -45,6 +45,7 @@ type LocalConnection struct {
 	effectivePMTU      int
 	SessionKey         *[32]byte
 	establishedTimeout *time.Timer
+	heartbeatTimeout   *time.Timer
 	heartbeatFrame     *ForwardedFrame
 	heartbeat          *time.Ticker
 	fragTest           *time.Ticker
@@ -301,10 +302,12 @@ func (conn *LocalConnection) queryLoop(queryChan <-chan *ConnectionInteraction)
 			case CSendProtocolMsg:
 				err = conn.handleSendProtocolMsg(query.payload.(ProtocolMsg))
 			}
-		case <-conn.establishedTimeout.C:
+		case <-timerChan(conn.establishedTimeout):
 			if !conn.established {
 				err = fmt.Errorf("failed to establish UDP connectivity")
 			}
+		case <-timerChan(conn.heartbeatTimeout):
+			err = fmt.Errorf("timed out waiting for UDP heartbeat")
 		case <-tickerChan(conn.heartbeat):
 			conn.Forward(true, conn.heartbeatFrame, nil)
 		case <-tickerChan(conn.fragTest):
@@ -329,6 +332,9 @@ func (conn *LocalConnection) handleReceivedHeartbeat(remoteUDPAddr *net.UDPAddr)
 	conn.remoteUDPAddr = remoteUDPAddr
 	conn.receivedHeartbeat = true
 	conn.Unlock()
+	if conn.established {
+		conn.heartbeatTimeout.Reset(HeartbeatTimeout)
+	}
 	if !old {
 		if err := conn.handleSendSimpleProtocolMsg(ProtocolConnectionEstablished); err != nil {
 			return err
@@ -362,6 +368,7 @@ func (conn *LocalConnection) handleSetEstablished() error {
 		dstPeer: conn.remote,
 		frame:   PMTUDiscovery},
 		nil)
+	conn.heartbeatTimeout = time.NewTimer(HeartbeatTimeout)
 	conn.heartbeat = time.NewTicker(SlowHeartbeat)
 	conn.fragTest = time.NewTicker(FragTestInterval)
 	// avoid initial waits for timers to fire
@@ -391,10 +398,8 @@ func (conn *LocalConnection) handleShutdown() {
 		conn.Router.Ourself.DeleteConnection(conn)
 	}
 
-	if conn.establishedTimeout != nil {
-		conn.establishedTimeout.Stop()
-	}
-
+	stopTimer(conn.establishedTimeout)
+	stopTimer(conn.heartbeatTimeout)
 	stopTicker(conn.heartbeat)
 	stopTicker(conn.fragTest)
 
@@ -498,3 +503,16 @@ func stopTicker(ticker *time.Ticker) {
 		ticker.Stop()
 	}
 }
+
+func timerChan(timer *time.Timer) <-chan time.Time {
+	if timer != nil {
+		return timer.C
+	}
+	return nil
+}
+
+func stopTimer(timer *time.Timer) {
+	if timer != nil {
+		timer.Stop()
+	}
+}

router/consts.go

@@ -6,24 +6,26 @@ import (
 )
 
 const (
-	EthernetOverhead   = 14
-	UDPOverhead        = 28 // 20 bytes for IPv4, 8 bytes for UDP
-	Port               = 6783
-	HttpPort           = Port + 1
-	DefaultPMTU        = 65535
-	MaxUDPPacketSize   = 65536
-	ChannelSize        = 16
-	UDPNonceSendAt     = 8192
-	FragTestSize       = 60001
-	PMTUDiscoverySize  = 60000
-	FastHeartbeat      = 500 * time.Millisecond
-	SlowHeartbeat      = 10 * time.Second
-	FragTestInterval   = 5 * time.Minute
-	EstablishedTimeout = 30 * time.Second
-	ReadTimeout        = 1 * time.Minute
-	PMTUVerifyAttempts = 8
-	PMTUVerifyTimeout  = 10 * time.Millisecond // gets doubled with every attempt
-	MaxDuration        = time.Duration(math.MaxInt64)
+	EthernetOverhead    = 14
+	UDPOverhead         = 28 // 20 bytes for IPv4, 8 bytes for UDP
+	Port                = 6783
+	HttpPort            = Port + 1
+	DefaultPMTU         = 65535
+	MaxUDPPacketSize    = 65536
+	ChannelSize         = 16
+	UDPNonceSendAt      = 8192
+	FragTestSize        = 60001
+	PMTUDiscoverySize   = 60000
+	FastHeartbeat       = 500 * time.Millisecond
+	SlowHeartbeat       = 10 * time.Second
+	FragTestInterval    = 5 * time.Minute
+	EstablishedTimeout  = 30 * time.Second
+	ReadTimeout         = 1 * time.Minute
+	PMTUVerifyAttempts  = 8
+	PMTUVerifyTimeout   = 10 * time.Millisecond // gets doubled with every attempt
+	MaxDuration         = time.Duration(math.MaxInt64)
+	MaxMissedHeartbeats = 3
+	HeartbeatTimeout    = MaxMissedHeartbeats * SlowHeartbeat
 )
 
 var (