Merge pull request #413 from awh/373_detect_udp_connectivity_breakage

Tear down connections on prolonged loss of UDP heartbeat.

Closes #373.

router/connection.go

@@ -37,27 +37,27 @@ type RemoteConnection struct {
 type LocalConnection struct {
 	sync.RWMutex
 	RemoteConnection
-	TCPConn            *net.TCPConn
-	tcpSender          TCPSender
-	remoteUDPAddr      *net.UDPAddr
-	receivedHeartbeat  bool
-	stackFrag          bool
-	effectivePMTU      int
-	SessionKey         *[32]byte
-	establishedTimeout *time.Timer
-	heartbeatFrame     *ForwardedFrame
-	heartbeat          *time.Ticker
-	fragTest           *time.Ticker
-	forwardChan        chan<- *ForwardedFrame
-	forwardChanDF      chan<- *ForwardedFrame
-	stopForward        chan<- interface{}
-	stopForwardDF      chan<- interface{}
-	verifyPMTU         chan<- int
-	Decryptor          Decryptor
-	Router             *Router
-	uid                uint64
-	queryChan          chan<- *ConnectionInteraction
-	finished           <-chan struct{} // closed to signal that queryLoop has finished
+	TCPConn           *net.TCPConn
+	tcpSender         TCPSender
+	remoteUDPAddr     *net.UDPAddr
+	receivedHeartbeat bool
+	stackFrag         bool
+	effectivePMTU     int
+	SessionKey        *[32]byte
+	heartbeatTimeout  *time.Timer
+	heartbeatFrame    *ForwardedFrame
+	heartbeat         *time.Ticker
+	fragTest          *time.Ticker
+	forwardChan       chan<- *ForwardedFrame
+	forwardChanDF     chan<- *ForwardedFrame
+	stopForward       chan<- interface{}
+	stopForwardDF     chan<- interface{}
+	verifyPMTU        chan<- int
+	Decryptor         Decryptor
+	Router            *Router
+	uid               uint64
+	queryChan         chan<- *ConnectionInteraction
+	finished          <-chan struct{} // closed to signal that queryLoop has finished
 }
 
 type ConnectionInteraction struct {
@@ -270,7 +270,7 @@ func (conn *LocalConnection) run(queryChan <-chan *ConnectionInteraction, finish
 		}
 	}
 
-	conn.establishedTimeout = time.NewTimer(EstablishedTimeout)
+	conn.heartbeatTimeout = time.NewTimer(HeartbeatTimeout)
 
 	if err := conn.queryLoop(queryChan); err != nil {
 		conn.log("connection shutting down due to error:", err)
@@ -305,15 +305,12 @@ func (conn *LocalConnection) queryLoop(queryChan <-chan *ConnectionInteraction)
 			case CReceivedHeartbeat:
 				err = conn.handleReceivedHeartbeat(query.payload.(*net.UDPAddr))
 			case CSetEstablished:
-				conn.establishedTimeout.Stop()
 				err = conn.handleSetEstablished()
 			case CSendProtocolMsg:
 				err = conn.handleSendProtocolMsg(query.payload.(ProtocolMsg))
 			}
-		case <-conn.establishedTimeout.C:
-			if !conn.established {
-				err = fmt.Errorf("failed to establish UDP connectivity")
-			}
+		case <-conn.heartbeatTimeout.C:
+			err = fmt.Errorf("timed out waiting for UDP heartbeat")
 		case <-tickerChan(conn.heartbeat):
 			conn.Forward(true, conn.heartbeatFrame, nil)
 		case <-tickerChan(conn.fragTest):
@@ -338,6 +335,7 @@ func (conn *LocalConnection) handleReceivedHeartbeat(remoteUDPAddr *net.UDPAddr)
 	conn.remoteUDPAddr = remoteUDPAddr
 	conn.receivedHeartbeat = true
 	conn.Unlock()
+	conn.heartbeatTimeout.Reset(HeartbeatTimeout)
 	if !old {
 		if err := conn.handleSendSimpleProtocolMsg(ProtocolConnectionEstablished); err != nil {
 			return err
@@ -400,8 +398,8 @@ func (conn *LocalConnection) handleShutdown() {
 		conn.Router.Ourself.DeleteConnection(conn)
 	}
 
-	if conn.establishedTimeout != nil {
-		conn.establishedTimeout.Stop()
+	if conn.heartbeatTimeout != nil {
+		conn.heartbeatTimeout.Stop()
 	}
 
 	stopTicker(conn.heartbeat)

router/consts.go

@@ -6,24 +6,25 @@ 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
+	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 (