Connection keepalive/disconnect

xsnet/consts.go

@@ -52,6 +52,7 @@ const (
 	CSEKEXAlgDenied    // server rejected proposed KEX alg
 	CSECipherAlgDenied // server rejected proposed Cipher alg
 	CSEHMACAlgDenied   // server rejected proposed HMAC alg
+	CSEConnDead        // connection keepalives expired
 )
 
 // Extended (>255 UNIX exit status) codes
@@ -78,6 +79,7 @@ const (
 	CSOTunKeepAlive // client tunnel heartbeat
 	CSOTunDisconn   // server -> client: tunnel rport disconnected
 	CSOTunHangup    // client -> server: tunnel lport hung up
+	CSOKeepAlive    // bidir keepalive packet to monitor main connection
 )
 
 // TunEndpoint.tunCtl control values - used to control workers for client
@@ -97,7 +99,7 @@ const (
 // Channel status Op byte type (see CSONone, ... and CSENone, ...)
 type CSOType uint32
 
-//TODO: this should be small (max unfragmented packet size?)
+// TODO: this should be small (max unfragmented packet size?)
 const MAX_PAYLOAD_LEN = 2*1024*1024*1024 - 1
 
 // Session symmetric crypto algs

xsnet/net.go

@@ -64,7 +64,6 @@ type (
 	// see: https://en.wikipedia.org/wiki/chaff_(countermeasure)
 	ChaffConfig struct {
 		shutdown bool //set to inform chaffHelper to shut down
-		enabled  bool
 		msecsMin uint //msecs min interval
 		msecsMax uint //msecs max interval
 		szMax    uint // max size in bytes
@@ -87,8 +86,9 @@ type (
 		Rows       uint16
 		Cols       uint16
 
-		chaff ChaffConfig
-		tuns  *map[uint16](*TunEndpoint)
+		keepalive uint // if this reaches zero, conn is considered dead
+		chaff     ChaffConfig
+		tuns      *map[uint16](*TunEndpoint)
 
 		closeStat *CSOType      // close status (CSOExitStatus)
 		r         cipher.Stream //read cipherStream
@@ -971,7 +971,7 @@ func Dial(protocol string, ipport string, extensions ...string) (hc Conn, err er
 
 // Close a hkex.Conn
 func (hc *Conn) Close() (err error) {
-	hc.DisableChaff()
+	hc.ShutdownChaff()
 	s := make([]byte, 4)
 	binary.BigEndian.PutUint32(s, uint32(*hc.closeStat))
 	log.Printf("** Writing closeStat %d at Close()\n", *hc.closeStat)
@@ -1337,6 +1337,9 @@ func (hc Conn) Read(b []byte) (n int, err error) {
 			case CSOChaff:
 				// Throw away pkt if it's chaff (ie., caller to Read() won't see this data)
 				log.Printf("[Chaff pkt, discarded (len %d)]\n", decryptN)
+			case CSOKeepAlive:
+				//log.Printf("[KeepAlive pkt, discarded (len %d)]\n", decryptN)
+				hc.ResetKeepAlive()
 			case CSOTermSize:
 				fmt.Sscanf(string(payloadBytes), "%d %d", &hc.Rows, &hc.Cols)
 				log.Printf("[TermSize pkt: rows %v cols %v]\n", hc.Rows, hc.Cols)
@@ -1568,18 +1571,12 @@ func (hc *Conn) WritePacket(b []byte, ctrlStatOp byte) (n int, err error) {
 	return retN, err
 }
 
-func (hc *Conn) EnableChaff() {
+func (hc *Conn) StartupChaff() {
 	hc.chaff.shutdown = false
-	hc.chaff.enabled = true
 	log.Println("Chaffing ENABLED")
 	hc.chaffHelper()
 }
 
-func (hc *Conn) DisableChaff() {
-	hc.chaff.enabled = false
-	log.Println("Chaffing DISABLED")
-}
-
 func (hc *Conn) ShutdownChaff() {
 	hc.chaff.shutdown = true
 	log.Println("Chaffing SHUTDOWN")
@@ -1594,9 +1591,10 @@ func (hc *Conn) SetupChaff(msecsMin uint, msecsMax uint, szMax uint) {
 // Helper routine to spawn a chaffing goroutine for each Conn
 func (hc *Conn) chaffHelper() {
 	go func() {
+		var nextDuration int
 		for {
-			var nextDuration int
-			if hc.chaff.enabled {
+			//logger.LogDebug(fmt.Sprintf("[chaffHelper Loop]\n"))
+			if !hc.chaff.shutdown {
 				var bufTmp []byte
 				bufTmp = make([]byte, rand.Intn(int(hc.chaff.szMax)))
 				min := int(hc.chaff.msecsMin)
@@ -1604,17 +1602,60 @@ func (hc *Conn) chaffHelper() {
 				_, _ = rand.Read(bufTmp)
 				_, err := hc.WritePacket(bufTmp, CSOChaff)
 				if err != nil {
-					log.Println("[ *** error - chaffHelper quitting *** ]")
-					hc.chaff.enabled = false
+					log.Println("[ *** error - chaffHelper shutting down *** ]")
+					hc.chaff.shutdown = true
 					break
 				}
-			}
-			time.Sleep(time.Duration(nextDuration) * time.Millisecond)
-			if hc.chaff.shutdown {
-				log.Println("*** chaffHelper shutting down")
+			} else {
+				log.Println("[ *** chaffHelper shutting down *** ]")
+				break
+			}
+			time.Sleep(time.Duration(nextDuration) * time.Millisecond)
+		}
+	}()
+}
+
+func (hc *Conn) StartupKeepAlive() {
+	hc.ResetKeepAlive()
+	log.Println("KeepAlive ENABLED")
+	hc.keepaliveHelper()
+}
+
+func (hc *Conn) ShutdownKeepAlive() {
+	log.Println("Conn SHUTDOWN")
+	hc.SetStatus(CSEConnDead)
+	hc.Close()
+}
+
+func (hc *Conn) ResetKeepAlive() {
+	hc.keepalive = 3
+	log.Println("KeepAlive RESET")
+}
+
+// Helper routine to spawn a keepalive goroutine for each Conn
+func (hc *Conn) keepaliveHelper() {
+	go func() {
+		for {
+			nextDuration := 10000
+			bufTmp := []byte{0x55, 0xaa}
+			_, err := hc.WritePacket(bufTmp, CSOKeepAlive)
+			//logger.LogDebug(fmt.Sprintf("[keepalive]\n"))
+			if err != nil {
+				logger.LogDebug(fmt.Sprintf("[ *** error - keepaliveHelper quitting *** ]\n"))
+				break
+			}
+			time.Sleep(time.Duration(nextDuration) * time.Millisecond)
+			hc.keepalive -= 1
+
+			//if rand.Intn(32) == 0 {
+			//	hc.keepalive = 0
+			//}
+
+			if hc.keepalive == 0 {
+				logger.LogDebug(fmt.Sprintf("*** keepaliveHelper shutting down\n"))
+				hc.ShutdownKeepAlive()
 				break
 			}
-
 		}
 	}()
 }