From 1d4c16dd766bdec3dd4a3a8b78a7f8a3f51c1433 Mon Sep 17 00:00:00 2001
From: Russ Magee <rmagee@gmail.com>
Date: Sat, 22 Jun 2019 00:44:23 -0700
Subject: [PATCH] Moved server keepalive ageing for tunnels to goroutine -- fix
 for premature tunnel collapses

---
 hkexnet/hkexnet.go | 10 +++++++---
 hkexnet/hkextun.go | 30 ++++++++++++++++++++++++------
 2 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/hkexnet/hkexnet.go b/hkexnet/hkexnet.go
index 66c2adb..21da20f 100644
--- a/hkexnet/hkexnet.go
+++ b/hkexnet/hkexnet.go
@@ -75,8 +75,9 @@ type (
 		c        *net.Conn   // which also implements io.Reader, io.Writer, ...
 		immClose bool
 
-		logCipherText bool // somewhat expensive, for debugging
-		logPlainText  bool // INSECURE and somewhat expensive, for debugging
+		logCipherText  bool // somewhat expensive, for debugging
+		logPlainText   bool // INSECURE and somewhat expensive, for debugging
+		logTunActivity bool
 
 		cipheropts uint32 // post-KEx cipher/hmac options
 		opts       uint32 // post-KEx protocol options (caller-defined)
@@ -1112,8 +1113,11 @@ func (hc Conn) Read(b []byte) (n int, err error) {
 				rport := binary.BigEndian.Uint16(payloadBytes[2:4])
 				//fmt.Printf("[Got CSOTunData: [lport %d:rport %d] data:%v\n", lport, rport, payloadBytes[4:])
 				if _, ok := (*hc.tuns)[rport]; ok {
-					logger.LogDebug(fmt.Sprintf("[Writing data to rport [%d:%d]", lport, rport))
+					if hc.logTunActivity {
+						logger.LogDebug(fmt.Sprintf("[Writing data to rport [%d:%d]", lport, rport))
+					}
 					(*hc.tuns)[rport].Data <- payloadBytes[4:]
+					(*hc.tuns)[rport].KeepAlive = 0
 				} else {
 					logger.LogDebug(fmt.Sprintf("[Attempt to write data to closed tun [%d:%d]", lport, rport))
 				}
diff --git a/hkexnet/hkextun.go b/hkexnet/hkextun.go
index da22882..6503c3f 100644
--- a/hkexnet/hkextun.go
+++ b/hkexnet/hkextun.go
@@ -244,6 +244,24 @@ func (hc *Conn) StartServerTunnel(lport, rport uint16) {
 	go func() {
 		var wg sync.WaitGroup
 
+		//
+		// worker to age server tunnel and kill it if keepalives
+		// stop from client
+		//
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for {
+				time.Sleep(100 * time.Millisecond)
+				(*hc.tuns)[rport].KeepAlive += 1
+				if (*hc.tuns)[rport].KeepAlive > 25 {
+					(*hc.tuns)[rport].Died = true
+					logger.LogDebug("[ServerTun] worker A: Client died, hanging up.")
+					break
+				}
+			}
+		}()
+
 		for cmd := range (*hc.tuns)[rport].Ctl {
 			var c net.Conn
 			logger.LogDebug(fmt.Sprintf("[ServerTun] got Ctl '%c'.", cmd))
@@ -330,12 +348,12 @@ func (hc *Conn) StartServerTunnel(lport, rport uint16) {
 								hc.WritePacket(rBuf[:n+4], CSOTunData)
 							}
 
-							if (*hc.tuns)[rport].KeepAlive > 50 {
-								(*hc.tuns)[rport].Died = true
-								logger.LogDebug("[ServerTun] worker A: Client died, hanging up.")
-							} else {
-								(*hc.tuns)[rport].KeepAlive += 1
-							}
+							//if (*hc.tuns)[rport].KeepAlive > 50000 {
+							//	(*hc.tuns)[rport].Died = true
+							//	logger.LogDebug("[ServerTun] worker A: Client died, hanging up.")
+							//} else {
+							//	(*hc.tuns)[rport].KeepAlive += 1
+							//}
 
 						}
 						logger.LogDebug("[ServerTun] worker A: exiting")