Added locking APIs for most Conn/Tun fields, save <- Data/ShutdownTun() race

Signed-off-by: Russ Magee <rmagee@gmail.com>

hkexnet/hkexnet.go

@@ -122,6 +122,14 @@ func Init(d bool, c string, f logger.Priority) {
 	_initLogging(d, c, f)
 }
 
+func (hc *Conn) Lock() {
+		hc.m.Lock()
+}
+
+func (hc *Conn) Unlock() {
+		hc.m.Unlock()
+}
+
 func (hc Conn) GetStatus() CSOType {
 	return *hc.closeStat
 }
@@ -1084,7 +1092,7 @@ func (hc Conn) Read(b []byte) (n int, err error) {
 				rport := binary.BigEndian.Uint16(payloadBytes[2:4])
 				logger.LogDebug(fmt.Sprintf("[Client] Got CSOTunRefused [%d:%d]", lport, rport))
 				if _, ok := (*hc.tuns)[rport]; ok {
-					(*hc.tuns)[rport].Died = true
+					hc.MarkTunDead(rport)
 				} else {
 					logger.LogDebug(fmt.Sprintf("[Client] CSOTunRefused on already-closed tun [%d:%d]", lport, rport))
 				}
@@ -1094,7 +1102,7 @@ func (hc Conn) Read(b []byte) (n int, err error) {
 				rport := binary.BigEndian.Uint16(payloadBytes[2:4])
 				logger.LogDebug(fmt.Sprintf("[Client] Got CSOTunDisconn [%d:%d]", lport, rport))
 				if _, ok := (*hc.tuns)[rport]; ok {
-					(*hc.tuns)[rport].Died = true
+					hc.MarkTunDead(rport)
 				} else {
 					logger.LogDebug(fmt.Sprintf("[Client] CSOTunDisconn on already-closed tun [%d:%d]", lport, rport))
 				}
@@ -1104,7 +1112,7 @@ func (hc Conn) Read(b []byte) (n int, err error) {
 				rport := binary.BigEndian.Uint16(payloadBytes[2:4])
 				logger.LogDebug(fmt.Sprintf("[Server] Got CSOTunHangup [%d:%d]", lport, rport))
 				if _, ok := (*hc.tuns)[rport]; ok {
-					(*hc.tuns)[rport].Died = true
+					hc.MarkTunDead(rport)
 				} else {
 					logger.LogDebug(fmt.Sprintf("[Server] CSOTunHangup to already-closed tun [%d:%d]", lport, rport))
 				}
@@ -1117,7 +1125,7 @@ func (hc Conn) Read(b []byte) (n int, err error) {
 						logger.LogDebug(fmt.Sprintf("[Writing data to rport [%d:%d]", lport, rport))
 					}
 					(*hc.tuns)[rport].Data <- payloadBytes[4:]
-					(*hc.tuns)[rport].KeepAlive = 0
+					hc.ResetTunnelAge(rport)
 				} else {
 					logger.LogDebug(fmt.Sprintf("[Attempt to write data to closed tun [%d:%d]", lport, rport))
 				}
@@ -1212,7 +1220,7 @@ func (hc *Conn) WritePacket(b []byte, ctrlStatOp byte) (n int, err error) {
 	//
 	// Would be nice to determine if the mutex scope
 	// could be tightened.
-	hc.m.Lock()
+	hc.Lock()
 	payloadLen = uint32(len(b))
 	//!fmt.Printf("  --== payloadLen:%d\n", payloadLen)
 	if hc.logPlainText {
@@ -1254,7 +1262,7 @@ func (hc *Conn) WritePacket(b []byte, ctrlStatOp byte) (n int, err error) {
 	} else {
 		//fmt.Println("[a]WriteError!")
 	}
-	hc.m.Unlock()
+	hc.Unlock()
 
 	if err != nil {
 		log.Println(err)

hkexnet/hkextun.go

@@ -16,6 +16,7 @@ import (
 	"net"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"blitter.com/go/hkexsh/logger"
@@ -46,7 +47,7 @@ type (
 		Lport     uint16    // ... ie., RPort is on server, LPort is on client
 		Peer      string    //net.Addr
 		Died      bool      // set by client upon receipt of a CSOTunDisconn
-		KeepAlive uint      // must be reset by client to keep server dial() alive
+		KeepAlive uint32    // must be reset by client to keep server dial() alive
 		Ctl       chan rune //See TunCtl_* consts
 		Data      chan []byte
 	}
@@ -67,6 +68,8 @@ func (hc *Conn) CollapseAllTunnels(client bool) {
 }
 
 func (hc *Conn) InitTunEndpoint(lp uint16, p string /* net.Addr */, rp uint16) {
+	hc.Lock()
+	defer hc.Unlock()
 	if (*hc.tuns) == nil {
 		(*hc.tuns) = make(map[uint16]*TunEndpoint)
 	}
@@ -87,6 +90,7 @@ func (hc *Conn) InitTunEndpoint(lp uint16, p string /* net.Addr */, rp uint16) {
 			// data channel removed on closure. Re-create it
 			(*hc.tuns)[rp].Data = make(chan []byte, 1)
 		}
+		(*hc.tuns)[rp].KeepAlive = 0
 		(*hc.tuns)[rp].Died = false
 	}
 	return
@@ -149,37 +153,23 @@ func (hc *Conn) StartClientTunnel(lport, rport uint16) {
 										if e == io.EOF {
 											logger.LogDebug(fmt.Sprintf("[ClientTun] worker A: lport Disconnected: shutting down tunnel %v", (*hc.tuns)[rport]))
 											// if Died was already set, server-side already is gone.
-											if !(*hc.tuns)[rport].Died {
+											if hc.TunIsAlive(rport) {
 												hc.WritePacket(tunDst.Bytes(), CSOTunHangup)
 											}
-											(*hc.tuns)[rport].Died = true
+											hc.ShutdownTun(rport)
-											if (*hc.tuns)[rport].Data != nil {
-												close((*hc.tuns)[rport].Data)
-												(*hc.tuns)[rport].Data = nil
-											}
-											delete((*hc.tuns), rport)
 											break
 										} else if strings.Contains(e.Error(), "i/o timeout") {
-											if (*hc.tuns)[rport].Died {
+											if !hc.TunIsAlive(rport) {
 												logger.LogDebug(fmt.Sprintf("[ClientTun] worker A: timeout: Server side died, hanging up %v", (*hc.tuns)[rport]))
-												if (*hc.tuns)[rport].Data != nil {
+												hc.ShutdownTun(rport)
-													close((*hc.tuns)[rport].Data)
-													(*hc.tuns)[rport].Data = nil
-												}
-												delete((*hc.tuns), rport)
 												break
 											}
 										} else {
 											logger.LogDebug(fmt.Sprintf("[ClientTun] worker A: Read error from lport of tun %v\n%s", (*hc.tuns)[rport], e))
-											if !(*hc.tuns)[rport].Died {
+											if hc.TunIsAlive(rport) {
 												hc.WritePacket(tunDst.Bytes(), CSOTunHangup)
 											}
-											(*hc.tuns)[rport].Died = true
+											hc.ShutdownTun(rport)
-											if (*hc.tuns)[rport].Data != nil {
-												close((*hc.tuns)[rport].Data)
-												(*hc.tuns)[rport].Data = nil
-											}
-											delete((*hc.tuns), rport)
 											break
 										}
 									}
@@ -232,7 +222,7 @@ func (hc *Conn) StartClientTunnel(lport, rport uint16) {
 						// When both workers have exited due to a disconnect or other
 						// condition, it's safe to remove the tunnel descriptor.
 						logger.LogDebug("[ClientTun] workers exited")
-						delete((*hc.tuns), rport)
+						hc.ShutdownTun(rport)
 					} // end for-accept
 				} // end Listen() block
 			}
@@ -240,6 +230,39 @@ func (hc *Conn) StartClientTunnel(lport, rport uint16) {
 	}()
 }
 
+func (hc *Conn) AgeTunnel(endp uint16) uint32 {
+	return atomic.AddUint32(&(*hc.tuns)[endp].KeepAlive, 1)
+}
+
+func (hc *Conn) ResetTunnelAge(endp uint16) {
+	atomic.StoreUint32(&(*hc.tuns)[endp].KeepAlive, 0)
+}
+
+func (hc *Conn) TunIsAlive(endp uint16) bool {
+	hc.Lock()
+	defer hc.Unlock()
+	return !(*hc.tuns)[endp].Died
+}
+
+func (hc *Conn) MarkTunDead(endp uint16) {
+	hc.Lock()
+	defer hc.Unlock()
+	(*hc.tuns)[endp].Died = true
+}
+
+func (hc *Conn) ShutdownTun(endp uint16) {
+	hc.Lock()
+	defer hc.Unlock()
+	if (*hc.tuns)[endp] != nil {
+		(*hc.tuns)[endp].Died = true
+		if (*hc.tuns)[endp].Data != nil {
+			close((*hc.tuns)[endp].Data)
+			(*hc.tuns)[endp].Data = nil
+		}
+	}
+	delete((*hc.tuns), endp)
+}
+
 func (hc *Conn) StartServerTunnel(lport, rport uint16) {
 	hc.InitTunEndpoint(lport, "", rport)
 	var err error
@@ -260,9 +283,9 @@ func (hc *Conn) StartServerTunnel(lport, rport uint16) {
 					logger.LogDebug("[ServerTun] worker A: Client endpoint removed.")
 					break
 				}
-				(*hc.tuns)[rport].KeepAlive += 1
+				age := hc.AgeTunnel(rport)
-				if (*hc.tuns)[rport].KeepAlive > 25 {
+				if age > 25 {
-					(*hc.tuns)[rport].Died = true
+					hc.MarkTunDead(rport)
 					logger.LogDebug("[ServerTun] worker A: Client died, hanging up.")
 					break
 				}
@@ -319,37 +342,23 @@ func (hc *Conn) StartServerTunnel(lport, rport uint16) {
 							if e != nil {
 								if e == io.EOF {
 									logger.LogDebug(fmt.Sprintf("[ServerTun] worker A: rport Disconnected: shutting down tunnel %v", (*hc.tuns)[rport]))
-									if !(*hc.tuns)[rport].Died {
+									if hc.TunIsAlive(rport) {
 										hc.WritePacket(tunDst.Bytes(), CSOTunDisconn)
 									}
-									(*hc.tuns)[rport].Died = true
+									hc.ShutdownTun(rport)
-									if (*hc.tuns)[rport].Data != nil {
-										close((*hc.tuns)[rport].Data)
-										(*hc.tuns)[rport].Data = nil
-									}
-									delete((*hc.tuns), rport)
 									break
 								} else if strings.Contains(e.Error(), "i/o timeout") {
-									if (*hc.tuns)[rport].Died {
+									if !hc.TunIsAlive(rport) {
 											logger.LogDebug(fmt.Sprintf("[ServerTun] worker A: timeout: Server side died, hanging up %v", (*hc.tuns)[rport]))
-										if (*hc.tuns)[rport].Data != nil {
+											hc.ShutdownTun(rport)
-											close((*hc.tuns)[rport].Data)
-											(*hc.tuns)[rport].Data = nil
-										}
-										delete((*hc.tuns), rport)
 										break
 									}
 								} else {
 									logger.LogDebug(fmt.Sprintf("[ServerTun] worker A: Read error from rport of tun %v: %s", (*hc.tuns)[rport], e))
-									if !(*hc.tuns)[rport].Died {
+									if hc.TunIsAlive(rport) {
 										hc.WritePacket(tunDst.Bytes(), CSOTunDisconn)
 									}
-									(*hc.tuns)[rport].Died = true
+									hc.ShutdownTun(rport)
-									if (*hc.tuns)[rport].Data != nil {
-										close((*hc.tuns)[rport].Data)
-										(*hc.tuns)[rport].Data = nil
-									}
-									delete((*hc.tuns), rport)
 									break
 								}
 							}
@@ -357,14 +366,6 @@ func (hc *Conn) StartServerTunnel(lport, rport uint16) {
 								rBuf = append(tunDst.Bytes(), rBuf[:n]...)
 								hc.WritePacket(rBuf[:n+4], CSOTunData)
 							}
-
-							//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")
 					}()
@@ -382,7 +383,7 @@ func (hc *Conn) StartServerTunnel(lport, rport uint16) {
 
 						logger.LogDebug("[ServerTun] worker B: starting")
 						for {
-							rData, ok := <-(*hc.tuns)[rport].Data
+							rData, ok := <-(*hc.tuns)[rport].Data // FIXME: race w/ShutdownTun() calls
 							if ok {
 								c.SetWriteDeadline(time.Now().Add(200 * time.Millisecond))
 								_, e := c.Write(rData)