Use TCP KeepAlive to detect dead peers and maintain NAT entries.

tcp.go

@@ -43,19 +43,22 @@ func tcpLocal(addr, server string, ciph core.StreamConnCipher, getAddr func(net.
 
 		go func() {
 			defer c.Close()
+			c.(*net.TCPConn).SetKeepAlive(true)
 
 			tgt, err := getAddr(c)
 			if err != nil {
 				logf("failed to get target address: %v", err)
 				return
 			}
 
-			rc, err := core.Dial("tcp", server, ciph)
+			rc, err := net.Dial("tcp", server)
 			if err != nil {
 				logf("failed to connect to server %v: %v", server, err)
 				return
 			}
 			defer rc.Close()
+			rc.(*net.TCPConn).SetKeepAlive(true)
+			rc = ciph.StreamConn(rc)
 
 			if _, err = rc.Write(tgt); err != nil {
 				logf("failed to send target address: %v", err)
@@ -76,7 +79,7 @@ func tcpLocal(addr, server string, ciph core.StreamConnCipher, getAddr func(net.
 
 // Listen on addr for incoming connections.
 func tcpRemote(addr string, ciph core.StreamConnCipher) {
-	l, err := core.Listen("tcp", addr, ciph)
+	l, err := net.Listen("tcp", addr)
 	if err != nil {
 		logf("failed to listen on %s: %v", addr, err)
 		return
@@ -92,6 +95,8 @@ func tcpRemote(addr string, ciph core.StreamConnCipher) {
 
 		go func() {
 			defer c.Close()
+			c.(*net.TCPConn).SetKeepAlive(true)
+			c = ciph.StreamConn(c)
 
 			tgt, err := socks.ReadAddr(c)
 			if err != nil {
@@ -105,6 +110,7 @@ func tcpRemote(addr string, ciph core.StreamConnCipher) {
 				return
 			}
 			defer rc.Close()
+			rc.(*net.TCPConn).SetKeepAlive(true)
 
 			logf("proxy %s <-> %s", c.RemoteAddr(), tgt)
 			_, _, err = relay(c, rc)