add TCPConn type

tcp/definitions.go

@@ -16,7 +16,7 @@ var (
 	errDropSegment    = errors.New("drop segment")
 	errWindowTooLarge = errors.New("invalid window size > 2**16")
 
-	errBufferTooSmall        = errors.New("buffer too small")
+	errBufferTooSmall        = errors.New("tcp buffer too small")
 	errNeedClosedTCBToOpen   = errors.New("need closed TCB to call open")
 	errInvalidState          = errors.New("invalid state")
 	errConnNotExist          = errors.New("connection does not exist")

tcp/handler.go

@@ -73,12 +73,14 @@ func (h *Handler) OpenActive(localPort, remotePort uint16, iss Value) error {
 	}
 	if h.scb.State() != StateClosed {
 		return errNeedClosedTCBToOpen
+	} else if remotePort == 0 {
+		return errors.New("zero port on open call")
 	}
 	h.reset(localPort, remotePort, iss)
 	return nil
 }
 
-// OpenListen prepares a passive connection. Set remote port to non-zero to
+// OpenListen prepares a passive connection.
 func (h *Handler) OpenListen(localPort uint16, iss Value) error {
 	if h.bufRx.Size() < minBufferSize || h.bufTx.Size() < minBufferSize {
 		return errBufferTooSmall
@@ -230,7 +232,8 @@ func (h *Handler) Read(b []byte) (int, error) {
 	return h.bufRx.Read(b)
 }
 
-func (h *Handler) Buffered() int {
+// BufferedInput returns amount of bytes buffered in receive buffer.
+func (h *Handler) BufferedInput() int {
 	if h.State().IsClosed() {
 		return 0
 	}

tcp/handler_test.go

@@ -33,8 +33,8 @@ func sendDataFull(t *testing.T, client, server *Handler, data, packetBuf []byte)
 	err = server.Recv(packetBuf[:n])
 	if err != nil {
 		t.Fatal("server receiving:", err)
-	} else if server.Buffered() != len(data) {
-		t.Fatal("server did not receive full data packet", server.Buffered(), len(data))
+	} else if server.BufferedInput() != len(data) {
+		t.Fatal("server did not receive full data packet", server.BufferedInput(), len(data))
 	}
 	clear(packetBuf)
 	n, err = server.Read(packetBuf)