Adding MODE support (#460)

We're only accepting the "Stream" mode though. But at least it's official.

This addresses #451.

handle_misc.go

@@ -283,6 +283,16 @@ func (c *clientHandler) handleTYPE(param string) error {
 	return nil
 }
 
+func (c *clientHandler) handleMODE(param string) error {
+	if param == "S" {
+		c.writeMessage(StatusOK, "Using stream mode")
+	} else {
+		c.writeMessage(StatusNotImplementedParam, "Unsupported mode")
+	}
+
+	return nil
+}
+
 func (c *clientHandler) handleQUIT(_ string) error {
 	c.transferWg.Wait()
 

handle_misc_test.go

@@ -418,3 +418,27 @@ func TestTYPE(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, StatusNotImplementedParam, returnCode)
 }
+
+func TestMode(t *testing.T) {
+	server := NewTestServer(t, false)
+	conf := goftp.Config{
+		User:     authUser,
+		Password: authPass,
+	}
+
+	client, err := goftp.DialConfig(conf, server.Addr())
+	require.NoError(t, err, "Couldn't connect")
+
+	defer func() { panicOnError(client.Close()) }()
+
+	raw, err := client.OpenRawConn()
+	require.NoError(t, err, "Couldn't open raw connection")
+
+	returnCode, _, err := raw.SendCommand("MODE S")
+	require.NoError(t, err)
+	require.Equal(t, StatusOK, returnCode)
+
+	returnCode, _, err = raw.SendCommand("MODE X")
+	require.NoError(t, err)
+	require.Equal(t, StatusNotImplementedParam, returnCode)
+}

server.go

@@ -87,6 +87,7 @@ var commandsMap = map[string]*CommandDescription{ //nolint:gochecknoglobals
 
 	// Connection handling
 	"TYPE": {Fn: (*clientHandler).handleTYPE},
+	"MODE": {Fn: (*clientHandler).handleMODE},
 	"PASV": {Fn: (*clientHandler).handlePASV},
 	"EPSV": {Fn: (*clientHandler).handlePASV},
 	"PORT": {Fn: (*clientHandler).handlePORT},