From f5a67ad2a7ea32026aa98dec22f16b1593501a80 Mon Sep 17 00:00:00 2001
From: Matt McGee <85582517+mmcgeefeedo@users.noreply.github.com>
Date: Tue, 27 Jul 2021 17:12:05 -0400
Subject: [PATCH] Add data channel (active/passive) information to the
 ClientContext interface (#248)

* GetLastDataChannel returns the last data channel mode (passive or active)

* use the paramsMutex for lastDataChannel updates

* update README.md with GetLastDataChannel update to ClientContext

* convert data channel to enums
---
 README.md              |  3 +++
 client_handler.go      | 25 +++++++++++++++++++++++++
 client_handler_test.go |  5 +++++
 driver.go              |  3 +++
 transfer_active.go     |  1 +
 transfer_pasv.go       |  1 +
 6 files changed, 38 insertions(+)

diff --git a/README.md b/README.md
index 0a5dd380..f4e92413 100644
--- a/README.md
+++ b/README.md
@@ -114,6 +114,9 @@ type ClientContext interface {
 
 	// GetLastCommand returns the last received command
 	GetLastCommand() string
+
+	// GetLastDataChannel returns the last data channel mode
+	GetLastDataChannel() DataChannel
 }
 
 // Settings define all the server settings
diff --git a/client_handler.go b/client_handler.go
index 6710f834..995b8ed9 100644
--- a/client_handler.go
+++ b/client_handler.go
@@ -34,6 +34,15 @@ const (
 	TransferTypeBinary
 )
 
+// DataChannel is the enumerable that represents the data channel (active or passive)
+type DataChannel int
+
+// Supported data channel types
+const (
+	DataChannelPassive DataChannel = iota + 1
+	DataChannelActive
+)
+
 const (
 	maxCommandSize = 4096
 )
@@ -91,6 +100,7 @@ type clientHandler struct {
 	transferWg          sync.WaitGroup  // wait group for command that open a transfer connection
 	transferMu          sync.Mutex      // this mutex will protect the transfer parameters
 	transfer            transferHandler // Transfer connection (passive or active)s
+	lastDataChannel     DataChannel     // Last data channel mode (passive or active)
 	isTransferOpen      bool            // indicate if the transfer connection is opened
 	isTransferAborted   bool            // indicate if the transfer was aborted
 	paramsMutex         sync.RWMutex    // mutex to protect the parameters exposed to the library users
@@ -231,6 +241,14 @@ func (c *clientHandler) GetLastCommand() string {
 	return c.command
 }
 
+// GetLastDataChannel returns the last data channel mode
+func (c *clientHandler) GetLastDataChannel() DataChannel {
+	c.paramsMutex.RLock()
+	defer c.paramsMutex.RUnlock()
+
+	return c.lastDataChannel
+}
+
 func (c *clientHandler) setLastCommand(cmd string) {
 	c.paramsMutex.Lock()
 	defer c.paramsMutex.Unlock()
@@ -238,6 +256,13 @@ func (c *clientHandler) setLastCommand(cmd string) {
 	c.command = cmd
 }
 
+func (c *clientHandler) setLastDataChannel(channel DataChannel) {
+	c.paramsMutex.Lock()
+	defer c.paramsMutex.Unlock()
+
+	c.lastDataChannel = channel
+}
+
 func (c *clientHandler) closeTransfer() error {
 	var err error
 	if c.transfer != nil {
diff --git a/client_handler_test.go b/client_handler_test.go
index e36ce027..f4d746df 100644
--- a/client_handler_test.go
+++ b/client_handler_test.go
@@ -86,6 +86,11 @@ func TestLastCommand(t *testing.T) {
 	assert.Empty(t, cc.GetLastCommand())
 }
 
+func TestLastDataChannel(t *testing.T) {
+	cc := clientHandler{lastDataChannel: DataChannelPassive}
+	assert.Equal(t, DataChannelPassive, cc.GetLastDataChannel())
+}
+
 func TestTransferOpenError(t *testing.T) {
 	s := NewTestServer(t, true)
 	conf := goftp.Config{
diff --git a/driver.go b/driver.go
index 5b9267ce..c1491681 100644
--- a/driver.go
+++ b/driver.go
@@ -147,6 +147,9 @@ type ClientContext interface {
 
 	// GetLastCommand returns the last received command
 	GetLastCommand() string
+
+	// GetLastDataChannel returns the last data channel mode
+	GetLastDataChannel() DataChannel
 }
 
 // FileTransfer defines the inferface for file transfers.
diff --git a/transfer_active.go b/transfer_active.go
index c9cac20a..bc27551d 100644
--- a/transfer_active.go
+++ b/transfer_active.go
@@ -55,6 +55,7 @@ func (c *clientHandler) handlePORT(param string) error {
 	}
 
 	c.transferMu.Unlock()
+	c.setLastDataChannel(DataChannelActive)
 
 	c.writeMessage(StatusOK, command+" command successful")
 
diff --git a/transfer_pasv.go b/transfer_pasv.go
index e9da39b8..4172ad94 100644
--- a/transfer_pasv.go
+++ b/transfer_pasv.go
@@ -184,6 +184,7 @@ func (c *clientHandler) handlePASV(param string) error {
 	c.transferMu.Lock()
 	c.transfer = p
 	c.transferMu.Unlock()
+	c.setLastDataChannel(DataChannelPassive)
 
 	return nil
 }