client handler: allow to set/get application specific data

client_handler.go

@@ -106,6 +106,7 @@ type clientHandler struct {
 	isTransferOpen      bool            // indicate if the transfer connection is opened
 	isTransferAborted   bool            // indicate if the transfer was aborted
 	tlsRequirement      TLSRequirement  // TLS requirement to respect
+	extra               any             // Additional application-specific data
 	paramsMutex         sync.RWMutex    // mutex to protect the parameters exposed to the library users
 }
 
@@ -245,6 +246,14 @@ func (c *clientHandler) HasTLSForTransfers() bool {
 	return c.transferTLS
 }
 
+func (c *clientHandler) SetExtra(extra any) {
+	c.extra = extra
+}
+
+func (c *clientHandler) Extra() any {
+	return c.extra
+}
+
 func (c *clientHandler) setTLSForTransfer(value bool) {
 	c.paramsMutex.Lock()
 	defer c.paramsMutex.Unlock()

client_handler_test.go

@@ -456,3 +456,36 @@ func TestDataConnectionRequirements(t *testing.T) {
 		assert.Contains(t, err.Error(), "unhandled data connection requirement")
 	}
 }
+
+func TestExtraData(t *testing.T) {
+	driver := &TestServerDriver{
+		Debug: false,
+	}
+	s := NewTestServerWithDriver(t, driver)
+
+	conf := goftp.Config{
+		User:     authUser,
+		Password: authPass,
+	}
+
+	c, err := goftp.DialConfig(conf, s.Addr())
+	require.NoError(t, err, "Couldn't connect")
+
+	defer func() { panicOnError(c.Close()) }()
+
+	raw, err := c.OpenRawConn()
+	require.NoError(t, err)
+
+	defer func() { require.NoError(t, raw.Close()) }()
+
+	info := driver.GetClientsInfo()
+	require.Len(t, info, 1)
+
+	for k, v := range info {
+		ccInfo, ok := v.(map[string]interface{})
+		require.True(t, ok)
+		extra, ok := ccInfo["extra"].(uint32)
+		require.True(t, ok)
+		require.Equal(t, k, extra)
+	}
+}

driver.go

@@ -188,6 +188,12 @@ type ClientContext interface {
 	// If you want to enforce the same requirement for all
 	// clients, use the TLSRequired parameter defined in server settings instead
 	SetTLSRequirement(requirement TLSRequirement) error
+
+	// SetExtra allows to set application specific data
+	SetExtra(extra any)
+
+	// Extra returns application specific data set using SetExtra
+	Extra() any
 }
 
 // FileTransfer defines the inferface for file transfers.

driver_test.go

@@ -214,6 +214,8 @@ func (driver *TestServerDriver) ClientConnected(cc ClientContext) (string, error
 	}
 
 	cc.SetDebug(driver.Debug)
+	// we set the client id as extra data just for testing
+	cc.SetExtra(cc.ID())
 	driver.Clients = append(driver.Clients, cc)
 	// This will remain the official name for now
 	return "TEST Server", err
@@ -267,6 +269,7 @@ func (driver *TestServerDriver) GetClientsInfo() map[uint32]interface{} {
 		ccInfo["hasTLSForTransfers"] = cc.HasTLSForTransfers()
 		ccInfo["lastCommand"] = cc.GetLastCommand()
 		ccInfo["debug"] = cc.Debug()
+		ccInfo["extra"] = cc.Extra()
 
 		info[cc.ID()] = ccInfo
 	}