/
server.go
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/
server.go
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package ftpd
import (
"crypto/tls"
"errors"
"fmt"
"io/ioutil"
"net"
"path/filepath"
ftpserver "github.com/fclairamb/ftpserverlib"
"github.com/drakkan/sftpgo/common"
"github.com/drakkan/sftpgo/dataprovider"
"github.com/drakkan/sftpgo/logger"
"github.com/drakkan/sftpgo/metrics"
"github.com/drakkan/sftpgo/utils"
"github.com/drakkan/sftpgo/version"
)
// Server implements the ftpserverlib MainDriver interface
type Server struct {
config *Configuration
certMgr *common.CertManager
initialMsg string
statusBanner string
}
// NewServer returns a new FTP server driver
func NewServer(config *Configuration, configDir string) (*Server, error) {
var err error
server := &Server{
config: config,
certMgr: nil,
initialMsg: config.Banner,
statusBanner: fmt.Sprintf("SFTPGo %v FTP Server", version.Get().Version),
}
certificateFile := getConfigPath(config.CertificateFile, configDir)
certificateKeyFile := getConfigPath(config.CertificateKeyFile, configDir)
if len(certificateFile) > 0 && len(certificateKeyFile) > 0 {
server.certMgr, err = common.NewCertManager(certificateFile, certificateKeyFile, logSender)
if err != nil {
return server, err
}
}
if len(config.BannerFile) > 0 {
bannerFilePath := config.BannerFile
if !filepath.IsAbs(bannerFilePath) {
bannerFilePath = filepath.Join(configDir, bannerFilePath)
}
bannerContent, err := ioutil.ReadFile(bannerFilePath)
if err == nil {
server.initialMsg = string(bannerContent)
} else {
logger.WarnToConsole("unable to read FTPD banner file: %v", err)
logger.Warn(logSender, "", "unable to read banner file: %v", err)
}
}
return server, err
}
// GetSettings returns FTP server settings
func (s *Server) GetSettings() (*ftpserver.Settings, error) {
var portRange *ftpserver.PortRange
if s.config.PassivePortRange.Start > 0 && s.config.PassivePortRange.End > s.config.PassivePortRange.Start {
portRange = &ftpserver.PortRange{
Start: s.config.PassivePortRange.Start,
End: s.config.PassivePortRange.End,
}
}
var ftpListener net.Listener
if common.Config.ProxyProtocol > 0 {
listener, err := net.Listen("tcp", fmt.Sprintf("%s:%d", s.config.BindAddress, s.config.BindPort))
if err != nil {
logger.Warn(logSender, "", "error starting listener on address %s:%d: %v", s.config.BindAddress, s.config.BindPort, err)
return nil, err
}
ftpListener, err = common.Config.GetProxyListener(listener)
if err != nil {
logger.Warn(logSender, "", "error enabling proxy listener: %v", err)
return nil, err
}
}
return &ftpserver.Settings{
Listener: ftpListener,
ListenAddr: fmt.Sprintf("%s:%d", s.config.BindAddress, s.config.BindPort),
PublicHost: s.config.ForcePassiveIP,
PassiveTransferPortRange: portRange,
ActiveTransferPortNon20: s.config.ActiveTransfersPortNon20,
IdleTimeout: -1,
ConnectionTimeout: 20,
Banner: s.statusBanner,
TLSRequired: s.config.TLSMode,
}, nil
}
// ClientConnected is called to send the very first welcome message
func (s *Server) ClientConnected(cc ftpserver.ClientContext) (string, error) {
if err := common.Config.ExecutePostConnectHook(cc.RemoteAddr().String(), common.ProtocolFTP); err != nil {
return common.ErrConnectionDenied.Error(), err
}
connID := fmt.Sprintf("%v", cc.ID())
user := dataprovider.User{}
connection := &Connection{
BaseConnection: common.NewBaseConnection(connID, common.ProtocolFTP, user, nil),
clientContext: cc,
}
common.Connections.Add(connection)
return s.initialMsg, nil
}
// ClientDisconnected is called when the user disconnects, even if he never authenticated
func (s *Server) ClientDisconnected(cc ftpserver.ClientContext) {
connID := fmt.Sprintf("%v_%v", common.ProtocolFTP, cc.ID())
common.Connections.Remove(connID)
}
// AuthUser authenticates the user and selects an handling driver
func (s *Server) AuthUser(cc ftpserver.ClientContext, username, password string) (ftpserver.ClientDriver, error) {
remoteAddr := cc.RemoteAddr().String()
user, err := dataprovider.CheckUserAndPass(username, password, utils.GetIPFromRemoteAddress(remoteAddr), common.ProtocolFTP)
if err != nil {
updateLoginMetrics(username, remoteAddr, err)
return nil, err
}
connection, err := s.validateUser(user, cc)
defer updateLoginMetrics(username, remoteAddr, err)
if err != nil {
return nil, err
}
connection.Fs.CheckRootPath(connection.GetUsername(), user.GetUID(), user.GetGID())
connection.Log(logger.LevelInfo, "User id: %d, logged in with FTP, username: %#v, home_dir: %#v remote addr: %#v",
user.ID, user.Username, user.HomeDir, remoteAddr)
dataprovider.UpdateLastLogin(user) //nolint:errcheck
return connection, nil
}
// GetTLSConfig returns a TLS Certificate to use
func (s *Server) GetTLSConfig() (*tls.Config, error) {
if s.certMgr != nil {
return &tls.Config{
GetCertificate: s.certMgr.GetCertificateFunc(),
MinVersion: tls.VersionTLS12,
}, nil
}
return nil, errors.New("no TLS certificate configured")
}
func (s *Server) validateUser(user dataprovider.User, cc ftpserver.ClientContext) (*Connection, error) {
connectionID := fmt.Sprintf("%v_%v", common.ProtocolFTP, cc.ID())
if !filepath.IsAbs(user.HomeDir) {
logger.Warn(logSender, connectionID, "user %#v has an invalid home dir: %#v. Home dir must be an absolute path, login not allowed",
user.Username, user.HomeDir)
return nil, fmt.Errorf("cannot login user with invalid home dir: %#v", user.HomeDir)
}
if utils.IsStringInSlice(common.ProtocolFTP, user.Filters.DeniedProtocols) {
logger.Debug(logSender, connectionID, "cannot login user %#v, protocol FTP is not allowed", user.Username)
return nil, fmt.Errorf("Protocol FTP is not allowed for user %#v", user.Username)
}
if !user.IsLoginMethodAllowed(dataprovider.LoginMethodPassword, nil) {
logger.Debug(logSender, connectionID, "cannot login user %#v, password login method is not allowed", user.Username)
return nil, fmt.Errorf("Password login method is not allowed for user %#v", user.Username)
}
if user.MaxSessions > 0 {
activeSessions := common.Connections.GetActiveSessions(user.Username)
if activeSessions >= user.MaxSessions {
logger.Debug(logSender, connectionID, "authentication refused for user: %#v, too many open sessions: %v/%v", user.Username,
activeSessions, user.MaxSessions)
return nil, fmt.Errorf("too many open sessions: %v", activeSessions)
}
}
if dataprovider.GetQuotaTracking() > 0 && user.HasOverlappedMappedPaths() {
logger.Debug(logSender, connectionID, "cannot login user %#v, overlapping mapped folders are allowed only with quota tracking disabled",
user.Username)
return nil, errors.New("overlapping mapped folders are allowed only with quota tracking disabled")
}
remoteAddr := cc.RemoteAddr().String()
if !user.IsLoginFromAddrAllowed(remoteAddr) {
logger.Debug(logSender, connectionID, "cannot login user %#v, remote address is not allowed: %v", user.Username, remoteAddr)
return nil, fmt.Errorf("Login for user %#v is not allowed from this address: %v", user.Username, remoteAddr)
}
fs, err := user.GetFilesystem(connectionID)
if err != nil {
return nil, err
}
connection := &Connection{
BaseConnection: common.NewBaseConnection(fmt.Sprintf("%v", cc.ID()), common.ProtocolFTP, user, fs),
clientContext: cc,
}
err = common.Connections.Swap(connection)
if err != nil {
return nil, errors.New("Internal authentication error")
}
return connection, nil
}
func updateLoginMetrics(username, remoteAddress string, err error) {
metrics.AddLoginAttempt(dataprovider.LoginMethodPassword)
ip := utils.GetIPFromRemoteAddress(remoteAddress)
if err != nil {
logger.ConnectionFailedLog(username, ip, dataprovider.LoginMethodPassword,
common.ProtocolFTP, err.Error())
}
metrics.AddLoginResult(dataprovider.LoginMethodPassword, err)
dataprovider.ExecutePostLoginHook(username, dataprovider.LoginMethodPassword, ip, common.ProtocolFTP, err)
}