rclone/vendor/github.com/jlaffaye/ftp/ftp.go

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// Package ftp implements a FTP client as described in RFC 959.
//
// A textproto.Error is returned for errors at the protocol level.
package ftp
import (
"bufio"
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"context"
"crypto/tls"
"errors"
"io"
"net"
"net/textproto"
"strconv"
"strings"
"time"
)
// EntryType describes the different types of an Entry.
type EntryType int
// The differents types of an Entry
const (
EntryTypeFile EntryType = iota
EntryTypeFolder
EntryTypeLink
)
// ServerConn represents the connection to a remote FTP server.
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// A single connection only supports one in-flight data connection.
// It is not safe to be called concurrently.
type ServerConn struct {
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options *dialOptions
conn *textproto.Conn
host string
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// Server capabilities discovered at runtime
features map[string]string
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skipEPSV bool
mlstSupported bool
}
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// DialOption represents an option to start a new connection with Dial
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type DialOption struct {
setup func(do *dialOptions)
}
// dialOptions contains all the options set by DialOption.setup
type dialOptions struct {
context context.Context
dialer net.Dialer
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tlsConfig *tls.Config
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conn net.Conn
disableEPSV bool
location *time.Location
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debugOutput io.Writer
dialFunc func(network, address string) (net.Conn, error)
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}
// Entry describes a file and is returned by List().
type Entry struct {
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Name string
Target string // target of symbolic link
Type EntryType
Size uint64
Time time.Time
}
// Response represents a data-connection
type Response struct {
conn net.Conn
c *ServerConn
closed bool
}
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// Dial connects to the specified address with optinal options
func Dial(addr string, options ...DialOption) (*ServerConn, error) {
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do := &dialOptions{}
for _, option := range options {
option.setup(do)
}
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if do.location == nil {
do.location = time.UTC
}
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tconn := do.conn
if tconn == nil {
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var err error
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if do.dialFunc != nil {
tconn, err = do.dialFunc("tcp", addr)
} else if do.tlsConfig != nil {
tconn, err = tls.DialWithDialer(&do.dialer , "tcp", addr, do.tlsConfig)
} else {
ctx := do.context
if ctx == nil {
ctx = context.Background()
}
tconn, err = do.dialer.DialContext(ctx, "tcp", addr)
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}
if err != nil {
return nil, err
}
}
// Use the resolved IP address in case addr contains a domain name
// If we use the domain name, we might not resolve to the same IP.
remoteAddr := tconn.RemoteAddr().(*net.TCPAddr)
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var sourceConn io.ReadWriteCloser = tconn
if do.debugOutput != nil {
sourceConn = newDebugWrapper(tconn, do.debugOutput)
}
c := &ServerConn{
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options: do,
features: make(map[string]string),
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conn: textproto.NewConn(sourceConn),
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host: remoteAddr.IP.String(),
}
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_, _, err := c.conn.ReadResponse(StatusReady)
if err != nil {
c.Quit()
return nil, err
}
err = c.feat()
if err != nil {
c.Quit()
return nil, err
}
if _, mlstSupported := c.features["MLST"]; mlstSupported {
c.mlstSupported = true
}
return c, nil
}
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// DialWithTimeout returns a DialOption that configures the ServerConn with specified timeout
func DialWithTimeout(timeout time.Duration) DialOption {
return DialOption{func(do *dialOptions) {
do.dialer.Timeout = timeout
}}
}
// DialWithDialer returns a DialOption that configures the ServerConn with specified net.Dialer
func DialWithDialer(dialer net.Dialer) DialOption {
return DialOption{func(do *dialOptions) {
do.dialer = dialer
}}
}
// DialWithNetConn returns a DialOption that configures the ServerConn with the underlying net.Conn
func DialWithNetConn(conn net.Conn) DialOption {
return DialOption{func(do *dialOptions) {
do.conn = conn
}}
}
// DialWithDisabledEPSV returns a DialOption that configures the ServerConn with EPSV disabled
// Note that EPSV is only used when advertised in the server features.
func DialWithDisabledEPSV(disabled bool) DialOption {
return DialOption{func(do *dialOptions) {
do.disableEPSV = disabled
}}
}
// DialWithLocation returns a DialOption that configures the ServerConn with specified time.Location
// The lococation is used to parse the dates sent by the server which are in server's timezone
func DialWithLocation(location *time.Location) DialOption {
return DialOption{func(do *dialOptions) {
do.location = location
}}
}
// DialWithContext returns a DialOption that configures the ServerConn with specified context
// The context will be used for the initial connection setup
func DialWithContext(ctx context.Context) DialOption {
return DialOption{func(do *dialOptions) {
do.context = ctx
}}
}
// DialWithTLS returns a DialOption that configures the ServerConn with specified TLS config
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//
// If called together with the DialWithDialFunc option, the DialWithDialFunc function
// will be used when dialing new connections but regardless of the function,
// the connection will be treated as a TLS connection.
func DialWithTLS(tlsConfig *tls.Config) DialOption {
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return DialOption{func(do *dialOptions) {
do.tlsConfig = tlsConfig
}}
}
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// DialWithDebugOutput returns a DialOption that configures the ServerConn to write to the Writer
// everything it reads from the server
func DialWithDebugOutput(w io.Writer) DialOption {
return DialOption{func(do *dialOptions) {
do.debugOutput = w
}}
}
// DialWithDialFunc returns a DialOption that configures the ServerConn to use the
// specified function to establish both control and data connections
//
// If used together with the DialWithNetConn option, the DialWithNetConn
// takes precedence for the control connection, while data connections will
// be established using function specified with the DialWithDialFunc option
func DialWithDialFunc(f func(network, address string) (net.Conn, error)) DialOption {
return DialOption{func(do *dialOptions) {
do.dialFunc = f
}}
}
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// Connect is an alias to Dial, for backward compatibility
func Connect(addr string) (*ServerConn, error) {
return Dial(addr)
}
// DialTimeout initializes the connection to the specified ftp server address.
//
// It is generally followed by a call to Login() as most FTP commands require
// an authenticated user.
func DialTimeout(addr string, timeout time.Duration) (*ServerConn, error) {
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return Dial(addr, DialWithTimeout(timeout))
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}
// Login authenticates the client with specified user and password.
//
// "anonymous"/"anonymous" is a common user/password scheme for FTP servers
// that allows anonymous read-only accounts.
func (c *ServerConn) Login(user, password string) error {
code, message, err := c.cmd(-1, "USER %s", user)
if err != nil {
return err
}
switch code {
case StatusLoggedIn:
case StatusUserOK:
_, _, err = c.cmd(StatusLoggedIn, "PASS %s", password)
if err != nil {
return err
}
default:
return errors.New(message)
}
// Switch to binary mode
if _, _, err = c.cmd(StatusCommandOK, "TYPE I"); err != nil {
return err
}
// Switch to UTF-8
err = c.setUTF8()
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// If using implicit TLS, make data connections also use TLS
if c.options.tlsConfig != nil {
c.cmd(StatusCommandOK, "PBSZ 0")
c.cmd(StatusCommandOK, "PROT P")
}
return err
}
// feat issues a FEAT FTP command to list the additional commands supported by
// the remote FTP server.
// FEAT is described in RFC 2389
func (c *ServerConn) feat() error {
code, message, err := c.cmd(-1, "FEAT")
if err != nil {
return err
}
if code != StatusSystem {
// The server does not support the FEAT command. This is not an
// error: we consider that there is no additional feature.
return nil
}
lines := strings.Split(message, "\n")
for _, line := range lines {
if !strings.HasPrefix(line, " ") {
continue
}
line = strings.TrimSpace(line)
featureElements := strings.SplitN(line, " ", 2)
command := featureElements[0]
var commandDesc string
if len(featureElements) == 2 {
commandDesc = featureElements[1]
}
c.features[command] = commandDesc
}
return nil
}
// setUTF8 issues an "OPTS UTF8 ON" command.
func (c *ServerConn) setUTF8() error {
if _, ok := c.features["UTF8"]; !ok {
return nil
}
code, message, err := c.cmd(-1, "OPTS UTF8 ON")
if err != nil {
return err
}
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// Workaround for FTP servers, that does not support this option.
if code == StatusBadArguments {
return nil
}
// The ftpd "filezilla-server" has FEAT support for UTF8, but always returns
// "202 UTF8 mode is always enabled. No need to send this command." when
// trying to use it. That's OK
if code == StatusCommandNotImplemented {
return nil
}
if code != StatusCommandOK {
return errors.New(message)
}
return nil
}
// epsv issues an "EPSV" command to get a port number for a data connection.
func (c *ServerConn) epsv() (port int, err error) {
_, line, err := c.cmd(StatusExtendedPassiveMode, "EPSV")
if err != nil {
return
}
start := strings.Index(line, "|||")
end := strings.LastIndex(line, "|")
if start == -1 || end == -1 {
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err = errors.New("invalid EPSV response format")
return
}
port, err = strconv.Atoi(line[start+3 : end])
return
}
// pasv issues a "PASV" command to get a port number for a data connection.
func (c *ServerConn) pasv() (host string, port int, err error) {
_, line, err := c.cmd(StatusPassiveMode, "PASV")
if err != nil {
return
}
// PASV response format : 227 Entering Passive Mode (h1,h2,h3,h4,p1,p2).
start := strings.Index(line, "(")
end := strings.LastIndex(line, ")")
if start == -1 || end == -1 {
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err = errors.New("invalid PASV response format")
return
}
// We have to split the response string
pasvData := strings.Split(line[start+1:end], ",")
if len(pasvData) < 6 {
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err = errors.New("invalid PASV response format")
return
}
// Let's compute the port number
portPart1, err1 := strconv.Atoi(pasvData[4])
if err1 != nil {
err = err1
return
}
portPart2, err2 := strconv.Atoi(pasvData[5])
if err2 != nil {
err = err2
return
}
// Recompose port
port = portPart1*256 + portPart2
// Make the IP address to connect to
host = strings.Join(pasvData[0:4], ".")
return
}
// getDataConnPort returns a host, port for a new data connection
// it uses the best available method to do so
func (c *ServerConn) getDataConnPort() (string, int, error) {
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if !c.options.disableEPSV && !c.skipEPSV {
if port, err := c.epsv(); err == nil {
return c.host, port, nil
}
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// if there is an error, skip EPSV for the next attempts
c.skipEPSV = true
}
return c.pasv()
}
// openDataConn creates a new FTP data connection.
func (c *ServerConn) openDataConn() (net.Conn, error) {
host, port, err := c.getDataConnPort()
if err != nil {
return nil, err
}
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addr := net.JoinHostPort(host, strconv.Itoa(port))
if c.options.dialFunc != nil {
return c.options.dialFunc("tcp", addr)
}
if c.options.tlsConfig != nil {
conn, err := c.options.dialer.Dial("tcp", addr)
if err != nil {
return nil, err
}
return tls.Client(conn, c.options.tlsConfig), err
}
return c.options.dialer.Dial("tcp", addr)
}
// cmd is a helper function to execute a command and check for the expected FTP
// return code
func (c *ServerConn) cmd(expected int, format string, args ...interface{}) (int, string, error) {
_, err := c.conn.Cmd(format, args...)
if err != nil {
return 0, "", err
}
return c.conn.ReadResponse(expected)
}
// cmdDataConnFrom executes a command which require a FTP data connection.
// Issues a REST FTP command to specify the number of bytes to skip for the transfer.
func (c *ServerConn) cmdDataConnFrom(offset uint64, format string, args ...interface{}) (net.Conn, error) {
conn, err := c.openDataConn()
if err != nil {
return nil, err
}
if offset != 0 {
_, _, err := c.cmd(StatusRequestFilePending, "REST %d", offset)
if err != nil {
conn.Close()
return nil, err
}
}
_, err = c.conn.Cmd(format, args...)
if err != nil {
conn.Close()
return nil, err
}
code, msg, err := c.conn.ReadResponse(-1)
if err != nil {
conn.Close()
return nil, err
}
if code != StatusAlreadyOpen && code != StatusAboutToSend {
conn.Close()
return nil, &textproto.Error{Code: code, Msg: msg}
}
return conn, nil
}
// NameList issues an NLST FTP command.
func (c *ServerConn) NameList(path string) (entries []string, err error) {
conn, err := c.cmdDataConnFrom(0, "NLST %s", path)
if err != nil {
return
}
r := &Response{conn: conn, c: c}
defer r.Close()
scanner := bufio.NewScanner(r)
for scanner.Scan() {
entries = append(entries, scanner.Text())
}
if err = scanner.Err(); err != nil {
return entries, err
}
return
}
// List issues a LIST FTP command.
func (c *ServerConn) List(path string) (entries []*Entry, err error) {
var cmd string
var parser parseFunc
if c.mlstSupported {
cmd = "MLSD"
parser = parseRFC3659ListLine
} else {
cmd = "LIST"
parser = parseListLine
}
conn, err := c.cmdDataConnFrom(0, "%s %s", cmd, path)
if err != nil {
return
}
r := &Response{conn: conn, c: c}
defer r.Close()
scanner := bufio.NewScanner(r)
now := time.Now()
for scanner.Scan() {
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entry, err := parser(scanner.Text(), now, c.options.location)
if err == nil {
entries = append(entries, entry)
}
}
if err := scanner.Err(); err != nil {
return nil, err
}
return
}
// ChangeDir issues a CWD FTP command, which changes the current directory to
// the specified path.
func (c *ServerConn) ChangeDir(path string) error {
_, _, err := c.cmd(StatusRequestedFileActionOK, "CWD %s", path)
return err
}
// ChangeDirToParent issues a CDUP FTP command, which changes the current
// directory to the parent directory. This is similar to a call to ChangeDir
// with a path set to "..".
func (c *ServerConn) ChangeDirToParent() error {
_, _, err := c.cmd(StatusRequestedFileActionOK, "CDUP")
return err
}
// CurrentDir issues a PWD FTP command, which Returns the path of the current
// directory.
func (c *ServerConn) CurrentDir() (string, error) {
_, msg, err := c.cmd(StatusPathCreated, "PWD")
if err != nil {
return "", err
}
start := strings.Index(msg, "\"")
end := strings.LastIndex(msg, "\"")
if start == -1 || end == -1 {
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return "", errors.New("unsuported PWD response format")
}
return msg[start+1 : end], nil
}
// FileSize issues a SIZE FTP command, which Returns the size of the file
func (c *ServerConn) FileSize(path string) (int64, error) {
_, msg, err := c.cmd(StatusFile, "SIZE %s", path)
if err != nil {
return 0, err
}
return strconv.ParseInt(msg, 10, 64)
}
// Retr issues a RETR FTP command to fetch the specified file from the remote
// FTP server.
//
// The returned ReadCloser must be closed to cleanup the FTP data connection.
func (c *ServerConn) Retr(path string) (*Response, error) {
return c.RetrFrom(path, 0)
}
// RetrFrom issues a RETR FTP command to fetch the specified file from the remote
// FTP server, the server will not send the offset first bytes of the file.
//
// The returned ReadCloser must be closed to cleanup the FTP data connection.
func (c *ServerConn) RetrFrom(path string, offset uint64) (*Response, error) {
conn, err := c.cmdDataConnFrom(offset, "RETR %s", path)
if err != nil {
return nil, err
}
return &Response{conn: conn, c: c}, nil
}
// Stor issues a STOR FTP command to store a file to the remote FTP server.
// Stor creates the specified file with the content of the io.Reader.
//
// Hint: io.Pipe() can be used if an io.Writer is required.
func (c *ServerConn) Stor(path string, r io.Reader) error {
return c.StorFrom(path, r, 0)
}
// StorFrom issues a STOR FTP command to store a file to the remote FTP server.
// Stor creates the specified file with the content of the io.Reader, writing
// on the server will start at the given file offset.
//
// Hint: io.Pipe() can be used if an io.Writer is required.
func (c *ServerConn) StorFrom(path string, r io.Reader, offset uint64) error {
conn, err := c.cmdDataConnFrom(offset, "STOR %s", path)
if err != nil {
return err
}
_, err = io.Copy(conn, r)
conn.Close()
if err != nil {
return err
}
_, _, err = c.conn.ReadResponse(StatusClosingDataConnection)
return err
}
// Rename renames a file on the remote FTP server.
func (c *ServerConn) Rename(from, to string) error {
_, _, err := c.cmd(StatusRequestFilePending, "RNFR %s", from)
if err != nil {
return err
}
_, _, err = c.cmd(StatusRequestedFileActionOK, "RNTO %s", to)
return err
}
// Delete issues a DELE FTP command to delete the specified file from the
// remote FTP server.
func (c *ServerConn) Delete(path string) error {
_, _, err := c.cmd(StatusRequestedFileActionOK, "DELE %s", path)
return err
}
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// RemoveDirRecur deletes a non-empty folder recursively using
// RemoveDir and Delete
func (c *ServerConn) RemoveDirRecur(path string) error {
err := c.ChangeDir(path)
if err != nil {
return err
}
currentDir, err := c.CurrentDir()
if err != nil {
return err
}
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entries, err := c.List(currentDir)
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if err != nil {
return err
}
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for _, entry := range entries {
if entry.Name != ".." && entry.Name != "." {
if entry.Type == EntryTypeFolder {
err = c.RemoveDirRecur(currentDir + "/" + entry.Name)
if err != nil {
return err
}
} else {
err = c.Delete(entry.Name)
if err != nil {
return err
}
}
}
}
err = c.ChangeDirToParent()
if err != nil {
return err
}
err = c.RemoveDir(currentDir)
return err
}
// MakeDir issues a MKD FTP command to create the specified directory on the
// remote FTP server.
func (c *ServerConn) MakeDir(path string) error {
_, _, err := c.cmd(StatusPathCreated, "MKD %s", path)
return err
}
// RemoveDir issues a RMD FTP command to remove the specified directory from
// the remote FTP server.
func (c *ServerConn) RemoveDir(path string) error {
_, _, err := c.cmd(StatusRequestedFileActionOK, "RMD %s", path)
return err
}
// NoOp issues a NOOP FTP command.
// NOOP has no effects and is usually used to prevent the remote FTP server to
// close the otherwise idle connection.
func (c *ServerConn) NoOp() error {
_, _, err := c.cmd(StatusCommandOK, "NOOP")
return err
}
// Logout issues a REIN FTP command to logout the current user.
func (c *ServerConn) Logout() error {
_, _, err := c.cmd(StatusReady, "REIN")
return err
}
// Quit issues a QUIT FTP command to properly close the connection from the
// remote FTP server.
func (c *ServerConn) Quit() error {
c.conn.Cmd("QUIT")
return c.conn.Close()
}
// Read implements the io.Reader interface on a FTP data connection.
func (r *Response) Read(buf []byte) (int, error) {
return r.conn.Read(buf)
}
// Close implements the io.Closer interface on a FTP data connection.
// After the first call, Close will do nothing and return nil.
func (r *Response) Close() error {
if r.closed {
return nil
}
err := r.conn.Close()
_, _, err2 := r.c.conn.ReadResponse(StatusClosingDataConnection)
if err2 != nil {
err = err2
}
r.closed = true
return err
}
// SetDeadline sets the deadlines associated with the connection.
func (r *Response) SetDeadline(t time.Time) error {
return r.conn.SetDeadline(t)
}