mirror of
https://github.com/restic/restic.git
synced 2024-08-23 04:40:46 +02:00
Allow setting custom arguments for the `sftp` backend, by using the `sftp.args` option. This is similar to the approach already implemented in the `rclone` backend, to support new arguments without requiring future code changes for each different SSH argument. Closes #4241
585 lines
14 KiB
Go
585 lines
14 KiB
Go
package sftp
|
|
|
|
import (
|
|
"bufio"
|
|
"context"
|
|
"crypto/rand"
|
|
"encoding/hex"
|
|
"fmt"
|
|
"hash"
|
|
"io"
|
|
"os"
|
|
"os/exec"
|
|
"path"
|
|
"time"
|
|
|
|
"github.com/restic/restic/internal/backend"
|
|
"github.com/restic/restic/internal/backend/layout"
|
|
"github.com/restic/restic/internal/backend/limiter"
|
|
"github.com/restic/restic/internal/backend/location"
|
|
"github.com/restic/restic/internal/debug"
|
|
"github.com/restic/restic/internal/errors"
|
|
"github.com/restic/restic/internal/restic"
|
|
|
|
"github.com/cenkalti/backoff/v4"
|
|
"github.com/pkg/sftp"
|
|
"golang.org/x/sync/errgroup"
|
|
)
|
|
|
|
// SFTP is a backend in a directory accessed via SFTP.
|
|
type SFTP struct {
|
|
c *sftp.Client
|
|
p string
|
|
|
|
cmd *exec.Cmd
|
|
result <-chan error
|
|
|
|
posixRename bool
|
|
|
|
layout.Layout
|
|
Config
|
|
backend.Modes
|
|
}
|
|
|
|
var _ restic.Backend = &SFTP{}
|
|
|
|
func NewFactory() location.Factory {
|
|
return location.NewLimitedBackendFactory("sftp", ParseConfig, location.NoPassword, limiter.WrapBackendConstructor(Create), limiter.WrapBackendConstructor(Open))
|
|
}
|
|
|
|
const defaultLayout = "default"
|
|
|
|
func startClient(cfg Config) (*SFTP, error) {
|
|
program, args, err := buildSSHCommand(cfg)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
debug.Log("start client %v %v", program, args)
|
|
// Connect to a remote host and request the sftp subsystem via the 'ssh'
|
|
// command. This assumes that passwordless login is correctly configured.
|
|
cmd := exec.Command(program, args...)
|
|
|
|
// prefix the errors with the program name
|
|
stderr, err := cmd.StderrPipe()
|
|
if err != nil {
|
|
return nil, errors.Wrap(err, "cmd.StderrPipe")
|
|
}
|
|
|
|
go func() {
|
|
sc := bufio.NewScanner(stderr)
|
|
for sc.Scan() {
|
|
fmt.Fprintf(os.Stderr, "subprocess %v: %v\n", program, sc.Text())
|
|
}
|
|
}()
|
|
|
|
// get stdin and stdout
|
|
wr, err := cmd.StdinPipe()
|
|
if err != nil {
|
|
return nil, errors.Wrap(err, "cmd.StdinPipe")
|
|
}
|
|
rd, err := cmd.StdoutPipe()
|
|
if err != nil {
|
|
return nil, errors.Wrap(err, "cmd.StdoutPipe")
|
|
}
|
|
|
|
bg, err := backend.StartForeground(cmd)
|
|
if err != nil {
|
|
if backend.IsErrDot(err) {
|
|
return nil, errors.Errorf("cannot implicitly run relative executable %v found in current directory, use -o sftp.command=./<command> to override", cmd.Path)
|
|
}
|
|
return nil, err
|
|
}
|
|
|
|
// wait in a different goroutine
|
|
ch := make(chan error, 1)
|
|
go func() {
|
|
err := cmd.Wait()
|
|
debug.Log("ssh command exited, err %v", err)
|
|
for {
|
|
ch <- errors.Wrap(err, "ssh command exited")
|
|
}
|
|
}()
|
|
|
|
// open the SFTP session
|
|
client, err := sftp.NewClientPipe(rd, wr)
|
|
if err != nil {
|
|
return nil, errors.Errorf("unable to start the sftp session, error: %v", err)
|
|
}
|
|
|
|
err = bg()
|
|
if err != nil {
|
|
return nil, errors.Wrap(err, "bg")
|
|
}
|
|
|
|
_, posixRename := client.HasExtension("posix-rename@openssh.com")
|
|
return &SFTP{c: client, cmd: cmd, result: ch, posixRename: posixRename}, nil
|
|
}
|
|
|
|
// clientError returns an error if the client has exited. Otherwise, nil is
|
|
// returned immediately.
|
|
func (r *SFTP) clientError() error {
|
|
select {
|
|
case err := <-r.result:
|
|
debug.Log("client has exited with err %v", err)
|
|
return backoff.Permanent(err)
|
|
default:
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// Open opens an sftp backend as described by the config by running
|
|
// "ssh" with the appropriate arguments (or cfg.Command, if set).
|
|
func Open(ctx context.Context, cfg Config) (*SFTP, error) {
|
|
debug.Log("open backend with config %#v", cfg)
|
|
|
|
sftp, err := startClient(cfg)
|
|
if err != nil {
|
|
debug.Log("unable to start program: %v", err)
|
|
return nil, err
|
|
}
|
|
|
|
return open(ctx, sftp, cfg)
|
|
}
|
|
|
|
func open(ctx context.Context, sftp *SFTP, cfg Config) (*SFTP, error) {
|
|
var err error
|
|
sftp.Layout, err = layout.ParseLayout(ctx, sftp, cfg.Layout, defaultLayout, cfg.Path)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
debug.Log("layout: %v\n", sftp.Layout)
|
|
|
|
fi, err := sftp.c.Stat(sftp.Layout.Filename(restic.Handle{Type: restic.ConfigFile}))
|
|
m := backend.DeriveModesFromFileInfo(fi, err)
|
|
debug.Log("using (%03O file, %03O dir) permissions", m.File, m.Dir)
|
|
|
|
sftp.Config = cfg
|
|
sftp.p = cfg.Path
|
|
sftp.Modes = m
|
|
return sftp, nil
|
|
}
|
|
|
|
func (r *SFTP) mkdirAllDataSubdirs(ctx context.Context, nconn uint) error {
|
|
// Run multiple MkdirAll calls concurrently. These involve multiple
|
|
// round-trips and we do a lot of them, so this whole operation can be slow
|
|
// on high-latency links.
|
|
g, _ := errgroup.WithContext(ctx)
|
|
// Use errgroup's built-in semaphore, because r.sem is not initialized yet.
|
|
g.SetLimit(int(nconn))
|
|
|
|
for _, d := range r.Paths() {
|
|
d := d
|
|
g.Go(func() error {
|
|
// First try Mkdir. For most directories in Paths, this takes one
|
|
// round trip, not counting duplicate parent creations causes by
|
|
// concurrency. MkdirAll first does Stat, then recursive MkdirAll
|
|
// on the parent, so calls typically take three round trips.
|
|
if err := r.c.Mkdir(d); err == nil {
|
|
return nil
|
|
}
|
|
return r.c.MkdirAll(d)
|
|
})
|
|
}
|
|
|
|
return g.Wait()
|
|
}
|
|
|
|
// Join combines path components with slashes (according to the sftp spec).
|
|
func (r *SFTP) Join(p ...string) string {
|
|
return path.Join(p...)
|
|
}
|
|
|
|
// ReadDir returns the entries for a directory.
|
|
func (r *SFTP) ReadDir(_ context.Context, dir string) ([]os.FileInfo, error) {
|
|
fi, err := r.c.ReadDir(dir)
|
|
|
|
// sftp client does not specify dir name on error, so add it here
|
|
err = errors.Wrapf(err, "(%v)", dir)
|
|
|
|
return fi, err
|
|
}
|
|
|
|
// IsNotExist returns true if the error is caused by a not existing file.
|
|
func (r *SFTP) IsNotExist(err error) bool {
|
|
return errors.Is(err, os.ErrNotExist)
|
|
}
|
|
|
|
func buildSSHCommand(cfg Config) (cmd string, args []string, err error) {
|
|
if cfg.Command != "" {
|
|
args, err := backend.SplitShellStrings(cfg.Command)
|
|
if err != nil {
|
|
return "", nil, err
|
|
}
|
|
if cfg.Args != "" {
|
|
return "", nil, errors.New("cannot specify both sftp.command and sftp.args options")
|
|
}
|
|
|
|
return args[0], args[1:], nil
|
|
}
|
|
|
|
cmd = "ssh"
|
|
|
|
host, port := cfg.Host, cfg.Port
|
|
|
|
args = []string{host}
|
|
if port != "" {
|
|
args = append(args, "-p", port)
|
|
}
|
|
if cfg.User != "" {
|
|
args = append(args, "-l", cfg.User)
|
|
}
|
|
|
|
if cfg.Args != "" {
|
|
a, err := backend.SplitShellStrings(cfg.Args)
|
|
if err != nil {
|
|
return "", nil, err
|
|
}
|
|
|
|
args = append(args, a...)
|
|
}
|
|
|
|
args = append(args, "-s", "sftp")
|
|
return cmd, args, nil
|
|
}
|
|
|
|
// Create creates an sftp backend as described by the config by running "ssh"
|
|
// with the appropriate arguments (or cfg.Command, if set).
|
|
func Create(ctx context.Context, cfg Config) (*SFTP, error) {
|
|
sftp, err := startClient(cfg)
|
|
if err != nil {
|
|
debug.Log("unable to start program: %v", err)
|
|
return nil, err
|
|
}
|
|
|
|
sftp.Layout, err = layout.ParseLayout(ctx, sftp, cfg.Layout, defaultLayout, cfg.Path)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
sftp.Modes = backend.DefaultModes
|
|
|
|
// test if config file already exists
|
|
_, err = sftp.c.Lstat(sftp.Layout.Filename(restic.Handle{Type: restic.ConfigFile}))
|
|
if err == nil {
|
|
return nil, errors.New("config file already exists")
|
|
}
|
|
|
|
// create paths for data and refs
|
|
if err = sftp.mkdirAllDataSubdirs(ctx, cfg.Connections); err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// repurpose existing connection
|
|
return open(ctx, sftp, cfg)
|
|
}
|
|
|
|
func (r *SFTP) Connections() uint {
|
|
return r.Config.Connections
|
|
}
|
|
|
|
// Location returns this backend's location (the directory name).
|
|
func (r *SFTP) Location() string {
|
|
return r.p
|
|
}
|
|
|
|
// Hasher may return a hash function for calculating a content hash for the backend
|
|
func (r *SFTP) Hasher() hash.Hash {
|
|
return nil
|
|
}
|
|
|
|
// HasAtomicReplace returns whether Save() can atomically replace files
|
|
func (r *SFTP) HasAtomicReplace() bool {
|
|
return r.posixRename
|
|
}
|
|
|
|
// Join joins the given paths and cleans them afterwards. This always uses
|
|
// forward slashes, which is required by sftp.
|
|
func Join(parts ...string) string {
|
|
return path.Clean(path.Join(parts...))
|
|
}
|
|
|
|
// tempSuffix generates a random string suffix that should be sufficiently long
|
|
// to avoid accidential conflicts
|
|
func tempSuffix() string {
|
|
var nonce [16]byte
|
|
_, err := rand.Read(nonce[:])
|
|
if err != nil {
|
|
panic(err)
|
|
}
|
|
return hex.EncodeToString(nonce[:])
|
|
}
|
|
|
|
// Save stores data in the backend at the handle.
|
|
func (r *SFTP) Save(_ context.Context, h restic.Handle, rd restic.RewindReader) error {
|
|
if err := r.clientError(); err != nil {
|
|
return err
|
|
}
|
|
|
|
filename := r.Filename(h)
|
|
tmpFilename := filename + "-restic-temp-" + tempSuffix()
|
|
dirname := r.Dirname(h)
|
|
|
|
// create new file
|
|
f, err := r.c.OpenFile(tmpFilename, os.O_CREATE|os.O_EXCL|os.O_WRONLY)
|
|
|
|
if r.IsNotExist(err) {
|
|
// error is caused by a missing directory, try to create it
|
|
mkdirErr := r.c.MkdirAll(r.Dirname(h))
|
|
if mkdirErr != nil {
|
|
debug.Log("error creating dir %v: %v", r.Dirname(h), mkdirErr)
|
|
} else {
|
|
// try again
|
|
f, err = r.c.OpenFile(tmpFilename, os.O_CREATE|os.O_EXCL|os.O_WRONLY)
|
|
}
|
|
}
|
|
|
|
// pkg/sftp doesn't allow creating with a mode.
|
|
// Chmod while the file is still empty.
|
|
if err == nil {
|
|
err = f.Chmod(r.Modes.File)
|
|
}
|
|
if err != nil {
|
|
return errors.Wrap(err, "OpenFile")
|
|
}
|
|
|
|
defer func() {
|
|
if err == nil {
|
|
return
|
|
}
|
|
|
|
// Try not to leave a partial file behind.
|
|
rmErr := r.c.Remove(f.Name())
|
|
if rmErr != nil {
|
|
debug.Log("sftp: failed to remove broken file %v: %v",
|
|
f.Name(), rmErr)
|
|
}
|
|
}()
|
|
|
|
// save data, make sure to use the optimized sftp upload method
|
|
wbytes, err := f.ReadFrom(rd)
|
|
if err != nil {
|
|
_ = f.Close()
|
|
err = r.checkNoSpace(dirname, rd.Length(), err)
|
|
return errors.Wrap(err, "Write")
|
|
}
|
|
|
|
// sanity check
|
|
if wbytes != rd.Length() {
|
|
_ = f.Close()
|
|
return errors.Errorf("wrote %d bytes instead of the expected %d bytes", wbytes, rd.Length())
|
|
}
|
|
|
|
err = f.Close()
|
|
if err != nil {
|
|
return errors.Wrap(err, "Close")
|
|
}
|
|
|
|
// Prefer POSIX atomic rename if available.
|
|
if r.posixRename {
|
|
err = r.c.PosixRename(tmpFilename, filename)
|
|
} else {
|
|
err = r.c.Rename(tmpFilename, filename)
|
|
}
|
|
return errors.Wrap(err, "Rename")
|
|
}
|
|
|
|
// checkNoSpace checks if err was likely caused by lack of available space
|
|
// on the remote, and if so, makes it permanent.
|
|
func (r *SFTP) checkNoSpace(dir string, size int64, origErr error) error {
|
|
// The SFTP protocol has a message for ENOSPC,
|
|
// but pkg/sftp doesn't export it and OpenSSH's sftp-server
|
|
// sends FX_FAILURE instead.
|
|
|
|
e, ok := origErr.(*sftp.StatusError)
|
|
_, hasExt := r.c.HasExtension("statvfs@openssh.com")
|
|
if !ok || e.FxCode() != sftp.ErrSSHFxFailure || !hasExt {
|
|
return origErr
|
|
}
|
|
|
|
fsinfo, err := r.c.StatVFS(dir)
|
|
if err != nil {
|
|
debug.Log("sftp: StatVFS returned %v", err)
|
|
return origErr
|
|
}
|
|
if fsinfo.Favail == 0 || fsinfo.Frsize*fsinfo.Bavail < uint64(size) {
|
|
err := errors.New("sftp: no space left on device")
|
|
return backoff.Permanent(err)
|
|
}
|
|
return origErr
|
|
}
|
|
|
|
// Load runs fn with a reader that yields the contents of the file at h at the
|
|
// given offset.
|
|
func (r *SFTP) Load(ctx context.Context, h restic.Handle, length int, offset int64, fn func(rd io.Reader) error) error {
|
|
return backend.DefaultLoad(ctx, h, length, offset, r.openReader, fn)
|
|
}
|
|
|
|
func (r *SFTP) openReader(_ context.Context, h restic.Handle, length int, offset int64) (io.ReadCloser, error) {
|
|
f, err := r.c.Open(r.Filename(h))
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
if offset > 0 {
|
|
_, err = f.Seek(offset, 0)
|
|
if err != nil {
|
|
_ = f.Close()
|
|
return nil, err
|
|
}
|
|
}
|
|
|
|
if length > 0 {
|
|
// unlimited reads usually use io.Copy which needs WriteTo support at the underlying reader
|
|
// limited reads are usually combined with io.ReadFull which reads all required bytes into a buffer in one go
|
|
return backend.LimitReadCloser(f, int64(length)), nil
|
|
}
|
|
|
|
return f, nil
|
|
}
|
|
|
|
// Stat returns information about a blob.
|
|
func (r *SFTP) Stat(_ context.Context, h restic.Handle) (restic.FileInfo, error) {
|
|
if err := r.clientError(); err != nil {
|
|
return restic.FileInfo{}, err
|
|
}
|
|
|
|
fi, err := r.c.Lstat(r.Filename(h))
|
|
if err != nil {
|
|
return restic.FileInfo{}, errors.Wrap(err, "Lstat")
|
|
}
|
|
|
|
return restic.FileInfo{Size: fi.Size(), Name: h.Name}, nil
|
|
}
|
|
|
|
// Remove removes the content stored at name.
|
|
func (r *SFTP) Remove(_ context.Context, h restic.Handle) error {
|
|
if err := r.clientError(); err != nil {
|
|
return err
|
|
}
|
|
|
|
return r.c.Remove(r.Filename(h))
|
|
}
|
|
|
|
// List runs fn for each file in the backend which has the type t. When an
|
|
// error occurs (or fn returns an error), List stops and returns it.
|
|
func (r *SFTP) List(ctx context.Context, t restic.FileType, fn func(restic.FileInfo) error) error {
|
|
basedir, subdirs := r.Basedir(t)
|
|
walker := r.c.Walk(basedir)
|
|
for {
|
|
ok := walker.Step()
|
|
if !ok {
|
|
break
|
|
}
|
|
|
|
if walker.Err() != nil {
|
|
if r.IsNotExist(walker.Err()) {
|
|
debug.Log("ignoring non-existing directory")
|
|
return nil
|
|
}
|
|
return walker.Err()
|
|
}
|
|
|
|
if walker.Path() == basedir {
|
|
continue
|
|
}
|
|
|
|
if walker.Stat().IsDir() && !subdirs {
|
|
walker.SkipDir()
|
|
continue
|
|
}
|
|
|
|
fi := walker.Stat()
|
|
if !fi.Mode().IsRegular() {
|
|
continue
|
|
}
|
|
|
|
debug.Log("send %v\n", path.Base(walker.Path()))
|
|
|
|
rfi := restic.FileInfo{
|
|
Name: path.Base(walker.Path()),
|
|
Size: fi.Size(),
|
|
}
|
|
|
|
if ctx.Err() != nil {
|
|
return ctx.Err()
|
|
}
|
|
|
|
err := fn(rfi)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
if ctx.Err() != nil {
|
|
return ctx.Err()
|
|
}
|
|
}
|
|
|
|
return ctx.Err()
|
|
}
|
|
|
|
var closeTimeout = 2 * time.Second
|
|
|
|
// Close closes the sftp connection and terminates the underlying command.
|
|
func (r *SFTP) Close() error {
|
|
if r == nil {
|
|
return nil
|
|
}
|
|
|
|
err := r.c.Close()
|
|
debug.Log("Close returned error %v", err)
|
|
|
|
// wait for closeTimeout before killing the process
|
|
select {
|
|
case err := <-r.result:
|
|
return err
|
|
case <-time.After(closeTimeout):
|
|
}
|
|
|
|
if err := r.cmd.Process.Kill(); err != nil {
|
|
return err
|
|
}
|
|
|
|
// get the error, but ignore it
|
|
<-r.result
|
|
return nil
|
|
}
|
|
|
|
func (r *SFTP) deleteRecursive(ctx context.Context, name string) error {
|
|
entries, err := r.ReadDir(ctx, name)
|
|
if err != nil {
|
|
return errors.Wrap(err, "ReadDir")
|
|
}
|
|
|
|
for _, fi := range entries {
|
|
itemName := r.Join(name, fi.Name())
|
|
if fi.IsDir() {
|
|
err := r.deleteRecursive(ctx, itemName)
|
|
if err != nil {
|
|
return errors.Wrap(err, "ReadDir")
|
|
}
|
|
|
|
err = r.c.RemoveDirectory(itemName)
|
|
if err != nil {
|
|
return errors.Wrap(err, "RemoveDirectory")
|
|
}
|
|
|
|
continue
|
|
}
|
|
|
|
err := r.c.Remove(itemName)
|
|
if err != nil {
|
|
return errors.Wrap(err, "ReadDir")
|
|
}
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// Delete removes all data in the backend.
|
|
func (r *SFTP) Delete(ctx context.Context) error {
|
|
return r.deleteRecursive(ctx, r.p)
|
|
}
|