/
session.go
306 lines (274 loc) · 6.95 KB
/
session.go
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package scp
import (
"bytes"
"context"
"fmt"
"github.com/pkg/errors"
"github.com/viant/afs/file"
"github.com/viant/afs/storage"
"golang.org/x/crypto/ssh"
"io"
"io/ioutil"
"os"
"path"
"strings"
"time"
)
const (
modeWrite = iota
modeRead
statusOK = 0x0
defaultTimeoutMs = 15000
)
type session struct {
*ssh.Session
skipBaseDir bool
locationName string
counter uint32
reader *reader
writer io.WriteCloser
mode int
timeout time.Duration
recursive bool
}
func (s *session) initCmd(location string) string {
_, s.locationName = path.Split(location)
var cmdSwitches = make([]string, 0)
switch s.mode {
case modeWrite:
cmdSwitches = append(cmdSwitches, "-t -p")
default:
cmdSwitches = append(cmdSwitches, "-f -p")
}
if s.recursive {
cmdSwitches = append(cmdSwitches, "-r")
}
return fmt.Sprintf("scp %v %v\n", strings.Join(cmdSwitches, " "), location)
}
func (s *session) writeStatusOK() error {
return s.write([]byte{statusOK})
}
func (s *session) runCmd(data string) error {
err := s.write([]byte(data))
if err == nil {
err = s.readStatus()
}
return err
}
func (s *session) sendToken(token byte) error {
err := s.write([]byte{token, '\n'})
if err == nil {
err = s.readStatus()
}
return err
}
func (s *session) write(data []byte) error {
_, err := s.writer.Write(data)
return err
}
func (s *session) init(location string) (err error) {
if strings.HasSuffix(location, "/") {
location = string(location[:len(location)-1])
}
if s.writer, err = s.StdinPipe(); err != nil {
return err
}
reader, err := s.StdoutPipe()
if err != nil {
return err
}
s.reader = newReader(reader)
cmd := s.initCmd(location)
if err = s.Start(cmd); err != nil {
return err
}
go s.reader.readInBackground()
return err
}
func (s *session) readContent(info os.FileInfo) (io.Reader, error) {
buf := new(bytes.Buffer)
for buf.Len() <= int(info.Size()) {
data, err := s.reader.read(s.timeout)
if err != nil {
return nil, err
}
buf.Write(data)
}
data := buf.Bytes()
overflow := data[info.Size():]
if len(overflow) != 1 || overflow[0] != statusOK {
return nil, fmt.Errorf("invalid statusOK, expected: %v, but had: %v ", statusOK, overflow)
}
data = data[:info.Size()]
return bytes.NewReader(data), nil
}
func (s *session) processNewResource(relativeElements *[]string, response []byte, modified *time.Time, handler func(parent string, info os.FileInfo, reader io.Reader) (bool, error)) (bool, error) {
fileInfo, err := NewInfo(string(response), modified)
if err != nil {
return false, err
}
var reader io.Reader
parent := path.Join(*relativeElements...)
if fileInfo.IsDir() {
if s.skipBaseDir && s.counter == 0 && fileInfo.Name() == s.locationName {
return false, nil
}
*relativeElements = append(*relativeElements, fileInfo.Name())
} else if err = s.writeStatusOK(); err == nil {
reader, err = s.readContent(fileInfo)
}
if err != nil {
return false, err
}
toContinue, err := handler(parent, fileInfo, reader)
return toContinue, err
}
func (s *session) download(ctx context.Context, skipBaseDir bool, location string, handler func(parent string, info os.FileInfo, reader io.Reader) (bool, error)) error {
if s.mode == modeWrite {
return fmt.Errorf("invalid mode")
}
err := s.init(location)
if err != nil {
return errors.Wrap(err, "failed to initialise session")
}
s.skipBaseDir = skipBaseDir
now := time.Now()
modified := &now
var pathElements = make([]string, 0)
for {
err = s.pull(&pathElements, modified, handler)
if err != nil {
if err == io.EOF {
return nil
}
break
}
}
return err
}
func (s *session) pull(pathElements *[]string, modified *time.Time, handler func(parent string, info os.FileInfo, reader io.Reader) (bool, error)) error {
err := s.writeStatusOK()
if err != nil {
return err
}
response, err := s.reader.read(s.timeout)
if err != nil {
return err
}
token := response[0]
switch token {
case FileToken, DirToken:
shallContinue, err := s.processNewResource(pathElements, response, modified, handler)
s.counter++
if err != nil || !shallContinue {
return err
}
case EndDirToken:
if len(*pathElements) > 0 {
*pathElements = (*pathElements)[:len(*pathElements)-1]
}
case TimestampToken:
timestamp, err := ParseTimeResponse(string(response))
if err != nil {
return err
}
*modified = *timestamp
case WarningToken, ErrorToken:
errorMessage := strings.TrimSpace(string(response[1:]))
return fmt.Errorf("%s", errorMessage)
default:
return fmt.Errorf("unsupported token: %v, %s", token, response)
}
return nil
}
func (s *session) readStatus() error {
data, err := s.reader.read(s.timeout)
if err != nil {
return err
}
status := data[0]
switch status {
case statusOK:
return nil
default:
return errors.New(strings.TrimSpace(string(data[1:])))
}
}
func (s *session) moveUp() error {
return s.sendToken(EndDirToken)
}
func (s *session) moveDown(info os.FileInfo) error {
return s.push(info, nil)
}
func (s *session) upload(location string) (storage.Upload, io.Closer, error) {
if s.mode == modeRead {
return nil, nil, fmt.Errorf("invalid mode")
}
err := s.init(location)
if err != nil {
return nil, nil, errors.Wrap(err, "failed to initialise session")
}
err = s.readStatus()
if err != nil {
return nil, nil, err
}
var prevRelativeElements = make([]string, 0)
handler := func(ctx context.Context, parent string, info os.FileInfo, reader io.Reader) error {
prevRelativePath := path.Join(prevRelativeElements...)
parent = strings.Trim(parent, "/")
prevRelativeElements = []string{}
if parent != "" {
prevRelativeElements = strings.Split(parent, "/")
}
err = adjustPath(prevRelativePath, parent, s.moveDown, s.moveUp)
if info.IsDir() {
prevRelativeElements = append(prevRelativeElements, info.Name())
return s.moveDown(info)
}
return s.push(info, reader)
}
return handler, s, nil
}
func (s *session) push(info os.FileInfo, reader io.Reader) error {
if info.Mode()&os.ModeSymlink > 0 {
//update size for symlink, otherwise size may be reported incorrectly
data, _ := ioutil.ReadAll(reader)
info = file.NewInfo(info.Name(), int64(len(data)), info.Mode().Perm(), info.ModTime(), info.IsDir())
reader = bytes.NewReader(data)
}
timestampCmd := InfoToTimestampCmd(info)
err := s.runCmd(timestampCmd)
if err == nil {
createCmd := InfoToCreateCmd(info)
err = s.runCmd(createCmd)
}
if err != nil {
return err
}
if !info.IsDir() {
if _, err = io.Copy(s.writer, reader); err != nil {
return err
}
err = s.writeStatusOK()
if err == nil {
err = s.readStatus()
}
}
return err
}
func (s *session) Close() error {
s.reader.sendCloseNotification()
s.reader.close()
return s.Session.Close()
}
func newSession(client *ssh.Client, mode int, recursive bool, timeout time.Duration) (*session, error) {
sshSession, err := client.NewSession()
if err != nil {
return nil, err
}
return &session{Session: sshSession,
mode: mode,
timeout: timeout,
recursive: recursive,
}, nil
}