func (f *File) WriteAt(b []byte, off int64) (n int, err error) {
req := fxpWriteMsg{Handle: f.handle}
fxpCh, err := f.sftp.chans.newChan()
if err != nil {
return
}
defer f.sftp.chans.remove(fxpCh.id)
req.SetID(fxpCh.id)
for len(b) > 0 {
req.Offset = uint64(n) + uint64(off)
l := min(uint64(len(b)), maxDataBytes)
req.Data = b[:l]
if err = f.sftp.writePacket(ssh.Marshal(req)); err != nil {
return
}
resp := fxpCh.waitForResponse()
switch msg := resp.(type) {
case *fxpStatusResp:
if msg.Status != OK {
err = msg
return
}
n += int(l)
b = b[l:]
default:
panic("unexpected message type returned from server")
}
}
return
}
func (f *File) ReadAt(b []byte, off int64) (n int, err error) {
req := fxpReadMsg{Handle: f.handle}
fxpCh, err := f.sftp.chans.newChan()
if err != nil {
return
}
defer f.sftp.chans.remove(fxpCh.id)
req.SetID(fxpCh.id)
for len(b) > 0 {
req.Offset = uint64(n) + uint64(off)
req.Length = uint32(min(uint64(len(b)), maxDataBytes))
if err = f.sftp.writePacket(ssh.Marshal(req)); err != nil {
return
}
resp := fxpCh.waitForResponse()
switch msg := resp.(type) {
case *fxpStatusResp:
if msg.Status == eof {
err = io.EOF
return
}
err = msg
return
case *fxpDataResp:
n += copy(b, msg.Data)
b = b[len(msg.Data):]
default:
panic("unexpected message type returned from server")
}
}
return
}
// init starts the SFTP protocol by negotiating the protocol version to use and
// starts the response handler in a goroutine.
func (s *Client) init() error {
msg := fxpInitMsg{
Version: 3,
}
if err := s.writePacket(ssh.Marshal(msg)); err != nil {
return err
}
packet, err := s.readOnePacket()
if err != nil {
return err
}
resp, err := decodeClient(packet)
if err != nil {
return err
}
switch resp := resp.(type) {
case *fxpVersionMsg:
if resp.Version != 3 {
return errors.New("only version 3 of Client protocol supported")
}
default:
return errors.New("invalid packet received during initialization")
}
go s.mainLoop()
return nil
}
// init starts the SFTP protocol by negotiating the protocol version to use and
// starts the response handler in a goroutine.
func (s *Client) init() error {
msg := fxpInitMsg{
Version: 3,
}
if err := s.writePacket(ssh.Marshal(msg)); err != nil {
return err
}
packet, err := s.readOnePacket()
if err != nil {
return err
}
resp, err := decodeClient(packet)
if err != nil {
return err
}
switch resp := resp.(type) {
case *fxpVersionMsg:
if resp.Version != 3 {
return errors.New("only version 3 of Client protocol supported")
}
default:
return errors.New("invalid packet received during initialization")
}
vers := resp.(*fxpVersionMsg)
s.exts = make(map[string]extension)
if len(vers.Ext) > 0 {
exts := vers.Ext
for len(exts) > 0 {
ew := extensionWire{}
if err := ssh.Unmarshal(exts, &ew); err != nil {
return err
}
if len(exts) < 2 {
break
}
exts = ew.Rest
e := extension{
Name: ew.Name,
Data: ew.Data,
}
// OpenSSH's sftp-server implementation specifies that
// the data portion of an extension is an ASCII-encoded
// version number. This is not part of the SFTP
// specification, however.
if n, err := strconv.Atoi(ew.Data); err == nil {
e.version = n
}
s.exts[e.Name] = e
}
}
go s.mainLoop()
return nil
}
// sendRequests sends a request to the server and returns a new channel on
// which the response will be sent.
func (s *Client) sendRequest(req ider) (*fxpChan, error) {
fxpCh, err := s.chans.newChan()
if err != nil {
return nil, err
}
req.SetID(fxpCh.id)
if err := s.writePacket(ssh.Marshal(req)); err != nil {
return nil, err
}
return fxpCh, nil
}