// Names extracts the repeated name data from the Data buffer. This message
// structure is not supported by Unmarshal, so we take advantage of the "rest"
// field.
func (r *fxpNameResp) names() ([]nameData, error) {
if r.Count == 0 {
return nil, nil
}
data := r.Data
r.Data = nil
names := make([]nameData, 0, r.Count)
for len(data) > 0 {
name := fxpNameData{}
if err := ssh.Unmarshal(data, &name); err != nil {
return nil, err
}
data = name.Data
var attr *FileAttributes
var err error
attr, data, err = newFileAttributes(data)
if err != nil {
return nil, err
}
names = append(names, nameData{
filename: name.Filename,
longname: name.Longname,
attr: attr,
})
}
if len(data) != 0 {
return nil, fmt.Errorf("Expected to have 0 bytes of data left, have %d", len(data))
}
return names, nil
}
// decodeClient decodes a response packet's raw data into its corresponding
// message structure.
func decodeClient(packet []byte) (interface{}, error) {
var msg interface{}
switch packet[0] {
case fxpPacketVersion:
msg = new(fxpVersionMsg)
case fxpPacketStatus:
msg = new(fxpStatusResp)
case fxpPacketHandle:
msg = new(fxpHandleResp)
case fxpPacketData:
msg = new(fxpDataResp)
case fxpPacketName:
msg = new(fxpNameResp)
case fxpPacketAttrs:
msg = new(fxpAttrsResp)
case fxpPacketExtendedReply:
msg = new(fxpExtendedResp)
default:
return nil, UnexpectedMessageError{0, packet[0]}
}
if err := ssh.Unmarshal(packet, msg); err != nil {
return nil, err
}
return msg, 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
}
// newFileAttributes returns a new FileAttributes that represents the passed
// data.
func newFileAttributes(data []byte) (_ *FileAttributes, out []byte, err error) {
// TODO(ekg): add error len(data) doesn't have enough bytes.
f := &FileAttributes{
flags: binary.BigEndian.Uint32(data[0:4]),
}
data = data[4:]
if f.flags&fxpAttrSize > 0 {
f.size = binary.BigEndian.Uint64(data[0:8])
data = data[8:]
}
if f.flags&fxpAttrUIDGID > 0 {
f.uid = binary.BigEndian.Uint32(data[0:4])
f.gid = binary.BigEndian.Uint32(data[4:8])
data = data[8:]
}
if f.flags&fxpAttrPermissions > 0 {
f.permission = binary.BigEndian.Uint32(data[0:4])
data = data[4:]
}
if f.flags&fxpAttrACModTime > 0 {
f.aTime = binary.BigEndian.Uint32(data[0:4])
f.mTime = binary.BigEndian.Uint32(data[4:8])
data = data[8:]
}
if f.flags&fxpAttrExtended > 0 {
c := binary.BigEndian.Uint32(data[0:4])
data = data[4:]
for i := 0; i < int(c); i++ {
e := extInfo{}
if err = ssh.Unmarshal(data, &e); err != nil {
return
}
data = e.Rest
e.Rest = nil
f.ext = append(f.ext, e)
}
}
return f, data, nil
}