445 lines
17 KiB
Python
445 lines
17 KiB
Python
# Copyright (C) 2003-2007 Robey Pointer <robeypointer@gmail.com>
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#
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# This file is part of paramiko.
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#
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# Paramiko is free software; you can redistribute it and/or modify it under the
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# terms of the GNU Lesser General Public License as published by the Free
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# Software Foundation; either version 2.1 of the License, or (at your option)
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# any later version.
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#
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# Paramiko is distrubuted in the hope that it will be useful, but WITHOUT ANY
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# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
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# A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
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# details.
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#
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# You should have received a copy of the GNU Lesser General Public License
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# along with Paramiko; if not, write to the Free Software Foundation, Inc.,
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# 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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"""
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Server-mode SFTP support.
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"""
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import os
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import errno
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from Crypto.Hash import MD5, SHA
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from paramiko.common import *
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from paramiko.server import SubsystemHandler
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from paramiko.sftp import *
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from paramiko.sftp_si import *
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from paramiko.sftp_attr import *
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# known hash algorithms for the "check-file" extension
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_hash_class = {
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'sha1': SHA,
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'md5': MD5,
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}
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class SFTPServer (BaseSFTP, SubsystemHandler):
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"""
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Server-side SFTP subsystem support. Since this is a L{SubsystemHandler},
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it can be (and is meant to be) set as the handler for C{"sftp"} requests.
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Use L{Transport.set_subsystem_handler} to activate this class.
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"""
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def __init__(self, channel, name, server, sftp_si=SFTPServerInterface, *largs, **kwargs):
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"""
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The constructor for SFTPServer is meant to be called from within the
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L{Transport} as a subsystem handler. C{server} and any additional
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parameters or keyword parameters are passed from the original call to
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L{Transport.set_subsystem_handler}.
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@param channel: channel passed from the L{Transport}.
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@type channel: L{Channel}
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@param name: name of the requested subsystem.
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@type name: str
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@param server: the server object associated with this channel and
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subsystem
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@type server: L{ServerInterface}
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@param sftp_si: a subclass of L{SFTPServerInterface} to use for handling
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individual requests.
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@type sftp_si: class
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"""
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BaseSFTP.__init__(self)
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SubsystemHandler.__init__(self, channel, name, server)
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transport = channel.get_transport()
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self.logger = util.get_logger(transport.get_log_channel() + '.sftp')
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self.ultra_debug = transport.get_hexdump()
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self.next_handle = 1
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# map of handle-string to SFTPHandle for files & folders:
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self.file_table = { }
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self.folder_table = { }
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self.server = sftp_si(server, *largs, **kwargs)
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def _log(self, level, msg):
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if issubclass(type(msg), list):
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for m in msg:
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super(SFTPServer, self)._log(level, "[chan " + self.sock.get_name() + "] " + m)
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else:
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super(SFTPServer, self)._log(level, "[chan " + self.sock.get_name() + "] " + msg)
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def start_subsystem(self, name, transport, channel):
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self.sock = channel
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self._log(DEBUG, 'Started sftp server on channel %s' % repr(channel))
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self._send_server_version()
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self.server.session_started()
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while True:
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try:
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t, data = self._read_packet()
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except EOFError:
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self._log(DEBUG, 'EOF -- end of session')
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return
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except Exception, e:
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self._log(DEBUG, 'Exception on channel: ' + str(e))
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self._log(DEBUG, util.tb_strings())
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return
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msg = Message(data)
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request_number = msg.get_int()
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try:
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self._process(t, request_number, msg)
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except Exception, e:
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self._log(DEBUG, 'Exception in server processing: ' + str(e))
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self._log(DEBUG, util.tb_strings())
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# send some kind of failure message, at least
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try:
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self._send_status(request_number, SFTP_FAILURE)
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except:
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pass
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def finish_subsystem(self):
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self.server.session_ended()
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super(SFTPServer, self).finish_subsystem()
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# close any file handles that were left open (so we can return them to the OS quickly)
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for f in self.file_table.itervalues():
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f.close()
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for f in self.folder_table.itervalues():
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f.close()
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self.file_table = {}
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self.folder_table = {}
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def convert_errno(e):
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"""
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Convert an errno value (as from an C{OSError} or C{IOError}) into a
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standard SFTP result code. This is a convenience function for trapping
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exceptions in server code and returning an appropriate result.
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@param e: an errno code, as from C{OSError.errno}.
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@type e: int
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@return: an SFTP error code like L{SFTP_NO_SUCH_FILE}.
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@rtype: int
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"""
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if e == errno.EACCES:
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# permission denied
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return SFTP_PERMISSION_DENIED
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elif (e == errno.ENOENT) or (e == errno.ENOTDIR):
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# no such file
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return SFTP_NO_SUCH_FILE
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else:
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return SFTP_FAILURE
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convert_errno = staticmethod(convert_errno)
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def set_file_attr(filename, attr):
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"""
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Change a file's attributes on the local filesystem. The contents of
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C{attr} are used to change the permissions, owner, group ownership,
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and/or modification & access time of the file, depending on which
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attributes are present in C{attr}.
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This is meant to be a handy helper function for translating SFTP file
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requests into local file operations.
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@param filename: name of the file to alter (should usually be an
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absolute path).
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@type filename: str
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@param attr: attributes to change.
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@type attr: L{SFTPAttributes}
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"""
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if sys.platform != 'win32':
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# mode operations are meaningless on win32
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if attr._flags & attr.FLAG_PERMISSIONS:
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os.chmod(filename, attr.st_mode)
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if attr._flags & attr.FLAG_UIDGID:
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os.chown(filename, attr.st_uid, attr.st_gid)
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if attr._flags & attr.FLAG_AMTIME:
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os.utime(filename, (attr.st_atime, attr.st_mtime))
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if attr._flags & attr.FLAG_SIZE:
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open(filename, 'w+').truncate(attr.st_size)
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set_file_attr = staticmethod(set_file_attr)
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### internals...
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def _response(self, request_number, t, *arg):
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msg = Message()
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msg.add_int(request_number)
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for item in arg:
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if type(item) is int:
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msg.add_int(item)
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elif type(item) is long:
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msg.add_int64(item)
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elif type(item) is str:
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msg.add_string(item)
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elif type(item) is SFTPAttributes:
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item._pack(msg)
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else:
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raise Exception('unknown type for ' + repr(item) + ' type ' + repr(type(item)))
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self._send_packet(t, str(msg))
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def _send_handle_response(self, request_number, handle, folder=False):
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if not issubclass(type(handle), SFTPHandle):
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# must be error code
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self._send_status(request_number, handle)
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return
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handle._set_name('hx%d' % self.next_handle)
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self.next_handle += 1
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if folder:
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self.folder_table[handle._get_name()] = handle
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else:
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self.file_table[handle._get_name()] = handle
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self._response(request_number, CMD_HANDLE, handle._get_name())
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def _send_status(self, request_number, code, desc=None):
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if desc is None:
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try:
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desc = SFTP_DESC[code]
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except IndexError:
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desc = 'Unknown'
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# some clients expect a "langauge" tag at the end (but don't mind it being blank)
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self._response(request_number, CMD_STATUS, code, desc, '')
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def _open_folder(self, request_number, path):
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resp = self.server.list_folder(path)
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if issubclass(type(resp), list):
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# got an actual list of filenames in the folder
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folder = SFTPHandle()
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folder._set_files(resp)
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self._send_handle_response(request_number, folder, True)
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return
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# must be an error code
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self._send_status(request_number, resp)
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def _read_folder(self, request_number, folder):
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flist = folder._get_next_files()
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if len(flist) == 0:
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self._send_status(request_number, SFTP_EOF)
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return
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msg = Message()
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msg.add_int(request_number)
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msg.add_int(len(flist))
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for attr in flist:
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msg.add_string(attr.filename)
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msg.add_string(str(attr))
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attr._pack(msg)
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self._send_packet(CMD_NAME, str(msg))
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def _check_file(self, request_number, msg):
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# this extension actually comes from v6 protocol, but since it's an
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# extension, i feel like we can reasonably support it backported.
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# it's very useful for verifying uploaded files or checking for
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# rsync-like differences between local and remote files.
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handle = msg.get_string()
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alg_list = msg.get_list()
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start = msg.get_int64()
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length = msg.get_int64()
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block_size = msg.get_int()
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if handle not in self.file_table:
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self._send_status(request_number, SFTP_BAD_MESSAGE, 'Invalid handle')
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return
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f = self.file_table[handle]
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for x in alg_list:
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if x in _hash_class:
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algname = x
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alg = _hash_class[x]
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break
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else:
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self._send_status(request_number, SFTP_FAILURE, 'No supported hash types found')
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return
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if length == 0:
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st = f.stat()
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if not issubclass(type(st), SFTPAttributes):
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self._send_status(request_number, st, 'Unable to stat file')
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return
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length = st.st_size - start
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if block_size == 0:
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block_size = length
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if block_size < 256:
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self._send_status(request_number, SFTP_FAILURE, 'Block size too small')
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return
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sum_out = ''
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offset = start
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while offset < start + length:
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blocklen = min(block_size, start + length - offset)
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# don't try to read more than about 64KB at a time
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chunklen = min(blocklen, 65536)
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count = 0
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hash_obj = alg.new()
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while count < blocklen:
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data = f.read(offset, chunklen)
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if not type(data) is str:
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self._send_status(request_number, data, 'Unable to hash file')
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return
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hash_obj.update(data)
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count += len(data)
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offset += count
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sum_out += hash_obj.digest()
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msg = Message()
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msg.add_int(request_number)
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msg.add_string('check-file')
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msg.add_string(algname)
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msg.add_bytes(sum_out)
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self._send_packet(CMD_EXTENDED_REPLY, str(msg))
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def _convert_pflags(self, pflags):
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"convert SFTP-style open() flags to python's os.open() flags"
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if (pflags & SFTP_FLAG_READ) and (pflags & SFTP_FLAG_WRITE):
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flags = os.O_RDWR
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elif pflags & SFTP_FLAG_WRITE:
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flags = os.O_WRONLY
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else:
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flags = os.O_RDONLY
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if pflags & SFTP_FLAG_APPEND:
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flags |= os.O_APPEND
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if pflags & SFTP_FLAG_CREATE:
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flags |= os.O_CREAT
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if pflags & SFTP_FLAG_TRUNC:
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flags |= os.O_TRUNC
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if pflags & SFTP_FLAG_EXCL:
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flags |= os.O_EXCL
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return flags
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def _process(self, t, request_number, msg):
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self._log(DEBUG, 'Request: %s' % CMD_NAMES[t])
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if t == CMD_OPEN:
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path = msg.get_string()
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flags = self._convert_pflags(msg.get_int())
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attr = SFTPAttributes._from_msg(msg)
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self._send_handle_response(request_number, self.server.open(path, flags, attr))
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elif t == CMD_CLOSE:
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handle = msg.get_string()
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if handle in self.folder_table:
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del self.folder_table[handle]
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self._send_status(request_number, SFTP_OK)
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return
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if handle in self.file_table:
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self.file_table[handle].close()
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del self.file_table[handle]
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self._send_status(request_number, SFTP_OK)
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return
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self._send_status(request_number, SFTP_BAD_MESSAGE, 'Invalid handle')
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elif t == CMD_READ:
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handle = msg.get_string()
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offset = msg.get_int64()
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length = msg.get_int()
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if handle not in self.file_table:
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self._send_status(request_number, SFTP_BAD_MESSAGE, 'Invalid handle')
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return
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data = self.file_table[handle].read(offset, length)
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if type(data) is str:
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if len(data) == 0:
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self._send_status(request_number, SFTP_EOF)
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else:
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self._response(request_number, CMD_DATA, data)
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else:
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self._send_status(request_number, data)
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elif t == CMD_WRITE:
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handle = msg.get_string()
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offset = msg.get_int64()
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data = msg.get_string()
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if handle not in self.file_table:
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self._send_status(request_number, SFTP_BAD_MESSAGE, 'Invalid handle')
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return
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self._send_status(request_number, self.file_table[handle].write(offset, data))
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elif t == CMD_REMOVE:
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path = msg.get_string()
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self._send_status(request_number, self.server.remove(path))
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elif t == CMD_RENAME:
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oldpath = msg.get_string()
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newpath = msg.get_string()
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self._send_status(request_number, self.server.rename(oldpath, newpath))
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elif t == CMD_MKDIR:
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path = msg.get_string()
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attr = SFTPAttributes._from_msg(msg)
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self._send_status(request_number, self.server.mkdir(path, attr))
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elif t == CMD_RMDIR:
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path = msg.get_string()
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self._send_status(request_number, self.server.rmdir(path))
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elif t == CMD_OPENDIR:
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path = msg.get_string()
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self._open_folder(request_number, path)
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return
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elif t == CMD_READDIR:
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handle = msg.get_string()
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if handle not in self.folder_table:
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self._send_status(request_number, SFTP_BAD_MESSAGE, 'Invalid handle')
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return
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folder = self.folder_table[handle]
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self._read_folder(request_number, folder)
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elif t == CMD_STAT:
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path = msg.get_string()
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resp = self.server.stat(path)
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if issubclass(type(resp), SFTPAttributes):
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self._response(request_number, CMD_ATTRS, resp)
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else:
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self._send_status(request_number, resp)
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elif t == CMD_LSTAT:
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path = msg.get_string()
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resp = self.server.lstat(path)
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if issubclass(type(resp), SFTPAttributes):
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self._response(request_number, CMD_ATTRS, resp)
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else:
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self._send_status(request_number, resp)
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elif t == CMD_FSTAT:
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handle = msg.get_string()
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if handle not in self.file_table:
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self._send_status(request_number, SFTP_BAD_MESSAGE, 'Invalid handle')
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return
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resp = self.file_table[handle].stat()
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if issubclass(type(resp), SFTPAttributes):
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self._response(request_number, CMD_ATTRS, resp)
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else:
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self._send_status(request_number, resp)
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elif t == CMD_SETSTAT:
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path = msg.get_string()
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attr = SFTPAttributes._from_msg(msg)
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self._send_status(request_number, self.server.chattr(path, attr))
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elif t == CMD_FSETSTAT:
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handle = msg.get_string()
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attr = SFTPAttributes._from_msg(msg)
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if handle not in self.file_table:
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self._response(request_number, SFTP_BAD_MESSAGE, 'Invalid handle')
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return
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self._send_status(request_number, self.file_table[handle].chattr(attr))
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elif t == CMD_READLINK:
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path = msg.get_string()
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resp = self.server.readlink(path)
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if type(resp) is str:
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self._response(request_number, CMD_NAME, 1, resp, '', SFTPAttributes())
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else:
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self._send_status(request_number, resp)
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elif t == CMD_SYMLINK:
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# the sftp 2 draft is incorrect here! path always follows target_path
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target_path = msg.get_string()
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path = msg.get_string()
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self._send_status(request_number, self.server.symlink(target_path, path))
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elif t == CMD_REALPATH:
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path = msg.get_string()
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rpath = self.server.canonicalize(path)
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self._response(request_number, CMD_NAME, 1, rpath, '', SFTPAttributes())
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elif t == CMD_EXTENDED:
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tag = msg.get_string()
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if tag == 'check-file':
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self._check_file(request_number, msg)
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else:
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self._send_status(request_number, SFTP_OP_UNSUPPORTED)
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else:
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self._send_status(request_number, SFTP_OP_UNSUPPORTED)
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from paramiko.sftp_handle import SFTPHandle
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