Semplice server FTP in python

Semplice server FTP in python

ftp icon 300x300 Semplice server FTP in python

Questo script serve per creare un semplice FTP Server in Python utilizzando la libreria ftpdlib.

 

Codice server.py:

import ftpserver
authorizer = ftpserver.DummyAuthorizer()
 
#potete aggiungere altri utenti "user" "12345" sono
#username e password
authorizer.add_user("user", "12345", "C:\", perm="elradfmw")
handler = ftpserver.FTPHandler
handler.authorizer = authorizer
 
#utilizzando 127.0.0.1 il server sarà locale
#utilizzando 0.0.0.0 il server sarà remoto
address = ("127.0.0.1", 21)
ftpd = ftpserver.FTPServer(address, handler)
ftpd.serve_forever()

libreria:

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#!/usr/bin/env python
# $Id$
#
#  pyftpdlib is released under the MIT license, reproduced below:
#  ======================================================================
#  Copyright (C) 2007-2011 Giampaolo Rodola’ <g.rodola@gmail.com>
#
#                         All Rights Reserved
#
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation
# files (the “Software”), to deal in the Software without
# restriction, including without limitation the rights to use,
# copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following
# conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
# OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
# OTHER DEALINGS IN THE SOFTWARE.
#
#  ====================================================================== 

“””pyftpdlib: RFC-959 asynchronous FTP server.

pyftpdlib implements a fully functioning asynchronous FTP server as
defined in RFC-959.  A hierarchy of classes outlined below implement
the backend functionality for the FTPd:

[FTPServer] – the base class for the backend.

[FTPHandler] – a class representing the server-protocol-interpreter
(server-PI, see RFC-959). Each time a new connection occurs
FTPServer will create a new FTPHandler instance to handle the
current PI session.

[ActiveDTP], [PassiveDTP] – base classes for active/passive-DTP
backends.

[DTPHandler] – this class handles processing of data transfer
operations (server-DTP, see RFC-959).

[ThrottledDTPHandler] – a DTPHandler subclass implementing transfer
rates limits.

[DummyAuthorizer] – an “authorizer” is a class handling FTPd
authentications and permissions. It is used inside FTPHandler class
to verify user passwords, to get user’s home directory and to get
permissions when a filesystem read/write occurs. “DummyAuthorizer”
is the base authorizer class providing a platform independent
interface for managing virtual users.

[AbstractedFS] – class used to interact with the file system,
providing a high level, cross-platform interface compatible
with both Windows and UNIX style filesystems.

[CallLater] – calls a function at a later time whithin the polling
loop asynchronously.

[AuthorizerError] – base class for authorizers exceptions.

pyftpdlib also provides 3 different logging streams through 3 functions
which can be overridden to allow for custom logging.

[log] – the main logger that logs the most important messages for
the end user regarding the FTPd.

[logline] – this function is used to log commands and responses
passing through the control FTP channel.

[logerror] – log traceback outputs occurring in case of errors.

Usage example:

>>> from pyftpdlib import ftpserver
>>> authorizer = ftpserver.DummyAuthorizer()
>>> authorizer.add_user(‘user’, ‘password’, ‘/home/user’, perm=’elradfmw’)
>>> authorizer.add_anonymous(‘/home/nobody’)
>>> ftp_handler = ftpserver.FTPHandler
>>> ftp_handler.authorizer = authorizer
>>> address = (“127.0.0.1”, 21)
>>> ftpd = ftpserver.FTPServer(address, ftp_handler)
>>> ftpd.serve_forever()
Serving FTP on 127.0.0.1:21
[]127.0.0.1:2503 connected.
127.0.0.1:2503 ==> 220 Ready.
127.0.0.1:2503 <== USER anonymous
127.0.0.1:2503 ==> 331 Username ok, send password.
127.0.0.1:2503 <== PASS ******
127.0.0.1:2503 ==> 230 Login successful.
[anonymous]@127.0.0.1:2503 User anonymous logged in.
127.0.0.1:2503 <== TYPE A
127.0.0.1:2503 ==> 200 Type set to: ASCII.
127.0.0.1:2503 <== PASV
127.0.0.1:2503 ==> 227 Entering passive mode (127,0,0,1,9,201).
127.0.0.1:2503 <== LIST
127.0.0.1:2503 ==> 150 File status okay. About to open data connection.
[anonymous]@127.0.0.1:2503 OK LIST “/”. Transfer starting.
127.0.0.1:2503 ==> 226 Transfer complete.
[anonymous]@127.0.0.1:2503 Transfer complete. 706 bytes transmitted.
127.0.0.1:2503 <== QUIT
127.0.0.1:2503 ==> 221 Goodbye.
[anonymous]@127.0.0.1:2503 Disconnected.
“””

import asyncore
import asynchat
import socket
import os
import sys
import traceback
import errno
import time
import glob
import tempfile
import warnings
import random
import stat
import heapq
import optparse
from tarfile import filemode as _filemode

try:
import pwd
import grp
except ImportError:
pwd = grp = None

__all__ = [‘proto_cmds’, ‘Error’, ‘log’, ‘logline’, ‘logerror’, ‘DummyAuthorizer’,
‘AuthorizerError’, ‘FTPHandler’, ‘FTPServer’, ‘PassiveDTP’,
‘ActiveDTP’, ‘DTPHandler’, ‘ThrottledDTPHandler’, ‘FileProducer’,
‘BufferedIteratorProducer’, ‘AbstractedFS’, ‘CallLater’]

__pname__   = ‘Python FTP server library (pyftpdlib)’
__ver__     = ‘0.6.0’
__date__    = ‘2011-01-24′
__author__  = “Giampaolo Rodola’ <g.rodola@gmail.com>”
__web__     = ‘http://code.google.com/p/pyftpdlib/’

proto_cmds = {
‘ABOR’ : dict(perm=None, auth=True,  arg=False, help=’Syntax: ABOR (abort transfer).’),
‘ALLO’ : dict(perm=None, auth=True,  arg=True,  help=’Syntax: ALLO <SP> bytes (noop; allocate storage).’),
‘APPE’ : dict(perm=’a’,  auth=True,  arg=True,  help=’Syntax: APPE <SP> file-name (append data to an existent file).’),
‘CDUP’ : dict(perm=’e’,  auth=True,  arg=False, help=’Syntax: CDUP (go to parent directory).’),
‘CWD’  : dict(perm=’e’,  auth=True,  arg=None,  help=’Syntax: CWD [<SP> dir-name] (change current working directory).’),
‘DELE’ : dict(perm=’d’,  auth=True,  arg=True,  help=’Syntax: DELE <SP> file-name (delete file).’),
‘EPRT’ : dict(perm=None, auth=True,  arg=True,  help=’Syntax: EPRT <SP> |proto|ip|port| (set server in extended active mode).’),
‘EPSV’ : dict(perm=None, auth=True,  arg=None,  help=’Syntax: EPSV [<SP> proto/”ALL”] (set server in extended passive mode).’),
‘FEAT’ : dict(perm=None, auth=False, arg=False, help=’Syntax: FEAT (list all new features supported).’),
‘HELP’ : dict(perm=None, auth=False, arg=None,  help=’Syntax: HELP [<SP> cmd] (show help).’),
‘LIST’ : dict(perm=’l’,  auth=True,  arg=None,  help=’Syntax: LIST [<SP> path-name] (list files).’),
‘MDTM’ : dict(perm=’l’,  auth=True,  arg=True,  help=’Syntax: MDTM [<SP> file-name] (get last modification time).’),
‘MLSD’ : dict(perm=’l’,  auth=True,  arg=None,  help=’Syntax: MLSD [<SP> dir-name] (list files in a machine-processable form).’),
‘MLST’ : dict(perm=’l’,  auth=True,  arg=None,  help=’Syntax: MLST [<SP> path-name] (show a path in a machine-processable form).’),
‘MODE’ : dict(perm=None, auth=True,  arg=True,  help=’Syntax: MODE <SP> mode (noop; set data transfer mode).’),
‘MKD’  : dict(perm=’m’,  auth=True,  arg=True,  help=’Syntax: MKD <SP> dir-name (create directory).’),
‘NLST’ : dict(perm=’l’,  auth=True,  arg=None,  help=’Syntax: NLST [<SP> path-name] (list files in a compact form).’),
‘NOOP’ : dict(perm=None, auth=False, arg=False, help=’Syntax: NOOP (just do nothing).’),
‘OPTS’ : dict(perm=None, auth=True,  arg=True,  help=’Syntax: OPTS <SP> ftp-command [<SP> option] (specify options for FTP commands).’),
‘PASS’ : dict(perm=None, auth=False, arg=True,  help=’Syntax: PASS <SP> user-name (set user password).’),
‘PASV’ : dict(perm=None, auth=True,  arg=False, help=’Syntax: PASV (set server in passive mode).’),
‘PORT’ : dict(perm=None, auth=True,  arg=True,  help=’Syntax: PORT <sp> h1,h2,h3,h4,p1,p2 (set server in active mode).’),
‘PWD’  : dict(perm=None, auth=True,  arg=False, help=’Syntax: PWD (get current working directory).’),
‘QUIT’ : dict(perm=None, auth=False, arg=False, help=’Syntax: QUIT (quit current session).’),
‘REIN’ : dict(perm=None, auth=True,  arg=False, help=’Syntax: REIN (reinitialize / flush account).’),
‘REST’ : dict(perm=None, auth=True,  arg=True,  help=’Syntax: REST <SP> marker (restart file position).’),
‘RETR’ : dict(perm=’r’,  auth=True,  arg=True,  help=’Syntax: RETR <SP> file-name (retrieve a file).’),
‘RMD’  : dict(perm=’d’,  auth=True,  arg=True,  help=’Syntax: RMD <SP> dir-name (remove directory).’),
‘RNFR’ : dict(perm=’f’,  auth=True,  arg=True,  help=’Syntax: RNFR <SP> file-name (file renaming (source name)).’),
‘RNTO’ : dict(perm=’f’,  auth=True,  arg=True,  help=’Syntax: RNTO <SP> file-name (file renaming (destination name)).’),
‘SITE’ : dict(perm=None, auth=False, arg=True,  help=’Syntax: SITE <SP> site-command (execute the specified SITE command).’),
‘SITE HELP’ : dict(perm=None, auth=False, arg=None, help=’Syntax: SITE HELP [<SP> site-command] (show SITE command help).’),
‘SIZE’ : dict(perm=’l’,  auth=True,  arg=True,  help=’Syntax: SIZE <SP> file-name (get file size).’),
‘STAT’ : dict(perm=’l’,  auth=False, arg=None,  help=’Syntax: STAT [<SP> path name] (status information [list files]).’),
‘STOR’ : dict(perm=’w’,  auth=True,  arg=True,  help=’Syntax: STOR <SP> file-name (store a file).’),
‘STOU’ : dict(perm=’w’,  auth=True,  arg=None,  help=’Syntax: STOU [<SP> file-name] (store a file with a unique name).’),
‘STRU’ : dict(perm=None, auth=True,  arg=True,  help=’Syntax: STRU <SP> type (noop; set file structure).’),
‘SYST’ : dict(perm=None, auth=False, arg=False, help=’Syntax: SYST (get operating system type).’),
‘TYPE’ : dict(perm=None, auth=True,  arg=True,  help=’Syntax: TYPE <SP> [A | I] (set transfer type).’),
‘USER’ : dict(perm=None, auth=False, arg=True,  help=’Syntax: USER <SP> user-name (set username).’),
‘XCUP’ : dict(perm=’e’,  auth=True,  arg=False, help=’Syntax: XCUP (obsolete; go to parent directory).’),
‘XCWD’ : dict(perm=’e’,  auth=True,  arg=None,  help=’Syntax: XCWD [<SP> dir-name] (obsolete; change current directory).’),
‘XMKD’ : dict(perm=’m’,  auth=True,  arg=True,  help=’Syntax: XMKD <SP> dir-name (obsolete; create directory).’),
‘XPWD’ : dict(perm=None, auth=True,  arg=False, help=’Syntax: XPWD (obsolete; get current dir).’),
‘XRMD’ : dict(perm=’d’,  auth=True,  arg=True,  help=’Syntax: XRMD <SP> dir-name (obsolete; remove directory).’),
}

def _strerror(err):
“””A wrap around os.strerror() which may be not available on all
platforms (e.g. pythonCE).

– (instance) err: an EnvironmentError or derived class instance.
“””
if hasattr(os, ‘strerror’):
return os.strerror(err.errno)
else:
return err.strerror

# the heap used for the scheduled tasks
_tasks = []

def _scheduler():
“””Run the scheduled functions due to expire soonest (if any).”””
now = time.time()
while _tasks and now >= _tasks[0].timeout:
call = heapq.heappop(_tasks)
if call.repush:
heapq.heappush(_tasks, call)
call.repush = False
continue
try:
try:
call.call()
except (KeyboardInterrupt, SystemExit, asyncore.ExitNow):
raise
except:
logerror(traceback.format_exc())
finally:
if not call.cancelled:
call.cancel()

# dirty hack to support property.setter on python < 2.6
if not hasattr(property, “setter”):
class property(property):
def setter(self, value):
cls_ns = sys._getframe(1).f_locals
for k, v in cls_ns.iteritems():
if v == self:
name = k
break
cls_ns[name] = property(self.fget, value, self.fdel, self.__doc__)
return cls_ns[name]

class CallLater(object):
“””Calls a function at a later time.

It can be used to asynchronously schedule a call within the polling
loop without blocking it. The instance returned is an object that
can be used to cancel or reschedule the call.
“””

def __init__(self, seconds, target, *args, **kwargs):
“””
– (int) seconds: the number of seconds to wait
– (obj) target: the callable object to call later
– args: the arguments to call it with
– kwargs: the keyword arguments to call it with; a special
‘_errback’ parameter can be passed: it is a callable
called in case target function raises an exception.
“””
assert callable(target), “%s is not callable” % target
assert sys.maxint >= seconds >= 0, “%s is not greater than or equal ”
“to 0 seconds” % seconds
self.__delay = seconds
self.__target = target
self.__args = args
self.__kwargs = kwargs
self.__errback = kwargs.pop(‘_errback’, None)
# seconds from the epoch at which to call the function
self.timeout = time.time() + self.__delay
self.repush = False
self.cancelled = False
heapq.heappush(_tasks, self)

def __le__(self, other):
return self.timeout <= other.timeout

def call(self):
“””Call this scheduled function.”””
assert not self.cancelled, “Already cancelled”
try:
self.__target(*self.__args, **self.__kwargs)
except (KeyboardInterrupt, SystemExit, asyncore.ExitNow):
raise
except:
if self.__errback is not None:
self.__errback()
else:
raise

def reset(self):
“””Reschedule this call resetting the current countdown.”””
assert not self.cancelled, “Already cancelled”
self.timeout = time.time() + self.__delay
self.repush = True

def delay(self, seconds):
“””Reschedule this call for a later time.”””
assert not self.cancelled, “Already cancelled.”
assert sys.maxint >= seconds >= 0, “%s is not greater than or equal ”
“to 0 seconds” % seconds
self.__delay = seconds
newtime = time.time() + self.__delay
if newtime > self.timeout:
self.timeout = newtime
self.repush = True
else:
# XXX – slow, can be improved
self.timeout = newtime
heapq.heapify(_tasks)

def cancel(self):
“””Unschedule this call.”””
assert not self.cancelled, “Already cancelled”
self.cancelled = True
del self.__target, self.__args, self.__kwargs, self.__errback
if self in _tasks:
pos = _tasks.index(self)
if pos == 0:
heapq.heappop(_tasks)
elif pos == len(_tasks) – 1:
_tasks.pop(pos)
else:
_tasks[pos] = _tasks.pop()
heapq._siftup(_tasks, pos)

# — library defined exceptions

class Error(Exception):
“””Base class for module exceptions.”””

class AuthorizerError(Error):
“””Base class for authorizer exceptions.”””

class _FileReadWriteError(OSError):
“””Exception raised when reading or writing a file during a transfer.”””

# — loggers

def log(msg):
“””Log messages intended for the end user.”””
print msg

def logline(msg):
“””Log commands and responses passing through the command channel.”””
print msg

def logerror(msg):
“””Log traceback outputs occurring in case of errors.”””
sys.stderr.write(str(msg) + ‘n’)
sys.stderr.flush()

# — authorizers

class DummyAuthorizer(object):
“””Basic “dummy” authorizer class, suitable for subclassing to
create your own custom authorizers.

An “authorizer” is a class handling authentications and permissions
of the FTP server.  It is used inside FTPHandler class for verifying
user’s password, getting users home directory, checking user
permissions when a file read/write event occurs and changing user
before accessing the filesystem.

DummyAuthorizer is the base authorizer, providing a platform
independent interface for managing “virtual” FTP users. System
dependent authorizers can by written by subclassing this base
class and overriding appropriate methods as necessary.
“””

read_perms = “elr”
write_perms = “adfmw”

def __init__(self):
self.user_table = {}

def add_user(self, username, password, homedir, perm=’elr’,
msg_login=”Login successful.”, msg_quit=”Goodbye.”):
“””Add a user to the virtual users table.

AuthorizerError exceptions raised on error conditions such as
invalid permissions, missing home directory or duplicate usernames.

Optional perm argument is a string referencing the user’s
permissions explained below:

Read permissions:
– “e” = change directory (CWD command)
– “l” = list files (LIST, NLST, STAT, MLSD, MLST, SIZE, MDTM commands)
– “r” = retrieve file from the server (RETR command)

Write permissions:
– “a” = append data to an existing file (APPE command)
– “d” = delete file or directory (DELE, RMD commands)
– “f” = rename file or directory (RNFR, RNTO commands)
– “m” = create directory (MKD command)
– “w” = store a file to the server (STOR, STOU commands)

Optional msg_login and msg_quit arguments can be specified to
provide customized response strings when user log-in and quit.
“””
if self.has_user(username):
raise ValueError(‘user “%s” already exists’ % username)
if not os.path.isdir(homedir):
raise ValueError(‘no such directory: “%s”‘ % homedir)
homedir = os.path.realpath(homedir)
self._check_permissions(username, perm)
dic = {‘pwd’: str(password),
‘home’: homedir,
‘perm’: perm,
‘operms’: {},
‘msg_login’: str(msg_login),
‘msg_quit’: str(msg_quit)
}
self.user_table[username] = dic

def add_anonymous(self, homedir, **kwargs):
“””Add an anonymous user to the virtual users table.

AuthorizerError exception raised on error conditions such as
invalid permissions, missing home directory, or duplicate
anonymous users.

The keyword arguments in kwargs are the same expected by
add_user method: “perm”, “msg_login” and “msg_quit”.

The optional “perm” keyword argument is a string defaulting to
“elr” referencing “read-only” anonymous user’s permissions.

Using write permission values (“adfmw”) results in a
RuntimeWarning.
“””
DummyAuthorizer.add_user(self, ‘anonymous’, ”, homedir, **kwargs)

def remove_user(self, username):
“””Remove a user from the virtual users table.”””
del self.user_table[username]

def override_perm(self, username, directory, perm, recursive=False):
“””Override permissions for a given directory.”””
self._check_permissions(username, perm)
if not os.path.isdir(directory):
raise ValueError(‘no such directory: “%s”‘ % directory)
directory = os.path.normcase(os.path.realpath(directory))
home = os.path.normcase(self.get_home_dir(username))
if directory == home:
raise ValueError(“can’t override home directory permissions”)
if not self._issubpath(directory, home):
raise ValueError(“path escapes user home directory”)
self.user_table[username][‘operms’][directory] = perm, recursive

def validate_authentication(self, username, password):
“””Return True if the supplied username and password match the
stored credentials.”””
if not self.has_user(username):
return False
if username == ‘anonymous’:
return True
return self.user_table[username][‘pwd’] == password

def impersonate_user(self, username, password):
“””Impersonate another user (noop).

It is always called before accessing the filesystem.
By default it does nothing.  The subclass overriding this
method is expected to provide a mechanism to change the
current user.
“””

def terminate_impersonation(self, username):
“””Terminate impersonation (noop).

It is always called after having accessed the filesystem.
By default it does nothing.  The subclass overriding this
method is expected to provide a mechanism to switch back
to the original user.
“””

def has_user(self, username):
“””Whether the username exists in the virtual users table.”””
return username in self.user_table

def has_perm(self, username, perm, path=None):
“””Whether the user has permission over path (an absolute
pathname of a file or a directory).

Expected perm argument is one of the following letters:
“elradfmw”.
“””
if path is None:
return perm in self.user_table[username][‘perm’]

path = os.path.normcase(path)
for dir in self.user_table[username][‘operms’].keys():
operm, recursive = self.user_table[username][‘operms’][dir]
if self._issubpath(path, dir):
if recursive:
return perm in operm
if (path == dir) or (os.path.dirname(path) == dir
and not os.path.isdir(path)):
return perm in operm

return perm in self.user_table[username][‘perm’]

def get_perms(self, username):
“””Return current user permissions.”””
return self.user_table[username][‘perm’]

def get_home_dir(self, username):
“””Return the user’s home directory.”””
return self.user_table[username][‘home’]

def get_msg_login(self, username):
“””Return the user’s login message.”””
return self.user_table[username][‘msg_login’]

def get_msg_quit(self, username):
“””Return the user’s quitting message.”””
return self.user_table[username][‘msg_quit’]

def _check_permissions(self, username, perm):
warned = 0
for p in perm:
if p not in self.read_perms + self.write_perms:
raise ValueError(‘no such permission “%s”‘ % p)
if (username == ‘anonymous’) and (p in self.write_perms) and not warned:
warnings.warn(“write permissions assigned to anonymous user.”,
RuntimeWarning)
warned = 1

def _issubpath(self, a, b):
“””Return True if a is a sub-path of b or if the paths are equal.”””
p1 = a.rstrip(os.sep).split(os.sep)
p2 = b.rstrip(os.sep).split(os.sep)
return p1[:len(p2)] == p2

# — DTP classes

class PassiveDTP(object, asyncore.dispatcher):
“””This class is an asyncore.dispatcher subclass. It creates a
socket listening on a local port, dispatching the resultant
connection to DTPHandler.

– (int) timeout: the timeout for a remote client to establish
connection with the listening socket. Defaults to 30 seconds.
“””
timeout = 30

def __init__(self, cmd_channel, extmode=False):
“””Initialize the passive data server.

– (instance) cmd_channel: the command channel class instance.
– (bool) extmode: wheter use extended passive mode response type.
“””
asyncore.dispatcher.__init__(self)
self.cmd_channel = cmd_channel
if self.timeout:
self._idler = CallLater(self.timeout, self.handle_timeout,
_errback=self.handle_error)
else:
self._idler = None

local_ip = self.cmd_channel.socket.getsockname()[0]
if local_ip in self.cmd_channel.masquerade_address_map:
masqueraded_ip = self.cmd_channel.masquerade_address_map[local_ip]
elif self.cmd_channel.masquerade_address:
masqueraded_ip = self.cmd_channel.masquerade_address
else:
masqueraded_ip = None

self.create_socket(self.cmd_channel._af, socket.SOCK_STREAM)

if self.cmd_channel.passive_ports is None:
# By using 0 as port number value we let kernel choose a
# free unprivileged random port.
self.bind((local_ip, 0))
else:
ports = list(self.cmd_channel.passive_ports)
while ports:
port = ports.pop(random.randint(0, len(ports) -1))
try:
self.bind((local_ip, port))
except socket.error, why:
if why[0] == errno.EADDRINUSE:  # port already in use
if ports:
continue
# If cannot use one of the ports in the configured
# range we’ll use a kernel-assigned port, and log
# a message reporting the issue.
# By using 0 as port number value we let kernel
# choose a free unprivileged random port.
else:
self.bind((local_ip, 0))
self.cmd_channel.log(
“Can’t find a valid passive port in the ”
“configured range. A random kernel-assigned ”
“port will be used.”
)
else:
raise
else:
break
self.listen(5)

port = self.socket.getsockname()[1]
if not extmode:
ip = masqueraded_ip or local_ip
if ip.startswith(‘::ffff:’):
# In this scenario, the server has an IPv6 socket, but
# the remote client is using IPv4 and its address is
# represented as an IPv4-mapped IPv6 address which
# looks like this ::ffff:151.12.5.65, see:
# http://en.wikipedia.org/wiki/IPv6#IPv4-mapped_addresses
# http://tools.ietf.org/html/rfc3493.html#section-3.7
# We truncate the first bytes to make it look like a
# common IPv4 address.
ip = ip[7:]
# The format of 227 response in not standardized.
# This is the most expected:
self.cmd_channel.respond(‘227 Entering passive mode (%s,%d,%d).’ % (
ip.replace(‘.’, ‘,’), port / 256, port % 256))
else:
self.cmd_channel.respond(‘229 Entering extended passive mode ‘
‘(|||%d|).’ % port)

# — connection / overridden

def handle_accept(self):
“””Called when remote client initiates a connection.”””
try:
sock, addr = self.accept()
except TypeError:
# sometimes accept() might return None (see issue 91)
return
except socket.error, err:
# ECONNABORTED might be thrown on *BSD (see issue 105)
if err[0] != errno.ECONNABORTED:
self.cmd_channel.logerror(traceback.format_exc())
return
else:
# sometimes addr == None instead of (ip, port) (see issue 104)
if addr == None:
return

# Check the origin of data connection.  If not expressively
# configured we drop the incoming data connection if remote
# IP address does not match the client’s IP address.
if (self.cmd_channel.remote_ip != addr[0]):
if not self.cmd_channel.permit_foreign_addresses:
try:
sock.close()
except socket.error:
pass
msg = ‘Rejected data connection from foreign address %s:%s.’
%(addr[0], addr[1])
self.cmd_channel.respond(“425 %s” % msg)
self.cmd_channel.log(msg)
# do not close listening socket: it couldn’t be client’s blame
return
else:
# site-to-site FTP allowed
msg = ‘Established data connection with foreign address %s:%s.’
% (addr[0], addr[1])
self.cmd_channel.log(msg)
# Immediately close the current channel (we accept only one
# connection at time) and avoid running out of max connections
# limit.
self.close()
# delegate such connection to DTP handler
handler = self.cmd_channel.dtp_handler(sock, self.cmd_channel)
if handler.connected:
self.cmd_channel.data_channel = handler
self.cmd_channel._on_dtp_connection()

def handle_timeout(self):
self.cmd_channel.respond(“421 Passive data channel timed out.”)
self.close()

def writable(self):
return 0

def handle_error(self):
“””Called to handle any uncaught exceptions.”””
try:
raise
except (KeyboardInterrupt, SystemExit, asyncore.ExitNow):
raise
except:
logerror(traceback.format_exc())
self.close()

def close(self):
asyncore.dispatcher.close(self)
if self._idler is not None and not self._idler.cancelled:
self._idler.cancel()

class ActiveDTP(object, asyncore.dispatcher):
“””This class is an asyncore.disptacher subclass. It creates a
socket resulting from the connection to a remote user-port,
dispatching it to DTPHandler.

– (int) timeout: the timeout for us to establish connection with
the client’s listening data socket.
“””
timeout = 30

def __init__(self, ip, port, cmd_channel):
“””Initialize the active data channel attemping to connect
to remote data socket.

– (str) ip: the remote IP address.
– (int) port: the remote port.
– (instance) cmd_channel: the command channel class instance.
“””
asyncore.dispatcher.__init__(self)
self.cmd_channel = cmd_channel
if self.timeout:
self._idler = CallLater(self.timeout, self.handle_timeout,
_errback=self.handle_error)
else:
self._idler = None
if ip.count(‘.’) == 4:
self._cmd = “PORT”
self._normalized_addr = “%s:%s” % (ip, port)
else:
self._cmd = “EPRT”
self._normalized_addr = “[%s]:%s” % (ip, port)

self.create_socket(self.cmd_channel._af, socket.SOCK_STREAM)
# Have the active connection come from the same IP address
# as the command channel, see:
# http://code.google.com/p/pyftpdlib/issues/detail?id=123
source_ip = self.cmd_channel.socket.getsockname()[0]
self.bind((source_ip, 0))
try:
self.connect((ip, port))
except (socket.gaierror, socket.error), err:
self.close()
msg = “Can’t connect to specified address.”
if hasattr(err, ‘errno’):
msg += ” %s.” % _strerror(err)
self.cmd_channel.respond(“425 ” + msg)
self.cmd_channel.log_cmd(self._cmd, self._normalized_addr, 425, msg)

# overridden to prevent unhandled read/write event messages to
# be printed by asyncore on Python < 2.6

def handle_write(self):
pass

def handle_read(self):
pass

def handle_connect(self):
“””Called when connection is established.”””
if self._idler is not None and not self._idler.cancelled:
self._idler.cancel()
msg = ‘Active data connection established.’
self.cmd_channel.respond(‘200 ‘ + msg)
self.cmd_channel.log_cmd(self._cmd, self._normalized_addr, 200, msg)
# delegate such connection to DTP handler
handler = self.cmd_channel.dtp_handler(self.socket, self.cmd_channel)
self.cmd_channel.data_channel = handler
self.cmd_channel._on_dtp_connection()
# Can’t close right now as the handler would have the socket
# object disconnected.  This class will be “closed” once the
# data transfer is completed or the client disconnects.
#self.close()

def handle_timeout(self):
msg = “Active data channel timed out.”
self.cmd_channel.respond(“421 ” +  msg)
self.cmd_channel.log_cmd(self._cmd, self._normalized_addr, 421, msg)
self.close()

def handle_expt(self):
msg = “Can’t connect to specified address.”
self.cmd_channel.respond(“425 ” + msg)
self.cmd_channel.log_cmd(self._cmd, self._normalized_addr, 425, msg)
self.close()

def handle_error(self):
“””Called to handle any uncaught exceptions.”””
try:
raise
except (KeyboardInterrupt, SystemExit, asyncore.ExitNow):
raise
except:
self.cmd_channel.logerror(traceback.format_exc())
self.handle_expt()

def close(self):
asyncore.dispatcher.close(self)
if self._idler is not None and not self._idler.cancelled:
self._idler.cancel()

class DTPHandler(object, asynchat.async_chat):
“””Class handling server-data-transfer-process (server-DTP, see
RFC-959) managing data-transfer operations involving sending
and receiving data.

Class attributes:

– (int) timeout: the timeout which roughly is the maximum time we
permit data transfers to stall for with no progress. If the
timeout triggers, the remote client will be kicked off
(defaults 300).

– (int) ac_in_buffer_size: incoming data buffer size (defaults 65536)

– (int) ac_out_buffer_size: outgoing data buffer size (defaults 65536)
“””

timeout = 300
ac_in_buffer_size = 65536
ac_out_buffer_size = 65536

def __init__(self, sock_obj, cmd_channel):
“””Initialize the command channel.

– (instance) sock_obj: the socket object instance of the newly
established connection.
– (instance) cmd_channel: the command channel class instance.
“””
self.cmd_channel = cmd_channel
self.file_obj = None
self.receive = False
self.transfer_finished = False
self.tot_bytes_sent = 0
self.tot_bytes_received = 0
self.cmd = None
self._data_wrapper = lambda x: x
self._lastdata = 0
self._closed = False
self._had_cr = False
self._start_time = time.time()
self._resp = None
if self.timeout:
self._idler = CallLater(self.timeout, self.handle_timeout,
_errback=self.handle_error)
else:
self._idler = None
try:
asynchat.async_chat.__init__(self, sock_obj)
except socket.error, err:
# http://code.google.com/p/pyftpdlib/issues/detail?id=143
self.close()
if err[0] == errno.EINVAL:
return
return self.handle_error()
# remove this instance from asyncore socket map
if not self.connected:
self.close()

# — utility methods

def _posix_ascii_data_wrapper(self, chunk):
“””The data wrapper used for receiving data in ASCII mode on
systems using a single line terminator, handling those cases
where CRLF (‘rn’) gets delivered in two chunks.
“””
if self._had_cr:
chunk = ‘r’ + chunk

if chunk.endswith(‘r’):
self._had_cr = True
chunk = chunk[:-1]
else:
self._had_cr = False

return chunk.replace(‘rn’, os.linesep)

def enable_receiving(self, type, cmd):
“””Enable receiving of data over the channel. Depending on the
TYPE currently in use it creates an appropriate wrapper for the
incoming data.

– (str) type: current transfer type, ‘a’ (ASCII) or ‘i’ (binary).
“””
self.cmd = cmd
if type == ‘a’:
if os.linesep == ‘rn’:
self._data_wrapper = lambda x: x
else:
self._data_wrapper = self._posix_ascii_data_wrapper
elif type == ‘i’:
self._data_wrapper = lambda x: x
else:
raise TypeError(“unsupported type”)
self.receive = True

def get_transmitted_bytes(self):
“Return the number of transmitted bytes.”
return self.tot_bytes_sent + self.tot_bytes_received

def get_elapsed_time(self):
“Return the transfer elapsed time in seconds.”
return time.time() – self._start_time

def transfer_in_progress(self):
“Return True if a transfer is in progress, else False.”
return self.get_transmitted_bytes() != 0

# — connection

def send(self, data):
result = asyncore.dispatcher.send(self, data)
self.tot_bytes_sent += result
return result

def refill_buffer (self):
“””Overridden as a fix around http://bugs.python.org/issue1740572
(when the producer is consumed, close() was called instead of
handle_close()).
“””
while 1:
if len(self.producer_fifo):
p = self.producer_fifo.first()
# a ‘None’ in the producer fifo is a sentinel,
# telling us to close the channel.
if p is None:
if not self.ac_out_buffer:
self.producer_fifo.pop()
#self.close()
self.handle_close()
return
elif isinstance(p, str):
self.producer_fifo.pop()
self.ac_out_buffer = self.ac_out_buffer + p
return
data = p.more()
if data:
self.ac_out_buffer = self.ac_out_buffer + data
return
else:
self.producer_fifo.pop()
else:
return

def handle_read(self):
“””Called when there is data waiting to be read.”””
try:
chunk = self.recv(self.ac_in_buffer_size)
except socket.error:
self.handle_error()
else:
self.tot_bytes_received += len(chunk)
if not chunk:
self.transfer_finished = True
#self.close()  # <– asyncore.recv() already do that…
return
try:
self.file_obj.write(self._data_wrapper(chunk))
except OSError, err:
raise _FileReadWriteError(err)

def readable(self):
“””Predicate for inclusion in the readable for select().”””
# we don’t use asynchat’s find terminator feature so we can
# freely avoid to call the original implementation
return self.receive

def writable(self):
“””Predicate for inclusion in the writable for select().”””
return not self.receive and asynchat.async_chat.writable(self)

def handle_timeout(self):
“””Called cyclically to check if data trasfer is stalling with
no progress in which case the client is kicked off.
“””
if self.get_transmitted_bytes() > self._lastdata:
self._lastdata = self.get_transmitted_bytes()
self._idler = CallLater(self.timeout, self.handle_timeout,
_errback=self.handle_error)
else:
msg = “Data connection timed out.”
self.cmd_channel.log(msg)
self._resp = “421 ” + msg
self.close()
self.cmd_channel.close_when_done()

def handle_expt(self):
“””Called on “exceptional” data events.”””
self.cmd_channel.respond(“426 Connection error; transfer aborted.”)
self.close()

def handle_error(self):
“””Called when an exception is raised and not otherwise handled.”””
try:
raise
except (KeyboardInterrupt, SystemExit, asyncore.ExitNow):
raise
except socket.error, err:
# fixes around various bugs:
# – http://bugs.python.org/issue1736101
# – http://code.google.com/p/pyftpdlib/issues/detail?id=104
# – http://code.google.com/p/pyftpdlib/issues/detail?id=109
if err[0] in (errno.ECONNRESET, errno.ENOTCONN, errno.ESHUTDOWN,
errno.ECONNABORTED, errno.EPIPE, errno.EBADF):
self.handle_close()
return
else:
self.cmd_channel.logerror(traceback.format_exc())
error = str(err[1])
# an error could occur in case we fail reading / writing
# from / to file (e.g. file system gets full)
except _FileReadWriteError, err:
error = _strerror(err[0])
except:
# some other exception occurred;  we don’t want to provide
# confidential error messages
self.cmd_channel.logerror(traceback.format_exc())
error = “Internal error”
self._resp = “426 %s; transfer aborted.” % error
self.close()

def handle_close(self):
“””Called when the socket is closed.”””
# If we used channel for receiving we assume that transfer is
# finished when client closes the connection, if we used channel
# for sending we have to check that all data has been sent
# (responding with 226) or not (responding with 426).
# In both cases handle_close() is automatically called by the
# underlying asynchat module.
if self.receive:
self.transfer_finished = True
else:
self.transfer_finished = len(self.producer_fifo) == 0
if self.transfer_finished:
self._resp = “226 Transfer complete.”
else:
tot_bytes = self.get_transmitted_bytes()
self._resp = “426 Transfer aborted; %d bytes transmitted.” % tot_bytes
self.close()

def close(self):
“””Close the data channel, first attempting to close any remaining
file handles.”””
if not self._closed:
self._closed = True
# RFC-959 says we must close the connection before replying
asyncore.dispatcher.close(self)
if self._resp:
self.cmd_channel.respond(self._resp)

if self.file_obj is not None and not self.file_obj.closed:
self.file_obj.close()
if self._idler is not None and not self._idler.cancelled:
self._idler.cancel()
if self.file_obj is not None:
filename = self.file_obj.name
elapsed_time = round(self.get_elapsed_time(), 3)
self.cmd_channel.log_transfer(cmd=self.cmd,
filename=self.file_obj.name,
receive=self.receive,
completed=self.transfer_finished,
elapsed=elapsed_time,
bytes=self.get_transmitted_bytes())
if self.transfer_finished:
if self.receive:
self.cmd_channel.on_file_received(filename)
else:
self.cmd_channel.on_file_sent(filename)
else:
if self.receive:
self.cmd_channel.on_incomplete_file_received(filename)
else:
self.cmd_channel.on_incomplete_file_sent(filename)
self.cmd_channel._on_dtp_close()

class ThrottledDTPHandler(DTPHandler):
“””A DTPHandler subclass which wraps sending and receiving in a data
counter and temporarily “sleeps” the channel so that you burst to no
more than x Kb/sec average.

– (int) read_limit: the maximum number of bytes to read (receive)
in one second (defaults to 0 == no limit).

– (int) write_limit: the maximum number of bytes to write (send)
in one second (defaults to 0 == no limit).

– (bool) auto_sized_buffers: this option only applies when read
and/or write limits are specified. When enabled it bumps down
the data buffer sizes so that they are never greater than read
and write limits which results in a less bursty and smoother
throughput (default: True).
“””
read_limit = 0
write_limit = 0
auto_sized_buffers = True

def __init__(self, sock_obj, cmd_channel):
DTPHandler.__init__(self, sock_obj, cmd_channel)
self._timenext = 0
self._datacount = 0
self.sleeping = False
self._throttler = None

if self.auto_sized_buffers:
if self.read_limit:
while self.ac_in_buffer_size > self.read_limit:
self.ac_in_buffer_size /= 2
if self.write_limit:
while self.ac_out_buffer_size > self.write_limit:
self.ac_out_buffer_size /= 2

def readable(self):
return not self.sleeping and DTPHandler.readable(self)

def writable(self):
return not self.sleeping and DTPHandler.writable(self)

def recv(self, buffer_size):
chunk = DTPHandler.recv(self, buffer_size)
if self.read_limit:
self._throttle_bandwidth(len(chunk), self.read_limit)
return chunk

def send(self, data):
num_sent = DTPHandler.send(self, data)
if self.write_limit:
self._throttle_bandwidth(num_sent, self.write_limit)
return num_sent

def _throttle_bandwidth(self, len_chunk, max_speed):
“””A method which counts data transmitted so that you burst to
no more than x Kb/sec average.
“””
self._datacount += len_chunk
if self._datacount >= max_speed:
self._datacount = 0
now = time.time()
sleepfor = self._timenext – now
if sleepfor > 0:
# we’ve passed bandwidth limits
def unsleep():
self.sleeping = False
self.sleeping = True
self._throttler = CallLater(sleepfor * 2, unsleep,
_errback=self.handle_error)
self._timenext = now + 1

def close(self):
if self._throttler is not None and not self._throttler.cancelled:
self._throttler.cancel()
DTPHandler.close(self)

# — producers

class FileProducer(object):
“””Producer wrapper for file[-like] objects.”””

buffer_size = 65536

def __init__(self, file, type):
“””Initialize the producer with a data_wrapper appropriate to TYPE.

– (file) file: the file[-like] object.
– (str) type: the current TYPE, ‘a’ (ASCII) or ‘i’ (binary).
“””
self.done = False
self.file = file
if type == ‘a’:
if os.linesep == ‘rn’:
self._data_wrapper = lambda x: x
else:
self._data_wrapper = lambda x: x.replace(os.linesep, ‘rn’)
elif type == ‘i’:
self._data_wrapper = lambda x: x
else:
raise TypeError(“unsupported type”)

def more(self):
“””Attempt a chunk of data of size self.buffer_size.”””
if self.done:
return ”
try:
data = self._data_wrapper(self.file.read(self.buffer_size))
except OSError, err:
raise _FileReadWriteError(err)
if not data:
self.done = True
if not self.file.closed:
self.file.close()
return data

class BufferedIteratorProducer(object):
“””Producer for iterator objects with buffer capabilities.”””
# how many times iterator.next() will be called before
# returning some data
loops = 20

def __init__(self, iterator):
self.iterator = iterator

def more(self):
“””Attempt a chunk of data from iterator by calling
its next() method different times.
“””
buffer = []
for x in xrange(self.loops):
try:
buffer.append(self.iterator.next())
except StopIteration:
break
return ”.join(buffer)

# — filesystem

class AbstractedFS(object):
“””A class used to interact with the file system, providing a
cross-platform interface compatible with both Windows and
UNIX style filesystems where all paths use “/” separator.

AbstractedFS distinguishes between “real” filesystem paths and
“virtual” ftp paths emulating a UNIX chroot jail where the user
can not escape its home directory (example: real “/home/user”
path will be seen as “/” by the client)

It also provides some utility methods and wraps around all os.*
calls involving operations against the filesystem like creating
files or removing directories.
“””

def __init__(self, root, cmd_channel):
“””
– (str) root: the user “real” home directory (e.g. ‘/home/user’)
– (instance) cmd_channel: the FTPHandler class instance
“””
# Set initial current working directory.
# By default initial cwd is set to “/” to emulate a chroot jail.
# If a different behavior is desired (e.g. initial cwd = root,
# to reflect the real filesystem) users overriding this class
# are responsible to set _cwd attribute as necessary.
self._cwd = ‘/’
self._root = root
self.cmd_channel = cmd_channel

@property
def root(self):
“””The user home directory.”””
return self._root

@property
def cwd(self):
“””The user current working directory.”””
return self._cwd

@root.setter
def root(self, path):
self._root = path

@cwd.setter
def cwd(self, path):
self._cwd = path

# — Pathname / conversion utilities

def ftpnorm(self, ftppath):
“””Normalize a “virtual” ftp pathname (tipically the raw string
coming from client) depending on the current working directory.

Example (having “/foo” as current working directory):
>>> ftpnorm(‘bar’)
‘/foo/bar’

Note: directory separators are system independent (“/”).
Pathname returned is always absolutized.
“””
if os.path.isabs(ftppath):
p = os.path.normpath(ftppath)
else:
p = os.path.normpath(os.path.join(self.cwd, ftppath))
# normalize string in a standard web-path notation having ‘/’
# as separator.
p = p.replace(“\”, “/”)
# os.path.normpath supports UNC paths (e.g. “//a/b/c”) but we
# don’t need them.  In case we get an UNC path we collapse
# redundant separators appearing at the beginning of the string
while p[:2] == ‘//’:
p = p[1:]
# Anti path traversal: don’t trust user input, in the event
# that self.cwd is not absolute, return “/” as a safety measure.
# This is for extra protection, maybe not really necessary.
if not os.path.isabs(p):
p = “/”
return p

def ftp2fs(self, ftppath):
“””Translate a “virtual” ftp pathname (tipically the raw string
coming from client) into equivalent absolute “real” filesystem
pathname.

Example (having “/home/user” as root directory):
>>> ftp2fs(“foo”)
‘/home/user/foo’

Note: directory separators are system dependent.
“””
# as far as I know, it should always be path traversal safe…
if os.path.normpath(self.root) == os.sep:
return os.path.normpath(self.ftpnorm(ftppath))
else:
p = self.ftpnorm(ftppath)[1:]
return os.path.normpath(os.path.join(self.root, p))

def fs2ftp(self, fspath):
“””Translate a “real” filesystem pathname into equivalent
absolute “virtual” ftp pathname depending on the user’s
root directory.

Example (having “/home/user” as root directory):
>>> fs2ftp(“/home/user/foo”)
‘/foo’

As for ftpnorm, directory separators are system independent
(“/”) and pathname returned is always absolutized.

On invalid pathnames escaping from user’s root directory
(e.g. “/home” when root is “/home/user”) always return “/”.
“””
if os.path.isabs(fspath):
p = os.path.normpath(fspath)
else:
p = os.path.normpath(os.path.join(self.root, fspath))
if not self.validpath(p):
return ‘/’
p = p.replace(os.sep, “/”)
p = p[len(self.root):]
if not p.startswith(‘/’):
p = ‘/’ + p
return p

def validpath(self, path):
“””Check whether the path belongs to user’s home directory.
Expected argument is a “real” filesystem pathname.

If path is a symbolic link it is resolved to check its real
destination.

Pathnames escaping from user’s root directory are considered
not valid.
“””
root = self.realpath(self.root)
path = self.realpath(path)
if not root.endswith(os.sep):
root = root + os.sep
if not path.endswith(os.sep):
path = path + os.sep
if path[0:len(root)] == root:
return True
return False

# — Wrapper methods around open() and tempfile.mkstemp

def open(self, filename, mode):
“””Open a file returning its handler.”””
return open(filename, mode)

def mkstemp(self, suffix=”, prefix=”, dir=None, mode=’wb’):
“””A wrap around tempfile.mkstemp creating a file with a unique
name.  Unlike mkstemp it returns an object with a file-like
interface.
“””
class FileWrapper:
def __init__(self, fd, name):
self.file = fd
self.name = name
def __getattr__(self, attr):
return getattr(self.file, attr)

text = not ‘b’ in mode
# max number of tries to find out a unique file name
tempfile.TMP_MAX = 50
fd, name = tempfile.mkstemp(suffix, prefix, dir, text=text)
file = os.fdopen(fd, mode)
return FileWrapper(file, name)

# — Wrapper methods around os.* calls

def chdir(self, path):
“””Change the current directory.”””
# temporarily join the specified directory to see if we have
# permissions to do so
basedir = os.getcwd()
try:
os.chdir(path)
except os.error:
raise
else:
os.chdir(basedir)
self._cwd = self.fs2ftp(path)

def mkdir(self, path):
“””Create the specified directory.”””
os.mkdir(path)

def listdir(self, path):
“””List the content of a directory.”””
return os.listdir(path)

def rmdir(self, path):
“””Remove the specified directory.”””
os.rmdir(path)

def remove(self, path):
“””Remove the specified file.”””
os.remove(path)

def rename(self, src, dst):
“””Rename the specified src file to the dst filename.”””
os.rename(src, dst)

def stat(self, path):
“””Perform a stat() system call on the given path.”””
return os.stat(path)

def lstat(self, path):
“””Like stat but does not follow symbolic links.”””
return os.lstat(path)

if not hasattr(os, ‘lstat’):
lstat = stat

# — Wrapper methods around os.path.* calls

def isfile(self, path):
“””Return True if path is a file.”””
return os.path.isfile(path)

def islink(self, path):
“””Return True if path is a symbolic link.”””
return os.path.islink(path)

def isdir(self, path):
“””Return True if path is a directory.”””
return os.path.isdir(path)

def getsize(self, path):
“””Return the size of the specified file in bytes.”””
return os.path.getsize(path)

def getmtime(self, path):
“””Return the last modified time as a number of seconds since
the epoch.”””
return os.path.getmtime(path)

def realpath(self, path):
“””Return the canonical version of path eliminating any
symbolic links encountered in the path (if they are
supported by the operating system).
“””
return os.path.realpath(path)

def lexists(self, path):
“””Return True if path refers to an existing path, including
a broken or circular symbolic link.
“””
return os.path.lexists(path)

def get_user_by_uid(self, uid):
“””Return the username associated with user id.
If this can’t be determined return raw uid instead.
On Windows just return “owner”.
“””
if pwd is not None:
try:
return pwd.getpwuid(uid).pw_name
except KeyError:
return uid
else:
return “owner”

def get_group_by_gid(self, gid):
“””Return the groupname associated with group id.
If this can’t be determined return raw gid instead.
On Windows just return “group”.
“””
if grp is not None:
try:
return grp.getgrgid(gid).gr_name
except KeyError:
return gid
else:
return “group”

if hasattr(os, ‘readlink’):
def readlink(self, path):
“””Return a string representing the path to which a
symbolic link points.
“””
return os.readlink(path)

# — Listing utilities

def get_list_dir(self, path):
“”””Return an iterator object that yields a directory listing
in a form suitable for LIST command.
“””
if self.isdir(path):
listing = self.listdir(path)
listing.sort()
return self.format_list(path, listing)
# if path is a file or a symlink we return information about it
else:
basedir, filename = os.path.split(path)
self.lstat(path)  # raise exc in case of problems
return self.format_list(basedir, [filename])

def format_list(self, basedir, listing, ignore_err=True):
“””Return an iterator object that yields the entries of given
directory emulating the “/bin/ls -lA” UNIX command output.

– (str) basedir: the absolute dirname.
– (list) listing: the names of the entries in basedir
– (bool) ignore_err: when False raise exception if os.lstat()
call fails.

On platforms which do not support the pwd and grp modules (such
as Windows), ownership is printed as “owner” and “group” as a
default, and number of hard links is always “1”. On UNIX
systems, the actual owner, group, and number of links are
printed.

This is how output appears to client:

-rw-rw-rw-   1 owner   group    7045120 Sep 02  3:47 music.mp3
drwxrwxrwx   1 owner   group          0 Aug 31 18:50 e-books
-rw-rw-rw-   1 owner   group        380 Sep 02  3:40 module.py
“””
if self.cmd_channel.use_gmt_times:
timefunc = time.gmtime
else:
timefunc = time.localtime
for basename in listing:
file = os.path.join(basedir, basename)
try:
st = self.lstat(file)
except os.error:
if ignore_err:
continue
raise
perms = _filemode(st.st_mode)  # permissions
nlinks = st.st_nlink  # number of links to inode
if not nlinks:  # non-posix system, let’s use a bogus value
nlinks = 1
size = st.st_size  # file size
uname = self.get_user_by_uid(st.st_uid)
gname = self.get_group_by_gid(st.st_gid)
try:
mtime = time.strftime(“%b %d %H:%M”, timefunc(st.st_mtime))
except ValueError:
# It could be raised if last mtime happens to be too
# old (prior to year 1900) in which case we return
# the current time as last mtime.
mtime = time.strftime(“%b %d %H:%M”, timefunc())
# if the file is a symlink, resolve it, e.g. “symlink -> realfile”
if stat.S_ISLNK(st.st_mode) and hasattr(self, ‘readlink’):
basename = basename + ” -> ” + self.readlink(file)

# formatting is matched with proftpd ls output
yield “%s %3s %-8s %-8s %8s %s %srn” % (perms, nlinks, uname, gname,
size, mtime, basename)

def format_mlsx(self, basedir, listing, perms, facts, ignore_err=True):
“””Return an iterator object that yields the entries of a given
directory or of a single file in a form suitable with MLSD and
MLST commands.

Every entry includes a list of “facts” referring the listed
element.  See RFC-3659, chapter 7, to see what every single
fact stands for.

– (str) basedir: the absolute dirname.
– (list) listing: the names of the entries in basedir
– (str) perms: the string referencing the user permissions.
– (str) facts: the list of “facts” to be returned.
– (bool) ignore_err: when False raise exception if os.stat()
call fails.

Note that “facts” returned may change depending on the platform
and on what user specified by using the OPTS command.

This is how output could appear to the client issuing
a MLSD request:

type=file;size=156;perm=r;modify=20071029155301;unique=801cd2; music.mp3
type=dir;size=0;perm=el;modify=20071127230206;unique=801e33; ebooks
type=file;size=211;perm=r;modify=20071103093626;unique=801e32; module.py
“””
if self.cmd_channel.use_gmt_times:
timefunc = time.gmtime
else:
timefunc = time.localtime
permdir = ”.join([x for x in perms if x not in ‘arw’])
permfile = ”.join([x for x in perms if x not in ‘celmp’])
if (‘w’ in perms) or (‘a’ in perms) or (‘f’ in perms):
permdir += ‘c’
if ‘d’ in perms:
permdir += ‘p’
for basename in listing:
file = os.path.join(basedir, basename)
retfacts = dict()
# in order to properly implement ‘unique’ fact (RFC-3659,
# chapter 7.5.2) we are supposed to follow symlinks, hence
# use os.stat() instead of os.lstat()
try:
st = self.stat(file)
except OSError:
if ignore_err:
continue
raise
# type + perm
if stat.S_ISDIR(st.st_mode):
if ‘type’ in facts:
if basename == ‘.’:
retfacts[‘type’] = ‘cdir’
elif basename == ‘..’:
retfacts[‘type’] = ‘pdir’
else:
retfacts[‘type’] = ‘dir’
if ‘perm’ in facts:
retfacts[‘perm’] = permdir
else:
if ‘type’ in facts:
retfacts[‘type’] = ‘file’
if ‘perm’ in facts:
retfacts[‘perm’] = permfile
if ‘size’ in facts:
retfacts[‘size’] = st.st_size  # file size
# last modification time
if ‘modify’ in facts:
try:
retfacts[‘modify’] = time.strftime(“%Y%m%d%H%M%S”,
timefunc(st.st_mtime))
# it could be raised if last mtime happens to be too old
# (prior to year 1900)
except ValueError:
pass
if ‘create’ in facts:
# on Windows we can provide also the creation time
try:
retfacts[‘create’] = time.strftime(“%Y%m%d%H%M%S”,
timefunc(st.st_ctime))
except ValueError:
pass
# UNIX only
if ‘unix.mode’ in facts:
retfacts[‘unix.mode’] = oct(st.st_mode & 0777)
if ‘unix.uid’ in facts:
retfacts[‘unix.uid’] = st.st_uid
if ‘unix.gid’ in facts:
retfacts[‘unix.gid’] = st.st_gid

# We provide unique fact (see RFC-3659, chapter 7.5.2) on
# posix platforms only; we get it by mixing st_dev and
# st_ino values which should be enough for granting an
# uniqueness for the file listed.
# The same approach is used by pure-ftpd.
# Implementors who want to provide unique fact on other
# platforms should use some platform-specific method (e.g.
# on Windows NTFS filesystems MTF records could be used).
if ‘unique’ in facts:
retfacts[‘unique’] = “%xg%x” % (st.st_dev, st.st_ino)

# facts can be in any order but we sort them by name
factstring = “”.join([“%s=%s;” % (x, retfacts[x])
for x in sorted(retfacts.keys())])
yield “%s %srn” % (factstring, basename)

# — FTP

class FTPHandler(object, asynchat.async_chat):
“””Implements the FTP server Protocol Interpreter (see RFC-959),
handling commands received from the client on the control channel.

All relevant session information is stored in class attributes
reproduced below and can be modified before instantiating this
class.

– (int) timeout:
The timeout which is the maximum time a remote client may spend
between FTP commands. If the timeout triggers, the remote client
will be kicked off.  Defaults to 300 seconds.

– (str) banner: the string sent when client connects.

– (int) max_login_attempts:
the maximum number of wrong authentications before disconnecting
the client (default 3).

– (bool)permit_foreign_addresses:
FTP site-to-site transfer feature: also referenced as “FXP” it
permits for transferring a file between two remote FTP servers
without the transfer going through the client’s host (not
recommended for security reasons as described in RFC-2577).
Having this attribute set to False means that all data
connections from/to remote IP addresses which do not match the
client’s IP address will be dropped (defualt False).

– (bool) permit_privileged_ports:
set to True if you want to permit active data connections (PORT)
over privileged ports (not recommended, defaulting to False).

– (str) masquerade_address:
the “masqueraded” IP address to provide along PASV reply when
pyftpdlib is running behind a NAT or other types of gateways.
When configured pyftpdlib will hide its local address and
instead use the public address of your NAT (default None).

– (dict) masquerade_address_map:
in case the server has multiple IP addresses which are all
behind a NAT router, you may wish to specify individual
masquerade_addresses for each of them. The map expects a
dictionary containing private IP addresses as keys, and their
corresponding public (masquerade) addresses as values.

– (list) passive_ports:
what ports the ftpd will use for its passive data transfers.
Value expected is a list of integers (e.g. range(60000, 65535)).
When configured pyftpdlib will no longer use kernel-assigned
random ports (default None).

– (bool) use_gmt_times:
when True causes the server to report all ls and MDTM times in
GMT and not local time (default True).

– (bool) tcp_no_delay: controls the use of the TCP_NODELAY socket
option which disables the Nagle algorithm resulting in
significantly better performances (default True on all systems
where it is supported).

All relevant instance attributes initialized when client connects
are reproduced below.  You may be interested in them in case you
want to subclass the original FTPHandler.

– (bool) authenticated: True if client authenticated himself.
– (str) username: the name of the connected user (if any).
– (int) attempted_logins: number of currently attempted logins.
– (str) current_type: the current transfer type (default “a”)
– (int) af: the connection’s address family (IPv4/IPv6)
– (instance) server: the FTPServer class instance.
– (instance) data_channel: the data channel instance (if any).
“””
# these are overridable defaults

# default classes
authorizer = DummyAuthorizer()
active_dtp = ActiveDTP
passive_dtp = PassiveDTP
dtp_handler = DTPHandler
abstracted_fs = AbstractedFS
proto_cmds = proto_cmds

# session attributes (explained in the docstring)
timeout = 300
banner = “pyftpdlib %s ready.” % __ver__
max_login_attempts = 3
permit_foreign_addresses = False
permit_privileged_ports = False
masquerade_address = None
masquerade_address_map = {}
passive_ports = None
use_gmt_times = True
tcp_no_delay = hasattr(socket, “TCP_NODELAY”)

def __init__(self, conn, server):
“””Initialize the command channel.

– (instance) conn: the socket object instance of the newly
established connection.
– (instance) server: the ftp server class instance.
“””
# public session attributes
self.server = server
self.fs = None
self.authenticated = False
self.username = “”
self.password = “”
self.attempted_logins = 0
self.sleeping = False
self.data_channel = None
self.remote_ip = “”
self.remote_port = “”

# private session attributes
self._last_response = “”
self._current_type = ‘a’
self._restart_position = 0
self._quit_pending = False
self._af = -1
self._in_buffer = []
self._in_buffer_len = 0
self._epsvall = False
self._dtp_acceptor = None
self._dtp_connector = None
self._in_dtp_queue = None
self._out_dtp_queue = None
self._closed = False
self._extra_feats = []
self._current_facts = [‘type’, ‘perm’, ‘size’, ‘modify’]
self._rnfr = None
if self.timeout:
self._idler = CallLater(self.timeout, self.handle_timeout,
_errback=self.handle_error)
else:
self._idler = None
if os.name == ‘posix’:
self._current_facts.append(‘unique’)
self._available_facts = self._current_facts[:]
if pwd and grp:
self._available_facts += [‘unix.mode’, ‘unix.uid’, ‘unix.gid’]
if os.name == ‘nt’:
self._available_facts.append(‘create’)

try:
asynchat.async_chat.__init__(self, conn)
except socket.error, err:
if err[0] == errno.EINVAL:
# http://code.google.com/p/pyftpdlib/issues/detail?id=143
return
self.handle_error()
return
self.set_terminator(“rn”)

# connection properties
try:
self.remote_ip, self.remote_port = self.socket.getpeername()[:2]
except socket.error, err:
# A race condition  may occur if the other end is closing
# before we can get the peername, hence ENOTCONN (see issue
# #100) while EINVAL can occur on OSX (see issue #143).
self.connected = False
if err[0] in (errno.ENOTCONN, errno.EINVAL):
self.close()
else:
self.handle_error()
return

if hasattr(self.socket, ‘family’):
self._af = self.socket.family
else:  # python < 2.5
ip, port = self.socket.getsockname()[:2]
self._af = socket.getaddrinfo(ip, port, socket.AF_UNSPEC,
socket.SOCK_STREAM)[0][0]

# try to handle urgent data inline
try:
self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_OOBINLINE, 1)
except socket.error:
pass

# disable Nagle algorithm for the control socket only, resulting
# in significantly better performances
if self.tcp_no_delay:
try:
self.socket.setsockopt(socket.SOL_TCP, socket.TCP_NODELAY, 1)
except socket.error:
pass

# remove this instance from asyncore socket_map
if not self.connected:
self.close()

def handle(self):
“””Return a 220 ‘ready’ response to the client over the command
channel.
“””
if len(self.banner) <= 75:
self.respond(“220 %s” % str(self.banner))
else:
self.push(‘220-%srn’ % str(self.banner))
self.respond(‘220 ‘)

def handle_max_cons(self):
“””Called when limit for maximum number of connections is reached.”””
msg = “Too many connections. Service temporary unavailable.”
self.respond(“421 %s” % msg)
self.log(msg)
# If self.push is used, data could not be sent immediately in
# which case a new “loop” will occur exposing us to the risk of
# accepting new connections.  Since this could cause asyncore to
# run out of fds (…and exposes the server to DoS attacks), we
# immediately close the channel by using close() instead of
# close_when_done(). If data has not been sent yet client will
# be silently disconnected.
self.close()

def handle_max_cons_per_ip(self):
“””Called when too many clients are connected from the same IP.”””
msg = “Too many connections from the same IP address.”
self.respond(“421 %s” % msg)
self.log(msg)
self.close_when_done()

def handle_timeout(self):
“””Called when client does not send any command within the time
specified in <timeout> attribute.”””
msg = “Control connection timed out.”
self.log(msg)
self.respond(“421 ” + msg)
self.close_when_done()

# — asyncore / asynchat overridden methods

def readable(self):
return not self.sleeping and asynchat.async_chat.readable(self)

def writable(self):
return not self.sleeping and asynchat.async_chat.writable(self)

def collect_incoming_data(self, data):
“””Read incoming data and append to the input buffer.”””
self._in_buffer.append(data)
self._in_buffer_len += len(data)
# Flush buffer if it gets too long (possible DoS attacks).
# RFC-959 specifies that a 500 response could be given in
# such cases
buflimit = 2048
if self._in_buffer_len > buflimit:
self.respond(‘500 Command too long.’)
self.log(‘Command received exceeded buffer limit of %s.’ % (buflimit))
self._in_buffer = []
self._in_buffer_len = 0

def found_terminator(self):
r”””Called when the incoming data stream matches the rn
terminator.
“””
if self._idler is not None and not self._idler.cancelled:
self._idler.reset()

line = ”.join(self._in_buffer)
self._in_buffer = []
self._in_buffer_len = 0

cmd = line.split(‘ ‘)[0].upper()
arg = line[len(cmd)+1:]
if cmd == “SITE” and arg:
cmd = “SITE %s” % arg.split(‘ ‘)[0].upper()
arg = line[len(cmd)+1:]

if cmd != ‘PASS’:
self.logline(“<== %s” % line)
else:
self.logline(“<== %s %s” % (line.split(‘ ‘)[0], ‘*’ * 6))

# Recognize those commands having a “special semantic”. They
# should be sent by following the RFC-959 procedure of sending
# Telnet IP/Synch sequence (chr 242 and 255) as OOB data but
# since many ftp clients don’t do it correctly we check the
# last 4 characters only.
if not cmd in self.proto_cmds:
if cmd[-4:] in (‘ABOR’, ‘STAT’, ‘QUIT’):
cmd = cmd[-4:]
else:
msg = ‘Command “%s” not understood.’ % cmd
self.respond(‘500 ‘ + msg)
if cmd:
self.log_cmd(cmd, arg, 500, msg)
return

if not arg and self.proto_cmds[cmd][‘arg’] == True:
msg = “Syntax error: command needs an argument.”
self.respond(“501 ” + msg)
self.log_cmd(cmd, “”, 501, msg)
return
if arg and self.proto_cmds[cmd][‘arg’] == False:
msg = “Syntax error: command does not accept arguments.”
self.respond(“501 ” + msg)
self.log_cmd(cmd, arg, 501, msg)
return

if not self.authenticated:
if self.proto_cmds[cmd][‘auth’] or (cmd == ‘STAT’ and arg):
msg = “Log in with USER and PASS first.”
self.respond(“530 ” + msg)
self.log_cmd(cmd, arg, 530, msg)
else:
# call the proper ftp_* method
self.process_command(cmd, arg)
return
else:
if (cmd == ‘STAT’) and not arg:
self.ftp_STAT(”)
return

# for file-system related commands check whether real path
# destination is valid
if self.proto_cmds[cmd][‘perm’] and (cmd != ‘STOU’):
if cmd in (‘CWD’, ‘XCWD’):
arg = self.fs.ftp2fs(arg or ‘/’)
elif cmd in (‘CDUP’, ‘XCUP’):
arg = self.fs.ftp2fs(‘..’)
elif cmd == ‘LIST’:
if arg.lower() in (‘-a’, ‘-l’, ‘-al’, ‘-la’):
arg = self.fs.ftp2fs(self.fs.cwd)
else:
arg = self.fs.ftp2fs(arg or self.fs.cwd)
elif cmd == ‘STAT’:
if glob.has_magic(arg):
msg = ‘Globbing not supported.’
self.respond(‘550 ‘ + msg)
self.log_cmd(cmd, arg, 550, msg)
return
arg = self.fs.ftp2fs(arg or self.fs.cwd)
else:  # LIST, NLST, MLSD, MLST
arg = self.fs.ftp2fs(arg or self.fs.cwd)

if not self.fs.validpath(arg):
line = self.fs.fs2ftp(arg)
msg = ‘”%s” points to a path which is outside ‘
“the user’s root directory” % line
self.respond(“550 %s.” % msg)
self.log_cmd(cmd, arg, 550, msg)
return

# check permission
perm = self.proto_cmds[cmd][‘perm’]
if perm is not None and cmd != ‘STOU’:
if not self.authorizer.has_perm(self.username, perm, arg):
msg = “Not enough privileges.”
self.respond(“550 ” + msg)
self.log_cmd(cmd, arg, 550, msg)
return

# call the proper ftp_* method
self.process_command(cmd, arg)

def process_command(self, cmd, *args, **kwargs):
“””Process command by calling the corresponding ftp_* class
method (e.g. for received command “MKD pathname”, ftp_MKD()
method is called with “pathname” as the argument).
“””
self._last_response = “”
method = getattr(self, ‘ftp_’ + cmd.replace(‘ ‘, ‘_’))
method(*args, **kwargs)
if self._last_response:
code = int(self._last_response[:3])
resp = self._last_response[4:]
self.log_cmd(cmd, args[0], code, resp)

def handle_expt(self):
“””Called when there is out of band (OOB) data to be read.
This might happen in case of such clients strictly following
the RFC-959 directives of sending Telnet IP and Synch as OOB
data before issuing ABOR, STAT and QUIT commands.
It should never be called since the SO_OOBINLINE option is
enabled except on some systems like FreeBSD where it doesn’t
seem to have effect.
“””
if hasattr(socket, ‘MSG_OOB’):
try:
data = self.socket.recv(1024, socket.MSG_OOB)
except socket.error, why:
if why[0] == errno.EINVAL:
return
else:
self._in_buffer.append(data)
return
self.log(“Can’t handle OOB data.”)
self.close()

def handle_error(self):
try:
raise
except (KeyboardInterrupt, SystemExit, asyncore.ExitNow):
raise
except socket.error, err:
# fixes around various bugs:
# – http://bugs.python.org/issue1736101
# – http://code.google.com/p/pyftpdlib/issues/detail?id=104
# – http://code.google.com/p/pyftpdlib/issues/detail?id=109
if err[0] in (errno.ECONNRESET, errno.ENOTCONN, errno.ESHUTDOWN,
errno.ECONNABORTED, errno.EPIPE, errno.EBADF):
self.handle_close()
return
else:
self.logerror(traceback.format_exc())
except:
self.logerror(traceback.format_exc())
self.close()

def handle_close(self):
self.close()

def close(self):
“””Close the current channel disconnecting the client.”””
if not self._closed:
self._closed = True
asynchat.async_chat.close(self)

self._shutdown_connecting_dtp()

if self.data_channel is not None:
self.data_channel.close()
del self.data_channel

del self._out_dtp_queue
del self._in_dtp_queue

if self._idler is not None and not self._idler.cancelled:
self._idler.cancel()

# remove client IP address from ip map
if self.remote_ip in self.server.ip_map:
self.server.ip_map.remove(self.remote_ip)

if self.fs is not None:
self.fs.cmd_channel = None
self.log(“Disconnected.”)

def _shutdown_connecting_dtp(self):
“””Close any ActiveDTP or PassiveDTP instance waiting to
establish a connection (passive or active).
“””
if self._dtp_acceptor is not None:
self._dtp_acceptor.close()
self._dtp_acceptor = None
if self._dtp_connector is not None:
self._dtp_connector.close()
self._dtp_connector = None

# — public callbacks
# Note: to run a time consuming task make sure to use a separate
# process or thread (see FAQs).

def on_file_sent(self, file):
“””Called every time a file has been succesfully sent.
“file” is the absolute name of the file just being sent.
“””

def on_file_received(self, file):
“””Called every time a file has been succesfully received.
“file” is the absolute name of the file just being received.
“””

def on_incomplete_file_sent(self, file):
“””Called every time a file has not been entirely sent.
(e.g. ABOR during transfer or client disconnected).
“file” is the absolute name of that file.
“””

def on_incomplete_file_received(self, file):
“””Called every time a file has not been entirely received
(e.g. ABOR during transfer or client disconnected).
“file” is the absolute name of that file.
“””

def on_login(self, username):
“””Called on user login.”””

def on_logout(self, username):
“””Called when user logs out due to QUIT or USER issued twice.”””

# — internal callbacks

def _on_dtp_connection(self):
“””Called every time data channel connects, either active or
passive.

Incoming and outgoing queues are checked for pending data.
If outbound data is pending, it is pushed into the data channel.
If awaiting inbound data, the data channel is enabled for
receiving.
“””
# Close accepting DTP only. By closing ActiveDTP DTPHandler
# would receive a closed socket object.
#self._shutdown_connecting_dtp()
if self._dtp_acceptor is not None:
self._dtp_acceptor.close()
self._dtp_acceptor = None

# stop the idle timer as long as the data transfer is not finished
if self._idler is not None and not self._idler.cancelled:
self._idler.cancel()

# check for data to send
if self._out_dtp_queue is not None:
data, isproducer, file, cmd = self._out_dtp_queue
self._out_dtp_queue = None
self.data_channel.cmd = cmd
if file:
self.data_channel.file_obj = file
try:
if not isproducer:
self.data_channel.push(data)
else:
self.data_channel.push_with_producer(data)
if self.data_channel is not None:
self.data_channel.close_when_done()
except:
# dealing with this exception is up to DTP (see bug #84)
self.data_channel.handle_error()

# check for data to receive
elif self._in_dtp_queue is not None:
file, cmd = self._in_dtp_queue
self.data_channel.file_obj = file
self._in_dtp_queue = None
self.data_channel.enable_receiving(self._current_type, cmd)

def _on_dtp_close(self):
“””Called every time the data channel is closed.”””
self.data_channel = None
if self._quit_pending:
self.close()
elif self.timeout:
# data transfer finished, restart the idle timer
self._idler = CallLater(self.timeout, self.handle_timeout,
_errback=self.handle_error)

# — utility

def respond(self, resp):
“””Send a response to the client using the command channel.”””
self._last_response = resp
self.push(resp + ‘rn’)
self.logline(‘==> %s’ % resp)

def push_dtp_data(self, data, isproducer=False, file=None, cmd=None):
“””Pushes data into the data channel.

It is usually called for those commands requiring some data to
be sent over the data channel (e.g. RETR).
If data channel does not exist yet, it queues the data to send
later; data will then be pushed into data channel when
_on_dtp_connection() will be called.

– (str/classobj) data: the data to send which may be a string
or a producer object).
– (bool) isproducer: whether treat data as a producer.
– (file) file: the file[-like] object to send (if any).
“””
if self.data_channel is not None:
self.respond(“125 Data connection already open. Transfer starting.”)
if file:
self.data_channel.file_obj = file
try:
if not isproducer:
self.data_channel.push(data)
else:
self.data_channel.push_with_producer(data)
if self.data_channel is not None:
self.data_channel.cmd = cmd
self.data_channel.close_when_done()
except:
# dealing with this exception is up to DTP (see bug #84)
self.data_channel.handle_error()
else:
self.respond(“150 File status okay. About to open data connection.”)
self._out_dtp_queue = (data, isproducer, file, cmd)

def flush_account(self):
“””Flush account information by clearing attributes that need
to be reset on a REIN or new USER command.
“””
self._shutdown_connecting_dtp()
# if there’s a transfer in progress RFC-959 states we are
# supposed to let it finish
if self.data_channel is not None:
if not self.data_channel.transfer_in_progress():
self.data_channel.close()
self.data_channel = None

username = self.username
self.authenticated = False
self.username = “”
self.password = “”
self.attempted_logins = 0
self._current_type = ‘a’
self._restart_position = 0
self._quit_pending = False
self.sleeping = False
self._in_dtp_queue = None
self._rnfr = None
self._out_dtp_queue = None
if username:
self.on_logout(username)

def run_as_current_user(self, function, *args, **kwargs):
“””Execute a function impersonating the current logged-in user.”””
self.authorizer.impersonate_user(self.username, self.password)
try:
return function(*args, **kwargs)
finally:
self.authorizer.terminate_impersonation(self.username)

# — logging wrappers

def log(self, msg):
“””Log a message, including additional identifying session data.”””
log(“[%s]@%s:%s %s” % (self.username, self.remote_ip,
self.remote_port, msg))

def logline(self, msg):
“””Log a line including additional indentifying session data.”””
logline(“%s:%s %s” % (self.remote_ip, self.remote_port, msg))

def logerror(self, msg):
“””Log unhandled exceptions.”””
logerror(msg)

def log_cmd(self, cmd, arg, respcode, respstr):
“””Log commands and responses in a standardized format.

– (str) cmd:
the command sent by client

– (str) arg:
the command argument sent by client.
For filesystem commands such as DELE, MKD, etc. this is
already represented as an absolute real filesystem path
like “/home/user/file.ext”.

– (int) respcode:
the response code as being sent by server. Response codes
starting with 4xx or 5xx are returned if the command has
been rejected for some reason.

– (str) respstr:
the response string as being sent by server.

By default only DELE, RMD, RNFR, RNTO, MKD commands are logged
and the output is redirected to self.log method (the main logger).

Can be overridden to provide alternate formats or to log
further commands.
“””
if cmd in (“DELE”, “RMD”, “RNFR”, “RNTO”, “MKD”):
line = ‘”%s” %s’ % (‘ ‘.join([cmd, str(arg)]).strip(), respcode)
self.log(line)

def log_transfer(self, cmd, filename, receive, completed, elapsed, bytes):
“””Log all file transfers in a standardized format.

– (str) cmd:
the original command who caused the tranfer.

– (str) filename:
the absolutized name of the file on disk.

– (bool) receive:
True if the transfer was used for client uploading (STOR,
STOU, APPE), False otherwise (RETR).

– (bool) completed:
True if the file has been entirely sent, else False.

– (float) elapsed:
transfer elapsed time in seconds.

– (int) bytes:
number of bytes transmitted.
“””
line = ‘”%s %s” completed=%s bytes=%s seconds=%s’ %
(cmd, filename, completed and 1 or 0, bytes, elapsed)
self.log(line)

# — connection

def _make_eport(self, ip, port):
“””Establish an active data channel with remote client which
issued a PORT or EPRT command.
“””
# FTP bounce attacks protection: according to RFC-2577 it’s
# recommended to reject PORT if IP address specified in it
# does not match client IP address.
remote_ip = self.remote_ip
if remote_ip.startswith(‘::ffff:’):
# In this scenario, the server has an IPv6 socket, but
# the remote client is using IPv4 and its address is
# represented as an IPv4-mapped IPv6 address which
# looks like this ::ffff:151.12.5.65, see:
# http://en.wikipedia.org/wiki/IPv6#IPv4-mapped_addresses
# http://tools.ietf.org/html/rfc3493.html#section-3.7
# We truncate the first bytes to make it look like a
# common IPv4 address.
remote_ip = remote_ip[7:]
if not self.permit_foreign_addresses and ip != remote_ip:
self.log(“Rejected data connection to foreign address %s:%s.”
% (ip, port))
self.respond(“501 Can’t connect to a foreign address.”)
return

# …another RFC-2577 recommendation is rejecting connections
# to privileged ports (< 1024) for security reasons.
if not self.permit_privileged_ports and port < 1024:
self.log(‘PORT against the privileged port “%s” refused.’ % port)
self.respond(“501 Can’t connect over a privileged port.”)
return

# close establishing DTP instances, if any
self._shutdown_connecting_dtp()

if self.data_channel is not None:
self.data_channel.close()
self.data_channel = None

# make sure we are not hitting the max connections limit
if self.server.max_cons:
if len(asyncore.socket_map) >= self.server.max_cons:
msg = “Too many connections. Can’t open data channel.”
self.respond(“425 %s” %msg)
self.log(msg)
return

# open data channel
self._dtp_connector = self.active_dtp(ip, port, self)

def _make_epasv(self, extmode=False):
“””Initialize a passive data channel with remote client which
issued a PASV or EPSV command.
If extmode argument is True we assume that client issued EPSV in
which case extended passive mode will be used (see RFC-2428).
“””
# close establishing DTP instances, if any
self._shutdown_connecting_dtp()

# close established data connections, if any
if self.data_channel is not None:
self.data_channel.close()
self.data_channel = None

# make sure we are not hitting the max connections limit
if self.server.max_cons:
if len(asyncore.socket_map) >= self.server.max_cons:
msg = “Too many connections. Can’t open data channel.”
self.respond(“425 %s” %msg)
self.log(msg)
return

# open data channel
self._dtp_acceptor = self.passive_dtp(self, extmode)

def ftp_PORT(self, line):
“””Start an active data channel by using IPv4.”””
if self._epsvall:
self.respond(“501 PORT not allowed after EPSV ALL.”)
return
# Parse PORT request for getting IP and PORT.
# Request comes in as:
# > h1,h2,h3,h4,p1,p2
# …where the client’s IP address is h1.h2.h3.h4 and the TCP
# port number is (p1 * 256) + p2.
try:
addr = map(int, line.split(‘,’))
if len(addr) != 6:
raise ValueError
for x in addr[:4]:
if not 0 <= x <= 255:
raise ValueError
ip = ‘%d.%d.%d.%d’ % tuple(addr[:4])
port = (addr[4] * 256) + addr[5]
if not 0 <= port <= 65535:
raise ValueError
except (ValueError, OverflowError):
self.respond(“501 Invalid PORT format.”)
return
self._make_eport(ip, port)

def ftp_EPRT(self, line):
“””Start an active data channel by choosing the network protocol
to use (IPv4/IPv6) as defined in RFC-2428.
“””
if self._epsvall:
self.respond(“501 EPRT not allowed after EPSV ALL.”)
return
# Parse EPRT request for getting protocol, IP and PORT.
# Request comes in as:
# <d>proto<d>ip<d>port<d>
# …where <d> is an arbitrary delimiter character (usually “|”) and
# <proto> is the network protocol to use (1 for IPv4, 2 for IPv6).
try:
af, ip, port = line.split(line[0])[1:-1]
port = int(port)
if not 0 <= port <= 65535:
raise ValueError
except (ValueError, IndexError, OverflowError):
self.respond(“501 Invalid EPRT format.”)
return

if af == “1”:
if self._af != socket.AF_INET:
self.respond(‘522 Network protocol not supported (use 2).’)
else:
try:
octs = map(int, ip.split(‘.’))
if len(octs) != 4:
raise ValueError
for x in octs:
if not 0 <= x <= 255:
raise ValueError
except (ValueError, OverflowError):
self.respond(“501 Invalid EPRT format.”)
else:
self._make_eport(ip, port)
elif af == “2”:
if self._af == socket.AF_INET:
self.respond(‘522 Network protocol not supported (use 1).’)
else:
self._make_eport(ip, port)
else:
if self._af == socket.AF_INET:
self.respond(‘501 Unknown network protocol (use 1).’)
else:
self.respond(‘501 Unknown network protocol (use 2).’)

def ftp_PASV(self, line):
“””Start a passive data channel by using IPv4.”””
if self._epsvall:
self.respond(“501 PASV not allowed after EPSV ALL.”)
return
self._make_epasv(extmode=False)

def ftp_EPSV(self, line):
“””Start a passive data channel by using IPv4 or IPv6 as defined
in RFC-2428.
“””
# RFC-2428 specifies that if an optional parameter is given,
# we have to determine the address family from that otherwise
# use the same address family used on the control connection.
# In such a scenario a client may use IPv4 on the control channel
# and choose to use IPv6 for the data channel.
# But how could we use IPv6 on the data channel without knowing
# which IPv6 address to use for binding the socket?
# Unfortunately RFC-2428 does not provide satisfing information
# on how to do that.  The assumption is that we don’t have any way
# to know wich address to use, hence we just use the same address
# family used on the control connection.
if not line:
self._make_epasv(extmode=True)
# IPv4
elif line == “1”:
if self._af != socket.AF_INET:
self.respond(‘522 Network protocol not supported (use 2).’)
else:
self._make_epasv(extmode=True)
# IPv6
elif line == “2”:
if self._af == socket.AF_INET:
self.respond(‘522 Network protocol not supported (use 1).’)
else:
self._make_epasv(extmode=True)
elif line.lower() == ‘all’:
self._epsvall = True
self.respond(‘220 Other commands other than EPSV are now disabled.’)
else:
if self._af == socket.AF_INET:
self.respond(‘501 Unknown network protocol (use 1).’)
else:
self.respond(‘501 Unknown network protocol (use 2).’)

def ftp_QUIT(self, line):
“””Quit the current session disconnecting the client.”””
if self.authenticated:
msg_quit = self.authorizer.get_msg_quit(self.username)
else:
msg_quit = “Goodbye.”
if len(msg_quit) <= 75:
self.respond(“221 %s” % msg_quit)
else:
self.push(“221-%srn” % msg_quit)
self.respond(“221 “)

# From RFC-959:
# If file transfer is in progress, the connection must remain
# open for result response and the server will then close it.
# We also stop responding to any further command.
if self.data_channel:
self._quit_pending = True
self.sleeping = True
else:
self._shutdown_connecting_dtp()
self.close_when_done()
if self.username:
self.on_logout(self.username)

# — data transferring

def ftp_LIST(self, path):
“””Return a list of files in the specified directory to the
client.
“””
# – If no argument, fall back on cwd as default.
# – Some older FTP clients erroneously issue /bin/ls-like LIST
#   formats in which case we fall back on cwd as default.
line = self.fs.fs2ftp(path)
try:
iterator = self.run_as_current_user(self.fs.get_list_dir, path)
except OSError, err:
why = _strerror(err)
self.respond(‘550 %s.’ % why)
else:
producer = BufferedIteratorProducer(iterator)
self.push_dtp_data(producer, isproducer=True, cmd=”LIST”)

def ftp_NLST(self, path):
“””Return a list of files in the specified directory in a
compact form to the client.
“””
line = self.fs.fs2ftp(path)
try:
if self.fs.isdir(path):
listing = self.run_as_current_user(self.fs.listdir, path)
else:
# if path is a file we just list its name
self.fs.lstat(path)  # raise exc in case of problems
listing = [os.path.basename(path)]
except OSError, err:
self.respond(‘550 %s.’ % _strerror(err))
else:
data = ”
if listing:
listing.sort()
data = ‘rn’.join(listing) + ‘rn’
self.push_dtp_data(data, cmd=”NLST”)

# — MLST and MLSD commands

# The MLST and MLSD commands are intended to standardize the file and
# directory information returned by the server-FTP process.  These
# commands differ from the LIST command in that the format of the
# replies is strictly defined although extensible.

def ftp_MLST(self, path):
“””Return information about a pathname in a machine-processable
form as defined in RFC-3659.
“””
line = self.fs.fs2ftp(path)
basedir, basename = os.path.split(path)
perms = self.authorizer.get_perms(self.username)
try:
iterator = self.run_as_current_user(self.fs.format_mlsx, basedir,
[basename], perms, self._current_facts, ignore_err=False)
data = ”.join(iterator)
except OSError, err:
self.respond(‘550 %s.’ % _strerror(err))
else:
# since TVFS is supported (see RFC-3659 chapter 6), a fully
# qualified pathname should be returned
data = data.split(‘ ‘)[0] + ‘ %srn’ % line
# response is expected on the command channel
self.push(‘250-Listing “%s”:rn’ % line)
# the fact set must be preceded by a space
self.push(‘ ‘ + data)
self.respond(‘250 End MLST.’)

def ftp_MLSD(self, path):
“””Return contents of a directory in a machine-processable form
as defined in RFC-3659.
“””
line = self.fs.fs2ftp(path)
# RFC-3659 requires 501 response code if path is not a directory
if not self.fs.isdir(path):
self.respond(“501 No such directory.”)
return
try:
listing = self.run_as_current_user(self.fs.listdir, path)
except OSError, err:
why = _strerror(err)
self.respond(‘550 %s.’ % why)
else:
perms = self.authorizer.get_perms(self.username)
iterator = self.fs.format_mlsx(path, listing, perms,
self._current_facts)
producer = BufferedIteratorProducer(iterator)
self.push_dtp_data(producer, isproducer=True, cmd=”MLSD”)

def ftp_RETR(self, file):
“””Retrieve the specified file (transfer from the server to the
client)
“””
line = self.fs.fs2ftp(file)
rest_pos = self._restart_position
self._restart_position = 0
try:
fd = self.run_as_current_user(self.fs.open, file, ‘rb’)
except IOError, err:
why = _strerror(err)
self.respond(‘550 %s.’ % why)
return

if rest_pos:
# Make sure that the requested offset is valid (within the
# size of the file being resumed).
# According to RFC-1123 a 554 reply may result in case that
# the existing file cannot be repositioned as specified in
# the REST.
ok = 0
try:
if rest_pos > self.fs.getsize(file):
raise ValueError
fd.seek(rest_pos)
ok = 1
except ValueError:
why = “Invalid REST parameter”
except IOError, err:
why = _strerror(err)
if not ok:
self.respond(‘554 %s’ %why)
return
producer = FileProducer(fd, self._current_type)
self.push_dtp_data(producer, isproducer=True, file=fd, cmd=”RETR”)

def ftp_STOR(self, file, mode=’w’):
“””Store a file (transfer from the client to the server).”””
# A resume could occur in case of APPE or REST commands.
# In that case we have to open file object in different ways:
# STOR: mode = ‘w’
# APPE: mode = ‘a’
# REST: mode = ‘r+’ (to permit seeking on file object)
if ‘a’ in mode:
cmd = ‘APPE’
else:
cmd = ‘STOR’
line = self.fs.fs2ftp(file)
rest_pos = self._restart_position
self._restart_position = 0
if rest_pos:
mode = ‘r+’
try:
fd = self.run_as_current_user(self.fs.open, file, mode + ‘b’)
except IOError, err:
why = _strerror(err)
self.respond(‘550 %s.’ %why)
return

if rest_pos:
# Make sure that the requested offset is valid (within the
# size of the file being resumed).
# According to RFC-1123 a 554 reply may result in case
# that the existing file cannot be repositioned as
# specified in the REST.
ok = 0
try:
if rest_pos > self.fs.getsize(file):
raise ValueError
fd.seek(rest_pos)
ok = 1
except ValueError:
why = “Invalid REST parameter”
except IOError, err:
why = _strerror(err)
if not ok:
self.respond(‘554 %s’ %why)
return

if self.data_channel is not None:
resp = “Data connection already open. Transfer starting.”
self.respond(“125 ” + resp)
self.data_channel.file_obj = fd
self.data_channel.enable_receiving(self._current_type, cmd)
else:
resp = “File status okay. About to open data connection.”
self.respond(“150 ” + resp)
self._in_dtp_queue = (fd, cmd)

def ftp_STOU(self, line):
“””Store a file on the server with a unique name.”””
# Note 1: RFC-959 prohibited STOU parameters, but this
# prohibition is obsolete.
# Note 2: 250 response wanted by RFC-959 has been declared
# incorrect in RFC-1123 that wants 125/150 instead.
# Note 3: RFC-1123 also provided an exact output format
# defined to be as follow:
# > 125 FILE: pppp
# …where pppp represents the unique path name of the
# file that will be written.

# watch for STOU preceded by REST, which makes no sense.
if self._restart_position:
self.respond(“450 Can’t STOU while REST request is pending.”)
return

if line:
basedir, prefix = os.path.split(self.fs.ftp2fs(line))
prefix = prefix + ‘.’
else:
basedir = self.fs.ftp2fs(self.fs.cwd)
prefix = ‘ftpd.’
try:
fd = self.run_as_current_user(self.fs.mkstemp, prefix=prefix,
dir=basedir)
except IOError, err:
# hitted the max number of tries to find out file with
# unique name
if err.errno == errno.EEXIST:
why = ‘No usable unique file name found’
# something else happened
else:
why = _strerror(err)
self.respond(“450 %s.” % why)
return

if not self.authorizer.has_perm(self.username, ‘w’, fd.name):
try:
fd.close()
self.run_as_current_user(self.fs.remove, fd.name)
except os.error:
pass
self.respond(“550 Not enough privileges.”)
return

# now just acts like STOR except that restarting isn’t allowed
filename = os.path.basename(fd.name)
if self.data_channel is not None:
self.respond(“125 FILE: %s” % filename)
self.data_channel.file_obj = fd
self.data_channel.enable_receiving(self._current_type, “STOU”)
else:
self.respond(“150 FILE: %s” % filename)
self._in_dtp_queue = (fd, “STOU”)

def ftp_APPE(self, file):
“””Append data to an existing file on the server.”””
# watch for APPE preceded by REST, which makes no sense.
if self._restart_position:
self.respond(“450 Can’t APPE while REST request is pending.”)
else:
self.ftp_STOR(file, mode=’a’)

def ftp_REST(self, line):
“””Restart a file transfer from a previous mark.”””
if self._current_type == ‘a’:
self.respond(‘501 Resuming transfers not allowed in ASCII mode.’)
return
try:
marker = int(line)
if marker < 0:
raise ValueError
except (ValueError, OverflowError):
self.respond(“501 Invalid parameter.”)
else:
self.respond(“350 Restarting at position %s.” % marker)
self._restart_position = marker

def ftp_ABOR(self, line):
“””Abort the current data transfer.”””
# ABOR received while no data channel exists
if (self._dtp_acceptor is None) and (self._dtp_connector is None)
and (self.data_channel is None):
self.respond(“225 No transfer to abort.”)
return
else:
# a PASV or PORT was received but connection wasn’t made yet
if self._dtp_acceptor is not None or self._dtp_connector is not None:
self._shutdown_connecting_dtp()
resp = “225 ABOR command successful; data channel closed.”

# If a data transfer is in progress the server must first
# close the data connection, returning a 426 reply to
# indicate that the transfer terminated abnormally, then it
# must send a 226 reply, indicating that the abort command
# was successfully processed.
# If no data has been transmitted we just respond with 225
# indicating that no transfer was in progress.
if self.data_channel is not None:
if self.data_channel.transfer_in_progress():
self.data_channel.close()
self.data_channel = None
self.respond(“426 Connection closed; transfer aborted.”)
self.log(“Transfer aborted via ABOR.”)
resp = “226 ABOR command successful.”
else:
self.data_channel.close()
self.data_channel = None
resp = “225 ABOR command successful; data channel closed.”
self.respond(resp)

# — authentication

def ftp_USER(self, line):
“””Set the username for the current session.”””
# RFC-959 specifies a 530 response to the USER command if the
# username is not valid.  If the username is valid is required
# ftpd returns a 331 response instead.  In order to prevent a
# malicious client from determining valid usernames on a server,
# it is suggested by RFC-2577 that a server always return 331 to
# the USER command and then reject the combination of username
# and password for an invalid username when PASS is provided later.
if not self.authenticated:
self.respond(‘331 Username ok, send password.’)
else:
# a new USER command could be entered at any point in order
# to change the access control flushing any user, password,
# and account information already supplied and beginning the
# login sequence again.
self.flush_account()
msg = ‘Previous account information was flushed’
self.log(msg)
self.respond(‘331 %s, send password.’ % msg)
self.username = line

_auth_failed_timeout = 5

def ftp_PASS(self, line):
“””Check username’s password against the authorizer.”””
if self.authenticated:
self.respond(“503 User already authenticated.”)
return
if not self.username:
self.respond(“503 Login with USER first.”)
return

def auth_failed(msg=”Authentication failed.”):
self.sleeping = False
if hasattr(self, ‘_closed’) and not self._closed:
self.attempted_logins += 1
if self.attempted_logins >= self.max_login_attempts:
msg += ” Disconnecting.”
self.respond(“530 ” + msg)
self.close_when_done()
else:
self.respond(“530 ” + msg)
self.log_cmd(“PASS”, line, 530, msg)

if self.authorizer.validate_authentication(self.username, line):
msg_login = self.authorizer.get_msg_login(self.username)
if len(msg_login) <= 75:
self.respond(‘230 %s’ % msg_login)
else:
self.push(“230-%srn” % msg_login)
self.respond(“230 “)
self.authenticated = True
self.password = line
self.attempted_logins = 0

home = self.authorizer.get_home_dir(self.username)
self.fs = self.abstracted_fs(home, self)
self.on_login(self.username)
else:
self.username = “”
self.sleeping = True
if self.username == ‘anonymous’:
CallLater(self._auth_failed_timeout, auth_failed,
“Anonymous access not allowed.”,
_errback=self.handle_error)
else:
CallLater(self._auth_failed_timeout, auth_failed,
_errback=self.handle_error)

def ftp_REIN(self, line):
“””Reinitialize user’s current session.”””
# From RFC-959:
# REIN command terminates a USER, flushing all I/O and account
# information, except to allow any transfer in progress to be
# completed.  All parameters are reset to the default settings
# and the control connection is left open.  This is identical
# to the state in which a user finds himself immediately after
# the control connection is opened.
self.log(“Previous account information was flushed.”)
self.flush_account()
# Note: RFC-959 erroneously mention “220” as the correct response
# code to be given in this case, but this is wrong…
self.respond(“230 Ready for new user.”)

# — filesystem operations

def ftp_PWD(self, line):
“””Return the name of the current working directory to the client.”””
# The 257 response is supposed to include the directory
# name and in case it contains embedded double-quotes
# they must be doubled (see RFC-959, chapter 7, appendix 2).
self.respond(‘257 “%s” is the current directory.’
% self.fs.cwd.replace(‘”‘, ‘””‘))

def ftp_CWD(self, path):
“””Change the current working directory.”””
line = self.fs.fs2ftp(path)
try:
self.run_as_current_user(self.fs.chdir, path)
except OSError, err:
why = _strerror(err)
self.respond(‘550 %s.’ % why)
else:
self.respond(‘250 “%s” is the current directory.’ % self.fs.cwd)

def ftp_CDUP(self, path):
“””Change into the parent directory.”””
# Note: RFC-959 says that code 200 is required but it also says
# that CDUP uses the same codes as CWD.
self.ftp_CWD(path)

def ftp_SIZE(self, path):
“””Return size of file in a format suitable for using with
RESTart as defined in RFC-3659.”””

# Implementation note: properly handling the SIZE command when
# TYPE ASCII is used would require to scan the entire file to
# perform the ASCII translation logic
# (file.read().replace(os.linesep, ‘rn’)) and then calculating
# the len of such data which may be different than the actual
# size of the file on the server.  Considering that calculating
# such result could be very resource-intensive and also dangerous
# (DoS) we reject SIZE when the current TYPE is ASCII.
# However, clients in general should not be resuming downloads
# in ASCII mode.  Resuming downloads in binary mode is the
# recommended way as specified in RFC-3659.

line = self.fs.fs2ftp(path)
if self._current_type == ‘a’:
why = “SIZE not allowed in ASCII mode”
self.respond(“550 %s.” %why)
return
if not self.fs.isfile(self.fs.realpath(path)):
why = “%s is not retrievable” % line
self.respond(“550 %s.” % why)
return
try:
size = self.run_as_current_user(self.fs.getsize, path)
except OSError, err:
why = _strerror(err)
self.respond(‘550 %s.’ % why)
else:
self.respond(“213 %s” % size)

def ftp_MDTM(self, path):
“””Return last modification time of file to the client as an ISO
3307 style timestamp (YYYYMMDDHHMMSS) as defined in RFC-3659.
“””
line = self.fs.fs2ftp(path)
if not self.fs.isfile(self.fs.realpath(path)):
self.respond(“550 %s is not retrievable” % line)
return
if self.use_gmt_times:
timefunc = time.gmtime
else:
timefunc = time.localtime
try:
secs = self.run_as_current_user(self.fs.getmtime, path)
lmt = time.strftime(“%Y%m%d%H%M%S”, timefunc(secs))
except (OSError, ValueError), err:
if isinstance(err, OSError):
why = _strerror(err)
else:
# It could happen if file’s last modification time
# happens to be too old (prior to year 1900)
why = “Can’t determine file’s last modification time”
self.respond(‘550 %s.’ % why)
else:
self.respond(“213 %s” % lmt)

def ftp_MKD(self, path):
“””Create the specified directory.”””
line = self.fs.fs2ftp(path)
try:
self.run_as_current_user(self.fs.mkdir, path)
except OSError, err:
why = _strerror(err)
self.respond(‘550 %s.’ %why)
else:
# The 257 response is supposed to include the directory
# name and in case it contains embedded double-quotes
# they must be doubled (see RFC-959, chapter 7, appendix 2).
self.respond(‘257 “%s” directory created.’ % line.replace(‘”‘, ‘””‘))

def ftp_RMD(self, path):
“””Remove the specified directory.”””
line = self.fs.fs2ftp(path)
if self.fs.realpath(path) == self.fs.realpath(self.fs.root):
msg = “Can’t remove root directory.”
self.respond(“550 %s” % msg)
return
try:
self.run_as_current_user(self.fs.rmdir, path)
except OSError, err:
why = _strerror(err)
self.respond(‘550 %s.’ % why)
else:
self.respond(“250 Directory removed.”)

def ftp_DELE(self, path):
“””Delete the specified file.”””
line = self.fs.fs2ftp(path)
try:
self.run_as_current_user(self.fs.remove, path)
except OSError, err:
why = _strerror(err)
self.respond(‘550 %s.’ % why)
else:
self.respond(“250 File removed.”)

def ftp_RNFR(self, path):
“””Rename the specified (only the source name is specified
here, see RNTO command)”””
if not self.fs.lexists(path):
self.respond(“550 No such file or directory.”)
elif self.fs.realpath(path) == self.fs.realpath(self.fs.root):
self.respond(“550 Can’t rename the home directory.”)
else:
self._rnfr = path
self.respond(“350 Ready for destination name.”)

def ftp_RNTO(self, path):
“””Rename file (destination name only, source is specified with
RNFR).
“””
if not self._rnfr:
self.respond(“503 Bad sequence of commands: use RNFR first.”)
return
src = self._rnfr
self._rnfr = None
try:
self.run_as_current_user(self.fs.rename, src, path)
except OSError, err:
why = _strerror(err)
self.respond(‘550 %s.’ % why)
else:
self.respond(“250 Renaming ok.”)

# — others

def ftp_TYPE(self, line):
“””Set current type data type to binary/ascii”””
type = line.upper().replace(‘ ‘, ”)
if type in (“A”, “L7”):
self.respond(“200 Type set to: ASCII.”)
self._current_type = ‘a’
elif type in (“I”, “L8”):
self.respond(“200 Type set to: Binary.”)
self._current_type = ‘i’
else:
self.respond(‘504 Unsupported type “%s”.’ % line)

def ftp_STRU(self, line):
“””Set file structure (“F” is the only one supported (noop)).”””
stru = line.upper()
if stru == ‘F’:
self.respond(‘200 File transfer structure set to: F.’)
elif stru in (‘P’, ‘R’):
# R is required in minimum implementations by RFC-959, 5.1.
# RFC-1123, 4.1.2.13, amends this to only apply to servers
# whose file systems support record structures, but also
# suggests that such a server “may still accept files with
# STRU R, recording the byte stream literally”.
# Should we accept R but with no operational difference from
# F? proftpd and wu-ftpd don’t accept STRU R. We just do
# the same.
#
# RFC-1123 recommends against implementing P.
self.respond(‘504 Unimplemented STRU type.’)
else:
self.respond(‘501 Unrecognized STRU type.’)

def ftp_MODE(self, line):
“””Set data transfer mode (“S” is the only one supported (noop)).”””
mode = line.upper()
if mode == ‘S’:
self.respond(‘200 Transfer mode set to: S’)
elif mode in (‘B’, ‘C’):
self.respond(‘504 Unimplemented MODE type.’)
else:
self.respond(‘501 Unrecognized MODE type.’)

def ftp_STAT(self, path):
“””Return statistics about current ftp session. If an argument
is provided return directory listing over command channel.

Implementation note:

RFC-959 does not explicitly mention globbing but many FTP
servers do support it as a measure of convenience for FTP
clients and users.

In order to search for and match the given globbing expression,
the code has to search (possibly) many directories, examine
each contained filename, and build a list of matching files in
memory.  Since this operation can be quite intensive, both CPU-
and memory-wise, we do not support globbing.
“””
# return STATus information about ftpd
if not path:
s = []
s.append(‘Connected to: %s:%s’ % self.socket.getsockname()[:2])
if self.authenticated:
s.append(‘Logged in as: %s’ % self.username)
else:
if not self.username:
s.append(“Waiting for username.”)
else:
s.append(“Waiting for password.”)
if self._current_type == ‘a’:
type = ‘ASCII’
else:
type = ‘Binary’
s.append(“TYPE: %s; STRUcture: File; MODE: Stream” % type)
if self._dtp_acceptor is not None:
s.append(‘Passive data channel waiting for connection.’)
elif self.data_channel is not None:
bytes_sent = self.data_channel.tot_bytes_sent
bytes_recv = self.data_channel.tot_bytes_received
elapsed_time = self.data_channel.get_elapsed_time()
s.append(‘Data connection open:’)
s.append(‘Total bytes sent: %s’ % bytes_sent)
s.append(‘Total bytes received: %s’ % bytes_recv)
s.append(‘Transfer elapsed time: %s secs’ % elapsed_time)
else:
s.append(‘Data connection closed.’)

self.push(‘211-FTP server status:rn’)
self.push(”.join([‘ %srn’ % item for item in s]))
self.respond(‘211 End of status.’)
# return directory LISTing over the command channel
else:
line = self.fs.fs2ftp(path)
try:
iterator = self.run_as_current_user(self.fs.get_list_dir, path)
except OSError, err:
why = _strerror(err)
self.respond(‘550 %s.’ %why)
else:
self.push(‘213-Status of “%s”:rn’ % line)
self.push_with_producer(BufferedIteratorProducer(iterator))
self.respond(‘213 End of status.’)

def ftp_FEAT(self, line):
“””List all new features supported as defined in RFC-2398.”””
features = [‘EPRT’,’EPSV’,’MDTM’,’REST STREAM’,’SIZE’,’TVFS’]
features.extend(self._extra_feats)
s = ”
for fact in self._available_facts:
if fact in self._current_facts:
s += fact + ‘*;’
else:
s += fact + ‘;’
features.append(‘MLST ‘ + s)
features.sort()
self.push(“211-Features supported:rn”)
self.push(“”.join([” %srn” % x for x in features]))

self.respond(‘211 End FEAT.’)

def ftp_OPTS(self, line):
“””Specify options for FTP commands as specified in RFC-2389.”””
try:
if line.count(‘ ‘) > 1:
raise ValueError(‘Invalid number of arguments’)
if ‘ ‘ in line:
cmd, arg = line.split(‘ ‘)
if ‘;’ not in arg:
raise ValueError(‘Invalid argument’)
else:
cmd, arg = line, ”
# actually the only command able to accept options is MLST
if cmd.upper() != ‘MLST’:
raise ValueError(‘Unsupported command “%s”‘ % cmd)
except ValueError, err:
self.respond(‘501 %s.’ % err)
else:
facts = [x.lower() for x in arg.split(‘;’)]
self._current_facts = [x for x in facts if x in self._available_facts]
f = ”.join([x + ‘;’ for x in self._current_facts])
self.respond(‘200 MLST OPTS ‘ + f)

def ftp_NOOP(self, line):
“””Do nothing.”””
self.respond(“200 I successfully done nothin’.”)

def ftp_SYST(self, line):
“””Return system type (always returns UNIX type: L8).”””
# This command is used to find out the type of operating system
# at the server.  The reply shall have as its first word one of
# the system names listed in RFC-943.
# Since that we always return a “/bin/ls -lA”-like output on
# LIST we  prefer to respond as if we would on Unix in any case.
self.respond(“215 UNIX Type: L8”)

def ftp_ALLO(self, line):
“””Allocate bytes for storage (noop).”””
# not necessary (always respond with 202)
self.respond(“202 No storage allocation necessary.”)

def ftp_HELP(self, line):
“””Return help text to the client.”””
if line:
line = line.upper()
if line in self.proto_cmds:
self.respond(“214 %s” % self.proto_cmds[line][‘help’])
else:
self.respond(“501 Unrecognized command.”)
else:
# provide a compact list of recognized commands
def formatted_help():
cmds = []
keys = [x for x in self.proto_cmds.keys() if not x.startswith(‘SITE ‘)]
keys.sort()
while keys:
elems = tuple((keys[0:8]))
cmds.append(‘ %-6s’ * len(elems) % elems + ‘rn’)
del keys[0:8]
return ”.join(cmds)

self.push(“214-The following commands are recognized:rn”)
self.push(formatted_help())
self.respond(“214 Help command successful.”)

# — site commands

# No SITE commands aside from SITE HELP are implemented by default.
# The user willing to add support for a specific SITE command must
# update self.proto_cmds dictionary and define a new ftp_SITE_%CMD%
# method in the subclass.

def ftp_SITE_HELP(self, line):
“””Return help text to the client for a given SITE command.”””
if line:
line = line.upper()
if line in self.proto_cmds:
self.respond(“214 %s” % self.proto_cmds[line][‘help’])
else:
self.respond(“501 Unrecognized SITE command.”)
else:
self.push(“214-The following SITE commands are recognized:rn”)
site_cmds = []
keys = self.proto_cmds.keys()
keys.sort()
for cmd in keys:
if cmd.startswith(‘SITE ‘):
site_cmds.append(‘ %srn’ % cmd[5:])
self.push(”.join(site_cmds))
self.respond(“214 Help SITE command successful.”)

# — support for deprecated cmds

# RFC-1123 requires that the server treat XCUP, XCWD, XMKD, XPWD
# and XRMD commands as synonyms for CDUP, CWD, MKD, LIST and RMD.
# Such commands are obsoleted but some ftp clients (e.g. Windows
# ftp.exe) still use them.

def ftp_XCUP(self, line):
“””Change to the parent directory. Synonym for CDUP. Deprecated.”””
self.ftp_CDUP(line)

def ftp_XCWD(self, line):
“””Change the current working directory. Synonym for CWD. Deprecated.”””
self.ftp_CWD(line)

def ftp_XMKD(self, line):
“””Create the specified directory. Synonym for MKD. Deprecated.”””
self.ftp_MKD(line)

def ftp_XPWD(self, line):
“””Return the current working directory. Synonym for PWD. Deprecated.”””
self.ftp_PWD(line)

def ftp_XRMD(self, line):
“””Remove the specified directory. Synonym for RMD. Deprecated.”””
self.ftp_RMD(line)

class FTPServer(object, asyncore.dispatcher):
“””This class is an asyncore.disptacher subclass.  It creates a FTP
socket listening on <address>, dispatching the requests to a <handler>
(typically FTPHandler class).

Depending on the type of address specified IPv4 or IPv6 connections
(or both, depending from the underlying system) will be accepted.

All relevant session information is stored in class attributes
described below.

– (int) max_cons:
number of maximum simultaneous connections accepted (defaults
to 512). Can be set to 0 for unlimited but it is recommended
to always have a limit to avoid running out of file descriptors
(DoS).

– (int) max_cons_per_ip:
number of maximum connections accepted for the same IP address
(defaults to 0 == unlimited).
“””

max_cons = 512
max_cons_per_ip = 0

def __init__(self, address, handler):
“””Initiate the FTP server opening listening on address.

– (tuple) address: the host:port pair on which the command
channel will listen.

– (classobj) handler: the handler class to use.
“””
asyncore.dispatcher.__init__(self)
self.handler = handler
self.ip_map = []
host, port = address
# in case of FTPS class not properly configured we want errors
# to be raised here rather than later, when client connects
if hasattr(handler, ‘get_ssl_context’):
handler.get_ssl_context()

# AF_INET or AF_INET6 socket
# Get the correct address family for our host (allows IPv6 addresses)
try:
info = socket.getaddrinfo(host, port, socket.AF_UNSPEC,
socket.SOCK_STREAM, 0, socket.AI_PASSIVE)
except socket.gaierror:
# Probably a DNS issue. Assume IPv4.
self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
self.set_reuse_addr()
self.bind((host, port))
else:
for res in info:
af, socktype, proto, canonname, sa = res
try:
self.create_socket(af, socktype)
self.set_reuse_addr()
self.bind(sa)
except socket.error, msg:
if self.socket:
self.socket.close()
self.socket = None
continue
break
if not self.socket:
raise socket.error(msg)
self.listen(5)

def set_reuse_addr(self):
# Overridden for convenience. Avoid to reuse address on Windows.
if (os.name in (‘nt’, ‘ce’)) or (sys.platform == ‘cygwin’):
return
asyncore.dispatcher.set_reuse_addr(self)

def serve_forever(self, timeout=1.0, use_poll=False, count=None):
“””A wrap around asyncore.loop(); starts the asyncore polling
loop including running the scheduler.
The arguments are the same expected by original asyncore.loop()
function:

– (float) timeout: the timeout passed to select() or poll()
system calls expressed in seconds (default 1.0).

– (bool) use_poll: when True use poll() instead of select()
(default False).

– (int) count: how many times the polling loop gets called
before returning.  If None loops forever (default None).
“””
if use_poll and hasattr(asyncore.select, ‘poll’):
poll_fun = asyncore.poll2
else:
poll_fun = asyncore.poll

if count is None:
log(“Serving FTP on %s:%s” % self.socket.getsockname()[:2])
try:
while asyncore.socket_map or _tasks:
poll_fun(timeout)
_scheduler()
except (KeyboardInterrupt, SystemExit, asyncore.ExitNow):
log(“Shutting down FTP server.”)
self.close_all()
else:
while (asyncore.socket_map or _tasks) and count > 0:
if asyncore.socket_map:
poll_fun(timeout)
if _tasks:
_scheduler()
count = count – 1

def handle_accept(self):
“””Called when remote client initiates a connection.”””
try:
sock, addr = self.accept()
except TypeError:
# sometimes accept() might return None (see issue 91)
return
except socket.error, err:
# ECONNABORTED might be thrown on *BSD (see issue 105)
if err[0] != errno.ECONNABORTED:
logerror(traceback.format_exc())
return
else:
# sometimes addr == None instead of (ip, port) (see issue 104)
if addr == None:
return

handler = None
ip = None
try:
handler = self.handler(sock, self)
if not handler.connected:
return
log(“[]%s:%s Connected.” % addr[:2])
ip = addr[0]
self.ip_map.append(ip)

# For performance and security reasons we should always set a
# limit for the number of file descriptors that socket_map
# should contain.  When we’re running out of such limit we’ll
# use the last available channel for sending a 421 response
# to the client before disconnecting it.
if self.max_cons and (len(asyncore.socket_map) > self.max_cons):
handler.handle_max_cons()
return

# accept only a limited number of connections from the same
# source address.
if self.max_cons_per_ip:
if (self.ip_map.count(ip) > self.max_cons_per_ip):
handler.handle_max_cons_per_ip()
return

handler.handle()
except (KeyboardInterrupt, SystemExit, asyncore.ExitNow):
raise
except:
# This is supposed to be an application bug that should
# be fixed. We do not want to tear down the server though
# (DoS). We just log the exception, hoping that someone
# will eventually file a bug. References:
# – http://code.google.com/p/pyftpdlib/issues/detail?id=143
# – http://code.google.com/p/pyftpdlib/issues/detail?id=166
# – https://groups.google.com/forum/#!topic/pyftpdlib/h7pPybzAx14
if handler is not None:
handler.close()
else:
if ip is not None and ip in self.ip_map:
self.ip_map.remove(ip)
logerror(traceback.format_exc())

def writable(self):
return 0

def handle_error(self):
“””Called to handle any uncaught exceptions.”””
try:
raise
except (KeyboardInterrupt, SystemExit, asyncore.ExitNow):
raise
except:
logerror(traceback.format_exc())
self.close()

def close_all(self, ignore_all=False):
“””Stop serving and also disconnects all currently connected
clients.

– (bool) ignore_all:
having it set to False results in raising exception in case
of unexpected errors.

Implementation note:

This is how asyncore.close_all() is implemented starting from
Python 2.6.
The previous versions of close_all() instead of iterating over
all opened channels and calling close() method for each one
of them only closed sockets generating memory leaks.
“””
values = asyncore.socket_map.values()
# We sort the list so that we close all FTP handler instances
# first since FTPHandler.close() has the peculiarity of
# automatically closing all its children (DTPHandler, ActiveDTP
# and PassiveDTP).
# This should minimize the possibility to incur in race
# conditions or memory leaks caused by orphaned references
# left behind in case of error.
values.sort(key=lambda inst: isinstance(inst, FTPHandler), reverse=True)
for x in values:
try:
x.close()
except OSError, x:
if x[0] == errno.EBADF:
pass
elif not ignore_all:
raise
except (asyncore.ExitNow, KeyboardInterrupt, SystemExit):
raise
except:
if not ignore_all:
raise
asyncore.socket_map.clear()

for x in _tasks:
try:
x.cancel()
except (asyncore.ExitNow, KeyboardInterrupt, SystemExit):
raise
except:
if not ignore_all:
raise
del _tasks[:]

def main():
“””Start a stand alone anonymous FTP server.”””

class CustomizedOptionFormatter(optparse.IndentedHelpFormatter):
“””Formats options shown in help in a prettier way.”””

def format_option(self, option):
result = []
opts = self.option_strings[option]
result.append(‘  %sn’ % opts)
if option.help:
help_text = ‘     %snn’ % self.expand_default(option)
result.append(help_text)
return ”.join(result)

usage = “python -m pyftpdlib.ftpserver [options]”
parser = optparse.OptionParser(usage=usage, description=main.__doc__,
formatter=CustomizedOptionFormatter())
parser.add_option(‘-i’, ‘–interface’, default=’0.0.0.0′, metavar=”ADDRESS”,
help=”specify the interface to run on (default all ”
“interfaces)”)
parser.add_option(‘-p’, ‘–port’, type=”int”, default=21, metavar=”PORT”,
help=”specity port number to run on (default 21)”)
parser.add_option(‘-w’, ‘–write’, action=”store_true”, default=False,
help=”grants write access for the anonymous user ”
“(default read-only)”)
parser.add_option(‘-d’, ‘–directory’, default=os.getcwd(), metavar=”FOLDER”,
help=”specify the directory to share (default current ”
“directory)”)
parser.add_option(‘-n’, ‘–nat-address’, default=None, metavar=”ADDRESS”,
help=”the NAT address to use for passive connections”)
parser.add_option(‘-r’, ‘–range’,  default=None, metavar=”FROM-TO”,
help=”the range of TCP ports to use for passive ”
“connections (e.g. -r 8000-9000)”)
parser.add_option(‘-v’, ‘–version’, action=’store_true’,
help=”print pyftpdlib version and exit”)

options, args = parser.parse_args()
if options.version:
sys.exit(“pyftpdlib %s” % __ver__)
passive_ports = None
if options.range:
try:
start, stop = options.range.split(‘-‘)
start = int(start)
stop = int(stop)
except ValueError:
parser.error(‘invalid argument passed to -r option’)
else:
passive_ports = range(start, stop + 1)
# On recent Windows versions, if address is not specified and IPv6
# is installed the socket will listen on IPv6 by default; in this
# case we force IPv4 instead.
if os.name in (‘nt’, ‘ce’) and not options.interface:
options.interface = ‘0.0.0.0’

authorizer = DummyAuthorizer()
perm = options.write and “elradfmw” or “elr”
authorizer.add_anonymous(options.directory, perm=perm)
handler = FTPHandler
handler.authorizer = authorizer
handler.masquerade_address = options.nat_address
handler.passive_ports = passive_ports
ftpd = FTPServer((options.interface, options.port), FTPHandler)
ftpd.serve_forever()

if __name__ == ‘__main__’:
main()

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