mirror of
https://github.com/python/cpython.git
synced 2024-11-27 20:04:41 +08:00
0e6c8ee235
* Prevent low-grade poplib REDOS (CVE-2018-1060) The regex to test a mail server's timestamp is susceptible to catastrophic backtracking on long evil responses from the server. Happily, the maximum length of malicious inputs is 2K thanks to a limit introduced in the fix for CVE-2013-1752. A 2KB evil response from the mail server would result in small slowdowns (milliseconds vs. microseconds) accumulated over many apop calls. This is a potential DOS vector via accumulated slowdowns. Replace it with a similar non-vulnerable regex. The new regex is RFC compliant. The old regex was non-compliant in edge cases. * Prevent difflib REDOS (CVE-2018-1061) The default regex for IS_LINE_JUNK is susceptible to catastrophic backtracking. This is a potential DOS vector. Replace it with an equivalent non-vulnerable regex. Also introduce unit and REDOS tests for difflib. Co-authored-by: Tim Peters <tim.peters@gmail.com> Co-authored-by: Christian Heimes <christian@python.org>
479 lines
15 KiB
Python
479 lines
15 KiB
Python
"""A POP3 client class.
|
|
|
|
Based on the J. Myers POP3 draft, Jan. 96
|
|
"""
|
|
|
|
# Author: David Ascher <david_ascher@brown.edu>
|
|
# [heavily stealing from nntplib.py]
|
|
# Updated: Piers Lauder <piers@cs.su.oz.au> [Jul '97]
|
|
# String method conversion and test jig improvements by ESR, February 2001.
|
|
# Added the POP3_SSL class. Methods loosely based on IMAP_SSL. Hector Urtubia <urtubia@mrbook.org> Aug 2003
|
|
|
|
# Example (see the test function at the end of this file)
|
|
|
|
# Imports
|
|
|
|
import errno
|
|
import re
|
|
import socket
|
|
|
|
try:
|
|
import ssl
|
|
HAVE_SSL = True
|
|
except ImportError:
|
|
HAVE_SSL = False
|
|
|
|
__all__ = ["POP3","error_proto"]
|
|
|
|
# Exception raised when an error or invalid response is received:
|
|
|
|
class error_proto(Exception): pass
|
|
|
|
# Standard Port
|
|
POP3_PORT = 110
|
|
|
|
# POP SSL PORT
|
|
POP3_SSL_PORT = 995
|
|
|
|
# Line terminators (we always output CRLF, but accept any of CRLF, LFCR, LF)
|
|
CR = b'\r'
|
|
LF = b'\n'
|
|
CRLF = CR+LF
|
|
|
|
# maximal line length when calling readline(). This is to prevent
|
|
# reading arbitrary length lines. RFC 1939 limits POP3 line length to
|
|
# 512 characters, including CRLF. We have selected 2048 just to be on
|
|
# the safe side.
|
|
_MAXLINE = 2048
|
|
|
|
|
|
class POP3:
|
|
|
|
"""This class supports both the minimal and optional command sets.
|
|
Arguments can be strings or integers (where appropriate)
|
|
(e.g.: retr(1) and retr('1') both work equally well.
|
|
|
|
Minimal Command Set:
|
|
USER name user(name)
|
|
PASS string pass_(string)
|
|
STAT stat()
|
|
LIST [msg] list(msg = None)
|
|
RETR msg retr(msg)
|
|
DELE msg dele(msg)
|
|
NOOP noop()
|
|
RSET rset()
|
|
QUIT quit()
|
|
|
|
Optional Commands (some servers support these):
|
|
RPOP name rpop(name)
|
|
APOP name digest apop(name, digest)
|
|
TOP msg n top(msg, n)
|
|
UIDL [msg] uidl(msg = None)
|
|
CAPA capa()
|
|
STLS stls()
|
|
UTF8 utf8()
|
|
|
|
Raises one exception: 'error_proto'.
|
|
|
|
Instantiate with:
|
|
POP3(hostname, port=110)
|
|
|
|
NB: the POP protocol locks the mailbox from user
|
|
authorization until QUIT, so be sure to get in, suck
|
|
the messages, and quit, each time you access the
|
|
mailbox.
|
|
|
|
POP is a line-based protocol, which means large mail
|
|
messages consume lots of python cycles reading them
|
|
line-by-line.
|
|
|
|
If it's available on your mail server, use IMAP4
|
|
instead, it doesn't suffer from the two problems
|
|
above.
|
|
"""
|
|
|
|
encoding = 'UTF-8'
|
|
|
|
def __init__(self, host, port=POP3_PORT,
|
|
timeout=socket._GLOBAL_DEFAULT_TIMEOUT):
|
|
self.host = host
|
|
self.port = port
|
|
self._tls_established = False
|
|
self.sock = self._create_socket(timeout)
|
|
self.file = self.sock.makefile('rb')
|
|
self._debugging = 0
|
|
self.welcome = self._getresp()
|
|
|
|
def _create_socket(self, timeout):
|
|
return socket.create_connection((self.host, self.port), timeout)
|
|
|
|
def _putline(self, line):
|
|
if self._debugging > 1: print('*put*', repr(line))
|
|
self.sock.sendall(line + CRLF)
|
|
|
|
|
|
# Internal: send one command to the server (through _putline())
|
|
|
|
def _putcmd(self, line):
|
|
if self._debugging: print('*cmd*', repr(line))
|
|
line = bytes(line, self.encoding)
|
|
self._putline(line)
|
|
|
|
|
|
# Internal: return one line from the server, stripping CRLF.
|
|
# This is where all the CPU time of this module is consumed.
|
|
# Raise error_proto('-ERR EOF') if the connection is closed.
|
|
|
|
def _getline(self):
|
|
line = self.file.readline(_MAXLINE + 1)
|
|
if len(line) > _MAXLINE:
|
|
raise error_proto('line too long')
|
|
|
|
if self._debugging > 1: print('*get*', repr(line))
|
|
if not line: raise error_proto('-ERR EOF')
|
|
octets = len(line)
|
|
# server can send any combination of CR & LF
|
|
# however, 'readline()' returns lines ending in LF
|
|
# so only possibilities are ...LF, ...CRLF, CR...LF
|
|
if line[-2:] == CRLF:
|
|
return line[:-2], octets
|
|
if line[:1] == CR:
|
|
return line[1:-1], octets
|
|
return line[:-1], octets
|
|
|
|
|
|
# Internal: get a response from the server.
|
|
# Raise 'error_proto' if the response doesn't start with '+'.
|
|
|
|
def _getresp(self):
|
|
resp, o = self._getline()
|
|
if self._debugging > 1: print('*resp*', repr(resp))
|
|
if not resp.startswith(b'+'):
|
|
raise error_proto(resp)
|
|
return resp
|
|
|
|
|
|
# Internal: get a response plus following text from the server.
|
|
|
|
def _getlongresp(self):
|
|
resp = self._getresp()
|
|
list = []; octets = 0
|
|
line, o = self._getline()
|
|
while line != b'.':
|
|
if line.startswith(b'..'):
|
|
o = o-1
|
|
line = line[1:]
|
|
octets = octets + o
|
|
list.append(line)
|
|
line, o = self._getline()
|
|
return resp, list, octets
|
|
|
|
|
|
# Internal: send a command and get the response
|
|
|
|
def _shortcmd(self, line):
|
|
self._putcmd(line)
|
|
return self._getresp()
|
|
|
|
|
|
# Internal: send a command and get the response plus following text
|
|
|
|
def _longcmd(self, line):
|
|
self._putcmd(line)
|
|
return self._getlongresp()
|
|
|
|
|
|
# These can be useful:
|
|
|
|
def getwelcome(self):
|
|
return self.welcome
|
|
|
|
|
|
def set_debuglevel(self, level):
|
|
self._debugging = level
|
|
|
|
|
|
# Here are all the POP commands:
|
|
|
|
def user(self, user):
|
|
"""Send user name, return response
|
|
|
|
(should indicate password required).
|
|
"""
|
|
return self._shortcmd('USER %s' % user)
|
|
|
|
|
|
def pass_(self, pswd):
|
|
"""Send password, return response
|
|
|
|
(response includes message count, mailbox size).
|
|
|
|
NB: mailbox is locked by server from here to 'quit()'
|
|
"""
|
|
return self._shortcmd('PASS %s' % pswd)
|
|
|
|
|
|
def stat(self):
|
|
"""Get mailbox status.
|
|
|
|
Result is tuple of 2 ints (message count, mailbox size)
|
|
"""
|
|
retval = self._shortcmd('STAT')
|
|
rets = retval.split()
|
|
if self._debugging: print('*stat*', repr(rets))
|
|
numMessages = int(rets[1])
|
|
sizeMessages = int(rets[2])
|
|
return (numMessages, sizeMessages)
|
|
|
|
|
|
def list(self, which=None):
|
|
"""Request listing, return result.
|
|
|
|
Result without a message number argument is in form
|
|
['response', ['mesg_num octets', ...], octets].
|
|
|
|
Result when a message number argument is given is a
|
|
single response: the "scan listing" for that message.
|
|
"""
|
|
if which is not None:
|
|
return self._shortcmd('LIST %s' % which)
|
|
return self._longcmd('LIST')
|
|
|
|
|
|
def retr(self, which):
|
|
"""Retrieve whole message number 'which'.
|
|
|
|
Result is in form ['response', ['line', ...], octets].
|
|
"""
|
|
return self._longcmd('RETR %s' % which)
|
|
|
|
|
|
def dele(self, which):
|
|
"""Delete message number 'which'.
|
|
|
|
Result is 'response'.
|
|
"""
|
|
return self._shortcmd('DELE %s' % which)
|
|
|
|
|
|
def noop(self):
|
|
"""Does nothing.
|
|
|
|
One supposes the response indicates the server is alive.
|
|
"""
|
|
return self._shortcmd('NOOP')
|
|
|
|
|
|
def rset(self):
|
|
"""Unmark all messages marked for deletion."""
|
|
return self._shortcmd('RSET')
|
|
|
|
|
|
def quit(self):
|
|
"""Signoff: commit changes on server, unlock mailbox, close connection."""
|
|
resp = self._shortcmd('QUIT')
|
|
self.close()
|
|
return resp
|
|
|
|
def close(self):
|
|
"""Close the connection without assuming anything about it."""
|
|
try:
|
|
file = self.file
|
|
self.file = None
|
|
if file is not None:
|
|
file.close()
|
|
finally:
|
|
sock = self.sock
|
|
self.sock = None
|
|
if sock is not None:
|
|
try:
|
|
sock.shutdown(socket.SHUT_RDWR)
|
|
except OSError as exc:
|
|
# The server might already have closed the connection.
|
|
# On Windows, this may result in WSAEINVAL (error 10022):
|
|
# An invalid operation was attempted.
|
|
if (exc.errno != errno.ENOTCONN
|
|
and getattr(exc, 'winerror', 0) != 10022):
|
|
raise
|
|
finally:
|
|
sock.close()
|
|
|
|
#__del__ = quit
|
|
|
|
|
|
# optional commands:
|
|
|
|
def rpop(self, user):
|
|
"""Not sure what this does."""
|
|
return self._shortcmd('RPOP %s' % user)
|
|
|
|
|
|
timestamp = re.compile(br'\+OK.[^<]*(<.*>)')
|
|
|
|
def apop(self, user, password):
|
|
"""Authorisation
|
|
|
|
- only possible if server has supplied a timestamp in initial greeting.
|
|
|
|
Args:
|
|
user - mailbox user;
|
|
password - mailbox password.
|
|
|
|
NB: mailbox is locked by server from here to 'quit()'
|
|
"""
|
|
secret = bytes(password, self.encoding)
|
|
m = self.timestamp.match(self.welcome)
|
|
if not m:
|
|
raise error_proto('-ERR APOP not supported by server')
|
|
import hashlib
|
|
digest = m.group(1)+secret
|
|
digest = hashlib.md5(digest).hexdigest()
|
|
return self._shortcmd('APOP %s %s' % (user, digest))
|
|
|
|
|
|
def top(self, which, howmuch):
|
|
"""Retrieve message header of message number 'which'
|
|
and first 'howmuch' lines of message body.
|
|
|
|
Result is in form ['response', ['line', ...], octets].
|
|
"""
|
|
return self._longcmd('TOP %s %s' % (which, howmuch))
|
|
|
|
|
|
def uidl(self, which=None):
|
|
"""Return message digest (unique id) list.
|
|
|
|
If 'which', result contains unique id for that message
|
|
in the form 'response mesgnum uid', otherwise result is
|
|
the list ['response', ['mesgnum uid', ...], octets]
|
|
"""
|
|
if which is not None:
|
|
return self._shortcmd('UIDL %s' % which)
|
|
return self._longcmd('UIDL')
|
|
|
|
|
|
def utf8(self):
|
|
"""Try to enter UTF-8 mode (see RFC 6856). Returns server response.
|
|
"""
|
|
return self._shortcmd('UTF8')
|
|
|
|
|
|
def capa(self):
|
|
"""Return server capabilities (RFC 2449) as a dictionary
|
|
>>> c=poplib.POP3('localhost')
|
|
>>> c.capa()
|
|
{'IMPLEMENTATION': ['Cyrus', 'POP3', 'server', 'v2.2.12'],
|
|
'TOP': [], 'LOGIN-DELAY': ['0'], 'AUTH-RESP-CODE': [],
|
|
'EXPIRE': ['NEVER'], 'USER': [], 'STLS': [], 'PIPELINING': [],
|
|
'UIDL': [], 'RESP-CODES': []}
|
|
>>>
|
|
|
|
Really, according to RFC 2449, the cyrus folks should avoid
|
|
having the implementation split into multiple arguments...
|
|
"""
|
|
def _parsecap(line):
|
|
lst = line.decode('ascii').split()
|
|
return lst[0], lst[1:]
|
|
|
|
caps = {}
|
|
try:
|
|
resp = self._longcmd('CAPA')
|
|
rawcaps = resp[1]
|
|
for capline in rawcaps:
|
|
capnm, capargs = _parsecap(capline)
|
|
caps[capnm] = capargs
|
|
except error_proto as _err:
|
|
raise error_proto('-ERR CAPA not supported by server')
|
|
return caps
|
|
|
|
|
|
def stls(self, context=None):
|
|
"""Start a TLS session on the active connection as specified in RFC 2595.
|
|
|
|
context - a ssl.SSLContext
|
|
"""
|
|
if not HAVE_SSL:
|
|
raise error_proto('-ERR TLS support missing')
|
|
if self._tls_established:
|
|
raise error_proto('-ERR TLS session already established')
|
|
caps = self.capa()
|
|
if not 'STLS' in caps:
|
|
raise error_proto('-ERR STLS not supported by server')
|
|
if context is None:
|
|
context = ssl._create_stdlib_context()
|
|
resp = self._shortcmd('STLS')
|
|
self.sock = context.wrap_socket(self.sock,
|
|
server_hostname=self.host)
|
|
self.file = self.sock.makefile('rb')
|
|
self._tls_established = True
|
|
return resp
|
|
|
|
|
|
if HAVE_SSL:
|
|
|
|
class POP3_SSL(POP3):
|
|
"""POP3 client class over SSL connection
|
|
|
|
Instantiate with: POP3_SSL(hostname, port=995, keyfile=None, certfile=None,
|
|
context=None)
|
|
|
|
hostname - the hostname of the pop3 over ssl server
|
|
port - port number
|
|
keyfile - PEM formatted file that contains your private key
|
|
certfile - PEM formatted certificate chain file
|
|
context - a ssl.SSLContext
|
|
|
|
See the methods of the parent class POP3 for more documentation.
|
|
"""
|
|
|
|
def __init__(self, host, port=POP3_SSL_PORT, keyfile=None, certfile=None,
|
|
timeout=socket._GLOBAL_DEFAULT_TIMEOUT, context=None):
|
|
if context is not None and keyfile is not None:
|
|
raise ValueError("context and keyfile arguments are mutually "
|
|
"exclusive")
|
|
if context is not None and certfile is not None:
|
|
raise ValueError("context and certfile arguments are mutually "
|
|
"exclusive")
|
|
if keyfile is not None or certfile is not None:
|
|
import warnings
|
|
warnings.warn("keyfile and certfile are deprecated, use a"
|
|
"custom context instead", DeprecationWarning, 2)
|
|
self.keyfile = keyfile
|
|
self.certfile = certfile
|
|
if context is None:
|
|
context = ssl._create_stdlib_context(certfile=certfile,
|
|
keyfile=keyfile)
|
|
self.context = context
|
|
POP3.__init__(self, host, port, timeout)
|
|
|
|
def _create_socket(self, timeout):
|
|
sock = POP3._create_socket(self, timeout)
|
|
sock = self.context.wrap_socket(sock,
|
|
server_hostname=self.host)
|
|
return sock
|
|
|
|
def stls(self, keyfile=None, certfile=None, context=None):
|
|
"""The method unconditionally raises an exception since the
|
|
STLS command doesn't make any sense on an already established
|
|
SSL/TLS session.
|
|
"""
|
|
raise error_proto('-ERR TLS session already established')
|
|
|
|
__all__.append("POP3_SSL")
|
|
|
|
if __name__ == "__main__":
|
|
import sys
|
|
a = POP3(sys.argv[1])
|
|
print(a.getwelcome())
|
|
a.user(sys.argv[2])
|
|
a.pass_(sys.argv[3])
|
|
a.list()
|
|
(numMsgs, totalSize) = a.stat()
|
|
for i in range(1, numMsgs + 1):
|
|
(header, msg, octets) = a.retr(i)
|
|
print("Message %d:" % i)
|
|
for line in msg:
|
|
print(' ' + line)
|
|
print('-----------------------')
|
|
a.quit()
|