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- Issue #15014: SMTP.auth() and SMTP.login() now support RFC 4954's optional 

initial-response argument to the SMTP AUTH command.
This commit is contained in:
Barry Warsaw 2015-07-09 10:39:55 -04:00
parent b85b427507
commit c5ea754e48
4 changed files with 153 additions and 39 deletions
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45
Doc/library/smtplib.rst
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@ -288,7 +288,7 @@ An :class:`SMTP` instance has the following methods:
Many sites disable SMTP ``VRFY`` in order to foil spammers.
.. method:: SMTP.login(user, password)
.. method:: SMTP.login(user, password, *, initial_response_ok=True)
Log in on an SMTP server that requires authentication. The arguments are the
username and the password to authenticate with. If there has been no previous
@ -309,14 +309,21 @@ An :class:`SMTP` instance has the following methods:
No suitable authentication method was found.
Each of the authentication methods supported by :mod:`smtplib` are tried in
turn if they are advertised as supported by the server (see :meth:`auth`
for a list of supported authentication methods).
turn if they are advertised as supported by the server. See :meth:`auth`
for a list of supported authentication methods. *initial_response_ok* is
passed through to :meth:`auth`.
Optional keyword argument *initial_response_ok* specifies whether, for
authentication methods that support it, an "initial response" as specified
in :rfc:`4954` can be sent along with the ``AUTH`` command, rather than
requiring a challenge/response.
.. versionchanged:: 3.5
:exc:`SMTPNotSupportedError` may be raised.
:exc:`SMTPNotSupportedError` may be raised, and the
*initial_response_ok* parameter was added.
.. method:: SMTP.auth(mechanism, authobject)
.. method:: SMTP.auth(mechanism, authobject, *, initial_response_ok=True)
Issue an ``SMTP`` ``AUTH`` command for the specified authentication
*mechanism*, and handle the challenge response via *authobject*.
@ -325,13 +332,23 @@ An :class:`SMTP` instance has the following methods:
be used as argument to the ``AUTH`` command; the valid values are
those listed in the ``auth`` element of :attr:`esmtp_features`.
*authobject* must be a callable object taking a single argument:
*authobject* must be a callable object taking an optional single argument:
data = authobject(challenge)
data = authobject(challenge=None)
It will be called to process the server's challenge response; the
*challenge* argument it is passed will be a ``bytes``. It should return
``bytes`` *data* that will be base64 encoded and sent to the server.
If optional keyword argument *initial_response_ok* is true,
``authobject()`` will be called first with no argument. It can return the
:rfc:`4954` "initial response" bytes which will be encoded and sent with
the ``AUTH`` command as below. If the ``authobject()`` does not support an
initial response (e.g. because it requires a challenge), it should return
None when called with ``challenge=None``. If *initial_response_ok* is
false, then ``authobject()`` will not be called first with None.
If the initial response check returns None, or if *initial_response_ok* is
false, ``authobject()`` will be called to process the server's challenge
response; the *challenge* argument it is passed will be a ``bytes``. It
should return ``bytes`` *data* that will be base64 encoded and sent to the
server.
The ``SMTP`` class provides ``authobjects`` for the ``CRAM-MD5``, ``PLAIN``,
and ``LOGIN`` mechanisms; they are named ``SMTP.auth_cram_md5``,
@ -340,10 +357,10 @@ An :class:`SMTP` instance has the following methods:
set to appropriate values.
User code does not normally need to call ``auth`` directly, but can instead
call the :meth:`login` method, which will try each of the above mechanisms in
turn, in the order listed. ``auth`` is exposed to facilitate the
implementation of authentication methods not (or not yet) supported directly
by :mod:`smtplib`.
call the :meth:`login` method, which will try each of the above mechanisms
in turn, in the order listed. ``auth`` is exposed to facilitate the
implementation of authentication methods not (or not yet) supported
directly by :mod:`smtplib`.
.. versionadded:: 3.5

34
Lib/smtplib.py
View File

@ -601,7 +601,7 @@ class SMTP:
if not (200 <= code <= 299):
raise SMTPHeloError(code, resp)
def auth(self, mechanism, authobject):
def auth(self, mechanism, authobject, *, initial_response_ok=True):
"""Authentication command - requires response processing.
'mechanism' specifies which authentication mechanism is to
@ -615,9 +615,20 @@ class SMTP:
It will be called to process the server's challenge response; the
challenge argument it is passed will be a bytes. It should return
bytes data that will be base64 encoded and sent to the server.
"""
Keyword arguments:
- initial_response_ok: Allow sending the RFC 4954 initial-response
to the AUTH command, if the authentication methods supports it.
"""
# RFC 4954 allows auth methods to provide an initial response. Not all
# methods support it. By definition, if they return something other
# than None when challenge is None, then they do. See issue #15014.
mechanism = mechanism.upper()
initial_response = (authobject() if initial_response_ok else None)
if initial_response is not None:
response = encode_base64(initial_response.encode('ascii'), eol='')
(code, resp) = self.docmd("AUTH", mechanism + " " + response)
else:
(code, resp) = self.docmd("AUTH", mechanism)
# Server replies with 334 (challenge) or 535 (not supported)
if code == 334:
@ -629,18 +640,21 @@ class SMTP:
return (code, resp)
raise SMTPAuthenticationError(code, resp)
def auth_cram_md5(self, challenge):
def auth_cram_md5(self, challenge=None):
""" Authobject to use with CRAM-MD5 authentication. Requires self.user
and self.password to be set."""
# CRAM-MD5 does not support initial-response.
if challenge is None:
return None
return self.user + " " + hmac.HMAC(
self.password.encode('ascii'), challenge, 'md5').hexdigest()
def auth_plain(self, challenge):
def auth_plain(self, challenge=None):
""" Authobject to use with PLAIN authentication. Requires self.user and
self.password to be set."""
return "\0%s\0%s" % (self.user, self.password)
def auth_login(self, challenge):
def auth_login(self, challenge=None):
""" Authobject to use with LOGIN authentication. Requires self.user and
self.password to be set."""
(code, resp) = self.docmd(
@ -649,13 +663,17 @@ class SMTP:
return self.password
raise SMTPAuthenticationError(code, resp)
def login(self, user, password):
def login(self, user, password, *, initial_response_ok=True):
"""Log in on an SMTP server that requires authentication.
The arguments are:
- user: The user name to authenticate with.
- password: The password for the authentication.
Keyword arguments:
- initial_response_ok: Allow sending the RFC 4954 initial-response
to the AUTH command, if the authentication methods supports it.
If there has been no previous EHLO or HELO command this session, this
method tries ESMTP EHLO first.
@ -698,7 +716,9 @@ class SMTP:
for authmethod in authlist:
method_name = 'auth_' + authmethod.lower().replace('-', '_')
try:
(code, resp) = self.auth(authmethod, getattr(self, method_name))
(code, resp) = self.auth(
authmethod, getattr(self, method_name),
initial_response_ok=initial_response_ok)
# 235 == 'Authentication successful'
# 503 == 'Error: already authenticated'
if code in (235, 503):

90
Lib/test/test_smtplib.py
View File

@ -1,6 +1,7 @@
import asyncore
import email.mime.text
from email.message import EmailMessage
from email.base64mime import body_encode as encode_base64
import email.utils
import socket
import smtpd
@ -814,11 +815,11 @@ class SMTPSimTests(unittest.TestCase):
def testVRFY(self):
smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=15)
for email, name in sim_users.items():
for addr_spec, name in sim_users.items():
expected_known = (250, bytes('%s %s' %
(name, smtplib.quoteaddr(email)),
(name, smtplib.quoteaddr(addr_spec)),
"ascii"))
self.assertEqual(smtp.vrfy(email), expected_known)
self.assertEqual(smtp.vrfy(addr_spec), expected_known)
u = 'nobody@nowhere.com'
expected_unknown = (550, ('No such user: %s' % u).encode('ascii'))
@ -851,7 +852,7 @@ class SMTPSimTests(unittest.TestCase):
def testAUTH_PLAIN(self):
self.serv.add_feature("AUTH PLAIN")
smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=15)
try: smtp.login(sim_auth[0], sim_auth[1])
try: smtp.login(sim_auth[0], sim_auth[1], initial_response_ok=False)
except smtplib.SMTPAuthenticationError as err:
self.assertIn(sim_auth_plain, str(err))
smtp.close()
@ -892,7 +893,7 @@ class SMTPSimTests(unittest.TestCase):
'LOGIN': smtp.auth_login,
}
for mechanism, method in supported.items():
try: smtp.auth(mechanism, method)
try: smtp.auth(mechanism, method, initial_response_ok=False)
except smtplib.SMTPAuthenticationError as err:
self.assertIn(sim_auth_credentials[mechanism.lower()].upper(),
str(err))
@ -1142,12 +1143,85 @@ class SMTPUTF8SimTests(unittest.TestCase):
smtp.send_message(msg))
EXPECTED_RESPONSE = encode_base64(b'\0psu\0doesnotexist', eol='')
class SimSMTPAUTHInitialResponseChannel(SimSMTPChannel):
def smtp_AUTH(self, arg):
# RFC 4954's AUTH command allows for an optional initial-response.
# Not all AUTH methods support this; some require a challenge. AUTH
# PLAIN does those, so test that here. See issue #15014.
args = arg.split()
if args[0].lower() == 'plain':
if len(args) == 2:
# AUTH PLAIN <initial-response> with the response base 64
# encoded. Hard code the expected response for the test.
if args[1] == EXPECTED_RESPONSE:
self.push('235 Ok')
return
self.push('571 Bad authentication')
class SimSMTPAUTHInitialResponseServer(SimSMTPServer):
channel_class = SimSMTPAUTHInitialResponseChannel
@unittest.skipUnless(threading, 'Threading required for this test.')
class SMTPAUTHInitialResponseSimTests(unittest.TestCase):
def setUp(self):
self.real_getfqdn = socket.getfqdn
socket.getfqdn = mock_socket.getfqdn
self.serv_evt = threading.Event()
self.client_evt = threading.Event()
# Pick a random unused port by passing 0 for the port number
self.serv = SimSMTPAUTHInitialResponseServer(
(HOST, 0), ('nowhere', -1), decode_data=True)
# Keep a note of what port was assigned
self.port = self.serv.socket.getsockname()[1]
serv_args = (self.serv, self.serv_evt, self.client_evt)
self.thread = threading.Thread(target=debugging_server, args=serv_args)
self.thread.start()
# wait until server thread has assigned a port number
self.serv_evt.wait()
self.serv_evt.clear()
def tearDown(self):
socket.getfqdn = self.real_getfqdn
# indicate that the client is finished
self.client_evt.set()
# wait for the server thread to terminate
self.serv_evt.wait()
self.thread.join()
def testAUTH_PLAIN_initial_response_login(self):
self.serv.add_feature('AUTH PLAIN')
smtp = smtplib.SMTP(HOST, self.port,
local_hostname='localhost', timeout=15)
smtp.login('psu', 'doesnotexist')
smtp.close()
def testAUTH_PLAIN_initial_response_auth(self):
self.serv.add_feature('AUTH PLAIN')
smtp = smtplib.SMTP(HOST, self.port,
local_hostname='localhost', timeout=15)
smtp.user = 'psu'
smtp.password = 'doesnotexist'
code, response = smtp.auth('plain', smtp.auth_plain)
smtp.close()
self.assertEqual(code, 235)
@support.reap_threads
def test_main(verbose=None):
support.run_unittest(GeneralTests, DebuggingServerTests,
support.run_unittest(
BadHELOServerTests,
DebuggingServerTests,
GeneralTests,
NonConnectingTests,
BadHELOServerTests, SMTPSimTests,
TooLongLineTests)
SMTPAUTHInitialResponseSimTests,
SMTPSimTests,
TooLongLineTests,
)
if __name__ == '__main__':
test_main()

3
Misc/NEWS
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@ -22,6 +22,9 @@ Library
- Issue #24259: tarfile now raises a ReadError if an archive is truncated
inside a data segment.
- Issue #15014: SMTP.auth() and SMTP.login() now support RFC 4954's optional
initial-response argument to the SMTP AUTH command.
What's New in Python 3.5.0 beta 3?
==================================