kolab_smtp_access_policy.py
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kolab_smtp_access_policy.py
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	#!/usr/bin/python
	#
	# Copyright 2010-2013 Kolab Systems AG (http://www.kolabsys.com)
	#
	# Jeroen van Meeuwen (Kolab Systems) <vanmeeuwen a kolabsys.com>
	#
	# This program is free software: you can redistribute it and/or modify
	# it under the terms of the GNU General Public License as published by
	# the Free Software Foundation, either version 3 of the License, or
	# (at your option) any later version.

	# This program is distributed in the hope that it will be useful,
	# but WITHOUT ANY WARRANTY; without even the implied warranty of
	# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	# GNU General Public License for more details.

	# You should have received a copy of the GNU General Public License
	# along with this program. If not, see <http://www.gnu.org/licenses/>.
	#

	import datetime
	import os
	import sys
	import time

	from optparse import OptionParser
	from ConfigParser import SafeConfigParser

	cache = None

	import sqlalchemy
	from sqlalchemy import Boolean
	from sqlalchemy import Column
	from sqlalchemy import Date
	from sqlalchemy import DateTime
	from sqlalchemy import Integer
	from sqlalchemy import MetaData
	from sqlalchemy import String
	from sqlalchemy import Table

	from sqlalchemy import create_engine
	from sqlalchemy.orm import mapper
	try:
	from sqlalchemy.orm import sessionmaker
	except:
	from sqlalchemy.orm import create_session

	from sqlalchemy.schema import Index
	from sqlalchemy.schema import UniqueConstraint

	sys.path = ['..','.'] + sys.path

	import pykolab

	from pykolab import utils
	from pykolab.auth import Auth
	from pykolab.constants import *
	from pykolab.translate import _

	# TODO: Figure out how to make our logger do some syslogging as well.
	log = pykolab.getLogger('pykolab.smtp_access_policy')

	# TODO: Removing the stdout handler would mean one can no longer test by
	# means of manual execution in debug mode.
	#log.remove_stdout_handler()

	conf = pykolab.getConf()

	auth = None
	mydomains = None

	#
	# Caching routines using SQLAlchemy.
	#
	# If creating the cache fails, we continue without any caching, significantly
	# increasing the load on LDAP.
	#
	cache_expire = 86400
	try:
	metadata = MetaData()
	except:
	cache = False

	session = None
	policy_result_table = Table(
	'policy_result', metadata,
	Column('id', Integer, primary_key=True),
	Column('key', String(16), nullable=False),
	Column('value', Boolean, nullable=False),
	Column('sender', String(64), nullable=False),
	Column('recipient', String(64), nullable=False),
	Column('sasl_username', String(64)),
	Column('sasl_sender', String(64)),
	Column('created', Integer, nullable=False),
	)

	Index(
	'fsrss',
	policy_result_table.c.key,
	policy_result_table.c.sender,
	policy_result_table.c.recipient,
	policy_result_table.c.sasl_username,
	policy_result_table.c.sasl_sender,
	unique=True
	)

	class PolicyResult(object):
	def __init__(
	self,
	key=None,
	value=None,
	sender=None,
	recipient=None,
	sasl_username=None,
	sasl_sender=None
	):

	self.key = key
	self.value = value
	self.sender = sender
	self.sasl_username = sasl_username
	self.sasl_sender = sasl_sender
	self.recipient = recipient
	self.created = (int)(time.time())

	mapper(PolicyResult, policy_result_table)

	statistic_table = Table(
	'statistic', metadata,
	Column('id', Integer, primary_key=True),
	Column('sender', String(64), nullable=False),
	Column('recipient', String(64), nullable=False),
	Column('date', Date, nullable=False),
	Column('count', Integer, nullable=False),
	)

	Index(
	'srd',
	statistic_table.c.sender,
	statistic_table.c.recipient,
	statistic_table.c.date,
	unique=True
	)

	class Statistic(object):
	def __init__(self, sender, recipient, date=datetime.date.today(), count=0):
	self.sender = sender
	self.recipient = recipient
	self.date = date
	self.count = count

	mapper(Statistic, statistic_table)

	class PolicyRequest(object):
	email_address_keys = [ 'sender', 'recipient' ]
	recipients = []

	auth = None

	sasl_domain = None
	sasl_user = None
	sender_domain = None
	sender_user = None

	sasl_user_uses_alias = False
	sasl_user_is_delegate = False

	def __init__(self, policy_request={}):
	"""
	Creates a new policy request object. Pass it a policy_request
	dictionary as described in the Postfix documentation on:

	http://www.postfix.org/SMTPD_POLICY_README.html
	"""
	for key in policy_request.keys():

	# Normalize email addresses (they may contain recipient delimiters)
	if key in self.email_address_keys:
	policy_request[key] = normalize_address(policy_request[key])

	if not key == 'recipient':
	if policy_request[key] == '':
	setattr(self, key, None)
	else:
	setattr(self, key, policy_request[key])

	else:
	if not policy_request['recipient'].strip() == '':
	self.recipients = list(set(self.recipients + [policy_request['recipient']]))

	def add_request(self, policy_request={}):
	"""
	Add subsequent policy requests to the existing policy request.

	All data in the request should be the same as the initial policy
	request, but for the recipient - with destination limits set over
	1, Postfix may attempt to deliver messages to more then one
	recipient during a single delivery attempt, and during submission,
	the policy will receive one policy request per recipient.
	"""

	# Check instance. Not sure what to do if the instance is not the same.
	if hasattr(self, 'instance'):
	if not policy_request['instance'] == self.instance:
	# TODO: We need to empty our pockets
	pass

	log.debug(
	_("Adding policy request to instance %s") % (self.instance),
	level=8
	)

	# Normalize email addresses (they may contain recipient delimiters)
	if policy_request.has_key('recipient'):
	policy_request['recipient'] = normalize_address(
	policy_request['recipient']
	)

	if not policy_request['recipient'].strip() == '':
	self.recipients = list(set(self.recipients + [policy_request['recipient']]))

	def parse_ldap_dn(self, dn):
	"""
	See if parameter 'dn' is a basestring LDAP dn, and if so, return
	the results we can obtain from said DN. Return a list of relevant
	attribute values.

	If not a DN, return None.
	"""
	values = []

	try:
	import ldap.dn

	ldap_dn = ldap.dn.explode_dn(dn)

	except ldap.DECODING_ERROR:
	# This is not a DN.
	return None

	if len(ldap_dn) > 0:
	search_attrs = conf.get_list(
	'kolab_smtp_access_policy',
	'address_search_attrs'
	)

	rule_subject = self.auth.get_user_attributes(
	self.sasl_domain,
	{ 'dn': dn },
	search_attrs + [ 'objectclass' ]
	)

	for search_attr in search_attrs:
	if rule_subject.has_key(search_attr):
	if isinstance(rule_subject[search_attr], basestring):
	values.append(rule_subject[search_attr])
	else:
	values.extend(rule_subject[search_attr])

	return values

	else:
	# ldap.dn.explode_dn didn't error out, but it also didn't split
	# the DN properly.
	return None

	def parse_ldap_uri(self, uri):
	values = []

	parsed_uri = utils.parse_ldap_uri(uri)

	if parsed_uri == None:
	return None

	(_protocol, _server, _port, _base_dn, _attrs, _scope, _filter) = \
	parsed_uri

	if len(_attrs) == 0:
	search_attrs = conf.get_list(
	'kolab_smtp_access_policy',
	'address_search_attrs'
	)
	else:
	search_attrs = [ _attrs ]

	users = []

	self.auth._auth._bind()
	_users = self.auth._auth._search(
	_base_dn,
	scope=LDAP_SCOPE[_scope],
	filterstr=_filter,
	attrlist=search_attrs + [ 'objectclass' ],
	override_search="_regular_search"
	)

	for _user in _users:
	for search_attr in search_attrs:
	values.extend(_user[1][search_attr])

	return values

	def parse_policy(self, _subject, _object, policy):
	"""
	Parse policy to apply on _subject, for object _object.

	The policy is a list of rules.

	The _subject is a sender for kolabAllowSMTPRecipient checks, and
	a recipient for kolabAllowSMTPSender checks.

	The _object is a recipient for kolabAllowSMTPRecipient checks, and
	a sender for kolabAllowSMTPSender checks.
	"""

	special_rule_values = {
	'$mydomains': expand_mydomains
	}

	rules = { 'allow': [], 'deny': [] }

	if isinstance(policy, basestring):
	policy = [policy]

	for rule in policy:
	# Find rules that are actually special values, simply by
	# mapping the rule onto a key in "special_rule_values", a
	# dictionary with the corresponding value set to a function to
	# execute.
	if rule in special_rule_values.keys():
	special_rules = special_rule_values[rule]()
	if rule.startswith("-"):
	rules['deny'].extend(special_rules)
	else:
	rules['allow'].extend(special_rules)

	continue

	# Lower-case the rule
	rule = rule.lower()

	# Also note the '-' cannot be passed on to the functions that
	# follow, so store the rule separately from the prefix that is
	# prepended to deny rules.
	if rule.startswith("-"):
	_prefix = '-'
	_rule = rule[1:]
	else:
	_prefix = ''
	_rule = rule

	# See if the value is an LDAP DN
	ldap_dn = self.parse_ldap_dn(_rule)

	if not ldap_dn == None and len(ldap_dn) > 0:
	if _prefix == '-':
	rules['deny'].extend(ldap_dn)
	else:
	rules['allow'].extend(ldap_dn)
	else:
	ldap_uri = self.parse_ldap_uri(_rule)

	if not ldap_uri == None and len(ldap_uri) > 0:
	if _prefix == '-':
	rules['deny'].extend(ldap_uri)
	else:
	rules['allow'].extend(ldap_uri)

	else:
	if rule.startswith("-"):
	rules['deny'].append(rule[1:])
	else:
	rules['allow'].append(rule)

	allowed = False
	for rule in rules['allow']:
	deny_override = False

	if _object.endswith(rule):
	for deny_rule in rules['deny']:
	if deny_rule.endswith(rule):
	deny_override = True

	if not deny_override:
	allowed = True

	denied = False

	for rule in rules['deny']:
	allow_override = False
	if _object.endswith(rule):
	if not allowed:
	denied = True
	continue
	else:
	for allow_rule in rules['allow']:
	if allow_rule.endswith(rule):
	allow_override = True

	if not allow_override:
	denied = True

	if not denied:
	allowed = True

	return allowed

	def verify_alias(self):
	"""
	Verify whether the user authenticated for this policy request is
	using an alias of its primary authentication ID / attribute.

	John.Doe@example.org (mail) for example could be sending with
	envelope sender jdoe@example.org (mailAlternateAddress, alias).
	"""

	search_attrs = conf.get_list(self.sasl_domain, 'address_search_attrs')

	if search_attrs == None or \
	(isinstance(search_attrs, list) and len(search_attrs) == 0):

	search_attrs = conf.get_list(self.sasl_domain, 'mail_attributes')

	if search_attrs == None or \
	(isinstance(search_attrs, list) and len(search_attrs) == 0):

	search_attrs = conf.get_list(
	'kolab_smtp_access_policy',
	'address_search_attrs'
	)

	if search_attrs == None or \
	(isinstance(search_attrs, list) and len(search_attrs) == 0):


	search_attrs = conf.get_list(
	conf.get('kolab', 'auth_mechanism'),
	'mail_attributes'
	)

	want_attrs = []

	for search_attr in search_attrs:
	if not self.sasl_user.has_key(search_attr):
	want_attrs.append(search_attr)

	if len(want_attrs) > 0:
	self.sasl_user.update(
	self.auth.get_user_attributes(
	self.sasl_domain,
	self.sasl_user,
	want_attrs
	)
	)

	# Catch a user using one of its own alias addresses.
	for search_attr in search_attrs:
	if self.sasl_user.has_key(search_attr):
	if isinstance(self.sasl_user[search_attr], list):
	if self.sender.lower() in [x.lower() for x in self.sasl_user[search_attr]]:
	return True
	elif self.sasl_user[search_attr].lower() == self.sender.lower():
	return True

	return False

	def verify_authenticity(self):
	"""
	Verify that the SASL username or lack thereof corresponds with
	allowing or disallowing authenticated users.

	If an SASL username is supplied, use it to obtain the authentication
	database user object including all attributes we may find ourselves
	interested in.
	"""

	if self.sasl_username == None:
	if not conf.allow_unauthenticated:
	reject(_("Unauthorized access not allowed"))
	else:
	# If unauthenticated is allowed, I have nothing to do here.
	return True

	sasl_username = self.sasl_username

	# If we have an sasl_username, find the user object in the
	# authentication database, along with the attributes we are
	# interested in.
	if self.sasl_domain == None:
	if len(self.sasl_username.split('@')) > 1:
	self.sasl_domain = self.sasl_username.split('@')[1]
	else:
	self.sasl_domain = conf.get('kolab', 'primary_domain')
	sasl_username = "%s@%s" % (self.sasl_username, self.sasl_domain)

	if self.auth == None:
	self.auth = Auth(self.sasl_domain)
	elif not self.auth.domain == self.sasl_domain:
	self.auth = Auth(self.sasl_domain)

	sasl_users = self.auth.find_recipient(
	sasl_username,
	domain=self.sasl_domain
	)

	if isinstance(sasl_users, list):
	if len(sasl_users) == 0:
	log.error(_("Could not find recipient"))
	return False
	else:
	self.sasl_user = { 'dn': sasl_users[0] }
	elif isinstance(sasl_users, basestring):
	self.sasl_user = { 'dn': sasl_users }

	if not self.sasl_user['dn']:
	# Got a final answer here, do the caching thing.
	cache_update(
	function='verify_sender',
	sender=self.sender,
	recipients=self.recipients,
	result=(int)(False),
	sasl_username=self.sasl_username,
	sasl_sender=self.sasl_sender
	)

	reject(
	_("Could not find envelope sender user %s (511)") % (
	self.sasl_username
	)
	)

	attrs = conf.get_list(self.sasl_domain, 'auth_attributes')

	if attrs == None or (isinstance(attrs, list) and len(attrs) == 0):
	attrs = conf.get_list(
	conf.get('kolab', 'auth_mechanism'),
	'auth_attributes'
	)

	mail_attrs = conf.get_list(self.sasl_domain, 'mail_attributes')
	if mail_attrs == None or \
	(isinstance(mail_attrs, list) and len(mail_attrs) == 0):

	mail_attrs = conf.get_list(
	conf.get('kolab', 'auth_mechanism'),
	'mail_attributes'
	)

	if not mail_attrs == None:
	attrs.extend(mail_attrs)

	attrs.extend(
	[
	'kolabAllowSMTPRecipient',
	'kolabAllowSMTPSender'
	]
	)

	attrs = list(set(attrs))

	user_attrs = self.auth.get_user_attributes(
	self.sasl_domain,
	self.sasl_user,
	attrs
	)

	user_attrs['dn'] = self.sasl_user['dn']
	self.sasl_user = utils.normalize(user_attrs)
	log.debug(
	_("Obtained authenticated user details for %r: %r") % (
	self.sasl_user['dn'],
	self.sasl_user.keys()
	),
	level=8
	)

	def verify_delegate(self):
	"""
	Verify whether the authenticated user is a delegate of the envelope
	sender.
	"""

	if self.sender_domain == None:
	if len(self.sender.split('@')) > 1:
	self.sender_domain = self.sender.split('@')[1]
	else:
	self.sender_domain = conf.get('kolab', 'primary_domain')

	if self.sender == self.sasl_username:
	return True

	search_attrs = conf.get_list(self.sender_domain, 'mail_attributes')
	if search_attrs == None:
	search_attrs = conf.get_list(
	conf.get('kolab', 'auth_mechanism'),
	'mail_attributes'
	)

	sender_users = self.auth.find_recipient(
	self.sender,
	domain=self.sender_domain
	)

	if isinstance(sender_users, list):
	if len(sender_users) > 1:
	# More then one sender user with this recipient address.
	# TODO: check each of the sender users found.
	self.sender_user = { 'dn': sender_users[0] }
	elif len(sender_users) == 1:
	self.sender_user = { 'dn': sender_users }
	else:
	self.sender_user = { 'dn': False }

	elif isinstance(sender_users, basestring):
	self.sender_user = { 'dn': sender_users }

	if not self.sender_user['dn']:
	cache_update(
	function='verify_sender',
	sender=self.sender,
	recipients=self.recipients,
	result=(int)(False),
	sasl_username=self.sasl_username,
	sasl_sender=self.sasl_sender
	)

	reject(_("Could not find envelope sender user %s") % (self.sender))

	attrs = search_attrs
	attrs.extend(
	[
	'kolabAllowSMTPRecipient',
	'kolabAllowSMTPSender',
	'kolabDelegate'
	]
	)

	user_attrs = self.auth.get_user_attributes(
	self.sender_domain,
	self.sender_user,
	attrs
	)

	user_attrs['dn'] = self.sender_user['dn']
	self.sender_user = utils.normalize(user_attrs)

	if not self.sender_user.has_key('kolabdelegate'):
	reject(
	_("%s is unauthorized to send on behalf of %s") % (
	self.sasl_user['dn'],
	self.sender_user['dn']
	)
	)

	elif self.sender_user['kolabdelegate'] == None:
	# No delegates for this sender could be found. The user is
	# definitely NOT a delegate of the sender.
	log.warning(
	_("User %s attempted to use envelope sender address %s without authorization") % (
	policy_request["sasl_username"],
	policy_request["sender"]
	)
	)

	# Got a final answer here, do the caching thing.
	if not cache == False:
	record_id = cache_update(
	function='verify_sender',
	sender=self.sender,
	recipients=self.recipients,
	result=(int)(False),
	sasl_username=self.sasl_username,
	sasl_sender=self.sasl_sender
	)

	sender_is_delegate = False

	else:
	# See if we can match the value of the envelope sender delegates to
	# the actual sender sasl_username
	if self.sasl_user == None:
	sasl_users = self.auth.find_recipient(
	self.sasl_username,
	domain=self.sasl_domain
	)

	if isinstance(sasl_users, list):
	if len(sasl_users) == 0:
	log.error(_("Could not find recipient"))
	return False
	else:
	self.sasl_user = { 'dn': sasl_users[0] }
	elif isinstance(sasl_users, basestring):
	self.sasl_user = { 'dn': sasl_users }

	# Possible values for the kolabDelegate attribute are:
	# a 'uid', a 'dn'.
	if not self.sasl_user.has_key('uid'):
	self.sasl_user['uid'] = self.auth.get_user_attribute(
	self.sasl_domain,
	self.sasl_user,
	'uid'
	)

	sender_delegates = self.sender_user['kolabdelegate']

	if not type(sender_delegates) == list:
	sender_delegates = [ sender_delegates ]

	for sender_delegate in sender_delegates:
	if self.sasl_user['dn'] == sender_delegate:
	log.debug(
	_("Found user %s to be a delegate user of %s") % (
	policy_request["sasl_username"],
	policy_request["sender"]
	),
	level=8
	)

	sender_is_delegate = True

	elif self.sasl_user['uid'] == sender_delegate:
	log.debug(
	_("Found user %s to be a delegate user of %s") % (
	policy_request["sasl_username"],
	policy_request["sender"]
	),
	level=8
	)

	sender_is_delegate = True

	# If nothing matches sender_is_delegate is still None.
	if not sender_is_delegate == True:
	sender_is_delegate = False

	return sender_is_delegate

	def verify_recipient(self, recipient):
	"""
	Verify whether the sender is allowed send to this recipient, using
	the recipient's kolabAllowSMTPSender.
	"""

	self.recipient = recipient

	if not self.sasl_username == '' and not self.sasl_username == None:
	log.debug(_("Verifying authenticated sender '%(sender)s' with sasl_username '%(sasl_username)s' for recipient '%(recipient)s'") % (self.__dict__)
	)
	else:
	log.debug(_("Verifying unauthenticated sender '%(sender)s' for recipient '%(recipient)s'") % (self.__dict__)
	)

	recipient_verified = False

	if not cache == False:
	records = cache_select(
	function='verify_recipient',
	sender=self.sender,
	recipient=recipient,
	sasl_username=self.sasl_username,
	sasl_sender=self.sasl_sender,
	)

	if not records == None and len(records) == 1:
	log.info(
	_("Reproducing verify_recipient(%s, %s) from cache") % (
	self.sender,
	recipient
	)
	)

	return records[0].value

	# TODO: Under some conditions, the recipient may not be fully qualified.
	# We'll cross that bridge when we get there, though.
	if len(recipient.split('@')) > 1:
	sasl_domain = recipient.split('@')[1]
	else:
	sasl_domain = conf.get('kolab', 'primary_domain')
	recipient = "%s@%s" % (recipient,sasl_domain)

	if not verify_domain(sasl_domain):
	if not cache == False:
	cache_update(
	function='verify_recipient',
	sender=self.sender,
	recipient=recipient,
	result=(int)(True),
	sasl_username=self.sasl_username,
	sasl_sender=self.sasl_sender
	)

	return True

	if self.auth == None:
	self.auth = Auth(sasl_domain)
	elif not self.auth.domain == sasl_domain:
	self.auth = Auth(sasl_domain)

	if verify_domain(sasl_domain):
	if not self.auth.domains == None and self.auth.domains.has_key(sasl_domain):
	log.debug(
	_("Using authentication domain %s instead of %s") % (
	self.auth.domains[sasl_domain],
	sasl_domain
	),
	level=8
	)

	sasl_domain = self.auth.domains[sasl_domain]
	else:
	log.debug(
	_("Domain %s is a primary domain") % (
	sasl_domain
	),
	level=8
	)

	else:
	log.warning(
	_("Checking the recipient for domain %s that is not ours. This is probably a configuration error.") % (
	sasl_domain
	)
	)

	return True

	recipients = self.auth.find_recipient(
	normalize_address(recipient),
	domain=sasl_domain,
	)

	if isinstance(recipients, list):
	if len(recipients) > 1:
	log.info(
	_("This recipient address is related to multiple object entries and the SMTP Access Policy can therefore not restrict message flow")
	)

	cache_update(
	function='verify_recipient',
	sender=self.sender,
	recipient=normalize_address(recipient),
	result=(int)(True),
	sasl_username=self.sasl_username,
	sasl_sender=self.sasl_sender
	)

	return True
	elif len(recipients) == 1:
	_recipient = { 'dn': recipients[0] }
	else:
	log.debug(
	_("Recipient address %r not found. Allowing since the MTA was configured to accept the recipient.") % (
	normalize_address(recipient)
	),
	level=3
	)

	cache_update(
	function='verify_recipient',
	sender=self.sender,
	recipient=normalize_address(recipient),
	result=(int)(True),
	sasl_username=self.sasl_username,
	sasl_sender=self.sasl_sender
	)

	return True

	elif isinstance(recipients, basestring):
	_recipient = {
	'dn': recipients
	}

	# We have gotten an invalid recipient. We need to catch this case,
	# because testing can input invalid recipients, and so can faulty
	# applications, or misconfigured servers.
	if not _recipient['dn']:
	if not conf.allow_unauthenticated:
	cache_update(
	function='verify_recipient',
	sender=self.sender,
	recipient=normalize_address(recipient),
	result=(int)(False),
	sasl_username=self.sasl_username,
	sasl_sender=self.sasl_sender
	)

	reject(_("Invalid recipient"))
	else:
	cache_update(
	function='verify_recipient',
	sender=self.sender,
	recipient=normalize_address(recipient),
	result=(int)(True),
	sasl_username=self.sasl_username,
	sasl_sender=self.sasl_sender
	)

	log.debug(_("Could not find this user, accepting"), level=8)
	return True

	if not _recipient['dn'] == False:
	recipient_policy = self.auth.get_entry_attribute(
	sasl_domain,
	_recipient['dn'],
	'kolabAllowSMTPSender'
	)

	# If no such attribute has been specified, allow
	if recipient_policy == None:
	cache_update(
	function='verify_recipient',
	sender=self.sender,
	recipient=normalize_address(recipient),
	result=(int)(True),
	sasl_username=self.sasl_username,
	sasl_sender=self.sasl_sender
	)

	recipient_verified = True

	# Otherwise, parse the policy obtained with the subject of the policy
	# being the recipient, and the object to apply the policy to being the
	# sender.
	else:
	recipient_verified = self.parse_policy(
	recipient,
	self.sender,
	recipient_policy
	)

	cache_update(
	function='verify_recipient',
	sender=self.sender,
	recipient=normalize_address(recipient),
	result=(int)(recipient_verified),
	sasl_username=self.sasl_username,
	sasl_sender=self.sasl_sender
	)

	return recipient_verified

	def verify_recipients(self):
	"""
	Verify whether the sender is allowed send to the recipients in this
	policy request, using each recipient's kolabAllowSMTPSender.

	Note there may be multiple recipients in this policy request, and
	therefor self.recipients is a list - walk through that list.
	"""

	recipients_verified = True

	if not cache == False:
	records = cache_select(
	function='verify_recipient',
	sender=self.sender,
	recipients=self.recipients,
	sasl_username=self.sasl_username,
	sasl_sender=self.sasl_sender,
	)

	if not records == None and len(records) == len(self.recipients):
	log.debug("Euh, what am I doing here?")
	for record in records:
	recipient_found = False
	for recipient in self.recipients:
	if recipient == record.recipient:
	recipient_found = True

	if not recipient_found:
	reject(_("Sender %s is not allowed to send to recipient %s") % (self.sender,recipient))

	for recipient in self.recipients:
	recipient_verified = self.verify_recipient(recipient)
	if not recipient_verified:
	recipients_verified = False

	return recipients_verified

	def verify_sender(self):
	"""
	Verify the sender's access policy.

	1) Verify whether the sasl_username is allowed to send using the
	envelope sender address, with the kolabDelegate attribute
	associated with the LDAP object that has the envelope sender
	address.

	2) Verify whether the sender is allowed to send to recipient(s)
	listed on the sender's object.

	A third potential action could be to check the recipient object to
	see if the sender is allowed to send to the recipient by the
	recipient's kolabAllowSMTPSender, but this is done in
	verify_recipients().
	"""

	sender_verified = False

	if self.sender == None:
	# Trusted host?
	if not hasattr(self, 'client_address') or \
	self.client_address == "" or \
	self.client_address == None:

	# Nothing to compare to.
	return False

	try:
	import netaddr

	networks = conf.get_list(
	'kolab_smtp_access_policy',
	'empty_sender_hosts'
	)

	trusted = False
	for network in networks:
	if netaddr.IPNetwork(self.client_address) in netaddr.IPNetwork(network):
	return True

	except ImportError, errmsg:
	return False

	if not cache == False:
	records = cache_select(
	sender=self.sender,
	recipients=self.recipients,
	sasl_username=self.sasl_username,
	sasl_sender=self.sasl_sender,
	function='verify_sender'
	)

	if not records == None and len(records) == len(self.recipients):
	log.info(_("Reproducing verify_sender(%r) from cache") % (
	self.__dict__
	)
	)

	for record in records:
	recipient_found = False
	for recipient in self.recipients:
	if recipient == record.recipient:
	recipient_found = True

	if recipient_found and not record.value:
	reject(_("Sender %s is not allowed to send to recipient %s") % (self.sender,recipient))

	return True

	if self.verify_authenticity() == False:
	reject(_("Unverifiable sender."))

	self.sasl_user_uses_alias = self.verify_alias()

	if not self.sasl_user_uses_alias:
	log.debug(_("Sender is not using an alias"), level=8)
	self.sasl_user_is_delegate = self.verify_delegate()

	# If the authenticated user is using delegate functionality, apply the
	# recipient policy attribute for the envelope sender.
	if self.sasl_user_is_delegate == False and \
	self.sasl_user_uses_alias == False:

	reject(_("Sender uses unauthorized envelope sender address"))

	elif self.sasl_user_is_delegate:
	# Apply the recipient policy for the sender using the envelope
	# sender user object.
	recipient_policy_domain = self.sender_domain
	recipient_policy_sender = self.sender
	recipient_policy_user = self.sender_user

	elif not self.sasl_user == None:
	# Apply the recipient policy from the authenticated user.
	recipient_policy_domain = self.sasl_domain
	recipient_policy_sender = self.sasl_username
	recipient_policy_user = self.sasl_user

	else:
	if not conf.allow_unauthenticated:
	reject(_("Could not verify sender"))
	else:
	recipient_policy_domain = self.sender_domain
	recipient_policy_sender = self.sender
	recipient_policy_user = self.sender_user

	log.debug(
	_("Verifying whether sender is allowed to send to recipient using sender policy"),
	level=8
	)

	if recipient_policy_user.has_key('kolaballowsmtprecipient'):
	recipient_policy = recipient_policy_user['kolaballowsmtprecipient']
	else:
	recipient_policy = self.auth.get_user_attribute(
	recipient_policy_domain,
	recipient_policy_user,
	'kolabAllowSMTPRecipient'
	)

	log.debug(_("Result is %r") % (recipient_policy), level=8)

	# If no such attribute has been specified, allow
	if recipient_policy == None:
	log.debug(
	_("No recipient policy restrictions exist for this sender"),
	level=8
	)

	sender_verified = True

	# Otherwise,parse the policy obtained.
	else:
	log.debug(
	_("Found a recipient policy to apply for this sender."),
	level=8
	)

	recipient_allowed = None

	for recipient in self.recipients:
	recipient_allowed = self.parse_policy(
	recipient_policy_sender,
	recipient,
	recipient_policy
	)

	if not recipient_allowed:
	reject(
	_("Sender %s not allowed to send to recipient %s") % (recipient_policy_user['dn'],recipient)
	)

	sender_verified = True

	if not cache == False:
	record_id = cache_update(
	function='verify_sender',
	sender=self.sender,
	recipients=self.recipients,
	result=(int)(sender_verified),
	sasl_username=self.sasl_username,
	sasl_sender=self.sasl_sender
	)

	return sender_verified

	def cache_cleanup():
	if not cache == True:
	return

	log.debug(_("Cleaning up the cache"), level=8)
	session.query(
	PolicyResult
	).filter(
	PolicyResult.created < ((int)(time.time()) - cache_expire)
	).delete()

	def cache_init():
	global cache, cache_expire, session

	if conf.has_section('kolab_smtp_access_policy'):
	if conf.has_option('kolab_smtp_access_policy', 'cache_uri'):
	cache_uri = conf.get('kolab_smtp_access_policy', 'cache_uri')
	cache = True
	if conf.has_option('kolab_smtp_access_policy', 'retention'):
	cache_expire = (int)(
	conf.get(
	'kolab_smtp_access_policy',
	'retention'
	)
	)
	elif conf.has_option('kolab_smtp_access_policy', 'uri'):
	log.warning(_("The 'uri' setting in the kolab_smtp_access_policy section is soon going to be deprecated in favor of 'cache_uri'"))
	cache_uri = conf.get('kolab_smtp_access_policy', 'uri')
	cache = True
	else:
	return False
	else:
	return False

	if conf.debuglevel > 8:
	engine = create_engine(cache_uri, echo=True)
	else:
	engine = create_engine(cache_uri, echo=False)

	try:
	metadata.create_all(engine)
	except sqlalchemy.exc.OperationalError, e:
	log.error(_("Operational Error in caching: %s" % (e)))
	return False

	Session = sessionmaker(bind=engine)
	session = Session()
	cache_cleanup()

	return cache

	def cache_select(
	function,
	sender,
	recipient='',
	recipients=[],
	sasl_username='',
	sasl_sender=''
	):

	if not cache == True:
	return None

	if not recipient == '' and recipients == []:
	recipients = [recipient]

	return session.query(
	PolicyResult
	).filter_by(
	key=function,
	sender=sender,
	sasl_username=sasl_username,
	sasl_sender=sasl_sender
	).filter(
	PolicyResult.recipient.in_(recipients)
	).filter(
	PolicyResult.created >= \
	((int)(time.time()) - cache_expire)
	).all()

	def cache_insert(
	function,
	sender,
	recipient='',
	recipients=[],
	result=None,
	sasl_username='',
	sasl_sender=''
	):

	if not cache == True:
	return []

	log.debug(
	_("Caching the policy result with timestamp %d") % (
	(int)(time.time())
	),
	level=8
	)

	if not recipient == '' and recipients == []:
	recipients = [recipient]

	for recipient in recipients:
	session.add(
	PolicyResult(
	key=function,
	value=result,
	sender=sender,
	recipient=recipient,
	sasl_username=sasl_username,
	sasl_sender=sasl_sender
	)
	)

	session.commit()

	def cache_update(
	function,
	sender,
	recipient='',
	recipients=[],
	result=None,
	sasl_username='',
	sasl_sender=''
	):

	"""
	Insert an updated set of rows into the cache depending on the necessity
	"""

	if not cache == True:
	return

	records = []

	_records = cache_select(
	function,
	sender,
	recipient,
	recipients,
	sasl_username,
	sasl_sender
	)

	for record in _records:
	if record.value == (int)(result):
	records.append(record)

	if not recipient == '' and recipients == []:
	recipients = [recipient]

	for recipient in recipients:
	recipient_found = False
	for record in records:
	if record.recipient == recipient:
	recipient_found = True
	if not recipient_found:
	cache_insert(
	function=function,
	sender=sender,
	recipient=recipient,
	result=result,
	sasl_username=sasl_username,
	sasl_sender=sasl_sender
	)

	def defer_if_permit(message, policy_request=None):
	log.info(_("Returning action DEFER_IF_PERMIT: %s") % (message))
	print "action=DEFER_IF_PERMIT %s\n\n" % (message)
	sys.exit(0)

	def dunno(message, policy_request=None):
	log.info(_("Returning action DUNNO: %s") % (message))
	print "action=DUNNO %s\n\n" % (message)
	sys.exit(0)

	def hold(message, policy_request=None):
	log.info(_("Returning action HOLD: %s") % (message))
	print "action=HOLD %s\n\n" % (message)
	sys.exit(0)

	def permit(message, policy_request=None):
	log.info(_("Returning action PERMIT: %s") % (message))

	# If we have no policy request, we have been called for a reason,
	# and everything relevant has been figured out already.
	if policy_request == None:
	print "action=PERMIT\n\n"
	sys.exit(0)

	# If the user is not authenticated, there's no reason to do
	# extra checks here -- to have been performed already.
	if not hasattr(policy_request, 'sasl_username'):
	print "action=PERMIT\n\n"
	sys.exit(0)

	# Same here.
	if policy_request.sasl_username == None:
	print "action=PERMIT\n\n"
	sys.exit(0)

	delegate_sender_header = None
	alias_sender_header = None

	# If the sender is a delegate of the envelope sender address, take into
	# account the preferred domain policy for appending the Sender and/or
	# X-Sender headers.
	#
	# Note that a delegatee by very definition is not using an alias.
	#
	if policy_request.sasl_user_is_delegate:
	# Domain-specific setting?
	if not policy_request.sender_domain == None:
	delegate_sender_header = conf.get(policy_request.sender_domain, 'delegate_sender_header')

	# Global setting?
	if delegate_sender_header == None:
	delegate_sender_header = conf.get('kolab_smtp_access_policy', 'delegate_sender_header')

	# Default
	if delegate_sender_header == None:
	delegate_sender_header = True

	# If the sender is using an alias as the envelope sender address, take
	# into account the preferred domain policy for appending the Sender
	# and/or X-Sender headers.
	elif policy_request.sasl_user_uses_alias:
	# Domain-specific setting?
	if not policy_request.sender_domain == None:
	alias_sender_header = conf.get(policy_request.sender_domain, 'alias_sender_header')

	# Global setting?
	if alias_sender_header == None:
	alias_sender_header = conf.get('kolab_smtp_access_policy', 'alias_sender_header')

	# Default
	if alias_sender_header == None:
	alias_sender_header = True

	# Make the values booleans
	delegate_sender_header = utils.true_or_false(delegate_sender_header)
	alias_sender_header = utils.true_or_false(alias_sender_header)

	# Do we use a (simple) encryption key to obscure the headers' contents?
	# Note that using an encryption key voids the actual use of proper Sender
	# and X-Sender headers such as they could be interpreted by a client
	# application.
	enc_key = conf.get(policy_request.sender_domain, 'sender_header_enc_key')
	if enc_key == None:
	enc_key = conf.get('kolab_smtp_access_policy', 'sender_header_enc_key')

	sender_header = None
	xsender_header = None

	if delegate_sender_header or alias_sender_header:
	# Domain specific?
	sender_header = conf.get(policy_request.sender_domain, 'sender_header')

	# Global setting?
	if sender_header == None:
	sender_header = conf.get('kolab_smtp_access_policy', 'sender_header')

	# Default
	if sender_header == None:
	sender_header = True

	# Domain specific?
	xsender_header = conf.get(policy_request.sender_domain, 'xsender_header')

	# Global setting?
	if xsender_header == None:
	xsender_header = conf.get('kolab_smtp_access_policy', 'xsender_header')

	# Default
	if xsender_header == None:
	xsender_header = True

	# Note that if the user is not a delegatee, and not using an alias, the sender
	# address is the envelope sender address, and the defaults for sender_header
	# and xsender_header being None, ultimately evaluating to False seems
	# appropriate.

	# Make the values booleans
	sender_header = utils.true_or_false(sender_header)
	xsender_header = utils.true_or_false(xsender_header)

	if sender_header or xsender_header:
	# Do the encoding, if any
	if not enc_key == None:
	header = 'X-Authenticated-As'
	xheader = None
	sender = utils.encode(enc_key, policy_request.sasl_username)
	else:
	header = 'Sender'
	xheader = 'X-Sender'
	sender = policy_request.sasl_username

	if sender_header:
	print "action=PREPEND %s: %s" % (header, sender)

	if xsender_header and not xheader == None:
	print "action=PREPEND %s: %s" % (xheader, sender)

	print "action=PERMIT\n\n"
	sys.exit(0)

	def reject(message, policy_request=None):
	log.info(_("Returning action REJECT: %s") % (message))
	print "action=REJECT %s\n\n" % (message)
	sys.exit(0)

	def expand_mydomains():
	"""
	Return a list of my domains.
	"""

	global auth,mydomains

	if not mydomains == None:
	return mydomains

	auth.connect()

	mydomains = auth.list_domains()

	return mydomains.keys()

	def normalize_address(email_address):
	"""
	Parse an address; Strip off anything after a recipient delimiter.
	"""

	# TODO: Recipient delimiter is configurable.
	if len(email_address.split("+")) > 1:
	# Take the first part split by recipient delimiter and the last part
	# split by '@'.
	return "%s@%s" % (
	email_address.split("+")[0].lower(),
	# TODO: Under some conditions, the recipient may not be fully
	# qualified. We'll cross that bridge when we get there, though.
	email_address.split('@')[1].lower()
	)
	else:
	return email_address.lower()

	def read_request_input():
	"""
	Read a single policy request from sys.stdin, and return a dictionary
	containing the request.
	"""

	start_time = time.time()

	log.debug(_("Starting to loop for new request"))

	policy_request = {}

	end_of_request = False
	while not end_of_request:
	if (time.time()-start_time) >= conf.timeout:
	log.warning(_("Timeout for policy request reading exceeded"))
	sys.exit(0)

	request_line = sys.stdin.readline()
	if request_line.strip() == '':
	if policy_request.has_key('request'):
	log.debug(_("End of current request"), level=8)
	end_of_request = True
	else:
	request_line = request_line.strip()
	log.debug(_("Getting line: %s") % (request_line), level=8)
	policy_request[request_line.split('=')[0]] = \
	'='.join(request_line.split('=')[1:]).lower()

	log.debug(_("Returning request"))

	return policy_request

	def verify_domain(domain):
	"""
	Verify whether the domain is internal (mine) or external.
	"""

	global auth,mydomains

	if not mydomains == None:
	return domain in mydomains.keys()

	auth.connect()

	domain_verified = False

	mydomains = auth.list_domains()

	if not mydomains == None and mydomains.has_key(domain):
	domain_verified = True
	else:
	domain_verified = False

	return domain_verified

	if __name__ == "__main__":
	access_policy_group = conf.add_cli_parser_option_group(
	_("Access Policy Options")
	)

	access_policy_group.add_option( "--timeout",
	dest = "timeout",
	action = "store",
	default = 10,
	help = _("SMTP Policy request timeout."))

	access_policy_group.add_option( "--verify-recipient",
	dest = "verify_recipient",
	action = "store_true",
	default = False,
	help = _("Verify the recipient access policy."))

	access_policy_group.add_option( "--verify-sender",
	dest = "verify_sender",
	action = "store_true",
	default = False,
	help = _("Verify the sender access policy."))

	access_policy_group.add_option( "--allow-unauthenticated",
	dest = "allow_unauthenticated",
	action = "store_true",
	default = False,
	help = _("Allow unauthenticated senders."))

	conf.finalize_conf()

	auth = Auth()

	cache = cache_init()

	policy_requests = {}

	# Start the work
	while True:
	policy_request = read_request_input()
	instance = policy_request['instance']
	log.debug(_("Got request instance %s") % (instance))
	if policy_requests.has_key(instance):
	policy_requests[instance].add_request(policy_request)
	else:
	policy_requests[instance] = PolicyRequest(policy_request)

	protocol_state = policy_request['protocol_state'].strip().lower()

	log.debug(
	_("Request instance %s is in state %s") % (
	instance,
	protocol_state
	)
	)

	if not protocol_state == 'data':
	log.debug(
	_("Request instance %s is not yet in DATA state") % (
	instance
	)
	)

	print "action=DUNNO\n\n"
	sys.stdout.flush()

	# We can recognize being in the DATA part by the recipient_count being
	# set to a non-zero value and the protocol_state being set to 'data'.
	# Note that the input we're getting is a string, not an integer.
	else:
	log.debug(_("Request instance %s reached DATA state") % (instance))

	sender_allowed = False
	recipient_allowed = False

	try:
	if conf.verify_sender:
	sender_allowed = policy_requests[instance].verify_sender()
	else:
	sender_allowed = True

	if conf.verify_recipient:
	recipient_allowed = \
	policy_requests[instance].verify_recipients()

	else:
	recipient_allowed = True

	except Exception, errmsg:
	import traceback
	log.error(_("Unhandled exception caught: %r") % (errmsg))
	log.error(traceback.format_exc())

	if not sender_allowed:
	reject(_("Sender access denied"))
	elif not recipient_allowed:
	reject(_("Recipient access denied"))
	else:
	permit(_("No objections"), policy_requests[instance])

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