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# Copyright (C) 2007-2008 by the Free Software Foundation, Inc.
#
# 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 2
# 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, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
# USA.
"""The implicit destination rule."""
__all__ = ['ImplicitDestination']
__metaclass__ = type
import re
from email.utils import getaddresses
from zope.interface import implements
from mailman.i18n import _
from mailman.interfaces import IRule
class ImplicitDestination:
"""The implicit destination rule."""
implements(IRule)
name = 'implicit-dest'
description = _('Catch messages with implicit destination.')
record = True
def check(self, mlist, msg, msgdata):
"""See `IRule`."""
# Implicit destination checking must be enabled in the mailing list.
if not mlist.require_explicit_destination:
return False
# Messages gated from NNTP will always have an implicit destination so
# are never checked.
if msgdata.get('fromusenet'):
return False
# Calculate the list of acceptable aliases. If the alias starts with
# a caret (i.e. ^), then it's a regular expression to match against.
aliases = set()
alias_patterns = set()
for alias in mlist.acceptable_aliases.splitlines():
alias = alias.strip().lower()
if alias.startswith('^'):
alias_patterns.add(alias)
elif '@' in alias:
aliases.add(alias)
else:
# This is not a regular expression, nor a fully-qualified
# email address, so skip it.
pass
# Add the list's posting address, i.e. the explicit address, to the
# set of acceptable aliases.
aliases.add(mlist.posting_address)
# Look at all the recipients. If the recipient is any acceptable
# alias (or the explicit posting address), then this rule does not
# match. If not, then add it to the set of recipients we'll check
# against the alias patterns later.
recipients = set()
for header in ('to', 'cc', 'resent-to', 'resent-cc'):
for fullname, address in getaddresses(msg.get_all(header, [])):
address = address.lower()
if address in aliases:
return False
recipients.add(address)
# Now for all alias patterns, see if any of the recipients matches a
# pattern. If so, then this rule does not match.
for pattern in alias_patterns:
escaped = re.escape(pattern)
for recipient in recipients:
try:
if re.match(pattern, recipient, re.IGNORECASE):
return False
except re.error:
# The pattern is a malformed regular expression. Try
# matching again with the pattern escaped.
try:
if re.match(escaped, recipient, re.IGNORECASE):
return False
except re.error:
pass
# Nothing matched.
return True
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