path: root/Mailman/app/chains.py

# Copyright (C) 2007 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 built-in rule chains."""

from __future__ import with_statement

__all__ = [
    'AcceptChain',
    'DiscardChain',
    'HoldChain',
    'RejectChain',
    ]
__metaclass__ = type


import logging

from Mailman import i18n
from Mailman.Message import UserNotification
from Mailman.Utils import maketext, oneline, wrap, GetCharSet
from Mailman.app.bounces import bounce_message
from Mailman.app.moderator import hold_message
from Mailman.app.replybot import autorespond_to_sender, can_acknowledge
from Mailman.configuration import config
from Mailman.i18n import _
from Mailman.interfaces import IChain, IChainLink, IMutableChain, IPendable
from Mailman.queue import Switchboard

log = logging.getLogger('mailman.vette')
elog = logging.getLogger('mailman.error')
SEMISPACE = '; '



class HeldMessagePendable(dict):
    implements(IPendable)
    PEND_KEY = 'held message'



class DiscardChain:
    """Discard a message."""
    implements(IChain)

    name = 'discard'
    description = _('Discard a message and stop processing.')

    def process(self, mlist, msg, msgdata):
        """See `IChain`."""
        log.info('DISCARD: %s', msg.get('message-id', 'n/a'))
        # Nothing more needs to happen.



class HoldChain:
    """Hold a message."""
    implements(IChain)

    name = 'hold'
    description = _('Hold a message and stop processing.')

    def process(self, mlist, msg, msgdata):
        """See `IChain`."""
        # Start by decorating the message with a header that contains a list
        # of all the rules that matched.
        msg['X-Mailman-Rule-Hits'] = SEMISPACE.join(msgdata['rules'])
        # Hold the message by adding it to the list's request database.
        # XXX How to calculate the reason?
        request_id = hold_message(mlist, msg, msgdata, None)
        # Calculate a confirmation token to send to the author of the
        # message.
        pendable = HeldMessagePendable(type=HeldMessagePendable.PEND_KEY,
                                       id=request_id)
        token = config.db.pendings.add(pendable)
        # Get the language to send the response in.  If the sender is a
        # member, then send it in the member's language, otherwise send it in
        # the mailing list's preferred language.
        member = mlist.members.get_member(sender)
        language = (member.preferred_language
                    if member else mlist.preferred_language)
        # A substitution dictionary for the email templates.
        charset = GetCharSet(mlist.preferred_language)
        original_subject = msg.get('subject')
        if original_subject is None:
            original_subject = _('(no subject)')
        else:
            original_subject = oneline(original_subject, charset)
        substitutions = {
            'listname'  : mlist.fqdn_listname,
            'subject'   : original_subject,
            'reason'    : 'XXX', #reason,
            'confirmurl': '%s/%s' % (mlist.script_url('confirm'), token),
            }
        sender = msg.get_sender()
        # At this point the message is held, but now we have to craft at least
        # two responses.  The first will go to the original author of the
        # message and it will contain the token allowing them to approve or
        # discard the message.  The second one will go to the moderators of
        # the mailing list, if the list is so configured.
        #
        # Start by possibly sending a response to the message author.  There
        # are several reasons why we might not go through with this.  If the
        # message was gated from NNTP, the author may not even know about this
        # list, so don't spam them.  If the author specifically requested that
        # acknowledgments not be sent, or if the message was bulk email, then
        # we do not send the response.  It's also possible that either the
        # mailing list, or the author (if they are a member) have been
        # configured to not send such responses.
        if (not msgdata.get('fromusenet') and
            can_acknowledge(msg) and
            mlist.respond_to_post_requests and
            autorespond_to_sender(mlist, sender, language)):
            # We can respond to the sender with a message indicating their
            # posting was held.
            subject = _(
              'Your message to $mlist.fqdn_listname awaits moderator approval')
            language = msgdata.get('lang', lang)
            text = maketext('postheld.txt', substitutions,
                            lang=language, mlist=mlist)
            nmsg = UserNotification(sender, adminaddr, subject, text, language)
            nmsg.send(mlist)
        # Now the message for the list moderators.  This one should appear to
        # come from <list>-owner since we really don't need to do bounce
        # processing on it.
        if mlist.admin_immed_notify:
            # Now let's temporarily set the language context to that which the
            # administrators are expecting.
            with i18n.using_language(mlist.preferred_language):
                language = mlist.preferred_language
                charset = GetCharSet(language)
                # We need to regenerate or re-translate a few values in the
                # substitution dictionary.
                d['reason'] = _(reason)
                d['subject'] = original_subject
                # craft the admin notification message and deliver it
                subject = _(
                    '$mlist.fqdn_listname post from $sender requires approval')
                nmsg = UserNotification(mlist.owner_address,
                                        mlist.owner_address,
                                        subject, lang=language)
                nmsg.set_type('multipart/mixed')
                text = MIMEText(
                    maketext('postauth.txt', substitution,
                             raw=True, mlist=mlist),
                    _charset=charset)
                dmsg = MIMEText(wrap(_("""\
If you reply to this message, keeping the Subject: header intact, Mailman will
discard the held message.  Do this if the message is spam.  If you reply to
this message and include an Approved: header with the list password in it, the
message will be approved for posting to the list.  The Approved: header can
also appear in the first line of the body of the reply.""")),
                                _charset=GetCharSet(lang))
                dmsg['Subject'] = 'confirm ' + token
                dmsg['Sender'] = requestaddr
                dmsg['From'] = requestaddr
                dmsg['Date'] = email.utils.formatdate(localtime=True)
                dmsg['Message-ID'] = email.utils.make_msgid()
                nmsg.attach(text)
                nmsg.attach(MIMEMessage(msg))
                nmsg.attach(MIMEMessage(dmsg))
                nmsg.send(mlist, **{'tomoderators': 1})
        # Log the held message
        log.info('HELD: %s post from %s held, message-id=%s: %s',
                 listname, sender, message_id, reason)



class RejectChain:
    """Reject/bounce a message."""
    implements(IChain)

    name = 'reject'
    description = _('Reject/bounce a message and stop processing.')

    def process(self, mlist, msg, msgdata):
        """See `IChain`."""
        # XXX Exception/reason
        bounce_message(mlist, msg)
        log.info('REJECT: %s', msg.get('message-id', 'n/a'))



class AcceptChain:
    """Accept the message for posting."""
    implements(IChain)

    name = 'accept'
    description = _('Accept a message.')

    def process(self, mlist, msg, msgdata):
        """See `IChain.`"""
        accept_queue = Switchboard(config.PREPQUEUE_DIR)
        accept_queue.enqueue(msg, msgdata)
        log.info('ACCEPT: %s', msg.get('message-id', 'n/a'))



class Link:
    """A chain link."""
    implements(IChainLink)

    def __init__(self, rule, jump):
        self.rule = rule
        self.jump = jump


class Chain:
    """Default built-in moderation chain."""
    implements(IMutableChain)

    def __init__(self, name, description):
        self.name = name
        self.description = description
        self._links = []

    def append_link(self, link):
        """See `IMutableChain`."""
        self._links.append(link)

    def flush(self):
        """See `IMutableChain`."""
        self._links = []

    def process(self, mlist, msg, msgdata):
        """See `IMutableChain`."""
        msgdata['rules'] = rules = []
        jump = None
        for link in self._links:
            # The None rule always match.
            if link.rule is None:
                jump = link.jump
                break
            # If the rule hits, just to the given chain.
            rule = config.rules.get(link.rule)
            if rule is None:
                elog.error('Rule not found: %s', rule)
            elif rule.check(mlist, msg, msgdata):
                rules.append(link.rule.name)
                # None is a special jump meaning "keep processing this chain".
                if link.jump is not None:
                    jump = link.jump
                    break
        else:
            # We got through the entire chain without a jumping rule match, so
            # we really don't know what to do.  Rather than raise an
            # exception, jump to the discard chain.
            log.info('Jumping to the discard chain by default.')
            jump = 'discard'
        # Find the named chain.
        chain = config.chains.get(jump)
        if chain is None:
            elog.error('Chain not found: %s', chain)
            # Well, what now?  Nothing much left to do but discard the
            # message, which we can do by simply returning.
        else:
            chain.process(mlist, msg, msgdata)



def initialize():
    """Set up chains, both built-in and from the database."""
    for chain_class in (DiscardChain, HoldChain, RejectChain, AcceptChain):
        chain = chain_class()
        assert chain.name not in config.chains, (
            'Duplicate chain name: %s' % chain.name)
        config.chains[chain.name] = chain
    # Set up a couple of other default chains.
    default = Chain('built-in', _('The built-in moderation chain'), 'accept')
    default.append_link(Link('approved', 'accept'))
    default.append_link(Link('emergency', 'hold'))
    default.append_link(Link('loop', 'discard'))
    # Do all these before deciding whether to hold the message for moderation.
    default.append_link(Link('administrivia', None))
    default.append_link(Link('implicit-dest', None))
    default.append_link(Link('max-recipients', None))
    default.append_link(Link('max-size', None))
    default.append_link(Link('news-moderation', None))
    default.append_link(Link('no-subject', None))
    default.append_link(Link('suspicious', None))
    # Now if any of the above hit, jump to the hold chain.
    default.append_link(Link('any', 'hold'))
    # Finally, the builtin chain defaults to acceptance.
    default.append_link(Link(None, 'accept'))
    # XXX Read chains from the database and initialize them.
    pass