# Copyright (C) 1998-2017 by the Free Software Foundation, Inc. # # This file is part of GNU Mailman. # # GNU Mailman 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. # # GNU Mailman 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 # GNU Mailman. If not, see . """Cook a message's headers.""" import logging from email.header import Header from email.utils import formataddr, getaddresses, parseaddr from mailman.core.i18n import _ from mailman.interfaces.handler import IHandler from mailman.interfaces.mailinglist import Personalization, ReplyToMunging from mailman.version import VERSION from public import public from zope.interface import implementer log = logging.getLogger('mailman.error') COMMASPACE = ', ' MAXLINELEN = 78 @public def uheader(mlist, s, header_name=None, continuation_ws='\t', maxlinelen=None): """Get the charset to encode the string in. Then search if there is any non-ascii character is in the string. If there is and the charset is us-ascii then we use iso-8859-1 instead. If the string is ascii only we use 'us-ascii' if another charset is specified. If the header contains a newline, truncate it (see GL#273). """ charset = mlist.preferred_language.charset if '\n' in s: s = '{} [...]'.format(s.split('\n')[0]) log.warning('Header {} contains a newline, truncating it.'.format( header_name, s)) return Header(s, charset, maxlinelen, header_name, continuation_ws) def process(mlist, msg, msgdata): """Process the headers of the message.""" # Set the "X-Ack: no" header if noack flag is set. if msgdata.get('noack'): del msg['x-ack'] msg['X-Ack'] = 'no' # Because we're going to modify various important headers in the email # message, we want to save some of the information in the msgdata # dictionary for later. Specifically, the sender header will get waxed, # but we need it for the Acknowledge module later. msgdata['original_sender'] = msg.sender # VirginRunner sets _fasttrack for internally crafted messages. fasttrack = msgdata.get('_fasttrack') # Add Precedence: and other useful headers. None of these are standard # and finding information on some of them are fairly difficult. Some are # just common practice, and we'll add more here as they become necessary. # Good places to look are: # # http://www.dsv.su.se/~jpalme/ietf/jp-ietf-home.html # http://www.faqs.org/rfcs/rfc2076.html # # None of these headers are added if they already exist. BAW: some # consider the advertising of this a security breach. I.e. if there are # known exploits in a particular version of Mailman and we know a site is # using such an old version, they may be vulnerable. It's too easy to # edit the code to add a configuration variable to handle this. if 'x-mailman-version' not in msg: msg['X-Mailman-Version'] = VERSION # We set "Precedence: list" because this is the recommendation from the # sendmail docs, the most authoritative source of this header's semantics. if 'precedence' not in msg: msg['Precedence'] = 'list' # Reply-To: munging. Do not do this if the message is "fast tracked", # meaning it is internally crafted and delivered to a specific user. BAW: # Yuck, I really hate this feature but I've caved under the sheer pressure # of the (very vocal) folks want it. OTOH, RFC 2822 allows Reply-To: to # be a list of addresses, so instead of replacing the original, simply # augment it. RFC 2822 allows max one Reply-To: header so collapse them # if we're adding a value, otherwise don't touch it. (Should we collapse # in all cases?) if not fasttrack: # A convenience function, requires nested scopes. pair is (name, addr) new = [] d = {} def add(pair): # noqa: E306 lcaddr = pair[1].lower() if lcaddr in d: return d[lcaddr] = pair new.append(pair) # List admin wants an explicit Reply-To: added if mlist.reply_goes_to_list is ReplyToMunging.explicit_header: add(parseaddr(mlist.reply_to_address)) # If we're not first stripping existing Reply-To: then we need to add # the original Reply-To:'s to the list we're building up. In both # cases we'll zap the existing field because RFC 2822 says max one is # allowed. if not mlist.first_strip_reply_to: orig = msg.get_all('reply-to', []) for pair in getaddresses(orig): add(pair) # Set Reply-To: header to point back to this list. Add this last # because some folks think that some MUAs make it easier to delete # addresses from the right than from the left. if mlist.reply_goes_to_list is ReplyToMunging.point_to_list: i18ndesc = uheader(mlist, mlist.description, 'Reply-To') add((str(i18ndesc), mlist.posting_address)) del msg['reply-to'] # Don't put Reply-To: back if there's nothing to add! if new: # Preserve order msg['Reply-To'] = COMMASPACE.join( [formataddr(pair) for pair in new]) # The To field normally contains the list posting address. However # when messages are fully personalized, that header will get # overwritten with the address of the recipient. We need to get the # posting address in one of the recipient headers or they won't be # able to reply back to the list. It's possible the posting address # was munged into the Reply-To header, but if not, we'll add it to a # Cc header. BAW: should we force it into a Reply-To header in the # above code? # Also skip Cc if this is an anonymous list as list posting address # is already in From and Reply-To in this case. if (mlist.personalize is Personalization.full and mlist.reply_goes_to_list is not # noqa: W503 ReplyToMunging.point_to_list and not mlist.anonymous_list): # noqa: W503 # Watch out for existing Cc headers, merge, and remove dups. Note # that RFC 2822 says only zero or one Cc header is allowed. new = [] d = {} for pair in getaddresses(msg.get_all('cc', [])): add(pair) i18ndesc = uheader(mlist, mlist.description, 'Cc') add((str(i18ndesc), mlist.posting_address)) del msg['Cc'] msg['Cc'] = COMMASPACE.join([formataddr(pair) for pair in new]) @public @implementer(IHandler) class CookHeaders: """Modify message headers.""" name = 'cook-headers' description = _('Modify message headers.') def process(self, mlist, msg, msgdata): """See `IHandler`.""" process(mlist, msg, msgdata)