# Adds a configurable mime content stripper to Mailman's processing pipeline
diff -crN --exclude=mm_cfg.py Mailman.orig/Defaults.py Mailman/Defaults.py
*** Mailman.orig/Defaults.py	Wed Oct 24 23:31:13 2001
--- Mailman/Defaults.py	Tue Oct 30 22:55:21 2001
***************
*** 374,379 ****
--- 374,380 ----
      'CalcRecips',
      'Cleanse',
      'CookHeaders',
+     'MimeDel',
      # And now we send the message to the digest mbox file, and to the arch and
      # news queues.  Runners will provide further processing of the message,
      # specific to those delivery paths.
***************
*** 620,627 ****
  ADMIN_CATEGORIES = [
      # First column
      'general', 'passwords', 'language', 'members', 'nondigest', 'digest',
      # Second column
!     'privacy', 'bounce',    'archive',  'gateway', 'autoreply', 'topics',
      ]
  
  
--- 621,629 ----
  ADMIN_CATEGORIES = [
      # First column
      'general', 'passwords', 'language', 'members', 'nondigest', 'digest',
+     'privacy', 
      # Second column
!     'contentfilter', 'bounce',    'archive',  'gateway', 'autoreply', 'topics',
      ]
  
  
***************
*** 759,764 ****
--- 761,775 ----
  # setting this variable to 1, list owners will be given the option to suppress
  # these headers.
  ALLOW_RFC2369_OVERRIDES = 0
+ 
+ # List of regexps of mime types to be removed by MimeDel; None or empty
+ # list means don't alter messages.
+ DEFAULT_REJECT_MIME_TYPES = None
+ 
+ # Whether to syslog (in 'mimedel' log) every message processed by MimeDel.
+ # Useful for debugging or giving comfort to those who are unconvinced of
+ # MimeDel's accuracy.
+ LOG_MIMEDEL = 0
  
  # Check for administrivia in messages sent to the main list?
  DEFAULT_ADMINISTRIVIA = 1
diff -crN --exclude=mm_cfg.py Mailman.orig/Gui/ContentFilter.py Mailman/Gui/ContentFilter.py
*** Mailman.orig/Gui/ContentFilter.py	Wed Dec 31 16:00:00 1969
--- Mailman/Gui/ContentFilter.py	Wed Oct 31 10:29:02 2001
***************
*** 0 ****
--- 1,49 ----
+ # Copyright (C) 2001 by Les Niles <les@2pi.org>
+ #
+ # 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ 
+ """MailList mixin class managing the content filtering options.
+ """
+ 
+ from Mailman import mm_cfg
+ from Mailman import Utils
+ from Mailman.i18n import _
+ 
+ 
+ 
+ class ContentFilter:
+     def GetConfigCategory(self):
+         return 'contentfilter', _('Content-filtering&nbsp;options')
+ 
+     def GetConfigInfo(self, mlist, category, subcat=None):
+         if category <> 'contentfilter':
+             return None
+         WIDTH = mm_cfg.TEXTFIELDWIDTH
+ 
+         return [
+             _("Policies concerning concerning the content of list traffic."),
+ 
+             ('reject_mime_types', mm_cfg.Text, (10, WIDTH), 0,
+              _('Remove sections of messages that have a mime type matching one of these regexps'),
+              _('''Use this option to remove each message section whose mime
+              type matches one of a set of regexps (Python/Perl style regular
+              expressions).  Blank lines and lines beginning with "#" will
+              be ignored.
+              <br>For example, to remove all image types, use "image/.*"
+              (note the "." following the "/").
+              <br>Additionally, each "multipart/alternative" section will
+              be replaced by just the first alternative that is non-empty
+              after the specified types have been removed. ''')),
+             ]
diff -crN --exclude=mm_cfg.py Mailman.orig/Gui/__init__.py Mailman/Gui/__init__.py
*** Mailman.orig/Gui/__init__.py	Wed Oct 24 23:31:15 2001
--- Mailman/Gui/__init__.py	Mon Oct 29 14:52:36 2001
***************
*** 26,28 ****
--- 26,29 ----
  from Topics import Topics
  from Usenet import Usenet
  from Language import Language
+ from ContentFilter import ContentFilter
diff -crN --exclude=mm_cfg.py Mailman.orig/Handlers/MimeDel.py Mailman/Handlers/MimeDel.py
*** Mailman.orig/Handlers/MimeDel.py	Wed Dec 31 16:00:00 1969
--- Mailman/Handlers/MimeDel.py	Wed Oct 31 10:27:53 2001
***************
*** 0 ****
--- 1,184 ----
+ # Copyright (C) 2001 by Les Niles <les@2pi.org>
+ #
+ # 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ 
+ """Mime-stripping filter for Mailman.
+ 
+ This module scans a message for MIME content, removing those sections whose
+ mime types match one of a list of regexps.  multipart/alternative sections
+ are replaced by the first non-empty component, and multipart/mixed sections
+ wrapping only single sections after other processing are replaced by their
+ contents.
+ 
+ """
+ 
+ import string
+ import re
+ 
+ from Mailman import mm_cfg
+ from Mailman import Message
+ from email import Parser
+ from Mailman.Logging.Syslog import syslog
+ 
+ mime_headers = ['content-type', 'content-transfer-encoding',
+                 'content-disposition', 'content-description', 'content-id']
+                 
+ def replace_mime_headers(dest, src):
+     """ Use the headers in src to replace all the corresponding headers
+     in dest.  Also delete any other mime headers in dest.
+     """
+     # Remove pre-existing mime_headers from dest
+     for h in mime_headers:
+         del dest[h]
+     # Replace dest headers with corresponding values from src
+     for h, v in src.items():
+         del dest[h]
+         dest[h] = v
+     
+ def proc_part(msg, rejects):
+     """ Modify the contents of the msg in place by removing any
+     sections whose mime type matches any of the list of regexps in
+     rejects[].  Any multipart/mixed section that ends up with just one
+     component is replaced by that component, and any that ends up with no
+     components is removed.  Multipart/alternative sections are replaced by
+     the first non-empty component, or deleted if no components remain.
+     Return 0 if no changes were made to the msg, -1 if the msg ended up
+     empty and the caller can delete it entirely, and +1 if changes were
+     made resulting in a non-empty msg.
+     """
+     intype = msg.get_type()
+     if msg.is_multipart():              # Ensures that get_payload() is a list
+         if intype[:21] == 'multipart/alternative':
+             # Two possibilities:
+             # None of the alternative types is retained => caller should
+             #   delete this section entirely
+             # One or more of the alternative types is retained => replace
+             #   this section with the first retained type.
+             for part in msg.get_payload():
+                 mod = proc_part(part, rejects)
+                 if mod >= 0 and len(part.get_payload()) > 0:
+                     replace_mime_headers(msg, part)
+                     msg.set_payload(part.get_payload())
+                     return 1
+             return -1
+ 
+         elif intype[:15] == 'multipart/mixed' \
+              or intype[:17] == 'multipart/related':
+             # Three possibilities:
+             # None of the parts are retained => caller should delete
+             #   this section entirely
+             # Exactly one part is retained => that part should replace
+             #   this section
+             # Two or more parts are retained => Keep this section,
+             #   with those parts.
+             r = []
+             rmod = 0
+             for part in msg.get_payload():
+                 mod = proc_part(part, rejects)
+                 if mod >= 0 and len(part.get_payload()) > 0:
+                     r.append(part)
+                     if mod:
+                         rmod = 1
+                 else:
+                     rmod = 1
+             if not r:
+                 return -1
+             if len(r) == 1:
+                 replace_mime_headers(msg, r[0])
+                 msg.set_payload(r[0].get_payload())
+             elif rmod:
+                 msg.set_payload(r)
+             return rmod
+ 
+     # Fall through here => Not multipart/mixed or multipart/alternative
+     for x in rejects:
+         if x.match(intype):
+             return -1
+     return 0
+ 
+ 
+ 
+ def process(mlist, msg, msgdata):
+     try:
+         if not mlist.reject_mime_types:
+             return                 # => This list doesn't want MimeDel
+     except:
+         return                          # Old-version list object
+     
+     # Short-circuit processing for plain-text and digests:
+     ct = msg.get_type()
+     if msgdata.get('isdigest') or not ct or ct[:10] == 'text/plain':
+         return
+     
+     rejects = []
+     for line in mlist.reject_mime_types.split('\n'):
+         line = line.strip()
+         if not line or line[0] == '#':
+             continue
+         # Require, at a minimum, a '/' with something before and after:
+         n = line.find('/')
+         if n < 1 or n >= len(line)-1:
+             syslog('config', 'bad reject_mime_types line in %s:\n%s\n',
+                    mlist.real_name, line)
+         else:
+             try:
+                 rejects.append(re.compile(line, re.IGNORECASE))
+             except re.error, err:
+                 syslog('config', '''\
+ bad regexp in reject_mime_types line in %s:\n%s (cause: %s)''',
+                        mlist.real_name, line, err)
+     if not rejects:
+         return
+ 
+     p = Parser.Parser()
+     parsed = p.parsestr(msg.as_string(unixfrom=1))
+ 
+     mod = proc_part(parsed, rejects)
+ 
+     if not mod:
+         return
+     
+     repmsg = """
+ --------------------------------------------------------------------
+ MimeDel received the following message
+ --------------------------------------------------------------------
+ \n  """ + string.replace(msg.as_string(), '\n', '\n  ')
+ 
+     replace_mime_headers(msg, parsed)   # Deletes mime headers if result empty
+     if mod < 0:
+         msg.set_payload('[The body of this message was removed by MimeDel]\n')
+     else:
+         if msg.preamble:
+             pre = msg.preamble+'\n'
+         else:
+             pre = ''
+         pre = pre + '[This message was processed by MimeDel]\n\n'
+         if parsed.is_multipart():
+             msg.set_payload(parsed.get_payload())
+             msg.preamble = pre
+         else:
+             msg.set_payload(pre + parsed.get_payload())
+ 
+     repmsg = repmsg + """
+ --------------------------------------------------------------------
+ And replaced it with the following
+ --------------------------------------------------------------------
+ \n  """ + string.replace(msg.as_string(), '\n', '\n  ') + '\n\n'
+ 
+     if mm_cfg.LOG_MIMEDEL:
+         try:
+             syslog('mimedel', repmsg)
+         except:
+             pass
diff -crN --exclude=mm_cfg.py Mailman.orig/MailList.py Mailman/MailList.py
*** Mailman.orig/MailList.py	Wed Oct 24 23:31:13 2001
--- Mailman/MailList.py	Mon Oct 29 11:47:14 2001
***************
*** 319,324 ****
--- 319,325 ----
          self.discard_these_nonmembers = []
          self.forward_auto_discards = mm_cfg.DEFAULT_FORWARD_AUTO_DISCARDS
          self.generic_nonmember_action = mm_cfg.DEFAULT_GENERIC_NONMEMBER_ACTION
+         self.reject_mime_types = mm_cfg.DEFAULT_REJECT_MIME_TYPES
  	# BAW: This should really be set in SecurityManager.InitVars()
  	self.password = crypted_password