# Copyright (C) 2005 by Stefan Schlott # # 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. """Decrypt the incoming message using the list key """ from Mailman import Errors from Mailman.Logging.Syslog import syslog from Mailman import mm_cfg from Mailman import GPGUtils from Mailman import Utils from email.Parser import Parser from email.MIMEText import MIMEText def isAdministrativeMail(mlist, msg, msgdata): result = False if msgdata.get('torequest') or msgdata.get('toleave') \ or msgdata.get('tojoin') or msgdata.get('toconfirm'): result = True return result def enforceEncryptPolicy(mlist, msg, msgdata): result = True if msgdata.get('toowner') or msgdata.get('toleave') \ or msgdata.get('tojoin') or msgdata.get('toconfirm'): result = False if msgdata.get('torequest'): # This could be more sophisticated: # Parse message, enforce if commands containing passwords are used # These would be: password, subscribe, unsubscribe, who result = False return result def process(mlist, msg, msgdata): #syslog('gpg','GPG decryption module called') # Nothing to do when all encryption has been disabled. if mlist.encrypt_policy == 0: return plaintext = None ciphertext = None sigid = None sigmsg = None is_pgpmime = False # Check: Is inline pgp? if msg.get_content_type()=='application/pgp' or msg.get_param('x-action')=='pgp-encrypted': ciphertext = msg.get_payload() is_pgpmime = False # Check: Is pgp/mime? if msg.get_content_type()=='multipart/encrypted' and msg.get_param('protocol')=='application/pgp-encrypted': if msg.is_multipart(): for submsg in msg.get_payload(): if submsg.get_content_type()=='application/octet-stream': is_pgpmime = True ciphertext=submsg.get_payload() else: ciphertext = msg.get_payload() # Some clients send text/plain messages containing PGP-encrypted data :-( if not msg.is_multipart() and (ciphertext==None) and \ (len(msg.get_payload())>10): firstline = msg.get_payload().splitlines()[0] if firstline=='-----BEGIN PGP MESSAGE-----': syslog('gpg','Encrypted message detected, although MIME type is %s',msg.get_content_type()) is_pgpmime = False ciphertext = msg.get_payload() # Ciphertext present? Decode if ciphertext: gh = GPGUtils.GPGHelper(mlist) (plaintext,sigid) = gh.decryptMessage(ciphertext) if plaintext is None: syslog('gpg','Unable to decrypt GPG data') raise Errors.RejectMessage, "Unable to decrypt mail!" # Check decryption result if plaintext: # Good signature message if (not isAdministrativeMail(mlist,msg,msgdata)): if (not sigid is None): sigmsg = 'Message had a good signature from sender' if mlist.anonymous_list==0 or mlist.anonymous_list=='No': sigmsg += ' (key id %s)'%sigid else: sigmsg = 'Posting had no valid signature' # Check transfer type parser = Parser() #syslog('gpg','Test: plaintext=%s',plaintext) tmpmsg = parser.parsestr(plaintext) #syslog('gpg','Test: plaintext is\n%s\n',plaintext) #syslog('gpg','Test: Parsed inner message is\n%s\n',tmpmsg.as_string()) if msg.get_content_type()=='application/pgp': msg.set_type("text/plain") msg.del_param("x-action") for i in ('Content-Type','Content-Disposition','Content-Transfer-Encoding'): if tmpmsg.has_key(i): if msg.has_key(i): msg.replace_header(i,tmpmsg.get(i)) else: msg.add_header(i,tmpmsg.get(i)) #syslog('gpg','Test: Sigline=%s',sigmsg) if tmpmsg.is_multipart(): #syslog('gpg','Test: Multipart') msg.set_payload(None) for i in tmpmsg.get_payload(): msg.attach(i) if not sigmsg is None: sigfooter = MIMEText(sigmsg, 'plain', Utils.GetCharSet(mlist.preferred_language)) sigfooter['Content-Disposition'] = 'inline' msg.attach(sigfooter) else: #syslog('gpg','Test: Not multipart') tmppayload = tmpmsg.get_payload() if not sigmsg is None: if not tmppayload.endswith('\n'): tmppayload += '\n' tmppayload += '-- \n%s\n' % sigmsg msg.set_payload(tmppayload) if not is_pgpmime: mailclient = '' if msg.has_key('User-Agent'): mailclient = msg.get('User-Agent').lower() # Content-Transfer-Encoding and charset are not standardized... if mailclient.startswith('mutt'): msg.set_param('charset','utf-8') if msg.has_key('Content-Transfer-Encoding'): msg.replace_header('Content-Transfer-Encoding','utf-8') else: msg.add_header('Content-Transfer-Encoding','utf-8') else: # Just a wild guess... msg.set_param('charset','iso-8859-1') if msg.has_key('Content-Transfer-Encoding'): msg.replace_header('Content-Transfer-Encoding','8bit') else: msg.add_header('Content-Transfer-Encoding','8bit') #syslog('gpg','Test: Message is now\n%s\n',msg.as_string()) # --- Old Code --- #if is_pgpmime: # if tmpmsg.is_multipart(): # msg.set_payload(None) # for i in tmpmsg.get_payload(): # msg.attach(i) # if not sigid is None: # sigfooter = MIMEText(sigmsg, 'plain', Utils.GetCharSet(mlist.preferred_language)) # sigfooter['Content-Disposition'] = 'inline' # msg.attach(sigfooter) # else: # tmppayload = tmpmsg.get_payload() # if not sigid is None: # tmppayload += '\n-- \n%s\n' % sigmsg # msg.set_payload(tmppayload) #else: # # Set content header # #if msg.get_content_type()=='application/pgp': # # msg.set_type("text/plain") # #msg.del_param("x-action") # # Whole decrypted text is content # tmppayload = tmpmsg.get_payload() # if not sigid is None: # tmppayload += '\n-- \n%s\n' % sigmsg # msg.set_payload(tmppayload) elif mlist.encrypt_policy==2: if enforceEncryptPolicy(mlist,msg,msgdata): syslog('gpg','Throwing RejectMessage exception: Message has to be encrypted') raise Errors.RejectMessage, "Message has to be encrypted!" else: syslog('gpg','Accepting unencrypted message')