crypto-exmlm: added python interface

This commit is contained in:
lars 2009-11-04 00:28:01 +00:00
parent 1fd5f5fca1
commit ca7ade45b8
3 changed files with 464 additions and 0 deletions

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#!/usr/bin/env python2.4
#
# This file is part of lispet - an encryption filter for the
# ezmlm-idx mailinglist manager.
#
# Copyright 02007 Sense.Lab e.V. <info@senselab.org>
#
# This script decrypts an incoming mail and encrypts it for each recipient
# separately. Afterwards it calls qmail-queue for each recipient.
# It is meant as a wrapper around qmail-queue. See 'man qmail-queue' for
# details of the qmail-queue interface.
#
# Syntax:
# lispet-encrypt [MAILINGLIST_DIRECTORY]
#
# If no MAILINGLIST_DIRECTORY is given, then it will only run some self-tests.
#
# Environment settings:
# - QMAILQUEUE should contain the path of the qmail-queue program (or a
# substitute - e.g. for spam filtering) - otherwise the default location
# /var/qmail/bin/qmail-queue is used
#
#
# lispet 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.
#
# lispet 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 the CryptoBox; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#
# TODO:
# implement 'sign_messages'
# implement 'hide_subject'
import sys
import os
import re
#the following modules are imported later
# import configobj
# try to load the module configobj
try:
import configobj
except ImportError:
sys.stderr.write("Failed to import the required module 'configobj'. "
. "Please check if it is installed!\n")
sys.exit(1)
############### some default settings ##################
## default settings - the setting keys must always be lower case!
DEFAULT_SETTINGS = {
"plain_without_key": False,
"sign_messages": False,
"gnupg_dir": ".gnupg"
}
def read_config(self):
"""Read the config file.
If a value is not defined in the config file, then the default value
is used.
Any line that does not really look like a config setting is ignored.
Any unknown configuration settings are ignored, too.
"""
result = DEFAULT_SETTINGS
## retrieve the absolute path of the configuration file
## by default it is relative to the mailinglist's directory
if os.path.isabs(CONF_FILE):
conf_file = CONF_FILE
else:
conf_file = os.path.join(self.list_dir, CONF_FILE)
if not os.access(conf_file, os.R_OK):
internal_error("Could not read gpgpy-ezmlm config file: %s" % conf_file)
## read all lines of the configuration file
all_lines = [ e.strip() for e in file(conf_file).readlines() ]
for line in all_lines:
## ignore empty lines, comments and lines without "="
if (not line) or e.startswith("#") or (e.find("=") == -1):
continue
key, value = line.split("=", 1)
## turn everything to lower case and remove surrounding whitespace
key, value = (key.strip().lower(), value.strip())
if (len(value) > 1) and \
((value.startswith('"') and value.endswith('"')) \
or (value.startswith("'") and value.endswith("'"))):
value = value[1:-1]
## ignore empty values or keys
if not key or not value:
continue
## check boolean values
if key in ['plain_without_key', 'sign_messages']:
if value.lower() == 'no':
result[key] = False
elif value.lower() == 'yes':
result[key] = True
else:
continue
## process the key directory
elif key == 'gnupg_dir':
result[key] = value
## unknown setting - ignore
else:
continue
if result["gnupg_dir"].startswith('~'):
result["gnupg_dir"] = os.path.expanduser(result["gnupg_dir"])
elif not os.path.isabs(result["gnupg_dir"]):
result["gnupg_dir"] = os.path.abspath(os.path.join(
self.list_dir, result["gnupg_dir"]))
return result

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#!/usr/bin/env python2.4
#
# This file is part of lispet - an encryption filter for different
# mailing list manager.
#
# Copyright 02007-02008 Sense.Lab e.V. <info@senselab.org>
#
#
# lispet 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.
#
# lispet 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 the CryptoBox; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#
import sys
import os
import re
# the following modules are imported later
#import subprocess
# check if the subprocess module is available (python >= 2.4)
try:
import subprocess
except ImportError:
sys.stderr.write("Failed to import the python module 'subprocess'! "
. "It requires python2.4 or higher.\n")
sys.exit(1)
############### some default settings ##################
## we will finally deliver via the original qmail-queue
if os.environ.has_key("QMAILQUEUE"):
QMAILQUEUE_BIN = os.environ["QMAILQUEUE"]
else:
QMAILQUEUE_BIN = '/var/qmail/bin/qmail-queue'
def write_to_qmailqueue:
## use tmpfile as input for qmail-queue
## we have to complicate things a little bit, as qmail-queue expects input
## at file handle 1 - this is usually stdout
# TODO: use something like StringIO instead
tmpfile = os.tmpfile()
tmpfile.write('F%s\0T%s\0\0' % (sender, recipient))
tmpfile.seek(0)
## execute the original qmail-queue
proc = subprocess.Popen(
shell = False,
stdin = subprocess.PIPE,
stdout = tmpfile.fileno(),
env = os.environ,
args = [ QMAILQUEUE_BIN ] )
proc.stdin.write(mail.as_string())
## tmpfile is deleted automatically after closing
tmpfile.close()
proc.stdin.close()
proc.wait()
## exit immediately, if qmail-queue failed once
if proc.returncode != 0:
sys.exit(proc.returncode)
#################### input/output stuff ###################
def internal_error(message=None, exitcode=81):
if message:
sys.stderr.write(message + "\n")
sys.exit(exitcode)
def process_input_and_output(handler):
"""Read mail content and the envelopement information from fd1 and fd2
see 'main qmail-queue' for details
"""
in_mail = os.fdopen(0, "r")
in_envelope = os.fdopen(1, "rb")
## try to read mail and
try:
mail_text = in_mail.read()
envelope = in_envelope.read()
except IOError:
## report "Unable to read the message or envelope." (see 'man qmail-queue')
sys.exit(54)
## see 'man qmail-queue' for details of the envelope format
envelope_addresses = re.match(u'F(.+?)\0((?:T[^\0]+?\0)+)\0$', envelope)
if not envelope_addresses or (len(envelope_addresses.groups()) != 2):
## report "Envelope format error." (see 'man qmail-queue')
sys.exit(91)
## the first match is the sender address
envelope_sender = envelope_addresses.groups()[0]
## the second match is the list of all recipients
## each preceded by "T" and followed by "\0"
envelope_recipients = envelope_addresses.groups()[1].split("\0")
## remove leading "T" and skip empty values
envelope_recipients = [ e[1:] for e in envelope_recipients if e ]
for recipient in envelope_recipients:
handler.process_mail(envelope_sender, recipient, mail_text)
def check_for_errors():
errors = False
## check the original qmail-queue binary
if not os.access(QMAILQUEUE_BIN, os.X_OK):
sys.stderr.write("Could not find executable qmail-queue: %s\n" % QMAILQUEUE_BIN)
errors = True
## check the existence of the pyme module
try:
import pyme
except ImportError:
sys.stderr.write("Failed to import python-pyme!\n")
errors = True
## check if the subprocess module is available (python >= 2.4)
try:
import subprocess
except ImportError:
sys.stderr.write("Failed to import the python module 'subprocess'! It requires python2.4.\n")
errors = True
return errors == False
if __name__ == '__main__':
# reduce priority
os.nice(5)
if not check_for_errors():
internal_error()
if len(sys.argv) == 1:
## we were only supposed to run the self-tests - exiting successfully
sys.exit(0)
## we expect exactly one parameter - the mailinglist directory
if len(sys.argv) != 2:
internal_error("More than one parameter (the mailinglist directory) given!")
## print some help if it was requested
if sys.argv[0] == '--help':
sys.stderr.write("Syntax: %s [MAILINGLIST_DIRECTORY]\n\n" % \
os.path.basename(sys.argv[0]))
sys.stderr.write("If you omit the MAILINGLIST_DIRECTORY, " \
+ "then only some self-tests are done.\n\n")
sys.exit(0)
## retrieve the mailing list directory by reading the dotqmail file
list_dir = sys.argv[1]
## does the mailinglist directory exist?
if not os.access(list_dir, os.X_OK):
internal_error("Could not access the mailinglist directory: %s" % list_dir)
## reencrypt the mail for each recipient
mail_handler = MailEncryption(list_dir)
process_input_and_output(mail_handler)

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#!/usr/bin/env python
#
# This file is part of lispet - an encryption filter for the different
# mailinglist manager.
#
# Copyright 02007-2008 Sense.Lab e.V. <info@senselab.org>
#
# lispet 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.
#
# lispet 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 the CryptoBox; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#
# TODO:
# implement 'sign_messages'
# implement 'hide_subject'
import sys
import os
import email
# the following modules are imported later
#import pyme
#import subprocess
## try to import the pyme module
try:
import pyme
except ImportError:
sys.stderr.write("Failed to import python-pyme!\n")
sys.exit(1)
## check if the subprocess module is available (python >= 2.4)
try:
import subprocess
except ImportError:
sys.stderr.write("Failed to import the python module 'subprocess'! "
. "It requires python2.4 or higher.\n")
sys.exit(1)
#################### some strings ######################
## put this warning into a mail instead of the encrypted content, in case
## the key of the recipient is missing
NOKEY_WARNING = "No valid encryption key found!"
## in case of 'cannot decrypt' errors
DECRYPT_ERROR = "Failed to decrypt the mail that was sent to the mailinglist. Please check the configuration of the mailinglist. Maybe the sender used an invalid encryption key?"
################ the encryption handler ################
class MailEncryption:
def __init__(self, list_dir):
self.list_dir = os.path.abspath(list_dir)
## does the list directory exist?
if not os.access(self.list_dir, os.X_OK):
internal_error("Could not access mailinglist directory: %s" \
% self.list_dir)
## read the config file
self.config = self.read_config()
## does the gnupg directory exist?
if not os.access(self.config["gnupg_dir"], os.X_OK):
internal_error("Could not access gnupg directory: %s" \
% self.config["gnupg_dir"])
## set GPGHOME environment - this should be used by pyme
os.environ["GNUPGHOME"] = self.config["gnupg_dir"]
## we _must_ import pyme after configuring the GNUPGHOME setting
import pyme.core
self.pyme = pyme
self.context = self.pyme.core.Context()
self.context.set_armor(1)
def get_valid_keys(self, pattern=""):
for key in self.context.op_keylist_all(pattern, 0):
if key.can_encrypt != 0:
yield key
def encrypt_to_keys(self, plain, keylist):
plaindata = self.pyme.core.Data(plain)
cipher = self.pyme.core.Data(plain)
self.context.op_encrypt(keylist, 1, plaindata, cipher)
cipher.seek(0, 0)
return cipher.read()
def reencrypt_mail(self, mail, keys):
if mail.is_multipart():
payloads = mail.get_payload()
index = 0
while index < len(payloads):
if self.is_encrypted(payloads[index].get_payload()):
decrypted_part = email.message_from_string(
self.decrypt_block(payloads[index].get_payload()))
if keys:
payloads[index].set_payload(self.encrypt_to_keys(
decrypted_part.as_string(), keys))
else:
if self.config["plain_without_key"]:
payloads[index].set_payload(decrypted_part.as_string())
else:
payloads[index].set_payload(NOKEY_WARNING)
index += 1
else:
if self.is_encrypted(mail.get_payload()):
if keys:
mail.set_payload(self.encrypt_to_keys(
self.decrypt_block(mail.get_payload()), keys))
else:
if self.config["plain_without_key"]:
mail.set_payload(self.decrypt_block(mail.get_payload()))
else:
mail.set_payload(NOKEY_WARNING)
def is_encrypted(self, text):
# TODO: check for base64 encoded mails!
return text.find("-----BEGIN PGP MESSAGE-----") != -1
def decrypt_block(self, text):
cipher = self.pyme.core.Data(text)
plain = self.pyme.core.Data()
try:
self.context.op_decrypt(cipher, plain)
except self.pyme.errors.GPGMEError:
## decryption failed - we do not do anything
plain = self.pyme.core.Data(DECRYPT_ERROR)
plain.seek(0, 0)
# this function should write to a stream
return plain.read()
def process_mail(self, sender, recipient, mail_text):
"""Decrypt the mail and encrypt it again for the specified recipient
"""
mail = email.message_from_string(mail_text)
keys = self.get_valid_keys(recipient)
## reencrypt the whole mail for the specific recipient
self.reencrypt_mail(mail, keys)
## use tmpfile as input for qmail-queue
## we have to complicate things a little bit, as qmail-queue expects input
## at file handle 1 - this is usually stdout
tmpfile = os.tmpfile()
tmpfile.write('F%s\0T%s\0\0' % (sender, recipient))
tmpfile.seek(0)
## execute the original qmail-queue
proc = subprocess.Popen(
shell = False,
stdin = subprocess.PIPE,
stdout = tmpfile.fileno(),
env = os.environ,
args = [ QMAILQUEUE_BIN ] )
proc.stdin.write(mail.as_string())
## tmpfile is deleted automatically after closing
tmpfile.close()
proc.stdin.close()
proc.wait()
## exit immediately, if qmail-queue failed once
if proc.returncode != 0:
sys.exit(proc.returncode)