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gpg-mailgate.py
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gpg-mailgate.py
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#!/usr/bin/python
#
# gpg-mailgate
#
# This file is part of the gpg-mailgate source code.
#
# gpg-mailgate 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.
#
# gpg-mailgate source code 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 gpg-mailgate source code. If not, see <http://www.gnu.org/licenses/>.
#
from ConfigParser import RawConfigParser
from email.mime.base import MIMEBase
import email
import email.message
import re
import GnuPG
import smtplib
import sys
import syslog
import traceback
import email.utils
import os
# imports for S/MIME
from M2Crypto import BIO, Rand, SMIME, X509
from email.mime.message import MIMEMessage
# Read configuration from /etc/gpg-mailgate.conf
_cfg = RawConfigParser()
_cfg.read('/etc/gpg-mailgate.conf')
cfg = dict()
for sect in _cfg.sections():
cfg[sect] = dict()
for (name, value) in _cfg.items(sect):
cfg[sect][name] = value
def log(msg):
if cfg.has_key('logging') and cfg['logging'].has_key('file'):
if cfg['logging']['file'] == "syslog":
syslog.syslog(syslog.LOG_INFO | syslog.LOG_MAIL, msg)
else:
logfile = open(cfg['logging']['file'], 'a')
logfile.write(msg + "\n")
logfile.close()
verbose=cfg.has_key('logging') and cfg['logging'].has_key('verbose') and cfg['logging']['verbose'] == 'yes'
CERT_PATH = cfg['smime']['cert_path']+"/"
# Read e-mail from stdin
raw = sys.stdin.read()
raw_message = email.message_from_string( raw )
from_addr = raw_message['From']
to_addrs = sys.argv[1:]
def send_msg( message, recipients = None ):
if recipients == None:
recipients = to_addrs
recipients = filter(None, recipients)
if recipients:
log("Sending email to: <%s>" % '> <'.join( recipients ))
relay = (cfg['relay']['host'], int(cfg['relay']['port']))
smtp = smtplib.SMTP(relay[0], relay[1])
smtp.sendmail( from_addr, recipients, message )
else:
log("No recipient found");
def encrypt_payload( payload, gpg_to_cmdline ):
raw_payload = payload.get_payload(decode=True)
if "-----BEGIN PGP MESSAGE-----" in raw_payload and "-----END PGP MESSAGE-----" in raw_payload:
return payload
gpg = GnuPG.GPGEncryptor( cfg['gpg']['keyhome'], gpg_to_cmdline, payload.get_content_charset() )
gpg.update( raw_payload )
payload.set_payload( gpg.encrypt() )
isAttachment = payload.get_param( 'attachment', None, 'Content-Disposition' ) is not None
if isAttachment:
filename = payload.get_filename()
if filename:
pgpFilename = filename + ".pgp"
if payload.get('Content-Disposition') is not None:
payload.set_param( 'filename', pgpFilename, 'Content-Disposition' )
if payload.get('Content-Type') is not None:
if payload.get_param( 'name' ) is not None:
payload.set_param( 'name', pgpFilename )
if payload.get('Content-Transfer-Encoding') is not None:
payload.replace_header( 'Content-Transfer-Encoding', "7bit" )
return payload
def encrypt_all_payloads( message, gpg_to_cmdline ):
encrypted_payloads = list()
if type( message.get_payload() ) == str:
return encrypt_payload( message, gpg_to_cmdline ).get_payload()
for payload in message.get_payload():
if( type( payload.get_payload() ) == list ):
encrypted_payloads.extend( encrypt_all_payloads( payload, gpg_to_cmdline ) )
else:
encrypted_payloads.append( encrypt_payload( payload, gpg_to_cmdline ) )
return encrypted_payloads
def get_msg( message ):
if not message.is_multipart():
return message.get_payload()
return '\n\n'.join( [str(m) for m in message.get_payload()] )
def get_cert_for_email(to_addr):
simple_path = os.path.join(CERT_PATH, to_addr)
if os.path.exists(simple_path): return (simple_path, to_addr)
# support [email protected] -> [email protected]
multi_email = re.match('^([^\+]+)\+([^@]+)@(.*)$', to_addr)
if multi_email:
fixed_up_email = "%s@%s"%(multi_email.group(1), multi_email.group(3))
log("Multi-email %s converted to %s"%(to_addr, fixed_up_email))
return get_cert_for_email(fixed_up_email)
return None
def to_smime_handler( raw_message, recipients = None ):
if recipients == None:
recipients = to_addrs
s = SMIME.SMIME()
sk = X509.X509_Stack()
normalized_recipient = []
for addr in recipients:
addr_addr = email.utils.parseaddr(addr)[1].lower()
cert_and_email = get_cert_for_email(addr_addr)
if cert_and_email:
(to_cert, normal_email) = cert_and_email
log("Found cert "+to_cert+" for "+addr+": "+normal_email)
normalized_recipient.append((email.utils.parseaddr(addr)[0], normal_email))
x509 = X509.load_cert(to_cert, format=X509.FORMAT_PEM)
sk.push(x509)
if len(normalized_recipient):
s.set_x509_stack(sk)
s.set_cipher(SMIME.Cipher('aes_192_cbc'))
p7 = s.encrypt( BIO.MemoryBuffer(raw_message.as_string()) )
# Output p7 in mail-friendly format.
out = BIO.MemoryBuffer()
out.write('From: '+from_addr+'\n')
to_list = ",".join([email.utils.formataddr(x) for x in normalized_recipient])
out.write('To: '+to_list+'\n')
if raw_message['Subject']:
out.write('Subject: '+raw_message['Subject']+'\n')
if cfg['default'].has_key('add_header') and cfg['default']['add_header'] == 'yes':
out.write('X-GPG-Mailgate: Encrypted by GPG Mailgate\n')
s.write(out, p7)
log("Sending message from "+from_addr+" to "+str(recipients))
raw_msg = out.read()
send_msg(raw_msg, recipients)
else:
log("Unable to find valid S/MIME recipient")
send_msg(raw_message.as_string(), recipients)
return None
keys = GnuPG.public_keys( cfg['gpg']['keyhome'] )
gpg_to = list()
ungpg_to = list()
for to in to_addrs:
if to in keys and not ( cfg['default'].has_key('keymap_only') and cfg['default']['keymap_only'] == 'yes' ):
gpg_to.append( (to, to) )
elif cfg.has_key('keymap') and cfg['keymap'].has_key(to):
gpg_to.append( (to, cfg['keymap'][to]) )
else:
if verbose:
log("Recipient (%s) not in PGP domain list." % to)
ungpg_to.append(to)
if gpg_to == list():
if cfg['default'].has_key('add_header') and cfg['default']['add_header'] == 'yes':
raw_message['X-GPG-Mailgate'] = 'Not encrypted, public key not found'
if verbose:
log("No PGP encrypted recipients.")
to_smime_handler( raw_message )
exit()
if ungpg_to != list():
to_smime_handler( raw_message, ungpg_to )
log("Encrypting email to: %s" % ' '.join( map(lambda x: x[0], gpg_to) ))
if cfg['default'].has_key('add_header') and cfg['default']['add_header'] == 'yes':
raw_message['X-GPG-Mailgate'] = 'Encrypted by GPG Mailgate'
gpg_to_cmdline = list()
gpg_to_smtp = list()
for rcpt in gpg_to:
gpg_to_smtp.append(rcpt[0])
gpg_to_cmdline.extend(rcpt[1].split(','))
encrypted_payloads = encrypt_all_payloads( raw_message, gpg_to_cmdline )
raw_message.set_payload( encrypted_payloads )
to_smime_handler( raw_message, gpg_to_smtp )