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Diffstat (limited to 'src/leap/bitmask/mail/outgoing/service.py')
| -rw-r--r-- | src/leap/bitmask/mail/outgoing/service.py | 518 |
1 files changed, 518 insertions, 0 deletions
diff --git a/src/leap/bitmask/mail/outgoing/service.py b/src/leap/bitmask/mail/outgoing/service.py new file mode 100644 index 0000000..8b02f2e --- /dev/null +++ b/src/leap/bitmask/mail/outgoing/service.py @@ -0,0 +1,518 @@ +# -*- coding: utf-8 -*- +# outgoing/service.py +# Copyright (C) 2013-2015 LEAP +# +# 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 3 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, see <http://www.gnu.org/licenses/>. + +""" +OutgoingMail module. + +The OutgoingMail class allows to send mail, and encrypts/signs it if needed. +""" + +import os.path +import re +from StringIO import StringIO +from copy import deepcopy +from email.parser import Parser +from email.mime.application import MIMEApplication +from email.mime.multipart import MIMEMultipart +from email.mime.text import MIMEText + +from OpenSSL import SSL + +from twisted.mail import smtp +from twisted.internet import reactor +from twisted.internet import defer +from twisted.protocols.amp import ssl +from twisted.python import log + +from leap.common.check import leap_assert_type, leap_assert +from leap.common.events import emit_async, catalog +from leap.keymanager.errors import KeyNotFound, KeyAddressMismatch +from leap.mail import __version__ +from leap.mail import errors +from leap.mail.utils import validate_address +from leap.mail.rfc3156 import MultipartEncrypted +from leap.mail.rfc3156 import MultipartSigned +from leap.mail.rfc3156 import encode_base64_rec +from leap.mail.rfc3156 import RFC3156CompliantGenerator +from leap.mail.rfc3156 import PGPSignature +from leap.mail.rfc3156 import PGPEncrypted + +# TODO +# [ ] rename this module to something else, service should be the implementor +# of IService + + +class SSLContextFactory(ssl.ClientContextFactory): + def __init__(self, cert, key): + self.cert = cert + self.key = key + + def getContext(self): + # FIXME -- we should use sslv23 to allow for tlsv1.2 + # and, if possible, explicitely disable sslv3 clientside. + # Servers should avoid sslv3 + self.method = SSL.TLSv1_METHOD # SSLv23_METHOD + ctx = ssl.ClientContextFactory.getContext(self) + ctx.use_certificate_file(self.cert) + ctx.use_privatekey_file(self.key) + return ctx + + +def outgoingFactory(userid, keymanager, opts, check_cert=True, bouncer=None): + + cert = unicode(opts.cert) + key = unicode(opts.key) + hostname = str(opts.hostname) + port = opts.port + + if check_cert: + if not os.path.isfile(cert): + raise errors.ConfigurationError( + 'No valid SMTP certificate could be found for %s!' % userid) + + return OutgoingMail( + str(userid), keymanager, cert, key, hostname, port, + bouncer) + + +class OutgoingMail(object): + """ + Sends Outgoing Mail, encrypting and signing if needed. + """ + + def __init__(self, from_address, keymanager, cert, key, host, port, + bouncer=None): + """ + Initialize the outgoing mail service. + + :param from_address: The sender address. + :type from_address: str + :param keymanager: A KeyManager for retrieving recipient's keys. + :type keymanager: leap.common.keymanager.KeyManager + :param cert: The client certificate for SSL authentication. + :type cert: str + :param key: The client private key for SSL authentication. + :type key: str + :param host: The hostname of the remote SMTP server. + :type host: str + :param port: The port of the remote SMTP server. + :type port: int + """ + + # assert params + leap_assert_type(from_address, str) + leap_assert('@' in from_address) + + # XXX it can be a zope.proxy too + # leap_assert_type(keymanager, KeyManager) + + leap_assert_type(host, str) + leap_assert(host != '') + leap_assert_type(port, int) + leap_assert(port is not 0) + leap_assert_type(cert, unicode) + leap_assert(cert != '') + leap_assert_type(key, unicode) + leap_assert(key != '') + + self._port = port + self._host = host + self._key = key + self._cert = cert + self._from_address = from_address + self._keymanager = keymanager + self._bouncer = bouncer + + def send_message(self, raw, recipient): + """ + Sends a message to a recipient. Maybe encrypts and signs. + + :param raw: The raw message + :type raw: str + :param recipient: The recipient for the message + :type recipient: smtp.User + :return: a deferred which delivers the message when fired + """ + d = self._maybe_encrypt_and_sign(raw, recipient) + d.addCallback(self._route_msg, raw) + d.addErrback(self.sendError, raw) + return d + + def sendSuccess(self, smtp_sender_result): + """ + Callback for a successful send. + + :param smtp_sender_result: The result from the ESMTPSender from + _route_msg + :type smtp_sender_result: tuple(int, list(tuple)) + """ + dest_addrstr = smtp_sender_result[1][0][0] + fromaddr = self._from_address + log.msg('Message sent from %s to %s' % (fromaddr, dest_addrstr)) + emit_async(catalog.SMTP_SEND_MESSAGE_SUCCESS, + fromaddr, dest_addrstr) + + def sendError(self, failure, origmsg): + """ + Callback for an unsuccessfull send. + + :param failure: The result from the last errback. + :type failure: anything + :param origmsg: the original, unencrypted, raw message, to be passed to + the bouncer. + :type origmsg: str + """ + # XXX: need to get the address from the original message to send signal + # emit_async(catalog.SMTP_SEND_MESSAGE_ERROR, self._from_address, + # self._user.dest.addrstr) + + # TODO when we implement outgoing queues/long-term-retries, we could + # examine the error *here* and delay the notification if it's just a + # temporal error. We might want to notify the permanent errors + # differently. + + err = failure.value + log.err(err) + + if self._bouncer: + self._bouncer.bounce_message( + err.message, to=self._from_address, + orig=origmsg) + else: + raise err + + def _route_msg(self, encrypt_and_sign_result, raw): + """ + Sends the msg using the ESMTPSenderFactory. + + :param encrypt_and_sign_result: A tuple containing the 'maybe' + encrypted message and the recipient + :type encrypt_and_sign_result: tuple + """ + message, recipient = encrypt_and_sign_result + log.msg("Connecting to SMTP server %s:%s" % (self._host, self._port)) + msg = message.as_string(False) + + # we construct a defer to pass to the ESMTPSenderFactory + d = defer.Deferred() + d.addCallback(self.sendSuccess) + d.addErrback(self.sendError, raw) + # we don't pass an ssl context factory to the ESMTPSenderFactory + # because ssl will be handled by reactor.connectSSL() below. + factory = smtp.ESMTPSenderFactory( + "", # username is blank, no client auth here + "", # password is blank, no client auth here + self._from_address, + recipient.dest.addrstr, + StringIO(msg), + d, + heloFallback=True, + requireAuthentication=False, + requireTransportSecurity=True) + factory.domain = bytes('leap.mail-' + __version__) + emit_async(catalog.SMTP_SEND_MESSAGE_START, + self._from_address, recipient.dest.addrstr) + reactor.connectSSL( + self._host, self._port, factory, + contextFactory=SSLContextFactory(self._cert, self._key)) + + def _maybe_encrypt_and_sign(self, raw, recipient, fetch_remote=True): + """ + Attempt to encrypt and sign the outgoing message. + + The behaviour of this method depends on: + + 1. the original message's content-type, and + 2. the availability of the recipient's public key. + + If the original message's content-type is "multipart/encrypted", then + the original message is not altered. For any other content-type, the + method attempts to fetch the recipient's public key. If the + recipient's public key is available, the message is encrypted and + signed; otherwise it is only signed. + + Note that, if the C{encrypted_only} configuration is set to True and + the recipient's public key is not available, then the recipient + address would have been rejected in SMTPDelivery.validateTo(). + + The following table summarizes the overall behaviour of the gateway: + + +---------------------------------------------------+----------------+ + | content-type | rcpt pubkey | enforce encr. | action | + +---------------------+-------------+---------------+----------------+ + | multipart/encrypted | any | any | pass | + | other | available | any | encrypt + sign | + | other | unavailable | yes | reject | + | other | unavailable | no | sign | + +---------------------+-------------+---------------+----------------+ + + :param raw: The raw message + :type raw: str + :param recipient: The recipient for the message + :type: recipient: smtp.User + + :return: A Deferred that will be fired with a MIMEMultipart message + and the original recipient Message + :rtype: Deferred + """ + # pass if the original message's content-type is "multipart/encrypted" + origmsg = Parser().parsestr(raw) + + if origmsg.get_content_type() == 'multipart/encrypted': + return defer.succeed((origmsg, recipient)) + + from_address = validate_address(self._from_address) + username, domain = from_address.split('@') + to_address = validate_address(recipient.dest.addrstr) + + def maybe_encrypt_and_sign(message): + d = self._encrypt_and_sign( + message, to_address, from_address, + fetch_remote=fetch_remote) + d.addCallbacks(signal_encrypt_sign, + if_key_not_found_send_unencrypted, + errbackArgs=(message,)) + return d + + def signal_encrypt_sign(newmsg): + emit_async(catalog.SMTP_END_ENCRYPT_AND_SIGN, + self._from_address, + "%s,%s" % (self._from_address, to_address)) + return newmsg, recipient + + def if_key_not_found_send_unencrypted(failure, message): + failure.trap(KeyNotFound, KeyAddressMismatch) + + log.msg('Will send unencrypted message to %s.' % to_address) + emit_async(catalog.SMTP_START_SIGN, self._from_address, to_address) + d = self._sign(message, from_address) + d.addCallback(signal_sign) + return d + + def signal_sign(newmsg): + emit_async(catalog.SMTP_END_SIGN, self._from_address) + return newmsg, recipient + + log.msg("Will encrypt the message with %s and sign with %s." + % (to_address, from_address)) + emit_async(catalog.SMTP_START_ENCRYPT_AND_SIGN, + self._from_address, + "%s,%s" % (self._from_address, to_address)) + d = self._maybe_attach_key(origmsg, from_address, to_address) + d.addCallback(maybe_encrypt_and_sign) + return d + + def _maybe_attach_key(self, origmsg, from_address, to_address): + filename = "%s-email-key.asc" % (from_address,) + + def attach_if_address_hasnt_encrypted(to_key): + # if the sign_used flag is true that means that we got an encrypted + # email from this address, because we conly check signatures on + # encrypted emails. In this case we don't attach. + # XXX: this might not be true some time in the future + if to_key.sign_used: + return origmsg + return get_key_and_attach(None) + + def get_key_and_attach(_): + d = self._keymanager.get_key(from_address, fetch_remote=False) + d.addCallback(attach_key) + return d + + def attach_key(from_key): + msg = origmsg + if not origmsg.is_multipart(): + msg = MIMEMultipart() + for h, v in origmsg.items(): + msg.add_header(h, v) + msg.attach(MIMEText(origmsg.get_payload())) + + keymsg = MIMEApplication(from_key.key_data, _subtype='pgp-keys', + _encoder=lambda x: x) + keymsg.add_header('content-disposition', 'attachment', + filename=filename) + msg.attach(keymsg) + return msg + + d = self._keymanager.get_key(to_address, fetch_remote=False) + d.addCallbacks(attach_if_address_hasnt_encrypted, get_key_and_attach) + d.addErrback(lambda _: origmsg) + return d + + def _encrypt_and_sign(self, origmsg, encrypt_address, sign_address, + fetch_remote=True): + """ + Create an RFC 3156 compliang PGP encrypted and signed message using + C{encrypt_address} to encrypt and C{sign_address} to sign. + + :param origmsg: The original message + :type origmsg: email.message.Message + :param encrypt_address: The address used to encrypt the message. + :type encrypt_address: str + :param sign_address: The address used to sign the message. + :type sign_address: str + + :return: A Deferred with the MultipartEncrypted message + :rtype: Deferred + """ + # create new multipart/encrypted message with 'pgp-encrypted' protocol + + def encrypt(res): + newmsg, origmsg = res + d = self._keymanager.encrypt( + origmsg.as_string(unixfrom=False), + encrypt_address, sign=sign_address, + fetch_remote=fetch_remote) + d.addCallback(lambda encstr: (newmsg, encstr)) + return d + + def create_encrypted_message(res): + newmsg, encstr = res + encmsg = MIMEApplication( + encstr, _subtype='octet-stream', _encoder=lambda x: x) + encmsg.add_header('content-disposition', 'attachment', + filename='msg.asc') + # create meta message + metamsg = PGPEncrypted() + metamsg.add_header('Content-Disposition', 'attachment') + # attach pgp message parts to new message + newmsg.attach(metamsg) + newmsg.attach(encmsg) + return newmsg + + d = self._fix_headers( + origmsg, + MultipartEncrypted('application/pgp-encrypted'), + sign_address) + d.addCallback(encrypt) + d.addCallback(create_encrypted_message) + return d + + def _sign(self, origmsg, sign_address): + """ + Create an RFC 3156 compliant PGP signed MIME message using + C{sign_address}. + + :param origmsg: The original message + :type origmsg: email.message.Message + :param sign_address: The address used to sign the message. + :type sign_address: str + + :return: A Deferred with the MultipartSigned message. + :rtype: Deferred + """ + # apply base64 content-transfer-encoding + encode_base64_rec(origmsg) + # get message text with headers and replace \n for \r\n + fp = StringIO() + g = RFC3156CompliantGenerator( + fp, mangle_from_=False, maxheaderlen=76) + g.flatten(origmsg) + msgtext = re.sub('\r?\n', '\r\n', fp.getvalue()) + # make sure signed message ends with \r\n as per OpenPGP stantard. + if origmsg.is_multipart(): + if not msgtext.endswith("\r\n"): + msgtext += "\r\n" + + def create_signed_message(res): + (msg, _), signature = res + sigmsg = PGPSignature(signature) + # attach original message and signature to new message + msg.attach(origmsg) + msg.attach(sigmsg) + return msg + + dh = self._fix_headers( + origmsg, + MultipartSigned('application/pgp-signature', 'pgp-sha512'), + sign_address) + ds = self._keymanager.sign( + msgtext, sign_address, digest_algo='SHA512', + clearsign=False, detach=True, binary=False) + d = defer.gatherResults([dh, ds]) + d.addCallback(create_signed_message) + return d + + def _fix_headers(self, msg, newmsg, sign_address): + """ + Move some headers from C{origmsg} to C{newmsg}, delete unwanted + headers from C{origmsg} and add new headers to C{newms}. + + Outgoing messages are either encrypted and signed or just signed + before being sent. Because of that, they are packed inside new + messages and some manipulation has to be made on their headers. + + Allowed headers for passing through: + + - From + - Date + - To + - Subject + - Reply-To + - References + - In-Reply-To + - Cc + + Headers to be added: + + - Message-ID (i.e. should not use origmsg's Message-Id) + - Received (this is added automatically by twisted smtp API) + - OpenPGP (see #4447) + + Headers to be deleted: + + - User-Agent + + :param msg: The original message. + :type msg: email.message.Message + :param newmsg: The new message being created. + :type newmsg: email.message.Message + :param sign_address: The address used to sign C{newmsg} + :type sign_address: str + + :return: A Deferred with a touple: + (new Message with the unencrypted headers, + original Message with headers removed) + :rtype: Deferred + """ + origmsg = deepcopy(msg) + # move headers from origmsg to newmsg + headers = origmsg.items() + passthrough = [ + 'from', 'date', 'to', 'subject', 'reply-to', 'references', + 'in-reply-to', 'cc' + ] + headers = filter(lambda x: x[0].lower() in passthrough, headers) + for hkey, hval in headers: + newmsg.add_header(hkey, hval) + del (origmsg[hkey]) + # add a new message-id to newmsg + newmsg.add_header('Message-Id', smtp.messageid()) + # delete user-agent from origmsg + del (origmsg['user-agent']) + + def add_openpgp_header(signkey): + username, domain = sign_address.split('@') + newmsg.add_header( + 'OpenPGP', 'id=%s' % signkey.fingerprint, + url='https://%s/key/%s' % (domain, username), + preference='signencrypt') + return newmsg, origmsg + + d = self._keymanager.get_key(sign_address, private=True) + d.addCallback(add_openpgp_header) + return d |