diff options
Diffstat (limited to 'src/leap/mail/smtp/smtprelay.py')
| -rw-r--r-- | src/leap/mail/smtp/smtprelay.py | 140 |
1 files changed, 99 insertions, 41 deletions
diff --git a/src/leap/mail/smtp/smtprelay.py b/src/leap/mail/smtp/smtprelay.py index 96eaa31..d9bbbf9 100644 --- a/src/leap/mail/smtp/smtprelay.py +++ b/src/leap/mail/smtp/smtprelay.py @@ -19,24 +19,38 @@ LEAP SMTP encrypted relay. """ -from zope.interface import implements +import re from StringIO import StringIO +from email.Header import Header +from email.utils import parseaddr +from email.parser import Parser +from email.mime.application import MIMEApplication + +from zope.interface import implements from OpenSSL import SSL from twisted.mail import smtp from twisted.internet.protocol import ServerFactory from twisted.internet import reactor, ssl from twisted.internet import defer from twisted.python import log -from email.Header import Header -from email.utils import parseaddr -from email.parser import Parser - from leap.common.check import leap_assert, leap_assert_type from leap.common.events import proto, signal from leap.keymanager import KeyManager from leap.keymanager.openpgp import OpenPGPKey from leap.keymanager.errors import KeyNotFound +from leap.mail.smtp.rfc3156 import ( + MultipartSigned, + MultipartEncrypted, + PGPEncrypted, + PGPSignature, + RFC3156CompliantGenerator, + encode_base64_rec, +) + +# replace email generator with a RFC 3156 compliant one. +from email import generator +generator.Generator = RFC3156CompliantGenerator # @@ -260,7 +274,8 @@ class SMTPDelivery(object): raise smtp.SMTPBadRcpt(user.dest.addrstr) log.msg("Warning: will send an unencrypted message (because " "encrypted_only' is set to False).") - signal(proto.SMTP_RECIPIENT_ACCEPTED_UNENCRYPTED, user.dest.addrstr) + signal( + proto.SMTP_RECIPIENT_ACCEPTED_UNENCRYPTED, user.dest.addrstr) return lambda: EncryptedMessage( self._origin, user, self._km, self._config) @@ -303,6 +318,16 @@ class CtxFactory(ssl.ClientContextFactory): return ctx +def move_headers(origmsg, newmsg): + headers = origmsg.items() + unwanted_headers = ['content-type', 'mime-version', 'content-disposition', + 'content-transfer-encoding'] + headers = filter(lambda x: x[0].lower() not in unwanted_headers, headers) + for hkey, hval in headers: + newmsg.add_header(hkey, hval) + del(origmsg[hkey]) + + class EncryptedMessage(object): """ Receive plaintext from client, encrypt it and send message to a @@ -343,6 +368,10 @@ class EncryptedMessage(object): # initialize list for message's lines self.lines = [] + # + # methods from smtp.IMessage + # + def lineReceived(self, line): """ Handle another line. @@ -360,9 +389,8 @@ class EncryptedMessage(object): """ log.msg("Message data complete.") self.lines.append('') # add a trailing newline - self.parseMessage() try: - self._encrypt_and_sign() + self._maybe_encrypt_and_sign() return self.sendMessage() except KeyNotFound: return None @@ -372,7 +400,7 @@ class EncryptedMessage(object): Separate message headers from body. """ parser = Parser() - self._message = parser.parsestr('\r\n'.join(self.lines)) + return parser.parsestr('\r\n'.join(self.lines)) def connectionLost(self): """ @@ -416,7 +444,7 @@ class EncryptedMessage(object): message send. @rtype: twisted.internet.defer.Deferred """ - msg = self._message.as_string(False) + msg = self._msg.as_string(False) log.msg("Connecting to SMTP server %s:%s" % (self._config[HOST_KEY], self._config[PORT_KEY])) @@ -442,46 +470,76 @@ class EncryptedMessage(object): d.addErrback(self.sendError) return d - def _encrypt_and_sign_payload_rec(self, message, pubkey, signkey): + # + # encryption methods + # + + def _encrypt_and_sign(self, pubkey, signkey): """ - Recursivelly descend in C{message}'s payload encrypting to C{pubkey} - and signing with C{signkey}. + Create an RFC 3156 compliang PGP encrypted and signed message using + C{pubkey} to encrypt and C{signkey} to sign. - @param message: The message whose payload we want to encrypt. - @type message: email.message.Message @param pubkey: The public key used to encrypt the message. @type pubkey: leap.common.keymanager.openpgp.OpenPGPKey @param signkey: The private key used to sign the message. @type signkey: leap.common.keymanager.openpgp.OpenPGPKey """ - if message.is_multipart() is False: - message.set_payload( - self._km.encrypt( - message.get_payload(), pubkey, sign=signkey)) - else: - for msg in message.get_payload(): - self._encrypt_and_sign_payload_rec(msg, pubkey, signkey) + # parse original message from received lines + origmsg = self.parseMessage() + # create new multipart/encrypted message with 'pgp-encrypted' protocol + newmsg = MultipartEncrypted('application/pgp-encrypted') + # move (almost) all headers from original message to the new message + move_headers(origmsg, newmsg) + # create 'application/octet-stream' encrypted message + encmsg = MIMEApplication( + self._km.encrypt(origmsg.as_string(unixfrom=False), pubkey, + sign=signkey), + _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) + self._msg = newmsg + + def _sign(self, signkey): + """ + Create an RFC 3156 compliant PGP signed MIME message using C{signkey}. - def _sign_payload_rec(self, message, signkey): - """ - Recursivelly descend in C{message}'s payload signing with C{signkey}. - - @param message: The message whose payload we want to encrypt. - @type message: email.message.Message - @param pubkey: The public key used to encrypt the message. - @type pubkey: leap.common.keymanager.openpgp.OpenPGPKey @param signkey: The private key used to sign the message. @type signkey: leap.common.keymanager.openpgp.OpenPGPKey """ - if message.is_multipart() is False: - message.set_payload( - self._km.sign( - message.get_payload(), signkey)) - else: - for msg in message.get_payload(): - self._sign_payload_rec(msg, signkey) - - def _encrypt_and_sign(self): + # parse original message from received lines + origmsg = self.parseMessage() + # create new multipart/signed message + newmsg = MultipartSigned('application/pgp-signature', 'pgp-sha512') + # move (almost) all headers from original message to the new message + move_headers(origmsg, newmsg) + # 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" + # calculate signature + signature = self._km.sign(msgtext, signkey, digest_algo='SHA512', + clearsign=False, detach=True, binary=False) + sigmsg = PGPSignature(signature) + # attach original message and signature to new message + newmsg.attach(origmsg) + newmsg.attach(sigmsg) + self._msg = newmsg + + def _maybe_encrypt_and_sign(self): """ Encrypt the message body. @@ -504,7 +562,7 @@ class EncryptedMessage(object): log.msg("Will encrypt the message to %s." % pubkey.fingerprint) signal(proto.SMTP_START_ENCRYPT_AND_SIGN, "%s,%s" % (self._fromAddress.addrstr, to_address)) - self._encrypt_and_sign_payload_rec(self._message, pubkey, signkey) + self._encrypt_and_sign(pubkey, signkey) signal(proto.SMTP_END_ENCRYPT_AND_SIGN, "%s,%s" % (self._fromAddress.addrstr, to_address)) except KeyNotFound: @@ -513,5 +571,5 @@ class EncryptedMessage(object): # rejected in SMTPDelivery.validateTo(). log.msg('Will send unencrypted message to %s.' % to_address) signal(proto.SMTP_START_SIGN, self._fromAddress.addrstr) - self._sign_payload_rec(self._message, signkey) + self._sign(signkey) signal(proto.SMTP_END_SIGN, self._fromAddress.addrstr) |