[pkg] move mail source to leap.bitmask.mail

1 files changed, 413 insertions, 0 deletions

diff --git a/src/leap/bitmask/mail/smtp/gateway.py b/src/leap/bitmask/mail/smtp/gateway.py
new file mode 100644
index 0000000..e49bbe8
--- /dev/null
+++ b/src/leap/bitmask/mail/smtp/gateway.py
@@ -0,0 +1,413 @@
+# -*- coding: utf-8 -*-
+# gateway.py
+# Copyright (C) 2013 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/>.
+"""
+LEAP SMTP encrypted gateway.
+
+The following classes comprise the SMTP gateway service:
+
+    * SMTPFactory - A twisted.internet.protocol.ServerFactory that provides
+      the SMTPDelivery protocol.
+
+    * SMTPDelivery - A twisted.mail.smtp.IMessageDelivery implementation. It
+      knows how to validate sender and receiver of messages and it generates
+      an EncryptedMessage for each recipient.
+
+    * EncryptedMessage - An implementation of twisted.mail.smtp.IMessage that
+      knows how to encrypt/sign itself before sending.
+"""
+from email.Header import Header
+
+from zope.interface import implements
+from zope.interface import implementer
+
+from twisted.cred.portal import Portal, IRealm
+from twisted.mail import smtp
+from twisted.mail.imap4 import LOGINCredentials, PLAINCredentials
+from twisted.internet import defer, protocol
+from twisted.python import log
+
+from leap.common.check import leap_assert_type
+from leap.common.events import emit_async, catalog
+from leap.mail import errors
+from leap.mail.cred import LocalSoledadTokenChecker
+from leap.mail.utils import validate_address
+from leap.mail.rfc3156 import RFC3156CompliantGenerator
+from leap.mail.outgoing.service import outgoingFactory
+from leap.mail.smtp.bounces import bouncerFactory
+from leap.keymanager.errors import KeyNotFound
+
+# replace email generator with a RFC 3156 compliant one.
+from email import generator
+
+generator.Generator = RFC3156CompliantGenerator
+
+
+LOCAL_FQDN = "bitmask.local"
+
+
+@implementer(IRealm)
+class LocalSMTPRealm(object):
+
+    _encoding = 'utf-8'
+
+    def __init__(self, keymanager_sessions, soledad_sessions, sendmail_opts,
+                 encrypted_only=False):
+        """
+        :param keymanager_sessions: a dict-like object, containing instances
+                                 of a Keymanager objects, indexed by
+                                 userid.
+        """
+        self._keymanager_sessions = keymanager_sessions
+        self._soledad_sessions = soledad_sessions
+        self._sendmail_opts = sendmail_opts
+        self.encrypted_only = encrypted_only
+
+    def requestAvatar(self, avatarId, mind, *interfaces):
+
+        if isinstance(avatarId, str):
+            avatarId = avatarId.decode(self._encoding)
+
+        def gotKeymanagerAndSoledad(result):
+            keymanager, soledad = result
+            d = bouncerFactory(soledad)
+            d.addCallback(lambda bouncer: (keymanager, soledad, bouncer))
+            return d
+
+        def getMessageDelivery(result):
+            keymanager, soledad, bouncer = result
+            # TODO use IMessageDeliveryFactory instead ?
+            # it could reuse the connections.
+            if smtp.IMessageDelivery in interfaces:
+                userid = avatarId
+                opts = self.getSendingOpts(userid)
+
+                outgoing = outgoingFactory(
+                    userid, keymanager, opts, bouncer=bouncer)
+                avatar = SMTPDelivery(userid, keymanager, self.encrypted_only,
+                                      outgoing)
+
+                return (smtp.IMessageDelivery, avatar,
+                        getattr(avatar, 'logout', lambda: None))
+
+            raise NotImplementedError(self, interfaces)
+
+        d1 = self.lookupKeymanagerInstance(avatarId)
+        d2 = self.lookupSoledadInstance(avatarId)
+        d = defer.gatherResults([d1, d2])
+        d.addCallback(gotKeymanagerAndSoledad)
+        d.addCallback(getMessageDelivery)
+        return d
+
+    def lookupKeymanagerInstance(self, userid):
+        try:
+            keymanager = self._keymanager_sessions[userid]
+        except:
+            raise errors.AuthenticationError(
+                'No keymanager session found for user %s. Is it authenticated?'
+                % userid)
+        # XXX this should return the instance after whenReady callback
+        return defer.succeed(keymanager)
+
+    def lookupSoledadInstance(self, userid):
+        try:
+            soledad = self._soledad_sessions[userid]
+        except:
+            raise errors.AuthenticationError(
+                'No soledad session found for user %s. Is it authenticated?'
+                % userid)
+        # XXX this should return the instance after whenReady callback
+        return defer.succeed(soledad)
+
+    def getSendingOpts(self, userid):
+        try:
+            opts = self._sendmail_opts[userid]
+        except KeyError:
+            raise errors.ConfigurationError(
+                'No sendingMail options found for user %s' % userid)
+        return opts
+
+
+class SMTPTokenChecker(LocalSoledadTokenChecker):
+    """A credentials checker that will lookup a token for the SMTP service.
+    For now it will be using the same identifier than IMAPTokenChecker"""
+
+    service = 'mail_auth'
+
+    # TODO besides checking for token credential,
+    # we could also verify the certificate here.
+
+
+class LEAPInitMixin(object):
+
+    """
+    A Mixin that takes care of initialization of all the data needed to access
+    LEAP sessions.
+    """
+    def __init__(self, soledad_sessions, keymanager_sessions, sendmail_opts,
+                 encrypted_only=False):
+        realm = LocalSMTPRealm(
+            keymanager_sessions, soledad_sessions, sendmail_opts,
+            encrypted_only)
+        portal = Portal(realm)
+
+        checker = SMTPTokenChecker(soledad_sessions)
+        self.checker = checker
+        self.portal = portal
+        portal.registerChecker(checker)
+
+
+class LocalSMTPServer(smtp.ESMTP, LEAPInitMixin):
+    """
+    The Production ESMTP Server: Authentication Needed.
+    Authenticates against SMTP Token stored in Local Soledad instance.
+    The Realm will produce a Delivery Object that handles encryption/signing.
+    """
+
+    # TODO: implement Queue using twisted.mail.mail.MailService
+
+    def __init__(self, soledads, keyms, sendmailopts, *args, **kw):
+        encrypted_only = kw.pop('encrypted_only', False)
+
+        LEAPInitMixin.__init__(self, soledads, keyms, sendmailopts,
+                               encrypted_only)
+        smtp.ESMTP.__init__(self, *args, **kw)
+
+
+# TODO implement retries -- see smtp.SenderMixin
+class SMTPFactory(protocol.ServerFactory):
+    """
+    Factory for an SMTP server with encrypted gatewaying capabilities.
+    """
+
+    protocol = LocalSMTPServer
+    domain = LOCAL_FQDN
+    timeout = 600
+    encrypted_only = False
+
+    def __init__(self, soledad_sessions, keymanager_sessions, sendmail_opts,
+                 deferred=None, retries=3):
+
+        self._soledad_sessions = soledad_sessions
+        self._keymanager_sessions = keymanager_sessions
+        self._sendmail_opts = sendmail_opts
+
+    def buildProtocol(self, addr):
+        p = self.protocol(
+            self._soledad_sessions, self._keymanager_sessions,
+            self._sendmail_opts, encrypted_only=self.encrypted_only)
+        p.factory = self
+        p.host = LOCAL_FQDN
+        p.challengers = {"LOGIN": LOGINCredentials, "PLAIN": PLAINCredentials}
+        return p
+
+
+#
+# SMTPDelivery
+#
+
+@implementer(smtp.IMessageDelivery)
+class SMTPDelivery(object):
+    """
+    Validate email addresses and handle message delivery.
+    """
+
+    def __init__(self, userid, keymanager, encrypted_only, outgoing_mail):
+        """
+        Initialize the SMTP delivery object.
+
+        :param userid: The user currently logged in
+        :type userid: unicode
+        :param keymanager: A Key Manager from where to get recipients' public
+                           keys.
+        :param encrypted_only: Whether the SMTP gateway should send unencrypted
+                               mail or not.
+        :type encrypted_only: bool
+        :param outgoing_mail: The outgoing mail to send the message
+        :type outgoing_mail: leap.mail.outgoing.service.OutgoingMail
+        """
+        self._userid = userid
+        self._outgoing_mail = outgoing_mail
+        self._km = keymanager
+        self._encrypted_only = encrypted_only
+        self._origin = None
+
+    def receivedHeader(self, helo, origin, recipients):
+        """
+        Generate the 'Received:' header for a message.
+
+        :param helo: The argument to the HELO command and the client's IP
+            address.
+        :type helo: (str, str)
+        :param origin: The address the message is from.
+        :type origin: twisted.mail.smtp.Address
+        :param recipients: A list of the addresses for which this message is
+            bound.
+        :type: list of twisted.mail.smtp.User
+
+        @return: The full "Received" header string.
+        :type: str
+        """
+        myHostname, clientIP = helo
+        headerValue = "by bitmask.local from %s with ESMTP ; %s" % (
+            clientIP, smtp.rfc822date())
+        # email.Header.Header used for automatic wrapping of long lines
+        return "Received: %s" % Header(s=headerValue, header_name='Received')
+
+    def validateTo(self, user):
+        """
+        Validate the address of a recipient of the message, possibly
+        rejecting it if the recipient key is not available.
+
+        This method is called once for each recipient, i.e. for each SMTP
+        protocol line beginning with "RCPT TO:", which includes all addresses
+        in "To", "Cc" and "Bcc" MUA fields.
+
+        The recipient's address is validated against the RFC 2822 definition.
+        If self._encrypted_only is True and no key is found for a recipient,
+        then that recipient is rejected.
+
+        The method returns an encrypted message object that is able to send
+        itself to the user's address.
+
+        :param user: The user whose address we wish to validate.
+        :type: twisted.mail.smtp.User
+
+        @return: A callable which takes no arguments and returns an
+                 encryptedMessage.
+        @rtype: no-argument callable
+
+        @raise SMTPBadRcpt: Raised if messages to the address are not to be
+                            accepted.
+        """
+        # try to find recipient's public key
+        address = validate_address(user.dest.addrstr)
+
+        # verify if recipient key is available in keyring
+        def found(_):
+            log.msg("Accepting mail for %s..." % user.dest.addrstr)
+            emit_async(catalog.SMTP_RECIPIENT_ACCEPTED_ENCRYPTED,
+                       self._userid, user.dest.addrstr)
+
+        def not_found(failure):
+            failure.trap(KeyNotFound)
+
+            # if key was not found, check config to see if will send anyway
+            if self._encrypted_only:
+                emit_async(catalog.SMTP_RECIPIENT_REJECTED, self._userid,
+                           user.dest.addrstr)
+                raise smtp.SMTPBadRcpt(user.dest.addrstr)
+            log.msg("Warning: will send an unencrypted message (because "
+                    "encrypted_only' is set to False).")
+            emit_async(
+                catalog.SMTP_RECIPIENT_ACCEPTED_UNENCRYPTED,
+                self._userid, user.dest.addrstr)
+
+        def encrypt_func(_):
+            return lambda: EncryptedMessage(user, self._outgoing_mail)
+
+        d = self._km.get_key(address)
+        d.addCallbacks(found, not_found)
+        d.addCallback(encrypt_func)
+        return d
+
+    def validateFrom(self, helo, origin):
+        """
+        Validate the address from which the message originates.
+
+        :param helo: The argument to the HELO command and the client's IP
+            address.
+        :type: (str, str)
+        :param origin: The address the message is from.
+        :type origin: twisted.mail.smtp.Address
+
+        @return: origin or a Deferred whose callback will be passed origin.
+        @rtype: Deferred or Address
+
+        @raise twisted.mail.smtp.SMTPBadSender: Raised if messages from this
+            address are not to be accepted.
+        """
+        # accept mail from anywhere. To reject an address, raise
+        # smtp.SMTPBadSender here.
+        if str(origin) != str(self._userid):
+            log.msg("Rejecting sender {0}, expected {1}".format(origin,
+                                                                self._userid))
+            raise smtp.SMTPBadSender(origin)
+        self._origin = origin
+        return origin
+
+
+#
+# EncryptedMessage
+#
+
+class EncryptedMessage(object):
+    """
+    Receive plaintext from client, encrypt it and send message to a
+    recipient.
+    """
+    implements(smtp.IMessage)
+
+    def __init__(self, user, outgoing_mail):
+        """
+        Initialize the encrypted message.
+
+        :param user: The recipient of this message.
+        :type user: twisted.mail.smtp.User
+        :param outgoing_mail: The outgoing mail to send the message
+        :type outgoing_mail: leap.mail.outgoing.service.OutgoingMail
+        """
+        # assert params
+        leap_assert_type(user, smtp.User)
+
+        self._user = user
+        self._lines = []
+        self._outgoing_mail = outgoing_mail
+
+    def lineReceived(self, line):
+        """
+        Handle another line.
+
+        :param line: The received line.
+        :type line: str
+        """
+        self._lines.append(line)
+
+    def eomReceived(self):
+        """
+        Handle end of message.
+
+        This method will encrypt and send the message.
+
+        :returns: a deferred
+        """
+        log.msg("Message data complete.")
+        self._lines.append('')  # add a trailing newline
+        raw_mail = '\r\n'.join(self._lines)
+
+        return self._outgoing_mail.send_message(raw_mail, self._user)
+
+    def connectionLost(self):
+        """
+        Log an error when the connection is lost.
+        """
+        log.msg("Connection lost unexpectedly!")
+        log.err()
+        emit_async(catalog.SMTP_CONNECTION_LOST, self._userid,
+                   self._user.dest.addrstr)
+        # unexpected loss of connection; don't save
+
+        self._lines = []