view sat/plugins/plugin_xep_0380.py @ 3153:2c7b42f53e9a

core (xmpp): avoid starting several clients at the same time: a check is done to avoid running startConnection several times at once, which would lead to the creation of several SatXMPPEntity instances at the same time, resulting in many issues. If startConnection is called while a previous one is not finished yet, a CancelError is now raised.
author Goffi <goffi@goffi.org>
date Mon, 03 Feb 2020 13:46:24 +0100
parents 559a625a236b
children dcebc585c29f
line wrap: on
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#!/usr/bin/env python3


# SAT plugin for Explicit Message Encryption
# Copyright (C) 2009-2020 Jérôme Poisson (goffi@goffi.org)

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero 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 Affero General Public License for more details.

# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

from sat.core.i18n import _, D_
from sat.core.constants import Const as C
from sat.core.log import getLogger
from twisted.words.protocols.jabber import jid

log = getLogger(__name__)

PLUGIN_INFO = {
    C.PI_NAME: "Explicit Message Encryption",
    C.PI_IMPORT_NAME: "XEP-0380",
    C.PI_TYPE: "SEC",
    C.PI_PROTOCOLS: ["XEP-0380"],
    C.PI_DEPENDENCIES: [],
    C.PI_MAIN: "XEP_0380",
    C.PI_HANDLER: "no",
    C.PI_DESCRIPTION: _("""Implementation of Explicit Message Encryption"""),
}

NS_EME = "urn:xmpp:eme:0"
KNOWN_NAMESPACES = {
    "urn:xmpp:otr:0": "OTR",
    "jabber:x:encrypted": "Legacy OpenPGP",
    "urn:xmpp:openpgp:0": "OpenPGP for XMPP",
}


class XEP_0380(object):

    def __init__(self, host):
        self.host = host
        host.trigger.add("sendMessage", self._sendMessageTrigger)
        host.trigger.add("MessageReceived", self._MessageReceivedTrigger, priority=100)
        host.registerNamespace("eme", NS_EME)

    def _addEMEElement(self, mess_data, namespace, name):
        message_elt = mess_data['xml']
        encryption_elt = message_elt.addElement((NS_EME, 'encryption'))
        encryption_elt['namespace'] = namespace
        if name is not None:
            encryption_elt['name'] = name
        return mess_data

    def _sendMessageTrigger(self, client, mess_data, __, post_xml_treatments):
        encryption = mess_data.get(C.MESS_KEY_ENCRYPTION)
        if encryption is not None:
            namespace = encryption['plugin'].namespace
            if namespace not in KNOWN_NAMESPACES:
                name = encryption['plugin'].name
            else:
                name = None
            post_xml_treatments.addCallback(
                self._addEMEElement, namespace=namespace, name=name)
        return True

    def _MessageReceivedTrigger(self, client, message_elt, post_treat):
        try:
            encryption_elt = next(message_elt.elements(NS_EME, 'encryption'))
        except StopIteration:
            return True

        namespace = encryption_elt['namespace']
        if namespace in client.encryption.getNamespaces():
            # message is encrypted and we can decrypt it
            return True

        name = KNOWN_NAMESPACES.get(namespace, encryption_elt.getAttribute("name"))

        # at this point, message is encrypted but we know that we can't decrypt it,
        # we need to notify the user
        sender_s = message_elt['from']
        to_jid = jid.JID(message_elt['from'])
        algorithm = "{} [{}]".format(name, namespace) if name else namespace
        log.warning(
            _("Message from {sender} is encrypted with {algorithm} and we can't "
              "decrypt it.".format(sender=message_elt['from'], algorithm=algorithm)))

        user_msg = D_(
            "User {sender} sent you an encrypted message (encrypted with {algorithm}), "
            "and we can't decrypt it.").format(sender=sender_s, algorithm=algorithm)

        extra = {C.MESS_EXTRA_INFO: C.EXTRA_INFO_DECR_ERR}
        client.feedback(to_jid, user_msg, extra)
        return False