475 lines
20 KiB
Python
475 lines
20 KiB
Python
#!/usr/bin/env python3
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# SAT: a jabber client
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# Copyright (C) 2009-2020 Jérôme Poisson (goffi@goffi.org)
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Affero General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Affero General Public License for more details.
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# You should have received a copy of the GNU Affero General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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from functools import partial
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from sat.core.i18n import D_, _
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from sat.core.constants import Const as C
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from sat.core import exceptions
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from collections import namedtuple
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from sat.core.log import getLogger
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from sat.tools.common import data_format
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from twisted.words.protocols.jabber import jid
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from twisted.internet import defer
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from twisted.python import failure
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import copy
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log = getLogger(__name__)
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log = getLogger(__name__)
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EncryptionPlugin = namedtuple("EncryptionPlugin", ("instance",
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"name",
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"namespace",
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"priority",
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"directed"))
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class EncryptionHandler(object):
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"""Class to handle encryption sessions for a client"""
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plugins = [] # plugin able to encrypt messages
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def __init__(self, client):
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self.client = client
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self._sessions = {} # bare_jid ==> encryption_data
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@property
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def host(self):
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return self.client.host_app
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@classmethod
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def registerPlugin(cls, plg_instance, name, namespace, priority=0, directed=False):
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"""Register a plugin handling an encryption algorithm
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@param plg_instance(object): instance of the plugin
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it must have the following methods:
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- getTrustUI(entity): return a XMLUI for trust management
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entity(jid.JID): entity to manage
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The returned XMLUI must be a form
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if may have the following methods:
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- startEncryption(entity): start encrypted session
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entity(jid.JID): entity to start encrypted session with
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- stopEncryption(entity): start encrypted session
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entity(jid.JID): entity to stop encrypted session with
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if they don't exists, those 2 methods will be ignored.
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@param name(unicode): human readable name of the encryption algorithm
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@param namespace(unicode): namespace of the encryption algorithm
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@param priority(int): priority of this plugin to encrypt an message when not
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selected manually
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@param directed(bool): True if this plugin is directed (if it works with one
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device only at a time)
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"""
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existing_ns = set()
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existing_names = set()
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for p in cls.plugins:
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existing_ns.add(p.namespace.lower())
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existing_names.add(p.name.lower())
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if namespace.lower() in existing_ns:
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raise exceptions.ConflictError("A plugin with this namespace already exists!")
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if name.lower() in existing_names:
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raise exceptions.ConflictError("A plugin with this name already exists!")
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plugin = EncryptionPlugin(
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instance=plg_instance,
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name=name,
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namespace=namespace,
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priority=priority,
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directed=directed)
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cls.plugins.append(plugin)
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cls.plugins.sort(key=lambda p: p.priority)
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log.info(_("Encryption plugin registered: {name}").format(name=name))
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@classmethod
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def getPlugins(cls):
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return cls.plugins
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@classmethod
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def getPlugin(cls, namespace):
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try:
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return next(p for p in cls.plugins if p.namespace == namespace)
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except StopIteration:
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raise exceptions.NotFound(_(
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"Can't find requested encryption plugin: {namespace}").format(
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namespace=namespace))
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@classmethod
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def getNamespaces(cls):
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"""Get available plugin namespaces"""
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return {p.namespace for p in cls.getPlugins()}
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@classmethod
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def getNSFromName(cls, name):
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"""Retrieve plugin namespace from its name
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@param name(unicode): name of the plugin (case insensitive)
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@return (unicode): namespace of the plugin
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@raise exceptions.NotFound: there is not encryption plugin of this name
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"""
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for p in cls.plugins:
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if p.name.lower() == name.lower():
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return p.namespace
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raise exceptions.NotFound(_(
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"Can't find a plugin with the name \"{name}\".".format(
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name=name)))
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def getBridgeData(self, session):
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"""Retrieve session data serialized for bridge.
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@param session(dict): encryption session
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@return (unicode): serialized data for bridge
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"""
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if session is None:
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return ''
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plugin = session['plugin']
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bridge_data = {'name': plugin.name,
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'namespace': plugin.namespace}
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if 'directed_devices' in session:
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bridge_data['directed_devices'] = session['directed_devices']
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return data_format.serialise(bridge_data)
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def _startEncryption(self, plugin, entity):
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"""Start encryption with a plugin
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This method must be called just before adding a plugin session.
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StartEncryptionn method of plugin will be called if it exists.
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"""
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try:
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start_encryption = plugin.instance.startEncryption
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except AttributeError:
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log.debug("No startEncryption method found for {plugin}".format(
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plugin = plugin.namespace))
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return defer.succeed(None)
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else:
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# we copy entity to avoid having the resource changed by stop_encryption
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return defer.maybeDeferred(start_encryption, self.client, copy.copy(entity))
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def _stopEncryption(self, plugin, entity):
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"""Stop encryption with a plugin
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This method must be called just before removing a plugin session.
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StopEncryptionn method of plugin will be called if it exists.
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"""
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try:
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stop_encryption = plugin.instance.stopEncryption
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except AttributeError:
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log.debug("No stopEncryption method found for {plugin}".format(
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plugin = plugin.namespace))
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return defer.succeed(None)
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else:
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# we copy entity to avoid having the resource changed by stop_encryption
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return defer.maybeDeferred(stop_encryption, self.client, copy.copy(entity))
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@defer.inlineCallbacks
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def start(self, entity, namespace=None, replace=False):
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"""Start an encryption session with an entity
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@param entity(jid.JID): entity to start an encryption session with
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must be bare jid is the algorithm encrypt for all devices
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@param namespace(unicode, None): namespace of the encryption algorithm
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to use.
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None to select automatically an algorithm
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@param replace(bool): if True and an encrypted session already exists,
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it will be replaced by the new one
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"""
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if not self.plugins:
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raise exceptions.NotFound(_("No encryption plugin is registered, "
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"an encryption session can't be started"))
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if namespace is None:
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plugin = self.plugins[0]
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else:
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plugin = self.getPlugin(namespace)
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bare_jid = entity.userhostJID()
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if bare_jid in self._sessions:
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# we have already an encryption session with this contact
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former_plugin = self._sessions[bare_jid]["plugin"]
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if former_plugin.namespace == namespace:
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log.info(_("Session with {bare_jid} is already encrypted with {name}. "
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"Nothing to do.").format(
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bare_jid=bare_jid, name=former_plugin.name))
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return
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if replace:
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# there is a conflict, but replacement is requested
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# so we stop previous encryption to use new one
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del self._sessions[bare_jid]
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yield self._stopEncryption(former_plugin, entity)
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else:
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msg = (_("Session with {bare_jid} is already encrypted with {name}. "
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"Please stop encryption session before changing algorithm.")
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.format(bare_jid=bare_jid, name=plugin.name))
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log.warning(msg)
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raise exceptions.ConflictError(msg)
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data = {"plugin": plugin}
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if plugin.directed:
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if not entity.resource:
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entity.resource = self.host.memory.getMainResource(self.client, entity)
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if not entity.resource:
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raise exceptions.NotFound(
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_("No resource found for {destinee}, can't encrypt with {name}")
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.format(destinee=entity.full(), name=plugin.name))
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log.info(_("No resource specified to encrypt with {name}, using "
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"{destinee}.").format(destinee=entity.full(),
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name=plugin.name))
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# indicate that we encrypt only for some devices
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directed_devices = data['directed_devices'] = [entity.resource]
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elif entity.resource:
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raise ValueError(_("{name} encryption must be used with bare jids."))
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yield self._startEncryption(plugin, entity)
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self._sessions[entity.userhostJID()] = data
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log.info(_("Encryption session has been set for {entity_jid} with "
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"{encryption_name}").format(
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entity_jid=entity.full(), encryption_name=plugin.name))
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self.host.bridge.messageEncryptionStarted(
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entity.full(),
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self.getBridgeData(data),
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self.client.profile)
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msg = D_("Encryption session started: your messages with {destinee} are "
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"now end to end encrypted using {name} algorithm.").format(
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destinee=entity.full(), name=plugin.name)
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directed_devices = data.get('directed_devices')
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if directed_devices:
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msg += "\n" + D_("Message are encrypted only for {nb_devices} device(s): "
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"{devices_list}.").format(
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nb_devices=len(directed_devices),
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devices_list = ', '.join(directed_devices))
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self.client.feedback(bare_jid, msg)
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@defer.inlineCallbacks
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def stop(self, entity, namespace=None):
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"""Stop an encryption session with an entity
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@param entity(jid.JID): entity with who the encryption session must be stopped
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must be bare jid if the algorithm encrypt for all devices
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@param namespace(unicode): namespace of the session to stop
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when specified, used to check we stop the right encryption session
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"""
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session = self.getSession(entity.userhostJID())
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if not session:
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raise failure.Failure(
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exceptions.NotFound(_("There is no encryption session with this "
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"entity.")))
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plugin = session['plugin']
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if namespace is not None and plugin.namespace != namespace:
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raise exceptions.InternalError(_(
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"The encryption session is not run with the expected plugin: encrypted "
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"with {current_name} and was expecting {expected_name}").format(
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current_name=session['plugin'].namespace,
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expected_name=namespace))
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if entity.resource:
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try:
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directed_devices = session['directed_devices']
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except KeyError:
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raise exceptions.NotFound(_(
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"There is a session for the whole entity (i.e. all devices of the "
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"entity), not a directed one. Please use bare jid if you want to "
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"stop the whole encryption with this entity."))
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try:
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directed_devices.remove(entity.resource)
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except ValueError:
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raise exceptions.NotFound(_("There is no directed session with this "
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"entity."))
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else:
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if not directed_devices:
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# if we have no more directed device sessions,
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# we stop the whole session
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# see comment below for deleting session before stopping encryption
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del self._sessions[entity.userhostJID()]
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yield self._stopEncryption(plugin, entity)
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else:
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# plugin's stopEncryption may call stop again (that's the case with OTR)
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# so we need to remove plugin from session before calling self._stopEncryption
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del self._sessions[entity.userhostJID()]
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yield self._stopEncryption(plugin, entity)
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log.info(_("encryption session stopped with entity {entity}").format(
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entity=entity.full()))
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self.host.bridge.messageEncryptionStopped(
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entity.full(),
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{'name': plugin.name,
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'namespace': plugin.namespace,
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},
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self.client.profile)
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msg = D_("Encryption session finished: your messages with {destinee} are "
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"NOT end to end encrypted anymore.\nYour server administrators or "
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"{destinee} server administrators will be able to read them.").format(
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destinee=entity.full())
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self.client.feedback(entity, msg)
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def getSession(self, entity):
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"""Get encryption session for this contact
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@param entity(jid.JID): get the session for this entity
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must be a bare jid
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@return (dict, None): encryption session data
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None if there is not encryption for this session with this jid
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"""
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if entity.resource:
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raise ValueError("Full jid given when expecting bare jid")
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return self._sessions.get(entity)
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def getTrustUI(self, entity_jid, namespace=None):
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"""Retrieve encryption UI
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@param entity_jid(jid.JID): get the UI for this entity
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must be a bare jid
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@param namespace(unicode): namespace of the algorithm to manage
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if None use current algorithm
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@return D(xmlui): XMLUI for trust management
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the xmlui is a form
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None if there is not encryption for this session with this jid
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@raise exceptions.NotFound: no algorithm/plugin found
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@raise NotImplementedError: plugin doesn't handle UI management
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"""
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if namespace is None:
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session = self.getSession(entity_jid)
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if not session:
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raise exceptions.NotFound(
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"No encryption session currently active for {entity_jid}"
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.format(entity_jid=entity_jid.full()))
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plugin = session['plugin']
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else:
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plugin = self.getPlugin(namespace)
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try:
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get_trust_ui = plugin.instance.getTrustUI
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except AttributeError:
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raise NotImplementedError(
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"Encryption plugin doesn't handle trust management UI")
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else:
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return defer.maybeDeferred(get_trust_ui, self.client, entity_jid)
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## Menus ##
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@classmethod
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def _importMenus(cls, host):
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host.importMenu(
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(D_("Encryption"), D_("unencrypted (plain text)")),
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partial(cls._onMenuUnencrypted, host=host),
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security_limit=0,
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help_string=D_("End encrypted session"),
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type_=C.MENU_SINGLE,
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)
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for plg in cls.getPlugins():
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host.importMenu(
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(D_("Encryption"), plg.name),
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partial(cls._onMenuName, host=host, plg=plg),
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security_limit=0,
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help_string=D_("Start {name} session").format(name=plg.name),
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type_=C.MENU_SINGLE,
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)
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host.importMenu(
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(D_("Encryption"), D_("⛨ {name} trust").format(name=plg.name)),
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partial(cls._onMenuTrust, host=host, plg=plg),
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security_limit=0,
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help_string=D_("Manage {name} trust").format(name=plg.name),
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type_=C.MENU_SINGLE,
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)
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@classmethod
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def _onMenuUnencrypted(cls, data, host, profile):
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client = host.getClient(profile)
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peer_jid = jid.JID(data['jid']).userhostJID()
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d = client.encryption.stop(peer_jid)
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d.addCallback(lambda __: {})
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return d
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@classmethod
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def _onMenuName(cls, data, host, plg, profile):
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client = host.getClient(profile)
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peer_jid = jid.JID(data['jid'])
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if not plg.directed:
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peer_jid = peer_jid.userhostJID()
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d = client.encryption.start(peer_jid, plg.namespace, replace=True)
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d.addCallback(lambda __: {})
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return d
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@classmethod
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@defer.inlineCallbacks
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def _onMenuTrust(cls, data, host, plg, profile):
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client = host.getClient(profile)
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peer_jid = jid.JID(data['jid']).userhostJID()
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ui = yield client.encryption.getTrustUI(peer_jid, plg.namespace)
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defer.returnValue({'xmlui': ui.toXml()})
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## Triggers ##
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def setEncryptionFlag(self, mess_data):
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"""Set "encryption" key in mess_data if session with destinee is encrypted"""
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to_jid = mess_data['to']
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encryption = self._sessions.get(to_jid.userhostJID())
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if encryption is not None:
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if mess_data["type"] == "groupchat" and encryption['plugin'].directed:
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raise exceptions.InternalError(
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f"encryption flag must not be set for groupchat if encryption algorithm "
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f"({encryption['plugin'].name}) is directed!")
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mess_data[C.MESS_KEY_ENCRYPTION] = encryption
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## Misc ##
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def markAsEncrypted(self, mess_data):
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"""Helper method to mark a message as having been e2e encrypted.
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This should be used in the post_treat workflow of messageReceived trigger of
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the plugin
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@param mess_data(dict): message data as used in post treat workflow
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"""
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mess_data[C.MESS_KEY_ENCRYPTED] = True
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return mess_data
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def isEncryptionRequested(self, mess_data):
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"""Helper method to check if encryption is requested in an outgoind message
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@param mess_data(dict): message data for outgoing message
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@return (bool): True if the encryption flag is present
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"""
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return bool(mess_data.get(C.MESS_KEY_ENCRYPTION, False))
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def isEncrypted(self, mess_data):
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"""Helper method to check if an incoming message has the e2e encrypted flag
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@param mess_data(dict): message data
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@return (bool): True if the encrypted flag is present
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"""
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return mess_data.get(C.MESS_KEY_ENCRYPTED, False)
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def markAsTrusted(self, mess_data):
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"""Helper methor to mark a message as sent from a trusted entity.
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This should be used in the post_treat workflow of messageReceived trigger of
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the plugin
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@param mess_data(dict): message data as used in post treat workflow
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"""
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mess_data[C.MESS_KEY_TRUSTED] = True
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return mess_data
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def markAsUntrusted(self, mess_data):
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"""Helper methor to mark a message as sent from an untrusted entity.
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This should be used in the post_treat workflow of messageReceived trigger of
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the plugin
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@param mess_data(dict): message data as used in post treat workflow
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"""
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mess_data['trusted'] = False
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return mess_data
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