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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# vim:fenc=utf-8 et ts=4 sts=4 sw=4
#
# Copyright © 2019 Maxime “pep” Buquet <pep@bouah.net>
#
# Distributed under terms of the zlib license. See COPYING file.
"""
Interface for E2EE (End-to-end Encryption) plugins.
"""
from typing import Callable, Dict, Optional, Union
from slixmpp import InvalidJID, JID, Message
from slixmpp.xmlstream import StanzaBase
from poezio.tabs import ConversationTab, DynamicConversationTab, PrivateTab, MucTab
from poezio.plugin import BasePlugin
import logging
log = logging.getLogger(__name__)
ChatTabs = Union[
MucTab,
DynamicConversationTab,
PrivateTab,
]
EME_NS = 'urn:xmpp:eme:0'
EME_TAG = 'encryption'
JCLIENT_NS = 'jabber:client'
HINTS_NS = 'urn:xmpp:hints'
class E2EEPlugin(BasePlugin):
"""Interface for E2EE plugins"""
# Specifies that the encryption mechanism does more than encrypting
# <body/>.
stanza_encryption = False
# Whitelist applied to messages when `stanza_encryption` is False.
tag_whitelist = list(map(lambda x: '{%s}%s' % (x[0], x[1]), [
(JCLIENT_NS, 'body'),
(EME_NS, EME_TAG),
(HINTS_NS, 'store'),
(HINTS_NS, 'no-copy'),
(HINTS_NS, 'no-store'),
(HINTS_NS, 'no-permanent-store'),
# TODO: Add other encryption mechanisms tags here
]))
replace_body_with_eme = True
# At least one of encryption_name and encryption_short_name must be set
encryption_name = None # type: Optional[str]
encryption_short_name = None # type: Optional[str]
# Required.
eme_ns = None # type: Optional[str]
# Static map, to be able to limit to one encryption mechanism per tab at a
# time
_enabled_tabs = {} # type: Dict[JID, Callable]
def init(self):
if self.encryption_name is None and self.encryption_short_name is None:
raise NotImplementedError
if self.eme_ns is None:
raise NotImplementedError
if self.encryption_name is None:
self.encryption_name = self.encryption_short_name
if self.encryption_short_name is None:
self.encryption_short_name = self.encryption_name
# Ensure decryption is done before everything, so that other handlers
# don't have to know about the encryption mechanism.
self.api.add_event_handler('muc_msg', self._decrypt, priority=0)
self.api.add_event_handler('conversation_msg', self._decrypt, priority=0)
self.api.add_event_handler('private_msg', self._decrypt, priority=0)
# Ensure encryption is done after everything, so that whatever can be
# encrypted is encrypted, and no plain element slips in.
# Using a stream filter might be a bit too much, but at least we're
# sure poezio is not sneaking anything past us.
self.core.xmpp.add_filter('out', self._encrypt)
for tab_t in (DynamicConversationTab, PrivateTab, MucTab):
self.api.add_tab_command(
tab_t,
self.encryption_short_name,
self._toggle_tab,
usage='',
short='Toggle {} encryption for tab.'.format(self.encryption_name),
help='Toggle automatic {} encryption for tab.'.format(self.encryption_name),
)
ConversationTab.add_information_element(
self.encryption_short_name,
self._display_encryption_status,
)
MucTab.add_information_element(
self.encryption_short_name,
self._display_encryption_status,
)
PrivateTab.add_information_element(
self.encryption_short_name,
self._display_encryption_status,
)
def cleanup(self):
ConversationTab.remove_information_element(self.encryption_short_name)
MucTab.remove_information_element(self.encryption_short_name)
PrivateTab.remove_information_element(self.encryption_short_name)
def _display_encryption_status(self, jid_s: str) -> str:
"""
Return information to display in the infobar if encryption is
enabled for the JID.
"""
try:
jid = JID(jid_s)
except InvalidJID:
return ""
if self._encryption_enabled(jid):
return " " + self.encryption_short_name
return ""
def _toggle_tab(self, _input: str) -> None:
jid = self.api.current_tab().jid # type: JID
if self._encryption_enabled(jid):
del self._enabled_tabs[jid]
self.api.information(
'{} encryption disabled for {}'.format(self.encryption_name, jid),
'Info',
)
else:
self._enabled_tabs[jid] = self.encrypt
self.api.information(
'{} encryption enabled for {}'.format(self.encryption_name, jid),
'Info',
)
def _encryption_enabled(self, jid: JID) -> bool:
return jid in self._enabled_tabs and self._enabled_tabs[jid] == self.encrypt
def _decrypt(self, message: Message, tab: ChatTabs) -> None:
if message.xml.find('{%s}%s' % (EME_NS, EME_TAG)) is None:
return None
if message['eme']['namespace'] != self.eme_ns:
return None
log.debug('Received %s message: %r', self.encryption_name, message['body'])
self.decrypt(message, tab)
log.debug('Decrypted %s message: %r', self.encryption_name, message['body'])
return None
def _encrypt(self, stanza: StanzaBase) -> Optional[StanzaBase]:
if not isinstance(stanza, Message) or stanza['type'] not in ('chat', 'groupchat'):
return stanza
message = stanza
tab = self.api.current_tab()
jid = tab.jid
if not self._encryption_enabled(jid):
return message
log.debug('Sending %s message: %r', self.encryption_name, message)
has_body = message.xml.find('{%s}%s' % (JCLIENT_NS, 'body')) is not None
# Drop all messages that don't contain a body if the plugin doesn't do
# Stanza Encryption
if not self.stanza_encryption and not has_body:
log.debug(
'%s plugin: Dropping message as it contains no body, and is '
'not doesn\'t do stanza encryption: %r',
self.encryption_name,
message,
)
return None
# Call the enabled encrypt method
self._enabled_tabs[jid](message, tab)
if has_body:
# Only add EME tag if the message has a body.
# Per discussion in jdev@:
# The receiving client needs to know the message contains
# meaningful information or not to display notifications to the
# user, and not display anything when it's e.g., a chatstate.
# This does leak the fact that the encrypted payload contains a
# message.
message['eme']['namespace'] = self.eme_ns
message['eme']['name'] = self.encryption_name
if self.replace_body_with_eme:
self.core.xmpp['xep_0380'].replace_body_with_eme(message)
# Filter stanza with the whitelist. Plugins doing stanza encryption
# will have to include these in their encrypted container beforehand.
for elem in message.xml[:]:
if elem.tag not in self.tag_whitelist:
message.xml.remove(elem)
log.debug('Encrypted %s message: %r', self.encryption_name, message)
return message
def decrypt(self, _message: Message, tab: ChatTabs):
"""Decryption method"""
raise NotImplementedError
def encrypt(self, _message: Message, tab: ChatTabs):
"""Encryption method"""
raise NotImplementedError
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