slixmpp-omemo/examples/echo_client.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

"""
    Slixmpp OMEMO plugin
    Copyright (C) 2010  Nathanael C. Fritz
    Copyright (C) 2019 Maxime “pep” Buquet <pep@bouah.net>
    This file is part of slixmpp-omemo.

    See the file LICENSE for copying permission.
"""

import os
import sys
import logging
from getpass import getpass
from argparse import ArgumentParser

from slixmpp import ClientXMPP, JID
from slixmpp.stanza import Message
from slixmpp_omemo import PluginCouldNotLoad, MissingOwnKey, EncryptionPrepareException
from slixmpp_omemo import UndecidedException, UntrustedException, NoAvailableSession
import slixmpp_omemo

log = logging.getLogger(__name__)


class EchoBot(ClientXMPP):

    """
    A simple Slixmpp bot that will echo encrypted messages it receives, along
    with a short thank you message.

    For details on how to build a client with slixmpp, look at exemples in the
    slixmpp repository.
    """

    def __init__(self, jid, password):
        ClientXMPP.__init__(self, jid, password)

        self.add_event_handler("session_start", self.start)
        self.add_event_handler("message", self.message)

    def start(self, _event) -> None:
        """
        Process the session_start event.

        Typical actions for the session_start event are
        requesting the roster and broadcasting an initial
        presence stanza.

        Arguments:
            event -- An empty dictionary. The session_start
                     event does not provide any additional
                     data.
        """
        self.send_presence()
        self.get_roster()

    def message(self, msg: Message, allow_untrusted: bool = False) -> None:
        """
        Process incoming message stanzas. Be aware that this also
        includes MUC messages and error messages. It is usually
        a good idea to check the messages's type before processing
        or sending replies.

        Arguments:
            msg -- The received message stanza. See the documentation
                   for stanza objects and the Message stanza to see
                   how it may be used.
        """
        if msg['type'] not in ('chat', 'normal'):
            return None

        if not self['xep_0384'].is_encrypted(msg):
            self.plain_reply(msg, 'This message was not encrypted.\n%(body)s' % msg)
            return None

        try:
            body = self['xep_0384'].decrypt_message(msg, allow_untrusted)
            self.encrypted_reply(msg, 'Thanks for sending\n%s' % body.decode("utf8"))
        except (MissingOwnKey,):
            # The message is missing our own key, it was not encrypted for
            # us, and we can't decrypt it.
            self.plain_reply(
                msg,
                'I can\'t decrypt this message as it is not encrypted for me.',
            )
        except (NoAvailableSession,) as exn:
            # We received a message from that contained a session that we
            # don't know about (deleted session storage, etc.). We can't
            # decrypt the message, and it's going to be lost.
            # Here, as we need to initiate a new encrypted session, it is
            # best if we send an encrypted message directly. XXX: Is it
            # where we talk about self-healing messages?
            self.encrypted_reply(
                msg,
                'I can\'t decrypt this message as it uses an encrypted '
                'session I don\'t know about.',
            )
        except (UndecidedException, UntrustedException) as exn:
            # We received a message from an untrusted device. We can
            # choose to decrypt the message nonetheless, with the
            # `allow_untrusted` flag on the `decrypt_message` call, which
            # we will do here. This is only possible for decryption,
            # encryption will require us to decide if we trust the device
            # or not. Clients _should_ indicate that the message was not
            # trusted, or in undecided state, if they decide to decrypt it
            # anyway.
            self.plain_reply(
                msg,
                "Your device '%s' is not in my trusted devices." % exn.device,
            )
            # We resend, setting the `allow_untrusted` parameter to True.
            self.message(msg, allow_untrusted=True)
        except (EncryptionPrepareException,):
            # Slixmpp tried its best, but there were errors it couldn't
            # resolve. At this point you should have seen other exceptions
            # and given a chance to resolve them already.
            self.plain_reply(msg, 'I was not able to decrypt the message.')

        return None

    def plain_reply(self, original_msg, body) -> None:
        """
        Helper to reply to messages
        """

        mto = original_msg['from']
        mtype = original_msg['type']
        msg = self.make_message(mto=mto, mtype=mtype)
        msg['body'] = body
        msg.send()

    def encrypted_reply(self, original_msg, body) -> None:
        """Helper to reply with encrypted messages"""

        # TODO: Send the message encrypted.
        self.plain_reply(msg, body)


if __name__ == '__main__':
    # Setup the command line arguments.
    parser = ArgumentParser(description=EchoBot.__doc__)

    # Output verbosity options.
    parser.add_argument("-q", "--quiet", help="set logging to ERROR",
                        action="store_const", dest="loglevel",
                        const=logging.ERROR, default=logging.INFO)
    parser.add_argument("-d", "--debug", help="set logging to DEBUG",
                        action="store_const", dest="loglevel",
                        const=logging.DEBUG, default=logging.INFO)

    # JID and password options.
    parser.add_argument("-j", "--jid", dest="jid",
                        help="JID to use")
    parser.add_argument("-p", "--password", dest="password",
                        help="password to use")

    # Data dir for omemo plugin
    DATA_DIR = os.path.join(
        os.path.dirname(os.path.abspath(__file__)),
        'omemo',
    )
    parser.add_argument("--data-dir", dest="data_dir",
                        help="data directory", default=DATA_DIR)

    args = parser.parse_args()

    # Setup logging.
    logging.basicConfig(level=args.loglevel,
                        format='%(levelname)-8s %(message)s')

    if args.jid is None:
        args.jid = input("Username: ")
    if args.password is None:
        args.password = getpass("Password: ")

    # Setup the EchoBot and register plugins. Note that while plugins may
    # have interdependencies, the order in which you register them does
    # not matter.

    # Ensure OMEMO data dir is created
    os.makedirs(args.data_dir, exist_ok=True)

    xmpp = EchoBot(args.jid, args.password)
    xmpp.register_plugin('xep_0030') # Service Discovery
    xmpp.register_plugin('xep_0199') # XMPP Ping
    xmpp.register_plugin('xep_0380') # Explicit Message Encryption

    try:
        xmpp.register_plugin(
            'xep_0384',
            {
                'data_dir': args.data_dir,
            },
            module=slixmpp_omemo,
        ) # OMEMO
    except (PluginCouldNotLoad,):
        log.exception('And error occured when loading the omemo plugin.')
        sys.exit(1)

    # Connect to the XMPP server and start processing XMPP stanzas.
    xmpp.connect()
    xmpp.process()