view sat/plugins/plugin_xep_0095.py @ 2646:712cb4ff3e13

core: new EncryptionHandler class which manage encrypted session as a core feature: Plugin handling encryption can now register using host.registerEncryptionPlugin, and an encryption session can now be started using messageEncryptionStart bridge method. This will make encryption handling more easy, as we now know if a session is clear or e2e encrypted, and which plugin handle it.
author Goffi <goffi@goffi.org>
date Sun, 29 Jul 2018 19:22:56 +0200
parents 56f94936df1e
children 003b8b4b56a7
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#!/usr/bin/env python2
# -*- coding: utf-8 -*-

# SAT plugin for managing xep-0095
# Copyright (C) 2009-2018 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 _
from sat.core.constants import Const as C
from sat.core.log import getLogger

log = getLogger(__name__)
from sat.core import exceptions
from twisted.words.protocols.jabber import xmlstream
from twisted.words.protocols.jabber import error
from zope.interface import implements
from wokkel import disco
from wokkel import iwokkel
import uuid


PLUGIN_INFO = {
    C.PI_NAME: "XEP 0095 Plugin",
    C.PI_IMPORT_NAME: "XEP-0095",
    C.PI_TYPE: "XEP",
    C.PI_PROTOCOLS: ["XEP-0095"],
    C.PI_MAIN: "XEP_0095",
    C.PI_HANDLER: "yes",
    C.PI_DESCRIPTION: _("""Implementation of Stream Initiation"""),
}


IQ_SET = '/iq[@type="set"]'
NS_SI = "http://jabber.org/protocol/si"
SI_REQUEST = IQ_SET + '/si[@xmlns="' + NS_SI + '"]'
SI_PROFILE_HEADER = "http://jabber.org/protocol/si/profile/"
SI_ERROR_CONDITIONS = ("bad-profile", "no-valid-streams")


class XEP_0095(object):
    def __init__(self, host):
        log.info(_("Plugin XEP_0095 initialization"))
        self.host = host
        self.si_profiles = {}  # key: SI profile, value: callback

    def getHandler(self, client):
        return XEP_0095_handler(self)

    def registerSIProfile(self, si_profile, callback):
        """Add a callback for a SI Profile

        @param si_profile(unicode): SI profile name (e.g. file-transfer)
        @param callback(callable): method to call when the profile name is asked
        """
        self.si_profiles[si_profile] = callback

    def unregisterSIProfile(self, si_profile):
        try:
            del self.si_profiles[si_profile]
        except KeyError:
            log.error(
                u"Trying to unregister SI profile [{}] which was not registered".format(
                    si_profile
                )
            )

    def streamInit(self, iq_elt, client):
        """This method is called on stream initiation (XEP-0095 #3.2)

        @param iq_elt: IQ element
        """
        log.info(_("XEP-0095 Stream initiation"))
        iq_elt.handled = True
        si_elt = iq_elt.elements(NS_SI, "si").next()
        si_id = si_elt["id"]
        si_mime_type = iq_elt.getAttribute("mime-type", "application/octet-stream")
        si_profile = si_elt["profile"]
        si_profile_key = (
            si_profile[len(SI_PROFILE_HEADER) :]
            if si_profile.startswith(SI_PROFILE_HEADER)
            else si_profile
        )
        if si_profile_key in self.si_profiles:
            # We know this SI profile, we call the callback
            self.si_profiles[si_profile_key](client, iq_elt, si_id, si_mime_type, si_elt)
        else:
            # We don't know this profile, we send an error
            self.sendError(client, iq_elt, "bad-profile")

    def sendError(self, client, request, condition):
        """Send IQ error as a result

        @param request(domish.Element): original IQ request
        @param condition(str): error condition
        """
        if condition in SI_ERROR_CONDITIONS:
            si_condition = condition
            condition = "bad-request"
        else:
            si_condition = None

        iq_error_elt = error.StanzaError(condition).toResponse(request)
        if si_condition is not None:
            iq_error_elt.error.addElement((NS_SI, si_condition))

        client.send(iq_error_elt)

    def acceptStream(self, client, iq_elt, feature_elt, misc_elts=None):
        """Send the accept stream initiation answer

        @param iq_elt(domish.Element): initial SI request
        @param feature_elt(domish.Element): 'feature' element containing stream method to use
        @param misc_elts(list[domish.Element]): list of elements to add
        """
        log.info(_("sending stream initiation accept answer"))
        if misc_elts is None:
            misc_elts = []
        result_elt = xmlstream.toResponse(iq_elt, "result")
        si_elt = result_elt.addElement((NS_SI, "si"))
        si_elt.addChild(feature_elt)
        for elt in misc_elts:
            si_elt.addChild(elt)
        client.send(result_elt)

    def _parseOfferResult(self, iq_elt):
        try:
            si_elt = iq_elt.elements(NS_SI, "si").next()
        except StopIteration:
            log.warning(u"No <si/> element found in result while expected")
            raise exceptions.DataError
        return (iq_elt, si_elt)

    def proposeStream(
        self,
        client,
        to_jid,
        si_profile,
        feature_elt,
        misc_elts,
        mime_type="application/octet-stream",
    ):
        """Propose a stream initiation

        @param to_jid(jid.JID): recipient
        @param si_profile(unicode): Stream initiation profile (XEP-0095)
        @param feature_elt(domish.Element): feature element, according to XEP-0020
        @param misc_elts(list[domish.Element]): list of elements to add
        @param mime_type(unicode): stream mime type
        @return (tuple): tuple with:
            - session id (unicode)
            - (D(domish_elt, domish_elt): offer deferred which returl a tuple
                with iq_elt and si_elt
        """
        offer = client.IQ()
        sid = str(uuid.uuid4())
        log.debug(_(u"Stream Session ID: %s") % offer["id"])

        offer["from"] = client.jid.full()
        offer["to"] = to_jid.full()
        si = offer.addElement("si", NS_SI)
        si["id"] = sid
        si["mime-type"] = mime_type
        si["profile"] = si_profile
        for elt in misc_elts:
            si.addChild(elt)
        si.addChild(feature_elt)

        offer_d = offer.send()
        offer_d.addCallback(self._parseOfferResult)
        return sid, offer_d


class XEP_0095_handler(xmlstream.XMPPHandler):
    implements(iwokkel.IDisco)

    def __init__(self, plugin_parent):
        self.plugin_parent = plugin_parent
        self.host = plugin_parent.host

    def connectionInitialized(self):
        self.xmlstream.addObserver(
            SI_REQUEST, self.plugin_parent.streamInit, client=self.parent
        )

    def getDiscoInfo(self, requestor, target, nodeIdentifier=""):
        return [disco.DiscoFeature(NS_SI)] + [
            disco.DiscoFeature(
                u"http://jabber.org/protocol/si/profile/{}".format(profile_name)
            )
            for profile_name in self.plugin_parent.si_profiles
        ]

    def getDiscoItems(self, requestor, target, nodeIdentifier=""):
        return []