view sat/plugins/plugin_xep_0020.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-0020
# 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.xish import domish

from zope.interface import implements

try:
    from twisted.words.protocols.xmlstream import XMPPHandler
except ImportError:
    from wokkel.subprotocols import XMPPHandler

from wokkel import disco, iwokkel, data_form

NS_FEATURE_NEG = "http://jabber.org/protocol/feature-neg"

PLUGIN_INFO = {
    C.PI_NAME: "XEP 0020 Plugin",
    C.PI_IMPORT_NAME: "XEP-0020",
    C.PI_TYPE: "XEP",
    C.PI_PROTOCOLS: ["XEP-0020"],
    C.PI_MAIN: "XEP_0020",
    C.PI_HANDLER: "yes",
    C.PI_DESCRIPTION: _("""Implementation of Feature Negotiation"""),
}


class XEP_0020(object):
    def __init__(self, host):
        log.info(_("Plugin XEP_0020 initialization"))

    def getHandler(self, client):
        return XEP_0020_handler()

    def getFeatureElt(self, elt):
        """Check element's children to find feature elements

        @param elt(domish.Element): parent element of the feature element
        @return: feature elements
        @raise exceptions.NotFound: no feature element found
        """
        try:
            feature_elt = elt.elements(NS_FEATURE_NEG, "feature").next()
        except StopIteration:
            raise exceptions.NotFound
        return feature_elt

    def _getForm(self, elt, namespace):
        """Return the first child data form

        @param elt(domish.Element): parent of the data form
        @param namespace (None, unicode): form namespace or None to ignore
        @return (None, data_form.Form): data form or None is nothing is found
        """
        if namespace is None:
            try:
                form_elt = elt.elements(data_form.NS_X_DATA).next()
            except StopIteration:
                return None
            else:
                return data_form.Form.fromElement(form_elt)
        else:
            return data_form.findForm(elt, namespace)

    def getChoosedOptions(self, feature_elt, namespace):
        """Return choosed feature for feature element

        @param feature_elt(domish.Element): feature domish element
        @param namespace (None, unicode): form namespace or None to ignore
        @return (dict): feature name as key, and choosed option as value
        @raise exceptions.NotFound: not data form is found
        """
        form = self._getForm(feature_elt, namespace)
        if form is None:
            raise exceptions.NotFound
        result = {}
        for field in form.fields:
            values = form.fields[field].values
            result[field] = values[0] if values else None
            if len(values) > 1:
                log.warning(
                    _(
                        u"More than one value choosed for {}, keeping the first one"
                    ).format(field)
                )
        return result

    def negotiate(self, feature_elt, name, negotiable_values, namespace):
        """Negotiate the feature options

        @param feature_elt(domish.Element): feature element
        @param name: the option name (i.e. field's var attribute) to negotiate
        @param negotiable_values(iterable): acceptable values for this negotiation
            first corresponding value will be returned
        @param namespace (None, unicode): form namespace or None to ignore
        @raise KeyError: name is not found in data form fields
        """
        form = self._getForm(feature_elt, namespace)
        options = [option.value for option in form.fields[name].options]
        for value in negotiable_values:
            if value in options:
                return value
        return None

    def chooseOption(self, options, namespace):
        """Build a feature element with choosed options

        @param options(dict): dict with feature as key and choosed option as value
        @param namespace (None, unicode): form namespace or None to ignore
        """
        feature_elt = domish.Element((NS_FEATURE_NEG, "feature"))
        x_form = data_form.Form("submit", formNamespace=namespace)
        x_form.makeFields(options)
        feature_elt.addChild(x_form.toElement())
        return feature_elt

    def proposeFeatures(self, options_dict, namespace):
        """Build a feature element with options to propose

        @param options_dict(dict): dict with feature as key and iterable of acceptable options as value
        @param namespace(None, unicode): feature namespace
        """
        feature_elt = domish.Element((NS_FEATURE_NEG, "feature"))
        x_form = data_form.Form("form", formNamespace=namespace)
        for field in options_dict:
            x_form.addField(
                data_form.Field(
                    "list-single",
                    field,
                    options=[data_form.Option(option) for option in options_dict[field]],
                )
            )
        feature_elt.addChild(x_form.toElement())
        return feature_elt


class XEP_0020_handler(XMPPHandler):
    implements(iwokkel.IDisco)

    def getDiscoInfo(self, requestor, target, nodeIdentifier=""):
        return [disco.DiscoFeature(NS_FEATURE_NEG)]

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