--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sat_pubsub/delegation.py	Fri Aug 16 12:00:02 2019 +0200
@@ -0,0 +1,293 @@
+#!/usr/bin/python
+#-*- coding: utf-8 -*-
+#
+# Copyright (c) 2015 Jérôme Poisson
+
+
+# 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/>.
+
+# ---
+
+# This module implements XEP-0355 (Namespace delegation) to use SàT Pubsub as PEP service
+
+from wokkel.subprotocols import XMPPHandler
+from wokkel import pubsub
+from wokkel import data_form
+from wokkel import disco, iwokkel
+from wokkel.iwokkel import IPubSubService
+from wokkel import mam
+from twisted.python import log
+from twisted.words.protocols.jabber import jid, error
+from twisted.words.protocols.jabber.xmlstream import toResponse
+from twisted.words.xish import domish
+from zope.interface import implements
+
+DELEGATION_NS = 'urn:xmpp:delegation:1'
+FORWARDED_NS = 'urn:xmpp:forward:0'
+DELEGATION_ADV_XPATH = '/message/delegation[@xmlns="{}"]'.format(DELEGATION_NS)
+DELEGATION_FWD_XPATH = '/iq[@type="set"]/delegation[@xmlns="{}"]/forwarded[@xmlns="{}"]'.format(DELEGATION_NS, FORWARDED_NS)
+
+DELEGATION_MAIN_SEP = "::"
+DELEGATION_BARE_SEP = ":bare:"
+
+TO_HACK = ((IPubSubService, pubsub, "PubSubRequest"),
+           (mam.IMAMService, mam, "MAMRequest"))
+
+
+class InvalidStanza(Exception):
+    pass
+
+
+class DelegationsHandler(XMPPHandler):
+    implements(iwokkel.IDisco)
+    _service_hacked = False
+
+    def __init__(self):
+        super(DelegationsHandler, self).__init__()
+
+    def _service_hack(self):
+        """Patch the request classes of services to track delegated stanzas"""
+        # XXX: we need to monkey patch to track origin of the stanza in PubSubRequest.
+        #      As PubSubRequest from sat.tmp.wokkel.pubsub use _request_class while
+        #      original wokkel.pubsub use directly pubsub.PubSubRequest, we need to
+        #      check which version is used before monkeypatching
+        for handler in self.parent.handlers:
+            for service, module, default_base_cls in TO_HACK:
+                if service.providedBy(handler):
+                    if hasattr(handler, '_request_class'):
+                        request_base_class = handler._request_class
+                    else:
+                        request_base_class = getattr(module, default_base_cls)
+
+                    class RequestWithDelegation(request_base_class):
+                        """A XxxRequest which put an indicator if the stanza comme from delegation"""
+
+                        @classmethod
+                        def fromElement(cls, element):
+                            """Check if element comme from delegation, and set a delegated flags
+
+                            delegated flag is either False, or it's a jid of the delegating server
+                            the delegated flag must be set on element before use
+                            """
+                            try:
+                                # __getattr__ is overriden in domish.Element, so we use __getattribute__
+                                delegated = element.__getattribute__('delegated')
+                            except AttributeError:
+                                delegated = False
+                            instance = cls.__base__.fromElement(element)
+                            instance.delegated = delegated
+                            return instance
+
+                    if hasattr(handler, '_request_class'):
+                        handler._request_class = RequestWithDelegation
+                    else:
+                        setattr(module, default_base_cls, RequestWithDelegation)
+        DelegationsHandler._service_hacked = True
+
+    def connectionInitialized(self):
+        if not self._service_hacked:
+            self._service_hack()
+        self.xmlstream.addObserver(DELEGATION_ADV_XPATH, self.onAdvertise)
+        self.xmlstream.addObserver(DELEGATION_FWD_XPATH, self._obsWrapper, 0, self.onForward)
+        self._current_iqs = {} # dict of iq being handler by delegation
+        self._xs_send = self.xmlstream.send
+        self.xmlstream.send = self._sendHack
+
+    def _sendHack(self, elt):
+        """This method is called instead of xmlstream to control sending
+
+        @param obj(domsish.Element, unicode, str): obj sent to real xmlstream
+        """
+        if isinstance(elt, domish.Element) and elt.name=='iq':
+            try:
+                id_ = elt.getAttribute('id')
+                ori_iq, managed_entity = self._current_iqs[id_]
+                if jid.JID(elt['to']) != managed_entity:
+                    log.msg("IQ id conflict: the managed entity doesn't match (got {got} was expecting {expected})"
+                            .format(got=jid.JID(elt['to']), expected=managed_entity))
+                    raise KeyError
+            except KeyError:
+                # the iq is not a delegated one
+                self._xs_send(elt)
+            else:
+                del self._current_iqs[id_]
+                iq_result_elt = toResponse(ori_iq, 'result')
+                fwd_elt = iq_result_elt.addElement('delegation', DELEGATION_NS).addElement('forwarded', FORWARDED_NS)
+                fwd_elt.addChild(elt)
+                elt.uri = elt.defaultUri = 'jabber:client'
+                self._xs_send(iq_result_elt)
+        else:
+            self._xs_send(elt)
+
+    def _obsWrapper(self, observer, stanza):
+        """Wrapper to observer which catch StanzaError
+
+        @param observer(callable): method to wrap
+        """
+        try:
+            observer(stanza)
+        except error.StanzaError as e:
+            error_elt = e.toResponse(stanza)
+            self._xs_send(error_elt)
+        stanza.handled = True
+
+    def onAdvertise(self, message):
+        """Manage the <message/> advertising delegations"""
+        delegation_elt = message.elements(DELEGATION_NS, 'delegation').next()
+        delegated = {}
+        for delegated_elt in delegation_elt.elements(DELEGATION_NS):
+            try:
+                if delegated_elt.name != 'delegated':
+                    raise InvalidStanza(u'unexpected element {}'.format(delegated_elt.name))
+                try:
+                    namespace = delegated_elt['namespace']
+                except KeyError:
+                    raise InvalidStanza(u'was expecting a "namespace" attribute in delegated element')
+                delegated[namespace] = []
+                for attribute_elt in delegated_elt.elements(DELEGATION_NS, 'attribute'):
+                    try:
+                        delegated[namespace].append(attribute_elt["name"])
+                    except KeyError:
+                        raise InvalidStanza(u'was expecting a "name" attribute in attribute element')
+            except InvalidStanza as e:
+                log.msg("Invalid stanza received ({})".format(e))
+
+        log.msg(u'delegations updated:\n{}'.format(
+            u'\n'.join([u"    - namespace {}{}".format(ns,
+            u"" if not attributes else u" with filtering on {} attribute(s)".format(
+            u", ".join(attributes))) for ns, attributes in delegated.items()])))
+
+        if not pubsub.NS_PUBSUB in delegated:
+            log.msg(u"Didn't got pubsub delegation from server, can't act as a PEP service")
+
+    def onForward(self, iq):
+        """Manage forwarded iq
+
+        @param iq(domish.Element): full delegation stanza
+        """
+
+        # FIXME: we use a hack supposing that our delegation come from hostname
+        #        and we are a component named [name].hostname
+        #        but we need to manage properly allowed servers
+        # TODO: do proper origin security check
+        _, allowed = iq['to'].split('.', 1)
+        if jid.JID(iq['from']) != jid.JID(allowed):
+            log.msg((u"SECURITY WARNING: forwarded stanza doesn't come from our server: {}"
+                     .format(iq.toXml())).encode('utf-8'))
+            raise error.StanzaError('not-allowed')
+
+        try:
+            fwd_iq = (iq.elements(DELEGATION_NS, 'delegation').next()
+                      .elements(FORWARDED_NS, 'forwarded').next()
+                      .elements('jabber:client', 'iq').next())
+        except StopIteration:
+            raise error.StanzaError('not-acceptable')
+
+        managed_entity = jid.JID(fwd_iq['from'])
+
+        self._current_iqs[fwd_iq['id']] = (iq, managed_entity)
+        fwd_iq.delegated = True
+
+        # we need a recipient in pubsub request for PEP
+        # so we set "to" attribute if it doesn't exist
+        if not fwd_iq.hasAttribute('to'):
+            fwd_iq["to"] = jid.JID(fwd_iq["from"]).userhost()
+
+        # we now inject the element in the stream
+        self.xmlstream.dispatch(fwd_iq)
+
+    def getDiscoInfo(self, requestor, target, nodeIdentifier=''):
+        """Manage disco nesting
+
+        This method looks for DiscoHandler in sibling handlers and use it to
+        collect main disco infos. It then filters by delegated namespace and return it.
+        An identity is added for PEP if pubsub namespace is requested.
+
+        The same features/identities are returned for main and bare nodes
+        """
+        if not nodeIdentifier.startswith(DELEGATION_NS):
+            return []
+
+        try:
+            _, namespace = nodeIdentifier.split(DELEGATION_MAIN_SEP, 1)
+        except ValueError:
+            try:
+                _, namespace = nodeIdentifier.split(DELEGATION_BARE_SEP, 1)
+            except ValueError:
+                log.msg("Unexpected disco node: {}".format(nodeIdentifier))
+                raise error.StanzaError('not-acceptable')
+
+        if not namespace:
+            log.msg("No namespace found in node {}".format(nodeIdentifier))
+            return []
+
+        if namespace.startswith(pubsub.NS_PUBSUB):
+            # pubsub use several namespaces starting with NS_PUBSUB (e.g. http://jabber.org/protocol/pubsub#owner)
+            # we return the same disco for all of them
+            namespace = pubsub.NS_PUBSUB
+
+        def gotInfos(infos):
+            ns_features = []
+            for info in infos:
+                if isinstance(info, disco.DiscoFeature) and info.startswith(namespace):
+                    ns_features.append(info)
+                elif (isinstance(info, data_form.Form) and info.formNamespace
+                    and info.formNamespace.startwith(namespace)):
+                    # extensions management (XEP-0128)
+                    ns_features.append(info)
+
+            if namespace == pubsub.NS_PUBSUB:
+                ns_features.append(disco.DiscoIdentity('pubsub', 'pep'))
+
+            return ns_features
+
+        for handler in self.parent.handlers:
+            if isinstance(handler, disco.DiscoHandler):
+                break
+
+        if not isinstance(handler, disco.DiscoHandler):
+            log.err("Can't find DiscoHandler")
+            return []
+
+        d = handler.info(requestor, target, '')
+        d.addCallback(gotInfos)
+        return d
+
+    def getDiscoItems(self, requestor, target, nodeIdentifier=''):
+        return []
+
+
+# we monkeypatch DiscoHandler to add delegation informations
+def _onDiscoItems(self, iq):
+    request = disco._DiscoRequest.fromElement(iq)
+    # it's really ugly to attach pep data to recipient
+    # but we don't have many options
+    request.recipient.pep = iq.delegated
+
+    def toResponse(items):
+        response = disco.DiscoItems()
+        response.nodeIdentifier = request.nodeIdentifier
+
+        for item in items:
+            response.append(item)
+
+        return response.toElement()
+
+    d = self.items(request.sender, request.recipient,
+                   request.nodeIdentifier)
+    d.addCallback(toResponse)
+    return d
+
+
+disco.DiscoHandler._onDiscoItems = _onDiscoItems