--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libervia/backend/plugins/plugin_xep_0047.py	Fri Jun 02 11:49:51 2023 +0200
@@ -0,0 +1,385 @@
+#!/usr/bin/env python3
+
+
+# SAT plugin for managing gateways (xep-0047)
+# Copyright (C) 2009-2021 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 libervia.backend.core.i18n import _
+from libervia.backend.core.log import getLogger
+
+log = getLogger(__name__)
+from libervia.backend.core.constants import Const as C
+from libervia.backend.core import exceptions
+from twisted.words.protocols.jabber import jid
+from twisted.words.protocols.jabber import xmlstream
+from twisted.words.protocols.jabber import error
+from twisted.internet import reactor
+from twisted.internet import defer
+from twisted.python import failure
+
+from wokkel import disco, iwokkel
+
+from zope.interface import implementer
+
+import base64
+
+try:
+    from twisted.words.protocols.xmlstream import XMPPHandler
+except ImportError:
+    from wokkel.subprotocols import XMPPHandler
+
+MESSAGE = "/message"
+IQ_SET = '/iq[@type="set"]'
+NS_IBB = "http://jabber.org/protocol/ibb"
+IBB_OPEN = IQ_SET + '/open[@xmlns="' + NS_IBB + '"]'
+IBB_CLOSE = IQ_SET + '/close[@xmlns="' + NS_IBB + '" and @sid="{}"]'
+IBB_IQ_DATA = IQ_SET + '/data[@xmlns="' + NS_IBB + '" and @sid="{}"]'
+IBB_MESSAGE_DATA = MESSAGE + '/data[@xmlns="' + NS_IBB + '" and @sid="{}"]'
+TIMEOUT = 120  # timeout for workflow
+DEFER_KEY = "finished"  # key of the deferred used to track session end
+
+PLUGIN_INFO = {
+    C.PI_NAME: "In-Band Bytestream Plugin",
+    C.PI_IMPORT_NAME: "XEP-0047",
+    C.PI_TYPE: "XEP",
+    C.PI_MODES: C.PLUG_MODE_BOTH,
+    C.PI_PROTOCOLS: ["XEP-0047"],
+    C.PI_MAIN: "XEP_0047",
+    C.PI_HANDLER: "yes",
+    C.PI_DESCRIPTION: _("""Implementation of In-Band Bytestreams"""),
+}
+
+
+class XEP_0047(object):
+    NAMESPACE = NS_IBB
+    BLOCK_SIZE = 4096
+
+    def __init__(self, host):
+        log.info(_("In-Band Bytestreams plugin initialization"))
+        self.host = host
+
+    def get_handler(self, client):
+        return XEP_0047_handler(self)
+
+    def profile_connected(self, client):
+        client.xep_0047_current_stream = {}  # key: stream_id, value: data(dict)
+
+    def _time_out(self, sid, client):
+        """Delete current_stream id, called after timeout
+
+        @param sid(unicode): session id of client.xep_0047_current_stream
+        @param client: %(doc_client)s
+        """
+        log.info(
+            "In-Band Bytestream: TimeOut reached for id {sid} [{profile}]".format(
+                sid=sid, profile=client.profile
+            )
+        )
+        self._kill_session(sid, client, "TIMEOUT")
+
+    def _kill_session(self, sid, client, failure_reason=None):
+        """Delete a current_stream id, clean up associated observers
+
+        @param sid(unicode): session id
+        @param client: %(doc_client)s
+        @param failure_reason(None, unicode): if None the session is successful
+            else, will be used to call failure_cb
+        """
+        try:
+            session = client.xep_0047_current_stream[sid]
+        except KeyError:
+            log.warning("kill id called on a non existant id")
+            return
+
+        try:
+            observer_cb = session["observer_cb"]
+        except KeyError:
+            pass
+        else:
+            client.xmlstream.removeObserver(session["event_data"], observer_cb)
+
+        if session["timer"].active():
+            session["timer"].cancel()
+
+        del client.xep_0047_current_stream[sid]
+
+        success = failure_reason is None
+        stream_d = session[DEFER_KEY]
+
+        if success:
+            stream_d.callback(None)
+        else:
+            stream_d.errback(failure.Failure(exceptions.DataError(failure_reason)))
+
+    def create_session(self, *args, **kwargs):
+        """like [_create_session] but return the session deferred instead of the whole session
+
+        session deferred is fired when transfer is finished
+        """
+        return self._create_session(*args, **kwargs)[DEFER_KEY]
+
+    def _create_session(self, client, stream_object, local_jid, to_jid, sid):
+        """Called when a bytestream is imminent
+
+        @param stream_object(IConsumer): stream object where data will be written
+        @param local_jid(jid.JID): same as [start_stream]
+        @param to_jid(jid.JId): jid of the other peer
+        @param sid(unicode): session id
+        @return (dict): session data
+        """
+        if sid in client.xep_0047_current_stream:
+            raise exceptions.ConflictError("A session with this id already exists !")
+        session_data = client.xep_0047_current_stream[sid] = {
+            "id": sid,
+            DEFER_KEY: defer.Deferred(),
+            "local_jid": local_jid,
+            "to": to_jid,
+            "stream_object": stream_object,
+            "seq": -1,
+            "timer": reactor.callLater(TIMEOUT, self._time_out, sid, client),
+        }
+
+        return session_data
+
+    def _on_ibb_open(self, iq_elt, client):
+        """"Called when an IBB <open> element is received
+
+        @param iq_elt(domish.Element): the whole <iq> stanza
+        """
+        log.debug(_("IBB stream opening"))
+        iq_elt.handled = True
+        open_elt = next(iq_elt.elements(NS_IBB, "open"))
+        block_size = open_elt.getAttribute("block-size")
+        sid = open_elt.getAttribute("sid")
+        stanza = open_elt.getAttribute("stanza", "iq")
+        if not sid or not block_size or int(block_size) > 65535:
+            return self._sendError("not-acceptable", sid or None, iq_elt, client)
+        if not sid in client.xep_0047_current_stream:
+            log.warning(_("Ignoring unexpected IBB transfer: %s" % sid))
+            return self._sendError("not-acceptable", sid or None, iq_elt, client)
+        session_data = client.xep_0047_current_stream[sid]
+        if session_data["to"] != jid.JID(iq_elt["from"]):
+            log.warning(
+                _("sended jid inconsistency (man in the middle attack attempt ?)")
+            )
+            return self._sendError("not-acceptable", sid, iq_elt, client)
+
+        # at this stage, the session looks ok and will be accepted
+
+        # we reset the timeout:
+        session_data["timer"].reset(TIMEOUT)
+
+        # we save the xmlstream, events and observer data to allow observer removal
+        session_data["event_data"] = event_data = (
+            IBB_MESSAGE_DATA if stanza == "message" else IBB_IQ_DATA
+        ).format(sid)
+        session_data["observer_cb"] = observer_cb = self._on_ibb_data
+        event_close = IBB_CLOSE.format(sid)
+        # we now set the stream observer to look after data packet
+        # FIXME: if we never get the events, the observers stay.
+        #        would be better to have generic observer and check id once triggered
+        client.xmlstream.addObserver(event_data, observer_cb, client=client)
+        client.xmlstream.addOnetimeObserver(event_close, self._on_ibb_close, client=client)
+        # finally, we send the accept stanza
+        iq_result_elt = xmlstream.toResponse(iq_elt, "result")
+        client.send(iq_result_elt)
+
+    def _on_ibb_close(self, iq_elt, client):
+        """"Called when an IBB <close> element is received
+
+        @param iq_elt(domish.Element): the whole <iq> stanza
+        """
+        iq_elt.handled = True
+        log.debug(_("IBB stream closing"))
+        close_elt = next(iq_elt.elements(NS_IBB, "close"))
+        # XXX: this observer is only triggered on valid sid, so we don't need to check it
+        sid = close_elt["sid"]
+
+        iq_result_elt = xmlstream.toResponse(iq_elt, "result")
+        client.send(iq_result_elt)
+        self._kill_session(sid, client)
+
+    def _on_ibb_data(self, element, client):
+        """Observer called on <iq> or <message> stanzas with data element
+
+        Manage the data elelement (check validity and write to the stream_object)
+        @param element(domish.Element): <iq> or <message> stanza
+        """
+        element.handled = True
+        data_elt = next(element.elements(NS_IBB, "data"))
+        sid = data_elt["sid"]
+
+        try:
+            session_data = client.xep_0047_current_stream[sid]
+        except KeyError:
+            log.warning(_("Received data for an unknown session id"))
+            return self._sendError("item-not-found", None, element, client)
+
+        from_jid = session_data["to"]
+        stream_object = session_data["stream_object"]
+
+        if from_jid.full() != element["from"]:
+            log.warning(
+                _(
+                    "sended jid inconsistency (man in the middle attack attempt ?)\ninitial={initial}\ngiven={given}"
+                ).format(initial=from_jid, given=element["from"])
+            )
+            if element.name == "iq":
+                self._sendError("not-acceptable", sid, element, client)
+            return
+
+        session_data["seq"] = (session_data["seq"] + 1) % 65535
+        if int(data_elt.getAttribute("seq", -1)) != session_data["seq"]:
+            log.warning(_("Sequence error"))
+            if element.name == "iq":
+                reason = "not-acceptable"
+                self._sendError(reason, sid, element, client)
+            self.terminate_stream(session_data, client, reason)
+            return
+
+        # we reset the timeout:
+        session_data["timer"].reset(TIMEOUT)
+
+        # we can now decode the data
+        try:
+            stream_object.write(base64.b64decode(str(data_elt)))
+        except TypeError:
+            # The base64 data is invalid
+            log.warning(_("Invalid base64 data"))
+            if element.name == "iq":
+                self._sendError("not-acceptable", sid, element, client)
+            self.terminate_stream(session_data, client, reason)
+            return
+
+        # we can now ack success
+        if element.name == "iq":
+            iq_result_elt = xmlstream.toResponse(element, "result")
+            client.send(iq_result_elt)
+
+    def _sendError(self, error_condition, sid, iq_elt, client):
+        """Send error stanza
+
+        @param error_condition: one of twisted.words.protocols.jabber.error.STANZA_CONDITIONS keys
+        @param sid(unicode,None): jingle session id, or None, if session must not be destroyed
+        @param iq_elt(domish.Element): full <iq> stanza
+        @param client: %(doc_client)s
+        """
+        iq_elt = error.StanzaError(error_condition).toResponse(iq_elt)
+        log.warning(
+            "Error while managing in-band bytestream session, cancelling: {}".format(
+                error_condition
+            )
+        )
+        if sid is not None:
+            self._kill_session(sid, client, error_condition)
+        client.send(iq_elt)
+
+    def start_stream(self, client, stream_object, local_jid, to_jid, sid, block_size=None):
+        """Launch the stream workflow
+
+        @param stream_object(ifaces.IStreamProducer): stream object to send
+        @param local_jid(jid.JID): jid to use as local jid
+            This is needed for client which can be addressed with a different jid than
+            client.jid if a local part is used (e.g. piotr@file.example.net where
+            client.jid would be file.example.net)
+        @param to_jid(jid.JID): JID of the recipient
+        @param sid(unicode): Stream session id
+        @param block_size(int, None): size of the block (or None for default)
+        """
+        session_data = self._create_session(client, stream_object, local_jid, to_jid, sid)
+
+        if block_size is None:
+            block_size = XEP_0047.BLOCK_SIZE
+        assert block_size <= 65535
+        session_data["block_size"] = block_size
+
+        iq_elt = client.IQ()
+        iq_elt["from"] = local_jid.full()
+        iq_elt["to"] = to_jid.full()
+        open_elt = iq_elt.addElement((NS_IBB, "open"))
+        open_elt["block-size"] = str(block_size)
+        open_elt["sid"] = sid
+        open_elt["stanza"] = "iq"  # TODO: manage <message> stanza ?
+        args = [session_data, client]
+        d = iq_elt.send()
+        d.addCallbacks(self._iq_data_stream_cb, self._iq_data_stream_eb, args, None, args)
+        return session_data[DEFER_KEY]
+
+    def _iq_data_stream_cb(self, iq_elt, session_data, client):
+        """Called during the whole data streaming
+
+        @param iq_elt(domish.Element): iq result
+        @param session_data(dict): data of this streaming session
+        @param client: %(doc_client)s
+        """
+        session_data["timer"].reset(TIMEOUT)
+
+        # FIXME: producer/consumer mechanism is not used properly here
+        buffer_ = session_data["stream_object"].file_obj.read(session_data["block_size"])
+        if buffer_:
+            next_iq_elt = client.IQ()
+            next_iq_elt["from"] = session_data["local_jid"].full()
+            next_iq_elt["to"] = session_data["to"].full()
+            data_elt = next_iq_elt.addElement((NS_IBB, "data"))
+            seq = session_data["seq"] = (session_data["seq"] + 1) % 65535
+            data_elt["seq"] = str(seq)
+            data_elt["sid"] = session_data["id"]
+            data_elt.addContent(base64.b64encode(buffer_).decode())
+            args = [session_data, client]
+            d = next_iq_elt.send()
+            d.addCallbacks(self._iq_data_stream_cb, self._iq_data_stream_eb, args, None, args)
+        else:
+            self.terminate_stream(session_data, client)
+
+    def _iq_data_stream_eb(self, failure, session_data, client):
+        if failure.check(error.StanzaError):
+            log.warning("IBB transfer failed: {}".format(failure.value))
+        else:
+            log.error("IBB transfer failed: {}".format(failure.value))
+        self.terminate_stream(session_data, client, "IQ_ERROR")
+
+    def terminate_stream(self, session_data, client, failure_reason=None):
+        """Terminate the stream session
+
+        @param session_data(dict): data of this streaming session
+        @param client: %(doc_client)s
+        @param failure_reason(unicode, None): reason of the failure, or None if steam was successful
+        """
+        iq_elt = client.IQ()
+        iq_elt["from"] = session_data["local_jid"].full()
+        iq_elt["to"] = session_data["to"].full()
+        close_elt = iq_elt.addElement((NS_IBB, "close"))
+        close_elt["sid"] = session_data["id"]
+        iq_elt.send()
+        self._kill_session(session_data["id"], client, failure_reason)
+
+
+@implementer(iwokkel.IDisco)
+class XEP_0047_handler(XMPPHandler):
+
+    def __init__(self, parent):
+        self.plugin_parent = parent
+
+    def connectionInitialized(self):
+        self.xmlstream.addObserver(
+            IBB_OPEN, self.plugin_parent._on_ibb_open, client=self.parent
+        )
+
+    def getDiscoInfo(self, requestor, target, nodeIdentifier=""):
+        return [disco.DiscoFeature(NS_IBB)]
+
+    def getDiscoItems(self, requestor, target, nodeIdentifier=""):
+        return []