--- a/sat/core/constants.py	Thu Nov 12 14:53:15 2020 +0100
+++ b/sat/core/constants.py	Thu Nov 12 14:53:15 2020 +0100
@@ -330,6 +330,7 @@
     ## action constants ##
     META_TYPE_FILE = "file"
     META_TYPE_OVERWRITE = "overwrite"
+    META_TYPE_NOT_IN_ROSTER_LEAK = "not_in_roster_leak"
 
     ## HARD-CODED ACTIONS IDS (generated with uuid.uuid4) ##
     AUTHENTICATE_PROFILE_ID = "b03bbfa8-a4ae-4734-a248-06ce6c7cf562"

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sat/plugins/plugin_xep_0353.py	Thu Nov 12 14:53:15 2020 +0100
@@ -0,0 +1,226 @@
+#!/usr/bin/env python3
+
+# SàT plugin for Jingle Message Initiation (XEP-0353)
+# Copyright (C) 2009-2020 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 zope.interface import implementer
+from twisted.internet import defer
+from twisted.internet import reactor
+from twisted.words.protocols.jabber import xmlstream, jid
+from twisted.words.xish import domish
+from wokkel import disco, iwokkel
+from sat.core.i18n import _, D_
+from sat.core.constants import Const as C
+from sat.core import exceptions
+from sat.core.log import getLogger
+from sat.tools import utils
+from sat.tools import xml_tools
+
+log = getLogger(__name__)
+
+
+NS_JINGLE_MESSAGE = "urn:xmpp:jingle-message:0"
+
+PLUGIN_INFO = {
+    C.PI_NAME: "Jingle Message Initiation",
+    C.PI_IMPORT_NAME: "XEP-0353",
+    C.PI_TYPE: "XEP",
+    C.PI_MODES: C.PLUG_MODE_BOTH,
+    C.PI_PROTOCOLS: ["XEP-0353"],
+    C.PI_DEPENDENCIES: ["XEP-0166"],
+    C.PI_MAIN: "XEP_0353",
+    C.PI_HANDLER: "yes",
+    C.PI_DESCRIPTION: _("""Implementation of Jingle Message Initiation"""),
+}
+
+
+class XEP_0353(object):
+
+    def __init__(self, host):
+        log.info(_("plugin {name} initialization").format(name=PLUGIN_INFO[C.PI_NAME]))
+        self.host = host
+        host.registerNamespace("jingle-message", NS_JINGLE_MESSAGE)
+        self._j = host.plugins["XEP-0166"]
+        host.trigger.add("XEP-0166_initiate", self._onInitiateTrigger)
+        host.trigger.add("messageReceived", self._onMessageReceived)
+
+    def getHandler(self, client):
+        return Handler()
+
+    def profileConnecting(self, client):
+        # mapping from session id to deferred used to wait for destinee answer
+        client._xep_0353_pending_sessions = {}
+
+    def buildMessageData(self, client, peer_jid, verb, session_id):
+        mess_data = {
+            'from': client.jid,
+            'to': peer_jid,
+            'uid': '',
+            'message': {},
+            'type': C.MESS_TYPE_CHAT,
+            'subject': {},
+            'extra': {}
+        }
+        client.generateMessageXML(mess_data)
+        verb_elt = mess_data["xml"].addElement((NS_JINGLE_MESSAGE, verb))
+        verb_elt["id"] = session_id
+        return mess_data
+
+    async def _onInitiateTrigger(self, client, session, contents):
+        peer_jid = session['peer_jid']
+        if peer_jid.resource:
+            return True
+
+        if peer_jid.userhostJID() not in client.roster:
+            # if the contact is not in our roster, we need to send a directed presence
+            # according to XEP-0353 §3.1
+            await client.presence.available(peer_jid)
+
+        mess_data = self.buildMessageData(client, peer_jid, "propose", session['id'])
+        for content in contents:
+            application, app_args, app_kwargs, content_name = self._j.getContentData(
+                content)
+            try:
+                jingleDescriptionElt = application.handler.jingleDescriptionElt
+            except AttributeError:
+                log.debug(f"no jingleDescriptionElt set for {application.handler}")
+                description_elt = domish.Element((content["app_ns"], "description"))
+            else:
+                description_elt = await utils.asDeferred(
+                    jingleDescriptionElt,
+                    client, session, content_name, *app_args, **app_kwargs
+                )
+        mess_data["xml"].propose.addChild(description_elt)
+        response_d = defer.Deferred()
+        # we wait for 2 min before cancelling the session init
+        response_d.addTimeout(2*60, reactor)
+        client._xep_0353_pending_sessions[session['id']] = response_d
+        await client.sendMessageData(mess_data)
+        try:
+            accepting_jid = await response_d
+        except defer.TimeoutError:
+            log.warning(_(
+                "Message initiation with {peer_jid} timed out"
+            ).format(peer_jid=peer_jid))
+        else:
+            session["peer_jid"] = accepting_jid
+        del client._xep_0353_pending_sessions[session['id']]
+        return True
+
+    async def _onMessageReceived(self, client, message_elt, post_treat):
+        for elt in message_elt.elements():
+            if elt.uri == NS_JINGLE_MESSAGE:
+                if elt.name == "propose":
+                    return await self._handlePropose(client, message_elt, elt)
+                elif elt.name == "retract":
+                    return self._handleRetract(client, message_elt, elt)
+                elif elt.name == "proceed":
+                    return self._handleProceed(client, message_elt, elt)
+                elif elt.name == "accept":
+                    return self._handleAccept(client, message_elt, elt)
+                elif elt.name == "reject":
+                    return self._handleAccept(client, message_elt, elt)
+                else:
+                    log.warning(f"invalid element: {elt.toXml}")
+                    return True
+        return True
+
+    async def _handlePropose(self, client, message_elt, elt):
+        peer_jid = jid.JID(message_elt["from"])
+        session_id = elt["id"]
+        if peer_jid.userhostJID() not in client.roster:
+            app_ns = elt.description.uri
+            try:
+                application = self._j.getApplication(app_ns)
+                human_name = getattr(application.handler, "human_name", application.name)
+            except (exceptions.NotFound, AttributeError):
+                if app_ns.startswith("urn:xmpp:jingle:apps:"):
+                    human_name = app_ns[21:].split(":", 1)[0].replace('-', ' ').title()
+                else:
+                    splitted_ns = app_ns.split(':')
+                    if len(splitted_ns) > 1:
+                        human_name = splitted_ns[-2].replace('- ', ' ').title()
+                    else:
+                        human_name = app_ns
+
+            confirm_msg = D_(
+                "Somebody not in your contact list ({peer_jid}) wants to do a "
+                '"{human_name}" session with you, this would leak your presence and '
+                "possibly you IP (internet localisation), do you accept?"
+            ).format(peer_jid=peer_jid, human_name=human_name)
+            confirm_title = D_("Invitation from an unknown contact")
+            accept = await xml_tools.deferConfirm(
+                self.host, confirm_msg, confirm_title, profile=client.profile,
+                action_extra={
+                    "meta_type": C.META_TYPE_NOT_IN_ROSTER_LEAK,
+                    "meta_session_id": session_id,
+                    "meta_from_jid": peer_jid.full(),
+                }
+            )
+            if not accept:
+                mess_data = self.buildMessageData(
+                    client, client.jid.userhostJID(), "reject", session_id)
+                await client.sendMessageData(mess_data)
+                # we don't sent anything to sender, to avoid leaking presence
+                return False
+            else:
+                await client.presence.available(peer_jid)
+        session_id = elt["id"]
+        mess_data = self.buildMessageData(
+            client, client.jid.userhostJID(), "accept", session_id)
+        await client.sendMessageData(mess_data)
+        mess_data = self.buildMessageData(
+            client, peer_jid, "proceed", session_id)
+        await client.sendMessageData(mess_data)
+        return False
+
+    def _handleRetract(self, client, message_elt, proceed_elt):
+        log.warning("retract is not implemented yet")
+        return False
+
+    def _handleProceed(self, client, message_elt, proceed_elt):
+        try:
+            session_id = proceed_elt["id"]
+        except KeyError:
+            log.warning(f"invalid proceed element in message_elt: {message_elt}")
+            return True
+        try:
+            response_d = client._xep_0353_pending_sessions[session_id]
+        except KeyError:
+            log.warning(
+                _("no pending session found with id {session_id}, did it timed out?")
+                .format(session_id=session_id)
+            )
+            return True
+
+        response_d.callback(jid.JID(message_elt["from"]))
+        return False
+
+    def _handleAccept(self, client, message_elt, accept_elt):
+        pass
+
+    def _handleReject(self, client, message_elt, accept_elt):
+        pass
+
+
+@implementer(iwokkel.IDisco)
+class Handler(xmlstream.XMPPHandler):
+
+    def getDiscoInfo(self, requestor, target, nodeIdentifier=""):
+        return [disco.DiscoFeature(NS_JINGLE_MESSAGE)]
+
+    def getDiscoItems(self, requestor, target, nodeIdentifier=""):
+        return []