--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sat/plugins/plugin_xep_0352.py	Mon Mar 25 07:08:23 2019 +0100
@@ -0,0 +1,76 @@
+#!/usr/bin/env python2
+# -*- coding: utf-8 -*-
+
+# SAT plugin for Explicit Message Encryption
+# Copyright (C) 2009-2019 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 twisted.words.xish import domish
+from sat.core.i18n import _, D_
+from sat.core.constants import Const as C
+from sat.core.log import getLogger
+
+log = getLogger(__name__)
+
+PLUGIN_INFO = {
+    C.PI_NAME: u"Client State Indication",
+    C.PI_IMPORT_NAME: u"XEP-0352",
+    C.PI_TYPE: C.PLUG_TYPE_XEP,
+    C.PI_PROTOCOLS: [u"XEP-0352"],
+    C.PI_DEPENDENCIES: [],
+    C.PI_MAIN: u"XEP_0352",
+    C.PI_HANDLER: u"no",
+    C.PI_DESCRIPTION: D_(u"Notify server when frontend is not actively used, to limit "
+                         u"traffic and save bandwidth and battery life"),
+}
+
+NS_CSI = u"urn:xmpp:csi:0"
+
+
+class XEP_0352(object):
+
+    def __init__(self, host):
+        log.info(_(u"Client State Indication plugin initialization"))
+        self.host = host
+        host.registerNamespace(u"csi", NS_CSI)
+
+    def isActive(self, client):
+        if not client._xep_0352_enabled:
+            return True
+        return client._xep_0352_active
+
+    def profileConnected(self, client):
+        if (NS_CSI, u'csi') in client.xmlstream.features:
+            log.info(_(u"Client State Indication is available on this server"))
+            client._xep_0352_enabled = True
+            client._xep_0352_active = True
+        else:
+            log.warning(_(u"Client State Indication is not available on this server, some"
+                          u" bandwidth optimisations can't be used."))
+            client._xep_0352_enabled = False
+
+    def setInactive(self, client):
+        if self.isActive(client):
+            inactive_elt = domish.Element((NS_CSI, u'inactive'))
+            client.send(inactive_elt)
+            client._xep_0352_active = False
+            log.info(u"inactive state set")
+
+    def setActive(self, client):
+        if not self.isActive(client):
+            active_elt = domish.Element((NS_CSI, u'active'))
+            client.send(active_elt)
+            client._xep_0352_active = True
+            log.info(u"active state set")