--- a/sat/plugins/plugin_xep_0363.py	Wed Jul 31 11:31:22 2019 +0200
+++ b/sat/plugins/plugin_xep_0363.py	Tue Aug 13 19:08:41 2019 +0200
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
 # SAT plugin for HTTP File Upload (XEP-0363)
@@ -24,7 +24,7 @@
 log = getLogger(__name__)
 from sat.core import exceptions
 from wokkel import disco, iwokkel
-from zope.interface import implements
+from zope.interface import implementer
 from twisted.words.protocols.jabber import jid
 from twisted.words.protocols.jabber.xmlstream import XMPPHandler
 from twisted.internet import reactor
@@ -50,7 +50,7 @@
     C.PI_DEPENDENCIES: ["FILE", "UPLOAD"],
     C.PI_MAIN: "XEP_0363",
     C.PI_HANDLER: "yes",
-    C.PI_DESCRIPTION: _(u"""Implementation of HTTP File Upload"""),
+    C.PI_DESCRIPTION: _("""Implementation of HTTP File Upload"""),
 }
 
 NS_HTTP_UPLOAD = "urn:xmpp:http:upload:0"
@@ -82,7 +82,7 @@
 
     def creatorForNetloc(self, hostname, port):
         log.warning(
-            u"TLS check disabled for {host} on port {port}".format(
+            "TLS check disabled for {host} on port {port}".format(
                 host=hostname, port=port
             )
         )
@@ -107,10 +107,10 @@
             in_sign="sisss",
             out_sign="(ss)",
             method=self._getSlot,
-            async=True,
+            async_=True,
         )
         host.plugins["UPLOAD"].register(
-            u"HTTP Upload", self.getHTTPUploadEntity, self.fileHTTPUpload
+            "HTTP Upload", self.getHTTPUploadEntity, self.fileHTTPUpload
         )
 
     def getHandler(self, client):
@@ -131,12 +131,12 @@
         except AttributeError:
             found_entities = yield self.host.findFeaturesSet(client, (NS_HTTP_UPLOAD,))
             try:
-                entity = client.http_upload_service = iter(found_entities).next()
+                entity = client.http_upload_service = next(iter(found_entities))
             except StopIteration:
                 entity = client.http_upload_service = None
 
         if entity is None:
-            raise failure.Failure(exceptions.NotFound(u"No HTTP upload entity found"))
+            raise failure.Failure(exceptions.NotFound("No HTTP upload entity found"))
 
         defer.returnValue(entity)
 
@@ -187,7 +187,7 @@
 
     def _getSlotEb(self, fail, client, progress_id_d, download_d):
         """an error happened while trying to get slot"""
-        log.warning(u"Can't get upload slot: {reason}".format(reason=fail.value))
+        log.warning("Can't get upload slot: {reason}".format(reason=fail.value))
         progress_id_d.errback(fail)
         download_d.errback(fail)
 
@@ -204,7 +204,7 @@
         @param ignore_tls_errors(bool): ignore TLS certificate is True
         @return (tuple
         """
-        log.debug(u"Got upload slot: {}".format(slot))
+        log.debug("Got upload slot: {}".format(slot))
         sat_file = self.host.plugins["FILE"].File(
             self.host, client, path, size=size, auto_end_signals=False
         )
@@ -243,7 +243,7 @@
             should be closed, be is needed to send the progressFinished signal
         @param slot(Slot): put/get urls
         """
-        log.info(u"HTTP upload finished")
+        log.info("HTTP upload finished")
         sat_file.progressFinished({"url": slot.get})
         download_d.callback(slot.get)
 
@@ -257,15 +257,15 @@
         try:
             wrapped_fail = fail.value.reasons[0]
         except (AttributeError, IndexError) as e:
-            log.warning(_(u"upload failed: {reason}").format(reason=e))
-            sat_file.progressError(unicode(fail))
+            log.warning(_("upload failed: {reason}").format(reason=e))
+            sat_file.progressError(str(fail))
             raise fail
         else:
             if wrapped_fail.check(SSL.Error):
-                msg = u"TLS validation error, can't connect to HTTPS server"
+                msg = "TLS validation error, can't connect to HTTPS server"
             else:
-                msg = u"can't upload file"
-            log.warning(msg + ": " + unicode(wrapped_fail.value))
+                msg = "can't upload file"
+            log.warning(msg + ": " + str(wrapped_fail.value))
             sat_file.progressError(msg)
 
     def _gotSlot(self, iq_elt, client):
@@ -275,26 +275,26 @@
         @param iq_elt(domish.Element): <IQ/> result as specified in XEP-0363
         """
         try:
-            slot_elt = iq_elt.elements(NS_HTTP_UPLOAD, "slot").next()
-            put_elt = slot_elt.elements(NS_HTTP_UPLOAD, "put").next()
+            slot_elt = next(iq_elt.elements(NS_HTTP_UPLOAD, "slot"))
+            put_elt = next(slot_elt.elements(NS_HTTP_UPLOAD, "put"))
             put_url = put_elt['url']
-            get_elt = slot_elt.elements(NS_HTTP_UPLOAD, "get").next()
+            get_elt = next(slot_elt.elements(NS_HTTP_UPLOAD, "get"))
             get_url = get_elt['url']
         except (StopIteration, KeyError):
-            raise exceptions.DataError(u"Incorrect stanza received from server")
+            raise exceptions.DataError("Incorrect stanza received from server")
         headers = []
         for header_elt in put_elt.elements(NS_HTTP_UPLOAD, "header"):
             try:
                 name = header_elt["name"]
-                value = unicode(header_elt)
+                value = str(header_elt)
             except KeyError:
-                log.warning(_(u"Invalid header element: {xml}").format(
+                log.warning(_("Invalid header element: {xml}").format(
                     iq_elt.toXml()))
                 continue
             name = name.replace('\n', '')
             value = value.replace('\n', '')
             if name.lower() not in ALLOWED_HEADERS:
-                log.warning(_(u'Ignoring unauthorised header "{name}": {xml}')
+                log.warning(_('Ignoring unauthorised header "{name}": {xml}')
                     .format(name=name, xml = iq_elt.toXml()))
                 continue
             headers.append((name, value))
@@ -351,14 +351,14 @@
             else:
                 if upload_jid is None:
                     raise failure.Failure(
-                        exceptions.NotFound(u"No HTTP upload entity found")
+                        exceptions.NotFound("No HTTP upload entity found")
                     )
 
         iq_elt = client.IQ("get")
         iq_elt["to"] = upload_jid.full()
         request_elt = iq_elt.addElement((NS_HTTP_UPLOAD, "request"))
         request_elt["filename"] = filename
-        request_elt["size"] = unicode(size)
+        request_elt["size"] = str(size)
         if content_type is not None:
             request_elt["content-type"] = content_type
 
@@ -368,8 +368,8 @@
         return d
 
 
+@implementer(iwokkel.IDisco)
 class XEP_0363_handler(XMPPHandler):
-    implements(iwokkel.IDisco)
 
     def getDiscoInfo(self, requestor, target, nodeIdentifier=""):
         return [disco.DiscoFeature(NS_HTTP_UPLOAD)]