--- a/sat/plugins/plugin_xep_0077.py	Sun Mar 03 17:17:07 2019 +0100
+++ b/sat/plugins/plugin_xep_0077.py	Sun Mar 03 19:18:45 2019 +0100
@@ -23,7 +23,7 @@
 from sat.core.log import getLogger
 
 log = getLogger(__name__)
-from twisted.words.protocols.jabber import jid, xmlstream, client
+from twisted.words.protocols.jabber import jid, xmlstream, client, error as jabber_error
 from twisted.internet import defer, reactor
 from sat.tools import xml_tools
 
@@ -50,12 +50,13 @@
     # FIXME: doesn't handle data form or oob
     namespace = 'jabber:client'
 
-    def __init__(self, jid_, password, email=None):
+    def __init__(self, jid_, password, email=None, check_certificate=True):
         log.debug(_(u"Registration asked for {jid}").format(jid=jid_))
         xmlstream.ConnectAuthenticator.__init__(self, jid_.host)
         self.jid = jid_
         self.password = password
         self.email = email
+        self.check_certificate = check_certificate
         self.registered = defer.Deferred()
 
     def associateWithStream(self, xs):
@@ -63,13 +64,10 @@
         xs.addObserver(xmlstream.STREAM_AUTHD_EVENT, self.register)
 
         xs.initializers = [client.CheckVersionInitializer(xs)]
-        inits = [ (xmlstream.TLSInitiatingInitializer, False),
-                ]
-
-        for initClass, required in inits:
-            init = initClass(xs)
-            init.required = required
-            xs.initializers.append(init)
+        tls_init = xmlstream.TLSInitiatingInitializer(xs)
+        tls_init.required = False
+        tls_init.check_certificate = self.check_certificate
+        xs.initializers.append(tls_init)
 
     def register(self, xmlstream):
         log.debug(_(u"Stream started with {server}, now registering"
@@ -88,6 +86,26 @@
         raise failure_
 
 
+class ServerRegister(xmlstream.XmlStreamFactory):
+
+    def __init__(self, *args, **kwargs):
+        xmlstream.XmlStreamFactory.__init__(self, *args, **kwargs)
+        self.addBootstrap(xmlstream.STREAM_END_EVENT, self._disconnected)
+
+    def clientConnectionLost(self, connector, reason):
+        connector.disconnect()
+
+    def _disconnected(self, reason):
+        if not self.authenticator.registered.called:
+            err = jabber_error.StreamError(u"Server unexpectedly closed the connection")
+            try:
+                if reason.value.args[0][0][2] == "certificate verify failed":
+                    err = exceptions.InvalidCertificate()
+            except (IndexError, TypeError):
+                pass
+            self.authenticator.registered.errback(err)
+
+
 class XEP_0077(object):
     def __init__(self, host):
         log.info(_("Plugin XEP_0077 initialization"))
@@ -237,11 +255,12 @@
         @param host(unicode): host of the server to register to
         @param port(int): port of the server to register to
         """
-        authenticator = RegisteringAuthenticator(jid_, password, email)
+        check_certificate = host != u"127.0.0.1"
+        authenticator = RegisteringAuthenticator(
+            jid_, password, email, check_certificate=check_certificate)
         registered_d = authenticator.registered
-        serverRegistrer = xmlstream.XmlStreamFactory(authenticator)
-        connector = reactor.connectTCP(host, port, serverRegistrer)
-        serverRegistrer.clientConnectionLost = lambda conn, reason: connector.disconnect()
+        server_register = ServerRegister(authenticator)
+        reactor.connectTCP(host, port, server_register)
         return registered_d
 
     def _changePassword(self, new_password, profile_key):