Finish implementing the new join dance.

synapse/api/auth.py

@@ -48,6 +48,15 @@ class Auth(object):
         """
         try:
             if hasattr(event, "room_id"):
+                if not event.old_state_events:
+                    # Oh, we don't know what the state of the room was, so we
+                    # are trusting that this is allowed (at least for now)
+                    defer.returnValue(True)
+
+                if hasattr(event, "outlier") and event.outlier:
+                    # TODO (erikj): Auth for outliers is done differently.
+                    defer.returnValue(True)
+
                 is_state = hasattr(event, "state_key")
 
                 if event.type == RoomMemberEvent.TYPE:

synapse/api/events/factory.py

@@ -51,12 +51,20 @@ class EventFactory(object):
         self.clock = hs.get_clock()
         self.hs = hs
 
+        self.event_id_count = 0
+
+    def create_event_id(self):
+        i = str(self.event_id_count)
+        self.event_id_count += 1
+
+        local_part = str(int(self.clock.time())) + i + random_string(5)
+
+        return "%s@%s" % (local_part, self.hs.hostname)
+
     def create_event(self, etype=None, **kwargs):
         kwargs["type"] = etype
         if "event_id" not in kwargs:
-            kwargs["event_id"] = "%s@%s" % (
-                random_string(10), self.hs.hostname
-            )
+            kwargs["event_id"] = self.create_event_id()
 
         if "ts" not in kwargs:
             kwargs["ts"] = int(self.clock.time_msec())