Add file with random disconnected bits of spec of current federation api

drafts/erikj_federation.rst

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+Federation
+==========
+
+Constructing a new event
+------------------------
+
+**TODO**
+
+Signing and Hashes
+~~~~~~~~~~~~~~~~~~
+
+**TODO**
+
+Authorization
+-------------
+
+When receiving new events from remote servers, or creating new events, a server 
+must know whether that event is allowed by the authorization rules. These rules
+depend solely on the state at that event. The types of state events that affect
+authorization are:
+
+- ``m.room.member``
+- ``m.room.join_rules``
+- ``m.room.power_levels``
+
+Servers should not create new events that reference unauthorized events. 
+However, any event that does reference an unauthorized event is not itself
+automatically considered unauthorized. 
+
+Unauthorized events that appear in the event graph do *not* have any effect on 
+the state of the graph. 
+
+.. Note:: This is in contrast to redacted events which can still affect the 
+          state of the graph. For example, a redacted *"join"* event will still
+          result in the user being considered joined.
+          
+
+Rules
+~~~~~
+
+The following are the rules to determine if an event is authorized (this does
+include validation).
+
+1. If type is ``m.room.create`` allow.
+#. If type is ``m.room.member``:
+  
+   a. If ``membership`` is ``join``:
+    
+      i. If the previous event is an ``m.room.create``, the depth is 1 and 
+         the ``state_key`` is the creator, then allow.
+      #. If the ``state_key`` does not match ``sender`` key, reject.
+      #. If the current state has ``membership`` set to ``join``.
+      #. If the ``sender`` is in the ``m.room.may_join`` list. [Not currently 
+         implemented]
+      #. If the ``join_rules`` is:
+      
+         - ``public``:  allow.
+         - ``invite``: allow if the current state has ``membership`` set to 
+           ``invite``
+         - ``knock``: **TODO**.
+         - ``private``: Reject.
+         
+      #. Reject
+
+   #. If ``membership`` is ``invite`` then allow if ``sender`` is in room, 
+      otherwise reject.
+   #. If ``membership`` is ``leave``:
+   
+      i. If ``sender`` matches ``state_key`` allow.
+      #. If ``sender``'s power level is greater than the the ``kick_level``
+         given in the current ``m.room.power_levels`` state (defaults to 50),
+         and the ``state_key``'s power level is less than or equal to the
+         ``sender``'s power level, then allow.
+      #. Reject.
+      
+   #. If ``membership`` is ``ban``:
+   
+      i. **TODO**.
+   
+   #. Reject.
+
+#. Reject the event if the event type's required power level is less that the
+   ``sender``'s power level.
+#. If the ``sender`` is not in the room, reject.
+#. If the type is ``m.room.power_levels``:
+
+   a. **TODO**.
+
+#. Allow.
+   
+   
+Definitions
+~~~~~~~~~~~
+
+Required Power Level
+  A given event type has an associated *required power level*. This is given
+  by the current ``m.room.power_levels`` event, it is either listed explicitly
+  in the ``events`` section or given by either ``state_default`` or 
+  ``events_default`` depending on if the event type is a state event or not.
+  
+
+
+
+Appendix
+========