matrix-spec/specification/rooms/v6.rst

.. Copyright 2020 The Matrix.org Foundation C.I.C.
..
.. Licensed under the Apache License, Version 2.0 (the "License");
.. you may not use this file except in compliance with the License.
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..     http://www.apache.org/licenses/LICENSE-2.0
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.. distributed under the License is distributed on an "AS IS" BASIS,
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Room Version 6
==============

This room version builds on `version 5 <v5.html>`_ while changing various
authorization rules performed on events.

.. contents:: Table of Contents
.. sectnum::


Client considerations
---------------------

The redaction algorithm has changed from `room version 1 <v1.html>`_ to remove
all rules against events of type ``m.room.aliases``. Room versions 2, 3, 4, and
5 all use v1's redaction algorithm. The algorithm is otherwise unchanged.


Server implementation components
--------------------------------

.. WARNING::
   The information contained in this section is strictly for server implementors.
   Applications which use the Client-Server API are generally unaffected by the
   intricacies contained here. The section above regarding client considerations
   is the resource that Client-Server API use cases should reference.


Room version 6 makes the following alterations to algorithms described in `room version 5 <v5.html>`_.

Redactions
~~~~~~~~~~

As mentioned in the client considerations portion of this specification, all
special meaning has been removed for events of type ``m.room.aliases``. The
algorithm is otherwise unchanged.

Authorization rules for events
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Like redactions, all rules relating specifically to events of type ``m.room.aliases``
are removed. They must still pass authorization checks relating to state events.

Additionally, the authorization rules for events of type ``m.room.power_levels``
now include the content key ``notifications``. This new rule takes the place of the
rule which checks the ``events`` and ``users`` keys.

For completeness, the changes to the auth rules can be represented as follows:

.. code:: diff

     ...

    -If type is `m.room.aliases`:
    -
    -   a. If event has no `state_key`, reject.
    -   b. If sender's domain doesn't matches `state_key`, reject.
    -   c. Otherwise, allow.

     ...

     If type is `m.room.power_levels`:

     ...

    -  * For each entry being added, changed or removed in both the `events` and `users` keys:
    +  * For each entry being added, changed or removed in the `events`, `users`, and `notifications` keys:

        i. If the current value is higher than the `sender`'s current power level, reject.

        ii. If the new value is higher than the `sender`'s current power level, reject.

     ...


The remaining rules are the same as in `room version 3 <v3.html#authorization-rules-for-events>`_
(the last inherited room version to specify the authorization rules).

Canonical JSON
~~~~~~~~~~~~~~

Servers MUST strictly enforce the JSON format specified in the
`appendices <../appendices.html#canonical-json>`_. This translates to a 400 ``M_BAD_JSON`` error
on most endpoints, or discarding of events over federation. For example, the Federation API's
``/send`` endpoint would discard the event whereas the Client Server API's ``/send/{eventType}``
endpoint would return a ``M_BAD_JSON`` error.