* Allow room creator to send MSC2716 related events in existing room versions

Discussed at https://github.com/matrix-org/matrix-doc/pull/2716/#discussion_r682474869

Restoring `get_create_event_for_room_txn` from,
https://github.com/matrix-org/synapse/pull/10245/commits/44bb3f0cf5cb365ef9281554daceeecfb17cc94d

* Add changelog

* Stop people from trying to redact MSC2716 events in unsupported room versions

* Populate rooms.creator column for easy lookup

> From some [out of band discussion](https://matrix.to/#/!UytJQHLQYfvYWsGrGY:jki.re/$p2fKESoFst038x6pOOmsY0C49S2gLKMr0jhNMz_JJz0?via=jki.re&via=matrix.org), my plan is to use `rooms.creator`. But currently, we don't fill in `creator` for remote rooms when a user is invited to a room for example. So we need to add some code to fill in `creator` wherever we add to the `rooms` table. And also add a background update to fill in the rows missing `creator` (we can use the same logic that `get_create_event_for_room_txn` is doing by looking in the state events to get the `creator`).
>
> https://github.com/matrix-org/synapse/pull/10566#issuecomment-901616642

* Remove and switch away from get_create_event_for_room_txn

* Fix no create event being found because no state events persisted yet

* Fix and add tests for rooms creator bg update

* Populate rooms.creator field for easy lookup

Part of https://github.com/matrix-org/synapse/pull/10566

 - Fill in creator whenever we insert into the rooms table
 - Add background update to backfill any missing creator values

* Add changelog

* Fix usage

* Remove extra delta already included in #10697

* Don't worry about setting creator for invite

* Only iterate over rows missing the creator

See https://github.com/matrix-org/synapse/pull/10697#discussion_r695940898

* Use constant to fetch room creator field

See https://github.com/matrix-org/synapse/pull/10697#discussion_r696803029

* More protection from other random types

See https://github.com/matrix-org/synapse/pull/10697#discussion_r696806853

* Move new background update to end of list

See https://github.com/matrix-org/synapse/pull/10697#discussion_r696814181

* Fix query casing

* Fix ambiguity iterating over cursor instead of list

Fix `psycopg2.ProgrammingError: no results to fetch` error
when tests run with Postgres.

```
SYNAPSE_POSTGRES=1 SYNAPSE_TEST_LOG_LEVEL=INFO python -m twisted.trial tests.storage.databases.main.test_room
```

---

We use `txn.fetchall` because it will return the results as a
list or an empty list when there are no results.

Docs:

> `cursor` objects are iterable, so, instead of calling explicitly fetchone() in a loop, the object itself can be used:
>
> https://www.psycopg.org/docs/cursor.html#cursor-iterable

And I'm guessing iterating over a raw cursor does something weird when there are no results.

---

Test CI failure: https://github.com/matrix-org/synapse/pull/10697/checks?check_run_id=3468916530
```
tests.test_visibility.FilterEventsForServerTestCase.test_large_room
===============================================================================
[FAIL]
Traceback (most recent call last):
  File "/home/runner/work/synapse/synapse/tests/storage/databases/main/test_room.py", line 85, in test_background_populate_rooms_creator_column
    self.get_success(
  File "/home/runner/work/synapse/synapse/tests/unittest.py", line 500, in get_success
    return self.successResultOf(d)
  File "/home/runner/work/synapse/synapse/.tox/py/lib/python3.9/site-packages/twisted/trial/_synctest.py", line 700, in successResultOf
    self.fail(
twisted.trial.unittest.FailTest: Success result expected on <Deferred at 0x7f4022f3eb50 current result: None>, found failure result instead:
Traceback (most recent call last):
  File "/home/runner/work/synapse/synapse/.tox/py/lib/python3.9/site-packages/twisted/internet/defer.py", line 701, in errback
    self._startRunCallbacks(fail)
  File "/home/runner/work/synapse/synapse/.tox/py/lib/python3.9/site-packages/twisted/internet/defer.py", line 764, in _startRunCallbacks
    self._runCallbacks()
  File "/home/runner/work/synapse/synapse/.tox/py/lib/python3.9/site-packages/twisted/internet/defer.py", line 858, in _runCallbacks
    current.result = callback(  # type: ignore[misc]
  File "/home/runner/work/synapse/synapse/.tox/py/lib/python3.9/site-packages/twisted/internet/defer.py", line 1751, in gotResult
    current_context.run(_inlineCallbacks, r, gen, status)
--- <exception caught here> ---
  File "/home/runner/work/synapse/synapse/.tox/py/lib/python3.9/site-packages/twisted/internet/defer.py", line 1657, in _inlineCallbacks
    result = current_context.run(
  File "/home/runner/work/synapse/synapse/.tox/py/lib/python3.9/site-packages/twisted/python/failure.py", line 500, in throwExceptionIntoGenerator
    return g.throw(self.type, self.value, self.tb)
  File "/home/runner/work/synapse/synapse/synapse/storage/background_updates.py", line 224, in do_next_background_update
    await self._do_background_update(desired_duration_ms)
  File "/home/runner/work/synapse/synapse/synapse/storage/background_updates.py", line 261, in _do_background_update
    items_updated = await update_handler(progress, batch_size)
  File "/home/runner/work/synapse/synapse/synapse/storage/databases/main/room.py", line 1399, in _background_populate_rooms_creator_column
    end = await self.db_pool.runInteraction(
  File "/home/runner/work/synapse/synapse/synapse/storage/database.py", line 686, in runInteraction
    result = await self.runWithConnection(
  File "/home/runner/work/synapse/synapse/synapse/storage/database.py", line 791, in runWithConnection
    return await make_deferred_yieldable(
  File "/home/runner/work/synapse/synapse/.tox/py/lib/python3.9/site-packages/twisted/internet/defer.py", line 858, in _runCallbacks
    current.result = callback(  # type: ignore[misc]
  File "/home/runner/work/synapse/synapse/tests/server.py", line 425, in <lambda>
    d.addCallback(lambda x: function(*args, **kwargs))
  File "/home/runner/work/synapse/synapse/.tox/py/lib/python3.9/site-packages/twisted/enterprise/adbapi.py", line 293, in _runWithConnection
    compat.reraise(excValue, excTraceback)
  File "/home/runner/work/synapse/synapse/.tox/py/lib/python3.9/site-packages/twisted/python/deprecate.py", line 298, in deprecatedFunction
    return function(*args, **kwargs)
  File "/home/runner/work/synapse/synapse/.tox/py/lib/python3.9/site-packages/twisted/python/compat.py", line 404, in reraise
    raise exception.with_traceback(traceback)
  File "/home/runner/work/synapse/synapse/.tox/py/lib/python3.9/site-packages/twisted/enterprise/adbapi.py", line 284, in _runWithConnection
    result = func(conn, *args, **kw)
  File "/home/runner/work/synapse/synapse/synapse/storage/database.py", line 786, in inner_func
    return func(db_conn, *args, **kwargs)
  File "/home/runner/work/synapse/synapse/synapse/storage/database.py", line 554, in new_transaction
    r = func(cursor, *args, **kwargs)
  File "/home/runner/work/synapse/synapse/synapse/storage/databases/main/room.py", line 1375, in _background_populate_rooms_creator_column_txn
    for room_id, event_json in txn:
psycopg2.ProgrammingError: no results to fetch
```

* Move code not under the MSC2716 room version underneath an experimental config option

See https://github.com/matrix-org/synapse/pull/10566#issuecomment-906437909

* Add ordering to rooms creator background update

See https://github.com/matrix-org/synapse/pull/10697#discussion_r696815277

* Add comment to better document constant

See https://github.com/matrix-org/synapse/pull/10697#discussion_r699674458

* Use constant field

Signed-off-by: Sean Quah <seanq@element.io>

`execute_values` is a faster version of `execute_batch`.

Raises a 400 error instead of a 500 if an unknown preset is passed
from a client to create a room.

Additionally this enforce type hints on all function signatures inside
of the synapse.rest.client package.

This will only happen when a server has multiple out of band membership
events in a single room.

This avoids breaking the entire endpoint if a room with
an unsupported room version is encountered.

This updates the ordering of the returned events from the spaces
summary API to that defined in MSC2946 (which updates MSC1772).

Previously a step was skipped causing ordering to be inconsistent with
clients.

Part of https://github.com/matrix-org/synapse/pull/10566

 - Fill in creator whenever we insert into the rooms table
 - Add background update to backfill any missing creator values

Synapse 1.42.0rc1 (2021-09-01)
==============================

Server administrators are reminded to read [the upgrade notes](docs/upgrade.md#upgrading-to-v1420).

Features
--------

- Add support for [MSC3231](https://github.com/matrix-org/matrix-doc/pull/3231): Token authenticated registration. Users can be required to submit a token during registration to authenticate themselves. Contributed by Callum Brown. ([\#10142](https://github.com/matrix-org/synapse/issues/10142))
- Add support for [MSC3283](https://github.com/matrix-org/matrix-doc/pull/3283): Expose `enable_set_displayname` in capabilities. ([\#10452](https://github.com/matrix-org/synapse/issues/10452))
- Port the `PresenceRouter` module interface to the new generic interface. ([\#10524](https://github.com/matrix-org/synapse/issues/10524))
- Add pagination to the spaces summary based on updates to [MSC2946](https://github.com/matrix-org/matrix-doc/pull/2946). ([\#10613](https://github.com/matrix-org/synapse/issues/10613), [\#10725](https://github.com/matrix-org/synapse/issues/10725))

Bugfixes
--------

- Validate new `m.room.power_levels` events. Contributed by @aaronraimist. ([\#10232](https://github.com/matrix-org/synapse/issues/10232))
- Display an error on User-Interactive Authentication fallback pages when authentication fails. Contributed by Callum Brown. ([\#10561](https://github.com/matrix-org/synapse/issues/10561))
- Remove pushers when deleting an e-mail address from an account. Pushers for old unlinked emails will also be deleted. ([\#10581](https://github.com/matrix-org/synapse/issues/10581), [\#10734](https://github.com/matrix-org/synapse/issues/10734))
- Reject Client-Server `/keys/query` requests which provide `device_ids` incorrectly. ([\#10593](https://github.com/matrix-org/synapse/issues/10593))
- Rooms with unsupported room versions are no longer returned via `/sync`. ([\#10644](https://github.com/matrix-org/synapse/issues/10644))
- Enforce the maximum length for per-room display names and avatar URLs. ([\#10654](https://github.com/matrix-org/synapse/issues/10654))
- Fix a bug which caused the `synapse_user_logins_total` Prometheus metric not to be correctly initialised on restart. ([\#10677](https://github.com/matrix-org/synapse/issues/10677))
- Improve `ServerNoticeServlet` to avoid duplicate requests and add unit tests. ([\#10679](https://github.com/matrix-org/synapse/issues/10679))
- Fix long-standing issue which caused an error when a thumbnail is requested and there are multiple thumbnails with the same quality rating. ([\#10684](https://github.com/matrix-org/synapse/issues/10684))
- Fix a regression introduced in v1.41.0 which affected the performance of concurrent fetches of large sets of events, in extreme cases causing the process to hang. ([\#10703](https://github.com/matrix-org/synapse/issues/10703))
- Fix a regression introduced in Synapse 1.41 which broke email transmission on Systems using older versions of the Twisted library. ([\#10713](https://github.com/matrix-org/synapse/issues/10713))

Improved Documentation
----------------------

- Add documentation on how to connect Django with Synapse using OpenID Connect and django-oauth-toolkit. Contributed by @HugoDelval. ([\#10192](https://github.com/matrix-org/synapse/issues/10192))
- Advertise https://matrix-org.github.io/synapse documentation in the `README` and `CONTRIBUTING` files. ([\#10595](https://github.com/matrix-org/synapse/issues/10595))
- Fix some of the titles not rendering in the OpenID Connect documentation. ([\#10639](https://github.com/matrix-org/synapse/issues/10639))
- Minor clarifications to the documentation for reverse proxies. ([\#10708](https://github.com/matrix-org/synapse/issues/10708))
- Remove table of contents from the top of installation and contributing documentation pages. ([\#10711](https://github.com/matrix-org/synapse/issues/10711))

Deprecations and Removals
-------------------------

- Remove deprecated Shutdown Room and Purge Room Admin API. ([\#8830](https://github.com/matrix-org/synapse/issues/8830))

Internal Changes
----------------

- Improve type hints for the proxy agent and SRV resolver modules. Contributed by @dklimpel. ([\#10608](https://github.com/matrix-org/synapse/issues/10608))
- Clean up some of the federation event authentication code for clarity. ([\#10614](https://github.com/matrix-org/synapse/issues/10614), [\#10615](https://github.com/matrix-org/synapse/issues/10615), [\#10624](https://github.com/matrix-org/synapse/issues/10624), [\#10640](https://github.com/matrix-org/synapse/issues/10640))
- Add a comment asking developers to leave a reason when bumping the database schema version. ([\#10621](https://github.com/matrix-org/synapse/issues/10621))
- Remove not needed database updates in modify user admin API. ([\#10627](https://github.com/matrix-org/synapse/issues/10627))
- Convert room member storage tuples to `attrs` classes. ([\#10629](https://github.com/matrix-org/synapse/issues/10629), [\#10642](https://github.com/matrix-org/synapse/issues/10642))
- Use auto-attribs for the attrs classes used in sync. ([\#10630](https://github.com/matrix-org/synapse/issues/10630))
- Make `backfill` and `get_missing_events` use the same codepath. ([\#10645](https://github.com/matrix-org/synapse/issues/10645))
- Improve the performance of the `/hierarchy` API (from [MSC2946](https://github.com/matrix-org/matrix-doc/pull/2946)) by caching responses received over federation. ([\#10647](https://github.com/matrix-org/synapse/issues/10647))
- Run a nightly CI build against Twisted trunk. ([\#10651](https://github.com/matrix-org/synapse/issues/10651), [\#10672](https://github.com/matrix-org/synapse/issues/10672))
- Do not print out stack traces for network errors when fetching data over federation. ([\#10662](https://github.com/matrix-org/synapse/issues/10662))
- Simplify tests for device admin rest API. ([\#10664](https://github.com/matrix-org/synapse/issues/10664))
- Add missing type hints to REST servlets. ([\#10665](https://github.com/matrix-org/synapse/issues/10665), [\#10666](https://github.com/matrix-org/synapse/issues/10666), [\#10674](https://github.com/matrix-org/synapse/issues/10674))
- Flatten the `tests.synapse.rests` package by moving the contents of `v1` and `v2_alpha` into the parent. ([\#10667](https://github.com/matrix-org/synapse/issues/10667))
- Update `complement.sh` to rebuild the base Docker image when run with workers. ([\#10686](https://github.com/matrix-org/synapse/issues/10686))
- Split the event-processing methods in `FederationHandler` into a separate `FederationEventHandler`. ([\#10692](https://github.com/matrix-org/synapse/issues/10692))
- Remove unused `compare_digest` function. ([\#10706](https://github.com/matrix-org/synapse/issues/10706))

Judging by the template, this was intended ages ago, but we never
actually passed an avatar URL to the template. So let's provide one.

Closes #1546.

Co-authored-by: Patrick Cloke <clokep@users.noreply.github.com>

Expand OIDC to OpenID Connect.

Use `gc.freeze()` on exit to exclude all existing objects from the final GC.
In testing, this sped up shutdown by up to a few seconds.

`gc.freeze()` runs in constant time, so there is little chance of performance
regression.

Signed-off-by: Sean Quah <seanq@element.io>

This adds configuration options (under an `oembed` section) to
configure which URLs are matched to use oEmbed for URL
previews.

This was erroneously put under schema version 62 instead of 63.

These were broken in an incorrect merge of GHSA-jj53-8fmw-f2w2 (cb35df94)

Point to the book where possible, and use hyperlinks to github to refer to files not included in the book.

Co-authored-by: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>

* Add some tests to characterise the problem

Some failing. Current states:

  RoomsMemberListTestCase
test_get_member_list ...
[OK]
test_get_member_list_mixed_memberships ...
[OK]
test_get_member_list_no_permission ...
[OK]
test_get_member_list_no_permission_former_member ...
[OK]
test_get_member_list_no_permission_former_member_with_at_token ...
[FAIL]
test_get_member_list_no_room ...
[OK]
test_get_member_list_no_permission_with_at_token ...
[FAIL]

* Correct the tests

* Check user is/was member before divulging room membership

* Pull out only the 1 membership event we want.

* Update tests/rest/client/v1/test_rooms.py

Co-authored-by: Erik Johnston <erik@matrix.org>

* Fixup tests (following apply review suggestion)

Co-authored-by: Erik Johnston <erik@matrix.org>

Turns out that the functionality added in #10546 to skip TLS was incompatible
with older Twisted versions, so we need to be a bit more inventive.

Also, add a test to (hopefully) not break this in future. Sadly, testing TLS is
really hard.

- Removed page summaries from CONTRIBUTING and installation pages as 
this information was already in the table of contents on the right hand side
- Fixed some broken links in CONTRIBUTING
- Added margin-right tag for when table of contents is being shown
(otherwise the text in the page sometimes overlaps with it)

* Update reverse_proxy.md

* Create 10708.doc

Fixes: #9544

The code to deduplicate repeated fetches of the same set of events was
N^2 (over the number of events requested), which could lead to a process
being completely wedged.

The main fix is to deduplicate the returned deferreds so we only await
on a deferred once rather than many times. Seperately, when handling the
returned events from the defrered we only add the events we care about
to the event map to be returned (so that we don't pay the price of
inserting extraneous events into the dict).

The idea here is to take anything to do with incoming events and move it out to a separate handler, as a way of making FederationHandler smaller.

Given that backfill and get_missing_events are basically the same thing, it's somewhat crazy that we have entirely separate code paths for them. This makes backfill use the existing get_missing_events code, and then clears up all the unused code.

Signed-off-by: Aaron Raimist <aaron@raim.ist>

When a user deletes an email from their account it will
now also remove all pushers for that email and that user
(even if these pushers were created by a different client)