I meant to do this before, in #10591, but because I'm stupid I forgot to do it
for V2 and V3 events.

I've factored the common code out to `EventBase` to save us having two copies
of it.

This means that for `FrozenEvent` we replace `self.get("event_id", None)` with
`self.event_id`, which I think is safe. `get()` is an alias for
`self._dict.get()`, whereas `event_id()` is an `@property` method which looks
up `self._event_id`, which is populated during construction from the same
dict. We don't seem to rely on the fallback, because if the `event_id` key is
absent from the dict then construction of the `EventBase` object will
fail.

Long story short, the only way this could change behaviour is if
`event_dict["event_id"]` is changed *after* the `EventBase` object is
constructed without updating the `_event_id` field, or vice versa - either of
which would be very problematic anyway and the behavior of `str(event)` is the
least of our worries.

So we can see distinguish between "evicting because the cache is too big" and "evicting because the cache entries haven't been recently used".

See https://github.com/matrix-org/matrix-doc/pull/2716#discussion_r684574497

Dropping support for older MSC2716 room versions so we don't have to worry about
supporting both chunk and batch events.

This should fix stale deleted files being still accessible.

The major change is moving the decision of whether to use oEmbed
further up the call-stack. This reverts the _download_url method to
being a "dumb" functionwhich takes a single URL and downloads it
(as it was before #7920).

This also makes more minor refactorings:

* Renames internal variables for clarity.
* Factors out shared code between the HTML and rich oEmbed
  previews.
* Fixes tests to preview an oEmbed image.

Test for #10830

Ideally the test would also make sure the new state event comes down sync, but this is probably good enough.

* add tests for checking if room search works with non-ascii char

* change encoding on parse_string to UTF-8

* lints

* properly encode search term

* lints

* add changelog file

* update changelog number

* set changelog entry filetype to .bugfix

* Revert "set changelog entry filetype to .bugfix"

This reverts commit be8e5a314251438ec4ec7dbc59ba32162c93e550.

* update changelog message and file type

* change parse_string default encoding back to ascii and update room search admin api calll to parse string

* refactor tests

* Update tests/rest/admin/test_room.py

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

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

Rename `/batch_send` query parameter from `?prev_event` to more obvious usage with `?prev_event_id` (MSC2716) (#10839)

As mentioned in https://github.com/matrix-org/matrix-doc/pull/2716#discussion_r705872887
and https://github.com/matrix-org/synapse/issues/10737

It's a simplification, but one that'll help make the user directory logic easier
to follow with the other changes upcoming. It's not strictly required for those
changes, but this will help simplify the resulting logic that listens for
`m.room.member` events and generally make the logic easier to follow.

This means the config option `search_all_users` ends up controlling the
search query only, and not the data we store. The cost of doing so is an
extra row in the `user_directory` and `user_directory_search` tables for
each local user which

- belongs to no public rooms
- belongs to no private rooms of size ≥ 2

I think the cost of this will be marginal (since they'll already have entries
 in `users` and `profiles` anyway).

As a small upside, a homeserver whose directory was built with this
change can toggle `search_all_users` without having to rebuild their
directory.

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

one day I'll learn how to spell hierarchy

* Allow membership event to unban user

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

This should ensure GHA runs synapse against the same-named sytest branch

Adds missing type hints to methods in the synapse.handlers
module and requires all methods to have type hints there.

This also removes the unused construct_auth_difference method
from the FederationHandler.

To avoid duplicating it between a few tests.

We added a bunch of spans in #10704, but this ended up adding a lot of
redundant spans for rooms where nothing changed, so instead we only
start the span if there might be something interesting going on.

Including admin, consent, key, synapse, and media. All REST servlets
(the synapse.rest module) now require typed method definitions.

Also enables Mypy for related tests.

In `MatrixFederationHttpClient._send_request()`, we make a HTTP request
using an `Agent`, wrap that request in a timeout and await the resulting
`Deferred`. On its own, the `Agent` performing the HTTP request
correctly stashes and restores the logging context while waiting.
The addition of the timeout introduces a path where the logging context
is not restored when execution resumes.

To address this, we wrap the timeout `Deferred` in a
`make_deferred_yieldable()` to stash the logging context and restore it
on completion of the `await`. However this is not sufficient, since by
the time we construct the timeout `Deferred`, the `Agent` has already
stashed and cleared the logging context when using
`make_deferred_yieldable()` to produce its `Deferred` for the request.

Hence, we wrap the `Agent` request in a `run_in_background()` to "fork"
and preserve the logging context so that we can stash and restore it
when `await`ing the timeout `Deferred`.

This approach is similar to the one used with `defer.gatherResults`.

Note that the code is still not fully correct. When a timeout occurs,
the request remains running in the background (existing behavior which
is nothing to do with the new call to `run_in_background`) and may
re-start the logging context after it has finished.

Synapse 1.43.0rc1 (2021-09-14)

This release drops support for the deprecated, unstable API for [MSC2858](https://github.com/matrix-org/matrix-doc/blob/master/proposals/2858-Multiple-SSO-Identity-Providers.md#unstable-prefix), as well as the undocumented `experimental.msc2858_enabled` config option. Client authors should update their clients to use the stable API, available since Synapse 1.30.

Features
--------

- Allow room creators to send historical events specified by [MSC2716](https://github.com/matrix-org/matrix-doc/pull/2716) in existing room versions. ([\#10566](https://github.com/matrix-org/synapse/issues/10566))
- Add config option to use non-default manhole password and keys. ([\#10643](https://github.com/matrix-org/synapse/issues/10643))
- Skip final GC at shutdown to improve restart performance. ([\#10712](https://github.com/matrix-org/synapse/issues/10712))
- Allow configuration of the oEmbed URLs used for URL previews. ([\#10714](https://github.com/matrix-org/synapse/issues/10714), [\#10759](https://github.com/matrix-org/synapse/issues/10759))
- Prefer [room version 9](https://github.com/matrix-org/matrix-doc/pull/3375) for restricted rooms per the [room version capabilities](https://github.com/matrix-org/matrix-doc/pull/3244) API. ([\#10772](https://github.com/matrix-org/synapse/issues/10772))

Bugfixes
--------

- Fix a long-standing bug where room avatars were not included in email notifications. ([\#10658](https://github.com/matrix-org/synapse/issues/10658))
- Fix a bug where the ordering algorithm was skipping the `origin_server_ts` step in the spaces summary resulting in unstable room orderings. ([\#10730](https://github.com/matrix-org/synapse/issues/10730))
- Fix edge case when persisting events into a room where there are multiple events we previously hadn't calculated auth chains for (and hadn't marked as needing to be calculated). ([\#10743](https://github.com/matrix-org/synapse/issues/10743))
- Fix a bug which prevented calls to `/createRoom` that included the `room_alias_name` parameter from being handled by worker processes. ([\#10757](https://github.com/matrix-org/synapse/issues/10757))
- Fix a bug which prevented user registration via SSO to require consent tracking for SSO mapping providers that don't prompt for Matrix ID selection. Contributed by @AndrewFerr. ([\#10733](https://github.com/matrix-org/synapse/issues/10733))
- Only return the stripped state events for the `m.space.child` events in a room for the spaces summary from [MSC2946](https://github.com/matrix-org/matrix-doc/pull/2946). ([\#10760](https://github.com/matrix-org/synapse/issues/10760))
- Properly handle room upgrades of spaces. ([\#10774](https://github.com/matrix-org/synapse/issues/10774))
- Fix a bug which generated invalid homeserver config when the `frontend_proxy` worker type was passed to the Synapse Worker-based Complement image. ([\#10783](https://github.com/matrix-org/synapse/issues/10783))

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

- Minor fix to the `media_repository` developer documentation. Contributed by @cuttingedge1109. ([\#10556](https://github.com/matrix-org/synapse/issues/10556))
- Update the documentation to note that the `/spaces` and `/hierarchy` endpoints can be routed to workers. ([\#10648](https://github.com/matrix-org/synapse/issues/10648))
- Clarify admin API documentation on undoing room deletions. ([\#10735](https://github.com/matrix-org/synapse/issues/10735))
- Split up the modules documentation and add examples for module developers. ([\#10758](https://github.com/matrix-org/synapse/issues/10758))
- Correct 2 typographical errors in the [Log Contexts documentation](https://matrix-org.github.io/synapse/latest/log_contexts.html). ([\#10795](https://github.com/matrix-org/synapse/issues/10795))
- Fix a wording mistake in the sample configuration. Contributed by @bramvdnheuvel:nltrix.net. ([\#10804](https://github.com/matrix-org/synapse/issues/10804))

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

- Remove the [unstable MSC2858 API](https://github.com/matrix-org/matrix-doc/blob/master/proposals/2858-Multiple-SSO-Identity-Providers.md#unstable-prefix), including the undocumented `experimental.msc2858_enabled` config option. The unstable API has been deprecated since Synapse 1.35. Client authors should update their clients to use the stable API introduced in Synapse 1.30 if they have not already done so. ([\#10693](https://github.com/matrix-org/synapse/issues/10693))

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

- Add OpenTracing logging to help debug stuck messages (as described by issue [#9424](https://github.com/matrix-org/synapse/issues/9424)). ([\#10704](https://github.com/matrix-org/synapse/issues/10704))
- Add type annotations to the `synapse.util` package. ([\#10601](https://github.com/matrix-org/synapse/issues/10601))
- Ensure `rooms.creator` field is always populated for easy lookup in [MSC2716](https://github.com/matrix-org/matrix-doc/pull/2716) usage later. ([\#10697](https://github.com/matrix-org/synapse/issues/10697))
- Add missing type hints to REST servlets. ([\#10707](https://github.com/matrix-org/synapse/issues/10707), [\#10728](https://github.com/matrix-org/synapse/issues/10728), [\#10736](https://github.com/matrix-org/synapse/issues/10736))
- Do not include rooms with unknown room versions in the spaces summary results. ([\#10727](https://github.com/matrix-org/synapse/issues/10727))
- Additional error checking for the `preset` field when creating a room. ([\#10738](https://github.com/matrix-org/synapse/issues/10738))
- Clean up some of the federation event authentication code for clarity. ([\#10744](https://github.com/matrix-org/synapse/issues/10744), [\#10745](https://github.com/matrix-org/synapse/issues/10745), [\#10746](https://github.com/matrix-org/synapse/issues/10746), [\#10771](https://github.com/matrix-org/synapse/issues/10771), [\#10773](https://github.com/matrix-org/synapse/issues/10773), [\#10781](https://github.com/matrix-org/synapse/issues/10781))
- Add an index to `presence_stream` to hopefully speed up startups a little. ([\#10748](https://github.com/matrix-org/synapse/issues/10748))
- Refactor event size checking code to simplify searching the codebase for the origins of certain error strings that are occasionally emitted. ([\#10750](https://github.com/matrix-org/synapse/issues/10750))
- Move tests relating to rooms having encryption out of the user directory tests. ([\#10752](https://github.com/matrix-org/synapse/issues/10752))
- Use `attrs` internally for the URL preview code & update documentation. ([\#10753](https://github.com/matrix-org/synapse/issues/10753))
- Minor speed ups when joining large rooms over federation. ([\#10754](https://github.com/matrix-org/synapse/issues/10754), [\#10755](https://github.com/matrix-org/synapse/issues/10755), [\#10756](https://github.com/matrix-org/synapse/issues/10756), [\#10780](https://github.com/matrix-org/synapse/issues/10780), [\#10784](https://github.com/matrix-org/synapse/issues/10784))
- Add a constant for `m.federate`. ([\#10775](https://github.com/matrix-org/synapse/issues/10775))
- Add a script to update the Debian changelog in a Docker container for systems that are not Debian-based. ([\#10778](https://github.com/matrix-org/synapse/issues/10778))
- Change the format of authenticated users in logs when a user is being puppeted by and admin user. ([\#10779](https://github.com/matrix-org/synapse/issues/10779))
- Remove fixed and flakey tests from the Sytest blacklist. ([\#10788](https://github.com/matrix-org/synapse/issues/10788))
- Improve internal details of the user directory code. ([\#10789](https://github.com/matrix-org/synapse/issues/10789))
- Use direct references to config flags. ([\#10798](https://github.com/matrix-org/synapse/issues/10798))
- Ensure the Rust reporter passes type checking with jaeger-client 4.7's type annotations. ([\#10799](https://github.com/matrix-org/synapse/issues/10799))

This is mostly an internal change, but improves type hints in the
media code.