This reverts #11019 and structures the code a bit more like it was before #10985.

The global cache state must be reset before running the tests since other test
cases might have configured caching (and thus touched the global state).

Searches the returned HTML for an oEmbed endpoint using the
autodiscovery mechanism (`<link rel=...>`), and will request it
to generate the preview.

This splits apart `handle_new_user` into a function which adds an entry to the `user_directory` and a function which updates the room sharing tables. I plan to continue doing more of this kind of refactoring to clarify the implementation.

Hopefully this fixes these tests sometimes failing in CI.

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

This is in the context of creating new module callbacks that modules in https://github.com/matrix-org/synapse-dinsic can use, in an effort to reconcile the spam checker API in synapse-dinsic with the one in mainline.

Note that a module callback already exists for 3pid invites (https://matrix-org.github.io/synapse/develop/modules/third_party_rules_callbacks.html#check_threepid_can_be_invited) but it doesn't check whether the sender of the invite is allowed to send it.

This removes the magic allowing accessing configurable
variables directly from the config object. It is now required
that a specific configuration class is used (e.g. `config.foo`
must be replaced with `config.server.foo`).

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

Fix a long-standing bug where a batch of user directory changes would be
silently dropped if the server left a room early in the batch.

* Pull out `wait_for_background_update` in tests

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

There are two steps to rebuilding the user directory:

1. a scan over rooms, followed by
2. a scan over local users.

The former reads avatars and display names from the `room_memberships`
table and therefore contains potentially private avatars and
display names. The latter reads from the the `profiles` table which only
contains public data; moreover it will overwrite any private profiles
that the rooms scan may have written to the user directory. This means
that the rebuild could leak private user while the rebuild was in
progress, only to later cover up the leaks once the rebuild had completed.

This change skips over local users when writing user_directory rows
when scanning rooms. Doing so means that it'll take longer for a rebuild
to make local users searchable, which is unfortunate. I think a future
PR can improve this by swapping the order of the two steps above. (And
indeed there's more to do here, e.g. copying from `profiles` without
going via Python.)

Small tidy-ups while I'm here:

* Remove duplicated code from test_initial. This was meant to be pulled into `purge_and_rebuild_user_dir`.
* Move `is_public` before updating sharing tables. No functional change; it's still before the first read of `is_public`.
* Don't bother creating a set from dict keys. Slightly nicer and makes the code simpler.

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

* add test

* add function to remove user from monthly active table in deactivate code

* add function to remove user from monthly active table

* add changelog entry

* update changelog number

* requested changes

* update docstring on new function

* fix lint error

* Update synapse/storage/databases/main/monthly_active_users.py

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

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

Signed-off-by: Andrew Ferrazzutti <fair@miscworks.net>

* Introduce `should_include_local_users_in_dir`

We exclude three kinds of local users from the user_directory tables. At
present we don't consistently exclude all three in the same places. This
commit introduces a new function to gather those exclusion conditions
together. Because we have to handle local and remote users in different
ways, I've made that function only consider the case of remote users.
It's the caller's responsibility to make the local versus remote
distinction clear and correct.

A test fixup is required. The test now hits a path which makes db
queries against the users table. The expected rows were missing, because
we were using a dummy user that hadn't actually been registered.

We also add new test cases to covert the exclusion logic.

----

By my reading this makes these changes:

* When an app service user registers or changes their profile, they will
  _not_ be added to the user directory. (Previously only support and
  deactivated users were excluded). This is consistent with the logic that
  rebuilds the user directory. See also [the discussion
  here](https://github.com/matrix-org/synapse/pull/10914#discussion_r716859548

).
* When rebuilding the directory, exclude support and disabled users from
  room sharing tables. Previously only appservice users were excluded.
* Exclude all three categories of local users when rebuilding the
  directory. Previously `_populate_user_directory_process_users` didn't do
  any exclusion.

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

This fixes a "Event not signed by authorising server" error when
transition room member from join -> join, e.g. when updating a
display name or avatar URL for restricted rooms.

* type-hint `HomeserverTestcase.setup_test_homeserver`

For better IDE completion. A small drive-by.

Uses `override_config` and fixes test_auto_create_auto_join_where_no_consent
to properly configure auto-join rooms.

This fixes a "Event not signed by authorising server" error when
transition room member from join -> join, e.g. when updating a
display name or avatar URL for restricted rooms.

Fix some harmless errors from background processes (mostly
due to awaiting Mock objects) that occurred in the Synapse
logs during unit tests.

This follows a correction made in twisted/twisted#1664 and should fix our Twisted Trial CI job.

Until that change is in a twisted release, we'll have to ignore the type
of the `host` argument. I've raised #10899 to remind us to review the
issue in a few months' time.

* Pull out GetUserDirectoryTables helper
* Don't rebuild the dir in tests that don't need it

In #10796 I changed registering a user to add directory entries under.
This means we don't have to force a directory regbuild in to tests of
the user directory search.

* Move test_initial to tests/storage
* Add type hints to both test_user_directory files

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

Broadly, the existing `event_auth.check` function has two parts:
 * a validation section: checks that the event isn't too big, that it has the rught signatures, etc. 
   This bit is independent of the rest of the state in the room, and so need only be done once 
   for each event.
 * an auth section: ensures that the event is allowed, given the rest of the state in the room.
   This gets done multiple times, against various sets of room state, because it forms part of
   the state res algorithm.

Currently, this is implemented with `do_sig_check` and `do_size_check` parameters, but I think
that makes everything hard to follow. Instead, we split the function in two and call each part
separately where it is needed.

* Inline `_check_event_auth` for outliers

When we are persisting an outlier, most of `_check_event_auth` is redundant:

 * `_update_auth_events_and_context_for_auth` does nothing, because the
   `input_auth_events` are (now) exactly the event's auth_events,
   which means that `missing_auth` is empty.

 * we don't care about soft-fail, kicking guest users or `send_on_behalf_of`
   for outliers

... so the only thing that matters is the auth itself, so let's just do that.

* `_auth_and_persist_fetched_events_inner`: de-async `prep`

`prep` no longer calls any `async` methods, so let's make it synchronous.

* Simplify `_check_event_auth`

We no longer need to support outliers here, which makes things rather simpler.

* changelog

* lint

URL cache files are short-lived and it does not make sense to offload
them (eg. to the cloud) or back them up.

This is in the context of creating new module callbacks that modules in https://github.com/matrix-org/synapse-dinsic can use, in an effort to reconcile the spam checker API in synapse-dinsic with the one in mainline.

This adds a callback that's fairly similar to user_may_create_room except it also allows processing based on the invites sent at room creation.

* Factor more stuff out of `_get_events_and_persist`

It turns out that the event-sorting algorithm in `_get_events_and_persist` is
also useful in other circumstances. Here we move the current
`_auth_and_persist_fetched_events` to `_auth_and_persist_fetched_events_inner`,
and then factor the sorting part out to `_auth_and_persist_fetched_events`.

* `_get_remote_auth_chain_for_event`: remove redundant `outlier` assignment

`get_event_auth` returns events with the outlier flag already set, so this is
redundant (though we need to update a test where `get_event_auth` is mocked).

* `_get_remote_auth_chain_for_event`: move existing-event tests earlier

Move a couple of tests outside the loop. This is a bit inefficient for now, but
a future commit will make it better. It should be functionally identical.

* `_get_remote_auth_chain_for_event`: use `_auth_and_persist_fetched_events`

We can use the same codepath for persisting the events fetched as part of an
auth chain as for those fetched individually by `_get_events_and_persist` for
building the state at a backwards extremity.

* `_get_remote_auth_chain_for_event`: use a dict for efficiency

`_auth_and_persist_fetched_events` sorts the events itself, so we no longer
need to care about maintaining the ordering from `get_event_auth` (and no
longer need to sort by depth in `get_event_auth`).

That means that we can use a map, making it easier to filter out events we
already have, etc.

* changelog

* `_auth_and_persist_fetched_events`: improve docstring

If the MAU count had been reached, Synapse incorrectly blocked appservice users even though they've been explicitly configured not to be tracked (the default). This was due to bypassing the relevant if as it was chained behind another earlier hit if as an elif.

Signed-off-by: Jason Robinson <jasonr@matrix.org>

* Improve typing in user_directory files

This makes the user_directory.py in storage pass most of mypy's
checks (including `no-untyped-defs`). Unfortunately that file is in the
tangled web of Store class inheritance so doesn't pass mypy at the moment.

The handlers directory has already been mypyed.

Co-authored-by: reivilibre <olivier@librepush.net>

Per updates to MSC3231 in order to use the same grammar
as other identifiers.

Co-authored-by: Dirk Klimpel <5740567+dklimpel@users.noreply.github.com>
Co-authored-by: reivilibre <olivier@librepush.net>
Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

This avoids the overhead of searching through the various
configuration classes by directly referencing the class that
the attributes are in.

It also improves type hints since mypy can now resolve the
types of the configuration variables.