Currently, we try to pull the event corresponding to a sync token from the database. However, when
we fetch redaction events, we check the target of that redaction (because we aren't allowed to send
redactions to clients without validating them). So, if the sync token points to a redaction of an event
that we don't have, we have a problem.

It turns out we don't really need that event, and can just work with its ID and metadata, which
sidesteps the whole problem.

The remaining piece is a background update that is needed
for backwards compatibility.

* Raise a dedicated `InvalidEventSignatureError` from `_check_sigs_on_pdu`

* Downgrade logging about redactions to DEBUG

this can be very spammy during a room join, and it's not very useful.

* Raise `InvalidEventSignatureError` from `_check_sigs_and_hash`

... and, more importantly, move the logging out to the callers.

* changelog

The replication logic for groups is no longer used, so the message
passing infrastructure can be removed.

Signed-off-by: Sean Quah <seanq@matrix.org>

Signed-off-by: Sean Quah <seanq@matrix.org>

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

While the query was fast, we were calling it *a lot*.

event_edges.room_id is implied by the event id, so there is no need to join on the room id.

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

This reverts commit e0fae823.

`M_` is a reserved namespace.

Signed-off-by: Jacek Kusnierz <jacek.kusnierz@tum.de>

Uniformize spam-checker API, part 3: Expand check_event_for_spam with the ability to return additional fields (#12846)

Signed-off-by: David Teller <davidt@element.io>

Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>

Signed-off-by: Nicolas Werner <nicolas.werner@hotmail.de>
Co-authored-by: Brendan Abolivier <github@brendanabolivier.com>

This method was introduced in #12852. It is using the `state_key` column from
the `events` table, which is not (yet) reliable (see #11496).

Signed-off-by: Sumner Evans <sumner@beeper.com>

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

Signed-off-by: David Teller <davidt@element.io>
Co-authored-by: Brendan Abolivier <babolivier@matrix.org>

* Properly marks private methods as private.
* Adds missing docstrings.
* Rework inline methods.

Instead of hard-coding strings in many places.