While this is not documented in the spec (but should be), Riot (and other clients) revoke 3PID invites by sending a m.room.third_party_invite event with an empty ({}) content to the room's state.
When the invited 3PID gets associated with a MXID, the identity server (which doesn't know about revocations) sends down to the MXID's homeserver all of the undelivered invites it has for this 3PID. The homeserver then tries to talk to the inviting homeserver in order to exchange these invite for m.room.member events.
When one of the invite is revoked, the inviting homeserver responds with a 500 error because it tries to extract a 'display_name' property from the content, which is empty. This might cause the invited server to consider that the server is down and not try to exchange other, valid invites (or at least delay it).
This fix handles the case of revoked invites by avoiding trying to fetch a 'display_name' from the original invite's content, and letting the m.room.member event fail the auth rules (because, since the original invite's content is empty, it doesn't have public keys), which results in sending a 403 with the correct error message to the invited server.
We have set the max retry interval to a value larger than a postgres or
sqlite int can hold, which caused exceptions when updating the
destinations table.
To fix postgres we need to change the column to a bigint, and for sqlite
we lower the max interval to 2**62 (which is still incredibly long).
Joining against `events` and ordering by `stream_ordering` is
inefficient as it forced scanning the entirety of the redactions table.
This isn't the case if we use `redactions.received_ts` column as we can
then use an index.
Currently we don't set `have_censored` column if we don't have the
target event of a redaction, which means we repeatedly attempt to censor
the same non-existant event.
When we persist non-redacted events we unset the `have_censored` column
for any redactions that target said event.
Doing a password reset via SMS has never worked, and in any case is a silly
idea because msisdn recycling is a thing.
See also matrix-org/matrix-doc#2303.
Erik Johnston