The spec [states](https://matrix.org/docs/spec/client_server/r0.6.1#phone-number) that `m.id.phone` requires the field `country` and `phone`.
In Synapse, we've been enforcing `country` and `number`.
I am not currently sure whether this affects any client implementations.
This issue was introduced in #1994.
While working on https://github.com/matrix-org/synapse/issues/5665 I found myself digging into the `Ratelimiter` class and seeing that it was both:
* Rather undocumented, and
* causing a *lot* of config checks
This PR attempts to refactor and comment the `Ratelimiter` class, as well as encourage config file accesses to only be done at instantiation.
Best to be reviewed commit-by-commit.
The idea here is that if an instance persists an event via the replication HTTP API it can return before we receive that event over replication, which can lead to races where code assumes that persisting an event immediately updates various caches (e.g. current state of the room).
Most of Synapse doesn't hit such races, so we don't do the waiting automagically, instead we do so where necessary to avoid unnecessary delays. We may decide to change our minds here if it turns out there are a lot of subtle races going on.
People probably want to look at this commit by commit.
* Remove redundant python2 support code
`str.decode()` doesn't exist on python3, so presumably this code was doing
nothing
* Filter out pushers with corrupt data
When we get a row with unparsable json, drop the row, rather than returning a
row with null `data`, which will then cause an explosion later on.
* Improve logging when we can't start a pusher
Log the ID to help us understand the problem
* Make email pusher setup more robust
We know we'll have a `data` member, since that comes from the database. What we
*don't* know is if that is a dict, and if that has a `brand` member, and if
that member is a string.
We were doing this in a number of places which meant that some login
code paths incremented the counter multiple times.
It was also applying ratelimiting to UIA endpoints, which was probably
not intentional.
In particular, some custom auth modules were calling
`check_user_exists`, which incremented the counters, meaning that people
would fail to login sometimes.
