This implements refresh tokens, as defined by MSC2918

This MSC has been implemented client side in Hydrogen Web: vector-im/hydrogen-web#235

The basics of the MSC works: requesting refresh tokens on login, having the access tokens expire, and using the refresh token to get a new one.

Signed-off-by: Quentin Gliech <quentingliech@gmail.com>

* Correctly ratelimit invites when creating a room

Also allow ratelimiting for more than one action at a time.

Part of #9744

Removes all redundant `# -*- coding: utf-8 -*-` lines from files, as python 3 automatically reads source code as utf-8 now.

`Signed-off-by: Jonathan de Jong <jonathan@automatia.nl&gt;`>

This should fix a class of bug where we forget to check if e.g. the appservice shouldn't be ratelimited.

We also check the `ratelimit_override` table to check if the user has ratelimiting disabled. That table is really only meant to override the event sender ratelimiting, so we don't use any values from it (as they might not make sense for different rate limits), but we do infer that if ratelimiting is disabled for the user we should disabled all ratelimits.

Fixes #9663

 - Update black version to the latest
 - Run black auto formatting over the codebase
    - Run autoformatting according to [`docs/code_style.md
`](https://github.com/matrix-org/synapse/blob/80d6dc9783aa80886a133756028984dbf8920168/docs/code_style.md)
 - Update `code_style.md` docs around installing black to use the correct version

And convert some inlineDeferreds to async-friendly functions.

Replaces the `federation_ip_range_blacklist` configuration setting with an
`ip_range_blacklist` setting with wider scope. It now applies to:

* Federation
* Identity servers
* Push notifications
* Checking key validitity for third-party invite events

The old `federation_ip_range_blacklist` setting is still honored if present, but
with reduced scope (it only applies to federation and identity servers).

We do it this way round so that only the "owner" can delete the access token (i.e. `/logout/all` by the "owner" also deletes that token, but `/logout/all` by the "target user" doesn't).

A future PR will add an API for creating such a token.

When the target user and authenticated entity are different the `Processed request` log line will be logged with a: `{@admin:server as @bob:server} ...`. I'm not convinced by that format (especially since it adds spaces in there, making it harder to use `cut -d ' '` to chop off the start of log lines). Suggestions welcome.

All handlers now available via get_*_handler() methods on the HomeServer.

Add new method ratelimiter.can_requester_do_action and ensure that appservices are exempt from being ratelimited.

Co-authored-by: Patrick Cloke <clokep@users.noreply.github.com>
Co-authored-by: Erik Johnston <erik@matrix.org>

Add new method ratelimiter.can_requester_do_action and ensure that appservices are exempt from being ratelimited.

Co-authored-by: Patrick Cloke <clokep@users.noreply.github.com>
Co-authored-by: Erik Johnston <erik@matrix.org>

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.

... and use it in places where it's trivial to do so.

This will make it easier to pass room versions into the FrozenEvent
constructors.

This allows support users to be created even on MAU limits via
the admin API. Support users are excluded from MAU after creation,
so it makes sense to exclude them in creation - except if the
whole host is in disabled state.

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

Record how long an access token is valid for, and raise a soft-logout once it
expires.

First of all, let's get rid of `TOKEN_NOT_FOUND_HTTP_STATUS`. It was a hack we
did at one point when it was possible to return either a 403 or a 401 if the
creds were missing. We always return a 401 in these cases now (thankfully), so
it's not needed.

Let's also stop abusing `AuthError` for these cases. Honestly they have nothing
that relates them to the other places that `AuthError` is used, other than the
fact that they are loosely under the 'Auth' banner. It makes no sense for them
to share exception classes.

Instead, let's add a couple of new exception classes: `InvalidClientTokenError`
and `MissingClientTokenError`, for the `M_UNKNOWN_TOKEN` and `M_MISSING_TOKEN`
cases respectively - and an `InvalidClientCredentialsError` base class for the
two of them.

this is only used in one place, so it's clearer if we inline it and reduce the
API surface.

Also, fixes a buglet where we would create an access token even if we were
about to block the user (we would never return the AT, so the user could never
use it, but it was still created and added to the db.)

The 'token' param is no longer used anywhere except the tests, so let's kill
that off too.

Fixes a bug where hs_disabled_message was not enforced for 3pid-based requests
if there was no server_notices_mxid configured.

* Rate-limiting for registration

* Add unit test for registration rate limiting

* Add config parameters for rate limiting on auth endpoints

* Doc

* Fix doc of rate limiting function

Co-Authored-By: babolivier <contact@brendanabolivier.com>

* Incorporate review

* Fix config parsing

* Fix linting errors

* Set default config for auth rate limiting

* Fix tests

* Add changelog

* Advance reactor instead of mocked clock

* Move parameters to registration specific config and give them more sensible default values

* Remove unused config options

* Don't mock the rate limiter un MAU tests

* Rename _register_with_store into register_with_store

* Make CI happy

* Remove unused import

* Update sample config

* Fix ratelimiting test for py2

* Add non-guest test

Allow for the creation of a support user.

A support user can access the server, join rooms, interact with other users, but does not appear in the user directory nor does it contribute to monthly active user limits.

Fixes a bug introduced in https://github.com/matrix-org/synapse/pull/1783 which
meant that single backslashes were not allowed in event field filters.

The intention here is to allow single-backslashes, but disallow
double-backslashes.