Inspired by the room batch handler, this uses previous event inserts to
pre-populate prev events during room creation, reducing the number of
queries required to create a room.
Signed off by Nick @ Beeper (@Fizzadar)
All tests are prefixed with `STALE_` and therefore they are silently
skipped. They were moved to `STALE_` in version `v0.5.0` in commit
2fcce3b3c5 - `Remove stale tests`.
Tests from `RoomEventsStoreTestCase` class are not used for last 8
years, I believe the best would be to remove them entirely.
Signed-off-by: Petr Vaněk <arkamar@atlas.cz>
Bounce recalculation of current state to the correct event persister and
move recalculation of current state into the event persistence queue, to
avoid concurrent updates to a room's current state.
Also give recalculation of a room's current state a real stream
ordering.
Signed-off-by: Sean Quah <seanq@matrix.org>
* Cast to postgres types when handling postgres db
* Remove unused method
* Easy annotations
* Annotate create_room
* Use `ParamSpec` to annotate looping_call
* Annotate `default_config`
* Track `now` as a float
`time_ms` returns an int like the proper Synapse `Clock`
* Introduce a `Timer` dataclass
* Introduce a Looper type
* Suppress checking of a mock
* tests.utils is typed
* Changelog
* Whoops, import ParamSpec from typing_extensions
* ditch the psycopg2 casts
==============================
Bugfixes
--------
- Update the version of the [ldap3 plugin](https://github.com/matrix-org/matrix-synapse-ldap3/) included in the `matrixdotorg/synapse` DockerHub images and the Debian packages hosted on `packages.matrix.org` to 0.2.1. This fixes [a bug](https://github.com/matrix-org/matrix-synapse-ldap3/pull/163) with usernames containing uppercase characters. ([\#13156](https://github.com/matrix-org/synapse/issues/13156))
- Fix a bug introduced in Synapse 1.62.0rc1 affecting unread counts for users on small servers. ([\#13168](https://github.com/matrix-org/synapse/issues/13168))
-----BEGIN PGP SIGNATURE-----
iQIzBAABCAAdFiEEgQG31Z317NrSMt0QiISIDS7+X/QFAmLDDVgACgkQiISIDS7+
X/Q+KQ//WuWB9hfAW8XEyYHWox95zaITsAzY/TTG1IXygAMjgEk2+9utdRaX3wbk
YDaZCeEw+vbK/3w/lt1RzI30K3uVCZVcW2DTQr1Qi4B+UWLOlCsVfOT9LcMvNoJe
ww/cOK6RpPgTlqk5ij0MtdjfWkAJeToi7ESMooORxhWFm3Zd8e5BpbNv89WUBZhk
zCqCjIdjSF+Mwk8NwmU1iJi5JQY/+Xl51uk2+wGIAe4vtgPTz7PJmoPF1E6nGGVF
9OYdlWU4H7u6js8n05QL2jKtX34uszCo2hwoW2aFPPmF0B2CFEV6WFBiDOppLZ1g
ZMJv1s/34RXoBu8pAuJnq2BZkWxu99LRmPV+f/R+S0jDT1MH9tdSdhfcGu7iH/Y9
uguGX3OOlxnkUb5o825Xt3mvBcVaTGY+sspFtB12RtXmWRdll/Hq6w11ZN5f6qDy
Nr/DuoPjMAH7kzelFn/GpP6K8zX8iYjf0lLCyrbYV7OYAI6/I+Vao+sT2ctHD1T8
s4aTTx1bEl23mo/RiqH2fRHaPhBjZKW0uv6iRNqDE2ThYPAXinVtt7MiUU0QGco5
vMca/RZBkEj0Lov0AleBx4XRXlBTyq5BX2V1frYLenKp42bDzN9sgsPAOPeKieHW
qjr+Ti9i47wGADXs2GI/mke/C8jlONEKJm/v8mwXItn8Za7wBJc=
=SpI6
-----END PGP SIGNATURE-----
Merge tag 'v1.62.0rc3' into develop
Synapse 1.62.0rc3 (2022-07-04)
==============================
Bugfixes
--------
- Update the version of the [ldap3 plugin](https://github.com/matrix-org/matrix-synapse-ldap3/) included in the `matrixdotorg/synapse` DockerHub images and the Debian packages hosted on `packages.matrix.org` to 0.2.1. This fixes [a bug](https://github.com/matrix-org/matrix-synapse-ldap3/pull/163) with usernames containing uppercase characters. ([\#13156](https://github.com/matrix-org/synapse/issues/13156))
- Fix a bug introduced in Synapse 1.62.0rc1 affecting unread counts for users on small servers. ([\#13168](https://github.com/matrix-org/synapse/issues/13168))
When we receive an event over federation during a faster join, there is no need
to wait for full state, since we have a whole reconciliation process designed
to take the partial state into account.
* Make _iterate_over_text easier to read by using simple data structures
* Prefer a set of tags to ignore
In my tests, it's 4x faster to check for containment in a set of this size
* Add a stack size limit to _iterate_over_text
* Continue accepting the case where there is no body element
* Use an early return instead for None
Co-authored-by: Richard van der Hoff <richard@matrix.org>
* Extend the auth rule checks for `m.room.create` events
... and move them up to the top of the function. Since the no auth_events are
allowed for m.room.create events, we may as well get the m.room.create event
checks out of the way first.
* Add a test for create events with prev_events
Pull out `twitter:` meta tags when generating a preview and
use it to augment any `og:` meta tags.
Prefers Open Graph information over Twitter card information.
* Add auth events to events used in tests
* Move some event auth checks out to a different method
Some of the event auth checks apply to an event's auth_events, rather than the
state at the event - which means they can play no part in state
resolution. Move them out to a separate method.
* Rename check_auth_rules_for_event
Now it only checks the state-dependent auth rules, it needs a better name.
Fixes#11887 hopefully.
The core change here is that `event_push_summary` now holds a summary of counts up until a much more recent point, meaning that the range of rows we need to count in `event_push_actions` is much smaller.
This needs two major changes:
1. When we get a receipt we need to recalculate `event_push_summary` rather than just delete it
2. The logic for deleting `event_push_actions` is now divorced from calculating `event_push_summary`.
In future it would be good to calculate `event_push_summary` while we persist a new event (it should just be a case of adding one to the relevant rows in `event_push_summary`), as that will further simplify the get counts logic and remove the need for us to periodically update `event_push_summary` in a background job.
* Rename test_fedclient to match its source file
* Require at least one destination to be truthy
* Explicitly validate user ID in profile endpoint GETs
Co-authored-by: Patrick Cloke <clokep@users.noreply.github.com>
This simplifies the access token verification logic by removing the `rights`
parameter which was only ever used for the unsubscribe link in email
notifications. The latter has been moved under the `/_synapse` namespace,
since it is not a standard API.
This also makes the email verification link more secure, by embedding the
app_id and pushkey in the macaroon and verifying it. This prevents the user
from tampering the query parameters of that unsubscribe link.
Macaroon generation is refactored:
- Centralised all macaroon generation and verification logic to the
`MacaroonGenerator`
- Moved to `synapse.utils`
- Changed the constructor to require only a `Clock`, hostname, and a secret key
(instead of a full `Homeserver`).
- Added tests for all methods.
Instead, use the `room_version` property of the event we're checking.
The `room_version` was originally added as a parameter somewhere around #4482,
but really it's been redundant since #6875 added a `room_version` field to `EventBase`.
In practice, when we run the auth rules, all of the events have the right room
version. Let's stop building Room V1 events for these tests and use the right
version.
The `room_id` field was removed from MSC2946 before
it was accepted. It was initially kept for backwards compatibility
and should be removed now that the stable form of the API
is used.
This change only stops Synapse from validating that it is returned,
a future PR will remove returning it as part of the response.
By always using delete_devices and sometimes passing a list
with a single device ID.
Previously these methods had gotten out of sync with each
other and it seems there's little benefit to the single-device
variant.
* Update worker docs to remove group endpoints.
* Removes an unused parameter to `ApplicationService`.
* Break dependency between media repo and groups.
* Avoid copying `m.room.related_groups` state events during room upgrades.
==============================
This release of Synapse adds a unique index to the `state_group_edges` table, in
order to prevent accidentally introducing duplicate information (for example,
because a database backup was restored multiple times). If your Synapse database
already has duplicate rows in this table, this could fail with an error and
require manual remediation.
Additionally, the signature of the `check_event_for_spam` module callback has changed.
The previous signature has been deprecated and remains working for now. Module authors
should update their modules to use the new signature where possible.
See [the upgrade notes](https://github.com/matrix-org/synapse/blob/develop/docs/upgrade.md#upgrading-to-v1600)
for more details.
Features
--------
- Add an option allowing users to use their password to reauthenticate for privileged actions even though password login is disabled. ([\#12883](https://github.com/matrix-org/synapse/issues/12883))
Bugfixes
--------
- Explicitly close `ijson` coroutines once we are done with them, instead of leaving the garbage collector to close them. ([\#12875](https://github.com/matrix-org/synapse/issues/12875))
Internal Changes
----------------
- Improve URL previews by not including the content of media tags in the generated description. ([\#12887](https://github.com/matrix-org/synapse/issues/12887))
-----BEGIN PGP SIGNATURE-----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=D3F+
-----END PGP SIGNATURE-----
Merge tag 'v1.60.0rc2' into develop
Synapse 1.60.0rc2 (2022-05-27)
==============================
This release of Synapse adds a unique index to the `state_group_edges` table, in
order to prevent accidentally introducing duplicate information (for example,
because a database backup was restored multiple times). If your Synapse database
already has duplicate rows in this table, this could fail with an error and
require manual remediation.
Additionally, the signature of the `check_event_for_spam` module callback has changed.
The previous signature has been deprecated and remains working for now. Module authors
should update their modules to use the new signature where possible.
See [the upgrade notes](https://github.com/matrix-org/synapse/blob/develop/docs/upgrade.md#upgrading-to-v1600)
for more details.
Features
--------
- Add an option allowing users to use their password to reauthenticate for privileged actions even though password login is disabled. ([\#12883](https://github.com/matrix-org/synapse/issues/12883))
Bugfixes
--------
- Explicitly close `ijson` coroutines once we are done with them, instead of leaving the garbage collector to close them. ([\#12875](https://github.com/matrix-org/synapse/issues/12875))
Internal Changes
----------------
- Improve URL previews by not including the content of media tags in the generated description. ([\#12887](https://github.com/matrix-org/synapse/issues/12887))
* Refactor HTTP response size limits
Rather than passing a separate `max_response_size` down the stack, make it an
attribute of the `parser`.
* Allow bigger responses on `federation/v1/state`
`/state` can return huge responses, so we need to handle that.
Makes it so that groups/communities no longer exist from a user-POV. E.g. we remove:
* All API endpoints (including Client-Server, Server-Server, and admin).
* Documented configuration options (and the experimental flag, which is now unused).
* Special handling during room upgrades.
* The `groups` section of the `/sync` response.
Implements the following behind an experimental configuration flag:
* A new push rule kind for mutually related events.
* A new default push rule (`.m.rule.thread_reply`) under an unstable prefix.
This is missing part of MSC3772:
* The `.m.rule.thread_reply_to_me` push rule, this depends on MSC3664 / #11804.
The main differences are:
- values with delimiters (such as colons) should be quoted, so always
quote the origin, since it could contain a colon followed by a port
number
- should allow more than one space after "X-Matrix"
- quoted values with backslash-escaped characters should be unescaped
- names should be case insensitive
A minor optimization to avoid unnecessary copying/building
identical dictionaries when filtering private read receipts.
Also clarifies comments and cleans-up some tests.
Parse the `m.relates_to` event content field (which describes relations)
in a single place, this is used during:
* Event persistence.
* Validation of the Client-Server API.
* Fetching bundled aggregations.
* Processing of push rules.
Each of these separately implement the logic and each made slightly
different assumptions about what was valid. Some had minor / potential
bugs.
`BaseFederationServlet` wraps its endpoints in a bunch of async code
that has not been vetted for compatibility with cancellation.
Fail CI if a `@cancellable` flag is applied to a federation endpoint.
Signed-off-by: Sean Quah <seanq@element.io>
While `ReplicationEndpoint`s register themselves via `JsonResource`,
they pass a method that calls the handler, instead of the handler itself,
to `register_paths`. As a result, `JsonResource` will not correctly pick
up the `@cancellable` flag and we have to apply it ourselves.
Signed-off-by: Sean Quah <seanq@element.io>
Both `RestServlet`s and `BaseFederationServlet`s register their handlers
with `HttpServer.register_paths` / `JsonResource.register_paths`. Update
`JsonResource` to respect the `@cancellable` flag on handlers registered
in this way.
Although `ReplicationEndpoint` also registers itself using
`register_paths`, it does not pass the handler method that would have the
`@cancellable` flag directly, and so needs separate handling.
Signed-off-by: Sean Quah <seanq@element.io>
`DirectServeHtmlResource` and `DirectServeJsonResource` both inherit
from `_AsyncResource`. These classes expect to be subclassed with
`_async_render_*` methods.
This commit has no effect on `JsonResource`, despite inheriting from
`_AsyncResource`. `JsonResource` has its own `_async_render` override
which will need to be updated separately.
Signed-off-by: Sean Quah <seanq@element.io>
Refactor how the `EventContext` class works, with the intention of reducing the amount of state we fetch from the DB during event processing.
The idea here is to get rid of the cached `current_state_ids` and `prev_state_ids` that live in the `EventContext`, and instead defer straight to the database (and its caching).
One change that may have a noticeable effect is that we now no longer prefill the `get_current_state_ids` cache on a state change. However, that query is relatively light, since its just a case of reading a table from the DB (unlike fetching state at an event which is more heavyweight). For deployments with workers this cache isn't even used.
Part of #12684
Also expose the `SynapseRequest` from `FakeChannel` in tests, so that
we can call `Request.connectionLost` to simulate a client disconnecting.
Signed-off-by: Sean Quah <seanq@element.io>
Fixes a regression from 8b309adb43 (#11660)
and b65acead42 (#11752) where events which
themselves were an edit or an annotation could have bundled aggregations calculated,
which is not allowed.
* Add mau_appservice_trial_days
* Add a test
* Tweaks
* changelog
* Ensure we sync after the delay
* Fix types
* Add config statement
* Fix test
* Reinstate logging that got removed
* Fix feature name
getClientIP was deprecated in Twisted 18.4.0, which also added
getClientAddress. The Synapse minimum version for Twisted is
currently 18.9.0, so all supported versions have the new API.
* Changes hidden read receipts to be a separate receipt type
(instead of a field on `m.read`).
* Updates the `/receipts` endpoint to accept `m.fully_read`.
* `m.login.jwt`, which was never specced and has been deprecated
since Synapse 1.16.0. (`org.matrix.login.jwt` can be used instead.)
* `uk.half-shot.msc2778.login.application_service`, which was
stabilized as part of the Matrix spec v1.2 release.
The `latest_event` field of the bundled aggregations for `m.thread` relations
did not include bundled aggregations itself. This resulted in clients needing to
immediately request the event from the server (and thus making it useless that
the latest event itself was serialized instead of just including an event ID).
I've seen a few errors which can only plausibly be explained by the calculated
event id for an event being different from the ID of the event in the
database. It should be cheap to check this, so let's do so and raise an
exception.
The status code of requests must always be set, regardless of client
disconnection, otherwise they will always be logged as 200!.
Broken for `respond_with_json` in
f48792eec4.
Broken for `respond_with_json_bytes` in
3e58ce72b4.
Broken for `respond_with_html_bytes` in
ea26e9a98b.
Signed-off-by: Sean Quah <seanq@element.io>
When configuring the return values of mocks, prefer awaitables from
`make_awaitable` over `defer.succeed`. `Deferred`s are only awaitable
once, so it is inappropriate for a mock to return the same `Deferred`
multiple times.
Also update `run_in_background` to support functions that return
arbitrary awaitables.
Signed-off-by: Sean Quah <seanq@element.io>
Over time we've begun to use newer versions of mypy, typeshed, stub
packages---and of course we've improved our own annotations. This makes
some type ignore comments no longer necessary. I have removed them.
There was one exception: a module that imports `select.epoll`. The
ignore is redundant on Linux, but I've kept it ignored for those of us
who work on the source tree using not-Linux. (#11771)
I'm more interested in the config line which enforces this. I want
unused ignores to be reported, because I think it's useful feedback when
annotating to know when you've fixed a problem you had to previously
ignore.
* Installing extras before typechecking
Lacking an easy way to install all extras generically, let's bite the bullet and
make install the hand-maintained `all` extra before typechecking.
Now that https://github.com/matrix-org/backend-meta/pull/6 is merged to
the release/v1 branch.
Multiple calls to `EventsWorkerStore._get_events_from_cache_or_db` can
reuse the same database fetch, which is initiated by the first call.
Ensure that cancelling the first call doesn't cancel the other calls
sharing the same database fetch.
Signed-off-by: Sean Quah <seanq@element.io>
This will mainly be useful when dealing with module callbacks, which are
all typed as returning `Awaitable`s instead of coroutines or
`Deferred`s.
Signed-off-by: Sean Quah <seanq@element.io>
When we join a room via the faster-joins mechanism, we end up with "partial
state" at some points on the event DAG. Many parts of the codebase need to
wait for the full state to load. So, we implement a mechanism to keep track of
which events have partial state, and wait for them to be fully-populated.
MSC2314 has now been closed, so we're backing out its implementation, which
originally happened in #6176.
Unfortunately it's not a direct revert, as that PR mixed in a bunch of
unrelated changes to tests etc.
In trying to use the MSC3026 busy presence status, the user's status
would be set back to 'online' next time they synced. This change makes
it so that syncing does not affect a user's presence status if it
is currently set to 'busy': it must be removed through the presence
API.
The MSC defers to implementations on the behaviour of busy presence,
so this ought to remain compatible with the MSC.
Consider the requester's ignored users when calculating the
bundled aggregations.
See #12285 / 4df10d3214
for corresponding changes for the `/relations` endpoint.
Of note:
* No untyped defs in `register_new_matrix_user`
This one might be contraversial. `request_registration` has three
dependency-injection arguments used for testing. I'm removing the
injection of the `requests` module and using `unitest.mock.patch` in the
test cases instead.
Doing `reveal_type(requests)` and `reveal_type(requests.get)` before the
change:
```
synapse/_scripts/register_new_matrix_user.py:45: note: Revealed type is "Any"
synapse/_scripts/register_new_matrix_user.py:46: note: Revealed type is "Any"
```
And after:
```
synapse/_scripts/register_new_matrix_user.py:44: note: Revealed type is "types.ModuleType"
synapse/_scripts/register_new_matrix_user.py:45: note: Revealed type is "def (url: Union[builtins.str, builtins.bytes], params: Union[Union[_typeshed.SupportsItems[Union[builtins.str, builtins.bytes, builtins.int, builtins.float], Union[builtins.str, builtins.bytes, builtins.int, builtins.float, typing.Iterable[Union[builtins.str, builtins.bytes, builtins.int, builtins.float]], None]], Tuple[Union[builtins.str, builtins.bytes, builtins.int, builtins.float], Union[builtins.str, builtins.bytes, builtins.int, builtins.float, typing.Iterable[Union[builtins.str, builtins.bytes, builtins.int, builtins.float]], None]], typing.Iterable[Tuple[Union[builtins.str, builtins.bytes, builtins.int, builtins.float], Union[builtins.str, builtins.bytes, builtins.int, builtins.float, typing.Iterable[Union[builtins.str, builtins.bytes, builtins.int, builtins.float]], None]]], builtins.str, builtins.bytes], None] =, data: Union[Any, None] =, headers: Union[Any, None] =, cookies: Union[Any, None] =, files: Union[Any, None] =, auth: Union[Any, None] =, timeout: Union[Any, None] =, allow_redirects: builtins.bool =, proxies: Union[Any, None] =, hooks: Union[Any, None] =, stream: Union[Any, None] =, verify: Union[Any, None] =, cert: Union[Any, None] =, json: Union[Any, None] =) -> requests.models.Response"
```
* Drive-by comment in `synapse.storage.types`
* No untyped defs in `synapse_port_db`
This was by far the most painful. I'm happy to break this up into
smaller pieces for review if it's not managable as-is.
Just after a task acquires a contended `Linearizer` lock, it sleeps.
If the task is cancelled during this sleep, we need to release the lock.
Signed-off-by: Sean Quah <seanq@element.io>
Refactor and convert `Linearizer` to async. This makes a `Linearizer`
cancellation bug easier to fix.
Also refactor to use an async context manager, which eliminates an
unlikely footgun where code that doesn't immediately use the context
manager could forget to release the lock.
Signed-off-by: Sean Quah <seanq@element.io>
This is a first step in dealing with #7721.
The idea is basically that rather than calculating the full set of users a device list update needs to be sent to up front, we instead simply record the rooms the user was in at the time of the change. This will allow a few things:
1. we can defer calculating the set of remote servers that need to be poked about the change; and
2. during `/sync` and `/keys/changes` we can avoid also avoid calculating users who share rooms with other users, and instead just look at the rooms that have changed.
However, care needs to be taken to correctly handle server downgrades. As such this PR writes to both `device_lists_changes_in_room` and the `device_lists_outbound_pokes` table synchronously. In a future release we can then bump the database schema compat version to `69` and then we can assume that the new `device_lists_changes_in_room` exists and is handled.
There is a temporary option to disable writing to `device_lists_outbound_pokes` synchronously, allowing us to test the new code path does work (and by implication upgrading to a future release and downgrading to this one will work correctly).
Note: Ideally we'd do the calculation of room to servers on a worker (e.g. the background worker), but currently only master can write to the `device_list_outbound_pokes` table.
There are a bunch of places we call get_success on an immediate value, which is unnecessary. Let's rip them out, and remove the redundant functionality in get_success and friends.
Switching to a sequence means there's no need to track `last_txn` on the
AS state table to generate new TXN IDs. This also means that there is
no longer contention between the AS scheduler and AS handler on updates
to the `application_services_state` table, which will prevent serialization
errors during the complete AS txn transaction.
It seems like calling `_get_state_group_for_events` for an event where the
state is unknown is an error. Accordingly, let's raise an exception rather than
silently returning an empty result.
If we're missing most of the events in the room state, then we may as well call the /state endpoint, instead of individually requesting each and every event.
The intention here is to avoid doing state lookups for outliers in
`/_matrix/federation/v1/event`. Unfortunately that's expanded into something of
a rewrite of `filter_events_for_server`, which ended up trying to do that
operation in a couple of places.
This endpoint was removed from MSC2675 before it was approved.
It is currently unspecified (even in any MSCs) and therefore subject to
removal. It is not implemented by any known clients.
This also changes the bundled aggregation format for `m.annotation`,
which previously included pagination tokens for the `/aggregations`
endpoint, which are no longer useful.
We fetch the thread summary in two phases:
1. The summary that is shared by all users (count of messages and latest event).
2. Whether the requesting user has participated in the thread.
There's no use in attempting step 2 for events which did not return a summary
from step 1.
An error occured if a filter was supplied with `event_fields` which did not include
`unsigned`.
In that case, bundled aggregations are still added as the spec states it is allowed
for servers to add additional fields.
To handle cancellation, we ensure that `after_callback`s and
`exception_callback`s are always run, since the transaction will
complete on another thread regardless of cancellation.
We also wait until everything is done before releasing the
`CancelledError`, so that logging contexts won't get used after they
have been finished.
Signed-off-by: Sean Quah <seanq@element.io>
* Moves the relation pagination tests to a separate class.
* Move the assertion of the response code into the `_send_relation` helper.
* Moves some helpers into the base-class.
These decorators mostly support cancellation already. Add cancellation
tests and fix use of finished logging contexts by delaying cancellation,
as suggested by @erikjohnston.
Signed-off-by: Sean Quah <seanq@element.io>
`delay_cancellation` behaves like `stop_cancellation`, except it
delays `CancelledError`s until the original `Deferred` resolves.
This is handy for unifying cleanup paths and ensuring that uncancelled
coroutines don't use finished logcontexts.
Signed-off-by: Sean Quah <seanq@element.io>