The idea here is that we pass the `max_stream_id` to everything, and only use the stream ID of the particular event to figure out *when* the max stream position has caught up to the event and we can notify people about it.

This is to maintain the distinction between the position of an item in the stream (i.e. event A has stream ID 513) and a token that can be used to partition the stream (i.e. give me all events after stream ID 352). This distinction becomes important when the tokens are more complicated than a single number, which they will be once we start tracking the position of multiple writers in the tokens.

The valid operations here are:

1. Is a position before or after a token
2. Fetching all events between two tokens
3. Merging multiple tokens to get the "max", i.e. `C = max(A, B)` means that for all positions P where P is before A *or* before B, then P is before C.

Future PR will change the token type to a dedicated type.

This PR adds a confirmation step to resetting your user password between clicking the link in your email and your password actually being reset.

This is to better align our password reset flow with the industry standard of requiring a confirmation from the user after email validation.

If a file cannot be thumbnailed for some reason (e.g. the file is empty), then
catch the exception and convert it to a reasonable error message for the client.

Removes the `user_joined_room` and stops calling it since there are no observers.

Also cleans-up some other unused signals and related code.

`pusher_pool.on_new_notifications` expected a min and max stream ID, however that was not what we were passing in. Instead, let's just pass it the current max stream ID and have it track the last stream ID it got passed.

I believe that it mostly worked as we called the function for every event. However, it would break for events that got persisted out of order, i.e, that were persisted but the max stream ID wasn't incremented as not all preceding events had finished persisting, and push for that event would be delayed until another event got pushed to the effected users.

This reverts commit e7fd336a.

Dendrite's implementing MSC2753 over at https://github.com/matrix-org/dendrite/pull/1370 to prove the implementation for MSC purposes, and so sytest has sprouted tests for it over at https://github.com/matrix-org/sytest/pull/944. But we don't want them to run on synapse until synapse implements it.

Don't remember `enabled` of deleted push rules and properly return 404 for missing push rules in `.../actions` and `.../enabled` (#7796)

Signed-off-by: Olivier Wilkinson (reivilibre) <olivier@librepush.net>

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

This fixes an issue where different methods (crop/scale) overwrite each other.

This first tries the new path. If that fails and we are looking for a
remote thumbnail, it tries the old path. If that still isn't found, it
continues as normal.

This should probably be removed in the future, after some of the newer
thumbnails were generated with the new path on most deployments. Then
the overhead should be minimal if the other thumbnails need to be
regenerated.

Signed-off-by: Nicolas Werner <nicolas.werner@hotmail.de>

The intention here is to change `StreamToken.room_key` to be a `RoomStreamToken` in a future PR, but that is a big enough change without this refactoring too.

This is a config option ported over from DINUM's Sydent: https://github.com/matrix-org/sydent/pull/285

They've switched to validating 3PIDs via Synapse rather than Sydent, and would like to retain this functionality.

This original purpose for this change is phishing prevention. This solution could also potentially be replaced by a similar one to https://github.com/matrix-org/synapse/pull/8004, but across all `*/submit_token` endpoint.

This option may still be useful to enterprise even with that safeguard in place though, if they want to be absolutely sure that their employees don't follow links to other domains.

This removes `SourcePaginationConfig` and `get_pagination_rows`. The reasoning behind this is that these generic classes/functions erased the types of the IDs it used (i.e. instead of passing around `StreamToken` it'd pass in e.g. `token.room_key`, which don't have uniform types).

Update `log_function` to use the right factory to create log records, to make
sure that they have `request` attributes.

Fixes: #8267.

It did not correctly handle IDs finishing being persisted out of
order, resulting in the `current_position` lagging until new IDs are
persisted.

Synapse 1.20.0rc1 (2020-09-08)
==============================

Removal warning
---------------

Some older clients used a [disallowed character](https://matrix.org/docs/spec/client_server/r0.6.1#post-matrix-client-r0-register-email-requesttoken) (`:`) in the `client_secret` parameter of various endpoints. The incorrect behaviour was allowed for backwards compatibility, but is now being removed from Synapse as most users have updated their client. Further context can be found at [\#6766](https://github.com/matrix-org/synapse/issues/6766).

Features
--------

- Add an endpoint to query your shared rooms with another user as an implementation of [MSC2666](https://github.com/matrix-org/matrix-doc/pull/2666). ([\#7785](https://github.com/matrix-org/synapse/issues/7785))
- Iteratively encode JSON to avoid blocking the reactor. ([\#8013](https://github.com/matrix-org/synapse/issues/8013), [\#8116](https://github.com/matrix-org/synapse/issues/8116))
- Add support for shadow-banning users (ignoring any message send requests). ([\#8034](https://github.com/matrix-org/synapse/issues/8034), [\#8092](https://github.com/matrix-org/synapse/issues/8092), [\#8095](https://github.com/matrix-org/synapse/issues/8095), [\#8142](https://github.com/matrix-org/synapse/issues/8142), [\#8152](https://github.com/matrix-org/synapse/issues/8152), [\#8157](https://github.com/matrix-org/synapse/issues/8157), [\#8158](https://github.com/matrix-org/synapse/issues/8158), [\#8176](https://github.com/matrix-org/synapse/issues/8176))
- Use the default template file when its equivalent is not found in a custom template directory. ([\#8037](https://github.com/matrix-org/synapse/issues/8037), [\#8107](https://github.com/matrix-org/synapse/issues/8107), [\#8252](https://github.com/matrix-org/synapse/issues/8252))
- Add unread messages count to sync responses, as specified in [MSC2654](https://github.com/matrix-org/matrix-doc/pull/2654). ([\#8059](https://github.com/matrix-org/synapse/issues/8059), [\#8254](https://github.com/matrix-org/synapse/issues/8254), [\#8270](https://github.com/matrix-org/synapse/issues/8270), [\#8274](https://github.com/matrix-org/synapse/issues/8274))
- Optimise `/federation/v1/user/devices/` API by only returning devices with encryption keys. ([\#8198](https://github.com/matrix-org/synapse/issues/8198))

Bugfixes
--------

- Fix a memory leak by limiting the length of time that messages will be queued for a remote server that has been unreachable. ([\#7864](https://github.com/matrix-org/synapse/issues/7864))
- Fix `Re-starting finished log context PUT-nnnn` warning when event persistence failed. ([\#8081](https://github.com/matrix-org/synapse/issues/8081))
- Synapse now correctly enforces the valid characters in the `client_secret` parameter used in various endpoints. ([\#8101](https://github.com/matrix-org/synapse/issues/8101))
- Fix a bug introduced in v1.7.2 impacting message retention policies that would allow federated homeservers to dictate a retention period that's lower than the configured minimum allowed duration in the configuration file. ([\#8104](https://github.com/matrix-org/synapse/issues/8104))
- Fix a long-standing bug where invalid JSON would be accepted by Synapse. ([\#8106](https://github.com/matrix-org/synapse/issues/8106))
- Fix a bug introduced in Synapse v1.12.0 which could cause `/sync` requests to fail with a 404 if you had a very old outstanding room invite. ([\#8110](https://github.com/matrix-org/synapse/issues/8110))
- Return a proper error code when the rooms of an invalid group are requested. ([\#8129](https://github.com/matrix-org/synapse/issues/8129))
- Fix a bug which could cause a leaked postgres connection if synapse was set to daemonize. ([\#8131](https://github.com/matrix-org/synapse/issues/8131))
- Clarify the error code if a user tries to register with a numeric ID. This bug was introduced in v1.15.0. ([\#8135](https://github.com/matrix-org/synapse/issues/8135))
- Fix a bug where appservices with ratelimiting disabled would still be ratelimited when joining rooms. This bug was introduced in v1.19.0. ([\#8139](https://github.com/matrix-org/synapse/issues/8139))
- Fix logging in via OpenID Connect with a provider that uses integer user IDs. ([\#8190](https://github.com/matrix-org/synapse/issues/8190))
- Fix a longstanding bug where user directory updates could break when unexpected profile data was included in events. ([\#8223](https://github.com/matrix-org/synapse/issues/8223))
- Fix a longstanding bug where stats updates could break when unexpected profile data was included in events. ([\#8226](https://github.com/matrix-org/synapse/issues/8226))
- Fix slow start times for large servers by removing a table scan of the `users` table from startup code. ([\#8271](https://github.com/matrix-org/synapse/issues/8271))

Updates to the Docker image
---------------------------

- Fix builds of the Docker image on non-x86 platforms. ([\#8144](https://github.com/matrix-org/synapse/issues/8144))
- Added curl for healthcheck support and readme updates for the change. Contributed by @maquis196. ([\#8147](https://github.com/matrix-org/synapse/issues/8147))

Improved Documentation
----------------------

- Link to matrix-synapse-rest-password-provider in the password provider documentation. ([\#8111](https://github.com/matrix-org/synapse/issues/8111))
- Updated documentation to note that Synapse does not follow `HTTP 308` redirects due to an upstream library not supporting them. Contributed by Ryan Cole. ([\#8120](https://github.com/matrix-org/synapse/issues/8120))
- Explain better what GDPR-erased means when deactivating a user. ([\#8189](https://github.com/matrix-org/synapse/issues/8189))

Internal Changes
----------------

- Add filter `name` to the `/users` admin API, which filters by user ID or displayname. Contributed by Awesome Technologies Innovationslabor GmbH. ([\#7377](https://github.com/matrix-org/synapse/issues/7377), [\#8163](https://github.com/matrix-org/synapse/issues/8163))
- Reduce run times of some unit tests by advancing the reactor a fewer number of times. ([\#7757](https://github.com/matrix-org/synapse/issues/7757))
- Don't fail `/submit_token` requests on incorrect session ID if `request_token_inhibit_3pid_errors` is turned on. ([\#7991](https://github.com/matrix-org/synapse/issues/7991))
- Convert various parts of the codebase to async/await. ([\#8071](https://github.com/matrix-org/synapse/issues/8071), [\#8072](https://github.com/matrix-org/synapse/issues/8072), [\#8074](https://github.com/matrix-org/synapse/issues/8074), [\#8075](https://github.com/matrix-org/synapse/issues/8075), [\#8076](https://github.com/matrix-org/synapse/issues/8076), [\#8087](https://github.com/matrix-org/synapse/issues/8087), [\#8100](https://github.com/matrix-org/synapse/issues/8100), [\#8119](https://github.com/matrix-org/synapse/issues/8119), [\#8121](https://github.com/matrix-org/synapse/issues/8121), [\#8133](https://github.com/matrix-org/synapse/issues/8133), [\#8156](https://github.com/matrix-org/synapse/issues/8156), [\#8162](https://github.com/matrix-org/synapse/issues/8162), [\#8166](https://github.com/matrix-org/synapse/issues/8166), [\#8168](https://github.com/matrix-org/synapse/issues/8168), [\#8173](https://github.com/matrix-org/synapse/issues/8173), [\#8191](https://github.com/matrix-org/synapse/issues/8191), [\#8192](https://github.com/matrix-org/synapse/issues/8192), [\#8193](https://github.com/matrix-org/synapse/issues/8193), [\#8194](https://github.com/matrix-org/synapse/issues/8194), [\#8195](https://github.com/matrix-org/synapse/issues/8195), [\#8197](https://github.com/matrix-org/synapse/issues/8197), [\#8199](https://github.com/matrix-org/synapse/issues/8199), [\#8200](https://github.com/matrix-org/synapse/issues/8200), [\#8201](https://github.com/matrix-org/synapse/issues/8201), [\#8202](https://github.com/matrix-org/synapse/issues/8202), [\#8207](https://github.com/matrix-org/synapse/issues/8207), [\#8213](https://github.com/matrix-org/synapse/issues/8213), [\#8214](https://github.com/matrix-org/synapse/issues/8214))
- Remove some unused database functions. ([\#8085](https://github.com/matrix-org/synapse/issues/8085))
- Add type hints to various parts of the codebase. ([\#8090](https://github.com/matrix-org/synapse/issues/8090), [\#8127](https://github.com/matrix-org/synapse/issues/8127), [\#8187](https://github.com/matrix-org/synapse/issues/8187), [\#8241](https://github.com/matrix-org/synapse/issues/8241), [\#8140](https://github.com/matrix-org/synapse/issues/8140), [\#8183](https://github.com/matrix-org/synapse/issues/8183), [\#8232](https://github.com/matrix-org/synapse/issues/8232), [\#8235](https://github.com/matrix-org/synapse/issues/8235), [\#8237](https://github.com/matrix-org/synapse/issues/8237), [\#8244](https://github.com/matrix-org/synapse/issues/8244))
- Return the previous stream token if a non-member event is a duplicate. ([\#8093](https://github.com/matrix-org/synapse/issues/8093), [\#8112](https://github.com/matrix-org/synapse/issues/8112))
- Separate `get_current_token` into two since there are two different use cases for it. ([\#8113](https://github.com/matrix-org/synapse/issues/8113))
- Remove `ChainedIdGenerator`. ([\#8123](https://github.com/matrix-org/synapse/issues/8123))
- Reduce the amount of whitespace in JSON stored and sent in responses. ([\#8124](https://github.com/matrix-org/synapse/issues/8124))
- Update the test federation client to handle streaming responses. ([\#8130](https://github.com/matrix-org/synapse/issues/8130))
- Micro-optimisations to `get_auth_chain_ids`. ([\#8132](https://github.com/matrix-org/synapse/issues/8132))
- Refactor `StreamIdGenerator` and `MultiWriterIdGenerator` to have the same interface. ([\#8161](https://github.com/matrix-org/synapse/issues/8161))
- Add functions to `MultiWriterIdGen` used by events stream. ([\#8164](https://github.com/matrix-org/synapse/issues/8164), [\#8179](https://github.com/matrix-org/synapse/issues/8179))
- Fix tests that were broken due to the merge of 1.19.1. ([\#8167](https://github.com/matrix-org/synapse/issues/8167))
- Make `SlavedIdTracker.advance` have the same interface as `MultiWriterIDGenerator`. ([\#8171](https://github.com/matrix-org/synapse/issues/8171))
- Remove unused `is_guest` parameter from, and add safeguard to, `MessageHandler.get_room_data`. ([\#8174](https://github.com/matrix-org/synapse/issues/8174), [\#8181](https://github.com/matrix-org/synapse/issues/8181))
- Standardize the mypy configuration. ([\#8175](https://github.com/matrix-org/synapse/issues/8175))
- Refactor some of `LoginRestServlet`'s helper methods, and move them to `AuthHandler` for easier reuse. ([\#8182](https://github.com/matrix-org/synapse/issues/8182))
- Fix `wait_for_stream_position` to allow multiple waiters on same stream ID. ([\#8196](https://github.com/matrix-org/synapse/issues/8196))
- Make `MultiWriterIDGenerator` work for streams that use negative values. ([\#8203](https://github.com/matrix-org/synapse/issues/8203))
- Refactor queries for device keys and cross-signatures. ([\#8204](https://github.com/matrix-org/synapse/issues/8204), [\#8205](https://github.com/matrix-org/synapse/issues/8205), [\#8222](https://github.com/matrix-org/synapse/issues/8222), [\#8224](https://github.com/matrix-org/synapse/issues/8224), [\#8225](https://github.com/matrix-org/synapse/issues/8225), [\#8231](https://github.com/matrix-org/synapse/issues/8231), [\#8233](https://github.com/matrix-org/synapse/issues/8233), [\#8234](https://github.com/matrix-org/synapse/issues/8234))
- Fix type hints for functions decorated with `@cached`. ([\#8240](https://github.com/matrix-org/synapse/issues/8240))
- Remove obsolete `order` field from federation send queues. ([\#8245](https://github.com/matrix-org/synapse/issues/8245))
- Stop sub-classing from object. ([\#8249](https://github.com/matrix-org/synapse/issues/8249))
- Add more logging to debug slow startup. ([\#8264](https://github.com/matrix-org/synapse/issues/8264))
- Do not attempt to upgrade database schema on worker processes. ([\#8266](https://github.com/matrix-org/synapse/issues/8266), [\#8276](https://github.com/matrix-org/synapse/issues/8276))

By importing from canonicaljson the simplejson module was still being used
in some situations. After this change the std lib json is consistenty used
throughout Synapse.

Rename 'populate_stats_process_rooms_2' background job back to 'populate_stats_process_rooms' again (#8243)

Fixes https://github.com/matrix-org/synapse/issues/8238

Alongside the delta file, some changes were also necessary to the codebase to remove references to the now defunct `populate_stats_process_rooms_2` background job. Thankfully the latter doesn't seem to have made it into any documentation yet :)

This takes about 10 seconds in the best case; often more.

Fix unread counts making sync fail if the value of the `unread_count`
column in `event_push_summary` is `None`.

I'm hoping this will provide some pointers for debugging
https://github.com/matrix-org/synapse/issues/7968.

The version 1.3.0 has a bug with unicode charecters:
```
>>> from canonicaljson import encode_pretty_printed_json
>>> encode_pretty_printed_json({'a': 'à'})
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/erdnaxeli/.pyenv/versions/3.6.7/lib/python3.6/site-packages/canonicaljson.py", line 96, in encode_pretty_printed_json
    return _pretty_encoder.encode(json_object).encode("ascii")
UnicodeEncodeError: 'ascii' codec can't encode character '\xe0' in position 12: ordinal not in range(128)
```

Signed-off-by: Alexandre Morignot <erdnaxeli@cervoi.se>

Co-authored-by: Alexandre Morignot <erdnaxeli@cervoi.se>

Fixes: #6467