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mastodon/spec/controllers
ThibG ca56527140
Add follower synchronization mechanism (#14510)
* Add support for followers synchronization on the receiving end

Check the `collectionSynchronization` attribute on `Create` and `Announce`
activities and synchronize followers from provided collection if possible.

* Add tests for followers synchronization on the receiving end

* Add support for follower synchronization on the sender's end

* Add tests for the sending end

* Switch from AS attributes to HTTP header

Replace the custom `collectionSynchronization` ActivityStreams attribute by
an HTTP header (`X-AS-Collection-Synchronization`) with the same syntax as
the `Signature` header and the following fields:
- `collectionId` to specify which collection to synchronize
- `digest` for the SHA256 hex-digest of the list of followers known on the
   receiving instance (where “receiving instance” is determined by accounts
   sharing the same host name for their ActivityPub actor `id`)
- `url` of a collection that should be fetched by the instance actor

Internally, move away from the webfinger-based `domain` attribute and use
account `uri` prefix to group accounts.

* Add environment variable to disable followers synchronization

Since the whole mechanism relies on some new preconditions that, in some
extremely rare cases, might not be met, add an environment variable
(DISABLE_FOLLOWERS_SYNCHRONIZATION) to disable the mechanism altogether and
avoid followers being incorrectly removed.

The current conditions are:
1. all managed accounts' actor `id` and inbox URL have the same URI scheme and
   netloc.
2. all accounts whose actor `id` or inbox URL share the same URI scheme and
   netloc as a managed account must be managed by the same Mastodon instance
   as well.

As far as Mastodon is concerned, breaking those preconditions require extensive
configuration changes in the reverse proxy and might also cause other issues.

Therefore, this environment variable provides a way out for people with highly
unusual configurations, and can be safely ignored for the overwhelming majority
of Mastodon administrators.

* Only set follower synchronization header on non-public statuses

This is to avoid unnecessary computations and allow Follow-related
activities to be handled by the usual codepath instead of going through
the synchronization mechanism (otherwise, any Follow/Undo/Accept activity
would trigger the synchronization mechanism even if processing the activity
itself would be enough to re-introduce synchronization)

* Change how ActivityPub::SynchronizeFollowersService handles follow requests

If the remote lists a local follower which we only know has sent a follow
request, consider the follow request as accepted instead of sending an Undo.

* Integrate review feeback

- rename X-AS-Collection-Synchronization to Collection-Synchronization
- various minor refactoring and code style changes

* Only select required fields when computing followers_hash

* Use actor URI rather than webfinger domain in synchronization endpoint

* Change hash computation to be a XOR of individual hashes

Makes it much easier to be memory-efficient, and avoid sorting discrepancy issues.

* Marginally improve followers_hash computation speed

* Further improve hash computation performances by using pluck_each
4 years ago
..
activitypub Add follower synchronization mechanism (#14510) 4 years ago
admin Add WebAuthn as an alternative 2FA method (#14466) 5 years ago
api Add option to be notified when a followed user posts (#13546) 5 years ago
auth Change account suspensions to be reversible by default (#14726) 5 years ago
concerns Change account suspensions to be reversible by default (#14726) 5 years ago
oauth Bump doorkeeper from 5.3.3 to 5.4.0 (#13733) 5 years ago
settings Refactor settings controllers (#14767) 5 years ago
well_known Remove dependency on goldfinger gem (#14919) 5 years ago
about_controller_spec.rb Compensate for scrollbar disappearing when media modal visible (#8100) 7 years ago
account_follow_controller_spec.rb Add specific rate limits for posting and following (#13172) 5 years ago
account_unfollow_controller_spec.rb Cover AccountUnfollowController more in spec (#3228) 8 years ago
accounts_controller_spec.rb Do not serve account actors at all in limited federation mode (#14800) 5 years ago
application_controller_spec.rb Change to always returns html document in error pages (#12214) 5 years ago
authorize_interactions_controller_spec.rb Optimize the process of following someone (#9220) 6 years ago
emojis_controller_spec.rb Misc. typos (#8694) 7 years ago
follower_accounts_controller_spec.rb Hide blocked users from more places (#12733) 5 years ago
following_accounts_controller_spec.rb Hide blocked users from more places (#12733) 5 years ago
home_controller_spec.rb Fix blurhash and autoplay not working on public pages (#11585) 6 years ago
intents_controller_spec.rb Add remote interaction dialog for toots (#8202) 7 years ago
invites_controller_spec.rb Lint pass (#8876) 7 years ago
manifests_controller_spec.rb Use raw status code on have_http_status (#7214) 7 years ago
media_controller_spec.rb Fix media attachments enumeration (#14254) 5 years ago
media_proxy_controller_spec.rb Fix media attachments enumeration (#14254) 5 years ago
relationships_controller_spec.rb Add relationship manager UI (#10268) 6 years ago
remote_follow_controller_spec.rb Remove dependency on goldfinger gem (#14919) 5 years ago
remote_interaction_controller_spec.rb Add specs for RemoteInteractionController (#9524) 6 years ago
shares_controller_spec.rb Fix blurhash and autoplay not working on public pages (#11585) 6 years ago
statuses_controller_spec.rb Fix RSS feeds not being cachable (#14368) 5 years ago
tags_controller_spec.rb Redesign public hashtag page to use a masonry layout (#9822) 6 years ago