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mastodon/app/services
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
concerns Fix activity not being signed (#13948) 5 years ago
keys Add E2EE API (#13820) 5 years ago
account_search_service.rb Fix following restriction not working when exact match in account search (#14394) 5 years ago
after_block_domain_from_account_service.rb Fix account domain block not properly unfollowing accounts from domain (#14304) 5 years ago
after_block_service.rb Refactor feed manager (#14761) 4 years ago
after_unallow_domain_service.rb Change account suspensions to be reversible by default (#14726) 4 years ago
app_sign_up_service.rb Add IP-based rules (#14963) 4 years ago
authorize_follow_service.rb
backup_service.rb Add E2EE API (#13820) 5 years ago
base_service.rb
batched_remove_status_service.rb Fix not publishing update of remote timeline (#13745) 5 years ago
block_domain_service.rb Change account suspensions to be reversible by default (#14726) 4 years ago
block_service.rb
bootstrap_timeline_service.rb Admin setting to disable default follows (#12566) 5 years ago
clear_domain_media_service.rb Make domain block/silence/reject-media code more robust (#13424) 5 years ago
delete_account_service.rb Change account suspensions to be reversible by default (#14726) 4 years ago
deliver_to_device_service.rb Add E2EE API (#13820) 5 years ago
fan_out_on_write_service.rb Change own direct-visibility statuses to be in the home feed again (#14711) 4 years ago
favourite_service.rb Add option to be notified when a followed user posts (#13546) 4 years ago
fetch_link_card_service.rb Bump rubocop from 0.86.0 to 0.88.0 (#14412) 4 years ago
fetch_oembed_service.rb Fix link crawler not specifying accepted content-type (#12646) 5 years ago
fetch_remote_status_service.rb Fix an error when ActivityPub::FetchRemoteStatusService url is called with nil (#12652) 5 years ago
fetch_resource_service.rb Fix not being able to resolve public resources in development environment (#13505) 5 years ago
follow_service.rb Add option to be notified when a followed user posts (#13546) 4 years ago
import_service.rb Add option to be notified when a followed user posts (#13546) 4 years ago
move_service.rb
mute_service.rb Add duration parameter to muting. (#13831) 4 years ago
notify_service.rb Add option to be notified when a followed user posts (#13546) 4 years ago
post_status_service.rb Fix media not being marked sensitive when client sets a CW but no text (#13277) 5 years ago
precompute_feed_service.rb Refactor feed manager (#14761) 4 years ago
process_hashtags_service.rb
process_mentions_service.rb Remove dependency on goldfinger gem (#14919) 4 years ago
reblog_service.rb Add option to be notified when a followed user posts (#13546) 4 years ago
reject_follow_service.rb
remove_status_service.rb Fix not publishing update of remote timeline (#13745) 5 years ago
report_service.rb
resolve_account_service.rb Remove dependency on goldfinger gem (#14919) 4 years ago
resolve_url_service.rb Fix some timeouts when searching URLs by limiting some database queries (#13253) 5 years ago
search_service.rb Fix hashtag search performing account search as well (#13758) 5 years ago
suspend_account_service.rb Change account suspensions to be reversible by default (#14726) 4 years ago
tag_search_service.rb
unallow_domain_service.rb Fix removing allowed domains being done synchronously (#14302) 5 years ago
unblock_domain_service.rb
unblock_service.rb
unfavourite_service.rb
unfollow_service.rb
unmute_service.rb
unsuspend_account_service.rb Change account suspensions to be reversible by default (#14726) 4 years ago
update_account_service.rb Bump rubocop from 0.86.0 to 0.88.0 (#14412) 4 years ago
verify_link_service.rb
vote_service.rb Fix invalid votes from the API being accepted (#12601) 5 years ago