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mastodon/spec/models
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
..
admin Add option to include reported statuses in warning e-mail (#11639) 5 years ago
concerns Add follower synchronization mechanism (#14510) 4 years ago
form Change deletes to preserve soft-deleted statuses in unresolved reports (#11805) 5 years ago
web
account_alias_spec.rb Add account migration UI (#11846) 5 years ago
account_conversation_spec.rb
account_deletion_request_spec.rb Change account suspensions to be reversible by default (#14726) 4 years ago
account_domain_block_spec.rb
account_filter_spec.rb
account_migration_spec.rb Add account migration UI (#11846) 5 years ago
account_moderation_note_spec.rb
account_spec.rb Search account domain in lowercase (#13016) 5 years ago
account_stat_spec.rb Fix account counters being overwritten by parallel writes (#12045) 5 years ago
account_tag_stat_spec.rb
announcement_mute_spec.rb Add announcements (#12662) 5 years ago
announcement_reaction_spec.rb Add announcements (#12662) 5 years ago
announcement_spec.rb Add announcements (#12662) 5 years ago
backup_spec.rb
block_spec.rb
conversation_mute_spec.rb
conversation_spec.rb Revert "Remove conversation URI (#11423)" (#11424) 6 years ago
custom_emoji_category_spec.rb
custom_emoji_filter_spec.rb
custom_emoji_spec.rb
custom_filter_spec.rb
device_spec.rb Add E2EE API (#13820) 5 years ago
domain_allow_spec.rb Add whitelist mode (#11291) 6 years ago
domain_block_spec.rb Allow blocking TLDs, and fix TLD blocks not being editable (#12805) 5 years ago
email_domain_block_spec.rb
encrypted_message_spec.rb Add E2EE API (#13820) 5 years ago
export_spec.rb
favourite_spec.rb
featured_tag_spec.rb
follow_request_spec.rb Add option to be notified when a followed user posts (#13546) 4 years ago
follow_spec.rb
home_feed_spec.rb Fix performance of home feed regeneration (#12084) 5 years ago
identity_spec.rb
import_spec.rb
invite_spec.rb Change account suspensions to be reversible by default (#14726) 4 years ago
ip_block_spec.rb Add IP-based rules (#14963) 4 years ago
list_account_spec.rb
list_spec.rb
marker_spec.rb Add timeline read markers API (#11762) 5 years ago
media_attachment_spec.rb Fix media attachments without file being uploadable (#12562) 5 years ago
mention_spec.rb
mute_spec.rb
notification_spec.rb Add follow_request notification type (#12198) 5 years ago
one_time_key_spec.rb Add E2EE API (#13820) 5 years ago
poll_spec.rb
poll_vote_spec.rb Implement pending tests (#11415) 6 years ago
preview_card_spec.rb
public_feed_spec.rb Refactor how public and tag timelines are queried (#14728) 4 years ago
relationship_filter_spec.rb Fix followings list order | Issue #13538 (#13676) 5 years ago
relay_spec.rb
remote_follow_spec.rb Fix uncaught domain normalization error in remote follow (#11703) 5 years ago
report_filter_spec.rb
report_spec.rb Bump faker from 1.9.6 to 2.1.0 and update faker api (#11489) 6 years ago
scheduled_status_spec.rb
session_activation_spec.rb
setting_spec.rb
site_upload_spec.rb
status_pin_spec.rb
status_spec.rb Refactor how public and tag timelines are queried (#14728) 4 years ago
status_stat_spec.rb
system_key_spec.rb Add E2EE API (#13820) 5 years ago
tag_feed_spec.rb Refactor how public and tag timelines are queried (#14728) 4 years ago
tag_spec.rb Fix hashtags being split by ZWNJ character (#11821) 5 years ago
trending_tags_spec.rb Change trending hashtags to not disappear instantly after midnight (#11712) 5 years ago
unavailable_domain_spec.rb Change delivery failure tracking to work with hostnames instead of URLs (#13437) 5 years ago
user_invite_request_spec.rb
user_spec.rb Add WebAuthn as an alternative 2FA method (#14466) 4 years ago
webauthn_credentials_spec.rb Fix validates :sign_count of WebauthnCredential (#14806) 4 years ago