* Filter incoming Announce activities by relation to local activity

Reject if announcer is not followed by local accounts, and is not
from an enabled relay, and the object is not a local status

Follow-up to #10005

* Fix tests

Reject those from accounts with no local followers, from relays
that are not enabled, which do not address local accounts and are
not replies to accounts that do have local followers

* When self-boosting, embed original toot into Announce serialization

* Process unknown self-boosts from Announce object if it is more than an URI

* Add some self-boost specs

* Only serialize private toots in self-Announces

* Create Redisable

* Use #redis instead of Redis.current

Fix #9993
Fix #5654

* [test] add japanese hashtag testcase

* Only URLs extract with pre-escaped text

( https://github.com/tootsuite/mastodon/issues/9989 )

* Allow unicode characters in URL query strings

Fixes #8408

* Alternative approach to unicode support in urls

Adds PoC/idea to approch this problem.

* Add Tombstone model to remember object deletion

* Do not recreate a status if it has been deleted

* Record Tombstone for remote deleted items

Also, only record deleted items from same-host actors

* Clear an user's tombstones when their key change

Fix #9838

Fix #8609

* Reduce chances of race conditions when processing deleted toots

* Prevent race condition when processing deleted toots

* Ensure blocked user unfollows blocker if Block/Undo Block are processed out of order

* Add specs for Block causing unfollow and for out-of-order Block + Undo

* Do not LDS-sign Follow, Accept, Reject, Undo, Block

* Do not use LDS for Create activities of private toots

* Minor cleanup

* Ignore unsigned activities instead of misattributing them

* Use status.distributable? instead of querying visibility directly

* Add setting to not aggregate reblogs

Fixes #9222

* Handle cases where user is nil in add_to_home and add_to_list

* Add hint for setting_aggregate_reblogs option

* Reword setting_aggregate_reblogs label

Follow-up to #9329

* Fix connect timeout not being enforced

The loop was catching the timeout exception that should stop execution, so the next IP would no longer be within a timed block, which led to requests taking much longer than 10 seconds.

* Use timeout on each IP attempt, but limit to 2 attempts

* Fix code style issue

* Do not break Request#perform if no block given

* Update method stub in spec for Request

* Move timeout inside the begin/rescue block

* Use Resolv::DNS with timeout of 1 to get IP addresses

* Update Request spec to stub Resolv::DNS instead of Addrinfo

* Fix Resolve::DNS stubs in Request spec

The failure rate in Sidekiq is too high

* Reduce connect timeout from 10s to 1s

* Limit failing signature verifications per source IP

Fixes #9115

* Fix missing `mention` argument when processing incoming Create activities

* Fix typo (param → params)

Fix #9091

* Add silent column to mentions

* Save silent mentions in ActivityPub Create handler and optimize it

Move networking calls out of the database transaction

* Add "limited" visibility level masked as "private" in the API

Unlike DMs, limited statuses are pushed into home feeds. The access
control rules between direct and limited statuses is almost the same,
except for counter and conversation logic

* Ensure silent column is non-null, add spec

* Ensure filters don't check silent mentions for blocks/mutes

As those are "this person is also allowed to see" rather than "this
person is involved", therefore does not warrant filtering

* Clean up code

* Use Status#active_mentions to limit returned mentions

* Fix code style issues

* Use Status#active_mentions in Notification

And remove stream_entry eager-loading from Notification

* Downcase signed_headers string before building the signed string

The HTTP Signatures draft does not mandate the “headers” field to be downcased,
but mandates the header field names to be downcased in the signed string, which
means that prior to this patch, Mastodon could fail to process signatures from
some compliant clients. It also means that it would not actually check the
Digest of non-compliant clients that wouldn't use a lowercased Digest field
name.

Thankfully, I don't know of any such client.

* Revert "Remove dead code (#8919)"

This reverts commit a00ce8c9.

* Restore time window checking, change it to 12 hours

By checking the Date header, we can prevent replaying old vulnerable
signatures. The focus is to prevent replaying old vulnerable requests
from software that has been fixed in the meantime, so a somewhat long
window should be fine and accounts for timezone misconfiguration.

* Escape users' URLs when formatting them

Fixes possible HTML injection

* Escape all string interpolations in Formatter class

Slightly improve performance by reducing class allocations
from repeated Formatter#encode calls

* Fix code style issues

Regression from #8951

Mention and emoji code may perform network calls, but does not need
to do that inside the database transaction. This may improve availability
of database connections when using pgBouncer in transaction mode.

* Add conversations API

* Add web UI for conversations

* Add test for conversations API

* Add tests for ConversationAccount

* Improve web UI

* Rename ConversationAccount to AccountConversation

* Remove conversations on block and mute

* Change last_status_id to be a denormalization of status_ids

* Add optimistic locking

* Force use language detector if account is remote

* Set unknown remote toot's language as nil