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mastodon/app/lib/activitypub/activity/undo.rb
ThibG 5d9acc0ce4
Fix not handling Undo on some activity types when they aren't inlined (#14346)
* Fix not handling Undo on some activity types when they aren't inlined

When receiving an Undo for a non-inlined activity, try looking it up in
database using the URI. The queries are ad-hoc because we don't have a global
index of object URIs, and not all activity types are stored in database with
an index on their URI.

Announces are just statuses, and have an index on URIs, so this check can
be done efficiently.

Accepts cannot be handled at all because we don't record their URI at any
point.

Follows don't have an index on URI, but they have an index on the issuing
account, which should make such queries largely manageable.

Likes don't have an index on URI, they have an index on the issuing account,
but the number of favs per account may be very high, so I decided not to
handle that.

Blocks don't have an index on URI, but they have an index on the issuing
account, which should make such queries largely manageable.

In all cases, if an Undo could not be handled properly, we call `delete_later!`
because that does not require us to know more than the URI of the undone
property.

* Add tests

* Make newer blocks overwrite older ones

Allows re-synchronizing block info by re-blocking and un-blocking again
when the original Undo Block has been lost.
2020-07-22 11:45:35 +02:00

132 lines
3.1 KiB
Ruby

# frozen_string_literal: true
class ActivityPub::Activity::Undo < ActivityPub::Activity
def perform
case @object['type']
when 'Announce'
undo_announce
when 'Accept'
undo_accept
when 'Follow'
undo_follow
when 'Like'
undo_like
when 'Block'
undo_block
when nil
handle_reference
end
end
private
def handle_reference
# Some implementations do not inline the object, and as we don't have a
# global index, we have to guess what object it is.
return if object_uri.nil?
try_undo_announce || try_undo_accept || try_undo_follow || try_undo_like || try_undo_block || delete_later!(object_uri)
end
def try_undo_announce
status = Status.where.not(reblog_of_id: nil).find_by(uri: object_uri, account: @account)
if status.present?
RemoveStatusService.new.call(status)
true
else
false
end
end
def try_undo_accept
# We can't currently handle `Undo Accept` as we don't record `Accept`'s uri
false
end
def try_undo_follow
follow = @account.follow_requests.find_by(uri: object_uri) || @account.active_relationships.find_by(uri: object_uri)
if follow.present?
follow.destroy
true
else
false
end
end
def try_undo_like
# There is an index on accounts, but an account may have *many* favs, so this may be too costly
false
end
def try_undo_block
block = @account.block_relationships.find_by(uri: object_uri)
if block.present?
UnblockService.new.call(@account, block.target_account)
true
else
false
end
end
def undo_announce
return if object_uri.nil?
status = Status.find_by(uri: object_uri, account: @account)
status ||= Status.find_by(uri: @object['atomUri'], account: @account) if @object.is_a?(Hash) && @object['atomUri'].present?
if status.nil?
delete_later!(object_uri)
else
RemoveStatusService.new.call(status)
end
end
def undo_accept
::Follow.find_by(target_account: @account, uri: target_uri)&.revoke_request!
end
def undo_follow
target_account = account_from_uri(target_uri)
return if target_account.nil? || !target_account.local?
if @account.following?(target_account)
@account.unfollow!(target_account)
elsif @account.requested?(target_account)
FollowRequest.find_by(account: @account, target_account: target_account)&.destroy
else
delete_later!(object_uri)
end
end
def undo_like
status = status_from_uri(target_uri)
return if status.nil? || !status.account.local?
if @account.favourited?(status)
favourite = status.favourites.where(account: @account).first
favourite&.destroy
else
delete_later!(object_uri)
end
end
def undo_block
target_account = account_from_uri(target_uri)
return if target_account.nil? || !target_account.local?
if @account.blocking?(target_account)
UnblockService.new.call(@account, target_account)
else
delete_later!(object_uri)
end
end
def target_uri
@target_uri ||= value_or_id(@object['object'])
end
end