chinwagsocial/app/services/activitypub/fetch_replies_service.rb
Claire a8a3e86216
Fix unbounded recursion in post discovery (#23507)
* Add a limit to how many posts can get fetched as a result of a single request

* Add tests

* Always pass `request_id` when processing `Announce` activities

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Co-authored-by: nametoolong <nametoolong@users.noreply.github.com>
2023-02-10 22:16:47 +01:00

49 lines
1.5 KiB
Ruby

# frozen_string_literal: true
class ActivityPub::FetchRepliesService < BaseService
include JsonLdHelper
def call(parent_status, collection_or_uri, allow_synchronous_requests: true, request_id: nil)
@account = parent_status.account
@allow_synchronous_requests = allow_synchronous_requests
@items = collection_items(collection_or_uri)
return if @items.nil?
FetchReplyWorker.push_bulk(filtered_replies) { |reply_uri| [reply_uri, { 'request_id' => request_id}] }
@items
end
private
def collection_items(collection_or_uri)
collection = fetch_collection(collection_or_uri)
return unless collection.is_a?(Hash)
collection = fetch_collection(collection['first']) if collection['first'].present?
return unless collection.is_a?(Hash)
case collection['type']
when 'Collection', 'CollectionPage'
collection['items']
when 'OrderedCollection', 'OrderedCollectionPage'
collection['orderedItems']
end
end
def fetch_collection(collection_or_uri)
return collection_or_uri if collection_or_uri.is_a?(Hash)
return unless @allow_synchronous_requests
return if invalid_origin?(collection_or_uri)
fetch_resource_without_id_validation(collection_or_uri, nil, true)
end
def filtered_replies
# Only fetch replies to the same server as the original status to avoid
# amplification attacks.
# Also limit to 5 fetched replies to limit potential for DoS.
@items.map { |item| value_or_id(item) }.reject { |uri| invalid_origin?(uri) }.take(5)
end
end