mastodon-glitch/app/services/activitypub/fetch_replies_service.rb

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# 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'
as_array(collection['items'])
when 'OrderedCollection', 'OrderedCollectionPage'
as_array(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 non_matching_uri_hosts?(@account.uri, collection_or_uri)
# NOTE: For backward compatibility reasons, Mastodon signs outgoing
# queries incorrectly by default.
#
# While this is relevant for all URLs with query strings, this is
# the only code path where this happens in practice.
#
# Therefore, retry with correct signatures if this fails.
begin
fetch_resource_without_id_validation(collection_or_uri, nil, true)
rescue Mastodon::UnexpectedResponseError => e
raise unless e.response && e.response.code == 401 && Addressable::URI.parse(collection_or_uri).query.present?
fetch_resource_without_id_validation(collection_or_uri, nil, true, request_options: { with_query_string: true })
end
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| non_matching_uri_hosts?(@account.uri, uri) }.take(5)
end
end