mastodon/app/services/activitypub/fetch_replies_service.rb

86 lines
2.8 KiB
Ruby

# frozen_string_literal: true
class ActivityPub::FetchRepliesService < BaseService
include JsonLdHelper
# Limit of fetched replies
MAX_REPLIES = 5
def call(parent_status, collection_or_uri, allow_synchronous_requests: true, request_id: nil, filter_by_host: true)
@account = parent_status.account
@allow_synchronous_requests = allow_synchronous_requests
@filter_by_host = filter_by_host
@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, max_pages = nil)
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)
all_items = []
n_pages = 1
while collection.is_a?(Hash)
items = case collection['type']
when 'Collection', 'CollectionPage'
collection['items']
when 'OrderedCollection', 'OrderedCollectionPage'
collection['orderedItems']
end
all_items.concat(as_array(items))
break if all_items.size >= MAX_REPLIES
break if !max_pages.nil? && n_pages >= max_pages
collection = collection['next'].present? ? fetch_collection(collection['next']) : nil
n_pages += 1
end
[all_items, n_pages]
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 @filter_by_host && 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: { omit_query_string: false })
end
end
def filtered_replies
if @filter_by_host
# 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(MAX_REPLIES)
else
@items.map { |item| value_or_id(item) }.take(MAX_REPLIES)
end
end
end