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

84 lines
2.7 KiB
Ruby

# frozen_string_literal: true
class ActivityPub::FetchRepliesService < BaseService
include JsonLdHelper
# Limit of fetched replies
MAX_REPLIES = 5
def call(reference_uri, collection_or_uri, max_pages: 1, allow_synchronous_requests: true, request_id: nil)
@reference_uri = reference_uri
@allow_synchronous_requests = allow_synchronous_requests
@items, n_pages = collection_items(collection_or_uri, max_pages: max_pages)
return if @items.nil?
@items = filter_replies(@items)
FetchReplyWorker.push_bulk(@items) { |reply_uri| [reply_uri, { 'request_id' => request_id }] }
[@items, n_pages]
end
private
def collection_items(collection_or_uri, max_pages: 1)
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)
items = []
n_pages = 1
while collection.is_a?(Hash)
items.concat(as_array(collection_page_items(collection)))
break if items.size >= MAX_REPLIES
break if n_pages >= max_pages
collection = collection['next'].present? ? fetch_collection(collection['next']) : nil
n_pages += 1
end
[items, n_pages]
end
def collection_page_items(collection)
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 non_matching_uri_hosts?(@reference_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, raise_on_error: :temporary)
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, raise_on_error: :temporary, request_options: { omit_query_string: false })
end
end
def filter_replies(items)
# 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?(@reference_uri, uri) }.take(MAX_REPLIES)
end
end