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mastodon/app/services/activitypub/fetch_replies_service.rb
ThibG 9d3c6f1849 Improved remote thread fetching (#10106)
* Fetch up to 5 replies when discovering a new remote status

This is used for resolving threads downwards. The originating
server must add a “replies” attributes with such replies for it to
be useful.

* Add some tests for ActivityPub::FetchRepliesWorker

* Add specs for ActivityPub::FetchRepliesService

* Serialize up to 5 public self-replies for ActivityPub notes

* Add specs for ActivityPub::NoteSerializer

* Move exponential backoff logic to a worker concern

* Fetch first page of paginated collections when fetching thread replies

* Add specs for paginated collections in replies

* Move Note replies serialization to a first CollectionPage

The collection isn't actually paginable yet as it has no id nor
a `next` field. This may come in another PR.

* Use pluck(:uri) instead of map(&:uri) to improve performances

* Fix fetching replies when they are in a CollectionPage
2019-02-28 15:22:21 +01:00

61 lines
1.7 KiB
Ruby

# frozen_string_literal: true
class ActivityPub::FetchRepliesService < BaseService
include JsonLdHelper
def call(parent_status, collection_or_uri, allow_synchronous_requests = true)
@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)
@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)
collection = fetch_resource_without_id_validation(collection_or_uri)
raise Mastodon::UnexpectedResponseError if collection.nil?
collection
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
def invalid_origin?(url)
return true if unsupported_uri_scheme?(url)
needle = Addressable::URI.parse(url).host
haystack = Addressable::URI.parse(@account.uri).host
!haystack.casecmp(needle).zero?
end
end