chinwagsocial/app/services/activitypub/fetch_remote_status_service.rb

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# frozen_string_literal: true
class ActivityPub::FetchRemoteStatusService < BaseService
include JsonLdHelper
include Redisable
DISCOVERIES_PER_REQUEST = 1000
# Should be called when uri has already been checked for locality
def call(uri, id: true, prefetched_body: nil, on_behalf_of: nil, expected_actor_uri: nil, request_id: nil)
@request_id = request_id || "#{Time.now.utc.to_i}-status-#{uri}"
@json = begin
if prefetched_body.nil?
fetch_resource(uri, id, on_behalf_of)
else
body_to_json(prefetched_body, compare_id: id ? uri : nil)
end
end
return unless supported_context?
actor_uri = nil
activity_json = nil
object_uri = nil
if expected_object_type?
actor_uri = value_or_id(first_of_value(@json['attributedTo']))
activity_json = { 'type' => 'Create', 'actor' => actor_uri, 'object' => @json }
object_uri = uri_from_bearcap(@json['id'])
elsif expected_activity_type?
actor_uri = value_or_id(first_of_value(@json['actor']))
activity_json = @json
object_uri = uri_from_bearcap(value_or_id(@json['object']))
end
return if activity_json.nil? || object_uri.nil? || !trustworthy_attribution?(@json['id'], actor_uri)
return if expected_actor_uri.present? && actor_uri != expected_actor_uri
return ActivityPub::TagManager.instance.uri_to_resource(object_uri, Status) if ActivityPub::TagManager.instance.local_uri?(object_uri)
actor = account_from_uri(actor_uri)
return if actor.nil? || actor.suspended?
# If we fetched a status that already exists, then we need to treat the
# activity as an update rather than create
activity_json['type'] = 'Update' if equals_or_includes_any?(activity_json['type'], %w(Create)) && Status.where(uri: object_uri, account_id: actor.id).exists?
with_redis do |redis|
discoveries = redis.incr("status_discovery_per_request:#{@request_id}")
redis.expire("status_discovery_per_request:#{@request_id}", 5.minutes.seconds)
return nil if discoveries > DISCOVERIES_PER_REQUEST
end
ActivityPub::Activity.factory(activity_json, actor, request_id: @request_id).perform
end
private
def trustworthy_attribution?(uri, attributed_to)
return false if uri.nil? || attributed_to.nil?
Addressable::URI.parse(uri).normalized_host.casecmp(Addressable::URI.parse(attributed_to).normalized_host).zero?
end
def account_from_uri(uri)
actor = ActivityPub::TagManager.instance.uri_to_resource(uri, Account)
actor = ActivityPub::FetchRemoteAccountService.new.call(uri, id: true, request_id: @request_id) if actor.nil? || actor.possibly_stale?
actor
end
def supported_context?
super(@json)
end
def expected_activity_type?
equals_or_includes_any?(@json['type'], %w(Create Announce))
end
def expected_object_type?
equals_or_includes_any?(@json['type'], ActivityPub::Activity::Create::SUPPORTED_TYPES + ActivityPub::Activity::Create::CONVERTED_TYPES)
end
end