mastodon/app/services/activitypub/fetch_remote_account_service.rb
Eugen Rochko 802cf6a4c5
Improve federated ID validation (#8372)
* Fix URI not being sufficiently validated with prefetched JSON

* Add additional id validation to OStatus documents, when possible
2018-08-22 20:55:14 +02:00

62 lines
1.9 KiB
Ruby

# frozen_string_literal: true
class ActivityPub::FetchRemoteAccountService < BaseService
include JsonLdHelper
SUPPORTED_TYPES = %w(Application Group Organization Person Service).freeze
# Should be called when uri has already been checked for locality
# Does a WebFinger roundtrip on each call
def call(uri, id: true, prefetched_body: nil, break_on_redirect: false)
@json = if prefetched_body.nil?
fetch_resource(uri, id)
else
body_to_json(prefetched_body, compare_id: id ? uri : nil)
end
return if !supported_context? || !expected_type? || (break_on_redirect && @json['movedTo'].present?)
@uri = @json['id']
@username = @json['preferredUsername']
@domain = Addressable::URI.parse(@uri).normalized_host
return unless verified_webfinger?
ActivityPub::ProcessAccountService.new.call(@username, @domain, @json)
rescue Oj::ParseError
nil
end
private
def verified_webfinger?
webfinger = Goldfinger.finger("acct:#{@username}@#{@domain}")
confirmed_username, confirmed_domain = split_acct(webfinger.subject)
return webfinger.link('self')&.href == @uri if @username.casecmp(confirmed_username).zero? && @domain.casecmp(confirmed_domain).zero?
webfinger = Goldfinger.finger("acct:#{confirmed_username}@#{confirmed_domain}")
@username, @domain = split_acct(webfinger.subject)
self_reference = webfinger.link('self')
return false unless @username.casecmp(confirmed_username).zero? && @domain.casecmp(confirmed_domain).zero?
return false if self_reference&.href != @uri
true
rescue Goldfinger::Error
false
end
def split_acct(acct)
acct.gsub(/\Aacct:/, '').split('@')
end
def supported_context?
super(@json)
end
def expected_type?
equals_or_includes_any?(@json['type'], SUPPORTED_TYPES)
end
end