hometown/app/services/fetch_remote_status_service.rb
Eugen Rochko 2af4f3c4e2 Improve shared status verification (#2525)
* Instead of parsing shared status contents verbatim, make roundtrip
to purported original URL. Confirm that the "original" URL is from the
same domain as the author it claims to be from.

* Fix obvious typo, add comment

* Use URI look-up first

* Add test, update Goldfinger dependency to make less useless HTTP requests per Webfinger lookup
2017-04-27 17:06:47 +02:00

58 lines
1.5 KiB
Ruby

# frozen_string_literal: true
class FetchRemoteStatusService < BaseService
def call(url, prefetched_body = nil)
if prefetched_body.nil?
atom_url, body = FetchAtomService.new.call(url)
else
atom_url = url
body = prefetched_body
end
return nil if atom_url.nil?
process_atom(atom_url, body)
end
private
def process_atom(url, body)
Rails.logger.debug "Processing Atom for remote status at #{url}"
xml = Nokogiri::XML(body)
xml.encoding = 'utf-8'
account = extract_author(url, xml)
return nil if account.nil?
statuses = ProcessFeedService.new.call(body, account)
statuses.first
end
def extract_author(url, xml)
url_parts = Addressable::URI.parse(url).normalize
username = xml.at_xpath('//xmlns:author/xmlns:name').try(:content)
domain = url_parts.host
return nil if username.nil?
Rails.logger.debug "Going to webfinger #{username}@#{domain}"
account = FollowRemoteAccountService.new.call("#{username}@#{domain}")
# If the author's confirmed URLs do not match the domain of the URL
# we are reading this from, abort
return nil unless confirmed_domain?(domain, account)
account
rescue Nokogiri::XML::XPath::SyntaxError
Rails.logger.debug 'Invalid XML or missing namespace'
nil
end
def confirmed_domain?(domain, account)
domain.casecmp(account.domain).zero? || domain.casecmp(Addressable::URI.parse(account.remote_url).normalize.host).zero?
end
end