# frozen_string_literal: true class FetchLinkCardService < BaseService include Redisable include Lockable URL_PATTERN = %r{ (#{Twitter::TwitterText::Regex[:valid_url_preceding_chars]}) # $1 preceding chars ( # $2 URL (https?:\/\/) # $3 Protocol (required) (#{Twitter::TwitterText::Regex[:valid_domain]}) # $4 Domain(s) (?::(#{Twitter::TwitterText::Regex[:valid_port_number]}))? # $5 Port number (optional) (/#{Twitter::TwitterText::Regex[:valid_url_path]}*)? # $6 URL Path and anchor (\?#{Twitter::TwitterText::Regex[:valid_url_query_chars]}*#{Twitter::TwitterText::Regex[:valid_url_query_ending_chars]})? # $7 Query String ) }iox def call(status) @status = status @original_url = parse_urls return if @original_url.nil? || @status.preview_cards.any? @url = @original_url.to_s with_lock("fetch:#{@original_url}") do @card = PreviewCard.find_by(url: @url) process_url if @card.nil? || @card.updated_at <= 2.weeks.ago || @card.missing_image? end attach_card if @card&.persisted? rescue HTTP::Error, OpenSSL::SSL::SSLError, Addressable::URI::InvalidURIError, Mastodon::HostValidationError, Mastodon::LengthValidationError => e Rails.logger.debug { "Error fetching link #{@original_url}: #{e}" } nil end private def process_url @card ||= PreviewCard.new(url: @url) attempt_oembed || attempt_opengraph end def html return @html if defined?(@html) Request.new(:get, @url).add_headers('Accept' => 'text/html', 'User-Agent' => Mastodon::Version.user_agent + ' Bot').perform do |res| # We follow redirects, and ideally we want to save the preview card for # the destination URL and not any link shortener in-between, so here # we set the URL to the one of the last response in the redirect chain @url = res.request.uri.to_s @card = PreviewCard.find_or_initialize_by(url: @url) if @card.url != @url if res.code == 200 && res.mime_type == 'text/html' @html_charset = res.charset @html = res.body_with_limit else @html_charset = nil @html = nil end end end def attach_card @status.preview_cards << @card Rails.cache.delete(@status) Trends.links.register(@status) end def parse_urls urls = begin if @status.local? @status.text.scan(URL_PATTERN).map { |array| Addressable::URI.parse(array[1]).normalize } else document = Nokogiri::HTML(@status.text) links = document.css('a') links.filter_map { |a| Addressable::URI.parse(a['href']) unless skip_link?(a) }.filter_map(&:normalize) end end urls.reject { |uri| bad_url?(uri) }.first end def bad_url?(uri) # Avoid local instance URLs and invalid URLs uri.host.blank? || TagManager.instance.local_url?(uri.to_s) || !%w(http https).include?(uri.scheme) end def mention_link?(anchor) @status.mentions.any? do |mention| anchor['href'] == ActivityPub::TagManager.instance.url_for(mention.account) end end def skip_link?(anchor) # Avoid links for hashtags and mentions (microformats) anchor['rel']&.include?('tag') || anchor['class']&.match?(/u-url|h-card/) || mention_link?(anchor) end def attempt_oembed service = FetchOEmbedService.new url_domain = Addressable::URI.parse(@url).normalized_host cached_endpoint = Rails.cache.read("oembed_endpoint:#{url_domain}") embed = service.call(@url, cached_endpoint: cached_endpoint) unless cached_endpoint.nil? embed ||= service.call(@url, html: html) unless html.nil? return false if embed.nil? url = Addressable::URI.parse(service.endpoint_url) @card.type = embed[:type] @card.title = embed[:title] || '' @card.author_name = embed[:author_name] || '' @card.author_url = embed[:author_url].present? ? (url + embed[:author_url]).to_s : '' @card.provider_name = embed[:provider_name] || '' @card.provider_url = embed[:provider_url].present? ? (url + embed[:provider_url]).to_s : '' @card.width = 0 @card.height = 0 case @card.type when 'link' @card.image_remote_url = (url + embed[:thumbnail_url]).to_s if embed[:thumbnail_url].present? when 'photo' return false if embed[:url].blank? @card.embed_url = (url + embed[:url]).to_s @card.image_remote_url = (url + embed[:url]).to_s @card.width = embed[:width].presence || 0 @card.height = embed[:height].presence || 0 when 'video' @card.width = embed[:width].presence || 0 @card.height = embed[:height].presence || 0 @card.html = Sanitize.fragment(embed[:html], Sanitize::Config::MASTODON_OEMBED) @card.image_remote_url = (url + embed[:thumbnail_url]).to_s if embed[:thumbnail_url].present? when 'rich' # Most providers rely on <script> tags, which is a no-no return false end @card.save_with_optional_image! end def attempt_opengraph return if html.nil? link_details_extractor = LinkDetailsExtractor.new(@url, @html, @html_charset) @card = PreviewCard.find_or_initialize_by(url: link_details_extractor.canonical_url) if link_details_extractor.canonical_url != @card.url @card.assign_attributes(link_details_extractor.to_preview_card_attributes) @card.save_with_optional_image! unless @card.title.blank? && @card.html.blank? end end