# frozen_string_literal: true class FetchLinkCardService < BaseService URL_PATTERN = %r{ ( # $1 URL (https?:\/\/)? # $2 Protocol (optional) (#{Twitter::Regex[:valid_domain]}) # $3 Domain(s) (?::(#{Twitter::Regex[:valid_port_number]}))? # $4 Port number (optional) (/#{Twitter::Regex[:valid_url_path]}*)? # $5 URL Path and anchor (\?#{Twitter::Regex[:valid_url_query_chars]}*#{Twitter::Regex[:valid_url_query_ending_chars]})? # $6 Query String ) }iox def call(status) @status = status @url = parse_urls return if @url.nil? || @status.preview_cards.any? @url = @url.to_s RedisLock.acquire(lock_options) do |lock| if lock.acquired? @card = PreviewCard.find_by(url: @url) process_url if @card.nil? || @card.updated_at <= 2.weeks.ago end end attach_card if @card&.persisted? rescue HTTP::Error, Addressable::URI::InvalidURIError => e Rails.logger.debug "Error fetching link #{@url}: #{e}" nil end private def process_url @card ||= PreviewCard.new(url: @url) res = Request.new(:head, @url).perform return if res.code != 200 || res.mime_type != 'text/html' attempt_oembed || attempt_opengraph end def attach_card @status.preview_cards << @card end def parse_urls if @status.local? urls = @status.text.scan(URL_PATTERN).map { |array| Addressable::URI.parse(array[0]).normalize } else html = Nokogiri::HTML(@status.text) links = html.css('a') urls = links.map { |a| Addressable::URI.parse(a['href']).normalize unless skip_link?(a) }.compact 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 skip_link?(a) # Avoid links for hashtags and mentions (microformats) a['rel']&.include?('tag') || a['class']&.include?('u-url') end def attempt_oembed response = OEmbed::Providers.get(@url) return false unless response.respond_to?(:type) @card.type = response.type @card.title = response.respond_to?(:title) ? response.title : '' @card.author_name = response.respond_to?(:author_name) ? response.author_name : '' @card.author_url = response.respond_to?(:author_url) ? response.author_url : '' @card.provider_name = response.respond_to?(:provider_name) ? response.provider_name : '' @card.provider_url = response.respond_to?(:provider_url) ? response.provider_url : '' @card.width = 0 @card.height = 0 case @card.type when 'link' @card.image = URI.parse(response.thumbnail_url) if response.respond_to?(:thumbnail_url) when 'photo' @card.url = response.url @card.width = response.width.presence || 0 @card.height = response.height.presence || 0 when 'video' @card.width = response.width.presence || 0 @card.height = response.height.presence || 0 @card.html = Formatter.instance.sanitize(response.html, Sanitize::Config::MASTODON_OEMBED) when 'rich' # Most providers rely on <script> tags, which is a no-no return false end @card.save_with_optional_image! rescue OEmbed::NotFound false end def attempt_opengraph response = Request.new(:get, @url).perform return if response.code != 200 || response.mime_type != 'text/html' html = response.to_s detector = CharlockHolmes::EncodingDetector.new detector.strip_tags = true guess = detector.detect(html, response.charset) page = Nokogiri::HTML(html, nil, guess&.fetch(:encoding, nil)) if meta_property(page, 'twitter:player') @card.type = :video @card.width = meta_property(page, 'twitter:player:width') || 0 @card.height = meta_property(page, 'twitter:player:height') || 0 @card.html = content_tag(:iframe, nil, src: meta_property(page, 'twitter:player'), width: @card.width, height: @card.height, allowtransparency: 'true', scrolling: 'no', frameborder: '0') else @card.type = :link @card.image_remote_url = meta_property(page, 'og:image') if meta_property(page, 'og:image') end @card.title = meta_property(page, 'og:title').presence || page.at_xpath('//title')&.content || '' @card.description = meta_property(page, 'og:description').presence || meta_property(page, 'description') || '' return if @card.title.blank? && @card.html.blank? @card.save_with_optional_image! end def meta_property(html, property) html.at_xpath("//meta[@property=\"#{property}\"]")&.attribute('content')&.value || html.at_xpath("//meta[@name=\"#{property}\"]")&.attribute('content')&.value end def lock_options { redis: Redis.current, key: "fetch:#{@url}" } end end