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119 lines
4.4 KiB
Ruby
119 lines
4.4 KiB
Ruby
# frozen_string_literal: true
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class FetchLinkCardForURLService < BaseService
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include Redisable
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include Lockable
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def call(url)
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@original_url = Addressable::URI.parse(url).normalize
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return if bad_url?(@original_url)
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@url = @original_url.to_s
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with_redis_lock("fetch:#{@original_url}") do
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@card = PreviewCard.find_by(url: @url)
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process_url if @card.nil? || @card.updated_at <= 2.weeks.ago || @card.missing_image?
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end
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@card
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rescue *Mastodon::HTTP_CONNECTION_ERRORS, Addressable::URI::InvalidURIError, Mastodon::HostValidationError, Mastodon::LengthValidationError, Encoding::UndefinedConversionError, ActiveRecord::RecordInvalid => e
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Rails.logger.debug { "Error fetching link #{@url}: #{e}" }
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nil
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end
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private
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def process_url
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@card ||= PreviewCard.new(url: @url)
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attempt_oembed || attempt_opengraph
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end
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def html
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return @html if defined?(@html)
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headers = {
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'Accept' => 'text/html',
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'Accept-Language' => "#{I18n.default_locale}, *;q=0.5",
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'User-Agent' => "#{Mastodon::Version.user_agent} Bot",
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}
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@html = Request.new(:get, @url).add_headers(headers).perform do |res|
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next unless res.code == 200 && res.mime_type == 'text/html'
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# We follow redirects, and ideally we want to save the preview card for
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# the destination URL and not any link shortener in-between, so here
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# we set the URL to the one of the last response in the redirect chain
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@url = res.request.uri.to_s
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@card = PreviewCard.find_or_initialize_by(url: @url) if @card.url != @url
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@html_charset = res.charset
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res.truncated_body
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end
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end
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def bad_url?(uri)
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# Avoid local instance URLs and invalid URLs
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uri.host.blank? || TagManager.instance.local_url?(uri.to_s) || !%w(http https).include?(uri.scheme)
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end
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def attempt_oembed
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service = FetchOEmbedService.new
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url_domain = Addressable::URI.parse(@url).normalized_host
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cached_endpoint = Rails.cache.read("oembed_endpoint:#{url_domain}")
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embed = service.call(@url, cached_endpoint: cached_endpoint) unless cached_endpoint.nil?
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embed ||= service.call(@url, html: html) unless html.nil?
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return false if embed.nil?
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url = Addressable::URI.parse(service.endpoint_url)
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@card.type = embed[:type]
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@card.title = embed[:title] || ''
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@card.author_name = embed[:author_name] || ''
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@card.author_url = embed[:author_url].present? ? (url + embed[:author_url]).to_s : ''
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@card.provider_name = embed[:provider_name] || ''
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@card.provider_url = embed[:provider_url].present? ? (url + embed[:provider_url]).to_s : ''
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@card.width = 0
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@card.height = 0
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case @card.type
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when 'link'
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@card.image_remote_url = (url + embed[:thumbnail_url]).to_s if embed[:thumbnail_url].present?
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when 'photo'
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return false if embed[:url].blank?
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@card.embed_url = (url + embed[:url]).to_s
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@card.image_remote_url = (url + embed[:url]).to_s
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@card.width = embed[:width].presence || 0
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@card.height = embed[:height].presence || 0
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when 'video'
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@card.width = embed[:width].presence || 0
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@card.height = embed[:height].presence || 0
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@card.html = Sanitize.fragment(embed[:html], Sanitize::Config::MASTODON_OEMBED)
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@card.image_remote_url = (url + embed[:thumbnail_url]).to_s if embed[:thumbnail_url].present?
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when 'rich'
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# Most providers rely on <script> tags, which is a no-no
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return false
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end
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@card.save_with_optional_image!
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end
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def attempt_opengraph
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return if html.nil?
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link_details_extractor = LinkDetailsExtractor.new(@url, @html, @html_charset)
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domain = Addressable::URI.parse(link_details_extractor.canonical_url).normalized_host
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provider = PreviewCardProvider.matching_domain(domain)
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linked_account = ResolveAccountService.new.call(link_details_extractor.author_account, suppress_errors: true) if link_details_extractor.author_account.present?
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@card = PreviewCard.find_or_initialize_by(url: link_details_extractor.canonical_url) if link_details_extractor.canonical_url != @card.url
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@card.assign_attributes(link_details_extractor.to_preview_card_attributes)
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@card.author_account = linked_account if linked_account&.can_be_attributed_from?(domain) || provider&.trendable?
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@card.save_with_optional_image! unless @card.title.blank? && @card.html.blank?
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end
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end
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