forked from fedi/mastodon
ec059317fa
* Add tests * Fix some link previews being incorrectly generated from different prior links PR #12403 added a cache to avoid redundant queries when the OEmbed endpoint can be guessed from the URL. This caching mechanism is not perfectly correct as there is no guarantee that all pages from a given domain share the same OEmbed provider endpoint. This PR prevents the FetchOEmbedService from caching OEmbed endpoint that cannot be generalized by replacing a fully-qualified URL from the endpoint's parameters, greatly reducing the number of incorrect cached generalizations.
114 lines
2.9 KiB
Ruby
114 lines
2.9 KiB
Ruby
# frozen_string_literal: true
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class FetchOEmbedService
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ENDPOINT_CACHE_EXPIRES_IN = 24.hours.freeze
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URL_REGEX = /(=(http[s]?(%3A|:)(\/\/|%2F%2F)))([^&]*)/i.freeze
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attr_reader :url, :options, :format, :endpoint_url
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def call(url, options = {})
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@url = url
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@options = options
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if @options[:cached_endpoint]
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parse_cached_endpoint!
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else
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discover_endpoint!
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end
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fetch!
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end
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private
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def discover_endpoint!
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return if html.nil?
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@format = @options[:format]
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page = Nokogiri::HTML(html)
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if @format.nil? || @format == :json
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@endpoint_url ||= page.at_xpath('//link[@type="application/json+oembed"]')&.attribute('href')&.value
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@format ||= :json if @endpoint_url
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end
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if @format.nil? || @format == :xml
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@endpoint_url ||= page.at_xpath('//link[@type="text/xml+oembed"]')&.attribute('href')&.value
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@format ||= :xml if @endpoint_url
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end
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return if @endpoint_url.blank?
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@endpoint_url = begin
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base_url = Addressable::URI.parse(@url)
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# If the OEmbed endpoint is given as http but the URL we opened
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# was served over https, we can assume OEmbed will be available
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# through https as well
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(base_url + @endpoint_url).tap do |absolute_url|
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absolute_url.scheme = base_url.scheme if base_url.scheme == 'https'
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end.to_s
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end
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cache_endpoint!
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rescue Addressable::URI::InvalidURIError
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@endpoint_url = nil
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end
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def parse_cached_endpoint!
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cached = @options[:cached_endpoint]
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return if cached[:endpoint].nil? || cached[:format].nil?
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@endpoint_url = Addressable::Template.new(cached[:endpoint]).expand(url: @url).to_s
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@format = cached[:format]
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end
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def cache_endpoint!
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return unless URL_REGEX.match?(@endpoint_url)
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url_domain = Addressable::URI.parse(@url).normalized_host
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endpoint_hash = {
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endpoint: @endpoint_url.gsub(URL_REGEX, '={url}'),
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format: @format,
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}
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Rails.cache.write("oembed_endpoint:#{url_domain}", endpoint_hash, expires_in: ENDPOINT_CACHE_EXPIRES_IN)
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end
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def fetch!
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return if @endpoint_url.blank?
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body = Request.new(:get, @endpoint_url).perform do |res|
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res.code != 200 ? nil : res.body_with_limit
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end
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validate(parse_for_format(body)) if body.present?
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rescue Oj::ParseError, Ox::ParseError
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nil
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end
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def parse_for_format(body)
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case @format
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when :json
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Oj.load(body, mode: :strict)&.with_indifferent_access
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when :xml
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Ox.load(body, mode: :hash_no_attrs)&.with_indifferent_access&.dig(:oembed)
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end
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end
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def validate(oembed)
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oembed if oembed[:version] == '1.0' && oembed[:type].present?
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end
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def html
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return @html if defined?(@html)
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@html = @options[:html] || Request.new(:get, @url).add_headers('Accept' => 'text/html').perform do |res|
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res.code != 200 || res.mime_type != 'text/html' ? nil : res.body_with_limit
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end
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end
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end
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