Add support for structured data and more OpenGraph tags to link cards (#16938)

Save preview cards under their canonical URL

Increase max redirects to follow from 2 to 3
This commit is contained in:
Eugen Rochko 2021-11-05 23:23:05 +01:00 committed by GitHub
parent 989c67d29d
commit 39cdf61ab7
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5 changed files with 260 additions and 52 deletions

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@ -0,0 +1,200 @@
# frozen_string_literal: true
class LinkDetailsExtractor
include ActionView::Helpers::TagHelper
class StructuredData
def initialize(data)
@data = data
end
def headline
json['headline']
end
def description
json['description']
end
def image
obj = first_of_value(json['image'])
return obj['url'] if obj.is_a?(Hash)
obj
end
def date_published
json['datePublished']
end
def date_modified
json['dateModified']
end
def author_name
author['name']
end
def author_url
author['url']
end
def publisher_name
publisher['name']
end
private
def author
first_of_value(json['author']) || {}
end
def publisher
first_of_value(json['publisher']) || {}
end
def first_of_value(arr)
arr.is_a?(Array) ? arr.first : arr
end
def json
@json ||= Oj.load(@data)
end
end
def initialize(original_url, html, html_charset)
@original_url = Addressable::URI.parse(original_url)
@html = html
@html_charset = html_charset
end
def to_preview_card_attributes
{
title: title || '',
description: description || '',
image_remote_url: image,
type: type,
width: width || 0,
height: height || 0,
html: html || '',
provider_name: provider_name || '',
provider_url: provider_url || '',
author_name: author_name || '',
author_url: author_url || '',
embed_url: embed_url || '',
}
end
def type
player_url.present? ? :video : :link
end
def html
player_url.present? ? content_tag(:iframe, src: player_url, width: width, height: height, allowtransparency: 'true', scrolling: 'no', frameborder: '0') : nil
end
def width
opengraph_tag('twitter:player:width')
end
def height
opengraph_tag('twitter:player:height')
end
def title
structured_data&.headline || opengraph_tag('og:title') || document.xpath('//title').map(&:content).first
end
def description
structured_data&.description || opengraph_tag('og:description') || meta_tag('description')
end
def image
valid_url_or_nil(opengraph_tag('og:image'))
end
def canonical_url
valid_url_or_nil(opengraph_tag('og:url') || link_tag('canonical'), same_origin_only: true) || @original_url.to_s
end
def provider_name
structured_data&.publisher_name || opengraph_tag('og:site_name')
end
def provider_url
valid_url_or_nil(host_to_url(opengraph_tag('og:site')))
end
def author_name
structured_data&.author_name || opengraph_tag('og:author') || opengraph_tag('og:author:username')
end
def author_url
structured_data&.author_url
end
def embed_url
valid_url_or_nil(opengraph_tag('twitter:player:stream'))
end
private
def player_url
valid_url_or_nil(opengraph_tag('twitter:player'))
end
def host_to_url(str)
return if str.blank?
str.start_with?(/https?:\/\//) ? str : "http://#{str}"
end
def valid_url_or_nil(str, same_origin_only: false)
return if str.blank?
url = @original_url + Addressable::URI.parse(str)
return if url.host.blank? || !%w(http https).include?(url.scheme) || (same_origin_only && url.host != @original_url.host)
url.to_s
rescue Addressable::URI::InvalidURIError
nil
end
def link_tag(name)
document.xpath("//link[@rel=\"#{name}\"]").map { |link| link['href'] }.first
end
def opengraph_tag(name)
document.xpath("//meta[@property=\"#{name}\" or @name=\"#{name}\"]").map { |meta| meta['content'] }.first
end
def meta_tag(name)
document.xpath("//meta[@name=\"#{name}\"]").map { |meta| meta['content'] }.first
end
def structured_data
@structured_data ||= begin
json_ld = document.xpath('//script[@type="application/ld+json"]').map(&:content).first
json_ld.present? ? StructuredData.new(json_ld) : nil
end
end
def document
@document ||= Nokogiri::HTML(@html, nil, encoding)
end
def encoding
@encoding ||= begin
guess = detector.detect(@html, @html_charset)
guess&.fetch(:confidence, 0).to_i > 60 ? guess&.fetch(:encoding, nil) : nil
end
end
def detector
@detector ||= CharlockHolmes::EncodingDetector.new.tap do |detector|
detector.strip_tags = true
end
end
end

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@ -94,7 +94,7 @@ class Request
end end
def http_client def http_client
HTTP.use(:auto_inflate).timeout(TIMEOUT.dup).follow(max_hops: 2) HTTP.use(:auto_inflate).timeout(TIMEOUT.dup).follow(max_hops: 3)
end end
end end

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@ -14,11 +14,11 @@ class FetchLinkCardService < BaseService
def call(status) def call(status)
@status = status @status = status
@url = parse_urls @original_url = parse_urls
return if @url.nil? || @status.preview_cards.any? return if @original_url.nil? || @status.preview_cards.any?
@url = @url.to_s @url = @original_url.to_s
RedisLock.acquire(lock_options) do |lock| RedisLock.acquire(lock_options) do |lock|
if lock.acquired? if lock.acquired?
@ -31,7 +31,7 @@ class FetchLinkCardService < BaseService
attach_card if @card&.persisted? attach_card if @card&.persisted?
rescue HTTP::Error, OpenSSL::SSL::SSLError, Addressable::URI::InvalidURIError, Mastodon::HostValidationError, Mastodon::LengthValidationError => e rescue HTTP::Error, OpenSSL::SSL::SSLError, Addressable::URI::InvalidURIError, Mastodon::HostValidationError, Mastodon::LengthValidationError => e
Rails.logger.debug "Error fetching link #{@url}: #{e}" Rails.logger.debug "Error fetching link #{@original_url}: #{e}"
nil nil
end end
@ -47,6 +47,12 @@ class FetchLinkCardService < BaseService
return @html if defined?(@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| 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.to_s
@card = PreviewCard.find_or_initialize_by(url: @url) if @card.url != @url
if res.code == 200 && res.mime_type == 'text/html' if res.code == 200 && res.mime_type == 'text/html'
@html_charset = res.charset @html_charset = res.charset
@html = res.body_with_limit @html = res.body_with_limit
@ -63,12 +69,15 @@ class FetchLinkCardService < BaseService
end end
def parse_urls def parse_urls
urls = begin
if @status.local? if @status.local?
urls = @status.text.scan(URL_PATTERN).map { |array| Addressable::URI.parse(array[1]).normalize } @status.text.scan(URL_PATTERN).map { |array| Addressable::URI.parse(array[1]).normalize }
else else
html = Nokogiri::HTML(@status.text) document = Nokogiri::HTML(@status.text)
links = html.css('a') links = document.css('a')
urls = links.filter_map { |a| Addressable::URI.parse(a['href']) unless skip_link?(a) }.filter_map(&:normalize)
links.filter_map { |a| Addressable::URI.parse(a['href']) unless skip_link?(a) }.filter_map(&:normalize)
end
end end
urls.reject { |uri| bad_url?(uri) }.first urls.reject { |uri| bad_url?(uri) }.first
@ -79,18 +88,16 @@ class FetchLinkCardService < BaseService
uri.host.blank? || TagManager.instance.local_url?(uri.to_s) || !%w(http https).include?(uri.scheme) uri.host.blank? || TagManager.instance.local_url?(uri.to_s) || !%w(http https).include?(uri.scheme)
end end
# rubocop:disable Naming/MethodParameterName def mention_link?(anchor)
def mention_link?(a)
@status.mentions.any? do |mention| @status.mentions.any? do |mention|
a['href'] == ActivityPub::TagManager.instance.url_for(mention.account) anchor['href'] == ActivityPub::TagManager.instance.url_for(mention.account)
end end
end end
def skip_link?(a) def skip_link?(anchor)
# Avoid links for hashtags and mentions (microformats) # Avoid links for hashtags and mentions (microformats)
a['rel']&.include?('tag') || a['class']&.match?(/u-url|h-card/) || mention_link?(a) anchor['rel']&.include?('tag') || anchor['class']&.match?(/u-url|h-card/) || mention_link?(anchor)
end end
# rubocop:enable Naming/MethodParameterName
def attempt_oembed def attempt_oembed
service = FetchOEmbedService.new service = FetchOEmbedService.new
@ -139,42 +146,14 @@ class FetchLinkCardService < BaseService
def attempt_opengraph def attempt_opengraph
return if html.nil? return if html.nil?
detector = CharlockHolmes::EncodingDetector.new link_details_extractor = LinkDetailsExtractor.new(@url, @html, @html_charset)
detector.strip_tags = true
guess = detector.detect(@html, @html_charset) @card = PreviewCard.find_or_initialize_by(url: link_details_extractor.canonical_url) if link_details_extractor.canonical_url != @card.url
encoding = guess&.fetch(:confidence, 0).to_i > 60 ? guess&.fetch(:encoding, nil) : nil @card.assign_attributes(link_details_extractor.to_preview_card_attributes)
page = Nokogiri::HTML(@html, nil, encoding) @card.save_with_optional_image! unless @card.title.blank? && @card.html.blank?
player_url = meta_property(page, 'twitter:player')
if player_url && !bad_url?(Addressable::URI.parse(player_url))
@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: player_url,
width: @card.width,
height: @card.height,
allowtransparency: 'true',
scrolling: 'no',
frameborder: '0')
else
@card.type = :link
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') || ''
@card.image_remote_url = (Addressable::URI.parse(@url) + meta_property(page, 'og:image')).to_s if meta_property(page, 'og:image')
return if @card.title.blank? && @card.html.blank?
@card.save_with_optional_image!
end
def meta_property(page, property)
page.at_xpath("//meta[contains(concat(' ', normalize-space(@property), ' '), ' #{property} ')]")&.attribute('content')&.value || page.at_xpath("//meta[@name=\"#{property}\"]")&.attribute('content')&.value
end end
def lock_options def lock_options
{ redis: Redis.current, key: "fetch:#{@url}", autorelease: 15.minutes.seconds } { redis: Redis.current, key: "fetch:#{@original_url}", autorelease: 15.minutes.seconds }
end end
end end

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@ -0,0 +1,29 @@
require 'rails_helper'
RSpec.describe LinkDetailsExtractor do
let(:original_url) { '' }
let(:html) { '' }
let(:html_charset) { nil }
subject { described_class.new(original_url, html, html_charset) }
describe '#canonical_url' do
let(:original_url) { 'https://foo.com/article?bar=baz123' }
context 'when canonical URL points to another host' do
let(:html) { '<!doctype html><link rel="canonical" href="https://bar.com/different-article" />' }
it 'ignores the canonical URLs' do
expect(subject.canonical_url).to eq original_url
end
end
context 'when canonical URL points to the same host' do
let(:html) { '<!doctype html><link rel="canonical" href="https://foo.com/article" />' }
it 'ignores the canonical URLs' do
expect(subject.canonical_url).to eq 'https://foo.com/article'
end
end
end
end

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@ -1,7 +1,7 @@
require 'rails_helper' require 'rails_helper'
RSpec.describe FetchLinkCardService, type: :service do RSpec.describe FetchLinkCardService, type: :service do
subject { FetchLinkCardService.new } subject { described_class.new }
before do before do
stub_request(:get, 'http://example.xn--fiqs8s/').to_return(request_fixture('idn.txt')) stub_request(:get, 'http://example.xn--fiqs8s/').to_return(request_fixture('idn.txt'))