mastodon/app/services/fetch_link_card_service.rb
Claire 9a19227f17
Fix some RedisLocks auto-releasing too fast (#16276)
* Fix Delete and Create-related locks expiring too fast

Fixes #16238

By default, RedisLock expires after 10 seconds, which may not be enough to
process statuses, especially when those have attached media files.

This commit extends those 10 seconds to 15 minutes, which should be plenty
enough to handle any status, while being short enough to not waste many
sidekiq job retries in the exceedingly rare case in which a sidekiq process
would crash when processing a `Create` or `Delete`.

* Fix other RedisLock autorelease durations

Fixes #15645

- things that only perform a few simple database queries (e.g. finding and
  saving a record) have been left unchanged, so they'll still use the default
  10s duration
- things that perform significantly more complex database queries have been
  changed to a 5 minutes timeout
- things that perform multiple HTTP queries have been changed to a 15 minutes
  timeout
2021-05-19 23:52:08 +02:00

181 lines
7 KiB
Ruby

# frozen_string_literal: true
class FetchLinkCardService < BaseService
URL_PATTERN = %r{
(#{Twitter::TwitterText::Regex[:valid_url_preceding_chars]}) # $1 preceeding 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
@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 || @card.missing_image?
else
raise Mastodon::RaceConditionError
end
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 #{@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|
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)
end
def parse_urls
if @status.local?
urls = @status.text.scan(URL_PATTERN).map { |array| Addressable::URI.parse(array[1]).normalize }
else
html = Nokogiri::HTML(@status.text)
links = html.css('a')
urls = links.filter_map { |a| Addressable::URI.parse(a['href']) unless skip_link?(a) }.filter_map(&:normalize)
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
# rubocop:disable Naming/MethodParameterName
def mention_link?(a)
@status.mentions.any? do |mention|
a['href'] == ActivityPub::TagManager.instance.url_for(mention.account)
end
end
def skip_link?(a)
# Avoid links for hashtags and mentions (microformats)
a['rel']&.include?('tag') || a['class']&.match?(/u-url|h-card/) || mention_link?(a)
end
# rubocop:enable Naming/MethodParameterName
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 = Formatter.instance.sanitize(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?
detector = CharlockHolmes::EncodingDetector.new
detector.strip_tags = true
guess = detector.detect(@html, @html_charset)
encoding = guess&.fetch(:confidence, 0).to_i > 60 ? guess&.fetch(:encoding, nil) : nil
page = Nokogiri::HTML(@html, nil, encoding)
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
def lock_options
{ redis: Redis.current, key: "fetch:#{@url}", autorelease: 15.minutes.seconds }
end
end