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115 lines
3.1 KiB
Ruby
115 lines
3.1 KiB
Ruby
# frozen_string_literal: true
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module RetrieveTitle
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CRAWL_TIMEOUT = 1
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UNRECOVERABLE_ERRORS = [
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Net::ReadTimeout,
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FinalDestination::SSRFError,
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FinalDestination::UrlEncodingError,
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]
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def self.crawl(url, max_redirects: nil, initial_https_redirect_ignore_limit: false)
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fetch_title(
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url,
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max_redirects: max_redirects,
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initial_https_redirect_ignore_limit: initial_https_redirect_ignore_limit,
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)
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rescue *UNRECOVERABLE_ERRORS
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# ¯\_(ツ)_/¯
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end
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def self.extract_title(html, encoding = nil)
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title = nil
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return nil if html =~ /<title>/ && html !~ %r{</title>}
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doc = nil
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begin
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doc = Nokogiri.HTML5(html, nil, encoding)
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rescue ArgumentError
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# invalid HTML (Eg: too many attributes, status tree too deep) - ignore
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# Error in nokogumbo is not specialized, uses generic ArgumentError
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# see: https://www.rubydoc.info/gems/nokogiri/Nokogiri/HTML5#label-Error+reporting
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end
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if doc
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title = doc.at("title")&.inner_text
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# A horrible hack - YouTube uses `document.title` to populate the title
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# for some reason. For any other site than YouTube this wouldn't be worth it.
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if title == "YouTube" && html =~ /document\.title *= *"(.*)";/
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title = Regexp.last_match[1].sub(/ - YouTube\z/, "")
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end
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if !title && node = doc.at('meta[property="og:title"]')
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title = node["content"]
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end
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end
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if title.present?
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title.gsub!(/\n/, " ")
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title.gsub!(/ +/, " ")
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title.strip!
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return title
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end
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nil
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end
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private
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def self.max_chunk_size(uri)
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# Exception for sites that leave the title until very late.
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if uri.host =~
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/(^|\.)amazon\.(com|ca|co\.uk|es|fr|de|it|com\.au|com\.br|cn|in|co\.jp|com\.mx)\z/
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return 500
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end
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return 300 if uri.host =~ /(^|\.)youtube\.com\z/ || uri.host =~ /(^|\.)youtu\.be\z/
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return 50 if uri.host =~ /(^|\.)github\.com\z/
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# default is 20k
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20
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end
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# Fetch the beginning of a HTML document at a url
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def self.fetch_title(url, max_redirects: nil, initial_https_redirect_ignore_limit: false)
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fd =
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FinalDestination.new(
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url,
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timeout: CRAWL_TIMEOUT,
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stop_at_blocked_pages: true,
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max_redirects: max_redirects,
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initial_https_redirect_ignore_limit: initial_https_redirect_ignore_limit,
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headers: {
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Accept: "text/html,*/*",
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},
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)
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current = nil
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title = nil
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encoding = nil
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fd.get do |_response, chunk, uri|
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unless Net::HTTPRedirection === _response
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throw :done if uri.blank?
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if current
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current << chunk
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else
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current = chunk
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end
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if !encoding && content_type = _response["content-type"]&.strip&.downcase
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if content_type =~ /charset="?([a-z0-9_-]+)"?/
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encoding = Regexp.last_match(1)
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encoding = nil if !Encoding.list.map(&:name).map(&:downcase).include?(encoding)
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end
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end
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max_size = max_chunk_size(uri) * 1024
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title = extract_title(current, encoding)
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throw :done if title || max_size < current.length
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end
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end
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title
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end
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end
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