Class: Rack::Prerender

Inherits:
Object
  • Object
show all
Defined in:
lib/prerender_rails.rb

Instance Method Summary collapse

Constructor Details

#initialize(app, options = {}) ⇒ Prerender

Returns a new instance of Prerender.



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# File 'lib/prerender_rails.rb', line 6

def initialize(app, options={})
  @connection_header_values = [
    'close',
    'keep-alive'
  ].freeze
  @hop_by_hop_headers = [
    'Connection',
    'Keep-Alive',
    'Public',
    'Proxy-Authenticate',
    'Transfer-Encoding',
    'Upgrade'
  ].freeze

  @crawler_user_agents = [
    'googlebot',
    'Google-InspectionTool',
    'yahoo',
    'bingbot',
    'baiduspider',
    'facebookexternalhit',
    'twitterbot',
    'rogerbot',
    'linkedinbot',
    'embedly',
    'bufferbot',
    'quora link preview',
    'showyoubot',
    'outbrain',
    'pinterest/0.',
    'developers.google.com/+/web/snippet',
    'www.google.com/webmasters/tools/richsnippets',
    'slackbot',
    'vkShare',
    'W3C_Validator',
    'redditbot',
    'Applebot',
    'WhatsApp',
    'flipboard',
    'tumblr',
    'bitlybot',
    'SkypeUriPreview',
    'nuzzel',
    'Discordbot',
    'Google Page Speed',
    'Qwantify',
    'Chrome-Lighthouse',
    'TelegramBot'
  ]

  @extensions_to_ignore = [
    '.js',
    '.css',
    '.xml',
    '.less',
    '.png',
    '.jpg',
    '.jpeg',
    '.gif',
    '.pdf',
    '.doc',
    '.txt',
    '.ico',
    '.rss',
    '.zip',
    '.mp3',
    '.rar',
    '.exe',
    '.wmv',
    '.doc',
    '.avi',
    '.ppt',
    '.mpg',
    '.mpeg',
    '.tif',
    '.wav',
    '.mov',
    '.psd',
    '.ai',
    '.xls',
    '.mp4',
    '.m4a',
    '.swf',
    '.dat',
    '.dmg',
    '.iso',
    '.flv',
    '.m4v',
    '.torrent'
  ]

  @options = options
  @options[:whitelist] = [@options[:whitelist]] if @options[:whitelist].is_a? String
  @options[:blacklist] = [@options[:blacklist]] if @options[:blacklist].is_a? String
  @extensions_to_ignore = @options[:extensions_to_ignore] if @options[:extensions_to_ignore]
  @crawler_user_agents = @options[:crawler_user_agents] if @options[:crawler_user_agents]
  @app = app
end

Instance Method Details

#after_render(env, response) ⇒ Object 



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# File 'lib/prerender_rails.rb', line 267

def after_render(env, response)
  return true unless @options[:after_render]
  @options[:after_render].call(env, response)
end

#before_render(env) ⇒ Object 



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# File 'lib/prerender_rails.rb', line 252

def before_render(env)
  return nil unless @options[:before_render]

  cached_render = @options[:before_render].call(env)

  if cached_render && cached_render.is_a?(String)
    Rack::Response.new(cached_render, 200, { 'Content-Type' => 'text/html; charset=utf-8' })
  elsif cached_render && cached_render.is_a?(Rack::Response)
    cached_render
  else
    nil
  end
end

#build_api_url(env) ⇒ Object 



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# File 'lib/prerender_rails.rb', line 214

def build_api_url(env)
  new_env = env
  if env["CF-VISITOR"]
    match = /"scheme":"(http|https)"/.match(env['CF-VISITOR'])
    new_env["HTTPS"] = true and new_env["rack.url_scheme"] = "https" and new_env["SERVER_PORT"] = 443 if (match && match[1] == "https")
    new_env["HTTPS"] = false and new_env["rack.url_scheme"] = "http" and new_env["SERVER_PORT"] = 80 if (match && match[1] == "http")
  end

  if env["X-FORWARDED-PROTO"]
    new_env["HTTPS"] = true and new_env["rack.url_scheme"] = "https" and new_env["SERVER_PORT"] = 443 if env["X-FORWARDED-PROTO"].split(',')[0] == "https"
    new_env["HTTPS"] = false and new_env["rack.url_scheme"] = "http" and new_env["SERVER_PORT"] = 80 if env["X-FORWARDED-PROTO"].split(',')[0] == "http"
  end

  if @options[:protocol]
    new_env["HTTPS"] = true and new_env["rack.url_scheme"] = "https" and new_env["SERVER_PORT"] = 443 if @options[:protocol] == "https"
    new_env["HTTPS"] = false and new_env["rack.url_scheme"] = "http" and new_env["SERVER_PORT"] = 80 if @options[:protocol] == "http"
  end

  url = Rack::Request.new(new_env).url
  prerender_url = get_prerender_service_url()
  forward_slash = prerender_url[-1, 1] == '/' ? '' : '/'
  "#{prerender_url}#{forward_slash}#{url}"
end

#build_rack_response_from_prerender(prerendered_response) ⇒ Object 



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# File 'lib/prerender_rails.rb', line 244

def build_rack_response_from_prerender(prerendered_response)
  response = Rack::Response.new(prerendered_response.body, prerendered_response.code, prerendered_response)

  @options[:build_rack_response_from_prerender].call(response, prerendered_response) if @options[:build_rack_response_from_prerender]

  response
end

#call(env) ⇒ Object 



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# File 'lib/prerender_rails.rb', line 106

def call(env)
  if should_show_prerendered_page(env)

    cached_response = before_render(env)

    if cached_response
      return cached_response.finish
    end

    prerendered_response = get_prerendered_page_response(env)

    if prerendered_response
      response = build_rack_response_from_prerender(prerendered_response)
      after_render(env, prerendered_response)
      return response.finish
    end
  end

  @app.call(env)
end

#get_prerender_service_url ⇒ Object 



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# File 'lib/prerender_rails.rb', line 239

def get_prerender_service_url
  @options[:prerender_service_url] || ENV['PRERENDER_SERVICE_URL'] || 'http://service.prerender.io/'
end

#get_prerendered_page_response(env) ⇒ Object 



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# File 'lib/prerender_rails.rb', line 174

def get_prerendered_page_response(env)
  begin
    url = URI.parse(build_api_url(env))
    headers = {
      'User-Agent' => env['HTTP_USER_AGENT'],
      'Accept-Encoding' => 'gzip',
      'X-Prerender-Int-Type' => 'Ruby'
    }
    headers['X-Prerender-Token'] = ENV['PRERENDER_TOKEN'] if ENV['PRERENDER_TOKEN']
    headers['X-Prerender-Token'] = @options[:prerender_token] if @options[:prerender_token]
    req = Net::HTTP::Get.new(url.request_uri, headers)
    req.basic_auth(ENV['PRERENDER_USERNAME'], ENV['PRERENDER_PASSWORD']) if @options[:basic_auth]
    http = Net::HTTP.new(url.host, url.port)
    http.use_ssl = true if url.scheme == 'https'
    response = http.request(req)
    if response['Content-Encoding'] == 'gzip'
      response.body = ActiveSupport::Gzip.decompress(response.body)
      response['Content-Length'] = response.body.bytesize
      response.delete('Content-Encoding')
    end

    hop_by_hop_headers = @hop_by_hop_headers
    connection = response['Connection']
    if connection
      connection_hop_by_hop_headers = connection.split(',').
                                        map(&:strip).
                                        map(&:downcase).
                                        difference(@connection_header_values)
      hop_by_hop_headers = connection_hop_by_hop_headers.
                             concat(hop_by_hop_headers)
    end
    hop_by_hop_headers.each { |h| response.delete(h) }

    response
  rescue
    nil
  end
end

#should_show_prerendered_page(env) ⇒ Object 



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# File 'lib/prerender_rails.rb', line 128

def should_show_prerendered_page(env)
  user_agent = env['HTTP_USER_AGENT']
  buffer_agent = env['HTTP_X_BUFFERBOT']
  prerender_agent = env['HTTP_X_PRERENDER']
  is_requesting_prerendered_page = false

  return false if !user_agent
  return false if env['REQUEST_METHOD'] != 'GET'

  request = Rack::Request.new(env)

  is_requesting_prerendered_page = true if Rack::Utils.parse_query(request.query_string).has_key?('_escaped_fragment_')

  #if it is a bot...show prerendered page
  is_requesting_prerendered_page = true if @crawler_user_agents.any? { |crawler_user_agent| user_agent.downcase.include?(crawler_user_agent.downcase) }

  #if it is BufferBot...show prerendered page
  is_requesting_prerendered_page = true if buffer_agent

  #if it is Prerender...don't show prerendered page
  is_requesting_prerendered_page = false if prerender_agent

  #if it is a bot and is requesting a resource...dont prerender
  return false if @extensions_to_ignore.any? { |extension| request.fullpath.include? extension }

  #if it is a bot and not requesting a resource and is not whitelisted...dont prerender
  return false if @options[:whitelist].is_a?(Array) && @options[:whitelist].all? { |whitelisted| !Regexp.new(whitelisted).match(request.fullpath) }

  #if it is a bot and not requesting a resource and is blacklisted(url or referer)...dont prerender
  if @options[:blacklist].is_a?(Array) && @options[:blacklist].any? { |blacklisted|
      blacklistedUrl = false
      blacklistedReferer = false
      regex = Regexp.new(blacklisted)

      blacklistedUrl = !!regex.match(request.fullpath)
      blacklistedReferer = !!regex.match(request.referer) if request.referer

      blacklistedUrl || blacklistedReferer
    }
    return false
  end

  return is_requesting_prerendered_page
end