Class: Rack::Prerendercloud

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

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

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

Returns a new instance of Prerendercloud.



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# File 'lib/prerendercloud.rb', line 35

def initialize(app, options={})
  # googlebot, yahoo, and bingbot are not in this list because
  # we support _escaped_fragment_ and want to ensure people aren't
  # penalized for cloaking.
  @crawler_user_agents = [
    'googlebot',
    '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'
  ]

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

Class Method Details

.header_whitelist ⇒ Object 



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# File 'lib/prerendercloud.rb', line 8

def header_whitelist
   # preserve (and send to client) these headers from service.prerender.cloud
   # which originally came from the origin server
  return [
    "vary",
    "content-type",
    "cache-control",
    "strict-transport-security",
    "content-security-policy",
    "public-key-pins",
    "x-frame-options",
    "x-xss-protection",
    "x-content-type-options",
    "location"
  ];
end

.normalize_headers(headers) ⇒ Object 



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# File 'lib/prerendercloud.rb', line 25

def normalize_headers(headers)
  filtered = headers.select { |key, value| header_whitelist.any? { |h| key.to_s.match(/#{h}/i) } }

  mapped = filtered.map do |k, v|
    [k, if v.is_a? Array then v.join("\n") else v end]
  end
  Utils::HeaderHash.new Hash[mapped]
end

Instance Method Details

#after_render(env, response) ⇒ Object 



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# File 'lib/prerendercloud.rb', line 259

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/prerendercloud.rb', line 244

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/prerendercloud.rb', line 201

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
  puts "Requesting prerendered page for #{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/prerendercloud.rb', line 232

def build_rack_response_from_prerender(prerendered_response)

  headers = (prerendered_response.respond_to?(:headers) && prerendered_response.headers) || self.class.normalize_headers(prerendered_response.to_hash)

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


  @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/prerendercloud.rb', line 80

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/prerendercloud.rb', line 227

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

#get_prerendered_page_response(env) ⇒ Object 



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# File 'lib/prerendercloud.rb', line 175

def get_prerendered_page_response(env)
  begin
    url = URI.parse(build_api_url(env))
    headers = {
      'User-Agent' => env['HTTP_USER_AGENT'],
      'Accept-Encoding' => 'gzip'
    }
    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)
    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.length
      response.delete('Content-Encoding')
    end
    response
  rescue => e
    puts "Error: #{e.class.name}"
    nil
  end
end

#prerenderable_extension(fullpath) ⇒ Object 



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# File 'lib/prerendercloud.rb', line 157

def prerenderable_extension(fullpath)

  path = URI.parse(fullpath).path;

  # doesn't detect index.whatever.html (multiple dots)
  hasHtmlOrNoExtension = !!path.match(/^(([^.]|\.html?)+)$/);

  return true if hasHtmlOrNoExtension

  # hack to handle basenames with multiple dots: index.whatever.html
  endsInHtml = !!path.match(/.html?$/);

  return true if endsInHtml

  return false;

end

#should_show_prerendered_page(env) ⇒ Object 



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# File 'lib/prerendercloud.rb', line 102

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

  return false if !user_agent
  return false if env['REQUEST_METHOD'] != 'GET'
  return false if user_agent.match(/prerendercloud/i);

  request = Rack::Request.new(env)

  return false if !prerenderable_extension(request.fullpath);

  #if it is a bot...show prerendered page
  if (@options[:bots_only])
    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
  else
    is_requesting_prerendered_page = true
  end

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

  # if whitelist exists and path is not whitelisted...don't prerender
  return false if @options[:whitelist].is_a?(Array) && @options[:whitelist].all? do |whitelisted|
    if whitelisted.is_a?(Regexp)
      !whitelisted.match(request.fullpath)
    else
      whitelisted != request.fullpath;
    end
  end

  # if blacklist exists and path is blacklisted(url or referer)...don't prerender
  if @options[:blacklist].is_a?(Array) && @options[:blacklist].any? do |blacklisted|
      blacklistedUrl = false
      blacklistedReferer = false

      if blacklisted.is_a?(Regexp)
        blacklistedUrl = !!blacklisted.match(request.fullpath)
        blacklistedReferer = !!blacklisted.match(request.referer) if request.referer
      else
        blacklistedUrl = blacklisted == request.fullpath
        blacklistedReferer = request.referer && blacklisted == request.referer
      end

      blacklistedUrl || blacklistedReferer
    end
    return false
  end

  return is_requesting_prerendered_page
end