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.



34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
 
# File 'lib/prerendercloud.rb', line 34

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 



8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
 
# 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"
  ];
end

.normalize_headers(headers) ⇒ Object 



24
25
26
27
28
29
30
31
 
# File 'lib/prerendercloud.rb', line 24

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 



248
249
250
251
 
# File 'lib/prerendercloud.rb', line 248

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

#before_render(env) ⇒ Object 



233
234
235
236
237
238
239
240
241
242
243
244
245
 
# File 'lib/prerendercloud.rb', line 233

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 



190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
 
# File 'lib/prerendercloud.rb', line 190

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 



221
222
223
224
225
226
227
228
229
230
231
 
# File 'lib/prerendercloud.rb', line 221

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 



79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
 
# File 'lib/prerendercloud.rb', line 79

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 



216
217
218
 
# File 'lib/prerendercloud.rb', line 216

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

#get_prerendered_page_response(env) ⇒ Object 



164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
 
# File 'lib/prerendercloud.rb', line 164

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 



146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
 
# File 'lib/prerendercloud.rb', line 146

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 



101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
 
# File 'lib/prerendercloud.rb', line 101

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? { |whitelisted| !Regexp.new(whitelisted).match(request.fullpath) }

  # if blacklist exists and path is blacklisted(url or referer)...don't 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