Class: Cobweb

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

Overview

Cobweb class is used to perform get and head requests. You can use this on its own if you wish without the crawler

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ Cobweb

See readme for more information on options available



31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
 
# File 'lib/cobweb.rb', line 31

def initialize(options = {})
  @options = options
  default_use_encoding_safe_process_job_to  false
  default_follow_redirects_to               true
  default_redirect_limit_to                 10
  default_processing_queue_to               "CobwebProcessJob"
  default_crawl_finished_queue_to           "CobwebFinishedJob"
  default_quiet_to                          true
  default_debug_to                          false
  default_cache_to                          300
  default_cache_type_to                     :crawl_based # other option is :full
  default_timeout_to                        10
  default_redis_options_to                  Hash.new
  default_internal_urls_to                  []
  default_first_page_redirect_internal_to   true
  default_text_mime_types_to                ["text/*", "application/xhtml+xml"]
  default_obey_robots_to                    false
  default_user_agent_to                     "cobweb/#{Cobweb.version} (ruby/#{RUBY_VERSION} nokogiri/#{Nokogiri::VERSION})"
  default_valid_mime_types_to                ["*/*"]
  default_raise_exceptions_to               false
  
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(method_sym, *arguments, &block) ⇒ Object

used for setting default options



21
22
23
24
25
26
27
28
 
# File 'lib/cobweb.rb', line 21

def method_missing(method_sym, *arguments, &block)
  if method_sym.to_s =~ /^default_(.*)_to$/
    tag_name = method_sym.to_s.split("_")[1..-2].join("_").to_sym
    @options[tag_name] = arguments[0] unless @options.has_key?(tag_name)
  else
    super
  end
end

Class Method Details

.escape_pattern_for_regex(pattern) ⇒ Object

escapes characters with meaning in regular expressions and adds wildcard expression



403
404
405
406
407
408
409
 
# File 'lib/cobweb.rb', line 403

def self.escape_pattern_for_regex(pattern)
  pattern = pattern.gsub(".", "\\.")
  pattern = pattern.gsub("?", "\\?")
  pattern = pattern.gsub("+", "\\+")
  pattern = pattern.gsub("*", ".*?")
  pattern
end

.version ⇒ Object

retrieves current version



16
17
18
 
# File 'lib/cobweb.rb', line 16

def self.version
  CobwebVersion.version
end

Instance Method Details

#get(url, options = @options) ⇒ Object

Performs a HTTP GET request to the specified url applying the options supplied



98
99
100
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
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
 
# File 'lib/cobweb.rb', line 98

def get(url, options = @options)
  raise "url cannot be nil" if url.nil?
  uri = Addressable::URI.parse(url)
  uri.normalize!
  uri.fragment=nil
  url = uri.to_s

  # get the unique id for this request
  unique_id = Digest::SHA1.hexdigest(url.to_s)
  if options.has_key?(:redirect_limit) and !options[:redirect_limit].nil?
    redirect_limit = options[:redirect_limit].to_i
  else
    redirect_limit = 10
  end
  
  # connect to redis
  if options.has_key? :crawl_id
    redis = Redis::Namespace.new("cobweb-#{Cobweb.version}-#{options[:crawl_id]}", :redis => Redis.new(@options[:redis_options]))
  else
    redis = Redis::Namespace.new("cobweb-#{Cobweb.version}", :redis => Redis.new(@options[:redis_options]))
  end
  full_redis = Redis::Namespace.new("cobweb-#{Cobweb.version}", :redis => Redis.new(@options[:redis_options]))

  content = {:base_url => url}

  # check if it has already been cached
  if ((@options[:cache_type] == :crawl_based && redis.get(unique_id)) || (@options[:cache_type] == :full && full_redis.get(unique_id))) && @options[:cache]
    puts "Cache hit for #{url}" unless @options[:quiet]
    content = HashUtil.deep_symbolize_keys(Marshal.load(redis.get(unique_id)))
  else
    # retrieve data
    unless @http && @http.address == uri.host && @http.port == uri.inferred_port
      puts "Creating connection to #{uri.host}..." if @options[:debug]
      @http = Net::HTTP.new(uri.host, uri.inferred_port)
    end
    if uri.scheme == "https"
      @http.use_ssl = true
      @http.verify_mode = OpenSSL::SSL::VERIFY_NONE
    end
    
    request_time = Time.now.to_f
    @http.read_timeout = @options[:timeout].to_i
    @http.open_timeout = @options[:timeout].to_i
    begin
      print "Retrieving #{url }... " unless @options[:quiet]
      request_options={}
      request_options['Cookie']= options[:cookies] if options.has_key?(:cookies)
      request_options['User-Agent']= options[:user_agent] if options.has_key?(:user_agent)

      request = Net::HTTP::Get.new uri.request_uri, request_options

      response = @http.request request
      
      if @options[:follow_redirects] and response.code.to_i >= 300 and response.code.to_i < 400
        puts "redirected... " unless @options[:quiet]
        
        # get location to redirect to
        uri = UriHelper.join_no_fragment(uri, response['location'])
        
        # decrement redirect limit
        redirect_limit = redirect_limit - 1

        raise RedirectError, "Redirect Limit reached" if redirect_limit == 0
        cookies = get_cookies(response)

        # get the content from redirect location
        content = get(uri, options.merge(:redirect_limit => redirect_limit, :cookies => cookies))
        content[:url] = uri.to_s
        content[:redirect_through] = [] if content[:redirect_through].nil?
        content[:redirect_through].insert(0, url)
        
        content[:response_time] = Time.now.to_f - request_time
      else
        content[:response_time] = Time.now.to_f - request_time
        
        puts "Retrieved." unless @options[:quiet]

        # create the content container
        content[:url] = uri.to_s
        content[:status_code] = response.code.to_i
        content[:mime_type] = ""
        content[:mime_type] = response.content_type.split(";")[0].strip unless response.content_type.nil?
        if !response["Content-Type"].nil? && response["Content-Type"].include?(";")
          charset = response["Content-Type"][response["Content-Type"].index(";")+2..-1] if !response["Content-Type"].nil? and response["Content-Type"].include?(";")
          charset = charset[charset.index("=")+1..-1] if charset and charset.include?("=")
          content[:character_set] = charset
        end
        content[:length] = response.content_length
        content[:text_content] = text_content?(content[:mime_type])
        if text_content?(content[:mime_type])
          if response["Content-Encoding"]=="gzip"
            content[:body] = Zlib::GzipReader.new(StringIO.new(response.body)).read
          else
            content[:body] = response.body
          end
        else
          content[:body] = Base64.encode64(response.body)
        end
        content[:location] = response["location"]
        content[:headers] = HashUtil.deep_symbolize_keys(response.to_hash)
        # parse data for links
        link_parser = ContentLinkParser.new(content[:url], content[:body])
        content[:links] = link_parser.link_data
        
      end
      # add content to cache if required
      if @options[:cache]
        redis.set(unique_id, Marshal.dump(content))
        redis.expire unique_id, @options[:cache].to_i
      end
    rescue RedirectError => e
      raise e if @options[:raise_exceptions]
      puts "ERROR RedirectError: #{e.message}"
      
      ## generate a blank content
      content = {}
      content[:url] = uri.to_s
      content[:response_time] = Time.now.to_f - request_time
      content[:status_code] = 0
      content[:length] = 0
      content[:body] = ""
      content[:error] = e.message
      content[:mime_type] = "error/dnslookup"
      content[:headers] = {}
      content[:links] = {}
      
    rescue SocketError => e
      raise e if @options[:raise_exceptions]
      puts "ERROR SocketError: #{e.message}"
      
      ## generate a blank content
      content = {}
      content[:url] = uri.to_s
      content[:response_time] = Time.now.to_f - request_time
      content[:status_code] = 0
      content[:length] = 0
      content[:body] = ""
      content[:error] = e.message
      content[:mime_type] = "error/dnslookup"
      content[:headers] = {}
      content[:links] = {}
      
    rescue Timeout::Error => e
      raise e if @options[:raise_exceptions]
      puts "ERROR Timeout::Error: #{e.message}"
      
      ## generate a blank content
      content = {}
      content[:url] = uri.to_s
      content[:response_time] = Time.now.to_f - request_time
      content[:status_code] = 0
      content[:length] = 0
      content[:body] = ""
      content[:error] = e.message
      content[:mime_type] = "error/serverdown"
      content[:headers] = {}
      content[:links] = {}
    end
    content
  end
end

#get_cookies(response) ⇒ Object

Returns array of cookies from content



86
87
88
89
90
91
92
93
94
95
 
# File 'lib/cobweb.rb', line 86

def get_cookies(response)
  all_cookies = response.get_fields('set-cookie')
  unless all_cookies.nil?
    cookies_array = Array.new
    all_cookies.each { |cookie|
      cookies_array.push(cookie.split('; ')[0])
    }
    cookies = cookies_array.join('; ')
  end
end

#head(url, options = @options) ⇒ Object

Performs a HTTP HEAD request to the specified url applying the options supplied



261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
 
# File 'lib/cobweb.rb', line 261

def head(url, options = @options)
  raise "url cannot be nil" if url.nil?    
  uri = Addressable::URI.parse(url)
  uri.normalize!
  uri.fragment=nil
  url = uri.to_s

  # get the unique id for this request
  unique_id = Digest::SHA1.hexdigest(url)
  if options.has_key?(:redirect_limit) and !options[:redirect_limit].nil?
    redirect_limit = options[:redirect_limit].to_i
  else
    redirect_limit = 10
  end
  
  # connect to redis
  if options.has_key? :crawl_id
    redis = Redis::Namespace.new("cobweb-#{Cobweb.version}-#{options[:crawl_id]}", :redis => Redis.new(@options[:redis_options]))
  else
    redis = Redis::Namespace.new("cobweb-#{Cobweb.version}", :redis => Redis.new(@options[:redis_options]))
  end
  
  content = {:base_url => url}
  
  # check if it has already been cached
  if redis.get("head-#{unique_id}") and @options[:cache]
    puts "Cache hit for #{url}" unless @options[:quiet]
    content = HashUtil.deep_symbolize_keys(Marshal.load(redis.get("head-#{unique_id}")))
  else
    # retrieve data
    unless @http && @http.address == uri.host && @http.port == uri.inferred_port
      puts "Creating connection to #{uri.host}..." unless @options[:quiet]
      @http = Net::HTTP.new(uri.host, uri.inferred_port)
    end
    if uri.scheme == "https"
      @http.use_ssl = true
      @http.verify_mode = OpenSSL::SSL::VERIFY_NONE
    end
    
    request_time = Time.now.to_f
    @http.read_timeout = @options[:timeout].to_i
    @http.open_timeout = @options[:timeout].to_i
    begin
      print "Retrieving #{url }... " unless @options[:quiet]
      request_options={}
      if options[:cookies]
        request_options[ 'Cookie']= options[:cookies]
      end
      request = Net::HTTP::Head.new uri.request_uri, request_options

      response = @http.request request

      if @options[:follow_redirects] and response.code.to_i >= 300 and response.code.to_i < 400
        puts "redirected... " unless @options[:quiet]

        uri = UriHelper.join_no_fragment(uri, response['location'])

        redirect_limit = redirect_limit - 1

        raise RedirectError, "Redirect Limit reached" if redirect_limit == 0
        cookies = get_cookies(response)

        content = head(uri, options.merge(:redirect_limit => redirect_limit, :cookies => cookies))
        content[:url] = uri.to_s
        content[:redirect_through] = [] if content[:redirect_through].nil?
        content[:redirect_through].insert(0, url)
      else
        content[:url] = uri.to_s
        content[:status_code] = response.code.to_i
        unless response.content_type.nil?
          content[:mime_type] = response.content_type.split(";")[0].strip
          if response["Content-Type"].include? ";"
            charset = response["Content-Type"][response["Content-Type"].index(";")+2..-1] if !response["Content-Type"].nil? and response["Content-Type"].include?(";")
            charset = charset[charset.index("=")+1..-1] if charset and charset.include?("=")
            content[:character_set] = charset
          end
        end 
        
        # add content to cache if required
        if @options[:cache]
          puts "Stored in cache [head-#{unique_id}]" if @options[:debug]
          redis.set("head-#{unique_id}", Marshal.dump(content))
          redis.expire "head-#{unique_id}", @options[:cache].to_i
        else
          puts "Not storing in cache as cache disabled" if @options[:debug]
        end
      end
    rescue RedirectError => e
      raise e if @options[:raise_exceptions]
      puts "ERROR RedirectError: #{e.message}"

      ## generate a blank content
      content = {}
      content[:url] = uri.to_s
      content[:response_time] = Time.now.to_f - request_time
      content[:status_code] = 0
      content[:length] = 0
      content[:body] = ""
      content[:error] = e.message
      content[:mime_type] = "error/dnslookup"
      content[:headers] = {}
      content[:links] = {}

    rescue SocketError => e
      raise e if @options[:raise_exceptions]
      puts "ERROR SocketError: #{e.message}"
      
      ## generate a blank content
      content = {}
      content[:url] = uri.to_s
      content[:response_time] = Time.now.to_f - request_time
      content[:status_code] = 0
      content[:length] = 0
      content[:body] = ""
      content[:error] = e.message
      content[:mime_type] = "error/dnslookup"
      content[:headers] = {}
      content[:links] = {}
      
    rescue Timeout::Error => e
      raise e if @options[:raise_exceptions]
      puts "ERROR Timeout::Error: #{e.message}"
      
      ## generate a blank content
      content = {}
      content[:url] = uri.to_s
      content[:response_time] = Time.now.to_f - request_time
      content[:status_code] = 0
      content[:length] = 0
      content[:body] = ""
      content[:error] = e.message
      content[:mime_type] = "error/serverdown"
      content[:headers] = {}
      content[:links] = {}
    end
    
    content
  end
  
end

#start(base_url) ⇒ Object

This method starts the resque based crawl and enqueues the base_url



55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
 
# File 'lib/cobweb.rb', line 55

def start(base_url)
  raise ":base_url is required" unless base_url
  request = {
    :crawl_id => Digest::SHA1.hexdigest("#{Time.now.to_i}.#{Time.now.usec}"),
    :url => base_url 
  }  
  
  if @options[:internal_urls].nil? || @options[:internal_urls].empty?
    uri = Addressable::URI.parse(base_url)
    @options[:internal_urls] = []
    @options[:internal_urls] << [uri.scheme, "://", uri.host, "/*"].join
    @options[:internal_urls] << [uri.scheme, "://", uri.host, ":", uri.inferred_port, "/*"].join
  end
  
  request.merge!(@options)
  @redis = Redis::Namespace.new("cobweb-#{Cobweb.version}-#{request[:crawl_id]}", :redis => Redis.new(request[:redis_options]))
  @redis.set("original_base_url", base_url)
  @redis.hset "statistics", "queued_at", DateTime.now
  @redis.set("crawl-counter", 0)
  @redis.set("queue-counter", 1)
  
  @stats = Stats.new(request)
  @stats.start_crawl(request)
  
  # add internal_urls into redis
  @options[:internal_urls].map{|url| @redis.sadd("internal_urls", url)}
  Resque.enqueue(CrawlJob, request)
  request
end