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Implement charset handling in WebRequestConcern

- The `force_encoding` and `unzip` options in WebsiteAgent are moved to
  WebRequestConcern so other users of the concern such as RssAgent can
  benefit from them.

- WebRequestConcern detects a charset specified in the Content-Type
  header to decode the content properly, and if it is missing the
  content is assumed to be encoded in UTF-8 unless it has a binary MIME
  type. Not all Faraday adopters handle character encodings, and
  Faraday passes through what is returned from the backend, so we need
  to do this on our own. (cf. lostisland/faraday#139)

- WebRequestConcern now converts text contents to UTF-8, so agents can
  handle non-UTF-8 data without having to deal with encodings
  themselves. Previously, WebsiteAgent in "json"/"text" modes and
  RssAgent would suffer from encoding errors when dealing with non-UTF-8
  contents. WebsiteAgent in "html"/"xml" modes did not have this
  problem because Nokogiri would always return results in UTF-8
  independent of the input encoding.

This should fix #608.

Akinori MUSHA 10 years ago
parent
77ec02271f
commit
6f667a4973
3 changed files with 65 additions and 21 deletions
Show Diff Stats
  1. 63 1
      app/concerns/web_request_concern.rb
  2. 1 0
      app/models/agents/rss_agent.rb
  3. 1 20
      app/models/agents/website_agent.rb

+ 63 - 1
app/concerns/web_request_concern.rb
View File 

@@ -14,6 +14,46 @@ module WebRequestConcern
14 14 
     end
15 15 
   end
16 16
17 
+  class CharacterEncoding < Faraday::Middleware
18 
+    def initialize(app, force_encoding: nil, default_encoding: nil, unzip: nil)
19 
+      super(app)
20 
+      @force_encoding   = force_encoding
21 
+      @default_encoding = default_encoding
22 
+      @unzip            = unzip
23 
+    end
24 
+
25 
+    def call(env)
26 
+      @app.call(env).on_complete do |env|
27 
+        body = env[:body]
28 
+
29 
+        case @unzip
30 
+        when 'gzip'.freeze
31 
+          body.replace(ActiveSupport::Gzip.decompress(body))
32 
+        end
33 
+
34 
+        case
35 
+        when @force_encoding
36 
+          encoding = @force_encoding
37 
+        when body.encoding == Encoding::ASCII_8BIT
38 
+          # Not all Faraday adapters support automatic charset
39 
+          # detection, so we do that.
40 
+          case env[:response_headers][:content_type]
41 
+          when /;\s*charset\s*=\s*([^()<>@,;:\\\"\/\[\]?={}\s]+)/i
42 
+            encoding = Encoding.find($1) rescue nil
43 
+          when /\A\s*(?:text\/[^\s;]+|application\/(?:[^\s;]+\+)?(?:xml|json))\s*(?:;|\z)/i
44 
+            encoding = @default_encoding
45 
+          else
46 
+            # Never try to transcode a binary content
47 
+            return
48 
+          end
49 
+        end
50 
+        body.encode!(Encoding::UTF_8, encoding) unless body.encoding == Encoding::UTF_8
51 
+      end
52 
+    end
53 
+  end
54 
+
55 
+  Faraday::Response.register_middleware character_encoding: CharacterEncoding
56 
+
17 57 
   extend ActiveSupport::Concern
18 58
19 59 
   def validate_web_request_options!
 
@@ -34,6 +74,23 @@ module WebRequestConcern
34 74 
     rescue ArgumentError => e
35 75 
       errors.add(:base, e.message)
36 76 
     end
77 
+
78 
+    if (encoding = options['force_encoding']).present?
79 
+      case encoding
80 
+      when String
81 
+        begin
82 
+          Encoding.find(encoding)
83 
+        rescue ArgumentError
84 
+          errors.add(:base, "Unknown encoding: #{encoding.inspect}")
85 
+        end
86 
+      else
87 
+        errors.add(:base, "force_encoding must be a string")
88 
+      end
89 
+    end
90 
+  end
91 
+
92 
+  def default_encoding
93 
+    Encoding::UTF_8
37 94 
   end
38 95
39 96 
   def faraday
 
@@ -44,6 +101,11 @@ module WebRequestConcern
44 101 
     }
45 102
46 103 
     @faraday ||= Faraday.new(faraday_options) { |builder|
104 
+      builder.response :character_encoding,
105 
+                       force_encoding: interpolated['force_encoding'].presence,
106 
+                       default_encoding: default_encoding,
107 
+                       unzip: interpolated['unzip'].presence
108 
+
47 109 
       builder.headers = headers if headers.length > 0
48 110
49 111 
       builder.headers[:user_agent] = user_agent
 
@@ -51,7 +113,7 @@ module WebRequestConcern
51 113 
       builder.use FaradayMiddleware::FollowRedirects
52 114 
       builder.request :url_encoded
53 115
54 
-      if boolify(options['disable_url_encoding'])
116 
+      if boolify(interpolated['disable_url_encoding'])
55 117 
         builder.options.params_encoder = DoNotEncoder
56 118 
       end
57 119

+ 1 - 0
app/models/agents/rss_agent.rb
View File 

@@ -29,6 +29,7 @@ module Agents
29 29 
           * `basic_auth` - Specify HTTP basic auth parameters: `"username:password"`, or `["username", "password"]`.
30 30 
           * `disable_ssl_verification` - Set to `true` to disable ssl verification.
31 31 
           * `disable_url_encoding` - Set to `true` to disable url encoding.
32 
+          * `force_encoding` - Set `force_encoding` to an encoding name if the website is known to respond with a missing, invalid or wrong charset in the Content-Type header.  Note that a text content without a charset is taken as encoded in UTF-8 (not ISO-8859-1).
32 33 
           * `user_agent` - A custom User-Agent name (default: "Faraday v#{Faraday::VERSION}").
33 34 
           * `max_events_per_run` - Limit number of events created (items parsed) per run for feed.
34 35

+ 1 - 20
app/models/agents/website_agent.rb
View File 

@@ -87,7 +87,7 @@ module Agents
87 87
88 88 
       Set `uniqueness_look_back` to limit the number of events checked for uniqueness (typically for performance).  This defaults to the larger of #{UNIQUENESS_LOOK_BACK} or #{UNIQUENESS_FACTOR}x the number of detected received results.
89 89
90 
-      Set `force_encoding` to an encoding name if the website does not return a Content-Type header with a proper charset.
90 
+      Set `force_encoding` to an encoding name if the website is known to respond with a missing, invalid or wrong charset in the Content-Type header.  Note that a text content without a charset is taken as encoded in UTF-8 (not ISO-8859-1).
91 91
92 92 
       Set `user_agent` to a custom User-Agent name if the website does not like the default value (`#{default_user_agent}`).
93 93 
 
@@ -157,19 +157,6 @@ module Agents
157 157 
         errors.add(:base, "Invalid uniqueness_look_back format") unless is_positive_integer?(options['uniqueness_look_back'])
158 158 
       end
159 159
160 
-      if (encoding = options['force_encoding']).present?
161 
-        case encoding
162 
-        when String
163 
-          begin
164 
-            Encoding.find(encoding)
165 
-          rescue ArgumentError
166 
-            errors.add(:base, "Unknown encoding: #{encoding.inspect}")
167 
-          end
168 
-        else
169 
-          errors.add(:base, "force_encoding must be a string")
170 
-        end
171 
-      end
172 
-
173 160 
       validate_web_request_options!
174 161 
     end
175 162 
 
@@ -284,12 +271,6 @@ module Agents
284 271 
       interpolation_context.stack {
285 272 
         interpolation_context['_response_'] = ResponseDrop.new(response)
286 273 
         body = response.body
287 
-        if (encoding = interpolated['force_encoding']).present?
288 
-          body = body.encode(Encoding::UTF_8, encoding)
289 
-        end
290 
-        if interpolated['unzip'] == "gzip"
291 
-          body = ActiveSupport::Gzip.decompress(body)
292 
-        end
293 274 
         doc = parse(body)
294 275
295 276 
         if extract_full_json?