vendor/rails/actionpack/lib/action_controller/vendor/rack-1.0/rack/deflater.rb

   1 require "zlib"
   2 require "stringio"
   3 require "time"  # for Time.httpdate
   4 require 'rack/utils'
   5
   6 module Rack
   7   class Deflater
   8     def initialize(app)
   9       @app = app
  10     end
  11
  12     def call(env)
  13       status, headers, body = @app.call(env)
  14       headers = Utils::HeaderHash.new(headers)
  15
  16       # Skip compressing empty entity body responses and responses with
  17       # no-transform set.
  18       if Utils::STATUS_WITH_NO_ENTITY_BODY.include?(status) ||
  19           headers['Cache-Control'].to_s =~ /\bno-transform\b/
  20         return [status, headers, body]
  21       end
  22
  23       request = Request.new(env)
  24
  25       encoding = Utils.select_best_encoding(%w(gzip deflate identity),
  26                                             request.accept_encoding)
  27
  28       # Set the Vary HTTP header.
  29       vary = headers["Vary"].to_s.split(",").map { |v| v.strip }
  30       unless vary.include?("*") || vary.include?("Accept-Encoding")
  31         headers["Vary"] = vary.push("Accept-Encoding").join(",")
  32       end
  33
  34       case encoding
  35       when "gzip"
  36         mtime = headers.key?("Last-Modified") ?
  37           Time.httpdate(headers["Last-Modified"]) : Time.now
  38         body = self.class.gzip(body, mtime)
  39         size = Rack::Utils.bytesize(body)
  40         headers = headers.merge("Content-Encoding" => "gzip", "Content-Length" => size.to_s)
  41         [status, headers, [body]]
  42       when "deflate"
  43         body = self.class.deflate(body)
  44         size = Rack::Utils.bytesize(body)
  45         headers = headers.merge("Content-Encoding" => "deflate", "Content-Length" => size.to_s)
  46         [status, headers, [body]]
  47       when "identity"
  48         [status, headers, body]
  49       when nil
  50         message = "An acceptable encoding for the requested resource #{request.fullpath} could not be found."
  51         [406, {"Content-Type" => "text/plain", "Content-Length" => message.length.to_s}, [message]]
  52       end
  53     end
  54
  55     def self.gzip(body, mtime)
  56       io = StringIO.new
  57       gzip = Zlib::GzipWriter.new(io)
  58       gzip.mtime = mtime
  59
  60       # TODO: Add streaming
  61       body.each { |part| gzip << part }
  62
  63       gzip.close
  64       return io.string
  65     end
  66
  67     DEFLATE_ARGS = [
  68       Zlib::DEFAULT_COMPRESSION,
  69       # drop the zlib header which causes both Safari and IE to choke
  70      -Zlib::MAX_WBITS,
  71       Zlib::DEF_MEM_LEVEL,
  72       Zlib::DEFAULT_STRATEGY
  73     ]
  74
  75     # Loosely based on Mongrel's Deflate handler
  76     def self.deflate(body)
  77       deflater = Zlib::Deflate.new(*DEFLATE_ARGS)
  78
  79       # TODO: Add streaming
  80       body.each { |part| deflater << part }
  81
  82       return deflater.finish
  83     end
  84   end
  85 end