require "zlib" require "stringio" require "time" # for Time.httpdate require 'rack/utils' module Rack class Deflater def initialize(app) @app = app end def call(env) status, headers, body = @app.call(env) headers = Utils::HeaderHash.new(headers) # Skip compressing empty entity body responses and responses with # no-transform set. if Utils::STATUS_WITH_NO_ENTITY_BODY.include?(status) || headers['Cache-Control'].to_s =~ /\bno-transform\b/ return [status, headers, body] end request = Request.new(env) encoding = Utils.select_best_encoding(%w(gzip deflate identity), request.accept_encoding) # Set the Vary HTTP header. vary = headers["Vary"].to_s.split(",").map { |v| v.strip } unless vary.include?("*") || vary.include?("Accept-Encoding") headers["Vary"] = vary.push("Accept-Encoding").join(",") end case encoding when "gzip" headers['Content-Encoding'] = "gzip" headers.delete('Content-Length') mtime = headers.key?("Last-Modified") ? Time.httpdate(headers["Last-Modified"]) : Time.now [status, headers, GzipStream.new(body, mtime)] when "deflate" headers['Content-Encoding'] = "deflate" headers.delete('Content-Length') [status, headers, DeflateStream.new(body)] when "identity" [status, headers, body] when nil message = "An acceptable encoding for the requested resource #{request.fullpath} could not be found." [406, {"Content-Type" => "text/plain", "Content-Length" => message.length.to_s}, [message]] end end class GzipStream def initialize(body, mtime) @body = body @mtime = mtime end def each(&block) @writer = block gzip =::Zlib::GzipWriter.new(self) gzip.mtime = @mtime @body.each { |part| gzip.write(part) gzip.flush } @body.close if @body.respond_to?(:close) gzip.close @writer = nil end def write(data) @writer.call(data) end end class DeflateStream DEFLATE_ARGS = [ Zlib::DEFAULT_COMPRESSION, # drop the zlib header which causes both Safari and IE to choke -Zlib::MAX_WBITS, Zlib::DEF_MEM_LEVEL, Zlib::DEFAULT_STRATEGY ] def initialize(body) @body = body end def each deflater = ::Zlib::Deflate.new(*DEFLATE_ARGS) @body.each { |part| yield deflater.deflate(part, Zlib::SYNC_FLUSH) } @body.close if @body.respond_to?(:close) yield deflater.finish nil end end end end