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" mtime = headers.key?("Last-Modified") ? Time.httpdate(headers["Last-Modified"]) : Time.now body = self.class.gzip(body, mtime) size = Rack::Utils.bytesize(body) headers = headers.merge("Content-Encoding" => "gzip", "Content-Length" => size.to_s) [status, headers, [body]] when "deflate" body = self.class.deflate(body) size = Rack::Utils.bytesize(body) headers = headers.merge("Content-Encoding" => "deflate", "Content-Length" => size.to_s) [status, headers, [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 def self.gzip(body, mtime) io = StringIO.new gzip = Zlib::GzipWriter.new(io) gzip.mtime = mtime # TODO: Add streaming body.each { |part| gzip << part } gzip.close return io.string end 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 ] # Loosely based on Mongrel's Deflate handler def self.deflate(body) deflater = Zlib::Deflate.new(*DEFLATE_ARGS) # TODO: Add streaming body.each { |part| deflater << part } return deflater.finish end end end