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require "zlib"
require "stringio"
module Rack
class Deflater
def initialize(app)
@app = app
end
def call(env)
status, headers, body = @app.call(env)
request = Request.new(env)
encoding = Utils.select_best_encoding(%w(gzip deflate identity), request.accept_encoding)
case encoding
when "gzip"
mtime = headers["Last-Modified"] || Time.now
[status, headers.merge("Content-Encoding" => "gzip"), self.class.gzip(body, mtime)]
when "deflate"
[status, headers.merge("Content-Encoding" => "deflate"), self.class.deflate(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"}, 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
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