require 'rack/utils' module Rack # Sets the Content-Length header on responses with fixed-length bodies. class ContentLength include Rack::Utils def initialize(app) @app = app end def call(env) status, headers, body = @app.call(env) headers = HeaderHash.new(headers) if !STATUS_WITH_NO_ENTITY_BODY.include?(status) && !headers['Content-Length'] && !headers['Transfer-Encoding'] && (body.respond_to?(:to_ary) || body.respond_to?(:to_str)) body = [body] if body.respond_to?(:to_str) # rack 0.4 compat length = body.to_ary.inject(0) { |len, part| len + bytesize(part) } headers['Content-Length'] = length.to_s end [status, headers, body] end end end