setup_header

# File lib/webrick/httpresponse.rb, line 221
    def setup_header() # :nodoc:
      @reason_phrase    ||= HTTPStatus::reason_phrase(@status)
      @header['server'] ||= @config[:ServerSoftware]
      @header['date']   ||= Time.now.httpdate

      # HTTP/0.9 features
      if @request_http_version < "1.0"
        @http_version = HTTPVersion.new("0.9")
        @keep_alive = false
      end

      # HTTP/1.0 features
      if @request_http_version < "1.1"
        if chunked?
          @chunked = false
          ver = @request_http_version.to_s
          msg = "chunked is set for an HTTP/#{ver} request. (ignored)"
          @logger.warn(msg)
        end
      end

      # Determine the message length (RFC2616 -- 4.4 Message Length)
      if @status == 304 || @status == 204 || HTTPStatus::info?(@status)
        @header.delete('content-length')
        @body = ""
      elsif chunked?
        @header["transfer-encoding"] = "chunked"
        @header.delete('content-length')
      elsif %{^multipart/byteranges} =~ @header['content-type']
        @header.delete('content-length')
      elsif @header['content-length'].nil?
        unless @body.is_a?(IO)
          @header['content-length'] = @body ? @body.bytesize : 0
        end
      end

      # Keep-Alive connection.
      if @header['connection'] == "close"
         @keep_alive = false
      elsif keep_alive?
        if chunked? || @header['content-length'] || @status == 304 || @status == 204 || HTTPStatus.info?(@status)
          @header['connection'] = "Keep-Alive"
        else
          msg = "Could not determine content-length of response body. Set content-length of the response or set Response#chunked = true"
          @logger.warn(msg)
          @header['connection'] = "close"
          @keep_alive = false
        end
      else
        @header['connection'] = "close"
      end

      # Location is a single absoluteURI.
      if location = @header['location']
        if @request_uri
          @header['location'] = @request_uri.merge(location)
        end
      end
    end