Added @Expiration for device

lib/upnp/control_point/device.rb

@@ -30,6 +30,8 @@ class Device < Base
  # @return [Hash] The whole parsed description... just in case.
  attr_reader :description
 
+ attr_reader :expiration
+
  #vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
  # Determined by device description file.
  #
@@ -139,6 +141,11 @@ def fetch
  @ext = ssdp_notification.has_key?(:ext) ? true : false
  @usn = ssdp_notification[:usn]
  @date = ssdp_notification[:date] || ''
+ @expiration = if @date.empty?
+ Time.now + @cache_control
+ else
+ @date + @cache_control
+ end
 
  if @location
  get_description(@location, description_getter)
@@ -204,6 +211,12 @@ def extract_url_base
  end
  end
 
+ # True if the device hasn't received an alive notification since it last
+ # told its max age.
+ def expired?
+ Time.now > @expiration if @expiration
+ end
+
  def has_devices?
  !@device_list.empty?
  end