content_directory.rb

require 'open3'
require 'uri'

require 'rubygems'
require 'UPnP/service'

##
# A UPnP ContentDirectory service.  See upnp.org for specifications.

class UPnP::Service::ContentDirectory < UPnP::Service

  VERSION = '1.0'

  ##
  # Returns the searching capabilities supported by the device

  add_action 'GetSearchCapabilities',
    [OUT, 'SearchCaps', 'SearchCapabilities']

  ##
  # Returns the CSV list of metadata tags that can be used in sortCriteria

  add_action 'GetSortCapabilities',
    [OUT, 'SortCaps', 'SortCapabilities']

  add_action 'GetSystemUpdateID',
    [OUT, 'Id', 'SystemUpdateID']

  add_action 'Browse',
    [IN, 'ObjectID',       'A_ARG_TYPE_ObjectID'],
    [IN, 'BrowseFlag',     'A_ARG_TYPE_BrowseFlag'],
    [IN, 'Filter',         'A_ARG_TYPE_Filter'],
    [IN, 'StartingIndex',  'A_ARG_TYPE_Index'],
    [IN, 'RequestedCount', 'A_ARG_TYPE_Count'],
    [IN, 'SortCriteria',   'A_ARG_TYPE_SortCriteria'],

    [OUT, 'Result',         'A_ARG_TYPE_Result'],
    [OUT, 'NumberReturned', 'A_ARG_TYPE_Count'],
    [OUT, 'TotalMatches',   'A_ARG_TYPE_Count'],
    [OUT, 'UpdateID',       'A_ARG_TYPE_UpdateID']

  # optional actions

  add_action 'Search',
    [IN, 'ContainerID', 'A_ARG_TYPE_ObjectID'],
    [IN, 'SearchCriteria', 'A_ARG_TYPE_SearchCriteria'],
    [IN, 'Filter', 'A_ARG_TYPE_Filter'],
    [IN, 'StartingIndex', 'A_ARG_TYPE_Index'],
    [IN, 'RequestedCount', 'A_ARG_TYPE_Count'],
    [IN, 'SortCriteria', 'A_ARG_TYPE_SortCriteria'],

    [OUT, 'Result', 'A_ARG_TYPE_Result'],
    [OUT, 'NumberReturned', 'A_ARG_TYPE_Count'],
    [OUT, 'TotalMatches', 'A_ARG_TYPE_Count'],
    [OUT, 'UpdateID', 'A_ARG_TYPE_UpdateID']

  add_action 'CreateObject',
    [IN, 'ContainerID', 'A_ARG_TYPE_ObjectID'],
    [IN, 'Elements', 'A_ARG_TYPE_Result'],

    [OUT, 'ObjectID', 'A_ARG_TYPE_ObjectID'],
    [OUT, 'Result', 'A_ARG_TYPE_Result']

  add_action 'DestroyObject',
    [IN, 'ObjectID', 'A_ARG_TYPE_ObjectID']

  add_action 'UpdateObject',
    [IN, 'ObjectID', 'A_ARG_TYPE_ObjectID'],
    [IN, 'CurrentTagValue', 'A_ARG_TYPE_TagValueList'],
    [IN, 'NewTagValue', 'A_ARG_TYPE_TagValueList']

  add_action 'ImportResource',
    [IN, 'SourceURI', 'A_ARG_TYPE_URI'],
    [IN, 'DestinationURI', 'A_ARG_TYPE_URI'],

    [OUT, 'TransferID', 'A_ARG_TYPE_TransferID']

  add_action 'ExportResource',
    [IN, 'SourceURI', 'A_ARG_TYPE_URI'],
    [IN, 'DestinationURI', 'A_ARG_TYPE_URI'],

    [OUT, 'TransferID', 'A_ARG_TYPE_TransferID']

  add_action 'StopTransferResource',
    [IN, 'TransferID', 'A_ARG_TYPE_TransferID']

  add_action 'GetTransferProgress',
    [IN, 'TransferID', 'A_ARG_TYPE_TransferID'],

    [OUT, 'TransferStatus', 'A_ARG_TYPE_TransferStatus'],
    [OUT, 'TransferLength', 'A_ARG_TYPE_TransferLength'],
    [OUT, 'TransferTotal', 'A_ARG_TYPE_TransferTotal']

  add_action 'DeleteResource',
    [IN, 'ResourceURI', 'A_ARG_TYPE_URI']

  add_action 'CreateReference',
    [IN, 'ContainerID', 'A_ARG_TYPE_ObjectID'],
    [IN, 'ObjectID', 'A_ARG_TYPE_ObjectID'],
    [OUT, 'NewID', 'A_ARG_TYPE_ObjectID']

  add_variable 'TransferIDs',               'string', nil, nil, true
  add_variable 'A_ARG_TYPE_ObjectID',       'string'
  add_variable 'A_ARG_TYPE_Result',         'string' # 2.5.4 - DIDL-Lite
  add_variable 'A_ARG_TYPE_SearchCriteria', 'string' # 2.5.5
  add_variable 'A_ARG_TYPE_BrowseFlag',     'string',
               %w[BrowseMetadata BrowseDirectChildren]
  add_variable 'A_ARG_TYPE_Filter',         'string' # 2.5.7
  add_variable 'A_ARG_TYPE_SortCriteria',   'string' # 2.5.8
  add_variable 'A_ARG_TYPE_Index',          'ui4'    # 2.5.9
  add_variable 'A_ARG_TYPE_Count',          'ui4'    # 2.5.10
  add_variable 'A_ARG_TYPE_UpdateID',       'ui4'    # 2.5.11
  add_variable 'A_ARG_Type_TransferID',     'ui4'    # 2.5.12
  add_variable 'A_ARG_Type_TransferStatus', 'string' # 2.5.13
  add_variable 'A_ARG_Type_TransferLength', 'string' # 2.5.14
  add_variable 'A_ARG_Type_TransferTotal',  'string' # 2.5.15
  add_variable 'A_ARG_TYPE_TagValueList',   'string' # 2.5.16
  add_variable 'A_ARG_TYPE_URI',            'uri'    # 2.5.17
  add_variable 'SearchCapabilities',        'string' # 2.5.18
  add_variable 'SortCapabilities',          'string' # 2.5.19
  add_variable 'SystemUpdateID',            'ui4',    nil, nil, true # 2.5.20
  add_variable 'ContainerUpdateIDs',        'string', nil, nil, true # 2.5.21

  def initialize(*args)
    @directories = []

    super
  end

  def on_init
    @SystemUpdateID = 0

    @object_count = 0
    @objects = {}
    @parents = {}

    add_object 'root', -1
    WEBrick::HTTPUtils::DefaultMimeTypes['mp3'] = 'audio/mpeg'
  end

  # :section: ContentServer implementation

  ##
  # Allows the caller to incrementally browse the hierarchy of the content
  # directory, including information listing the classes of objects available
  # in any container.

  def Browse(object_id, browse_flag, filter, starting_index, requested_count,
             sort_criteria)
    filter = filter.split ','
    object_id = object_id.to_i
    update_id = 0

    case browse_flag
    when 'BrowseMetadata' then
      number_returned = 1
      total_matches = 1

      result = metadata_result object_id
    when 'BrowseDirectChildren' then
      number_returned, total_matches, result = children_result object_id
    else
      raise "unknown BrowseFlag #{browse_flag}"
    end

    [nil, result, number_returned, total_matches, update_id]
  end

  ##
  # Returns the current value of the SystemUpdateID state variable.  For use
  # by clients that want to poll for any changes in the content directory
  # instead of subscribing to events.

  def GetSystemUpdateID
    [nil, @SystemUpdateID]
  end

  # :section: Support implementation

  ##
  # Adds object +name+ to the directory tree under +parent+

  def add_object(name, parent)
    object_id = @object_count
    @object_count += 1

    @objects[object_id] = name
    @objects[name] = object_id

    @parents[object_id] = parent

    object_id
  end

  ##
  # Adds +directory+ as a path searched by the content server

  def add_directory(directory)
    return self if @directories.include? directory

    add_object directory, 0
    @directories << directory

    self
  end

  def children_result(object_id)
    object = get_object object_id

    children = if object_id == 0 then
                 @directories
               else
                 Dir[File.join(object, '*')]
               end

    result = make_result do |xml|
      children.each do |child|
        child_id = get_object child, object_id

        result_object xml, child, child_id, File.basename(child)
      end
    end

    [children.length, children.length, result]
  end

  def get_object(name, parent_id = nil)
    if @objects.key? name then
      @objects[name]
    elsif parent_id.nil? then
      raise Error, "object #{name} does not exist"
    else
      add_object name, parent_id
    end
  end

  def get_parent(object_id)
    if @parents.key? object_id then
      @parents[object_id]
    else
      raise Error, "invalid object id #{object_id}"
    end
  end

  def item_class(mime_type)
    case mime_type
    when /^image/ then
      'object.item.imageItem'
    when /^audio/ then
      'object.item.audioItem'
    else
      puts "unhandled mime type #{mime_type}"
      'object.item'
    end
  end

  def make_result
    result = []

    xml = Builder::XmlMarkup.new :indent => 2, :target => result
    xml.tag! 'DIDL-Lite',
             'xmlns' => 'urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/',
             'xmlns:dc' => 'http://purl.org/dc/elements/1.1/',
             'xmlns:upnp' => 'urn:schemas-upnp-org:metadata-1-0/upnp/' do
      yield xml
    end

    result.join
  end

  def metadata_result(object_id)
    object = get_object object_id
    parent = get_parent object_id

    title = File.basename object

    make_result do |xml|
      result_object xml, object, object_id, title
    end
  end

  def mount_extra(http_server)
    super

    @directories.each do |root|
      root_id = get_object root
      path = File.join service_path, root_id.to_s

      http_server.mount path, WEBrick::HTTPServlet::FileHandler, root
    end
  end

  def resource(xml, object, mime_type, stat)
    info = nil
    url = nil

    case mime_type
    when /^audio\/(.*)/ then
      pn = case $1
           when 'mpeg' then
             'MP3'
           end

      pn = "DLNA.ORG_PN=#{pn}"

      additional = [pn, 'DLNA.ORG_OP=01', 'DLNA.ORG_CI=0'].compact.join ';'

      info = ['http-get', '*', mime_type, additional]
    when /^image\/(.*)/ then
      pn = case $1
           when 'jpeg' then
             'JPEG_LRG'
           end

      pn = "DLNA.ORG_PN=#{pn}"

      additional = [pn, 'DLNA.ORG_OP=01', 'DLNA.ORG_CI=0'].compact.join ';'

      info = ['http-get', '*', mime_type, additional]
    end

    if info then
      url = resource_url object

      attributes = {
        :protocolInfo => info.join(':'),
        :size => stat.size,
      }

      xml.res attributes, URI.escape(url)
    end
  end

  ##
  # A URL to this object on this server.  Correctly handles multi-homed
  # servers.

  def resource_url(object)
    _, port, host, addr = Thread.current[:WEBrickSocket].addr

    root = root_for object
    root_id = get_object root

    object = object.sub root, ''

    File.join "http://#{addr}:#{port}", service_path, root_id.to_s, object
  end

  def result_object(xml, object, object_id, title)
    if object_id == 0 then
      result_container xml, object, object_id, @directories.length, title
    elsif File.directory? object then
      children = Dir[File.join(object, '*/')].length

      result_container xml, object, object_id, children, title
    else
      result_item xml, object, object_id, title
    end
  end

  def result_container(xml, object, object_id, children, title)
    xml.tag! 'container', :id => object_id, :parentID => get_parent(object_id),
                   :restricted => true, :childCount => children do
      xml.dc :title, title
      xml.upnp :class, 'object.container'
    end
  end

  def result_item(xml, object, object_id, title)
    inn, out, = Open3.popen3('file', '-bI', object)
    inn.close

    mime_type = out.read.strip

    stat = File.stat object

    xml.tag! 'item', :id => object_id, :parentID => get_parent(object_id),
             :restricted => true, :childCount => 0 do
      xml.dc :title, title
      xml.dc :date, stat.ctime.iso8601
      xml.upnp :class, item_class(mime_type)

      resource xml, object, mime_type, stat
    end
  end

  ##
  # Returns the root for +object_id+

  def root_for(object_id)
    object_id = get_object object_id unless Integer === object_id

    while (parent_id = get_parent(object_id)) != 0 do
      object_id = parent_id
    end

    get_object object_id
  end

end