Class: EasyUpnp::SsdpSearcher

Inherits:
Object
  • Object
show all
Defined in:
lib/easy_upnp/ssdp_searcher.rb

Constant Summary collapse

MULTICAST_ADDR =

These are dictated by the SSDP protocol and cannot be changed

'239.255.255.250'
MULTICAST_PORT = 
1900
DEFAULT_OPTIONS = 
{
    # Number of seconds to wait for responses
    :timeout => 2,

    # Part of the SSDP protocol. Servers should delay a random amount of time between 0 and N
    # seconds before sending the response.
    :mx => 1,

    # Sometimes recommended to send repeat M-SEARCH queries. Control that here.
    :repeat_queries => 1
}

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ SsdpSearcher

Returns a new instance of SsdpSearcher.



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# File 'lib/easy_upnp/ssdp_searcher.rb', line 25

def initialize(options = {})
  unsupported_args = options.keys.reject { |x| DEFAULT_OPTIONS[x] }
  raise RuntimeError.new "Unsupported arguments: #{unsupported_args}" if unsupported_args.any?

  @options = DEFAULT_OPTIONS.merge options
end

Instance Method Details

#construct_msearch_packet(urn) ⇒ Object 



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# File 'lib/easy_upnp/ssdp_searcher.rb', line 71

def construct_msearch_packet(urn)
  <<-MSEARCH
M-SEARCH * HTTP/1.1\r
HOST: #{MULTICAST_ADDR}:#{MULTICAST_PORT}\r
MAN: "ssdp:discover"\r
MX: #{option :mx}\r
ST: #{urn}\r
\r
  MSEARCH
end

#option(key) ⇒ Object 



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# File 'lib/easy_upnp/ssdp_searcher.rb', line 32

def option(key)
  @options[key]
end

#parse_message(message) ⇒ Object 



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# File 'lib/easy_upnp/ssdp_searcher.rb', line 82

def parse_message(message)
  lines = message.split "\r\n"
  headers = lines.map do |line|
    if !(match = line.match(/([^:]+):\s?(.*)/i)).nil?
      header, value = match.captures
      key = header.
          downcase.
          gsub('-', '_').
          to_sym

      [key, value]
    end
  end

  Hash[headers.reject(&:nil?)]
end

#search(urn = 'ssdp:all') ⇒ Object 



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# File 'lib/easy_upnp/ssdp_searcher.rb', line 36

def search(urn = 'ssdp:all')
  socket = build_socket
  packet = construct_msearch_packet(urn)

  # Send M-SEARCH packet over UDP socket
  option(:repeat_queries).times do
    socket.send packet, 0, MULTICAST_ADDR, MULTICAST_PORT
  end

  raw_messages = []

  # Wait for responses. Timeout after a specified number of seconds
  begin
    Timeout::timeout(option :timeout) do
      loop do
        raw_messages.push(socket.recv(4196))
      end
    end
  rescue Timeout::Error
    # This is expected
  ensure
    socket.close
  end

  # Parse messages (extract HTTP headers)
  parsed_messages = raw_messages.map { |x| parse_message x }

  # Group messages by device they come from (identified by a UUID in the 'USN' header),
  # and create UpnpDevices for them. This wrap the services advertized by the SSDP
  # results.
  parsed_messages.reject { |x| !x[:usn] }.group_by { |x| x[:usn].split('::').first }.map do |k, v|
    UpnpDevice.from_ssdp_messages(k, v)
  end
end