lighttroupe/luz

#
# OSCServer is a non-blocking UDP server that parses each packet as OpenSoundControl
#
# https://en.wikipedia.org/wiki/User_Datagram_Protocol
#
# https://en.wikipedia.org/wiki/Open_Sound_Control
#
require 'socket'
require 'ipaddr'
require 'osc'

class IPSocket
    def set_reuse_address_flag
        setsockopt(Socket::SOL_SOCKET, Socket::SO_REUSEADDR, 1)            # this allows us to run twice without the socket complaining (OS won't necessarily deliver packets to both sockets, though)
        self
    end
end

class OSCServer
    READ_LIMIT = 1024*8   # any big number (NOTE: too big and read_nonblock sometimes takes a really long time...)

    attr_reader :ignored_message_count, :error_count

    def initialize
        @socket = UDPSocket.new.set_reuse_address_flag
        @socket_array = [@socket]
        @ignored_message_count, @error_count = 0, 0
    end

    def on_new_message(address, args)
        raise NotImplementedError        # override
    end

    def listen(address, port)
        ip = IPAddr.new(address).hton + IPAddr.new('0.0.0.0').hton
        @socket.setsockopt(Socket::IPPROTO_IP, Socket::IP_ADD_MEMBERSHIP, ip) rescue Errno::ENODEV    # don't die if there are no networks present to do this on
        @socket.bind(Socket::INADDR_ANY, port)
        self
    end

    def update(max_packets=nil)
        begin
            loop {
                # check readability of socket to avoid generating unnecessary Errno::EAGAIN exceptions
                return if IO.select(@socket_array, nil, nil, 0).nil?

                data = @socket.read_nonblock(READ_LIMIT)

                OSC::Packet.decode(data) { |address, args| on_new_message(address, args) }
                max_packets -= 1 if max_packets

                return if max_packets == 0
            }
        rescue Errno::EAGAIN
            # This is thrown by read_nonblock when there is no more data to read
            return
        rescue Exception => e
            puts e.report_format
            @error_count += 1
            return
        end
    end
end