Joining a multicast group with Ruby

ruby-mcast-join.rb

#!/usr/bin/env ruby

require 'rubygems'
require 'socket'
require 'ipaddr'

MCAST_GROUP = {
  :addr => '224.5.6.7',
  :port => 12345,
  :bindaddr => '192.168.1.2'
}

ip = IPAddr.new(MCAST_GROUP[:addr]).hton + IPAddr.new(MCAST_GROUP[:bindaddr]).hton

begin
  sock = UDPSocket.open
  sock.setsockopt Socket::IPPROTO_IP, Socket::IP_ADD_MEMBERSHIP, ip
  sock.bind Socket::INADDR_ANY, MCAST_GROUP[:port]

  loop do
    msg, info = sock.recvfrom(1024)
    puts "MSG: #{msg} from #{info[2]} (#{info[3]})/#{info[1]} len #{msg.size}"
  end
ensure
  sock.close
end