Question

I’m using this bit of code to send and receive data, problem is I don’t receive anything..

Code:

US_HOST = "239.255.255.250"
US_PORT = 1900

module SSDP
  class Client < EventMachine::Connection
    def receive_data data
      p "Received some data:"
      p data
    end
  end
end

us = EM.open_datagram_socket US_HOST, US_PORT, SSDP::Client

us.send_data msg

def msg
<<-MSEARCH
M-SEARCH * HTTP/1.1\r
HOST: #{US_HOST}:#{US_PORT}\r
MAN: ssdp:discover\r
MX: 1\r
ST: ssdp:all\r
\r
MSEARCH
end

If I’m sending the exact same message with Ruby’s UDPSocket I do receive data (from the UDPSocket, not from EM)..

Can someone tell me what I’m doing wrong here?

Thanks

Answer 1

This is how i got EventMachine to setup a datagram socket and listen for SSDP announcments.

Change:

us = EM.open_datagram_socket(US_HOST, US_PORT, SSDP::Client)

To:

us = EM.open_datagram_socket('0.0.0.0', US_PORT, SSDP::Client)

You have to actually bind to your ip address and not the multicast address. Then add a constructor to your client class where you tell the socket to join the multicast group for SSDP.

class Client < EventMachine::Connection

def initialize
  puts "Socket setup"
  set_sock_opt(Socket::IPPROTO_IP, Socket::IP_ADD_MEMBERSHIP, 
               IPAddr.new('239.255.255.250').hton +
               IPAddr.new('0.0.0.0').hton)
end


.....