Let two UDP-servers listen on the same port?

Question

I have a client which sends data via UDP-broadcast. (To let\'s say 127.0.0.255:12345)

Now I want to have multiple servers listening to this data. To do so on a local

Answer 1

Several sources explain that you should use SO_REUSEADDR on windows. But none mention that it is possible to receive UDP message with and without binding the socket. The code below binds the socket to a local listen_endpoint, that is essential, because without that you can and will still receive your UDP messages, but by default your will have exclusive ownership of the port.

However if you set reuse_address(true) on the socket (or on the acceptor when using TCP), and bind the socket afterwards, it will enable multiple applications, or multiple instances of your own application to do it again, and everyone will receive all messages.

// Create the socket so that multiple may be bound to the same address.
boost::asio::ip::udp::endpoint listen_endpoint(
    listen_address, multicast_port);

// == important part ==
socket_.open(listen_endpoint.protocol());
socket_.set_option(boost::asio::ip::udp::socket::reuse_address(true));
socket_.bind(listen_endpoint);
// == important part ==

boost::array recvBuffer;
socket_.async_receive_from(boost::asio::buffer(recvBuffer), m_remote_endpoint,
        boost::bind(&SocketReader::ReceiveUDPMessage, this, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred)