How do I find which port number .Net Remoting Allocates?

Question

If I create a TcpChannel using port zero i.e. allowing .Net Remoting to allocate an available port, is there anyway to then determine which port number has been allocated?

I know that I can specify the port number when creating the channel, however I don't want to do this as I want to run multiple instances of the listening application on the same Citrix server - each instance listening on a different port.

Ideally I don't want to have to go to the trouble of reserving a bunch of ports and then keeping track of which ones have been allocated. I'd just like to let the port be allocated automatically - but then I need to be able to know which port number has been allocated.

Answer 1

My solution was as follows:

• Use the following code to identify an unused port for each instance of the client application:

  IPEndPoint endPoint = new IPEndPoint(IPAddress.Any, 0);
  
  using (Socket socket = new Socket(
               AddressFamily.InterNetwork, 
               SocketType.Stream, 
               ProtocolType.Tcp))
  {
      socket.Bind(endPoint);
      IPEndPoint local = (IPEndPoint)socket.LocalEndPoint;
      return local.Port;
  }
  

• Store the unused port number in the client application.

• Pass the stored port number to the host application via a command line parameter for use when setting up the TcpChannel and calling Activator.GetObject.

• Use the stored port number in the client application in the URL passed to Activator.GetObject.

Answer 2

I don't know much about this, but browsing at MSDN it states that post zero usage returns a TcpServerChannel, and a TcpServerChannel has a GetChannelUri() method; does that include the port number? (you might need to parse, via new Uri(s).Port).

Again, complete guess-work. If not, just say ;-p

edit by AakashM to add This is the correct approach. Following

var channel = new TcpChannel(0);

the dynamically-allocated post of the contained server channel can be retrieved with

var channelData = (ChannelDataStore)channel.ChannelData;
var port = new System.Uri(channelData.ChannelUris[0]).Port;

The ugly cast is necessary because the TcpChannel.ChannelData property is typed as object...