How can I create an HttpListener class on a random port in C#?

Question

I would like to create an application that serves web pages internally and can be run in multiple instances on the same machine. To do so, I would like to create an H

Answer 1

Here's an answer, derived from Snooganz's answer. It avoids the race condition between testing for availability, and later binding.

public static bool TryBindListenerOnFreePort(out HttpListener httpListener, out int port)
{
    // IANA suggested range for dynamic or private ports
    const int MinPort = 49215;
    const int MaxPort = 65535;

    for (port = MinPort; port < MaxPort; port++)
    {
        httpListener = new HttpListener();
        httpListener.Prefixes.Add($"http://localhost:{port}/");
        try
        {
            httpListener.Start();
            return true;
        }
        catch
        {
            // nothing to do here -- the listener disposes itself when Start throws
        }
    }

    port = 0;
    httpListener = null;
    return false;
}

On my machine this method takes 15ms on average, which is acceptable for my use case. Hope this helps someone else.