test.cs

using Microsoft.AspNetCore.Http;
using System;
using System.Linq;
using System.Net;
using System.Threading.Tasks;
using TXTextControl.Web;

public class CustomWebSocketMiddleware {
	private RequestDelegate m_next;
	private IPAddress m_serviceAddress;
	private int m_servicePort;

	internal static readonly byte[] DefaultServiceAddress = { 127, 0, 0, 1 };
	internal const int DefaultServicePort = 4279;

	public CustomWebSocketMiddleware(RequestDelegate next) {
		m_next = next;
		m_serviceAddress = new IPAddress(DefaultServiceAddress);
		m_servicePort = DefaultServicePort;
	}

	public CustomWebSocketMiddleware(RequestDelegate next,
					 IPAddress serviceAddress,
					 int servicePort = DefaultServicePort) {
		m_next = next;
		m_serviceAddress = serviceAddress;
		m_servicePort = servicePort;
	}

	public CustomWebSocketMiddleware(RequestDelegate next,
					 string hostNameOrAddress,
					 int servicePort = DefaultServicePort) {
		m_next = next;
		IPAddress addr = Dns.GetHostAddresses(hostNameOrAddress).FirstOrDefault();
		if (addr == null) throw new Exception($"Host '{hostNameOrAddress}' not found.");
		m_serviceAddress = addr;
		m_servicePort = servicePort;
	}

	public async Task Invoke(HttpContext context) {
		if (context.WebSockets.IsWebSocketRequest &&
		  context.WebSockets.WebSocketRequestedProtocols.Contains("TXTextControl.Web")) {
			var ws = new WebSocketHandler(m_serviceAddress, m_servicePort);
			await ws.Invoke(context);
		}
		else if (m_next != null) {
			await m_next.Invoke(context);
		}
	}
}