test.cs

namespace TXTextControl
{
    public class TXSecurityMiddleware
    {
        private RequestDelegate m_next;

        // stored access token usually retrieved from any storage
        // implemented thought OAuth or any other identity protocol
        private const string access_token = "821e2f35-86e3-4917-a963-b0c4228d1315";

        public TXSecurityMiddleware(RequestDelegate next)
        {
            m_next = next;
        }

    public async Task Invoke(HttpContext context)
    {
      // Check if the request is a TX Text Control request
      if (context.WebSockets.IsWebSocketRequest &&
        context.WebSockets.WebSocketRequestedProtocols.Contains("TXTextControl.Web") ||
        (context.Request.Query.ContainsKey("access_token") &&
        context.GetEndpoint()?.DisplayName?.Contains("TXTextControl.Web.MVC.DocumentViewer") == true))
      {
        // Retrieve access token from the query string
        var accessToken = context.Request.Query["access_token"];

        // Showcase only: Easy comparison of tokens
        if (accessToken != access_token)
        {
          throw new UnauthorizedAccessException();
        }
        else
        {
          await m_next.Invoke(context);
        }
      }
      else if (m_next != null)
      {
        await m_next.Invoke(context);
      }
    }

  }

}