ASPC.Marvel.CrimeAPI.TokenHelper.GetRealmFromTargetUrl C# (CSharp) Метод

        public static string GetRealmFromTargetUrl(Uri targetApplicationUri)
        {
            WebRequest request = WebRequest.Create(targetApplicationUri + "/_vti_bin/client.svc");
            request.Headers.Add("Authorization: Bearer ");

            try
            {
                using (request.GetResponse())
                {
                }
            }
            catch (WebException e)
            {
                if (e.Response == null)
                {
                    return null;
                }

                string bearerResponseHeader = e.Response.Headers["WWW-Authenticate"];
                if (string.IsNullOrEmpty(bearerResponseHeader))
                {
                    return null;
                }

                const string bearer = "Bearer realm=\"";
                int bearerIndex = bearerResponseHeader.IndexOf(bearer, StringComparison.Ordinal);
                if (bearerIndex < 0)
                {
                    return null;
                }

                int realmIndex = bearerIndex + bearer.Length;

                if (bearerResponseHeader.Length >= realmIndex + 36)
                {
                    string targetRealm = bearerResponseHeader.Substring(realmIndex, 36);

                    Guid realmGuid;

                    if (Guid.TryParse(targetRealm, out realmGuid))
                    {
                        return targetRealm;
                    }
                }
            }
            return null;
        }