System.Net.Security.SecureChannel.GetAlertMessageFromChain C# (CSharp) Method

        private static TlsAlertMessage GetAlertMessageFromChain(X509Chain chain)
        {
            foreach (X509ChainStatus chainStatus in chain.ChainStatus)
            {
                if (chainStatus.Status == X509ChainStatusFlags.NoError)
                {
                    continue;
                }

                if ((chainStatus.Status &
                    (X509ChainStatusFlags.UntrustedRoot | X509ChainStatusFlags.PartialChain |
                     X509ChainStatusFlags.Cyclic)) != 0)
                {
                    return TlsAlertMessage.UnknownCA;
                }

                if ((chainStatus.Status &
                    (X509ChainStatusFlags.Revoked | X509ChainStatusFlags.OfflineRevocation )) != 0)
                {
                    return TlsAlertMessage.CertificateRevoked;
                }

                if ((chainStatus.Status &
                    (X509ChainStatusFlags.CtlNotTimeValid | X509ChainStatusFlags.NotTimeNested |
                     X509ChainStatusFlags.NotTimeValid)) != 0)
                {
                    return TlsAlertMessage.CertificateExpired;
                }

                if ((chainStatus.Status & X509ChainStatusFlags.CtlNotValidForUsage) != 0)
                {
                    return TlsAlertMessage.UnsupportedCert; 
                }

                if ((chainStatus.Status &
                    (X509ChainStatusFlags.CtlNotSignatureValid | X509ChainStatusFlags.InvalidExtension |
                     X509ChainStatusFlags.NotSignatureValid | X509ChainStatusFlags.InvalidPolicyConstraints) |
                     X509ChainStatusFlags.NoIssuanceChainPolicy | X509ChainStatusFlags.NotValidForUsage) != 0)
                {
                    return TlsAlertMessage.BadCertificate;
                }

                // All other errors:
                return TlsAlertMessage.CertificateUnknown;
            }

            Debug.Fail("GetAlertMessageFromChain was called but none of the chain elements had errors.");
            return TlsAlertMessage.BadCertificate;
        }