// Verify if request has JWT.
func isRequestJWT(r *http.Request) bool {
	return strings.HasPrefix(r.Header.Get(xhttp.Authorization), jwtAlgorithm)
}

// Verify if request has AWS Signature Version '4'.
func isRequestSignatureV4(r *http.Request) bool {
	return strings.HasPrefix(r.Header.Get(xhttp.Authorization), signV4Algorithm)
}

// Verify if request has AWS Signature Version '2'.
func isRequestSignatureV2(r *http.Request) bool {

func hasMultipleAuth(r *http.Request) bool {
	authTypeCount := 0
	for _, hasValidAuth := range []func(*http.Request) bool{
		isRequestSignatureV2, isRequestPresignedSignatureV2,
		isRequestSignatureV4, isRequestPresignedSignatureV4,
		isRequestJWT, isRequestPostPolicySignatureV4,
	} {
		if hasValidAuth(r) {
			authTypeCount++
		}
	}
	return authTypeCount > 1
}

	case ErrInternalError:
		return ErrSTSInternalError
	default:
		return ErrSTSAccessDenied
	}
}

func checkAssumeRoleAuth(ctx context.Context, r *http.Request) (auth.Credentials, APIErrorCode) {
	if !isRequestSignatureV4(r) {
		return auth.Credentials{}, ErrAccessDenied
	}

	s3Err := isReqAuthenticated(ctx, r, globalSite.Region(), serviceSTS)
	if s3Err != ErrNone {
		return auth.Credentials{}, s3Err
	}