Add auth mode check
@@ -1012,6 +1012,30 @@ static int ssl_conf_check(const mbedtls_ssl_context *ssl)
if( ret != 0 )
return( ret );
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
+ /* RFC 8446 section 4.4.3
+ *
+ * If the verification fails, the receiver MUST terminate the handshake with
+ * a "decrypt_error" alert.
+ *
+ * If the client is configured as TLS 1.3 only with optional verify, return
+ * bad config.
+ *
+ */
+ if( mbedtls_ssl_conf_tls13_ephemeral_enabled(
+ (mbedtls_ssl_context *)ssl ) &&
+ ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT &&
+ ssl->conf->max_tls_version == MBEDTLS_SSL_VERSION_TLS1_3 &&
+ ssl->conf->min_tls_version == MBEDTLS_SSL_VERSION_TLS1_3 &&
+ ssl->conf->authmode == MBEDTLS_SSL_VERIFY_OPTIONAL )
+ {
+ MBEDTLS_SSL_DEBUG_MSG(
+ 1, ( "Optional verfiy auth mode "
+ "is not available for TLS 1.3 client" ) );
+ return( MBEDTLS_ERR_SSL_BAD_CONFIG );
+ }
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
+
/* Space for further checks */
return( 0 );
