---
name: "gnutls_reauth"
section: "3"
platform: "linux"
package: "gnutls"
version: "3.8.13-3"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/gnutls_reauth"
---

# gnutls\_reauth(3)

API function

## NAME

gnutls\_reauth - API function

## SYNOPSIS

**#include \<gnutls/gnutls.h\>**

**int gnutls\_reauth(gnutls\_session\_t** *session***, unsigned int** *flags***);**

## ARGUMENTS

- gnutls\_session\_t session

  is a **gnutls\_session\_t** type.

- unsigned int flags

  must be zero

## DESCRIPTION

This function performs the post-handshake authentication for TLS 1.3. The post-handshake authentication is initiated by the server by calling this function. Clients respond when **GNUTLS\_E\_REAUTH\_REQUEST** has been seen while receiving data.

The non-fatal errors expected by this function are: **GNUTLS\_E\_INTERRUPTED**, **GNUTLS\_E\_AGAIN**, as well as **GNUTLS\_E\_GOT\_APPLICATION\_DATA** when called on server side.

The former two interrupt the authentication procedure due to the transport layer being interrupted, and the latter because there were pending data prior to peer initiating the re-authentication. The server should read/process that data as unauthenticated and retry calling **gnutls\_reauth()**.

When this function is called under TLS1.2 or earlier or the peer didn't advertise post-handshake auth, it always fails with **GNUTLS\_E\_INVALID\_REQUEST**. The verification of the received peers certificate is delegated to the session or credentials verification callbacks. A server can check whether post handshake authentication is supported by the client by checking the session flags with **gnutls\_session\_get\_flags()**.

Prior to calling this function in server side, the function **gnutls\_certificate\_server\_set\_request()** must be called setting expectations for the received certificate (request or require). If none are set this function will return with **GNUTLS\_E\_INVALID\_REQUEST**.

Note that post handshake authentication is available irrespective of the initial negotiation type (PSK or certificate). In all cases however, certificate credentials must be set to the session prior to calling this function.

## RETURNS

**GNUTLS\_E\_SUCCESS** on a successful authentication, otherwise a negative error code.

## REPORTING BUGS

Report bugs to \<bugs@gnutls.org\>.\
 Home page: https://www.gnutls.org

## COPYRIGHT

Copyright © 2001-2023 Free Software Foundation, Inc., and others.\
 Copying and distribution of this file, with or without modification, are permitted in any medium without royalty provided the copyright notice and this notice are preserved.

## SEE ALSO

The full documentation for **gnutls** is maintained as a Texinfo manual. If the /usr/share/doc/gnutls/ directory does not contain the HTML form visit

- https://www.gnutls.org/manual/