---
name: "gnutls_session_supplemental_register"
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_session_supplemental_register"
---

# gnutls\_session\_supplemental\_register(3)

API function

## NAME

gnutls\_session\_supplemental\_register - API function

## SYNOPSIS

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

**int gnutls\_session\_supplemental\_register(gnutls\_session\_t** *session***, const char \*** *name***, gnutls\_supplemental\_data\_format\_type\_t** *type***, gnutls\_supp\_recv\_func** *recv\_func***, gnutls\_supp\_send\_func** *send\_func***, unsigned** *flags***);**

## ARGUMENTS

- gnutls\_session\_t session

  the session for which this will be registered

- const char \* name

  the name of the supplemental data to register

- gnutls\_supplemental\_data\_format\_type\_t type

  the type of the supplemental data format

- gnutls\_supp\_recv\_func recv\_func

  the function to receive the data

- gnutls\_supp\_send\_func send\_func

  the function to send the data

- unsigned flags

  must be zero

## DESCRIPTION

This function will register a new supplemental data type (rfc4680). The registered supplemental functions will be used for that specific session. The provided  *type* must be an unassigned type in **gnutls\_supplemental\_data\_format\_type\_t**.

If the type is already registered or handled by GnuTLS internally **GNUTLS\_E\_ALREADY\_REGISTERED** will be returned.

As supplemental data are not defined under TLS 1.3, this function will disable TLS 1.3 support for the given session.

## RETURNS

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

## SINCE

3\.5.5

## 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/