---
name: "gnutls_x509_crt_get_extension_oid"
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_x509_crt_get_extension_oid"
---

# gnutls\_x509\_crt\_get\_extension\_oid(3)

API function

## NAME

gnutls\_x509\_crt\_get\_extension\_oid - API function

## SYNOPSIS

**#include \<gnutls/x509.h\>**

**int gnutls\_x509\_crt\_get\_extension\_oid(gnutls\_x509\_crt\_t** *cert***, unsigned** *indx***, void \*** *oid***, size\_t \*** *oid\_size***);**

## ARGUMENTS

- gnutls\_x509\_crt\_t cert

  should contain a **gnutls\_x509\_crt\_t** type

- unsigned indx

  Specifies which extension OID to send. Use (0) to get the first one.

- void \* oid

  a pointer to a structure to hold the OID (may be null)

- size\_t \* oid\_size

  initially holds the size of  *oid*

## DESCRIPTION

This function will return the requested extension OID in the certificate. The extension OID will be stored as a string in the provided buffer.

The  *oid* returned will be null terminated, although  *oid\_size* will not account for the trailing null.

## RETURNS

On success, **GNUTLS\_E\_SUCCESS** (0) is returned, otherwise a negative error code is returned.  If you have reached the last extension available **GNUTLS\_E\_REQUESTED\_DATA\_NOT\_AVAILABLE** will be returned.

## 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/