---
name: "gnutls_certificate_set_retrieve_function3"
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_certificate_set_retrieve_function3"
---

# gnutls\_certificate\_set\_retrieve\_function3(3)

API function

## NAME

gnutls\_certificate\_set\_retrieve\_function3 - API function

## SYNOPSIS

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

**void gnutls\_certificate\_set\_retrieve\_function3(gnutls\_certificate\_credentials\_t** *cred***, gnutls\_certificate\_retrieve\_function3 \*** *func***);**

## ARGUMENTS

- gnutls\_certificate\_credentials\_t cred

  is a **gnutls\_certificate\_credentials\_t** type.

- gnutls\_certificate\_retrieve\_function3 \* func

  is the callback function

## DESCRIPTION

This function sets a callback to be called in order to retrieve the certificate and OCSP responses to be used in the handshake.  *func* will be called only if the peer requests a certificate either during handshake or during post-handshake authentication.

The callback's function prototype is defined in \`abstract.h':

int gnutls\_certificate\_retrieve\_function3( gnutls\_session\_t, const struct gnutls\_cert\_retr\_st \*info, gnutls\_pcert\_st \*\*certs, unsigned int \*certs\_length, gnutls\_ocsp\_data\_st \*\*ocsp, unsigned int \*ocsp\_length, gnutls\_privkey\_t \*privkey, unsigned int \*flags);

The info field of the callback contains:\
  *req\_ca\_dn* which is a list with the CA names that the server considers trusted. This is a hint and typically the client should send a certificate that is signed by one of these CAs. These names, when available, are DER encoded. To get a more meaningful value use the function **gnutls\_x509\_rdn\_get()**.\
  *pk\_algos* contains a list with server's acceptable public key algorithms. The certificate returned should support the server's given algorithms.

The callback should fill-in the following values:

 *certs* should contain an allocated list of certificates and public keys.\
  *certs\_length* is the size of the previous list.\
  *ocsp* should contain an allocated list of OCSP responses.\
  *ocsp\_length* is the size of the previous list.\
  *privkey* is the private key.

If flags in the callback are set to **GNUTLS\_CERT\_RETR\_DEINIT\_ALL** then all provided values must be allocated using **gnutls\_malloc()**, and will be released by gnutls; otherwise they will not be touched by gnutls.

The callback function should set the certificate and OCSP response list to be sent, and return 0 on success. If no certificates are available, the  *certs\_length* and  *ocsp\_length* should be set to zero. The return value (-1) indicates error and the handshake will be terminated. If both certificates are set in the credentials and a callback is available, the callback takes predence.

Raw public-keys: In case raw public-keys are negotiated as certificate type, certificates that would normally hold the public-key material are not available. In that case,\
  *certs* contains an allocated list with only the public key. Since there is no certificate, there is also no certificate status. Therefore, OCSP information should not be set.

## SINCE

3\.6.3

## 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/