gnutls_certificate_set_retrieve_function2 - API function

       #include <gnutls/abstract.h>

       cred, gnutls_certificate_retrieve_function2 * func);

       gnutls_certificate_credentials_t cred
                   is a gnutls_certificate_credentials_t type.

       gnutls_certificate_retrieve_function2 * func
                   is the callback function

       This function sets a callback to be called in order to retrieve the
       certificate to be used in the handshake. The callback will take control
       only if a certificate is requested by the peer.

       The callback's function prototype is: int (*callback)(gnutls_session_t,
       const gnutls_datum_t* req_ca_dn, int nreqs, const gnutls_pk_algorithm_t*
       pk_algos, int pk_algos_length, gnutls_pcert_st** pcert, unsigned int
       *pcert_length, gnutls_privkey_t * pkey);

        req_ca_dn is only used in X.509 certificates.  Contains 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.

        pcert should contain a single certificate and public key or a list of

        pcert_length is the size of the previous list.

        pkey is the private key.

       If the callback function is provided then gnutls will call it, in the
       handshake, after the certificate request message has been received.  All
       the provided by the callback values will not be released or modified by

       In server side pk_algos and req_ca_dn are NULL.

       The callback function should set the certificate list to be sent, and
       return 0 on success. If no certificate was selected then the number of
       certificates should be set to zero. The 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.


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gnutls                              gnutls0certificate_set_retrieve_function2(3)