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. You are
advised to use gnutls_certificate_set_retrieve_function2() because it
is much more efficient in the processing it requires from gnutls.
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,
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 signature
algorithms. The certificate returned should support the server's
st should contain the certificates and private keys.
If the callback function is provided then gnutls will call it, in the
handshake, after the certificate request message has been received.
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
This page is part of the GnuTLS (GnuTLS Transport Layer Security
Library) project. Information about the project can be found at
⟨http://www.gnutls.org/⟩. If you have a bug report for this manual
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⟨http://www.gnutls.org/download.html⟩ on 2017-03-13. If you discover
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