gnutls_srp_set_server_credentials_function(3)

NAME
gnutls_srp_set_server_credentials_function - API function

SYNOPSIS
#include <gnutls/gnutls.h>

void gnutls_srp_set_server_credentials_function(gnutls_srp_server_credentials_t cred, gnutls_srp_server_credentials_function * func);

ARGUMENTS

gnutls_srp_server_credentials_t cred
    is a gnutls_srp_server_credentials_t type.

gnutls_srp_server_credentials_function * func
    is the callback function

DESCRIPTION
This function can be used to set a callback to retrieve the user's SRP credentials. The callback's function form is:

int (*callback)(gnutls_session_t, const char* username, gnutls_datum_t *salt, gnutls_datum_t *verifier, gnutls_datum_t *generator, gnutls_datum_t *prime);

 username contains the actual username. The salt , verifier , generator and prime must be filled in using the gnutls_malloc(). For convenience prime and generator may also be one of the static parameters defined in gnutls.h.

Initially, the data field is NULL in every gnutls_datum_t structure that the callback has to fill in. When the callback is done GnuTLS deallocates all of those buffers which are non-NULL, regardless of the return value.

In order to prevent attackers from guessing valid usernames, if a user does not exist, g and n values should be filled in using a random user's parameters. In that case the callback must return the special value (1). See gnutls_srp_set_server_fake_salt_seed too. If this is not required for your application, return a negative number from the callback to abort the handshake.

The callback function will only be called once per handshake. The callback function should return 0 on success, while -1 indicates an error.

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/