Scroll to navigation

gnutls_session_ext_register(3) gnutls gnutls_session_ext_register(3)


gnutls_session_ext_register - API function


#include <gnutls/gnutls.h>

int gnutls_session_ext_register(gnutls_session_t session, const char * name, int id, gnutls_ext_parse_type_t parse_point, gnutls_ext_recv_func recv_func, gnutls_ext_send_func send_func, gnutls_ext_deinit_data_func deinit_func, gnutls_ext_pack_func pack_func, gnutls_ext_unpack_func unpack_func, unsigned flags);


the session for which this extension will be set
the name of the extension to register
the numeric id of the extension
the parse type of the extension (see gnutls_ext_parse_type_t)
a function to receive the data
a function to send the data
a function deinitialize any private data
a function which serializes the extension's private data (used on session packing for resumption)
a function which will deserialize the extension's private data
must be zero or flags from gnutls_ext_flags_t


This function will register a new extension type. The extension will be only usable within the registered session. If the extension type is already registered then GNUTLS_E_ALREADY_REGISTERED will be returned, unless the flag GNUTLS_EXT_FLAG_OVERRIDE_INTERNAL is specified. The latter flag when specified can be used to override certain extensions introduced after 3.6.0. It is expected to be used by applications which handle custom extensions that are not currently supported in GnuTLS, but direct support for them may be added in the future.

Each registered extension can store temporary data into the gnutls_session_t structure using gnutls_ext_set_data(), and they can be retrieved using gnutls_ext_get_data().

The validity of the extension registered can be given by the appropriate flags of gnutls_ext_flags_t. If no validity is given, then the registered extension will be valid for client and TLS1.2 server hello (or encrypted extensions for TLS1.3).


GNUTLS_E_SUCCESS on success, otherwise a negative error code.




Report bugs to <>.
Home page:


Copyright © 2001- 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.


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
3.7.7 gnutls