gnutls_dtls_cookie_send(3) — Linux manual page


gnutls_dtls_cookie_send(3)       gnutls       gnutls_dtls_cookie_send(3)

NAME         top

       gnutls_dtls_cookie_send - API function

SYNOPSIS         top

       #include <gnutls/dtls.h>

       int gnutls_dtls_cookie_send(gnutls_datum_t * key, void *
       client_data, size_t client_data_size, gnutls_dtls_prestate_st *
       prestate, gnutls_transport_ptr_t ptr, gnutls_push_func

ARGUMENTS         top

       gnutls_datum_t * key
                   is a random key to be used at cookie generation

       void * client_data
                   contains data identifying the client (i.e. address)

       size_t client_data_size
                   The size of client's data

       gnutls_dtls_prestate_st * prestate
                   The previous cookie returned by

       gnutls_transport_ptr_t ptr
                   A transport pointer to be used by  push_func

       gnutls_push_func push_func
                   A function that will be used to reply

DESCRIPTION         top

       This function can be used to prevent denial of service attacks to
       a DTLS server by requiring the client to reply using a cookie
       sent by this function. That way it can be ensured that a client
       we allocated resources for (i.e. gnutls_session_t) is the one
       that the original incoming packet was originated from.

       This function must be called at the first incoming packet, prior
       to allocating any resources and must be succeeded by

RETURNS         top

       the number of bytes sent, or a negative error code.

SINCE         top


REPORTING BUGS         top

       Report bugs to <>.
       Home page:

COPYRIGHT         top

       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         top

       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

COLOPHON         top

       This page is part of the GnuTLS (GnuTLS Transport Layer Security
       Library) project.  Information about the project can be found at
       ⟨⟩.  If you have a bug report for this
       manual page, send it to  This page was obtained
       from the tarball gnutls-3.8.2.tar.xz fetched from
       ⟨⟩ on 2023-12-22.  If you
       discover any rendering problems in this HTML version of the page,
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gnutls                            3.8.2       gnutls_dtls_cookie_send(3)