gnutls_dtls_cookie_send man page

gnutls_dtls_cookie_send — API function


#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 push_func);


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_dtls_cookie_verify()
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


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 gnutls_dtls_cookie_verify().


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



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3.5.8 gnutls gnutls