1=pod 2 3=head1 NAME 4 5SSL_CTX_set_stateless_cookie_generate_cb, 6SSL_CTX_set_stateless_cookie_verify_cb 7- Callback functions for stateless TLS1.3 cookies 8 9=head1 SYNOPSIS 10 11 #include <openssl/ssl.h> 12 13 void SSL_CTX_set_stateless_cookie_generate_cb( 14 SSL_CTX *ctx, 15 int (*gen_stateless_cookie_cb) (SSL *ssl, 16 unsigned char *cookie, 17 size_t *cookie_len)); 18 void SSL_CTX_set_stateless_cookie_verify_cb( 19 SSL_CTX *ctx, 20 int (*verify_stateless_cookie_cb) (SSL *ssl, 21 const unsigned char *cookie, 22 size_t cookie_len)); 23 24=head1 DESCRIPTION 25 26SSL_CTX_set_cookie_generate_cb() sets the callback used by L<SSL_stateless(3)> 27to generate the application-controlled portion of the cookie provided to clients 28in the HelloRetryRequest transmitted as a response to a ClientHello with a 29missing or invalid cookie. gen_stateless_cookie_cb() must write at most 30SSL_COOKIE_LENGTH bytes into B<cookie>, and must write the number of bytes 31written to B<cookie_len>. If a cookie cannot be generated, a zero return value 32can be used to abort the handshake. 33 34SSL_CTX_set_cookie_verify_cb() sets the callback used by L<SSL_stateless(3)> to 35determine whether the application-controlled portion of a ClientHello cookie is 36valid. A nonzero return value from app_verify_cookie_cb() communicates that the 37cookie is valid. The integrity of the entire cookie, including the 38application-controlled portion, is automatically verified by HMAC before 39verify_stateless_cookie_cb() is called. 40 41=head1 RETURN VALUES 42 43Neither function returns a value. 44 45=head1 SEE ALSO 46 47L<SSL_stateless(3)> 48 49=head1 COPYRIGHT 50 51Copyright 2018 The OpenSSL Project Authors. All Rights Reserved. 52 53Licensed under the OpenSSL license (the "License"). You may not use 54this file except in compliance with the License. You can obtain a copy 55in the file LICENSE in the source distribution or at 56L<https://www.openssl.org/source/license.html>. 57 58=cut 59