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SSL_CTX_SET_STATELESS_COOKIE_GENERASSL_CTX_SET_STATELESS_COOKIE_GENERATE_CB(3)
NAME
       SSL_CTX_set_stateless_cookie_generate_cb,
       SSL_CTX_set_stateless_cookie_verify_cb, SSL_CTX_set_cookie_generate_cb,
       SSL_CTX_set_cookie_verify_cb - Callback functions for stateless TLS1.3
       cookies
SYNOPSIS
        #include <openssl/ssl.h>
        void SSL_CTX_set_stateless_cookie_generate_cb(
            SSL_CTX *ctx,
            int (*gen_stateless_cookie_cb) (SSL *ssl,
                                            unsigned char *cookie,
                                            size_t *cookie_len));
        void SSL_CTX_set_stateless_cookie_verify_cb(
            SSL_CTX *ctx,
            int (*verify_stateless_cookie_cb) (SSL *ssl,
                                               const unsigned char *cookie,
                                               size_t cookie_len));
        void SSL_CTX_set_cookie_generate_cb(SSL_CTX *ctx,
                                            int (*app_gen_cookie_cb) (SSL *ssl,
                                                                      unsigned char
                                                                      *cookie,
                                                                      unsigned int
                                                                      *cookie_len));
        void SSL_CTX_set_cookie_verify_cb(SSL_CTX *ctx,
                                          int (*app_verify_cookie_cb) (SSL *ssl,
                                                                       const unsigned
                                                                       char *cookie,
                                                                       unsigned int
                                                                       cookie_len));
DESCRIPTION
       SSL_CTX_set_stateless_cookie_generate_cb() sets the callback used by
       SSL_stateless(3) to generate the application-controlled portion of the
       cookie provided to clients in the HelloRetryRequest transmitted as a
       response to a ClientHello with a missing or invalid cookie.
       gen_stateless_cookie_cb() must write at most SSL_COOKIE_LENGTH bytes
       into cookie, and must write the number of bytes written to cookie_len.
       If a cookie cannot be generated, a zero return value can be used to
       abort the handshake.
       SSL_CTX_set_stateless_cookie_verify_cb() sets the callback used by
       SSL_stateless(3) to determine whether the application-controlled
       portion of a ClientHello cookie is valid. The cookie data is pointed to
       by cookie and is of length cookie_len. A nonzero return value from
       verify_stateless_cookie_cb() communicates that the cookie is valid. The
       integrity of the entire cookie, including the application-controlled
       portion, is automatically verified by HMAC before
       verify_stateless_cookie_cb() is called.
       SSL_CTX_set_cookie_generate_cb() sets the callback used by
       DTLSv1_listen(3) to generate the cookie provided to clients in the
       HelloVerifyRequest transmitted as a response to a ClientHello with a
       missing or invalid cookie.  app_gen_cookie_cb()  must write at most
       DTLS1_COOKIE_LENGTH bytes into cookie, and must write the number of
       bytes written to cookie_len. If a cookie cannot be generated, a zero
       return value can be used to abort the handshake.
       SSL_CTX_set_cookie_verify_cb() sets the callback used by
       DTLSv1_listen(3) to determine whether the cookie in a ClientHello is
       valid. The cookie data is pointed to by cookie and is of length
       cookie_len. A nonzero return value from app_verify_cookie_cb()
       communicates that the cookie is valid. The integrity of the cookie is
       not verified by OpenSSL. This is an application responsibility.
RETURN VALUES
       Neither function returns a value.
SEE ALSO
       SSL_stateless(3), DTLSv1_listen(3)
HISTORY
       SSL_CTX_set_stateless_cookie_generate_cb() and
       SSL_CTX_set_stateless_cookie_verify_cb() were added in OpenSSL 1.1.1.
COPYRIGHT
       Copyright 2018 The OpenSSL Project Authors. All Rights Reserved.
       Licensed under the OpenSSL license (the "License").  You may not use
       this file except in compliance with the License.  You can obtain a copy
       in the file LICENSE in the source distribution or at
       <https://www.openssl.org/source/license.html>;.
1.1.1k                            2SSL_CTX_SET_STATELESS_COOKIE_GENERATE_CB(3)