5 SSL_CTX_set_session_ticket_cb,
6 SSL_SESSION_get0_ticket_appdata,
7 SSL_SESSION_set1_ticket_appdata,
8 SSL_CTX_generate_session_ticket_fn,
9 SSL_CTX_decrypt_session_ticket_fn - manage session ticket application data
13 #include <openssl/ssl.h>
15 typedef int (*SSL_CTX_generate_session_ticket_fn)(SSL *s, void *arg);
16 typedef SSL_TICKET_RETURN (*SSL_CTX_decrypt_session_ticket_fn)(SSL *s, SSL_SESSION *ss,
17 const unsigned char *keyname,
19 SSL_TICKET_STATUS status,
21 int SSL_CTX_set_session_ticket_cb(SSL_CTX *ctx,
22 SSL_CTX_generate_session_ticket_fn gen_cb,
23 SSL_CTX_decrypt_session_ticket_fn dec_cb,
25 int SSL_SESSION_set1_ticket_appdata(SSL_SESSION *ss, const void *data, size_t len);
26 int SSL_SESSION_get0_ticket_appdata(SSL_SESSION *ss, void **data, size_t *len);
30 SSL_CTX_set_set_session_ticket_cb() sets the application callbacks B<gen_cb>
31 and B<dec_cb> that are used by a server to set and get application data stored
32 with a session, and placed into a session ticket. Either callback function may
33 be set to NULL. The value of B<arg> is passed to the callbacks.
35 B<gen_cb> is the application defined callback invoked when a session ticket is
36 about to be created. The application can call SSL_SESSION_set1_ticket_appdata()
37 at this time to add application data to the session ticket. The value of B<arg>
38 is the same as that given to SSL_CTX_set_session_ticket_cb(). The B<gen_cb>
39 callback is defined as type B<SSL_CTX_generate_session_ticket_fn>.
41 B<dec_cb> is the application defined callback invoked after session ticket
42 decryption has been attempted and any session ticket application data is
43 available. If ticket decryption was successful then the B<ss> argument contains
44 the session data. The B<keyname> and B<keyname_len> arguments identify the key
45 used to decrypt the session ticket. The B<status> argument is the result of the
46 ticket decryption. See the L<NOTES> section below for further details. The value
47 of B<arg> is the same as that given to SSL_CTX_set_session_ticket_cb(). The
48 B<dec_cb> callback is defined as type B<SSL_CTX_decrypt_session_ticket_fn>.
50 SSL_SESSION_set1_ticket_appdata() sets the application data specified by
51 B<data> and B<len> into B<ss> which is then placed into any generated session
52 tickets. It can be called at any time before a session ticket is created to
53 update the data placed into the session ticket. However, given that sessions
54 and tickets are created by the handshake, the B<gen_cb> is provided to notify
55 the application that a session ticket is about to be generated.
57 SSL_SESSION_get0_ticket_appdata() assigns B<data> to the session ticket
58 application data and assigns B<len> to the length of the session ticket
59 application data from B<ss>. The application data can be set via
60 SSL_SESSION_set1_ticket_appdata() or by a session ticket. NULL will be assigned
61 to B<data> and 0 will be assigned to B<len> if there is no session ticket
62 application data. SSL_SESSION_get0_ticket_appdata() can be called any time
63 after a session has been created. The B<dec_cb> is provided to notify the
64 application that a session ticket has just been decrypted.
68 When the B<dec_cb> callback is invoked, the SSL_SESSION B<ss> has not yet been
69 assigned to the SSL B<s>. The B<status> indicates the result of the ticket
70 decryption. The callback must check the B<status> value before performing any
71 action, as it is called even if ticket decryption fails.
73 The B<keyname> and B<keyname_len> arguments to B<dec_cb> may be used to identify
74 the key that was used to encrypt the session ticket.
76 The B<status> argument can be any of these values:
80 =item SSL_TICKET_EMPTY
82 Empty ticket present. No ticket data will be used and a new ticket should be
83 sent to the client. This only occurs in TLSv1.2 or below. In TLSv1.3 it is not
84 valid for a client to send an empty ticket.
86 =item SSL_TICKET_NO_DECRYPT
88 The ticket couldn't be decrypted. No ticket data will be used and a new ticket
89 should be sent to the client.
91 =item SSL_TICKET_SUCCESS
93 A ticket was successfully decrypted, any session ticket application data should
94 be available. A new ticket should not be sent to the client.
96 =item SSL_TICKET_SUCCESS_RENEW
98 Same as B<SSL_TICKET_SUCCESS>, but a new ticket should be sent to the client.
102 The return value can be any of these values:
106 =item SSL_TICKET_RETURN_ABORT
108 The handshake should be aborted, either because of an error or because of some
109 policy. Note that in TLSv1.3 a client may send more than one ticket in a single
110 handshake. Therefore just because one ticket is unacceptable it does not mean
111 that all of them are. For this reason this option should be used with caution.
113 =item SSL_TICKET_RETURN_IGNORE
115 Do not use a ticket (if one was available). Do not send a renewed ticket to the
118 =item SSL_TICKET_RETURN_IGNORE_RENEW
120 Do not use a ticket (if one was available). Send a renewed ticket to the client.
122 If the callback does not wish to change the default ticket behaviour then it
123 should return this value if B<status> is B<SSL_TICKET_EMPTY> or
124 B<SSL_TICKET_NO_DECRYPT>.
126 =item SSL_TICKET_RETURN_USE
128 Use the ticket. Do not send a renewed ticket to the client. It is an error for
129 the callback to return this value if B<status> has a value other than
130 B<SSL_TICKET_SUCCESS> or B<SSL_TICKET_SUCCESS_RENEW>.
132 If the callback does not wish to change the default ticket behaviour then it
133 should return this value if B<status> is B<SSL_TICKET_SUCCESS>.
135 =item SSL_TICKET_RETURN_USE_RENEW
137 Use the ticket. Send a renewed ticket to the client. It is an error for the
138 callback to return this value if B<status> has a value other than
139 B<SSL_TICKET_SUCCESS> or B<SSL_TICKET_SUCCESS_RENEW>.
141 If the callback does not wish to change the default ticket behaviour then it
142 should return this value if B<status> is B<SSL_TICKET_SUCCESS_RENEW>.
146 If B<status> has the value B<SSL_TICKET_EMPTY> or B<SSL_TICKET_NO_DECRYPT> then
147 no session data will be available and the callback must not use the B<ss>
148 argument. If B<status> has the value B<SSL_TICKET_SUCCESS> or
149 B<SSL_TICKET_SUCCESS_RENEW> then the application can call
150 SSL_SESSION_get0_ticket_appdata() using the session provided in the B<ss>
151 argument to retrieve the application data.
153 When the B<gen_cb> callback is invoked, the SSL_get_session() function can be
154 used to retrieve the SSL_SESSION for SSL_SESSION_set1_ticket_appdata().
156 By default, in TLSv1.2 and below, a new session ticket is not issued on a
157 successful resumption and therefore B<gen_cb> will not be called. In TLSv1.3 the
158 default behaviour is to always issue a new ticket on resumption. In both cases
159 this behaviour can be changed if a ticket key callback is in use (see
160 L<SSL_CTX_set_tlsext_ticket_key_cb(3)>).
164 The SSL_CTX_set_session_ticket_cb(), SSL_SESSION_set1_ticket_appdata() and
165 SSL_SESSION_get0_ticket_appdata() functions return 1 on success and 0 on
168 The B<gen_cb> callback must return 1 to continue the connection. A return of 0
169 will terminate the connection with an INTERNAL_ERROR alert.
171 The B<dec_cb> callback must return a value as described in L<NOTES> above.
176 L<SSL_get_session(3)>
180 The SSL_CTX_set_session_ticket_cb(), SSSL_SESSION_set1_ticket_appdata()
181 and SSL_SESSION_get_ticket_appdata() functions were added in OpenSSL 1.1.1.
185 Copyright 2017-2018 The OpenSSL Project Authors. All Rights Reserved.
187 Licensed under the OpenSSL license (the "License"). You may not use
188 this file except in compliance with the License. You can obtain a copy
189 in the file LICENSE in the source distribution or at
190 L<https://www.openssl.org/source/license.html>.