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7b2bde500d
Reviewed-by: Shane Lontis <shane.lontis@oracle.com> Reviewed-by: Tomas Mraz <tomas@openssl.org> (Merged from https://github.com/openssl/openssl/pull/16874)
97 lines
4.0 KiB
Plaintext
97 lines
4.0 KiB
Plaintext
=pod
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=head1 NAME
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SSL_set_num_tickets,
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SSL_get_num_tickets,
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SSL_CTX_set_num_tickets,
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SSL_CTX_get_num_tickets,
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SSL_new_session_ticket
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- control the number of TLSv1.3 session tickets that are issued
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=head1 SYNOPSIS
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#include <openssl/ssl.h>
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int SSL_set_num_tickets(SSL *s, size_t num_tickets);
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size_t SSL_get_num_tickets(const SSL *s);
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int SSL_CTX_set_num_tickets(SSL_CTX *ctx, size_t num_tickets);
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size_t SSL_CTX_get_num_tickets(const SSL_CTX *ctx);
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int SSL_new_session_ticket(SSL *s);
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=head1 DESCRIPTION
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SSL_CTX_set_num_tickets() and SSL_set_num_tickets() can be called for a server
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application and set the number of TLSv1.3 session tickets that will be sent to
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the client after a full handshake. Set the desired value (which could be 0) in
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the B<num_tickets> argument. Typically these functions should be called before
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the start of the handshake.
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The default number of tickets is 2. Following a resumption the number of tickets
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issued will never be more than 1 regardless of the value set via
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SSL_set_num_tickets() or SSL_CTX_set_num_tickets(). If B<num_tickets> is set to
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0 then no tickets will be issued for either a normal connection or a resumption.
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Tickets are also issued on receipt of a post-handshake certificate from the
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client following a request by the server using
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L<SSL_verify_client_post_handshake(3)>. These new tickets will be associated
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with the updated client identity (i.e. including their certificate and
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verification status). The number of tickets issued will normally be the same as
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was used for the initial handshake. If the initial handshake was a full
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handshake then SSL_set_num_tickets() can be called again prior to calling
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SSL_verify_client_post_handshake() to update the number of tickets that will be
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sent.
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To issue tickets after other events (such as application-layer changes),
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SSL_new_session_ticket() is used by a server application to request that a new
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ticket be sent when it is safe to do so. New tickets are only allowed to be
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sent in this manner after the initial handshake has completed, and only for
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TLS 1.3 connections. By default, the ticket generation and transmission are
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delayed until the server is starting a new write operation, so that it is
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bundled with other application data being written and properly aligned to a
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record boundary. If the connection was at a record boundary when
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SSL_new_session_ticket() was called, the ticket can be sent immediately
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(without waiting for the next application write) by calling
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SSL_do_handshake(). SSL_new_session_ticket() can be called more than once to
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request additional tickets be sent; all such requests are queued and written
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together when it is safe to do so and triggered by SSL_write() or
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SSL_do_handshake(). Note that a successful return from
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SSL_new_session_ticket() indicates only that the request to send a ticket was
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processed, not that the ticket itself was sent. To be notified when the
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ticket itself is sent, a new-session callback can be registered with
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L<SSL_CTX_sess_set_new_cb(3)> that will be invoked as the ticket or tickets
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are generated.
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SSL_CTX_get_num_tickets() and SSL_get_num_tickets() return the number of
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tickets set by a previous call to SSL_CTX_set_num_tickets() or
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SSL_set_num_tickets(), or 2 if no such call has been made.
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=head1 RETURN VALUES
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SSL_CTX_set_num_tickets(), SSL_set_num_tickets(), and
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SSL_new_session_ticket() return 1 on success or 0 on failure.
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SSL_CTX_get_num_tickets() and SSL_get_num_tickets() return the number of tickets
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that have been previously set.
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=head1 SEE ALSO
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L<ssl(7)>
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=head1 HISTORY
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SSL_new_session_ticket() was added in OpenSSL 3.0.0.
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SSL_set_num_tickets(), SSL_get_num_tickets(), SSL_CTX_set_num_tickets(), and
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SSL_CTX_get_num_tickets() were added in OpenSSL 1.1.1.
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=head1 COPYRIGHT
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Copyright 2018-2021 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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