93 lines
3.0 KiB
Plaintext
93 lines
3.0 KiB
Plaintext
=pod
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=head1 NAME
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SSL_CTX_set_session_id_context, SSL_set_session_id_context - set context within which session can be reused (server side only)
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=head1 SYNOPSIS
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#include <openssl/ssl.h>
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int SSL_CTX_set_session_id_context(SSL_CTX *ctx, const unsigned char *sid_ctx,
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unsigned int sid_ctx_len);
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int SSL_set_session_id_context(SSL *ssl, const unsigned char *sid_ctx,
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unsigned int sid_ctx_len);
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=head1 DESCRIPTION
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SSL_CTX_set_session_id_context() sets the context B<sid_ctx> of length
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B<sid_ctx_len> within which a session can be reused for the B<ctx> object.
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SSL_set_session_id_context() sets the context B<sid_ctx> of length
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B<sid_ctx_len> within which a session can be reused for the B<ssl> object.
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=head1 NOTES
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Sessions are generated within a certain context. When exporting/importing
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sessions with B<i2d_SSL_SESSION>/B<d2i_SSL_SESSION> it would be possible,
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to re-import a session generated from another context (e.g. another
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application), which might lead to malfunctions. Therefore, each application
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must set its own session id context B<sid_ctx> which is used to distinguish
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the contexts and is stored in exported sessions. The B<sid_ctx> can be
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any kind of binary data with a given length, it is therefore possible
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to use e.g. the name of the application and/or the hostname and/or service
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name ...
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The session id context becomes part of the session. The session id context
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is set by the SSL/TLS server. The SSL_CTX_set_session_id_context() and
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SSL_set_session_id_context() functions are therefore only useful on the
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server side.
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OpenSSL clients will check the session id context returned by the server
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when reusing a session.
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The maximum length of the B<sid_ctx> is limited to
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B<SSL_MAX_SID_CTX_LENGTH>.
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=head1 WARNINGS
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If the session id context is not set on an SSL/TLS server and client
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certificates are used, stored sessions
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will not be reused but a fatal error will be flagged and the handshake
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will fail.
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If a server returns a different session id context to an OpenSSL client
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when reusing a session, an error will be flagged and the handshake will
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fail. OpenSSL servers will always return the correct session id context,
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as an OpenSSL server checks the session id context itself before reusing
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a session as described above.
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=head1 RETURN VALUES
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SSL_CTX_set_session_id_context() and SSL_set_session_id_context()
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return the following values:
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=over 4
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=item Z<>0
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The length B<sid_ctx_len> of the session id context B<sid_ctx> exceeded
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the maximum allowed length of B<SSL_MAX_SID_CTX_LENGTH>. The error
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is logged to the error stack.
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=item Z<>1
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The operation succeeded.
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=back
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=head1 SEE ALSO
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L<ssl(7)>
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=head1 COPYRIGHT
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Copyright 2001-2020 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the OpenSSL license (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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