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423b1a840c
sessions in the external session cache might be removed. Submitted by: "Nadav Har'El" <nyh@math.technion.ac.il> PR: 547
88 lines
3.9 KiB
Plaintext
88 lines
3.9 KiB
Plaintext
=pod
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=head1 NAME
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SSL_CTX_sess_set_new_cb, SSL_CTX_sess_set_remove_cb, SSL_CTX_sess_set_get_cb, SSL_CTX_sess_get_new_cb, SSL_CTX_sess_get_remove_cb, SSL_CTX_sess_get_get_cb - provide callback functions for server side external session caching
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=head1 SYNOPSIS
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#include <openssl/ssl.h>
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void SSL_CTX_sess_set_new_cb(SSL_CTX *ctx,
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int (*new_session_cb)(SSL *, SSL_SESSION *));
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void SSL_CTX_sess_set_remove_cb(SSL_CTX *ctx,
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void (*remove_session_cb)(SSL_CTX *ctx, SSL_SESSION *));
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void SSL_CTX_sess_set_get_cb(SSL_CTX *ctx,
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SSL_SESSION (*get_session_cb)(SSL *, unsigned char *, int, int *));
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int (*SSL_CTX_sess_get_new_cb(SSL_CTX *ctx))(struct ssl_st *ssl, SSL_SESSION *sess);
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void (*SSL_CTX_sess_get_remove_cb(SSL_CTX *ctx))(struct ssl_ctx_st *ctx, SSL_SESSION *sess);
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SSL_SESSION *(*SSL_CTX_sess_get_get_cb(SSL_CTX *ctx))(struct ssl_st *ssl, unsigned char *data, int len, int *copy);
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int (*new_session_cb)(struct ssl_st *ssl, SSL_SESSION *sess);
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void (*remove_session_cb)(struct ssl_ctx_st *ctx, SSL_SESSION *sess);
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SSL_SESSION *(*get_session_cb)(struct ssl_st *ssl, unsigned char *data,
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int len, int *copy);
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=head1 DESCRIPTION
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SSL_CTX_sess_set_new_cb() sets the callback function, which is automatically
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called whenever a new session was negotiated.
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SSL_CTX_sess_set_remove_cb() sets the callback function, which is
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automatically called whenever a session is removed by the SSL engine,
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because it is considered faulty or the session has become obsolete because
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of exceeding the timeout value.
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SSL_CTX_sess_set_get_cb() sets the callback function which is called,
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whenever a SSL/TLS client proposed to resume a session but the session
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could not be found in the internal session cache (see
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L<SSL_CTX_set_session_cache_mode(3)|SSL_CTX_set_session_cache_mode(3)>).
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(SSL/TLS server only.)
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SSL_CTX_sess_get_new_cb(), SSL_CTX_sess_get_remove_cb(), and
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SSL_CTX_sess_get_get_cb() allow to retrieve the function pointers of the
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provided callback functions. If a callback function has not been set,
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the NULL pointer is returned.
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=head1 NOTES
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In order to allow external session caching, synchronization with the internal
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session cache is realized via callback functions. Inside these callback
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functions, session can be saved to disk or put into a database using the
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L<d2i_SSL_SESSION(3)|d2i_SSL_SESSION(3)> interface.
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The new_session_cb() is called, whenever a new session has been negotiated
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and session caching is enabled (see
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L<SSL_CTX_set_session_cache_mode(3)|SSL_CTX_set_session_cache_mode(3)>).
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The new_session_cb() is passed the B<ssl> connection and the ssl session
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B<sess>. If the callback returns B<0>, the session will be immediately
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removed again.
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The remove_session_cb() is called, whenever the SSL engine removes a session
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from the internal cache. This happens when the session is removed because
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it is expired or when a connection was not shutdown cleanly. It also happens
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for all sessions in the internal session cache when
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L<SSL_CTX_free(3)|SSL_CTX_free(3)> is called. The remove_session_cb() is passed
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the B<ctx> and the ssl session B<sess>. It does not provide any feedback.
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The get_session_cb() is only called on SSL/TLS servers with the session id
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proposed by the client. The get_session_cb() is always called, also when
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session caching was disabled. The get_session_cb() is passed the
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B<ssl> connection, the session id of length B<length> at the memory location
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B<data>. With the parameter B<copy> the callback can require the
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SSL engine to increment the reference count of the SSL_SESSION object,
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Normally the reference count is not incremented and therefore the
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session must not be explicitly freed with
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L<SSL_SESSION_free(3)|SSL_SESSION_free(3)>.
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=head1 SEE ALSO
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L<ssl(3)|ssl(3)>, L<d2i_SSL_SESSION(3)|d2i_SSL_SESSION(3)>,
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L<SSL_CTX_set_session_cache_mode(3)|SSL_CTX_set_session_cache_mode(3)>,
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L<SSL_CTX_flush_sessions(3)|SSL_CTX_flush_sessions(3)>,
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L<SSL_SESSION_free(3)|SSL_SESSION_free(3)>,
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L<SSL_CTX_free(3)|SSL_CTX_free(3)>
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=cut
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