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+=pod
+
+=head1 NAME
+
+SSL_CTX_set_session_cache_mode, SSL_CTX_get_session_cache_mode - enable/disable session caching
+
+=head1 SYNOPSIS
+
+ #include <openssl/ssl.h>
+
+ long SSL_CTX_set_session_cache_mode(SSL_CTX ctx, long mode);
+ long SSL_CTX_get_session_cache_mode(SSL_CTX ctx);
+
+=head1 DESCRIPTION
+
+SSL_CTX_set_session_cache_mode() enables/disables session caching
+by setting the operational mode for B<ctx> to <mode>.
+
+SSL_CTX_get_session_cache_mode() returns the currently used cache mode.
+
+=head1 NOTES
+
+The OpenSSL library can store/retrieve SSL/TLS sessions for later reuse.
+The sessions can be held in memory for each B<ctx>, if more than one
+SSL_CTX object is being maintained, the sessions are unique for each SSL_CTX
+object.
+
+In order to reuse a session, a client must send the session's id to the
+server. It can only send exactly one id. The server then decides whether it
+agrees in reusing the session or starts the handshake for a new session.
+
+A server will lookup up the session in its internal session storage. If
+the session is not found in internal storage or internal storage is
+deactivated, the server will try the external storage if available.
+
+Since a client may try to reuse a session intended for use in a different
+context, the session id context must be set by the server (see
+L<SSL_CTX_set_session_id_context(3)|SSL_CTX_set_session_id_context(3)>).
+
+The following session cache modes and modifiers are available:
+
+=over 4
+
+=item SSL_SESS_CACHE_OFF
+
+No session caching for client or server takes place.
+
+=item SSL_SESS_CACHE_CLIENT
+
+Client sessions are added to the session cache. As there is no reliable way
+for the OpenSSL library to know whether a session should be reused or which
+session to choose (due to the abstract BIO layer the SSL engine does not
+have details about the connection), the application must select the session
+to be reused by using the L<SSL_set_session(3)|SSL_set_session(3)>
+function. This option is not activated by default.
+
+=item SSL_SESS_CACHE_SERVER
+
+Server sessions are added to the session cache. When a client proposes a
+session to be reused, the session is looked up in the internal session cache.
+If the session is found, the server will try to reuse the session.
+This is the default.
+
+=item SSL_SESS_CACHE_BOTH
+
+Enable both SSL_SESS_CACHE_CLIENT and SSL_SESS_CACHE_SERVER at the same time.
+
+=item SSL_SESS_CACHE_NO_AUTO_CLEAR
+
+Normally the session cache is checked for expired sessions every
+255 connections using the
+L<SSL_CTX_flush_sessions(3)|SSL_CTX_flush_sessions(3)> function. Since
+this may lead to a delay which cannot be controlled, the automatic
+flushing may be disabled and
+L<SSL_CTX_flush_sessions(3)|SSL_CTX_flush_sessions(3)> can be called
+explicitly by the application.
+
+=item SSL_SESS_CACHE_NO_INTERNAL_LOOKUP
+
+By setting this flag sessions are cached in the internal storage but
+they are not looked up automatically. If an external session cache
+is enabled, sessions are looked up in the external cache. As automatic
+lookup only applies for SSL/TLS servers, the flag has no effect on
+clients.
+
+=back
+
+The default mode is SSL_SESS_CACHE_SERVER.
+
+=head1 RETURN VALUES
+
+SSL_CTX_set_session_cache_mode() returns the previously set cache mode.
+
+SSL_CTX_get_session_cache_mode() returns the currently set cache mode.
+
+
+=head1 SEE ALSO
+
+L<ssl(3)|ssl(3)>, L<SSL_set_session(3)|SSL_set_session(3)>,
+L<SSL_CTX_sess_set_cache_size(3)|SSL_CTX_sess_set_cache_size(3)>,
+L<SSL_CTX_sess_set_get_cb(3)|SSL_CTX_sess_set_get_cb(3)>,
+L<SSL_CTX_set_session_id_context(3)|SSL_CTX_set_session_id_context(3)>,
+L<SSL_CTX_set_timeout.pod(3)|SSL_CTX_set_timeout.pod(3)>,
+L<SSL_CTX_flush_sessions(3)|SSL_CTX_flush_sessions(3)>
+
+=cut
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