SSL_CTX_set_session_cache_mode(3SSL_CTX_set_session_cache_mode(3)

NAME    [Toc]    [Back]

       SSL_CTX_set_session_cache_mode,           SSL_CTX_get_session_cache_mode
 - Enable or disable session caching

SYNOPSIS    [Toc]    [Back]

       #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 );

DESCRIPTION    [Toc]    [Back]

       The SSL_CTX_set_session_cache_mode() function  enables  or
       disables  session  caching by setting the operational mode
       for ctx to <mode>.

       The SSL_CTX_get_session_cache_mode() function returns  the
       currently used cache mode.

NOTES    [Toc]    [Back]

       The  OpenSSL  library  can store/retrieve SSL/TLS sessions
       for later reuse.  The sessions can be held in  memory  for
       each  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 one id.  The
       server then decides whether to reuse the session or  start
       the handshake for a new session.

       A  server  will  check the session in its internal session
       storage. If the session is not found in  internal  storage
       or  internal  storage, it 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 SSL_CTX_set_session_id_context(3)).

       The following session cache modes and modifiers are available:
 No session caching for client or server takes place.
       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 SSL_set_session()
       function. This option is not activated by default.  Server
       sessions  are  added  to  the session cache. When a client
       proposes a session 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.
       Enable        both        SSL_SESS_CACHE_CLIENT        and
       SSL_SESS_CACHE_SERVER at the same time.  Normally the session
  cache is checked for expired sessions every 255 connections
  using  the  SSL_CTX_flush_sessions()   function.
       Since  this  might  lead  to  a delay which cannot be controlled,
 the automatic flushing can be  disabled  and  the
       SSL_CTX_flush_sessions()  can  be called explicitly by the
       application.  By setting this option, 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  option  has
       no effect on clients.

       The default mode is SSL_SESS_CACHE_SERVER.

RETURN VALUES    [Toc]    [Back]

       The  SSL_CTX_set_session_cache_mode() function returns the
       previously set cache mode.

       The SSL_CTX_get_session_cache_mode() function returns  the
       currently set cache mode.

SEE ALSO    [Toc]    [Back]

       Functions:     ssl(3),     SSL_set_session(3),    SSL_session_reused(3)                     SSL_CTX_sess_number(3),
       SSL_CTX_sess_set_cache_size(3),
       SSL_CTX_sess_set_get_cb(3),    SSL_CTX_set_session_id_context(3), SSL_CTX_set_timeout(3), SSL_CTX_flush_sessions(3)



                                SSL_CTX_set_session_cache_mode(3)