1: =pod
    2: 
    3: =head1 NAME
    4: 
    5: SSL_get_session - retrieve TLS/SSL session data
    6: 
    7: =head1 SYNOPSIS
    8: 
    9:  #include <openssl/ssl.h>
   10: 
   11:  SSL_SESSION *SSL_get_session(const SSL *ssl);
   12:  SSL_SESSION *SSL_get0_session(const SSL *ssl);
   13:  SSL_SESSION *SSL_get1_session(SSL *ssl);
   14: 
   15: =head1 DESCRIPTION
   16: 
   17: SSL_get_session() returns a pointer to the B<SSL_SESSION> actually used in
   18: B<ssl>. The reference count of the B<SSL_SESSION> is not incremented, so
   19: that the pointer can become invalid by other operations.
   20: 
   21: SSL_get0_session() is the same as SSL_get_session().
   22: 
   23: SSL_get1_session() is the same as SSL_get_session(), but the reference
   24: count of the B<SSL_SESSION> is incremented by one.
   25: 
   26: =head1 NOTES
   27: 
   28: The ssl session contains all information required to re-establish the
   29: connection without a new handshake.
   30: 
   31: SSL_get0_session() returns a pointer to the actual session. As the
   32: reference counter is not incremented, the pointer is only valid while
   33: the connection is in use. If L<SSL_clear(3)|SSL_clear(3)> or
   34: L<SSL_free(3)|SSL_free(3)> is called, the session may be removed completely
   35: (if considered bad), and the pointer obtained will become invalid. Even
   36: if the session is valid, it can be removed at any time due to timeout
   37: during L<SSL_CTX_flush_sessions(3)|SSL_CTX_flush_sessions(3)>.
   38: 
   39: If the data is to be kept, SSL_get1_session() will increment the reference
   40: count, so that the session will not be implicitly removed by other operations
   41: but stays in memory. In order to remove the session
   42: L<SSL_SESSION_free(3)|SSL_SESSION_free(3)> must be explicitly called once
   43: to decrement the reference count again.
   44: 
   45: SSL_SESSION objects keep internal link information about the session cache
   46: list, when being inserted into one SSL_CTX object's session cache.
   47: One SSL_SESSION object, regardless of its reference count, must therefore
   48: only be used with one SSL_CTX object (and the SSL objects created
   49: from this SSL_CTX object).
   50: 
   51: =head1 RETURN VALUES
   52: 
   53: The following return values can occur:
   54: 
   55: =over 4
   56: 
   57: =item NULL
   58: 
   59: There is no session available in B<ssl>.
   60: 
   61: =item Pointer to an SSL
   62: 
   63: The return value points to the data of an SSL session.
   64: 
   65: =back
   66: 
   67: =head1 SEE ALSO
   68: 
   69: L<ssl(3)|ssl(3)>, L<SSL_free(3)|SSL_free(3)>,
   70: L<SSL_clear(3)|SSL_clear(3)>,
   71: L<SSL_SESSION_free(3)|SSL_SESSION_free(3)>
   72: 
   73: =cut