NAME

       gnutls_session_get_data2 - API function

SYNOPSIS

       #include <gnutls/gnutls.h>

       int gnutls_session_get_data2(gnutls_session_t session, gnutls_datum_t * data);

ARGUMENTS

       gnutls_session_t session
                   is a gnutls_session_t type.

       gnutls_datum_t * data
                   is a pointer to a datum that will hold the session.

DESCRIPTION

       Returns  necessary  parameters to support resumption. The client should call this function
       and store  the  returned  session  data.  A  session  can  be  resumed  later  by  calling
       gnutls_session_set_data()  with  the  returned  data.  Note  that  under  TLS  1.3,  it is
       recommended for clients to use session parameters only once, to prevent  passive-observers
       from correlating the different connections.

       The returned  data are allocated and must be released using gnutls_free().

       This  function  will  fail if called prior to handshake completion. In case of false start
       TLS, the handshake completes only after data have  been  successfully  received  from  the
       peer.

       Under TLS1.3 session resumption is possible only after a session ticket is received by the
       client. To ensure that such a ticket has been received use gnutls_session_get_flags()  and
       check  for  flag GNUTLS_SFLAGS_SESSION_TICKET; if this flag is not set, this function will
       wait for a new ticket within an estimated roundtrip, and if not received will return dummy
       data which cannot lead to resumption.

       To    get    notified    when    new    tickets   are   received   by   the   server   use
       gnutls_handshake_set_hook_function()  to  wait   for   GNUTLS_HANDSHAKE_NEW_SESSION_TICKET
       messages.  Each call of gnutls_session_get_data2() after a ticket is received, will return
       session resumption data corresponding to the last received ticket.

       Note  that  this  function  under  TLS1.3   requires   a   callback   to   be   set   with
       gnutls_transport_set_pull_timeout_function()  for  successful  operation.  There was a bug
       before 3.6.10 which could make this function fail if that callback was not set.  On  later
       versions  if  not  set,  the function will return a successful error code, but will return
       dummy data that cannot lead to a resumption.

RETURNS

       On success, GNUTLS_E_SUCCESS (0) is returned, otherwise an error code is returned.

REPORTING BUGS

       Report bugs to <bugs@gnutls.org>.
       Home page: https://www.gnutls.org

COPYRIGHT

       Copyright © 2001-2023 Free Software Foundation, Inc., and others.
       Copying and distribution of this file, with or without modification, are permitted in  any
       medium without royalty provided the copyright notice and this notice are preserved.

SEE ALSO

       The   full   documentation  for  gnutls  is  maintained  as  a  Texinfo  manual.   If  the
       /usr/share/doc/gnutls/ directory does not contain the HTML form visit

       https://www.gnutls.org/manual/