NAME         top

       gnutls_handshake_set_post_client_hello_function - API function

SYNOPSIS         top

       #include <gnutls/gnutls.h>

       void gnutls_handshake_set_post_client_hello_function(gnutls_session_t
       session, gnutls_handshake_simple_hook_func func);

ARGUMENTS         top

       gnutls_session_t session
                   is a gnutls_session_t type.

       gnutls_handshake_simple_hook_func func
                   is the function to be called

DESCRIPTION         top

       This function will set a callback to be called after the client hello
       has been received (callback valid in server side only). This allows
       the server to adjust settings based on received extensions.

       Those settings could be ciphersuites, requesting certificate, or
       anything else except for version negotiation (this is done before the
       hello message is parsed).

       This callback must return 0 on success or a gnutls error code to
       terminate the handshake.

       Since GnuTLS 3.3.5 the callback is allowed to return GNUTLS_E_AGAIN
       or GNUTLS_E_INTERRUPTED to put the handshake on hold. In that case
       gnutls_handshake() will return GNUTLS_E_INTERRUPTED and can be
       resumed when needed.

WARNING         top

       You should not use this function to terminate the handshake based on
       client input unless you know what you are doing. Before the handshake
       is finished there is no way to know if there is a man-in-the-middle
       attack being performed.

REPORTING BUGS         top

       Report bugs to <>.
       Home page:

COPYRIGHT         top

       Copyright © 2001-2019 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         top

       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 

COLOPHON         top

       This page is part of the GnuTLS (GnuTLS Transport Layer Security
       Library) project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug report for this manual
       page, send it to  This page was obtained from the
       tarball gnutls-3.6.6.tar.xz fetched from
       ⟨⟩ on 2019-03-06.  If you discover
       any rendering problems in this HTML version of the page, or you
       believe there is a better or more up-to-date source for the page, or
       you have corrections or improvements to the information in this
       COLOPHON (which is not part of the original manual page), send a mail

gnutls                    gnutls_han3d.s6h.a5ke_set_post_client_hello_function(3)