@deftypefun {void} {gnutls_handshake_set_post_client_hello_function} (gnutls_session_t @var{session}, gnutls_handshake_simple_hook_func @var{func})

@var{session}: is a @code{gnutls_session_t}  type.

@var{func}: is the function to be called

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 @code{GNUTLS_E_AGAIN}  or @code{GNUTLS_E_INTERRUPTED}  to

put the handshake on hold. In that case @code{gnutls_handshake()} 

will return @code{GNUTLS_E_INTERRUPTED}  and can be resumed when needed.

@strong{Warning:} 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.

@end deftypefun