gnutls_handshake_set_post_client_hello_function — API function


#include <gnutls/gnutls.h>
void gnutls_handshake_set_post_client_hello_function( gnutls_session_t session,
  gnutls_handshake_post_client_hello_func func);


gnutls_session_t session

is a gnutls_session_t structure.

gnutls_handshake_post_client_hello_func 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.


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.


Report bugs to <>.

General guidelines for reporting bugs:

GnuTLS home page:


The full documentation for gnutls is maintained as a Texinfo manual. If the info and gnutls programs are properly installed at your site, the command

info gnutls

should give you access to the complete manual. As an alternative you may obtain the manual from:


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