pub type ssl_export_keys_ext_t = Option<unsafe extern "C" fn(p_expkey: *mut c_void, ms: *const c_uchar, kb: *const c_uchar, maclen: size_t, keylen: size_t, ivlen: size_t, client_random: *const c_uchar, server_random: *const c_uchar, tls_prf_type: tls_prf_types) -> c_int>;