pub type SSL_custom_ext_add_cb_ex = Option<unsafe extern "C" fn(ssl: *mut SSL, ext_type: c_uint, context: c_uint, out: *mut *const c_uchar, outlen: *mut size_t, x: *mut X509, chainidx: size_t, al: *mut c_int, add_arg: *mut c_void) -> c_int>;