freeDiameter - fd_sess_handler_create

Question

I just had one question about "fd_sess_handler_create" function in freeDiameter library.

Well, in test_app extension, there is a ta_cli_init function to initialize the client procedure, this block was compiled fine when the code was in C :

int ta_cli_init(void)
{
  CHECK_FCT( fd_sess_handler_create(&ta_cli_reg, (void*)free, NULL, NULL) );
  CHECK_FCT( fd_event_trig_regcb(ta_conf->signal, "test_app.cli", ta_cli_test_message ) );
  return 0;
}

However, as soon as i changed the code to C++ , the compiler started to nagging about "cleanup" parameter (second param) that I had to change the code to make the it compiled:

void sess_handler_free(struct sess_state * state, os0_t sid, void * opaque)
{
}

int ta_cli_init(void)
{
  CHECK_FCT( fd_sess_handler_create(&ta_cli_reg, &sess_handler_free, NULL, NULL) );
  CHECK_FCT( fd_event_trig_regcb(ta_conf->signal, "ocs_app.cli", ta_cli_test_message ) );

  return 0;
}

The code is now can be compiled, but because i wasnt sure about cleanup context, as you see i left it empty.

Could you plz explain to me what exactly should be cleaned up in my custom sess_handler_free function body ?

Answer 1

The sess_handler_free needs to free off struct sess_state plus any additional data structures your code has appended to it.

If you don't have any additional data structures, you should just use be able to make sess_handler_free call free(state). (Passing the free function directly is another way of doing this.)

If you do have additional data structures, you need to find them from the struct sess_state and free them off using delete if they were created using new or free if they were created using malloc.

See diameap_cli_sess_cleanup as an example implementation - notice that it checks for methodData, user.password and user.userid fields and frees them off if present, before freeing the struct sess_state itself - this extension allocated these fields, so it is responsible for freeing them.