comparison.c

/* Basic rust callback function */
pub fn func(data: &[u8], src_addr: &SocketAddr, obj: &Rc<RefCell<Any>>) {
    let mut temp = obj.borrow_mut();

    let mut dht = match temp.downcast_mut::<DHT>() {
        Some(dht) => dht,
        None => return,
    };
  
  ...
}

/* Equivalent in C */
void func(const char *data, const IP_Port *src_addr, void *obj)
{
    DHT *dht = obj; 
  
    if (!dht) {
        return; 
    }
 
    ...
}