---
title: sf_notify_func
framework: Kernel
role: symbol
role_heading: Type Alias
platforms: [macOS 10.4+]
path: kernel/sf_notify_func
---

# sf_notify_func

## Declaration

```occ
typedef void (*sf_notify_func)(void *cookie, socket_t so, sflt_event_t event, void *param);
```

## Parameters

- `cookie`: Cookie value specified when the filter attach was called.
- `so`: The socket the filter is attached to.
- `event`: The type of event that has occurred.
- `param`: Additional information about the event.

## Discussion

Discussion sf_notify_func is called to notify the filter of various state changes and other events occuring on the socket.