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

# sf_connect_in_func

## Declaration

```occ
typedef errno_t (*sf_connect_in_func)(void *cookie, socket_t so, const struct sockaddr *from);
```

## Parameters

- `cookie`: Cookie value specified when the filter attach was called.
- `so`: The socket the filter is attached to.
- `from`: The address the incoming connection is from.

## Return Value

Return Value Return: 0 - The caller will continue with normal processing of the connection. Anything Else - The caller will rejecting the incoming connection.

## Discussion

Discussion sf_connect_in_func is called to filter inbound connections. A protocol will call this before accepting an incoming connection and placing it on the queue of completed connections. Warning: This filter is on the data path. Do not spend excesive time. Do not wait for data on another socket.