Technical Reference: Kernel and Subsystems, Volume 1

add_input_type Kernel Service

Purpose

Adds a new input type to the Network Input table.

Syntax

#include <sys/types.h>
#include <sys/errno.h>
#include <net/if.h>
#include <net/netisr.h>
int add_input_type (type, service_level, isr, ifq, af)
u_short type;
u_short service_level;
int (* isr) ();
struct ifqueue * ifq;
u_short af;

Parameters

type	Specifies which type of protocol a packet contains. A value of x'FFFF' indicates that this input type is a wildcard type and matches all input packets.
service_level	Determines the processing level at which the protocol input handler is called. If the service_level parameter is set to NET_OFF_LEVEL, the input handler specified by the isr parameter is called directly. Setting the service_level parameter to NET_KPROC schedules a network dispatcher. This dispatcher calls the subroutine identified by the isr parameter.
isr	Identifies the routine that serves as the input handler for an input packet type.
ifq	Specifies an input queue for holding input buffers. If this parameter has a non-null value, an input buffer (mbuf) is enqueued. The ifq parameter must be specified if the processing level specified by the service_level parameter is NET_KPROC. Specifying null for this parameter generates a call to the input handler specified by the isr parameter, as in the following:
af	Specifies the address family of the calling protocol. The af parameter must be specified if the ifq parameter is not a null character. (*isr)(CommonPortion,Buffer); In this example, `CommonPortion` points to the network common portion (the arpcom structure) of a network interface and `Buffer` is a pointer to a buffer (mbuf) containing an input packet.

Description

To enable the reception of packets, an address family calls the add_input_type kernel service to register a packet type in the Network Input table. Multiple packet types require multiple calls toAIX 5L Version 5.2 Kernel Extensions and Device Support Programming Concepts the add_input_type kernel service.

Execution Environment

The add_input_type kernel service can be called from either the process or interrupt environment.

Return Values

0	Indicates that the type was successfully added.
EEXIST	Indicates that the type was previously added to the Network Input table.
ENOSPC	Indicates that no free slots are left in the table.
EINVAL	Indicates that an error occurred in the input parameters.

Examples

To register an Internet packet type (TYPE_IP), invoke the add_input_type service as follows:
```
add_input_type(TYPE_IP,  NET_KPROC,  ipintr,  &ipintrq,  AF_INET); 
```
This packet is processed through the network kproc. The input handler is ipintr. The input queue is ipintrq.
To specify the input handler for ARP packets, invoke the add_input_type service as follows:
```
add_input_type(TYPE_ARP,  NET_OFF_LEVEL,  arpinput,  NULL,  NULL); 
```
Packets are not queued and the arpinput subroutine is called directly.

Related Information

The del_input_type kernel service, find_input_type kernel service.

Network Kernel Services in AIX 5L Version 5.2 Kernel Extensions and Device Support Programming Concepts.