pcap_datalink Subroutine

Purpose

Obtains the link layer type (data link type) for the packet capture device.

Library

pcap Library (libpcap.a)

Syntax

#include <pcap.h> int pcap_datalink(pcap_t * p);

Description

The pcap_datalink subroutine returns the link layer type of the packet capture device, for example, IFT_ETHER. This is useful in determining the size of the datalink header at the beginning of each packet that is read.

Parameters

Item	Description
p	Points to the packet capture descriptor as returned by the pcap_open_live or the pcap_open_offline subroutine.

Return Values

The pcap_datalink subroutine returns the values of standard libpcap link layer type from the <net/bpf.h> header file.

Note: Only call this subroutine after successful calls to either the pcap_open_live or the pcap_open_offline subroutine. Never call the pcap_datalink subroutine after a call to pcap_close as unpredictable results will occur.