@(#) $Header: /tcpdump/master/libpcap/pcap_next_ex.3pcap,v 1.1.2.3 2008-04-06 03:21:56 guy Exp $

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pcap_next_ex, pcap_next - read the next packet from a pcap_t

#include <pcap/pcap.h>

int pcap_next_ex(pcap_t *p, struct pcap_pkthdr **pkt_header,
const u_char **pkt_data);
const u_char *pcap_next(pcap_t *p, struct pcap_pkthdr *h);

pcap_next_ex() reads the next packet and returns a success/failure indication. If the packet was read without problems, the pointer pointed to by the pkt_header argument is set to point to the pcap_pkthdr struct for the packet, and the pointer pointed to by the pkt_data argument is set to point to the data in the packet.

pcap_next() reads the next packet (by calling pcap_dispatch() with a cnt of 1) and returns a u_char pointer to the data in that packet. The pcap_pkthdr structure pointed to by h is filled in with the appropriate values for the packet.

pcap_next_ex() returns 1 if the packet was read without problems, 0 if packets are being read from a live capture, and the timeout expired, -1 if an error occurred while reading the packet, and -2 if packets are being read from a ``savefile'', and there are no more packets to read from the savefile. If -1 is returned, pcap_geterr() or pcap_perror() may be called with p as an argument to fetch or display the error text.

pcap_next() returns a pointer to the packet data on success, and returns NULL if an error occured, or if no packets were read from a live capture (if, for example, they were discarded because they didn't pass the packet filter, or if, on platforms that support a read timeout that starts before any packets arrive, the timeout expires before any packets arrive, or if the file descriptor for the capture device is in non-blocking mode and no packets were available to be read), or if no more packets are available in a ``savefile.'' Unfortunately, there is no way to determine whether an error occured or not.

pcap(3PCAP), pcap_geterr(3PCAP), pcap_dispatch(3PCAP)