.\" @(#) $Header: /tcpdump/master/libpcap/pcap_next_ex.3pcap,v 1.3 2008-04-06 02:53:22 guy Exp $
.\"
.\" Copyright (c) 1994, 1996, 1997
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that: (1) source code distributions
.\" retain the above copyright notice and this paragraph in its entirety, (2)
.\" distributions including binary code include the above copyright notice and
.\" this paragraph in its entirety in the documentation or other materials
.\" provided with the distribution, and (3) all advertising materials mentioning
.\" features or use of this software display the following acknowledgement:
.\" ``This product includes software developed by the University of California,
.\" Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
.\" the University nor the names of its contributors may be used to endorse
.\" or promote products derived from this software without specific prior
.\" written permission.
.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
.\"
.TH PCAP_NEXT_EX 3PCAP "5 April 2008"
.SH NAME
pcap_next_ex, pcap_next \- read the next packet from a pcap_t
.SH SYNOPSIS
.nf
.ft B
#include <pcap/pcap.h>
.ft
.LP
.ft B
int pcap_next_ex(pcap_t *p, struct pcap_pkthdr **pkt_header,
.ti +8
const u_char **pkt_data);
const u_char *pcap_next(pcap_t *p, struct pcap_pkthdr *h);
.ft
.fi
.SH DESCRIPTION
.B 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
.I pkt_header
argument is set to point to the
.I pcap_pkthdr
struct for the packet, and the
pointer pointed to by the
.I pkt_data
argument is set to point to the data in the packet.
.PP
.B pcap_next()
reads the next packet (by calling
.B pcap_dispatch()
with a
.I cnt
of 1) and returns a
.I u_char
pointer to the data in that packet.
The
.I pcap_pkthdr
structure pointed to by
.I h
is filled in with the appropriate values for the packet.
.SH RETURN VALUE
.B 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,
.B pcap_geterr()
or
.B pcap_perror()
may be called with
.I p
as an argument to fetch or display the error text.
.PP
.B pcap_next()
returns a pointer to the packet data on success, and returns
.B 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.
.SH SEE ALSO
pcap(3PCAP), pcap_geterr(3PCAP), pcap_dispatch(3PCAP)