xref: /freebsd/contrib/libpcap/pcap_stats.3pcap (revision a831d7d1c538b93ffec095657d9a6e6e778db195)
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.

PCAP_STATS 3PCAP "7 September 2009"
NAME
pcap_stats - get capture statistics
SYNOPSIS
#include <pcap/pcap.h>

int pcap_stats(pcap_t *p, struct pcap_stat *ps);

DESCRIPTION
pcap_stats() fills in the struct pcap_stat pointed to by its second argument. The values represent packet statistics from the start of the run to the time of the call.

pcap_stats() is supported only on live captures, not on ``savefiles''; no statistics are stored in ``savefiles'', so no statistics are available when reading from a ``savefile''.

A struct pcap_stat has the following members:

ps_recv number of packets received;

ps_drop number of packets dropped because there was no room in the operating system's buffer when they arrived, because packets weren't being read fast enough;

ps_ifdrop number of packets dropped by the network interface or its driver.

The statistics do not behave the same way on all platforms. ps_recv might count packets whether they passed any filter set with pcap_setfilter (3PCAP) or not, or it might count only packets that pass the filter. It also might, or might not, count packets dropped because there was no room in the operating system's buffer when they arrived. ps_drop is not available on all platforms; it is zero on platforms where it's not available. If packet filtering is done in libpcap, rather than in the operating system, it would count packets that don't pass the filter. Both ps_recv and ps_drop might, or might not, count packets not yet read from the operating system and thus not yet seen by the application. ps_ifdrop might, or might not, be implemented; if it's zero, that might mean that no packets were dropped by the interface, or it might mean that the statistic is unavailable, so it should not be treated as an indication that the interface did not drop any packets.

RETURN VALUE
pcap_stats() returns 0 on success and returns -1 if there is an error or if p doesn't support packet statistics. If -1 is returned, pcap_geterr() or pcap_perror() may be called with p as an argument to fetch or display the error text.
SEE ALSO
pcap(3PCAP), pcap_geterr(3PCAP)