PCAP_OPEN_OFFLINE(3) PCAP_OPEN_OFFLINE(3)
NAME
pcap_open_offline, pcap_open_offline_with_tstamp_precision,
pcap_fopen_offline, pcap_fopen_offline_with_tstamp_precision - open a
saved capture file for reading
SYNOPSIS
#include <pcap/pcap.h>
char errbuf[PCAP_ERRBUF_SIZE];
pcap_t *pcap_open_offline(const char *fname, char *errbuf);
pcap_t *pcap_open_offline_with_tstamp_precision(const char *fname,
u_int precision, char *errbuf);
pcap_t *pcap_fopen_offline(FILE *fp, char *errbuf);
pcap_fopen_offline_with_tstamp_precision(3) *fp,
u_int precision, char *errbuf);
DESCRIPTION
pcap_open_offline() and pcap_open_offline_with_tstamp_precision() are
called to open a ``savefile'' for reading.
fname specifies the name of the file to open. The file can have the
pcap file format as described in pcap-savefile(5), which is the file
format used by, among other programs, tcpdump(1) and tcpslice(1), or
can have the pcapng file format, although not all pcapng files can be
read. The name "-" is a synonym for stdin.
pcap_open_offline_with_tstamp_precision() takes an additional precision
argument specifying the time stamp precision desired; if
PCAP_TSTAMP_PRECISION_MICRO is specified, packet time stamps will be
supplied in seconds and microseconds, and if PCAP_TSTAMP_PRECISION_NANO
is specified, packet time stamps will be supplied in seconds and
nanoseconds. If the time stamps in the file do not have the same
precision as the requested precision, they will be scaled up or down as
necessary before being supplied.
Alternatively, you may call pcap_fopen_offline() or
pcap_fopen_offline_with_tstamp_precision() to read dumped data from an
existing open stream fp; this stream will be closed by a subsequent
call to pcap_close(3) unless it is stdin.
pcap_fopen_offline_with_tstamp_precision() takes an additional
precision argument as described above. Note that on Windows, that
stream should be opened in binary mode.
errbuf is a buffer large enough to hold at least PCAP_ERRBUF_SIZE
chars.
RETURN VALUE
pcap_open_offline(), pcap_open_offline_with_tstamp_precision(),
pcap_fopen_offline(), and pcap_fopen_offline_with_tstamp_precision()
return a pcap_t * on success and NULL on failure. If NULL is returned,
errbuf is filled in with an appropriate error message.
BACKWARD COMPATIBILITY
pcap_open_offline_with_tstamp_precision() and
pcap_fopen_offline_with_tstamp_precision() became available in libpcap
release 1.5.1. In previous releases, time stamps from a savefile are
always given in seconds and microseconds.
SEE ALSO
pcap(3), pcap-savefile(5)
12 October 2024 PCAP_OPEN_OFFLINE(3)
libpcap 1.10.6 - Generated Wed Dec 31 07:32:20 CST 2025