PCAP_OPEN_OFFLINE(3PCAP) PCAP_OPEN_OFFLINE(3PCAP)

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_t *pcap_fopen_offline_with_tstamp_precision(FILE *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(4), 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.
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(3PCAP), pcap-savefile(4)

30 November 2023 PCAP_OPEN_OFFLINE(3PCAP)