PCAP_OPEN_OFFLINE(3)   FreeBSD Library Functions Manual   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_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(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)