NAME

       pcap_dump_open,  pcap_dump_open_append,  pcap_dump_fopen  -  open a file to which to write
       packets

SYNOPSIS

       #include <pcap/pcap.h>

       pcap_dumper_t *pcap_dump_open(pcap_t *p, const char *fname);
       pcap_dumper_t *pcap_dump_open_append(pcap_t *p, const char *fname);
       pcap_dumper_t *pcap_dump_fopen(pcap_t *p, FILE *fp);

DESCRIPTION

       pcap_dump_open() is called to open a ``savefile'' for writing.  fname specifies  the  name
       of  the  file  to open. The file will have the same format as those used by tcpdump(1) and
       tcpslice(1).  If the file does not exist, it will be created; if the file exists, it  will
       be truncated and overwritten.  The name "-" is a synonym for stdout.

       pcap_dump_fopen()  is called to write data to an existing open stream fp; this stream will
       be closed by a subsequent call to pcap_dump_close(3PCAP).  The stream is assumed to be  at
       the  beginning  of  a  file  that has been newly created or truncated, so that writes will
       start at the beginning of the file.  Note that on Windows, that stream should be opened in
       binary mode.

       p  is  a  capture or ``savefile'' handle returned by an earlier call to pcap_create(3PCAP)
       and activated by an earlier call to pcap_activate(3PCAP), or returned by an  earlier  call
       to  pcap_open_offline(3PCAP),  pcap_open_live(3PCAP),  or pcap_open_dead(3PCAP).  The time
       stamp precision, link-layer type, and snapshot length from p are used  as  the  link-layer
       type and snapshot length of the output file.

       pcap_dump_open_append() is like pcap_dump_open() but, if the file already exists, and is a
       pcap file with the same byte order as the host opening the file, and  has  the  same  time
       stamp  precision,  link-layer  header  type,  and  snapshot length as p, it will write new
       packets at the end of the file.

RETURN VALUE

       A pointer  to  a  pcap_dumper_t  structure  to  use  in  subsequent  pcap_dump(3PCAP)  and
       pcap_dump_close(3PCAP)  calls  is  returned  on success.  NULL is returned on failure.  If
       NULL is returned, pcap_geterr(3PCAP) can be used to get the error text.

BACKWARD COMPATIBILITY

       The pcap_dump_open_append() function  became  available  in  libpcap  release  1.7.2.   In
       previous releases, there is no support for appending packets to an existing savefile.

SEE ALSO

       pcap(3PCAP), pcap-savefile(5)

                                           3 July 2020                      PCAP_DUMP_OPEN(3PCAP)