#!/usr/bin/perl

use Net::Pcap;
$|=1;

$nargs=@ARGV;
if ($nargs != 3){ die "ddpcap <source> <basename> <n{b|p|s|m}>\n"; }

$source = $ARGV[0] ;
$seg = $ARGV[1] ;
$seq = 0;
$count = $ARGV[2] ;
$unit = chop($count);
unless ($unit =~ /[bpsm]/){
	die "invalid qualifier: \"$unit\"\n";
}

die "i can't find the source file \"$source\"\n" unless ( -e $source );

if ($unit =~ /m/){
	$unit = "s";
	$count *= 60 ;
}

$fp_time = 0;
$done = 0;
$pcap_ifd = Net::Pcap::open_offline($source, \$err);

while (!$done){
	$c = 0; $fp_time = 0;
 	$name = sprintf("%s_%06d.tcp",$seg,$seq);
	$pcap_ofd = Net::Pcap::open_offline($name, \$err);
	$pcap_ofd_dumper = Net::Pcap::dump_open($pcap_ifd, $name);
	$seq++;
	print "dumping to $name.\n";

	do {
		$pkt_data = Net::Pcap::next($pcap_ifd, \%pkt_hdr);
		if($pkt_data eq "" ){
			$done = 1;
			Net::Pcap::close($pcap_ifd);
			print "closed $name.\n";
			exit;
		}
		&calculate;
		Net::Pcap::dump($pcap_ofd_dumper, \%pkt_hdr, $pkt_data);
	} while ( $c < $count );
	Net::Pcap::dump_close($pcap_ofd_dumper);
	print "closed $name.\n";
}

# ----------------------------------------------------------------
sub calculate{
	if($unit =~ /s/){
		if ($fp_time == 0){
			$fp_time = $pkt_hdr{tv_sec};
		}
		$c = $pkt_hdr{tv_sec} - $fp_time;
		#seconds
	} elsif($unit =~ /b/){
		$c += $pkt_hdr{len} ; #bytes
	} else {
		$c++ ; #packets
	}
}
	
# ----------------------------------------------------------------