use strict;
use English;
use IPC::Open2;
use Data::Dumper;

$|++;

my $TSHARKOPTS = "-l -V -i -";
my $TSHARK = $ENV{TSHARK} || '/opt/exp/sbin/tshark' || 'tshark';

# Need to use elsif's here, since perl (-e) uses unix-type path names
#	and TSHARK needs dos-type path names...
if($OSNAME eq 'MSWin32'){
	if(-e $ENV{TSHARK}) {
		$TSHARK = $ENV{TSHARK};
	}elsif(-e 'c:/Program Files/wireshark/tshark.exe' ) {
		$TSHARK = "c:\\\"Program Files\"\\wireshark\\tshark.exe";
	}else{
		die "Cannot find TSHARK";
	}
}

# Startup child...
my $CHILD = open2(\*READ, \*WRITE, "$TSHARK $TSHARKOPTS") ||
		die "Can't open2 child process: $!";

print STDERR "tshark started CHILD=$CHILD...\n";

my @header = (
0xa1b2, 0xc3d4, 0x0002, 0x0004, 0x0000, 0x0000, 0x0000, 0x0000,
0x0000, 0xffff, 0x0000, 0x0001);

my @msg1 = (
0x4c, 0x52, 0x56, 0x67, 0x00, 0x0c, 0xc5, 0x88, 0x00, 0x00, 0x00,
0x56, 0x00, 0x00, 0x00, 0x56, 0x00, 0x21, 0x05, 0x6e, 0x7d, 0xcb,
0x00, 0x16, 0x4d, 0xc4, 0xdf, 0x64, 0x08, 0x00, 0x45, 0x02, 0x00,
0x48, 0x00, 0x00, 0x40, 0x00, 0x3f, 0x84, 0x1f, 0xdb, 0x0a, 0x98,
0x02, 0x21, 0x0a, 0x98, 0x04, 0x05, 0x0b, 0xb9, 0x04, 0x00, 0x78,
0xa1, 0x28, 0xad, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0x00, 0x26,
0x4d, 0x2b, 0x6d, 0xf8, 0x00, 0x01, 0x00, 0x7c, 0x00, 0x00, 0x00,
0x12, 0x00, 0x17, 0x00, 0x12, 0x00, 0x00, 0x02, 0x00, 0x63, 0x00,
0x05, 0x04, 0x46, 0xb3, 0x00, 0x00, 0x00, 0x02, 0x40, 0x02, 0x02,
0x80, 0x00, 0x00,
);

my $bhead = pack('n*', @header);
my $bmsg1 = pack('c*', @msg1);

# Output PCAP file header to tshark...
print WRITE $bhead;

# Count as we go through the message loop...
my $c=0;
while (1)
{
	if(! $CHILD) { last };
	$c++;
	# Force a blocking read after 2 rounds...
	if($c<3) {
		print WRITE $bmsg1;
	}
	my $got = NBread(\*READ);
	print STDERR "$c: ", scalar(split(/^/, $got)), " lines\n";
	sleep 1;
}

sub NBread
{
	my $fd = shift || die "Missing read file descriptor";

	# Read from decoder...
	my $line;
	my $otext;
	eval {
		local $SIG{ALRM} = sub { die 'TIMEOUT' };
		do {
			alarm 2;
			if( ! ($line = <$fd>) ) {
				# Child died for some reason...
				alarm 0;
				warn "Decoder pid=$CHILD, not available!\n";
				undef($CHILD);
				last;
			}
			$otext .= $line;
			alarm 0;
		} until ($line =~ /^\s*$/);
	};
	if ($@) { print STDERR "$@" };

	return($otext);
}