#!/usr/bin/perl
# (C)2002 by IBM Corporation, published under terms of the GPL V2
# Author: Holger Smolinski <smolinsk@de.ibm.com>
# this file is a wrapper around tcpdump, which provides the capability
# for debugging qeth and/or HiperSocket(TM) network interfaces under
# Linux for S/390 and zSeries. tcpdump Syntax is preserved.
# Bugs: When the input pipe ends the process is not stopped.

use Getopt::Std;

my $incmd,$outcmd;

getopts ("adeflnNOpqRStuvxXc:C:F:i:m:r:s:T:w:E:",\%options);

# Check which options to replace for the reader process 
if ( defined($options{'r'}) ) {
  $incmd = "cat $options{'r'}";
  $filter_out = 1;
} else {
  $incmd = "tcpdump -l -w -";
  $filter_out = 0;
  if ( defined($options{'i'}) ) {
    $incmd .= " -i ".$options{'i'};
    delete $options{'i'}; # remove -i option from option list
  }
  foreach $key (@ARGV) {
    $incmd .= " $key";
  }
}

$outcmd = "tcpdump -r -";
# Rebuild arglist for the writer process
delete $options{'r'}; # remove -r option from option list
foreach $key (keys %options) {
  if ((index "adeflnNOpqRStuvxX",$key) >= 0 ) {
    $outcmd .= " -$key";
  } else {
    $outcmd .= " -$key $options{$key}";
  }
  if ( $filter_out == 1 ) {
    foreach $key (@ARGV) {
      $outcmd .= " $key";
    }
  }
} 

open READER,"$incmd|" or die "Cannot spawn reader command $incmd";
open WRITER,"|$outcmd" or die "Cannot spawn writer command $outcmd";

sysread READER,$filehdr,24 or die "Cannot read file header";
($magic,$version_major,$version_minor,$thiszone,$sigfigs,$snaplen,$linktype) = 
  unpack("ISSIIII",$filehdr);
$snaplen += 14;
$filehdr = pack ("ISSIIII",($magic,$version_major,$version_minor,$thiszone,$sigfigs,$snaplen,$linktype));
syswrite WRITER,$filehdr,24;

$etherheaderip6 = pack ("IIIS",(0,0,0,0x8dd));
$etherheaderip4 = pack ("IIIS",(0,0,0,0x800));

while ( 1 ) {
  $hdrd = 0;
  do {$hdrd += sysread READER, $pkthdr, 16-$hdrd, $hdrd; } while ($hdrd < 16);
  ($seconds,$usecs,$caplen,$len) = unpack ("IIII",$pkthdr);
  $hdrd = 0;
  do {$hdrd += sysread READER, $packet,$caplen-$hdrd, $hdrd; } while ($hdrd < $caplen);
  $paktype = unpack("C",$packet);
  if ( $paktype & 0xf0 == 0x60 ) {
    $caplen += 14;
    $len += 14;
    $header = $etehrheaderip6;
  } elsif ($paktype >= 0x45 && $paktype <= 0x4f ) {
    $caplen += 14;
    $len += 14;
    $header = $etherheaderip4;
  } else {
    $header = "";
  }	
  $pkthdr = pack ("IIII",($seconds,$usecs,$caplen,$len));
  syswrite WRITER,"$pkthdr$header$packet",16+$caplen;
}