Okay. As some of you may remember, I asked a question a couple of days ago about comparing packet data to find common substrings. (See My Original Post)
I have written some code (see below) that appears to produce valid output. However, when I was looking through the output, I've noticed that some of the substring match counts are wrong. For a sample run, I copied the same packet data four times, which should have made the output a little easier to check.
The first line of output is a substring that contains all of the packet data, so it makes sense that there are four matches. The second line bothers me, though. It's a substring length($packet)-1 in size. Eye-grepping the input, I can see that this should have four matches as well, but when I run the script I get 7!
I'm not asking for an in-depth analysis, but I've been looking at it so much in the last couple of days that I may be missing something obvious. Any help is appreciated!
die "No file name" unless @ARGV;

my @packets = ();
my $short = 9999;

while (<>)
{
 push(@packets,$_);
 if (length($_)-1 < $short)
 {
  $short = length($_) -1; # Find shortest packet
 }
}
chop(@packets);


my $maxlen =0;
my $index = 0;
my $curpack;
my %all;
foreach $curpack (@packets)
{
 #Iterate over packets
 $maxlen = length($curpack);
 for (my $fsize = 2; $fsize <= $maxlen; $fsize ++)
 {
  #Check size 2..$maxlen substrings
  for (my $pnum = 0; $pnum < @packets; $pnum ++)
  {
   #Iterate over packets to check against
   for (0..($maxlen-$fsize+1))
   {
    #Don't compare against self or shorter strings
    if (($index != $pnum) && ($fsize <= length($packets[$pnum])))
    {
     my $str = substr($curpack,$_,$fsize);
     my @temparr = ($packets[$pnum] =~ /$str/g);
     my $nmatch = @temparr;
     if (defined($all{$str}))
     {
      $all{$str} += $nmatch;
     }
     else
     {
      #Remember to count self
      $all{$str} = $nmatch + 1;
     }
    undef @temparr;
    }
   }
  }
 }
 $index ++;
 print "Comparing packet ",$index," to all others:\n";
 my $value;
 my @sort = sort {length($b) <=> length($a)} keys %all;
 foreach $value (@sort)
 {
  #Show only results in >1 packet
  if ($all{$value} > 1) 
  {
   print "(",length($value),") $value: $all{$value} times\n";
  }
  delete($all{$value});
 }
 undef @sort;
}

exit;

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In reply to Packet Patterns redux - my script can't count by Guildenstern

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