Perl Download Manager

Intro
This is my PERL downloader program, with resume.
Only works if SERVER has Parts enabled.
Well pretty much thats it

#!/usr/bin/perl

use strict;
use threads;
use threads::shared;
use HTTP::Request;
use HTTP::Response;
use Math::Round qw(nearest);
use LWP;



exit unless(defined $ARGV[0] && -e $ARGV[0]);

open HND,$ARGV[0];
NEXT:
while(my $url = <HND>)
{
 my $file = substr($url,rindex($url,"/")+1);
 $file =~ s/%20/_/g;

 chomp $url;

 exit if($url eq "" || $file eq "");

 print "Downloading $url \n to $file \n";


 our @stats:shared = (0,0,0,0,0,0,0,0,0,0,0,0,0,0);
 our $exit:shared = 0;
 our $tdl:shared = 0;
 our $tgl:shared = 0;

 our $lastime:shared = time();
 our $lasdl:shared = 0;

 my $folder = "/home/arun/download/";

 select STDOUT; $| = 1;

 sub catchintr()
 {
  my $who = shift;
  print "\n$who is Bugging me\nDownload Paused\nExit message dispatched";
  $exit = 1;
 }

 $SIG{INT} = \&catchintr;
 $SIG{HUP} = \&catchintr;

 sub dloader
 { 
  select STDOUT; $| = 1;
 
  my ($inx,$url,$localfile,$blockstart,$blockend) = @_;

  my $length = $blockend - $blockstart + 1;
 
  my $stbit = 0;
  if(-f $localfile)
  {
   open HND, $localfile or die $!;
   binmode HND;
   seek HND,0,2;
   $stbit = tell HND;
   close HND;
   $tdl += $stbit;
  }
  else
  {
   open HND,">$localfile" or die $!;
   print HND "";
   close HND;
  }
 
  my $ua = LWP::UserAgent->new;

  my $pcksize = 1024*64;

  my $enbit = $stbit+$pcksize-1;
  my $parts = int($length / $pcksize)+1;
  $enbit = $length - 1 if($enbit > $length);
  my $err =0;
  my $i = int($stbit / $pcksize);

  my $req = HTTP::Request->new('GET',$url);

  if($stbit >= $length)
  {
   print "$localfile Part Complete! $length <=> $stbit\n";
   $stats[$inx] = 1;
   return;
  }
  while($stbit < ($length-1) && $err < 100)
  {
   my $stbit2 = $stbit + $blockstart;
   my $enbit2 = $enbit + $blockstart;
  
   my $range = "bytes=$stbit2-$enbit2";
   $req->header('Range' => $range);
  
   $i++;
  
   print "\n $inx ... $i / $parts ";
   my $res = $ua->request($req);

   threads->yield();  

   if($res->code == 206)
   {
   
    open HND, ">>$localfile";
    binmode HND;
    print HND $res->content;
    close HND;
   
    $stbit = $stbit + $pcksize;
    $enbit = $stbit + $pcksize - 1;
    $enbit = $length - 1 if($enbit > $length);
   
    $tdl += $pcksize;


    if($tdl < 1024)
    {
     print "[$tdl] bytes";
    }
    elsif($tdl < 1024 * 1024)
    {
     print "[".nearest(0.01,$tdl/1024,)." KB]";
    }
    else
    {
     print "[".nearest(0.01,$tdl/1048576)." MB]";
    }

    if((time()-$lastime) > 0)
    {
     print " [ ".nearest(0.01,($tdl-$lasdl) / (1024 * (time() - $lastime) ) ). " kB/s ] ";
     $lasdl = $tdl;
     $lastime = time();
    }
    
   }
   elsif($res->code == 416)
   {
    print "\n\nSeems complete";
    exit;
   }
   else
   {
    print "\nGlitch $err : ";
    print $res->code;
    print "\nResuming...\n";
    sleep 1;
    $i--;
    $err++;
   }
  
   if($exit)
   {
    print "\n$inx is exiting ";
    $stats[$inx] = 1;
    return 0;
   }
  
  }
  if($err == 100)
  {
   print "\nToo many errors in $inx, killing everyone\n";
   $exit = 1;
  }
 
  $stats[$inx] = 1;
  return $err;
 }
 my $errls = 0;

 REDO:
 my $req = HTTP::Request->new('HEAD',$url);
 print $req->as_string;
 my $ua = LWP::UserAgent->new;

 my $res = $ua->request($req);

 print $res->as_string;
 if($res->code != 200)
 {
  print "\n\n";
  goto REDO if($errls++ < 10);
 }


 my $length = $res->header('Content-Length');
 $tgl = $length;
 my $req = HTTP::Request->new('HEAD',$url);
 $req->header('Range' => 'bytes=0-99');
 my $res = $ua->request($req);
 print $res->as_string;
 if($res->code != 206)
 {
  print "Parts cant be used!\n:(\n";
  goto NEXT;
 }

 if(!defined $length)
 {
  $length=-1;
  print "Missing Length
  Any Idea? : ";
  $length = <>;
  print "\n";
 }
 my $blocks = 8;
 my $blocksize = ($length + $blocks - $length % $blocks) / $blocks;
 if($blocksize < 1024 * 512)
 {
  $blocks = 4;
  $blocksize = ($length + $blocks - $length % $blocks) / $blocks;
 }
 #print $blocksize," ",$blocksize*$blocks," ",$length;

 my $blockstart = 0;

 my @thread = ();

 print "\nthreading Gatherers ...\n";

 my ($blockend);
 for(my $i=1;$i<=$blocks;$i++)
 {
  $blockend = $blockstart + $blocksize;
  $blockend = $length if($blockend > $length);
  $thread[$i] = threads->new(sub{dloader($i,$url,$folder."$file.$i.part",$blockstart,$blockend)});
  $blockstart = $blockend + 1;
 }


 my $flag = 0;

 do
 {
  $flag = 0;
  for(my $i=1;$i<=$blocks;$i++)
  {
   $flag = 1 if($stats[$i] == 0);
  }
  sleep 1;
 }
 while($flag);

 if($exit)
 {
  open STAT,">>$folder"."$file.stat";
  print STAT "".localtime;
  print STAT " : Downloaded $tdl / $tgl bytes ".($tdl*100/$tgl)."%\n";
  close STAT;
  exit;
 }

 print "\n\ngathering Gatherers...\n";


 print "\nMerging ... ";

 open OUT,">$file";
 binmode OUT;
 for(my $i=1;$i<=$blocks;$i++)
 {
  print "\n+ ".$folder."$file.$i.part";
  open IN, $folder."$file.$i.part";
  binmode IN;
  my $buffer;
  print OUT $buffer while(read(IN,$buffer,65536));
  close IN;
 
  unlink $folder."$file.$i.part";
 }
 close OUT;
 print "\nDone :)\n";
 open STAT,">>$folder$file.stat";
 print STAT "".localtime;
 print STAT " : Finished Downloading $tdl / $tgl bytes \n";
 close STAT;
}

close HND;