getsockname() on closed socket

CODE:

#!c:/perl/bin/perl.exe -w
use Net::FTP;
use strict;
my $server='202.96.64.144';
my $user = 'anonymous';
my $pw = 'anonymous';
my $ftp = Net::FTP->new($server) ;
$ftp->login($user,$pw) ;
#print "login ok! starting list files on $server....\n";
&list("/pub");
$ftp->quit;
sub list()
{
my $current = $_[0];
my @subdirs;

$ftp->cwd($current);
my @allfiles = $ftp->ls();

foreach (@allfiles){
  if(&find_type($_) eq "d"){
   push @subdirs,$_;
  }
  else{
   print $current."/$_\n";
  }
}

foreach (@subdirs){

  &list($current . "/" . $_);
}
}


sub find_type{
my $path = shift;
my $pwd = $ftp->pwd;
my $type = '-';
if ($ftp->cwd($path)) {
  $ftp->cwd ($pwd);
  $type = 'd';
}
return $type;
}