Hack this.

sub normalize_path {
  my ( $path ) = @_ ;
  return '' unless $path;
  # ensure that multiple %HH encoded stuff is decoded completely (know
+n hack)
  1 while $path =~ s/%([0-9a-fA-F]{2})/chr hex $1/ge;
  # get rid of those damn back slashes
  $path =~ s!\\+!/!g;
  # I don't see the need for many more chars than these
  # as the stated purpose is docs, not cgi ?;&= are
  # pointless, espacially as I just destroyed the query
  # string (potentially) if these are encoded with %HH
  $path =~ s![^\w \Q-?&;:,=./#\E]!!g;
  # fix ../ we don't have any \ left to fool us
  $path =~ s!\.\.?/!!g;
  # trim leading whitespace
  $path =~ s/^\s+//g;
  # allow single spaces for say Documents and Settings
  $path =~ s/ +/ /g;
  return  $path ;
}
[download]

cheers

tachyon

s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print

Hack this.

Piece of cake:

my $up_dir = '.../...//';
my $path = ($up_dir x 10) . 'etc/passwd';
print normalize_path($path), "\n";
[download]

Prints:

../../../../../../../../../../etc/passwd
[download]

--
Ilya Martynov, ilya@iponweb.net
CTO IPonWEB (UK) Ltd
Quality Perl Programming and Unix Support UK managed @ offshore prices - http://www.iponweb.net
Personal website - http://martynov.org

Cute! ++ of course. I find it fascinating how you can use ingenuity to spoof these types of filters. Here is one that provides more utility and of course patches your hack.

sub ilya_proof_path {
  my ( $path ) = @_ ;
  return '' unless $path;
  my ($type, $domain, $q_string );
  ( $path, $q_string ) = split '\?', $path;
  $q_string =~ tr/\0//d if $q_string;
  1 while $path =~ s/%([0-9a-fA-F]{2})/chr hex $1/ge;
  $path =~ s!\\+!/!g;
  $path =~ s![^\w \Q-:./#\E]!!g;
  $path =~ s!\.\.*/!!g;
  $path =~ s/^\s+//g;
  $path =~ s/ +/ /g;
  $type = $1 if  $path =~ s!^(\w+):/+!!;
  $domain = $1 if $type and $type =~ m/(?:https?|ftps?)/ and $path =~ 
+s!^([\w\.-]+)/!!;
  # tolerate win32 drive letters as a pseudo domain
  $domain = $1 if $type and $type =~ m/file/ and $path =~ s!^([A-Z]:)/
+!!;
  return  $path, $type, $domain, $q_string ;
}
[download]

cheers

tachyon

s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print