HTML::Scrubber - Perl extension for scrubbing/sanitizing html
#!/usr/bin/perl -w
use HTML::Scrubber;
use strict;
#
my $html = q[
<style type="text/css"> BAD { background: #666; color: #666;} </style>
<script language="javascript"> alert("Hello, I am EVIL!"); </script>
<HR>
a => <a href=1>link </a>
br => <br>
b => <B> bold </B>
u => <U> UNDERLINE </U>
];
#
my $scrubber = HTML::Scrubber->new( allow => [ qw[ p b i u hr br ] ] ); #
#
print $scrubber->scrub($html); #
#
$scrubber->deny( qw[ p b i u hr br ] ); #
#
print $scrubber->scrub($html); #
#
If you wanna "scrub" or "sanitize" html input in a reliable an flexible fashion, then this module is for you.
I wasn't satisfied with HTML::Sanitizer because it is based on HTML::TreeBuilder, so I thought I'd write something similar that works directly with HTML::Parser.
First a note on documentation: just study the EXAMPLE below. It's all the documentation you could need
Also, be sure to read all the comments as well as How does it work?.
If you're new to perl, good luck to you.
warn "comments are ", $p->comment ? 'allowed' : 'not allowed';
$p->comment(0); # off by default
warn "process instructions are ", $p->process ? 'allowed' : 'not allowed';
$p->process(0); # off by default
warn "script tags (and everything in between) are supressed"
if $p->script; # off by default
$p->script( 0 || 1 );
** Please note that this is implemented
using HTML::Parser's ignore_elements function,
so if script is set to true,
all script tags encountered will be validated like all other tags.
warn "style tags (and everything in between) are supressed"
if $p->style; # off by default
$p->style( 0 || 1 );
** Please note that this is implemented
using HTML::Parser's ignore_elements function,
so if style is set to true,
all style tags encountered will be validated like all other tags.
$p->allow(qw[ t a g s ]);
$p->deny(qw[ t a g s ]);
$p->rules(
img => {
src => qr{^(?!http://)}i, # only relative image links allowed
alt => 1, # alt attribute allowed
'*' => 0, # deny all other attributes
},
b => 1,
...
);
print "default is ", $p->default();
$p->default(1); # allow tags by default
$p->default(
undef, # don't change
{ # default attribute rules
'*' => 1, # allow attributes by default
}
);
$html = $scrubber->scrub_file('foo.html'); ## returns giant string
die "Eeek $!" unless defined $html; ## opening foo.html may have failed
$scrubber->scrub_file('foo.html', 'new.html') or die "Eeek $!";
$scrubber->scrub_file('foo.html', *STDOUT)
or die "Eeek $!"
if fileno STDOUT;
print $scrubber->scrub($html); ## returns giant string
$scrubber->scrub($html, 'new.html') or die "Eeek $!";
$scrubber->scrub($html', *STDOUT)
or die "Eeek $!"
if fileno STDOUT;
When a tag is encountered, HTML::Scrubber allows/denies the tag using the explicit rule if one exists.
If no explicit rule exists, Scrubber applies the default rule.
If an explicit rule exists, but it's a simple rule(1), the default attribute rule is applied.
#!/usr/bin/perl -w
use HTML::Scrubber;
use strict;
#
my @allow = qw[ br hr b a ];
#
my @rules = (
script => 0,
img => {
src => qr{^(?!http://)}i, # only relative image links allowed
alt => 1, # alt attribute allowed
'*' => 0, # deny all other attributes
},
);
#
my @default = (
0 => # default rule, deny all tags
{
'*' => 1, # default rule, allow all attributes
'href' => qr{^(?!(?:java)?script)}i,
'src' => qr{^(?!(?:java)?script)}i,
# If your perl doesn't have qr
# just use a string with length greater than 1
'cite' => '(?i-xsm:^(?!(?:java)?script))',
'language' => 0,
'name' => 1, # could be sneaky, but hey ;)
'onblur' => 0,
'onchange' => 0,
'onclick' => 0,
'ondblclick' => 0,
'onerror' => 0,
'onfocus' => 0,
'onkeydown' => 0,
'onkeypress' => 0,
'onkeyup' => 0,
'onload' => 0,
'onmousedown' => 0,
'onmousemove' => 0,
'onmouseout' => 0,
'onmouseover' => 0,
'onmouseup' => 0,
'onreset' => 0,
'onselect' => 0,
'onsubmit' => 0,
'onunload' => 0,
'src' => 0,
'type' => 0,
}
);
#
my $scrubber = HTML::Scrubber->new();
$scrubber->allow( @allow );
$scrubber->rules( @rules ); # key/value pairs
$scrubber->default( @default );
$scrubber->comment(1); # 1 allow, 0 deny
#
## preferred way to create the same object
$scrubber = HTML::Scrubber->new(
allow => \@allow,
rules => \@rules,
default => \@default,
comment => 1,
process => 0,
);
#
require Data::Dumper,die Data::Dumper::Dumper($scrubber) if @ARGV;
#
my $it = q[
<?php echo(" EVIL EVIL EVIL "); ?> <!-- asdf -->
<hr>
<I FAKE="attribute" > IN ITALICS WITH FAKE="attribute" </I><br>
<B> IN BOLD </B><br>
<A NAME="evil">
<A HREF="javascript:alert('die die die');">HREF=JAVA <!></A>
<br>
<A HREF="image/bigone.jpg" ONMOUSEOVER="alert('die die die');">
<IMG SRC="image/smallone.jpg" ALT="ONMOUSEOVER JAVASCRIPT">
</A>
</A> <br>
];
#
print "#original text",$/, $it, $/;
print
"#scrubbed text (default ",
$scrubber->default(), # no arguments returns the current value
" comment ",
$scrubber->comment(),
" process ",
$scrubber->process(),
" )",
$/,
$scrubber->scrub($it),
$/;
#
$scrubber->default(1); # allow all tags by default
$scrubber->comment(0); # deny comments
#
print
"#scrubbed text (default ",
$scrubber->default(),
" comment ",
$scrubber->comment(),
" process ",
$scrubber->process(),
" )",
$/,
$scrubber->scrub($it),
$/;
#
$scrubber->process(1); # allow process instructions (dangerous)
$default[0] = 1; # allow all tags by default
$default[1]->{'*'} = 0; # deny all attributes by default
$scrubber->default(@default); # set the default again
#
print
"#scrubbed text (default ",
$scrubber->default(),
" comment ",
$scrubber->comment(),
" process ",
$scrubber->process(),
" )",
$/,
$scrubber->scrub($it),
$/;
If you have Test::Inline (and you've installed HTML::Scrubber), try
pod2test Scrubber.pm >scrubber.t
perl scrubber.t
HTML::Parser, Test::Inline, HTML::Sanitizer.
Please use https://rt.cpan.org/NoAuth/Bugs.html?Dist=HTML-Scrubber to report bugs/additions/etc or send mail to <bug-HTML-Scrubber#rt.cpan.org>.
D. H. (PodMaster)
Copyright (c) 2003-2004 by D.H. (PodMaster). All rights reserved.
This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. The LICENSE file contains the full text of the license.