NAME
HTML::Scrubber - Perl extension for scrubbing/sanitizing html
VERSION
version 0.10
SYNOPSIS
use HTML::Scrubber;
my $scrubber = HTML::Scrubber->new( allow => [ qw[ p b i u hr br ] ] );
print $scrubber->scrub('<p><b>bold</b> <em>missing</em></p>');
# output is: <p><b>bold</b> </p>
# more complex input
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>
];
print $scrubber->scrub($html);
$scrubber->deny( qw[ p b i u hr br ] );
print $scrubber->scrub($html);
DESCRIPTION
If you want to "scrub" or "sanitize" html input in a reliable and
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.
METHODS
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.
comment
warn "comments are ", $p->comment ? 'allowed' : 'not allowed';
$p->comment(0); # off by default
process
warn "process instructions are ", $p->process ? 'allowed' : 'not allowed';
$p->process(0); # off by default
script
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.
style
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.
allow
$p->allow(qw[ t a g s ]);
deny
$p->deny(qw[ t a g s ]);
rules
$p->rules(
img => {
src => qr{^(?!http://)}i, # only relative image links allowed
alt => 1, # alt attribute allowed
'*' => 0, # deny all other attributes
},
a => {
href => sub { ... }, # check or adjust with a callback
},
b => 1,
...
);
Updates set of attribute rules. Each rule can be 1/0, regular expression
or a callback. Values longer than 1 char are treated as regexps.
Callback is called with the following arguments: this object, tag name,
attribute name and attribute value, should return empty list to drop
attribute, "undef" to keep it without value or a new scalar value.
default
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
}
);
scrub_file
$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;
scrub
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;
*default* handler, used by both _scrub and _scrub_fh Moved all the
common code (basically all of it) into a single routine for ease of
maintenance
*default* handler, does the scrubbing if we're scrubbing out to a file.
Now calls _scrub_str and pushes that out to a file.
*default* handler, does the scrubbing if we're returning a giant string.
Now calls _scrub_str and appends that to the output string.
How does it work?
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.
EXAMPLE
#!/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{^(?:http|https|ftp)://}i,
'src' => qr{^(?:http|https|ftp)://}i,
# If your perl doesn't have qr
# just use a string with length greater than 1
'cite' => '(?i-xsm:^(?:http|https|ftp):)',
'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),
$/;
FUN
If you have Test::Inline (and you've installed HTML::Scrubber), try
pod2test Scrubber.pm >scrubber.t
perl scrubber.t
SEE ALSO
HTML::Parser, Test::Inline, HTML::Sanitizer.
INSTALLATION
See perlmodinstall for information and options on installing Perl
modules.
BUGS AND LIMITATIONS
You can make new bug reports, and view existing ones, through the web
interface at
<http://rt.cpan.org/Public/Dist/Display.html?Name=HTML-Scrubber>.
AVAILABILITY
The project homepage is <https://metacpan.org/release/HTML-Scrubber>.
The latest version of this module is available from the Comprehensive
Perl Archive Network (CPAN). Visit <http://www.perl.com/CPAN/> to find a
CPAN site near you, or see
<https://metacpan.org/module/HTML::Scrubber/>.
AUTHORS
* Ruslan Zakirov <Ruslan.Zakirov@gmail.com>
* Nigel Metheringham <nigelm@cpan.org>
* D. H. <podmaster@cpan.org>
COPYRIGHT AND LICENSE
This software is copyright (c) 2013 by Ruslan Zakirov, Nigel
Metheringham, 2003-2004 D. H..
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.