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# Movable Type (r) Open Source (C) 2002-2008 Six Apart, Ltd.
# This program is distributed under the terms of the
# GNU General Public License, version 2.
#
# $Id: Sanitize.pm 1174 2008-01-08 21:02:50Z bchoate $
# Original Copyright (c) 2002 Brad Choate
package MT::Sanitize;
use strict;
use MT::Util qw(decode_html);
sub parse_spec {
my $class = shift;
my($a) = @_;
my(%ok_tags, %tag_attr);
for my $rule (split /\s*,\s*/, $a) {
my(%ok_attr, $tag, $style);
$tag = lc $rule;
if ($tag =~ m|^([^\s]+)\s+(.+)$|) {
($tag, my($attrs)) = ($1, $2);
$style = $1 if $tag =~ s|(/)$||;
%ok_attr = map { $_ => 1 } split /\s+/, $attrs;
} else {
$style = $1 if $tag =~ s|(/)$||;
}
$tag_attr{$tag} = $style if $style;
$ok_tags{$tag} = keys %ok_attr ? \%ok_attr : 1;
}
{ ok => \%ok_tags, tag_attr => \%tag_attr }
}
my %Strip = (
'%' => '%>',
'?' => '?>',
'!--' => '-->',
);
my $Strip_RE = join '|', map quotemeta($_), keys %Strip;
sub sanitize {
my $class = shift;
my($s, $arg) = @_;
$s = '' unless defined $s;
$s =~ tr/\x00//d;
$arg = '1' unless defined $arg;
return $s if $arg eq '0';
unless (!$arg || ref($arg)) {
$arg = $class->parse_spec($arg);
}
my $ok_tags = $arg->{ok};
my $tag_attr = $arg->{tag_attr};
my(@open_tags, %open_tags);
my $out = '';
my $start = 0;
my $last_pos = 0;
my $seq = 0;
while ($s =~ m|<|gs) {
my $start = (pos $s) - 1;
my $inside = substr($s, $start + 1, 5); # 5 chars should do it...
if ($last_pos < $start) {
$out .= substr($s, $last_pos, $start - $last_pos);
}
if ($inside =~ m|^($Strip_RE)|) {
my $tag = $1;
pos $s = $start + length($tag) + 1;
if ($s =~ m|\Q$Strip{$tag}\E|gs) {
$last_pos = pos $s;
} else {
# can't find the closure.
$last_pos = pos $s;
last;
}
} elsif ($inside =~ m|^[<>]|) {
$last_pos = $start + 1;
} elsif ($s =~ m|(.+?)>|gs) {
$inside = $1;
$last_pos = pos $s;
my $name;
my $closure = 0;
if ($inside =~ m/^([^ ]+) (.+)$/s) {
$name = lc($1);
$inside = $2;
} else {
$name = lc($inside);
$inside = '';
}
if ($name =~ m|^/|) {
$name =~ s|^/||;
$closure = 1;
}
if ($inside =~ m|/$|s) {
$inside =~ s|/$||s;
$closure = 2;
}
if ($ok_tags->{$name} ||
(exists $tag_attr->{$name} && $tag_attr->{$name} eq '/')) {
if ($inside) {
my @attrs;
while ($inside =~ m/([:\w]+)\s*=\s*(['"])(.*?)\2/gs) {
my ($attr, $q, $val) = (lc($1), $2, $3);
if ($ok_tags->{'*'}{$attr} ||
(ref $ok_tags->{$name} && $ok_tags->{$name}{$attr})) {
my $dec_val = decode_html($val);
if ($attr =~ m/^(src|href|dynsrc)$/) {
$dec_val =~ s/�*58(?:=;|[^0-9])/:/;
$dec_val =~ s/�*3[Aa](?:=;|[^a-fA-F0-9])/:/;
if ((my $prot) = $dec_val =~ m/^([\s\S]+?):/) {
next if $prot =~ m/[\r\n\t]/;
$prot =~ s/\s+//gs;
next if $prot =~ m/[^a-zA-Z0-9\+]/;
next if $prot =~ m/script$/i;
next if $prot =~ m/&#/;
}
}
push @attrs, qq{$attr=$q$val$q};
}
}
$inside = @attrs ? join ' ', @attrs : '';
}
if (exists $tag_attr->{$name} && ($tag_attr->{$name} eq '/')) {
$closure = 2;
}
if ($closure != 1 || ($closure == 1 && $open_tags{$name})) {
if ($closure == 1) {
$out .= _expel_up_to(\@open_tags, \%open_tags, $name);
} elsif (!$closure) {
###if (@open_tags &&
### ($open_tags{$name}) &&
### (exists $tag_attr{$name}) &&
### ($tag_attr{$name} eq '!')) {
### # unnestable tag-- expel stuff
### $out .= _expel_up_to(\@open_tags, \%open_tags, $name);
### $out .= '</' . $name . '>';
###}
push @open_tags, $name;
$open_tags{$name}++;
}
$out .= '<'.($closure==1?'/':'').
$name.
($inside ? ' '.$inside : '').
($closure==2?' /':'').'>';
if ($closure == 1) {
$open_tags{$name}--;
}
}
}
} else {
last;
}
}
if (defined $last_pos && ($last_pos < length($s))) {
if (substr($s, $last_pos) !~ m/</) {
$out .= substr($s, $last_pos);
}
}
if (@open_tags) {
$out .= _expel_up_to(\@open_tags, \%open_tags, '');
}
$out;
}
sub _expel_up_to {
my ($open_tags, $open_hash, $stop_tag) = @_;
my $out = '';
while (@$open_tags &&
(!defined $stop_tag || $open_tags->[$#$open_tags] ne $stop_tag)) {
my $t = pop @$open_tags;
$open_hash->{$t}--;
$out .= '</' . $t . '>';
}
if (@$open_tags) {
my $t = pop @$open_tags;
}
$out;
}
1;
__END__
=head1 NAME
MT::Sanitize - Sanitize HTML for Safety
=head1 SYNOPSIS
use MT::Sanitize;
my $html = <<HTML;
<a name="foo.html" onclick="evilJS()">foolink</a>
HTML
my $str = MT::Sanitize->sanitize($html, 'a href');
## $str is now <a href="foo.html">foolink</a>
=head1 METHODS
=head2 parse_spec($tags)
Return a hash reference of allowed tags and their attributes.
=head2 sanitize($text, [0|1|\%args])
"Sanitize" the I<text> with the rules defined in I<args> (or by the
C<parse_spec> method if rules are not provided).
=head1 AUTHOR & COPYRIGHT
Please see L<MT/AUTHOR & COPYRIGHT>.
=cut
=cut
|
