Hi,

I am parsing input from a CGI form, and so want to run everything through regular expressions to untaint the data.

Yesterday, I grabbed the data ($data = $form->param('input') )and sent it through a reg exp ( $data =~ /(^[\w-.\s\(\)\']+)$/ ) and whenever metacharacters were part of $data, it would knock Perl over.

Then I used $data = "\Q$data\E" before putting it through the regexp, which worked fine.

Today I carry on working, and suddenly the regexp was complaining about everything. I took a look at what was happening, and it was effectively being escaped twice. Perl wasn't complaining (I'm using strict, warnings, CGI qw(:standard) and CGI::Carp qw/fatalsToBrowser/.

It's working now, but I don't know what would make illegal characters knock it over yesterday and not today.

Any info would be greatly appreciated.

waspcatcher

Edit Masem 2001-11-08 - CODE tag on regex.

In reply to metacharacters and reg exps by waspcatcher

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