Re: CGI - hazardous characters

[bradcathey]

in reply to CGI - hazardous characters

Not sure exactly what you are looking for, but here's some Perl that grabs the form value and then tests it for unwanted characters and untaints in the same step. I have a bunch of validation methods depending on what I'm testing for.

Calling script:

($sql{'name'}, $error) = $self->val_text( 1, 64, $self->query->param('
+name') );
   if ( $error-> { msg } ) { push @error_list, { "name" => $error->{ m
+sg } }; }

Validation script

sub val_alphanum {
   my $self = shift;
   my ($mand, $len, $value) = @_;
   if (!$value && $mand) {
      return (undef, { msg => 'cannot be blank' });
   } elsif ($len && (length($value) > $len) ) {
    return (undef, { msg => 'is limited to '.$len.' characters.' });  
   } elsif ($value && $value !~ /^(\w*)$/) {
      return (undef, { msg => 'can only use letters, numbers and _'  
   } else {
      my $tf = new HTML::TagFilter;
      return ($tf->filter($1));
   }
}

I've put a lot of work in to figuring out this CGI stuff—you can see more complete examples at Using Perl, jQuery, and JSON for Web development and A Tutorial for CGI::Application.