CGI::Untaint(3pm)					User Contributed Perl Documentation					 CGI::Untaint(3pm)

NAME

       CGI::Untaint - process CGI input parameters

SYNOPSIS

	 use CGI::Untaint;

	 my $q = new CGI;
	 my $handler = CGI::Untaint->new( $q->Vars );
	 my $handler2 = CGI::Untaint->new({
	       INCLUDE_PATH => 'My::Untaint',
	 }, $apr->parms);

	 my $name     = $handler->extract(-as_printable => 'name');
	 my $homepage = $handler->extract(-as_url => 'homepage');

	 my $postcode = $handler->extract(-as_postcode => 'address6');

	 # Create your own handler...

	 package MyRecipes::CGI::Untaint::legal_age;
	 use base 'CGI::Untaint::integer';
	 sub is_valid {
	   shift->value > 21;
	 }

	 package main;
	 my $age = $handler->extract(-as_legal_age => 'age');

DESCRIPTION

       Dealing with large web based applications with multiple forms is a minefield. It's often hard enough to ensure you validate all your input
       at all, without having to worry about doing it in a consistent manner. If any of the validation rules change, you often have to alter them
       in many different places. And, if you want to operate taint-safe, then you're just adding even more headaches.

       This module provides a simple, convenient, abstracted and extensible manner for validating and untainting the input from web forms.

       You simply create a handler with a hash of your parameters (usually $q->Vars), and then iterate over the fields you wish to extract,
       performing whatever validations you choose. The resulting variable is guaranteed not only to be valid, but also untainted.

CONSTRUCTOR

   new
	 my $handler  = CGI::Untaint->new( $q->Vars );
	 my $handler2 = CGI::Untaint->new({
	       INCLUDE_PATH => 'My::Untaint',
	 }, $apr->parms);

       The simplest way to contruct an input handler is to pass a hash of parameters (usually $q->Vars) to new(). Each parameter will then be able
       to be extracted later by calling an extract() method on it.

       However, you may also pass a leading reference to a hash of configuration variables.

       Currently the only such variable supported is 'INCLUDE_PATH', which allows you to specify a local path in which to find extraction
       handlers.  See "LOCAL EXTRACTION HANDLERS".

METHODS

   extract
	 my $homepage = $handler->extract(-as_url => 'homepage');
	 my $state = $handler->extract(-as_us_state => 'address4');
	 my $state = $handler->extract(-as_like_us_state => 'address4');

       Once you have constructed your Input Handler, you call the 'extract' method on each piece of data with which you are concerned.

       The takes an -as_whatever flag to state what type of data you require. This will check that the input value correctly matches the required
       specification, and return an untainted value. It will then call the is_valid() method, where applicable, to ensure that this doesn't just
       _look_ like a valid value, but actually is one.

       If you want to skip this stage, then you can call -as_like_whatever which will perform the untainting but not the validation.

   error
	 my $error = $handler->error;

       If the validation failed, this will return the reason why.

LOCAL EXTRACTION HANDLERS

       As well as as the handlers supplied with this module for extracting data, you may also create your own. In general these should inherit
       from 'CGI::Untaint::object', and must provide an '_untaint_re' method which returns a compiled regular expression, suitably bracketed such
       that $1 will return the untainted value required.

       e.g. if you often extract single digit variables, you could create

	 package My::Untaint::digit;

	 use base 'CGI::Untaint::object';

	 sub _untaint_re { qr/^(d)$/ }

	 1;

       You should specify the path 'My::Untaint' in the INCLUDE_PATH configuration option.  (See new() above.)

       When extract() is called CGI::Untaint will also check to see if you have an is_valid() method also, and if so will run this against the
       value extracted from the regular expression (available as $self->value).

       If this returns a true value, then the extracted value will be returned, otherwise we return undef.

       is_valid() can also modify the value being returned, by assigning
	 $self->value($new_value)

       e.g. in the above example, if you sometimes need to ensure that the digit extracted is prime, you would supply:

	 sub is_valid { (1 x shift->value) !~ /^1?$|^(11+?)1+$/ };

       Now, when users call extract(), it will also check that the value is valid(), i.e. prime:

	 my $number = $handler->extract(-as_digit => 'value');

       A user wishing to skip the validation, but still ensure untainting can call

	 my $number = $handler->extract(-as_like_digit => 'value');

   Test::CGI::Untaint
       If you create your own local handlers, then you may wish to explore Test::CGI::Untaint, available from the CPAN. This makes it very easy to
       write tests for your handler. (Thanks to Profero Ltd.)

AVAILABLE HANDLERS

       This package comes with the following simplistic handlers:

	 printable  - a printable string
	 integer    - an integer
	 hex	    - a hexadecimal number (as a string)

       To really make this work for you you either need to write, or download from CPAN, other handlers. Some of the handlers available on CPAN
       include:

	 asin	      - an Amazon ID
	 boolean      - boolean value
	 country      - a country code or name
	 creditcard   - a credit card number
	 date	      - a date (into a Date::Simple)
	 datetime     - a date (into a DateTime)
	 email	      - an email address
	 hostname     - a DNS host name
	 html	      - sanitized HTML
	 ipaddress    - an IP address
	 isbn	      - an ISBN
	 uk_postcode  - a UK Postcode
	 url	      - a URL
	 zipcode      - a US zipcode

BUGS

       None known yet.

SEE ALSO

       CGI. perlsec. Test::CGI::Untaint.

AUTHOR

       Tony Bowden

BUGS and QUERIES
       Please direct all correspondence regarding this module to:
	 bug-CGI-Untaint@rt.cpan.org

COPYRIGHT and LICENSE
       Copyright (C) 2001-2005 Tony Bowden. All rights reserved.

       This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

perl v5.10.0							    2005-09-20							 CGI::Untaint(3pm)