1CGI::Untaint(3) User Contributed Perl Documentation CGI::Untaint(3)
2
6 CGI::Untaint - process CGI input parameters
7
9 use CGI::Untaint;
10 my $q = new CGI;
12 my $handler = CGI::Untaint->new( $q->Vars );
13 my $handler2 = CGI::Untaint->new({
14 INCLUDE_PATH => 'My::Untaint',
15 }, $apr->parms);
16 my $name = $handler->extract(-as_printable => 'name');
18 my $homepage = $handler->extract(-as_url => 'homepage');
19 my $postcode = $handler->extract(-as_postcode => 'address6');
21 # Create your own handler...
23 package MyRecipes::CGI::Untaint::legal_age;
25 use base 'CGI::Untaint::integer';
26 sub is_valid {
27 shift->value > 21;
28 }
29 package main;
31 my $age = $handler->extract(-as_legal_age => 'age');
32
34 Dealing with large web based applications with multiple forms is a
35 minefield. It's often hard enough to ensure you validate all your input
36 at all, without having to worry about doing it in a consistent manner.
37 If any of the validation rules change, you often have to alter them in
38 many different places. And, if you want to operate taint-safe, then
39 you're just adding even more headaches.
40 This module provides a simple, convenient, abstracted and extensible
42 manner for validating and untainting the input from web forms.
43 You simply create a handler with a hash of your parameters (usually
45 $q->Vars), and then iterate over the fields you wish to extract,
46 performing whatever validations you choose. The resulting variable is
47 guaranteed not only to be valid, but also untainted.
48
50 new
51 my $handler = CGI::Untaint->new( $q->Vars );
52 my $handler2 = CGI::Untaint->new({
53 INCLUDE_PATH => 'My::Untaint',
54 }, $apr->parms);
55 The simplest way to contruct an input handler is to pass a hash of
57 parameters (usually $q->Vars) to new(). Each parameter will then be
58 able to be extracted later by calling an extract() method on it.
59 However, you may also pass a leading reference to a hash of
61 configuration variables.
62 Currently the only such variable supported is 'INCLUDE_PATH', which
64 allows you to specify a local path in which to find extraction
65 handlers. See "LOCAL EXTRACTION HANDLERS".
66
68 extract
69 my $homepage = $handler->extract(-as_url => 'homepage');
70 my $state = $handler->extract(-as_us_state => 'address4');
71 my $state = $handler->extract(-as_like_us_state => 'address4');
72 Once you have constructed your Input Handler, you call the 'extract'
74 method on each piece of data with which you are concerned.
75 The takes an -as_whatever flag to state what type of data you require.
77 This will check that the input value correctly matches the required
78 specification, and return an untainted value. It will then call the
79 is_valid() method, where applicable, to ensure that this doesn't just
80 _look_ like a valid value, but actually is one.
81 If you want to skip this stage, then you can call -as_like_whatever
83 which will perform the untainting but not the validation.
84 error
86 my $error = $handler->error;
87 If the validation failed, this will return the reason why.
89
91 As well as as the handlers supplied with this module for extracting
92 data, you may also create your own. In general these should inherit
93 from 'CGI::Untaint::object', and must provide an '_untaint_re' method
94 which returns a compiled regular expression, suitably bracketed such
95 that $1 will return the untainted value required.
96 e.g. if you often extract single digit variables, you could create
98 package My::Untaint::digit;
100 use base 'CGI::Untaint::object';
102 sub _untaint_re { qr/^(\d)$/ }
104 1;
106 You should specify the path 'My::Untaint' in the INCLUDE_PATH
108 configuration option. (See new() above.)
109 When extract() is called CGI::Untaint will also check to see if you
111 have an is_valid() method also, and if so will run this against the
112 value extracted from the regular expression (available as
113 $self->value).
114 If this returns a true value, then the extracted value will be
116 returned, otherwise we return undef.
117 is_valid() can also modify the value being returned, by assigning
119 $self->value($new_value)
120 e.g. in the above example, if you sometimes need to ensure that the
122 digit extracted is prime, you would supply:
123 sub is_valid { (1 x shift->value) !~ /^1?$|^(11+?)\1+$/ };
125 Now, when users call extract(), it will also check that the value is
127 valid(), i.e. prime:
128 my $number = $handler->extract(-as_digit => 'value');
130 A user wishing to skip the validation, but still ensure untainting can
132 call
133 my $number = $handler->extract(-as_like_digit => 'value');
135 Test::CGI::Untaint
137 If you create your own local handlers, then you may wish to explore
138 Test::CGI::Untaint, available from the CPAN. This makes it very easy to
139 write tests for your handler. (Thanks to Profero Ltd.)
140
142 This package comes with the following simplistic handlers:
143 printable - a printable string
145 integer - an integer
146 hex - a hexadecimal number (as a string)
147 To really make this work for you you either need to write, or download
149 from CPAN, other handlers. Some of the handlers available on CPAN
150 include:
151 asin - an Amazon ID
153 boolean - boolean value
154 country - a country code or name
155 creditcard - a credit card number
156 date - a date (into a Date::Simple)
157 datetime - a date (into a DateTime)
158 email - an email address
159 hostname - a DNS host name
160 html - sanitized HTML
161 ipaddress - an IP address
162 isbn - an ISBN
163 uk_postcode - a UK Postcode
164 url - a URL
165 zipcode - a US zipcode
166
168 None known yet.
169
171 CGI. perlsec. Test::CGI::Untaint.
172
174 Tony Bowden
175
177 Please direct all correspondence regarding this module to:
178 bug-CGI-Untaint@rt.cpan.org
179
181 Copyright (C) 2001-2005 Tony Bowden. All rights reserved.
182 This module is free software; you can redistribute it and/or modify it
184 under the same terms as Perl itself.
185perl v5.12.0 2005-09-20 CGI::Untaint(3)