Provided by: libplack-middleware-csrfblock-perl_0.10-1_all 
NAME
Plack::Middleware::CSRFBlock - Block CSRF Attacks with minimal changes to your app
VERSION
version 0.10
SYNOPSIS
use Plack::Builder;
my $app = sub { ... }
builder {
enable 'Session';
enable 'CSRFBlock';
$app;
}
DESCRIPTION
This middleware blocks CSRF. You can use this middleware without any modifications to your
application, in most cases. Here is the strategy:
output filter
When the application response content-type is "text/html" or "application/xhtml+xml",
this inserts a hidden input tag that contains a token string into "form"s in the
response body. For example, when the application response body is:
<html>
<head>
<title>input form</title>
</head>
<body>
<form action="/api" method="post">
<input type="text" name="email" /><input type="submit" />
</form>
</html>
This becomes:
<html>
<head>
<title>input form</title>
</head>
<body>
<form action="/api" method="post"><input type="hidden" name="SEC" value="0f15ba869f1c0d77" />
<input type="text" name="email" /><input type="submit" />
</form>
</html>
This affects "form" tags with "method="post"", case insensitive.
It is possible to add an optional meta tag by setting "meta_tag" to a defined value.
The 'name' attribute of the HTML tag will be set to the value of "meta_tag". For the
previous example, when "meta_tag" is set to 'csrf_token', the output will be:
<html>
<head><meta name="csrf_token" content="0f15ba869f1c0d77"/>
<title>input form</title>
</head>
<body>
<form action="/api" method="post"><input type="hidden" name="SEC" value="0f15ba869f1c0d77" />
<input type="text" name="email" /><input type="submit" />
</form>
</html>
input check
For every POST requests, this module checks the "X-CSRF-Token" header first, then
"POST" input parameters. If the correct token is not found in either, then a 403
Forbidden is returned by default.
Supports "application/x-www-form-urlencoded" and "multipart/form-data" for input
parameters, but any "POST" will be validated with the "X-CSRF-Token" header. Thus,
every "POST" will have to have either the header, or the appropriate form parameters
in the body.
javascript
This module can be used easily with javascript by having your javascript provide the
"X-CSRF-Token" with any ajax "POST" requests it makes. You can get the "token" in
javascript by getting the value of the "csrftoken" "meta" tag in the page <head>.
Here is sample code that will work for "jQuery":
$(document).ajaxSend(function(e, xhr, options) {
var token = $("meta[name='csrftoken']").attr("content");
xhr.setRequestHeader("X-CSRF-Token", token);
});
This will include the X-CSRF-Token header with any "AJAX" requests made from your
javascript.
OPTIONS
use Plack::Builder;
my $app = sub { ... }
builder {
enable 'Session';
enable 'CSRFBlock',
parameter_name => 'csrf_secret',
token_length => 20,
session_key => 'csrf_token',
blocked => sub {
[302, [Location => 'http://www.google.com'], ['']];
},
onetime => 0,
;
$app;
}
parameter_name (default:"SEC")
Name of the input tag for the token.
meta_tag (default:undef)
Name of the "meta" tag added to the "head" tag of output pages. The content of this
"meta" tag will be the token value. The purpose of this tag is to give javascript
access to the token if needed for AJAX requests. If this attribute is not explicitly
set the meta tag will not be included.
header_name (default:"X-CSRF-Token")
Name of the HTTP Header that the token can be sent in. This is useful for sending the
header for Javascript AJAX requests, and this header is required for any post request
that is not of type "application/x-www-form-urlencoded" or "multipart/form-data".
token_length (default:16);
Length of the token string. Max value is 40.
session_key (default:"csrfblock.token")
This middleware uses Plack::Middleware::Session for token storage. this is the session
key for that.
blocked (default:403 response)
The application called when CSRF is detected.
Note: This application can read posted data, but DO NOT use them!
onetime (default:FALSE)
If this is true, this middleware uses onetime token, that is, whenever client sent
collect token and this middleware detect that, token string is regenerated.
This makes your applications more secure, but in many cases, is too strict.
SEE ALSO
Plack::Middleware::Session
AUTHORS
• Rintaro Ishizaki <rintaro@cpan.org>
• William Wolf <throughnothing@gmail.com>
• Matthew Phillips <mattp@cpan.org>
COPYRIGHT AND LICENSE
This software is copyright (c) 2014 by the Authors of Plack-Middleware-CSRFBlock.
This is free software; you can redistribute it and/or modify it under the same terms as
the Perl 5 programming language system itself.