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Mojolicious-Plugin-SecureCORS-1.0.0
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/ Mojolicious::Plugin::SecureCORS

NAME

Mojolicious::Plugin::SecureCORS - Complete control over CORS

SYNOPSIS

# in Mojolicious app
sub startup {
  my $app = shift;
  …

  # load and configure
  $app->plugin('SecureCORS');
  $app->plugin('SecureCORS', { max_age => undef });

  # set app-wide CORS defaults
  $app->routes->to('cors.credentials'=>1);

  # set default CORS options for nested routes
  $r = $r->under(…, {'cors.origin' => '*'}, …);

  # set CORS options for this route (at least "origin" option must be
  # defined to allow CORS, either here or in parent routes)
  $r->get(…, {'cors.origin' => '*'}, …);
  $r->route(…)->to('cors.origin' => '*');

  # allow non-simple (with preflight) CORS on this route
  $r->cors(…);

  # create bridge to protect all nested routes
  $r = $app->routes->under_strict_cors('/resource');

DESCRIPTION

Mojolicious::Plugin::SecureCORS is a plugin that allow you to configure Cross Origin Resource Sharing for routes in Mojolicious app.

Implements this spec: http://www.w3.org/TR/2014/REC-cors-20140116/.

SECURITY

Don't use the lazy 'cors.origin'=>'*' for resources which should be available only for intranet or which behave differently when accessed from intranet - otherwise malicious website opened in browser running on workstation in intranet will get access to these resources.

Don't use the lazy 'cors.origin'=>'*' for resources which should be available only from some known websites - otherwise other malicious website will be able to attack your site by injecting JavaScript into the victim’s browser.

Consider using under_strict_cors() - it won't "save" you but may helps.

INTERFACE

CORS options

To allow CORS on some route you should define relevant CORS options for that route. These options will be processed automatically using "after_render" in Mojolicious hook and result in adding corresponding HTTP headers to the response.

Options should be added into default parameters for the route or it parent routes. Defining CORS options on parent route allow you to set some predefined defaults for their nested routes.

  • 'cors.origin' => '*'

  • 'cors.origin' => 'null'

  • 'cors.origin' => 'http://example.com'

  • 'cors.origin' => 'https://example.com http://example.com:8080 null'

  • 'cors.origin' => qr/\.local\z/ms

  • 'cors.origin' => undef (default)

    This option is required to enable CORS support for the route.

    Only matched origins will be allowed to process returned response ('*' will match any origin).

    When set to false value no origins will match, so it effectively disable CORS support (may be useful if you've set this option value on parent route).

  • 'cors.credentials' => 1

  • 'cors.credentials' => undef (default)

    While handling preflight request true/false value will tell browser to send or not send credentials (cookies, http auth, ssl certificate) with actual request.

    While handling simple/actual request if set to false and browser has sent credentials will disallow to process returned response.

  • 'cors.expose' => 'X-Some'

  • 'cors.expose' => 'X-Some, X-Other, Server'

  • 'cors.expose' => undef (default)

    Allow access to these headers while processing returned response.

    These headers doesn't need to be included in this option:

    Cache-Control
Content-Language
Content-Type
Expires
Last-Modified
Pragma

  • 'cors.headers' => 'X-Requested-With'

  • 'cors.headers' => 'X-Requested-With, Content-Type, X-Some'

  • 'cors.headers' => qr/\AX-|\AContent-Type\z/msi

  • 'cors.headers' => undef (default)

    Define headers which browser is allowed to send. Work only for non-simple CORS because it require preflight.

  • 'cors.methods' => 'POST'

  • 'cors.methods' => 'GET, POST, PUT, DELETE'

    This option can be used only for cors() route. It's needed in complex cases when it's impossible to automatically detect CORS option while handling preflight - see below for example.

$r->cors(…)

Accept same params as "route" in Mojolicious::Routes::Route.

Add handler for preflight (OPTIONS) CORS request - it's required to allow non-simple CORS requests on given path.

To be able to respond on preflight request this handler should know CORS options for requested method/path. In most cases it will be able to detect them automatically by searching for route defined for same path and HTTP method given in CORS request. Example:

$r->cors('/rpc');
$r->get('/rpc', { 'cors.origin' => 'http://example.com' });
$r->put('/rpc', { 'cors.origin' => qr/\.local\z/ms });

But in some cases target route can't be detected, for example if you've defined several routes for same path using different conditions which can't be checked which processing preflight request because browser didn't sent enough information yet (like Content-Type: value which will be used in actual request). In this case you should manually define all relevant CORS options on preflight route - in addition to CORS options defined on target routes. Because you can't know which one of defined routes will be used to handle actual request, in case they use different CORS options you should use combined in less restrictive way options for preflight route. Example:

$r->cors('/rpc')->to(
    'cors.methods'      => 'GET, POST',
    'cors.origin'       => 'http://localhost http://example.com',
    'cors.credentials'  => 1,
);
$r->any([qw(GET POST)] => '/rpc',
    headers => { 'Content-Type' => 'application/json-rcp' },
)->to('jsonrpc#handler',
    'cors.origin'       => 'http://localhost',
);
$r->post('/rpc',
    headers => { 'Content-Type' => 'application/soap+xml' },
)->to('soaprpc#handler',
    'cors.origin'       => 'http://example.com',
    'cors.credentials'  => 1,
);

This route use "headers" condition, so you can add your own handler for OPTIONS method on same path after this one, to handle non-CORS OPTIONS requests on same path.

$bridge = $r->under_strict_cors(…)

Accept same params as "bridge" in Mojolicious::Routes::Route.

Under returned bridge CORS requests to any route which isn't configured for CORS (i.e. won't have 'cors.origin' in route's default parameters) will be rendered as "403 Forbidden".

This feature should make it harder to attack your site by injecting JavaScript into the victim’s browser on vulnerable website. More details: https://code.google.com/p/html5security/wiki/CrossOriginRequestSecurity#Processing_rogue_COR:.

OPTIONS

Mojolicious::Plugin::SecureCORS supports the following options.

max_age

$app->plugin('SecureCORS', { max_age => undef });

Value for Access-Control-Max-Age: sent by preflight OPTIONS handler. If set to undef this header will not be sent.

Default is 1800 (30 minutes).

METHODS

Mojolicious::Plugin::SecureCORS inherits all methods from Mojolicious::Plugin and implements the following new ones.

register

$plugin->register(Mojolicious->new);
$plugin->register(Mojolicious->new, { max_age => undef });

Register hooks in Mojolicious application.

SEE ALSO

Mojolicious.

BUGS AND LIMITATIONS

No bugs have been reported.

SUPPORT

Please report any bugs or feature requests through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Mojolicious-Plugin-SecureCORS. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

You can also look for information at:

AUTHOR

Alex Efros <powerman@cpan.org>

LICENSE AND COPYRIGHT

Copyright 2014 Alex Efros <powerman@cpan.org>.

This program is distributed under the MIT (X11) License: http://www.opensource.org/licenses/mit-license.php

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.