In most of my applications I like to handle authorization (querying the ACL) in one (or more) of three ways:
In general I find it’s best to keep authorization within the domain (querying the ACL within my models when they’re accessed) as this provides the most consistent behavior. For example, if I eventually add a REST API to my application I don’t have to duplicate all my authorization logic in the new REST controllers. When the application calls something like Default_Model_Post::save() it either saves or throws an ACL exception, no matter where it was called from. This is great in that it saves me from having to duplicate code and keeps my system more secure.
On the other hand, there are times when it’s just a lot easier to handle authorization in the controller. For example, if guests should never access my “Admin” module, it doesn’t make sense to ever let them access /admin/ URLs. Also, if you’re using Zend_Navigation, having ACL resources that match controller actions lets you utilize its ACL integration.
If you’re ever going to mix these two techniques, you’ll eventually bump into the case where a model and a controller share the same name. What if you need to set permissions on a “user” controller and different permissions on a “user” model? This is where namespacing comes into play. As suggested by the Zend Framework manual, I always name my controller action resources in the format mvc:module.controller.action. I name my model resources similarly, in the format model:module.modelName.methodName. In both theses cases, “mvc” and “model” are the namespace, and everything following the colon is the actual resource name. Now I can refer to my “admin” module as mvc:admin and the models within my admin module as model:admin.
This is where things get interesting. If you set up your ACL chains correctly, you can set permissions on whole modules or models and have those rules cascade to their child controllers or methods. For example, say you set up your ACL as follows:
$acl = new Zend_Acl();
$acl->addResource('mvc:');
$acl->addResource('mvc:admin', 'mvc:');
$acl->addResource('mvc:admin.user', 'mvc:admin');
$acl->addResource('mvc:admin.user.create', 'mvc:admin.user');
$acl->addRole('guest');
$acl->addRole('admin', 'guest');
$acl->deny();
$acl->allow('admin', 'mvc:admin');
Now if a user with the role “admin” tries to access the resource “mvc:admin.user.create” (http://basename/admin/user/create) they will be allowed, but a user with the role “guest” will not. Using this technique gives you as much granularity as you need in your ACL, but at the same time lets you set broad permissions where appropriate.
This is where Galahad_Acl comes into play. Setting up all these resources can be tedious, as is checking permissions in each controller. Galahad_Acl in conjunction with Galahad_Model_Entity and Galahad_Controller_Plugin_Acl automate everything but the actual permissions that are specific to your application.
Continue reading “Namespacing ACL resources & Galahad_Acl” »
Recent Comments