symfony2 get firewall name on login page - security

Question

I'd want to use a login page to access different firewalls, so I need to get information about the firewall I'm logging in.
In my controller I'd use
$this->container->get('security.context')->getToken()->getProviderKey()
but as an anonymous user I don't have access to getProviderKey method.
I could also parse
_security.xxx.target_path
to get xxx firewall but I'm looking for a more general solution if it exists at all.
Any idea?

Answer 1

As of symfony 3.2, you can now get the current firewall configuration using the following:
public function indexAction(Request $request)
{
$firewall = $this->container
->get('security.firewall.map')
->getFirewallConfig($request)
->getName();
}
Ref: http://symfony.com/blog/new-in-symfony-3-2-firewall-config-class-and-profiler

Answer 2

For Symfony 3.4 I wrote this to avoid referencing the non-public "security.firewall.map" service:
$firewallName = null;
if (($firewallContext = trim($request->attributes->get("_firewall_context", null))) && (false !== ($firewallContextNameSplit = strrpos($firewallContext, ".")))) {
$firewallName = substr($firewallContext, $firewallContextNameSplit + 1);
}
(Referencing "security.firewall.map" on 3.4 will throw an exception.)
Edit: This will not work in a custom exception controller function.

Answer 3

I was doing a little research on this myself recently so that I could send this information in an XACML request as part of the environment.
As far as I can tell from GitHub issues like this one:
https://github.com/symfony/symfony/issues/14435
There is currently no way to reliably get the information out of Symfony except the dirty compiler pass hack suggested on the linked issue. It does appear from the conversation on these issues, they are working on making this available, however, the status is still open, so we will have to be patient and wait for it to be provided.

Answer 4

#Adambean's answer is pretty elegant, but I'd write it as a one-liner:
$firewallName = array_slice(explode('.', trim($request->attributes->get('_firewall_context'))), -1)[0];
The difference is that $firewallName will always be a string (which may be empty).
Also, please note that this answer (like #Adambean's) doesn't work for a firewall with a dot in its name.