Check SecureMode in a Plack middleware

[bschmalhofer]

Currently the authentication checks are done in the interface modules and possibly in Kernel::GenericInterface::Provider. IMHO, it would be nice to refactor that into nice Plack middlewares. However, this might be a bit tricky. Therefore I propose to do a simple case in an examplar fashion. install.pl and migration.pl only check the SecureMode. Thus this case is an easy case for refactoring.

In order to not make otobo.psgi unmanageable, the new middleware should be a module in Kernel/System/Web/Middlewares.

[bschmalhofer]

A first test looked fine. _installer.pl could be accessed for a new installation. After calling bin/docker/quick_setup.pl access is denied. In the latter case the HTTP status is now 403.
@svenoe : Could you take a look at the PR? It is a little bit more complicated than it could be expected. The reason is that currently no middlewares can be assigned to specific interfaces. At least I didn't see an obvious way.

[bschmalhofer]

Ah, Plack expects middlewares to reside in Plack::Middleware. So the SecureMode middleware will be called Plack::Middleware::OTOBO::SecureModeAccessFilter.

The interface modules will be outfitted with the method response, thus a interface specifc Plack App will look like:

   sub {
        my ($Env) = @_;

        return Kernel::System::Web::InterfacePublic->new(
            Debug   => 0,      # pass 1 for enabling debug messages
            PSGIEnv => $Env,
        )->Response;
    };

[bschmalhofer]

A hopefully final beautification. The interface modules can inherit from Plack::Component, https://metacpan.org/pod/Plack::Component, and Response() can be renamed to call(). This would leave us with:

mount "/public.pl" => Kernel::System::Web::InterfacePublic->new()->to_app;
in otobo.psgi.

[bschmalhofer]

Looks good so far. Closing this issue.