[IPA] SID allocation using DNA plugin

[Endi Sukma Dewata]

Andrew,

Attach is another patch for the other problem I found during
provisioning. The relax control wasn't defined in the list
so the ldap_encode() failed and the request was never sent
to FDS.

I also found another problem in the provisioning tool. The script
invokes post_setup() to execute additional backend-specific tasks:

    provision_backend.post_setup()

For FDS, the post_setup is configured as follows:

    result.post_setup = fds_post_setup

The fds_post_setup() is defined within provision_fds_backend()
as follows:

    def fds_post_setup(self):

The provision_fds_backend() itself is not a member function, so
the self parameter is considered a regular parameter, not a pointer
to the object, so this invocation fails because it's missing an
argument:

    provision_backend.post_setup()

I think ideally this problem should be addressed using polymorphism
instead of function pointer. So we need to create 2 subclasses of
the ProvisionBackend called OpenLDAPBackend and FDSBackend. The
base class should include an empty post_setup() and this should be
overriden in the FDSBackend. In the main code the code should
instantiate the class as follows:

    if backend_type == "fedora-ds":
        provision_backend = FDSBackend(...)

    if backend_type == "openldap":
        provision_backend = OpenLDAPBackend(...)

    provision_backend.post_setup()

We could also do this on other parts of the code to cleanly separate
FDS and OpenLDAP code. What do you think?

Thanks.

--
Endi S. Dewata