Fixed rebinding protection bug when using forwarder setups

Fixed rebinding protection bug when using forwarder setups

BIND wasn't honoring option "deny-answer-aliases" when configured to
forward queries.

Before the fix it was possible for nameservers listed in "forwarders"
option to return CNAME answers pointing to unrelated domains of the
original query, which could be used as a vector for rebinding attacks.

The fix ensures that BIND apply filters even if configured as a forwarder
instance.

(cherry picked from commit af6a4de3d5ad6c1967173facf366e6c86b3ffc28)