Drop DNS request for ".onion" special-use domain name #196
Description
See: https://tools.ietf.org/html/rfc7686
Name Resolution APIs and Libraries (...) MUST either respond to requests for .onion names by resolving them according to [tor-rendezvous] or by responding with NXDOMAIN.
A legacy client may inadvertently attempt to resolve a .onion name through the DNS. This causes a disclosure that the client is attempting to use Tor to reach a specific service. Malicious resolvers could be engineered to capture and record such leaks, which might have very adverse consequences for the well-being of the user. This issue is mitigated if the client's software is updated to not leak such queries or updated to support [tor-rendezvous], or if the client's DNS software is updated to drop any request to the .onion special-use domain name.