This diff refactors netx and netxlite to ensure we're not using
netxlite legacy names inside of netx.
To this end, we're cheating a bit. We're exposing a new factory to
get an unwrapped stdlib resolver rather than defining a legacy name
to export the private name of the same factory.
This is actually a fine place to stop, for now, the next and
netxlite refactoring at https://github.com/ooni/probe/issues/2121.
Acknowledge that transports MAY be used in isolation (i.e., outside
of a Resolver) and add support for wrapping.
Ensure that every factory that creates an unwrapped type is named
accordingly to hopefully ensure there are no surprises.
Implement DNSTransport wrapping and use a technique similar to the
one used by Dialer to customize the DNSTransport while constructing
more complex data types (e.g., a specific resolver).
Ensure that the stdlib resolver's own "getaddrinfo" transport (1)
is wrapped and (2) could be extended during construction.
This work is part of my ongoing effort to bring to this repository
websteps-illustrated changes relative to netxlite.
Ref issue: https://github.com/ooni/probe/issues/2096
This diff modifies the system resolver to use a getaddrinf transport.
Obviously the transport is a fake, but its existence will allow us
to observe DNS events more naturally.
A lookup using the system resolver would be a ANY lookup that will
contain all the resolved IP addresses into the same response.
This change was also part of websteps-illustrated, albeit the way in
which I did it there was less clean than what we have here.
Ref issue: https://github.com/ooni/probe/issues/2096
