* feat(netxlite): support extracting the CNAME
Closes https://github.com/ooni/probe/issues/2225
* fix(netxlite): attempt to increase coverage and improve tests
1. dnsovergetaddrinfo: specify the behavior of a DNSResponse returned
by this file to make it line with normal responses and write unit tests
to make sure we adhere to expectations;
2. dnsoverudp: make sure we wait to deferred responses also w/o a
custom context and post on a private channel and test that;
3. utls: recognize that we can actually write a test for NetConn and
what needs to change when we'll use go1.19 by default will just be
a cast that at that point can be removed.
This diff refactors the DNSTransport model to receive in input a DNSQuery and return in output a DNSResponse.
The design of DNSQuery and DNSResponse takes into account the use case of a transport using getaddrinfo, meaning that we don't need to serialize and deserialize messages when using getaddrinfo.
The current codebase does not use a getaddrinfo transport, but I wrote one such a transport in the Websteps Winter 2021 prototype (https://github.com/bassosimone/websteps-illustrated/).
The design conversation that lead to producing this diff is https://github.com/ooni/probe/issues/2099
Previously, the DNS decoder did not check whether it was parsing
a DNS query or a DNS response, which was wrong.
As a side note, it seems I am using "reply" in the codebase instead
of "response". The latter seems correct DNS terminology.
This diff has been extracted from 9249d14f80
See https://github.com/ooni/probe/issues/2096.
This diff has been extracted from c2f7ccab0e
See https://github.com/ooni/probe/issues/2096
While there, export DecodeReply to decode a raw reply without
interpreting the Rcode or parsing the results, which seems a
nice extra feature to have to more flexibly parse DNS replies
in other parts of the codebase.
This error occurred for example when querying kazemjalali.com
in websteps measurements run from Iran.
This error is relatively uncommon, but it still makes sense to
create a specific mapping rule for it.
Originally: 4269e82fbd
See https://github.com/ooni/probe/issues/2096
When preparing a tutorial for netxlite, I figured it is easier
to tell people "hey, this is the package you should use for all
low-level networking stuff" rather than introducing people to
a set of packages working together where some piece of functionality
is here and some other piece is there.
Part of https://github.com/ooni/probe/issues/1591
