[tor-dev] GSoC: Questions on allowing for more DNS request types

Lucille Newman newmanlucy at uchicago.edu
Sun Apr 2 14:20:03 UTC 2017


I was interested in the project for allowing any kind of DNS support in Tor
for GSoC, or, since it is late for that deadline, then also otherwise.
After reading proposal 219, I have some questions.

1. A comment by NM suggests that we should specify exact behavior when
generating DNS packets (line 56). Should the DNS packets not be generated
as according to RFC 1035? Are there other things that need to be taken into
consideration here?

2. Another comment (line 63) asks whether 496 bytes is enough for the DNS
packet of a DNS_BEGIN cell. Since QNAME can be arbitrarily long, I suppose
it is possible that 496 is not enough? If this seems like a reasonable
concern, then maybe we could do a similar thing to the DNS_RESPONSE cells
with allowing multiple cells for a single question and having a flag to
indicate the last cell?

3. What would cause a DNS_BEGIN request or response to be aborted (line

4. How do we differentiate special names like .onion, .exit, .noconnect
(line 145)?

5. The comments at (lines 135-143) indicate that it might not be necessary
or practical to refuse requests that resolve to local addresses. This means
that such queries will not be sent, but an error will be returned before
sending to a DNS server?

Thanks so much.
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