[tor-dev] Review of Proposal 147: Eliminate the need for v2 directories in generating v3 directories (was: Tor proposal status (December 2013))

Nick Mathewson nickm at alum.mit.edu
Mon Jan 6 18:55:31 UTC 2014

On Tue, Dec 24, 2013 at 3:55 AM, Karsten Loesing <karsten at torproject.org> wrote:
> On 12/17/13 10:31 PM, Nick Mathewson wrote:
>> 147  Eliminate the need for v2 directories in generating v3 directories
>>      This proposal explains a way that we can phase out the
>>      vestigial use of v2 directory documents in keeping authorities
>>      well-informed enough to generating the v3 consensus.  It's
>>      still correct; somebody should implement it before the v2
>>      directory code rots any further. (5/2011)
> This proposal looks plausible to me.  Some minor remarks:
> - The proposal suggests that authorities send an opinion document to the
> other authorities "at the regular vote upload URL".  URLs are cheap, why
> not use a different URL to keep things separated, e.g., /tor/post/opinion ?


> - Should dir-spec.txt suggest a timing for pushing-and-pulling opinion
> documents?  Authorities could send their opinions at :45:00 and fetch
> missing opinions at :47:30.  This could be defined by a new
> OpinionSeconds part contained in "voting-delay" lines.  This would be a
> SHOULD requirement, not a MUST requirement.

This is plausible.

> - The proposal doesn't say what lines must be contained in opinion
> documents.  It seems that an authority that parses an opinion document
> is only interested in a) relay fingerprint, b) descriptor publication
> time, and c) descriptor digest; unless there's more information that
> helps authorities decide whether "they might accept" a descriptor.  If
> not, opinion documents only need to contain a small subset of headers
> and all the "r" lines that would be contained in a later vote.

This also seems okay.  It would however mean that we can't use the
same parsing logic as we use for regular votes.

> - The proposal doesn't explicitly say this, so just to be sure: when an
> authority finds that it's missing a router descriptor that it then
> downloads, it also downloads the corresponding extra-info descriptor
> afterwards, right?

I suppose it should.

> - Another thing that is left implicit in the proposal: the opinion
> document will always contain the valid-after time of the *next*
> consensus.  Well, the URL /tor/status-vote/next/opinion implies that,
> but maybe we should explicitly mention this in dir-spec.txt.

Hm. maybe valid-after and valid-until should just get ignored on
opinions. Or omitted.

Also, ISTR that Roger told me that this whole proposal didn't actually
seem to be necessary in practice. I wish I could remember the
rationale, though.


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