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

Karsten Loesing karsten at torproject.org
Tue Dec 24 08:55:00 UTC 2013

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.

- 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.

- 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?

- 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.

All the best,

P. S.: Two more to go: 164 and 177...

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