On 1/15/14 1:08 PM, Karsten Loesing wrote:
On 1/6/14 7:55 PM, Nick Mathewson wrote:
On Tue, Dec 24, 2013 at 3:55 AM, Karsten Loesing karsten@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 ?
sure.
Okay, starting a patch with proposal 147 tweaks and changing this URL as suggested.
- 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.
Added to the proposal.
- 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.
True. Added as two comments to the proposal.
- 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.
Added.
- 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.
Added as comments.
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.
I talked to Roger on IRC, and here's why this proposal may indeed be overkill:
As of January 2013, there is only a single version 3 directory authority left that serves version 2 statuses: dizum. moria1 and tor26 have been rejecting version 2 requests for a long time, and it's mostly an oversight that dizum still serves them. The other six authorities have never generated version 2 statuses for others to be used as pre-voting opinions. So, it's basically not true that version 2 statuses are required for the version 3 protocol to work properly.
Here's a possible way to move this forward.
- Please review and merge my prop147tweaks branch that contains tweaks
from our discussion above, regardless of whether this proposal will be implemented or not.
- I'm going to run a quick analysis of archived vote documents to see
how much authorities would have benefited from the others' votes before generating their own votes.
From January 1 to 7, 2014, only 0.4 relays on average were not included
in a consensus because they were listed in less than 5 votes. These 0.4 relays could probably have been included with pre-voting opinions.
(Here's how I found out: extract the votes-2014-01.tar.bz2 tarball, run `grep -R "^r " 0[1-7] | cut -c 4-22,112- | cut -d" " -f1,3 | sort | uniq -c | sort | grep " [1-4] " | wc -l`, result is 63, divide by 7*24 published consensuses, obtain 0.375 as end result.)
- I'm going to ask Alex to disable version 2 statuses on dizum using
DisableV2DirectoryInfo_ 1 to see what that does to the network. We should probably finish the 2048 bits RSA keys upgrade first before changing yet another variable.
- If there's no convincing argument to implement opinion documents, we
close this proposal as rejected.
What do you think?
All the best, Karsten