[tor-bugs] #16943 [Tor]: Implement prop250 (Random Number Generation During Tor Voting)

[Tor Bug Tracker & Wiki]

#16943: Implement prop250 (Random Number Generation During Tor Voting)
-------------------------+------------------------------------
 Reporter:  asn          |          Owner:
     Type:  enhancement  |         Status:  needs_review
 Priority:  High         |      Milestone:  Tor: 0.2.8.x-final
Component:  Tor          |        Version:
 Severity:  Normal       |     Resolution:
 Keywords:  tor-hs       |  Actual Points:
Parent ID:  #8244        |         Points:  large
  Sponsor:  SponsorR     |
-------------------------+------------------------------------

Comment (by asn):

 Replying to [comment:22 teor]:
 > Replying to [comment:21 dgoulet]:
 > > After proposal review that happened few days ago on #tor-dev, we made
 some adjustments to the specification and code.
 > >
 > > Please find the latest code here: `prop250_final_v3`
 > >
 > > Proposal 250 has been updated with the latest in torspec.git
 >
 > Code review:
 >
 > General comments:
 >
 > get_start_time_of_current_round() doesn't take
 TestingV3AuthVotingStartOffset into account. Why not use:
 > {{{
 > time_t next_start = voting_schedule.interval_starts;
 > time_t curr_start = dirvote_get_start_of_next_interval(next_start -
 interval - 1,interval,
 >                       options->TestingV3AuthVotingStartOffset);
 > }}}
 >
 > get_next_valid_after_time() duplicates code in
 dirvote_recalculate_timing().
 > Why not use `voting_schedule.interval_starts`?
 > (You'd need to make sure dirvote_recalculate_timing() had been called
 before either of these functions used `voting_schedule.interval_starts`.)
 >

 Hmm, I would like to do that but it doesn't seem so easy.
 `dirvote_recalculate_timing()`  has not been called when we call
 `state_new()`, since we call it when we boot up and we haven't voted yet
 at that point.

 I then called `dirvote_recalculate_timing()` myself and everything worked
 fine, but I'm not sure if it's actually correct. That function updates the
 global `voting_schedule` structure which is then used by other parts of
 the codebase and I'm not sure if initializing it with 'now' set to the
 next 'valid_after' would be correct here :x

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/16943#comment:24>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online