[tor-bugs] #24815 [Core Tor/Tor]: Validate shared random state dates before each voting period

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#24815: Validate shared random state dates before each voting period
------------------------------+--------------------------------
     Reporter:  teor          |      Owner:  (none)
         Type:  defect        |     Status:  new
     Priority:  Medium        |  Milestone:  Tor: 0.3.3.x-final
    Component:  Core Tor/Tor  |    Version:  Tor: 0.2.9.1-alpha
     Severity:  Normal        |   Keywords:  tor-sr, tor-ddos
Actual Points:                |  Parent ID:
       Points:  1             |   Reviewer:
      Sponsor:                |
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 When tor's clock jumps, the shared random state can get out of sync with
 the current round.

 This happens to me on a test authority on a laptop that sleeps regularly.
 But it could also happen to authorities that miss a voting round because
 they are under heavy load. (I have seen clock jumps happen on Linux and
 BSD under the recent heavy load.)

 I see this message when I restart my authority:
 {{{
 Jan 07 09:48:13.179 [info] or_state_load: Loaded state from
 "/Users/USER/tor/auth/auth-sr-3e/state"
 Jan 07 09:48:14.977 [info] disk_state_validate: SR: Disk state valid
 after/until times are invalid.
 Jan 07 09:48:14.984 [info] sr_state_update: SR: State prepared for
 upcoming voting period (2018-01-06 23:00:00). Upcoming phase is reveal
 (counters: 0 commit & 1 reveal rounds).
 Jan 07 09:48:16.026 [info] or_state_save: Saved state to
 "/Users/USER/tor/auth/auth-sr-3e/state"
 }}}

 Even though this message was logged just before I killed it:
 {{{
 Jan 07 09:47:45.328 [info] or_state_save: Saved state to
 "/Users/USER/tor/auth/auth-sr-3e/state"
 }}}

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/24815>
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