[tor-bugs] #26980 [Core Tor/Tor]: HSv3 descriptors rejected because of bad SRV start time computation

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#26980: HSv3 descriptors rejected because of bad SRV start time computation
-------------------------------------------------+-------------------------
 Reporter:  asn                                  |          Owner:  (none)
     Type:  defect                               |         Status:  new
 Priority:  High                                 |      Milestone:  Tor:
                                                 |  0.3.5.x-final
Component:  Core Tor/Tor                         |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  035-must regression tor-hs hsv3      |  Actual Points:
  reachability                                   |
Parent ID:                                       |         Points:
 Reviewer:                                       |        Sponsor:
-------------------------------------------------+-------------------------
Description changed by asn:

Old description:

> When we introduced #25552, we started OPE encrypting the time diff since
> the start of the SRV run. We also have some logic on which SRV period we
> should use to calculate the time diff:
> {{{
>   if (is_current) {
>     srv_start = sr_state_get_start_time_of_previous_protocol_run();
>   } else {
>     srv_start = sr_state_get_start_time_of_current_protocol_run();
>   }
> }}}
>
> There is a bug here, because when we cross from the 23:00 consensus to
> the 00:00 consensus (or the 01:00 one), the start of the SRV protocol
> changes and screws up the revision counter monotonicity.
>
> This causes one descriptor batch upload to fail.

New description:

 When we introduced #25552, we started OPE encrypting the time diff since
 the start of the SRV run. We also have some logic on which SRV period we
 should use to calculate the time diff:
 {{{
   if (is_current) {
     srv_start = sr_state_get_start_time_of_previous_protocol_run();
   } else {
     srv_start = sr_state_get_start_time_of_current_protocol_run();
   }
 }}}

 There is a bug here, because when we cross from the 23:00 consensus to the
 01:00 consensus, the start of the SRV protocol changes and screws up the
 revision counter monotonicity.

 This causes one descriptor batch upload to fail.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/26980#comment:3>
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