Re: [tor-bugs] #23387 [Core Tor/Tor]: prop224: HSdir index desynch between client and service (was: prop224: Time period desynch between client and service)

["Tor Bug Tracker & Wiki" <blackhole@xxxxxxxxxxxxxx>]

#23387: prop224: HSdir index desynch between client and service
-----------------------------+------------------------------------
 Reporter:  asn              |          Owner:  (none)
     Type:  defect           |         Status:  new
 Priority:  High             |      Milestone:  Tor: 0.3.2.x-final
Component:  Core Tor/Tor     |        Version:
 Severity:  Normal           |     Resolution:
 Keywords:  prop224, tor-hs  |  Actual Points:
Parent ID:                   |         Points:
 Reviewer:                   |        Sponsor:
-----------------------------+------------------------------------
Description changed by asn:

Old description:

> David found his client unable to connect to his service. Apparently, they
> compute different hsdir indices because the time period num is not
> synched:
> {{{
> service side: Sep 01 12:36:59.000 [info] hs_get_responsible_hsdirs():
> Finding responsible HSDirs for blinded key
> mCs1ObO+OmLpjYy36SWX3tv5rV9S2P6/BNo8rVjUy0g, time period number 17411 and
> for next period
> }}}
> {{{
> client side: Sep 01 08:23:34.000 [info] hs_get_responsible_hsdirs:
> Finding responsible HSDirs for blinded key
> 3vsekKmh3WYjr85reqpS6Ts2xqJxSSgZHxgX/Jp1FK0, time period number 17410 and
> for current period
> }}}
>
> Theory: We use `time(NULL)` as the time in `node_set_hsdir_index()`
> whereas we use the live consensus `valid-after` in
> `rotate_all_descriptors()`. This can cause desynch within the same tor
> instance. We should probably use the live consensus `valid-after` in all
> cases to have a common point of reference, and avoid problems with clock
> skews.

New description:

 David found his client unable to connect to his service. Apparently, they
 compute different hsdir indices, since it was 12:20UTC (non-overlap
 period) and the live consensus had valid-after at 11:00UTC (overlap
 period). Apparently something got confused.

 Theory: We use `time(NULL)` as the time in `node_set_hsdir_index()`
 whereas we use the live consensus `valid-after` in
 `rotate_all_descriptors()`. This can cause desynch within the same tor
 instance. We should probably use the live consensus `valid-after` in all
 cases to have a common point of reference, and avoid problems with clock
 skews.

--

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/23387#comment:1>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
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