[tor-bugs] #23091 [Core Tor/Tor]: Broken condition in check_expired_networkstatus_callback()

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#23091: Broken condition in check_expired_networkstatus_callback()
------------------------------+--------------------------------
     Reporter:  dgoulet       |      Owner:
         Type:  defect        |     Status:  new
     Priority:  Medium        |  Milestone:  Tor: 0.3.2.x-final
    Component:  Core Tor/Tor  |    Version:
     Severity:  Normal        |   Keywords:
Actual Points:                |  Parent ID:
       Points:                |   Reviewer:
      Sponsor:                |
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 Turns out that this condition in `check_expired_networkstatus_callback()`:

 {{{
   if (ns && ns->valid_until < now+NS_EXPIRY_SLOP &&
       router_have_minimum_dir_info()) {
     router_dir_info_changed();
   }
 }}}

 ... is always true if we have all our needed directory info which means
 that `router_dir_info_changed()` is called every 2 minutes (the callback
 interval).

 Nick suggested that it should be `now - NS_EXPIRY_SLOP` which goes like
 this:

 If `valid_until` is 6am today, then `now - 24h` == 1pm yesterday, and
 `valid_until < (now - 24h)` is false. But at 6:01am tomorrow, `valid_until
 < now - 24h` becomes true.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/23091>
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