[tor-bugs] #14219 [Tor]: Visiting a down hidden service that was recently up results in many hsdesc fetches

[Tor Bug Tracker & Wiki]

#14219: Visiting a down hidden service that was recently up results in many hsdesc
fetches
------------------------+------------------------------
     Reporter:  arma    |      Owner:
         Type:  defect  |     Status:  new
     Priority:  normal  |  Milestone:  Tor: 0.2.???
    Component:  Tor     |    Version:
   Resolution:          |   Keywords:  SponsorR, tor-hs
Actual Points:          |  Parent ID:
       Points:          |
------------------------+------------------------------

Comment (by arma):

 Found it!

 The issue is that there are actually two copies of the hsdesc that are
 published -- one for each replica. So when I fetch the descriptor the
 first time, I get, say, the one that starts with
 {{{
 rendezvous-service-descriptor blwd4dzs2mnncf4wtc3bpv6pljwx5awb
 }}}
 Then when I try all those intro points and give up, I get another one, and
 I get, say,
 {{{
 rendezvous-service-descriptor b2szzssgq53trigyvau654eqr4k6w756
 }}}
 Then my third fetch got me
 {{{
 rendezvous-service-descriptor blwd4dzs2mnncf4wtc3bpv6pljwx5awb
 }}}
 Then my fourth fetch was
 {{{
 rendezvous-service-descriptor blwd4dzs2mnncf4wtc3bpv6pljwx5awb
 }}}
 and at that point it failed the hs request.

 So that's why it's probabilistic -- you keep fetching until you flip heads
 (without replacement) twice in a row!

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/14219#comment:1>
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