[tor-bugs] #27471 [Core Tor/Tor]: HS intermittently fails: Non-fatal assertion failed in send_introduce1

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#27471: HS intermittently fails: Non-fatal assertion failed in send_introduce1
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 Reporter:  tgragnato            |          Owner:  (none)
     Type:  defect               |         Status:  new
 Priority:  Very High            |      Milestone:  Tor: 0.3.5.x-final
Component:  Core Tor/Tor         |        Version:  Tor: 0.3.4.7-rc
 Severity:  Minor                |     Resolution:
 Keywords:  tor-hs, regression?  |  Actual Points:
Parent ID:                       |         Points:
 Reviewer:                       |        Sponsor:
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Comment (by dgoulet):

 One theory right now that seems to be plausible but kind of a corner case:

 1) When we lookup the intro circuit in
 `connection_ap_handshake_attach_circuit()`, we go over all circuits and
 try to figure out which is the best for this connection. We use
 `circuit_matches_with_rend_stream()` to check if the circuit is acceptable
 by comparing the .onion requested by the SOCKS connection with the .onion
 on the intro circuit (`hs_ident`).

 What if we had a set of intro points that aren't used by the service
 anymore so the client got NACK on all of them, then fetches a new
 descriptor with new intro points, then a new intro circuit is launched and
 finally the lookup function when the RP acked selected an old intro
 circuits but still for the same service.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/27471#comment:2>
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