[tor-bugs] #25882 [Core Tor/Tor]: clients not detecting stale onion service introduction points

[Tor Bug Tracker & Wiki]

#25882: clients not detecting stale onion service introduction points
--------------------------+------------------------------------
 Reporter:  cypherpunks   |          Owner:  dgoulet
     Type:  defect        |         Status:  assigned
 Priority:  Medium        |      Milestone:  Tor: 0.3.4.x-final
Component:  Core Tor/Tor  |        Version:
 Severity:  Normal        |     Resolution:
 Keywords:  tor-hs        |  Actual Points:
Parent ID:  #22455        |         Points:
 Reviewer:                |        Sponsor:
--------------------------+------------------------------------

Comment (by asn):

 Replying to [comment:17 dgoulet]:
 >
 > I think, there are couple things we might want to consider.
 >
 > a. Extend the time out cutoff of an established waiting for service
 rendezvous circuit client side
 (`CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED`) so we give a bit of room to
 the service to communicate. 2 seconds timeout (in this case) is imo very
 short especially considering a popular service...
 >
 > b. Some sort of upper threshold on how many connection attempts we do to
 a service before we stop trying. For instance, we could consider that
 after 3 back and forth, we stop trying and close the SOCKS connection with
 an "Unable to connect" kind of error.
 >
 >  Right now, it will do the above dance for 120 seconds (the SOCKS port
 default timeout) so it puts pressure on the network where we could have
 stopped at 3 attempts before..
 >
 > I personally think we should maybe aim for a combination of (a) and (b).

 Approach seems reasonable but I'm not sure whether it addresses the root
 issue which is that the service has an intro circuit open to an intro
 point which it does not respond to (the client connects fine if it fetches
 a new HS desc). Do you think that's because of the small 2 second timeout,
 or could it be another bug?

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/25882#comment:18>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online