[tor-bugs] #22689 [Core Tor/Tor]: hs: Stop rend and intro points being used as single hop proxies

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#22689: hs: Stop rend and intro points being used as single hop proxies
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 Reporter:  teor          |          Owner:  dgoulet
     Type:  defect        |         Status:  needs_review
 Priority:  Medium        |      Milestone:  Tor: 0.3.3.x-final
Component:  Core Tor/Tor  |        Version:
 Severity:  Normal        |     Resolution:
 Keywords:  relay-safety  |  Actual Points:
Parent ID:  #17945        |         Points:  0.5
 Reviewer:  teor          |        Sponsor:
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Comment (by teor):

 v2 Intro:

 v2 Tor2web will extend to another intro point, and then succeed because
 it's no longer a single hop path.

 v2 Rendezvous:

 v2 single onion services retry failed rendezvous with a 3-hop path, so
 they should retry once.
 But we turned off retries to try to reduce the DDoS load.
 So I guess they will just fail.
 And then v2 Tor2web will try another rendezvous point, and eventually give
 up.
 But we turned off Tor2web at rendezvous points.

 So we should use one of these combination of rendezvous retry and Tor2web
 settings in the consensus:
 * banning Tor2web works, or
 * allowing Tor2web and at least 1 retry also works.

 But allowing Tor2web and with no retries will put extra load on the
 network from Tor2web / single onion service failures.

 v3:

 We never implemented any special retry behaviour for v3 single onion
 services, but that doesn't matter, because there is no v3 Tor2web.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/22689#comment:16>
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