[tor-bugs] #17945 [Core Tor/Tor]: Stop Tor2Web connecting to (Rendezvous) Single Onion Services

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#17945: Stop Tor2Web connecting to (Rendezvous) Single Onion Services
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 Reporter:  teor                                 |          Owner:  dgoulet
     Type:  enhancement                          |         Status:
                                                 |  needs_revision
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  0.3.3.x-final
Component:  Core Tor/Tor                         |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  tor2web, tor-hs, 029-proposed, 029   |  Actual Points:
  -teor-no, needs-design, needs-proposal-maybe,  |
  single-onion, review-group-33                  |
Parent ID:  #24962                               |         Points:  5
 Reviewer:  asn, teor                            |        Sponsor:
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Changes (by teor):

 * status:  needs_review => needs_revision


Comment:

 Good catch!

 There should be no way we can get to this code without a p_chan, because
 both circuits needed a p_chan at some point in the past to establish a
 rendezvous. But we could accidentally add a bug like this in future.

 If either circuit doesn't have a p_chan (because it's just been closed),
 the rendezvous should fail.
 So we should do the p_chan check and fail, because channel_is_client()
 hard asserts on NULL channels.

 Do you think we should BUG() if either p_chan is NULL?
 I'm not sure, because channels can close by themselves, and I'm not sure
 if they clean up all their circuits straight away.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/17945#comment:47>
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