[tor-bugs] #25568 [Core Tor/Tor]: hs: Lookup failure cache when introducing to an intro point

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#25568: hs: Lookup failure cache when introducing to an intro point
-------------------------------------------------+-------------------------
 Reporter:  dgoulet                              |          Owner:  neel
     Type:  defect                               |         Status:
                                                 |  needs_revision
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  unspecified
Component:  Core Tor/Tor                         |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  security, tor-hs,                    |  Actual Points:
  034-triage-20180328, 034-removed-20180328      |
Parent ID:                                       |         Points:
 Reviewer:  dgoulet                              |        Sponsor:
-------------------------------------------------+-------------------------
Changes (by dgoulet):

 * status:  needs_review => needs_revision


Comment:

 Replying to [comment:16 neel]:
 > I have a new PR on a different branch here:
 https://github.com/torproject/tor/pull/1161

 I don't think this will work as expected.

 First, I believe this is only a v2 problem because in v3, when picking an
 intro point from the descriptor, we do _not_ pick unusable IPs.

 Where with v2, this check is not done when picking the intro point but
 rather when sending the INTRO cell. Problem lies with
 `rend_client_any_intro_points_usable()` I believe because it select a new
 intro point and only checks at `ip->timed_out` and not the failure cache.

 Once a NACK arrives, the v2 code actually removes the intro point from the
 parsed descriptor so we can't even check the IP object for an error. We
 really need to query the failure cache.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/25568#comment:17>
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