[tor-bugs] #21576 [Core Tor/Tor]: Bug: Assertion linked_dir_conn_base failed in connection_ap_handshake_send_begin

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#21576: Bug: Assertion linked_dir_conn_base failed in
connection_ap_handshake_send_begin
---------------------------------+------------------------------------
 Reporter:  alecmuffett          |          Owner:  teor
     Type:  defect               |         Status:  merge_ready
 Priority:  Medium               |      Milestone:  Tor: 0.3.0.x-final
Component:  Core Tor/Tor         |        Version:  Tor: 0.2.9.3-alpha
 Severity:  Normal               |     Resolution:
 Keywords:  crash, 029-backport  |  Actual Points:  0.5
Parent ID:                       |         Points:  0.2
 Reviewer:                       |        Sponsor:
---------------------------------+------------------------------------

Comment (by teor):

 Replying to [comment:7 asn]:
 > I'm a big newbie with this part of the codebase (particularly linked
 connections and how they work), but the fix looks reasonable given the
 description above, and it doesn't seem like it can make matters worse.
 >
 > I guess a side-question is whether that's the best place in the codebase
 to bail if the linked connection does not exist. Maybe we shouldn't even
 start sending the BEGIN cell if the linked conn has been teared down?

 We could do that too, but that's a separate ticket.

 We must always do the check right before we do the circuit length
 anonymity check, because we can't work out if a directory circuit needs to
 be anonymous or not without its linked directory connection.

 > Anyway, I think Nick will be better to evaluate this patch, so I'm
 marking this as `merge_ready`.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/21576#comment:8>
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