[tor-bugs] #6799 [Tor]: Don't expire unused relay-to-relay TLS conns so quickly

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#6799: Don't expire unused relay-to-relay TLS conns so quickly
-------------------------+-------------------------------------------------
     Reporter:  arma     |      Owner:
         Type:  defect   |     Status:  needs_review
     Priority:  major    |  Milestone:  Tor: 0.2.5.x-final
    Component:  Tor      |    Version:
   Resolution:           |   Keywords:  tor-relay anonymity-attack
Actual Points:           |  025-triaged 024-backport andrea-review-0255
       Points:           |  Parent ID:
-------------------------+-------------------------------------------------

Comment (by nickm):

 Here's what happens right before one of those unbalanced client-side
 canonical channel expirations:

 {{{
 May 15 22:54:07.000 [debug] circuit_expire_old_circuits_clientside():
 Closing ci
 rcuit that has been unused for 3626990 msec.
 May 15 22:54:07.000 [debug] circuit_get_by_circid_channel_impl():
 circuit_get_by
 _circid_channel_impl() returning circuit 0x7f0846e25ff0 for circ_id
 2927002286,
 channel ID 19 (0x7f0846e65b20)
 May 15 22:54:07.000 [debug] circuit_get_by_circid_channel_impl():
 circuit_get_by
 _circid_channel_impl() returning circuit 0x7f0846e25ff0 for circ_id
 2927002286,
 channel ID 19 (0x7f0846e65b20)
 May 15 22:54:07.000 [debug] circuitmux_append_destroy_cell(): Cmux at
 0x7f0846e4
 b2b0 queued a destroy for circ 2927002286, cmux counter is now 1, global
 counter
  is now 1
 May 15 22:54:07.000 [debug] circuitmux_append_destroy_cell(): Primed a
 buffer.
 May 15 22:54:07.000 [debug] channel_write_packed_cell(): Writing
 packed_cell_t 0
 x7f0846e65d38 to channel 0x7f0846e65b20 with global ID 19
 May 15 22:54:07.000 [debug] circuit_get_by_circid_channel_impl():
 circuit_get_by
 _circid_channel_impl() returning circuit 0x7f0846e25ff0 for circ_id
 2927002286,
 channel ID 19 (0x7f0846e65b20)
 May 15 22:54:07.000 [debug] circuitmux_notify_xmit_destroy(): Cmux at
 0x7f0846e4b2b0 sent a destroy, cmux counter is now 0, global counter is
 now 0
 May 15 22:54:07.000 [debug] channel_send_destroy(): Sending destroy
 (circID 2927002286) on channel 0x7f0846e65b20 (global ID 19)
 May 15 22:54:07.000 [notice] Expiring non-used OR connection
 0x7f0846e28060 to fd 5 (127.0.0.1:5004) [idle 3627, timeout 1274,
 canonical=1].
 }}}

 Is it possible that when we fixed #7912, we didn't have client destroy
 cell update timestamp_last_added_nonpadding?  I'm not sure this is
 actually a bad thing.  Opened #12023 for that issue, though.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/6799#comment:17>
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