[tor-bugs] #29990 [Core Tor/Tor]: Handle zero monotonic time differences in the circuit padding code

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#29990: Handle zero monotonic time differences in the circuit padding code
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 Reporter:  teor                                 |          Owner:  (none)
     Type:  defect                               |         Status:  new
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  0.4.1.x-final
Component:  Core Tor/Tor                         |        Version:  Tor:
                                                 |  unspecified
 Severity:  Normal                               |     Resolution:
 Keywords:  wtf-pad, tor-relay, tor-cell,        |  Actual Points:
  padding, 041-must                              |
Parent ID:  #29500                               |         Points:  2
 Reviewer:                                       |        Sponsor:
                                                 |  Sponsor2
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Comment (by mikeperry):

 Aha, I think I found it! Our mocking forces us to call monotime_init()
 *before* we set the mocked time value. monotime_init() thus stores the
 first ratchet value at whatever the platform is at, and then we set fake
 mocked time to some later value.

 If monotime_init() gets a value from the host that is **greater** than
 what we choose to mock time at for our unittests, all subsequent
 monotime_abosolute() calls return zero.

 So, the right way to fix all of this mess is to either fix our mocking to
 allow us to call monotime_init() with a mocked time, or just always set
 our mocked time to some time after whatever monotime_init() stored.

 I am going to attempt the later, to see if it fixes whatever hackintosh VM
 is involved here (I don't have one of those).

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/29990#comment:6>
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