[tor-bugs] #25423 [Core Tor/Stem]: Treat 'ExitRelay 0' as a reject-all policy

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#25423: Treat 'ExitRelay 0' as a reject-all policy
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 Reporter:  atagar         |          Owner:  dmr
     Type:  defect         |         Status:  needs_review
 Priority:  Medium         |      Milestone:
Component:  Core Tor/Stem  |        Version:
 Severity:  Normal         |     Resolution:
 Keywords:                 |  Actual Points:
Parent ID:                 |         Points:
 Reviewer:  atagar         |        Sponsor:
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Comment (by atagar):

 > 1. Failure for GETINFO exit-policy/full to return info.

 Crap. Great catch, dmr! This is a bug within tor. Mind filing a ticket for
 it?

 In the meantime I wonder if we should resurrect our old exit policy
 fetching code as a fallback...

 > 3. Fixed cache-invalidation bugs

 Good catch! Fix pushed.

 > 4. Multiple configuration changes could cause our cache to be invalid

 Another nice catch. Think I agree with meejah here. Constructing another
 ExitPolicy instance is cheap so we can be broader with invalidation.
 Change pushed so we now invalidate it with any config change.

 > 5. Additional event that can invalidate our cache

 Good idea about listening for StatusEvent events. This could also let us
 drop our CACHE_ADDRESS_FOR constant.

 > 8. Probably unnecessary use of with self._msg_lock (removed)

 Oh! Good point. Removed.

 > 9. Potentially deprecate ExitPolicy.get_config_policy() (no change made)

 Good idea. Now that we're no longer attempting to make sense of the torrc
 this function will become less and less reliable over time. Function
 deprecated.

 How does this look?

 https://gitweb.torproject.org/stem.git/commit/?id=c305b7f

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/25423#comment:11>
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