[tor-bugs] #32264 [Metrics/Exit Scanner]: MS: Perform fetches of check.tpo in an exitmap plugin

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#32264: MS: Perform fetches of check.tpo in an exitmap plugin
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 Reporter:  irl                   |          Owner:  irl
     Type:  task                  |         Status:  needs_review
 Priority:  Medium                |      Milestone:
Component:  Metrics/Exit Scanner  |        Version:
 Severity:  Normal                |     Resolution:
 Keywords:                        |  Actual Points:
Parent ID:  #29654                |         Points:
 Reviewer:  karsten               |        Sponsor:
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Changes (by irl):

 * status:  accepted => needs_review
 * reviewer:   => karsten


Comment:

 https://github.com/irl/exitmap/commit/fb0e74e6f818aa368f5119f9499d84019ab6c52e
 is the commit, but really it is just adding a more verbose log message at
 a higher log level on line 73.

 I think the big changes between this and the current system are:

 * things will be scanned more often (with the current network we can check
 every relay every 50 minutes or so)
 * there are no retries (maybe doesn't matter with the more frequent
 scanning, i'm not sure if the old system had retries)
 * the scanner is stateless, tor holds the state, it's the job of the
 merger script in #32265 to carry forward old results
 * the scanner doesn't output a published or last

 Exit policies are checked to see if it's possible to exit to
 check.torproject.org. If it's not possible, no attempt will be made.

 No descriptor information other than the fingerprint is in the output.
 This means exit lists don't contain the OR IP address. I /think/
 Exonerator gets this from parsing server descriptors anyway.

 Review is more for the concept than the code.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/32264#comment:3>
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