[metrics-bugs] #33214 [Core Tor/Tor]: ConnDirectionStatistics is off by default, but most relays report it

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#33214: ConnDirectionStatistics is off by default, but most relays report it
--------------------------+------------------------------------
 Reporter:  teor          |          Owner:  (none)
     Type:  defect        |         Status:  assigned
 Priority:  Medium        |      Milestone:  Tor: 0.4.4.x-final
Component:  Core Tor/Tor  |        Version:
 Severity:  Normal        |     Resolution:
 Keywords:                |  Actual Points:
Parent ID:  #33052        |         Points:  1
 Reviewer:                |        Sponsor:  Sponsor55-can
--------------------------+------------------------------------

Comment (by nickm):

 I think we're talking about "conn-bi-direct" specifically; please let me
 know if that isn't true.

 Here's the code in router.c that reports the value in a descriptor:
 {{{
     if (options->ConnDirectionStatistics &&
         load_stats_file("stats"PATH_SEPARATOR"conn-stats",
                         "conn-bi-direct", now, &contents) > 0) {
       smartlist_add(chunks, contents);
     }
 }}}

 I see nothing in the codebase (outside of the tests) that sets
 `ConnDirectionStatistics` to true.  It seems to have worked this way since
 at least 0.2.9.

 One confusing thing about how our code works here is that
 load_stats_file() will include a conn-bi-direct line if it appears in
 _any_ stats file that it includes.  But I don't see anything else that
 includes "stats/conn-stats", and I don't see anything that writes conn-bi-
 direct anywhere else.

 I've googled `ConnDirectionStatistics 1` to see if I could find an example
 torrc that a bunch of people are using.  There are a couple of example
 torrcs there, but nothing that seems to me like a huge number of people
 would necessarily be using it.

 Do we have any observed commonalities among the relays that are or are not
 reporting this statistics?  Are any of them on relays where we know the
 operators and can ask them what they have configured and why?

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/33214#comment:2>
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