[tor-bugs] #24110 [Core Tor/Tor]: NS_CONTROL_PORT formats change when using microdescriptors

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#24110: NS_CONTROL_PORT formats change when using microdescriptors
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 Reporter:  teor          |          Owner:  (none)
     Type:  defect        |         Status:  new
 Priority:  Medium        |      Milestone:  Tor: 0.3.3.x-final
Component:  Core Tor/Tor  |        Version:  Tor: 0.3.0.1-alpha
 Severity:  Normal        |     Resolution:
 Keywords:  bwauth-needs  |  Actual Points:
Parent ID:                |         Points:  1
 Reviewer:                |        Sponsor:
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Comment (by catalyst):

 Replying to [comment:9 atagar]:
 > Gotcha. So just to be clear tor does the following?
 >
 > {{{
 > if 'GETCONF FetchUselessDescriptors' == '1' or 'GETCONF
 UseMicrodescriptors' == '0'
 >   return plain router status entries for 'GETINFO ns/all'
 > else
 >   return mirodescriptor router status entries for 'GETINFO ns/all'
 > }}}
 It's not quite that.  I think it always returns NS-flavored `r` lines,
 except with truncated descriptor digests if tor is using microdescriptors.
 See [https://gitweb.torproject.org/tor.git/tree/src/or/dirserv.c#n1929
 this part] of dirserv.c, and note that any call that comes from control.c
 passes `NS_CONTROL_PORT` for `format`, so the `r` line always gets output
 in the NS flavor format (8 components including the `r`), but if tor is
 using microdescriptors, it'll be a truncated microdescriptor digest
 instead of a full descriptor digest.  It looks like
 [https://gitweb.torproject.org/stem.git/tree/stem/control.py#n1951 stem]
 doesn't check for `auto`, so it defaults to expecting the 8-component
 form, which happens to work unless someone explicitly set
 `UseMicroDescriptors=1` for some reason.

 Maybe the "right" thing to do is have the control protocol return whatever
 `r` line format corresponds to the consensus flavor it's using, but that
 might break existing applications that expect the current "wrong"
 behavior.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/24110#comment:10>
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