[tor-bugs] #18548 [Tor]: Tor calling sandbox_getaddrinfo() delays bootstrap when no system DNS is available

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#18548: Tor calling sandbox_getaddrinfo() delays bootstrap when no system DNS is
available
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 Reporter:  anonym        |          Owner:
     Type:  defect        |         Status:  new
 Priority:  Medium        |      Milestone:  Tor: 0.2.8.x-final
Component:  Tor           |        Version:  Tor: 0.2.7.6
 Severity:  Normal        |     Resolution:
 Keywords:  AffectsTails  |  Actual Points:
Parent ID:                |         Points:
 Reviewer:                |        Sponsor:
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Comment (by anonym):

 Replying to [comment:1 nickm]:
 > It looks like the main culprit here is the init_addrinfo() call, which
 tries to resolve our own hostname and cache the result.  I wonder why it
 was necessary to do that.  Does anything break if you remove the body of
 init_addrinfo()?

 Doing so fixes the delay issue, as expected. I cannot see any obvious
 regressions: basic client usage still works; nothing new happened on the
 info+ level in log (I didn't check the debug level cause I don't have the
 expected patterns memorized :)). Not sure about non-client operation,
 though.

 > DNSPort doesn't have anything to do with the Tor client's use of
 getaddrinfo as far as I know.  Not sure why you're seeing that.

 Sure. What I wanted to highlight is that configuring Tor's DNSPort as the
 system resolver, which I *assume* is pretty common and one reason for
 introducing that feature in the first place, triggers the problem. Just
 ignore the part about the delay doubling; while somewhat interesting, it's
 a bit beside the point.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/18548#comment:3>
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