[tor-bugs] #16971 [Tor]: Testing tor networks use external DNS

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#16971: Testing tor networks use external DNS
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     Reporter:  teor    |      Owner:
         Type:  defect  |     Status:  new
     Priority:  major   |  Milestone:  Tor: 0.2.7.x-final
    Component:  Tor     |    Version:  Tor: 0.2.7.2-alpha
   Resolution:          |   Keywords:  Post027Freeze TorCoreTeam201509
Actual Points:          |  Parent ID:
       Points:          |
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Comment (by teor):

 The first DNS connection happens approximately 90 seconds after running
 `src/test/test-network.sh --sleep 120` with the new default bridges+hs
 chutney flavour. The DNS request seems to happen regardless of chutney
 flavour, so it's coming from the authority, relay, or client code.

 I checked the following flavours:
 * bridges+hs (default)
 * basic-min
 * bridges
 * bridges+ipv6
 * hs
 * ipv6-exit-min

 The DNS request can be cancelled (by LittleSnitch) and the chutney tests
 still succeed. If the connection attempt remains blocked (the LittleSnitch
 dialog is kept open), all other network communication from tor stops. (So
 the request is happening on the main tor thread, not some other OS
 X-created thread.)

 If `--sleep` is set low enough, the entire test can run successfully, and
 the tor processes terminate, before the DNS query is even sent.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/16971#comment:1>
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