[tor-bugs] #25599 [Obfuscation/Snowflake]: SOCKS4 failure message

Tor Bug Tracker & Wiki blackhole at torproject.org
Thu Mar 22 18:10:09 UTC 2018

#25599: SOCKS4 failure message
     Reporter:  arlolra                |      Owner:  (none)
         Type:  defect                 |     Status:  new
     Priority:  Medium                 |  Milestone:
    Component:  Obfuscation/Snowflake  |    Version:
     Severity:  Normal                 |   Keywords:
Actual Points:                         |  Parent ID:
       Points:                         |   Reviewer:
      Sponsor:                         |
 > Sometimes, Tor emits this:
 >> [warn] The connection to the SOCKS4 proxy server at$someport
 just failed. Make sure that the proxy >> server is up and running.
 > At which point no more handlers fire. Looking at the Tor source, this
 happens when SOCKS is "marked for close". This is inconvenient because
 then the client must be restarted for connectivity to work again.


 > Are you still experiencing this? Is it reproducible?


 > I experienced this sporadically while working on multiplexing. Right now
 it seems fine though.
 > It seems to be 100% reproducible if I explicitly readPipe.Close() on the
 webrtc peer. My guess is that when the copyLoop sends an error or EOF at
 SOCKS, Tor interprets that as an unexpected situation, "marks for close /
 deletion" and so the SOCKS4 server disappears.
 > Maybe there's a way to account for this in main() to also be able to
 recover the initial SOCKS listening? (this is not in the goptlib example,
 which we were originally based on) When the SOCKS connection is closed
 normally in handler, there's doesn't seem to be an issue.
 > But, should test more possibilities / longer times.

 \\ Migrated from https://github.com/keroserene/snowflake/issues/32

Ticket URL: <https://trac.torproject.org/projects/tor/ticket/25599>
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