[tor-bugs] #31115 [Core Tor/Tor]: tor returns first 4 bytes of IPv6 address only when using SOCKS command "F0"

Tue Jul 9 11:29:03 UTC 2019

#31115: tor returns first 4 bytes of IPv6 address only when using SOCKS command
"F0"
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 Reporter:  cypherpunks   |          Owner:  (none)
     Type:  defect        |         Status:  new
 Priority:  Medium        |      Component:  Core Tor/Tor
  Version:  Tor: 0.3.5.8  |       Severity:  Normal
 Keywords:                |  Actual Points:
Parent ID:                |         Points:
 Reviewer:                |        Sponsor:
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 Context:

 Tor has a custom extension to the SOCKS protocol, defined in:
 https://gitweb.torproject.org/torspec.git/tree/socks-extensions.txt#n48

 that allows resolving hostnames.

 exitmap makes use of this SOCKS extension.

 When the answer is an IPv6 address (ATYP=04) only the first 4 bytes are
 contained in the response instead of the entire IPv6 address.

 Expected behavior: The entire IPv6 address should be in the response (128
 bit instead of 32 bit).

 https://lists.torproject.org/pipermail/tor-dev/2019-July/013931.html

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/31115>
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