[tor-bugs] #22937 [Core Tor/Tor]: Clarify how resolved values are encoded in cells

Tor Bug Tracker & Wiki blackhole at torproject.org
Sat Jul 15 11:56:59 UTC 2017


#22937: Clarify how resolved values are encoded in cells
------------------------------+--------------------------------
     Reporter:  teor          |      Owner:
         Type:  defect        |     Status:  new
     Priority:  Medium        |  Milestone:  Tor: 0.3.2.x-final
    Component:  Core Tor/Tor  |    Version:
     Severity:  Normal        |   Keywords:  tor-spec easy doc
Actual Points:                |  Parent ID:  #18856
       Points:                |   Reviewer:
      Sponsor:                |
------------------------------+--------------------------------
 T1. Is length 0 for error types?
 T2. IPv4 and IPv6 addresses are in network byte order
 T3. Hostnames are in standard DNS order (we might not need to say this)
 T4. TTLs are left out in NETINFO cells

 {{{
    To find the address associated with a hostname, the OP sends a
    RELAY_RESOLVE cell containing the hostname to be resolved with a NUL
    terminating byte. (For a reverse lookup, the OP sends a RELAY_RESOLVE
    cell containing an in-addr.arpa address.) The OR replies with a
    RELAY_RESOLVED cell containing any number of answers. Each answer is
    of the form:

        Type   (1 octet)
        Length (1 octet)
        Value  (variable-width)
        TTL    (4 octets)
    "Length" is the length of the Value field.
    "Type" is one of:
       0x00 -- Hostname
       0x04 -- IPv4 address
       0x06 -- IPv6 address
       0xF0 -- Error, transient
       0xF1 -- Error, nontransient

     If any answer has a type of 'Error', then no other answer may be
 given.

     For backward compatibility, if there are any IPv4 answers, one of
 those
     must be given as the first answer.

     The RELAY_RESOLVE cell must use a nonzero, distinct streamID; the
     corresponding RELAY_RESOLVED cell must use the same streamID.  No
 stream
     is actually created by the OR when resolving the name.
 }}}

 https://gitweb.torproject.org/torspec.git/tree/tor-spec.txt#n1480

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/22937>
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