[tor-bugs] #22929 [Core Tor/Tor]: What cells can be sent before a VERSIONS cell, and what is their CIRCID_LEN?

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#22929: What cells can be sent before a VERSIONS cell, and what is their
CIRCID_LEN?
------------------------------+--------------------------------
     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
Actual Points:                |  Parent ID:
       Points:                |   Reviewer:
      Sponsor:                |
------------------------------+--------------------------------
 tor-spec.txt says:
 {{{
    CIRCID_LEN is 2 for link protocol versions 1, 2, and 3.  CIRCID_LEN
    is 4 for link protocol version 4 or higher.  The VERSIONS cell itself
    always has CIRCID_LEN == 2 for backward compatibility.
 }}}

 But what is the CIRCID_LEN for early VPADDING, AUTHORIZE, or PADDING
 cells?

 {{{
    When this handshake is in use, the first cell must
    be VERSIONS, VPADDING or AUTHORIZE, and no other cell type is allowed
 to
    intervene besides those specified, except for PADDING and VPADDING
 cells.
 }}}

 Is it valid to send VPADDING, then PADDING, then VERSIONS?
 If so, what is their CIRCID_LEN?
 Which sentence prevails, the one above, or the one below?

 {{{
    Parties MUST NOT send any
    other cells on a connection until they have received a VERSIONS cell.
 }}}

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/22929>
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