[tor-bugs] #22934 [Core Tor/Tor]: PADDING cells can't be sent immediately after a VERSIONS cell

[Tor Bug Tracker & Wiki]

#22934: PADDING cells can't be sent immediately after a VERSIONS cell
------------------------------+---------------------------------
     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, tor-relay
Actual Points:                |  Parent ID:  #18856
       Points:  0.5           |   Reviewer:
      Sponsor:                |
------------------------------+---------------------------------
 When I send a VERSIONS cell and a PADDING cell in the same socket write,
 Tor 0.3.0.9 closes the connection:
 {{{
 Jul 15 19:55:43.000 [info] channel_register: Channel 0x7f848276e300
 (global ID 207) in state opening (1) registered with no identity digest
 Jul 15 19:55:43.000 [info] channel_tls_process_versions_cell: Negotiated
 version 3 with [scrubbed]:58001; Sending cells: VERSIONS CERTS
 AUTH_CHALLENGE NETINFO
 Jul 15 19:55:43.000 [info] channel_tls_handle_cell: Received unexpected
 cell command 0 in chan state opening / conn state handshaking (Tor, v3
 handshake); closing the connection.
 Jul 15 19:55:43.000 [info] conn_close_if_marked: Conn (addr [scrubbed], fd
 9, type OR, state 7) marked, but wants to flush 2033 bytes. (Marked at
 src/or/connection_or.c:1338)
 Jul 15 19:55:43.000 [info] conn_close_if_marked: We stalled too much while
 trying to write 2033 bytes to address [scrubbed].  If this happens a lot,
 either something is wrong with your network connection, or something is
 wrong with theirs. (fd 9, type OR, state 7, marked at
 src/or/connection_or.c:1338).
 }}}
 It doesn't matter if I send a VPADDING cell before the padding cell.

 But the tor spec says:
 {{{
 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.
 }}}
 https://gitweb.torproject.org/torspec.git/tree/tor-spec.txt#n482

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/22934>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online