[tor-bugs] #21293 [Core Tor/Tor]: circuit_receive_relay_cell(): Bug: relay crypt failed. Dropping connection.

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#21293: circuit_receive_relay_cell(): Bug: relay crypt failed. Dropping connection.
--------------------------------+------------------------------------
 Reporter:  s7r                 |          Owner:
     Type:  defect              |         Status:  new
 Priority:  Medium              |      Milestone:  Tor: 0.3.1.x-final
Component:  Core Tor/Tor        |        Version:  Tor: 0.3.0.1-alpha
 Severity:  Normal              |     Resolution:
 Keywords:  tor-hs, tor-client  |  Actual Points:
Parent ID:                      |         Points:
 Reviewer:                      |        Sponsor:
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Comment (by arma):

 There are failure cases of relay_crypt() that indicate bugs:

 * whenever relay_crypt_one_payload() fails

 And there are failure cases of relay_crypt() that indicate that somebody
 out there on the Internet isn't behaving as expected:

 {{{
       if (thishop->state != CPATH_STATE_OPEN) {
         log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
                "Relay cell before first created cell? Closing.");
         return -1;
       }
 }}}
 which I can trigger by sending a relay data cell in response to a relay
 extend request

 and
 {{{
       log_fn(LOG_PROTOCOL_WARN, LD_OR,
              "Incoming cell at client not recognized. Closing.");
       return -1;
 }}}
 which I can trigger by sending a relay data cell with a non-zero
 'recognized' field.

 I guess there is the question here of whether we should let the user know
 that something weird is going on, but I think the right answer is probably
 to change the outer warn from "bug warn omg" to log_protocol_warn and move
 on with our lives.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/21293#comment:1>
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