command_process_create_cell(cell_t *cell, or_connection_t *conn)
{
  or_circuit_t *circ;
  int id_is_high;

  if (we_are_hibernating()) {
    log_info(LD_OR,
             "Received create cell but we're shutting down. Sending back "
             "destroy.");
    connection_or_send_destroy(cell->circ_id, conn,
                               END_CIRC_REASON_HIBERNATING);
    return;
  }

  if (!server_mode(get_options())) {
    log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
           "Received create cell (type %d) from %s:%d, but we're a client. "
           "Sending back a destroy.",
           (int)cell->command, conn->_base.address, conn->_base.port);
    connection_or_send_destroy(cell->circ_id, conn,
                               END_CIRC_REASON_TORPROTOCOL);
    return;
  }

  /* If the high bit of the circuit ID is not as expected, close the
   * circ. */
  id_is_high = cell->circ_id & (1<<15);
  if ((id_is_high && conn->circ_id_type == CIRC_ID_TYPE_HIGHER) ||
      (!id_is_high && conn->circ_id_type == CIRC_ID_TYPE_LOWER)) {
    log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
           "Received create cell with unexpected circ_id %d. Closing.",
           cell->circ_id);
    connection_or_send_destroy(cell->circ_id, conn,
                               END_CIRC_REASON_TORPROTOCOL);
    return;
  }

  if (circuit_id_in_use_on_orconn(cell->circ_id, conn)) {
    routerinfo_t *router = router_get_by_digest(conn->identity_digest);
    log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
           "Received CREATE cell (circID %d) for known circ. "
           "Dropping (age %d).",
           cell->circ_id, (int)(time(NULL) - conn->_base.timestamp_created));
    if (router)
      log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
             "Details: nickname \"%s\", platform %s.",
             router->nickname, escaped(router->platform));
    return;
  }

  circ = or_circuit_new(cell->circ_id, conn);
  circ->_base.purpose = CIRCUIT_PURPOSE_OR;
  circuit_set_state(TO_CIRCUIT(circ), CIRCUIT_STATE_ONIONSKIN_PENDING);
  if (cell->command == CELL_CREATE) {
    char *onionskin = tor_malloc(ONIONSKIN_CHALLENGE_LEN);
    memcpy(onionskin, cell->payload, ONIONSKIN_CHALLENGE_LEN);

    /* hand it off to the cpuworkers, and then return. */
    if (assign_onionskin_to_cpuworker(NULL, circ, onionskin) < 0) {
      log_warn(LD_GENERAL,"Failed to hand off onionskin. Closing.");
      circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_INTERNAL);
      return;
    }
    log_debug(LD_OR,"success: handed off onionskin.");
  } else {
    /* This is a CREATE_FAST cell; we can handle it immediately without using
     * a CPU worker. */
    char keys[CPATH_KEY_MATERIAL_LEN];
    char reply[DIGEST_LEN*2];

    tor_assert(cell->command == CELL_CREATE_FAST);

    /* Make sure we never try to use the OR connection on which we
     * received this cell to satisfy an EXTEND request,  */
    conn->is_connection_with_client = 1;

    if (fast_server_handshake(cell->payload, (uint8_t*)reply,
                              (uint8_t*)keys, sizeof(keys))<0) {
      log_warn(LD_OR,"Failed to generate key material. Closing.");
      circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_INTERNAL);
      return;
    }
    if (onionskin_answer(circ, CELL_CREATED_FAST, reply, keys)<0) {
      log_warn(LD_OR,"Failed to reply to CREATE_FAST cell. Closing.");
      circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_INTERNAL);
      return;
    }
  }
}
Unknown