path: root/src/core/or/command.c

/* Copyright (c) 2001 Matej Pfajfar.
 * Copyright (c) 2001-2004, Roger Dingledine.
 * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
 * Copyright (c) 2007-2019, The Tor Project, Inc. */
/* See LICENSE for licensing information */

/**
 * \file command.c
 * \brief Functions for processing incoming cells.
 *
 * When we receive a cell from a client or a relay, it arrives on some
 * channel, and tells us what to do with it. In this module, we dispatch based
 * on the cell type using the functions command_process_cell() and
 * command_process_var_cell(), and deal with the cell accordingly.  (These
 * handlers are installed on a channel with the command_setup_channel()
 * function.)
 *
 * Channels have a chance to handle some cell types on their own before they
 * are ever passed here --- typically, they do this for cells that are
 * specific to a given channel type.  For example, in channeltls.c, the cells
 * for the initial connection handshake are handled before we get here.  (Of
 * course, the fact that there _is_ only one channel type for now means that
 * we may have gotten the factoring wrong here.)
 *
 * Handling other cell types is mainly farmed off to other modules, after
 * initial sanity-checking.  CREATE* cells are handled ultimately in onion.c,
 * CREATED* cells trigger circuit creation in circuitbuild.c, DESTROY cells
 * are handled here (since they're simple), and RELAY cells, in all their
 * complexity, are passed off to relay.c.
 **/

/* In-points to command.c:
 *
 * - command_process_cell(), called from
 *   incoming cell handlers of channel_t instances;
 *   callbacks registered in command_setup_channel(),
 *   called when channels are created in circuitbuild.c
 */
#include "core/or/or.h"
#include "app/config/config.h"
#include "core/crypto/onion_crypto.h"
#include "core/mainloop/connection.h"
#include "core/mainloop/cpuworker.h"
#include "core/or/channel.h"
#include "core/or/circuitbuild.h"
#include "core/or/circuitlist.h"
#include "core/or/command.h"
#include "core/or/connection_or.h"
#include "core/or/dos.h"
#include "core/or/onion.h"
#include "core/or/relay.h"
#include "feature/control/control.h"
#include "feature/hibernate/hibernate.h"
#include "feature/nodelist/describe.h"
#include "feature/nodelist/nodelist.h"
#include "feature/nodelist/routerlist.h"
#include "feature/relay/routermode.h"
#include "feature/stats/rephist.h"
#include "lib/crypt_ops/crypto_util.h"

#include "core/or/cell_st.h"
#include "core/or/or_circuit_st.h"
#include "core/or/origin_circuit_st.h"
#include "core/or/var_cell_st.h"

/** How many CELL_CREATE cells have we received, ever? */
uint64_t stats_n_create_cells_processed = 0;
/** How many CELL_CREATED cells have we received, ever? */
uint64_t stats_n_created_cells_processed = 0;
/** How many CELL_RELAY cells have we received, ever? */
uint64_t stats_n_relay_cells_processed = 0;
/** How many CELL_DESTROY cells have we received, ever? */
uint64_t stats_n_destroy_cells_processed = 0;

/* Handle an incoming channel */
static void command_handle_incoming_channel(channel_listener_t *listener,
                                            channel_t *chan);

/* These are the main functions for processing cells */
static void command_process_create_cell(cell_t *cell, channel_t *chan);
static void command_process_created_cell(cell_t *cell, channel_t *chan);
static void command_process_relay_cell(cell_t *cell, channel_t *chan);
static void command_process_destroy_cell(cell_t *cell, channel_t *chan);

/** Convert the cell <b>command</b> into a lower-case, human-readable
 * string. */
const char *
cell_command_to_string(uint8_t command)
{
  switch (command) {
    case CELL_PADDING: return "padding";
    case CELL_CREATE: return "create";
    case CELL_CREATED: return "created";
    case CELL_RELAY: return "relay";
    case CELL_DESTROY: return "destroy";
    case CELL_CREATE_FAST: return "create_fast";
    case CELL_CREATED_FAST: return "created_fast";
    case CELL_VERSIONS: return "versions";
    case CELL_NETINFO: return "netinfo";
    case CELL_RELAY_EARLY: return "relay_early";
    case CELL_CREATE2: return "create2";
    case CELL_CREATED2: return "created2";
    case CELL_VPADDING: return "vpadding";
    case CELL_CERTS: return "certs";
    case CELL_AUTH_CHALLENGE: return "auth_challenge";
    case CELL_AUTHENTICATE: return "authenticate";
    case CELL_AUTHORIZE: return "authorize";
    default: return "unrecognized";
  }
}

#ifdef KEEP_TIMING_STATS
/** This is a wrapper function around the actual function that processes the
 * <b>cell</b> that just arrived on <b>conn</b>. Increment <b>*time</b>
 * by the number of microseconds used by the call to <b>*func(cell, conn)</b>.
 */
static void
command_time_process_cell(cell_t *cell, channel_t *chan, int *time,
                               void (*func)(cell_t *, channel_t *))
{
  struct timeval start, end;
  long time_passed;

  tor_gettimeofday(&start);

  (*func)(cell, chan);

  tor_gettimeofday(&end);
  time_passed = tv_udiff(&start, &end) ;

  if (time_passed > 10000) { /* more than 10ms */
    log_debug(LD_OR,"That call just took %ld ms.",time_passed/1000);
  }
  if (time_passed < 0) {
    log_info(LD_GENERAL,"That call took us back in time!");
    time_passed = 0;
  }
  *time += time_passed;
}
#endif /* defined(KEEP_TIMING_STATS) */

/** Process a <b>cell</b> that was just received on <b>chan</b>. Keep internal
 * statistics about how many of each cell we've processed so far
 * this second, and the total number of microseconds it took to
 * process each type of cell.
 */
void
command_process_cell(channel_t *chan, cell_t *cell)
{
#ifdef KEEP_TIMING_STATS
  /* how many of each cell have we seen so far this second? needs better
   * name. */
  static int num_create=0, num_created=0, num_relay=0, num_destroy=0;
  /* how long has it taken to process each type of cell? */
  static int create_time=0, created_time=0, relay_time=0, destroy_time=0;
  static time_t current_second = 0; /* from previous calls to time */

  time_t now = time(NULL);

  if (now > current_second) { /* the second has rolled over */
    /* print stats */
    log_info(LD_OR,
         "At end of second: %d creates (%d ms), %d createds (%d ms), "
         "%d relays (%d ms), %d destroys (%d ms)",
         num_create, create_time/1000,
         num_created, created_time/1000,
         num_relay, relay_time/1000,
         num_destroy, destroy_time/1000);

    /* zero out stats */
    num_create = num_created = num_relay = num_destroy = 0;
    create_time = created_time = relay_time = destroy_time = 0;

    /* remember which second it is, for next time */
    current_second = now;
  }
#endif /* defined(KEEP_TIMING_STATS) */

#ifdef KEEP_TIMING_STATS
#define PROCESS_CELL(tp, cl, cn) STMT_BEGIN {                   \
    ++num ## tp;                                                \
    command_time_process_cell(cl, cn, & tp ## time ,            \
                              command_process_ ## tp ## _cell);  \
  } STMT_END
#else /* !(defined(KEEP_TIMING_STATS)) */
#define PROCESS_CELL(tp, cl, cn) command_process_ ## tp ## _cell(cl, cn)
#endif /* defined(KEEP_TIMING_STATS) */

  switch (cell->command) {
    case CELL_CREATE:
    case CELL_CREATE_FAST:
    case CELL_CREATE2:
      ++stats_n_create_cells_processed;
      PROCESS_CELL(create, cell, chan);
      break;
    case CELL_CREATED:
    case CELL_CREATED_FAST:
    case CELL_CREATED2:
      ++stats_n_created_cells_processed;
      PROCESS_CELL(created, cell, chan);
      break;
    case CELL_RELAY:
    case CELL_RELAY_EARLY:
      ++stats_n_relay_cells_processed;
      PROCESS_CELL(relay, cell, chan);
      break;
    case CELL_DESTROY:
      ++stats_n_destroy_cells_processed;
      PROCESS_CELL(destroy, cell, chan);
      break