main.c

关于tor匿名通信的源代码

    } else {
      or_connection_t *best =
        connection_or_get_by_identity_digest(or_conn->identity_digest);
      if (best && best != or_conn &&
          (conn->state == OR_CONN_STATE_OPEN ||
           now > conn->timestamp_created + TLS_HANDSHAKE_TIMEOUT)) {
          /* We only mark as obsolete connections that already are in
           * OR_CONN_STATE_OPEN, i.e. that have finished their TLS handshaking.
           * This is necessary because authorities judge whether a router is
           * reachable based on whether they were able to TLS handshake with it
           * recently.  Without this check we would expire connections too
           * early for router->last_reachable to be updated.
           */
        log_info(LD_OR,
                 "Marking duplicate conn to %s:%d obsolete "
                 "(fd %d, %d secs old).",
                 conn->address, conn->port, conn->s,
                 (int)(now - conn->timestamp_created));
        conn->or_is_obsolete = 1;
      }
    }
  }

  if (conn->or_is_obsolete && !or_conn->n_circuits) {
    /* no unmarked circs -- mark it now */
    log_info(LD_OR,
             "Expiring non-used OR connection to fd %d (%s:%d) [Obsolete].",
             conn->s, conn->address, conn->port);
    connection_mark_for_close(conn);
    conn->hold_open_until_flushed = 1;
    return;
  }

  /* If we haven't written to an OR connection for a while, then either nuke
     the connection or send a keepalive, depending. */
  if (now >= conn->timestamp_lastwritten + options->KeepalivePeriod) {
    routerinfo_t *router = router_get_by_digest(or_conn->identity_digest);
    int maxCircuitlessPeriod = options->MaxCircuitDirtiness*3/2;
    if (!connection_state_is_open(conn)) {
      /* We never managed to actually get this connection open and happy. */
      log_info(LD_OR,"Expiring non-open OR connection to fd %d (%s:%d).",
               conn->s,conn->address, conn->port);
      connection_mark_for_close(conn);
      conn->hold_open_until_flushed = 1;
    } else if (we_are_hibernating() && !or_conn->n_circuits &&
               !buf_datalen(conn->outbuf)) {
      /* We're hibernating, there's no circuits, and nothing to flush.*/
      log_info(LD_OR,"Expiring non-used OR connection to fd %d (%s:%d) "
               "[Hibernating or exiting].",
               conn->s,conn->address, conn->port);
      connection_mark_for_close(conn);
      conn->hold_open_until_flushed = 1;
    } else if (!clique_mode(options) && !or_conn->n_circuits &&
               now >= or_conn->timestamp_last_added_nonpadding +
                                           maxCircuitlessPeriod &&
               (!router || !server_mode(options) ||
                !router_is_clique_mode(router))) {
      log_info(LD_OR,"Expiring non-used OR connection to fd %d (%s:%d) "
               "[Not in clique mode].",
               conn->s,conn->address, conn->port);
      connection_mark_for_close(conn);
      conn->hold_open_until_flushed = 1;
    } else if (
         now >= or_conn->timestamp_lastempty + options->KeepalivePeriod*10 &&
         now >= conn->timestamp_lastwritten + options->KeepalivePeriod*10) {
      log_fn(LOG_PROTOCOL_WARN,LD_PROTOCOL,
             "Expiring stuck OR connection to fd %d (%s:%d). (%d bytes to "
             "flush; %d seconds since last write)",
             conn->s, conn->address, conn->port,
             (int)buf_datalen(conn->outbuf),
             (int)(now-conn->timestamp_lastwritten));
      connection_mark_for_close(conn);
    } else if (!buf_datalen(conn->outbuf)) {
      /* either in clique mode, or we've got a circuit. send a padding cell. */
      log_fn(LOG_DEBUG,LD_OR,"Sending keepalive to (%s:%d)",
             conn->address, conn->port);
      memset(&cell,0,sizeof(cell_t));
      cell.command = CELL_PADDING;
      connection_or_write_cell_to_buf(&cell, or_conn);
    }
  }
}

/** Honor a NEWNYM request: make future requests unlinkability to past
 * requests. */
static void
signewnym_impl(time_t now)
{
  circuit_expire_all_dirty_circs();
  addressmap_clear_transient();
  time_of_last_signewnym = now;
  signewnym_is_pending = 0;
}

/** Perform regular maintenance tasks.  This function gets run once per
 * second by prepare_for_poll.
 */
static void
run_scheduled_events(time_t now)
{
  static time_t time_to_fetch_directory = 0;
  static time_t time_to_fetch_running_routers = 0;
  static time_t last_rotated_x509_certificate = 0;
  static time_t time_to_check_v3_certificate = 0;
  static time_t time_to_check_listeners = 0;
  static time_t time_to_check_descriptor = 0;
  static time_t time_to_check_ipaddress = 0;
  static time_t time_to_shrink_memory = 0;
  static time_t time_to_try_getting_descriptors = 0;
  static time_t time_to_reset_descriptor_failures = 0;
  static time_t time_to_add_entropy = 0;
  static time_t time_to_write_hs_statistics = 0;
  static time_t time_to_write_bridge_status_file = 0;
  static time_t time_to_downrate_stability = 0;
  static time_t time_to_save_stability = 0;
  static time_t time_to_clean_caches = 0;
  static time_t time_to_recheck_bandwidth = 0;
  static time_t time_to_check_for_expired_networkstatus = 0;
  or_options_t *options = get_options();
  int i;
  int have_dir_info;

  /** 0. See if we've been asked to shut down and our timeout has
   * expired; or if our bandwidth limits are exhausted and we
   * should hibernate; or if it's time to wake up from hibernation.
   */
  consider_hibernation(now);

  /* 0b. If we've deferred a signewnym, make sure it gets handled
   * eventually. */
  if (signewnym_is_pending &&
      time_of_last_signewnym + MAX_SIGNEWNYM_RATE <= now) {
    log(LOG_INFO, LD_CONTROL, "Honoring delayed NEWNYM request");
    signewnym_impl(now);
  }

  /** 1a. Every MIN_ONION_KEY_LIFETIME seconds, rotate the onion keys,
   *  shut down and restart all cpuworkers, and update the directory if
   *  necessary.
   */
  if (server_mode(options) &&
      get_onion_key_set_at()+MIN_ONION_KEY_LIFETIME < now) {
    log_info(LD_GENERAL,"Rotating onion key.");
    rotate_onion_key();
    cpuworkers_rotate();
    if (router_rebuild_descriptor(1)<0) {
      log_info(LD_CONFIG, "Couldn't rebuild router descriptor");
    }
    if (advertised_server_mode())
      router_upload_dir_desc_to_dirservers(0);
  }

  if (time_to_try_getting_descriptors < now) {
    update_router_descriptor_downloads(now);
    update_extrainfo_downloads(now);
    if (options->UseBridges)
      fetch_bridge_descriptors(now);
    if (router_have_minimum_dir_info())
      time_to_try_getting_descriptors = now + LAZY_DESCRIPTOR_RETRY_INTERVAL;
    else
      time_to_try_getting_descriptors = now + GREEDY_DESCRIPTOR_RETRY_INTERVAL;
  }

  if (time_to_reset_descriptor_failures < now) {
    router_reset_descriptor_download_failures();
    time_to_reset_descriptor_failures =
      now + DESCRIPTOR_FAILURE_RESET_INTERVAL;
  }

  /** 1b. Every MAX_SSL_KEY_LIFETIME seconds, we change our TLS context. */
  if (!last_rotated_x509_certificate)
    last_rotated_x509_certificate = now;
  if (last_rotated_x509_certificate+MAX_SSL_KEY_LIFETIME < now) {
    log_info(LD_GENERAL,"Rotating tls context.");
    if (tor_tls_context_new(get_identity_key(), MAX_SSL_KEY_LIFETIME) < 0) {
      log_warn(LD_BUG, "Error reinitializing TLS context");
      /* XXX is it a bug here, that we just keep going? -RD */
    }
    last_rotated_x509_certificate = now;
    /* We also make sure to rotate the TLS connections themselves if they've
     * been up for too long -- but that's done via or_is_obsolete in
     * connection_run_housekeeping() above. */
  }

  if (time_to_add_entropy < now) {
    if (time_to_add_entropy) {
      /* We already seeded once, so don't die on failure. */
      crypto_seed_rng(0);
    }
/** How often do we add more entropy to OpenSSL's RNG pool? */
#define ENTROPY_INTERVAL (60*60)
    time_to_add_entropy = now + ENTROPY_INTERVAL;
  }

  /** 1c. If we have to change the accounting interval or record
   * bandwidth used in this accounting interval, do so. */
  if (accounting_is_enabled(options))
    accounting_run_housekeeping(now);

  if (now % 10 == 0 && (authdir_mode_tests_reachability(options)) &&
      !we_are_hibernating()) {
    /* try to determine reachability of the other Tor relays */
    dirserv_test_reachability(now, 0);
  }

  /** 1d. Periodically, we discount older stability information so that new
   * stability info counts more, and save the stability information to disk as
   * appropriate. */
  if (time_to_downrate_stability < now)
    time_to_downrate_stability = rep_hist_downrate_old_runs(now);
  if (authdir_mode_tests_reachability(options)) {
    if (time_to_save_stability < now) {
      if (time_to_save_stability && rep_hist_record_mtbf_data()<0) {
        log_warn(LD_GENERAL, "Couldn't store mtbf data.");
      }
#define SAVE_STABILITY_INTERVAL (30*60)
      time_to_save_stability = now + SAVE_STABILITY_INTERVAL;
    }
  }

  /* 1e. Periodicaly, if we're a v3 authority, we check whether our cert is
   * close to expiring and warn the admin if it is. */
  if (time_to_check_v3_certificate < now) {
    v3_authority_check_key_expiry();
#define CHECK_V3_CERTIFICATE_INTERVAL (5*60)
    time_to_check_v3_certificate = now + CHECK_V3_CERTIFICATE_INTERVAL;
  }

  /* 1f. Check whether our networkstatus has expired.
   */
  if (time_to_check_for_expired_networkstatus < now) {
    networkstatus_t *ns = networkstatus_get_latest_consensus();
    /*XXXX020 this value needs to be the same as REASONABLY_LIVE_TIME in
     * networkstatus_get_reasonably_live_consensus(), but that value is way
     * way too high.  Arma: is the bridge issue there resolved yet? -NM */
#define NS_EXPIRY_SLOP (24*60*60)
    if (ns && ns->valid_until < now+NS_EXPIRY_SLOP &&
        router_have_minimum_dir_info()) {
      router_dir_info_changed();
    }
#define CHECK_EXPIRED_NS_INTERVAL (2*60)
    time_to_check_for_expired_networkstatus = now + CHECK_EXPIRED_NS_INTERVAL;
  }

  /** 2. Periodically, we consider getting a new directory, getting a
   * new running-routers list, and/or force-uploading our descriptor
   * (if we've passed our internal checks). */
  if (time_to_fetch_directory < now) {
    /* Only caches actually need to fetch v1 directories now. */
    if (directory_fetches_dir_info_early(options) &&
        !authdir_mode_v1(options) && any_trusted_dir_is_v1_authority() &&
        !should_delay_dir_fetches(options))
      directory_get_from_dirserver(DIR_PURPOSE_FETCH_DIR,
                                   ROUTER_PURPOSE_GENERAL, NULL, 1);
/** How often do we (as a cache) fetch a new V1 directory? */
#define V1_DIR_FETCH_PERIOD (12*60*60)
    time_to_fetch_directory = now + V1_DIR_FETCH_PERIOD;
  }

  /* Caches need to fetch running_routers; directory clients don't. */
  if (time_to_fetch_running_routers < now) {
    if (directory_fetches_dir_info_early(options) &&
        !authdir_mode_v1(options) && any_trusted_dir_is_v1_authority() &&
        !should_delay_dir_fetches(options))
      directory_get_from_dirserver(DIR_PURPOSE_FETCH_RUNNING_LIST,
                                   ROUTER_PURPOSE_GENERAL, NULL, 1);
/** How often do we (as a cache) fetch a new V1 runningrouters document? */
#define V1_RUNNINGROUTERS_FETCH_PERIOD (12*60*60)
    time_to_fetch_running_routers = now + V1_RUNNINGROUTERS_FETCH_PERIOD;
  }

  /* Remove old information from rephist and the rend cache. */
  if (time_to_clean_caches < now) {
    rep_history_clean(now - options->RephistTrackTime);
    rend_cache_clean();
    rend_cache_clean_v2_descs_as_dir();
#define CLEAN_CACHES_INTERVAL (30*60)
    time_to_clean_caches = now + CLEAN_CACHES_INTERVAL;
  }

/** How often do we check whether part of our router info has changed in a way
 * that would require an upload? */
#define CHECK_DESCRIPTOR_INTERVAL (60)
/** How often do we (as a router) check whether our IP address has changed? */
#define CHECK_IPADDRESS_INTERVAL (15*60)

  /* 2b. Once per minute, regenerate and upload the descriptor if the old
   * one is inaccurate. */
  if (time_to_check_descriptor < now) {
    static int dirport_reachability_count = 0;
    time_to_check_descriptor = now + CHECK_DESCRIPTOR_INTERVAL;
    check_descriptor_bandwidth_changed(now);
    if (time_to_check_ipaddress < now) {
      time_to_check_ipaddress = now + CHECK_IPADDRESS_INTERVAL;
      check_descriptor_ipaddress_changed(now);
    }
/** If our router descriptor ever goes this long without being regenerated
 * because something changed, we force an immediate regenerate-and-upload. */
#define FORCE_REGENERATE_DESCRIPTOR_INTERVAL (18*60*60)
    mark_my_descriptor_dirty_if_older_than(
                                  now - FORCE_REGENERATE_DESCRIPTOR_INTERVAL);
    consider_publishable_server(0);
    /* also, check religiously for reachability, if it's within the first
     * 20 minutes of our uptime. */
    if (server_mode(options) &&
        (has_completed_circuit || !any_predicted_circuits(now)) &&
        !we_are_hibernating()) {
      if (stats_n_seconds_working < TIMEOUT_UNTIL_UNREACHABILITY_COMPLAINT) {
        consider_testing_reachability(1, dirport_reachability_count==0);
        if (++dirport_reachability_count > 5)
          dirport_reachability_count = 0;
      } else if (time_to_recheck_bandwidth < now) {
        /* If we haven't checked for 12 hours and our bandwidth estimate is
         * low, do another bandwidth test. This is especially important for
         * bridges, since they might go long periods without much use. */
        routerinfo_t *me = router_get_my_routerinfo();
        if (time_to_recheck_bandwidth && me &&
            me->bandwidthcapacity < me->bandwidthrate &&
            me->bandwidthcapacity < 51200) {
          reset_bandwidth_test();
        }
#define BANDWIDTH_RECHECK_INTERVAL (12*60*60)
        time_to_recheck_bandwidth = now + BANDWIDTH_RECHECK_INTERVAL;
      }
    }

    /* If any networkstatus documents are no longer recent, we need to
     * update all the descriptors' running status. */
    /* purge obsolete entries */
    networkstatus_v2_list_clean(now);
    /* Remove dead routers. */
    routerlist_remove_old_routers();

    /* Also, once per minute, check whether we want to download any
     * networkstatus documents.
     */
    update_networkstatus_downloads(now);
  }

  /** 2c. Let directory voting happen. */
  if (authdir_mode_v3(options))
    dirvote_act(options, now);

  /** 3a. Every second, we examine pending circuits and prune the
   *    ones which have been pending for more than a few seconds.
   *    We do this before step 4, so it can try building more if
   *    it's not comfortable with the number of available circuits.
   */
  circuit_expire_building(now);

  /** 3b. Also look at pending streams and prune the ones that 'began'
   *     a long time ago but haven't gotten a 'connected' yet.
   *     Do this before step 4, so we can put them back into pending
   *     state to be picked up by the new circuit.
   */
  connection_ap_expire_beginning();

  /** 3c. And expire connections that we've held open for too long.