hibernate.c

关于tor匿名通信的源代码

    case UNIT_DAY:
      if (before)
        --tm.tm_mday;
      if (get_end)
        ++tm.tm_mday;
      break;
    default:
      tor_assert(0);
  }

  tm.tm_hour = cfg_start_hour;
  tm.tm_min = cfg_start_min;
  tm.tm_sec = 0;
  tm.tm_isdst = -1; /* Autodetect DST */
  return mktime(&tm);
}

/** Return the start of the accounting period containing the time
 * <b>now</b>. */
static time_t
start_of_accounting_period_containing(time_t now)
{
  return edge_of_accounting_period_containing(now, 0);
}

/** Return the start of the accounting period that comes after the one
 * containing the time <b>now</b>. */
static time_t
start_of_accounting_period_after(time_t now)
{
  return edge_of_accounting_period_containing(now, 1);
}

/** Initialize the accounting subsystem. */
void
configure_accounting(time_t now)
{
  /* Try to remember our recorded usage. */
  if (!interval_start_time)
    read_bandwidth_usage(); /* If we fail, we'll leave values at zero, and
                             * reset below.*/
  if (!interval_start_time ||
      start_of_accounting_period_after(interval_start_time) <= now) {
    /* We didn't have recorded usage, or we don't have recorded usage
     * for this interval. Start a new interval. */
    log_info(LD_ACCT, "Starting new accounting interval.");
    reset_accounting(now);
  } else if (interval_start_time ==
        start_of_accounting_period_containing(interval_start_time)) {
    log_info(LD_ACCT, "Continuing accounting interval.");
    /* We are in the interval we thought we were in. Do nothing.*/
    interval_end_time = start_of_accounting_period_after(interval_start_time);
  } else {
    log_warn(LD_ACCT,
             "Mismatched accounting interval; starting a fresh one.");
    reset_accounting(now);
  }
  accounting_set_wakeup_time();
}

/** Set expected_bandwidth_usage based on how much we sent/received
 * per minute last interval (if we were up for at least 30 minutes),
 * or based on our declared bandwidth otherwise. */
static void
update_expected_bandwidth(void)
{
  uint64_t used, expected;
  uint64_t max_configured = (get_options()->BandwidthRate * 60);

  if (n_seconds_active_in_interval < 1800) {
    /* If we haven't gotten enough data last interval, set 'expected'
     * to 0.  This will set our wakeup to the start of the interval.
     * Next interval, we'll choose our starting time based on how much
     * we sent this interval.
     */
    expected = 0;
  } else {
    used = n_bytes_written_in_interval < n_bytes_read_in_interval ?
      n_bytes_read_in_interval : n_bytes_written_in_interval;
    expected = used / (n_seconds_active_in_interval / 60);
    if (expected > max_configured)
      expected = max_configured;
  }
  expected_bandwidth_usage = expected;
}

/** Called at the start of a new accounting interval: reset our
 * expected bandwidth usage based on what happened last time, set up
 * the start and end of the interval, and clear byte/time totals.
 */
static void
reset_accounting(time_t now)
{
  log_info(LD_ACCT, "Starting new accounting interval.");
  update_expected_bandwidth();
  interval_start_time = start_of_accounting_period_containing(now);
  interval_end_time = start_of_accounting_period_after(interval_start_time);
  n_bytes_read_in_interval = 0;
  n_bytes_written_in_interval = 0;
  n_seconds_active_in_interval = 0;
}

/** Return true iff we should save our bandwidth usage to disk. */
static INLINE int
time_to_record_bandwidth_usage(time_t now)
{
  /* Note every 600 sec */
#define NOTE_INTERVAL (600)
  /* Or every 20 megabytes */
#define NOTE_BYTES 20*(1024*1024)
  static uint64_t last_read_bytes_noted = 0;
  static uint64_t last_written_bytes_noted = 0;
  static time_t last_time_noted = 0;

  if (last_time_noted + NOTE_INTERVAL <= now ||
      last_read_bytes_noted + NOTE_BYTES <= n_bytes_read_in_interval ||
      last_written_bytes_noted + NOTE_BYTES <= n_bytes_written_in_interval ||
      (interval_end_time && interval_end_time <= now)) {
    last_time_noted = now;
    last_read_bytes_noted = n_bytes_read_in_interval;
    last_written_bytes_noted = n_bytes_written_in_interval;
    return 1;
  }
  return 0;
}

/** Invoked once per second.  Checks whether it is time to hibernate,
 * record bandwidth used, etc.  */
void
accounting_run_housekeeping(time_t now)
{
  if (now >= interval_end_time) {
    configure_accounting(now);
  }
  if (time_to_record_bandwidth_usage(now)) {
    if (accounting_record_bandwidth_usage(now, get_or_state())) {
      log_warn(LD_FS, "Couldn't record bandwidth usage to disk.");
    }
  }
}

/** When we have no idea how fast we are, how long do we assume it will take
 * us to exhaust our bandwidth? */
#define GUESS_TIME_TO_USE_BANDWIDTH (24*60*60)

/** Based on our interval and our estimated bandwidth, choose a
 * deterministic (but random-ish) time to wake up. */
static void
accounting_set_wakeup_time(void)
{
  char buf[ISO_TIME_LEN+1];
  char digest[DIGEST_LEN];
  crypto_digest_env_t *d_env;
  int time_in_interval;
  uint64_t time_to_exhaust_bw;
  int time_to_consider;

  if (! identity_key_is_set()) {
    if (init_keys() < 0) {
      log_err(LD_BUG, "Error initializing keys");
      tor_assert(0);
    }
  }

  format_iso_time(buf, interval_start_time);
  crypto_pk_get_digest(get_identity_key(), digest);

  d_env = crypto_new_digest_env();
  crypto_digest_add_bytes(d_env, buf, ISO_TIME_LEN);
  crypto_digest_add_bytes(d_env, digest, DIGEST_LEN);
  crypto_digest_get_digest(d_env, digest, DIGEST_LEN);
  crypto_free_digest_env(d_env);

  if (!expected_bandwidth_usage) {
    char buf1[ISO_TIME_LEN+1];
    char buf2[ISO_TIME_LEN+1];
    format_local_iso_time(buf1, interval_start_time);
    format_local_iso_time(buf2, interval_end_time);
    time_to_exhaust_bw = GUESS_TIME_TO_USE_BANDWIDTH;
    interval_wakeup_time = interval_start_time;

    log_notice(LD_ACCT,
           "Configured hibernation.  This interval begins at %s "
           "and ends at %s.  We have no prior estimate for bandwidth, so "
           "we will start out awake and hibernate when we exhaust our quota.",
           buf1, buf2);
    return;
  }

  time_in_interval = (int)(interval_end_time - interval_start_time);

  time_to_exhaust_bw =
    (get_options()->AccountingMax/expected_bandwidth_usage)*60;
  if (time_to_exhaust_bw > TIME_MAX) {
    time_to_exhaust_bw = TIME_MAX;
    time_to_consider = 0;
  } else {
    time_to_consider = time_in_interval - (int)time_to_exhaust_bw;
  }

  if (time_to_consider<=0) {
    interval_wakeup_time = interval_start_time;
  } else {
    /* XXX can we simplify this just by picking a random (non-deterministic)
     * time to be up? If we go down and come up, then we pick a new one. Is
     * that good enough? -RD */

    /* This is not a perfectly unbiased conversion, but it is good enough:
     * in the worst case, the first half of the day is 0.06 percent likelier
     * to be chosen than the last half. */
    interval_wakeup_time = interval_start_time +
      (get_uint32(digest) % time_to_consider);

    format_iso_time(buf, interval_wakeup_time);
  }

  {
    char buf1[ISO_TIME_LEN+1];
    char buf2[ISO_TIME_LEN+1];
    char buf3[ISO_TIME_LEN+1];
    char buf4[ISO_TIME_LEN+1];
    time_t down_time;
    if (interval_wakeup_time+time_to_exhaust_bw > TIME_MAX)
      down_time = TIME_MAX;
    else
      down_time = (time_t)(interval_wakeup_time+time_to_exhaust_bw);
    if (down_time>interval_end_time)
      down_time = interval_end_time;
    format_local_iso_time(buf1, interval_start_time);
    format_local_iso_time(buf2, interval_wakeup_time);
    format_local_iso_time(buf3, down_time);
    format_local_iso_time(buf4, interval_end_time);

    log_notice(LD_ACCT,
           "Configured hibernation.  This interval began at %s; "
           "the scheduled wake-up time %s %s; "
           "we expect%s to exhaust our quota for this interval around %s; "
           "the next interval begins at %s (all times local)",
           buf1,
           time(NULL)<interval_wakeup_time?"is":"was", buf2,
           time(NULL)<down_time?"":"ed", buf3,
           buf4);
  }
}

/* This rounds 0 up to 1000, but that's actually a feature. */
#define ROUND_UP(x) (((x) + 0x3ff) & ~0x3ff)
/** Save all our bandwidth tracking information to disk. Return 0 on
 * success, -1 on failure. */
int
accounting_record_bandwidth_usage(time_t now, or_state_t *state)
{
  /* Just update the state */
  state->AccountingIntervalStart = interval_start_time;
  state->AccountingBytesReadInInterval = ROUND_UP(n_bytes_read_in_interval);
  state->AccountingBytesWrittenInInterval =
    ROUND_UP(n_bytes_written_in_interval);
  state->AccountingSecondsActive = n_seconds_active_in_interval;
  state->AccountingExpectedUsage = expected_bandwidth_usage;

  or_state_mark_dirty(state,
                      now+(get_options()->AvoidDiskWrites ? 7200 : 60));

  return 0;
}
#undef ROUND_UP

/** Read stored accounting information from disk. Return 0 on success;
 * return -1 and change nothing on failure. */
static int
read_bandwidth_usage(void)
{
  or_state_t *state = get_or_state();

  {
    char *fname = get_datadir_fname("bw_accounting");
    unlink(fname);
    tor_free(fname);
  }

  if (!state)
    return 0;

  /* Okay; it looks like the state file is more up-to-date than the
   * bw_accounting file, or the bw_accounting file is nonexistant,
   * or the bw_accounting file is corrupt.
   */
  log_info(LD_ACCT, "Reading bandwdith accounting data from state file");
  n_bytes_read_in_interval = state->AccountingBytesReadInInterval;
  n_bytes_written_in_interval = state->AccountingBytesWrittenInInterval;
  n_seconds_active_in_interval = state->AccountingSecondsActive;
  interval_start_time = state->AccountingIntervalStart;
  expected_bandwidth_usage = state->AccountingExpectedUsage;

  {
    char tbuf1[ISO_TIME_LEN+1];
    char tbuf2[ISO_TIME_LEN+1];
    format_iso_time(tbuf1, state->LastWritten);
    format_iso_time(tbuf2, state->AccountingIntervalStart);

    log_info(LD_ACCT,
       "Successfully read bandwidth accounting info from state written at %s "
       "for interval starting at %s.  We have been active for %lu seconds in "