hibernate.c

关于tor匿名通信的源代码

/* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
 * Copyright (c) 2007-2008, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/* $Id$ */
const char hibernate_c_id[] =
  "$Id$";

/**
 * \file hibernate.c
 * \brief Functions to close listeners, stop allowing new circuits,
 * etc in preparation for closing down or going dormant; and to track
 * bandwidth and time intervals to know when to hibernate and when to
 * stop hibernating.
 **/

/*
hibernating, phase 1:
  - send destroy in response to create cells
  - send end (policy failed) in response to begin cells
  - close an OR conn when it has no circuits

hibernating, phase 2:
  (entered when bandwidth hard limit reached)
  - close all OR/AP/exit conns)
*/

#include "or.h"

/** Possible values of hibernate_state */
typedef enum {
  /** We are running normally. */
  HIBERNATE_STATE_LIVE=1,
  /** We're trying to shut down cleanly, and we'll kill all active connections
   * at shutdown_time. */
  HIBERNATE_STATE_EXITING=2,
  /** We're running low on allocated bandwidth for this period, so we won't
   * accept any new connections. */
  HIBERNATE_STATE_LOWBANDWIDTH=3,
  /** We are hibernating, and we won't wake up till there's more bandwidth to
   * use. */
  HIBERNATE_STATE_DORMANT=4
} hibernate_state_t;

extern long stats_n_seconds_working; /* published uptime */

/** Are we currently awake, asleep, running out of bandwidth, or shutting
 * down? */
static hibernate_state_t hibernate_state = HIBERNATE_STATE_LIVE;
/** If are hibernating, when do we plan to wake up? Set to 0 if we
 * aren't hibernating. */
static time_t hibernate_end_time = 0;
/** If we are shutting down, when do we plan finally exit? Set to 0 if
 * we aren't shutting down. */
static time_t shutdown_time = 0;

/** Possible accounting periods. */
typedef enum {
  UNIT_MONTH=1, UNIT_WEEK=2, UNIT_DAY=3,
} time_unit_t;

/* Fields for accounting logic.  Accounting overview:
 *
 * Accounting is designed to ensure that no more than N bytes are sent in
 * either direction over a given interval (currently, one month, one week, or
 * one day) We could
 * try to do this by choking our bandwidth to a trickle, but that
 * would make our streams useless.  Instead, we estimate what our
 * bandwidth usage will be, and guess how long we'll be able to
 * provide that much bandwidth before hitting our limit.  We then
 * choose a random time within the accounting interval to come up (so
 * that we don't get 50 Tors running on the 1st of the month and none
 * on the 30th).
 *
 * Each interval runs as follows:
 *
 * 1. We guess our bandwidth usage, based on how much we used
 *     last time.  We choose a "wakeup time" within the interval to come up.
 * 2. Until the chosen wakeup time, we hibernate.
 * 3. We come up at the wakeup time, and provide bandwidth until we are
 *    "very close" to running out.
 * 4. Then we go into low-bandwidth mode, and stop accepting new
 *    connections, but provide bandwidth until we run out.
 * 5. Then we hibernate until the end of the interval.
 *
 * If the interval ends before we run out of bandwidth, we go back to
 * step one.
 */

/** How many bytes have we read in this accounting interval? */
static uint64_t n_bytes_read_in_interval = 0;
/** How many bytes have we written in this accounting interval? */
static uint64_t n_bytes_written_in_interval = 0;
/** How many seconds have we been running this interval? */
static uint32_t n_seconds_active_in_interval = 0;
/** When did this accounting interval start? */
static time_t interval_start_time = 0;
/** When will this accounting interval end? */
static time_t interval_end_time = 0;
/** How far into the accounting interval should we hibernate? */
static time_t interval_wakeup_time = 0;
/** How much bandwidth do we 'expect' to use per minute?  (0 if we have no
 * info from the last period.) */
static uint64_t expected_bandwidth_usage = 0;
/** What unit are we using for our accounting? */
static time_unit_t cfg_unit = UNIT_MONTH;
/** How many days,hours,minutes into each unit does our accounting interval
 * start? */
static int cfg_start_day = 0;
static int cfg_start_hour = 0;
static int cfg_start_min = 0;

static void reset_accounting(time_t now);
static int read_bandwidth_usage(void);
static time_t start_of_accounting_period_after(time_t now);
static time_t start_of_accounting_period_containing(time_t now);
static void accounting_set_wakeup_time(void);

/* ************
 * Functions for bandwidth accounting.
 * ************/

/** Configure accounting start/end time settings based on
 * options->AccountingStart.  Return 0 on success, -1 on failure. If
 * <b>validate_only</b> is true, do not change the current settings. */
int
accounting_parse_options(or_options_t *options, int validate_only)
{
  time_unit_t unit;
  int ok, idx;
  long d,h,m;
  smartlist_t *items;
  const char *v = options->AccountingStart;
  const char *s;
  char *cp;

  if (!v) {
    if (!validate_only) {
      cfg_unit = UNIT_MONTH;
      cfg_start_day = 1;
      cfg_start_hour = 0;
      cfg_start_min = 0;
    }
    return 0;
  }

  items = smartlist_create();
  smartlist_split_string(items, v, NULL,
                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK,0);
  if (smartlist_len(items)<2) {
    log_warn(LD_CONFIG, "Too few arguments to AccountingStart");
    goto err;
  }
  s = smartlist_get(items,0);
  if (0==strcasecmp(s, "month")) {
    unit = UNIT_MONTH;
  } else if (0==strcasecmp(s, "week")) {
    unit = UNIT_WEEK;
  } else if (0==strcasecmp(s, "day")) {
    unit = UNIT_DAY;
  } else {
    log_warn(LD_CONFIG,
             "Unrecognized accounting unit '%s': only 'month', 'week',"
             " and 'day' are supported.", s);
    goto err;
  }

  switch (unit) {
  case UNIT_WEEK:
    d = tor_parse_long(smartlist_get(items,1), 10, 1, 7, &ok, NULL);
    if (!ok) {
      log_warn(LD_CONFIG, "Weekly accounting must begin on a day between "
               "1 (Monday) and 7 (Sunday)");
      goto err;
    }
    break;
  case UNIT_MONTH:
    d = tor_parse_long(smartlist_get(items,1), 10, 1, 28, &ok, NULL);
    if (!ok) {
      log_warn(LD_CONFIG, "Monthly accounting must begin on a day between "
               "1 and 28");
      goto err;
    }
    break;
  case UNIT_DAY:
    d = 0;
    break;
  default:
    tor_assert(0);
  }

  idx = unit==UNIT_DAY?1:2;
  if (smartlist_len(items) != (idx+1)) {
    log_warn(LD_CONFIG,"Accounting unit '%s' requires %d argument%s.",
             s, idx, (idx>1)?"s":"");
    goto err;
  }
  s = smartlist_get(items, idx);
  h = tor_parse_long(s, 10, 0, 23, &ok, &cp);
  if (!ok) {
    log_warn(LD_CONFIG,"Accounting start time not parseable: bad hour.");
    goto err;
  }
  if (!cp || *cp!=':') {
    log_warn(LD_CONFIG,
             "Accounting start time not parseable: not in HH:MM format");
    goto err;
  }
  m = tor_parse_long(cp+1, 10, 0, 59, &ok, &cp);
  if (!ok) {
    log_warn(LD_CONFIG, "Accounting start time not parseable: bad minute");
    goto err;
  }
  if (!cp || *cp!='\0') {
    log_warn(LD_CONFIG,
             "Accounting start time not parseable: not in HH:MM format");
    goto err;
  }

  if (!validate_only) {
    cfg_unit = unit;
    cfg_start_day = (int)d;
    cfg_start_hour = (int)h;
    cfg_start_min = (int)m;
  }
  SMARTLIST_FOREACH(items, char *, item, tor_free(item));
  smartlist_free(items);
  return 0;
 err:
  SMARTLIST_FOREACH(items, char *, item, tor_free(item));
  smartlist_free(items);
  return -1;
}

/** If we want to manage the accounting system and potentially
 * hibernate, return 1, else return 0.
 */
int
accounting_is_enabled(or_options_t *options)
{
  if (options->AccountingMax)
    return 1;
  return 0;
}

/** Called from main.c to tell us that <b>seconds</b> seconds have
 * passed, <b>n_read</b> bytes have been read, and <b>n_written</b>
 * bytes have been written. */
void
accounting_add_bytes(size_t n_read, size_t n_written, int seconds)
{
  n_bytes_read_in_interval += n_read;
  n_bytes_written_in_interval += n_written;
  /* If we haven't been called in 10 seconds, we're probably jumping
   * around in time. */
  n_seconds_active_in_interval += (seconds < 10) ? seconds : 0;
}

/** If get_end, return the end of the accounting period that contains
 * the time <b>now</b>.  Else, return the start of the accounting
 * period that contains the time <b>now</b> */
static time_t
edge_of_accounting_period_containing(time_t now, int get_end)
{
  int before;
  struct tm tm;
  tor_localtime_r(&now, &tm);

  /* Set 'before' to true iff the current time is before the hh:mm
   * changeover time for today. */
  before = tm.tm_hour < cfg_start_hour ||
    (tm.tm_hour == cfg_start_hour && tm.tm_min < cfg_start_min);

  /* Dispatch by unit.  First, find the start day of the given period;
   * then, if get_end is true, increment to the end day. */
  switch (cfg_unit)
    {
    case UNIT_MONTH: {
      /* If this is before the Nth, we want the Nth of last month. */
      if (tm.tm_mday < cfg_start_day ||
          (tm.tm_mday < cfg_start_day && before)) {
        --tm.tm_mon;
      }
      /* Otherwise, the month is correct. */
      tm.tm_mday = cfg_start_day;
      if (get_end)
        ++tm.tm_mon;
      break;
    }
    case UNIT_WEEK: {
      /* What is the 'target' day of the week in struct tm format? (We
         say Sunday==7; struct tm says Sunday==0.) */
      int wday = cfg_start_day % 7;
      /* How many days do we subtract from today to get to the right day? */
      int delta = (7+tm.tm_wday-wday)%7;
      /* If we are on the right day, but the changeover hasn't happened yet,
       * then subtract a whole week. */
      if (delta == 0 && before)
        delta = 7;
      tm.tm_mday -= delta;
      if (get_end)
        tm.tm_mday += 7;
      break;
    }