nmap/timing.cc

/***************************************************************************
 * timing.cc -- Functions related to computing scan timing (such as        *
 * keeping track of and adjusting smoothed round trip times, statistical   *
 * deviations, timeout values, etc.  Various user options (such as the     *
 * timing policy (-T)) also play a role in these calculations              *
 *                                                                         *
 ***********************IMPORTANT NMAP LICENSE TERMS************************
 *                                                                         *
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 * also a registered trademark of Insecure.Com LLC.  This program is free  *
 * software; you may redistribute and/or modify it under the terms of the  *
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 *                                                                         *
 ***************************************************************************/

/* $Id$ */

#include "timing.h"
#include "NmapOps.h"
#include "utils.h"

extern NmapOps o;

/* Call this function on a newly allocated struct timeout_info to
   initialize the values appropriately */
void initialize_timeout_info(struct timeout_info *to) {
  to->srtt = -1;
  to->rttvar = -1;
  to->timeout = o.initialRttTimeout() * 1000;
}

/* Adjust our timeout values based on the time the latest probe took for a 
   response.  We update our RTT averages, etc. */
void adjust_timeouts(struct timeval sent, struct timeout_info *to) {
  struct timeval received;
  gettimeofday(&received, NULL);

  adjust_timeouts2(&sent, &received, to);
  return;
}

/* Same as adjust_timeouts(), except this one allows you to specify
 the receive time too (which could be because it was received a while
 back or it could be for efficiency because the caller already knows
 the current time */
void adjust_timeouts2(const struct timeval *sent, 
		      const struct timeval *received, 
		      struct timeout_info *to) {
  long delta = 0;

  if (o.debugging > 3) {
    log_write(LOG_STDOUT, "Timeout vals: srtt: %d rttvar: %d to: %d ", to->srtt, to->rttvar, to->timeout);
  }

  delta = TIMEVAL_SUBTRACT(*received, *sent);

  /* Argh ... pcap receive time is sometimes a little off my
     getimeofday() results on various platforms :(.  So a packet may
     appear to be received as much as a hundredth of a second before
     it was sent.  So I will allow small negative RTT numbers */
  if (delta < 0 && delta > -50000) {
    if (o.debugging > 2)
      log_write(LOG_STDOUT, "Small negative delta (probably due to libpcap time / gettimeofday() discrepancy) - adjusting from %lius to %dus\n", delta, 10000);
    delta = 10000;
  }


  if (to->srtt == -1 && to->rttvar == -1) {
    /* We need to initialize the sucker ... */
    to->srtt = delta;
    to->rttvar = MAX(5000, MIN(to->srtt, 2000000));
    to->timeout = to->srtt + (to->rttvar << 2);
  }
  else {
    if (delta >= 8000000 || delta < 0) {
      if (o.verbose)
	error("%s: packet supposedly had rtt of %lu microseconds.  Ignoring time.", __func__, delta);
      return;
    }
    delta -= to->srtt;
    /* sanity check 2*/
    if (delta > 1500000 && delta > 3 * to->srtt + 2 * to->rttvar) {
      /* WANKER ALERT! */
      if (o.debugging) {
	log_write(LOG_STDOUT, "Bogus delta: %ld (srtt %d) ... ignoring\n", delta, to->srtt);
      }
      return;
    }
    to->srtt += delta >> 3;
    to->rttvar += (ABS(delta) - to->rttvar) >> 2;
    to->timeout = to->srtt + (to->rttvar << 2);  
  }
  if (to->rttvar > 2300000) {
    error("RTTVAR has grown to over 2.3 seconds, decreasing to 2.0");
    to->rttvar = 2000000;
  }
  
  /* It hurts to do this ... it really does ... but otherwise we are being
     too risky */
  to->timeout = box(o.minRttTimeout() * 1000, o.maxRttTimeout() * 1000,  
		    to->timeout);

  if (o.scan_delay)
    to->timeout = MAX((unsigned) to->timeout, o.scan_delay * 1000);

  if (o.debugging > 3) {
    log_write(LOG_STDOUT, "delta %ld ==> srtt: %d rttvar: %d to: %d\n", delta, to->srtt, to->rttvar, to->timeout);
  }

  /* if (to->srtt < 0 || to->rttvar < 0 || to->timeout < 0 || delta < -50000000 || 
      sent->tv_sec == 0 || received->tv_sec == 0 ) {
    fatal("Serious time computation problem in adjust_timeout ... received = (%ld, %ld) sent=(%ld,%ld) delta = %ld srtt = %d rttvar = %d to = %d", (long) received->tv_sec, (long)received->tv_usec, (long) sent->tv_sec, (long) sent->tv_usec, delta, to->srtt, to->rttvar, to->timeout);
  } */
}

/* Sleeps if necessary to ensure that it isn't called twice within less
   time than o.send_delay.  If it is passed a non-null tv, the POST-SLEEP
   time is recorded in it */
void enforce_scan_delay(struct timeval *tv) {
  static int init = -1;
  static struct timeval lastcall;
  struct timeval now;
  int time_diff;

  if (!o.scan_delay) {
    if (tv) gettimeofday(tv, NULL);
    return;
  }

  if (init == -1) {
    gettimeofday(&lastcall, NULL);
    init = 0;
    if (tv)
      memcpy(tv, &lastcall, sizeof(struct timeval));
    return;
  }

  gettimeofday(&now, NULL);
  time_diff = TIMEVAL_MSEC_SUBTRACT(now, lastcall);
  if (time_diff < (int) o.scan_delay) {  
    if (o.debugging > 1) {
      log_write(LOG_PLAIN, "Sleeping for %d milliseconds in %s()\n", o.scan_delay - time_diff, __func__);
    }
    usleep((o.scan_delay - time_diff) * 1000);
    gettimeofday(&lastcall, NULL);
  } else
    memcpy(&lastcall, &now, sizeof(struct timeval));
  if (tv) {
    memcpy(tv, &lastcall, sizeof(struct timeval));
  }

  return;    
}

ScanProgressMeter::ScanProgressMeter(char *stypestr) {
  scantypestr = strdup(stypestr);
  gettimeofday(&begin, NULL);
  last_print_test = begin;
  memset(&last_print, 0, sizeof(last_print));
  memset(&last_est, 0, sizeof(last_print));
  beginOrEndTask(&begin, NULL, true);
}

ScanProgressMeter::~ScanProgressMeter() {
  if (scantypestr) {
    free(scantypestr);
    scantypestr = NULL;
  }
}

/* Decides whether a timing report is likely to even be
   printed.  There are stringent limitations on how often they are
   printed, as well as the verbosity level that must exist.  So you
   might as well check this before spending much time computing
   progress info.  now can be NULL if caller doesn't have the current
   time handy.  Just because this function returns true does not mean
   that the next printStatsIfNeccessary will always print something.
   It depends on whether time estimates have changed, which this func
   doesn't even know about. */
bool ScanProgressMeter::mayBePrinted(const struct timeval *now) {
  struct timeval tv;

  if (!o.verbose)
    return false;

  if (!now) {
    gettimeofday(&tv, NULL);
    now = (const struct timeval *) &tv;
  }

  if (last_print.tv_sec == 0) {
    /* We've never printed before -- the rules are less stringent */
    if (TIMEVAL_MSEC_SUBTRACT(*now, begin) > 30000)
      return true;
    else return false;
  } 

  if (TIMEVAL_MSEC_SUBTRACT(*now, last_print_test) < 3000) 
    return false;  /* No point even checking too often */

  /* We'd never want to print more than once per 30 seconds */
  if (TIMEVAL_MSEC_SUBTRACT(*now, last_print) < 30000)
    return false;

  return true;
}

/* Prints an estimate of when this scan will complete.  It only does
   so if mayBePrinted() is true, and it seems reasonable to do so
   because the estimate has changed significantly.  Returns whether
   or not a line was printed.*/
bool ScanProgressMeter::printStatsIfNeccessary(double perc_done, 
					       const struct timeval *now) {
  struct timeval tvtmp;
  long time_used_ms;
  long time_needed_ms;
  long time_left_ms;
  long prev_est_time_left_ms; /* Time left as per prev. estimate */
  long change_abs_ms; /* absolute value of change */
  bool printit = false;

  if (!now) {
    gettimeofday(&tvtmp, NULL);
    now = (const struct timeval *) &tvtmp;
  }
  
  if (!mayBePrinted(now))
    return false;

  last_print_test = *now;

  if (perc_done <= 0.003)
    return false; /* Need more info first */

  assert(perc_done <= 1.0);

  /* OK, now lets estimate the time to finish */
  time_used_ms = TIMEVAL_MSEC_SUBTRACT(*now, begin);
  time_needed_ms = (int) ((double) time_used_ms / perc_done);
  time_left_ms = time_needed_ms - time_used_ms;

  if (time_left_ms < 30000)
    return false; /* No point in updating when it is virtually finished. */

  /* If we have not printed before, or if our previous ETC has elapsed, print
     a new one */
  if (last_print.tv_sec < 0)
    printit = true;
  else {
    /* If the estimate changed by more than X minutes, and if that
       change represents at least X% of the time remaining, print
       it.  */
    prev_est_time_left_ms = TIMEVAL_MSEC_SUBTRACT(last_est, *now);
    change_abs_ms = ABS(prev_est_time_left_ms - time_left_ms);
    if (prev_est_time_left_ms <= 0)
      printit = true;
    else if (o.debugging || (change_abs_ms > 180000 && change_abs_ms > .05 * MAX(time_left_ms, prev_est_time_left_ms)))
      printit = true;
  }

  if (printit) {
     return printStats(perc_done, now);
  } 
  return false;
}


/* Prints an estimate of when this scan will complete.  */
bool ScanProgressMeter::printStats(double perc_done, 
                                   const struct timeval *now) {
  struct timeval tvtmp;
  long time_used_ms;
  long time_needed_ms;
  long time_left_ms;
  long sec_left;
  time_t timet;
  struct tm *ltime;

  if (!now) {
    gettimeofday(&tvtmp, NULL);
    now = (const struct timeval *) &tvtmp;
  }
  
  /* OK, now lets estimate the time to finish */
  time_used_ms = TIMEVAL_MSEC_SUBTRACT(*now, begin);
  time_needed_ms = (int) ((double) time_used_ms / perc_done);
  time_left_ms = time_needed_ms - time_used_ms;

    /* Here we go! */
    last_print = *now;
    TIMEVAL_MSEC_ADD(last_est, *now, time_left_ms);
    timet = last_est.tv_sec;
    ltime = localtime(&timet);
    assert(ltime);

    sec_left = time_left_ms / 1000;

    // If we're less than 1% done we probably don't have enough
    // data for decent timing estimates. Also with perc_done == 0
    // these elements will be nonsensical.
    if (perc_done < 0.01) {
      log_write(LOG_STDOUT, "%s Timing: About %.2f%% done\n", 
                scantypestr, perc_done * 100);
      log_flush(LOG_STDOUT);
    } else {
      log_write(LOG_STDOUT, "%s Timing: About %.2f%% done; ETC: %02d:%02d (%li:%02li:%02li remaining)\n", 
                scantypestr, perc_done * 100, ltime->tm_hour, ltime->tm_min, sec_left / 3600, 
                (sec_left % 3600) / 60, sec_left % 60);
      log_write(LOG_XML, "<taskprogress task=\"%s\" time=\"%lu\" percent=\"%.2f\" remaining=\"%li\" etc=\"%lu\" />\n",
		scantypestr, (unsigned long) now->tv_sec,
		perc_done * 100, sec_left, (unsigned long) last_est.tv_sec);
      log_flush(LOG_STDOUT|LOG_XML);
    }
    return true;
}

/* Indicates that the task is beginning or ending, and that a message should
   be generated if appropriate.  Returns whether a message was printed.
   now may be NULL, if the caller doesn't have the current time handy.
   additional_info may be NULL if no additional information is necessary. */
bool ScanProgressMeter::beginOrEndTask(const struct timeval *now, const char *additional_info, bool beginning) {
  struct timeval tvtmp;
  struct tm *tm;
  time_t tv_sec;

  if (!o.verbose) {
    return false;
  }

  if (!now) {
    gettimeofday(&tvtmp, NULL);
    now = (const struct timeval *) &tvtmp;
  }

  tv_sec = now->tv_sec;
  tm = localtime(&tv_sec);
  if (beginning) {
    log_write(LOG_STDOUT, "Initiating %s at %02d:%02d", scantypestr, tm->tm_hour, tm->tm_min);
    log_write(LOG_XML, "<taskbegin task=\"%s\" time=\"%lu\"", scantypestr, (unsigned long) now->tv_sec);
    if (additional_info) {
      log_write(LOG_STDOUT, " (%s)", additional_info);
      log_write(LOG_XML, " extrainfo=\"%s\"", additional_info);
    }
    log_write(LOG_STDOUT, "\n");
    log_write(LOG_XML, " />\n");
  } else {
    log_write(LOG_STDOUT, "Completed %s at %02d:%02d, %.2fs elapsed", scantypestr, tm->tm_hour, tm->tm_min, TIMEVAL_MSEC_SUBTRACT(*now, begin) / 1000.0);
    log_write(LOG_XML, "<taskend task=\"%s\" time=\"%lu\"", scantypestr, (unsigned long) now->tv_sec);
    if (additional_info) {
      log_write(LOG_STDOUT, " (%s)", additional_info);
      log_write(LOG_XML, " extrainfo=\"%s\"", additional_info);
    }
    log_write(LOG_STDOUT, "\n");
    log_write(LOG_XML, " />\n");
  }
  log_flush(LOG_STDOUT|LOG_XML);
  return true;
}