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print-ntp.c

/*
 * Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
 *    The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that: (1) source code distributions
 * retain the above copyright notice and this paragraph in its entirety, (2)
 * distributions including binary code include the above copyright notice and
 * this paragraph in its entirety in the documentation or other materials
 * provided with the distribution, and (3) all advertising materials mentioning
 * features or use of this software display the following acknowledgement:
 * ``This product includes software developed by the University of California,
 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
 * the University nor the names of its contributors may be used to endorse
 * or promote products derived from this software without specific prior
 * written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Format and print ntp packets.
 *    By Jeffrey Mogul/DECWRL
 *    loosely based on print-bootp.c
 */

#ifndef lint
static const char rcsid[] _U_ =
    "@(#) $Header: /tcpdump/master/tcpdump/print-ntp.c,v 1.37.2.2 2003/11/16 08:51:36 guy Exp $ (LBL)";
#endif

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <tcpdump-stdinc.h>

#include <stdio.h>
#include <string.h>
#ifdef HAVE_STRFTIME
#include <time.h>
#endif

#include "interface.h"
#include "addrtoname.h"
#include "extract.h"
#ifdef MODEMASK
#undef MODEMASK                           /* Solaris sucks */
#endif
#include "ntp.h"

static void p_sfix(const struct s_fixedpt *);
static void p_ntp_time(const struct l_fixedpt *);
static void p_ntp_delta(const struct l_fixedpt *, const struct l_fixedpt *);

/*
 * Print ntp requests
 */
void
ntp_print(register const u_char *cp, u_int length)
{
      register const struct ntpdata *bp;
      int mode, version, leapind;

      bp = (struct ntpdata *)cp;
      /* Note funny sized packets */
      if (length != sizeof(struct ntpdata))
            (void)printf(" [len=%d]", length);

      TCHECK(bp->status);

      version = (int)(bp->status & VERSIONMASK) >> 3;
      printf("NTPv%d", version);

      leapind = bp->status & LEAPMASK;
      switch (leapind) {

      case NO_WARNING:
            break;

      case PLUS_SEC:
            fputs(" +1s", stdout);
            break;

      case MINUS_SEC:
            fputs(" -1s", stdout);
            break;
      }

      mode = bp->status & MODEMASK;
      switch (mode) {

      case MODE_UNSPEC: /* unspecified */
            fputs(" unspec", stdout);
            break;

      case MODE_SYM_ACT:      /* symmetric active */
            fputs(" sym_act", stdout);
            break;

      case MODE_SYM_PAS:      /* symmetric passive */
            fputs(" sym_pas", stdout);
            break;

      case MODE_CLIENT: /* client */
            fputs(" client", stdout);
            break;

      case MODE_SERVER: /* server */
            fputs(" server", stdout);
            break;

      case MODE_BROADCAST:    /* broadcast */
            fputs(" bcast", stdout);
            break;

      case MODE_RES1:         /* reserved */
            fputs(" res1", stdout);
            break;

      case MODE_RES2:         /* reserved */
            fputs(" res2", stdout);
            break;

      }

      TCHECK(bp->stratum);
      printf(", strat %d", bp->stratum);

      TCHECK(bp->ppoll);
      printf(", poll %d", bp->ppoll);

      /* Can't TCHECK bp->precision bitfield so bp->distance + 0 instead */
      TCHECK2(bp->distance, 0);
      printf(", prec %d", bp->precision);

      if (!vflag)
            return;

      TCHECK(bp->distance);
      fputs(" dist ", stdout);
      p_sfix(&bp->distance);

      TCHECK(bp->dispersion);
      fputs(", disp ", stdout);
      p_sfix(&bp->dispersion);

      TCHECK(bp->refid);
      fputs(", ref ", stdout);
      /* Interpretation depends on stratum */
      switch (bp->stratum) {

      case UNSPECIFIED:
            printf("(unspec)");
            break;

      case PRIM_REF:
            fn_printn((u_char *)&(bp->refid), 4, NULL);
            break;

      case INFO_QUERY:
            printf("%s INFO_QUERY", ipaddr_string(&(bp->refid)));
            /* this doesn't have more content */
            return;

      case INFO_REPLY:
            printf("%s INFO_REPLY", ipaddr_string(&(bp->refid)));
            /* this is too complex to be worth printing */
            return;

      default:
            printf("%s", ipaddr_string(&(bp->refid)));
            break;
      }

      TCHECK(bp->reftime);
      putchar('@');
      p_ntp_time(&(bp->reftime));

      TCHECK(bp->org);
      fputs(" orig ", stdout);
      p_ntp_time(&(bp->org));

      TCHECK(bp->rec);
      fputs(" rec ", stdout);
      p_ntp_delta(&(bp->org), &(bp->rec));

      TCHECK(bp->xmt);
      fputs(" xmt ", stdout);
      p_ntp_delta(&(bp->org), &(bp->xmt));

      return;

trunc:
      fputs(" [|ntp]", stdout);
}

static void
p_sfix(register const struct s_fixedpt *sfp)
{
      register int i;
      register int f;
      register float ff;

      i = EXTRACT_16BITS(&sfp->int_part);
      f = EXTRACT_16BITS(&sfp->fraction);
      ff = f / 65536.0; /* shift radix point by 16 bits */
      f = ff * 1000000.0;     /* Treat fraction as parts per million */
      printf("%d.%06d", i, f);
}

#define     FMAXINT     (4294967296.0)    /* floating point rep. of MAXINT */

static void
p_ntp_time(register const struct l_fixedpt *lfp)
{
      register int32_t i;
      register u_int32_t uf;
      register u_int32_t f;
      register float ff;

      i = EXTRACT_32BITS(&lfp->int_part);
      uf = EXTRACT_32BITS(&lfp->fraction);
      ff = uf;
      if (ff < 0.0)           /* some compilers are buggy */
            ff += FMAXINT;
      ff = ff / FMAXINT;      /* shift radix point by 32 bits */
      f = ff * 1000000000.0;  /* treat fraction as parts per billion */
      printf("%u.%09d", i, f);

#ifdef HAVE_STRFTIME
      /*
       * For extra verbosity, print the time in human-readable format.
       */
      if (vflag > 1 && i) {
          time_t seconds = i - JAN_1970;
          struct tm *tm;
          char time_buf[128];

          tm = localtime(&seconds);
          strftime(time_buf, sizeof (time_buf), "%Y/%m/%d %H:%M:%S", tm);
          printf (" (%s)", time_buf);
      }
#endif
}

/* Prints time difference between *lfp and *olfp */
static void
p_ntp_delta(register const struct l_fixedpt *olfp,
          register const struct l_fixedpt *lfp)
{
      register int32_t i;
      register u_int32_t u, uf;
      register u_int32_t ou, ouf;
      register u_int32_t f;
      register float ff;
      int signbit;

      u = EXTRACT_32BITS(&lfp->int_part);
      ou = EXTRACT_32BITS(&olfp->int_part);
      uf = EXTRACT_32BITS(&lfp->fraction);
      ouf = EXTRACT_32BITS(&olfp->fraction);
      if (ou == 0 && ouf == 0) {
            p_ntp_time(lfp);
            return;
      }

      i = u - ou;

      if (i > 0) {            /* new is definitely greater than old */
            signbit = 0;
            f = uf - ouf;
            if (ouf > uf)     /* must borrow from high-order bits */
                  i -= 1;
      } else if (i < 0) {     /* new is definitely less than old */
            signbit = 1;
            f = ouf - uf;
            if (uf > ouf)     /* must carry into the high-order bits */
                  i += 1;
            i = -i;
      } else {          /* int_part is zero */
            if (uf > ouf) {
                  signbit = 0;
                  f = uf - ouf;
            } else {
                  signbit = 1;
                  f = ouf - uf;
            }
      }

      ff = f;
      if (ff < 0.0)           /* some compilers are buggy */
            ff += FMAXINT;
      ff = ff / FMAXINT;      /* shift radix point by 32 bits */
      f = ff * 1000000000.0;  /* treat fraction as parts per billion */
      if (signbit)
            putchar('-');
      else
            putchar('+');
      printf("%d.%09d", i, f);
}


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