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   1 /*
   2  * Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that: (1) source code distributions
   7  * retain the above copyright notice and this paragraph in its entirety, (2)
   8  * distributions including binary code include the above copyright notice and
   9  * this paragraph in its entirety in the documentation or other materials
  10  * provided with the distribution, and (3) all advertising materials mentioning
  11  * features or use of this software display the following acknowledgement:
  12  * ``This product includes software developed by the University of California,
  13  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  14  * the University nor the names of its contributors may be used to endorse
  15  * or promote products derived from this software without specific prior
  16  * written permission.
  17  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  18  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  20  *
  21  */
  22
  23 #ifdef HAVE_CONFIG_H
  24 #include <config.h>
  25 #endif
  26
  27 #include "ntp.h"
  28
  29 #include "extract.h"
  30
  31 #define JAN_1970        INT64_T_CONSTANT(2208988800)    /* 1970 - 1900 in seconds */
  32
  33 void
  34 p_ntp_time(netdissect_options *ndo,
  35            const struct l_fixedpt *lfp)
  36 {
  37         uint32_t i;
  38         uint32_t uf;
  39         uint32_t f;
  40         double ff;
  41
  42         i = GET_BE_U_4(lfp->int_part);
  43         uf = GET_BE_U_4(lfp->fraction);
  44         ff = uf;
  45         if (ff < 0.0)           /* some compilers are buggy */
  46                 ff += FMAXINT;
  47         ff = ff / FMAXINT;                      /* shift radix point by 32 bits */
  48         f = (uint32_t)(ff * 1000000000.0);      /* treat fraction as parts per billion */
  49         ND_PRINT("%u.%09u", i, f);
  50
  51 #ifdef HAVE_STRFTIME
  52         /*
  53          * print the UTC time in human-readable format.
  54          */
  55         if (i) {
  56             int64_t seconds_64bit = (int64_t)i - JAN_1970;
  57             time_t seconds;
  58             struct tm *tm;
  59             char time_buf[128];
  60
  61             seconds = (time_t)seconds_64bit;
  62             if (seconds != seconds_64bit) {
  63                 /*
  64                  * It doesn't fit into a time_t, so we can't hand it
  65                  * to gmtime.
  66                  */
  67                 ND_PRINT(" (unrepresentable)");
  68             } else {
  69                 tm = gmtime(&seconds);
  70                 if (tm == NULL) {
  71                     /*
  72                      * gmtime() can't handle it.
  73                      * (Yes, that might happen with some version of
  74                      * Microsoft's C library.)
  75                      */
  76                     ND_PRINT(" (unrepresentable)");
  77                 } else {
  78                     /* use ISO 8601 (RFC3339) format */
  79                     strftime(time_buf, sizeof (time_buf), "%Y-%m-%dT%H:%M:%SZ", tm);
  80                     ND_PRINT(" (%s)", time_buf);
  81                 }
  82             }
  83         }
  84 #endif
  85 }