/*
* 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.
*
*/

#include <config.h>

#include "ntp.h"

#include "extract.h"

#define JAN_1970        INT64_T_CONSTANT(2208988800)    /* 1970 - 1900 in seconds */

void
p_ntp_time(netdissect_options *ndo,
          const struct l_fixedpt *lfp)
{
       uint32_t i;
       uint32_t uf;
       uint32_t f;
       double ff;

       i = GET_BE_U_4(lfp->int_part);
       uf = GET_BE_U_4(lfp->fraction);
       ff = uf;
       if (ff < 0.0)           /* some compilers are buggy */
               ff += FMAXINT;
       ff = ff / FMAXINT;                      /* shift radix point by 32 bits */
       f = (uint32_t)(ff * 1000000000.0);      /* treat fraction as parts per billion */
       ND_PRINT("%u.%09u", i, f);

       /*
        * print the UTC time in human-readable format.
        */
       if (i) {
           int64_t seconds_64bit = (int64_t)i - JAN_1970;
           time_t seconds;
           char time_buf[128];
           const char *time_string;

           seconds = (time_t)seconds_64bit;
           if (seconds != seconds_64bit) {
               /*
                * It doesn't fit into a time_t, so we can't hand it
                * to gmtime.
                */
               time_string = "[Time is too large to fit into a time_t]";
           } else {
               /* use ISO 8601 (RFC3339) format */
               time_string = nd_format_time(time_buf, sizeof (time_buf),
                 "%Y-%m-%dT%H:%M:%SZ", gmtime(&seconds));
           }
           ND_PRINT(" (%s)", time_string);
       }
}