/*      $NetBSD: ns_date.c,v 1.1.1.2 2012/09/09 16:08:03 christos Exp $ */

/*
* Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
* Copyright (c) 1999 by Internet Software Consortium.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
* OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

#ifndef lint
static const char rcsid[] = "Id: ns_date.c,v 1.6 2005/04/27 04:56:39 sra Exp ";
#endif

/* Import. */

#include "port_before.h"

#include <arpa/nameser.h>

#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <time.h>

#include "port_after.h"

#ifdef SPRINTF_CHAR
# define SPRINTF(x) strlen(sprintf/**/x)
#else
# define SPRINTF(x) ((size_t)sprintf x)
#endif

/* Forward. */

static int      datepart(const char *, int, int, int, int *);

/* Public. */

/*%
* Convert a date in ASCII into the number of seconds since
* 1 January 1970 (GMT assumed).  Format is yyyymmddhhmmss, all
* digits required, no spaces allowed.
*/

u_int32_t
ns_datetosecs(const char *cp, int *errp) {
       struct tm time;
       u_int32_t result;
       int mdays, i;
       static const int days_per_month[12] =
               {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

       if (strlen(cp) != 14U) {
               *errp = 1;
               return (0);
       }
       *errp = 0;

       memset(&time, 0, sizeof time);
       time.tm_year  = datepart(cp +  0, 4, 1990, 9999, errp) - 1900;
       time.tm_mon   = datepart(cp +  4, 2,   01,   12, errp) - 1;
       time.tm_mday  = datepart(cp +  6, 2,   01,   31, errp);
       time.tm_hour  = datepart(cp +  8, 2,   00,   23, errp);
       time.tm_min   = datepart(cp + 10, 2,   00,   59, errp);
       time.tm_sec   = datepart(cp + 12, 2,   00,   59, errp);
       if (*errp)              /*%< Any parse errors? */
               return (0);

       /*
        * OK, now because timegm() is not available in all environments,
        * we will do it by hand.  Roll up sleeves, curse the gods, begin!
        */

#define SECS_PER_DAY    ((u_int32_t)24*60*60)
#define isleap(y) ((((y) % 4) == 0 && ((y) % 100) != 0) || ((y) % 400) == 0)

       result  = time.tm_sec;                          /*%< Seconds */
       result += time.tm_min * 60;                     /*%< Minutes */
       result += time.tm_hour * (60*60);               /*%< Hours */
       result += (time.tm_mday - 1) * SECS_PER_DAY;    /*%< Days */
       /* Months are trickier.  Look without leaping, then leap */
       mdays = 0;
       for (i = 0; i < time.tm_mon; i++)
               mdays += days_per_month[i];
       result += mdays * SECS_PER_DAY;                 /*%< Months */
       if (time.tm_mon > 1 && isleap(1900+time.tm_year))
               result += SECS_PER_DAY;         /*%< Add leapday for this year */
       /* First figure years without leapdays, then add them in.  */
       /* The loop is slow, FIXME, but simple and accurate.  */
       result += (time.tm_year - 70) * (SECS_PER_DAY*365); /*%< Years */
       for (i = 70; i < time.tm_year; i++)
               if (isleap(1900+i))
                       result += SECS_PER_DAY; /*%< Add leapday for prev year */
       return (result);
}

/* Private. */

/*%
* Parse part of a date.  Set error flag if any error.
* Don't reset the flag if there is no error.
*/
static int
datepart(const char *buf, int size, int min, int max, int *errp) {
       int result = 0;
       int i;

       for (i = 0; i < size; i++) {
               if (!isdigit((unsigned char)(buf[i])))
                       *errp = 1;
               result = (result * 10) + buf[i] - '0';
       }
       if (result < min)
               *errp = 1;
       if (result > max)
               *errp = 1;
       return (result);
}

/*! \file */