1/*	$NetBSD: timegm.c,v 1.2 2017/01/28 21:31:45 christos Exp $	*/
2
3/*
4 * Copyright (c) 1997 Kungliga Tekniska H��gskolan
5 * (Royal Institute of Technology, Stockholm, Sweden).
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * 3. Neither the name of the Institute nor the names of its contributors
20 *    may be used to endorse or promote products derived from this software
21 *    without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36#include "der_locl.h"
37
38#define ASN1_MAX_YEAR	2000
39
40static int
41is_leap(unsigned y)
42{
43    y += 1900;
44    return (y % 4) == 0 && ((y % 100) != 0 || (y % 400) == 0);
45}
46
47static const unsigned ndays[2][12] ={
48    {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
49    {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}};
50
51/*
52 * This is a simplifed version of timegm(3) that doesn't accept out of
53 * bound values that timegm(3) normally accepts but those are not
54 * valid in asn1 encodings.
55 */
56
57time_t
58_der_timegm (struct tm *tm)
59{
60  time_t res = 0;
61  int i;
62
63  /*
64   * See comment in _der_gmtime
65   */
66  if (tm->tm_year > ASN1_MAX_YEAR)
67      return 0;
68
69  if (tm->tm_year < 0)
70      return -1;
71  if (tm->tm_mon < 0 || tm->tm_mon > 11)
72      return -1;
73  if (tm->tm_mday < 1 || tm->tm_mday > (int)ndays[is_leap(tm->tm_year)][tm->tm_mon])
74      return -1;
75  if (tm->tm_hour < 0 || tm->tm_hour > 23)
76      return -1;
77  if (tm->tm_min < 0 || tm->tm_min > 59)
78      return -1;
79  if (tm->tm_sec < 0 || tm->tm_sec > 59)
80      return -1;
81
82  for (i = 70; i < tm->tm_year; ++i)
83    res += is_leap(i) ? 366 : 365;
84
85  for (i = 0; i < tm->tm_mon; ++i)
86    res += ndays[is_leap(tm->tm_year)][i];
87  res += tm->tm_mday - 1;
88  res *= 24;
89  res += tm->tm_hour;
90  res *= 60;
91  res += tm->tm_min;
92  res *= 60;
93  res += tm->tm_sec;
94  return res;
95}
96
97struct tm *
98_der_gmtime(time_t t, struct tm *tm)
99{
100    time_t secday = t % (3600 * 24);
101    time_t days = t / (3600 * 24);
102
103    memset(tm, 0, sizeof(*tm));
104
105    tm->tm_sec = secday % 60;
106    tm->tm_min = (secday % 3600) / 60;
107    tm->tm_hour = (int)(secday / 3600);
108
109    /*
110     * Refuse to calculate time ~ 2000 years into the future, this is
111     * not possible for systems where time_t is a int32_t, however,
112     * when time_t is a int64_t, that can happen, and this becomes a
113     * denial of sevice.
114     */
115    if (days > (ASN1_MAX_YEAR * 365))
116	return NULL;
117
118    tm->tm_year = 70;
119    while(1) {
120	unsigned dayinyear = (is_leap(tm->tm_year) ? 366 : 365);
121	if (days < dayinyear)
122	    break;
123	tm->tm_year += 1;
124	days -= dayinyear;
125    }
126    tm->tm_mon = 0;
127
128    while (1) {
129	unsigned daysinmonth = ndays[is_leap(tm->tm_year)][tm->tm_mon];
130	if (days < daysinmonth)
131	    break;
132	days -= daysinmonth;
133	tm->tm_mon++;
134    }
135    tm->tm_mday = (int)(days + 1);
136
137    return tm;
138}
139