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