1 /* $NetBSD: timegm.c,v 1.2 2017/01/28 21:31:45 christos Exp $ */
2
3 /*
4 * Copyright (c) 1997 Kungliga Tekniska Högskolan
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
40 static int
is_leap(unsigned y)41 is_leap(unsigned y)
42 {
43 y += 1900;
44 return (y % 4) == 0 && ((y % 100) != 0 || (y % 400) == 0);
45 }
46
47 static 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
57 time_t
_der_timegm(struct tm * tm)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
97 struct tm *
_der_gmtime(time_t t,struct tm * 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