1 /* $OpenBSD: a_time_tm.c,v 1.16 2020/12/16 18:35:59 tb Exp $ */
2 /*
3  * Copyright (c) 2015 Bob Beck <beck@openbsd.org>
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 #include "includes.h"
19 
20 #include <ctype.h>
21 #include <limits.h>
22 #include <stdio.h>
23 #include <string.h>
24 #include <time.h>
25 
26 #define GENTIME_LENGTH 15
27 #define UTCTIME_LENGTH 13
28 
29 #define V_ASN1_UTCTIME		23
30 #define V_ASN1_GENERALIZEDTIME	24
31 
32 int
33 ASN1_time_tm_cmp(struct tm *tm1, struct tm *tm2)
34 {
35 	if (tm1->tm_year < tm2->tm_year)
36 		return (-1);
37 	if (tm1->tm_year > tm2->tm_year)
38 		return (1);
39 	if (tm1->tm_mon < tm2->tm_mon)
40 		return (-1);
41 	if (tm1->tm_mon > tm2->tm_mon)
42 		return (1);
43 	if (tm1->tm_mday < tm2->tm_mday)
44 		return (-1);
45 	if (tm1->tm_mday > tm2->tm_mday)
46 		return (1);
47 	if (tm1->tm_hour < tm2->tm_hour)
48 		return (-1);
49 	if (tm1->tm_hour > tm2->tm_hour)
50 		return (1);
51 	if (tm1->tm_min < tm2->tm_min)
52 		return (-1);
53 	if (tm1->tm_min > tm2->tm_min)
54 		return (1);
55 	if (tm1->tm_sec < tm2->tm_sec)
56 		return (-1);
57 	if (tm1->tm_sec > tm2->tm_sec)
58 		return (1);
59 	return 0;
60 }
61 
62 int
63 ASN1_time_tm_clamp_notafter(struct tm *tm)
64 {
65 #ifdef SMALL_TIME_T
66 	struct tm broken_os_epoch_tm;
67 	time_t broken_os_epoch_time = INT_MAX;
68 
69 	if (gmtime_r(&broken_os_epoch_time, &broken_os_epoch_tm) == NULL)
70 		return 0;
71 
72 	if (ASN1_time_tm_cmp(tm, &broken_os_epoch_tm) == 1)
73 		memcpy(tm, &broken_os_epoch_tm, sizeof(*tm));
74 #endif
75 	return 1;
76 }
77 
78 /*
79  * Parse an RFC 5280 format ASN.1 time string.
80  *
81  * mode must be:
82  * 0 if we expect to parse a time as specified in RFC 5280 for an X509 object.
83  * V_ASN1_UTCTIME if we wish to parse an RFC5280 format UTC time.
84  * V_ASN1_GENERALIZEDTIME if we wish to parse an RFC5280 format Generalized time.
85  *
86  * Returns:
87  * -1 if the string was invalid.
88  * V_ASN1_UTCTIME if the string validated as a UTC time string.
89  * V_ASN1_GENERALIZEDTIME if the string validated as a Generalized time string.
90  *
91  * Fills in *tm with the corresponding time if tm is non NULL.
92  */
93 #define	ATOI2(ar)	((ar) += 2, ((ar)[-2] - '0') * 10 + ((ar)[-1] - '0'))
94 int
95 ASN1_time_parse(const char *bytes, size_t len, struct tm *tm, int mode)
96 {
97 	size_t i;
98 	int type = 0;
99 	struct tm ltm;
100 	struct tm *lt;
101 	const char *p;
102 
103 	if (bytes == NULL)
104 		return (-1);
105 
106 	/* Constrain to valid lengths. */
107 	if (len != UTCTIME_LENGTH && len != GENTIME_LENGTH)
108 		return (-1);
109 
110 	lt = tm;
111 	if (lt == NULL)
112 		lt = &ltm;
113 	memset(lt, 0, sizeof(*lt));
114 
115 	/* Timezone is required and must be GMT (Zulu). */
116 	if (bytes[len - 1] != 'Z')
117 		return (-1);
118 
119 	/* Make sure everything else is digits. */
120 	for (i = 0; i < len - 1; i++) {
121 		if (isdigit((unsigned char)bytes[i]))
122 			continue;
123 		return (-1);
124 	}
125 
126 	/*
127 	 * Validate and convert the time
128 	 */
129 	p = bytes;
130 	switch (len) {
131 	case GENTIME_LENGTH:
132 		if (mode == V_ASN1_UTCTIME)
133 			return (-1);
134 		lt->tm_year = (ATOI2(p) * 100) - 1900;	/* cc */
135 		type = V_ASN1_GENERALIZEDTIME;
136 		/* FALLTHROUGH */
137 	case UTCTIME_LENGTH:
138 		if (type == 0) {
139 			if (mode == V_ASN1_GENERALIZEDTIME)
140 				return (-1);
141 			type = V_ASN1_UTCTIME;
142 		}
143 		lt->tm_year += ATOI2(p);		/* yy */
144 		if (type == V_ASN1_UTCTIME) {
145 			if (lt->tm_year < 50)
146 				lt->tm_year += 100;
147 		}
148 		lt->tm_mon = ATOI2(p) - 1;		/* mm */
149 		if (lt->tm_mon < 0 || lt->tm_mon > 11)
150 			return (-1);
151 		lt->tm_mday = ATOI2(p);			/* dd */
152 		if (lt->tm_mday < 1 || lt->tm_mday > 31)
153 			return (-1);
154 		lt->tm_hour = ATOI2(p);			/* HH */
155 		if (lt->tm_hour < 0 || lt->tm_hour > 23)
156 			return (-1);
157 		lt->tm_min = ATOI2(p);			/* MM */
158 		if (lt->tm_min < 0 || lt->tm_min > 59)
159 			return (-1);
160 		lt->tm_sec = ATOI2(p);			/* SS */
161 		/* Leap second 60 is not accepted. Reconsider later? */
162 		if (lt->tm_sec < 0 || lt->tm_sec > 59)
163 			return (-1);
164 		break;
165 	default:
166 		return (-1);
167 	}
168 
169 	return (type);
170 }