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Commit | Line | Data |
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6fc6879b JM |
1 | /* |
2 | * ASN.1 DER parsing | |
3 | * Copyright (c) 2006, Jouni Malinen <j@w1.fi> | |
4 | * | |
0f3d578e JM |
5 | * This software may be distributed under the terms of the BSD license. |
6 | * See README for more details. | |
6fc6879b JM |
7 | */ |
8 | ||
9 | #include "includes.h" | |
10 | ||
11 | #include "common.h" | |
6fc6879b JM |
12 | #include "asn1.h" |
13 | ||
14 | int asn1_get_next(const u8 *buf, size_t len, struct asn1_hdr *hdr) | |
15 | { | |
16 | const u8 *pos, *end; | |
17 | u8 tmp; | |
18 | ||
19 | os_memset(hdr, 0, sizeof(*hdr)); | |
20 | pos = buf; | |
21 | end = buf + len; | |
22 | ||
23 | hdr->identifier = *pos++; | |
24 | hdr->class = hdr->identifier >> 6; | |
25 | hdr->constructed = !!(hdr->identifier & (1 << 5)); | |
26 | ||
27 | if ((hdr->identifier & 0x1f) == 0x1f) { | |
28 | hdr->tag = 0; | |
29 | do { | |
30 | if (pos >= end) { | |
31 | wpa_printf(MSG_DEBUG, "ASN.1: Identifier " | |
32 | "underflow"); | |
33 | return -1; | |
34 | } | |
35 | tmp = *pos++; | |
36 | wpa_printf(MSG_MSGDUMP, "ASN.1: Extended tag data: " | |
37 | "0x%02x", tmp); | |
38 | hdr->tag = (hdr->tag << 7) | (tmp & 0x7f); | |
39 | } while (tmp & 0x80); | |
40 | } else | |
41 | hdr->tag = hdr->identifier & 0x1f; | |
42 | ||
43 | tmp = *pos++; | |
44 | if (tmp & 0x80) { | |
45 | if (tmp == 0xff) { | |
46 | wpa_printf(MSG_DEBUG, "ASN.1: Reserved length " | |
47 | "value 0xff used"); | |
48 | return -1; | |
49 | } | |
50 | tmp &= 0x7f; /* number of subsequent octets */ | |
51 | hdr->length = 0; | |
52 | if (tmp > 4) { | |
53 | wpa_printf(MSG_DEBUG, "ASN.1: Too long length field"); | |
54 | return -1; | |
55 | } | |
56 | while (tmp--) { | |
57 | if (pos >= end) { | |
58 | wpa_printf(MSG_DEBUG, "ASN.1: Length " | |
59 | "underflow"); | |
60 | return -1; | |
61 | } | |
62 | hdr->length = (hdr->length << 8) | *pos++; | |
63 | } | |
64 | } else { | |
65 | /* Short form - length 0..127 in one octet */ | |
66 | hdr->length = tmp; | |
67 | } | |
68 | ||
69 | if (end < pos || hdr->length > (unsigned int) (end - pos)) { | |
70 | wpa_printf(MSG_DEBUG, "ASN.1: Contents underflow"); | |
71 | return -1; | |
72 | } | |
73 | ||
74 | hdr->payload = pos; | |
75 | return 0; | |
76 | } | |
77 | ||
78 | ||
efe22727 | 79 | int asn1_parse_oid(const u8 *buf, size_t len, struct asn1_oid *oid) |
6fc6879b | 80 | { |
6fc6879b JM |
81 | const u8 *pos, *end; |
82 | unsigned long val; | |
83 | u8 tmp; | |
84 | ||
85 | os_memset(oid, 0, sizeof(*oid)); | |
86 | ||
efe22727 JM |
87 | pos = buf; |
88 | end = buf + len; | |
6fc6879b JM |
89 | |
90 | while (pos < end) { | |
91 | val = 0; | |
92 | ||
93 | do { | |
94 | if (pos >= end) | |
95 | return -1; | |
96 | tmp = *pos++; | |
97 | val = (val << 7) | (tmp & 0x7f); | |
98 | } while (tmp & 0x80); | |
99 | ||
100 | if (oid->len >= ASN1_MAX_OID_LEN) { | |
101 | wpa_printf(MSG_DEBUG, "ASN.1: Too long OID value"); | |
102 | return -1; | |
103 | } | |
104 | if (oid->len == 0) { | |
105 | /* | |
106 | * The first octet encodes the first two object | |
107 | * identifier components in (X*40) + Y formula. | |
108 | * X = 0..2. | |
109 | */ | |
110 | oid->oid[0] = val / 40; | |
111 | if (oid->oid[0] > 2) | |
112 | oid->oid[0] = 2; | |
113 | oid->oid[1] = val - oid->oid[0] * 40; | |
114 | oid->len = 2; | |
115 | } else | |
116 | oid->oid[oid->len++] = val; | |
117 | } | |
118 | ||
119 | return 0; | |
120 | } | |
121 | ||
122 | ||
efe22727 JM |
123 | int asn1_get_oid(const u8 *buf, size_t len, struct asn1_oid *oid, |
124 | const u8 **next) | |
125 | { | |
126 | struct asn1_hdr hdr; | |
127 | ||
128 | if (asn1_get_next(buf, len, &hdr) < 0 || hdr.length == 0) | |
129 | return -1; | |
130 | ||
131 | if (hdr.class != ASN1_CLASS_UNIVERSAL || hdr.tag != ASN1_TAG_OID) { | |
132 | wpa_printf(MSG_DEBUG, "ASN.1: Expected OID - found class %d " | |
133 | "tag 0x%x", hdr.class, hdr.tag); | |
134 | return -1; | |
135 | } | |
136 | ||
137 | *next = hdr.payload + hdr.length; | |
138 | ||
139 | return asn1_parse_oid(hdr.payload, hdr.length, oid); | |
140 | } | |
141 | ||
142 | ||
6fc6879b JM |
143 | void asn1_oid_to_str(struct asn1_oid *oid, char *buf, size_t len) |
144 | { | |
145 | char *pos = buf; | |
146 | size_t i; | |
147 | int ret; | |
148 | ||
149 | if (len == 0) | |
150 | return; | |
151 | ||
152 | buf[0] = '\0'; | |
153 | ||
154 | for (i = 0; i < oid->len; i++) { | |
155 | ret = os_snprintf(pos, buf + len - pos, | |
156 | "%s%lu", | |
157 | i == 0 ? "" : ".", oid->oid[i]); | |
158 | if (ret < 0 || ret >= buf + len - pos) | |
159 | break; | |
160 | pos += ret; | |
161 | } | |
162 | buf[len - 1] = '\0'; | |
163 | } | |
164 | ||
165 | ||
166 | static u8 rotate_bits(u8 octet) | |
167 | { | |
168 | int i; | |
169 | u8 res; | |
170 | ||
171 | res = 0; | |
172 | for (i = 0; i < 8; i++) { | |
173 | res <<= 1; | |
174 | if (octet & 1) | |
175 | res |= 1; | |
176 | octet >>= 1; | |
177 | } | |
178 | ||
179 | return res; | |
180 | } | |
181 | ||
182 | ||
183 | unsigned long asn1_bit_string_to_long(const u8 *buf, size_t len) | |
184 | { | |
185 | unsigned long val = 0; | |
186 | const u8 *pos = buf; | |
187 | ||
188 | /* BER requires that unused bits are zero, so we can ignore the number | |
189 | * of unused bits */ | |
190 | pos++; | |
191 | ||
192 | if (len >= 2) | |
193 | val |= rotate_bits(*pos++); | |
194 | if (len >= 3) | |
195 | val |= ((unsigned long) rotate_bits(*pos++)) << 8; | |
196 | if (len >= 4) | |
197 | val |= ((unsigned long) rotate_bits(*pos++)) << 16; | |
198 | if (len >= 5) | |
199 | val |= ((unsigned long) rotate_bits(*pos++)) << 24; | |
200 | if (len >= 6) | |
201 | wpa_printf(MSG_DEBUG, "X509: %s - some bits ignored " | |
202 | "(BIT STRING length %lu)", | |
203 | __func__, (unsigned long) len); | |
204 | ||
205 | return val; | |
206 | } |