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a77ad6ea DH |
1 | /* ASN.1 Object identifier (OID) registry |
2 | * | |
3 | * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. | |
4 | * Written by David Howells (dhowells@redhat.com) | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public Licence | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the Licence, or (at your option) any later version. | |
10 | */ | |
11 | ||
12 | #include <linux/export.h> | |
13 | #include <linux/oid_registry.h> | |
4f73175d DH |
14 | #include <linux/kernel.h> |
15 | #include <linux/errno.h> | |
16 | #include <linux/bug.h> | |
a77ad6ea DH |
17 | #include "oid_registry_data.c" |
18 | ||
19 | /** | |
20 | * look_up_OID - Find an OID registration for the specified data | |
21 | * @data: Binary representation of the OID | |
22 | * @datasize: Size of the binary representation | |
23 | */ | |
24 | enum OID look_up_OID(const void *data, size_t datasize) | |
25 | { | |
26 | const unsigned char *octets = data; | |
27 | enum OID oid; | |
28 | unsigned char xhash; | |
29 | unsigned i, j, k, hash; | |
30 | size_t len; | |
31 | ||
32 | /* Hash the OID data */ | |
33 | hash = datasize - 1; | |
34 | ||
35 | for (i = 0; i < datasize; i++) | |
36 | hash += octets[i] * 33; | |
37 | hash = (hash >> 24) ^ (hash >> 16) ^ (hash >> 8) ^ hash; | |
38 | hash &= 0xff; | |
39 | ||
40 | /* Binary search the OID registry. OIDs are stored in ascending order | |
41 | * of hash value then ascending order of size and then in ascending | |
42 | * order of reverse value. | |
43 | */ | |
44 | i = 0; | |
45 | k = OID__NR; | |
46 | while (i < k) { | |
47 | j = (i + k) / 2; | |
48 | ||
49 | xhash = oid_search_table[j].hash; | |
50 | if (xhash > hash) { | |
51 | k = j; | |
52 | continue; | |
53 | } | |
54 | if (xhash < hash) { | |
55 | i = j + 1; | |
56 | continue; | |
57 | } | |
58 | ||
59 | oid = oid_search_table[j].oid; | |
60 | len = oid_index[oid + 1] - oid_index[oid]; | |
61 | if (len > datasize) { | |
62 | k = j; | |
63 | continue; | |
64 | } | |
65 | if (len < datasize) { | |
66 | i = j + 1; | |
67 | continue; | |
68 | } | |
69 | ||
70 | /* Variation is most likely to be at the tail end of the | |
71 | * OID, so do the comparison in reverse. | |
72 | */ | |
73 | while (len > 0) { | |
74 | unsigned char a = oid_data[oid_index[oid] + --len]; | |
75 | unsigned char b = octets[len]; | |
76 | if (a > b) { | |
77 | k = j; | |
78 | goto next; | |
79 | } | |
80 | if (a < b) { | |
81 | i = j + 1; | |
82 | goto next; | |
83 | } | |
84 | } | |
85 | return oid; | |
86 | next: | |
87 | ; | |
88 | } | |
89 | ||
90 | return OID__NR; | |
91 | } | |
92 | EXPORT_SYMBOL_GPL(look_up_OID); | |
4f73175d DH |
93 | |
94 | /* | |
95 | * sprint_OID - Print an Object Identifier into a buffer | |
96 | * @data: The encoded OID to print | |
97 | * @datasize: The size of the encoded OID | |
98 | * @buffer: The buffer to render into | |
99 | * @bufsize: The size of the buffer | |
100 | * | |
101 | * The OID is rendered into the buffer in "a.b.c.d" format and the number of | |
102 | * bytes is returned. -EBADMSG is returned if the data could not be intepreted | |
103 | * and -ENOBUFS if the buffer was too small. | |
104 | */ | |
105 | int sprint_oid(const void *data, size_t datasize, char *buffer, size_t bufsize) | |
106 | { | |
107 | const unsigned char *v = data, *end = v + datasize; | |
108 | unsigned long num; | |
109 | unsigned char n; | |
110 | size_t ret; | |
111 | int count; | |
112 | ||
113 | if (v >= end) | |
114 | return -EBADMSG; | |
115 | ||
116 | n = *v++; | |
117 | ret = count = snprintf(buffer, bufsize, "%u.%u", n / 40, n % 40); | |
118 | buffer += count; | |
119 | bufsize -= count; | |
120 | if (bufsize == 0) | |
121 | return -ENOBUFS; | |
122 | ||
123 | while (v < end) { | |
124 | num = 0; | |
125 | n = *v++; | |
126 | if (!(n & 0x80)) { | |
127 | num = n; | |
128 | } else { | |
129 | num = n & 0x7f; | |
130 | do { | |
131 | if (v >= end) | |
132 | return -EBADMSG; | |
133 | n = *v++; | |
134 | num <<= 7; | |
135 | num |= n & 0x7f; | |
136 | } while (n & 0x80); | |
137 | } | |
138 | ret += count = snprintf(buffer, bufsize, ".%lu", num); | |
139 | buffer += count; | |
140 | bufsize -= count; | |
141 | if (bufsize == 0) | |
142 | return -ENOBUFS; | |
143 | } | |
144 | ||
145 | return ret; | |
146 | } | |
147 | EXPORT_SYMBOL_GPL(sprint_oid); | |
148 | ||
149 | /** | |
150 | * sprint_OID - Print an Object Identifier into a buffer | |
151 | * @oid: The OID to print | |
152 | * @buffer: The buffer to render into | |
153 | * @bufsize: The size of the buffer | |
154 | * | |
155 | * The OID is rendered into the buffer in "a.b.c.d" format and the number of | |
156 | * bytes is returned. | |
157 | */ | |
158 | int sprint_OID(enum OID oid, char *buffer, size_t bufsize) | |
159 | { | |
160 | int ret; | |
161 | ||
162 | BUG_ON(oid >= OID__NR); | |
163 | ||
164 | ret = sprint_oid(oid_data + oid_index[oid], | |
165 | oid_index[oid + 1] - oid_index[oid], | |
166 | buffer, bufsize); | |
167 | BUG_ON(ret == -EBADMSG); | |
168 | return ret; | |
169 | } | |
170 | EXPORT_SYMBOL_GPL(sprint_OID); |