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/module.h>
13 #include <linux/export.h>
14 #include <linux/oid_registry.h>
15 #include <linux/kernel.h>
16 #include <linux/errno.h>
17 #include <linux/bug.h>
18 #include "oid_registry_data.c"
19
20 MODULE_DESCRIPTION("OID Registry");
21 MODULE_AUTHOR("Red Hat, Inc.");
22 MODULE_LICENSE("GPL");
23
24 /**
25 * look_up_OID - Find an OID registration for the specified data
26 * @data: Binary representation of the OID
27 * @datasize: Size of the binary representation
28 */
look_up_OID(const void * data,size_t datasize)29 enum OID look_up_OID(const void *data, size_t datasize)
30 {
31 const unsigned char *octets = data;
32 enum OID oid;
33 unsigned char xhash;
34 unsigned i, j, k, hash;
35 size_t len;
36
37 /* Hash the OID data */
38 hash = datasize - 1;
39
40 for (i = 0; i < datasize; i++)
41 hash += octets[i] * 33;
42 hash = (hash >> 24) ^ (hash >> 16) ^ (hash >> 8) ^ hash;
43 hash &= 0xff;
44
45 /* Binary search the OID registry. OIDs are stored in ascending order
46 * of hash value then ascending order of size and then in ascending
47 * order of reverse value.
48 */
49 i = 0;
50 k = OID__NR;
51 while (i < k) {
52 j = (i + k) / 2;
53
54 xhash = oid_search_table[j].hash;
55 if (xhash > hash) {
56 k = j;
57 continue;
58 }
59 if (xhash < hash) {
60 i = j + 1;
61 continue;
62 }
63
64 oid = oid_search_table[j].oid;
65 len = oid_index[oid + 1] - oid_index[oid];
66 if (len > datasize) {
67 k = j;
68 continue;
69 }
70 if (len < datasize) {
71 i = j + 1;
72 continue;
73 }
74
75 /* Variation is most likely to be at the tail end of the
76 * OID, so do the comparison in reverse.
77 */
78 while (len > 0) {
79 unsigned char a = oid_data[oid_index[oid] + --len];
80 unsigned char b = octets[len];
81 if (a > b) {
82 k = j;
83 goto next;
84 }
85 if (a < b) {
86 i = j + 1;
87 goto next;
88 }
89 }
90 return oid;
91 next:
92 ;
93 }
94
95 return OID__NR;
96 }
97 EXPORT_SYMBOL_GPL(look_up_OID);
98
99 /*
100 * sprint_OID - Print an Object Identifier into a buffer
101 * @data: The encoded OID to print
102 * @datasize: The size of the encoded OID
103 * @buffer: The buffer to render into
104 * @bufsize: The size of the buffer
105 *
106 * The OID is rendered into the buffer in "a.b.c.d" format and the number of
107 * bytes is returned. -EBADMSG is returned if the data could not be intepreted
108 * and -ENOBUFS if the buffer was too small.
109 */
sprint_oid(const void * data,size_t datasize,char * buffer,size_t bufsize)110 int sprint_oid(const void *data, size_t datasize, char *buffer, size_t bufsize)
111 {
112 const unsigned char *v = data, *end = v + datasize;
113 unsigned long num;
114 unsigned char n;
115 size_t ret;
116 int count;
117
118 if (v >= end)
119 return -EBADMSG;
120
121 n = *v++;
122 ret = count = snprintf(buffer, bufsize, "%u.%u", n / 40, n % 40);
123 buffer += count;
124 bufsize -= count;
125 if (bufsize == 0)
126 return -ENOBUFS;
127
128 while (v < end) {
129 num = 0;
130 n = *v++;
131 if (!(n & 0x80)) {
132 num = n;
133 } else {
134 num = n & 0x7f;
135 do {
136 if (v >= end)
137 return -EBADMSG;
138 n = *v++;
139 num <<= 7;
140 num |= n & 0x7f;
141 } while (n & 0x80);
142 }
143 ret += count = snprintf(buffer, bufsize, ".%lu", num);
144 buffer += count;
145 bufsize -= count;
146 if (bufsize == 0)
147 return -ENOBUFS;
148 }
149
150 return ret;
151 }
152 EXPORT_SYMBOL_GPL(sprint_oid);
153
154 /**
155 * sprint_OID - Print an Object Identifier into a buffer
156 * @oid: The OID to print
157 * @buffer: The buffer to render into
158 * @bufsize: The size of the buffer
159 *
160 * The OID is rendered into the buffer in "a.b.c.d" format and the number of
161 * bytes is returned.
162 */
sprint_OID(enum OID oid,char * buffer,size_t bufsize)163 int sprint_OID(enum OID oid, char *buffer, size_t bufsize)
164 {
165 int ret;
166
167 BUG_ON(oid >= OID__NR);
168
169 ret = sprint_oid(oid_data + oid_index[oid],
170 oid_index[oid + 1] - oid_index[oid],
171 buffer, bufsize);
172 BUG_ON(ret == -EBADMSG);
173 return ret;
174 }
175 EXPORT_SYMBOL_GPL(sprint_OID);
176