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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> |
14 | #include <linux/kernel.h> |
15 | #include <linux/errno.h> |
16 | #include <linux/bug.h> |
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); |
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); |
171 |
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