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
20MODULE_DESCRIPTION("OID Registry");
21MODULE_AUTHOR("Red Hat, Inc.");
22MODULE_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 */
29enum 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}
97EXPORT_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 */
110int 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}
152EXPORT_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 */
163int 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}
175EXPORT_SYMBOL_GPL(sprint_OID);
176