1 /* ASN.1 Object identifier (OID) registry
3 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
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.
12 #include <linux/export.h>
13 #include <linux/oid_registry.h>
14 #include "oid_registry_data.c"
17 * look_up_OID - Find an OID registration for the specified data
18 * @data: Binary representation of the OID
19 * @datasize: Size of the binary representation
21 enum OID look_up_OID(const void *data, size_t datasize)
23 const unsigned char *octets = data;
26 unsigned i, j, k, hash;
29 /* Hash the OID data */
32 for (i = 0; i < datasize; i++)
33 hash += octets[i] * 33;
34 hash = (hash >> 24) ^ (hash >> 16) ^ (hash >> 8) ^ hash;
37 /* Binary search the OID registry. OIDs are stored in ascending order
38 * of hash value then ascending order of size and then in ascending
39 * order of reverse value.
46 xhash = oid_search_table[j].hash;
56 oid = oid_search_table[j].oid;
57 len = oid_index[oid + 1] - oid_index[oid];
67 /* Variation is most likely to be at the tail end of the
68 * OID, so do the comparison in reverse.
71 unsigned char a = oid_data[oid_index[oid] + --len];
72 unsigned char b = octets[len];
89 EXPORT_SYMBOL_GPL(look_up_OID);