lib/oid_registry.c

   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  */
  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  */
 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  */
 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);