diff options
Diffstat (limited to 'lib/oid_registry.c')
| -rw-r--r-- | lib/oid_registry.c | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/lib/oid_registry.c b/lib/oid_registry.c new file mode 100644 index 00000000000..d8de11f4590 --- /dev/null +++ b/lib/oid_registry.c @@ -0,0 +1,170 @@ +/* ASN.1 Object identifier (OID) registry + * + * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ + +#include <linux/export.h> +#include <linux/oid_registry.h> +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/bug.h> +#include "oid_registry_data.c" + +/** + * look_up_OID - Find an OID registration for the specified data + * @data: Binary representation of the OID + * @datasize: Size of the binary representation + */ +enum OID look_up_OID(const void *data, size_t datasize) +{ + const unsigned char *octets = data; + enum OID oid; + unsigned char xhash; + unsigned i, j, k, hash; + size_t len; + + /* Hash the OID data */ + hash = datasize - 1; + + for (i = 0; i < datasize; i++) + hash += octets[i] * 33; + hash = (hash >> 24) ^ (hash >> 16) ^ (hash >> 8) ^ hash; + hash &= 0xff; + + /* Binary search the OID registry. OIDs are stored in ascending order + * of hash value then ascending order of size and then in ascending + * order of reverse value. + */ + i = 0; + k = OID__NR; + while (i < k) { + j = (i + k) / 2; + + xhash = oid_search_table[j].hash; + if (xhash > hash) { + k = j; + continue; + } + if (xhash < hash) { + i = j + 1; + continue; + } + + oid = oid_search_table[j].oid; + len = oid_index[oid + 1] - oid_index[oid]; + if (len > datasize) { + k = j; + continue; + } + if (len < datasize) { + i = j + 1; + continue; + } + + /* Variation is most likely to be at the tail end of the + * OID, so do the comparison in reverse. + */ + while (len > 0) { + unsigned char a = oid_data[oid_index[oid] + --len]; + unsigned char b = octets[len]; + if (a > b) { + k = j; + goto next; + } + if (a < b) { + i = j + 1; + goto next; + } + } + return oid; + next: + ; + } + + return OID__NR; +} +EXPORT_SYMBOL_GPL(look_up_OID); + +/* + * sprint_OID - Print an Object Identifier into a buffer + * @data: The encoded OID to print + * @datasize: The size of the encoded OID + * @buffer: The buffer to render into + * @bufsize: The size of the buffer + * + * The OID is rendered into the buffer in "a.b.c.d" format and the number of + * bytes is returned. -EBADMSG is returned if the data could not be intepreted + * and -ENOBUFS if the buffer was too small. + */ +int sprint_oid(const void *data, size_t datasize, char *buffer, size_t bufsize) +{ + const unsigned char *v = data, *end = v + datasize; + unsigned long num; + unsigned char n; + size_t ret; + int count; + + if (v >= end) + return -EBADMSG; + + n = *v++; + ret = count = snprintf(buffer, bufsize, "%u.%u", n / 40, n % 40); + buffer += count; + bufsize -= count; + if (bufsize == 0) + return -ENOBUFS; + + while (v < end) { + num = 0; + n = *v++; + if (!(n & 0x80)) { + num = n; + } else { + num = n & 0x7f; + do { + if (v >= end) + return -EBADMSG; + n = *v++; + num <<= 7; + num |= n & 0x7f; + } while (n & 0x80); + } + ret += count = snprintf(buffer, bufsize, ".%lu", num); + buffer += count; + bufsize -= count; + if (bufsize == 0) + return -ENOBUFS; + } + + return ret; +} +EXPORT_SYMBOL_GPL(sprint_oid); + +/** + * sprint_OID - Print an Object Identifier into a buffer + * @oid: The OID to print + * @buffer: The buffer to render into + * @bufsize: The size of the buffer + * + * The OID is rendered into the buffer in "a.b.c.d" format and the number of + * bytes is returned. + */ +int sprint_OID(enum OID oid, char *buffer, size_t bufsize) +{ + int ret; + + BUG_ON(oid >= OID__NR); + + ret = sprint_oid(oid_data + oid_index[oid], + oid_index[oid + 1] - oid_index[oid], + buffer, bufsize); + BUG_ON(ret == -EBADMSG); + return ret; +} +EXPORT_SYMBOL_GPL(sprint_OID); |