From a77ad6ea0b0bb1f9d1f52ed494bd72a5fdde208e Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 21 Sep 2012 23:30:46 +0100 Subject: X.509: Implement simple static OID registry Implement a simple static OID registry that allows the mapping of an encoded OID to an enum value for ease of use. The OID registry index enum appears in the: linux/oid_registry.h header file. A script generates the registry from lines in the header file that look like: OID_foo,/*1.2.3.4*/ The actual OID is taken to be represented by the numbers with interpolated dots in the comment. All other lines in the header are ignored. The registry is queries by calling: OID look_up_oid(const void *data, size_t datasize); This returns a number from the registry enum representing the OID if found or OID__NR if not. Signed-off-by: David Howells Signed-off-by: Rusty Russell --- lib/oid_registry.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 89 insertions(+) create mode 100644 lib/oid_registry.c (limited to 'lib/oid_registry.c') diff --git a/lib/oid_registry.c b/lib/oid_registry.c new file mode 100644 index 00000000000..33cfd171f62 --- /dev/null +++ b/lib/oid_registry.c @@ -0,0 +1,89 @@ +/* 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 +#include +#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); -- cgit v1.2.3