tesla_key.c

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/*-
 * Copyright (c) 2013 Jonathan Anderson
 * All rights reserved.
 *
 * This software was developed by SRI International and the University of
 * Cambridge Computer Laboratory under DARPA/AFRL contract (FA8750-10-C-0237)
 * ("CTSRD"), as part of the DARPA CRASH research programme.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $Id$
 */

#include "tesla_internal.h"

#ifndef _KERNEL
#include <inttypes.h>
#include <stdio.h>
#endif


#define IS_SET(mask, index) (mask & (1 << index))

int
tesla_key_matches(const struct tesla_key *pattern, const struct tesla_key *k)
{
        assert(pattern != NULL);
        assert(k != NULL);

        // The pattern's mask must be a subset of the target's (ANY matches
        // 42 but not the other way around).
        if (!SUBSET(pattern->tk_mask, k->tk_mask))
                return (0);

        for (uint32_t i = 0; i < TESLA_KEY_SIZE; i++) {
                // Only check keys specified by the bitmasks.
                uint32_t mask = (1 << i);
                if ((pattern->tk_mask & mask) != mask)
                        continue;

                // A non-match of any sub-key implies a non-match of the key.
                if (pattern->tk_keys[i] != k->tk_keys[i])
                        return (0);
        }

        return (1);
}

int32_t
tesla_key_union(tesla_key *dest, const tesla_key *source)
{
        for (uint32_t i = 0; i < TESLA_KEY_SIZE; i++) {
                if (IS_SET(source->tk_mask, i)) {
                        if (IS_SET(dest->tk_mask, i)) {
                            if (dest->tk_keys[i] != source->tk_keys[i])
                                return (TESLA_ERROR_EINVAL);
                        } else {
                                dest->tk_keys[i] = source->tk_keys[i];
                        }
                }
        }

        dest->tk_mask |= source->tk_mask;
        return (TESLA_SUCCESS);
}