unbound/util/rfc_1982.c
2023-09-05 17:35:30 +02:00

76 lines
2.3 KiB
C

/*
* util/rfc_1982.c - RFC 1982 Serial Number Arithmetic
*
* Copyright (c) 2023, NLnet Labs. All rights reserved.
*
* This software is open source.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 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.
*
* Neither the name of the NLNET LABS nor the names of its contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
* HOLDER 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.
*/
/**
* \file
*
* This file contains functions for RFC 1982 serial number arithmetic.
*/
#include "config.h"
#include "util/rfc_1982.h"
int
compare_1982(uint32_t a, uint32_t b)
{
/* for 32 bit values */
const uint32_t cutoff = ((uint32_t) 1 << (32 - 1));
if (a == b) {
return 0;
} else if ((a < b && b - a < cutoff) || (a > b && a - b > cutoff)) {
return -1;
} else {
return 1;
}
}
uint32_t
subtract_1982(uint32_t a, uint32_t b)
{
/* for 32 bit values */
const uint32_t cutoff = ((uint32_t) 1 << (32 - 1));
if(a == b)
return 0;
if(a < b && b - a < cutoff) {
return b-a;
}
if(a > b && a - b > cutoff) {
return ((uint32_t)0xffffffff) - (a-b-1);
}
/* wrong case, b smaller than a */
return 0;
}