110 lines
2.4 KiB
C
110 lines
2.4 KiB
C
/*
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* Copyright (c) 2016 MariaDB Corporation Ab
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*
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* Use of this software is governed by the Business Source License included
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* in the LICENSE.TXT file and at www.mariadb.com/bsl11.
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*
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* Change Date: 2019-07-01
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*
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* On the date above, in accordance with the Business Source License, use
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* of this software will be governed by version 2 or later of the General
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* Public License.
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*/
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/**
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* @file random_jkiss.c - Random number generator for the MariaDB Corporation MaxScale
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*
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* See http://www0.cs.ucl.ac.uk/staff/d.jones/GoodPracticeRNG.pdf for discussion of random
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* number generators (RNGs).
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*/
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#include <stdbool.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <maxscale/random_jkiss.h>
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#include <maxscale/debug.h>
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/* Public domain code for JKISS RNG - Comment header added */
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/* If possible, the seed variables will be set from /dev/urandom but
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* should that fail, these arbitrary numbers will be used as a last resort.
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*/
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static unsigned int x = 123456789, y = 987654321, z = 43219876, c = 6543217; /* Seed variables */
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static bool init = false;
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unsigned int random_jkiss(void)
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{
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unsigned long long t;
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unsigned int result;
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ss_dassert(init);
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x = 314527869 * x + 1234567;
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y ^= y << 5;
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y ^= y >> 7;
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y ^= y << 22;
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t = 4294584393ULL * z + c;
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c = t >> 32;
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z = t;
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result = x + y + z;
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return result;
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}
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/* Own code adapted from http://www0.cs.ucl.ac.uk/staff/d.jones/GoodPracticeRNG.pdf */
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/***
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*
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* Obtain a seed random number from /dev/urandom if available.
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*
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* @return uint Random number
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*
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*/
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static unsigned int random_jkiss_devrand(void)
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{
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int fn;
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unsigned int r;
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if ((fn = open("/dev/urandom", O_RDONLY)) == -1)
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{
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return 0;
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}
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if (read(fn, &r, sizeof(r)) != sizeof(r))
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{
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r = 0;
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}
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close(fn);
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return r;
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}
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void random_jkiss_init(void)
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{
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if (!init)
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{
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int newrand, i;
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if ((newrand = random_jkiss_devrand()) != 0)
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{
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x = newrand;
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}
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if ((newrand = random_jkiss_devrand()) != 0)
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{
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y = newrand;
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}
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if ((newrand = random_jkiss_devrand()) != 0)
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{
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z = newrand;
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}
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if ((newrand = random_jkiss_devrand()) != 0)
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{
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c = newrand % 698769068 + 1; /* Should be less than 698769069 */
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}
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init = true;
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}
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}
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