334e71b079
The random number generator can be initialized when MaxScale's other systems are being initialized. This removes the need to initialized it when the function is used for the first time.
116 lines
2.5 KiB
C
116 lines
2.5 KiB
C
/*
|
|
* Copyright (c) 2016 MariaDB Corporation Ab
|
|
*
|
|
* Use of this software is governed by the Business Source License included
|
|
* in the LICENSE.TXT file and at www.mariadb.com/bsl.
|
|
*
|
|
* Change Date: 2019-07-01
|
|
*
|
|
* On the date above, in accordance with the Business Source License, use
|
|
* of this software will be governed by version 2 or later of the General
|
|
* Public License.
|
|
*/
|
|
|
|
/**
|
|
* @file random_jkiss.c - Random number generator for the MariaDB Corporation MaxScale
|
|
*
|
|
* See http://www0.cs.ucl.ac.uk/staff/d.jones/GoodPracticeRNG.pdf for discussion of random
|
|
* number generators (RNGs).
|
|
*/
|
|
|
|
#include <stdbool.h>
|
|
#include <sys/types.h>
|
|
#include <sys/stat.h>
|
|
#include <fcntl.h>
|
|
#include <unistd.h>
|
|
#include <maxscale/random_jkiss.h>
|
|
#include <maxscale/debug.h>
|
|
|
|
/* Public domain code for JKISS RNG - Comment header added */
|
|
|
|
/* If possible, the seed variables will be set from /dev/urandom but
|
|
* should that fail, these arbitrary numbers will be used as a last resort.
|
|
*/
|
|
static unsigned int x = 123456789, y = 987654321, z = 43219876, c = 6543217; /* Seed variables */
|
|
static bool init = false;
|
|
|
|
unsigned int random_jkiss(void)
|
|
{
|
|
unsigned long long t;
|
|
unsigned int result;
|
|
ss_dassert(init);
|
|
|
|
x = 314527869 * x + 1234567;
|
|
y ^= y << 5;
|
|
y ^= y >> 7;
|
|
y ^= y << 22;
|
|
t = 4294584393ULL * z + c;
|
|
c = t >> 32;
|
|
z = t;
|
|
result = x + y + z;
|
|
return result;
|
|
}
|
|
|
|
/* Own code adapted from http://www0.cs.ucl.ac.uk/staff/d.jones/GoodPracticeRNG.pdf */
|
|
|
|
/***
|
|
*
|
|
* Obtain a seed random number from /dev/urandom if available.
|
|
*
|
|
* @return uint Random number
|
|
*
|
|
*/
|
|
static unsigned int random_jkiss_devrand(void)
|
|
{
|
|
int fn;
|
|
unsigned int r;
|
|
|
|
if ((fn = open("/dev/urandom", O_RDONLY)) == -1)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
if (read(fn, &r, sizeof(r)) != sizeof(r))
|
|
{
|
|
r = 0;
|
|
}
|
|
close(fn);
|
|
return r;
|
|
}
|
|
|
|
void random_jkiss_init(void)
|
|
{
|
|
if (!init)
|
|
{
|
|
int newrand, i;
|
|
|
|
if ((newrand = random_jkiss_devrand()) != 0)
|
|
{
|
|
x = newrand;
|
|
}
|
|
|
|
if ((newrand = random_jkiss_devrand()) != 0)
|
|
{
|
|
y = newrand;
|
|
}
|
|
|
|
if ((newrand = random_jkiss_devrand()) != 0)
|
|
{
|
|
z = newrand;
|
|
}
|
|
|
|
if ((newrand = random_jkiss_devrand()) != 0)
|
|
{
|
|
c = newrand % 698769068 + 1; /* Should be less than 698769069 */
|
|
}
|
|
|
|
/* "Warm up" our random number generator */
|
|
for (i = 0; i < 100; i++)
|
|
{
|
|
random_jkiss();
|
|
}
|
|
|
|
init = true;
|
|
}
|
|
}
|