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/*
* Routines to get randomness.
*/
#include <syslog.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <limits.h>
#include "pids.h"
#include "random.h"
#include "sanitise.h" // interesting_numbers
#include "types.h"
unsigned int rand_bool(void)
{
return rand() % 2;
}
static unsigned int rand_single_bit(unsigned char size)
{
return (1L << (rand() % size));
}
/*
* set N bits, where N= rand(0 - WORDSIZE/2)
*/
static unsigned long randbits(int limit)
{
unsigned int num = rand() % limit / 2;
unsigned int i;
unsigned long r = 0;
for (i = 0; i < num; i++)
r |= (1 << (rand() % (limit - 1)));
return r;
}
/*
* Based on very similar routine stolen from iknowthis. Thanks Tavis.
*/
static unsigned long taviso(void)
{
unsigned long r = 0;
switch (rand() % 4) {
case 0: r = rand() & rand();
#if __WORDSIZE == 64
r <<= 32;
r |= rand() & rand();
#endif
break;
case 1: r = rand() % rand();
#if __WORDSIZE == 64
r <<= 32;
r |= rand() % rand();
#endif
break;
case 2: r = rand() | rand();
#if __WORDSIZE == 64
r <<= 32;
r |= rand() | rand();
#endif
break;
case 3: r = rand();
#if __WORDSIZE == 64
r <<= 32;
r |= rand();
#endif
break;
default:
break;
}
return r;
}
/*
* Pick 8 random bytes, and concatenate them into a long.
*/
static unsigned long rand8x8(void)
{
unsigned long r = 0UL;
unsigned int i;
for (i = (rand() % 7) + 1; i > 0; --i)
r = (r << 8) | rand() % 256;
return r;
}
/*
* Pick 1 random byte, and repeat it through a long.
*/
static unsigned long rept8(unsigned int num)
{
unsigned long r = 0UL;
unsigned int i;
unsigned char c;
c = rand() % 256;
for (i = rand() % (num - 1) ; i > 0; --i)
r = (r << 8) | c;
return r;
}
/*
* "selector" function for 32bit random.
* only called from rand32()
*/
static unsigned int __rand32(void)
{
unsigned long r = 0;
switch (rand() % 7) {
case 0: r = rand_single_bit(32);
break;
case 1: r = randbits(32);
break;
case 2: r = rand();
break;
case 3: r = taviso();
break;
case 4: r = rand8x8();
break;
case 5: r = rept8(4);
break;
case 6: return get_interesting_32bit_value();
default:
break;
}
return r;
}
/*
* Generate, and munge a 32bit number.
*/
unsigned int rand32(void)
{
unsigned long r = 0;
r = __rand32();
if (rand_bool()) {
unsigned int i;
unsigned int rounds;
/* mangle it. */
rounds = rand() % 3;
for (i = 0; i < rounds; i++) {
switch (rand_bool()) {
case 0: r |= __rand32();
break;
case 1: r ^= __rand32();
break;
default:
break;
}
}
}
/* Sometimes deduct it from INT_MAX */
if (rand_bool())
r = INT_MAX - r;
/* Sometimes flip sign */
if (rand_bool())
r |= (1L << 31);
/* we might get lucky if something is counting ints/longs etc. */
if (rand() % 100 < 25) {
int _div = 1 << ((rand() % 4) + 1); /* 2,4,8 or 16 */
r /= _div;
}
/* limit the size */
switch (rand() % 4) {
case 0: r &= 0xff;
break;
case 1: r &= 0xffff;
break;
case 2: r &= 0xffffff;
break;
default:
break;
}
return r;
}
/*
* Generate and munge a 64bit number.
*/
u64 rand64(void)
{
unsigned long r = 0;
if (rand_bool()) {
/* 32-bit ranges. */
r = rand32();
} else {
/* 33:64-bit ranges. */
switch (rand() % 7) {
case 0: r = rand_single_bit(64);
break;
case 1: r = randbits(64);
break;
case 2: r = rand32() | rand32() << 31;
break;
case 3: r = taviso();
break;
case 4: r = rand8x8();
break;
case 5: r = rept8(8);
break;
/* Sometimes pick a not-so-random number. */
case 6: return get_interesting_value();
default:
break;
}
/* limit the size */
switch (rand() % 4) {
case 0: r &= 0x000000ffffffffffULL;
break;
case 1: r &= 0x0000ffffffffffffULL;
break;
case 2: r &= 0x00ffffffffffffffULL;
break;
default:
break;
}
}
/* Sometimes invert the generated number. */
if (rand_bool())
r = ~r;
/* increase distribution in MSB */
if ((rand() % 10)) {
unsigned int i;
unsigned int rounds;
rounds = rand() % 4;
for (i = 0; i < rounds; i++)
r |= (1L << ((__WORDSIZE - 1) - (rand() % 8)));
}
/* randomly flip sign bit. */
if (rand_bool())
r |= (1L << (__WORDSIZE - 1));
return r;
}
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