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/*
* Copyright (C) 2012 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see
* <http://www.gnu.org/licenses/>.
*
* Authors:
* Daniel P. Berrange <berrange@redhat.com>
*/
#include <config.h>
#include <stdlib.h>
#include <inttypes.h>
#include <math.h>
#include <strings.h>
#include "virrandom.h"
#include "threads.h"
#include "count-one-bits.h"
#include "util.h"
#include "virterror_internal.h"
#include "logging.h"
#define VIR_FROM_THIS VIR_FROM_NONE
static char randomState[128];
static struct random_data randomData;
static virMutex randomLock;
static int
virRandomOnceInit(void)
{
unsigned int seed = time(NULL) ^ getpid();
#if 0
/* Normally we want a decent seed. But if reproducible debugging
* of a fixed pseudo-random sequence is ever required, uncomment
* this block to let an environment variable force the seed. */
const char *debug = getenv("VIR_DEBUG_RANDOM_SEED");
if (debug && virStrToLong_ui(debug, NULL, 0, &seed) < 0)
return -1;
#endif
if (virMutexInit(&randomLock) < 0)
return -1;
if (initstate_r(seed,
randomState,
sizeof(randomState),
&randomData) < 0)
return -1;
return 0;
}
VIR_ONCE_GLOBAL_INIT(virRandom)
/* The algorithm of virRandomBits requires that RAND_MAX == 2^n-1 for
* some n; gnulib's random_r meets this property. */
verify(((RAND_MAX + 1U) & RAND_MAX) == 0);
/**
* virRandomBits:
* @nbits: Number of bits of randommess required
*
* Generate an evenly distributed random number between [0,2^nbits), where
* @nbits must be in the range (0,64].
*
* Return: a random number with @nbits entropy
*/
uint64_t virRandomBits(int nbits)
{
int bits_per_iter = count_one_bits(RAND_MAX);
uint64_t ret = 0;
int32_t bits;
if (virRandomInitialize() < 0) {
/* You're already hosed, so this particular non-random value
* isn't any worse. */
VIR_WARN("random number generation is broken");
return 0;
}
virMutexLock(&randomLock);
while (nbits > bits_per_iter) {
random_r(&randomData, &bits);
ret = (ret << bits_per_iter) | (bits & RAND_MAX);
nbits -= bits_per_iter;
}
random_r(&randomData, &bits);
ret = (ret << nbits) | (bits & ((1 << nbits) - 1));
virMutexUnlock(&randomLock);
return ret;
}
/**
* virRandom:
*
* Generate an evenly distributed random number between [0.0,1.0)
*
* Return: a random number with 48 bits of entropy
*/
double virRandom(void)
{
uint64_t val = virRandomBits(48);
return ldexp(val, -48);
}
/**
* virRandomInt:
* @max: upper limit
*
* Generate an evenly distributed random integer between [0, @max)
*
* Return: a random number between [0,@max)
*/
uint32_t virRandomInt(uint32_t max)
{
if ((max & (max - 1)) == 0)
return virRandomBits(ffs(max) - 1);
double val = virRandom();
return val * max;
}
#define QUMRANET_OUI "001a4a"
#define VMWARE_OUI "000569"
#define MICROSOFT_OUI "0050f2"
#define XEN_OUI "00163e"
int
virRandomGenerateWWN(char **wwn,
const char *virt_type) {
const char *oui = NULL;
if (!virt_type) {
virReportError(VIR_ERR_INVALID_ARG, "%s",
_("argument virt_type must not be NULL"));
return -1;
}
if (STREQ(virt_type, "QEMU")) {
oui = QUMRANET_OUI;
} else if (STREQ(virt_type, "Xen") ||
STREQ(virt_type, "xenlight") ||
STREQ(virt_type, "XenAPI")) {
oui = XEN_OUI;
} else if (STREQ(virt_type, "ESX") ||
STREQ(virt_type, "VMWARE")) {
oui = VMWARE_OUI;
} else if (STREQ(virt_type, "HYPER-V")) {
oui = MICROSOFT_OUI;
} else {
virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
_("Unsupported virt type"));
return -1;
}
if (virAsprintf(wwn, "5" "%s%09llx", oui,
(unsigned long long)virRandomBits(36)) < 0) {
virReportOOMError();
return -1;
}
return 0;
}
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