busybox/e2fsprogs/uuid/gen_uuid.c
2006-10-05 10:17:08 +00:00

306 lines
7.6 KiB
C

/* vi: set sw=4 ts=4: */
/*
* gen_uuid.c --- generate a DCE-compatible uuid
*
* Copyright (C) 1996, 1997, 1998, 1999 Theodore Ts'o.
*
* %Begin-Header%
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, and the entire permission notice in its entirety,
* including the disclaimer of warranties.
* 2. 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.
* 3. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
* WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR 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 NOT ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
* %End-Header%
*/
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <sys/time.h>
#ifdef HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>
#endif
#include <sys/socket.h>
#ifdef HAVE_SYS_SOCKIO_H
#include <sys/sockio.h>
#endif
#ifdef HAVE_NET_IF_H
#include <net/if.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_NET_IF_DL_H
#include <net/if_dl.h>
#endif
#include "uuidP.h"
#ifdef HAVE_SRANDOM
#define srand(x) srandom(x)
#define rand() random()
#endif
static int get_random_fd(void)
{
struct timeval tv;
static int fd = -2;
int i;
if (fd == -2) {
gettimeofday(&tv, 0);
fd = open("/dev/urandom", O_RDONLY);
if (fd == -1)
fd = open("/dev/random", O_RDONLY | O_NONBLOCK);
srand((getpid() << 16) ^ getuid() ^ tv.tv_sec ^ tv.tv_usec);
}
/* Crank the random number generator a few times */
gettimeofday(&tv, 0);
for (i = (tv.tv_sec ^ tv.tv_usec) & 0x1F; i > 0; i--)
rand();
return fd;
}
/*
* Generate a series of random bytes. Use /dev/urandom if possible,
* and if not, use srandom/random.
*/
static void get_random_bytes(void *buf, int nbytes)
{
int i, n = nbytes, fd = get_random_fd();
int lose_counter = 0;
unsigned char *cp = (unsigned char *) buf;
if (fd >= 0) {
while (n > 0) {
i = read(fd, cp, n);
if (i <= 0) {
if (lose_counter++ > 16)
break;
continue;
}
n -= i;
cp += i;
lose_counter = 0;
}
}
/*
* We do this all the time, but this is the only source of
* randomness if /dev/random/urandom is out to lunch.
*/
for (cp = buf, i = 0; i < nbytes; i++)
*cp++ ^= (rand() >> 7) & 0xFF;
return;
}
/*
* Get the ethernet hardware address, if we can find it...
*/
static int get_node_id(unsigned char *node_id)
{
#ifdef HAVE_NET_IF_H
int sd;
struct ifreq ifr, *ifrp;
struct ifconf ifc;
char buf[1024];
int n, i;
unsigned char *a;
#ifdef HAVE_NET_IF_DL_H
struct sockaddr_dl *sdlp;
#endif
/*
* BSD 4.4 defines the size of an ifreq to be
* max(sizeof(ifreq), sizeof(ifreq.ifr_name)+ifreq.ifr_addr.sa_len
* However, under earlier systems, sa_len isn't present, so the size is
* just sizeof(struct ifreq)
*/
#ifdef HAVE_SA_LEN
#ifndef max
#define max(a,b) ((a) > (b) ? (a) : (b))
#endif
#define ifreq_size(i) max(sizeof(struct ifreq),\
sizeof((i).ifr_name)+(i).ifr_addr.sa_len)
#else
#define ifreq_size(i) sizeof(struct ifreq)
#endif /* HAVE_SA_LEN*/
sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
if (sd < 0) {
return -1;
}
memset(buf, 0, sizeof(buf));
ifc.ifc_len = sizeof(buf);
ifc.ifc_buf = buf;
if (ioctl (sd, SIOCGIFCONF, (char *)&ifc) < 0) {
close(sd);
return -1;
}
n = ifc.ifc_len;
for (i = 0; i < n; i+= ifreq_size(*ifrp) ) {
ifrp = (struct ifreq *)((char *) ifc.ifc_buf+i);
strncpy(ifr.ifr_name, ifrp->ifr_name, IFNAMSIZ);
#ifdef SIOCGIFHWADDR
if (ioctl(sd, SIOCGIFHWADDR, &ifr) < 0)
continue;
a = (unsigned char *) &ifr.ifr_hwaddr.sa_data;
#else
#ifdef SIOCGENADDR
if (ioctl(sd, SIOCGENADDR, &ifr) < 0)
continue;
a = (unsigned char *) ifr.ifr_enaddr;
#else
#ifdef HAVE_NET_IF_DL_H
sdlp = (struct sockaddr_dl *) &ifrp->ifr_addr;
if ((sdlp->sdl_family != AF_LINK) || (sdlp->sdl_alen != 6))
continue;
a = (unsigned char *) &sdlp->sdl_data[sdlp->sdl_nlen];
#else
/*
* XXX we don't have a way of getting the hardware
* address
*/
close(sd);
return 0;
#endif /* HAVE_NET_IF_DL_H */
#endif /* SIOCGENADDR */
#endif /* SIOCGIFHWADDR */
if (!a[0] && !a[1] && !a[2] && !a[3] && !a[4] && !a[5])
continue;
if (node_id) {
memcpy(node_id, a, 6);
close(sd);
return 1;
}
}
close(sd);
#endif
return 0;
}
/* Assume that the gettimeofday() has microsecond granularity */
#define MAX_ADJUSTMENT 10
static int get_clock(uint32_t *clock_high, uint32_t *clock_low, uint16_t *ret_clock_seq)
{
static int adjustment = 0;
static struct timeval last = {0, 0};
static uint16_t clock_seq;
struct timeval tv;
unsigned long long clock_reg;
try_again:
gettimeofday(&tv, 0);
if ((last.tv_sec == 0) && (last.tv_usec == 0)) {
get_random_bytes(&clock_seq, sizeof(clock_seq));
clock_seq &= 0x3FFF;
last = tv;
last.tv_sec--;
}
if ((tv.tv_sec < last.tv_sec) ||
((tv.tv_sec == last.tv_sec) &&
(tv.tv_usec < last.tv_usec))) {
clock_seq = (clock_seq+1) & 0x3FFF;
adjustment = 0;
last = tv;
} else if ((tv.tv_sec == last.tv_sec) &&
(tv.tv_usec == last.tv_usec)) {
if (adjustment >= MAX_ADJUSTMENT)
goto try_again;
adjustment++;
} else {
adjustment = 0;
last = tv;
}
clock_reg = tv.tv_usec*10 + adjustment;
clock_reg += ((unsigned long long) tv.tv_sec)*10000000;
clock_reg += (((unsigned long long) 0x01B21DD2) << 32) + 0x13814000;
*clock_high = clock_reg >> 32;
*clock_low = clock_reg;
*ret_clock_seq = clock_seq;
return 0;
}
void uuid_generate_time(uuid_t out)
{
static unsigned char node_id[6];
static int has_init = 0;
struct uuid uu;
uint32_t clock_mid;
if (!has_init) {
if (get_node_id(node_id) <= 0) {
get_random_bytes(node_id, 6);
/*
* Set multicast bit, to prevent conflicts
* with IEEE 802 addresses obtained from
* network cards
*/
node_id[0] |= 0x01;
}
has_init = 1;
}
get_clock(&clock_mid, &uu.time_low, &uu.clock_seq);
uu.clock_seq |= 0x8000;
uu.time_mid = (uint16_t) clock_mid;
uu.time_hi_and_version = ((clock_mid >> 16) & 0x0FFF) | 0x1000;
memcpy(uu.node, node_id, 6);
uuid_pack(&uu, out);
}
void uuid_generate_random(uuid_t out)
{
uuid_t buf;
struct uuid uu;
get_random_bytes(buf, sizeof(buf));
uuid_unpack(buf, &uu);
uu.clock_seq = (uu.clock_seq & 0x3FFF) | 0x8000;
uu.time_hi_and_version = (uu.time_hi_and_version & 0x0FFF) | 0x4000;
uuid_pack(&uu, out);
}
/*
* This is the generic front-end to uuid_generate_random and
* uuid_generate_time. It uses uuid_generate_random only if
* /dev/urandom is available, since otherwise we won't have
* high-quality randomness.
*/
void uuid_generate(uuid_t out)
{
if (get_random_fd() >= 0)
uuid_generate_random(out);
else
uuid_generate_time(out);
}