1 /* vi: set sw=4 ts=4: */
3 * gen_uuid.c --- generate a DCE-compatible uuid
5 * Copyright (C) 1996, 1997, 1998, 1999 Theodore Ts'o.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, and the entire permission notice in its entirety,
13 * including the disclaimer of warranties.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. The name of the author may not be used to endorse or promote
18 * products derived from this software without specific prior
21 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
22 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
24 * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
25 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
26 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
27 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
28 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
29 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
31 * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
41 #include <sys/types.h>
45 #ifdef HAVE_SYS_IOCTL_H
46 #include <sys/ioctl.h>
48 #include <sys/socket.h>
49 #ifdef HAVE_SYS_SOCKIO_H
50 #include <sys/sockio.h>
55 #ifdef HAVE_NETINET_IN_H
56 #include <netinet/in.h>
58 #ifdef HAVE_NET_IF_DL_H
59 #include <net/if_dl.h>
65 #define srand(x) srandom(x)
66 #define rand() random()
69 static int get_random_fd(void)
77 fd = open("/dev/urandom", O_RDONLY);
79 fd = open("/dev/random", O_RDONLY | O_NONBLOCK);
80 srand((getpid() << 16) ^ getuid() ^ tv.tv_sec ^ tv.tv_usec);
82 /* Crank the random number generator a few times */
84 for (i = (tv.tv_sec ^ tv.tv_usec) & 0x1F; i > 0; i--)
91 * Generate a series of random bytes. Use /dev/urandom if possible,
92 * and if not, use srandom/random.
94 static void get_random_bytes(void *buf, int nbytes)
96 int i, n = nbytes, fd = get_random_fd();
98 unsigned char *cp = (unsigned char *) buf;
104 if (lose_counter++ > 16)
115 * We do this all the time, but this is the only source of
116 * randomness if /dev/random/urandom is out to lunch.
118 for (cp = buf, i = 0; i < nbytes; i++)
119 *cp++ ^= (rand() >> 7) & 0xFF;
124 * Get the ethernet hardware address, if we can find it...
126 static int get_node_id(unsigned char *node_id)
130 struct ifreq ifr, *ifrp;
135 #ifdef HAVE_NET_IF_DL_H
136 struct sockaddr_dl *sdlp;
140 * BSD 4.4 defines the size of an ifreq to be
141 * max(sizeof(ifreq), sizeof(ifreq.ifr_name)+ifreq.ifr_addr.sa_len
142 * However, under earlier systems, sa_len isn't present, so the size is
143 * just sizeof(struct ifreq)
147 #define max(a,b) ((a) > (b) ? (a) : (b))
149 #define ifreq_size(i) max(sizeof(struct ifreq),\
150 sizeof((i).ifr_name)+(i).ifr_addr.sa_len)
152 #define ifreq_size(i) sizeof(struct ifreq)
153 #endif /* HAVE_SA_LEN*/
155 sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
159 memset(buf, 0, sizeof(buf));
160 ifc.ifc_len = sizeof(buf);
162 if (ioctl (sd, SIOCGIFCONF, (char *)&ifc) < 0) {
167 for (i = 0; i < n; i+= ifreq_size(*ifrp) ) {
168 ifrp = (struct ifreq *)((char *) ifc.ifc_buf+i);
169 strncpy(ifr.ifr_name, ifrp->ifr_name, IFNAMSIZ);
171 if (ioctl(sd, SIOCGIFHWADDR, &ifr) < 0)
173 a = (unsigned char *) &ifr.ifr_hwaddr.sa_data;
176 if (ioctl(sd, SIOCGENADDR, &ifr) < 0)
178 a = (unsigned char *) ifr.ifr_enaddr;
180 #ifdef HAVE_NET_IF_DL_H
181 sdlp = (struct sockaddr_dl *) &ifrp->ifr_addr;
182 if ((sdlp->sdl_family != AF_LINK) || (sdlp->sdl_alen != 6))
184 a = (unsigned char *) &sdlp->sdl_data[sdlp->sdl_nlen];
187 * XXX we don't have a way of getting the hardware
192 #endif /* HAVE_NET_IF_DL_H */
193 #endif /* SIOCGENADDR */
194 #endif /* SIOCGIFHWADDR */
195 if (!a[0] && !a[1] && !a[2] && !a[3] && !a[4] && !a[5])
198 memcpy(node_id, a, 6);
208 /* Assume that the gettimeofday() has microsecond granularity */
209 #define MAX_ADJUSTMENT 10
211 static int get_clock(uint32_t *clock_high, uint32_t *clock_low, uint16_t *ret_clock_seq)
213 static int adjustment = 0;
214 static struct timeval last = {0, 0};
215 static uint16_t clock_seq;
217 unsigned long long clock_reg;
220 gettimeofday(&tv, 0);
221 if ((last.tv_sec == 0) && (last.tv_usec == 0)) {
222 get_random_bytes(&clock_seq, sizeof(clock_seq));
227 if ((tv.tv_sec < last.tv_sec) ||
228 ((tv.tv_sec == last.tv_sec) &&
229 (tv.tv_usec < last.tv_usec))) {
230 clock_seq = (clock_seq+1) & 0x3FFF;
233 } else if ((tv.tv_sec == last.tv_sec) &&
234 (tv.tv_usec == last.tv_usec)) {
235 if (adjustment >= MAX_ADJUSTMENT)
243 clock_reg = tv.tv_usec*10 + adjustment;
244 clock_reg += ((unsigned long long) tv.tv_sec)*10000000;
245 clock_reg += (((unsigned long long) 0x01B21DD2) << 32) + 0x13814000;
247 *clock_high = clock_reg >> 32;
248 *clock_low = clock_reg;
249 *ret_clock_seq = clock_seq;
253 void uuid_generate_time(uuid_t out)
255 static unsigned char node_id[6];
256 static int has_init = 0;
261 if (get_node_id(node_id) <= 0) {
262 get_random_bytes(node_id, 6);
264 * Set multicast bit, to prevent conflicts
265 * with IEEE 802 addresses obtained from
272 get_clock(&clock_mid, &uu.time_low, &uu.clock_seq);
273 uu.clock_seq |= 0x8000;
274 uu.time_mid = (uint16_t) clock_mid;
275 uu.time_hi_and_version = ((clock_mid >> 16) & 0x0FFF) | 0x1000;
276 memcpy(uu.node, node_id, 6);
280 void uuid_generate_random(uuid_t out)
285 get_random_bytes(buf, sizeof(buf));
286 uuid_unpack(buf, &uu);
288 uu.clock_seq = (uu.clock_seq & 0x3FFF) | 0x8000;
289 uu.time_hi_and_version = (uu.time_hi_and_version & 0x0FFF) | 0x4000;
294 * This is the generic front-end to uuid_generate_random and
295 * uuid_generate_time. It uses uuid_generate_random only if
296 * /dev/urandom is available, since otherwise we won't have
297 * high-quality randomness.
299 void uuid_generate(uuid_t out)
301 if (get_random_fd() >= 0)
302 uuid_generate_random(out);
304 uuid_generate_time(out);