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;
123 * Get the ethernet hardware address, if we can find it...
125 static int get_node_id(unsigned char *node_id)
129 struct ifreq ifr, *ifrp;
134 #ifdef HAVE_NET_IF_DL_H
135 struct sockaddr_dl *sdlp;
139 * BSD 4.4 defines the size of an ifreq to be
140 * max(sizeof(ifreq), sizeof(ifreq.ifr_name)+ifreq.ifr_addr.sa_len
141 * However, under earlier systems, sa_len isn't present, so the size is
142 * just sizeof(struct ifreq)
146 #define max(a,b) ((a) > (b) ? (a) : (b))
148 #define ifreq_size(i) max(sizeof(struct ifreq),\
149 sizeof((i).ifr_name)+(i).ifr_addr.sa_len)
151 #define ifreq_size(i) sizeof(struct ifreq)
152 #endif /* HAVE_SA_LEN*/
154 sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
158 memset(buf, 0, sizeof(buf));
159 ifc.ifc_len = sizeof(buf);
161 if (ioctl (sd, SIOCGIFCONF, (char *)&ifc) < 0) {
166 for (i = 0; i < n; i+= ifreq_size(*ifrp) ) {
167 ifrp = (struct ifreq *)((char *) ifc.ifc_buf+i);
168 strncpy(ifr.ifr_name, ifrp->ifr_name, IFNAMSIZ);
170 if (ioctl(sd, SIOCGIFHWADDR, &ifr) < 0)
172 a = (unsigned char *) &ifr.ifr_hwaddr.sa_data;
175 if (ioctl(sd, SIOCGENADDR, &ifr) < 0)
177 a = (unsigned char *) ifr.ifr_enaddr;
179 #ifdef HAVE_NET_IF_DL_H
180 sdlp = (struct sockaddr_dl *) &ifrp->ifr_addr;
181 if ((sdlp->sdl_family != AF_LINK) || (sdlp->sdl_alen != 6))
183 a = (unsigned char *) &sdlp->sdl_data[sdlp->sdl_nlen];
186 * XXX we don't have a way of getting the hardware
191 #endif /* HAVE_NET_IF_DL_H */
192 #endif /* SIOCGENADDR */
193 #endif /* SIOCGIFHWADDR */
194 if (!a[0] && !a[1] && !a[2] && !a[3] && !a[4] && !a[5])
197 memcpy(node_id, a, 6);
207 /* Assume that the gettimeofday() has microsecond granularity */
208 #define MAX_ADJUSTMENT 10
210 static int get_clock(uint32_t *clock_high, uint32_t *clock_low, uint16_t *ret_clock_seq)
212 static int adjustment = 0;
213 static struct timeval last = {0, 0};
214 static uint16_t clock_seq;
216 unsigned long long clock_reg;
219 gettimeofday(&tv, 0);
220 if ((last.tv_sec == 0) && (last.tv_usec == 0)) {
221 get_random_bytes(&clock_seq, sizeof(clock_seq));
226 if ((tv.tv_sec < last.tv_sec) ||
227 ((tv.tv_sec == last.tv_sec) &&
228 (tv.tv_usec < last.tv_usec))) {
229 clock_seq = (clock_seq+1) & 0x3FFF;
232 } else if ((tv.tv_sec == last.tv_sec) &&
233 (tv.tv_usec == last.tv_usec)) {
234 if (adjustment >= MAX_ADJUSTMENT)
242 clock_reg = tv.tv_usec*10 + adjustment;
243 clock_reg += ((unsigned long long) tv.tv_sec)*10000000;
244 clock_reg += (((unsigned long long) 0x01B21DD2) << 32) + 0x13814000;
246 *clock_high = clock_reg >> 32;
247 *clock_low = clock_reg;
248 *ret_clock_seq = clock_seq;
252 void uuid_generate_time(uuid_t out)
254 static unsigned char node_id[6];
255 static int has_init = 0;
260 if (get_node_id(node_id) <= 0) {
261 get_random_bytes(node_id, 6);
263 * Set multicast bit, to prevent conflicts
264 * with IEEE 802 addresses obtained from
271 get_clock(&clock_mid, &uu.time_low, &uu.clock_seq);
272 uu.clock_seq |= 0x8000;
273 uu.time_mid = (uint16_t) clock_mid;
274 uu.time_hi_and_version = ((clock_mid >> 16) & 0x0FFF) | 0x1000;
275 memcpy(uu.node, node_id, 6);
279 void uuid_generate_random(uuid_t out)
284 get_random_bytes(buf, sizeof(buf));
285 uuid_unpack(buf, &uu);
287 uu.clock_seq = (uu.clock_seq & 0x3FFF) | 0x8000;
288 uu.time_hi_and_version = (uu.time_hi_and_version & 0x0FFF) | 0x4000;
293 * This is the generic front-end to uuid_generate_random and
294 * uuid_generate_time. It uses uuid_generate_random only if
295 * /dev/urandom is available, since otherwise we won't have
296 * high-quality randomness.
298 void uuid_generate(uuid_t out)
300 if (get_random_fd() >= 0)
301 uuid_generate_random(out);
303 uuid_generate_time(out);