2 * gen_uuid.c --- generate a DCE-compatible uuid
4 * Copyright (C) 1996, 1997, 1998, 1999 Theodore Ts'o.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, and the entire permission notice in its entirety,
12 * including the disclaimer of warranties.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. The name of the author may not be used to endorse or promote
17 * products derived from this software without specific prior
20 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
21 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
22 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
23 * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
24 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
26 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
27 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
28 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
30 * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
40 #include <sys/types.h>
43 #ifdef HAVE_SYS_IOCTL_H
44 #include <sys/ioctl.h>
46 #include <sys/socket.h>
47 #ifdef HAVE_SYS_SOCKIO_H
48 #include <sys/sockio.h>
53 #ifdef HAVE_NETINET_IN_H
54 #include <netinet/in.h>
56 #ifdef HAVE_NET_IF_DL_H
57 #include <net/if_dl.h>
63 #define srand(x) srandom(x)
64 #define rand() random()
67 static int get_random_fd(void)
75 fd = open("/dev/urandom", O_RDONLY);
77 fd = open("/dev/random", O_RDONLY | O_NONBLOCK);
78 srand((getpid() << 16) ^ getuid() ^ tv.tv_sec ^ tv.tv_usec);
80 /* Crank the random number generator a few times */
82 for (i = (tv.tv_sec ^ tv.tv_usec) & 0x1F; i > 0; i--)
89 * Generate a series of random bytes. Use /dev/urandom if possible,
90 * and if not, use srandom/random.
92 static void get_random_bytes(void *buf, int nbytes)
94 int i, n = nbytes, fd = get_random_fd();
96 unsigned char *cp = (unsigned char *) buf;
102 if (lose_counter++ > 16)
113 * We do this all the time, but this is the only source of
114 * randomness if /dev/random/urandom is out to lunch.
116 for (cp = buf, i = 0; i < nbytes; i++)
117 *cp++ ^= (rand() >> 7) & 0xFF;
122 * Get the ethernet hardware address, if we can find it...
124 static int get_node_id(unsigned char *node_id)
128 struct ifreq ifr, *ifrp;
133 #ifdef HAVE_NET_IF_DL_H
134 struct sockaddr_dl *sdlp;
138 * BSD 4.4 defines the size of an ifreq to be
139 * max(sizeof(ifreq), sizeof(ifreq.ifr_name)+ifreq.ifr_addr.sa_len
140 * However, under earlier systems, sa_len isn't present, so the size is
141 * just sizeof(struct ifreq)
145 #define max(a,b) ((a) > (b) ? (a) : (b))
147 #define ifreq_size(i) max(sizeof(struct ifreq),\
148 sizeof((i).ifr_name)+(i).ifr_addr.sa_len)
150 #define ifreq_size(i) sizeof(struct ifreq)
151 #endif /* HAVE_SA_LEN*/
153 sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
157 memset(buf, 0, sizeof(buf));
158 ifc.ifc_len = sizeof(buf);
160 if (ioctl (sd, SIOCGIFCONF, (char *)&ifc) < 0) {
165 for (i = 0; i < n; i+= ifreq_size(*ifrp) ) {
166 ifrp = (struct ifreq *)((char *) ifc.ifc_buf+i);
167 strncpy(ifr.ifr_name, ifrp->ifr_name, IFNAMSIZ);
169 if (ioctl(sd, SIOCGIFHWADDR, &ifr) < 0)
171 a = (unsigned char *) &ifr.ifr_hwaddr.sa_data;
174 if (ioctl(sd, SIOCGENADDR, &ifr) < 0)
176 a = (unsigned char *) ifr.ifr_enaddr;
178 #ifdef HAVE_NET_IF_DL_H
179 sdlp = (struct sockaddr_dl *) &ifrp->ifr_addr;
180 if ((sdlp->sdl_family != AF_LINK) || (sdlp->sdl_alen != 6))
182 a = (unsigned char *) &sdlp->sdl_data[sdlp->sdl_nlen];
185 * XXX we don't have a way of getting the hardware
190 #endif /* HAVE_NET_IF_DL_H */
191 #endif /* SIOCGENADDR */
192 #endif /* SIOCGIFHWADDR */
193 if (!a[0] && !a[1] && !a[2] && !a[3] && !a[4] && !a[5])
196 memcpy(node_id, a, 6);
206 /* Assume that the gettimeofday() has microsecond granularity */
207 #define MAX_ADJUSTMENT 10
209 static int get_clock(uint32_t *clock_high, uint32_t *clock_low, uint16_t *ret_clock_seq)
211 static int adjustment = 0;
212 static struct timeval last = {0, 0};
213 static uint16_t clock_seq;
215 unsigned long long clock_reg;
218 gettimeofday(&tv, 0);
219 if ((last.tv_sec == 0) && (last.tv_usec == 0)) {
220 get_random_bytes(&clock_seq, sizeof(clock_seq));
225 if ((tv.tv_sec < last.tv_sec) ||
226 ((tv.tv_sec == last.tv_sec) &&
227 (tv.tv_usec < last.tv_usec))) {
228 clock_seq = (clock_seq+1) & 0x3FFF;
231 } else if ((tv.tv_sec == last.tv_sec) &&
232 (tv.tv_usec == last.tv_usec)) {
233 if (adjustment >= MAX_ADJUSTMENT)
241 clock_reg = tv.tv_usec*10 + adjustment;
242 clock_reg += ((unsigned long long) tv.tv_sec)*10000000;
243 clock_reg += (((unsigned long long) 0x01B21DD2) << 32) + 0x13814000;
245 *clock_high = clock_reg >> 32;
246 *clock_low = clock_reg;
247 *ret_clock_seq = clock_seq;
251 void uuid_generate_time(uuid_t out)
253 static unsigned char node_id[6];
254 static int has_init = 0;
259 if (get_node_id(node_id) <= 0) {
260 get_random_bytes(node_id, 6);
262 * Set multicast bit, to prevent conflicts
263 * with IEEE 802 addresses obtained from
270 get_clock(&clock_mid, &uu.time_low, &uu.clock_seq);
271 uu.clock_seq |= 0x8000;
272 uu.time_mid = (uint16_t) clock_mid;
273 uu.time_hi_and_version = ((clock_mid >> 16) & 0x0FFF) | 0x1000;
274 memcpy(uu.node, node_id, 6);
278 void uuid_generate_random(uuid_t out)
283 get_random_bytes(buf, sizeof(buf));
284 uuid_unpack(buf, &uu);
286 uu.clock_seq = (uu.clock_seq & 0x3FFF) | 0x8000;
287 uu.time_hi_and_version = (uu.time_hi_and_version & 0x0FFF) | 0x4000;
292 * This is the generic front-end to uuid_generate_random and
293 * uuid_generate_time. It uses uuid_generate_random only if
294 * /dev/urandom is available, since otherwise we won't have
295 * high-quality randomness.
297 void uuid_generate(uuid_t out)
299 if (get_random_fd() >= 0)
300 uuid_generate_random(out);
302 uuid_generate_time(out);