gen_uuid.c revision e70f32b79d29e287f8347c5d41c6716f094cc654 
1/*
2 * gen_uuid.c --- generate a DCE-compatible uuid
3 *
4 * Copyright (C) 1996, 1997, 1998, 1999 Theodore Ts'o.
5 *
6 * %Begin-Header%
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
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
18 *    written permission.
19 *
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
31 * DAMAGE.
32 * %End-Header%
33 */
34
35/*
36 * Force inclusion of SVID stuff since we need it if we're compiling in
37 * gcc-wall wall mode
38 */
39#define _SVID_SOURCE
40
41#include <stdio.h>
42#ifdef HAVE_UNISTD_H
43#include <unistd.h>
44#endif
45#ifdef HAVE_STDLIB_H
46#include <stdlib.h>
47#endif
48#include <string.h>
49#include <fcntl.h>
50#include <errno.h>
51#include <sys/types.h>
52#include <sys/time.h>
53#include <sys/wait.h>
54#include <sys/stat.h>
55#include <sys/file.h>
56#ifdef HAVE_SYS_IOCTL_H
57#include <sys/ioctl.h>
58#endif
59#ifdef HAVE_SYS_SOCKET_H
60#include <sys/socket.h>
61#endif
62#include <sys/un.h>
63#ifdef HAVE_SYS_SOCKIO_H
64#include <sys/sockio.h>
65#endif
66#ifdef HAVE_NET_IF_H
67#include <net/if.h>
68#endif
69#ifdef HAVE_NETINET_IN_H
70#include <netinet/in.h>
71#endif
72#ifdef HAVE_NET_IF_DL_H
73#include <net/if_dl.h>
74#endif
75#if defined(__linux__) && defined(HAVE_SYS_SYSCALL_H)
76#include <sys/syscall.h>
77#endif
78
79#include "uuidP.h"
80#include "uuidd.h"
81
82#ifdef HAVE_SRANDOM
83#define srand(x) 	srandom(x)
84#define rand() 		random()
85#endif
86
87#ifdef TLS
88#define THREAD_LOCAL static TLS
89#else
90#define THREAD_LOCAL static
91#endif
92
93#if defined(__linux__) && defined(__NR_gettid) && defined(HAVE_JRAND48)
94#define DO_JRAND_MIX
95THREAD_LOCAL unsigned short jrand_seed[3];
96#endif
97
98static int get_random_fd(void)
99{
100	struct timeval	tv;
101	static int	fd = -2;
102	int		i;
103
104	if (fd == -2) {
105		gettimeofday(&tv, 0);
106		fd = open("/dev/urandom", O_RDONLY);
107		if (fd == -1)
108			fd = open("/dev/random", O_RDONLY | O_NONBLOCK);
109		if (fd >= 0) {
110			i = fcntl(fd, F_GETFD);
111			if (i >= 0)
112				fcntl(fd, F_SETFD, i | FD_CLOEXEC);
113		}
114		srand((getpid() << 16) ^ getuid() ^ tv.tv_sec ^ tv.tv_usec);
115#ifdef DO_JRAND_MIX
116		jrand_seed[0] = getpid() ^ (tv.tv_sec & 0xFFFF);
117		jrand_seed[1] = getppid() ^ (tv.tv_usec & 0xFFFF);
118		jrand_seed[2] = (tv.tv_sec ^ tv.tv_usec) >> 16;
119#endif
120	}
121	/* Crank the random number generator a few times */
122	gettimeofday(&tv, 0);
123	for (i = (tv.tv_sec ^ tv.tv_usec) & 0x1F; i > 0; i--)
124		rand();
125	return fd;
126}
127
128
129/*
130 * Generate a series of random bytes.  Use /dev/urandom if possible,
131 * and if not, use srandom/random.
132 */
133static void get_random_bytes(void *buf, int nbytes)
134{
135	int i, n = nbytes, fd = get_random_fd();
136	int lose_counter = 0;
137	unsigned char *cp = (unsigned char *) buf;
138	unsigned short tmp_seed[3];
139
140	if (fd >= 0) {
141		while (n > 0) {
142			i = read(fd, cp, n);
143			if (i <= 0) {
144				if (lose_counter++ > 16)
145					break;
146				continue;
147			}
148			n -= i;
149			cp += i;
150			lose_counter = 0;
151		}
152	}
153
154	/*
155	 * We do this all the time, but this is the only source of
156	 * randomness if /dev/random/urandom is out to lunch.
157	 */
158	for (cp = buf, i = 0; i < nbytes; i++)
159		*cp++ ^= (rand() >> 7) & 0xFF;
160#ifdef DO_JRAND_MIX
161	memcpy(tmp_seed, jrand_seed, sizeof(tmp_seed));
162	jrand_seed[2] = jrand_seed[2] ^ syscall(__NR_gettid);
163	for (cp = buf, i = 0; i < nbytes; i++)
164		*cp++ ^= (jrand48(tmp_seed) >> 7) & 0xFF;
165	memcpy(jrand_seed, tmp_seed,
166	       sizeof(jrand_seed)-sizeof(unsigned short));
167#endif
168
169	return;
170}
171
172/*
173 * Get the ethernet hardware address, if we can find it...
174 */
175static int get_node_id(unsigned char *node_id)
176{
177#ifdef HAVE_NET_IF_H
178	int 		sd;
179	struct ifreq 	ifr, *ifrp;
180	struct ifconf 	ifc;
181	char buf[1024];
182	int		n, i;
183	unsigned char 	*a;
184#ifdef HAVE_NET_IF_DL_H
185	struct sockaddr_dl *sdlp;
186#endif
187
188/*
189 * BSD 4.4 defines the size of an ifreq to be
190 * max(sizeof(ifreq), sizeof(ifreq.ifr_name)+ifreq.ifr_addr.sa_len
191 * However, under earlier systems, sa_len isn't present, so the size is
192 * just sizeof(struct ifreq)
193 */
194#ifdef HAVE_SA_LEN
195#ifndef max
196#define max(a,b) ((a) > (b) ? (a) : (b))
197#endif
198#define ifreq_size(i) max(sizeof(struct ifreq),\
199     sizeof((i).ifr_name)+(i).ifr_addr.sa_len)
200#else
201#define ifreq_size(i) sizeof(struct ifreq)
202#endif /* HAVE_SA_LEN*/
203
204	sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
205	if (sd < 0) {
206		return -1;
207	}
208	memset(buf, 0, sizeof(buf));
209	ifc.ifc_len = sizeof(buf);
210	ifc.ifc_buf = buf;
211	if (ioctl (sd, SIOCGIFCONF, (char *)&ifc) < 0) {
212		close(sd);
213		return -1;
214	}
215	n = ifc.ifc_len;
216	for (i = 0; i < n; i+= ifreq_size(*ifrp) ) {
217		ifrp = (struct ifreq *)((char *) ifc.ifc_buf+i);
218		strncpy(ifr.ifr_name, ifrp->ifr_name, IFNAMSIZ);
219#ifdef SIOCGIFHWADDR
220		if (ioctl(sd, SIOCGIFHWADDR, &ifr) < 0)
221			continue;
222		a = (unsigned char *) &ifr.ifr_hwaddr.sa_data;
223#else
224#ifdef SIOCGENADDR
225		if (ioctl(sd, SIOCGENADDR, &ifr) < 0)
226			continue;
227		a = (unsigned char *) ifr.ifr_enaddr;
228#else
229#ifdef HAVE_NET_IF_DL_H
230		sdlp = (struct sockaddr_dl *) &ifrp->ifr_addr;
231		if ((sdlp->sdl_family != AF_LINK) || (sdlp->sdl_alen != 6))
232			continue;
233		a = (unsigned char *) &sdlp->sdl_data[sdlp->sdl_nlen];
234#else
235		/*
236		 * XXX we don't have a way of getting the hardware
237		 * address
238		 */
239		close(sd);
240		return 0;
241#endif /* HAVE_NET_IF_DL_H */
242#endif /* SIOCGENADDR */
243#endif /* SIOCGIFHWADDR */
244		if (!a[0] && !a[1] && !a[2] && !a[3] && !a[4] && !a[5])
245			continue;
246		if (node_id) {
247			memcpy(node_id, a, 6);
248			close(sd);
249			return 1;
250		}
251	}
252	close(sd);
253#endif
254	return 0;
255}
256
257/* Assume that the gettimeofday() has microsecond granularity */
258#define MAX_ADJUSTMENT 10
259
260static int get_clock(uint32_t *clock_high, uint32_t *clock_low,
261		     uint16_t *ret_clock_seq, int *num)
262{
263	THREAD_LOCAL int		adjustment = 0;
264	THREAD_LOCAL struct timeval	last = {0, 0};
265	THREAD_LOCAL int		state_fd = -2;
266	THREAD_LOCAL FILE		*state_f;
267	THREAD_LOCAL uint16_t		clock_seq;
268	struct timeval 			tv;
269	struct flock			fl;
270	unsigned long long		clock_reg;
271	mode_t				save_umask;
272
273	if (state_fd == -2) {
274		save_umask = umask(0);
275		state_fd = open("/var/lib/libuuid/clock.txt",
276				O_RDWR|O_CREAT, 0660);
277		(void) umask(save_umask);
278		state_f = fdopen(state_fd, "r+");
279		if (!state_f) {
280			close(state_fd);
281			state_fd = -1;
282		}
283	}
284	fl.l_type = F_WRLCK;
285	fl.l_whence = SEEK_SET;
286	fl.l_start = 0;
287	fl.l_len = 0;
288	fl.l_pid = 0;
289	if (state_fd >= 0) {
290		rewind(state_f);
291		while (fcntl(state_fd, F_SETLKW, &fl) < 0) {
292			if ((errno == EAGAIN) || (errno == EINTR))
293				continue;
294			fclose(state_f);
295			close(state_fd);
296			state_fd = -1;
297			break;
298		}
299	}
300	if (state_fd >= 0) {
301		unsigned int cl;
302		unsigned long tv1, tv2;
303		int a;
304
305		if (fscanf(state_f, "clock: %04x tv: %lu %lu adj: %d\n",
306			   &cl, &tv1, &tv2, &a) == 4) {
307			clock_seq = cl & 0x3FFF;
308			last.tv_sec = tv1;
309			last.tv_usec = tv2;
310			adjustment = a;
311		}
312	}
313
314	if ((last.tv_sec == 0) && (last.tv_usec == 0)) {
315		get_random_bytes(&clock_seq, sizeof(clock_seq));
316		clock_seq &= 0x3FFF;
317		last = tv;
318		last.tv_sec--;
319	}
320
321try_again:
322	gettimeofday(&tv, 0);
323	if ((tv.tv_sec < last.tv_sec) ||
324	    ((tv.tv_sec == last.tv_sec) &&
325	     (tv.tv_usec < last.tv_usec))) {
326		clock_seq = (clock_seq+1) & 0x3FFF;
327		adjustment = 0;
328		last = tv;
329	} else if ((tv.tv_sec == last.tv_sec) &&
330	    (tv.tv_usec == last.tv_usec)) {
331		if (adjustment >= MAX_ADJUSTMENT)
332			goto try_again;
333		adjustment++;
334	} else {
335		adjustment = 0;
336		last = tv;
337	}
338
339	clock_reg = tv.tv_usec*10 + adjustment;
340	clock_reg += ((unsigned long long) tv.tv_sec)*10000000;
341	clock_reg += (((unsigned long long) 0x01B21DD2) << 32) + 0x13814000;
342
343	if (num && (*num > 1)) {
344		adjustment += *num - 1;
345		last.tv_usec += adjustment / 10;
346		adjustment = adjustment % 10;
347		last.tv_sec += last.tv_usec / 1000000;
348		last.tv_usec = last.tv_usec % 1000000;
349	}
350
351	if (state_fd > 0) {
352		rewind(state_f);
353		ftruncate(state_fd, 0);
354		fprintf(state_f, "clock: %04x tv: %lu %lu adj: %d\n",
355			clock_seq, last.tv_sec, last.tv_usec, adjustment);
356		fflush(state_f);
357		rewind(state_f);
358		fl.l_type = F_UNLCK;
359		fcntl(state_fd, F_SETLK, &fl);
360	}
361
362	*clock_high = clock_reg >> 32;
363	*clock_low = clock_reg;
364	*ret_clock_seq = clock_seq;
365	return 0;
366}
367
368static ssize_t read_all(int fd, char *buf, size_t count)
369{
370	ssize_t ret;
371	ssize_t c = 0;
372
373	memset(buf, 0, count);
374	while (count > 0) {
375		ret = read(fd, buf, count);
376		if (ret < 0) {
377			if ((errno == EAGAIN) || (errno == EINTR))
378				continue;
379			return -1;
380		}
381		count -= ret;
382		buf += ret;
383		c += ret;
384	}
385	return c;
386}
387
388
389/*
390 * Try using the uuidd daemon to generate the UUID
391 *
392 * Returns 0 on success, non-zero on failure.
393 */
394static int get_uuid_via_daemon(int op, uuid_t out, int *num)
395{
396#ifdef USE_UUIDD
397	char op_buf[64];
398	int op_len;
399	int s;
400	ssize_t ret;
401	int32_t reply_len = 0, expected = 16;
402	struct sockaddr_un srv_addr;
403	pid_t pid;
404	static const char *uuidd_path = UUIDD_PATH;
405	static int access_ret = -2;
406	static int start_attempts = 0;
407
408	if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
409		return -1;
410
411	srv_addr.sun_family = AF_UNIX;
412	strcpy(srv_addr.sun_path, UUIDD_SOCKET_PATH);
413
414	if (connect(s, (const struct sockaddr *) &srv_addr,
415		    sizeof(struct sockaddr_un)) < 0) {
416		if (access_ret == -2)
417			access_ret = access(uuidd_path, X_OK);
418		if (access_ret == 0 && start_attempts++ < 5) {
419			if ((pid = fork()) == 0) {
420				execl(uuidd_path, "uuidd", "-qT", "300",
421				      (char *) NULL);
422				exit(1);
423			}
424			(void) waitpid(pid, 0, 0);
425			if (connect(s, (const struct sockaddr *) &srv_addr,
426				    sizeof(struct sockaddr_un)) < 0)
427				goto fail;
428		} else
429			goto fail;
430	}
431	op_buf[0] = op;
432	op_len = 1;
433	if (op == UUIDD_OP_BULK_TIME_UUID) {
434		memcpy(op_buf+1, num, sizeof(*num));
435		op_len += sizeof(*num);
436		expected += sizeof(*num);
437	}
438
439	ret = write(s, op_buf, op_len);
440	if (ret < 1)
441		goto fail;
442
443	ret = read_all(s, (char *) &reply_len, sizeof(reply_len));
444	if (ret < 0)
445		goto fail;
446
447	if (reply_len != expected)
448		goto fail;
449
450	ret = read_all(s, op_buf, reply_len);
451
452	if (op == UUIDD_OP_BULK_TIME_UUID)
453		memcpy(op_buf+16, num, sizeof(int));
454
455	memcpy(out, op_buf, 16);
456
457	close(s);
458	return ((ret == expected) ? 0 : -1);
459
460fail:
461	close(s);
462#endif
463	return -1;
464}
465
466void uuid__generate_time(uuid_t out, int *num)
467{
468	static unsigned char node_id[6];
469	static int has_init = 0;
470	struct uuid uu;
471	uint32_t	clock_mid;
472
473	if (!has_init) {
474		if (get_node_id(node_id) <= 0) {
475			get_random_bytes(node_id, 6);
476			/*
477			 * Set multicast bit, to prevent conflicts
478			 * with IEEE 802 addresses obtained from
479			 * network cards
480			 */
481			node_id[0] |= 0x01;
482		}
483		has_init = 1;
484	}
485	get_clock(&clock_mid, &uu.time_low, &uu.clock_seq, num);
486	uu.clock_seq |= 0x8000;
487	uu.time_mid = (uint16_t) clock_mid;
488	uu.time_hi_and_version = ((clock_mid >> 16) & 0x0FFF) | 0x1000;
489	memcpy(uu.node, node_id, 6);
490	uuid_pack(&uu, out);
491}
492
493void uuid_generate_time(uuid_t out)
494{
495#ifdef TLS
496	THREAD_LOCAL int		num = 0;
497	THREAD_LOCAL struct uuid	uu;
498	THREAD_LOCAL time_t		last_time = 0;
499	time_t				now;
500
501	if (num > 0) {
502		now = time(0);
503		if (now > last_time+1)
504			num = 0;
505	}
506	if (num <= 0) {
507		num = 1000;
508		if (get_uuid_via_daemon(UUIDD_OP_BULK_TIME_UUID,
509					out, &num) == 0) {
510			last_time = time(0);
511			uuid_unpack(out, &uu);
512			num--;
513			return;
514		}
515		num = 0;
516	}
517	if (num > 0) {
518		uu.time_low++;
519		if (uu.time_low == 0) {
520			uu.time_mid++;
521			if (uu.time_mid == 0)
522				uu.time_hi_and_version++;
523		}
524		num--;
525		uuid_pack(&uu, out);
526		return;
527	}
528#else
529	if (get_uuid_via_daemon(UUIDD_OP_TIME_UUID, out, 0) == 0)
530		return;
531#endif
532
533	uuid__generate_time(out, 0);
534}
535
536
537void uuid__generate_random(uuid_t out, int *num)
538{
539	uuid_t	buf;
540	struct uuid uu;
541	int i, n;
542
543	if (!num || !*num)
544		n = 1;
545	else
546		n = *num;
547
548	for (i = 0; i < n; i++) {
549		get_random_bytes(buf, sizeof(buf));
550		uuid_unpack(buf, &uu);
551
552		uu.clock_seq = (uu.clock_seq & 0x3FFF) | 0x8000;
553		uu.time_hi_and_version = (uu.time_hi_and_version & 0x0FFF)
554			| 0x4000;
555		uuid_pack(&uu, out);
556		out += sizeof(uuid_t);
557	}
558}
559
560void uuid_generate_random(uuid_t out)
561{
562	int	num = 1;
563	/* No real reason to use the daemon for random uuid's -- yet */
564
565	uuid__generate_random(out, &num);
566}
567
568
569/*
570 * This is the generic front-end to uuid_generate_random and
571 * uuid_generate_time.  It uses uuid_generate_random only if
572 * /dev/urandom is available, since otherwise we won't have
573 * high-quality randomness.
574 */
575void uuid_generate(uuid_t out)
576{
577	if (get_random_fd() >= 0)
578		uuid_generate_random(out);
579	else
580		uuid_generate_time(out);
581}
582