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 * This file may be redistributed under the terms of the GNU
8 * Library General Public License.
9 * %End-Header%
10 */
11
12/*
13 * Force inclusion of SVID stuff since we need it if we're compiling in
14 * gcc-wall wall mode
15 */
16#define _SVID_SOURCE
17
18#ifdef HAVE_UNISTD_H
19#include <unistd.h>
20#endif
21#ifdef HAVE_STDLIB_H
22#include <stdlib.h>
23#endif
24#include <string.h>
25#include <fcntl.h>
26#include <errno.h>
27#include <sys/types.h>
28#include <sys/time.h>
29#include <sys/stat.h>
30#include <sys/file.h>
31#ifdef HAVE_SYS_IOCTL_H
32#include <sys/ioctl.h>
33#endif
34#ifdef HAVE_SYS_SOCKET_H
35#include <sys/socket.h>
36#endif
37#ifdef HAVE_SYS_SOCKIO_H
38#include <sys/sockio.h>
39#endif
40#ifdef HAVE_NET_IF_H
41#include <net/if.h>
42#endif
43#ifdef HAVE_NETINET_IN_H
44#include <netinet/in.h>
45#endif
46
47#include "uuidP.h"
48//#include "uuid.h"
49#ifdef HAVE_SRANDOM
50#define srand(x) 	srandom(x)
51#define rand() 		random()
52#endif
53
54static int get_random_fd(void)
55{
56	struct timeval	tv;
57	static int	fd = -2;
58	int		i;
59
60	if (fd == -2) {
61		gettimeofday(&tv, 0);
62		fd = open("/dev/urandom", O_RDONLY);
63		if (fd == -1)
64			fd = open("/dev/random", O_RDONLY | O_NONBLOCK);
65		srand((getpid() << 16) ^ getuid() ^ tv.tv_sec ^ tv.tv_usec);
66	}
67	/* Crank the random number generator a few times */
68	gettimeofday(&tv, 0);
69	for (i = (tv.tv_sec ^ tv.tv_usec) & 0x1F; i > 0; i--)
70		rand();
71	return fd;
72}
73
74
75/*
76 * Generate a series of random bytes.  Use /dev/urandom if possible,
77 * and if not, use srandom/random.
78 */
79static void get_random_bytes(void *buf, int nbytes)
80{
81	int i, n = nbytes, fd = get_random_fd();
82	int lose_counter = 0;
83	unsigned char *cp = (unsigned char *) buf;
84
85	if (fd >= 0) {
86		while (n > 0) {
87			i = read(fd, cp, n);
88			if (i <= 0) {
89				if (lose_counter++ > 16)
90					break;
91				continue;
92			}
93			n -= i;
94			cp += i;
95			lose_counter = 0;
96		}
97	}
98
99	/*
100	 * We do this all the time, but this is the only source of
101	 * randomness if /dev/random/urandom is out to lunch.
102	 */
103	for (cp = buf, i = 0; i < nbytes; i++)
104		*cp++ ^= (rand() >> 7) & 0xFF;
105	return;
106}
107
108/*
109 * Get the ethernet hardware address, if we can find it...
110 */
111static int get_node_id(unsigned char *node_id)
112{
113#ifdef HAVE_NET_IF_H
114	int 		sd;
115	struct ifreq 	ifr, *ifrp;
116	struct ifconf 	ifc;
117	char buf[1024];
118	int		n, i;
119	unsigned char 	*a;
120
121/*
122 * BSD 4.4 defines the size of an ifreq to be
123 * max(sizeof(ifreq), sizeof(ifreq.ifr_name)+ifreq.ifr_addr.sa_len
124 * However, under earlier systems, sa_len isn't present, so the size is
125 * just sizeof(struct ifreq)
126 */
127#ifdef HAVE_SA_LEN
128#ifndef max
129#define max(a,b) ((a) > (b) ? (a) : (b))
130#endif
131#define ifreq_size(i) max(sizeof(struct ifreq),\
132     sizeof((i).ifr_name)+(i).ifr_addr.sa_len)
133#else
134#define ifreq_size(i) sizeof(struct ifreq)
135#endif /* HAVE_SA_LEN*/
136
137	sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
138	if (sd < 0) {
139		return -1;
140	}
141	memset(buf, 0, sizeof(buf));
142	ifc.ifc_len = sizeof(buf);
143	ifc.ifc_buf = buf;
144	if (ioctl (sd, SIOCGIFCONF, (char *)&ifc) < 0) {
145		close(sd);
146		return -1;
147	}
148	n = ifc.ifc_len;
149	for (i = 0; i < n; i+= ifreq_size(*ifr) ) {
150		ifrp = (struct ifreq *)((char *) ifc.ifc_buf+i);
151		strncpy(ifr.ifr_name, ifrp->ifr_name, IFNAMSIZ);
152#ifdef SIOCGIFHWADDR
153		if (ioctl(sd, SIOCGIFHWADDR, &ifr) < 0)
154			continue;
155		a = (unsigned char *) &ifr.ifr_hwaddr.sa_data;
156#else
157#ifdef SIOCGENADDR
158		if (ioctl(sd, SIOCGENADDR, &ifr) < 0)
159			continue;
160		a = (unsigned char *) ifr.ifr_enaddr;
161#else
162		/*
163		 * XXX we don't have a way of getting the hardware
164		 * address
165		 */
166		close(sd);
167		return 0;
168#endif /* SIOCGENADDR */
169#endif /* SIOCGIFHWADDR */
170		if (!a[0] && !a[1] && !a[2] && !a[3] && !a[4] && !a[5])
171			continue;
172		if (node_id) {
173			memcpy(node_id, a, 6);
174			close(sd);
175			return 1;
176		}
177	}
178	close(sd);
179#endif
180	return 0;
181}
182
183/* Assume that the gettimeofday() has microsecond granularity */
184#define MAX_ADJUSTMENT 10
185
186static int get_clock(__u32 *clock_high, __u32 *clock_low, __u16 *ret_clock_seq)
187{
188	static int			adjustment = 0;
189	static struct timeval		last = {0, 0};
190	static __u16			clock_seq;
191	struct timeval 			tv;
192	unsigned long long		clock_reg;
193
194try_again:
195	gettimeofday(&tv, 0);
196	if ((last.tv_sec == 0) && (last.tv_usec == 0)) {
197		get_random_bytes(&clock_seq, sizeof(clock_seq));
198		clock_seq &= 0x1FFF;
199		last = tv;
200		last.tv_sec--;
201	}
202	if ((tv.tv_sec < last.tv_sec) ||
203	    ((tv.tv_sec == last.tv_sec) &&
204	     (tv.tv_usec < last.tv_usec))) {
205		clock_seq = (clock_seq+1) & 0x1FFF;
206		adjustment = 0;
207		last = tv;
208	} else if ((tv.tv_sec == last.tv_sec) &&
209	    (tv.tv_usec == last.tv_usec)) {
210		if (adjustment >= MAX_ADJUSTMENT)
211			goto try_again;
212		adjustment++;
213	} else {
214		adjustment = 0;
215		last = tv;
216	}
217
218	clock_reg = tv.tv_usec*10 + adjustment;
219	clock_reg += ((unsigned long long) tv.tv_sec)*10000000;
220	clock_reg += (((unsigned long long) 0x01B21DD2) << 32) + 0x13814000;
221
222	*clock_high = clock_reg >> 32;
223	*clock_low = clock_reg;
224	*ret_clock_seq = clock_seq;
225	return 0;
226}
227
228void uuid_generate_time(uuid_t out)
229{
230	static unsigned char node_id[6];
231	static int has_init = 0;
232	struct uuid uu;
233	__u32	clock_mid;
234
235	if (!has_init) {
236		if (get_node_id(node_id) <= 0) {
237			get_random_bytes(node_id, 6);
238			/*
239			 * Set multicast bit, to prevent conflicts
240			 * with IEEE 802 addresses obtained from
241			 * network cards
242			 */
243			node_id[0] |= 0x80;
244		}
245		has_init = 1;
246	}
247	get_clock(&clock_mid, &uu.time_low, &uu.clock_seq);
248	uu.clock_seq |= 0x8000;
249	uu.time_mid = (__u16) clock_mid;
250	uu.time_hi_and_version = (clock_mid >> 16) | 0x1000;
251	memcpy(uu.node, node_id, 6);
252	uuid_pack(&uu, out);
253}
254
255void uuid_generate_random(uuid_t out)
256{
257	uuid_t	buf;
258	struct uuid uu;
259
260	get_random_bytes(buf, sizeof(buf));
261	uuid_unpack(buf, &uu);
262
263	uu.clock_seq = (uu.clock_seq & 0x3FFF) | 0x8000;
264	uu.time_hi_and_version = (uu.time_hi_and_version & 0x0FFF) | 0x4000;
265	uuid_pack(&uu, out);
266}
267
268/*
269 * This is the generic front-end to uuid_generate_random and
270 * uuid_generate_time.  It uses uuid_generate_random only if
271 * /dev/urandom is available, since otherwise we won't have
272 * high-quality randomness.
273 */
274void uuid_generate(uuid_t out)
275{
276	if (get_random_fd() >= 0)
277		uuid_generate_random(out);
278	else
279		uuid_generate_time(out);
280}
281