kern_uuid.c revision 102263 
1/*
2 * Copyright (c) 2002 Marcel Moolenaar
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 *
26 * $FreeBSD: head/sys/kern/kern_uuid.c 102263 2002-08-22 12:47:22Z bde $
27 */
28
29#include <sys/param.h>
30#include <sys/endian.h>
31#include <sys/kernel.h>
32#include <sys/lock.h>
33#include <sys/mutex.h>
34#include <sys/sbuf.h>
35#include <sys/socket.h>
36#include <sys/sysproto.h>
37#include <sys/systm.h>
38#include <sys/uuid.h>
39
40#include <net/if.h>
41#include <net/if_dl.h>
42#include <net/if_types.h>
43
44/*
45 * See also:
46 *	http://www.opengroup.org/dce/info/draft-leach-uuids-guids-01.txt
47 *	http://www.opengroup.org/onlinepubs/009629399/apdxa.htm
48 *
49 * Note that the generator state is itself an UUID, but the time and clock
50 * sequence fields are written in the native byte order.
51 */
52
53CTASSERT(sizeof(struct uuid) == 16);
54
55/* We use an alternative, more convenient representation in the generator. */
56struct uuid_private {
57	union {
58		uint64_t	ll;		/* internal. */
59		struct {
60			uint32_t	low;
61			uint16_t	mid;
62			uint16_t	hi;
63		} x;
64	} time;
65	uint16_t	seq;			/* Big-endian. */
66	uint16_t	node[UUID_NODE_LEN>>1];
67};
68
69CTASSERT(sizeof(struct uuid_private) == 16);
70
71static struct uuid_private uuid_last;
72
73static struct mtx uuid_mutex;
74MTX_SYSINIT(uuid_lock, &uuid_mutex, "UUID generator mutex lock", MTX_DEF);
75
76/*
77 * Return the first MAC address we encounter or, if none was found,
78 * construct a sufficiently random multicast address. We don't try
79 * to return the same MAC address as previously returned. We always
80 * generate a new multicast address if no MAC address exists in the
81 * system.
82 * It would be nice to know if 'ifnet' or any of its sub-structures
83 * has been changed in any way. If not, we could simply skip the
84 * scan and safely return the MAC address we returned before.
85 */
86static void
87uuid_node(uint16_t *node)
88{
89	struct ifnet *ifp;
90	struct ifaddr *ifa;
91	struct sockaddr_dl *sdl;
92	int i;
93
94	/* XXX: lock ifnet. */
95	TAILQ_FOREACH(ifp, &ifnet, if_link) {
96		/* Walk the address list */
97		TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
98			sdl = (struct sockaddr_dl*)ifa->ifa_addr;
99			if (sdl != NULL && sdl->sdl_family == AF_LINK &&
100			    sdl->sdl_type == IFT_ETHER) {
101				/* Got a MAC address. */
102				bcopy(LLADDR(sdl), node, UUID_NODE_LEN);
103				/* XXX: unlock ifnet. */
104				return;
105			}
106		}
107	}
108	/* XXX: unlock ifnet. */
109
110	for (i = 0; i < (UUID_NODE_LEN>>1); i++)
111		node[i] = (uint16_t)arc4random();
112	*((uint8_t*)node) |= 0x80;
113}
114
115/*
116 * Get the current time as a 60 bit count of 100-nanosecond intervals
117 * since 00:00:00.00, October 15,1582. We apply a magic offset to convert
118 * the Unix time since 00:00:00.00, Januari 1, 1970 to the date of the
119 * Gregorian reform to the Christian calendar.
120 */
121static uint64_t
122uuid_time(void)
123{
124	struct bintime bt;
125	uint64_t time = 0x01B21DD213814000LL;
126
127	bintime(&bt);
128	time += (uint64_t)bt.sec * 10000000LL;
129	time += (10000000LL * (uint32_t)(bt.frac >> 32)) >> 32;
130	return (time & ((1LL << 60) - 1LL));
131}
132
133#ifndef _SYS_SYSPROTO_H_
134struct uuidgen_args {
135	struct uuid *store;
136	int	count;
137};
138#endif
139
140int
141uuidgen(struct thread *td, struct uuidgen_args *uap)
142{
143	struct uuid_private uuid;
144	uint64_t time;
145	int error;
146
147	/*
148	 * Limit the number of UUIDs that can be created at the same time
149	 * to some arbitrary number. This isn't really necessary, but I
150	 * like to have some sort of upper-bound that's less than 2G :-)
151	 * XXX needs to be tunable.
152	 */
153	if (uap->count < 1 || uap->count > 2048)
154		return (EINVAL);
155
156	/* XXX: pre-validate accessibility to the whole of the UUID store? */
157
158	mtx_lock(&uuid_mutex);
159
160	uuid_node(uuid.node);
161	time = uuid_time();
162
163	if (uuid_last.time.ll == 0LL || uuid_last.node[0] != uuid.node[0] ||
164	    uuid_last.node[1] != uuid.node[1] ||
165	    uuid_last.node[2] != uuid.node[2])
166		uuid.seq = (uint16_t)arc4random() & 0x3fff;
167	else if (uuid_last.time.ll >= time)
168		uuid.seq = (uuid_last.seq + 1) & 0x3fff;
169	else
170		uuid.seq = uuid_last.seq;
171
172	uuid_last = uuid;
173	uuid_last.time.ll = (time + uap->count - 1) & ((1LL << 60) - 1LL);
174
175	mtx_unlock(&uuid_mutex);
176
177	/* Set sequence and variant and deal with byte order. */
178	uuid.seq = htobe16(uuid.seq | 0x8000);
179
180	/* XXX: this should copyout larger chunks at a time. */
181	do {
182		/* Set time and version (=1) and deal with byte order. */
183		uuid.time.x.low = (uint32_t)time;
184		uuid.time.x.mid = (uint16_t)(time >> 32);
185		uuid.time.x.hi = ((uint16_t)(time >> 48) & 0xfff) | (1 << 12);
186		error = copyout(&uuid, uap->store, sizeof(uuid));
187		uap->store++;
188		uap->count--;
189		time++;
190	} while (uap->count > 0 && !error);
191
192	return (error);
193}
194
195int
196snprintf_uuid(char *buf, size_t sz, struct uuid *uuid)
197{
198	struct uuid_private *id;
199	int cnt;
200
201	id = (struct uuid_private *)uuid;
202	cnt = snprintf(buf, sz, "%08x-%04x-%04x-%04x-%04x%04x%04x",
203	    id->time.x.low, id->time.x.mid, id->time.x.hi, be16toh(id->seq),
204	    be16toh(id->node[0]), be16toh(id->node[1]), be16toh(id->node[2]));
205	return (cnt);
206}
207
208int
209printf_uuid(struct uuid *uuid)
210{
211	char buf[38];
212
213	snprintf_uuid(buf, sizeof(buf), uuid);
214	return (printf("%s", buf));
215}
216
217int
218sbuf_printf_uuid(struct sbuf *sb, struct uuid *uuid)
219{
220	char buf[38];
221
222	snprintf_uuid(buf, sizeof(buf), uuid);
223	return (sbuf_printf(sb, "%s", buf));
224}
225