The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_uuid.c

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    1 /* $NetBSD: kern_uuid.c,v 1.1 2004/01/29 02:00:03 tsarna Exp $ */
    2 /* $FreeBSD: /repoman/r/ncvs/src/sys/kern/kern_uuid.c,v 1.7 2004/01/12 13:34:11 rse Exp $ */
    3 
    4 /*
    5  * Copyright (c) 2002 Marcel Moolenaar
    6  * All rights reserved.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  *
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   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  *
   18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   28  */
   29 
   30 #include <sys/cdefs.h>
   31 __KERNEL_RCSID(0, "$NetBSD: kern_uuid.c,v 1.1 2004/01/29 02:00:03 tsarna Exp $");
   32 
   33 #include <sys/param.h>
   34 #include <sys/endian.h>
   35 #include <sys/kernel.h>
   36 #include <sys/lock.h>
   37 #include <sys/socket.h>
   38 #include <sys/systm.h>
   39 #include <sys/uuid.h>
   40 
   41 /* NetBSD */
   42 #include <sys/proc.h>
   43 #include <sys/sa.h>
   44 #include <sys/mount.h>
   45 #include <sys/syscallargs.h>
   46 #include <sys/uio.h>
   47 
   48 #include <net/if.h>
   49 #include <net/if_dl.h>
   50 #include <net/if_types.h>
   51 
   52 
   53 int sys_uuidgen(struct lwp *, void *, register_t *);
   54 
   55 /*
   56  * See also:
   57  *      http://www.opengroup.org/dce/info/draft-leach-uuids-guids-01.txt
   58  *      http://www.opengroup.org/onlinepubs/009629399/apdxa.htm
   59  *
   60  * Note that the generator state is itself an UUID, but the time and clock
   61  * sequence fields are written in the native byte order.
   62  */
   63 
   64 /* XXX Do we have a similar ASSERT()? */
   65 #define CTASSERT(x)
   66 
   67 CTASSERT(sizeof(struct uuid) == 16);
   68 
   69 /* We use an alternative, more convenient representation in the generator. */
   70 struct uuid_private {
   71         union {
   72                 uint64_t        ll;             /* internal. */
   73                 struct {
   74                         uint32_t        low;
   75                         uint16_t        mid;
   76                         uint16_t        hi;
   77                 } x;
   78         } time;
   79         uint16_t        seq;                    /* Big-endian. */
   80         uint16_t        node[UUID_NODE_LEN>>1];
   81 };
   82 
   83 CTASSERT(sizeof(struct uuid_private) == 16);
   84 
   85 static struct uuid_private uuid_last;
   86 
   87 /* "UUID generator mutex lock" */
   88 static struct simplelock uuid_mutex = SIMPLELOCK_INITIALIZER;
   89 
   90 /*
   91  * Return the first MAC address we encounter or, if none was found,
   92  * construct a sufficiently random multicast address. We don't try
   93  * to return the same MAC address as previously returned. We always
   94  * generate a new multicast address if no MAC address exists in the
   95  * system.
   96  * It would be nice to know if 'ifnet' or any of its sub-structures
   97  * has been changed in any way. If not, we could simply skip the
   98  * scan and safely return the MAC address we returned before.
   99  */
  100 static void
  101 uuid_node(uint16_t *node)
  102 {
  103         struct ifnet *ifp;
  104         struct ifaddr *ifa;
  105         struct sockaddr_dl *sdl;
  106         int i, s;
  107 
  108         s = splnet();
  109         TAILQ_FOREACH(ifp, &ifnet, if_list) {
  110                 /* Walk the address list */
  111                 TAILQ_FOREACH(ifa, &ifp->if_addrlist, ifa_list) {
  112                         sdl = (struct sockaddr_dl*)ifa->ifa_addr;
  113                         if (sdl != NULL && sdl->sdl_family == AF_LINK &&
  114                             sdl->sdl_type == IFT_ETHER) {
  115                                 /* Got a MAC address. */
  116                                 memcpy(node, LLADDR(sdl), UUID_NODE_LEN);
  117                                 splx(s);
  118                                 return;
  119                         }
  120                 }
  121         }
  122         splx(s);
  123 
  124         for (i = 0; i < (UUID_NODE_LEN>>1); i++)
  125                 node[i] = (uint16_t)arc4random();
  126         *((uint8_t*)node) |= 0x01;
  127 }
  128 
  129 /*
  130  * Get the current time as a 60 bit count of 100-nanosecond intervals
  131  * since 00:00:00.00, October 15,1582. We apply a magic offset to convert
  132  * the Unix time since 00:00:00.00, January 1, 1970 to the date of the
  133  * Gregorian reform to the Christian calendar.
  134  */
  135 /*
  136  * At present, NetBSD has no timespec source, only timeval sources.  So,
  137  * we use timeval.
  138  */
  139 static uint64_t
  140 uuid_time(void)
  141 {
  142         struct timeval tv;
  143         uint64_t time = 0x01B21DD213814000LL;
  144 
  145         microtime(&tv);
  146         time += (uint64_t)tv.tv_sec * 10000000LL;
  147         time += (uint64_t)(10 * tv.tv_usec);
  148         return (time & ((1LL << 60) - 1LL));
  149 }
  150 
  151 int
  152 sys_uuidgen(struct lwp *l, void *v, register_t *retval)
  153 {
  154         struct sys_uuidgen_args *uap = v;
  155         struct uuid_private uuid;
  156         uint64_t time;
  157         int error;
  158 
  159         /*
  160          * Limit the number of UUIDs that can be created at the same time
  161          * to some arbitrary number. This isn't really necessary, but I
  162          * like to have some sort of upper-bound that's less than 2G :-)
  163          * XXX needs to be tunable.
  164          */
  165         if (SCARG(uap,count) < 1 || SCARG(uap,count) > 2048)
  166                 return (EINVAL);
  167 
  168         /* XXX: pre-validate accessibility to the whole of the UUID store? */
  169 
  170         simple_lock(&uuid_mutex);
  171 
  172         uuid_node(uuid.node);
  173         time = uuid_time();
  174 
  175         if (uuid_last.time.ll == 0LL || uuid_last.node[0] != uuid.node[0] ||
  176             uuid_last.node[1] != uuid.node[1] ||
  177             uuid_last.node[2] != uuid.node[2])
  178                 uuid.seq = (uint16_t)arc4random() & 0x3fff;
  179         else if (uuid_last.time.ll >= time)
  180                 uuid.seq = (uuid_last.seq + 1) & 0x3fff;
  181         else
  182                 uuid.seq = uuid_last.seq;
  183 
  184         uuid_last = uuid;
  185         uuid_last.time.ll = (time + SCARG(uap,count) - 1) & ((1LL << 60) - 1LL);
  186 
  187         simple_unlock(&uuid_mutex);
  188 
  189         /* Set sequence and variant and deal with byte order. */
  190         uuid.seq = htobe16(uuid.seq | 0x8000);
  191 
  192         /* XXX: this should copyout larger chunks at a time. */
  193         do {
  194                 /* Set time and version (=1) and deal with byte order. */
  195                 uuid.time.x.low = (uint32_t)time;
  196                 uuid.time.x.mid = (uint16_t)(time >> 32);
  197                 uuid.time.x.hi = ((uint16_t)(time >> 48) & 0xfff) | (1 << 12);
  198                 error = copyout(&uuid, SCARG(uap,store), sizeof(uuid));
  199                 SCARG(uap,store)++;
  200                 SCARG(uap,count)--;
  201                 time++;
  202         } while (SCARG(uap,count) > 0 && !error);
  203 
  204         return (error);
  205 }
  206 
  207 #ifdef notyet
  208 int
  209 snprintf_uuid(char *buf, size_t sz, struct uuid *uuid)
  210 {
  211         struct uuid_private *id;
  212         int cnt;
  213 
  214         id = (struct uuid_private *)uuid;
  215         cnt = snprintf(buf, sz, "%08x-%04x-%04x-%04x-%04x%04x%04x",
  216             id->time.x.low, id->time.x.mid, id->time.x.hi, be16toh(id->seq),
  217             be16toh(id->node[0]), be16toh(id->node[1]), be16toh(id->node[2]));
  218         return (cnt);
  219 }
  220 
  221 int
  222 printf_uuid(struct uuid *uuid)
  223 {
  224         char buf[38];
  225 
  226         snprintf_uuid(buf, sizeof(buf), uuid);
  227         printf("%s", buf);
  228         return 0;
  229 }
  230 
  231 /*
  232  * Encode/Decode UUID into byte-stream.
  233  *   http://www.opengroup.org/dce/info/draft-leach-uuids-guids-01.txt
  234  *
  235  * 0                   1                   2                   3
  236  *   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  237  *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  238  *  |                          time_low                             |
  239  *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  240  *  |       time_mid                |         time_hi_and_version   |
  241  *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  242  *  |clk_seq_hi_res |  clk_seq_low  |         node (0-1)            |
  243  *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  244  *  |                         node (2-5)                            |
  245  *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  246  */
  247 
  248 void
  249 le_uuid_enc(void *buf, struct uuid const *uuid)
  250 {
  251         u_char *p;
  252         int i;
  253 
  254         p = buf;
  255         le32enc(p, uuid->time_low);
  256         le16enc(p + 4, uuid->time_mid);
  257         le16enc(p + 6, uuid->time_hi_and_version);
  258         p[8] = uuid->clock_seq_hi_and_reserved;
  259         p[9] = uuid->clock_seq_low;
  260         for (i = 0; i < _UUID_NODE_LEN; i++)
  261                 p[10 + i] = uuid->node[i];
  262 }
  263 
  264 void
  265 le_uuid_dec(void const *buf, struct uuid *uuid)
  266 {
  267         u_char const *p;
  268         int i;
  269 
  270         p = buf;
  271         uuid->time_low = le32dec(p);
  272         uuid->time_mid = le16dec(p + 4);
  273         uuid->time_hi_and_version = le16dec(p + 6);
  274         uuid->clock_seq_hi_and_reserved = p[8];
  275         uuid->clock_seq_low = p[9];
  276         for (i = 0; i < _UUID_NODE_LEN; i++)
  277                 uuid->node[i] = p[10 + i];
  278 }
  279 void
  280 be_uuid_enc(void *buf, struct uuid const *uuid)
  281 {
  282         u_char *p;
  283         int i;
  284 
  285         p = buf;
  286         be32enc(p, uuid->time_low);
  287         be16enc(p + 4, uuid->time_mid);
  288         be16enc(p + 6, uuid->time_hi_and_version);
  289         p[8] = uuid->clock_seq_hi_and_reserved;
  290         p[9] = uuid->clock_seq_low;
  291         for (i = 0; i < _UUID_NODE_LEN; i++)
  292                 p[10 + i] = uuid->node[i];
  293 }
  294 
  295 void
  296 be_uuid_dec(void const *buf, struct uuid *uuid)
  297 {
  298         u_char const *p;
  299         int i;
  300 
  301         p = buf;
  302         uuid->time_low = be32dec(p);
  303         uuid->time_mid = le16dec(p + 4);
  304         uuid->time_hi_and_version = be16dec(p + 6);
  305         uuid->clock_seq_hi_and_reserved = p[8];
  306         uuid->clock_seq_low = p[9];
  307         for (i = 0; i < _UUID_NODE_LEN; i++)
  308                 uuid->node[i] = p[10 + i];
  309 }
  310 #endif

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