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 1.4 2005/01/24 21:25:09 matt Exp $       */
    2 
    3 /*
    4  * Copyright (c) 2002 Marcel Moolenaar
    5  * All rights reserved.
    6  *
    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  *
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   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  *
   17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   27  *
   28  * $FreeBSD: /repoman/r/ncvs/src/sys/kern/kern_uuid.c,v 1.7 2004/01/12 13:34:11 rse Exp $
   29  */
   30 
   31 #include <sys/cdefs.h>
   32 __KERNEL_RCSID(0, "$NetBSD: kern_uuid.c,v 1.4 2005/01/24 21:25:09 matt Exp $");
   33 
   34 #include <sys/param.h>
   35 #include <sys/endian.h>
   36 #include <sys/kernel.h>
   37 #include <sys/lock.h>
   38 #include <sys/socket.h>
   39 #include <sys/systm.h>
   40 #include <sys/uuid.h>
   41 
   42 /* NetBSD */
   43 #include <sys/proc.h>
   44 #include <sys/sa.h>
   45 #include <sys/mount.h>
   46 #include <sys/syscallargs.h>
   47 #include <sys/uio.h>
   48 
   49 #include <net/if.h>
   50 #include <net/if_dl.h>
   51 #include <net/if_types.h>
   52 
   53 /*
   54  * See also:
   55  *      http://www.opengroup.org/dce/info/draft-leach-uuids-guids-01.txt
   56  *      http://www.opengroup.org/onlinepubs/009629399/apdxa.htm
   57  *
   58  * Note that the generator state is itself an UUID, but the time and clock
   59  * sequence fields are written in the native byte order.
   60  */
   61 
   62 /* XXX Do we have a similar ASSERT()? */
   63 #define CTASSERT(x)
   64 
   65 CTASSERT(sizeof(struct uuid) == 16);
   66 
   67 /* We use an alternative, more convenient representation in the generator. */
   68 struct uuid_private {
   69         union {
   70                 uint64_t        ll;             /* internal. */
   71                 struct {
   72                         uint32_t        low;
   73                         uint16_t        mid;
   74                         uint16_t        hi;
   75                 } x;
   76         } time;
   77         uint16_t        seq;                    /* Big-endian. */
   78         uint16_t        node[UUID_NODE_LEN>>1];
   79 };
   80 
   81 CTASSERT(sizeof(struct uuid_private) == 16);
   82 
   83 static struct uuid_private uuid_last;
   84 
   85 /* "UUID generator mutex lock" */
   86 static struct simplelock uuid_mutex = SIMPLELOCK_INITIALIZER;
   87 
   88 /*
   89  * Return the first MAC address we encounter or, if none was found,
   90  * construct a sufficiently random multicast address. We don't try
   91  * to return the same MAC address as previously returned. We always
   92  * generate a new multicast address if no MAC address exists in the
   93  * system.
   94  * It would be nice to know if 'ifnet' or any of its sub-structures
   95  * has been changed in any way. If not, we could simply skip the
   96  * scan and safely return the MAC address we returned before.
   97  */
   98 static void
   99 uuid_node(uint16_t *node)
  100 {
  101         struct ifnet *ifp;
  102         struct ifaddr *ifa;
  103         struct sockaddr_dl *sdl;
  104         int i, s;
  105 
  106         s = splnet();
  107         IFNET_FOREACH(ifp) {
  108                 /* Walk the address list */
  109                 IFADDR_FOREACH(ifa, ifp) {
  110                         sdl = (struct sockaddr_dl*)ifa->ifa_addr;
  111                         if (sdl != NULL && sdl->sdl_family == AF_LINK &&
  112                             sdl->sdl_type == IFT_ETHER) {
  113                                 /* Got a MAC address. */
  114                                 memcpy(node, LLADDR(sdl), UUID_NODE_LEN);
  115                                 splx(s);
  116                                 return;
  117                         }
  118                 }
  119         }
  120         splx(s);
  121 
  122         for (i = 0; i < (UUID_NODE_LEN>>1); i++)
  123                 node[i] = (uint16_t)arc4random();
  124         *((uint8_t*)node) |= 0x01;
  125 }
  126 
  127 /*
  128  * Get the current time as a 60 bit count of 100-nanosecond intervals
  129  * since 00:00:00.00, October 15,1582. We apply a magic offset to convert
  130  * the Unix time since 00:00:00.00, January 1, 1970 to the date of the
  131  * Gregorian reform to the Christian calendar.
  132  */
  133 /*
  134  * At present, NetBSD has no timespec source, only timeval sources.  So,
  135  * we use timeval.
  136  */
  137 static uint64_t
  138 uuid_time(void)
  139 {
  140         struct timeval tv;
  141         uint64_t time = 0x01B21DD213814000LL;
  142 
  143         microtime(&tv);
  144         time += (uint64_t)tv.tv_sec * 10000000LL;
  145         time += (uint64_t)(10 * tv.tv_usec);
  146         return (time & ((1LL << 60) - 1LL));
  147 }
  148 
  149 /*
  150  * Internal routine to actually generate the UUID.
  151  */
  152 static void
  153 uuid_generate(struct uuid_private *uuid, uint64_t *timep, int count)
  154 {
  155         uint64_t time;
  156 
  157         simple_lock(&uuid_mutex);
  158 
  159         uuid_node(uuid->node);
  160         time = uuid_time();
  161         *timep = 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 + count - 1) & ((1LL << 60) - 1LL);
  174 
  175         simple_unlock(&uuid_mutex);
  176 }
  177 
  178 int
  179 sys_uuidgen(struct lwp *l, void *v, register_t *retval)
  180 {
  181         struct sys_uuidgen_args *uap = v;
  182         struct uuid_private uuid;
  183         uint64_t time;
  184         int error;
  185 
  186         /*
  187          * Limit the number of UUIDs that can be created at the same time
  188          * to some arbitrary number. This isn't really necessary, but I
  189          * like to have some sort of upper-bound that's less than 2G :-)
  190          * XXX needs to be tunable.
  191          */
  192         if (SCARG(uap,count) < 1 || SCARG(uap,count) > 2048)
  193                 return (EINVAL);
  194 
  195         /* XXX: pre-validate accessibility to the whole of the UUID store? */
  196 
  197         /* Generate the base UUID. */
  198         uuid_generate(&uuid, &time, SCARG(uap, count));
  199 
  200         /* Set sequence and variant and deal with byte order. */
  201         uuid.seq = htobe16(uuid.seq | 0x8000);
  202 
  203         /* XXX: this should copyout larger chunks at a time. */
  204         do {
  205                 /* Set time and version (=1) and deal with byte order. */
  206                 uuid.time.x.low = (uint32_t)time;
  207                 uuid.time.x.mid = (uint16_t)(time >> 32);
  208                 uuid.time.x.hi = ((uint16_t)(time >> 48) & 0xfff) | (1 << 12);
  209                 error = copyout(&uuid, SCARG(uap,store), sizeof(uuid));
  210                 SCARG(uap, store)++;
  211                 SCARG(uap, count)--;
  212                 time++;
  213         } while (SCARG(uap, count) > 0 && error == 0);
  214 
  215         return (error);
  216 }
  217 
  218 int
  219 uuid_snprintf(char *buf, size_t sz, const struct uuid *uuid)
  220 {
  221         const struct uuid_private *id;
  222         int cnt;
  223 
  224         id = (const struct uuid_private *)uuid;
  225         cnt = snprintf(buf, sz, "%08x-%04x-%04x-%04x-%04x%04x%04x",
  226             id->time.x.low, id->time.x.mid, id->time.x.hi, be16toh(id->seq),
  227             be16toh(id->node[0]), be16toh(id->node[1]), be16toh(id->node[2]));
  228         return (cnt);
  229 }
  230 
  231 int
  232 uuid_printf(const struct uuid *uuid)
  233 {
  234         char buf[UUID_STR_LEN];
  235 
  236         (void) uuid_snprintf(buf, sizeof(buf), uuid);
  237         printf("%s", buf);
  238         return (0);
  239 }
  240 
  241 /*
  242  * Encode/Decode UUID into octet-stream.
  243  *   http://www.opengroup.org/dce/info/draft-leach-uuids-guids-01.txt
  244  *
  245  * 0                   1                   2                   3
  246  *   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
  247  *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  248  *  |                          time_low                             |
  249  *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  250  *  |       time_mid                |         time_hi_and_version   |
  251  *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  252  *  |clk_seq_hi_res |  clk_seq_low  |         node (0-1)            |
  253  *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  254  *  |                         node (2-5)                            |
  255  *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  256  */
  257 
  258 void
  259 uuid_enc_le(void *buf, const struct uuid *uuid)
  260 {
  261         uint8_t *p = buf;
  262         int i;
  263 
  264         le32enc(p, uuid->time_low);
  265         le16enc(p + 4, uuid->time_mid);
  266         le16enc(p + 6, uuid->time_hi_and_version);
  267         p[8] = uuid->clock_seq_hi_and_reserved;
  268         p[9] = uuid->clock_seq_low;
  269         for (i = 0; i < _UUID_NODE_LEN; i++)
  270                 p[10 + i] = uuid->node[i];
  271 }
  272 
  273 void
  274 uuid_dec_le(void const *buf, struct uuid *uuid)
  275 {
  276         const uint8_t *p = buf;
  277         int i;
  278 
  279         uuid->time_low = le32dec(p);
  280         uuid->time_mid = le16dec(p + 4);
  281         uuid->time_hi_and_version = le16dec(p + 6);
  282         uuid->clock_seq_hi_and_reserved = p[8];
  283         uuid->clock_seq_low = p[9];
  284         for (i = 0; i < _UUID_NODE_LEN; i++)
  285                 uuid->node[i] = p[10 + i];
  286 }
  287 
  288 void
  289 uuid_enc_be(void *buf, const struct uuid *uuid)
  290 {
  291         uint8_t *p = buf;
  292         int i;
  293 
  294         be32enc(p, uuid->time_low);
  295         be16enc(p + 4, uuid->time_mid);
  296         be16enc(p + 6, uuid->time_hi_and_version);
  297         p[8] = uuid->clock_seq_hi_and_reserved;
  298         p[9] = uuid->clock_seq_low;
  299         for (i = 0; i < _UUID_NODE_LEN; i++)
  300                 p[10 + i] = uuid->node[i];
  301 }
  302 
  303 void
  304 uuid_dec_be(void const *buf, struct uuid *uuid)
  305 {
  306         const uint8_t *p = buf;
  307         int i;
  308 
  309         uuid->time_low = be32dec(p);
  310         uuid->time_mid = le16dec(p + 4);
  311         uuid->time_hi_and_version = be16dec(p + 6);
  312         uuid->clock_seq_hi_and_reserved = p[8];
  313         uuid->clock_seq_low = p[9];
  314         for (i = 0; i < _UUID_NODE_LEN; i++)
  315                 uuid->node[i] = p[10 + i];
  316 }

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