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 /*-
    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 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD: releng/8.3/sys/kern/kern_uuid.c 199583 2009-11-20 15:27:52Z jhb $");
   29 
   30 #include <sys/param.h>
   31 #include <sys/endian.h>
   32 #include <sys/kernel.h>
   33 #include <sys/lock.h>
   34 #include <sys/mutex.h>
   35 #include <sys/sbuf.h>
   36 #include <sys/socket.h>
   37 #include <sys/sysproto.h>
   38 #include <sys/systm.h>
   39 #include <sys/jail.h>
   40 #include <sys/uuid.h>
   41 
   42 #include <net/if.h>
   43 #include <net/if_dl.h>
   44 #include <net/if_types.h>
   45 #include <net/vnet.h>
   46 
   47 /*
   48  * See also:
   49  *      http://www.opengroup.org/dce/info/draft-leach-uuids-guids-01.txt
   50  *      http://www.opengroup.org/onlinepubs/009629399/apdxa.htm
   51  *
   52  * Note that the generator state is itself an UUID, but the time and clock
   53  * sequence fields are written in the native byte order.
   54  */
   55 
   56 CTASSERT(sizeof(struct uuid) == 16);
   57 
   58 /* We use an alternative, more convenient representation in the generator. */
   59 struct uuid_private {
   60         union {
   61                 uint64_t        ll;             /* internal. */
   62                 struct {
   63                         uint32_t        low;
   64                         uint16_t        mid;
   65                         uint16_t        hi;
   66                 } x;
   67         } time;
   68         uint16_t        seq;                    /* Big-endian. */
   69         uint16_t        node[UUID_NODE_LEN>>1];
   70 };
   71 
   72 CTASSERT(sizeof(struct uuid_private) == 16);
   73 
   74 static struct uuid_private uuid_last;
   75 
   76 static struct mtx uuid_mutex;
   77 MTX_SYSINIT(uuid_lock, &uuid_mutex, "UUID generator mutex lock", MTX_DEF);
   78 
   79 /*
   80  * Return the first MAC address we encounter or, if none was found,
   81  * construct a sufficiently random multicast address. We don't try
   82  * to return the same MAC address as previously returned. We always
   83  * generate a new multicast address if no MAC address exists in the
   84  * system.
   85  * It would be nice to know if 'ifnet' or any of its sub-structures
   86  * has been changed in any way. If not, we could simply skip the
   87  * scan and safely return the MAC address we returned before.
   88  */
   89 static void
   90 uuid_node(uint16_t *node)
   91 {
   92         struct ifnet *ifp;
   93         struct ifaddr *ifa;
   94         struct sockaddr_dl *sdl;
   95         int i;
   96 
   97         CURVNET_SET(TD_TO_VNET(curthread));
   98         IFNET_RLOCK_NOSLEEP();
   99         TAILQ_FOREACH(ifp, &V_ifnet, if_link) {
  100                 /* Walk the address list */
  101                 IF_ADDR_LOCK(ifp);
  102                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
  103                         sdl = (struct sockaddr_dl*)ifa->ifa_addr;
  104                         if (sdl != NULL && sdl->sdl_family == AF_LINK &&
  105                             sdl->sdl_type == IFT_ETHER) {
  106                                 /* Got a MAC address. */
  107                                 bcopy(LLADDR(sdl), node, UUID_NODE_LEN);
  108                                 IF_ADDR_UNLOCK(ifp);
  109                                 IFNET_RUNLOCK_NOSLEEP();
  110                                 CURVNET_RESTORE();
  111                                 return;
  112                         }
  113                 }
  114                 IF_ADDR_UNLOCK(ifp);
  115         }
  116         IFNET_RUNLOCK_NOSLEEP();
  117 
  118         for (i = 0; i < (UUID_NODE_LEN>>1); i++)
  119                 node[i] = (uint16_t)arc4random();
  120         *((uint8_t*)node) |= 0x01;
  121         CURVNET_RESTORE();
  122 }
  123 
  124 /*
  125  * Get the current time as a 60 bit count of 100-nanosecond intervals
  126  * since 00:00:00.00, October 15,1582. We apply a magic offset to convert
  127  * the Unix time since 00:00:00.00, January 1, 1970 to the date of the
  128  * Gregorian reform to the Christian calendar.
  129  */
  130 static uint64_t
  131 uuid_time(void)
  132 {
  133         struct bintime bt;
  134         uint64_t time = 0x01B21DD213814000LL;
  135 
  136         bintime(&bt);
  137         time += (uint64_t)bt.sec * 10000000LL;
  138         time += (10000000LL * (uint32_t)(bt.frac >> 32)) >> 32;
  139         return (time & ((1LL << 60) - 1LL));
  140 }
  141 
  142 struct uuid *
  143 kern_uuidgen(struct uuid *store, size_t count)
  144 {
  145         struct uuid_private uuid;
  146         uint64_t time;
  147         size_t n;
  148 
  149         mtx_lock(&uuid_mutex);
  150 
  151         uuid_node(uuid.node);
  152         time = uuid_time();
  153 
  154         if (uuid_last.time.ll == 0LL || uuid_last.node[0] != uuid.node[0] ||
  155             uuid_last.node[1] != uuid.node[1] ||
  156             uuid_last.node[2] != uuid.node[2])
  157                 uuid.seq = (uint16_t)arc4random() & 0x3fff;
  158         else if (uuid_last.time.ll >= time)
  159                 uuid.seq = (uuid_last.seq + 1) & 0x3fff;
  160         else
  161                 uuid.seq = uuid_last.seq;
  162 
  163         uuid_last = uuid;
  164         uuid_last.time.ll = (time + count - 1) & ((1LL << 60) - 1LL);
  165 
  166         mtx_unlock(&uuid_mutex);
  167 
  168         /* Set sequence and variant and deal with byte order. */
  169         uuid.seq = htobe16(uuid.seq | 0x8000);
  170 
  171         for (n = 0; n < count; n++) {
  172                 /* Set time and version (=1). */
  173                 uuid.time.x.low = (uint32_t)time;
  174                 uuid.time.x.mid = (uint16_t)(time >> 32);
  175                 uuid.time.x.hi = ((uint16_t)(time >> 48) & 0xfff) | (1 << 12);
  176                 store[n] = *(struct uuid *)&uuid;
  177                 time++;
  178         }
  179 
  180         return (store);
  181 }
  182 
  183 #ifndef _SYS_SYSPROTO_H_
  184 struct uuidgen_args {
  185         struct uuid *store;
  186         int     count;
  187 };
  188 #endif
  189 int
  190 uuidgen(struct thread *td, struct uuidgen_args *uap)
  191 {
  192         struct uuid *store;
  193         size_t count;
  194         int error;
  195 
  196         /*
  197          * Limit the number of UUIDs that can be created at the same time
  198          * to some arbitrary number. This isn't really necessary, but I
  199          * like to have some sort of upper-bound that's less than 2G :-)
  200          * XXX probably needs to be tunable.
  201          */
  202         if (uap->count < 1 || uap->count > 2048)
  203                 return (EINVAL);
  204 
  205         count = uap->count;
  206         store = malloc(count * sizeof(struct uuid), M_TEMP, M_WAITOK);
  207         kern_uuidgen(store, count);
  208         error = copyout(store, uap->store, count * sizeof(struct uuid));
  209         free(store, M_TEMP);
  210         return (error);
  211 }
  212 
  213 int
  214 snprintf_uuid(char *buf, size_t sz, struct uuid *uuid)
  215 {
  216         struct uuid_private *id;
  217         int cnt;
  218 
  219         id = (struct uuid_private *)uuid;
  220         cnt = snprintf(buf, sz, "%08x-%04x-%04x-%04x-%04x%04x%04x",
  221             id->time.x.low, id->time.x.mid, id->time.x.hi, be16toh(id->seq),
  222             be16toh(id->node[0]), be16toh(id->node[1]), be16toh(id->node[2]));
  223         return (cnt);
  224 }
  225 
  226 int
  227 printf_uuid(struct uuid *uuid)
  228 {
  229         char buf[38];
  230 
  231         snprintf_uuid(buf, sizeof(buf), uuid);
  232         return (printf("%s", buf));
  233 }
  234 
  235 int
  236 sbuf_printf_uuid(struct sbuf *sb, struct uuid *uuid)
  237 {
  238         char buf[38];
  239 
  240         snprintf_uuid(buf, sizeof(buf), uuid);
  241         return (sbuf_printf(sb, "%s", buf));
  242 }
  243 
  244 /*
  245  * Encode/Decode UUID into byte-stream.
  246  *   http://www.opengroup.org/dce/info/draft-leach-uuids-guids-01.txt
  247  *
  248  * 0                   1                   2                   3
  249  *   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
  250  *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  251  *  |                          time_low                             |
  252  *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  253  *  |       time_mid                |         time_hi_and_version   |
  254  *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  255  *  |clk_seq_hi_res |  clk_seq_low  |         node (0-1)            |
  256  *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  257  *  |                         node (2-5)                            |
  258  *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  259  */
  260 
  261 void
  262 le_uuid_enc(void *buf, struct uuid const *uuid)
  263 {
  264         u_char *p;
  265         int i;
  266 
  267         p = buf;
  268         le32enc(p, uuid->time_low);
  269         le16enc(p + 4, uuid->time_mid);
  270         le16enc(p + 6, uuid->time_hi_and_version);
  271         p[8] = uuid->clock_seq_hi_and_reserved;
  272         p[9] = uuid->clock_seq_low;
  273         for (i = 0; i < _UUID_NODE_LEN; i++)
  274                 p[10 + i] = uuid->node[i];
  275 }
  276 
  277 void
  278 le_uuid_dec(void const *buf, struct uuid *uuid)
  279 {
  280         u_char const *p;
  281         int i;
  282 
  283         p = buf;
  284         uuid->time_low = le32dec(p);
  285         uuid->time_mid = le16dec(p + 4);
  286         uuid->time_hi_and_version = le16dec(p + 6);
  287         uuid->clock_seq_hi_and_reserved = p[8];
  288         uuid->clock_seq_low = p[9];
  289         for (i = 0; i < _UUID_NODE_LEN; i++)
  290                 uuid->node[i] = p[10 + i];
  291 }
  292 
  293 void
  294 be_uuid_enc(void *buf, struct uuid const *uuid)
  295 {
  296         u_char *p;
  297         int i;
  298 
  299         p = buf;
  300         be32enc(p, uuid->time_low);
  301         be16enc(p + 4, uuid->time_mid);
  302         be16enc(p + 6, uuid->time_hi_and_version);
  303         p[8] = uuid->clock_seq_hi_and_reserved;
  304         p[9] = uuid->clock_seq_low;
  305         for (i = 0; i < _UUID_NODE_LEN; i++)
  306                 p[10 + i] = uuid->node[i];
  307 }
  308 
  309 void
  310 be_uuid_dec(void const *buf, struct uuid *uuid)
  311 {
  312         u_char const *p;
  313         int i;
  314 
  315         p = buf;
  316         uuid->time_low = be32dec(p);
  317         uuid->time_mid = le16dec(p + 4);
  318         uuid->time_hi_and_version = be16dec(p + 6);
  319         uuid->clock_seq_hi_and_reserved = p[8];
  320         uuid->clock_seq_low = p[9];
  321         for (i = 0; i < _UUID_NODE_LEN; i++)
  322                 uuid->node[i] = p[10 + i];
  323 }
  324 
  325 int
  326 parse_uuid(const char *str, struct uuid *uuid)
  327 {
  328         u_int c[11];
  329         int n;
  330 
  331         /* An empty string represents a nil UUID. */
  332         if (*str == '\0') {
  333                 bzero(uuid, sizeof(*uuid));
  334                 return (0);
  335         }
  336 
  337         /* The UUID string representation has a fixed length. */
  338         if (strlen(str) != 36)
  339                 return (EINVAL);
  340 
  341         /*
  342          * We only work with "new" UUIDs. New UUIDs have the form:
  343          *      01234567-89ab-cdef-0123-456789abcdef
  344          * The so called "old" UUIDs, which we don't support, have the form:
  345          *      0123456789ab.cd.ef.01.23.45.67.89.ab
  346          */
  347         if (str[8] != '-')
  348                 return (EINVAL);
  349 
  350         n = sscanf(str, "%8x-%4x-%4x-%2x%2x-%2x%2x%2x%2x%2x%2x", c + 0, c + 1,
  351             c + 2, c + 3, c + 4, c + 5, c + 6, c + 7, c + 8, c + 9, c + 10);
  352         /* Make sure we have all conversions. */
  353         if (n != 11)
  354                 return (EINVAL);
  355 
  356         /* Successful scan. Build the UUID. */
  357         uuid->time_low = c[0];
  358         uuid->time_mid = c[1];
  359         uuid->time_hi_and_version = c[2];
  360         uuid->clock_seq_hi_and_reserved = c[3];
  361         uuid->clock_seq_low = c[4];
  362         for (n = 0; n < 6; n++)
  363                 uuid->node[n] = c[n + 5];
  364 
  365         /* Check semantics... */
  366         return (((c[3] & 0x80) != 0x00 &&               /* variant 0? */
  367             (c[3] & 0xc0) != 0x80 &&                    /* variant 1? */
  368             (c[3] & 0xe0) != 0xc0) ? EINVAL : 0);       /* variant 2? */
  369 }

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