uuid/uuidsrc/gen_uuid.c

   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  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, and the entire permission notice in its entirety,
  12  *    including the disclaimer of warranties.
  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  * 3. The name of the author may not be used to endorse or promote
  17  *    products derived from this software without specific prior
  18  *    written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
  21  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  22  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
  23  * WHICH ARE HEREBY DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE
  24  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
  26  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
  27  * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  28  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
  30  * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
  31  * DAMAGE.
  32  * %End-Header%
  33  */
  34
  35 /*
  36  * Force inclusion of SVID stuff since we need it if we're compiling in
  37  * gcc-wall wall mode
  38  */
  39 #define _SVID_SOURCE
  40
  41 #ifdef HAVE_UNISTD_H
  42 #include <unistd.h>
  43 #endif
  44 #ifdef HAVE_STDLIB_H
  45 #include <stdlib.h>
  46 #endif
  47 #include <string.h>
  48 #include <fcntl.h>
  49 #include <errno.h>
  50 #include <sys/types.h>
  51 #include <sys/time.h>
  52 #include <sys/stat.h>
  53 #include <sys/file.h>
  54 #ifdef HAVE_SYS_IOCTL_H
  55 #include <sys/ioctl.h>
  56 #endif
  57 #ifdef HAVE_SYS_SOCKET_H
  58 #include <sys/socket.h>
  59 #endif
  60 #ifdef HAVE_SYS_SOCKIO_H
  61 #include <sys/sockio.h>
  62 #endif
  63 #ifdef HAVE_NET_IF_H
  64 #include <net/if.h>
  65 #endif
  66 #ifdef HAVE_NETINET_IN_H
  67 #include <netinet/in.h>
  68 #endif
  69 #ifdef HAVE_NET_IF_DL_H
  70 #include <net/if_dl.h>
  71 #endif
  72
  73 #include "uuidP.h"
  74
  75 #ifdef HAVE_SRANDOM
  76 #define srand(x)        srandom(x)
  77 #define rand()          random()
  78 #endif
  79
  80 static int get_random_fd(void)
  81 {
  82         struct timeval  tv;
  83         static int      fd = -2;
  84         int             i;
  85
  86         if (fd == -2) {
  87                 gettimeofday(&tv, 0);
  88                 fd = open("/dev/urandom", O_RDONLY);
  89                 if (fd == -1)
  90                         fd = open("/dev/random", O_RDONLY | O_NONBLOCK);
  91                 srand((getpid() << 16) ^ getuid() ^ tv.tv_sec ^ tv.tv_usec);
  92         }
  93         /* Crank the random number generator a few times */
  94         gettimeofday(&tv, 0);
  95         for (i = (tv.tv_sec ^ tv.tv_usec) & 0x1F; i > 0; i--)
  96                 rand();
  97         return fd;
  98 }
  99
 100
 101 /*
 102  * Generate a series of random bytes.  Use /dev/urandom if possible,
 103  * and if not, use srandom/random.
 104  */
 105 static void get_random_bytes(void *buf, int nbytes)
 106 {
 107         int i, n = nbytes, fd = get_random_fd();
 108         int lose_counter = 0;
 109         unsigned char *cp = (unsigned char *) buf;
 110
 111         if (fd >= 0) {
 112                 while (n > 0) {
 113                         i = read(fd, cp, n);
 114                         if (i <= 0) {
 115                                 if (lose_counter++ > 16)
 116                                         break;
 117                                 continue;
 118                         }
 119                         n -= i;
 120                         cp += i;
 121                         lose_counter = 0;
 122                 }
 123         }
 124
 125         /*
 126          * We do this all the time, but this is the only source of
 127          * randomness if /dev/random/urandom is out to lunch.
 128          */
 129         for (cp = buf, i = 0; i < nbytes; i++)
 130                 *cp++ ^= (rand() >> 7) & 0xFF;
 131         return;
 132 }
 133
 134 /*
 135  * Get the ethernet hardware address, if we can find it...
 136  */
 137 static int get_node_id(unsigned char *node_id)
 138 {
 139 #ifdef HAVE_NET_IF_H
 140         int             sd;
 141         struct ifreq    ifr, *ifrp;
 142         struct ifconf   ifc;
 143         char buf[1024];
 144         int             n, i;
 145         unsigned char   *a;
 146 #ifdef AF_LINK
 147         struct sockaddr_dl *sdlp;
 148 #endif
 149
 150 /*
 151  * BSD 4.4 defines the size of an ifreq to be
 152  * max(sizeof(ifreq), sizeof(ifreq.ifr_name)+ifreq.ifr_addr.sa_len
 153  * However, under earlier systems, sa_len isn't present, so the size is
 154  * just sizeof(struct ifreq)
 155  */
 156 #ifdef HAVE_SA_LEN
 157 #ifndef max
 158 #define max(a,b) ((a) > (b) ? (a) : (b))
 159 #endif
 160 #define ifreq_size(i) max(sizeof(struct ifreq),\
 161      sizeof((i).ifr_name)+(i).ifr_addr.sa_len)
 162 #else
 163 #define ifreq_size(i) sizeof(struct ifreq)
 164 #endif /* HAVE_SA_LEN*/
 165
 166         sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
 167         if (sd < 0) {
 168                 return -1;
 169         }
 170         memset(buf, 0, sizeof(buf));
 171         ifc.ifc_len = sizeof(buf);
 172         ifc.ifc_buf = buf;
 173         if (ioctl (sd, SIOCGIFCONF, (char *)&ifc) < 0) {
 174                 close(sd);
 175                 return -1;
 176         }
 177         n = ifc.ifc_len;
 178         for (i = 0; i < n; i+= ifreq_size(*ifrp) ) {
 179                 ifrp = (struct ifreq *)((char *) ifc.ifc_buf+i);
 180                 strncpy(ifr.ifr_name, ifrp->ifr_name, IFNAMSIZ);
 181 #ifdef SIOCGIFHWADDR
 182                 if (ioctl(sd, SIOCGIFHWADDR, &ifr) < 0)
 183                         continue;
 184                 a = (unsigned char *) &ifr.ifr_hwaddr.sa_data;
 185 #else
 186 #ifdef SIOCGENADDR
 187                 if (ioctl(sd, SIOCGENADDR, &ifr) < 0)
 188                         continue;
 189                 a = (unsigned char *) ifr.ifr_enaddr;
 190 #else
 191 #ifdef AF_LINK
 192                 sdlp = (struct sockaddr_dl *) &ifrp->ifr_addr;
 193                 if ((sdlp->sdl_family != AF_LINK) || (sdlp->sdl_alen != 6))
 194                         continue;
 195                 a = (unsigned char *) &sdlp->sdl_data[sdlp->sdl_nlen];
 196 #else
 197                 /*
 198                  * XXX we don't have a way of getting the hardware
 199                  * address
 200                  */
 201                 close(sd);
 202                 return 0;
 203 #endif /* AF_LINK */
 204 #endif /* SIOCGENADDR */
 205 #endif /* SIOCGIFHWADDR */
 206                 if (!a[0] && !a[1] && !a[2] && !a[3] && !a[4] && !a[5])
 207                         continue;
 208                 if (node_id) {
 209                         memcpy(node_id, a, 6);
 210                         close(sd);
 211                         return 1;
 212                 }
 213         }
 214         close(sd);
 215 #endif
 216         return 0;
 217 }
 218
 219 /* Assume that the gettimeofday() has microsecond granularity */
 220 #define MAX_ADJUSTMENT 10
 221
 222 static int get_clock(uint32_t *clock_high, uint32_t *clock_low, uint16_t *ret_clock_seq)
 223 {
 224         static int                      adjustment = 0;
 225         static struct timeval           last = {0, 0};
 226         static uint16_t                 clock_seq;
 227         struct timeval                  tv;
 228         unsigned long long              clock_reg;
 229
 230 try_again:
 231         gettimeofday(&tv, 0);
 232         if ((last.tv_sec == 0) && (last.tv_usec == 0)) {
 233                 get_random_bytes(&clock_seq, sizeof(clock_seq));
 234                 clock_seq &= 0x3FFF;
 235                 last = tv;
 236                 last.tv_sec--;
 237         }
 238         if ((tv.tv_sec < last.tv_sec) ||
 239             ((tv.tv_sec == last.tv_sec) &&
 240              (tv.tv_usec < last.tv_usec))) {
 241                 clock_seq = (clock_seq+1) & 0x3FFF;
 242                 adjustment = 0;
 243                 last = tv;
 244         } else if ((tv.tv_sec == last.tv_sec) &&
 245             (tv.tv_usec == last.tv_usec)) {
 246                 if (adjustment >= MAX_ADJUSTMENT)
 247                         goto try_again;
 248                 adjustment++;
 249         } else {
 250                 adjustment = 0;
 251                 last = tv;
 252         }
 253
 254         clock_reg = tv.tv_usec*10 + adjustment;
 255         clock_reg += ((unsigned long long) tv.tv_sec)*10000000;
 256         clock_reg += (((unsigned long long) 0x01B21DD2) << 32) + 0x13814000;
 257
 258         *clock_high = clock_reg >> 32;
 259         *clock_low = clock_reg;
 260         *ret_clock_seq = clock_seq;
 261         return 0;
 262 }
 263
 264 void uuid_generate_time(uuid_t out)
 265 {
 266         static unsigned char node_id[6];
 267         static int has_init = 0;
 268         struct uuid uu;
 269         uint32_t        clock_mid;
 270
 271         if (!has_init) {
 272                 if (get_node_id(node_id) <= 0) {
 273                         get_random_bytes(node_id, 6);
 274                         /*
 275                          * Set multicast bit, to prevent conflicts
 276                          * with IEEE 802 addresses obtained from
 277                          * network cards
 278                          */
 279                         node_id[0] |= 0x01;
 280                 }
 281                 has_init = 1;
 282         }
 283         get_clock(&clock_mid, &uu.time_low, &uu.clock_seq);
 284         uu.clock_seq |= 0x8000;
 285         uu.time_mid = (uint16_t) clock_mid;
 286         uu.time_hi_and_version = ((clock_mid >> 16) & 0x0FFF) | 0x1000;
 287         memcpy(uu.node, node_id, 6);
 288         uuid_pack(&uu, out);
 289 }
 290
 291 void uuid_generate_random(uuid_t out)
 292 {
 293         uuid_t  buf;
 294         struct uuid uu;
 295
 296         get_random_bytes(buf, sizeof(buf));
 297         uuid_unpack(buf, &uu);
 298
 299         uu.clock_seq = (uu.clock_seq & 0x3FFF) | 0x8000;
 300         uu.time_hi_and_version = (uu.time_hi_and_version & 0x0FFF) | 0x4000;
 301         uuid_pack(&uu, out);
 302 }
 303
 304 /*
 305  * This is the generic front-end to uuid_generate_random and
 306  * uuid_generate_time.  It uses uuid_generate_random only if
 307  * /dev/urandom is available, since otherwise we won't have
 308  * high-quality randomness.
 309  */
 310 void uuid_generate(uuid_t out)
 311 {
 312         if (get_random_fd() >= 0)
 313                 uuid_generate_random(out);
 314         else
 315                 uuid_generate_time(out);
 316 }