lib/uuid/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 #include <stdio.h>
  42 #ifdef HAVE_UNISTD_H
  43 #include <unistd.h>
  44 #endif
  45 #ifdef HAVE_STDLIB_H
  46 #include <stdlib.h>
  47 #endif
  48 #include <string.h>
  49 #include <fcntl.h>
  50 #include <errno.h>
  51 #include <sys/types.h>
  52 #include <sys/time.h>
  53 #include <sys/wait.h>
  54 #include <sys/stat.h>
  55 #include <sys/file.h>
  56 #ifdef HAVE_SYS_IOCTL_H
  57 #include <sys/ioctl.h>
  58 #endif
  59 #ifdef HAVE_SYS_SOCKET_H
  60 #include <sys/socket.h>
  61 #endif
  62 #include <sys/un.h>
  63 #ifdef HAVE_SYS_SOCKIO_H
  64 #include <sys/sockio.h>
  65 #endif
  66 #ifdef HAVE_NET_IF_H
  67 #include <net/if.h>
  68 #endif
  69 #ifdef HAVE_NETINET_IN_H
  70 #include <netinet/in.h>
  71 #endif
  72 #ifdef HAVE_NET_IF_DL_H
  73 #include <net/if_dl.h>
  74 #endif
  75 #if defined(__linux__) && defined(HAVE_SYS_SYSCALL_H)
  76 #include <sys/syscall.h>
  77 #endif
  78
  79 #include "uuidP.h"
  80 #include "uuidd.h"
  81
  82 #ifdef HAVE_SRANDOM
  83 #define srand(x)        srandom(x)
  84 #define rand()          random()
  85 #endif
  86
  87 #ifdef TLS
  88 #define THREAD_LOCAL static TLS
  89 #else
  90 #define THREAD_LOCAL static
  91 #endif
  92
  93 #if defined(__linux__) && defined(__NR_gettid) && defined(HAVE_JRAND48)
  94 #define DO_JRAND_MIX
  95 THREAD_LOCAL unsigned short jrand_seed[3];
  96 #endif
  97
  98 static int get_random_fd(void)
  99 {
 100         struct timeval  tv;
 101         static int      fd = -2;
 102         int             i;
 103
 104         if (fd == -2) {
 105                 gettimeofday(&tv, 0);
 106                 fd = open("/dev/urandom", O_RDONLY);
 107                 if (fd == -1)
 108                         fd = open("/dev/random", O_RDONLY | O_NONBLOCK);
 109                 if (fd >= 0) {
 110                         i = fcntl(fd, F_GETFD);
 111                         if (i >= 0)
 112                                 fcntl(fd, F_SETFD, i | FD_CLOEXEC);
 113                 }
 114                 srand((getpid() << 16) ^ getuid() ^ tv.tv_sec ^ tv.tv_usec);
 115 #ifdef DO_JRAND_MIX
 116                 jrand_seed[0] = getpid() ^ (tv.tv_sec & 0xFFFF);
 117                 jrand_seed[1] = getppid() ^ (tv.tv_usec & 0xFFFF);
 118                 jrand_seed[2] = (tv.tv_sec ^ tv.tv_usec) >> 16;
 119 #endif
 120         }
 121         /* Crank the random number generator a few times */
 122         gettimeofday(&tv, 0);
 123         for (i = (tv.tv_sec ^ tv.tv_usec) & 0x1F; i > 0; i--)
 124                 rand();
 125         return fd;
 126 }
 127
 128
 129 /*
 130  * Generate a series of random bytes.  Use /dev/urandom if possible,
 131  * and if not, use srandom/random.
 132  */
 133 static void get_random_bytes(void *buf, int nbytes)
 134 {
 135         int i, n = nbytes, fd = get_random_fd();
 136         int lose_counter = 0;
 137         unsigned char *cp = (unsigned char *) buf;
 138         unsigned short tmp_seed[3];
 139
 140         if (fd >= 0) {
 141                 while (n > 0) {
 142                         i = read(fd, cp, n);
 143                         if (i <= 0) {
 144                                 if (lose_counter++ > 16)
 145                                         break;
 146                                 continue;
 147                         }
 148                         n -= i;
 149                         cp += i;
 150                         lose_counter = 0;
 151                 }
 152         }
 153
 154         /*
 155          * We do this all the time, but this is the only source of
 156          * randomness if /dev/random/urandom is out to lunch.
 157          */
 158         for (cp = buf, i = 0; i < nbytes; i++)
 159                 *cp++ ^= (rand() >> 7) & 0xFF;
 160 #ifdef DO_JRAND_MIX
 161         memcpy(tmp_seed, jrand_seed, sizeof(tmp_seed));
 162         jrand_seed[2] = jrand_seed[2] ^ syscall(__NR_gettid);
 163         for (cp = buf, i = 0; i < nbytes; i++)
 164                 *cp++ ^= (jrand48(tmp_seed) >> 7) & 0xFF;
 165         memcpy(jrand_seed, tmp_seed,
 166                sizeof(jrand_seed)-sizeof(unsigned short));
 167 #endif
 168
 169         return;
 170 }
 171
 172 /*
 173  * Get the ethernet hardware address, if we can find it...
 174  */
 175 static int get_node_id(unsigned char *node_id)
 176 {
 177 #ifdef HAVE_NET_IF_H
 178         int             sd;
 179         struct ifreq    ifr, *ifrp;
 180         struct ifconf   ifc;
 181         char buf[1024];
 182         int             n, i;
 183         unsigned char   *a;
 184 #ifdef HAVE_NET_IF_DL_H
 185         struct sockaddr_dl *sdlp;
 186 #endif
 187
 188 /*
 189  * BSD 4.4 defines the size of an ifreq to be
 190  * max(sizeof(ifreq), sizeof(ifreq.ifr_name)+ifreq.ifr_addr.sa_len
 191  * However, under earlier systems, sa_len isn't present, so the size is
 192  * just sizeof(struct ifreq)
 193  */
 194 #ifdef HAVE_SA_LEN
 195 #ifndef max
 196 #define max(a,b) ((a) > (b) ? (a) : (b))
 197 #endif
 198 #define ifreq_size(i) max(sizeof(struct ifreq),\
 199      sizeof((i).ifr_name)+(i).ifr_addr.sa_len)
 200 #else
 201 #define ifreq_size(i) sizeof(struct ifreq)
 202 #endif /* HAVE_SA_LEN*/
 203
 204         sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
 205         if (sd < 0) {
 206                 return -1;
 207         }
 208         memset(buf, 0, sizeof(buf));
 209         ifc.ifc_len = sizeof(buf);
 210         ifc.ifc_buf = buf;
 211         if (ioctl (sd, SIOCGIFCONF, (char *)&ifc) < 0) {
 212                 close(sd);
 213                 return -1;
 214         }
 215         n = ifc.ifc_len;
 216         for (i = 0; i < n; i+= ifreq_size(*ifrp) ) {
 217                 ifrp = (struct ifreq *)((char *) ifc.ifc_buf+i);
 218                 strncpy(ifr.ifr_name, ifrp->ifr_name, IFNAMSIZ);
 219 #ifdef SIOCGIFHWADDR
 220                 if (ioctl(sd, SIOCGIFHWADDR, &ifr) < 0)
 221                         continue;
 222                 a = (unsigned char *) &ifr.ifr_hwaddr.sa_data;
 223 #else
 224 #ifdef SIOCGENADDR
 225                 if (ioctl(sd, SIOCGENADDR, &ifr) < 0)
 226                         continue;
 227                 a = (unsigned char *) ifr.ifr_enaddr;
 228 #else
 229 #ifdef HAVE_NET_IF_DL_H
 230                 sdlp = (struct sockaddr_dl *) &ifrp->ifr_addr;
 231                 if ((sdlp->sdl_family != AF_LINK) || (sdlp->sdl_alen != 6))
 232                         continue;
 233                 a = (unsigned char *) &sdlp->sdl_data[sdlp->sdl_nlen];
 234 #else
 235                 /*
 236                  * XXX we don't have a way of getting the hardware
 237                  * address
 238                  */
 239                 close(sd);
 240                 return 0;
 241 #endif /* HAVE_NET_IF_DL_H */
 242 #endif /* SIOCGENADDR */
 243 #endif /* SIOCGIFHWADDR */
 244                 if (!a[0] && !a[1] && !a[2] && !a[3] && !a[4] && !a[5])
 245                         continue;
 246                 if (node_id) {
 247                         memcpy(node_id, a, 6);
 248                         close(sd);
 249                         return 1;
 250                 }
 251         }
 252         close(sd);
 253 #endif
 254         return 0;
 255 }
 256
 257 /* Assume that the gettimeofday() has microsecond granularity */
 258 #define MAX_ADJUSTMENT 10
 259
 260 static int get_clock(uint32_t *clock_high, uint32_t *clock_low,
 261                      uint16_t *ret_clock_seq, int *num)
 262 {
 263         THREAD_LOCAL int                adjustment = 0;
 264         THREAD_LOCAL struct timeval     last = {0, 0};
 265         THREAD_LOCAL int                state_fd = -2;
 266         THREAD_LOCAL FILE               *state_f;
 267         THREAD_LOCAL uint16_t           clock_seq;
 268         struct timeval                  tv;
 269         struct flock                    fl;
 270         unsigned long long              clock_reg;
 271         mode_t                          save_umask;
 272
 273         if (state_fd == -2) {
 274                 save_umask = umask(0);
 275                 state_fd = open("/var/lib/libuuid/clock.txt",
 276                                 O_RDWR|O_CREAT, 0660);
 277                 (void) umask(save_umask);
 278                 state_f = fdopen(state_fd, "r+");
 279                 if (!state_f) {
 280                         close(state_fd);
 281                         state_fd = -1;
 282                 }
 283         }
 284         fl.l_type = F_WRLCK;
 285         fl.l_whence = SEEK_SET;
 286         fl.l_start = 0;
 287         fl.l_len = 0;
 288         fl.l_pid = 0;
 289         if (state_fd >= 0) {
 290                 rewind(state_f);
 291                 while (fcntl(state_fd, F_SETLKW, &fl) < 0) {
 292                         if ((errno == EAGAIN) || (errno == EINTR))
 293                                 continue;
 294                         fclose(state_f);
 295                         close(state_fd);
 296                         state_fd = -1;
 297                         break;
 298                 }
 299         }
 300         if (state_fd >= 0) {
 301                 unsigned int cl;
 302                 unsigned long tv1, tv2;
 303                 int a;
 304
 305                 if (fscanf(state_f, "clock: %04x tv: %lu %lu adj: %d\n",
 306                            &cl, &tv1, &tv2, &a) == 4) {
 307                         clock_seq = cl & 0x3FFF;
 308                         last.tv_sec = tv1;
 309                         last.tv_usec = tv2;
 310                         adjustment = a;
 311                 }
 312         }
 313
 314         if ((last.tv_sec == 0) && (last.tv_usec == 0)) {
 315                 get_random_bytes(&clock_seq, sizeof(clock_seq));
 316                 clock_seq &= 0x3FFF;
 317                 last = tv;
 318                 last.tv_sec--;
 319         }
 320
 321 try_again:
 322         gettimeofday(&tv, 0);
 323         if ((tv.tv_sec < last.tv_sec) ||
 324             ((tv.tv_sec == last.tv_sec) &&
 325              (tv.tv_usec < last.tv_usec))) {
 326                 clock_seq = (clock_seq+1) & 0x3FFF;
 327                 adjustment = 0;
 328                 last = tv;
 329         } else if ((tv.tv_sec == last.tv_sec) &&
 330             (tv.tv_usec == last.tv_usec)) {
 331                 if (adjustment >= MAX_ADJUSTMENT)
 332                         goto try_again;
 333                 adjustment++;
 334         } else {
 335                 adjustment = 0;
 336                 last = tv;
 337         }
 338
 339         clock_reg = tv.tv_usec*10 + adjustment;
 340         clock_reg += ((unsigned long long) tv.tv_sec)*10000000;
 341         clock_reg += (((unsigned long long) 0x01B21DD2) << 32) + 0x13814000;
 342
 343         if (num && (*num > 1)) {
 344                 adjustment += *num - 1;
 345                 last.tv_usec += adjustment / 10;
 346                 adjustment = adjustment % 10;
 347                 last.tv_sec += last.tv_usec / 1000000;
 348                 last.tv_usec = last.tv_usec % 1000000;
 349         }
 350
 351         if (state_fd > 0) {
 352                 rewind(state_f);
 353                 ftruncate(state_fd, 0);
 354                 fprintf(state_f, "clock: %04x tv: %lu %lu adj: %d\n",
 355                         clock_seq, last.tv_sec, last.tv_usec, adjustment);
 356                 fflush(state_f);
 357                 rewind(state_f);
 358                 fl.l_type = F_UNLCK;
 359                 fcntl(state_fd, F_SETLK, &fl);
 360         }
 361
 362         *clock_high = clock_reg >> 32;
 363         *clock_low = clock_reg;
 364         *ret_clock_seq = clock_seq;
 365         return 0;
 366 }
 367
 368 static ssize_t read_all(int fd, char *buf, size_t count)
 369 {
 370         ssize_t ret;
 371         ssize_t c = 0;
 372
 373         memset(buf, 0, count);
 374         while (count > 0) {
 375                 ret = read(fd, buf, count);
 376                 if (ret < 0) {
 377                         if ((errno == EAGAIN) || (errno == EINTR))
 378                                 continue;
 379                         return -1;
 380                 }
 381                 count -= ret;
 382                 buf += ret;
 383                 c += ret;
 384         }
 385         return c;
 386 }
 387
 388
 389 /*
 390  * Try using the uuidd daemon to generate the UUID
 391  *
 392  * Returns 0 on success, non-zero on failure.
 393  */
 394 static int get_uuid_via_daemon(int op, uuid_t out, int *num)
 395 {
 396 #ifdef USE_UUIDD
 397         char op_buf[64];
 398         int op_len;
 399         int s;
 400         ssize_t ret;
 401         int32_t reply_len = 0, expected = 16;
 402         struct sockaddr_un srv_addr;
 403         pid_t pid;
 404         static const char *uuidd_path = UUIDD_PATH;
 405         static int access_ret = -2;
 406         static int start_attempts = 0;
 407
 408         if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
 409                 return -1;
 410
 411         srv_addr.sun_family = AF_UNIX;
 412         strcpy(srv_addr.sun_path, UUIDD_SOCKET_PATH);
 413
 414         if (connect(s, (const struct sockaddr *) &srv_addr,
 415                     sizeof(struct sockaddr_un)) < 0) {
 416                 if (access_ret == -2)
 417                         access_ret = access(uuidd_path, X_OK);
 418                 if (access_ret == 0 && start_attempts++ < 5) {
 419                         if ((pid = fork()) == 0) {
 420                                 execl(uuidd_path, "uuidd", "-qT", "300",
 421                                       (char *) NULL);
 422                                 exit(1);
 423                         }
 424                         (void) waitpid(pid, 0, 0);
 425                         if (connect(s, (const struct sockaddr *) &srv_addr,
 426                                     sizeof(struct sockaddr_un)) < 0)
 427                                 goto fail;
 428                 } else
 429                         goto fail;
 430         }
 431         op_buf[0] = op;
 432         op_len = 1;
 433         if (op == UUIDD_OP_BULK_TIME_UUID) {
 434                 memcpy(op_buf+1, num, sizeof(*num));
 435                 op_len += sizeof(*num);
 436                 expected += sizeof(*num);
 437         }
 438
 439         ret = write(s, op_buf, op_len);
 440         if (ret < 1)
 441                 goto fail;
 442
 443         ret = read_all(s, (char *) &reply_len, sizeof(reply_len));
 444         if (ret < 0)
 445                 goto fail;
 446
 447         if (reply_len != expected)
 448                 goto fail;
 449
 450         ret = read_all(s, op_buf, reply_len);
 451
 452         if (op == UUIDD_OP_BULK_TIME_UUID)
 453                 memcpy(op_buf+16, num, sizeof(int));
 454
 455         memcpy(out, op_buf, 16);
 456
 457         close(s);
 458         return ((ret == expected) ? 0 : -1);
 459
 460 fail:
 461         close(s);
 462 #endif
 463         return -1;
 464 }
 465
 466 void uuid__generate_time(uuid_t out, int *num)
 467 {
 468         static unsigned char node_id[6];
 469         static int has_init = 0;
 470         struct uuid uu;
 471         uint32_t        clock_mid;
 472
 473         if (!has_init) {
 474                 if (get_node_id(node_id) <= 0) {
 475                         get_random_bytes(node_id, 6);
 476                         /*
 477                          * Set multicast bit, to prevent conflicts
 478                          * with IEEE 802 addresses obtained from
 479                          * network cards
 480                          */
 481                         node_id[0] |= 0x01;
 482                 }
 483                 has_init = 1;
 484         }
 485         get_clock(&clock_mid, &uu.time_low, &uu.clock_seq, num);
 486         uu.clock_seq |= 0x8000;
 487         uu.time_mid = (uint16_t) clock_mid;
 488         uu.time_hi_and_version = ((clock_mid >> 16) & 0x0FFF) | 0x1000;
 489         memcpy(uu.node, node_id, 6);
 490         uuid_pack(&uu, out);
 491 }
 492
 493 void uuid_generate_time(uuid_t out)
 494 {
 495 #ifdef TLS
 496         THREAD_LOCAL int                num = 0;
 497         THREAD_LOCAL struct uuid        uu;
 498         THREAD_LOCAL time_t             last_time = 0;
 499         time_t                          now;
 500
 501         if (num > 0) {
 502                 now = time(0);
 503                 if (now > last_time+1)
 504                         num = 0;
 505         }
 506         if (num <= 0) {
 507                 num = 1000;
 508                 if (get_uuid_via_daemon(UUIDD_OP_BULK_TIME_UUID,
 509                                         out, &num) == 0) {
 510                         last_time = time(0);
 511                         uuid_unpack(out, &uu);
 512                         num--;
 513                         return;
 514                 }
 515                 num = 0;
 516         }
 517         if (num > 0) {
 518                 uu.time_low++;
 519                 if (uu.time_low == 0) {
 520                         uu.time_mid++;
 521                         if (uu.time_mid == 0)
 522                                 uu.time_hi_and_version++;
 523                 }
 524                 num--;
 525                 uuid_pack(&uu, out);
 526                 return;
 527         }
 528 #else
 529         if (get_uuid_via_daemon(UUIDD_OP_TIME_UUID, out, 0) == 0)
 530                 return;
 531 #endif
 532
 533         uuid__generate_time(out, 0);
 534 }
 535
 536
 537 void uuid__generate_random(uuid_t out, int *num)
 538 {
 539         uuid_t  buf;
 540         struct uuid uu;
 541         int i, n;
 542
 543         if (!num || !*num)
 544                 n = 1;
 545         else
 546                 n = *num;
 547
 548         for (i = 0; i < n; i++) {
 549                 get_random_bytes(buf, sizeof(buf));
 550                 uuid_unpack(buf, &uu);
 551
 552                 uu.clock_seq = (uu.clock_seq & 0x3FFF) | 0x8000;
 553                 uu.time_hi_and_version = (uu.time_hi_and_version & 0x0FFF)
 554                         | 0x4000;
 555                 uuid_pack(&uu, out);
 556                 out += sizeof(uuid_t);
 557         }
 558 }
 559
 560 void uuid_generate_random(uuid_t out)
 561 {
 562         int     num = 1;
 563         /* No real reason to use the daemon for random uuid's -- yet */
 564
 565         uuid__generate_random(out, &num);
 566 }
 567
 568
 569 /*
 570  * This is the generic front-end to uuid_generate_random and
 571  * uuid_generate_time.  It uses uuid_generate_random only if
 572  * /dev/urandom is available, since otherwise we won't have
 573  * high-quality randomness.
 574  */
 575 void uuid_generate(uuid_t out)
 576 {
 577         if (get_random_fd() >= 0)
 578                 uuid_generate_random(out);
 579         else
 580                 uuid_generate_time(out);
 581 }