release/src/router/busybox/e2fsprogs/uuid/gen_uuid.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * gen_uuid.c --- generate a DCE-compatible uuid
   4  *
   5  * Copyright (C) 1996, 1997, 1998, 1999 Theodore Ts'o.
   6  *
   7  * %Begin-Header%
   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  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, and the entire permission notice in its entirety,
  13  *    including the disclaimer of warranties.
  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  * 3. The name of the author may not be used to endorse or promote
  18  *    products derived from this software without specific prior
  19  *    written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
  22  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  23  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
  24  * WHICH ARE HEREBY DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE
  25  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  26  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
  27  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
  28  * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  29  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  30  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
  31  * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
  32  * DAMAGE.
  33  * %End-Header%
  34  */
  35
  36 #include <unistd.h>
  37 #include <stdlib.h>
  38 #include <string.h>
  39 #include <fcntl.h>
  40 #include <errno.h>
  41 #include <sys/types.h>
  42 #include <sys/stat.h>
  43 #include <sys/file.h>
  44 #include <sys/time.h>
  45 #ifdef HAVE_SYS_IOCTL_H
  46 #include <sys/ioctl.h>
  47 #endif
  48 #include <sys/socket.h>
  49 #ifdef HAVE_SYS_SOCKIO_H
  50 #include <sys/sockio.h>
  51 #endif
  52 #ifdef HAVE_NET_IF_H
  53 #include <net/if.h>
  54 #endif
  55 #ifdef HAVE_NETINET_IN_H
  56 #include <netinet/in.h>
  57 #endif
  58 #ifdef HAVE_NET_IF_DL_H
  59 #include <net/if_dl.h>
  60 #endif
  61
  62 #include "uuidP.h"
  63
  64 #ifdef HAVE_SRANDOM
  65 #define srand(x)        srandom(x)
  66 #define rand()          random()
  67 #endif
  68
  69 static int get_random_fd(void)
  70 {
  71         struct timeval  tv;
  72         static int      fd = -2;
  73         int             i;
  74
  75         if (fd == -2) {
  76                 gettimeofday(&tv, 0);
  77                 fd = open("/dev/urandom", O_RDONLY);
  78                 if (fd == -1)
  79                         fd = open("/dev/random", O_RDONLY | O_NONBLOCK);
  80                 srand((getpid() << 16) ^ getuid() ^ tv.tv_sec ^ tv.tv_usec);
  81         }
  82         /* Crank the random number generator a few times */
  83         gettimeofday(&tv, 0);
  84         for (i = (tv.tv_sec ^ tv.tv_usec) & 0x1F; i > 0; i--)
  85                 rand();
  86         return fd;
  87 }
  88
  89
  90 /*
  91  * Generate a series of random bytes.  Use /dev/urandom if possible,
  92  * and if not, use srandom/random.
  93  */
  94 static void get_random_bytes(void *buf, int nbytes)
  95 {
  96         int i, n = nbytes, fd = get_random_fd();
  97         int lose_counter = 0;
  98         unsigned char *cp = (unsigned char *) buf;
  99
 100         if (fd >= 0) {
 101                 while (n > 0) {
 102                         i = read(fd, cp, n);
 103                         if (i <= 0) {
 104                                 if (lose_counter++ > 16)
 105                                         break;
 106                                 continue;
 107                         }
 108                         n -= i;
 109                         cp += i;
 110                         lose_counter = 0;
 111                 }
 112         }
 113
 114         /*
 115          * We do this all the time, but this is the only source of
 116          * randomness if /dev/random/urandom is out to lunch.
 117          */
 118         for (cp = buf, i = 0; i < nbytes; i++)
 119                 *cp++ ^= (rand() >> 7) & 0xFF;
 120 }
 121
 122 /*
 123  * Get the ethernet hardware address, if we can find it...
 124  */
 125 static int get_node_id(unsigned char *node_id)
 126 {
 127 #ifdef HAVE_NET_IF_H
 128         int             sd;
 129         struct ifreq    ifr, *ifrp;
 130         struct ifconf   ifc;
 131         char buf[1024];
 132         int             n, i;
 133         unsigned char   *a;
 134 #ifdef HAVE_NET_IF_DL_H
 135         struct sockaddr_dl *sdlp;
 136 #endif
 137
 138 /*
 139  * BSD 4.4 defines the size of an ifreq to be
 140  * max(sizeof(ifreq), sizeof(ifreq.ifr_name)+ifreq.ifr_addr.sa_len
 141  * However, under earlier systems, sa_len isn't present, so the size is
 142  * just sizeof(struct ifreq)
 143  */
 144 #ifdef HAVE_SA_LEN
 145 #ifndef max
 146 #define max(a,b) ((a) > (b) ? (a) : (b))
 147 #endif
 148 #define ifreq_size(i) max(sizeof(struct ifreq),\
 149      sizeof((i).ifr_name)+(i).ifr_addr.sa_len)
 150 #else
 151 #define ifreq_size(i) sizeof(struct ifreq)
 152 #endif /* HAVE_SA_LEN*/
 153
 154         sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
 155         if (sd < 0) {
 156                 return -1;
 157         }
 158         memset(buf, 0, sizeof(buf));
 159         ifc.ifc_len = sizeof(buf);
 160         ifc.ifc_buf = buf;
 161         if (ioctl (sd, SIOCGIFCONF, (char *)&ifc) < 0) {
 162                 close(sd);
 163                 return -1;
 164         }
 165         n = ifc.ifc_len;
 166         for (i = 0; i < n; i+= ifreq_size(*ifrp) ) {
 167                 ifrp = (struct ifreq *)((char *) ifc.ifc_buf+i);
 168                 strncpy_IFNAMSIZ(ifr.ifr_name, ifrp->ifr_name);
 169 #ifdef SIOCGIFHWADDR
 170                 if (ioctl(sd, SIOCGIFHWADDR, &ifr) < 0)
 171                         continue;
 172                 a = (unsigned char *) &ifr.ifr_hwaddr.sa_data;
 173 #else
 174 #ifdef SIOCGENADDR
 175                 if (ioctl(sd, SIOCGENADDR, &ifr) < 0)
 176                         continue;
 177                 a = (unsigned char *) ifr.ifr_enaddr;
 178 #else
 179 #ifdef HAVE_NET_IF_DL_H
 180                 sdlp = (struct sockaddr_dl *) &ifrp->ifr_addr;
 181                 if ((sdlp->sdl_family != AF_LINK) || (sdlp->sdl_alen != 6))
 182                         continue;
 183                 a = (unsigned char *) &sdlp->sdl_data[sdlp->sdl_nlen];
 184 #else
 185                 /*
 186                  * XXX we don't have a way of getting the hardware
 187                  * address
 188                  */
 189                 close(sd);
 190                 return 0;
 191 #endif /* HAVE_NET_IF_DL_H */
 192 #endif /* SIOCGENADDR */
 193 #endif /* SIOCGIFHWADDR */
 194                 if (!a[0] && !a[1] && !a[2] && !a[3] && !a[4] && !a[5])
 195                         continue;
 196                 if (node_id) {
 197                         memcpy(node_id, a, 6);
 198                         close(sd);
 199                         return 1;
 200                 }
 201         }
 202         close(sd);
 203 #endif
 204         return 0;
 205 }
 206
 207 /* Assume that the gettimeofday() has microsecond granularity */
 208 #define MAX_ADJUSTMENT 10
 209
 210 static int get_clock(uint32_t *clock_high, uint32_t *clock_low, uint16_t *ret_clock_seq)
 211 {
 212         static int                      adjustment = 0;
 213         static struct timeval           last = {0, 0};
 214         static uint16_t                 clock_seq;
 215         struct timeval                  tv;
 216         unsigned long long              clock_reg;
 217
 218 try_again:
 219         gettimeofday(&tv, 0);
 220         if ((last.tv_sec == 0) && (last.tv_usec == 0)) {
 221                 get_random_bytes(&clock_seq, sizeof(clock_seq));
 222                 clock_seq &= 0x3FFF;
 223                 last = tv;
 224                 last.tv_sec--;
 225         }
 226         if ((tv.tv_sec < last.tv_sec) ||
 227             ((tv.tv_sec == last.tv_sec) &&
 228              (tv.tv_usec < last.tv_usec))) {
 229                 clock_seq = (clock_seq+1) & 0x3FFF;
 230                 adjustment = 0;
 231                 last = tv;
 232         } else if ((tv.tv_sec == last.tv_sec) &&
 233             (tv.tv_usec == last.tv_usec)) {
 234                 if (adjustment >= MAX_ADJUSTMENT)
 235                         goto try_again;
 236                 adjustment++;
 237         } else {
 238                 adjustment = 0;
 239                 last = tv;
 240         }
 241
 242         clock_reg = tv.tv_usec*10 + adjustment;
 243         clock_reg += ((unsigned long long) tv.tv_sec)*10000000;
 244         clock_reg += (((unsigned long long) 0x01B21DD2) << 32) + 0x13814000;
 245
 246         *clock_high = clock_reg >> 32;
 247         *clock_low = clock_reg;
 248         *ret_clock_seq = clock_seq;
 249         return 0;
 250 }
 251
 252 void uuid_generate_time(uuid_t out)
 253 {
 254         static unsigned char node_id[6];
 255         static int has_init = 0;
 256         struct uuid uu;
 257         uint32_t        clock_mid;
 258
 259         if (!has_init) {
 260                 if (get_node_id(node_id) <= 0) {
 261                         get_random_bytes(node_id, 6);
 262                         /*
 263                          * Set multicast bit, to prevent conflicts
 264                          * with IEEE 802 addresses obtained from
 265                          * network cards
 266                          */
 267                         node_id[0] |= 0x01;
 268                 }
 269                 has_init = 1;
 270         }
 271         get_clock(&clock_mid, &uu.time_low, &uu.clock_seq);
 272         uu.clock_seq |= 0x8000;
 273         uu.time_mid = (uint16_t) clock_mid;
 274         uu.time_hi_and_version = ((clock_mid >> 16) & 0x0FFF) | 0x1000;
 275         memcpy(uu.node, node_id, 6);
 276         uuid_pack(&uu, out);
 277 }
 278
 279 void uuid_generate_random(uuid_t out)
 280 {
 281         uuid_t  buf;
 282         struct uuid uu;
 283
 284         get_random_bytes(buf, sizeof(buf));
 285         uuid_unpack(buf, &uu);
 286
 287         uu.clock_seq = (uu.clock_seq & 0x3FFF) | 0x8000;
 288         uu.time_hi_and_version = (uu.time_hi_and_version & 0x0FFF) | 0x4000;
 289         uuid_pack(&uu, out);
 290 }
 291
 292 /*
 293  * This is the generic front-end to uuid_generate_random and
 294  * uuid_generate_time.  It uses uuid_generate_random only if
 295  * /dev/urandom is available, since otherwise we won't have
 296  * high-quality randomness.
 297  */
 298 void uuid_generate(uuid_t out)
 299 {
 300         if (get_random_fd() >= 0)
 301                 uuid_generate_random(out);
 302         else
 303                 uuid_generate_time(out);
 304 }