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gen_uuid.c

/*
 * gen_uuid.c --- generate a DCE-compatible uuid
 *
 * Copyright (C) 1996, 1997, 1998, 1999 Theodore Ts'o.
 *
 * %Begin-Header%
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, and the entire permission notice in its entirety,
 *    including the disclaimer of warranties.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote
 *    products derived from this software without specific prior
 *    written permission.
 * 
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
 * WHICH ARE HEREBY DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 * %End-Header%
 */

/*
 * Force inclusion of SVID stuff since we need it if we're compiling in
 * gcc-wall wall mode
 */
#define _SVID_SOURCE

#include <stdio.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <sys/file.h>
#ifdef HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>
#endif
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef HAVE_SYS_UN_H
#include <sys/un.h>
#endif
#ifdef HAVE_SYS_SOCKIO_H
#include <sys/sockio.h>
#endif
#ifdef HAVE_NET_IF_H
#include <net/if.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_NET_IF_DL_H
#include <net/if_dl.h>
#endif
#if defined(__linux__) && defined(HAVE_SYS_SYSCALL_H)
#include <sys/syscall.h>
#endif

#include "uuidP.h"
#include "uuidd.h"

#ifdef HAVE_SRANDOM
#define srand(x)  srandom(x)
#define rand()          random()
#endif

#ifdef TLS
#define THREAD_LOCAL static TLS
#else
#define THREAD_LOCAL static
#endif

#if defined(__linux__) && defined(__NR_gettid) && defined(HAVE_JRAND48)
#define DO_JRAND_MIX
THREAD_LOCAL unsigned short jrand_seed[3];
#endif

static int get_random_fd(void)
{
      struct timeval    tv;
      static int  fd = -2;
      int         i;

      if (fd == -2) {
            gettimeofday(&tv, 0);
            fd = open("/dev/urandom", O_RDONLY);
            if (fd == -1)
                  fd = open("/dev/random", O_RDONLY | O_NONBLOCK);
            if (fd >= 0) {
                  i = fcntl(fd, F_GETFD);
                  if (i >= 0) 
                        fcntl(fd, F_SETFD, i | FD_CLOEXEC);
            }
            srand((getpid() << 16) ^ getuid() ^ tv.tv_sec ^ tv.tv_usec);
#ifdef DO_JRAND_MIX
            jrand_seed[0] = getpid() ^ (tv.tv_sec & 0xFFFF);
            jrand_seed[1] = getppid() ^ (tv.tv_usec & 0xFFFF);
            jrand_seed[2] = (tv.tv_sec ^ tv.tv_usec) >> 16;
#endif
      }
      /* Crank the random number generator a few times */
      gettimeofday(&tv, 0);
      for (i = (tv.tv_sec ^ tv.tv_usec) & 0x1F; i > 0; i--)
            rand();
      return fd;
}


/*
 * Generate a series of random bytes.  Use /dev/urandom if possible,
 * and if not, use srandom/random.
 */
static void get_random_bytes(void *buf, int nbytes)
{
      int i, n = nbytes, fd = get_random_fd();
      int lose_counter = 0;
      unsigned char *cp = (unsigned char *) buf;
      unsigned short tmp_seed[3];

      if (fd >= 0) {
            while (n > 0) {
                  i = read(fd, cp, n);
                  if (i <= 0) {
                        if (lose_counter++ > 16)
                              break;
                        continue;
                  }
                  n -= i;
                  cp += i;
                  lose_counter = 0;
            }
      }
      
      /*
       * We do this all the time, but this is the only source of
       * randomness if /dev/random/urandom is out to lunch.
       */
      for (cp = buf, i = 0; i < nbytes; i++)
            *cp++ ^= (rand() >> 7) & 0xFF;
#ifdef DO_JRAND_MIX
      memcpy(tmp_seed, jrand_seed, sizeof(tmp_seed));
      jrand_seed[2] = jrand_seed[2] ^ syscall(__NR_gettid);
      for (cp = buf, i = 0; i < nbytes; i++)
            *cp++ ^= (jrand48(tmp_seed) >> 7) & 0xFF;
      memcpy(jrand_seed, tmp_seed, 
             sizeof(jrand_seed)-sizeof(unsigned short));
#endif

      return;
}

/*
 * Get the ethernet hardware address, if we can find it...
 */
static int get_node_id(unsigned char *node_id)
{
#ifdef HAVE_NET_IF_H
      int         sd;
      struct ifreq      ifr, *ifrp;
      struct ifconf     ifc;
      char buf[1024];
      int         n, i;
      unsigned char     *a;
#ifdef HAVE_NET_IF_DL_H
      struct sockaddr_dl *sdlp;
#endif

/*
 * BSD 4.4 defines the size of an ifreq to be
 * max(sizeof(ifreq), sizeof(ifreq.ifr_name)+ifreq.ifr_addr.sa_len
 * However, under earlier systems, sa_len isn't present, so the size is 
 * just sizeof(struct ifreq)
 */
#ifdef HAVE_SA_LEN
#ifndef max
#define max(a,b) ((a) > (b) ? (a) : (b))
#endif
#define ifreq_size(i) max(sizeof(struct ifreq),\
     sizeof((i).ifr_name)+(i).ifr_addr.sa_len)
#else
#define ifreq_size(i) sizeof(struct ifreq)
#endif /* HAVE_SA_LEN*/

      sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
      if (sd < 0) {
            return -1;
      }
      memset(buf, 0, sizeof(buf));
      ifc.ifc_len = sizeof(buf);
      ifc.ifc_buf = buf;
      if (ioctl (sd, SIOCGIFCONF, (char *)&ifc) < 0) {
            close(sd);
            return -1;
      }
      n = ifc.ifc_len;
      for (i = 0; i < n; i+= ifreq_size(*ifrp) ) {
            ifrp = (struct ifreq *)((char *) ifc.ifc_buf+i);
            strncpy(ifr.ifr_name, ifrp->ifr_name, IFNAMSIZ);
#ifdef SIOCGIFHWADDR
            if (ioctl(sd, SIOCGIFHWADDR, &ifr) < 0)
                  continue;
            a = (unsigned char *) &ifr.ifr_hwaddr.sa_data;
#else
#ifdef SIOCGENADDR
            if (ioctl(sd, SIOCGENADDR, &ifr) < 0)
                  continue;
            a = (unsigned char *) ifr.ifr_enaddr;
#else
#ifdef HAVE_NET_IF_DL_H
            sdlp = (struct sockaddr_dl *) &ifrp->ifr_addr;
            if ((sdlp->sdl_family != AF_LINK) || (sdlp->sdl_alen != 6))
                  continue;
            a = (unsigned char *) &sdlp->sdl_data[sdlp->sdl_nlen];
#else
            /*
             * XXX we don't have a way of getting the hardware
             * address
             */
            close(sd);
            return 0;
#endif /* HAVE_NET_IF_DL_H */
#endif /* SIOCGENADDR */
#endif /* SIOCGIFHWADDR */
            if (!a[0] && !a[1] && !a[2] && !a[3] && !a[4] && !a[5])
                  continue;
            if (node_id) {
                  memcpy(node_id, a, 6);
                  close(sd);
                  return 1;
            }
      }
      close(sd);
#endif
      return 0;
}

/* Assume that the gettimeofday() has microsecond granularity */
#define MAX_ADJUSTMENT 10

static int get_clock(uint32_t *clock_high, uint32_t *clock_low,
                 uint16_t *ret_clock_seq, int *num)
{
      THREAD_LOCAL int        adjustment = 0;
      THREAD_LOCAL struct timeval   last = {0, 0};
      THREAD_LOCAL int        state_fd = -2;
      THREAD_LOCAL FILE       *state_f;
      THREAD_LOCAL uint16_t         clock_seq;
      struct timeval                tv;
      struct flock                  fl;
      unsigned long long            clock_reg;
      mode_t                        save_umask;

      if (state_fd == -2) {
            save_umask = umask(0);
            state_fd = open("/var/lib/libuuid/clock.txt",
                        O_RDWR|O_CREAT, 0660);
            (void) umask(save_umask);
            state_f = fdopen(state_fd, "r+");
            if (!state_f) {
                  close(state_fd);
                  state_fd = -1;
            }
      }
      fl.l_type = F_WRLCK;
      fl.l_whence = SEEK_SET;
      fl.l_start = 0;
      fl.l_len = 0;
      fl.l_pid = 0;
      if (state_fd >= 0) {
            rewind(state_f);
            while (fcntl(state_fd, F_SETLKW, &fl) < 0) {
                  if ((errno == EAGAIN) || (errno == EINTR))
                        continue;
                  fclose(state_f);
                  close(state_fd);
                  state_fd = -1;
                  break;
            }
      }
      if (state_fd >= 0) {
            unsigned int cl;
            unsigned long tv1, tv2;
            int a;

            if (fscanf(state_f, "clock: %04x tv: %lu %lu adj: %d\n",
                     &cl, &tv1, &tv2, &a) == 4) {
                  clock_seq = cl & 0x3FFF;
                  last.tv_sec = tv1;
                  last.tv_usec = tv2;
                  adjustment = a;
            }
      }

      if ((last.tv_sec == 0) && (last.tv_usec == 0)) {
            get_random_bytes(&clock_seq, sizeof(clock_seq));
            clock_seq &= 0x3FFF;
            gettimeofday(&last, 0);
            last.tv_sec--;
      }

try_again:
      gettimeofday(&tv, 0);
      if ((tv.tv_sec < last.tv_sec) ||
          ((tv.tv_sec == last.tv_sec) &&
           (tv.tv_usec < last.tv_usec))) {
            clock_seq = (clock_seq+1) & 0x3FFF;
            adjustment = 0;
            last = tv;
      } else if ((tv.tv_sec == last.tv_sec) &&
          (tv.tv_usec == last.tv_usec)) {
            if (adjustment >= MAX_ADJUSTMENT)
                  goto try_again;
            adjustment++;
      } else {
            adjustment = 0;
            last = tv;
      }
            
      clock_reg = tv.tv_usec*10 + adjustment;
      clock_reg += ((unsigned long long) tv.tv_sec)*10000000;
      clock_reg += (((unsigned long long) 0x01B21DD2) << 32) + 0x13814000;

      if (num && (*num > 1)) {
            adjustment += *num - 1;
            last.tv_usec += adjustment / 10;
            adjustment = adjustment % 10;
            last.tv_sec += last.tv_usec / 1000000;
            last.tv_usec = last.tv_usec % 1000000;
      }

      if (state_fd > 0) {
            rewind(state_f);
            ftruncate(state_fd, 0);
            fprintf(state_f, "clock: %04x tv: %lu %lu adj: %d\n",
                  clock_seq, last.tv_sec, last.tv_usec, adjustment);
            fflush(state_f);
            rewind(state_f);
            fl.l_type = F_UNLCK;
            fcntl(state_fd, F_SETLK, &fl);
      }

      *clock_high = clock_reg >> 32;
      *clock_low = clock_reg;
      *ret_clock_seq = clock_seq;
      return 0;
}

static ssize_t read_all(int fd, char *buf, size_t count)
{
      ssize_t ret;
      ssize_t c = 0;

      memset(buf, 0, count);
      while (count > 0) {
            ret = read(fd, buf, count);
            if (ret < 0) {
                  if ((errno == EAGAIN) || (errno == EINTR))
                        continue;
                  return -1;
            }
            count -= ret;
            buf += ret;
            c += ret;
      }
      return c;
}


/*
 * Try using the uuidd daemon to generate the UUID
 *
 * Returns 0 on success, non-zero on failure.
 */
static int get_uuid_via_daemon(int op, uuid_t out, int *num)
{
#if defined(USE_UUIDD) && defined(HAVE_SYS_UN_H)
      char op_buf[64];
      int op_len;
      int s;
      ssize_t ret;
      int32_t reply_len = 0, expected = 16;
      struct sockaddr_un srv_addr;
      pid_t pid;
      static const char *uuidd_path = UUIDD_PATH;
      static int access_ret = -2;
      static int start_attempts = 0;

      if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
            return -1;

      srv_addr.sun_family = AF_UNIX;
      strcpy(srv_addr.sun_path, UUIDD_SOCKET_PATH);

      if (connect(s, (const struct sockaddr *) &srv_addr,
                sizeof(struct sockaddr_un)) < 0) {
            if (access_ret == -2)
                  access_ret = access(uuidd_path, X_OK);
            if (access_ret == 0 && start_attempts++ < 5) {
                  if ((pid = fork()) == 0) {
                        execl(uuidd_path, "uuidd", "-qT", "300", 
                              (char *) NULL);
                        exit(1);
                  }
                  (void) waitpid(pid, 0, 0);
                  if (connect(s, (const struct sockaddr *) &srv_addr,
                            sizeof(struct sockaddr_un)) < 0)
                        goto fail;
            } else
                  goto fail;
      }
      op_buf[0] = op;
      op_len = 1;
      if (op == UUIDD_OP_BULK_TIME_UUID) {
            memcpy(op_buf+1, num, sizeof(*num));
            op_len += sizeof(*num);
            expected += sizeof(*num);
      }

      ret = write(s, op_buf, op_len);
      if (ret < 1)
            goto fail;

      ret = read_all(s, (char *) &reply_len, sizeof(reply_len));
      if (ret < 0)
            goto fail;

      if (reply_len != expected)
            goto fail;

      ret = read_all(s, op_buf, reply_len);

      if (op == UUIDD_OP_BULK_TIME_UUID)
            memcpy(op_buf+16, num, sizeof(int));

      memcpy(out, op_buf, 16);

      close(s);
      return ((ret == expected) ? 0 : -1);

fail:
      close(s);
#endif
      return -1;
}

void uuid__generate_time(uuid_t out, int *num)
{
      static unsigned char node_id[6];
      static int has_init = 0;
      struct uuid uu;
      uint32_t    clock_mid;

      if (!has_init) {
            if (get_node_id(node_id) <= 0) {
                  get_random_bytes(node_id, 6);
                  /*
                   * Set multicast bit, to prevent conflicts
                   * with IEEE 802 addresses obtained from
                   * network cards
                   */
                  node_id[0] |= 0x01;
            }
            has_init = 1;
      }
      get_clock(&clock_mid, &uu.time_low, &uu.clock_seq, num);
      uu.clock_seq |= 0x8000;
      uu.time_mid = (uint16_t) clock_mid;
      uu.time_hi_and_version = ((clock_mid >> 16) & 0x0FFF) | 0x1000;
      memcpy(uu.node, node_id, 6);
      uuid_pack(&uu, out);
}

void uuid_generate_time(uuid_t out)
{
#ifdef TLS
      THREAD_LOCAL int        num = 0;
      THREAD_LOCAL struct uuid      uu;
      THREAD_LOCAL time_t           last_time = 0;
      time_t                        now;

      if (num > 0) {
            now = time(0);
            if (now > last_time+1)
                  num = 0;
      }
      if (num <= 0) {
            num = 1000;
            if (get_uuid_via_daemon(UUIDD_OP_BULK_TIME_UUID,
                              out, &num) == 0) {
                  last_time = time(0);
                  uuid_unpack(out, &uu);
                  num--;
                  return;
            }
            num = 0;
      }
      if (num > 0) {
            uu.time_low++;
            if (uu.time_low == 0) {
                  uu.time_mid++;
                  if (uu.time_mid == 0)
                        uu.time_hi_and_version++;
            }
            num--;
            uuid_pack(&uu, out);
            return;
      }
#else
      if (get_uuid_via_daemon(UUIDD_OP_TIME_UUID, out, 0) == 0)
            return;
#endif

      uuid__generate_time(out, 0);
}


void uuid__generate_random(uuid_t out, int *num)
{
      uuid_t      buf;
      struct uuid uu;
      int i, n;

      if (!num || !*num)
            n = 1;
      else
            n = *num;

      for (i = 0; i < n; i++) {
            get_random_bytes(buf, sizeof(buf));
            uuid_unpack(buf, &uu);

            uu.clock_seq = (uu.clock_seq & 0x3FFF) | 0x8000;
            uu.time_hi_and_version = (uu.time_hi_and_version & 0x0FFF)
                  | 0x4000;
            uuid_pack(&uu, out);
            out += sizeof(uuid_t);
      }
}

void uuid_generate_random(uuid_t out)
{
      int   num = 1;
      /* No real reason to use the daemon for random uuid's -- yet */

      uuid__generate_random(out, &num);
}


/*
 * This is the generic front-end to uuid_generate_random and
 * uuid_generate_time.  It uses uuid_generate_random only if
 * /dev/urandom is available, since otherwise we won't have
 * high-quality randomness.
 */
void uuid_generate(uuid_t out)
{
      if (get_random_fd() >= 0)
            uuid_generate_random(out);
      else
            uuid_generate_time(out);
}

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