/* vi: set sw=4 ts=4: */
/*
 * 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%
 */

#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <sys/time.h>
#ifdef HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>
#endif
#include <sys/socket.h>
#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

#include "uuidP.h"

#ifdef HAVE_SRANDOM
#define srand(x)        srandom(x)
#define rand()          random()
#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);
                srand((getpid() << 16) ^ getuid() ^ tv.tv_sec ^ tv.tv_usec);
        }
        /* 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;

        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;
}

/*
 * 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_IFNAMSIZ(ifr.ifr_name, ifrp->ifr_name);
#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)
{
        static int                      adjustment = 0;
        static struct timeval           last = {0, 0};
        static uint16_t                 clock_seq;
        struct timeval                  tv;
        unsigned long long              clock_reg;

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

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

void uuid_generate_time(uuid_t out)
{
        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);
        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_random(uuid_t out)
{
        uuid_t  buf;
        struct uuid uu;

        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);
}

/*
 * 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);
}