/*
 * 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 <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#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>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/sockio.h>
#include <net/if.h>
#include <netinet/in.h>
#include <net/if_dl.h>
#include <sys/resource.h>

#include "uuidP.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 = 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;
#ifdef DO_JRAND_MIX
        {
                unsigned short tmp_seed[3];

                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;
}

#ifndef _KERNEL_MODE
/*
 * Get the ethernet hardware address, if we can find it...
 *
 * XXX for a windows version, probably should use GetAdaptersInfo:
 * http://www.codeguru.com/cpp/i-n/network/networkinformation/article.php/c5451
 * commenting out get_node_id just to get gen_uuid to compile under windows
 * is not the right way to go!
 */
static int get_node_id(unsigned char *node_id)
{
        int             sd;
        struct ifreq    ifr, *ifrp;
        struct ifconf   ifc;
        char buf[1024];
        int             n, i;
        unsigned char   *a;
        struct sockaddr_dl *sdlp;

/*
 * 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)
 */
#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)

        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
                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];
#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);
        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;
        uint64_t                        clock_reg;
        mode_t                          save_umask;
        int                             len;

        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);
                if (state_fd >= 0) {
                        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);
                        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 += ((uint64_t) tv.tv_sec)*10000000;
        clock_reg += (((uint64_t) 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);
                len = fprintf(state_f,
                              "clock: %04x tv: %016lu %08lu adj: %08d\n",
                              clock_seq, last.tv_sec, (long)last.tv_usec,
                              adjustment);
                fflush(state_f);
                if (ftruncate(state_fd, len) < 0) {
                        fprintf(state_f, "                   \n");
                        fflush(state_f);
                }
                rewind(state_f);
                fl.l_type = F_UNLCK;
                if (fcntl(state_fd, F_SETLK, &fl) < 0) {
                        fclose(state_f);
                        state_fd = -1;
                }
        }

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

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 (-1 == 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 (-1 == 0)
                return;
#endif

        uuid__generate_time(out, 0);
}
#endif // !_KERNEL_MODE

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);
}

/*
 * Check whether good random source (/dev/random or /dev/urandom)
 * is available.
 */
static int have_random_source(void)
{
        struct stat s;

        return (!stat("/dev/random", &s) || !stat("/dev/urandom", &s));
}


#ifndef _KERNEL_MODE
/*
 * 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 (have_random_source())
                uuid_generate_random(out);
        else
                uuid_generate_time(out);
}
#else
void uuid_generate(uuid_t out)
{
        uuid_generate_random(out);
}
#endif