kern_uuid.c

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/*-
 * Copyright (c) 2002 Marcel Moolenaar
 * All rights reserved.
 *
 * 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, this list of conditions and the following disclaimer.
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 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 ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$BSDSUniX$");

#include <sys/param.h>
#include <sys/endian.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/sbuf.h>
#include <sys/socket.h>
#include <sys/sysproto.h>
#include <sys/systm.h>
#include <sys/jail.h>
#include <sys/uuid.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/vnet.h>

/*
 * See also:
 *      http://www.opengroup.org/dce/info/draft-leach-uuids-guids-01.txt
 *      http://www.opengroup.org/onlinepubs/009629399/apdxa.htm
 *
 * Note that the generator state is itself an UUID, but the time and clock
 * sequence fields are written in the native byte order.
 */

CTASSERT(sizeof(struct uuid) == 16);

/* We use an alternative, more convenient representation in the generator. */
struct uuid_private {
        union {
                uint64_t        ll;             /* internal. */
                struct {
                        uint32_t        low;
                        uint16_t        mid;
                        uint16_t        hi;
                } x;
        } time;
        uint16_t        seq;                    /* Big-endian. */
        uint16_t        node[UUID_NODE_LEN>>1];
};

CTASSERT(sizeof(struct uuid_private) == 16);

static struct uuid_private uuid_last;

static struct mtx uuid_mutex;
MTX_SYSINIT(uuid_lock, &uuid_mutex, "UUID generator mutex lock", MTX_DEF);

/*
 * Return the first MAC address we encounter or, if none was found,
 * construct a sufficiently random multicast address. We don't try
 * to return the same MAC address as previously returned. We always
 * generate a new multicast address if no MAC address exists in the
 * system.
 * It would be nice to know if 'ifnet' or any of its sub-structures
 * has been changed in any way. If not, we could simply skip the
 * scan and safely return the MAC address we returned before.
 */
static void
uuid_node(uint16_t *node)
{
        struct ifnet *ifp;
        struct ifaddr *ifa;
        struct sockaddr_dl *sdl;
        int i;

        CURVNET_SET(TD_TO_VNET(curthread));
        IFNET_RLOCK_NOSLEEP();
        TAILQ_FOREACH(ifp, &V_ifnet, if_link) {
                /* Walk the address list */
                IF_ADDR_RLOCK(ifp);
                TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
                        sdl = (struct sockaddr_dl*)ifa->ifa_addr;
                        if (sdl != NULL && sdl->sdl_family == AF_LINK &&
                            sdl->sdl_type == IFT_ETHER) {
                                /* Got a MAC address. */
                                bcopy(LLADDR(sdl), node, UUID_NODE_LEN);
                                IF_ADDR_RUNLOCK(ifp);
                                IFNET_RUNLOCK_NOSLEEP();
                                CURVNET_RESTORE();
                                return;
                        }
                }
                IF_ADDR_RUNLOCK(ifp);
        }
        IFNET_RUNLOCK_NOSLEEP();

        for (i = 0; i < (UUID_NODE_LEN>>1); i++)
                node[i] = (uint16_t)arc4random();
        *((uint8_t*)node) |= 0x01;
        CURVNET_RESTORE();
}

/*
 * Get the current time as a 60 bit count of 100-nanosecond intervals
 * since 00:00:00.00, October 15,1582. We apply a magic offset to convert
 * the Unix time since 00:00:00.00, January 1, 1970 to the date of the
 * Gregorian reform to the Christian calendar.
 */
static uint64_t
uuid_time(void)
{
        struct bintime bt;
        uint64_t time = 0x01B21DD213814000LL;

        bintime(&bt);
        time += (uint64_t)bt.sec * 10000000LL;
        time += (10000000LL * (uint32_t)(bt.frac >> 32)) >> 32;
        return (time & ((1LL << 60) - 1LL));
}

struct uuid *
kern_uuidgen(struct uuid *store, size_t count)
{
        struct uuid_private uuid;
        uint64_t time;
        size_t n;

        mtx_lock(&uuid_mutex);

        uuid_node(uuid.node);
        time = uuid_time();

        if (uuid_last.time.ll == 0LL || uuid_last.node[0] != uuid.node[0] ||
            uuid_last.node[1] != uuid.node[1] ||
            uuid_last.node[2] != uuid.node[2])
                uuid.seq = (uint16_t)arc4random() & 0x3fff;
        else if (uuid_last.time.ll >= time)
                uuid.seq = (uuid_last.seq + 1) & 0x3fff;
        else
                uuid.seq = uuid_last.seq;

        uuid_last = uuid;
        uuid_last.time.ll = (time + count - 1) & ((1LL << 60) - 1LL);

        mtx_unlock(&uuid_mutex);

        /* Set sequence and variant and deal with byte order. */
        uuid.seq = htobe16(uuid.seq | 0x8000);

        for (n = 0; n < count; n++) {
                /* Set time and version (=1). */
                uuid.time.x.low = (uint32_t)time;
                uuid.time.x.mid = (uint16_t)(time >> 32);
                uuid.time.x.hi = ((uint16_t)(time >> 48) & 0xfff) | (1 << 12);
                store[n] = *(struct uuid *)&uuid;
                time++;
        }

        return (store);
}

#ifndef _SYS_SYSPROTO_H_
struct uuidgen_args {
        struct uuid *store;
        int     count;
};
#endif
int
sys_uuidgen(struct thread *td, struct uuidgen_args *uap)
{
        struct uuid *store;
        size_t count;
        int error;

        /*
         * Limit the number of UUIDs that can be created at the same time
         * to some arbitrary number. This isn't really necessary, but I
         * like to have some sort of upper-bound that's less than 2G :-)
         * XXX probably needs to be tunable.
         */
        if (uap->count < 1 || uap->count > 2048)
                return (EINVAL);

        count = uap->count;
        store = malloc(count * sizeof(struct uuid), M_TEMP, M_WAITOK);
        kern_uuidgen(store, count);
        error = copyout(store, uap->store, count * sizeof(struct uuid));
        free(store, M_TEMP);
        return (error);
}

int
snprintf_uuid(char *buf, size_t sz, struct uuid *uuid)
{
        struct uuid_private *id;
        int cnt;

        id = (struct uuid_private *)uuid;
        cnt = snprintf(buf, sz, "%08x-%04x-%04x-%04x-%04x%04x%04x",
            id->time.x.low, id->time.x.mid, id->time.x.hi, be16toh(id->seq),
            be16toh(id->node[0]), be16toh(id->node[1]), be16toh(id->node[2]));
        return (cnt);
}

int
printf_uuid(struct uuid *uuid)
{
        char buf[38];

        snprintf_uuid(buf, sizeof(buf), uuid);
        return (printf("%s", buf));
}

int
sbuf_printf_uuid(struct sbuf *sb, struct uuid *uuid)
{
        char buf[38];

        snprintf_uuid(buf, sizeof(buf), uuid);
        return (sbuf_printf(sb, "%s", buf));
}

/*
 * Encode/Decode UUID into byte-stream.
 *   http://www.opengroup.org/dce/info/draft-leach-uuids-guids-01.txt
 *
 * 0                   1                   2                   3
 *   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |                          time_low                             |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |       time_mid                |         time_hi_and_version   |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |clk_seq_hi_res |  clk_seq_low  |         node (0-1)            |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *  |                         node (2-5)                            |
 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 */

void
le_uuid_enc(void *buf, struct uuid const *uuid)
{
        u_char *p;
        int i;

        p = buf;
        le32enc(p, uuid->time_low);
        le16enc(p + 4, uuid->time_mid);
        le16enc(p + 6, uuid->time_hi_and_version);
        p[8] = uuid->clock_seq_hi_and_reserved;
        p[9] = uuid->clock_seq_low;
        for (i = 0; i < _UUID_NODE_LEN; i++)
                p[10 + i] = uuid->node[i];
}

void
le_uuid_dec(void const *buf, struct uuid *uuid)
{
        u_char const *p;
        int i;

        p = buf;
        uuid->time_low = le32dec(p);
        uuid->time_mid = le16dec(p + 4);
        uuid->time_hi_and_version = le16dec(p + 6);
        uuid->clock_seq_hi_and_reserved = p[8];
        uuid->clock_seq_low = p[9];
        for (i = 0; i < _UUID_NODE_LEN; i++)
                uuid->node[i] = p[10 + i];
}

void
be_uuid_enc(void *buf, struct uuid const *uuid)
{
        u_char *p;
        int i;

        p = buf;
        be32enc(p, uuid->time_low);
        be16enc(p + 4, uuid->time_mid);
        be16enc(p + 6, uuid->time_hi_and_version);
        p[8] = uuid->clock_seq_hi_and_reserved;
        p[9] = uuid->clock_seq_low;
        for (i = 0; i < _UUID_NODE_LEN; i++)
                p[10 + i] = uuid->node[i];
}

void
be_uuid_dec(void const *buf, struct uuid *uuid)
{
        u_char const *p;
        int i;

        p = buf;
        uuid->time_low = be32dec(p);
        uuid->time_mid = be16dec(p + 4);
        uuid->time_hi_and_version = be16dec(p + 6);
        uuid->clock_seq_hi_and_reserved = p[8];
        uuid->clock_seq_low = p[9];
        for (i = 0; i < _UUID_NODE_LEN; i++)
                uuid->node[i] = p[10 + i];
}

int
parse_uuid(const char *str, struct uuid *uuid)
{
        u_int c[11];
        int n;

        /* An empty string represents a nil UUID. */
        if (*str == '\0') {
                bzero(uuid, sizeof(*uuid));
                return (0);
        }

        /* The UUID string representation has a fixed length. */
        if (strlen(str) != 36)
                return (EINVAL);

        /*
         * We only work with "new" UUIDs. New UUIDs have the form:
         *      01234567-89ab-cdef-0123-456789abcdef
         * The so called "old" UUIDs, which we don't support, have the form:
         *      0123456789ab.cd.ef.01.23.45.67.89.ab
         */
        if (str[8] != '-')
                return (EINVAL);

        n = sscanf(str, "%8x-%4x-%4x-%2x%2x-%2x%2x%2x%2x%2x%2x", c + 0, c + 1,
            c + 2, c + 3, c + 4, c + 5, c + 6, c + 7, c + 8, c + 9, c + 10);
        /* Make sure we have all conversions. */
        if (n != 11)
                return (EINVAL);

        /* Successful scan. Build the UUID. */
        uuid->time_low = c[0];
        uuid->time_mid = c[1];
        uuid->time_hi_and_version = c[2];
        uuid->clock_seq_hi_and_reserved = c[3];
        uuid->clock_seq_low = c[4];
        for (n = 0; n < 6; n++)
                uuid->node[n] = c[n + 5];

        /* Check semantics... */
        return (((c[3] & 0x80) != 0x00 &&               /* variant 0? */
            (c[3] & 0xc0) != 0x80 &&                    /* variant 1? */
            (c[3] & 0xe0) != 0xc0) ? EINVAL : 0);       /* variant 2? */
}