/*
 * 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.
 *
 * $FreeBSD$
 */

#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/uuid.h>

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

	/* XXX: lock ifnet. */
	TAILQ_FOREACH(ifp, &ifnet, if_link) {
		/* Walk the address list */
		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);
				/* XXX: unlock ifnet. */
				return;
			}
		}
	}
	/* XXX: unlock ifnet. */

	for (i = 0; i < (UUID_NODE_LEN>>1); i++)
		node[i] = (uint16_t)arc4random();
	*((uint8_t*)node) |= 0x80;
}

/*
 * 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, Januari 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));
}

#ifndef _SYS_SYSPROTO_H_
struct uuidgen_args {
	struct uuid *store;
	int	count;
};
#endif

int
uuidgen(struct thread *td, struct uuidgen_args *uap)
{
	struct uuid_private uuid;
	uint64_t time;
	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 needs to be tunable.
	 */
	if (uap->count < 1 || uap->count > 2048)
		return (EINVAL);

	/* XXX: pre-validate accessibility to the whole of the UUID store? */

	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 + uap->count - 1) & ((1LL << 60) - 1LL);

	mtx_unlock(&uuid_mutex);

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

	/* XXX: this should copyout larger chunks at a time. */
	do {
		/* Set time and version (=1) and deal with byte order. */
		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);
		error = copyout(&uuid, uap->store, sizeof(uuid));
		uap->store++;
		uap->count--;
		time++;
	} while (uap->count > 0 && !error);

	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));
}