xref: /illumos-gate/usr/src/lib/libuuid/common/uuid.c (revision 2bcedfbf993c2cb7f5e7588f579acc5a80a1080f)

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 * Copyright 2012 Milan Jurik. All rights reserved.
 * Copyright 2014 Joyent, Inc. All rights reserved.
 * Copyright 2014 Andrew Stormont.
 */

/*
 * The copyright in this file is taken from the original Leach & Salz
 * UUID specification, from which this implementation is derived.
 */

/*
 * Copyright (c) 1990- 1993, 1996 Open Software Foundation, Inc.
 * Copyright (c) 1989 by Hewlett-Packard Company, Palo Alto, Ca. &
 * Digital Equipment Corporation, Maynard, Mass.  Copyright (c) 1998
 * Microsoft.  To anyone who acknowledges that this file is provided
 * "AS IS" without any express or implied warranty: permission to use,
 * copy, modify, and distribute this file for any purpose is hereby
 * granted without fee, provided that the above copyright notices and
 * this notice appears in all source code copies, and that none of the
 * names of Open Software Foundation, Inc., Hewlett-Packard Company,
 * or Digital Equipment Corporation be used in advertising or
 * publicity pertaining to distribution of the software without
 * specific, written prior permission.  Neither Open Software
 * Foundation, Inc., Hewlett-Packard Company, Microsoft, nor Digital
 * Equipment Corporation makes any representations about the
 * suitability of this software for any purpose.
 */

/*
 * This module is the workhorse for generating abstract
 * UUIDs.  It delegates system-specific tasks (such
 * as obtaining the node identifier or system time)
 * to the sysdep module.
 */

#include <ctype.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <fcntl.h>
#include <unistd.h>
#include <synch.h>
#include <sys/mman.h>
#include "uuid_misc.h"

shared_buffer_t		*data;

static	uuid_node_t	node_id_cache;
static	int		node_init;
static	int		file_type;
static	int		fd;

/*
 * The urandmtx mutex prevents multiple opens of /dev/urandom and protects the
 * cache.
 */
#define	RCACHE_SIZE	65535
static	mutex_t		urandmtx;
static	int		fd_urand = -1;
static	char		rcache[RCACHE_SIZE];
static	char		*rcachep = rcache;

/*
 * misc routines
 */
uint16_t		get_random(void);
void			get_current_time(uuid_time_t *);

void			struct_to_string(uuid_t, struct uuid *);
void			string_to_struct(struct uuid *, uuid_t);
int			get_ethernet_address(uuid_node_t *);

/*
 * local functions
 */
static	int		map_state();
static	void 		format_uuid(struct uuid *, uint16_t, uuid_time_t,
    uuid_node_t);
static	void		fill_random_bytes(uchar_t *, int);
static	int		uuid_create(struct uuid *);
static	void		gen_ethernet_address(uuid_node_t *);
static	void		revalidate_data(uuid_node_t *);

/*
 * Generates a uuid based on version 1 format.
 * Returns 0 on success and -1 on failure.
 */
static int
uuid_create(struct uuid *uuid)
{
	uuid_time_t	timestamp;
	uuid_node_t	system_node;
	int		ret, non_unique = 0;

	/*
	 * Get the system MAC address and/or cache it
	 */
	if (node_init) {
		bcopy(&node_id_cache, &system_node, sizeof (uuid_node_t));
	} else {
		gen_ethernet_address(&system_node);
		bcopy(&system_node, &node_id_cache, sizeof (uuid_node_t));
		node_init = 1;
	}

	/*
	 * Access the state file, mmap it and initialize the shared lock.
	 * file_type tells us whether we had access to the state file or
	 * created a temporary one.
	 */
	if (map_state() == -1)
		return (-1);

	/*
	 * Acquire the lock
	 */
	for (;;) {
		if ((ret = mutex_lock(&data->lock)) == 0)
			break;
		else
			switch (ret) {
				case EOWNERDEAD:
					revalidate_data(&system_node);
					(void) mutex_consistent(&data->lock);
					(void) mutex_unlock(&data->lock);
					break;
				case ENOTRECOVERABLE:
					return (ret);
			}
	}

	/* State file is either new or is temporary, get a random clock seq */
	if (data->state.clock == 0) {
		data->state.clock = get_random();
		non_unique++;
	}

	if (memcmp(&system_node, &data->state.node, sizeof (uuid_node_t)) != 0)
		data->state.clock++;

	get_current_time(&timestamp);

	/*
	 * If timestamp is not set or is not in the past, bump
	 * data->state.clock
	 */
	if ((data->state.ts == 0) || (data->state.ts >= timestamp)) {
		data->state.clock++;
		data->state.ts = timestamp;
	}

	if (non_unique)
		system_node.nodeID[0] |= 0x80;

	/* Stuff fields into the UUID struct */
	format_uuid(uuid, data->state.clock, timestamp, system_node);

	(void) mutex_unlock(&data->lock);

	return (0);
}

/*
 * Fills system_node with Ethernet address if available,
 * else fills random numbers
 */
static void
gen_ethernet_address(uuid_node_t *system_node)
{
	uchar_t		node[6];

	if (get_ethernet_address(system_node) != 0) {
		fill_random_bytes(node, 6);
		(void) memcpy(system_node->nodeID, node, 6);
		/*
		 * use 8:0:20 with the multicast bit set
		 * to avoid namespace collisions.
		 */
		system_node->nodeID[0] = 0x88;
		system_node->nodeID[1] = 0x00;
		system_node->nodeID[2] = 0x20;
	}
}

/*
 * Formats a UUID, given the clock_seq timestamp, and node address.
 * Fills in passed-in pointer with the resulting uuid.
 */
static void
format_uuid(struct uuid *uuid, uint16_t clock_seq,
    uuid_time_t timestamp, uuid_node_t node)
{

	/*
	 * First set up the first 60 bits from the timestamp
	 */
	uuid->time_low = (uint32_t)(timestamp & 0xFFFFFFFF);
	uuid->time_mid = (uint16_t)((timestamp >> 32) & 0xFFFF);
	uuid->time_hi_and_version = (uint16_t)((timestamp >> 48) & 0x0FFF);

	/*
	 * This is version 1, so say so in the UUID version field (4 bits)
	 */
	uuid->time_hi_and_version |= (1 << 12);

	/*
	 * Now do the clock sequence
	 */
	uuid->clock_seq_low = clock_seq & 0xFF;

	/*
	 * We must save the most-significant 2 bits for the reserved field
	 */
	uuid->clock_seq_hi_and_reserved = (clock_seq & 0x3F00) >> 8;

	/*
	 * The variant for this format is the 2 high bits set to 10,
	 * so here it is
	 */
	uuid->clock_seq_hi_and_reserved |= 0x80;

	/*
	 * write result to passed-in pointer
	 */
	(void) memcpy(&uuid->node_addr, &node, sizeof (uuid->node_addr));
}

/*
 * Opens/creates the state file, falling back to a tmp
 */
static int
map_state()
{
	FILE	*tmp;

	/* If file's mapped, return */
	if (file_type != 0)
		return (1);

	if ((fd = open(STATE_LOCATION, O_RDWR)) < 0) {
		file_type = TEMP_FILE;

		if ((tmp = tmpfile()) == NULL)
			return (-1);
		else
			fd = fileno(tmp);
	} else {
		file_type = STATE_FILE;
	}

	(void) ftruncate(fd, (off_t)sizeof (shared_buffer_t));

	/* LINTED - alignment */
	data = (shared_buffer_t *)mmap(NULL, sizeof (shared_buffer_t),
	    PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);

	if (data == MAP_FAILED)
		return (-1);

	(void) mutex_init(&data->lock, USYNC_PROCESS|LOCK_ROBUST, 0);

	(void) close(fd);

	return (1);
}

static void
revalidate_data(uuid_node_t *node)
{
	int i;

	data->state.ts = 0;

	for (i = 0; i < sizeof (data->state.node.nodeID); i++)
		data->state.node.nodeID[i] = 0;

	data->state.clock = 0;

	gen_ethernet_address(node);
	bcopy(node, &node_id_cache, sizeof (uuid_node_t));
	node_init = 1;
}

/*
 * Prints a nicely-formatted uuid to stdout.
 */
void
uuid_print(struct uuid u)
{
	int i;

	(void) printf("%8.8x-%4.4x-%4.4x-%2.2x%2.2x-", u.time_low, u.time_mid,
	    u.time_hi_and_version, u.clock_seq_hi_and_reserved,
	    u.clock_seq_low);
	for (i = 0; i < 6; i++)
		(void) printf("%2.2x", u.node_addr[i]);
	(void) printf("\n");
}

/*
 * Only called with urandmtx held.
 * Fills/refills the cache of randomness. We know that our allocations of
 * randomness are always much less than the total size of the cache.
 * Tries to use /dev/urandom random number generator - if that fails for some
 * reason, it retries MAX_RETRY times then sets rcachep to NULL so we no
 * longer use the cache.
 */
static void
load_cache()
{
	int i, retries = 0;
	int nbytes = RCACHE_SIZE;
	char *buf = rcache;

	while (nbytes > 0) {
		i = read(fd_urand, buf, nbytes);
		if ((i < 0) && (errno == EINTR)) {
			continue;
		}
		if (i <= 0) {
			if (retries++ == MAX_RETRY)
				break;
			continue;
		}
		nbytes -= i;
		buf += i;
		retries = 0;
	}
	if (nbytes == 0)
		rcachep = rcache;
	else
		rcachep = NULL;
}

static void
close_pre()
{
	(void) mutex_lock(&urandmtx);
}

static void
close_parent()
{
	(void) mutex_unlock(&urandmtx);
}

static void
close_child()
{
	if (fd_urand != -1) {
		(void) close(fd_urand);
		fd_urand = -1;
	}
	(void) mutex_unlock(&urandmtx);
}

#pragma init(cache_init)
static void
cache_init(void)
{
	(void) pthread_atfork(close_pre, close_parent, close_child);
}

/*
 * Fills buf with random numbers - nbytes is the number of bytes
 * to fill-in. Tries to use cached data from the /dev/urandom random number
 * generator - if that fails for some reason, it uses srand48(3C)
 */
static void
fill_random_bytes(uchar_t *buf, int nbytes)
{
	int i;

	if (fd_urand == -1) {
		(void) mutex_lock(&urandmtx);
		/* check again now that we have the mutex */
		if (fd_urand == -1) {
			if ((fd_urand = open(URANDOM_PATH,
			    O_RDONLY | O_CLOEXEC)) >= 0)
				load_cache();
		}
		(void) mutex_unlock(&urandmtx);
	}
	if (fd_urand >= 0 && rcachep != NULL) {
		int cnt;

		(void) mutex_lock(&urandmtx);
		if (rcachep != NULL &&
		    (rcachep + nbytes) >= (rcache + RCACHE_SIZE))
			load_cache();

		if (rcachep != NULL) {
			for (cnt = 0; cnt < nbytes; cnt++)
				*buf++ = *rcachep++;
			(void) mutex_unlock(&urandmtx);
			return;
		}
		(void) mutex_unlock(&urandmtx);
	}
	for (i = 0; i < nbytes; i++) {
		*buf++ = get_random() & 0xFF;
	}
}

/*
 * Unpacks the structure members in "struct uuid" to a char string "uuid_t".
 */
void
struct_to_string(uuid_t ptr, struct uuid *uu)
{
	uint_t		tmp;
	uchar_t		*out = ptr;

	tmp = uu->time_low;
	out[3] = (uchar_t)tmp;
	tmp >>= 8;
	out[2] = (uchar_t)tmp;
	tmp >>= 8;
	out[1] = (uchar_t)tmp;
	tmp >>= 8;
	out[0] = (uchar_t)tmp;

	tmp = uu->time_mid;
	out[5] = (uchar_t)tmp;
	tmp >>= 8;
	out[4] = (uchar_t)tmp;

	tmp = uu->time_hi_and_version;
	out[7] = (uchar_t)tmp;
	tmp >>= 8;
	out[6] = (uchar_t)tmp;

	tmp = uu->clock_seq_hi_and_reserved;
	out[8] = (uchar_t)tmp;
	tmp = uu->clock_seq_low;
	out[9] = (uchar_t)tmp;

	(void) memcpy(out+10, uu->node_addr, 6);

}

/*
 * Packs the values in the "uuid_t" string into "struct uuid".
 */
void
string_to_struct(struct uuid *uuid, uuid_t in)
{
	uchar_t	*ptr;
	uint_t	tmp;

	ptr = in;

	tmp = *ptr++;
	tmp = (tmp << 8) | *ptr++;
	tmp = (tmp << 8) | *ptr++;
	tmp = (tmp << 8) | *ptr++;
	uuid->time_low = tmp;

	tmp = *ptr++;
	tmp = (tmp << 8) | *ptr++;
	uuid->time_mid = tmp;

	tmp = *ptr++;
	tmp = (tmp << 8) | *ptr++;
	uuid->time_hi_and_version = tmp;

	tmp = *ptr++;
	uuid->clock_seq_hi_and_reserved = tmp;

	tmp = *ptr++;
	uuid->clock_seq_low = tmp;

	(void) memcpy(uuid->node_addr, ptr, 6);

}

/*
 * Generates UUID based on DCE Version 4
 */
void
uuid_generate_random(uuid_t uu)
{
	struct uuid	uuid;

	if (uu == NULL)
		return;

	(void) memset(uu, 0, sizeof (uuid_t));
	(void) memset(&uuid, 0, sizeof (struct uuid));

	fill_random_bytes(uu, sizeof (uuid_t));
	string_to_struct(&uuid, uu);
	/*
	 * This is version 4, so say so in the UUID version field (4 bits)
	 */
	uuid.time_hi_and_version |= (1 << 14);
	/*
	 * we don't want the bit 1 to be set also which is for version 1
	 */
	uuid.time_hi_and_version &= VER1_MASK;

	/*
	 * The variant for this format is the 2 high bits set to 10,
	 * so here it is
	 */
	uuid.clock_seq_hi_and_reserved |= 0x80;

	/*
	 * Set MSB of Ethernet address to 1 to indicate that it was generated
	 * randomly
	 */
	uuid.node_addr[0] |= 0x80;
	struct_to_string(uu, &uuid);
}

/*
 * Generates UUID based on DCE Version 1.
 */
void
uuid_generate_time(uuid_t uu)
{
	struct 	uuid uuid;

	if (uu == NULL)
		return;

	if (uuid_create(&uuid) < 0) {
		uuid_generate_random(uu);
		return;
	}

	struct_to_string(uu, &uuid);
}

/*
 * Creates a new UUID. The uuid will be generated based on high-quality
 * randomness from /dev/urandom, if available by calling uuid_generate_random.
 * If it failed to generate UUID then uuid_generate will call
 * uuid_generate_time.
 */
void
uuid_generate(uuid_t uu)
{
	if (uu == NULL) {
		return;
	}
	if (fd_urand == -1) {
		(void) mutex_lock(&urandmtx);
		/* check again now that we have the mutex */
		if (fd_urand == -1) {
			if ((fd_urand = open(URANDOM_PATH, O_RDONLY)) >= 0)
				load_cache();
		}
		(void) mutex_unlock(&urandmtx);
	}
	if (fd_urand >= 0) {
		uuid_generate_random(uu);
	} else {
		(void) uuid_generate_time(uu);
	}
}

/*
 * Copies the UUID variable src to dst.
 */
void
uuid_copy(uuid_t dst, uuid_t src)
{
	(void) memcpy(dst, src, UUID_LEN);
}

/*
 * Sets the value of the supplied uuid variable uu, to the NULL value.
 */
void
uuid_clear(uuid_t uu)
{
	(void) memset(uu, 0, UUID_LEN);
}

/*
 * This function converts the supplied UUID uu from the internal
 * binary format into a 36-byte string (plus trailing null char)
 * and stores this value in the character string pointed to by out.
 */
static void
uuid_unparse_common(uuid_t uu, char *out, boolean_t upper)
{
	struct uuid 	uuid;
	uint16_t	clock_seq;
	char		etheraddr[13];
	int		index = 0, i;

	/* basic sanity checking */
	if (uu == NULL) {
		return;
	}

	string_to_struct(&uuid, uu);
	clock_seq = uuid.clock_seq_hi_and_reserved;
	clock_seq = (clock_seq  << 8) | uuid.clock_seq_low;
	for (i = 0; i < 6; i++) {
		(void) sprintf(&etheraddr[index++], upper ? "%.2X" : "%.2x",
		    uuid.node_addr[i]);
		index++;
	}
	etheraddr[index] = '\0';

	(void) snprintf(out, 25,
	    upper ? "%08X-%04X-%04X-%04X-" : "%08x-%04x-%04x-%04x-",
	    uuid.time_low, uuid.time_mid, uuid.time_hi_and_version, clock_seq);
	(void) strlcat(out, etheraddr, UUID_PRINTABLE_STRING_LENGTH);
}

void
uuid_unparse_upper(uuid_t uu, char *out)
{
	uuid_unparse_common(uu, out, B_TRUE);
}

void
uuid_unparse_lower(uuid_t uu, char *out)
{
	uuid_unparse_common(uu, out, B_FALSE);
}

void
uuid_unparse(uuid_t uu, char *out)
{
	/*
	 * Historically uuid_unparse on Solaris returns lower case,
	 * for compatibility we preserve this behaviour.
	 */
	uuid_unparse_common(uu, out, B_FALSE);
}

/*
 * The uuid_is_null function compares the value of the supplied
 * UUID variable uu to the NULL value. If the value is equal
 * to the NULL UUID, 1 is returned, otherwise 0 is returned.
 */
int
uuid_is_null(uuid_t uu)
{
	int		i;
	uuid_t		null_uu;

	(void) memset(null_uu, 0, sizeof (uuid_t));
	i = memcmp(uu, null_uu, sizeof (uuid_t));
	if (i == 0) {
		/* uu is NULL uuid */
		return (1);
	} else {
		return (0);
	}
}

/*
 * uuid_parse converts the UUID string given by 'in' into the
 * internal uuid_t format. The input UUID is a string of the form
 * cefa7a9c-1dd2-11b2-8350-880020adbeef in printf(3C) format.
 * Upon successfully parsing the input string, UUID is stored
 * in the location pointed to by uu
 */
int
uuid_parse(char *in, uuid_t uu)
{

	char		*ptr, buf[3];
	int		i;
	struct uuid	uuid;
	uint16_t	clock_seq;

	/* do some sanity checking */
	if ((strlen(in) != 36) || (uu == NULL) || (in[36] != '\0')) {
		return (-1);
	}

	ptr = in;
	for (i = 0; i < 36; i++, ptr++) {
		if ((i == 8) || (i == 13) || (i == 18) || (i == 23)) {
			if (*ptr != '-') {
				return (-1);
			}
		} else {
			if (!isxdigit(*ptr)) {
				return (-1);
			}
		}
	}

	uuid.time_low = strtoul(in, NULL, 16);
	uuid.time_mid = strtoul(in+9, NULL, 16);
	uuid.time_hi_and_version = strtoul(in+14, NULL, 16);
	clock_seq = strtoul(in+19, NULL, 16);
	uuid.clock_seq_hi_and_reserved = (clock_seq & 0xFF00) >> 8;
	uuid.clock_seq_low = (clock_seq & 0xFF);

	ptr = in+24;
	buf[2] = '\0';
	for (i = 0; i < 6; i++) {
		buf[0] = *ptr++;
		buf[1] = *ptr++;
		uuid.node_addr[i] = strtoul(buf, NULL, 16);
	}
	struct_to_string(uu, &uuid);
	return (0);
}

/*
 * uuid_time extracts the time at which the supplied UUID uu
 * was created. This function can only extract the creation
 * time for UUIDs created with the uuid_generate_time function.
 * The time at which the UUID was created, in seconds and
 * microseconds since the epoch is stored in the location
 * pointed to by ret_tv.
 */
time_t
uuid_time(uuid_t uu, struct timeval *ret_tv)
{
	struct uuid	uuid;
	uint_t		high;
	struct timeval	tv;
	u_longlong_t	clock_reg;
	uint_t		tmp;
	uint8_t		clk;

	string_to_struct(&uuid, uu);
	tmp = (uuid.time_hi_and_version & 0xF000) >> 12;
	clk = uuid.clock_seq_hi_and_reserved;

	/* check if uu is NULL, Version = 1 of DCE and Variant = 0b10x */
	if ((uu == NULL) || ((tmp & 0x01) != 0x01) || ((clk & 0x80) != 0x80)) {
		return (-1);
	}
	high = uuid.time_mid | ((uuid.time_hi_and_version & 0xFFF) << 16);
	clock_reg = uuid.time_low | ((u_longlong_t)high << 32);

	clock_reg -= (((u_longlong_t)0x01B21DD2) << 32) + 0x13814000;
	tv.tv_sec = clock_reg / 10000000;
	tv.tv_usec = (clock_reg % 10000000) / 10;

	if (ret_tv) {
		*ret_tv = tv;
	}

	return (tv.tv_sec);
}