/*

 * iSCSI InitiatorName creation utility

 * Copyright (C) 2001 Cisco Systems, Inc.

 * maintained by linux-iscsi-devel@lists.sourceforge.net

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published

 * by the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

 * General Public License for more details.

 *

 * See the file COPYING included with this distribution for more details.

 *

 * $Id: iscsi-iname.c,v 1.1.2.3 2005/03/15 06:33:44 wysochanski Exp $

 *

 * iscsi-iname.c - Compute an iSCSI InitiatorName for this host.

 * Note that to ensure uniqueness, the system time is

 * a factor.  This name must be cached and only regenerated

 * if there is no cached value.

 */

#include <stdint.h>

#include <fcntl.h>

#include <unistd.h>

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <sys/utsname.h>

#include <sys/time.h>

#include "md5.h"

#define RANDOM_NUM_GENERATOR	"/dev/urandom"

/* iSCSI names have a maximum length of 223 characters, we reserve 13 to append

 * a seperator and 12 characters (6 random bytes in hex representation) */

#define PREFIX_MAX_LEN 210

int

main(int argc, char *argv[])

{

	struct timeval time;

	struct utsname system_info;

	long hostid;

	struct MD5Context context;

	unsigned char digest[16];

	unsigned char *bytes = digest;

	unsigned char entropy[16];

	int e;

	int fd;

	char *prefix;

	/* initialize */

	memset(digest, 0, sizeof (digest));

	memset(&context, 0, sizeof (context));

	MD5Init(&context);

	/* take a prefix if given, otherwise use a default. */

	if (argc > 1 && argv[1]) {

		prefix = argv[1];

		if (( strcmp(prefix, "-h") == 0 ) ||

		    ( strcmp(prefix, "--help") == 0 )) {

			printf("\nGenerates a unique iSCSI node name "

			       "on every invocation.\n");

			exit(0);

		} else if ( strcmp(prefix, "-p") == 0 ) {

			prefix = argv[2];

			if (strnlen(prefix, PREFIX_MAX_LEN + 1) > PREFIX_MAX_LEN) {

				printf("Error: Prefix cannot exceed %d "

				       "characters.\n", PREFIX_MAX_LEN);

				exit(1);

			}

		} else {

			printf("\nUsage: iscsi-iname [-h | --help | "

			       "-p <prefix>]\n");

			exit(0);

		}

	} else {

		prefix = "iqn.1994-05.com.redhat";

	}

	/* try to feed some entropy from the pool to MD5 in order to get

	 * uniqueness properties

	 */

	if ((fd = open(RANDOM_NUM_GENERATOR, O_RDONLY))) {

		e = read(fd, &entropy, 16);

		if (e >= 1)

			MD5Update(&context, (md5byte *)entropy, e);

		close(fd);

	}

	/* time the name is created is a factor in order to get

	 * uniqueness properties

	 */

	if (gettimeofday(&time, NULL) < 0) {

		perror("error: gettimeofday failed");

		return 1;

	}

	MD5Update(&context, (md5byte *) & time.tv_sec, sizeof (time.tv_sec));

	MD5Update(&context, (md5byte *) & time.tv_usec, sizeof (time.tv_usec));

	/* hostid */

	hostid = gethostid();

	MD5Update(&context, (md5byte *) & hostid, sizeof (hostid));

	/* get the hostname and system name */

	if (uname(&system_info) < 0) {

		perror("error: uname failed");

		return 1;

	}

	MD5Update(&context, (md5byte *) system_info.sysname,

		  sizeof (system_info.sysname));

	MD5Update(&context, (md5byte *) system_info.nodename,

		  sizeof (system_info.nodename));

	MD5Update(&context, (md5byte *) system_info.release,

		  sizeof (system_info.release));

	MD5Update(&context, (md5byte *) system_info.version,

		  sizeof (system_info.version));

	MD5Update(&context, (md5byte *) system_info.machine,

		  sizeof (system_info.machine));

	/* compute the md5 hash of all the bits we just collected */

	MD5Final(digest, &context);

	/* vary which md5 bytes we pick (though we probably don't need to do

	 * this, since hopefully MD5 produces results such that each byte is as

	 * good as any other).

	 */

	if ((fd = open(RANDOM_NUM_GENERATOR, O_RDONLY))) {

		if (read(fd, entropy, 1) == 1)

			bytes = &digest[(entropy[0] % (sizeof(digest) - 6))];

		close(fd);

	}

	/* print the prefix followed by 6 bytes of the MD5 hash */

	printf("%s:%x%x%x%x%x%x\n", prefix,

		bytes[0], bytes[1], bytes[2], bytes[3], bytes[4], bytes[5]);

	return 0;

}