utils/iscsi-iname.c

   1 /*
   2  * iSCSI InitiatorName creation utility
   3  * Copyright (C) 2001 Cisco Systems, Inc.
   4  * maintained by linux-iscsi-devel@lists.sourceforge.net
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published
   8  * by the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14  * General Public License for more details.
  15  *
  16  * See the file COPYING included with this distribution for more details.
  17  *
  18  * $Id: iscsi-iname.c,v 1.1.2.3 2005/03/15 06:33:44 wysochanski Exp $
  19  *
  20  * iscsi-iname.c - Compute an iSCSI InitiatorName for this host.
  21  * Note that to ensure uniqueness, the system time is
  22  * a factor.  This name must be cached and only regenerated
  23  * if there is no cached value.
  24  */
  25
  26 #include <stdint.h>
  27 #include <fcntl.h>
  28 #include <unistd.h>
  29 #include <stdlib.h>
  30 #include <stdio.h>
  31 #include <string.h>
  32 #include <sys/utsname.h>
  33 #include <sys/time.h>
  34
  35 #include "md5.h"
  36
  37 #define RANDOM_NUM_GENERATOR    "/dev/urandom"
  38
  39 int
  40 main(int argc, char *argv[])
  41 {
  42         char iname[256];
  43         struct timeval time;
  44         struct utsname system_info;
  45         long hostid;
  46         struct MD5Context context;
  47         unsigned char digest[16];
  48         unsigned char *bytes = digest;
  49         unsigned char entropy[16];
  50         int e;
  51         int fd;
  52         char *prefix;
  53
  54         /* initialize */
  55         memset(iname, 0, sizeof (iname));
  56         memset(digest, 0, sizeof (digest));
  57         memset(&context, 0, sizeof (context));
  58         MD5Init(&context);
  59
  60         /* take a prefix if given, otherwise use a default. */
  61         if (argc > 1 && argv[1]) {
  62                 prefix = argv[1];
  63                 if (( strcmp(prefix, "-h") == 0 ) ||
  64                     ( strcmp(prefix, "--help") == 0 )) {
  65                         printf("\nGenerates a unique iSCSI node name "
  66                                "on every invocation.\n");
  67                         exit(0);
  68                 } else if ( strcmp(prefix, "-p") == 0 ) {
  69                         prefix = argv[2];
  70                 } else {
  71                         printf("\nUsage: iscsi-iname [-h | --help | "
  72                                "-p <prefix>]\n");
  73                         exit(0);
  74                 }
  75         } else {
  76                 prefix = "iqn.2005-03.org.open-iscsi";
  77         }
  78
  79         /* try to feed some entropy from the pool to MD5 in order to get
  80          * uniqueness properties
  81          */
  82
  83         if ((fd = open(RANDOM_NUM_GENERATOR, O_RDONLY))) {
  84                 e = read(fd, &entropy, 16);
  85                 if (e >= 1)
  86                         MD5Update(&context, (md5byte *)entropy, e);
  87                 close(fd);
  88         }
  89
  90         /* time the name is created is a factor in order to get
  91          * uniqueness properties
  92          */
  93         if (gettimeofday(&time, NULL) < 0) {
  94                 perror("error: gettimeofday failed");
  95                 return 1;
  96         }
  97         MD5Update(&context, (md5byte *) & time.tv_sec, sizeof (time.tv_sec));
  98         MD5Update(&context, (md5byte *) & time.tv_usec, sizeof (time.tv_usec));
  99
 100         /* hostid */
 101         hostid = gethostid();
 102         MD5Update(&context, (md5byte *) & hostid, sizeof (hostid));
 103
 104         /* get the hostname and system name */
 105         if (uname(&system_info) < 0) {
 106                 perror("error: uname failed");
 107                 return 1;
 108         }
 109         MD5Update(&context, (md5byte *) system_info.sysname,
 110                   sizeof (system_info.sysname));
 111         MD5Update(&context, (md5byte *) system_info.nodename,
 112                   sizeof (system_info.nodename));
 113         MD5Update(&context, (md5byte *) system_info.release,
 114                   sizeof (system_info.release));
 115         MD5Update(&context, (md5byte *) system_info.version,
 116                   sizeof (system_info.version));
 117         MD5Update(&context, (md5byte *) system_info.machine,
 118                   sizeof (system_info.machine));
 119
 120         /* compute the md5 hash of all the bits we just collected */
 121         MD5Final(digest, &context);
 122
 123         /* vary which md5 bytes we pick (though we probably don't need to do
 124          * this, since hopefully MD5 produces results such that each byte is as
 125          * good as any other).
 126          */
 127
 128         if ((fd = open(RANDOM_NUM_GENERATOR, O_RDONLY))) {
 129                 if (read(fd, entropy, 1) == 1)
 130                         bytes = &digest[(entropy[0] % (sizeof(digest) - 6))];
 131                 close(fd);
 132         }
 133
 134         /* print the prefix followed by 6 bytes of the MD5 hash */
 135         sprintf(iname, "%s:%x%x%x%x%x%x", prefix,
 136                 bytes[0], bytes[1], bytes[2], bytes[3], bytes[4], bytes[5]);
 137
 138         iname[sizeof (iname) - 1] = '\0';
 139         printf("%s\n", iname);
 140         return 0;
 141 }