src/libsystemd/sd-id128/sd-id128.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2011 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd 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   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <unistd.h>
  23
  24 #include "sd-id128.h"
  25
  26 #include "fd-util.h"
  27 #include "hexdecoct.h"
  28 #include "io-util.h"
  29 #include "macro.h"
  30 #include "random-util.h"
  31 #include "util.h"
  32
  33 _public_ char *sd_id128_to_string(sd_id128_t id, char s[SD_ID128_STRING_MAX]) {
  34         unsigned n;
  35
  36         assert_return(s, NULL);
  37
  38         for (n = 0; n < 16; n++) {
  39                 s[n*2] = hexchar(id.bytes[n] >> 4);
  40                 s[n*2+1] = hexchar(id.bytes[n] & 0xF);
  41         }
  42
  43         s[32] = 0;
  44
  45         return s;
  46 }
  47
  48 _public_ int sd_id128_from_string(const char s[], sd_id128_t *ret) {
  49         unsigned n, i;
  50         sd_id128_t t;
  51         bool is_guid = false;
  52
  53         assert_return(s, -EINVAL);
  54         assert_return(ret, -EINVAL);
  55
  56         for (n = 0, i = 0; n < 16;) {
  57                 int a, b;
  58
  59                 if (s[i] == '-') {
  60                         /* Is this a GUID? Then be nice, and skip over
  61                          * the dashes */
  62
  63                         if (i == 8)
  64                                 is_guid = true;
  65                         else if (i == 13 || i == 18 || i == 23) {
  66                                 if (!is_guid)
  67                                         return -EINVAL;
  68                         } else
  69                                 return -EINVAL;
  70
  71                         i++;
  72                         continue;
  73                 }
  74
  75                 a = unhexchar(s[i++]);
  76                 if (a < 0)
  77                         return -EINVAL;
  78
  79                 b = unhexchar(s[i++]);
  80                 if (b < 0)
  81                         return -EINVAL;
  82
  83                 t.bytes[n++] = (a << 4) | b;
  84         }
  85
  86         if (i != (is_guid ? 36 : 32))
  87                 return -EINVAL;
  88
  89         if (s[i] != 0)
  90                 return -EINVAL;
  91
  92         *ret = t;
  93         return 0;
  94 }
  95
  96 static sd_id128_t make_v4_uuid(sd_id128_t id) {
  97         /* Stolen from generate_random_uuid() of drivers/char/random.c
  98          * in the kernel sources */
  99
 100         /* Set UUID version to 4 --- truly random generation */
 101         id.bytes[6] = (id.bytes[6] & 0x0F) | 0x40;
 102
 103         /* Set the UUID variant to DCE */
 104         id.bytes[8] = (id.bytes[8] & 0x3F) | 0x80;
 105
 106         return id;
 107 }
 108
 109 _public_ int sd_id128_get_machine(sd_id128_t *ret) {
 110         static thread_local sd_id128_t saved_machine_id;
 111         static thread_local bool saved_machine_id_valid = false;
 112         _cleanup_close_ int fd = -1;
 113         char buf[33];
 114         unsigned j;
 115         sd_id128_t t;
 116         int r;
 117
 118         assert_return(ret, -EINVAL);
 119
 120         if (saved_machine_id_valid) {
 121                 *ret = saved_machine_id;
 122                 return 0;
 123         }
 124
 125         fd = open("/etc/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY);
 126         if (fd < 0)
 127                 return -errno;
 128
 129         r = loop_read_exact(fd, buf, 33, false);
 130         if (r < 0)
 131                 return r;
 132         if (buf[32] !='\n')
 133                 return -EIO;
 134
 135         for (j = 0; j < 16; j++) {
 136                 int a, b;
 137
 138                 a = unhexchar(buf[j*2]);
 139                 b = unhexchar(buf[j*2+1]);
 140
 141                 if (a < 0 || b < 0)
 142                         return -EIO;
 143
 144                 t.bytes[j] = a << 4 | b;
 145         }
 146
 147         saved_machine_id = t;
 148         saved_machine_id_valid = true;
 149
 150         *ret = t;
 151         return 0;
 152 }
 153
 154 _public_ int sd_id128_get_boot(sd_id128_t *ret) {
 155         static thread_local sd_id128_t saved_boot_id;
 156         static thread_local bool saved_boot_id_valid = false;
 157         _cleanup_close_ int fd = -1;
 158         char buf[36];
 159         unsigned j;
 160         sd_id128_t t;
 161         char *p;
 162         int r;
 163
 164         assert_return(ret, -EINVAL);
 165
 166         if (saved_boot_id_valid) {
 167                 *ret = saved_boot_id;
 168                 return 0;
 169         }
 170
 171         fd = open("/proc/sys/kernel/random/boot_id", O_RDONLY|O_CLOEXEC|O_NOCTTY);
 172         if (fd < 0)
 173                 return -errno;
 174
 175         r = loop_read_exact(fd, buf, 36, false);
 176         if (r < 0)
 177                 return r;
 178
 179         for (j = 0, p = buf; j < 16; j++) {
 180                 int a, b;
 181
 182                 if (p >= buf + 35)
 183                         return -EIO;
 184
 185                 if (*p == '-') {
 186                         p++;
 187                         if (p >= buf + 35)
 188                                 return -EIO;
 189                 }
 190
 191                 a = unhexchar(p[0]);
 192                 b = unhexchar(p[1]);
 193
 194                 if (a < 0 || b < 0)
 195                         return -EIO;
 196
 197                 t.bytes[j] = a << 4 | b;
 198
 199                 p += 2;
 200         }
 201
 202         saved_boot_id = t;
 203         saved_boot_id_valid = true;
 204
 205         *ret = t;
 206         return 0;
 207 }
 208
 209 _public_ int sd_id128_randomize(sd_id128_t *ret) {
 210         sd_id128_t t;
 211         int r;
 212
 213         assert_return(ret, -EINVAL);
 214
 215         r = dev_urandom(&t, sizeof(t));
 216         if (r < 0)
 217                 return r;
 218
 219         /* Turn this into a valid v4 UUID, to be nice. Note that we
 220          * only guarantee this for newly generated UUIDs, not for
 221          * pre-existing ones. */
 222
 223         *ret = make_v4_uuid(t);
 224         return 0;
 225 }