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

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2011 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <errno.h>
  23 #include <fcntl.h>
  24 #include <unistd.h>
  25
  26 #include "util.h"
  27 #include "macro.h"
  28 #include "sd-id128.h"
  29
  30 _public_ char *sd_id128_to_string(sd_id128_t id, char s[33]) {
  31         unsigned n;
  32
  33         assert_return(s, NULL);
  34
  35         for (n = 0; n < 16; n++) {
  36                 s[n*2] = hexchar(id.bytes[n] >> 4);
  37                 s[n*2+1] = hexchar(id.bytes[n] & 0xF);
  38         }
  39
  40         s[32] = 0;
  41
  42         return s;
  43 }
  44
  45 _public_ int sd_id128_from_string(const char s[], sd_id128_t *ret) {
  46         unsigned n, i;
  47         sd_id128_t t;
  48         bool is_guid = false;
  49
  50         assert_return(s, -EINVAL);
  51         assert_return(ret, -EINVAL);
  52
  53         for (n = 0, i = 0; n < 16;) {
  54                 int a, b;
  55
  56                 if (s[i] == '-') {
  57                         /* Is this a GUID? Then be nice, and skip over
  58                          * the dashes */
  59
  60                         if (i == 8)
  61                                 is_guid = true;
  62                         else if (i == 13 || i == 18 || i == 23) {
  63                                 if (!is_guid)
  64                                         return -EINVAL;
  65                         } else
  66                                 return -EINVAL;
  67
  68                         i++;
  69                         continue;
  70                 }
  71
  72                 a = unhexchar(s[i++]);
  73                 if (a < 0)
  74                         return -EINVAL;
  75
  76                 b = unhexchar(s[i++]);
  77                 if (b < 0)
  78                         return -EINVAL;
  79
  80                 t.bytes[n++] = (a << 4) | b;
  81         }
  82
  83         if (i != (is_guid ? 36 : 32))
  84                 return -EINVAL;
  85
  86         if (s[i] != 0)
  87                 return -EINVAL;
  88
  89         *ret = t;
  90         return 0;
  91 }
  92
  93 static sd_id128_t make_v4_uuid(sd_id128_t id) {
  94         /* Stolen from generate_random_uuid() of drivers/char/random.c
  95          * in the kernel sources */
  96
  97         /* Set UUID version to 4 --- truly random generation */
  98         id.bytes[6] = (id.bytes[6] & 0x0F) | 0x40;
  99
 100         /* Set the UUID variant to DCE */
 101         id.bytes[8] = (id.bytes[8] & 0x3F) | 0x80;
 102
 103         return id;
 104 }
 105
 106 _public_ int sd_id128_get_machine(sd_id128_t *ret) {
 107         static thread_local sd_id128_t saved_machine_id;
 108         static thread_local bool saved_machine_id_valid = false;
 109         _cleanup_close_ int fd = -1;
 110         char buf[33];
 111         ssize_t k;
 112         unsigned j;
 113         sd_id128_t t;
 114
 115         assert_return(ret, -EINVAL);
 116
 117         if (saved_machine_id_valid) {
 118                 *ret = saved_machine_id;
 119                 return 0;
 120         }
 121
 122         fd = open("/etc/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY);
 123         if (fd < 0)
 124                 return -errno;
 125
 126         k = loop_read(fd, buf, 33, false);
 127         if (k < 0)
 128                 return (int) k;
 129
 130         if (k != 33)
 131                 return -EIO;
 132
 133         if (buf[32] !='\n')
 134                 return -EIO;
 135
 136         for (j = 0; j < 16; j++) {
 137                 int a, b;
 138
 139                 a = unhexchar(buf[j*2]);
 140                 b = unhexchar(buf[j*2+1]);
 141
 142                 if (a < 0 || b < 0)
 143                         return -EIO;
 144
 145                 t.bytes[j] = a << 4 | b;
 146         }
 147
 148         saved_machine_id = t;
 149         saved_machine_id_valid = true;
 150
 151         *ret = t;
 152         return 0;
 153 }
 154
 155 _public_ int sd_id128_get_boot(sd_id128_t *ret) {
 156         static thread_local sd_id128_t saved_boot_id;
 157         static thread_local bool saved_boot_id_valid = false;
 158         _cleanup_close_ int fd = -1;
 159         char buf[36];
 160         ssize_t k;
 161         unsigned j;
 162         sd_id128_t t;
 163         char *p;
 164
 165         assert_return(ret, -EINVAL);
 166
 167         if (saved_boot_id_valid) {
 168                 *ret = saved_boot_id;
 169                 return 0;
 170         }
 171
 172         fd = open("/proc/sys/kernel/random/boot_id", O_RDONLY|O_CLOEXEC|O_NOCTTY);
 173         if (fd < 0)
 174                 return -errno;
 175
 176         k = loop_read(fd, buf, 36, false);
 177         if (k < 0)
 178                 return (int) k;
 179
 180         if (k != 36)
 181                 return -EIO;
 182
 183         for (j = 0, p = buf; j < 16; j++) {
 184                 int a, b;
 185
 186                 if (p >= buf + k)
 187                         return -EIO;
 188
 189                 if (*p == '-')
 190                         p++;
 191
 192                 a = unhexchar(p[0]);
 193                 b = unhexchar(p[1]);
 194
 195                 if (a < 0 || b < 0)
 196                         return -EIO;
 197
 198                 t.bytes[j] = a << 4 | b;
 199
 200                 p += 2;
 201         }
 202
 203         saved_boot_id = t;
 204         saved_boot_id_valid = true;
 205
 206         *ret = t;
 207         return 0;
 208 }
 209
 210 _public_ int sd_id128_randomize(sd_id128_t *ret) {
 211         sd_id128_t t;
 212         int r;
 213
 214         assert_return(ret, -EINVAL);
 215
 216         r = dev_urandom(&t, sizeof(t));
 217         if (r < 0)
 218                 return r;
 219
 220         /* Turn this into a valid v4 UUID, to be nice. Note that we
 221          * only guarantee this for newly generated UUIDs, not for
 222          * pre-existing ones.*/
 223
 224         *ret = make_v4_uuid(t);
 225         return 0;
 226 }