src/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 General Public License as published by
  10   the Free Software Foundation; either version 2 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   General Public License for more details.
  17
  18   You should have received a copy of the GNU 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 "sd-id128.h"
  27
  28 #include "util.h"
  29 #include "macro.h"
  30
  31 _public_ char *sd_id128_to_string(sd_id128_t id, char s[33]) {
  32         unsigned n;
  33
  34         if (!s)
  35                 return NULL;
  36
  37         for (n = 0; n < 16; n++) {
  38                 s[n*2] = hexchar(id.bytes[n] >> 4);
  39                 s[n*2+1] = hexchar(id.bytes[n] & 0xF);
  40         }
  41
  42         s[32] = 0;
  43
  44         return s;
  45 }
  46
  47 _public_ int sd_id128_from_string(const char s[33], sd_id128_t *ret) {
  48         unsigned n;
  49         sd_id128_t t;
  50
  51         if (!s)
  52                 return -EINVAL;
  53         if (!ret)
  54                 return -EINVAL;
  55
  56         for (n = 0; n < 16; n++) {
  57                 int a, b;
  58
  59                 a = unhexchar(s[n*2]);
  60                 if (a < 0)
  61                         return -EINVAL;
  62
  63                 b = unhexchar(s[n*2+1]);
  64                 if (b < 0)
  65                         return -EINVAL;
  66
  67                 t.bytes[n] = (a << 4) | b;
  68         }
  69
  70         if (s[32] != 0)
  71                 return -EINVAL;
  72
  73         *ret = t;
  74         return 0;
  75 }
  76
  77 static sd_id128_t make_v4_uuid(sd_id128_t id) {
  78         /* Stolen from generate_random_uuid() of drivers/char/random.c
  79          * in the kernel sources */
  80
  81         /* Set UUID version to 4 --- truly random generation */
  82         id.bytes[6] = (id.bytes[6] & 0x0F) | 0x40;
  83
  84         /* Set the UUID variant to DCE */
  85         id.bytes[8] = (id.bytes[8] & 0x3F) | 0x80;
  86
  87         return id;
  88 }
  89
  90 _public_ int sd_id128_get_machine(sd_id128_t *ret) {
  91         static __thread sd_id128_t saved_machine_id;
  92         static __thread bool saved_machine_id_valid = false;
  93         int fd;
  94         char buf[32];
  95         ssize_t k;
  96         unsigned j;
  97         sd_id128_t t;
  98
  99         if (!ret)
 100                 return -EINVAL;
 101
 102         if (saved_machine_id_valid) {
 103                 *ret = saved_machine_id;
 104                 return 0;
 105         }
 106
 107         fd = open("/etc/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY);
 108         if (fd < 0)
 109                 return -errno;
 110
 111         k = loop_read(fd, buf, 32, false);
 112         close_nointr_nofail(fd);
 113
 114         if (k < 0)
 115                 return (int) k;
 116
 117         if (k < 32)
 118                 return -EIO;
 119
 120         for (j = 0; j < 16; j++) {
 121                 int a, b;
 122
 123                 a = unhexchar(buf[j*2]);
 124                 b = unhexchar(buf[j*2+1]);
 125
 126                 if (a < 0 || b < 0)
 127                         return -EIO;
 128
 129                 t.bytes[j] = a << 4 | b;
 130         }
 131
 132         saved_machine_id = t;
 133         saved_machine_id_valid = true;
 134
 135         *ret = t;
 136         return 0;
 137 }
 138
 139 _public_ int sd_id128_get_boot(sd_id128_t *ret) {
 140         static __thread sd_id128_t saved_boot_id;
 141         static __thread bool saved_boot_id_valid = false;
 142         int fd;
 143         char buf[36];
 144         ssize_t k;
 145         unsigned j;
 146         sd_id128_t t;
 147         char *p;
 148
 149         if (!ret)
 150                 return -EINVAL;
 151
 152         if (saved_boot_id_valid) {
 153                 *ret = saved_boot_id;
 154                 return 0;
 155         }
 156
 157         fd = open("/proc/sys/kernel/random/boot_id", O_RDONLY|O_CLOEXEC|O_NOCTTY);
 158         if (fd < 0)
 159                 return -errno;
 160
 161         k = loop_read(fd, buf, 36, false);
 162         close_nointr_nofail(fd);
 163
 164         if (k < 0)
 165                 return (int) k;
 166
 167         if (k < 36)
 168                 return -EIO;
 169
 170         for (j = 0, p = buf; j < 16; j++) {
 171                 int a, b;
 172
 173                 if (*p == '-')
 174                         p++;
 175
 176                 a = unhexchar(p[0]);
 177                 b = unhexchar(p[1]);
 178
 179                 if (a < 0 || b < 0)
 180                         return -EIO;
 181
 182                 t.bytes[j] = a << 4 | b;
 183
 184                 p += 2;
 185         }
 186
 187         saved_boot_id = t;
 188         saved_boot_id_valid = true;
 189
 190         *ret = t;
 191         return 0;
 192 }
 193
 194 _public_ int sd_id128_randomize(sd_id128_t *ret) {
 195         int fd;
 196         ssize_t k;
 197         sd_id128_t t;
 198
 199         if (!ret)
 200                 return -EINVAL;
 201
 202         fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY);
 203         if (fd < 0)
 204                 return -errno;
 205
 206         k = loop_read(fd, &t, 16, false);
 207         close_nointr_nofail(fd);
 208
 209         if (k < 0)
 210                 return (int) k;
 211
 212         if (k < 16)
 213                 return -EIO;
 214
 215         /* Turn this into a valid v4 UUID, to be nice. Note that we
 216          * only guarantee this for newly generated UUIDs, not for
 217          * pre-existing ones.*/
 218
 219         *ret = make_v4_uuid(t);
 220         return 0;
 221 }