src/common/uuid.c

   1 /*
   2  * Copyright (C) 2018 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   3  * Copyright (C) 2019 Michael Jeanson <mjeanson@efficios.com>
   4  *
   5  * SPDX-License-Identifier: LGPL-2.1-only
   6  *
   7  */
   8
   9 #include <common/compat/string.h>
  10 #include <common/random.h>
  11 #include <common/error.h>
  12
  13 #include <stddef.h>
  14 #include <stdint.h>
  15 #include <stdio.h>
  16 #include <stdlib.h>
  17 #include <string.h>
  18 #include <time.h>
  19
  20 #include "uuid.h"
  21
  22 static const lttng_uuid nil_uuid;
  23 static bool lttng_uuid_is_init;
  24
  25 void lttng_uuid_to_str(const lttng_uuid uuid, char *uuid_str)
  26 {
  27         sprintf(uuid_str, LTTNG_UUID_FMT, LTTNG_UUID_FMT_VALUES(uuid));
  28 }
  29
  30 int lttng_uuid_from_str(const char *str_in, lttng_uuid uuid_out)
  31 {
  32         int ret = 0;
  33         lttng_uuid uuid_scan;
  34
  35         if ((str_in == NULL) || (uuid_out == NULL)) {
  36                 ret = -1;
  37                 goto end;
  38         }
  39
  40         if (lttng_strnlen(str_in, LTTNG_UUID_STR_LEN) != LTTNG_UUID_STR_LEN - 1) {
  41                 ret = -1;
  42                 goto end;
  43         }
  44
  45         /* Scan to a temporary location in case of a partial match. */
  46         if (sscanf(str_in, LTTNG_UUID_FMT, LTTNG_UUID_SCAN_VALUES(uuid_scan)) !=
  47                         LTTNG_UUID_LEN) {
  48                 ret = -1;
  49         }
  50
  51         lttng_uuid_copy(uuid_out, uuid_scan);
  52 end:
  53         return ret;
  54 }
  55
  56 bool lttng_uuid_is_equal(const lttng_uuid a, const lttng_uuid b)
  57 {
  58         return memcmp(a, b, LTTNG_UUID_LEN) == 0;
  59 }
  60
  61 bool lttng_uuid_is_nil(const lttng_uuid uuid)
  62 {
  63         return memcmp(nil_uuid, uuid, sizeof(lttng_uuid)) == 0;
  64 }
  65
  66 void lttng_uuid_copy(lttng_uuid dst, const lttng_uuid src)
  67 {
  68         memcpy(dst, src, LTTNG_UUID_LEN);
  69 }
  70
  71 /*
  72  * Generate a random UUID according to RFC4122, section 4.4.
  73  */
  74 int lttng_uuid_generate(lttng_uuid uuid_out)
  75 {
  76         int i, ret = 0;
  77
  78         if (uuid_out == NULL) {
  79                 ret = -1;
  80                 goto end;
  81         }
  82
  83         if (!lttng_uuid_is_init) {
  84                 seed_t new_seed;
  85
  86                 ret = lttng_produce_best_effort_random_seed(&new_seed);
  87                 if (ret) {
  88                         ERR("Failed to initialize random seed while generating UUID");
  89                         goto end;
  90                 }
  91
  92                 srand(new_seed);
  93                 lttng_uuid_is_init = true;
  94         }
  95
  96         /*
  97          * Generate 16 bytes of random bits.
  98          */
  99         for (i = 0; i < LTTNG_UUID_LEN; i++) {
 100                 uuid_out[i] = (uint8_t) rand();
 101         }
 102
 103         /*
 104          * Set the two most significant bits (bits 6 and 7) of the
 105          * clock_seq_hi_and_reserved to zero and one, respectively.
 106          */
 107         uuid_out[8] &= ~(1 << 6);
 108         uuid_out[8] |= (1 << 7);
 109
 110         /*
 111          * Set the four most significant bits (bits 12 through 15) of the
 112          * time_hi_and_version field to the 4-bit version number from
 113          * Section 4.1.3.
 114          */
 115         uuid_out[6] &= 0x0f;
 116         uuid_out[6] |= (LTTNG_UUID_VER << 4);
 117
 118 end:
 119         return ret;
 120 }