src/common/uuid.cpp

   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.hpp>
  10 #include <common/error.hpp>
  11 #include <common/format.hpp>
  12 #include <common/random.hpp>
  13
  14 #include <stddef.h>
  15 #include <stdint.h>
  16 #include <stdio.h>
  17 #include <stdlib.h>
  18 #include <string.h>
  19 #include <time.h>
  20
  21 #include "uuid.hpp"
  22
  23 namespace {
  24 const lttng_uuid nil_uuid = {};
  25 bool lttng_uuid_is_init;
  26 } /* namespace */
  27
  28 void lttng_uuid_to_str(const lttng_uuid& uuid, char *uuid_str)
  29 {
  30         sprintf(uuid_str, LTTNG_UUID_FMT, LTTNG_UUID_FMT_VALUES(uuid));
  31 }
  32
  33 std::string lttng::utils::uuid_to_str(const lttng_uuid& uuid)
  34 {
  35         std::string uuid_str(LTTNG_UUID_STR_LEN, '\0');
  36
  37         ::lttng_uuid_to_str(uuid, &uuid_str[0]);
  38
  39         /* Don't include '\0' in the C++ string. */
  40         uuid_str.resize(uuid_str.size() - 1);
  41
  42         return uuid_str;
  43 }
  44
  45 int lttng_uuid_from_str(const char *str_in, lttng_uuid& uuid_out)
  46 {
  47         int ret = 0;
  48         lttng_uuid uuid_scan;
  49
  50         if (str_in == nullptr) {
  51                 ret = -1;
  52                 goto end;
  53         }
  54
  55         if (lttng_strnlen(str_in, LTTNG_UUID_STR_LEN) != LTTNG_UUID_STR_LEN - 1) {
  56                 ret = -1;
  57                 goto end;
  58         }
  59
  60         /* Scan to a temporary location in case of a partial match. */
  61         if (sscanf(str_in, LTTNG_UUID_FMT, LTTNG_UUID_SCAN_VALUES(uuid_scan)) !=
  62                         LTTNG_UUID_LEN) {
  63                 ret = -1;
  64                 goto end;
  65         }
  66
  67         uuid_out = uuid_scan;
  68 end:
  69         return ret;
  70 }
  71
  72 bool lttng_uuid_is_nil(const lttng_uuid& uuid)
  73 {
  74         return uuid == nil_uuid;
  75 }
  76
  77 /*
  78  * Generate a random UUID according to RFC4122, section 4.4.
  79  */
  80 int lttng_uuid_generate(lttng_uuid& uuid_out)
  81 {
  82         int i, ret = 0;
  83
  84         if (!lttng_uuid_is_init) {
  85                 try {
  86                         srand(lttng::random::produce_best_effort_random_seed());
  87                 } catch (std::exception& e) {
  88                         ERR("Failed to initialize random seed during generation of UUID: %s",
  89                                         e.what());
  90                         ret = -1;
  91                         goto end;
  92                 }
  93
  94                 lttng_uuid_is_init = true;
  95         }
  96
  97         /*
  98          * Generate 16 bytes of random bits.
  99          */
 100         for (i = 0; i < LTTNG_UUID_LEN; i++) {
 101                 uuid_out[i] = (uint8_t) rand();
 102         }
 103
 104         /*
 105          * Set the two most significant bits (bits 6 and 7) of the
 106          * clock_seq_hi_and_reserved to zero and one, respectively.
 107          */
 108         uuid_out[8] &= ~(1 << 6);
 109         uuid_out[8] |= (1 << 7);
 110
 111         /*
 112          * Set the four most significant bits (bits 12 through 15) of the
 113          * time_hi_and_version field to the 4-bit version number from
 114          * Section 4.1.3.
 115          */
 116         uuid_out[6] &= 0x0f;
 117         uuid_out[6] |= (LTTNG_UUID_VER << 4);
 118
 119 end:
 120         return ret;
 121 }