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//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2025
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#include "td/utils/Random.h"
#include "td/utils/logging.h"
#include "td/utils/port/thread_local.h"
#if TD_HAVE_OPENSSL
#include <openssl/rand.h>
#endif
#include <atomic>
#include <cstring>
#include <limits>
#include <random>
namespace td {
#if TD_HAVE_OPENSSL
namespace {
std::atomic<int64> random_seed_generation{0};
} // namespace
void Random::secure_bytes(MutableSlice dest) {
Random::secure_bytes(dest.ubegin(), dest.size());
}
void Random::secure_bytes(unsigned char *ptr, size_t size) {
constexpr size_t BUF_SIZE = 512;
static TD_THREAD_LOCAL unsigned char *buf; // static zero-initialized
static TD_THREAD_LOCAL size_t buf_pos;
static TD_THREAD_LOCAL int64 generation;
if (init_thread_local<unsigned char[]>(buf, BUF_SIZE)) {
buf_pos = BUF_SIZE;
generation = 0;
}
if (ptr == nullptr) {
MutableSlice(buf, BUF_SIZE).fill_zero_secure();
buf_pos = BUF_SIZE;
return;
}
if (generation != random_seed_generation.load(std::memory_order_relaxed)) {
generation = random_seed_generation.load(std::memory_order_acquire);
buf_pos = BUF_SIZE;
}
auto ready = min(size, BUF_SIZE - buf_pos);
if (ready != 0) {
std::memcpy(ptr, buf + buf_pos, ready);
buf_pos += ready;
ptr += ready;
size -= ready;
if (size == 0) {
return;
}
}
if (size < BUF_SIZE) {
int err = RAND_bytes(buf, static_cast<int>(BUF_SIZE));
// TODO: it CAN fail
LOG_IF(FATAL, err != 1);
buf_pos = size;
std::memcpy(ptr, buf, size);
return;
}
CHECK(size <= static_cast<size_t>(std::numeric_limits<int>::max()));
int err = RAND_bytes(ptr, static_cast<int>(size));
// TODO: it CAN fail
LOG_IF(FATAL, err != 1);
}
int32 Random::secure_int32() {
int32 res = 0;
secure_bytes(reinterpret_cast<unsigned char *>(&res), sizeof(int32));
return res;
}
int64 Random::secure_int64() {
int64 res = 0;
secure_bytes(reinterpret_cast<unsigned char *>(&res), sizeof(int64));
return res;
}
uint32 Random::secure_uint32() {
uint32 res = 0;
secure_bytes(reinterpret_cast<unsigned char *>(&res), sizeof(uint32));
return res;
}
uint64 Random::secure_uint64() {
uint64 res = 0;
secure_bytes(reinterpret_cast<unsigned char *>(&res), sizeof(uint64));
return res;
}
void Random::add_seed(Slice bytes, double entropy) {
RAND_add(bytes.data(), static_cast<int>(bytes.size()), entropy);
random_seed_generation++;
}
void Random::secure_cleanup() {
Random::secure_bytes(nullptr, 0);
}
#endif
static unsigned int rand_device_helper() {
static TD_THREAD_LOCAL std::random_device *rd;
init_thread_local<std::random_device>(rd);
return (*rd)();
}
uint32 Random::fast_uint32() {
static TD_THREAD_LOCAL std::mt19937 *gen;
if (!gen) {
auto &rg = rand_device_helper;
std::seed_seq seq{rg(), rg(), rg(), rg(), rg(), rg(), rg(), rg(), rg(), rg(), rg(), rg()};
init_thread_local<std::mt19937>(gen, seq);
}
return static_cast<uint32>((*gen)());
}
uint64 Random::fast_uint64() {
static TD_THREAD_LOCAL std::mt19937_64 *gen;
if (!gen) {
auto &rg = rand_device_helper;
std::seed_seq seq{rg(), rg(), rg(), rg(), rg(), rg(), rg(), rg(), rg(), rg(), rg(), rg()};
init_thread_local<std::mt19937_64>(gen, seq);
}
return static_cast<uint64>((*gen)());
}
int Random::fast(int min_value, int max_value) {
if (min_value == std::numeric_limits<int>::min() && max_value == std::numeric_limits<int>::max()) {
// to prevent integer overflow and division by zero
min_value++;
}
DCHECK(min_value <= max_value);
return static_cast<int>(min_value + fast_uint32() % (max_value - min_value + 1)); // TODO signed_cast
}
double Random::fast(double min_value, double max_value) {
DCHECK(min_value <= max_value);
return min_value + fast_uint32() * 1.0 / std::numeric_limits<uint32>::max() * (max_value - min_value);
}
bool Random::fast_bool() {
return (fast_uint32() & 1) != 0;
}
Random::Xorshift128plus::Xorshift128plus(uint64 seed) {
auto next = [&] {
// splitmix64
seed += static_cast<uint64>(0x9E3779B97F4A7C15ull);
uint64 z = seed;
z = (z ^ (z >> 30)) * static_cast<uint64>(0xBF58476D1CE4E5B9ull);
z = (z ^ (z >> 27)) * static_cast<uint64>(0x94D049BB133111EBull);
return z ^ (z >> 31);
};
seed_[0] = next();
seed_[1] = next();
}
Random::Xorshift128plus::Xorshift128plus(uint64 seed_a, uint64 seed_b) {
seed_[0] = seed_a;
seed_[1] = seed_b;
}
uint64 Random::Xorshift128plus::operator()() {
uint64 x = seed_[0];
const uint64 y = seed_[1];
seed_[0] = y;
x ^= x << 23;
seed_[1] = x ^ y ^ (x >> 17) ^ (y >> 26);
return seed_[1] + y;
}
int Random::Xorshift128plus::fast(int min_value, int max_value) {
return static_cast<int>((*this)() % (max_value - min_value + 1) + min_value);
}
int64 Random::Xorshift128plus::fast64(int64 min_value, int64 max_value) {
return static_cast<int64>((*this)() % (max_value - min_value + 1) + min_value);
}
void Random::Xorshift128plus::bytes(MutableSlice dest) {
int cnt = 0;
uint64 buf = 0;
for (auto &c : dest) {
if (cnt == 0) {
buf = operator()();
cnt = 8;
}
cnt--;
c = static_cast<char>(buf & 255);
buf >>= 8;
}
}
} // namespace td
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