mirror of https://github.com/OpenTTD/OpenTTD.git
132 lines
4.2 KiB
C++
132 lines
4.2 KiB
C++
/*
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* This file is part of OpenTTD.
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* OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
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* OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
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*/
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/** @file random_func.cpp Implementation of the pseudo random generator. */
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#include "../stdafx.h"
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#include "random_func.hpp"
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#include "bitmath_func.hpp"
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#include "../debug.h"
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#ifdef RANDOM_DEBUG
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#include "../network/network.h"
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#include "../network/network_server.h"
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#include "../network/network_internal.h"
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#include "../company_func.h"
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#include "../fileio_func.h"
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#include "../timer/timer_game_calendar.h"
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#endif /* RANDOM_DEBUG */
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#if defined(_WIN32)
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# include <windows.h>
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# include <bcrypt.h>
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#elif defined(__APPLE__) || defined(__NetBSD__) || defined(__FreeBSD__)
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// No includes required.
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#elif defined(__GLIBC__) && ((__GLIBC__ > 2) || ((__GLIBC__ == 2) && (__GLIBC_MINOR__ >= 25)))
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# include <sys/random.h>
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#elif defined(__EMSCRIPTEN__)
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# include <emscripten.h>
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#endif
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#include "../safeguards.h"
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Randomizer _random, _interactive_random;
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/**
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* Generate the next pseudo random number
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* @return the random number
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*/
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uint32_t Randomizer::Next()
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{
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const uint32_t s = this->state[0];
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const uint32_t t = this->state[1];
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this->state[0] = s + std::rotr(t ^ 0x1234567F, 7) + 1;
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return this->state[1] = std::rotr(s, 3) - 1;
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}
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/**
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* (Re)set the state of the random number generator.
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* @param seed the new state
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*/
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void Randomizer::SetSeed(uint32_t seed)
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{
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this->state[0] = seed;
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this->state[1] = seed;
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}
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/**
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* (Re)set the state of the random number generators.
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* @param seed the new state
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*/
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void SetRandomSeed(uint32_t seed)
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{
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_random.SetSeed(seed);
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_interactive_random.SetSeed(seed * 0x1234567);
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}
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#ifdef RANDOM_DEBUG
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uint32_t Random(const std::source_location location)
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{
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if (_networking && (!_network_server || (NetworkClientSocket::IsValidID(0) && NetworkClientSocket::Get(0)->status != NetworkClientSocket::STATUS_INACTIVE))) {
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Debug(random, 0, "{:08x}; {:02x}; {:04x}; {:02x}; {}:{}", TimerGameEconomy::date, TimerGameEconomy::date_fract, _frame_counter, (uint8_t)_current_company, location.file_name(), location.line());
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}
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return _random.Next();
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}
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#endif /* RANDOM_DEBUG */
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/**
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* Fill the given buffer with random bytes.
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*
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* This function will attempt to use a cryptographically-strong random
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* generator, but will fall back to a weaker random generator if none is
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* available.
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*
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* In the end, the buffer will always be filled with some form of random
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* bytes when this function returns.
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*
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* @param buf The buffer to fill with random bytes.
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*/
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void RandomBytesWithFallback(std::span<uint8_t> buf)
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{
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#if defined(_WIN32)
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auto res = BCryptGenRandom(nullptr, static_cast<PUCHAR>(buf.data()), static_cast<ULONG>(buf.size()), BCRYPT_USE_SYSTEM_PREFERRED_RNG);
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if (res >= 0) return;
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#elif defined(__APPLE__) || defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__)
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arc4random_buf(buf.data(), buf.size());
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return;
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#elif defined(__GLIBC__) && ((__GLIBC__ > 2) || ((__GLIBC__ == 2) && (__GLIBC_MINOR__ >= 25)))
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auto res = getrandom(buf.data(), buf.size(), 0);
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if (res > 0 && static_cast<size_t>(res) == buf.size()) return;
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#elif defined(__EMSCRIPTEN__)
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auto res = EM_ASM_INT({
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var buf = $0;
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var bytes = $1;
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var crypto = window.crypto;
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if (crypto === undefined || crypto.getRandomValues === undefined) {
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return -1;
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}
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crypto.getRandomValues(Module.HEAPU8.subarray(buf, buf + bytes));
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return 1;
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}, buf.data(), buf.size());
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if (res > 0) return;
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#else
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# warning "No cryptographically-strong random generator available; using a fallback instead"
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#endif
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static bool warned_once = false;
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Debug(misc, warned_once ? 1 : 0, "Cryptographically-strong random generator unavailable; using fallback");
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warned_once = true;
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for (uint i = 0; i < buf.size(); i++) {
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buf[i] = static_cast<uint8_t>(InteractiveRandom());
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}
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}
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