mirror of
https://github.com/savoirfairelinux/opendht.git
synced 2026-11-08 04:21:51 +00:00
118 lines
2.6 KiB
C++
118 lines
2.6 KiB
C++
/*
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* Copyright (C) 2014-2017 Savoir-faire Linux Inc.
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* Author : Adrien Béraud <adrien.beraud@savoirfairelinux.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#include "rng.h"
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#include <chrono>
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#include <cstring>
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namespace dht {
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namespace crypto {
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random_device::random_device() :
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gen(std::chrono::system_clock::now().time_since_epoch().count())
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{}
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random_device::result_type
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random_device::operator()()
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{
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result_type prand = dis(gen);
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result_type hwrand;
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if (hasRdseed() and rdseed(&hwrand))
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prand ^= hwrand;
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else if (hasRdrand() and rdrand(&hwrand))
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prand ^= hwrand;
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return prand;
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}
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random_device::CPUIDinfo::CPUIDinfo(const unsigned int func, const unsigned int subfunc)
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{
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__asm__ __volatile__ (
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"cpuid"
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: "=a"(EAX), "=b"(EBX), "=c"(ECX), "=d"(EDX)
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: "a"(func), "c"(subfunc)
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);
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}
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bool
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random_device::hasIntelCpu()
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{
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CPUIDinfo info (0, 0);
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return (memcmp((char *) (&info.EBX), "Genu", 4) == 0
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&& memcmp((char *) (&info.EDX), "ineI", 4) == 0
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&& memcmp((char *) (&info.ECX), "ntel", 4) == 0);
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}
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bool
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random_device::_hasRdrand()
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{
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return hasIntelCpu() && (CPUIDinfo {1, 0}.ECX & (1 << 30));
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}
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bool
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random_device::_hasRdseed()
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{
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return hasIntelCpu() && (CPUIDinfo {7, 0}.ECX & (1 << 18));
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}
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bool
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random_device::rdrandStep(result_type* r)
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{
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unsigned char ok;
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asm volatile ("rdrand %0; setc %1"
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: "=r" (*r), "=qm" (ok));
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return ok;
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}
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bool
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random_device::rdrand(result_type* r)
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{
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result_type res;
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unsigned retries = 8;
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while (retries--)
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if (rdrandStep(&res)) {
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*r = res;
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return true;
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}
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return false;
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}
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bool
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random_device::rdseedStep(result_type* r)
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{
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unsigned char ok;
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asm volatile ("rdseed %0; setc %1"
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: "=r" (*r), "=qm" (ok));
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return ok;
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}
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bool
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random_device::rdseed(result_type* r)
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{
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result_type res;
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unsigned retries = 256;
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while (retries--)
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if (rdseedStep(&res)) {
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*r = res;
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return true;
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}
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return false;
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}
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}}
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