forked from cerc-io/plugeth
pow: only support prime calculations on Go 1.8 and above
This commit is contained in:
parent
023670f6ba
commit
df72e20cc5
@ -35,6 +35,7 @@ import (
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)
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var (
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ErrNonceOutOfRange = errors.New("nonce out of range")
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ErrInvalidDifficulty = errors.New("non-positive difficulty")
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ErrInvalidMixDigest = errors.New("invalid mix digest")
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ErrInvalidPoW = errors.New("pow difficulty invalid")
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@ -174,13 +175,18 @@ func NewSharedEthash() PoW {
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// Verify implements PoW, checking whether the given block satisfies the PoW
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// difficulty requirements.
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func (ethash *Ethash) Verify(block Block) error {
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// Sanity check that the block number is below the lookup table size (60M blocks)
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number := block.NumberU64()
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if number/epochLength >= uint64(len(cacheSizes)) {
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// Go < 1.7 cannot calculate new cache/dataset sizes (no fast prime check)
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return ErrNonceOutOfRange
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}
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// Ensure twe have a valid difficulty for the block
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difficulty := block.Difficulty()
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if difficulty.Sign() <= 0 {
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return ErrInvalidDifficulty
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}
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// Recompute the digest and PoW value and verify against the block
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number := block.NumberU64()
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cache := ethash.cache(number)
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size := datasetSize(number)
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@ -19,7 +19,6 @@ package pow
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import (
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"encoding/binary"
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"io"
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"math/big"
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"runtime"
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"sync"
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"sync/atomic"
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@ -45,42 +44,6 @@ const (
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loopAccesses = 64 // Number of accesses in hashimoto loop
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)
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// cacheSize calculates and returns the size of the ethash verification cache that
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// belongs to a certain block number. The cache size grows linearly, however, we
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// always take the highest prime below the linearly growing threshold in order to
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// reduce the risk of accidental regularities leading to cyclic behavior.
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func cacheSize(block uint64) uint64 {
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// If we have a pre-generated value, use that
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epoch := int(block / epochLength)
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if epoch < len(cacheSizes) {
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return cacheSizes[epoch]
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}
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// No known cache size, calculate manually (sanity branch only)
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size := uint64(cacheInitBytes + cacheGrowthBytes*epoch - hashBytes)
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for !new(big.Int).SetUint64(size / hashBytes).ProbablyPrime(1) { // Always accurate for n < 2^64
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size -= 2 * hashBytes
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}
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return size
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}
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// datasetSize calculates and returns the size of the ethash mining dataset that
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// belongs to a certain block number. The dataset size grows linearly, however, we
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// always take the highest prime below the linearly growing threshold in order to
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// reduce the risk of accidental regularities leading to cyclic behavior.
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func datasetSize(block uint64) uint64 {
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// If we have a pre-generated value, use that
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epoch := int(block / epochLength)
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if epoch < len(datasetSizes) {
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return datasetSizes[epoch]
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}
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// No known dataset size, calculate manually (sanity branch only)
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size := uint64(datasetInitBytes + datasetGrowthBytes*epoch - mixBytes)
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for !new(big.Int).SetUint64(size / mixBytes).ProbablyPrime(1) { // Always accurate for n < 2^64
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size -= 2 * mixBytes
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}
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return size
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}
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// seedHash is the seed to use for generating a verification cache and the mining
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// dataset.
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func seedHash(block uint64) []byte {
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47
pow/ethash_algo_go1.7.go
Normal file
47
pow/ethash_algo_go1.7.go
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@ -0,0 +1,47 @@
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// Copyright 2017 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser 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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// The go-ethereum library 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 Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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// +build !go1.8
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package pow
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// cacheSize calculates and returns the size of the ethash verification cache that
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// belongs to a certain block number. The cache size grows linearly, however, we
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// always take the highest prime below the linearly growing threshold in order to
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// reduce the risk of accidental regularities leading to cyclic behavior.
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func cacheSize(block uint64) uint64 {
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// If we have a pre-generated value, use that
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epoch := int(block / epochLength)
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if epoch < len(cacheSizes) {
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return cacheSizes[epoch]
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}
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// We don't have a way to verify primes fast before Go 1.8
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panic("fast prime testing unsupported in Go < 1.8")
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}
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// datasetSize calculates and returns the size of the ethash mining dataset that
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// belongs to a certain block number. The dataset size grows linearly, however, we
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// always take the highest prime below the linearly growing threshold in order to
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// reduce the risk of accidental regularities leading to cyclic behavior.
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func datasetSize(block uint64) uint64 {
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// If we have a pre-generated value, use that
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epoch := int(block / epochLength)
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if epoch < len(datasetSizes) {
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return datasetSizes[epoch]
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}
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// We don't have a way to verify primes fast before Go 1.8
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panic("fast prime testing unsupported in Go < 1.8")
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}
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57
pow/ethash_algo_go1.8.go
Normal file
57
pow/ethash_algo_go1.8.go
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@ -0,0 +1,57 @@
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// Copyright 2017 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser 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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// The go-ethereum library 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 Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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// +build go1.8
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package pow
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import "math/big"
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// cacheSize calculates and returns the size of the ethash verification cache that
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// belongs to a certain block number. The cache size grows linearly, however, we
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// always take the highest prime below the linearly growing threshold in order to
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// reduce the risk of accidental regularities leading to cyclic behavior.
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func cacheSize(block uint64) uint64 {
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// If we have a pre-generated value, use that
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epoch := int(block / epochLength)
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if epoch < len(cacheSizes) {
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return cacheSizes[epoch]
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}
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// No known cache size, calculate manually (sanity branch only)
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size := uint64(cacheInitBytes + cacheGrowthBytes*uint64(epoch) - hashBytes)
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for !new(big.Int).SetUint64(size / hashBytes).ProbablyPrime(1) { // Always accurate for n < 2^64
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size -= 2 * hashBytes
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}
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return size
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}
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// datasetSize calculates and returns the size of the ethash mining dataset that
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// belongs to a certain block number. The dataset size grows linearly, however, we
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// always take the highest prime below the linearly growing threshold in order to
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// reduce the risk of accidental regularities leading to cyclic behavior.
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func datasetSize(block uint64) uint64 {
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// If we have a pre-generated value, use that
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epoch := int(block / epochLength)
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if epoch < len(datasetSizes) {
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return datasetSizes[epoch]
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}
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// No known dataset size, calculate manually (sanity branch only)
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size := uint64(datasetInitBytes + datasetGrowthBytes*uint64(epoch) - mixBytes)
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for !new(big.Int).SetUint64(size / mixBytes).ProbablyPrime(1) { // Always accurate for n < 2^64
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size -= 2 * mixBytes
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}
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return size
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}
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46
pow/ethash_algo_go1.8_test.go
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46
pow/ethash_algo_go1.8_test.go
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@ -0,0 +1,46 @@
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// Copyright 2017 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser 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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// The go-ethereum library 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 Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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// +build go1.8
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package pow
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import "testing"
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// Tests whether the dataset size calculator work correctly by cross checking the
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// hard coded lookup table with the value generated by it.
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func TestSizeCalculations(t *testing.T) {
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var tests []uint64
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// Verify all the cache sizes from the lookup table
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defer func(sizes []uint64) { cacheSizes = sizes }(cacheSizes)
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tests, cacheSizes = cacheSizes, []uint64{}
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for i, test := range tests {
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if size := cacheSize(uint64(i*epochLength) + 1); size != test {
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t.Errorf("cache %d: cache size mismatch: have %d, want %d", i, size, test)
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}
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}
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// Verify all the dataset sizes from the lookup table
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defer func(sizes []uint64) { datasetSizes = sizes }(datasetSizes)
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tests, datasetSizes = datasetSizes, []uint64{}
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for i, test := range tests {
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if size := datasetSize(uint64(i*epochLength) + 1); size != test {
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t.Errorf("dataset %d: dataset size mismatch: have %d, want %d", i, size, test)
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}
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}
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}
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@ -23,31 +23,6 @@ import (
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"github.com/ethereum/go-ethereum/common/hexutil"
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)
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// Tests whether the dataset size calculator work correctly by cross checking the
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// hard coded lookup table with the value generated by it.
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func TestSizeCalculations(t *testing.T) {
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var tests []uint64
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// Verify all the cache sizes from the lookup table
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defer func(sizes []uint64) { cacheSizes = sizes }(cacheSizes)
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tests, cacheSizes = cacheSizes, []uint64{}
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for i, test := range tests {
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if size := cacheSize(uint64(i*epochLength) + 1); size != test {
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t.Errorf("cache %d: cache size mismatch: have %d, want %d", i, size, test)
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}
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}
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// Verify all the dataset sizes from the lookup table
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defer func(sizes []uint64) { datasetSizes = sizes }(datasetSizes)
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tests, datasetSizes = datasetSizes, []uint64{}
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for i, test := range tests {
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if size := datasetSize(uint64(i*epochLength) + 1); size != test {
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t.Errorf("dataset %d: dataset size mismatch: have %d, want %d", i, size, test)
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}
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}
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}
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// Tests that verification caches can be correctly generated.
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func TestCacheGeneration(t *testing.T) {
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tests := []struct {
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