498 lines
18 KiB
Go
498 lines
18 KiB
Go
// 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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package ethash
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import (
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"bytes"
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"errors"
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"fmt"
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"math/big"
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"runtime"
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"sync/atomic"
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"time"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/common/math"
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"github.com/ethereum/go-ethereum/consensus"
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"github.com/ethereum/go-ethereum/consensus/misc"
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"github.com/ethereum/go-ethereum/core/state"
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"github.com/ethereum/go-ethereum/core/types"
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"github.com/ethereum/go-ethereum/params"
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set "gopkg.in/fatih/set.v0"
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)
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// Ethash proof-of-work protocol constants.
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var (
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blockReward *big.Int = big.NewInt(5e+18) // Block reward in wei for successfully mining a block
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maxUncles = 2 // Maximum number of uncles allowed in a single block
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)
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// Various error messages to mark blocks invalid. These should be private to
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// prevent engine specific errors from being referenced in the remainder of the
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// codebase, inherently breaking if the engine is swapped out. Please put common
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// error types into the consensus package.
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var (
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errInvalidChain = errors.New("invalid header chain")
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errLargeBlockTime = errors.New("timestamp too big")
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errZeroBlockTime = errors.New("timestamp equals parent's")
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errTooManyUncles = errors.New("too many uncles")
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errDuplicateUncle = errors.New("duplicate uncle")
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errUncleIsAncestor = errors.New("uncle is ancestor")
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errDanglingUncle = errors.New("uncle's parent is not ancestor")
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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("invalid proof-of-work")
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)
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// VerifyHeader checks whether a header conforms to the consensus rules of the
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// stock Ethereum ethash engine.
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func (ethash *Ethash) VerifyHeader(chain consensus.ChainReader, header *types.Header, seal bool) error {
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// If we're running a full engine faking, accept any input as valid
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if ethash.fakeFull {
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return nil
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}
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// Short circuit if the header is known, or it's parent not
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number := header.Number.Uint64()
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if chain.GetHeader(header.Hash(), number) != nil {
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return nil
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}
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parent := chain.GetHeader(header.ParentHash, number-1)
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if parent == nil {
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return consensus.ErrUnknownAncestor
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}
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// Sanity checks passed, do a proper verification
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return ethash.verifyHeader(chain, header, parent, false, seal)
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}
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// VerifyHeaders is similar to VerifyHeader, but verifies a batch of headers
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// concurrently. The method returns a quit channel to abort the operations and
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// a results channel to retrieve the async verifications.
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func (ethash *Ethash) VerifyHeaders(chain consensus.ChainReader, headers []*types.Header, seals []bool) (chan<- struct{}, <-chan error) {
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// If we're running a full engine faking, accept any input as valid
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if ethash.fakeFull {
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abort, results := make(chan struct{}), make(chan error, len(headers))
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for i := 0; i < len(headers); i++ {
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results <- nil
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}
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return abort, results
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}
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// Spawn as many workers as allowed threads
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workers := runtime.GOMAXPROCS(0)
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if len(headers) < workers {
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workers = len(headers)
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}
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// Create a task channel and spawn the verifiers
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type result struct {
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index int
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err error
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}
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inputs := make(chan int, workers)
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outputs := make(chan result, len(headers))
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var badblock uint64
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for i := 0; i < workers; i++ {
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go func() {
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for index := range inputs {
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// If we've found a bad block already before this, stop validating
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if bad := atomic.LoadUint64(&badblock); bad != 0 && bad <= headers[index].Number.Uint64() {
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outputs <- result{index: index, err: errInvalidChain}
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continue
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}
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// We need to look up the first parent
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var parent *types.Header
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if index == 0 {
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parent = chain.GetHeader(headers[0].ParentHash, headers[0].Number.Uint64()-1)
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} else if headers[index-1].Hash() == headers[index].ParentHash {
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parent = headers[index-1]
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}
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// Ensure the validation is useful and execute it
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var failure error
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switch {
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case chain.GetHeader(headers[index].Hash(), headers[index].Number.Uint64()-1) != nil:
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outputs <- result{index: index, err: nil}
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case parent == nil:
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failure = consensus.ErrUnknownAncestor
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outputs <- result{index: index, err: failure}
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default:
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failure = ethash.verifyHeader(chain, headers[index], parent, false, seals[index])
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outputs <- result{index: index, err: failure}
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}
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// If a validation failure occurred, mark subsequent blocks invalid
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if failure != nil {
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number := headers[index].Number.Uint64()
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if prev := atomic.LoadUint64(&badblock); prev == 0 || prev > number {
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// This two step atomic op isn't thread-safe in that `badblock` might end
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// up slightly higher than the block number of the first failure (if many
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// workers try to write at the same time), but it's fine as we're mostly
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// interested to avoid large useless work, we don't care about 1-2 extra
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// runs. Doing "full thread safety" would involve mutexes, which would be
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// a noticeable sync overhead on the fast spinning worker routines.
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atomic.StoreUint64(&badblock, number)
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}
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}
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}
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}()
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}
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// Feed item indices to the workers until done, sorting and feeding the results to the caller
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dones := make([]bool, len(headers))
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errors := make([]error, len(headers))
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abort := make(chan struct{})
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returns := make(chan error, len(headers))
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go func() {
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defer close(inputs)
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input, output := 0, 0
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for i := 0; i < len(headers)*2; i++ {
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var res result
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// If there are tasks left, push to workers
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if input < len(headers) {
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select {
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case inputs <- input:
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input++
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continue
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case <-abort:
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return
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case res = <-outputs:
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}
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} else {
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// Otherwise keep waiting for results
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select {
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case <-abort:
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return
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case res = <-outputs:
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}
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}
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// A result arrived, save and propagate if next
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dones[res.index], errors[res.index] = true, res.err
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for output < len(headers) && dones[output] {
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returns <- errors[output]
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output++
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}
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}
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}()
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return abort, returns
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}
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// VerifyUncles verifies that the given block's uncles conform to the consensus
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// rules of the stock Ethereum ethash engine.
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func (ethash *Ethash) VerifyUncles(chain consensus.ChainReader, block *types.Block) error {
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// If we're running a full engine faking, accept any input as valid
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if ethash.fakeFull {
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return nil
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}
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// Verify that there are at most 2 uncles included in this block
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if len(block.Uncles()) > maxUncles {
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return errTooManyUncles
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}
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// Gather the set of past uncles and ancestors
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uncles, ancestors := set.New(), make(map[common.Hash]*types.Header)
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number, parent := block.NumberU64()-1, block.ParentHash()
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for i := 0; i < 7; i++ {
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ancestor := chain.GetBlock(parent, number)
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if ancestor == nil {
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break
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}
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ancestors[ancestor.Hash()] = ancestor.Header()
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for _, uncle := range ancestor.Uncles() {
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uncles.Add(uncle.Hash())
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}
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parent, number = ancestor.ParentHash(), number-1
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}
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ancestors[block.Hash()] = block.Header()
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uncles.Add(block.Hash())
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// Verify each of the uncles that it's recent, but not an ancestor
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for _, uncle := range block.Uncles() {
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// Make sure every uncle is rewarded only once
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hash := uncle.Hash()
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if uncles.Has(hash) {
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return errDuplicateUncle
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}
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uncles.Add(hash)
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// Make sure the uncle has a valid ancestry
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if ancestors[hash] != nil {
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return errUncleIsAncestor
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}
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if ancestors[uncle.ParentHash] == nil || uncle.ParentHash == block.ParentHash() {
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return errDanglingUncle
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}
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if err := ethash.verifyHeader(chain, uncle, ancestors[uncle.ParentHash], true, true); err != nil {
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return err
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}
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}
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return nil
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}
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// verifyHeader checks whether a header conforms to the consensus rules of the
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// stock Ethereum ethash engine.
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//
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// See YP section 4.3.4. "Block Header Validity"
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func (ethash *Ethash) verifyHeader(chain consensus.ChainReader, header, parent *types.Header, uncle bool, seal bool) error {
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// Ensure that the header's extra-data section is of a reasonable size
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if uint64(len(header.Extra)) > params.MaximumExtraDataSize {
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return fmt.Errorf("extra-data too long: %d > %d", len(header.Extra), params.MaximumExtraDataSize)
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}
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// Verify the header's timestamp
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if uncle {
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if header.Time.Cmp(math.MaxBig256) > 0 {
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return errLargeBlockTime
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}
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} else {
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if header.Time.Cmp(big.NewInt(time.Now().Unix())) > 0 {
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return consensus.ErrFutureBlock
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}
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}
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if header.Time.Cmp(parent.Time) <= 0 {
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return errZeroBlockTime
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}
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// Verify the block's difficulty based in it's timestamp and parent's difficulty
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expected := CalcDifficulty(chain.Config(), header.Time.Uint64(), parent.Time.Uint64(), parent.Number, parent.Difficulty)
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if expected.Cmp(header.Difficulty) != 0 {
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return fmt.Errorf("invalid difficulty: have %v, want %v", header.Difficulty, expected)
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}
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// Verify that the gas limit remains within allowed bounds
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diff := new(big.Int).Set(parent.GasLimit)
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diff = diff.Sub(diff, header.GasLimit)
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diff.Abs(diff)
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limit := new(big.Int).Set(parent.GasLimit)
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limit = limit.Div(limit, params.GasLimitBoundDivisor)
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if diff.Cmp(limit) >= 0 || header.GasLimit.Cmp(params.MinGasLimit) < 0 {
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return fmt.Errorf("invalid gas limit: have %v, want %v += %v", header.GasLimit, parent.GasLimit, limit)
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}
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// Verify that the block number is parent's +1
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if diff := new(big.Int).Sub(header.Number, parent.Number); diff.Cmp(big.NewInt(1)) != 0 {
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return consensus.ErrInvalidNumber
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}
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// Verify the engine specific seal securing the block
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if seal {
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if err := ethash.VerifySeal(chain, header); err != nil {
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return err
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}
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}
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// If all checks passed, validate any special fields for hard forks
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if err := misc.VerifyDAOHeaderExtraData(chain.Config(), header); err != nil {
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return err
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}
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if err := misc.VerifyForkHashes(chain.Config(), header, uncle); err != nil {
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return err
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}
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return nil
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}
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// CalcDifficulty is the difficulty adjustment algorithm. It returns the difficulty
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// that a new block should have when created at time given the parent block's time
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// and difficulty.
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//
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// TODO (karalabe): Move the chain maker into this package and make this private!
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func CalcDifficulty(config *params.ChainConfig, time, parentTime uint64, parentNumber, parentDiff *big.Int) *big.Int {
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if config.IsHomestead(new(big.Int).Add(parentNumber, common.Big1)) {
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return calcDifficultyHomestead(time, parentTime, parentNumber, parentDiff)
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}
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return calcDifficultyFrontier(time, parentTime, parentNumber, parentDiff)
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}
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// Some weird constants to avoid constant memory allocs for them.
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var (
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expDiffPeriod = big.NewInt(100000)
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big10 = big.NewInt(10)
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bigMinus99 = big.NewInt(-99)
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)
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// calcDifficultyHomestead is the difficulty adjustment algorithm. It returns
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// the difficulty that a new block should have when created at time given the
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// parent block's time and difficulty. The calculation uses the Homestead rules.
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func calcDifficultyHomestead(time, parentTime uint64, parentNumber, parentDiff *big.Int) *big.Int {
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// https://github.com/ethereum/EIPs/blob/master/EIPS/eip-2.mediawiki
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// algorithm:
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// diff = (parent_diff +
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// (parent_diff / 2048 * max(1 - (block_timestamp - parent_timestamp) // 10, -99))
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// ) + 2^(periodCount - 2)
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bigTime := new(big.Int).SetUint64(time)
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bigParentTime := new(big.Int).SetUint64(parentTime)
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// holds intermediate values to make the algo easier to read & audit
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x := new(big.Int)
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y := new(big.Int)
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// 1 - (block_timestamp -parent_timestamp) // 10
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x.Sub(bigTime, bigParentTime)
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x.Div(x, big10)
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x.Sub(common.Big1, x)
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// max(1 - (block_timestamp - parent_timestamp) // 10, -99)))
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if x.Cmp(bigMinus99) < 0 {
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x.Set(bigMinus99)
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}
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// (parent_diff + parent_diff // 2048 * max(1 - (block_timestamp - parent_timestamp) // 10, -99))
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y.Div(parentDiff, params.DifficultyBoundDivisor)
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x.Mul(y, x)
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x.Add(parentDiff, x)
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// minimum difficulty can ever be (before exponential factor)
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if x.Cmp(params.MinimumDifficulty) < 0 {
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x.Set(params.MinimumDifficulty)
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}
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// for the exponential factor
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periodCount := new(big.Int).Add(parentNumber, common.Big1)
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periodCount.Div(periodCount, expDiffPeriod)
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// the exponential factor, commonly referred to as "the bomb"
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// diff = diff + 2^(periodCount - 2)
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if periodCount.Cmp(common.Big1) > 0 {
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y.Sub(periodCount, common.Big2)
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y.Exp(common.Big2, y, nil)
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x.Add(x, y)
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}
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return x
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}
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// calcDifficultyFrontier is the difficulty adjustment algorithm. It returns the
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// difficulty that a new block should have when created at time given the parent
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// block's time and difficulty. The calculation uses the Frontier rules.
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func calcDifficultyFrontier(time, parentTime uint64, parentNumber, parentDiff *big.Int) *big.Int {
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diff := new(big.Int)
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adjust := new(big.Int).Div(parentDiff, params.DifficultyBoundDivisor)
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bigTime := new(big.Int)
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bigParentTime := new(big.Int)
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bigTime.SetUint64(time)
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bigParentTime.SetUint64(parentTime)
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if bigTime.Sub(bigTime, bigParentTime).Cmp(params.DurationLimit) < 0 {
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diff.Add(parentDiff, adjust)
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} else {
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diff.Sub(parentDiff, adjust)
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}
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if diff.Cmp(params.MinimumDifficulty) < 0 {
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diff.Set(params.MinimumDifficulty)
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}
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periodCount := new(big.Int).Add(parentNumber, common.Big1)
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periodCount.Div(periodCount, expDiffPeriod)
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if periodCount.Cmp(common.Big1) > 0 {
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// diff = diff + 2^(periodCount - 2)
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expDiff := periodCount.Sub(periodCount, common.Big2)
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expDiff.Exp(common.Big2, expDiff, nil)
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diff.Add(diff, expDiff)
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diff = math.BigMax(diff, params.MinimumDifficulty)
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}
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return diff
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}
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// VerifySeal implements consensus.Engine, checking whether the given block satisfies
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// the PoW difficulty requirements.
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func (ethash *Ethash) VerifySeal(chain consensus.ChainReader, header *types.Header) error {
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// If we're running a fake PoW, accept any seal as valid
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if ethash.fakeMode {
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time.Sleep(ethash.fakeDelay)
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if ethash.fakeFail == header.Number.Uint64() {
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return errInvalidPoW
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}
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return nil
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}
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// If we're running a shared PoW, delegate verification to it
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if ethash.shared != nil {
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return ethash.shared.VerifySeal(chain, header)
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}
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// Sanity check that the block number is below the lookup table size (60M blocks)
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number := header.Number.Uint64()
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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 that we have a valid difficulty for the block
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if header.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 header
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cache := ethash.cache(number)
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size := datasetSize(number)
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if ethash.tester {
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size = 32 * 1024
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}
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digest, result := hashimotoLight(size, cache, header.HashNoNonce().Bytes(), header.Nonce.Uint64())
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if !bytes.Equal(header.MixDigest[:], digest) {
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return errInvalidMixDigest
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}
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target := new(big.Int).Div(maxUint256, header.Difficulty)
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if new(big.Int).SetBytes(result).Cmp(target) > 0 {
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return errInvalidPoW
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}
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return nil
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}
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// Prepare implements consensus.Engine, initializing the difficulty field of a
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// header to conform to the ethash protocol. The changes are done inline.
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func (ethash *Ethash) Prepare(chain consensus.ChainReader, header *types.Header) error {
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parent := chain.GetHeader(header.ParentHash, header.Number.Uint64()-1)
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if parent == nil {
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return consensus.ErrUnknownAncestor
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}
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header.Difficulty = CalcDifficulty(chain.Config(), header.Time.Uint64(),
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parent.Time.Uint64(), parent.Number, parent.Difficulty)
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return nil
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}
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// Finalize implements consensus.Engine, accumulating the block and uncle rewards,
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// setting the final state and assembling the block.
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func (ethash *Ethash) Finalize(chain consensus.ChainReader, header *types.Header, state *state.StateDB, txs []*types.Transaction, uncles []*types.Header, receipts []*types.Receipt) (*types.Block, error) {
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// Accumulate any block and uncle rewards and commit the final state root
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AccumulateRewards(state, header, uncles)
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header.Root = state.IntermediateRoot(chain.Config().IsEIP158(header.Number))
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// Header seems complete, assemble into a block and return
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return types.NewBlock(header, txs, uncles, receipts), nil
|
|
}
|
|
|
|
// Some weird constants to avoid constant memory allocs for them.
|
|
var (
|
|
big8 = big.NewInt(8)
|
|
big32 = big.NewInt(32)
|
|
)
|
|
|
|
// AccumulateRewards credits the coinbase of the given block with the mining
|
|
// reward. The total reward consists of the static block reward and rewards for
|
|
// included uncles. The coinbase of each uncle block is also rewarded.
|
|
//
|
|
// TODO (karalabe): Move the chain maker into this package and make this private!
|
|
func AccumulateRewards(state *state.StateDB, header *types.Header, uncles []*types.Header) {
|
|
reward := new(big.Int).Set(blockReward)
|
|
r := new(big.Int)
|
|
for _, uncle := range uncles {
|
|
r.Add(uncle.Number, big8)
|
|
r.Sub(r, header.Number)
|
|
r.Mul(r, blockReward)
|
|
r.Div(r, big8)
|
|
state.AddBalance(uncle.Coinbase, r)
|
|
|
|
r.Div(blockReward, big32)
|
|
reward.Add(reward, r)
|
|
}
|
|
state.AddBalance(header.Coinbase, reward)
|
|
}
|