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// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library 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. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package core
import (
"fmt"
"github.com/ethereum/go-ethereum/consensus"
"github.com/ethereum/go-ethereum/core/state"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/params"
)
// BlockValidator is responsible for validating block headers, uncles and
// processed state.
//
// BlockValidator implements Validator.
type BlockValidator struct {
config *params.ChainConfig // Chain configuration options
bc *BlockChain // Canonical block chain
engine consensus.Engine // Consensus engine used for validating
}
// NewBlockValidator returns a new block validator which is safe for re-use
func NewBlockValidator(config *params.ChainConfig, blockchain *BlockChain, engine consensus.Engine) *BlockValidator {
validator := &BlockValidator{
config: config,
engine: engine,
bc: blockchain,
}
return validator
}
// ValidateBody validates the given block's uncles and verifies the the block
// header's transaction and uncle roots. The headers are assumed to be already
// validated at this point.
func (v *BlockValidator) ValidateBody(block *types.Block) error {
// Check whether the block's known, and if not, that it's linkable
if v.bc.HasBlockAndState(block.Hash()) {
return ErrKnownBlock
}
if !v.bc.HasBlockAndState(block.ParentHash()) {
return consensus.ErrUnknownAncestor
}
// Header validity is known at this point, check the uncles and transactions
header := block.Header()
if err := v.engine.VerifyUncles(v.bc, block); err != nil {
return err
}
if hash := types.CalcUncleHash(block.Uncles()); hash != header.UncleHash {
return fmt.Errorf("uncle root hash mismatch: have %x, want %x", hash, header.UncleHash)
}
if hash := types.DeriveSha(block.Transactions()); hash != header.TxHash {
return fmt.Errorf("transaction root hash mismatch: have %x, want %x", hash, header.TxHash)
}
return nil
}
// ValidateState validates the various changes that happen after a state
// transition, such as amount of used gas, the receipt roots and the state root
// itself. ValidateState returns a database batch if the validation was a success
// otherwise nil and an error is returned.
func (v *BlockValidator) ValidateState(block, parent *types.Block, statedb *state.StateDB, receipts types.Receipts, usedGas uint64) error {
header := block.Header()
if block.GasUsed() != usedGas {
return fmt.Errorf("invalid gas used (remote: %d local: %d)", block.GasUsed(), usedGas)
}
// Validate the received block's bloom with the one derived from the generated receipts.
// For valid blocks this should always validate to true.
rbloom := types.CreateBloom(receipts)
if rbloom != header.Bloom {
return fmt.Errorf("invalid bloom (remote: %x local: %x)", header.Bloom, rbloom)
}
// Tre receipt Trie's root (R = (Tr [[H1, R1], ... [Hn, R1]]))
receiptSha := types.DeriveSha(receipts)
if receiptSha != header.ReceiptHash {
return fmt.Errorf("invalid receipt root hash (remote: %x local: %x)", header.ReceiptHash, receiptSha)
}
// Validate the state root against the received state root and throw
// an error if they don't match.
if root := statedb.IntermediateRoot(v.config.IsEIP158(header.Number)); header.Root != root {
return fmt.Errorf("invalid merkle root (remote: %x local: %x)", header.Root, root)
}
return nil
}
// CalcGasLimit computes the gas limit of the next block after parent.
// This is miner strategy, not consensus protocol.
func CalcGasLimit(parent *types.Block) uint64 {
// contrib = (parentGasUsed * 3 / 2) / 1024
contrib := (parent.GasUsed() + parent.GasUsed()/2) / params.GasLimitBoundDivisor
// decay = parentGasLimit / 1024 -1
decay := parent.GasLimit()/params.GasLimitBoundDivisor - 1
/*
strategy: gasLimit of block-to-mine is set based on parent's
gasUsed value. if parentGasUsed > parentGasLimit * (2/3) then we
increase it, otherwise lower it (or leave it unchanged if it's right
at that usage) the amount increased/decreased depends on how far away
from parentGasLimit * (2/3) parentGasUsed is.
*/
limit := parent.GasLimit() - decay + contrib
if limit < params.MinGasLimit {
limit = params.MinGasLimit
}
// however, if we're now below the target (TargetGasLimit) we increase the
// limit as much as we can (parentGasLimit / 1024 -1)
if limit < params.TargetGasLimit {
limit = parent.GasLimit() + decay
if limit > params.TargetGasLimit {
limit = params.TargetGasLimit
}
}
return limit
}
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