block_validator.go

// 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/common"
	// "github.com/ethereum/go-ethereum/common/math"
	"github.com/ethereum/go-ethereum/consensus"
	"github.com/ethereum/go-ethereum/consensus/dbft"
	"github.com/ethereum/go-ethereum/core/state"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/crypto/sha3"
	"github.com/ethereum/go-ethereum/log"	
	"github.com/ethereum/go-ethereum/params"
	"github.com/ethereum/go-ethereum/rlp"
)

// 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(), block.NumberU64()) {
		return ErrKnownBlock
	}
	if !v.bc.HasBlockAndState(block.ParentHash(), block.NumberU64()-1) {
		if !v.bc.HasBlock(block.ParentHash(), block.NumberU64()-1) {
			return consensus.ErrUnknownAncestor
		}
		return consensus.ErrPrunedAncestor
	}
	// 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)
	}

	if d, ok := v.engine.(*dbft.Dbft); ok {
		addrlist := v.bc.GetLastVote(block.NumberU64())
		var sigCount int
		checkReplica := make(map[uint64]int64)
		for _, sig := range block.GroupSignatures() {
			addr, err := PubKeyrecover(dbft.EliminateSigningField(header), sig.Sig)
			if err != nil {
				log.Error("Could not recover pubkey of signer", "err", err, "len", len(sig.Sig))
				return fmt.Errorf("Could not recover pubkey of signer")
			}
			if addr != addrlist[int(sig.IIndex)] {
				log.Error("Group Signature not from a miner", "addr", addr, "iIndex", sig.IIndex, "sig", sig.Sig)
				return fmt.Errorf("Group signature not from a miner.")
			}
			checkReplica[sig.IIndex] += 1
			sigCount += 1
		}
		// This logic can be simplified with a slice.
		for _, count := range checkReplica {
			if count != 1 {
				return fmt.Errorf("Replicated signatures exist.")
			}			
		}

		required := d.RequiredNodes(uint64(len(addrlist))) - 1 // We do not require the speaker signature
		if (sigCount < required) {
			log.Error("Not enough signers", "sigCount", sigCount, "required", d.RequiredNodes(uint64(len(addrlist))))
			return fmt.Errorf("Not enough signers to pass the groupSig validation")
		}
	}
	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
}

//dbft ***
// func EliminateSigningField(header *types.Header) *types.Header {
// 	unsignedHeader := types.CopyHeader(header)

// 	unsignedHeader.Extra = header.Extra[:32]
// 	unsignedHeader.Extra = append(unsignedHeader.Extra, make([]byte, 65)...)

// 	//unsignedHeader.Extra = header.Extra[:len(header.Extra)-65]
// 	unsignedHeader.MixDigest = types.EmptySigHash
// 	return unsignedHeader
// }

func FixedGasLimitForDBFT() uint64 {
	return params.GenesisGasLimit
}

func sigHash(header *types.Header) (hash common.Hash) {
	hasher := sha3.NewKeccak256()
	//fmt.Println("Extra length: ", len(header.Extra), "Check sighash: ", common.ToHex(header.Extra))
	rlp.Encode(hasher, []interface{}{
		header.ParentHash,
		header.UncleHash,
		header.Coinbase,
		header.Root,
		header.TxHash,
		header.ReceiptHash,
		header.Bloom,
		header.Difficulty,
		header.Number,
		header.GasLimit,
		header.GasUsed,
		header.Time,
		//header.Extra,
		header.Extra[:len(header.Extra)-types.SealLength],
		//header.MixDigest,
		header.Nonce,
	})
	hasher.Sum(hash[:0])
	return hash
}

func PubKeyrecover(header *types.Header, sig []byte) (common.Address, error) {
	// Recover the public key and the Ethereum address
	pubkey, err := crypto.Ecrecover(sigHash(header).Bytes(), sig)
	if err != nil {
		return common.Address{}, err
	}
	var signer common.Address
	copy(signer[:], crypto.Keccak256(pubkey[1:])[12:])

	return signer, nil
}