core, eth, rpc: split out block validator and state processor

This removes the burden on a single object to take care of all
validation and state processing. Now instead the validation is done by
the `core.BlockValidator` (`types.Validator`) that takes care of both
header and uncle validation through the `ValidateBlock` method and state
validation through the `ValidateState` method. The state processing is
done by a new object `core.StateProcessor` (`types.Processor`) and
accepts a new state as input and uses that to process the given block's
transactions (and uncles for rewords) to calculate the state root for
the next block (P_n + 1).

1 files changed, 243 insertions, 0 deletions

diff --git a/core/block_validator.go b/core/block_validator.go
new file mode 100644
index 000000000..62d096d02
--- /dev/null
+++ b/core/block_validator.go
@@ -0,0 +1,243 @@
+// Copyright 2014 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"
+	"math/big"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/state"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/logger/glog"
+	"github.com/ethereum/go-ethereum/params"
+	"github.com/ethereum/go-ethereum/pow"
+	"gopkg.in/fatih/set.v0"
+)
+
+// BlockValidator is responsible for validating block headers, uncles and
+// processed state.
+//
+// BlockValidator implements Validator.
+type BlockValidator struct {
+	bc  *BlockChain // Canonical block chain
+	Pow pow.PoW     // Proof of work used for validating
+}
+
+// NewBlockValidator returns a new block validator which is safe for re-use
+func NewBlockValidator(blockchain *BlockChain, pow pow.PoW) *BlockValidator {
+	validator := &BlockValidator{
+		Pow: pow,
+		bc:  blockchain,
+	}
+	return validator
+}
+
+// ValidateBlock validates the given block's header and uncles and verifies the
+// the block header's transaction and uncle roots.
+//
+// ValidateBlock does not validate the header's pow. The pow work validated
+// seperately so we can process them in paralel.
+//
+// ValidateBlock also validates and makes sure that any previous state (or present)
+// state that might or might not be present is checked to make sure that fast
+// sync has done it's job proper. This prevents the block validator form accepting
+// false positives where a header is present but the state is not.
+func (v *BlockValidator) ValidateBlock(block *types.Block) error {
+	if v.bc.HasBlock(block.Hash()) {
+		if _, err := state.New(block.Root(), v.bc.chainDb); err == nil {
+			return &KnownBlockError{block.Number(), block.Hash()}
+		}
+	}
+	parent := v.bc.GetBlock(block.ParentHash())
+	if parent == nil {
+		return ParentError(block.ParentHash())
+	}
+	if _, err := state.New(parent.Root(), v.bc.chainDb); err != nil {
+		return ParentError(block.ParentHash())
+	}
+
+	header := block.Header()
+	// validate the block header
+	if err := ValidateHeader(v.Pow, header, parent.Header(), false, false); err != nil {
+		return err
+	}
+	// verify the uncles are correctly rewarded
+	if err := v.VerifyUncles(block, parent); err != nil {
+		return err
+	}
+
+	// Verify UncleHash before running other uncle validations
+	unclesSha := types.CalcUncleHash(block.Uncles())
+	if unclesSha != header.UncleHash {
+		return fmt.Errorf("invalid uncles root hash. received=%x calculated=%x", header.UncleHash, unclesSha)
+	}
+
+	// The transactions Trie's root (R = (Tr [[i, RLP(T1)], [i, RLP(T2)], ... [n, RLP(Tn)]]))
+	// can be used by light clients to make sure they've received the correct Txs
+	txSha := types.DeriveSha(block.Transactions())
+	if txSha != header.TxHash {
+		return fmt.Errorf("invalid transaction root hash. received=%x calculated=%x", header.TxHash, txSha)
+	}
+
+	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 succes
+// otherwise nil and an error is returned.
+func (v *BlockValidator) ValidateState(block, parent *types.Block, statedb *state.StateDB, receipts types.Receipts, usedGas *big.Int) (err error) {
+	header := block.Header()
+	if block.GasUsed().Cmp(usedGas) != 0 {
+		return ValidationError(fmt.Sprintf("gas used error (%v / %v)", 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("unable to replicate block's bloom=%x", 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. received=%x calculated=%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(); header.Root != root {
+		return fmt.Errorf("invalid merkle root: header=%x computed=%x", header.Root, root)
+	}
+	return nil
+}
+
+// VerifyUncles verifies the given block's uncles and applies the Ethereum
+// consensus rules to the various block headers included; it will return an
+// error if any of the included uncle headers were invalid. It returns an error
+// if the validation failed.
+func (v *BlockValidator) VerifyUncles(block, parent *types.Block) error {
+	// validate that there at most 2 uncles included in this block
+	if len(block.Uncles()) > 2 {
+		return ValidationError("Block can only contain maximum 2 uncles (contained %v)", len(block.Uncles()))
+	}
+
+	uncles := set.New()
+	ancestors := make(map[common.Hash]*types.Block)
+	for _, ancestor := range v.bc.GetBlocksFromHash(block.ParentHash(), 7) {
+		ancestors[ancestor.Hash()] = ancestor
+		// Include ancestors uncles in the uncle set. Uncles must be unique.
+		for _, uncle := range ancestor.Uncles() {
+			uncles.Add(uncle.Hash())
+		}
+	}
+	ancestors[block.Hash()] = block
+	uncles.Add(block.Hash())
+
+	for i, uncle := range block.Uncles() {
+		hash := uncle.Hash()
+		if uncles.Has(hash) {
+			// Error not unique
+			return UncleError("uncle[%d](%x) not unique", i, hash[:4])
+		}
+		uncles.Add(hash)
+
+		if ancestors[hash] != nil {
+			branch := fmt.Sprintf("  O - %x\n  |\n", block.Hash())
+			for h := range ancestors {
+				branch += fmt.Sprintf("  O - %x\n  |\n", h)
+			}
+			glog.Infoln(branch)
+			return UncleError("uncle[%d](%x) is ancestor", i, hash[:4])
+		}
+
+		if ancestors[uncle.ParentHash] == nil || uncle.ParentHash == parent.Hash() {
+			return UncleError("uncle[%d](%x)'s parent is not ancestor (%x)", i, hash[:4], uncle.ParentHash[0:4])
+		}
+
+		if err := ValidateHeader(v.Pow, uncle, ancestors[uncle.ParentHash].Header(), true, true); err != nil {
+			return ValidationError(fmt.Sprintf("uncle[%d](%x) header invalid: %v", i, hash[:4], err))
+		}
+	}
+
+	return nil
+}
+
+// ValidateHeader validates the given header and, depending on the pow arg,
+// checks the proof of work of the given header. Returns an error if the
+// validation failed.
+func (v *BlockValidator) ValidateHeader(header, parent *types.Header, checkPow bool) error {
+	// Short circuit if the parent is missing.
+	if parent == nil {
+		return ParentError(header.ParentHash)
+	}
+	// Short circuit if the header's already known or its parent missing
+	if v.bc.HasHeader(header.Hash()) {
+		return nil
+	}
+	return ValidateHeader(v.Pow, header, parent, checkPow, false)
+}
+
+// Validates a header. Returns an error if the header is invalid.
+//
+// See YP section 4.3.4. "Block Header Validity"
+func ValidateHeader(pow pow.PoW, header *types.Header, parent *types.Header, checkPow, uncle bool) error {
+	if big.NewInt(int64(len(header.Extra))).Cmp(params.MaximumExtraDataSize) == 1 {
+		return fmt.Errorf("Header extra data too long (%d)", len(header.Extra))
+	}
+
+	if uncle {
+		if header.Time.Cmp(common.MaxBig) == 1 {
+			return BlockTSTooBigErr
+		}
+	} else {
+		if header.Time.Cmp(big.NewInt(time.Now().Unix())) == 1 {
+			return BlockFutureErr
+		}
+	}
+	if header.Time.Cmp(parent.Time) != 1 {
+		return BlockEqualTSErr
+	}
+
+	expd := CalcDifficulty(header.Time.Uint64(), parent.Time.Uint64(), parent.Number, parent.Difficulty)
+	if expd.Cmp(header.Difficulty) != 0 {
+		return fmt.Errorf("Difficulty check failed for header %v, %v", header.Difficulty, expd)
+	}
+
+	a := new(big.Int).Set(parent.GasLimit)
+	a = a.Sub(a, header.GasLimit)
+	a.Abs(a)
+	b := new(big.Int).Set(parent.GasLimit)
+	b = b.Div(b, params.GasLimitBoundDivisor)
+	if !(a.Cmp(b) < 0) || (header.GasLimit.Cmp(params.MinGasLimit) == -1) {
+		return fmt.Errorf("GasLimit check failed for header %v (%v > %v)", header.GasLimit, a, b)
+	}
+
+	num := new(big.Int).Set(parent.Number)
+	num.Sub(header.Number, num)
+	if num.Cmp(big.NewInt(1)) != 0 {
+		return BlockNumberErr
+	}
+
+	if checkPow {
+		// Verify the nonce of the header. Return an error if it's not valid
+		if !pow.Verify(types.NewBlockWithHeader(header)) {
+			return &BlockNonceErr{header.Number, header.Hash(), header.Nonce.Uint64()}
+		}
+	}
+	return nil
+}