all: simplify witness and integrate it into live geth

Author: karalabe

cmd/evm/blockrunner.go

@@ -86,7 +86,7 @@ func blockTestCmd(ctx *cli.Context) error {
 			continue
 		}
 		test := tests[name]
-		if err := test.Run(false, rawdb.HashScheme, tracer, func(res error, chain *core.BlockChain) {
+		if err := test.Run(false, rawdb.HashScheme, false, tracer, func(res error, chain *core.BlockChain) {
 			if ctx.Bool(DumpFlag.Name) {
 				if state, _ := chain.State(); state != nil {
 					fmt.Println(string(state.Dump(nil)))

cmd/utils/stateless/stateless.go

@@ -23,6 +23,7 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/consensus"
 	"github.com/ethereum/go-ethereum/core/state"
+	"github.com/ethereum/go-ethereum/core/stateless"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/trie"
@@ -35,14 +36,12 @@ import (
 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 {
+func NewBlockValidator(config *params.ChainConfig, blockchain *BlockChain) *BlockValidator {
 	validator := &BlockValidator{
 		config: config,
-		engine: engine,
 		bc:     blockchain,
 	}
 	return validator
@@ -60,7 +59,7 @@ func (v *BlockValidator) ValidateBody(block *types.Block) error {
 	// Header validity is known at this point. Here we verify that uncles, transactions
 	// and withdrawals given in the block body match the header.
 	header := block.Header()
-	if err := v.engine.VerifyUncles(v.bc, block); err != nil {
+	if err := v.bc.engine.VerifyUncles(v.bc, block); err != nil {
 		return err
 	}
 	if hash := types.CalcUncleHash(block.Uncles()); hash != header.UncleHash {
@@ -122,31 +121,55 @@ func (v *BlockValidator) ValidateBody(block *types.Block) error {
 
 // 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.
-// If validateRemoteRoot is false, the provided block header's root is not asserted to be equal to the one computed from
-// execution.
-func (v *BlockValidator) ValidateState(block *types.Block, statedb *state.StateDB, receipts types.Receipts, usedGas uint64, checkRemoteRoot bool) (root common.Hash, err error) {
+func (v *BlockValidator) ValidateState(block *types.Block, statedb *state.StateDB, receipts types.Receipts, usedGas uint64, stateless bool) error {
 	header := block.Header()
 	if block.GasUsed() != usedGas {
-		return root, fmt.Errorf("invalid gas used (remote: %d local: %d)", 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 root, fmt.Errorf("invalid bloom (remote: %x  local: %x)", header.Bloom, rbloom)
+		return fmt.Errorf("invalid bloom (remote: %x  local: %x)", header.Bloom, rbloom)
+	}
+	// In stateless mode, return early because the receipt and state root are not
+	// provided through the witness, rather the cross validator needs to return it.
+	if stateless {
+		return nil
 	}
 	// The receipt Trie's root (R = (Tr [[H1, R1], ... [Hn, Rn]]))
 	receiptSha := types.DeriveSha(receipts, trie.NewStackTrie(nil))
 	if receiptSha != header.ReceiptHash {
-		return root, fmt.Errorf("invalid receipt root hash (remote: %x local: %x)", header.ReceiptHash, receiptSha)
+		return fmt.Errorf("invalid receipt root hash (remote: %x local: %x)", header.ReceiptHash, receiptSha)
 	}
-	// Compute the state root and if enabled, check it against the
-	// received state root and throw an error if they don't match.
-	root = statedb.IntermediateRoot(v.config.IsEIP158(header.Number))
-	if checkRemoteRoot && header.Root != root {
-		return root, fmt.Errorf("invalid merkle root (remote: %x local: %x) dberr: %w", header.Root, root, statedb.Error())
+	// 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) dberr: %w", header.Root, root, statedb.Error())
 	}
-	return root, nil
+	return nil
+}
+
+// ValidateWitness cross validates a block execution with stateless remote clients.
+//
+// Normally we'd distribute the block witness to remote cross validators, wait
+// for them to respond and then merge the results. For now, however, it's only
+// Geth, so do an internal stateless run.
+func (v *BlockValidator) ValidateWitness(witness *stateless.Witness, receiptRoot common.Hash, stateRoot common.Hash) error {
+	// Run the cross client stateless execution
+	// TODO(karalabe): Self-stateless for now, swap with other clients
+	crossReceiptRoot, crossStateRoot, err := ExecuteStateless(v.config, witness)
+	if err != nil {
+		return fmt.Errorf("stateless execution failed: %v", err)
+	}
+	// Stateless cross execution suceeeded, validate the withheld computed fields
+	if crossReceiptRoot != receiptRoot {
+		return fmt.Errorf("cross validator receipt root mismatch (cross: %x local: %x)", crossReceiptRoot, receiptRoot)
+	}
+	if crossStateRoot != stateRoot {
+		return fmt.Errorf("cross validator state root mismatch (cross: %x local: %x)", crossStateRoot, stateRoot)
+	}
+	return nil
 }
 
 // CalcGasLimit computes the gas limit of the next block after parent. It aims

core/block_validator.go

@@ -37,6 +37,7 @@ import (
 	"github.com/ethereum/go-ethereum/core/rawdb"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/state/snapshot"
+	"github.com/ethereum/go-ethereum/core/stateless"
 	"github.com/ethereum/go-ethereum/core/tracing"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/core/vm"
@@ -302,18 +303,18 @@ func NewBlockChain(db ethdb.Database, cacheConfig *CacheConfig, genesis *Genesis
 		vmConfig:      vmConfig,
 		logger:        vmConfig.Tracer,
 	}
-	bc.flushInterval.Store(int64(cacheConfig.TrieTimeLimit))
-	bc.forker = NewForkChoice(bc, shouldPreserve)
-	bc.stateCache = state.NewDatabaseWithNodeDB(bc.db, bc.triedb)
-	bc.validator = NewBlockValidator(chainConfig, bc, engine)
-	bc.prefetcher = newStatePrefetcher(chainConfig, bc, engine)
-	bc.processor = NewStateProcessor(chainConfig, bc, engine)
-
 	var err error
 	bc.hc, err = NewHeaderChain(db, chainConfig, engine, bc.insertStopped)
 	if err != nil {
 		return nil, err
 	}
+	bc.flushInterval.Store(int64(cacheConfig.TrieTimeLimit))
+	bc.forker = NewForkChoice(bc, shouldPreserve)
+	bc.stateCache = state.NewDatabaseWithNodeDB(bc.db, bc.triedb)
+	bc.validator = NewBlockValidator(chainConfig, bc)
+	bc.prefetcher = newStatePrefetcher(chainConfig, bc.hc)
+	bc.processor = NewStateProcessor(chainConfig, bc.hc)
+
 	bc.genesisBlock = bc.GetBlockByNumber(0)
 	if bc.genesisBlock == nil {
 		return nil, ErrNoGenesis
@@ -1809,7 +1810,14 @@ func (bc *BlockChain) insertChain(chain types.Blocks, setHead bool) (int, error)
 		// while processing transactions. Before Byzantium the prefetcher is mostly
 		// useless due to the intermediate root hashing after each transaction.
 		if bc.chainConfig.IsByzantium(block.Number()) {
-			statedb.StartPrefetcher("chain", !bc.vmConfig.EnableWitnessCollection)
+			var witness *stateless.Witness
+			if bc.vmConfig.EnableWitnessCollection {
+				witness, err = stateless.NewWitness(bc, block)
+				if err != nil {
+					return it.index, err
+				}
+			}
+			statedb.StartPrefetcher("chain", witness)
 		}
 		activeState = statedb
 
@@ -1916,19 +1924,26 @@ func (bc *BlockChain) processBlock(block *types.Block, statedb *state.StateDB, s
 
 	// Process block using the parent state as reference point
 	pstart := time.Now()
-	receipts, logs, usedGas, err := bc.processor.Process(block, statedb, bc.vmConfig, nil)
+	receipts, logs, usedGas, err := bc.processor.Process(block, statedb, bc.vmConfig)
 	if err != nil {
 		bc.reportBlock(block, receipts, err)
 		return nil, err
 	}
 	ptime := time.Since(pstart)
 
 	vstart := time.Now()
-	if _, err := bc.validator.ValidateState(block, statedb, receipts, usedGas, true); err != nil {
+	if err := bc.validator.ValidateState(block, statedb, receipts, usedGas, false); err != nil {
 		bc.reportBlock(block, receipts, err)
 		return nil, err
 	}
 	vtime := time.Since(vstart)
+
+	if witness := statedb.Witness(); witness != nil {
+		if err = bc.validator.ValidateWitness(witness, block.ReceiptHash(), block.Root()); err != nil {
+			bc.reportBlock(block, receipts, err)
+			return nil, fmt.Errorf("cross verification failed: %v", err)
+		}
+	}
 	proctime := time.Since(start) // processing + validation
 
 	// Update the metrics touched during block processing and validation

core/blockchain.go

@@ -163,13 +163,12 @@ func testBlockChainImport(chain types.Blocks, blockchain *BlockChain) error {
 		if err != nil {
 			return err
 		}
-		receipts, _, usedGas, err := blockchain.processor.Process(block, statedb, vm.Config{}, nil)
+		receipts, _, usedGas, err := blockchain.processor.Process(block, statedb, vm.Config{})
 		if err != nil {
 			blockchain.reportBlock(block, receipts, err)
 			return err
 		}
-		_, err = blockchain.validator.ValidateState(block, statedb, receipts, usedGas, true)
-		if err != nil {
+		if err = blockchain.validator.ValidateState(block, statedb, receipts, usedGas, false); err != nil {
 			blockchain.reportBlock(block, receipts, err)
 			return err
 		}

core/blockchain_test.go

@@ -99,7 +99,7 @@ func (b *BlockGen) Difficulty() *big.Int {
 func (b *BlockGen) SetParentBeaconRoot(root common.Hash) {
 	b.header.ParentBeaconRoot = &root
 	var (
-		blockContext = NewEVMBlockContext(b.header, b.cm, &b.header.Coinbase, nil)
+		blockContext = NewEVMBlockContext(b.header, b.cm, &b.header.Coinbase)
 		vmenv        = vm.NewEVM(blockContext, vm.TxContext{}, b.statedb, b.cm.config, vm.Config{})
 	)
 	ProcessBeaconBlockRoot(root, vmenv, b.statedb)

core/chain_makers.go

@@ -19,8 +19,6 @@ package core
 import (
 	"math/big"
 
-	"github.com/ethereum/go-ethereum/core/state"
-
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/consensus"
 	"github.com/ethereum/go-ethereum/consensus/misc/eip4844"
@@ -40,9 +38,8 @@ type ChainContext interface {
 	GetHeader(common.Hash, uint64) *types.Header
 }
 
-// NewEVMBlockContext creates a new context for use in the EVM.  If witness is non-nil, the context sources block hashes
-// for the BLOCKHASH opcode from the witness.
-func NewEVMBlockContext(header *types.Header, chain ChainContext, author *common.Address, witness *state.Witness) vm.BlockContext {
+// NewEVMBlockContext creates a new context for use in the EVM.
+func NewEVMBlockContext(header *types.Header, chain ChainContext, author *common.Address) vm.BlockContext {
 	var (
 		beneficiary common.Address
 		baseFee     *big.Int
@@ -65,18 +62,10 @@ func NewEVMBlockContext(header *types.Header, chain ChainContext, author *common
 	if header.Difficulty.Sign() == 0 {
 		random = &header.MixDigest
 	}
-	var getHash vm.GetHashFunc
-	if witness != nil {
-		getHash = func(n uint64) common.Hash {
-			return witness.BlockHash(n)
-		}
-	} else {
-		getHash = GetHashFn(header, chain)
-	}
 	return vm.BlockContext{
 		CanTransfer: CanTransfer,
 		Transfer:    Transfer,
-		GetHash:     getHash,
+		GetHash:     GetHashFn(header, chain),
 		Coinbase:    beneficiary,
 		BlockNumber: new(big.Int).Set(header.Number),
 		Time:        header.Time,

core/evm.go

@@ -125,9 +125,9 @@ type Trie interface {
 	// be created with new root and updated trie database for following usage
 	Commit(collectLeaf bool) (common.Hash, *trienode.NodeSet)
 
-	// AccessList returns a map of path->blob containing all trie nodes that have
-	// been accessed.
-	AccessList() map[string][]byte
+	// Witness returns a set containing all trie nodes that have been accessed.
+	// The returned map could be nil if the witness is empty.
+	Witness() map[string]struct{}
 
 	// NodeIterator returns an iterator that returns nodes of the trie. Iteration
 	// starts at the key after the given start key. And error will be returned