consensus, eth/catalyst: remove TD checks and enforcement

consensus/beacon/consensus.go

@@ -83,19 +83,35 @@ func (beacon *Beacon) Author(header *types.Header) (common.Address, error) {
 // VerifyHeader checks whether a header conforms to the consensus rules of the
 // stock Ethereum consensus engine.
 func (beacon *Beacon) VerifyHeader(chain consensus.ChainHeaderReader, header *types.Header) error {
-	reached, err := IsTTDReached(chain, header.ParentHash, header.Number.Uint64()-1)
+	// During the live merge transision, the consensus engine used the terminal
-	if err != nil {
+	// total difficulty to detect when PoW (PoA) switched to PoS. Maintainig the
-		return err
+	// total difficulty values however require applying all the blocks from the
-	}
+	// genesis to build up the TD. This stops being a possibility if the tail of
-	if !reached {
+	// the chain is pruned already during sync.
-		return beacon.ethone.VerifyHeader(chain, header)
+	//
-	}
+	// One heuristic that can be used to distinguis pre-merge and post-merge
-	// Short circuit if the parent is not known
+	// blocks is whether their *difficulty* is >0 or ==0 respectively. This of
+	// course would mean that we cannot prove anymore for a past chain that it
+	// truly transisioned at the correct TTD, but if we consider that ancient
+	// point in time finalized a long time ago, there should be no attempt from
+	// the consensus client to rewrite very old history.
+	//
+	// One thing that's probably not needed but which we can add to make this
+	// verification even stricter is to enforce that the chain can switch from
+	// >0 to ==0 TD only once by forbidding an ==0 to be followed by a >0.
+
+	// Verify that we're not reverting to pre-merge from post-merge
 	parent := chain.GetHeader(header.ParentHash, header.Number.Uint64()-1)
 	if parent == nil {
 		return consensus.ErrUnknownAncestor
 	}
-	// Sanity checks passed, do a proper verification
+	if parent.Difficulty.Sign() == 0 && header.Difficulty.Sign() > 0 {
+		return consensus.ErrInvalidTerminalBlock
+	}
+	// Check >0 TDs with pre-merge, --0 TDs with post-merge rules
+	if header.Difficulty.Sign() > 0 {
+		return beacon.ethone.VerifyHeader(chain, header)
+	}
 	return beacon.verifyHeader(chain, header, parent)
 }
 

eth/catalyst/api.go

@@ -361,21 +361,12 @@ func (api *ConsensusAPI) forkchoiceUpdated(update engine.ForkchoiceStateV1, payl
 	}
 	// Block is known locally, just sanity check that the beacon client does not
 	// attempt to push us back to before the merge.
-	if block.Difficulty().BitLen() > 0 || block.NumberU64() == 0 {
+	if block.Difficulty().BitLen() > 0 && block.NumberU64() > 0 {
-		var (
+		ph := api.eth.BlockChain().GetHeader(block.ParentHash(), block.NumberU64()-1)
-			td  = api.eth.BlockChain().GetTd(update.HeadBlockHash, block.NumberU64())
+		if ph == nil {
-			ptd = api.eth.BlockChain().GetTd(block.ParentHash(), block.NumberU64()-1)
+			return engine.STATUS_INVALID, errors.New("parent unavailable for difficulty check")
-			ttd = api.eth.BlockChain().Config().TerminalTotalDifficulty
-		)
-		if td == nil || (block.NumberU64() > 0 && ptd == nil) {
-			log.Error("TDs unavailable for TTD check", "number", block.NumberU64(), "hash", update.HeadBlockHash, "td", td, "parent", block.ParentHash(), "ptd", ptd)
-			return engine.STATUS_INVALID, errors.New("TDs unavailable for TDD check")
 		}
-		if td.Cmp(ttd) < 0 {
+		if ph.Difficulty.Sign() == 0 && block.Difficulty().Sign() > 0 {
-			log.Error("Refusing beacon update to pre-merge", "number", block.NumberU64(), "hash", update.HeadBlockHash, "diff", block.Difficulty(), "age", common.PrettyAge(time.Unix(int64(block.Time()), 0)))
-			return engine.ForkChoiceResponse{PayloadStatus: engine.INVALID_TERMINAL_BLOCK, PayloadID: nil}, nil
-		}
-		if block.NumberU64() > 0 && ptd.Cmp(ttd) >= 0 {
 			log.Error("Parent block is already post-ttd", "number", block.NumberU64(), "hash", update.HeadBlockHash, "diff", block.Difficulty(), "age", common.PrettyAge(time.Unix(int64(block.Time()), 0)))
 			return engine.ForkChoiceResponse{PayloadStatus: engine.INVALID_TERMINAL_BLOCK, PayloadID: nil}, nil
 		}
@@ -901,21 +892,6 @@ func (api *ConsensusAPI) newPayload(params engine.ExecutableData, versionedHashe
 	if parent == nil {
 		return api.delayPayloadImport(block), nil
 	}
-	// We have an existing parent, do some sanity checks to avoid the beacon client
-	// triggering too early
-	var (
-		ptd  = api.eth.BlockChain().GetTd(parent.Hash(), parent.NumberU64())
-		ttd  = api.eth.BlockChain().Config().TerminalTotalDifficulty
-		gptd = api.eth.BlockChain().GetTd(parent.ParentHash(), parent.NumberU64()-1)
-	)
-	if ptd.Cmp(ttd) < 0 {
-		log.Warn("Ignoring pre-merge payload", "number", params.Number, "hash", params.BlockHash, "td", ptd, "ttd", ttd)
-		return engine.INVALID_TERMINAL_BLOCK, nil
-	}
-	if parent.Difficulty().BitLen() > 0 && gptd != nil && gptd.Cmp(ttd) >= 0 {
-		log.Error("Ignoring pre-merge parent block", "number", params.Number, "hash", params.BlockHash, "td", ptd, "ttd", ttd)
-		return engine.INVALID_TERMINAL_BLOCK, nil
-	}
 	if block.Time() <= parent.Time() {
 		log.Warn("Invalid timestamp", "parent", block.Time(), "block", block.Time())
 		return api.invalid(errors.New("invalid timestamp"), parent.Header()), nil

eth/catalyst/api_test.go

@@ -164,24 +164,6 @@ func TestEth2AssembleBlockWithAnotherBlocksTxs(t *testing.T) {
 	}
 }
 
-func TestSetHeadBeforeTotalDifficulty(t *testing.T) {
-	genesis, blocks := generateMergeChain(10, false)
-	n, ethservice := startEthService(t, genesis, blocks)
-	defer n.Close()
-
-	api := NewConsensusAPI(ethservice)
-	fcState := engine.ForkchoiceStateV1{
-		HeadBlockHash:      blocks[5].Hash(),
-		SafeBlockHash:      common.Hash{},
-		FinalizedBlockHash: common.Hash{},
-	}
-	if resp, err := api.ForkchoiceUpdatedV1(fcState, nil); err != nil {
-		t.Errorf("fork choice updated should not error: %v", err)
-	} else if resp.PayloadStatus.Status != engine.INVALID_TERMINAL_BLOCK.Status {
-		t.Errorf("fork choice updated before total terminal difficulty should be INVALID")
-	}
-}
-
 func TestEth2PrepareAndGetPayload(t *testing.T) {
 	genesis, blocks := generateMergeChain(10, false)
 	// We need to properly set the terminal total difficulty
@@ -902,70 +884,6 @@ func TestInvalidBloom(t *testing.T) {
 	}
 }
 
-func TestNewPayloadOnInvalidTerminalBlock(t *testing.T) {
-	genesis, preMergeBlocks := generateMergeChain(100, false)
-	n, ethservice := startEthService(t, genesis, preMergeBlocks)
-	defer n.Close()
-	api := NewConsensusAPI(ethservice)
-
-	// Test parent already post TTD in FCU
-	parent := preMergeBlocks[len(preMergeBlocks)-2]
-	fcState := engine.ForkchoiceStateV1{
-		HeadBlockHash:      parent.Hash(),
-		SafeBlockHash:      common.Hash{},
-		FinalizedBlockHash: common.Hash{},
-	}
-	resp, err := api.ForkchoiceUpdatedV1(fcState, nil)
-	if err != nil {
-		t.Fatalf("error sending forkchoice, err=%v", err)
-	}
-	if resp.PayloadStatus != engine.INVALID_TERMINAL_BLOCK {
-		t.Fatalf("error sending invalid forkchoice, invalid status: %v", resp.PayloadStatus.Status)
-	}
-
-	// Test parent already post TTD in NewPayload
-	args := &miner.BuildPayloadArgs{
-		Parent:       parent.Hash(),
-		Timestamp:    parent.Time() + 1,
-		Random:       crypto.Keccak256Hash([]byte{byte(1)}),
-		FeeRecipient: parent.Coinbase(),
-	}
-	payload, err := api.eth.Miner().BuildPayload(args, false)
-	if err != nil {
-		t.Fatalf("error preparing payload, err=%v", err)
-	}
-	data := *payload.Resolve().ExecutionPayload
-	// We need to recompute the blockhash, since the miner computes a wrong (correct) blockhash
-	txs, _ := decodeTransactions(data.Transactions)
-	header := &types.Header{
-		ParentHash:  data.ParentHash,
-		UncleHash:   types.EmptyUncleHash,
-		Coinbase:    data.FeeRecipient,
-		Root:        data.StateRoot,
-		TxHash:      types.DeriveSha(types.Transactions(txs), trie.NewStackTrie(nil)),
-		ReceiptHash: data.ReceiptsRoot,
-		Bloom:       types.BytesToBloom(data.LogsBloom),
-		Difficulty:  common.Big0,
-		Number:      new(big.Int).SetUint64(data.Number),
-		GasLimit:    data.GasLimit,
-		GasUsed:     data.GasUsed,
-		Time:        data.Timestamp,
-		BaseFee:     data.BaseFeePerGas,
-		Extra:       data.ExtraData,
-		MixDigest:   data.Random,
-	}
-	block := types.NewBlockWithHeader(header).WithBody(types.Body{Transactions: txs})
-	data.BlockHash = block.Hash()
-	// Send the new payload
-	resp2, err := api.NewPayloadV1(data)
-	if err != nil {
-		t.Fatalf("error sending NewPayload, err=%v", err)
-	}
-	if resp2 != engine.INVALID_TERMINAL_BLOCK {
-		t.Fatalf("error sending invalid forkchoice, invalid status: %v", resp.PayloadStatus.Status)
-	}
-}
-
 // TestSimultaneousNewBlock does several parallel inserts, both as
 // newPayLoad and forkchoiceUpdate. This is to test that the api behaves
 // well even of the caller is not being 'serial'.

ethstats/ethstats.go

@@ -65,7 +65,6 @@ type backend interface {
 	SubscribeNewTxsEvent(ch chan<- core.NewTxsEvent) event.Subscription
 	CurrentHeader() *types.Header
 	HeaderByNumber(ctx context.Context, number rpc.BlockNumber) (*types.Header, error)
-	GetTd(ctx context.Context, hash common.Hash) *big.Int
 	Stats() (pending int, queued int)
 	SyncProgress() ethereum.SyncProgress
 }
@@ -628,7 +627,6 @@ func (s *Service) reportBlock(conn *connWrapper, header *types.Header) error {
 func (s *Service) assembleBlockStats(header *types.Header) *blockStats {
 	// Gather the block infos from the local blockchain
 	var (
-		td     *big.Int
 		txs    []txStats
 		uncles []*types.Header
 	)
@@ -644,8 +642,6 @@ func (s *Service) assembleBlockStats(header *types.Header) *blockStats {
 		if block == nil {
 			return nil
 		}
-		td = fullBackend.GetTd(context.Background(), header.Hash())
-
 		txs = make([]txStats, len(block.Transactions()))
 		for i, tx := range block.Transactions() {
 			txs[i].Hash = tx.Hash()
@@ -656,7 +652,6 @@ func (s *Service) assembleBlockStats(header *types.Header) *blockStats {
 		if header == nil {
 			header = s.backend.CurrentHeader()
 		}
-		td = s.backend.GetTd(context.Background(), header.Hash())
 		txs = []txStats{}
 	}
 	// Assemble and return the block stats
@@ -671,7 +666,7 @@ func (s *Service) assembleBlockStats(header *types.Header) *blockStats {
 		GasUsed:    header.GasUsed,
 		GasLimit:   header.GasLimit,
 		Diff:       header.Difficulty.String(),
-		TotalDiff:  td.String(),
+		TotalDiff:  "0", // unknown post-merge with pruned chain tail
 		Txs:        txs,
 		TxHash:     header.TxHash,
 		Root:       header.Root,