fix(baseapp): select txs correctly with no-op mempool (backport cosmo…

…s#17769) (cosmos#17848)

Co-authored-by: Aleksandr Bezobchuk <[email protected]>
Co-authored-by: Aleksandr Bezobchuk <[email protected]>

CHANGELOG.md

@@ -43,6 +43,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### Bug Fixes
 
+* (baseapp) [#17769](https://github.com/cosmos/cosmos-sdk/pull/17769) Ensure we respect block size constraints in the `DefaultProposalHandler`'s `PrepareProposal` handler when a nil or no-op mempool is used. We provide a `TxSelector` type to assist in making transaction selection generalized. We also fix a comparison bug in tx selection when `req.maxTxBytes` is reached.
 * (config) [#17649](https://github.com/cosmos/cosmos-sdk/pull/17649) Fix `mempool.max-txs` configuration is invalid in `app.config`.
 * (mempool) [#17668](https://github.com/cosmos/cosmos-sdk/pull/17668) Fix `PriorityNonceIterator.Next()` nil pointer ref for min priority at the end of iteration.
 

baseapp/abci_utils.go

@@ -0,0 +1,256 @@
+package baseapp
+
+import (
+	"github.com/cockroachdb/errors"
+	abci "github.com/cometbft/cometbft/abci/types"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/types/mempool"
+)
+
+type (
+	// GasTx defines the contract that a transaction with a gas limit must implement.
+	GasTx interface {
+		GetGas() uint64
+	}
+
+	// ProposalTxVerifier defines the interface that is implemented by BaseApp,
+	// that any custom ABCI PrepareProposal and ProcessProposal handler can use
+	// to verify a transaction.
+	ProposalTxVerifier interface {
+		PrepareProposalVerifyTx(tx sdk.Tx) ([]byte, error)
+		ProcessProposalVerifyTx(txBz []byte) (sdk.Tx, error)
+	}
+
+	// DefaultProposalHandler defines the default ABCI PrepareProposal and
+	// ProcessProposal handlers.
+	DefaultProposalHandler struct {
+		mempool    mempool.Mempool
+		txVerifier ProposalTxVerifier
+		txSelector TxSelector
+	}
+)
+
+func NewDefaultProposalHandler(mp mempool.Mempool, txVerifier ProposalTxVerifier) *DefaultProposalHandler {
+	return &DefaultProposalHandler{
+		mempool:    mp,
+		txVerifier: txVerifier,
+		txSelector: NewDefaultTxSelector(),
+	}
+}
+
+// SetTxSelector sets the TxSelector function on the DefaultProposalHandler.
+func (h *DefaultProposalHandler) SetTxSelector(ts TxSelector) {
+	h.txSelector = ts
+}
+
+// PrepareProposalHandler returns the default implementation for processing an
+// ABCI proposal. The application's mempool is enumerated and all valid
+// transactions are added to the proposal. Transactions are valid if they:
+//
+// 1) Successfully encode to bytes.
+// 2) Are valid (i.e. pass runTx, AnteHandler only).
+//
+// Enumeration is halted once RequestPrepareProposal.MaxBytes of transactions is
+// reached or the mempool is exhausted.
+//
+// Note:
+//
+// - Step (2) is identical to the validation step performed in
+// DefaultProcessProposal. It is very important that the same validation logic
+// is used in both steps, and applications must ensure that this is the case in
+// non-default handlers.
+//
+// - If no mempool is set or if the mempool is a no-op mempool, the transactions
+// requested from CometBFT will simply be returned, which, by default, are in
+// FIFO order.
+func (h *DefaultProposalHandler) PrepareProposalHandler() sdk.PrepareProposalHandler {
+	return func(ctx sdk.Context, req abci.RequestPrepareProposal) abci.ResponsePrepareProposal {
+		var maxBlockGas uint64
+		if b := ctx.ConsensusParams().Block; b != nil {
+			maxBlockGas = uint64(b.MaxGas)
+		}
+
+		defer h.txSelector.Clear()
+
+		// If the mempool is nil or NoOp we simply return the transactions
+		// requested from CometBFT, which, by default, should be in FIFO order.
+		//
+		// Note, we still need to ensure the transactions returned respect req.MaxTxBytes.
+		_, isNoOp := h.mempool.(mempool.NoOpMempool)
+		if h.mempool == nil || isNoOp {
+			for _, txBz := range req.Txs {
+				// XXX: We pass nil as the memTx because we have no way of decoding the
+				// txBz. We'd need to break (update) the ProposalTxVerifier interface.
+				// As a result, we CANNOT account for block max gas.
+				stop := h.txSelector.SelectTxForProposal(uint64(req.MaxTxBytes), maxBlockGas, nil, txBz)
+				if stop {
+					break
+				}
+			}
+
+			return abci.ResponsePrepareProposal{Txs: h.txSelector.SelectedTxs()}
+		}
+
+		iterator := h.mempool.Select(ctx, req.Txs)
+		for iterator != nil {
+			memTx := iterator.Tx()
+
+			// NOTE: Since transaction verification was already executed in CheckTx,
+			// which calls mempool.Insert, in theory everything in the pool should be
+			// valid. But some mempool implementations may insert invalid txs, so we
+			// check again.
+			txBz, err := h.txVerifier.PrepareProposalVerifyTx(memTx)
+			if err != nil {
+				err := h.mempool.Remove(memTx)
+				if err != nil && !errors.Is(err, mempool.ErrTxNotFound) {
+					panic(err)
+				}
+			} else {
+				stop := h.txSelector.SelectTxForProposal(uint64(req.MaxTxBytes), maxBlockGas, memTx, txBz)
+				if stop {
+					break
+				}
+			}
+
+			iterator = iterator.Next()
+		}
+
+		return abci.ResponsePrepareProposal{Txs: h.txSelector.SelectedTxs()}
+	}
+}
+
+// ProcessProposalHandler returns the default implementation for processing an
+// ABCI proposal. Every transaction in the proposal must pass 2 conditions:
+//
+// 1. The transaction bytes must decode to a valid transaction.
+// 2. The transaction must be valid (i.e. pass runTx, AnteHandler only)
+//
+// If any transaction fails to pass either condition, the proposal is rejected.
+// Note that step (2) is identical to the validation step performed in
+// DefaultPrepareProposal. It is very important that the same validation logic
+// is used in both steps, and applications must ensure that this is the case in
+// non-default handlers.
+func (h *DefaultProposalHandler) ProcessProposalHandler() sdk.ProcessProposalHandler {
+	// If the mempool is nil or NoOp we simply return ACCEPT,
+	// because PrepareProposal may have included txs that could fail verification.
+	_, isNoOp := h.mempool.(mempool.NoOpMempool)
+	if h.mempool == nil || isNoOp {
+		return NoOpProcessProposal()
+	}
+
+	return func(ctx sdk.Context, req abci.RequestProcessProposal) abci.ResponseProcessProposal {
+		var totalTxGas uint64
+
+		var maxBlockGas int64
+		if b := ctx.ConsensusParams().Block; b != nil {
+			maxBlockGas = b.MaxGas
+		}
+
+		for _, txBytes := range req.Txs {
+			tx, err := h.txVerifier.ProcessProposalVerifyTx(txBytes)
+			if err != nil {
+				return abci.ResponseProcessProposal{Status: abci.ResponseProcessProposal_REJECT}
+			}
+
+			if maxBlockGas > 0 {
+				gasTx, ok := tx.(GasTx)
+				if ok {
+					totalTxGas += gasTx.GetGas()
+				}
+
+				if totalTxGas > uint64(maxBlockGas) {
+					return abci.ResponseProcessProposal{Status: abci.ResponseProcessProposal_REJECT}
+				}
+			}
+		}
+
+		return abci.ResponseProcessProposal{Status: abci.ResponseProcessProposal_ACCEPT}
+	}
+}
+
+// NoOpPrepareProposal defines a no-op PrepareProposal handler. It will always
+// return the transactions sent by the client's request.
+func NoOpPrepareProposal() sdk.PrepareProposalHandler {
+	return func(_ sdk.Context, req abci.RequestPrepareProposal) abci.ResponsePrepareProposal {
+		return abci.ResponsePrepareProposal{Txs: req.Txs}
+	}
+}
+
+// NoOpProcessProposal defines a no-op ProcessProposal Handler. It will always
+// return ACCEPT.
+func NoOpProcessProposal() sdk.ProcessProposalHandler {
+	return func(_ sdk.Context, _ abci.RequestProcessProposal) abci.ResponseProcessProposal {
+		return abci.ResponseProcessProposal{Status: abci.ResponseProcessProposal_ACCEPT}
+	}
+}
+
+// TxSelector defines a helper type that assists in selecting transactions during
+// mempool transaction selection in PrepareProposal. It keeps track of the total
+// number of bytes and total gas of the selected transactions. It also keeps
+// track of the selected transactions themselves.
+type TxSelector interface {
+	// SelectedTxs should return a copy of the selected transactions.
+	SelectedTxs() [][]byte
+
+	// Clear should clear the TxSelector, nulling out all relevant fields.
+	Clear()
+
+	// SelectTxForProposal should attempt to select a transaction for inclusion in
+	// a proposal based on inclusion criteria defined by the TxSelector. It must
+	// return <true> if the caller should halt the transaction selection loop
+	// (typically over a mempool) or <false> otherwise.
+	SelectTxForProposal(maxTxBytes, maxBlockGas uint64, memTx sdk.Tx, txBz []byte) bool
+}
+
+type defaultTxSelector struct {
+	totalTxBytes uint64
+	totalTxGas   uint64
+	selectedTxs  [][]byte
+}
+
+func NewDefaultTxSelector() TxSelector {
+	return &defaultTxSelector{}
+}
+
+func (ts *defaultTxSelector) SelectedTxs() [][]byte {
+	txs := make([][]byte, len(ts.selectedTxs))
+	copy(txs, ts.selectedTxs)
+	return txs
+}
+
+func (ts *defaultTxSelector) Clear() {
+	ts.totalTxBytes = 0
+	ts.totalTxGas = 0
+	ts.selectedTxs = nil
+}
+
+func (ts *defaultTxSelector) SelectTxForProposal(maxTxBytes, maxBlockGas uint64, memTx sdk.Tx, txBz []byte) bool {
+	txSize := uint64(len(txBz))
+
+	var txGasLimit uint64
+	if memTx != nil {
+		if gasTx, ok := memTx.(GasTx); ok {
+			txGasLimit = gasTx.GetGas()
+		}
+	}
+
+	// only add the transaction to the proposal if we have enough capacity
+	if (txSize + ts.totalTxBytes) <= maxTxBytes {
+		// If there is a max block gas limit, add the tx only if the limit has
+		// not been met.
+		if maxBlockGas > 0 {
+			if (txGasLimit + ts.totalTxGas) <= maxBlockGas {
+				ts.totalTxGas += txGasLimit
+				ts.totalTxBytes += txSize
+				ts.selectedTxs = append(ts.selectedTxs, txBz)
+			}
+		} else {
+			ts.totalTxBytes += txSize
+			ts.selectedTxs = append(ts.selectedTxs, txBz)
+		}
+	}
+
+	// check if we've reached capacity; if so, we cannot select any more transactions
+	return ts.totalTxBytes >= maxTxBytes || (maxBlockGas > 0 && (ts.totalTxGas >= maxBlockGas))
+}