eth/filters: exit early if topics-filter has more than 4 topics (#28494)

Currently, geth's will return `[]` for any `len(topics) > 4` log filter. The EVM only supports up to four logs, via LOG4 opcode, so larger criterias fail. This change makes the filter query exit early in those cases.

Author: jsvisa

eth/filters/api.go

@@ -37,8 +37,12 @@ var (
 	errInvalidTopic      = errors.New("invalid topic(s)")
 	errFilterNotFound    = errors.New("filter not found")
 	errInvalidBlockRange = errors.New("invalid block range params")
+	errExceedMaxTopics   = errors.New("exceed max topics")
 )
 
+// The maximum number of topic criteria allowed, vm.LOG4 - vm.LOG0
+const maxTopics = 4
+
 // filter is a helper struct that holds meta information over the filter type
 // and associated subscription in the event system.
 type filter struct {
@@ -334,6 +338,9 @@ func (api *FilterAPI) NewFilter(crit FilterCriteria) (rpc.ID, error) {
 
 // GetLogs returns logs matching the given argument that are stored within the state.
 func (api *FilterAPI) GetLogs(ctx context.Context, crit FilterCriteria) ([]*types.Log, error) {
+	if len(crit.Topics) > maxTopics {
+		return nil, errExceedMaxTopics
+	}
 	var filter *Filter
 	if crit.BlockHash != nil {
 		// Block filter requested, construct a single-shot filter

eth/filters/filter_system.go

@@ -299,6 +299,9 @@ func (es *EventSystem) subscribe(sub *subscription) *Subscription {
 // given criteria to the given logs channel. Default value for the from and to
 // block is "latest". If the fromBlock > toBlock an error is returned.
 func (es *EventSystem) SubscribeLogs(crit ethereum.FilterQuery, logs chan []*types.Log) (*Subscription, error) {
+	if len(crit.Topics) > maxTopics {
+		return nil, errExceedMaxTopics
+	}
 	var from, to rpc.BlockNumber
 	if crit.FromBlock == nil {
 		from = rpc.LatestBlockNumber

eth/filters/filter_system_test.go

@@ -386,6 +386,8 @@ func TestLogFilterCreation(t *testing.T) {
 			{FilterCriteria{FromBlock: big.NewInt(rpc.PendingBlockNumber.Int64()), ToBlock: big.NewInt(100)}, false},
 			// from block "higher" than to block
 			{FilterCriteria{FromBlock: big.NewInt(rpc.PendingBlockNumber.Int64()), ToBlock: big.NewInt(rpc.LatestBlockNumber.Int64())}, false},
+			// topics more then 4
+			{FilterCriteria{Topics: [][]common.Hash{{}, {}, {}, {}, {}}}, false},
 		}
 	)
 
@@ -420,6 +422,7 @@ func TestInvalidLogFilterCreation(t *testing.T) {
 		0: {FromBlock: big.NewInt(rpc.PendingBlockNumber.Int64()), ToBlock: big.NewInt(rpc.LatestBlockNumber.Int64())},
 		1: {FromBlock: big.NewInt(rpc.PendingBlockNumber.Int64()), ToBlock: big.NewInt(100)},
 		2: {FromBlock: big.NewInt(rpc.LatestBlockNumber.Int64()), ToBlock: big.NewInt(100)},
+		3: {Topics: [][]common.Hash{{}, {}, {}, {}, {}}},
 	}
 
 	for i, test := range testCases {
@@ -445,6 +448,7 @@ func TestInvalidGetLogsRequest(t *testing.T) {
 		0: {BlockHash: &blockHash, FromBlock: big.NewInt(100)},
 		1: {BlockHash: &blockHash, ToBlock: big.NewInt(500)},
 		2: {BlockHash: &blockHash, FromBlock: big.NewInt(rpc.LatestBlockNumber.Int64())},
+		3: {BlockHash: &blockHash, Topics: [][]common.Hash{{}, {}, {}, {}, {}}},
 	}
 
 	for i, test := range testCases {