fix: eth: strict event parsing

We now enforce the following rules:

1. No duplicate topics or data.
2. Topics must have 32 byte keys.
3. Topics may not be skipped. (e.g., no t1 & t3 without a t2).
4. Raw codecs.

We _don't_ require that topics/data be emitted in any specific order.

We _skip_ events with unknown keys. We _drop_ events that violate the
above rules.

chain/types/ethtypes/eth_types.go

@@ -25,13 +25,6 @@ import (
 	"github.com/filecoin-project/lotus/lib/must"
 )
 
-var (
-	EthTopic1 = "t1"
-	EthTopic2 = "t2"
-	EthTopic3 = "t3"
-	EthTopic4 = "t4"
-)
-
 var ErrInvalidAddress = errors.New("invalid Filecoin Eth address")
 
 type EthUint64 uint64

itests/eth_filter_test.go

@@ -2153,16 +2153,6 @@ func ParseEthLog(in map[string]interface{}) (*ethtypes.EthLog, error) {
 	return el, err
 }
 
-func paddedEthBytes(orig []byte) ethtypes.EthBytes {
-	needed := 32 - len(orig)
-	if needed <= 0 {
-		return orig
-	}
-	ret := make([]byte, 32)
-	copy(ret[needed:], orig)
-	return ret
-}
-
 func paddedUint64(v uint64) ethtypes.EthBytes {
 	buf := make([]byte, 32)
 	binary.BigEndian.PutUint64(buf[24:], v)

node/impl/full/eth.go

@@ -1358,6 +1358,65 @@ type filterTipSetCollector interface {
 	TakeCollectedTipSets(context.Context) []types.TipSetKey
 }
 
+func ethLogFromEvent(entries []types.EventEntry) (data []byte, topics []ethtypes.EthHash, ok bool) {
+	var (
+		topicsFound      [4]bool
+		topicsFoundCount int
+		dataFound        bool
+	)
+	for _, entry := range entries {
+		// Check if the key is t1..t4
+		if len(entry.Key) == 2 && "t1" <= entry.Key && entry.Key <= "t4" {
+			// '1' - '1' == 0, etc.
+			idx := int(entry.Key[1] - '1')
+
+			// Drop events with mis-sized topics.
+			if len(entry.Value) != 32 {
+				return nil, nil, false
+			}
+
+			// Drop events with non-raw topics to avoid mistakes.
+			if entry.Codec != cid.Raw {
+				return nil, nil, false
+			}
+
+			// Drop events with duplicate topics.
+			if topicsFound[idx] {
+				return nil, nil, false
+			}
+			topicsFound[idx] = true
+			topicsFoundCount++
+
+			// Extend the topics array
+			for len(topics) <= idx {
+				topics = append(topics, ethtypes.EthHash{})
+			}
+			copy(topics[idx][:], entry.Value)
+		} else if entry.Key == "d" {
+			// Drop events with non-raw data to avoid mistakes.
+			if entry.Codec != cid.Raw {
+				return nil, nil, false
+			}
+
+			// Drop events with duplicate data fields.
+			if dataFound {
+				return nil, nil, false
+			}
+
+			dataFound = true
+			data = entry.Value
+		}
+
+		// Skip entries we don't understand (makes it easier to extend things).
+	}
+
+	// Drop events with skipped topics.
+	if len(topics) != topicsFoundCount {
+		return nil, nil, false
+	}
+	return data, topics, true
+}
+
 func ethFilterResultFromEvents(evs []*filter.CollectedEvent, sa StateAPI) (*ethtypes.EthFilterResult, error) {
 	res := &ethtypes.EthFilterResult{}
 	for _, ev := range evs {
@@ -1367,24 +1426,14 @@ func ethFilterResultFromEvents(evs []*filter.CollectedEvent, sa StateAPI) (*etht
 			TransactionIndex: ethtypes.EthUint64(ev.MsgIdx),
 			BlockNumber:      ethtypes.EthUint64(ev.Height),
 		}
+		var (
+			err error
+			ok  bool
+		)
 
-		var err error
-
-		for _, entry := range ev.Entries {
-			// Skip all events that aren't "raw" data.
-			if entry.Codec != cid.Raw {
-				continue
-			}
-			if entry.Key == ethtypes.EthTopic1 || entry.Key == ethtypes.EthTopic2 || entry.Key == ethtypes.EthTopic3 || entry.Key == ethtypes.EthTopic4 {
-				if len(entry.Value) != 32 {
-					continue
-				}
-				var value ethtypes.EthHash
-				copy(value[:], entry.Value)
-				log.Topics = append(log.Topics, value)
-			} else {
-				log.Data = entry.Value
-			}
+		log.Data, log.Topics, ok = ethLogFromEvent(ev.Entries)
+		if !ok {
+			continue
 		}
 
 		log.Address, err = ethtypes.EthAddressFromFilecoinAddress(ev.EmitterAddr)
@@ -1912,23 +1961,16 @@ func newEthTxReceipt(ctx context.Context, tx ethtypes.EthTx, lookup *api.MsgLook
 				BlockNumber:      blockNumber,
 			}
 
-			for _, entry := range evt.Entries {
-				// Ignore any non-raw values/keys.
-				if entry.Codec != cid.Raw {
-					continue
-				}
-				if entry.Key == ethtypes.EthTopic1 || entry.Key == ethtypes.EthTopic2 || entry.Key == ethtypes.EthTopic3 || entry.Key == ethtypes.EthTopic4 {
-					if len(entry.Value) != 32 {
-						continue
-					}
-					var value ethtypes.EthHash
-					copy(value[:], entry.Value)
-					l.Topics = append(l.Topics, value)
-					ethtypes.EthBloomSet(receipt.LogsBloom, entry.Value)
-				} else {
-					l.Data = entry.Value
-				}
+			data, topics, ok := ethLogFromEvent(evt.Entries)
+			if !ok {
+				// not an eth event.
+				continue
 			}
+			for _, topic := range topics {
+				ethtypes.EthBloomSet(receipt.LogsBloom, topic[:])
+			}
+			l.Data = data
+			l.Topics = topics
 
 			addr, err := address.NewIDAddress(uint64(evt.Emitter))
 			if err != nil {

node/impl/full/eth_test.go

@@ -0,0 +1,101 @@
+package full
+
+import (
+	"testing"
+
+	"github.com/filecoin-project/lotus/chain/types"
+	"github.com/filecoin-project/lotus/chain/types/ethtypes"
+	"github.com/ipfs/go-cid"
+	"github.com/stretchr/testify/require"
+)
+
+func TestEthLogFromEvent(t *testing.T) {
+	// basic empty
+	data, topics, ok := ethLogFromEvent(nil)
+	require.True(t, ok)
+	require.Nil(t, data)
+	require.Nil(t, topics)
+
+	// basic topic
+	data, topics, ok = ethLogFromEvent([]types.EventEntry{{
+		Flags: 0,
+		Key:   "t1",
+		Codec: cid.Raw,
+		Value: make([]byte, 32),
+	}})
+	require.True(t, ok)
+	require.Nil(t, data)
+	require.Len(t, topics, 1)
+	require.Equal(t, topics[0], ethtypes.EthHash{})
+
+	// basic topic with data
+	data, topics, ok = ethLogFromEvent([]types.EventEntry{{
+		Flags: 0,
+		Key:   "t1",
+		Codec: cid.Raw,
+		Value: make([]byte, 32),
+	}, {
+		Flags: 0,
+		Key:   "d",
+		Codec: cid.Raw,
+		Value: []byte{0x0},
+	}})
+	require.True(t, ok)
+	require.Equal(t, data, []byte{0x0})
+	require.Len(t, topics, 1)
+	require.Equal(t, topics[0], ethtypes.EthHash{})
+
+	// skip topic
+	_, _, ok = ethLogFromEvent([]types.EventEntry{{
+		Flags: 0,
+		Key:   "t2",
+		Codec: cid.Raw,
+		Value: make([]byte, 32),
+	}})
+	require.False(t, ok)
+
+	// duplicate topic
+	_, _, ok = ethLogFromEvent([]types.EventEntry{{
+		Flags: 0,
+		Key:   "t1",
+		Codec: cid.Raw,
+		Value: make([]byte, 32),
+	}, {
+		Flags: 0,
+		Key:   "t1",
+		Codec: cid.Raw,
+		Value: make([]byte, 32),
+	}})
+	require.False(t, ok)
+
+	// duplicate data
+	_, _, ok = ethLogFromEvent([]types.EventEntry{{
+		Flags: 0,
+		Key:   "d",
+		Codec: cid.Raw,
+		Value: make([]byte, 32),
+	}, {
+		Flags: 0,
+		Key:   "d",
+		Codec: cid.Raw,
+		Value: make([]byte, 32),
+	}})
+	require.False(t, ok)
+
+	// unknown key is fine
+	data, topics, ok = ethLogFromEvent([]types.EventEntry{{
+		Flags: 0,
+		Key:   "t5",
+		Codec: cid.Raw,
+		Value: make([]byte, 32),
+	}, {
+		Flags: 0,
+		Key:   "t1",
+		Codec: cid.Raw,
+		Value: make([]byte, 32),
+	}})
+	require.True(t, ok)
+	require.Nil(t, data)
+	require.Len(t, topics, 1)
+	require.Equal(t, topics[0], ethtypes.EthHash{})
+}