feat: support safe param for eth_getBlockByNumber for 30 blocks

app/submodule/eth/eth_utils.go

@@ -56,6 +56,22 @@ func getTipsetByBlockNumber(ctx context.Context, store *chain.Store, blkParam st
 			return nil, fmt.Errorf("cannot get parent tipset")
 		}
 		return parent, nil
+	case "safe":
+		latestHeight := head.Height() - 1
+		safeHeight := latestHeight - types.SafeEpochDelay
+		ts, err := store.GetTipSetByHeight(ctx, head, safeHeight, true)
+		if err != nil {
+			return nil, fmt.Errorf("cannot get tipset at height: %v", safeHeight)
+		}
+		return ts, nil
+	case "finalized":
+		latestHeight := head.Height() - 1
+		safeHeight := latestHeight - constants.Finality
+		ts, err := store.GetTipSetByHeight(ctx, head, safeHeight, true)
+		if err != nil {
+			return nil, fmt.Errorf("cannot get tipset at height: %v", safeHeight)
+		}
+		return ts, nil
 	default:
 		var num types.EthUint64
 		err := num.UnmarshalJSON([]byte(`"` + blkParam + `"`))

venus-shared/actors/types/eth.go

@@ -25,6 +25,12 @@ import (
 
 var ErrInvalidAddress = errors.New("invalid Filecoin Eth address")
 
+// Research into Filecoin chain behaviour suggests that probabilistic finality
+// generally approaches the intended stability guarantee at, or near, 30 epochs.
+// Although a strictly "finalized" safe recommendation remains 900 epochs.
+// See https://github.com/filecoin-project/FIPs/blob/master/FRCs/frc-0089.md
+const SafeEpochDelay = abi.ChainEpoch(30)
+
 // mainnet
 var Eip155ChainID = 314