fix: eth: correctly convert filecoin message <-> eth txn (#10257)

1. We do allow deploying with empty initcode.
2. Make sure that the encoded "code" is non-empty, if specified.

Basically, this makes everything consistent (and it's how I specified it
in the FIP).

chain/types/ethtypes/eth_transactions.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/filecoin-project/go-address"
 	gocrypto "github.com/filecoin-project/go-crypto"
+	"github.com/filecoin-project/go-state-types/abi"
 	"github.com/filecoin-project/go-state-types/big"
 	builtintypes "github.com/filecoin-project/go-state-types/builtin"
 	typescrypto "github.com/filecoin-project/go-state-types/crypto"
@@ -97,24 +98,31 @@ func EthTxFromSignedEthMessage(smsg *types.SignedMessage) (EthTx, error) {
 
 func EthTxArgsFromUnsignedEthMessage(msg *types.Message) (EthTxArgs, error) {
 	var (
-		to           *EthAddress
+		to     *EthAddress
-		params       []byte
+		params []byte
-		paramsReader = bytes.NewReader(msg.Params)
+		err    error
-		err          error
 	)
 
 	if msg.Version != 0 {
 		return EthTxArgs{}, xerrors.Errorf("unsupported msg version: %d", msg.Version)
 	}
 
+	if len(msg.Params) > 0 {
+		paramsReader := bytes.NewReader(msg.Params)
+		params, err = cbg.ReadByteArray(paramsReader, uint64(len(msg.Params)))
+		if err != nil {
+			return EthTxArgs{}, xerrors.Errorf("failed to read params byte array: %w", err)
+		}
+		if paramsReader.Len() != 0 {
+			return EthTxArgs{}, xerrors.Errorf("extra data found in params")
+		}
+		if len(params) == 0 {
+			return EthTxArgs{}, xerrors.Errorf("non-empty params encode empty byte array")
+		}
+	}
+
 	if msg.To == builtintypes.EthereumAddressManagerActorAddr {
-		switch msg.Method {
+		if msg.Method != builtintypes.MethodsEAM.CreateExternal {
-		case builtintypes.MethodsEAM.CreateExternal:
-			params, err = cbg.ReadByteArray(paramsReader, uint64(len(msg.Params)))
-			if err != nil {
-				return EthTxArgs{}, xerrors.Errorf("failed to read params byte array: %w", err)
-			}
-		default:
 			return EthTxArgs{}, fmt.Errorf("unsupported EAM method")
 		}
 	} else if msg.Method == builtintypes.MethodsEVM.InvokeContract {
@@ -123,23 +131,12 @@ func EthTxArgsFromUnsignedEthMessage(msg *types.Message) (EthTxArgs, error) {
 			return EthTxArgs{}, err
 		}
 		to = &addr
-
-		if len(msg.Params) > 0 {
-			params, err = cbg.ReadByteArray(paramsReader, uint64(len(msg.Params)))
-			if err != nil {
-				return EthTxArgs{}, xerrors.Errorf("failed to read params byte array: %w", err)
-			}
-		}
 	} else {
 		return EthTxArgs{},
 			xerrors.Errorf("invalid methodnum %d: only allowed method is InvokeContract(%d)",
 				msg.Method, builtintypes.MethodsEVM.InvokeContract)
 	}
 
-	if paramsReader.Len() != 0 {
-		return EthTxArgs{}, xerrors.Errorf("extra data found in params")
-	}
-
 	return EthTxArgs{
 		ChainID:              build.Eip155ChainId,
 		Nonce:                int(msg.Nonce),
@@ -159,34 +156,26 @@ func (tx *EthTxArgs) ToUnsignedMessage(from address.Address) (*types.Message, er
 
 	var err error
 	var params []byte
-	var to address.Address
+	if len(tx.Input) > 0 {
-	method := builtintypes.MethodsEVM.InvokeContract
-	// nil indicates the EAM, only CreateExternal is allowed
-	if tx.To == nil {
-		to = builtintypes.EthereumAddressManagerActorAddr
-		method = builtintypes.MethodsEAM.CreateExternal
-		if len(tx.Input) == 0 {
-			return nil, xerrors.New("cannot call CreateExternal without params")
-		}
-
 		buf := new(bytes.Buffer)
 		if err = cbg.WriteByteArray(buf, tx.Input); err != nil {
-			return nil, xerrors.Errorf("failed to serialize Create params: %w", err)
+			return nil, xerrors.Errorf("failed to write input args: %w", err)
 		}
-
 		params = buf.Bytes()
+	}
+
+	var to address.Address
+	var method abi.MethodNum
+	// nil indicates the EAM, only CreateExternal is allowed
+	if tx.To == nil {
+		method = builtintypes.MethodsEAM.CreateExternal
+		to = builtintypes.EthereumAddressManagerActorAddr
 	} else {
+		method = builtintypes.MethodsEVM.InvokeContract
 		to, err = tx.To.ToFilecoinAddress()
 		if err != nil {
 			return nil, xerrors.Errorf("failed to convert To into filecoin addr: %w", err)
 		}
-		if len(tx.Input) > 0 {
-			buf := new(bytes.Buffer)
-			if err = cbg.WriteByteArray(buf, tx.Input); err != nil {
-				return nil, xerrors.Errorf("failed to write input args: %w", err)
-			}
-			params = buf.Bytes()
-		}
 	}
 
 	return &types.Message{

node/impl/full/eth.go

@@ -751,18 +751,20 @@ func (a *EthModule) ethCallToFilecoinMessage(ctx context.Context, tx ethtypes.Et
 	}
 
 	var params []byte
+	if len(tx.Data) > 0 {
+		initcode := abi.CborBytes(tx.Data)
+		params2, err := actors.SerializeParams(&initcode)
+		if err != nil {
+			return nil, fmt.Errorf("failed to serialize params: %w", err)
+		}
+		params = params2
+	}
+
 	var to address.Address
 	var method abi.MethodNum
 	if tx.To == nil {
 		// this is a contract creation
 		to = builtintypes.EthereumAddressManagerActorAddr
-
-		initcode := abi.CborBytes(tx.Data)
-		params2, err := actors.SerializeParams(&initcode)
-		if err != nil {
-			return nil, fmt.Errorf("failed to serialize Create params: %w", err)
-		}
-		params = params2
 		method = builtintypes.MethodsEAM.CreateExternal
 	} else {
 		addr, err := tx.To.ToFilecoinAddress()
@@ -770,15 +772,6 @@ func (a *EthModule) ethCallToFilecoinMessage(ctx context.Context, tx ethtypes.Et
 			return nil, xerrors.Errorf("cannot get Filecoin address: %w", err)
 		}
 		to = addr
-
-		if len(tx.Data) > 0 {
-			var buf bytes.Buffer
-			if err := cbg.WriteByteArray(&buf, tx.Data); err != nil {
-				return nil, fmt.Errorf("failed to encode tx input into a cbor byte-string")
-			}
-			params = buf.Bytes()
-		}
-
 		method = builtintypes.MethodsEVM.InvokeContract
 	}