fix: Eth API: accept input data in call arguments under field 'input'

The correct name for this field is 'input' according to the Ethereum specs [0].
However, for the longest time, clients have been using 'data' and servers have been
lenient to accept both, preferring 'input' over 'data' when both appear.

Our lack of support for 'input' had gone unnoticed until go-ethereum decided
to adjust their ethclient implementation to issue eth_call and eth_estimateGas
requests with the 'input' field instead of 'data' [1]. This suddenly broke apps
using this client against Lotus' Eth API.

[0]: https://github.com/ethereum/execution-apis/blob/main/src/schemas/transaction.yaml#L33-L35
[1]: ethereum/go-ethereum#28078

Co-authored-by: raulk <raul.kripalani@gmail.com>

Author: Stebalien

chain/types/ethtypes/eth_types.go

@@ -229,13 +229,25 @@ type EthCall struct {
 }
 
 func (c *EthCall) UnmarshalJSON(b []byte) error {
-	type TempEthCall EthCall
-	var params TempEthCall
+	type EthCallRaw EthCall // Avoid a recursive call.
+	type EthCallDecode struct {
+		// The field should be "input" by spec, but many clients use "data" so we support
+		// both, but prefer "input".
+		Input *EthBytes `json:"input"`
+		EthCallRaw
+	}
 
+	var params EthCallDecode
 	if err := json.Unmarshal(b, &params); err != nil {
 		return err
 	}
-	*c = EthCall(params)
+
+	// If input is specified, prefer it.
+	if params.Input != nil {
+		params.Data = *params.Input
+	}
+
+	*c = EthCall(params.EthCallRaw)
 	return nil
 }
 

chain/types/ethtypes/eth_types_test.go

@@ -194,11 +194,40 @@ func TestMaskedIDInF4(t *testing.T) {
 }
 
 func TestUnmarshalEthCall(t *testing.T) {
-	data := `{"from":"0x4D6D86b31a112a05A473c4aE84afaF873f632325","to":"0xFe01CC39f5Ae8553D6914DBb9dC27D219fa22D7f","gas":"0x5","gasPrice":"0x6","value":"0x123","data":""}`
+	data := `{"from":"0x4D6D86b31a112a05A473c4aE84afaF873f632325","to":"0xFe01CC39f5Ae8553D6914DBb9dC27D219fa22D7f","gas":"0x5","gasPrice":"0x6","value":"0x123","data":"0xFF"}`
 
 	var c EthCall
 	err := c.UnmarshalJSON([]byte(data))
 	require.Nil(t, err)
+	require.EqualValues(t, []byte{0xff}, c.Data)
+}
+
+func TestUnmarshalEthCallInput(t *testing.T) {
+	data := `{"from":"0x4D6D86b31a112a05A473c4aE84afaF873f632325","to":"0xFe01CC39f5Ae8553D6914DBb9dC27D219fa22D7f","gas":"0x5","gasPrice":"0x6","value":"0x123","input":"0xFF"}`
+
+	var c EthCall
+	err := c.UnmarshalJSON([]byte(data))
+	require.Nil(t, err)
+	require.EqualValues(t, []byte{0xff}, c.Data)
+}
+
+func TestUnmarshalEthCallInputAndData(t *testing.T) {
+	data := `{"from":"0x4D6D86b31a112a05A473c4aE84afaF873f632325","to":"0xFe01CC39f5Ae8553D6914DBb9dC27D219fa22D7f","gas":"0x5","gasPrice":"0x6","value":"0x123","data":"0xFE","input":"0xFF"}`
+
+	var c EthCall
+	err := c.UnmarshalJSON([]byte(data))
+	require.Nil(t, err)
+	require.EqualValues(t, []byte{0xff}, c.Data)
+}
+
+func TestUnmarshalEthCallInputAndDataEmpty(t *testing.T) {
+	// Even if the input is empty, it should be used when specified.
+	data := `{"from":"0x4D6D86b31a112a05A473c4aE84afaF873f632325","to":"0xFe01CC39f5Ae8553D6914DBb9dC27D219fa22D7f","gas":"0x5","gasPrice":"0x6","value":"0x123","data":"0xFE","input":""}`
+
+	var c EthCall
+	err := c.UnmarshalJSON([]byte(data))
+	require.Nil(t, err)
+	require.EqualValues(t, []byte{}, c.Data)
 }
 
 func TestUnmarshalEthBytes(t *testing.T) {