stringify json for EIP 712 encoding

ethereum/eip712/message.go

@@ -2,6 +2,8 @@ package eip712
 
 import (
 	"fmt"
+	"strconv"
+	"strings"
 
 	"github.com/tidwall/gjson"
 	"github.com/tidwall/sjson"
@@ -29,6 +31,11 @@ func createEIP712MessagePayload(data []byte) (eip712MessagePayload, error) {
 		return eip712MessagePayload{}, err
 	}
 
+	basicPayload, err = stringifyJSONMsgFields(basicPayload)
+	if err != nil {
+		return eip712MessagePayload{}, errorsmod.Wrap(err, "failed to stringify JSON message fields")
+	}
+
 	payload, numPayloadMsgs, err := FlattenPayloadMessages(basicPayload)
 	if err != nil {
 		return eip712MessagePayload{}, errorsmod.Wrap(err, "failed to flatten payload JSON messages")
@@ -48,6 +55,62 @@ func createEIP712MessagePayload(data []byte) (eip712MessagePayload, error) {
 	return messagePayload, nil
 }
 
+// stringifyJSONMsgFields converts object- and array-valued "msg" fields to
+// strings. Message fields conventionally contain opaque JSON (for example,
+// CosmWasm contract messages), whose runtime shape cannot be represented by a
+// stable EIP-712 type. Existing string values are left alone so ordinary
+// string fields and already-stringified JSON are not changed.
+//
+// The conversion only affects the derived EIP-712 payload. The protobuf
+// transaction still contains the original value used during execution.
+func stringifyJSONMsgFields(value gjson.Result) (gjson.Result, error) {
+	if !value.IsObject() && !value.IsArray() {
+		return value, nil
+	}
+
+	updated := value.Raw
+	var iterationErr error
+	value.ForEach(func(key, child gjson.Result) bool {
+		path := key.Str
+		if value.IsArray() {
+			path = strconv.FormatInt(key.Int(), 10)
+		} else {
+			path = escapeSJSONPath(path)
+		}
+
+		if !value.IsArray() && key.Str == "msg" && (child.IsObject() || child.IsArray()) {
+			updated, iterationErr = sjson.Set(updated, path, child.Raw)
+			return iterationErr == nil
+		}
+
+		if !child.IsObject() && !child.IsArray() {
+			return true
+		}
+
+		var transformed gjson.Result
+		transformed, iterationErr = stringifyJSONMsgFields(child)
+		if iterationErr != nil {
+			return false
+		}
+
+		updated, iterationErr = sjson.SetRaw(updated, path, transformed.Raw)
+		return iterationErr == nil
+	})
+	if iterationErr != nil {
+		return gjson.Result{}, iterationErr
+	}
+
+	return gjson.Parse(updated), nil
+}
+
+// escapeSJSONPath escapes object keys so they are treated as literal field
+// names rather than SJSON path syntax.
+func escapeSJSONPath(path string) string {
+	path = strings.ReplaceAll(path, `\`, `\\`)
+	path = strings.ReplaceAll(path, `.`, `\.`)
+	return strings.ReplaceAll(path, `:`, `\:`)
+}
+
 // unmarshalBytesToJSONObject converts a bytestream into
 // a JSON object, then makes sure the JSON is an object.
 func unmarshalBytesToJSONObject(data []byte) (gjson.Result, error) {

ethereum/eip712/message_test.go

@@ -0,0 +1,105 @@
+package eip712
+
+import (
+	"testing"
+
+	"github.com/ethereum/go-ethereum/signer/core/apitypes"
+	"github.com/stretchr/testify/require"
+	"github.com/tidwall/gjson"
+)
+
+func TestCreateEIP712MessagePayloadStringifiesOpaqueJSONMsg(t *testing.T) {
+	t.Parallel()
+
+	data := []byte(`{
+		"account_number":"0",
+		"chain_id":"evm-1",
+		"fee":{"amount":[],"gas":"200000"},
+		"memo":"",
+		"msgs":[{
+			"type":"wasm/MsgExecuteContract",
+			"value":{
+				"contract":"cosmos1contract",
+				"funds":[],
+				"msg":{"transfer":{"amount":"10","recipient":"cosmos1recipient"}},
+				"sender":"cosmos1sender"
+			}
+		}],
+		"sequence":"0"
+	}`)
+
+	payload, err := createEIP712MessagePayload(data)
+	require.NoError(t, err)
+
+	msg := payload.payload.Get("msg0.value.msg")
+	require.Equal(t, gjson.String, msg.Type)
+	require.JSONEq(t, `{"transfer":{"amount":"10","recipient":"cosmos1recipient"}}`, msg.Str)
+
+	types, err := createEIP712Types(payload)
+	require.NoError(t, err)
+	require.Contains(t, types["TypeValue0"], apitypes.Type{Name: "msg", Type: ethString})
+	require.NotContains(t, types, "TypeValueMsg0")
+}
+
+func TestCreateEIP712MessagePayloadHandlesNestedAndArrayJSONMsg(t *testing.T) {
+	t.Parallel()
+
+	data := []byte(`{
+		"account_number":"0",
+		"chain_id":"evm-1",
+		"fee":{"amount":[],"gas":"200000"},
+		"memo":"",
+		"msgs":[{
+			"type":"cosmos.authz.v1beta1/MsgExec",
+			"value":{"msgs":[{"type":"wasm/MsgExecuteContract","value":{"msg":[{"mint":{}},2]}}]}
+		}],
+		"sequence":"0"
+	}`)
+
+	payload, err := createEIP712MessagePayload(data)
+	require.NoError(t, err)
+
+	msg := payload.payload.Get("msg0.value.msgs.0.value.msg")
+	require.Equal(t, gjson.String, msg.Type)
+	require.JSONEq(t, `[{"mint":{}},2]`, msg.Str)
+}
+
+func TestCreateEIP712MessagePayloadPreservesStringMsg(t *testing.T) {
+	t.Parallel()
+
+	for _, value := range []string{
+		`"ordinary text"`,
+		`"{\"already\":\"stringified\"}"`,
+	} {
+		data := []byte(`{
+			"account_number":"0",
+			"chain_id":"evm-1",
+			"fee":{"amount":[],"gas":"200000"},
+			"memo":"",
+			"msgs":[{"type":"example/Msg","value":{"msg":` + value + `}}],
+			"sequence":"0"
+		}`)
+
+		original := gjson.ParseBytes(data).Get("msgs.0.value.msg").Str
+		payload, err := createEIP712MessagePayload(data)
+		require.NoError(t, err)
+		require.Equal(t, original, payload.payload.Get("msg0.value.msg").Str)
+	}
+}
+
+func TestCreateEIP712MessagePayloadPreservesTypedObjects(t *testing.T) {
+	t.Parallel()
+
+	data := []byte(`{
+		"account_number":"0",
+		"chain_id":"evm-1",
+		"fee":{"amount":[],"gas":"200000"},
+		"memo":"",
+		"msgs":[{"type":"example/Msg","value":{"details":{"enabled":true},"msg":"text"}}],
+		"sequence":"0"
+	}`)
+
+	payload, err := createEIP712MessagePayload(data)
+	require.NoError(t, err)
+	require.True(t, payload.payload.Get("msg0.value.details").IsObject())
+}