Add JSON validity check to cosmosInlineJSON

x/tx/signing/aminojson/encoder.go

@@ -82,20 +82,20 @@ func nullSliceAsEmptyEncoder(enc *Encoder, v protoreflect.Value, w io.Writer) er
 }
 
 // cosmosInlineJSON takes bytes and inlines them into a JSON document.
-// This assumes the bytes contain valid JSON since otherwise the resulting document is invalid.
+//
+// This requires the bytes contain valid JSON since otherwise the resulting document would be invalid.
+// Invalid JSON will result in an error.
 //
 // This replicates the behavior of JSON messages embedded in protobuf bytes
 // required for CosmWasm, e.g.:
 // https://github.com/CosmWasm/wasmd/blob/08567ff20e372e4f4204a91ca64a371538742bed/x/wasm/types/tx.go#L20-L22
 func cosmosInlineJSON(_ *Encoder, v protoreflect.Value, w io.Writer) error {
 	switch bz := v.Interface().(type) {
 	case []byte:
-		// Caution, this does not include a validity check as json.RawMessage can be anything 🤷‍♂️
-		blob, err := json.RawMessage(bz).MarshalJSON()
-		if err != nil {
-			return err
+		if !json.Valid(bz) {
+			return errors.New("invalid JSON bytes")
 		}
-		_, err = w.Write(blob)
+		_, err := w.Write(bz)
 		return err
 	default:
 		return fmt.Errorf("unsupported type %T", bz)

x/tx/signing/aminojson/encoder_test.go

@@ -56,15 +56,17 @@ func TestCosmosInlineJSON(t *testing.T) {
 			wantErr:    false,
 			wantOutput: `"hey yo"`,
 		},
-		// This test case is a bit tricky. Conceptually it makes no sense for this
-		// to pass. The question is just where the JSON validity check is done.
-		// In wasmd we have it in the message field validation. But it might make
-		// sense to move it here instead.
-		// For now it's better to consider this case undefined behaviour.
 		"supported type - invalid JSON": {
-			value:      protoreflect.ValueOfBytes([]byte(`foo`)),
-			wantErr:    false,
-			wantOutput: `foo`,
+			value:   protoreflect.ValueOfBytes([]byte(`foo`)),
+			wantErr: true,
+		},
+		"supported type - invalid JSON (empty)": {
+			value:   protoreflect.ValueOfBytes([]byte(``)),
+			wantErr: true,
+		},
+		"supported type - invalid JSON (nil bytes)": {
+			value:   protoreflect.ValueOfBytes(nil),
+			wantErr: true,
 		},
 		"unsupported type - bool": {
 			value:   protoreflect.ValueOfBool(true),