Blackhole outbound: Add customizable response data support (#6713)

https://github.com/XTLS/Xray-core/pull/6711#issuecomment-5508683394

---------

Co-authored-by: Raaad1on <djilyawhite@gmail.com>

infra/conf/blackhole_test.go

@@ -3,7 +3,6 @@ package conf_test
 import (
 	"testing"
 
-	"github.com/xtls/xray-core/common/serial"
 	. "github.com/xtls/xray-core/infra/conf"
 	"github.com/xtls/xray-core/proxy/blackhole"
 )
@@ -22,7 +21,7 @@ func TestHTTPResponseJSON(t *testing.T) {
 			}`,
 			Parser: loadJSON(creator),
 			Output: &blackhole.Config{
-				Response: serial.ToTypedMessage(&blackhole.HTTPResponse{}),
+				Response: &blackhole.Response{Type: "http"},
 			},
 		},
 		{
@@ -32,3 +31,27 @@ func TestHTTPResponseJSON(t *testing.T) {
 		},
 	})
 }
+
+func TestCustomResponseJSON(t *testing.T) {
+	creator := func() Buildable {
+		return new(BlackholeConfig)
+	}
+
+	runMultiTestCase(t, []TestCase{
+		{
+			Input: `{
+				"response": {
+					"type": "custom",
+					"customResponseData": "Y3VzdG9tIHJlc3BvbnNl"
+				}
+			}`,
+			Parser: loadJSON(creator),
+			Output: &blackhole.Config{
+				Response: &blackhole.Response{
+					Type:               "custom",
+					CustomResponseData: []byte("custom response"),
+				},
+			},
+		},
+	})
+}