fix: kpa issue

api/core/helper/code_executor/javascript/javascript_transformer.py

@@ -4,6 +4,8 @@ from core.helper.code_executor.template_transformer import TemplateTransformer
 
 
 class NodeJsTemplateTransformer(TemplateTransformer):
+    _comment_prefix: str = "//"
+
     @classmethod
     def get_runner_script(cls) -> str:
         runner_script = dedent(f"""            {cls._code_placeholder}

api/core/helper/code_executor/jinja2/jinja2_transformer.py

@@ -31,7 +31,7 @@ class Jinja2TemplateTransformer(TemplateTransformer):
         script = script.replace(cls._template_b64_placeholder, code_b64)
         inputs_str = cls.serialize_inputs(inputs)
         script = script.replace(cls._inputs_placeholder, inputs_str)
-        return script
+        return cls._generate_anti_kpa_padding() + script
 
     @classmethod
     def get_runner_script(cls) -> str:

api/core/helper/code_executor/template_transformer.py

@@ -1,5 +1,6 @@
 import json
 import re
+import secrets
 from abc import ABC, abstractmethod
 from base64 import b64encode
 from collections.abc import Mapping
@@ -7,11 +8,16 @@ from typing import Any
 
 from dify_graph.variables.utils import dumps_with_segments
 
+# Minimum random padding bytes to exceed the sandbox XOR key length (64 bytes).
+_ANTI_KPA_MIN_PADDING = 512
+_ANTI_KPA_JITTER = 256
+
 
 class TemplateTransformer(ABC):
     _code_placeholder: str = "{{code}}"
     _inputs_placeholder: str = "{{inputs}}"
     _result_tag: str = "<<RESULT>>"
+    _comment_prefix: str = "#"
 
     @classmethod
     def serialize_code(cls, code: str) -> str:
@@ -106,6 +112,12 @@ class TemplateTransformer(ABC):
         input_base64_encoded = b64encode(inputs_json_str).decode("utf-8")
         return input_base64_encoded
 
+    @classmethod
+    def _generate_anti_kpa_padding(cls) -> str:
+        padding_size = secrets.randbelow(_ANTI_KPA_JITTER) + _ANTI_KPA_MIN_PADDING
+        nonce = secrets.token_hex(padding_size)
+        return f"{cls._comment_prefix} {nonce}\n"
+
     @classmethod
     def assemble_runner_script(cls, code: str, inputs: Mapping[str, Any]) -> str:
         # assemble runner script
@@ -113,7 +125,7 @@ class TemplateTransformer(ABC):
         script = script.replace(cls._code_placeholder, code)
         inputs_str = cls.serialize_inputs(inputs)
         script = script.replace(cls._inputs_placeholder, inputs_str)
-        return script
+        return cls._generate_anti_kpa_padding() + script
 
     @classmethod
     def get_preload_script(cls) -> str:

api/tests/unit_tests/core/helper/code_executor/javascript/test_javascript_transformer.py

@@ -8,5 +8,17 @@ def test_get_runner_script():
     script = NodeJsTemplateTransformer.assemble_runner_script(code, inputs)
     script_lines = script.splitlines()
     code_lines = code.splitlines()
-    # Check that the first lines of script are exactly the same as code
-    assert script_lines[: len(code_lines)] == code_lines
+    # First line is a random anti-KPA padding comment using JS syntax
+    assert script_lines[0].startswith("// ")
+    # User code follows immediately after the padding line
+    assert script_lines[1 : 1 + len(code_lines)] == code_lines
+
+
+def test_anti_kpa_padding_is_unique():
+    code = JavascriptCodeProvider.get_default_code()
+    inputs = {"arg1": "a", "arg2": "b"}
+    script_a = NodeJsTemplateTransformer.assemble_runner_script(code, inputs)
+    script_b = NodeJsTemplateTransformer.assemble_runner_script(code, inputs)
+    padding_a = script_a.splitlines()[0]
+    padding_b = script_b.splitlines()[0]
+    assert padding_a != padding_b, "Each assembled script must have unique random padding"

api/tests/unit_tests/core/helper/code_executor/python3/test_python3_transformer.py

@@ -8,5 +8,17 @@ def test_get_runner_script():
     script = Python3TemplateTransformer.assemble_runner_script(code, inputs)
     script_lines = script.splitlines()
     code_lines = code.splitlines()
-    # Check that the first lines of script are exactly the same as code
-    assert script_lines[: len(code_lines)] == code_lines
+    # First line is a random anti-KPA padding comment
+    assert script_lines[0].startswith("# ")
+    # User code follows immediately after the padding line
+    assert script_lines[1 : 1 + len(code_lines)] == code_lines
+
+
+def test_anti_kpa_padding_is_unique():
+    code = Python3CodeProvider.get_default_code()
+    inputs = {"arg1": "a", "arg2": "b"}
+    script_a = Python3TemplateTransformer.assemble_runner_script(code, inputs)
+    script_b = Python3TemplateTransformer.assemble_runner_script(code, inputs)
+    padding_a = script_a.splitlines()[0]
+    padding_b = script_b.splitlines()[0]
+    assert padding_a != padding_b, "Each assembled script must have unique random padding"