[proxy] simplify usage of class variables of `Policy` subtypes

This commit also prevents popup script injection to Haketilo-served pages like `https://hkt.mitm.it/`.

1 files changed, 13 insertions, 5 deletions

diff --git a/src/hydrilla/proxy/policies/base.py b/src/hydrilla/proxy/policies/base.py
index 0c37185..7ce5105 100644
--- a/src/hydrilla/proxy/policies/base.py
+++ b/src/hydrilla/proxy/policies/base.py
@@ -62,12 +62,20 @@ popup_script = jinja_env.get_template('popup.js.jinja').render()
 popup_script_sha256_bytes = sha256(popup_script.encode()).digest()
 popup_script_sha256_b64 = b64encode(popup_script_sha256_bytes).decode()
 
+
 class PolicyPriority(int, enum.Enum):
     """...."""
     _ONE   = 1
     _TWO   = 2
     _THREE = 3
 
+
+class MsgProcessOpt(enum.Enum):
+    """...."""
+    MUST     = True
+    MUST_NOT = False
+
+
 MessageInfo = t.Union[
     http_messages.RequestInfo,
     http_messages.ResponseInfo
@@ -91,8 +99,8 @@ BOMs = (
 # https://stackoverflow.com/questions/70999513/conflict-between-mix-ins-for-abstract-dataclasses/70999704#70999704
 @dc.dataclass(frozen=True) # type: ignore[misc]
 class Policy(ABC):
-    _process_request:  t.ClassVar[bool] = False
-    _process_response: t.ClassVar[bool] = False
+    _process_request:  t.ClassVar[t.Optional[MsgProcessOpt]] = None
+    _process_response: t.ClassVar[t.Optional[MsgProcessOpt]] = None
     anticache:         t.ClassVar[bool] = True
 
     priority: t.ClassVar[PolicyPriority]
@@ -107,15 +115,15 @@ class Policy(ABC):
             self,
             request_info: http_messages.BodylessRequestInfo
     ) -> bool:
-        return self._process_request
+        return self._process_request == MsgProcessOpt.MUST
 
     def should_process_response(
             self,
             request_info:  http_messages.RequestInfo,
             response_info: http_messages.AnyResponseInfo
     ) -> bool:
-        if self._process_response:
-            return True
+        if self._process_response is not None:
+            return self._process_response.value
 
         return (self.current_popup_settings.popup_enabled and
                 http_messages.is_likely_a_page(request_info, response_info))