[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/`.

6 files changed, 36 insertions, 37 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))
diff --git a/src/hydrilla/proxy/policies/misc.py b/src/hydrilla/proxy/policies/misc.py
index af6c144..350f3dc 100644
--- a/src/hydrilla/proxy/policies/misc.py
+++ b/src/hydrilla/proxy/policies/misc.py
@@ -42,13 +42,11 @@ from .rule import AllowPolicy, BlockPolicy
 
 
 class FallbackAllowPolicy(AllowPolicy):
-    """....."""
-    priority: t.ClassVar[base.PolicyPriority] = base.PolicyPriority._ONE
+    priority = base.PolicyPriority._ONE
 
 
 class FallbackBlockPolicy(BlockPolicy):
-    """...."""
-    priority: t.ClassVar[base.PolicyPriority] = base.PolicyPriority._ONE
+    priority = base.PolicyPriority._ONE
 
 
 @dc.dataclass(frozen=True)
@@ -63,11 +61,11 @@ class MitmItPagePolicy(base.Policy):
     request and response not to be modified in any way and also (unlike
     FallbackAllowPolicy) prevents them from being streamed.
     """
-    _process_request:  t.ClassVar[bool] = True
-    _process_response: t.ClassVar[bool] = True
-    anticache:         t.ClassVar[bool] = False
+    _process_request  = base.MsgProcessOpt.MUST
+    _process_response = base.MsgProcessOpt.MUST
+    anticache         = False
 
-    priority: t.ClassVar[base.PolicyPriority] = base.PolicyPriority._THREE
+    priority = base.PolicyPriority._THREE
 
     def consume_request(self, request_info: http_messages.RequestInfo) -> None:
         return None
diff --git a/src/hydrilla/proxy/policies/payload.py b/src/hydrilla/proxy/policies/payload.py
index 76a1202..3252c6a 100644
--- a/src/hydrilla/proxy/policies/payload.py
+++ b/src/hydrilla/proxy/policies/payload.py
@@ -105,10 +105,9 @@ def block_attr(element: bs4.PageElement, attr_name: str) -> None:
 
 @dc.dataclass(frozen=True)
 class PayloadInjectPolicy(PayloadAwarePolicy):
-    """...."""
-    _process_response: t.ClassVar[bool] = True
+    _process_response = base.MsgProcessOpt.MUST
 
-    priority: t.ClassVar[base.PolicyPriority] = base.PolicyPriority._TWO
+    priority = base.PolicyPriority._TWO
 
     @property
     def current_popup_settings(self) -> state.PopupSettings:
@@ -179,8 +178,7 @@ class _PayloadHasProblemsError(HaketiloException):
     pass
 
 class AutoPayloadInjectPolicy(PayloadInjectPolicy):
-    """...."""
-    priority: t.ClassVar[base.PolicyPriority] = base.PolicyPriority._ONE
+    priority = base.PolicyPriority._ONE
 
     def consume_response(self, http_info: http_messages.FullHTTPInfo) \
         -> t.Optional[http_messages.ResponseInfo]:
@@ -217,10 +215,10 @@ class AutoPayloadInjectPolicy(PayloadInjectPolicy):
 
 @dc.dataclass(frozen=True)
 class PayloadSuggestPolicy(PayloadAwarePolicy):
-    """...."""
-    _process_request: t.ClassVar[bool] = True
+    _process_request  = base.MsgProcessOpt.MUST
+    _process_response = base.MsgProcessOpt.MUST_NOT
 
-    priority: t.ClassVar[base.PolicyPriority] = base.PolicyPriority._ONE
+    priority = base.PolicyPriority._ONE
 
     def consume_request(self, request_info: http_messages.RequestInfo) \
         -> http_messages.ResponseInfo:
diff --git a/src/hydrilla/proxy/policies/payload_resource.py b/src/hydrilla/proxy/policies/payload_resource.py
index d8e5ea5..38cfd21 100644
--- a/src/hydrilla/proxy/policies/payload_resource.py
+++ b/src/hydrilla/proxy/policies/payload_resource.py
@@ -212,10 +212,9 @@ MessageInfo = t.Union[
 
 @dc.dataclass(frozen=True)
 class PayloadResourcePolicy(PayloadAwarePolicy):
-    """...."""
-    _process_request: t.ClassVar[bool] = True
+    _process_request = base.MsgProcessOpt.MUST
 
-    priority: t.ClassVar[base.PolicyPriority] = base.PolicyPriority._THREE
+    priority = base.PolicyPriority._THREE
 
     def extract_resource_path(self, request_url: ParsedUrl) -> tuple[str, ...]:
         # Payload resource pattern has path of the form:
@@ -370,10 +369,10 @@ resource_blocked_response = http_messages.ResponseInfo.make(
 
 @dc.dataclass(frozen=True)
 class BlockedResponsePolicy(base.Policy):
-    """...."""
-    _process_request: t.ClassVar[bool] = True
+    _process_request  = base.MsgProcessOpt.MUST
+    _process_response = base.MsgProcessOpt.MUST_NOT
 
-    priority: t.ClassVar[base.PolicyPriority] = base.PolicyPriority._THREE
+    priority = base.PolicyPriority._THREE
 
     def consume_request(self, request_info: http_messages.RequestInfo) \
         -> http_messages.ResponseInfo:
diff --git a/src/hydrilla/proxy/policies/rule.py b/src/hydrilla/proxy/policies/rule.py
index 2a6d8cb..8c5e69b 100644
--- a/src/hydrilla/proxy/policies/rule.py
+++ b/src/hydrilla/proxy/policies/rule.py
@@ -40,17 +40,15 @@ from . import base
 
 
 class AllowPolicy(base.Policy):
-    """...."""
-    priority: t.ClassVar[base.PolicyPriority] = base.PolicyPriority._TWO
+    priority = base.PolicyPriority._TWO
 
 
 script_csp_directives = ('script-src', 'script-src-elem', 'script-src-attr')
 
 class BlockPolicy(base.Policy):
-    """...."""
-    _process_response: t.ClassVar[bool] = True
+    _process_response = base.MsgProcessOpt.MUST
 
-    priority: t.ClassVar[base.PolicyPriority] = base.PolicyPriority._TWO
+    priority = base.PolicyPriority._TWO
 
     @property
     def current_popup_settings(self) -> state.PopupSettings:
@@ -67,13 +65,11 @@ class BlockPolicy(base.Policy):
 
 @dc.dataclass(frozen=True)
 class RuleAllowPolicy(AllowPolicy):
-    """...."""
     pattern: ParsedPattern
 
 
 @dc.dataclass(frozen=True)
 class RuleBlockPolicy(BlockPolicy):
-    """...."""
     pattern: ParsedPattern
 
 
diff --git a/src/hydrilla/proxy/policies/web_ui.py b/src/hydrilla/proxy/policies/web_ui.py
index 74a0655..1c32ea9 100644
--- a/src/hydrilla/proxy/policies/web_ui.py
+++ b/src/hydrilla/proxy/policies/web_ui.py
@@ -41,10 +41,10 @@ from . import base
 
 @dc.dataclass(frozen=True)
 class WebUIPolicy(base.Policy):
-    """...."""
-    _process_request:  t.ClassVar[bool] = True
+    _process_request  = base.MsgProcessOpt.MUST
+    _process_response = base.MsgProcessOpt.MUST_NOT
 
-    priority: t.ClassVar[base.PolicyPriority] = base.PolicyPriority._THREE
+    priority = base.PolicyPriority._THREE
 
     haketilo_state: state.HaketiloState
     ui_domain:      web_ui.UIDomain