Cpp bindings: Return false from Validator::Accept() on unrecognized message or invalid flags

mojo/public/tools/bindings/generators/cpp_templates/interface_definition.tmpl

 {%- import "interface_macros.tmpl" as interface_macros %}
 {%- import "struct_macros.tmpl" as struct_macros %}
 {%- set class_name = interface.name %}
 {%- set proxy_name = interface.name ~ "Proxy" %}
 {%- set namespace_as_string = "%s"|format(namespace|replace(".","::")) %}
 
 {%- macro alloc_params(struct) %}
 {%-   for param in struct.packed.packed_fields_in_ordinal_order %}
   {{param.field.kind|cpp_result_type}} p_{{param.field.name}}{};
 {%-   endfor %}
@@ skipping 203 matching lines @@
 }
 
 {#--- Request validator definitions #}
 
 {{class_name}}RequestValidator::{{class_name}}RequestValidator(
     mojo::MessageReceiver* sink) : MessageFilter(sink) {
 }
 
 bool {{class_name}}RequestValidator::Accept(mojo::Message* message) {
 {%- if interface.methods %}
+  if (message->has_flag(mojo::internal::kMessageIsResponse)) {
+    ReportValidationError(
+        mojo::internal::VALIDATION_ERROR_MESSAGE_HEADER_INVALID_FLAG_COMBINATION);

[yzshen1, 2015/03/03 18:05:37]

(1) Do you think we should rename this error? -- because the fact that it is
invalid is NOT because the flag "combination" is invalid. The error was designed
to indicate error such as having ExpectsResponse and IsResponse at the same
time.

(2) Please add tests for all the new failures.

[rudominer, 2015/03/04 00:12:01]

Let's do this in a separate CL. I filed b/463684
Done

+    return false;
+  }
   switch (message->header()->name) {
 {%-   for method in interface.methods %}
     case internal::k{{class_name}}_{{method.name}}_Name: {
 {%-     if method.response_parameters != None %}
-      if (!message->has_flag(mojo::internal::kMessageExpectsResponse))
-        break;
+      if (!message->has_flag(mojo::internal::kMessageExpectsResponse)) {
+        ReportValidationError(
+            mojo::internal::VALIDATION_ERROR_MESSAGE_HEADER_INVALID_FLAG_COMBINATION);
+        return false;
+      }
 {%-     else %}
-      if (message->has_flag(mojo::internal::kMessageExpectsResponse) ||
-          message->has_flag(mojo::internal::kMessageIsResponse)) {
-        break;
+      if (message->has_flag(mojo::internal::kMessageExpectsResponse)) {
+        ReportValidationError(
+            mojo::internal::VALIDATION_ERROR_MESSAGE_HEADER_INVALID_FLAG_COMBINATION);
+        return false;
       }
 {%-     endif %}
       mojo::internal::BoundsChecker bounds_checker(
           message->payload(), message->payload_num_bytes(),
           message->handles()->size());
       if (!internal::{{class_name}}_{{method.name}}_Params_Data::Validate(
               message->payload(), &bounds_checker)) {
         return false;
       }
       break;
     }
 {%-   endfor %}
+    default: {
+      // Unrecognized message.
+      ReportValidationError(
+          mojo::internal::VALIDATION_ERROR_MESSAGE_HEADER_UNKNOWN_METHOD);
+      return false;
+    }
   }
 {%- endif %}
 
   assert(sink_);
   return sink_->Accept(message);
 }
 
 {#--- Response validator definitions #}
 {% if interface|has_callbacks %}
 {{class_name}}ResponseValidator::{{class_name}}ResponseValidator(
     mojo::MessageReceiver* sink) : MessageFilter(sink) {
 }
 
 bool {{class_name}}ResponseValidator::Accept(mojo::Message* message) {
 {%- if interface.methods %}
+  if (!message->has_flag(mojo::internal::kMessageIsResponse)) {
+    ReportValidationError(
+        mojo::internal::VALIDATION_ERROR_MESSAGE_HEADER_INVALID_FLAG_COMBINATION);
+    return false;
+  }
   switch (message->header()->name) {
 {%-   for method in interface.methods if method.response_parameters != None %}
     case internal::k{{class_name}}_{{method.name}}_Name: {
-      if (!message->has_flag(mojo::internal::kMessageIsResponse))
-        break;
       mojo::internal::BoundsChecker bounds_checker(
           message->payload(), message->payload_num_bytes(),
           message->handles()->size());
       if (!internal::{{class_name}}_{{method.name}}_ResponseParams_Data::Validate(
               message->payload(), &bounds_checker)) {
         return false;
       }
       break;
     }
 {%-   endfor %}
+    default: {
+      // Unrecognized message.
+      ReportValidationError(
+          mojo::internal::VALIDATION_ERROR_MESSAGE_HEADER_UNKNOWN_METHOD);
+      return false;
+    }
   }
 {%- endif %}
 
   assert(sink_);
   return sink_->Accept(message);
 }
 {%- endif -%}