dotnet: emit enclosing class information for nested classes

[mike-hunhoff]

capa does not emit the <namespace>.<class> of the class that encloses a nested class.

e.g when processing Settings.System::PutInt, capa emits only System::PutInt when ideally capa would emit something like Android.Provider.Settings.System::PutInt.

The suggestion of using Android.Provider.Settings.System::PutInt could be confusing though because, based on how capa currently treats namespaces + classes, this makes it appear that Android.Provider.Settings is a namespace when it is a class. Alternately, capa could take the same route as dnSpy by emitting Android.Provider.Settings/System::PutInt where / denotes a nested class signifying that Android.Provider.Settings is the enclosing class and System is the nested class.

How should capa emit features for Android.Provider.Settings/System::PutInt?

capa currently emits:

• namespace(Android.Provider)
• class(Android.Provider.Settings)
• class(System)
• import(System::PutInt)
• api(System::PutInt)

I propose that capa emit:

• namespace(Android.Provider)
• class(Android.Provider.Settings)
• class(Android.Provider.Settings/System)
• import(Android.Provider.Settings/System::PutInt)
• api(Android.Provider.Settings/System::PutInt)

Reading the ECMA specs, I can't find anything that states a max nesting depth for .NET types. Therefore, we should not assume a max depth when coding this new feature.

capa should handle nested classes for both locally defined (TypeDef) classes and imported (TypeRef) classes. For TypeDef classes, capa should be able to use the NestedClasses (0x29) table. For TypeRef classes, capa should be able to use the ResolutionScope index where a TypeRef is nested if its ResolutionScope index is a TypeRef index.

[bkojusner]

Working on it!