GetModuleType and derivatives should respect .NET Core / .NET 5+ behavior

[Washi1337]

AsmResolver Version

5.0.0

.NET Version

.NET 6.0

Operating System

Windows

Describe the Bug

While in .NET Framework the module type (<Module>) is always considered to be the first type in the TypeDef metadata table (i.e., token 0x02000001), .NET Core also checks whether this type is actually called <Module>. This behavior is currently not reflected in ModuleDefinition.GetModuleType() and derivatives.

How To Reproduce

With the following sample binaries:

ModuleCctor.zip

Run the following code:

string[] paths = {
    "ModuleCctorNetFramework.exe",
    "ModuleCctorNet6.dll",
    "ModuleCctorAbsentNet6.dll",
    "ModuleCctorLookalikeNet6.dll",
};

foreach (string path in paths)
{
    var module = ModuleDefinition.FromFile(path);
    Console.WriteLine(path + ": " + (module.GetModuleType()?.FullName ?? "No <Module> type."));
}

Expected Behavior

ModuleCctorNetFramework.exe: CustomModuleType
ModuleCctorNet6.dll: <Module>
ModuleCctorAbsentNet6.dll: No <Module> type.
ModuleCctorLookalikeNet6.dll: No <Module> type.

Actual Behavior

ModuleCctorNetFramework.exe: CustomModuleType
ModuleCctorNet6.dll: <Module>
ModuleCctorAbsentNet6.dll: <Module>
ModuleCctorLookalikeNet6.dll: Program

Additional Context

No response