' ***********************************************************************
' Author   : Elektro
' Modified : 11-January-2017
' ***********************************************************************

#Region " Public Members Summary "

#Region " Methods "

' Execute(Byte())
' Execute(Byte(), Object())

' ExecuteSafe(Byte())
' ExecuteSafe(Byte(), Object())

#End Region

#End Region

#Region " Option Statements "

Option Strict On
Option Explicit On
Option Infer Off

#End Region

#Region " Imports "

Imports System.Reflection
Imports System.Security
Imports System.Security.Permissions

#End Region

#Region " Resource Util "

Namespace Resources.Tools

    Partial Public NotInheritable Class ResourceUtil

#Region " Public Methods "

        ''' ----------------------------------------------------------------------------------------------------
        ''' <summary>
        ''' Loads a resource in memory and executes its main entrypoint.
        ''' <para></para>
        ''' The resource must be a .NET assembly.
        ''' </summary>
        ''' ----------------------------------------------------------------------------------------------------
        ''' <example> This is a code example.
        ''' <code>
        ''' Execute(My.Resources.MyProgram)
        ''' </code>
        ''' </example>
        ''' ----------------------------------------------------------------------------------------------------
        ''' <param name="resource">
        ''' The resource to execute.
        ''' </param>
        ''' ----------------------------------------------------------------------------------------------------
        ''' <exception cref="EntryPointNotFoundException">
        ''' Entrypoint not found in the specified resource. Are you sure it is a .NET assembly?
        ''' </exception>
        ''' ----------------------------------------------------------------------------------------------------
        <DebuggerStepThrough>
        Public Shared Sub Execute(ByVal resource As Byte())
            ResourceUtil.Execute(resource, Nothing)
        End Sub

        ''' ----------------------------------------------------------------------------------------------------
        ''' <summary>
        ''' Loads a resource in memory and executes its main entrypoint.
        ''' <para></para>
        ''' The resource must be a .NET assembly.
        ''' </summary>
        ''' ----------------------------------------------------------------------------------------------------
        ''' <example> This is a code example.
        ''' <code>
        ''' Execute(My.Resources.MyProgram, {"Parameter 1", "Parameter 2", "etc..."})
        ''' </code>
        ''' </example>
        ''' ----------------------------------------------------------------------------------------------------
        ''' <param name="resource">
        ''' The resource to execute.
        ''' </param>
        '''
        ''' <param name="parameters">
        ''' The parameters to pass to the method executed.
        ''' </param>
        ''' ----------------------------------------------------------------------------------------------------
        ''' <exception cref="EntryPointNotFoundException">
        ''' Entrypoint not found in the specified resource. Are you sure it is a .NET assembly?
        ''' </exception>
        ''' ----------------------------------------------------------------------------------------------------
        <DebuggerStepThrough>
        Public Shared Sub Execute(ByVal resource As Byte(), ByVal parameters As Object())
            Dim helper As New ExecuteHelper()
            helper.LoadAssembly(resource, parameters)
        End Sub

        ''' ----------------------------------------------------------------------------------------------------
        ''' <summary>
        ''' Loads a resource in memory and executes its main entrypoint.
        ''' <para></para>
        ''' The resource must be a .NET assembly.
        ''' <para></para>
        ''' If the loaded assembly attempts to force an application termination
        ''' by for example internaly calling <see cref="Environment.Exit"/>, then the call is catched and ignored.
        ''' <para></para>
        ''' The downside is that the loaded assembly will not be able to call (P/Invoke) unmanaged code. You are advised.
        ''' <para></para>
        ''' *** Note that this is a experimental methodology. ***
        ''' </summary>
        ''' ----------------------------------------------------------------------------------------------------
        ''' <example> This is a code example.
        ''' <code>
        ''' ExecuteSafe(My.Resources.MyProgram)
        ''' </code>
        ''' </example>
        ''' ----------------------------------------------------------------------------------------------------
        ''' <param name="resource">
        ''' The resource to execute.
        ''' </param>
        ''' ----------------------------------------------------------------------------------------------------
        ''' <exception cref="EntryPointNotFoundException">
        ''' Entrypoint not found in the specified resource. Are you sure it is a .NET assembly?
        ''' </exception>
        ''' ----------------------------------------------------------------------------------------------------
        <DebuggerStepThrough>
        Public Shared Sub ExecuteSafe(ByVal resource As Byte())
            ResourceUtil.ExecuteSafe(resource, Nothing)
        End Sub

        ''' ----------------------------------------------------------------------------------------------------
        ''' <summary>
        ''' Loads a resource in memory and executes its main entrypoint.
        ''' <para></para>
        ''' The resource must be a .NET assembly.
        ''' <para></para>
        ''' If the loaded assembly attempts to force an application termination
        ''' by for example internaly calling <see cref="Environment.Exit"/>, then the call is catched and ignored.
        ''' <para></para>
        ''' The downside is that the loaded assembly will not be able to call (P/Invoke) unmanaged code. You are advised.
        ''' <para></para>
        ''' *** Note that this is a experimental methodology. ***
        ''' </summary>
        ''' ----------------------------------------------------------------------------------------------------
        ''' <example> This is a code example.
        ''' <code>
        ''' ExecuteSafe(My.Resources.MyProgram, {"Parameter 1", "Parameter 2", "etc..."})
        ''' </code>
        ''' </example>
        ''' ----------------------------------------------------------------------------------------------------
        ''' <param name="resource">
        ''' The resource to execute.
        ''' </param>
        '''
        ''' <param name="parameters">
        ''' The parameters to pass to the method executed.
        ''' </param>
        ''' ----------------------------------------------------------------------------------------------------
        ''' <exception cref="EntryPointNotFoundException">
        ''' Entrypoint not found in the specified resource. Are you sure it is a .NET assembly?
        ''' </exception>
        ''' ----------------------------------------------------------------------------------------------------
        <DebuggerStepThrough>
        Public Shared Sub ExecuteSafe(ByVal resource As Byte(), ByVal parameters As Object())

            ' This is where the main executable resides. For more info on this, see "Remarks" in
            ' https://msdn.microsoft.com/en-us/library/system.appdomainsetup.applicationbase(v=vs.110).aspx#Anchor_1
            Dim adSetup As New AppDomainSetup()
            adSetup.ApplicationBase = AppDomain.CurrentDomain.BaseDirectory

            ' Permissions of the AppDomain/what it can do.
            Dim permission As New PermissionSet(PermissionState.None)
            With permission
                ' All SecurityPermission flags EXCEPT UnmanagedCode, which is required by Environment.Exit() method.
                .AddPermission(New SecurityPermission(SecurityPermissionFlag.AllFlags And Not SecurityPermissionFlag.UnmanagedCode))
                .AddPermission(New EnvironmentPermission(PermissionState.Unrestricted))
                .AddPermission(New EventLogPermission(PermissionState.Unrestricted))
                .AddPermission(New FileDialogPermission(PermissionState.Unrestricted))
                .AddPermission(New FileIOPermission(PermissionState.Unrestricted))
                .AddPermission(New GacIdentityPermission(PermissionState.Unrestricted))
                .AddPermission(New IsolatedStorageFilePermission(PermissionState.Unrestricted))
                .AddPermission(New KeyContainerPermission(PermissionState.Unrestricted))
                .AddPermission(New PerformanceCounterPermission(PermissionState.Unrestricted))
                .AddPermission(New PrincipalPermission(PermissionState.Unrestricted))
                .AddPermission(New ReflectionPermission(PermissionState.Unrestricted))
                .AddPermission(New RegistryPermission(PermissionState.Unrestricted))
                .AddPermission(New SiteIdentityPermission(PermissionState.Unrestricted))
                .AddPermission(New StorePermission(PermissionState.Unrestricted))
                .AddPermission(New TypeDescriptorPermission(PermissionState.Unrestricted))
                .AddPermission(New UIPermission(PermissionState.Unrestricted))
                .AddPermission(New UrlIdentityPermission(PermissionState.Unrestricted))
                .AddPermission(New ZoneIdentityPermission(PermissionState.Unrestricted))
            End With

            ' Our sandboxed AppDomain.
            Dim domain As AppDomain = AppDomain.CreateDomain("SomeGenericName", Nothing, adSetup, permission, Nothing)

            Try
                ' Create an instance of Helper in the sandboxed AppDomain.
                Dim helper As ExecuteHelper = DirectCast(domain.CreateInstanceAndUnwrap(GetType(ExecuteHelper).Assembly.FullName, GetType(ExecuteHelper).FullName), ExecuteHelper)
                helper.LoadAssembly(resource, parameters)

            Catch ex As TargetInvocationException When (ex.InnerException.GetType() = GetType(SecurityException))
                ' Some kind of permissions issue occured here, possibly an attempt to call Environment.Exit() or call (P/Invoke) unmanaged code.
                ' Do Nothing.

            Catch ex As Exception
                Throw

            End Try

        End Sub

#End Region

    End Class

    ''' ----------------------------------------------------------------------------------------------------
    ''' <summary>
    ''' A class that serves to execute assemblies that are stored as application resource (eg. My.Resources.MyProgram1 )
    ''' </summary>
    ''' ----------------------------------------------------------------------------------------------------
    Friend NotInheritable Class ExecuteHelper : Inherits MarshalByRefObject

        ''' ----------------------------------------------------------------------------------------------------
        ''' <summary>
        ''' Loads the assembly.
        ''' </summary>
        ''' ----------------------------------------------------------------------------------------------------
        ''' <param name="bytes">
        ''' The bytes of the assembly/resource to execute.
        ''' </param>
        '''
        ''' <param name="parameters">
        ''' The parameters to pass to the method executed.
        ''' </param>
        ''' ----------------------------------------------------------------------------------------------------
        ''' <exception cref="EntryPointNotFoundException">
        ''' Entrypoint not found in the specified resource. Are you sure it is a .NET assembly?
        ''' </exception>
        ''' ----------------------------------------------------------------------------------------------------
        Public Sub LoadAssembly(ByVal bytes As Byte(), ByVal parameters As Object())
            Dim ass As Assembly = Assembly.Load(bytes)
            Dim method As MethodInfo = ass.EntryPoint

            If (method IsNot Nothing) Then
                Dim instance As Object = ass.CreateInstance(method.Name)
                method.Invoke(instance, parameters)
                If (instance IsNot Nothing) AndAlso (instance.GetType().GetInterfaces.Contains(GetType(IDisposable))) Then
                    DirectCast(instance, IDisposable).Dispose()
                End If
                instance = Nothing
                method = Nothing
                ass = Nothing

            Else
                Throw New EntryPointNotFoundException("Entrypoint not found in the specified resource. Are you sure it is a .NET assembly?")

            End If
        End Sub

    End Class

End Namespace

#End Region