Monthly Archives: October 2011

Back In Business!

0
Filed under Uncategorized

Looks like I’ve finally gotten things sorted with WordPress and permalinks, the 404-handler.php and URLRewriting. Ugh. Many thanks to the guys at servergrid for being patient while I worked through all this to get things back online!

The Email Me Contact form even works again (finally!).

Direct integration of ILMerge with VB.net Projects

0
Filed under .NET, Error Handling, MSBuild, Troubleshooting

I’ve been working on a few utility type applications lately (more on them later, once they’re firmed up), but one thing I’ve found incredibly useful for certain projects is ILMerge.

If you’re not familiar with it, ILMerge is a utility that essentially can combine two or more .net assemblies into a single assembly, and reducing an application’s footprint is something I’m particularly passionate about!

In the past, I’ve always created postbuild steps that included executing ILMerge as just a command line post build process, but doing it this way has always been problematic. To start, debugging in the IDE tends to be compromised at best, and not possible at worst. Plus it just never felt clean.

In researching the problem, I ran across three blog posts that have provided more than enough info to get me past the Post Build process and actually integrate ILMerge directly into the build process itself, and one very intriguing alternative.

First, Scott Hanselman wrote about his experiences using ILMerge to merge a VB.net assembly into an otherwise C# project back in 2007. A great article and a fantastic first step.

Then, I came across Daniel Fortunov’s  article about integrating ILMerge into the VS build process. His example is also very good and a little cleaner, I’d say than Scott’s approach, but both articles are definitely worth checking out if you find yourself needing this kind of thing.

Lastly, Jeffrey Richter wrote a terrifically short but incredibly eye-popping article about a technique to load .net assemblies dynamically from binary resources baked into a single assembly at compile time. Very simple and clean. A great technique to have in your toolbox if the need ever arises.

For my part, I’ve used the ILMerge technique to merge Mono.Cecil.dll (a C# library from the mono project for directly altering .net assemblies) into a VB.net utility that can repackage portions of an assembly’s PDB file directly into the assembly’s EXE or DLL file, to supply line numbers during the rendering of an exception’s stack trace without actually have to provide a PDB (and all the additional metadata about your assembly) to your client. A fantastic debugging technique and one that I’ve been working with (off and on) for several years now. I’ll write about it in more detail later.

VB6 Menus Disabled

0
Filed under Troubleshooting, VB6

In my current job, I have to do some maintenance on some legacy VB6 code. Yeah, its archaic by .net standards, but there’s something….comforting I guess…. about VB6. I spent almost 10 years with that language, so at this point, I know it just about as good as anyone, save maybe Bruce Kenney or Matthew Curland.

At any rate, I’ve been working with it over the last few weeks and happened today to notice that the Bookmarks menu items were all disabled, even when the cursor was located somewhere where I should be able to set a bookmark. You can see the menu items in the screenshots below. Note that in these shots, then menu items are enabled properly. I didn’t think to grab clips before trying to resolve this.

image    image

At first, I thought the problem was with one of the Addins I’d been playing with (CodeSmart, MZTools, etc).

But disabling them didn’t make a difference. Of course, it’s completely possible that an addin did the damage and VB just never “fixed itself” but I have no way of knowing.

The Fix

After playing with several possibilities and even scanning through the registry, I ended up with this simple fix.

Right Click on the menu bar, select Customize, you’ll get this window.

image

For each of the items highlighted above (and the others if you suspect problems there too), click the item and click the RESET button.

That’s it!

Simple. No reboots required. You don’t even have to restart VB.

Self-Registering COM .net Assemblies

10
Filed under .NET, Utilities

One of the big benefits of the .net system is the fact that it doesn’t rely on COM and the registry to find referenced assemblies. At it’s simplest, the .net loader (which is responsible for resolving external assembly references) looks in the same folder as the assembly that contains the reference, and if the referenced assembly is there, it’s loaded. Done.

Why on earth COM couldn’t have been this way from the beginning is beyond me (ok, actually it’s not, there were plenty of, at least at the time, what appeared to be good arguments for putting all that registration stuff in the registry, but that’s a whole different posting).

At any rate, the new style .net assembly resolution rules work great for .net assemblies, but not with .net assemblies that expose COM objects. And I’m still seeing plenty of projects where COM integration is a primary component. For various reasons, the code for these projects needs to be in .net, so that has left me having to deal with .net COM interop on more than one occasion.

UPDATE: 10/15/2011

I just discovered the <ComRegisterFunction> and <ComUnregisterFunction> attributes, which, initially, I thought might automatically do everything this entire post is about. Doh!

However, that’s not the case. These two attributes can be attached to functions that will be called by REGASM.EXE during dll registration or unregistration. But they do not create the standard dll entry points "DllRegisterServer” and “DllUnregisterServer”. Hence, even if you use these two attributes, you would still have a COM .net assembly that would have to be registered via RegAsm.

Fly in the Ointment

In all honesty, .net COM interop is not too bad. If you know how to use interfaces, the <COMCLASS> attribute, and a few other particular attributes, it’s not much more difficult to create COM components in .net (C# or VB) than it was to create them in VB6.

Except for one thing.

Registration.

COM Components pretty much have to be registered in the registry (ok there’s registry free COM, but that’s another article as well and it’s not often used). For registering COM dlls, the tool of choice has long been REGSVR32.exe. Unfortunately, self registering COM dlls require 2 C-Style entry points, called DLLRegisterServer and DLLUnregisterServer for RegSvr32 to work it’s magic and register or unregister the COM dll. You can see these entry points (and typically 2 others, DllCanUnloadNow and DllGetClassObject) if you open up just about any COM dll in DependencyViewer:

image

Registering a COM .net Assembly

After a little poking around on Google, I came across the RegistrationServices object. This object provides everything you need to register and unregister a COM .net assembly.

Here’s a snippet to actually register a .net assembly that exposed COM objects:

Dim asm = Assembly.LoadFile(AssemblyName)
Dim regAsm = New RegistrationServices()
Dim bResult = regAsm.RegisterAssembly(asm, AssemblyRegistrationFlags.SetCodeBase)

The Unregistration process is very similar.

The Typical Situation

The most common time that a COM dll is registered or unregistered is at installation or uninstallation time. The Windows Installer contains plenty of functionality to register and unregister COM dlls, and .net assemblies, so generally speaking, you often don’t need to even worry whether you COM .net assemblies can be self registered or not, because Windows Installer can automatically handle them.

However, if you want to distribute a dll with no install (maybe an xcopy deployment scenario, or any other situation where an full blown install would be more work than it’s worth), the scene isn’t so pretty. For your COM .net assembly to be registered properly, it will need to have REGASM run on it. REGASM is the .net version of REGSVR32.exe. Unfortunately, REGSVR32 is on the path of every Windows machine out there, so it can be run from anywhere on your system.

REGASM, however, is not. And finding it is often no picknick.

The Ideal Solution

In a perfect world, the Register for COM Interop option in the Visual Studio project options screen, would automatically create the required DLLRegisterServer and DLLUnRegisterServer entry points for you, just like VB6 did. After all, all that’s really necessary for that functions is a call to the RegistrationServices object as detailed above, pointing to the currently running assembly! It’s a trivial bit of code.

But alas, that minor detail was left out.

The Work Around (or ILAsm to the Rescue)

At this point, I knew how to register and unregister COM assemblies. I knew how RegSvr32 functions internally (all it does is perform a LoadLibrary on the given DLL file, attempt to retrieve the procaddress of the DllRegisterServer or DllUnregisterServer functions, call them if they exist, and fail with an error if they don’t).

The only thing missing was how to expose those two functions from a .net assembly as a standard C-style dll entrypoint.

It turns out that neither C# nor VB, at this point, can flag functions to be exported as entry points.

But…. msil (Microsoft intermediate language, what any .net app is initially compiled into) can.

And doing so is quite common knowledge. I’ve actually written about it before, most recently here.

That post mentions the original source for the DLLExport idea and provides a background and code, so I won’t replicate that here. Suffice it to say that essentially, what tools like this do is take a compiled. .net assembly, in which certain methods have been marked with a particular attribute, disassemble the assembly, tweak the resulting IL code slightly to expose those attributed functions as real entry points and then use ILASM to reassemble the tweaked code back into a normal assembly, only now with the entry points exposed.

So, to create a self-registering COM .net assembly, all that’s really necessary is to include this DLLRegister class in your project (along with the DLLExportAttribute class mentioned in the link above):

Imports System.Runtime.InteropServices
Imports System.Reflection

''' <summary>
''' Provides Self-Registration functions for COM exposed .net assemblies
''' </summary>
''' <remarks></remarks>
Public Class DllRegisterFunctions
    Public Const S_OK As Integer = 0
    Public Const SELFREG_E_TYPELIB = &H80040200
    Public Const SELFREG_E_CLASS = &H80040201

    <DllExport.DllExport("DllRegisterServer", CallingConvention.Cdecl)> _
    Public Shared Function DllRegisterServer() As Integer
        Try
            Dim asm = Assembly.LoadFile(Assembly.GetExecutingAssembly.Location)
            Dim regAsm = New RegistrationServices()
            Dim bResult = regAsm.RegisterAssembly(asm, AssemblyRegistrationFlags.SetCodeBase)
            Return S_OK
        Catch ex As Exception
            Return SELFREG_E_TYPELIB
        End Try
    End Function

    <DllExport.DllExport("DllUnregisterServer", CallingConvention.Cdecl)> _
    Public Shared Function DllUnregisterServer() As Integer
        Try
            Dim asm = Assembly.LoadFile(Assembly.GetExecutingAssembly.Location)
            Dim regAsm = New RegistrationServices()
            Dim bResult = regAsm.UnregisterAssembly(asm)
            Return S_OK
        Catch ex As Exception
            Return SELFREG_E_TYPELIB
        End Try
    End Function
End Class

compile the dll, run DLLExport utility on the dll to expose these marked functions, and presto, done!

But wait, There’s More!

This is all well and good, and it definitely works, but using a post-compile process like this is certainly not ideal. If you’ve signed or strong-named your dll during the compile process, that information will be lost during the recompile. Worse, your debugging PDB will not follow through, so debugging the post-processed dll can be tricky as well.

It’d be great is .net had a linker, and we could just link a precompiled OBJ file in that already contained the DllRegister and Unregister functions and export points. Unfortunately, .net doesn’t have a linking process.

A Dead End

However, there is a very nifty utility called ILMerge that CAN merge two or more .net assemblies into one. “Perfect!” I thought, but a quick test resulted in an error from ILMerge indicating that “one or more assemblies contains unmanaged code”. I can only guess that ILMerge doesn’t support exported entry points like this, at least not yet.

I’m Not Dead Yet!

A few days passed, and I was searching for a solution to a completely unrelated issue when I happened upon a page describing Microsoft’s Side-by-Side functionality. Something about the SxS extensions they use all over the place gave me an idea.

If all that the RegistrationServices object needs to register a COM .net dll is the filename, why not create a stub registration dll that contains DllRegisterServer and DllUnregisterServer functions that actually register a side by side dll that contains the actual  COM objects.

So, say you have a dll called MyDll.dll.

Under this scenario, you’d actually put your code into a dll called MyDllSxS.dll (side by side, get it <g>) and then just make a copy of this self-register handling dll and call it MyDll.dll.

When someone runs regsvr32 mydll.dll, the DllRegisterServer function in the stub actually registers the MyDllSxS.dll.

The stub then, is exactly the same for any self-registering COM .net assembly and can just be copied side-by-side as much as necessary.

Granted, this approach does increase the overall application footprint (since there are additional dlls to distribute), but because the extra files are very small (16k or so) and all exactly the same, I don’t see this as a huge issue.

Still Not Perfect

Unfortunately, even though the above approach works great, is simple, and doesn’t require peculiar compilation steps on your codebase, it does still mean you do have a second dll to distribute. And, realistically, if you’re going to do that, why not instead create a little EXE than gets distributed with your app and does the exact same thing as the DllRegisterServer and DllUnregisterServer functions?

Well, honestly, I don’t have a good answer for that. In truth, RegAsm does a little more than just registering and unregistering COM .net assemblies. But for general usage in the field, those two functions are all you really normally need, and building a quick console app to do just that is trivial given the above code.

At then end of the day, for those projects that need COM integration, I’ll probably just include the DLLExportAttribute directly in the project, include the DllRegisterFunctions class to supply the necessary entry points,  and finally run DLLExport on the compiled DLL in the Release mode build of the project to actual export those entry points.

It’s not ideal, but:

  • It works
  • It doesn’t require any  more DLLs than you’d otherwise include in the project
  • It’s not terribly onerous to implement
  • The resulting dlls register and unregister just as a savvy user would expect them to, via regsvr32.

Exposing C-Style Entry Points in a .net Assembly (revisited)

6
Filed under .NET, Code Garage

I’ve written about exposing Entry Points from a .net dll before, most recently here.

But I recently came across another take on the subject that was so clean, I thought I’d record it and a link here, just to be complete.

First, a little background. Occasionally, I’ve found I have need to expose standard c-style entry points from a .net dll. This usually centers around integrating with some application, typically plugins, where the hosting app attempts to use LoadLibrary on your dll and then resolve a specific entrypoint via GetProcAddress.

I’ve done this kind of thing in a variety of ways, C or C++ wrappers, ASM, etc, but .net doesn’t provide any way to expose entry points.

Or does it?

In reality, neither C# or VB.net allow such functionality, but MSIL (Microsoft Intermediate Language) does. In fact, this has been around for so long, there’s actually several different approaches to implementing this functionality out on the web.

The two I know about are:

I had some troubles with Selvin’s version, but Mr. Giesecke’s version resolved the issue nicely at the time.

However, after looking over the 3’rd option, I have to say I like it a little more. I should point out, though, that I’ve only used Mr. Giesecke’s approach with .net 3.5, and the other approach with .net 4.0, so keep that in mind.

Essentially, the way these utilities work is to use ILDASM to disassembly a compiled .net assembly, they then read the resulting IL file, tweak it in a few specific ways, and finally use ILASM to reassemble the project.

One important note here: ILASM.exe actually comes with the .net runtime and as such, it’s already on your computer if you have the .net runtime installed.

On the other hand, ILDASM comes with the .net framework SDK, which is NOT part of the framework runtime. You’ll need to download and install the SDK in order to have ILDASM available. You can get the 2.0 SDK here.

On to the Code

Mr. Giesecke’s utility is well documented and I won’t reproduce that here.

The source code for the other utility I mentioned was posted by the author in a forum thread. It’s C#, and well, this is VBFengShui, plus I wanted to ferret through it and understand what was going on a little more than I had in the past, so converting it to VB seemed like a good idea. Plus I cleaned up a few minor nits here and there to boot.

The final program is listed below. It’s fully contained in a single class. It’s long, but not that long.

Imports System.Text
Imports System.IO
Imports System.Reflection
Imports Microsoft.Win32
Imports System.ComponentModel
Imports System.Runtime.InteropServices
Imports System.Runtime.CompilerServices

Namespace DllExport
    '
    '   Export native 64bit method from .NET assembly
    '   =============================================
    '   Adapted from code found here
    '   http://social.msdn.microsoft.com/Forums/en-US/clr/thread/8648ff5e-c599-42e4-b873-6b91205a5c93/
    '
    '   More info
    '   http://msdn.microsoft.com/en-us/library/ww9a897z.aspx
    '   http://stackoverflow.com/questions/2378730/register-a-c-vb-net-com-dll-programatically
    '
    '
    '   ==================================
    '   Comments from the original project
    '   ==================================
    '   It is well known fact that .NET assembly could be tweaked to export native method,
    '   similar way how normal DLLs do it. There is good description and tool from Selvin
    '   for 32bit native function.
    '
    '   My problem was how to do it for 64bits. Here you go.
    '
    '   1) you ILDAsm your assembly into il code.
    '   2) Edit the IL and change header to look like this:
    '
    '   For 32bit:
    '      .corflags 0x00000002
    '      .vtfixup [1] int32 fromunmanaged at VT_01
    '      .data VT_01 = int32[1]
    '
    '   For 64bit
    '      .corflags 0x00000008
    '      .vtfixup [1] int64 fromunmanaged at VT_01
    '      .data VT_01 = int64[1]
    '
    '   3) Header of your exported method would look similar to this. This is same for 32bit version.
    '      .vtentry 1 : 1
    '      .export [1] as Java_net_sf_jni4net_Bridge_initDotNet
    '
    '   4) You ILAsm the file back into DLL. For x64 you use /x64 flag.
    '
    '   5) Update: It looks like none of the .vtfixup, .data or .vtentry changes are required any more to make this work.
    '      This simplifies the parser quite a lot. We only need to change .corflags and modify the method signature
    '
    '   Usage requires a build step which includes this
    '      if "$(OutDir)"=="bin\Debug\" (set EXPORTARGS=/debug /name32:" x86" /name64:" x64") ELSE (set EXPORTARGS=/name32:" x86" /name64:" x64")
    '      "$(SolutionDir)Utilities\DllExport.exe" %EXPORTARGS% /input:"$(TargetPath)"
    '
    '   You can, of course, choose not to build the x86 or x64 versions by leaving out the
    '   applicable /name: tag
    '

    ''' <summary>
    ''' Class to export attributed functions as standard cdecl functions
    ''' </summary>
    Class DLLExport
#Region "Enums"
        Private Enum Platform
            x86
            x64
        End Enum
#End Region

#Region "Fields"
        Private rInputFile As String
        Private rOutputFile As String
        Private rDebugOn As Boolean
        Private rVerboseOn As Boolean
        Private rLines As New List(Of String)()
        Private rExportIdx As Integer
        Private rX86Suffix As String
        Private rX64Suffix As String
        Private rExportX86 As Boolean
        Private rExportX64 As Boolean
#End Region

#Region " EntryPoint"
        Public Shared Sub Main(args As String())
            Dim dllexport = New DLLExport

#If DEBUG Then
            '---- these are a few Debugging command lines
            'string[] testargs = {"", "/debug", "/name32:\"-x86\"", "/name64:\"-x64\"", "/input:\"..\\..\\..\\DLLRegister\\bin\\release\\DllRegisterRaw.dll\"", "/output:\"..\\..\\..\\DLLRegister\\bin\\release\\DllRegister.dll\"" };
            'Dim testargs As String() = {"", "/debug", "/name32:""-x86""", "/input:""..\..\..\DllRegisterSxS\bin\x86\Debug\DllRegisterSxS.dll"""}
            args = "|/debug|/input:""..\..\..\DllRegisterSxS\bin\x86\Debug\DllRegisterSxSRaw.dll""|/output:""..\..\..\DllRegisterSxS\bin\x86\Debug\DllRegisterSxS.dll""".Split("|")
#End If
            Dim cdir As String = ""
            Dim r As Integer = 1
            Try
                cdir = System.IO.Directory.GetCurrentDirectory()
                r = dllexport.Execute(args)
            Catch ex As Exception
                Console.WriteLine("")
                Console.WriteLine(String.Format("Unable to process file: \r\n{0}", ex.ToString))
            Finally
                System.IO.Directory.SetCurrentDirectory(cdir)
            End Try

            '---- return an application exit code
            Environment.ExitCode = r
        End Sub
#End Region

#Region "Initialization"

        ''' <summary>
        ''' Constructor
        ''' </summary>
        Public Sub New()
            'Nothing special
        End Sub
#End Region

#Region "Properties"

        ''' <summary>
        ''' Get just the file name without extension
        ''' </summary>
        Private ReadOnly Property FileName() As String
            Get
                Return Path.GetFileNameWithoutExtension(rInputFile)
            End Get
        End Property

        ''' <summary>
        ''' Get the folder that contains the file
        ''' </summary>
        Private ReadOnly Property FileFolder() As String
            Get
                Return Path.GetDirectoryName(rInputFile)
            End Get
        End Property

        ''' <summary>
        ''' Get the path to the disassembler
        ''' </summary>
        Private ReadOnly Property DisassemblerPath() As String
            Get
                Dim registryPath = "SOFTWARE\Microsoft\Microsoft SDKs\Windows"
                Dim registryValue = "CurrentInstallFolder"
                Dim key = If(Registry.LocalMachine.OpenSubKey(registryPath), Registry.CurrentUser.OpenSubKey(registryPath))

                If key Is Nothing Then
                    Throw New Exception("Cannot locate ildasm.exe.")
                End If

                Dim SDKPath = TryCast(key.GetValue(registryValue), String)

                If SDKPath Is Nothing Then
                    Throw New Exception("Cannot locate ildasm.exe.")
                End If

                SDKPath = Path.Combine(SDKPath, "Bin\ildasm.exe")

                If Not File.Exists(SDKPath) Then
                    Throw New Exception("Cannot locate ildasm.exe.")
                End If

                Return SDKPath
            End Get
        End Property

        ''' <summary>
        ''' Get the path to the assembler
        ''' </summary>
        Private ReadOnly Property AssemblerPath() As String
            Get
                Dim version = Environment.Version.Major.ToString() & "." & Environment.Version.Minor.ToString() & "." & Environment.Version.Build.ToString()

                Dim ILASMPath = Environment.ExpandEnvironmentVariables("%SystemRoot%\Microsoft.NET\Framework\v" & version & "\ilasm.exe")

                If Not File.Exists(ILASMPath) Then
                    Throw New Exception("Cannot locate ilasm.exe.")
                End If

                Return ILASMPath
            End Get
        End Property
#End Region

#Region "Public Methods"

        ''' <summary>
        ''' Run the conversion
        ''' </summary>
        ''' <returns>An integer used as the DOS return value (0-success, 1 failed)</returns>
        Public Function Execute(inargs As String()) As Integer
            Console.WriteLine("DLLExport Tool v{0}", My.Application.Info.Version.ToString)
            Console.WriteLine("Utility to create old-style dll entry points in .net assemblies")
            Console.WriteLine("")

            If ProcessArguments(inargs) Then
                ' Show usage
                Console.WriteLine("usage: DllExport.exe assembly [/Release|/Debug] [/Verbose] [/Out:new_assembly] [/name32:32bitsuffix] [/name64:64bitsuffix] ")
                Console.WriteLine("")
                Console.WriteLine("If neither name32 or name64 is specified, only a 32bit output will be generated.")
                Return 1
            End If

            If Not File.Exists(rInputFile) Then
                Throw New Exception("The input file does not exist: '" & rInputFile & "'")
            End If

            WriteInfo("DllExport Tool")
            WriteInfo(String.Format("Debug: {0}", rDebugOn))
            WriteInfo(String.Format("Input: '{0}'", rInputFile))
            WriteInfo(String.Format("Output: '{0}'", rOutputFile))

            Console.WriteLine("")

            Disassemble()
            ReadLines()
            '---- for debugging, backup the original il
            'SaveLines(@"C:\Temp\DllExport\Disassembled Original.il");
            ParseAllDllExport()

            '---- 32-bit
            If rExportX86 Then
                FixCorFlags(Platform.x86)
                '---- for debugging, back up the tweaked il
                'SaveLines(@"C:\Temp\DllExport\Disassembled x86.il");
                Assemble(Platform.x86)
            End If

            '---- 64-bit
            If rExportX64 Then
                FixCorFlags(Platform.x64)
                '---- for debugging, back up the tweaked il
                'SaveLines(@"C:\Temp\DllExport\Disassembled x64.il");
                Assemble(Platform.x64)
            End If

            Dim exportCount As Integer = rExportIdx - 1
            Console.WriteLine("DllExport: Exported " & exportCount & (If(exportCount = 1, " function", " functions")))

            Console.WriteLine()
            Return 0
        End Function
#End Region

#Region "Private, Protected Methods"

        ''' <summary>
        ''' Parse the arguments
        ''' </summary>
        Private Function ProcessArguments(inargs As String()) As Boolean
            rDebugOn = False
            rVerboseOn = False
            rInputFile = Nothing
            rOutputFile = Nothing
            rX86Suffix = Nothing
            rX64Suffix = Nothing
            rExportX86 = False
            rExportX64 = False

            '---- mainly for testing to allow swapping out command line args programmatically
            Dim args As String()
            If inargs Is Nothing Then
                args = Environment.GetCommandLineArgs()
            Else
                args = inargs
            End If

            '---- parse each command line arg
            For idx = 1 To args.Length - 1
                Dim argLower = args(idx).ToLower()

                If argLower.StartsWith("/name32:") Then
                    rExportX86 = True
                    rX86Suffix = args(idx).Substring(8).Trim("""".ToCharArray())
                ElseIf argLower.StartsWith("/name64:") Then
                    rExportX64 = True
                    rX64Suffix = args(idx).Substring(8).Trim("""".ToCharArray())
                ElseIf argLower = "/debug" Then
                    rDebugOn = True
                ElseIf argLower = "/verbose" Then
                    rVerboseOn = True
                ElseIf argLower.StartsWith("/input:") Then
                    rInputFile = args(idx).Substring(7).Trim("""".ToCharArray())
                ElseIf argLower.StartsWith("/output:") Then
                    rOutputFile = args(idx).Substring(8).Trim("""".ToCharArray())
                End If
            Next

            '---- if neither x86 or x64, then assume x86
            If Not rExportX86 AndAlso Not rExportX64 Then
                rExportX86 = True
            End If

            If rInputFile = String.Empty OrElse rInputFile Is Nothing Then
                Throw New Exception("You must provide a filename to process.")
            Else
                If Not File.Exists(rInputFile) OrElse Me.FileFolder = String.Empty Then
                    '---- if there's no folder for inputfile, assume the current folder
                    rInputFile = Path.Combine(Directory.GetCurrentDirectory(), rInputFile)

                    If Not File.Exists(rInputFile) Then
                        '---- still can't find the input file, bail
                        Throw New Exception(String.Format("The input file does not exist: '{0}'", rInputFile))
                    End If
                End If

                '---- if no output specified, use the same as input
                If String.IsNullOrEmpty(rOutputFile) Then
                    rOutputFile = rInputFile
                End If

                '---- return true on failure, false on success
                Return String.IsNullOrEmpty(rInputFile)
            End If
        End Function

        ''' <summary>
        ''' Disassemble the input file
        ''' </summary>
        Private Sub Disassemble()
            rExportIdx = 1
            System.IO.Directory.SetCurrentDirectory(Me.FileFolder)
            Dim proc As New Process()

            ' Must specify the /caverbal switch in order to get the custom attribute
            ' values as text and not as binary blobs
            Dim arguments As String = String.Format("/nobar{1}/out:""{0}.il"" ""{0}.dll""", Me.FileName, " /linenum /caverbal ")

            WriteInfo("Disassemble file with arguments '" & arguments & "'")

            Dim info As New ProcessStartInfo(Me.DisassemblerPath, arguments)

            info.UseShellExecute = False
            info.CreateNoWindow = False
            info.RedirectStandardOutput = True
            proc.StartInfo = info

            Try
                proc.Start()
            Catch e As Win32Exception
                Dim handled As Boolean = False

                If e.NativeErrorCode = 3 Then
                    ' try to check wow64 program files
                    Dim fn As String = info.FileName

                    If fn.Substring(1, 16).ToLower() = ":\program files\" Then
                        info.FileName = fn.Insert(16, " (x86)")
                        handled = True
                        proc.Start()
                    End If
                End If
                If Not handled Then
                    Throw (e)
                End If
            End Try

            proc.WaitForExit()

            If proc.ExitCode <> 0 Then
                WriteError(proc.StandardOutput.ReadToEnd())
                Throw New Exception("Could not Disassemble: Error code '" & proc.ExitCode & "'")
            End If
        End Sub

        ''' <summary>
        ''' Read all the lines from the disassembled IL file
        ''' </summary>
        Private Sub ReadLines()
            rLines.Clear()

            If String.IsNullOrEmpty(rInputFile) Then
                Throw New Exception("The input file could not be found")
            End If

            Dim ilFile As String = Me.FileName & ".il"

            If Not File.Exists(ilFile) Then
                Throw New Exception("The disassembled IL file could not be found")
            End If

            Dim sr As StreamReader = File.OpenText(ilFile)

            While Not sr.EndOfStream
                Dim line As String = sr.ReadLine()
                rLines.Add(line)
            End While

            sr.Close()
            sr.Dispose()
        End Sub

        ''' <summary>
        ''' Save the current lines to the specified file
        ''' </summary>
        Private Sub SaveLines(fileName As String)
            Try
                Dim folder = Path.GetDirectoryName(fileName)

                If Not Directory.Exists(folder) Then
                    Directory.CreateDirectory(folder)
                End If

                Dim fileStream = File.CreateText(fileName)

                For Each line As String In rLines
                    fileStream.WriteLine(line)
                Next

                fileStream.Close()
            Catch
            End Try
        End Sub

        ''' <summary>
        ''' Fix the Cor flags
        ''' </summary>
        Private Sub FixCorFlags(platform__1 As Platform)
            For idx As Integer = 0 To rLines.Count - 1
                If rLines(idx).StartsWith(".corflags") Then
                    Select Case platform__1
                        Case Platform.x86
                            rLines(idx) = ".corflags 0x00000002  // 32BITREQUIRED"
                            Exit Select

                        Case Platform.x64
                            rLines(idx) = ".corflags 0x00000008  // 64BITREQUIRED"
                            Exit Select
                    End Select
                    Exit For
                End If
            Next
        End Sub

        ''' <summary>
        ''' Parse all DllExport entries
        ''' </summary>
        Private Sub ParseAllDllExport()
            Dim dllExportIdx As Integer = FindAttributeLine(-1, -1)

            While dllExportIdx >= 0
                ParseDllExport(dllExportIdx)
                dllExportIdx = FindAttributeLine(dllExportIdx + 1, -1)
            End While
        End Sub

        ''' <summary>
        ''' Parse the DllExport entry
        ''' </summary>
        ''' <param name="dllExportIdx"></param>
        Private Sub ParseDllExport(dllExportIdx As Integer)
            Dim exportNameIdx As Integer = FindLineContains("string('", True, dllExportIdx, dllExportIdx + 5)
            Dim calConvIdx As Integer = FindLineContains("int32(", True, dllExportIdx, dllExportIdx + 5)
            Dim exportName As String = Nothing
            Dim startIdx As Integer = 0
            Dim endIdx As Integer = 0

            If calConvIdx < 0 Then
                Throw New Exception("Could not find Calling Convention for line " & dllExportIdx.ToString())
            End If

            If exportNameIdx >= 0 Then
                startIdx = rLines(exportNameIdx).IndexOf("('")
                endIdx = rLines(exportNameIdx).IndexOf("')")

                If startIdx >= 0 AndAlso endIdx >= 0 Then
                    exportName = rLines(exportNameIdx).Substring(startIdx + 2, endIdx - startIdx - 2)
                End If
            End If

            startIdx = rLines(calConvIdx).IndexOf("int32(")
            endIdx = rLines(calConvIdx).IndexOf(")")

            If startIdx < 0 OrElse endIdx < 0 Then
                Throw New Exception("Could not find Calling Convention for line " & dllExportIdx.ToString())
            End If

            Dim calConvText As String = rLines(calConvIdx).Substring(startIdx + 6, endIdx - startIdx - 6)
            Dim calConvValue As Integer = 0

            If Not Integer.TryParse(calConvText, calConvValue) Then
                Throw New Exception("Could not parse Calling Convention for line " & dllExportIdx.ToString())
            End If

            Dim callConv As CallingConvention = CType(calConvValue, CallingConvention)

            Dim endDllExport As Integer = FindLineContains("}", True, calConvIdx, calConvIdx + 10)

            If endDllExport < 0 Then
                Throw New Exception("Could not find end of Calling Convention for line " & dllExportIdx.ToString())
            End If

            ' Remove the DllExport lines
            While endDllExport >= dllExportIdx
                rLines.RemoveAt(System.Math.Max(System.Threading.Interlocked.Decrement(endDllExport), endDllExport + 1))
            End While

            Dim insertIdx As Integer = FindLineStartsWith(".maxstack", True, dllExportIdx, dllExportIdx + 20)

            If insertIdx < 0 Then
                Throw New Exception("Could not find '.maxstack' insert location for line " & dllExportIdx.ToString())
            End If

            Dim tabs As Integer = rLines(insertIdx).IndexOf(".")

            Dim exportText As String = TabString(tabs) & ".export [" & (System.Math.Max(System.Threading.Interlocked.Increment(rExportIdx), rExportIdx - 1)).ToString() & "]"

            If Not String.IsNullOrEmpty(exportName) Then
                exportText += " as " & exportName
            End If

            rLines.Insert(insertIdx, exportText)

            Dim methodName As String = UpdateMethodCalConv(FindLineStartsWith(".method", False, insertIdx - 1, -1), callConv)

            If Not String.IsNullOrEmpty(methodName) Then
                If Not String.IsNullOrEmpty(exportName) Then
                    Console.WriteLine("Exported '" & methodName & "' as '" & exportName & "'")
                Else
                    Console.WriteLine("Exported '" & methodName & "'")
                End If
            End If
        End Sub

        ''' <summary>
        ''' Update the method's calling convention
        ''' </summary>
        ''' <param name="methodIdx"></param>
        ''' <param name="callConv"></param>
        Private Function UpdateMethodCalConv(methodIdx As Integer, callConv As CallingConvention) As String
            If methodIdx < 0 OrElse FindLineStartsWith(".method", True, methodIdx, methodIdx) <> methodIdx Then
                Throw New Exception("Invalid method index: " & methodIdx.ToString())
            End If

            Dim endIdx As Integer = FindLineStartsWith("{", True, methodIdx, -1)

            If endIdx < 0 Then
                Throw New Exception("Could not find method open brace location for line " & methodIdx.ToString())
            End If

            endIdx -= 1
            Dim insertLine As Integer = -1
            Dim insertCol As Integer = -1
            Dim methodName As String = Nothing

            For idx As Integer = methodIdx To endIdx
                Dim marshalIdx As Integer = rLines(idx).IndexOf("marshal(")

                If marshalIdx >= 0 Then
                    ' Must be inserted before the "marshal(" entry
                    insertLine = idx
                    insertCol = marshalIdx
                    Exit For
                Else
                    Dim openBraceIdx As Integer = rLines(idx).IndexOf("("c)

                    While openBraceIdx >= 0 AndAlso insertLine < 0 AndAlso insertCol < 0
                        Dim spaceIdx As Integer = rLines(idx).LastIndexOf(" "c, openBraceIdx)

                        If spaceIdx >= 0 Then
                            Dim findMethodName As String = rLines(idx).Substring(spaceIdx + 1, openBraceIdx - spaceIdx - 1)

                            ' The method name is anything but "marshal"
                            If findMethodName <> "marshal" Then
                                insertLine = idx
                                insertCol = spaceIdx + 1
                                methodName = findMethodName
                                Exit While
                            End If

                            openBraceIdx = rLines(idx).IndexOf("("c, openBraceIdx + 1)
                        End If
                    End While
                End If

                If methodIdx >= 0 AndAlso insertCol >= 0 Then
                    Exit For
                End If
            Next

            If insertLine < 0 OrElse insertCol < 0 Then
                Throw New Exception("Could not find method name for line " & methodIdx.ToString())
            End If

            Dim leftText As String = rLines(insertLine).Substring(0, insertCol)
            Dim rightText As String = rLines(insertLine).Substring(insertCol)
            Dim callConvText As String = "modopt([mscorlib]"

            Select Case callConv
                Case System.Runtime.InteropServices.CallingConvention.Cdecl
                    callConvText += GetType(CallConvCdecl).FullName & ") "
                    Exit Select

                Case System.Runtime.InteropServices.CallingConvention.FastCall
                    callConvText += GetType(CallConvFastcall).FullName & ") "
                    Exit Select

                Case System.Runtime.InteropServices.CallingConvention.StdCall
                    callConvText += GetType(CallConvStdcall).FullName & ") "
                    Exit Select

                Case System.Runtime.InteropServices.CallingConvention.ThisCall
                    callConvText += GetType(CallConvThiscall).FullName & ") "
                    Exit Select

                Case System.Runtime.InteropServices.CallingConvention.Winapi
                    callConvText += GetType(CallConvStdcall).FullName & ") "
                    Exit Select
                Case Else

                    Throw New Exception("Invalid calling convention specified: '" & callConv.ToString() & "'")
            End Select

            rLines(insertLine) = leftText & callConvText & rightText
            Return methodName
        End Function

        ''' <summary>
        ''' Assemble the destination file
        ''' </summary>
        Private Sub Assemble(platform__1 As Platform)
            Dim sw As StreamWriter = File.CreateText(Me.FileName & ".il")

            For Each line As String In rLines
                sw.WriteLine(line)
            Next

            sw.Close()
            sw.Dispose()

            Dim resFile As String = Me.FileName & ".res"
            Dim res As String = """" & resFile & """"

            If File.Exists(resFile) Then
                res = " /resource=" & res
            Else
                res = ""
            End If

            Dim proc As New Process()
            Dim extension As String = Path.GetExtension(rInputFile)
            Dim outFile As String = Path.GetFileNameWithoutExtension(rOutputFile)

            Select Case platform__1
                Case Platform.x86
                    If Not String.IsNullOrEmpty(rX86Suffix) Then
                        outFile += rX86Suffix
                    End If

                Case Platform.x64
                    If Not String.IsNullOrEmpty(rX64Suffix) Then
                        outFile += rX64Suffix
                    End If
            End Select

            If extension = String.Empty Then
                extension = ".dll"
            End If

            outFile += extension

            Dim argOptions As String = "/nologo /quiet /DLL"
            Dim argIl As String = """" & Me.FileName & ".il"""
            Dim argOut As String = "/out:""" & outFile & """"

            If rDebugOn Then
                argOptions += " /debug /pdb"
            Else
                argOptions += " /optimize"
            End If

            If platform__1 = Platform.x64 Then
                argOptions += " /x64"
            End If

            Dim arguments As String = argOptions & " " & argIl & " " & res & " " & argOut

            WriteInfo(String.Format("Compiling file with arguments '{0}", arguments))

            Dim info As New ProcessStartInfo(Me.AssemblerPath, arguments)
            info.UseShellExecute = False
            info.CreateNoWindow = False
            info.RedirectStandardOutput = True
            proc.StartInfo = info
            proc.Start()
            proc.WaitForExit()

            WriteInfo(proc.StandardOutput.ReadToEnd())

            If proc.ExitCode <> 0 Then
                Throw New Exception(String.Format("Could not assemble: Error code '{0}'", proc.ExitCode))
            End If
        End Sub

        ''' <summary>
        ''' Find the next line that starts with the specified text, ignoring leading whitespace
        ''' </summary>
        ''' <param name="findText"></param>
        ''' <param name="startIdx"></param>
        ''' <param name="endIdx"></param>
        ''' <returns></returns>
        Private Function FindLineStartsWith(findText As String, forward As Boolean, startIdx As Integer, endIdx As Integer) As Integer
            If forward Then
                If startIdx < 0 Then
                    startIdx = 0
                End If

                If endIdx < 0 Then
                    endIdx = rLines.Count - 1
                Else
                    endIdx = Math.Min(endIdx, rLines.Count - 1)
                End If

                For idx As Integer = startIdx To endIdx
                    If rLines(idx).Contains(findText) AndAlso rLines(idx).Trim().StartsWith(findText) Then
                        Return idx
                    End If
                Next
            Else
                If startIdx < 0 Then
                    startIdx = rLines.Count - 1
                End If

                If endIdx < 0 Then
                    endIdx = 0
                End If

                For idx As Integer = startIdx To endIdx Step -1
                    If rLines(idx).Contains(findText) AndAlso rLines(idx).Trim().StartsWith(findText) Then
                        Return idx
                    End If
                Next
            End If

            Return -1
        End Function

        ''' <summary>
        ''' Find the next Attribute line
        ''' </summary>
        ''' <param name="startIdx"></param>
        ''' <param name="endIdx"></param>
        ''' <returns></returns>
        Private Function FindAttributeLine(startIdx As Integer, endIdx As Integer) As Integer
            If startIdx < 0 Then
                startIdx = 0
            End If

            If endIdx < 0 Then
                endIdx = rLines.Count - 1
            Else
                endIdx = Math.Min(endIdx, rLines.Count - 1)
            End If

            For idx As Integer = startIdx To endIdx
                If rLines(idx).Contains("DllExportAttribute::.ctor") AndAlso rLines(idx).Trim().StartsWith(".custom instance void ") Then
                    Return idx
                End If
            Next

            Return -1
        End Function

        ''' <summary>
        ''' Find the line that contains the specified text
        ''' </summary>
        ''' <param name="findText"></param>
        ''' <param name="startIdx"></param>
        ''' <param name="endIdx"></param>
        ''' <returns></returns>
        Private Function FindLineContains(findText As String, forward As Boolean, startIdx As Integer, endIdx As Integer) As Integer
            If forward Then
                If startIdx < 0 Then
                    startIdx = 0
                End If

                If endIdx < 0 Then
                    endIdx = rLines.Count - 1
                Else
                    endIdx = Math.Min(endIdx, rLines.Count - 1)
                End If

                For idx As Integer = startIdx To endIdx - 1
                    If rLines(idx).Contains(findText) Then
                        Return idx
                    End If
                Next
            Else
                If startIdx < 0 Then
                    startIdx = rLines.Count - 1
                End If

                If endIdx < 0 Then
                    endIdx = 0
                End If

                For idx As Integer = startIdx To endIdx Step -1
                    If rLines(idx).Contains(findText) Then
                        Return idx
                    End If
                Next
            End If

            Return -1
        End Function

        ''' <summary>
        ''' Get a string padded with the number of spaces
        ''' </summary>
        ''' <param name="tabCount"></param>
        ''' <returns></returns>
        Private Function TabString(tabCount As Integer) As String
            If tabCount <= 0 Then Return String.Empty

            Dim sb As New StringBuilder()

            sb.Append(" "c, tabCount)
            Return sb.ToString()
        End Function

        ''' <summary>
        ''' Write an informational message
        ''' </summary>
        ''' <param name="info"></param>
        Private Sub WriteInfo(info As String)
            If rVerboseOn Then
                Console.WriteLine(info)
            End If
        End Sub

        ''' <summary>
        ''' Write an informational message
        ''' </summary>
        Private Sub WriteError(msg As String)
            Console.WriteLine(msg)
        End Sub

#End Region
    End Class
End Namespace

There’s really nothing tricky or earth-shattering here. Mainly calls to ILDASM and ILASM, and quite a lot of string parsing (looking for the DLLExportAttribute markers and replacing them with the applicable IL code).

The DLLExport Marker Attribute

As for that DLLExportAttribute, its definition is much simpler:

Imports System.Runtime.CompilerServices
Imports System.Runtime.InteropServices

Namespace DllExport
    ''' <summary>
    ''' Attribute added to a static method to export it
    ''' </summary>
    <AttributeUsage(AttributeTargets.Method)> _
    Public Class DllExportAttribute
        Inherits Attribute

        ''' <summary>
        ''' Constructor 1
        ''' </summary>
        ''' <param name="exportName"></param>
        Public Sub New(exportName As String)
            Me.New(exportName, System.Runtime.InteropServices.CallingConvention.StdCall)
        End Sub

        ''' <summary>
        ''' Constructor 2
        ''' </summary>
        ''' <param name="exportName"></param>
        ''' <param name="callingConvention"></param>
        Public Sub New(exportName As String, callingConvention As CallingConvention)
            _ExportName = exportName
            _CallingConvention = callingConvention
        End Sub
        Private _ExportName As String

        ''' <summary>
        ''' Get the export name, or null to use the method name
        ''' </summary>
        Public ReadOnly Property ExportName() As String
            Get
                Return _ExportName
            End Get
        End Property

        ''' <summary>
        ''' Get the calling convention
        ''' </summary>
        Public ReadOnly Property CallingConvention() As String
            Get
                Select Case _CallingConvention
                    Case System.Runtime.InteropServices.CallingConvention.Cdecl
                        Return GetType(CallConvCdecl).FullName

                    Case System.Runtime.InteropServices.CallingConvention.FastCall
                        Return GetType(CallConvFastcall).FullName

                    Case System.Runtime.InteropServices.CallingConvention.StdCall
                        Return GetType(CallConvStdcall).FullName

                    Case System.Runtime.InteropServices.CallingConvention.ThisCall
                        Return GetType(CallConvThiscall).FullName

                    Case System.Runtime.InteropServices.CallingConvention.Winapi
                        Return GetType(CallConvStdcall).FullName
                    Case Else

                        Return ""
                End Select
            End Get
        End Property
        Private _CallingConvention As CallingConvention

    End Class
End Namespace

What Next?

So, now that we can easily expose entry points from a .net assembly, what can we do with that?

For starters, as my previous post mentioned, I’ve built a .net plugin for the MAME front end called Mala. It’s still in very early stages, and is not yet available, but it definitely works.

Even more interesting, I’ve experimented with creating self-registering COM .net assemblies. But that will have to wait for another posting.

For the full project, and a pre-compiled DLLExport.exe file, grab this zip.

And definitely let me know how you use it!

%$^&@*~ Worm!

0
Filed under Rants

imageWell, I’ve been working professionally for a long time now and have only had a virus/worm problem once (I knew better than to open the FTP port through my firewall, but my wife needed to send a large file, I wouldn’t leave it open, and, what could happen? <ugh>)…

Anyway, fast forward to last Sunday, I’m doing a some research on a little project of mine when suddenly things are running really slowly.

I check a few of the usual suspects and nothing. So I open TaskMan, figuring I’ve got FireFox running rampant and chewing a bunch of ram.

Well it was, but that wasn’t what was interesting.

What was interesting?

What was interesting was that I was seeing a 20 character long randomly named EXE run, spawn another similarly named EXE, then die. Over and over again.

That’s not the behavior of any kind of normal application.

Yikes.

First things first.

After some frantic clicking trying to kill the process before it could spawn, I finally managed to. Ok. So now what. I opened FireFox and Googled “random named exe running”, got back a list of results and clicked on one.

I ended up at some link farm page (you know the kind, tons of links, but nothing worth anything).

Ok. Back up and try another result. Different link farm page, but same format.

Huh-Whuh?

Ok, Search for “CreateWindow”, first Google result is an MSDN page, click on it, same dang link farm page!

Crap. I’d been hijacked.

Reboot

Maybe it was just an in memory thing, so I reboot (and disconnect from my network!).

Once I log back in, everything crawling. Back in TaskMan and I see, literally, dozens of randomly named EXE’s spawning and dying all over the place.

Double Yikes!

Eset’s NOD32 is running, but it can’t keep up.

Shutdown.

Using another computer, I used NOD32 to create an emergency rescue USB drive.

Back to the infected machine, I boot to the thumb drive and start a scan. Oh…..Dear……Lord….. This is going to take a while.

Hours Later….

When it finally finished, it’d found a number of infected files, particularly, the Win32/Olmarik worm, and cleaned them, but I wasn’t convinced.

I did a quick check for any EXE’s dated that day, and sure enough, there were dozens of them, all about 2.4mb in size, in the SysWow64 folder. I deleted them all, then searched for any other files modified in the last 2 days that I didn’t immediately recognize. I deleted everything I found.

Restart and everything’s running lovely again.

Not out of the Woods

I start up FireFox and Google search results are still redirecting to various link farms. Crap.

I use another computer to search for solutions…

  1. Uninstall FireFox
  2. Delete everything related to FireFox on your drive.
  3. Uninstall Java
  4. Delete everything related to Java on my drive

Reboot and reinstall FF. Back and working normally. Phew! I just have to restore all my bookmarks and addins and I should be good there.

Turns out, the worm creates some Java hooks into your browser than causes the redirection. Nasty stuff.

Still Not Out of the Woods

I suspected it still wasn’t over and sure enough, I’m right. A few hours later, I happen to need to use KeePass for a password. Pressing Ctrl-Alt-A (standard KeePass hotkey), I get an Explorer popup saying that “The executable 43HJKAN5H1AVC.exe could not be located. Remove this shortcut?”

Son-of-a-bitch.

The damn worm created short-cut links to those random named exes I’d already deleted.

So off I go hunting down all the LNK files modified in the last few days and delete all of them.

Finally, I believe everything’s back to normal (though I’m still walking cautiously for now). I’ve since run a full computer scan on all my machines with nothing noted. Fingers crossed.

Post mortem

I’m still not completely sure what vector the worm used to get in, considering NOD32 was running the whole time. The only thing I can think of was that my daughter was in and out of my office at the time. I could have been distracted at some point and clicked a popup that I didn’t really intend to click.

But that’s just a guess.

The second thing that bothers me is why NOD32 didn’t catch this. It did catch at least parts of it, but the Java browser hijack totally slipped through. Doesn’t give me a good feeling…