How can I open DLL files to see what is written inside?

Question

I lost the solution of a class library. Can I open the DLL file which is created by the class library?

Answer 1

You are better off with a decompiler like Redgate's .NET Reflector or JetBrains' ReSharper decompiler.

There are open source ones also, like:

• dotPeek

• ILSpy

Answer 2

Follow the below steps...

1. Go to the Start Menu.
2. Type Visual Studio Tool.
3. Go to the folder above.
4. Click on "Developer Command Prompt for VS 2013" in the case of Visual Studio 2013 or just "Visual Studio Command Prompt " in case of Visual Studio 2010.
5. After the command prompt loaded to the screen, type ILDASM.EXE press ENTER.
6. An ILDASM window will open. Drag the .dll file to the window from your folder. Or click on menu File → New. Then add the required .dll file.
7. After the above steps, the manifest and .dll file will appear. Double click on those files to see what they contain.

Answer 3

I think you have downloaded the .NET Reflector & this FileGenerator plugin http://filegenreflector.codeplex.com/ , If you do,

1. Open up the Reflector.exe,

2. Go to View and click Add-Ins,

3. In the Add-Ins window click Add...,

4. Then find the dll you have downloaded

5. FileGenerator.dll (witch came wth the FileGenerator plugin),

6. Then close the Add-Ins window.

7. Go to File and click Open and choose the dll that you want to decompile,

8. After you have opend it, it will appear in the tree view,

9. Go to Tools and click Generate Files(Crtl+Shift+G),

10. select the output directory and select appropriate settings as your wish, Click generate files.

OR

use http://ilspy.net/

Answer 4

You cannot get the exact code, but you can get a decompiled version of it.

The most popular (and best) tool is Reflector, but there are also other .NET decompilers (such as Dis#).

You can also decompile the CIL using ILDASM, which comes bundled with the .NET Framework SDK tools.

Answer 5

I use JetBrains' dotPeek software. You can try that too.

Answer 6

Telerik's Just Decompile is the best I've used. It's free once you sign up with an email.

Answer 7

Open the .dll file with Visual Studio. Or a resource editor.

Answer 8

*.dll files are archive files opened with WinZip, 7-Zip, etc. That isn’t to say that all .dll files are archives. You can save anything with the .dll extension. However, most Windows .dll files are generated to be archives. Examples of this are Windows > twain_32.dll which is an archive file. However, twain.dll is not. If you look at twain.dll you will see an MZŽ as the first three notepad characters which denotes a compiled C file/program or part of a program. Whereas MZ seems to be an archive.

Also, most .exe files are archives mostly containing an icon image, etc. For the file and the windows installer packages as well, they contain all the information the program needs to run images, movies, etc. and also directories including installation information and plain text files.

I have a game here, game.exe, and it contains Java class files and image a pointer directing the .exe to run a .bat file. Obviously, your .bat file will run a javac call from the archive and run the game. There are also a few .dll archives containing Java class files.

[autorun]
ICON=AUTORUN\MINCRAFTLOGO.ICO
standard icon redirect here .ico is an image file within a .dll file within a .exe file. So the image seen on the .exe file is the minecraft logo. This is in a file called autorun.inf. Second example

[discstarter]
    startpage=Autostart\Disk1.html
    uselanguagestartpage=1
    windowcaption=Solid Edge
    licensee=Siemens PLM Software
    productguid=05B227DF-DB00-4934-B3C8-40B7D8FAA54A
    singleinstance=1
    hidesplashscreen=1
    noscrollbars=0
    showstatusbar=1
    splashscreentime=0
    windowwidth=750
    windowheight=775
    buttondir=Autostart
    toolbarcolor=16777215
    toolbar=goback,goforward,gohome,print,exit
    [autorun]
    open=autostart.exe
    icon=Autostart\ENGINE.ICO

This is the solid edge autorun.inf file contained in solidedge.exe Autostart\ is the Autostart.dll directory. open=autostart.exe specifies the autostart.exe file to run from within the original solidedge.exe archive. Here is a sample program using the .dll (dynamic link library) files: Creating And Using DLLs.

It also shows how they are created. As you can see, the contents of the DLL file file is called by an EXE file file as I previously explained. Also there is a tutorial here Walkthrough: Create and use your own Dynamic Link Library (C++), and, as I said before, 7-Zip or WinZip will open a dynamic link library as an archive as long as you have the .dll file. If the contents of the dynamic link library have been compiled obviously, you need a program which can read the file.

However, since .dll files are by definition just archive library files, the DLL file itself should be readable and not a compiled C or C# file, etc., etc. Basically, .dll files are archives. Well, they should be when a .dll file is created in Visual Studio. The DLL file is created and any information you store in the DLL file file is encrypted. Mostly, this encryption is handled by Visual Studio itself and generally isn't edited by hand. When you read a .dll file contents as a .exe, the contents are automatically decrypted. Now when we talk about compiling a program we are changing the contents into bytecode the machine easily interprets.

This file size would be smaller than the original file of the same contents. However, the filesize is larger, suggesting that the file has actually been encrypted. It is probably to stop people reading their code. As a result, the reading of .dll contents is termed decryption and not decompilation. Decompilation would convert the already-compiled .txt files to unreadable byte code. The use of standard .dll files is by definition not open source, because it involves the deliberate obfuscation of byte code.