Reflector and its add-in FileDisassembler.

Reflector will allow to see the source code. FileDisassembler will allow you to convert it into a VS solution.

Actually, none of these answers are right.

Yeah, all the tools can decompile *.dll files into *.csproj file but none of them supports CLI or batch processing. You can save yourself the time with installations.

The best possible solution so far is use dotPeek, put all *.dll files into one folder and use Explore Folder option.

dotPeek will analyse the given folder and shows a tree of DLLs located inside the folder. You can generate csproj manually for every single dll which is loaded.

If you came across this post because you are looking answer how locate specific instruction in your or 3rd party dlls, specially a use of reflection, you can use this PowerShell script to decompile dlls into IL and look for the instruction (System.Reflection.Assembly::Load(string) for reflection).

Note

It is using Intermediate Language DisASseMbler (ILDASM) from .NET Framework SDK kit. Adjust the path accordingly to your version of SDK.

function Get-LibDump
{
    Param(
# Specifies a path to one or more locations. Wildcards are permitted.
    [Parameter(Mandatory=$true,
            Position=0,
            ParameterSetName="Basic",
            ValueFromPipeline=$true,
            ValueFromPipelineByPropertyName=$true,
            HelpMessage="Path to one or more locations.")]
    [ValidateNotNullOrEmpty()]
    [SupportsWildcards()]
    [ValidateScript({$_ | Test-Path})]
    [System.IO.FileInfo]
    $Path
    )
    process
    {
        $dumpFileFilePath = $Path.BaseName + '.il'
        $outFile = "C:\LibDump\$dumpFileFilePath"
        Start-Process -FilePath 'c:\Program Files (x86)\Microsoft SDKs\Windows\v10.0A\bin\NETFX 4.7.2 Tools\ildasm.exe' -ArgumentList "/UNICODE /OUT=`"$outFile`" `"$($Path.FullName)`"" -Wait
        "Dump from:`n$(Resolve-Path -Path $Path.FullName -Relative)" | Out-File -FilePath $outFile -Encoding:unicode -Append
    }
}

# Use
Get-ChildItem -Path $PathToLibFolder -Filter '*.dll' -File -Recurse | Get-LibDump

Here is a good article about Reflector and how to integrate Reflector into Visual Studio.

Of particular interest is the Reflector.VisualStudio Add-In. This add-in, created by Jaime Cansdale, allows for Reflector to be hosted within Visual Studio. With this add-in, you can have Reflector integrated within the Visual Studio environment.

To get started, you will need to have the latest version of Reflector on your machine. Once you have downloaded Reflector, download the latest version of the Reflector.VisualStudio Add-In from http://www.testdriven.NET/reflector. The download contains a number of files that need to be placed in the same directory as Reflector.exe. To install the add-in, drop to the command line and run:

Reflector.VisualStudio.exe /install

After the add-in has been installed, you can start using Reflector from Visual Studio. You’ll notice a new menu item, Addins, which has a menu option titled Reflector. This option, when selected, displays the Reflector window, which can be docked in the IDE. Additionally, the add-in provides context menu support.

When you right-click in an open code file in Visual Studio, you’ll see a Reflector menu item that expands into a submenu with options to disassemble the code into C# or Visual Basic, display the call graph or callee graph, and other related choices. The context menu also includes a Synchronize with Reflector menu item that, when clicked, syncs the object browser tree in the Reflector window with the current code file.

So you see at the top where it lists .Ref at the end of the package name? I'm not positive but I suspect this is trimmed down version of the DLL that doesn't include the full source.

If you search for the dll elsewhere you should be able to find the dll with the full source and decompile that with a standalone decompiler.

So for your example you can find the full dll at C:\Program Files (x86)\dotnet\shared\Microsoft.AspNetCore.App\3.0.0\Microsoft.AspNetCore.Authentication.Cookies.dll

Personally I prefer using the free decompiler offered by JetBrains called dotPeek. It allows you to navigate directly to the decompiled source using F12, however this will only lead you back to where you are stuck now. BUT if you open the path I listed above for the full DLL and open that in dotPeek, you'll get the full decompiled source code.

As far as I know there's no way to lookup the actual DLL via keyboard shortcut inside the IDE, you have to find the DLL yourself and open it in a decompiler.