Monday, March 26, 2018

Avoiding StackOverflowException when use assembly binding redirect in PowerShell

Recently I faced with interesting problem with assembly binding redirect in PowerShell: in my script I needed to use the following versions of the assemblies (these exact versions were used in other components and I couldn’t add another versions because of number of reasons):

OfficeDevPnP.Core 2.22.1801.0
Microsoft.Graph 1.7.0.0
Microsoft.Graph.Core 1.7.0.0

The problem is that OfficeDevPnP.Core 2.22.1801.0 references different versions of Microsoft.Graph and Microsoft.Grap.Core:

Microsoft.Graph 1.1.1.0
Microsoft.Graph.Core 1.2.1.0

So I needed to use assembly binding redirect. At first I tried approach described in the following post: Use specific version of Sharepoint client object model in PowerShell via assembly binding redirection:

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$currentDir = Convert-Path(Get-Location)
$pnpCoreDir = resolve-path($currentDir + "\..\packages\SharePointPnPCoreOnline.2.22.1801.0\lib\net45\")
$graphDir = resolve-path($currentDir + "\..\packages\Microsoft.Graph.1.7.0\lib\net45\")
$graphCoreDir = resolve-path($currentDir + "\..\packages\Microsoft.Graph.Core.1.7.0\lib\net45\")
 
$AssemblyGraphCore = [System.Reflection.Assembly]::LoadFile([System.IO.Path]::Combine($graphCoreDir, "Microsoft.Graph.Core.dll"))
$AssemblyGraph = [System.Reflection.Assembly]::LoadFile([System.IO.Path]::Combine($graphDir, "Microsoft.Graph.dll"))
[System.Reflection.Assembly]::LoadFile([System.IO.Path]::Combine($pnpCoreDir, "OfficeDevPnP.Core.dll"))
 
 
<#$OnAssemblyResolve = [System.ResolveEventHandler] {
    param($sender, $e)
     
    if ($e.Name.StartsWith("Microsoft.Graph,"))
    {
        $AssemblyGraph = [System.Reflection.Assembly]::LoadFile([System.IO.Path]::Combine($graphDir, "Microsoft.Graph.dll"))
        return $AssemblyGraph
    }
    if ($e.Name.StartsWith("Microsoft.Graph.Core,"))
    {
        $AssemblyGraphCore = [System.Reflection.Assembly]::LoadFile([System.IO.Path]::Combine($graphCoreDir, "Microsoft.Graph.Core.dll"))
        return $AssemblyGraphCore
    }
 
    foreach($a in [System.AppDomain]::CurrentDomain.GetAssemblies())
    {
        if ($a.FullName -eq $e.Name)
        {
          return $a
        }
    }
    Write-Host "Return null" -foregroundcolor red
    return $null
}
[System.AppDomain]::CurrentDomain.add_AssemblyResolve($OnAssemblyResolve)

However attempt to call method from loaded assemblies caused StackOverflowException and closing PowerShell session.

After that I tried C#-based assembly redirector (found it in the following forum thread: Powershell - Assembly binding redirect NOT found in application configuration file):

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if (!("Redirector" -as [type]))
{
$source =
@'
using System;
using System.Linq;
using System.Reflection;
using System.Text.RegularExpressions;
 
public class Redirector
{
    public readonly string[] ExcludeList;
 
    public Redirector(string[] ExcludeList = null)
    {
        this.ExcludeList  = ExcludeList;
        this.EventHandler = new ResolveEventHandler(AssemblyResolve);
    }
 
    public readonly ResolveEventHandler EventHandler;
 
    protected Assembly AssemblyResolve(object sender, ResolveEventArgs resolveEventArgs)
    {
        Console.WriteLine("Attempting to resolve: " + resolveEventArgs.Name); // remove this after its verified to work
        foreach (var assembly in AppDomain.CurrentDomain.GetAssemblies())
        {
            var pattern  = "PublicKeyToken=(.*)$";
            var info     = assembly.GetName();
            var included = ExcludeList == null || !ExcludeList.Contains(resolveEventArgs.Name.Split(',')[0], StringComparer.InvariantCultureIgnoreCase);
 
            if (included && resolveEventArgs.Name.StartsWith(info.Name, StringComparison.InvariantCultureIgnoreCase))
            {
                if (Regex.IsMatch(info.FullName, pattern))
                {
                    var Matches        = Regex.Matches(info.FullName, pattern);
                    var publicKeyToken = Matches[0].Groups[1];
 
                    if (resolveEventArgs.Name.EndsWith("PublicKeyToken=" + publicKeyToken, StringComparison.InvariantCultureIgnoreCase))
                    {
                        Console.WriteLine("Redirecting lib to: " + info.FullName); // remove this after its verified to work
                        return assembly;
                    }
                }
            }
        }
 
        return null;
    }
}
'@
 
    $type = Add-Type -TypeDefinition $source -PassThru
}
 
try
{
    $redirector = [Redirector]::new($null)
    [System.AppDomain]::CurrentDomain.add_AssemblyResolve($redirector.EventHandler)
}
catch
{
    #.net core uses a different redirect method
    Write-Warning "Unable to register assembly redirect(s). Are you on ARM (.Net Core)?"
}

And surprisingly this approach worked. It looks like a bug in PowerShell script-based assembly binding redirect. Hope it will help someone.

at
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