Querying Active Directory from MVC result in: Attempted to access an unloaded appdomain. (Exception from HRESULT: 0x80131014)

Question

I have an issue using c# on .Net 4 in a MVC web application, where when I query Active Directory, I frequently get an error: Attempted to access an unloaded appdomain. (Exception from HRESULT: 0x80131014).

The strange thing is, that it will work flawlessly for a time, and then it will just start happening, and then just disappear again.

I have made a few modifications to the function to get it to work , but they all seem to fail. I am wondering if I am doing something wrong, or if there is a better way to do it.

Here is my current function, that will accept a loginId, and a PrincipalContext. The loginId can either be the user DisplayName i.e "John Smith", or DOMAINNAME\josmi. The default is to use the first 2 letters of their firstname, and then the first 3 letters of their surname. There is a check in there if this is not the case. This part if fine.

public List<ADGroup> GetMemberGroups(string loginId, PrincipalContext principalContext, int tries = 0)
{
    var result = new List<ADGroup>();

    try
    {
        var samAccountName = "";
        if (loginId.Contains(" "))
        {
            var fName = loginId.Split(Char.Parse(" "))[0].ToLower();
            var sName = loginId.Split(Char.Parse(" "))[1].ToLower();

            if (sName.Trim().Length == 2)
                samAccountName = string.Format("{0}{1}", fName.StartsWith(".") ? fName.Substring(0, 4) : fName.Substring(0, 3), sName.Substring(0, 2));
            else
                samAccountName = string.Format("{0}{1}", fName.StartsWith(".") ? fName.Substring(0, 3) : fName.Substring(0, 2), sName.Substring(0, 3));
        }
        else
            samAccountName = loginId.Substring(loginId.IndexOf(@"\") + 1);

        var authPrincipal = UserPrincipal.FindByIdentity(principalContext, IdentityType.SamAccountName, samAccountName);

        if (authPrincipal == null)
            throw new Exception(string.Format("authPrincipal is null for loginId - {0}", loginId));

        var firstLevelGroups = authPrincipal.GetGroups();

        AddGroups(firstLevelGroups, ref result);
    }
    catch
    {
        if (tries > 5)
            throw;

        tries += 1;

        System.Threading.Thread.Sleep(1000);
        GetMemberGroups(loginId, principalContext, tries);
    }

    return result;
}

    private void AddGroups(PrincipalSearchResult<Principal> principal, ref List<ADGroup> returnList)
    {
        foreach (var item in principal)
        {
            if (item.GetGroups().Count() > 0)
                AddGroups(item.GetGroups(), ref returnList);

            returnList.Add(new ADGroup(item.SamAccountName, item.Sid.Value));
        }
    }

This function is called like this:

MembershipGroups = ad.GetMemberGroups(user.SamAccountName, new PrincipalContext(ContextType.Domain));

The the error that I SOMETIMES get is:

System.AppDomainUnloadedException: Attempted to access an unloaded appdomain. (Exception from HRESULT: 0x80131014) at System.StubHelpers.StubHelpers.InternalGetCOMHRExceptionObject(Int32 hr, IntPtr pCPCMD, Object pThis) at System.StubHelpers.StubHelpers.GetCOMHRExceptionObject(Int32 hr, IntPtr pCPCMD, Object pThis) at System.DirectoryServices.AccountManagement.UnsafeNativeMethods.IADsPathname.Retrieve(Int32 lnFormatType) at System.DirectoryServices.AccountManagement.ADStoreCtx.LoadDomainInfo() at System.DirectoryServices.AccountManagement.ADStoreCtx.get_UserSuppliedServerName() at System.DirectoryServices.AccountManagement.ADDNLinkedAttrSet.BuildPathFromDN(String dn) at System.DirectoryServices.AccountManagement.ADDNLinkedAttrSet.MoveNextPrimaryGroupDN() at System.DirectoryServices.AccountManagement.ADDNLinkedAttrSet.MoveNext() at System.DirectoryServices.AccountManagement.FindResultEnumerator1.MoveNext() at System.DirectoryServices.AccountManagement.FindResultEnumerator1.System.Collections.IEnumerator.MoveNext()

Answer 1

looking though reflector at System.DirectoryServices.AccountManagement the internal class "UnsafeNativeMethods" is implemented in native code, so UserSuppliedServerName one level up is all I can go on without looking at the CLR VM, (frankly im not sure even how to do that) Seems that a node is failing to return its primary group, so perhaps consider other implementations, after a bit of googling ive come across these that may help

• Active Directory and nested groups this one may be promising heres the code sample..

      public IList<string> FindUserGroupsLdap(string username)
  { 
      // setup credentials and connection  
      var credentials = new NetworkCredential("username", "password", "domain");  
      var ldapidentifier = new LdapDirectoryIdentifier("server", 389, true, false); 
      var ldapConn = new LdapConnection(ldapidentifier, credentials); 
      // retrieving the rootDomainNamingContext, this will make sure we query the absolute root   
      var getRootRequest = new SearchRequest(string.Empty, "objectClass=*", SearchScope.Base, "rootDomainNamingContext");  
      var rootResponse = (SearchResponse)ldapConn.SendRequest(getRootRequest);   
      var rootContext = rootResponse.Entries[0].Attributes["rootDomainNamingContext"][0].ToString();  
      // retrieve the user 
      string ldapFilter = string.Format("(&(objectCategory=person)(sAMAccountName={0}))", username); 
      var getUserRequest = new SearchRequest(rootContext, ldapFilter, SearchScope.Subtree, null);  
      var userResponse = (SearchResponse)ldapConn.SendRequest(getUserRequest);     
      // send a new request to retrieve the tokenGroups attribute, we can not do this with our previous request since 
      // tokenGroups needs SearchScope.Base (dont know why...)  
      var tokenRequest = new SearchRequest(userResponse.Entries[0].DistinguishedName, "(&(objectCategory=person))", SearchScope.Base, "tokenGroups");  
      var tokenResponse = (SearchResponse)ldapConn.SendRequest(tokenRequest);  
      var tokengroups = tokenResponse.Entries[0].Attributes["tokenGroups"].GetValues(typeof(byte[])); 
      // build query string this query will then look like (|(objectSid=sid)(objectSid=sid2)(objectSid=sid3))  
      // we need to convert the given bytes to a hexadecimal representation because thats the way they   
      // sit in ActiveDirectory  
      var sb = new StringBuilder();  
      sb.Append("(|");   
      for (int i = 0; i < tokengroups.Length; i++)  
      {  
          var arr = (byte[])tokengroups[i];    
          sb.AppendFormat("(objectSid={0})", BuildHexString(arr));   
      }   
      sb.Append(")");    
      // send the request with our build query. This will retrieve all groups with the given objectSid
      var groupsRequest = new SearchRequest(rootContext, sb.ToString(), SearchScope.Subtree, "sAMAccountName"); 
      var groupsResponse = (SearchResponse)ldapConn.SendRequest(groupsRequest); 
      // loop trough and get the sAMAccountName (normal, readable name)   
      var userMemberOfGroups = new List<string>();    
      foreach (SearchResultEntry entry in groupsResponse.Entries)    
      userMemberOfGroups.Add(entry.Attributes["sAMAccountName"][0].ToString());  
      return userMemberOfGroups;
  } 
  
  private string BuildHexString(byte[] bytes)
  {  
      var sb = new StringBuilder(); 
      for (int i = 0; i < bytes.Length; i++) 
      sb.AppendFormat("\\{0}", bytes[i].ToString("X2")); 
      return sb.ToString();
  }
  

These are more for info purposes

• How to use the PrimaryGroupID attribute to find the primary group for a user
• Determining User Group Membership in Active Directory and ADAM