Determine if user is in AD group for .NET 4.0 application

Question

I am trying to determine if a user is a member of an Active Directory (AD) group for an internal ASP.NET 4.0 application. The code below throws an "Attempted to access an unloaded appdomain" exception error on the last line (return statement) in the case when the user is not a member of the AD group.

public static bool IsInADGroup(string userName, string groupName)
{
    var principalContext = new PrincipalContext(ContextType.Domain);
    UserPrincipal userPrincipal = UserPrincipal.FindByIdentity(principalContext, userName);
    if (userPrincipal == null)
        return false;

    GroupPrincipal groupPrincipal = GroupPrincipal.FindByIdentity(principalContext, groupName);
    if (groupPrincipal == null)
        return false;

      return userPrincipal.IsMemberOf(groupPrincipal);
}

Any ideas on how to fix or other workarounds?

Answer 1

Could this bug be your problem?

I've solved the same problems using this workaround:

           using (DirectoryEntry rootDse = new DirectoryEntry("LDAP://rootdse"))
        {
            var dnsName = rootDse.Properties["dnsHostName"].Value.ToString();
            using (PrincipalContext ctx = new PrincipalContext(ContextType.Domain, dnsName)) {}