Question

I’m using WindowsTokenRoleProvider to determine Active Directory group membership in an ASP.NET web application.

My problem is that performance is not good, especially when a user is in many groups. As an example, I am in 253(!) groups, and WindowsTokenRoleProvider is taking around 150 seconds to determine what groups I am in.

I know I can use caching so that this isn’t done on subsequent requests for a user, but obviously it isn’t acceptable to take that long on the first hit.

What are my options? Can I force WindowsTokenRoleProvider to only consider certain groups? (I’m only interested in 5).

Answer 1

Some testing has revealed that my problem is that calling:

Roles.IsUserInRole(groupName)

is accessing the method GetRolesForUser in the RoleProvider – which is retrieving details of every role the user is a member of.

But calling:

Roles.Provider.IsUserInRole(groupName)

determines whether or not the user is in the group – without retrieving the details of every role the user is in.

Weird, but it looks like using Roles.Provider.IsUserInRole will solve my problem.

* UPDATE *

It turns out that this is just a partial workaround; if I use imperative permission checks, or ‘allow’ and ‘deny’ in web.comfig, then WindowsTokenRoleProvider still goes and slowly gets details of every group the user is a member of :o(

So my question still stands…

* UPDATE *

I solved this by creating a class that extends from WindowsTokenRoleProvider and overriding GetRolesForUser so it only checks for membership of roles specified in the configuration. It includes caching too:

/// <summary>
/// Retrieve the list of roles (Windows Groups) that a user is a member of
/// </summary>
/// <remarks>
/// Note that we are checking only against each system role because calling:
/// base.GetRolesForUser(username);
/// Is _very_ slow if the user is in a lot of AD groups
/// </remarks>
/// <param name="username">The user to check membership for</param>
/// <returns>String array containing the names of the roles the user is a member of</returns>
public override string[] GetRolesForUser(string username)
{
    // Will contain the list of roles that the user is a member of
    List<string> roles = null;

    // Create unique cache key for the user
    string key = String.Concat(username, ":", base.ApplicationName);

    // Get cache for current session
    Cache cache = HttpContext.Current.Cache;

    // Obtain cached roles for the user
    if (cache[key] != null)
    {
        roles = new List<string>(cache[key] as string[]);
    }

    // Was the list of roles for the user in the cache?
    if (roles == null)
    {
        roles = new List<string>();

        // For each system role, determine if the user is a member of that role
        foreach (SystemRoleElement role in WebConfigSection.Settings.SystemRoles)
        {
            if (base.IsUserInRole(username, role.Name))
            {
                roles.Add(role.Name);
            }
        }

        // Cache the roles for 1 hour
        cache.Insert(key, roles.ToArray(), null, DateTime.Now.AddHours(1), Cache.NoSlidingExpiration);
    }

    // Return list of roles for the user
    return roles.ToArray();
}