check if user is a member of a group

Question

I have a code to check if the user is a member of a group. I am using this at my login.

Please note I have a domain user and local user eg. testdomain\administrator and administrator.

This is the code I use:

using (DirectoryEntry groupEntry = new DirectoryEntry("WinNT://./" + userGroupName + ",group"))
{
    foreach (object member in (IEnumerable)groupEntry.Invoke("Members"))
    {
        using (DirectoryEntry memberEntry = new DirectoryEntry(member))
        {
            string completeName = memberEntry.Name;
            DirectoryEntry domainValue = GUIUtility.FindDomain(memberEntry);
            if (domainValue != null)
            {
                completeName = domainValue.Name + "\\" + memberEntry.Name;
            }
            Global.logger.Info("completeName from " + userGroupName + " = " + completeName);
            if (userName.Equals(completeName, StringComparison.InvariantCultureIgnoreCase))
            {
                Global.logger.Debug("IsUserPartOfWindowsGroup returned True with username =" + userName + " , UserGroupName = " + userGroupName);
                return true;
            }
        }
    }
    Global.logger.Debug("IsUserPartOfWindowsGroup returned false for username =" + userName + " , UserGroupName = " + userGroupName);
    return false;
}

This code works, but

DirectoryEntry domainValue = GUIUtility.FindDomain(memberEntry);

is taking a lot of time in the profiler as I see it. Is there a better/ faster way to handle this?

public static DirectoryEntry FindDomain(DirectoryEntry memberEntry)
{
    if (memberEntry.Parent != null)
    {
        if (memberEntry.Parent.SchemaClassName.Equals("domain", StringComparison.InvariantCultureIgnoreCase))
        {
            return memberEntry.Parent;
        }
    }
    return null;
}

another way:

DirectoryEntry entry = new DirectoryEntry("LDAP://" + domain, userName, Password);
DirectorySearcher mySearcher = new DirectorySearcher(entry);
mySearcher.Filter = "(&(objectClass=user)(|(cn=" + userName + ")(sAMAccountName=" + userName + ")))";
SearchResult result = mySearcher.FindOne();

Global.logger.Info("result == " + result.Path);
foreach (string GroupPath in result.Properties["memberOf"])
{
    if (GroupPath.Contains(adminGroupName))
    {
        Global.logger.Info(compUsrNameForEncryption + "exists in " + adminGroupName);
    }
}

Answer 1

This is pretty close to what I use:

public bool IsUserInGroup(string userName, string groupName)
{
    using (var context = new PrincipalContext(ContextType.Machine))
    {
        using (var searcher = new PrincipalSearcher(new UserPrincipal(context) { SamAccountName = userName }))
        {
            using (var user = searcher.FindOne() as UserPrincipal)
            {
                return user != null && user.IsMemberOf(context, IdentityType.SamAccountName, groupName);
            }
        }
    }
}

I haven't tested it for local users though. The logic works in my domain, I just changed PrincipalContext(ContextType.Machine) so it should look at local users now.

Don't forget to add a reference and using statement for System.DirectoryServices.AccountManagement