ClassCastException when using NTLM Authentication with struts

[Alex Philippi]

Hi,
our web app uses the NTLM Authentication for SSO. This NTLM filter called for every action the user made. For legacy support the user could use some old struts actions.

Everthing is ok but when the user click on an struts action we get this weird exception:

java.lang.ClassCastException: our.company.name.NtlmHttpServletRequest cannot be cast to javax.servlet.ServletRequestWrapper
org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1062)
org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:386)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:229)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
javax.servlet.http.HttpServlet.service(HttpServlet.java:697)
javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
com.dhc.dhcvision.server.servlet.filter.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:75)
com.dhc.dhcvision.server.servlet.filter.CacheAndResponseFilter.doFilter(CacheAndResponseFilter.java:108)
com.dhc.dhcvision.server.servlet.filter.SSOFilter.handleSSOLogin(SSOFilter.java:223)
com.dhc.dhcvision.server.servlet.filter.SSOFilter.doFilter(SSOFilter.java:144)
org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)

The NtlmHttpServletRequest:

public class NtlmHttpServletRequest extends HttpServletRequestWrapper {

    Principal principal;

    NtlmHttpServletRequest (HttpServletRequest req, Principal principal) {
        super(req);
        this.principal = principal;
    }

    public String getRemoteUser() {
        return principal.getName();
    }

    public Principal getUserPrincipal() {
        return principal;
    }

    public String getAuthType() {
        return "NTLM";
    }
}

I dont get it... Normally there could not be a ClassCastException. Any ideas?

We use struts-version 1.2.8 and JBOSS 4.0.5

Best regards
Alex