Grails Spring Security AbstractPreAuthenticatedProcessingFilter redirect - spring

Question

I am trying to do PreAuthentication using Spring Security Grails plugin. I read the pre authentication documentation given below, but could not find anything concrete for my situation
http://static.springsource.org/spring-security/site/docs/3.0.x/reference/preauth.html
In my situation, we have a agent which parses the SAML request and gives a map after successful authentication. Recommendation is to use this jar. Hence, I extended AbstractPreAuthenticatedProcessingFilter and try to do this
#Override
protected Object getPreAuthenticatedPrincipal(HttpServletRequest request) {
userInfo = agent.readToken(request);
if (!userInfo){
WebUtils.retrieveGrailsWebRequest().getCurrentResponse().sendRedirect(ssoUrl)
}
return userInfo
}
I have placed myFilter under src/groovy and registered this filter in BootStrap
def init = { servletContext ->
SpringSecurityUtils.clientRegisterFilter(
'myFilter', SecurityFilterPosition.PRE_AUTH_FILTER.order)
}
Its getting loaded correctly, but filter is not issuing a redirect. First of all, I wanted to check if this is the right approach and if it is, how to get redirect working.
I have asked the same question in grails user forum
Any help is greatly appreciated.
Update:
Final configuration which worked for me
Wrote MyAuthenticationService which implements AuthenticationUserDetailsService as suggested. You also have to define preAuthenticatedAuthenticationProvider which wraps your custom service
resources.groovy
securityFilter(MySSOAuthFilters){ bean ->
authenticationManager = ref('authenticationManager')
grailsApplication = ref('grailsApplication')
}
customUserDetailsService(MyAuthenticationService)
preAuthenticatedAuthenticationProvider(org.springframework.security.web.authentication.preauth.PreAuthenticatedAuthenticationProvider) {
preAuthenticatedUserDetailsService = ref('customUserDetailsService')
}
I was not able to do <form-login> because in Grails, this is done using
grails.plugins.springsecurity.auth.loginFormUrl config parameter which only accepts relative url.
What I ended up doing is grails.plugins.springsecurity.auth.loginFormUrl = '/login/index'
In LoginController
def index() {
if(springSecurityService.isLoggedIn()){
log.info("User is logged in")
return redirect(controller: 'mycontroller', action: 'list')
}
log.info("user is not logged in...redirect to sso.")
return redirect(url: ssoUrl)
}
Hope this helps

Answer 1

A couple of things I see that need to be changed.
First, do not to send a redirect in the preauth filter just simply return null. The preauth filter is only used to return a subject that your AuthenticationUserDetailsService can use to create the UserDetails object by implementing the method below in your implementation of the AuthenticationUserDetailsService .
public UserDetails loadUserDetails(AbstractAuthenticationToken token) {
return createUserFromSubject((Subject) token.getPrincipal());
}
Second, set the form login page as part of your configuration. This will be used to redirect to if no subject exists.
<form-login login-page="http://url_youwanttoredirect_to_on_auth_req" authentication-failure-url="http://url_youwanttoredirect_to_on_auth_req"/>