Package org.springframework.security.cas.web

Class CasAuthenticationFilter

java.lang.Object
org.springframework.web.filter.GenericFilterBean
org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter
org.springframework.security.cas.web.CasAuthenticationFilter
All Implemented Interfaces:
jakarta.servlet.Filter, org.springframework.beans.factory.Aware, org.springframework.beans.factory.BeanNameAware, org.springframework.beans.factory.DisposableBean, org.springframework.beans.factory.InitializingBean, org.springframework.context.ApplicationEventPublisherAware, org.springframework.context.EnvironmentAware, org.springframework.context.MessageSourceAware, org.springframework.core.env.EnvironmentCapable, org.springframework.web.context.ServletContextAware
public class CasAuthenticationFilter extends AbstractAuthenticationProcessingFilter
Processes a CAS service ticket, obtains proxy granting tickets, and processes proxy tickets.

Service Tickets

A service ticket consists of an opaque ticket string. It arrives at this filter by the user's browser successfully authenticating using CAS, and then receiving an HTTP redirect to a service. The opaque ticket string is presented in the ticket request parameter.

This filter monitors the service URL so that it can receive the service ticket and process it. By default, this filter processes the URL /login/cas. When processing this URL, the value of ServiceProperties.getService() is used as the service when validating the ticket. This means that it is important that ServiceProperties.getService() specifies the same value as the filterProcessesUrl.

Processing the service ticket involves creating a CasServiceTicketAuthenticationToken which uses CasServiceTicketAuthenticationToken.CAS_STATEFUL_IDENTIFIER for the principal and the opaque ticket string as the credentials.

Obtaining Proxy Granting Tickets

If specified, the filter can also monitor the proxyReceptorUrl. The filter will respond to the requests matching this url so that the CAS Server can provide a PGT to the filter. Note that in addition to the proxyReceptorUrl a non-null proxyGrantingTicketStorage must be provided in order for the filter to respond to proxy receptor requests. By configuring a shared ProxyGrantingTicketStorage between the TicketValidator and the CasAuthenticationFilter, one can have the CasAuthenticationFilter handling the proxying requirements for CAS.

Proxy Tickets

The filter can process tickets present on any url. This is useful when one wants to process proxy tickets. In order for proxy tickets to get processed, ServiceProperties.isAuthenticateAllArtifacts() must return true. Additionally, if the request is already authenticated, authentication will not occur. Last, AuthenticationDetailsSource.buildDetails(Object) must return a ServiceAuthenticationDetails. This can be accomplished using the ServiceAuthenticationDetailsSource. In this case, ServiceAuthenticationDetails.getServiceUrl() will be used for the service url.

Processing the proxy ticket involves creating a CasServiceTicketAuthenticationToken which uses CasServiceTicketAuthenticationToken.CAS_STATELESS_IDENTIFIER for the principal and the opaque ticket string as the credentials. When a proxy ticket is successfully authenticated, the FilterChain continues and the authenticationSuccessHandler is not used.

Notes about the AuthenticationManager

The configured AuthenticationManager is expected to provide a provider that can recognise CasServiceTicketAuthenticationTokens containing this special principal name, and process them accordingly by validation with the CAS server. Additionally, it should be capable of using the result of ServiceAuthenticationDetails.getServiceUrl() as the service when validating the ticket.

Example Configuration

An example configuration that supports service tickets, obtaining proxy granting tickets, and proxy tickets is illustrated below: 

 <b:bean id="serviceProperties"
     class="org.springframework.security.cas.ServiceProperties"
     p:service="https://service.example.com/cas-sample/login/cas"
     p:authenticateAllArtifacts="true"/>
 <b:bean id="casEntryPoint"
     class="org.springframework.security.cas.web.CasAuthenticationEntryPoint"
     p:serviceProperties-ref="serviceProperties" p:loginUrl="https://login.example.org/cas/login" />
 <b:bean id="casFilter"
     class="org.springframework.security.cas.web.CasAuthenticationFilter"
     p:authenticationManager-ref="authManager"
     p:serviceProperties-ref="serviceProperties"
     p:proxyGrantingTicketStorage-ref="pgtStorage"
     p:proxyReceptorUrl="/login/cas/proxyreceptor">
     <b:property name="authenticationDetailsSource">
         <b:bean class="org.springframework.security.cas.web.authentication.ServiceAuthenticationDetailsSource"/>
     </b:property>
     <b:property name="authenticationFailureHandler">
         <b:bean class="org.springframework.security.web.authentication.SimpleUrlAuthenticationFailureHandler"
             p:defaultFailureUrl="/casfailed.jsp"/>
     </b:property>
 </b:bean>
 <!--
     NOTE: In a real application you should not use an in memory implementation. You will also want
           to ensure to clean up expired tickets by calling ProxyGrantingTicketStorage.cleanup()
  -->
 <b:bean id="pgtStorage" class="org.apereo.cas.client.proxy.ProxyGrantingTicketStorageImpl"/>
 <b:bean id="casAuthProvider" class="org.springframework.security.cas.authentication.CasAuthenticationProvider"
     p:serviceProperties-ref="serviceProperties"
     p:key="casAuthProviderKey">
     <b:property name="authenticationUserDetailsService">
         <b:bean
             class="org.springframework.security.core.userdetails.UserDetailsByNameServiceWrapper">
             <b:constructor-arg ref="userService" />
         </b:bean>
     </b:property>
     <b:property name="ticketValidator">
         <b:bean
             class="org.apereo.cas.client.validation.Cas20ProxyTicketValidator"
             p:acceptAnyProxy="true"
             p:proxyCallbackUrl="https://service.example.com/cas-sample/login/cas/proxyreceptor"
             p:proxyGrantingTicketStorage-ref="pgtStorage">
             <b:constructor-arg value="https://login.example.org/cas" />
         </b:bean>
     </b:property>
     <b:property name="statelessTicketCache">
         <b:bean class="org.springframework.security.cas.authentication.EhCacheBasedTicketCache">
             <b:property name="cache">
                 <b:bean class="net.sf.ehcache.Cache"
                   init-method="initialise"
                   destroy-method="dispose">
                     <b:constructor-arg value="casTickets"/>
                     <b:constructor-arg value="50"/>
                     <b:constructor-arg value="true"/>
                     <b:constructor-arg value="false"/>
                     <b:constructor-arg value="3600"/>
                     <b:constructor-arg value="900"/>
                 </b:bean>
             </b:property>
         </b:bean>
     </b:property>
 </b:bean>