CAS Spring Security 3 整合配置

 通常来讲， Web 应用的安全性包括用户认证（ Authentication ）和用户受权（ Authorization ）两个部分。用户认证指的是验证某个用户是否为系统中的合法主体，也就是说用户可否访问该系统。用户受权指的是验证某个用户是否有权限执行某个操做。在一个系统中，不一样用户所具备的权限是不一样的。好比对一个文件来讲，有的用户只能进行读取，而有的用户能够进行修改。通常来讲，系统会为不一样的用户分配不一样的角色，而每一个角色则对应一系列的权限。

  对于上面提到的两种应用情景， Spring Security 框架都有很好的支持。在用户认证方面， Spring Security 框架支持主流的认证方式，包括 HTTP 基本认证、 HTTP 表单验证、 HTTP 摘要认证、 OpenID 和 LDAP 等。在用户受权方面， Spring Security 提供了基于角色的访问控制和访问控制列表（ Access Control List ， ACL ），能够对应用中的领域对象进行细粒度的控制。

若 Spring Security 整合 CAS 单点登陆 ， 使用 CAS 进行认证和获取受权信息 ， 使用 Spring Security 验证权限 ，则能够很好的把公共的认证和受权与具体应用剥离开来，同时简化应用的配置。本文就 Spring Security 与 CAS 的整合进行说明。

一 、基本需求 
1. jdk 5.0 
2. tomcat 6 
3. Spring 3.0.5.RELEASE 
4. Spring Security 3.1.0.RELEASE 
5. CAS cas-server-3.4.7， cas-client-3.2.0 
6. 使用http协议进行传输 
7. 经过jdbc进行用户验证，须要经过casserver提供除登陆用户名之外的附加信息（用于Spring Security 进行验证权限） 
2、搭建CAS Server 
1. 把从 http://www.jasig.org/cas/download 上下载cas解压找到 cas-server-3.4.7-releasecas-server-3.4.7modulescas-server-webapp-3.4.7.war , 解压cas-server-webapp-3.4.7.war ，部署在至tomcat上端口为 8080的server上，如部署路径为 http://localhost:8080/cas 。为了达到需求目的，咱们主要须要对 /WEB-INF/deployerConfigContext.xml 文件进行修改。

2. 使用 jdbc 数据源进行用户认证，须要修改 deployerConfigContext.xml 的 authenticationHandlers 方式 
<property name=" authenticationHandlers "> 
<list> 
<!-- 
| This is the authentication handler that authenticates services by means of callback via SSL, thereby validating 
| a server side SSL certificate. 
+--> 
<bean class="org.jasig.cas.authentication.handler.support.HttpBasedServiceCredentialsAuthenticationHandler" 
p:httpClient-ref="httpClient" /> 
<!-- 
| This is the authentication handler declaration that every CAS deployer will need to change before deploying CAS  
| into production. The default SimpleTestUsernamePasswordAuthenticationHandler authenticates UsernamePasswordCredentials 
| where the username equals the password. You will need to replace this with an AuthenticationHandler that implements your 
| local authentication strategy. You might accomplish this by coding a new such handler and declaring 
| edu.someschool.its.cas.MySpecialHandler here, or you might use one of the handlers provided in the adaptors modules. 
+--> 
// 注释掉，不然只要用户名和密码一致的话均可以获得认证   
<!-- bean class="org.jasig.cas.authentication.handler.support.SimpleTestUsernamePasswordAuthenticationHandler" / --> 

// 数据库认证方式 
<!--DATABASE -- > 
<bean class="org.jasig.cas.adaptors.jdbc.QueryDatabaseAuthenticationHandler">
<property name="dataSource" ref="dataSource" /> 
<property name="sql" value="select password from t_admin_user where login_name=?" /> 
</bean> 

</list> 
<property name="authenticationHandlers">

<!-- DATABASE 增长数据源配置 --> 
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> 
<property name="driverClassName"><value>com.mysql.jdbc.Driver</value></property> 
<property name="url"><value>jdbc:mysql:///cas?useUnicode=true&amp;characterEncoding=utf-8</value></property> 
<property name="username"><value>root</value></property> 
</bean>

3. 经过 casserver 提供除登陆用户名之外的附加信息（用于 Spring Security 进行验证权限），修改 /WEB-INF/ deployerConfigContext .xml 
3.1 修改 credentialsToPrincipalResolvers 
<property name="credentialsToPrincipalResolvers"> 
<list> 
<bean class="org.jasig.cas.authentication.principal.UsernamePasswordCredentialsToPrincipalResolver" >  
<property name="attributeRepository" ref="attributeRepository" /> // 增长此属性，为认证过的用户的 Principal 添加属性 
</bean> 
<bean class="org.jasig.cas.authentication.principal.HttpBasedServiceCredentialsToPrincipalResolver" /> 
</list> 
</property> 

3.2 修改该文件中默认的 attributeRepositorybean 配置 
<!-- 使用 SingleRowJdbcPersonAttributeDao 获取更多用户的信息 --> 
<bean id="attributeRepository" class="org.jasig.services.persondir.support.jdbc.SingleRowJdbcPersonAttributeDao"> 
<constructor-arg index="0" ref="dataSource"/> 
<constructor-arg index="1" value="select role_name,group_name from role where login_name = ?"/>  
<!-- 这里的 key 需写 username,value 对应数据库用户名字段 --> 
<property name="queryAttributeMapping"> 
<map> 
<entry key="username" value="login_name"/> 
</map> 
</property> 
<!--key 对应数据库字段， value 对应客户端获取参数 --> 
<property name="resultAttributeMapping"> 
<map> 
<entry key="role_name" value="authorities"/> // 这个从数据库中获取的角色，用于在应用中 security 的权限验证 
</map> 
</property> 
</bean>

3.3 修改该文件中最默认的 serviceRegistryDao 中的属性所有注释掉 
这个 bean 中的 RegisteredServiceImpl 的 ignoreAttributes 属性将决定是否添加 attributes 属性内容，默认为 false: 不添加，只有去掉这个配置， cas server 才会将获取的用户的附加属性添加到认证用的 Principal 的 attributes 中去。 
<bean id="serviceRegistryDao" class="org.jasig.cas.services.InMemoryServiceRegistryDaoImpl"></bean>

3.4 若采用 CAS 的 Cas20ServiceTicketValidator 认证，则须要修改 WEB-INFviewjspprotocol2.0casServiceValidationSuccess.jsp 文件，才能把获取的属性传递至客户端 
<%@ page session="false" %> 
<%@ taglib prefix="c" uri=" http://java.sun.com/jsp/jstl/core " %> 
<%@ taglib uri=" http://java.sun.com/jsp/jstl/functions " prefix="fn" %> 
<cas:serviceResponse xmlns:cas=\'http://www.yale.edu/tp/cas\'> 
<cas:authenticationSuccess> 
<cas:user>${fn:escapeXml(assertion.chainedAuthentications[fn:length(assertion.chainedAuthentications)-1].principal.id)}</cas:user> 

<c:if test="${not empty pgtIou}"> 
<cas:proxyGrantingTicket>${pgtIou}</cas:proxyGrantingTicket> 
</c:if> 
<c:if test="${fn:length(assertion.chainedAuthentications) > 1}"> 
<cas:proxies> 
<c:forEach var="proxy" items="${assertion.chainedAuthentications}" varStatus="loopStatus" begin="0" end="${fn:length(assertion.chainedAuthentications)-2}" step="1"> 
<cas:proxy>${fn:escapeXml(proxy.principal.id)}</cas:proxy> 
</c:forEach> 
</cas:proxies> 
</c:if> 
<!-- 增长以下内容 --> 
<c:if test="${fn:length(assertion.chainedAuthentications[fn:length(assertion.chainedAuthentications)-1].principal.attributes)> 0}"> 
<cas:attributes> 
<c:forEach  
var="attr" 
items="${assertion.chainedAuthentications[fn:length(assertion.chainedAuthentications)-1].principal.attributes}" 
varStatus="loopStatus"  
begin="0" 
end="${fn:length(assertion.chainedAuthentications[fn:length(assertion.chainedAuthentications)-1].principal.attributes)-1}" 
step="1"> 
<cas:${fn:escapeXml(attr.key)}>${fn:escapeXml(attr.value)}</cas:${fn:escapeXml(attr.key)}> 
</c:forEach> 
</cas:attributes> 
</c:if> 
</cas:authenticationSuccess> 
</cas:serviceResponse>

至此， CAS Server 搭建完毕。

3、搭建 CAS Client （即 Spring Security ）应用

1. CAS Client 下须要把 spring-security-cas-3.1.0.M2.jar 等 Spring Security 相关的jar 引入，把 cas-client-core-3.2.0.jar 引入，用于从 cas server 上获取相关认证与受权信息。

2. CAS Client 应用的 web.xml ， 增长以下 
<!-- spring 配置文件 - -> 
<context-param> 
<param-name>contextConfigLocation</param-name> 
<param-value>classpath:applicationContext-security-ns.xml</param-value> 
</context-param>

<!-- spring security filter --> 
<filter> 
<filter-name>springSecurityFilterChain</filter-name> 
<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class> 
</filter>

<filter-mapping> 
<filter-name>springSecurityFilterChain</filter-name> 
<url-pattern>/*</url-pattern> 
</filter-mapping>

<!-- spring 默认侦听器 --> 
<listener> 
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> 
</listener>

3. spring security 文件的配置 applicationContext-security-ns.xml

<?xml version="1.0"?> 
<beans xmlns=" http://www.springframework.org/schema/beans "  
xmlns:security=" http://www.springframework.org/schema/security "  
xmlns:xsi=" http://www.w3.org/2001/XMLSchema-instance "  
xsi:schemaLocation=" http://www.springframework.org/schema/beans   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd   
http://www.springframework.org/schema/security   http://www.springframework.org/schema/security/spring-security-3.1.xsd ">

<!-- 
Enable security, let the casAuthenticationEntryPoint handle all intercepted urls. 
The CAS_FILTER needs to be in the right position within the filter chain. 
-->  
<security:http entry-point-ref="casAuthenticationEntryPoint" auto-config="true"> 
<security:intercept-url pattern="/**" access="ROLE_USER"></security:intercept-url> 
<security:custom-filter position="CAS_FILTER" ref="casAuthenticationFilter"></security:custom-filter> 
</security:http>

<!-- 
Required for the casProcessingFilter, so define it explicitly set and 
specify an Id Even though the authenticationManager is created by 
default when namespace based config is used. 
--> 
<security:authentication-manager alias="authenticationManager"> 
<security:authentication-provider ref="casAuthenticationProvider"></security:authentication-provider> 
</security:authentication-manager>

<!-- 
This section is used to configure CAS. The service is the 
actual redirect that will be triggered after the CAS login sequence. 
--> 
<bean id="serviceProperties" class="org.springframework.security.cas.ServiceProperties"> 
//http://localhost:8088/SpringSecurity 具体应用 
// j_spring_cas_security_check spring 的虚拟 URL ，此标志标识使用 CAS authentication upon return from CAS SSO login. 
<property name="service" value=" http://localhost:8088/SpringSecurity/j_spring_cas_security_check"></property > 
<property name="sendRenew" value="false"></property> 
</bean>

<!-- 
The CAS filter handles the redirect from the CAS server and starts the ticket validation. 
--> 
<bean id="casAuthenticationFilter" class="org.springframework.security.cas.web.CasAuthenticationFilter"> 
<property name="authenticationManager" ref="authenticationManager"></property> 
</bean>

<!-- 
The entryPoint intercepts all the CAS authentication requests. 
It redirects to the CAS loginUrl for the CAS login page. 
--> 
<bean id="casAuthenticationEntryPoint" class="org.springframework.security.cas.web.CasAuthenticationEntryPoint"> 
<property name="loginUrl" value=" http://localhost:8080/cas/login"></property> //SSO 登陆地址 
<property name="serviceProperties" ref="serviceProperties"></property> 
</bean>

<!-- 
Handles the CAS ticket processing. 
--> 
<bean id="casAuthenticationProvider" class="org.springframework.security.cas.authentication.CasAuthenticationProvider"> 
<property name="authenticationUserDetailsService" ref="authenticationUserDetailsService"/> 
<property name="serviceProperties" ref="serviceProperties"></property> 
<property name="ticketValidator"> 
<bean class="org.jasig.cas.client.validation.Cas20ServiceTicketValidator"> 
<constructor-arg index="0" value=" http://localhost:8080/cas " /> //SSO 验证地址 
</bean> 
</property> 
<property name="key" value="cas"></property> 

</bean> 
<!-- authorities 对应 CAS server 的 登陆属性， 在此设置到 spirng security 中，用于spring security 的验证 --> 
<bean id="authenticationUserDetailsService" class="org.springframework.security.cas.userdetails.GrantedAuthorityFromAssertionAttributesUserDetailsService"> 
<constructor-arg> 
<array> 
<value>authorities</value> 
</array> 
</constructor-arg> 
</bean> 
</beans>

至此， CAS 客户端搭建完毕。

4、总结

经过上述的配置，则具体应用在使用的时候，用户认证和受权则无需过问，只需在应用中配置相关的角色访问权限便可。即，只需对下面的红色部分进行修改，便可以完成应用的认证和受权工做。大大简化了应用和认证与受权的剥离工做

<security:http entry-point-ref="casAuthenticationEntryPoint" auto-config="true"> 
<security:intercept-url pattern="/**" access="ROLE_USER"></security:intercept-url>  
<security:custom-filter position="CAS_FILTER" ref="casAuthenticationFilter"></security:custom-filter> 
</security:http>

5、扩展

若在同一 SSO 下有多个应用， 同一户在不一样应用下有不一样的角色，则考虑扩展获取用户权限的环节；资源和角色在数据库中进行配置等等。