cas简介

梦里梦外; 2022-05-15 14:21 224阅读 0赞

一、概述

central authentication service，中央认证服务。耶鲁大学的一个开源项目，目的是为web应用系统提供一种可靠的单点登录方法。

cas包括两个部分，cas server和cas client。cas server负责对用户的认证；cas client负责处理对客户端受保护资源的访问请求，当登录时，重定向到cas server。

二、使用示例

从官网下载cas-server和cas-client的发行包。在cas-server包里的module目录下有cas-server.war的示例项目。网上搜索cas-client的示例项目mywebapp.war，不太好找。

示例war使用步骤

1. 配置tomcat虚拟主机

在tomcat中server.xml配置3个虚拟主机，两个客户端www.gougou.com和www.maomao.com，一个服务端www.server.com。

在window下，将这3个域名和127.0.0.1做映射。在tomcat配置的虚拟主机的目录下，分别放置相应的war包，启动tomcat自动部署项目，然后关闭tomcat，将项目包的文件夹改名为ROOT，这样可以直接访问。在客户端的项目的lib目录下复制入cas-client-core的jar和commons-loggings的jar。启动tomcat，测试3个域名是否可以访问。可能出现java版本和cas-server版本的兼容问题，一般是java版本过高，考虑降低java版本。

2. 修改客户端的配置文件

修改客户端的web.xml

<filter>
    
                       <filter-name>CAS Authentication Filter</filter-name>
    
                       <filter-class>org.jasig.cas.client.authentication.AuthenticationFilter</filter-class>
    
                       <init-param>
    
                                <param-name>casServerLoginUrl</param-name>
    
                                <param-value>http://www.server.com:8081/login</param-value>
    
                       </init-param>
    
                       <init-param>
    
                                <param-name>serverName</param-name>
    
                                <param-value>http://www.maomao.com:8081</param-value>
    
                       </init-param>
    
                       <init-param>
    
                                <param-name>renew</param-name>
    
                                <param-value>false</param-value>
    
                       </init-param>
    
                       <init-param>
    
                                <param-name>gateway</param-name>
    
                                <param-value>false</param-value>
    
                       </init-param>
    
             </filter>
    
            
    
             <filter>
    
                       <filter-name>CAS Validation Filter</filter-name>
    
                       <filter-class>org.jasig.cas.client.validation.Cas20ProxyReceivingTicketValidationFilter</filter-class>
    
                       <init-param>
    
                                <param-name>casServerUrlPrefix</param-name>
    
                                <param-value>http://www.server.com:8081</param-value>
    
                       </init-param>
    
                       <init-param>
    
                                <param-name>serverName</param-name>
    
                                <param-value>http://www.maomao.com:8081</param-value>
    
                       </init-param>
    
                       
    
             </filter>

3. 修改服务端配置文件，设置为单点登录

cas服务器使用spring配置文件，使用cookie技术。ticketGrantingTicketCookieGenerator.xml设置cookie相关的。

修改cookie后，测试单点登录。

三、在项目开发中使用cas

使用eclipse开发，创建3个项目。一个casServer，和两个web客户端服务项目。分别配置两个客户端项目的web.xml中，的验证登录网址，以及服务端配置文件中cookie的配置，见上。

1. 在客户端获取登录用户名

4种方式

2. 修改服务器登录验证规则

在服务器cas的deployerConfigContext.xml中，配置用户认证登录方式，可以配置多个，只要其中之一通过就通过。

3. 使用配置的用户名和密码

4. 自定义验证规则

所有的认证类都继承自AuthenticationHandler。自定义的基于用户名和密码的验证类继承AbstractUsernamePasswordAuthenticationHandler。

编写MyUsernamePasswordAuthenticationHandler类

/**
    
     * 自定义的用户名密码认证类
    
     * 认证规则，密码是用户名的后两位，用户名长度需要大于3位
    
     * @author Administrator
    
     *
    
     */
    
    public class MyUsernamePasswordAuthenticationHandler extends AbstractUsernamePasswordAuthenticationHandler {
    
    
    
             @Override
    
             protected boolean authenticateUsernamePasswordInternal(UsernamePasswordCredentials credentials)
    
                                throws AuthenticationException {
    
                       // TODO Auto-generated method stub
    
                       //参数合法性判断
    
                       if(credentials == null){
    
                                return false;
    
                       }
    
                       //获取用户名和密码
    
                       final String username = credentials.getUsername();
    
                       final String password = credentials.getPassword();
    
                       //用户名长度合法性判断
    
                       if(username.length() < 3){
    
                                return false;
    
                       }
    
                       //密码是否与用户名后两位等同
    
                       if(password.length() > 0 && password.equals(username.substring(username.length() - 2))){
    
                                return true;
    
                       }
    
                       return false;
    
             }
    
    
    
    }

将自定的认证类配置到配置文件

5. 使用jdbc连接数据库认证登录

前提导入cas-server-support-jdbc-3.4.11.jar和mysql-connector的jar。配置数据库环境，创建数据库cas，添加表user，插入两个数据，密码采用md5加密。

在deployerConfigContext.xml的最后配置数据库连接dataSource。

<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    
        <property name="driverClassName" value="com.mysql.jdbc.Driver" />
    
        <property name="url" value="jdbc:mysql://localhost:3306/cas?characterEncoding=UTF-8" />
    
        <property name="username" value="root" />
    
        <property name="password" value="xxxx" />
    
        </bean>

可以使用两种方式查询数据库，需要配置在认证处理器里面

<property name="authenticationHandlers">
    
                                <list>
    
                                         <bean class="org.jasig.cas.authentication.handler.support.HttpBasedServiceCredentialsAuthenticationHandler"
    
                                                   p:httpClient-ref="httpClient" />
    
                                         
    
                                         <bean class="com.cas.authentication.MyUsernamePasswordAuthenticationHandler"></bean>
    
                                         
    
                                    
    
                                      
    
                                      <bean class="org.jasig.cas.adaptors.jdbc.QueryDatabaseAuthenticationHandler">
    
                                                <property name="dataSource" ref="dataSource" />
    
                                                <property name="sql" value="select password from user where username = ?" />
    
                                                <property name="passwordEncoder">
    
                                                            <bean class="org.jasig.cas.authentication.handler.DefaultPasswordEncoder">
    
                                                                     <constructor-arg value="MD5"/>
    
                                                                     <property name="characterEncoding" value="UTF-8"></property>
    
                                                            </bean>
    
                                                   </property>
    
                                               
    
                                      </bean>
    
                                </list>
    
                       </property>

6. 获取其他用户信息

1)返回用户的id

原始的cas服务器中，通过deployerConfigContext.xml中的<property name="credentialsToPrincipalResolvers">中的bean来将服务器中的credentials转换为pricinpal返回给客户端，为了返回id，需要自定义一个MyCredentialsToPrincipalResolver实现CredentialsToPrincipalResolver接口，并配置到这个文件中。

/**
    
     * 自定义的credentials转pricinpal的类
    
     * @author Administrator
    
     *
    
     */
    
    public class MyCredentialsToPrincipalResolver implements CredentialsToPrincipalResolver {
    
    
    
             private DataSource dataSource;
    
            
    
             public DataSource getDataSource() {
    
                       return dataSource;
    
             }
    
    
    
             public void setDataSource(DataSource dataSource) {
    
                       this.dataSource = dataSource;
    
             }
    
    
    
             @Override
    
             public Principal resolvePrincipal(Credentials credentials) {
    
                       // TODO Auto-generated method stub
    
                       //非空判断
    
                       if(credentials == null){
    
                                return null;
    
                       }
    
                       UsernamePasswordCredentials upCredentials = (UsernamePasswordCredentials)credentials;
    
                       final String username = upCredentials.getUsername();
    
                       final String password = upCredentials.getPassword();
    
                       String md5pwd = MD5Util.getPassword(password);
    
                       String sql = "select id from user where username = ? and password = ?";
    
                       int id;
    
                       JdbcTemplate jdbcTemplate = new JdbcTemplate(getDataSource());
    
                       id = jdbcTemplate.queryForInt(sql, username, md5pwd);
    
                       if(id > 0){
    
                                Principal principal = new SimplePrincipal(id+"");
    
                                return principal;
    
                       }
    
                       return null;
    
             }
    
    
    
             @Override
    
             public boolean supports(Credentials credentials) {
    
                       // TODO Auto-generated method stub
    
                       return credentials != null
    
                                         && UsernamePasswordCredentials.class
    
                                                            .isAssignableFrom(credentials.getClass());
    
             }
    
    
    
    }

配置文件

7. 获取更多用户信息

基本同上，在服务器返回自定义的principal时，将用户信息以map传入SimplePrincipal的第二个参数。

/**
    
     * 自定义的credentials转pricinpal的类
    
     * @author Administrator
    
     *
    
     */
    
    public class MyCredentialsToPrincipalResolver implements CredentialsToPrincipalResolver {
    
    
    
             private DataSource dataSource;
    
            
    
             public DataSource getDataSource() {
    
                       return dataSource;
    
             }
    
    
    
             public void setDataSource(DataSource dataSource) {
    
                       this.dataSource = dataSource;
    
             }
    
    
    
             @Override
    
             public Principal resolvePrincipal(Credentials credentials) {
    
                       // TODO Auto-generated method stub
    
                       //非空判断
    
                       if(credentials == null){
    
                                return null;
    
                       }
    
                       UsernamePasswordCredentials upCredentials = (UsernamePasswordCredentials)credentials;
    
                       final String username = upCredentials.getUsername();
    
                       final String password = upCredentials.getPassword();
    
                       Map<String, Object> map = new HashMap<>();
    
                       map.put("username", username);
    
                       map.put("password", password);
    
                       String address = "上海";
    
                       map.put("address", address);
    
                       String md5pwd = MD5Util.getPassword(password);
    
                       String sql = "select id from user where username = ? and password = ?";
    
                       int id;
    
                       JdbcTemplate jdbcTemplate = new JdbcTemplate(getDataSource());
    
                       id = jdbcTemplate.queryForInt(sql, username, md5pwd);
    
                       if(id > 0){
    
                                map.put("id", id);
    
                                Principal principal = new SimplePrincipal(id+"", map);
    
                                return principal;
    
                       }
    
                       return null;
    
             }
    
    
    
             @Override
    
             public boolean supports(Credentials credentials) {
    
                       // TODO Auto-generated method stub
    
                       return credentials != null
    
                                         && UsernamePasswordCredentials.class
    
                                                            .isAssignableFrom(credentials.getClass());
    
             }
    
    
    
    }

修改服务器的casServiceValidationSuccess.jsp文件

<%@ 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>
    
                       <cas:attributes>
    
                                <c:forEach items="${assertion.chainedAuthentications[fn:length(assertion.chainedAuthentications)-1].principal.attributes}"
    
                                         var="attr">
    
                                         <cas:${attr.key}>${attr.value}</cas:${attr.key}>
    
                                </c:forEach>
    
                       </cas:attributes>
    
             </cas:authenticationSuccess>
    
    </cas:serviceResponse>

修改deployerConfigContext.xml文件，将最后一个配置InMemoryServiceRegistryDaoImpl这个bean的所有属性注释掉。

注意，如果出现中文乱码，可以使用URLEncoder和URLDecoder在服务端用utf-8编码，在客户端用utf-8解码。

8. 使用监听器将服务器返回的数据封装成自定义对象放到session中

服务器返回数据后，以\_const\_cas\_assertion\_为key将Assertion对象session中去，利用这个，可以通过监听session，将Assertion对象封装成自定义对象放入session返回。

在客户端创建一个User类

略。

在客户端创建一个监听器类

/**
    
     * 自定义监听session信息的类
    
     * @author Administrator
    
     *
    
     */
    
    public class MySessionListener implements HttpSessionAttributeListener {
    
    
    
             @Override
    
             public void attributeAdded(HttpSessionBindingEvent event) {
    
                       // TODO Auto-generated method stub
    
                       String key = event.getName();
    
                       if(key.equals(AbstractCasFilter.CONST_CAS_ASSERTION)){
    
                                //监听获取Assertion对象
    
                                Assertion assertion = (Assertion) event.getSession().getAttribute(AbstractCasFilter.CONST_CAS_ASSERTION);
    
                                //获取在服务器端配置的map
    
                                Map<String, Object> map = assertion.getPrincipal().getAttributes();
    
                                //遍历map将其中的值放入User对象
    
                                User user = new User();
    
                                user.setId(Integer.parseInt((String)map.get("id")));
    
                                user.setUsername((String)map.get("username"));
    
                                user.setPassword((String)map.get("password"));
    
                                user.setAddress((String)map.get("address"));
    
                                event.getSession().setAttribute("user", user);
    
                       }
    
             }
    
    
    
             @Override
    
             public void attributeRemoved(HttpSessionBindingEvent event) {
    
                       // TODO Auto-generated method stub
    
    
    
             }
    
    
    
             @Override
    
             public void attributeReplaced(HttpSessionBindingEvent event) {
    
                       // TODO Auto-generated method stub
    
    
    
             }
    
    
    
    }

在客户端的web.xml文件中配置这个监听器

<listener>
    
                       <listener-class>com.cas.client.listener.MySessionListener</listener-class>
    
             </listener>

测试。

9. 单点注销

在cas的客户端，使用一个map维护所有登陆用户的session和tg凭据。cas服务器将依次将客户端发送请求，被cas客户端的注销过滤器拦截到，注销过滤器完成客户端的注销工作。实现单点注销，需要将客户端的单点注销过滤器打开。

使用单点登录服务器的地址www.server.com/logout测试注销。