CAS单点登录（一）：服务端搭建

 

1.下载

先在网上下载cas-server-3.5.2,将里面的cas-server-webapp-3.5.2.war放到tomcat的webapps目录下。

2.https设置

cas单点登默认使用的是https，所以需要证书，由于是个人测试和学习用的，可以用JDK自带的keytool工具生成证书。

2.1用JDK生成证书：

 

keytool -genkey -keystore "E:cas-xutingcas-xuting.keystore" -alias "CASCHENJIE" -keyalg "RSA" -validity 36500 -dname "CN=localhost,OU=org.cj,L=cd,ST=sc,C=c" -keypass "xuting" -storepass "
xuting"

 2.2颁发证书

keytool -alias "CASCHENJIE" -exportcert -keystore "E:cas-xutingcas-xuting.keystore" -file "E:cas-xutingCASCHENJIE.cer" -storepass "xuting"

2.3安装证书

双击CASCHEBJIE.cer安装证书
或将证书存储到受信任的根证书颁发机构。
或者为客户端的JVM导入证书：

2.4配置tomcat服务器

<Connector port="8443" protocol="org.apache.coyote.http11.Http11Protocol"
               maxThreads="150" SSLEnabled="true" scheme="https" secure="true"
               clientAuth="false" sslProtocol="TLS"
                keystoreFile="E:/cas-xuting/cas-xuting.keystore" keystorePass="xuting"/>

3.启动tomcat测试

 当秘密和用户名相同时登录成功

这样一个简单的CAS的单点登录的服务端就搭建成功。

4.CAS服务端的源码解析

更具点单登录流程走，流程配置在/WEB-INF/login-webflow.xml文件中。

 4.1设置一个变量credentials来存放用户名和密码信息

<var name="credentials" class="org.jasig.cas.authentication.principal.UsernamePasswordCredentials" />

 4.2流程初始化从on-start标签开始

<on-start>  
    <evaluate expression="initialFlowSetupAction" />  
</on-start> 
4.2.1 initialFlowSetupAction的配置在/WEB-INF/cas-servlet.xml中
<bean id="initialFlowSetupAction" class="org.jasig.cas.web.flow.InitialFlowSetupAction"  
        p:argumentExtractors-ref="argumentExtractors"  
        p:warnCookieGenerator-ref="warnCookieGenerator"  
        p:ticketGrantingTicketCookieGenerator-ref="ticketGrantingTicketCookieGenerator"/>  
4.2.1.1argumentExtractors的配置又在/WEB-INF/spring-configuration/argumentExtractorsConfiguration.xml中。
<bean  
    id="casArgumentExtractor"  
    class="org.jasig.cas.web.support.CasArgumentExtractor"  
    p:httpClient-ref="noRedirectHttpClient"  
    p:disableSingleSignOut="${slo.callbacks.disabled:false}" /> 
  
<bean id="samlArgumentExtractor" class="org.jasig.cas.web.support.SamlArgumentExtractor"  
    p:httpClient-ref="noRedirectHttpClient"  
    p:disableSingleSignOut="${slo.callbacks.disabled:false}" />  
      
<util:list id="argumentExtractors">  
    <ref bean="casArgumentExtractor" />  
    <ref bean="samlArgumentExtractor" />  
</util:list>

4.2.1.2其中warnCookieGenerator配置文件在/WEB-INF/spring-configuration/warnCookieGenerator.xml中。

<bean id="warnCookieGenerator" class="org.jasig.cas.web.support.CookieRetrievingCookieGenerator"  
    p:cookieSecure="true"  
    p:cookieMaxAge="-1"  
    p:cookieName="CASPRIVACY"  
    p:cookiePath="/cas" />

4.2.1.3其中ticketGrantingTicketCookieGenerator配置文件在/WEB-INF/spring-configuration/ticketGrantingTicketCookieGenerator.xml中。

<bean id="ticketGrantingTicketCookieGenerator" class="org.jasig.cas.web.support.CookieRetrievingCookieGenerator"  
    p:cookieSecure="false"  
    p:cookieMaxAge="-1"  
    p:cookieName="CASTGC"  
    p:cookiePath="/cas" />  
4.2.2初始化部分会调用InitialFlowSetupAction的doExecute方法，如果有特殊需求，可以在此方法中增加相应的逻辑。如果希望单点登录集成统一身份认证，那么可以在此处增加统一身份认证的逻辑。
InitialFlowSetupAction的doExecute方法：
protected Event doExecute(final RequestContext context) throws Exception {  
    final HttpServletRequest request = WebUtils.getHttpServletRequest(context);  
    if (!this.pathPopulated) {  
        final String contextPath = context.getExternalContext().getContextPath();  
        final String cookiePath = StringUtils.hasText(contextPath) ? contextPath + "/" : "/";  
        logger.info("Setting path for cookies to: " + cookiePath);  
        this.warnCookieGenerator.setCookiePath(cookiePath);  
        this.ticketGrantingTicketCookieGenerator.setCookiePath(cookiePath);  
        this.pathPopulated = true;  
    }  
    //将TGT放在FlowScope作用域中  
    context.getFlowScope().put(  
        "ticketGrantingTicketId", this.ticketGrantingTicketCookieGenerator.retrieveCookieValue(request));  
    //将warnCookieValue放在FlowScope作用域中  
    context.getFlowScope().put(  
        "warnCookieValue", Boolean.valueOf(this.warnCookieGenerator.retrieveCookieValue(request)));  
    //获取service参数  
    final Service service = WebUtils.getService(this.argumentExtractors, context);  
  
    if (service != null && logger.isDebugEnabled()) {  
        logger.debug("Placing service in FlowScope: " + service.getId());  
    }  
    //将service放在FlowScope作用域中  
    context.getFlowScope().put("service", service);  
  
    return result("success");  
}

4.3InitialFlowSetupAction的doExecute要做的就是把ticketGrantingTicketId，warnCookieValue和service放到FlowScope的作用域中，以便在登录流程中的state中进行判断。初始化完成后，登录流程流转到第一个state（ticketGrantingTicketExistsCheck）。

<decision-state id="ticketGrantingTicketExistsCheck">  
    <if test="flowScope.ticketGrantingTicketId != null" then="hasServiceCheck" else="gatewayRequestCheck" />  
</decision-state>

4.4当我们第一次访问集成了CAS单点登录的应用系统（假设为：webapp1）时（http://127.0.0.1:8090/webapp1/main.do），此时应用系统会跳转到CAS单点登录的服务器端（http://127.0.0.1:8081/cas-server/login?service=http://127.0.0.1:8090/webapp1/main.do）。此时，request的cookies中不存在CASTGC（TGT），因此FlowScope作用域中的ticketGrantingTicketId为null，登录流程流转到第二个state（gatewayRequestCheck）。

<decision-state id="gatewayRequestCheck">  
    <if test="requestParameters.gateway != '' and requestParameters.gateway != null and flowScope.service != null"   
        then="gatewayServicesManagementCheck" else="serviceAuthorizationCheck" />  
</decision-state> 


4.5因为初始化时，尽管把service保存在了FlowScope作用域中，但request中的参数gateway不存在，登录流程流转到第三个state（serviceAuthorizationCheck）。




<action-state id="serviceAuthorizationCheck">  
    <evaluate expression="serviceAuthorizationCheck"/>  
    <transition to="generateLoginTicket"/>  
</action-state>  





4.5.1ServiceAuthorizationCheck的doExecute方法




protected Event doExecute(final RequestContext context) throws Exception {  
    final Service service = WebUtils.getService(context);  
    //No service == plain /login request. Return success indicating transition to the login form  
    if(service == null) {  
        return success();  
    }  
    final RegisteredService registeredService = this.servicesManager.findServiceBy(service);  
  
    if (registeredService == null) {  
        logger.warn("Unauthorized Service Access for Service: [ {} ] - service is not defined in the service registry.", service.getId());  
        throw new UnauthorizedServiceException();  
    }  
    else if (!registeredService.isEnabled()) {  
        logger.warn("Unauthorized Service Access for Service: [ {} ] - service is not enabled in the service registry.", service.getId());  
        throw new UnauthorizedServiceException();  
    }  
  
    return success();  
}  





4.6ServiceAuthorizationCheck的doExecute方法，要做的就是判断FlowScope作用域中是否存在service，如果service存在，查找service的注册信息。登录流程流转到第四个state（generateLoginTicket）。




<action-state id="generateLoginTicket">  
    <evaluate expression="generateLoginTicketAction.generate(flowRequestContext)" />  
    <transition on="generated" to="viewLoginForm" />  
</action-state>  





4.6.1generateLoginTicketAction配置在/WEB-INF/cas-servlet.xml中。




<bean id="generateLoginTicketAction" class="org.jasig.cas.web.flow.GenerateLoginTicketAction"  
    p:ticketIdGenerator-ref="loginTicketUniqueIdGenerator" />  





4.6.1.1其中loginTicketUniqueIdGenerator又在/WEB-INF/spring-configuration/uniqueIdGenerators.xml中




<bean id="loginTicketUniqueIdGenerator" class="org.jasig.cas.util.DefaultUniqueTicketIdGenerator">  
    <constructor-arg  
        index="0"  
        type="int"  
        value="30" />  
</bean>  





4.6.1.2DefaultUniqueTicketIdGenerator要做的就是生成以LT作为前缀的loginTicket（例：LT-2-pfDmbEHfX2OkS0swLtDd7iDwmzlhsn）。注：LT只作为登录时使用的票据。


GenerateLoginTicketAction的generate方法




public final String generate(final RequestContext context) {  
    //LT-2-pfDmbEHfX2OkS0swLtDd7iDwmzlhsn  
    final String loginTicket = this.ticketIdGenerator.getNewTicketId(PREFIX);//生成loginTicket  
    this.logger.debug("Generated login ticket " + loginTicket);  
    WebUtils.putLoginTicket(context, loginTicket);//放到flowScope中  
    return "generated";  
} 





4.7GenerateLoginTicketAction的generate要做的就是生成loginTicket，并且把loginTicket放到FlowScope作用域中。登录流程流转到第五个state（viewLoginForm）。





<view-state id="viewLoginForm" view="casLoginView" model="credentials">  
    <binder>  
        <binding property="username" />  
        <binding property="password" />  
    </binder>  
    <on-entry>  
        <set name="viewScope.commandName" value="'credentials'" />  
    </on-entry>  
          
    <transition on="submit" bind="true" validate="true" to="realSubmit">  
        <evaluate expression="authenticationViaFormAction.doBind(flowRequestContext, flowScope.credentials)" />  
    </transition>  
</view-state>  




至此，经过五个state的流转，我们完成了第一次访问集成了单点登录的应用系统，此时流转到CAS单点登录服务器端的登录页面/WEB-INF/jsp/ui/default/casLoginView.jsp。由于casLoginView.jsp是CAS提供的默认登录页面，需要把此页面修改成我们系统需要的登录页面，格式需要参考casLoginView.jsp。


注意，默认的登录页面中有lt、execution和_eventId三个隐藏参数，lt参数值就是在GenerateLoginTicketAction的generate方法中生成的loginTicket。




<input type="hidden" name="lt" value="${loginTicket}" />  
<input type="hidden" name="execution" value="${flowExecutionKey}" />  
<input type="hidden" name="_eventId" value="submit" /> 




5CAS单点登录服务器端的登录验证
5.1当输入用户名和密码，点击登录按钮时，会执行AuthenticationViaFormAction的doBind方法。（上文4.7中authenticationViaFormAction可以知道）


它的的配置在/WEB-INF/cas-servlet.xml中




 <bean id="authenticationViaFormAction" class="org.jasig.cas.web.flow.AuthenticationViaFormAction"
        p:centralAuthenticationService-ref="centralAuthenticationService"
        p:warnCookieGenerator-ref="warnCookieGenerator"/>





 AuthenticationViaFormAction的doBind方法




public final void doBind(final RequestContext context, final Credentials credentials) throws Exception {  
    final HttpServletRequest request = WebUtils.getHttpServletRequest(context);  
    //bean中没有注入，这里什么也不做  
    if (this.credentialsBinder != null && this.credentialsBinder.supports(credentials.getClass())) {  
        this.credentialsBinder.bind(request, credentials);  
    }  
}  






5.1.1登录流程流转到第一个state（realSubmit），会执行AuthenticationViaFormAction的submit方法 




<action-state id="realSubmit">  
    <evaluate expression="authenticationViaFormAction.submit(flowRequestContext, flowScope.credentials, messageContext)" />  
    <transition on="warn" to="warn" /><!-- 警告,转向其他站点前提示我 -->  
    <transition on="success" to="sendTicketGrantingTicket" /><!-- 成功 -->  
    <transition on="error" to="generateLoginTicket" /><!-- 错误 -->  
    <transition on="accountDisabled" to="casAccountDisabledView" />  
    <transition on="mustChangePassword" to="casMustChangePassView" />  
    <transition on="accountLocked" to="casAccountLockedView" />  
    <transition on="badHours" to="casBadHoursView" />  
    <transition on="badWorkstation" to="casBadWorkstationView" />  
    <transition on="passwordExpired" to="casExpiredPassView" />  
</action-state>  





其中AuthenticationViaFormAction的submit方法




public final String submit(final RequestContext context, final Credentials credentials, final MessageContext messageContext)   
    throws Exception {  
    // Validate login ticket  
    final String authoritativeLoginTicket = WebUtils.getLoginTicketFromFlowScope(context);  
    final String providedLoginTicket = WebUtils.getLoginTicketFromRequest(context);  
    //判断FlowScope和request中的loginTicket是否相同  
    if (!authoritativeLoginTicket.equals(providedLoginTicket)) {  
        this.logger.warn("Invalid login ticket " + providedLoginTicket);  
        final String code = "INVALID_TICKET";  
        messageContext.addMessage(new MessageBuilder().error().code(code).arg(providedLoginTicket).defaultText(code).build());  
        return "error";  
    }  
    //requestScope和FlowScope中获取TGT  
    final String ticketGrantingTicketId = WebUtils.getTicketGrantingTicketId(context);  
    //FlowScope中获取service  
    final Service service = WebUtils.getService(context);  
    if (StringUtils.hasText(context.getRequestParameters().get("renew"))   
            && ticketGrantingTicketId != null && service != null) {  
  
        try {  
            final String serviceTicketId = this.centralAuthenticationService.grantServiceTicket(  
                ticketGrantingTicketId, service, credentials);  
            WebUtils.putServiceTicketInRequestScope(context, serviceTicketId);  
            putWarnCookieIfRequestParameterPresent(context);  
            return "warn";  
        } catch (final TicketException e) {  
            if (isCauseAuthenticationException(e)) {  
                populateErrorsInstance(e, messageContext);  
                return getAuthenticationExceptionEventId(e);  
            }  
                  
            this.centralAuthenticationService.destroyTicketGrantingTicket(ticketGrantingTicketId);  
            if (logger.isDebugEnabled()) {  
                logger.debug("Attempted to generate a ServiceTicket using renew=true with different credentials", e);  
            }  
        }  
    }  
  
    try {  
        //根据用户凭证构造TGT，把TGT放到requestScope中，同时把TGT缓存到服务器的cache<ticketId,TGT>中  
        WebUtils.putTicketGrantingTicketInRequestScope(context,   
            this.centralAuthenticationService.createTicketGrantingTicket(credentials));  
        putWarnCookieIfRequestParameterPresent(context);  
        return "success";  
    } catch (final TicketException e) {  
        populateErrorsInstance(e, messageContext);  
        if (isCauseAuthenticationException(e))  
            return getAuthenticationExceptionEventId(e);  
        return "error";  
    }  
}  





5.2AuthenticationViaFormAction的submit要做的就是判断FlowScope和request中的loginTicket是否相同。如果不同跳转到错误页面，如果相同，则根据用户凭证生成TGT（登录成功票据），并放到requestScope作用域中，同时把TGT缓存到服务器的cache<ticketId,TGT>中。登录流程流转到第二个state（sendTicketGrantingTicket）。


既然是登录，那么可以在此方法中加入自己的业务逻辑，比如，可以加入验证码的判断，以及错误信息的提示，用户名或者密码错误，验证码错误等逻辑判断。




<action-state id="sendTicketGrantingTicket">  
    <evaluate expression="sendTicketGrantingTicketAction" />  
    <transition to="serviceCheck" />  
</action-state>  





5.2.1SendTicketGrantingTicketAction的doExecute方法




protected Event doExecute(final RequestContext context) {  
    //requestScope和FlowScope中获取TGT  
    final String ticketGrantingTicketId = WebUtils.getTicketGrantingTicketId(context);   
    final String ticketGrantingTicketValueFromCookie = (String) context.getFlowScope().get("ticketGrantingTicketId");  
          
    if (ticketGrantingTicketId == null) {  
        return success();  
    }  
    //response中添加TGC  
    this.ticketGrantingTicketCookieGenerator.addCookie(WebUtils.getHttpServletRequest(context), WebUtils  
        .getHttpServletResponse(context), ticketGrantingTicketId);  
  
    if (ticketGrantingTicketValueFromCookie != null && !ticketGrantingTicketId.equals(ticketGrantingTicketValueFromCookie)) {  
        this.centralAuthenticationService  
            .destroyTicketGrantingTicket(ticketGrantingTicketValueFromCookie);  
    }  
  
    return success();  
}  





5.3SendTicketGrantingTicketAction的doExecute要做的是获取TGT，并根据TGT生成cookie添加到response。登录流程流转到第三个state（serviceCheck）。




<decision-state id="serviceCheck">  
    <if test="flowScope.service != null" then="generateServiceTicket" else="viewGenericLoginSuccess" />  
</decision-state>  




5.4由于此时FlowScope中存在service（http://127.0.0.1:8081/cas-server/login?service=http://127.0.0.1:8090/webapp1/main.do），登录流程流转到第四个state（generateServiceTicket）。




<action-state id="generateServiceTicket">  
    <evaluate expression="generateServiceTicketAction" />  
    <transition on="success" to ="warn" />  
    <transition on="error" to="generateLoginTicket" />  
    <transition on="gateway" to="gatewayServicesManagementCheck" />  
</action-state>  





5.4.1其中GenerateServiceTicketAction的doExecute方法




protected Event doExecute(final RequestContext context) {  
    //获取service  
    final Service service = WebUtils.getService(context);  
    //获取TGT  
    final String ticketGrantingTicket = WebUtils.getTicketGrantingTicketId(context);  
  
    try {  
        //根据TGT和service生成service ticket(ST-2-97kwhcdrBW97ynpBbZH5-cas01.example.org)  
        final String serviceTicketId = this.centralAuthenticationService.grantServiceTicket(ticketGrantingTicket,  
            service);  
        //ST放到requestScope中  
        WebUtils.putServiceTicketInRequestScope(context, serviceTicketId);  
        return success();  
    } catch (final TicketException e) {  
        if (isGatewayPresent(context)) {  
            return result("gateway");  
        }  
    }  
  
    return error();  
}  





5.5GenerateServiceTicketAction的doExecute要做的是获取service和TGT，并根据service和TGT生成以ST为前缀的serviceTicket（例：ST-2-97kwhcdrBW97ynpBbZH5-cas01.example.org），并把serviceTicket放到requestScope中。登录流程流转到第五个state（warn）。




<decision-state id="warn">  
    <if test="flowScope.warnCookieValue" then="showWarningView" else="redirect" />  
</decision-state>  





5.6由于此时FlowScope中不存在warnCookieValue，登录流程流转到第六个state（redirect）。




<action-state id="redirect">  
    <evaluate expression="flowScope.service.getResponse(requestScope.serviceTicketId)"   
        result-type="org.jasig.cas.authentication.principal.Response" result="requestScope.response" />  
    <transition to="postRedirectDecision" />  
</action-state>  




5.7从requestScope中获取serviceTicket，构造response对象，并把response放到requestScope中。登录流程流转到第七个state（postRedirectDecision）。




<decision-state id="postRedirectDecision">  
    <if test="requestScope.response.responseType.name() == 'POST'" then="postView" else="redirectView" />  
</decision-state>  





5.8由于request请求（http://127.0.0.1:8081/cas-server/login?service=http://127.0.0.1:8090/webapp1/main.do）是get类型，登录流程流转到第八个state（redirectView）




<end-state id="redirectView" view="externalRedirect:${requestScope.response.url}" />  




此时流程如下：


    

  1. 跳转到应用系统（http://127.0.0.1:8090/webapp1/main.do?ticket=ST-1-4hH2s5tzsMGCcToDvGCb-cas01.example.org）。
    2. 

  2. 进入CAS客户端的AuthenticationFilter过滤器，由于session中获取名为“_const_cas_assertion_”的assertion对象不存在，但是request有ticket参数，所以进入到下一个过滤器。
    3. 

  3. TicketValidationFilter过滤器的validate方法通过httpClient访问CAS服务器端（http://127.0.0.1:8081/cas-server/serviceValidate?ticket=ST-1-4hH2s5tzsMGCcToDvGCb-cas01.example.org&service=http://127.0.0.1:8090/webapp1/main.do）验证ticket是否正确，并返回assertion对象。
    4. 



5.9Assertion对象格式类似于




<cas:serviceResponse xmlns:cas='http://www.yale.edu/tp/cas'>  
    <cas:authenticationSuccess>  
        <cas:user>system</cas:user>  
  
    </cas:authenticationSuccess>  
</cas:serviceResponse> 
















        

	      

	    

	  

	  

	    
      
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          原文地址：https://www.cnblogs.com/ttmemory/p/7908109.html