cas_client之AuthenticationFilter源碼分析

packageorg.jasig.cas.client.authentication;

import java.io.IOException;

import java.io.PrintStream;

import java.util.Date;

import java.util.HashMap;

import java.util.Map;

import javax.servlet.FilterChain;

import javax.servlet.FilterConfig;

import javax.servlet.ServletException;

import javax.servlet.ServletRequest;

import javax.servlet.ServletResponse;

importjavax.servlet.http.HttpServletRequest;

importjavax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;

import org.jasig.cas.client.util.AbstractCasFilter;

importorg.jasig.cas.client.util.CommonUtils;

importorg.jasig.cas.client.util.ReflectUtils;

importorg.jasig.cas.client.validation.Assertion;

import org.slf4j.Logger;

//就是檢查是否有服務ticket，如果沒有就需要進行登錄認證。

//否則：如果服務url自身帶服務ticket參數，則過濾器直接放行，代理模式就有這么一環設計。

public class AuthenticationFilter

 extends AbstractCasFilter

{

 //sso中心認證服務的登錄地址。

 private String casServerLoginUrl;

 private boolean renew = false;

 private boolean gateway = false;

 //網關存儲解析器。

 private GatewayResolver gatewayStorage = newDefaultGatewayResolverImpl();

 //認證重定向策略，默認是直接重定向地址。

 private AuthenticationRedirectStrategy authenticationRedirectStrategy =new DefaultAuthenticationRedirectStrategy();

 //可以被忽略的url模式匹配策略。

 private UrlPatternMatcherStrategy ignoreUrlPatternMatcherStrategyClass =null;

 private static final Map<String, Class<? extendsUrlPatternMatcherStrategy>> PATTERN_MATCHER_TYPES = new HashMap();

 //默認有3種模式匹配策略：包含、正則、相等。

 static

  {

   PATTERN_MATCHER_TYPES.put("CONTAINS",ContainsPatternUrlPatternMatcherStrategy.class);

   PATTERN_MATCHER_TYPES.put("REGEX",RegexUrlPatternMatcherStrategy.class);

   PATTERN_MATCHER_TYPES.put("EXACT",ExactUrlPatternMatcherStrategy.class);

  }

 protected void initInternal(FilterConfig filterConfig)

   throws ServletException

  {

   if (!isIgnoreInitConfiguration())

    {

     super.initInternal(filterConfig);

     setCasServerLoginUrl(getPropertyFromInitParams(filterConfig,"casServerLoginUrl", null));

     this.logger.trace("Loaded CasServerLoginUrl parameter: {}",this.casServerLoginUrl);

     setRenew(parseBoolean(getPropertyFromInitParams(filterConfig,"renew", "false")));

     this.logger.trace("Loaded renew parameter: {}",Boolean.valueOf(this.renew));

     setGateway(parseBoolean(getPropertyFromInitParams(filterConfig,"gateway", "false")));

     this.logger.trace("Loaded gateway parameter: {}",Boolean.valueOf(this.gateway));

     //忽略模式：可以自定義、根據實際情況配置，默認是正則表達式。

     String ignorePattern = getPropertyFromInitParams(filterConfig,"ignorePattern", null);

     this.logger.trace("Loaded ignorePattern parameter: {}",ignorePattern);

     //默認是正則模式，可以自定義實現UrlPatternMatcherStrategy接口。

     String ignoreUrlPatternType = getPropertyFromInitParams(filterConfig,"ignoreUrlPatternType", "REGEX");

     this.logger.trace("Loaded ignoreUrlPatternType parameter: {}",ignoreUrlPatternType);

     if (ignorePattern != null)

     {

       Class<? extends UrlPatternMatcherStrategy> ignoreUrlMatcherClass =(Class)PATTERN_MATCHER_TYPES.get(ignoreUrlPatternType);

       if (ignoreUrlMatcherClass != null) {

         this.ignoreUrlPatternMatcherStrategyClass = ((UrlPatternMatcherStrategy)ReflectUtils.newInstance(ignoreUrlMatcherClass.getName(),new Object[0]));

       } else {

         try

         {

           this.logger.trace("Assuming {} is a qualified class name...",ignoreUrlPatternType);

           this.ignoreUrlPatternMatcherStrategyClass =((UrlPatternMatcherStrategy)ReflectUtils.newInstance(ignoreUrlPatternType, newObject[0]));

         }

         catch (IllegalArgumentException e)

         {

           this.logger.error("Could not instantiate class [{}]",ignoreUrlPatternType, e);

         }

       }

       if (this.ignoreUrlPatternMatcherStrategyClass != null) {

         this.ignoreUrlPatternMatcherStrategyClass.setPattern(ignorePattern);

       }

     }

     String gatewayStorageClass = getPropertyFromInitParams(filterConfig,"gatewayStorageClass", null);

     if (gatewayStorageClass != null) {

       this.gatewayStorage =((GatewayResolver)ReflectUtils.newInstance(gatewayStorageClass, newObject[0]));

     }

     String authenticationRedirectStrategyClass =getPropertyFromInitParams(filterConfig,"authenticationRedirectStrategyClass", null);

     if (authenticationRedirectStrategyClass != null) {

       this.authenticationRedirectStrategy =((AuthenticationRedirectStrategy)ReflectUtils.newInstance(authenticationRedirectStrategyClass,new Object[0]));

     }

    }

  }

 public void init()

  {

   super.init();

   CommonUtils.assertNotNull(this.casServerLoginUrl,"casServerLoginUrl cannot be null.");

  }

 public final void doFilter(ServletRequest servletRequest,ServletResponse servletResponse, FilterChain filterChain)

   throws IOException, ServletException

  {

   HttpServletRequest request = (HttpServletRequest)servletRequest;

   HttpServletResponse response = (HttpServletResponse)servletResponse;

   //判斷當前請求url是否可以被忽略模式匹配認證通過。

   if (isRequestUrlExcluded(request))

    {

     this.logger.debug("Request is ignored.");

     filterChain.doFilter(request, response);

     return;

    }

   //獲取sso認證中心存儲的session屬性_const_cas_assertion_。

   HttpSession session = request.getSession(false);

   Assertion assertion = session != null ?(Assertion)session.getAttribute("_const_cas_assertion_") : null;

   if (assertion != null)

    {

     filterChain.doFilter(request, response);

     return;

    }

   //從request中構建需要認證的服務url。

   String serviceUrl = constructServiceUrl(request, response);

   //從request中獲取票據ticket。

   String ticket = retrieveTicketFromRequest(request);

   //如果設置網關，則從session當中獲取屬性_const_cas_gateway，并從session中去掉此屬性。

   boolean wasGatewayed = (this.gateway) &&(this.gatewayStorage.hasGatewayedAlready(request, serviceUrl));

   //如果存在認證票據ticket或者網關設置，則直接認證通過。

   if ((CommonUtils.isNotBlank(ticket)) || (wasGatewayed))

    {

     filterChain.doFilter(request, response);

     return;

    }

   this.logger.debug("no ticket and no assertion found");

   String modifiedServiceUrl;

   if (this.gateway)

    {

     this.logger.debug("setting gateway attribute in session");

    //在session中設置網關屬性_const_cas_gateway=yes

     modifiedServiceUrl = this.gatewayStorage.storeGatewayInformation(request,serviceUrl);

    }

   else

    {

     modifiedServiceUrl = serviceUrl;

    }

   this.logger.debug("Constructed service url: {}",modifiedServiceUrl);

   //直接重定向sso認證中心url,進行登錄認證。

   String urlToRedirectTo = CommonUtils.constructRedirectUrl(this.casServerLoginUrl,getServiceParameterName(), modifiedServiceUrl, this.renew, this.gateway);

   this.logger.debug("redirecting to \"{}\"",urlToRedirectTo);

   this.authenticationRedirectStrategy.redirect(request, response,urlToRedirectTo);

  }

 public final void setRenew(boolean renew)

  {

   this.renew = renew;

  }

 public final void setGateway(boolean gateway)

  {

   this.gateway = gateway;

  }

 public final void setCasServerLoginUrl(String casServerLoginUrl)

  {

   this.casServerLoginUrl = casServerLoginUrl;

  }

 public final void setGatewayStorage(GatewayResolver gatewayStorage)

  {

   this.gatewayStorage = gatewayStorage;

  }

  //根據可以忽略的URL地址匹配策略，來判斷當前請求url是否可以認證：因此在配置此過濾器的時候，如果存在不需要認證的url，那么就可以根據url的形式配置ignorePattern參數和ignoreUrlPatternType參數。

 private boolean isRequestUrlExcluded(HttpServletRequest request)

  {

   if (this.ignoreUrlPatternMatcherStrategyClass == null) {

     return false;

    }

   StringBuffer urlBuffer = request.getRequestURL();

   if (request.getQueryString() != null) {

     urlBuffer.append("?").append(request.getQueryString());

    }

   String requestUri = urlBuffer.toString();

   return this.ignoreUrlPatternMatcherStrategyClass.matches(requestUri);

  }

}