spring security filter

一、spring security过滤器默认配置

WebSecurityConfigurerAdapter.init()
WebSecurityConfigurerAdapter.getHttp()
new HttpSecurity()
new FilterComparator()
按优先级顺序放入，前面的优先级比后面的高，关键的filter
Step order = new Step(INITIAL_ORDER, ORDER_STEP);
put(ChannelProcessingFilter.class, order.next());
put(ConcurrentSessionFilter.class, order.next());
put(WebAsyncManagerIntegrationFilter.class, order.next());
put(SecurityContextPersistenceFilter.class, order.next());
put(HeaderWriterFilter.class, order.next());
put(CorsFilter.class, order.next());
put(CsrfFilter.class, order.next());
put(LogoutFilter.class, order.next());
filterToOrder.put(   "org.springframework.security.oauth2.client.web.OAuth2AuthorizationRequestRedirectFilter", order.next());
put(X509AuthenticationFilter.class, order.next());
put(AbstractPreAuthenticatedProcessingFilter.class, order.next());
filterToOrder.put("org.springframework.security.cas.web.CasAuthenticationFilter",
        order.next());
filterToOrder.put("org.springframework.security.oauth2.client.web.OAuth2LoginAuthenticationFilter",
        order.next());
put(UsernamePasswordAuthenticationFilter.class, order.next());
put(ConcurrentSessionFilter.class, order.next());
filterToOrder.put(
        "org.springframework.security.openid.OpenIDAuthenticationFilter", order.next());
put(DefaultLoginPageGeneratingFilter.class, order.next());
put(DefaultLogoutPageGeneratingFilter.class, order.next());
put(ConcurrentSessionFilter.class, order.next());
put(DigestAuthenticationFilter.class, order.next());
filterToOrder.put(
        "org.springframework.security.oauth2.server.resource.web.BearerTokenAuthenticationFilter", order.next());
put(BasicAuthenticationFilter.class, order.next());
put(RequestCacheAwareFilter.class, order.next());
put(SecurityContextHolderAwareRequestFilter.class, order.next());
put(JaasApiIntegrationFilter.class, order.next());
put(RememberMeAuthenticationFilter.class, order.next());
put(AnonymousAuthenticationFilter.class, order.next());
filterToOrder.put(
    "org.springframework.security.oauth2.client.web.OAuth2AuthorizationCodeGrantFilter",
        order.next());
put(SessionManagementFilter.class, order.next());
put(ExceptionTranslationFilter.class, order.next());
put(FilterSecurityInterceptor.class, order.next());
put(SwitchUserFilter.class, order.next());

二、springsecurity过滤器链springSecurityFilterChain通过代理创建（懒加载）

1、oauth2认证中心

查看容器中的关于springsecurity需要的filter（springSecurityFilterChain），需要跟踪tomcat支持包下的ApplicationFilterFactory类，查看返回的过滤器链对象filterChain,ApplicationFilterFactory.createFilterChain(ServletRequest request,Wrapper wrapper, Servlet servlet)，也可以查看DelegatingFilterProxy.initDelegate(WebApplicationContext wac)，这个方法是在执行DelegatingFilterProxy的doFilter方法时才会执行，达到懒加载delegate的目的。

适配后的过滤器链

token相关（/oauth/token,/oauth/token_key,/oauth/check_token）的springSecurityFilterChain过滤器链（按优先级顺序）
WebAsyncManagerIntegrationFilter
SecurityContextPersistenceFilter
HeaderWriterFilter
LogoutFilter
ClientCredentialsTokenEndpointFilter
BasicAuthenticationFilter
RequestCacheAwareFilter
SecurityContextHolderAwareRequestFilter
AnonymousAuthenticationFilter
SessionManagementFilter
ExceptionTranslationFilter
FilterSecurityInterceptor

anyRequest相关springSecurityFilterChain的过滤器链
WebAsyncManagerIntegrationFilter
SecurityContextPersistenceFilter
HeaderWriterFilter
CorsFilter
LogoutFilter
UsernamePasswordAuthenticationFilter
RequestCacheAwareFilter
SecurityContextHolderAwareRequestFilter
AnonymousAuthenticationFilter
SessionManagementFilter
ExceptionTranslationFilter
FilterSecurityInterceptor

2、oauth2的SSO客户端（@EnableOAuth2Sso）过滤器如下：

客户端注解@EnableOAuth2Client引入的过滤器
OAuth2ClientContextFilter

客户端的springSecurityFilterChain过滤器链

WebAsyncManagerIntegrationFilter
SecurityContextPersistenceFilter
HeaderWriterFilter
LogoutFilter
OAuth2ClientAuthenticationProcessingFilter
RequestCacheAwareFilter
SecurityContextHolderAwareRequestFilter
AnonymousAuthenticationFilter
SessionManagementFilter
ExceptionTranslationFilter
FilterSecurityInterceptor

三、springsecurity过滤器链所处容器中过滤器链的位置如下图所示

在这里插入图片描述

四、请求与过滤器链

1、springSecurityFilterChain

初始化过滤器：启动tomcat容器时，ServletContextInitializerBeans.addAdaptableBeans会从beanFactory将实现javax.servlet.Filter接口相关的bean（含springSecurityFilterChain类型为DelegatingFilterProxyRegistrationBean）加载到initializers
再执行ServletContextInitializerBeans.onStartup(ServletContext servletContext)将执行springSecurityFilterChain.getFilter()获取到DelegatingFilterProxy的实例并添加到容器ServletContext（即ApplicationContext，真正存入StandardContext，filter以FilterDef类型存储）中。

2、处理请求

1）调用tomcat的类StandardWrapperValve的invoke方法，获取整体的过滤器链ApplicationFilterChain并执行。

获取整体的过滤器链ApplicationFilterFactory.createFilterChain从StandardContext中获取适合的过滤器配置（ApplicationFilterConfig）添加到过滤器链中。

public final void invoke(Request request, Response response)
throws IOException, ServletException {
....
// Create the filter chain for this request
ApplicationFilterChain filterChain =
ApplicationFilterFactory.createFilterChain(request, wrapper, servlet);

// Call the filter chain for this request
// NOTE: This also calls the servlet's service() method
Container container = this.container;
try {
....
filterChain.doFilter(request.getRequest(),
response.getResponse());
....
} catch (Exception e) {
.....
} finally {
// Release the filter chain (if any) for this request
if (filterChain != null) {
filterChain.release();
}
....
}

ApplicationFilterChain过滤器链执行方法doFilter，内部执行internalDoFilter方法

private void internalDoFilter(ServletRequest request,
ServletResponse response)
throws IOException, ServletException {
   // Call the next filter if there is one
   if (pos < n) {
       ApplicationFilterConfig filterConfig = filters[pos++];//获取过滤器链中下一个过滤器配置
       try {
           Filter filter = filterConfig.getFilter();//从配置中得到过滤器
           .....
           filter.doFilter(request, response, this);//过滤器执行时，需要将当前的过滤器链作为参数传入，以便在过滤器内部执行过滤器链的doFilter方法，调用下一个过滤器，实现过滤器的链式调用

       }
   }
   ....
}

2）执行springsecurity的过滤器链springSecurityFilterChain

当执行到springSecurityFilterChain，再执行DelegatingFilterProxy.doFilter、initDelegate完成对FilterChainProxy（delegate真正的springSecurity过滤器链）的实例的创建，再执行DelegatingFilterProxy.invokeDelegate方法，调用FilterChainProxy.doFilter执行doFilterInternal方法创建VirtualFilterChain（这个就是springsecurity真正的过滤器链，包含原始的过滤器链ApplicationFilterChain和springsecurity的过滤器列表）并执行它的doFilter来开始执行springsecurity的过滤器链，内部先执行springsecurity的过滤器链，最后再回到原始的过滤器链originalChain（ApplicationFilterChain），继续执行后续的过滤器。

   public void doFilter(ServletRequest request, ServletResponse response)
           throws IOException, ServletException {
       if (currentPosition == size) {
           if (logger.isDebugEnabled()) {
               logger.debug(UrlUtils.buildRequestUrl(firewalledRequest)
                       + " reached end of additional filter chain; proceeding with original chain");
           }

// Deactivate path stripping as we exit the security filter chain
this.firewalledRequest.reset();

           originalChain.doFilter(request, response);
       }
       else {
           currentPosition++;

Filter nextFilter = additionalFilters.get(currentPosition - 1);

           if (logger.isDebugEnabled()) {
               logger.debug(UrlUtils.buildRequestUrl(firewalledRequest)
                       + " at position " + currentPosition + " of " + size
                       + " in additional filter chain; firing Filter: '"
                       + nextFilter.getClass().getSimpleName() + "'");
           }

           nextFilter.doFilter(request, response, this);
       }
   }

3）过滤器链执行流程

spring security filter

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