一文搞懂Spring Security异常处理机制
今天来和小伙伴们聊一聊 Spring Security 中的异常处理机制。
在 Spring Security 的过滤器链中,ExceptionTranslationFilter 过滤器专门用来处理异常,在 ExceptionTranslationFilter 中,我们可以看到,异常被分为了两大类:认证异常和授权异常,两种异常分别由不同的回调函数来处理,今天就来和大家分享一下这里的条条框框。
1.异常分类
Spring Security 中的异常可以分为两大类,一种是认证异常,一种是授权异常。
认证异常就是 AuthenticationException,它有众多的实现类:
可以看到,这里的异常实现类还是蛮多的,都是都是认证相关的异常,也就是登录失败的异常。这些异常,有的松哥在之前的文章中都和大家介绍过了,例如下面这段代码
resp.setContentType("application/json;charset=utf-8"); PrintWriter out = resp.getWriter(); RespBean respBean = RespBean.error(e.getMessage()); if (e instanceof LockedException) { respBean.setMsg("账户被锁定,请联系管理员!"); } else if (e instanceof CredentialsExpiredException) { respBean.setMsg("密码过期,请联系管理员!"); } else if (e instanceof AccountExpiredException) { respBean.setMsg("账户过期,请联系管理员!"); } else if (e instanceof DisabledException) { respBean.setMsg("账户被禁用,请联系管理员!"); } else if (e instanceof BadCredentialsException) { respBean.setMsg("用户名或者密码输入错误,请重新输入!"); } out.write(new ObjectMapper().writeValueAsString(respBean)); out.flush(); out.close();
另一类就是授权异常 AccessDeniedException,授权异常的实现类比较少,因为授权失败的可能原因比较少。
2.ExceptionTranslationFilter
ExceptionTranslationFilter 是 Spring Security 中专门负责处理异常的过滤器,默认情况下,这个过滤器已经被自动加载到过滤器链中。
有的小伙伴可能不清楚是怎么被加载的,我这里和大家稍微说一下。
当我们使用 Spring Security 的时候,如果需要自定义实现逻辑,都是继承自 WebSecurityConfigurerAdapter 进行扩展,WebSecurityConfigurerAdapter 中本身就进行了一部分的初始化操作,我们来看下它里边 HttpSecurity 的初始化过程:
protected final HttpSecurity getHttp() throws Exception { if (http != null) { return http; } AuthenticationEventPublisher eventPublisher = getAuthenticationEventPublisher(); localConfigureAuthenticationBldr.authenticationEventPublisher(eventPublisher); AuthenticationManager authenticationManager = authenticationManager(); authenticationBuilder.parentAuthenticationManager(authenticationManager); Map<Class<?>, Object> sharedObjects = createSharedObjects(); http = new HttpSecurity(objectPostProcessor, authenticationBuilder, sharedObjects); if (!disableDefaults) { http .csrf().and() .addFilter(new WebAsyncManagerIntegrationFilter()) .exceptionHandling().and() .headers().and() .sessionManagement().and() .securityContext().and() .requestCache().and() .anonymous().and() .servletApi().and() .apply(new DefaultLoginPageConfigurer<>()).and() .logout(); ClassLoader classLoader = this.context.getClassLoader(); List<AbstractHttpConfigurer> defaultHttpConfigurers = SpringFactoriesLoader.loadFactories(AbstractHttpConfigurer.class, classLoader); for (AbstractHttpConfigurer configurer : defaultHttpConfigurers) { http.apply(configurer); } } configure(http); return http; }
可以看到,在 getHttp 方法的最后,调用了 configure(http);
,我们在使用 Spring Security 时,自定义配置类继承自 WebSecurityConfigurerAdapter 并重写的 configure(HttpSecurity http) 方法就是在这里调用的,换句话说,当我们去配置 HttpSecurity 时,其实它已经完成了一波初始化了。
在默认的 HttpSecurity 初始化的过程中,调用了 exceptionHandling 方法,这个方法会将 ExceptionHandlingConfigurer 配置进来,最终调用 ExceptionHandlingConfigurer#configure 方法将 ExceptionTranslationFilter 添加到 Spring Security 过滤器链中。
我们来看下 ExceptionHandlingConfigurer#configure 方法源码:
@Override public void configure(H http) { AuthenticationEntryPoint entryPoint = getAuthenticationEntryPoint(http); ExceptionTranslationFilter exceptionTranslationFilter = new ExceptionTranslationFilter( entryPoint, getRequestCache(http)); AccessDeniedHandler deniedHandler = getAccessDeniedHandler(http); exceptionTranslationFilter.setAccessDeniedHandler(deniedHandler); exceptionTranslationFilter = postProcess(exceptionTranslationFilter); http.addFilter(exceptionTranslationFilter); }
可以看到,这里构造了两个对象传入到 ExceptionTranslationFilter 中:
- AuthenticationEntryPoint 这个用来处理认证异常。
- AccessDeniedHandler 这个用来处理授权异常。
具体的处理逻辑则在 ExceptionTranslationFilter 中,我们来看一下:
public class ExceptionTranslationFilter extends GenericFilterBean { public ExceptionTranslationFilter(AuthenticationEntryPoint authenticationEntryPoint, RequestCache requestCache) { this.authenticationEntryPoint = authenticationEntryPoint; this.requestCache = requestCache; } public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { HttpServletRequest request = (HttpServletRequest) req; HttpServletResponse response = (HttpServletResponse) res; try { chain.doFilter(request, response); } catch (IOException ex) { throw ex; } catch (Exception ex) { Throwable[] causeChain = throwableAnalyzer.determineCauseChain(ex); RuntimeException ase = (AuthenticationException) throwableAnalyzer .getFirstThrowableOfType(AuthenticationException.class, causeChain); if (ase == null) { ase = (AccessDeniedException) throwableAnalyzer.getFirstThrowableOfType( AccessDeniedException.class, causeChain); } if (ase != null) { if (response.isCommitted()) { throw new ServletException("Unable to handle the Spring Security Exception because the response is already committed.", ex); } handleSpringSecurityException(request, response, chain, ase); } else { if (ex instanceof ServletException) { throw (ServletException) ex; } else if (ex instanceof RuntimeException) { throw (RuntimeException) ex; } throw new RuntimeException(ex); } } } private void handleSpringSecurityException(HttpServletRequest request, HttpServletResponse response, FilterChain chain, RuntimeException exception) throws IOException, ServletException { if (exception instanceof AuthenticationException) { sendStartAuthentication(request, response, chain, (AuthenticationException) exception); } else if (exception instanceof AccessDeniedException) { Authentication authentication = SecurityContextHolder.getContext().getAuthentication(); if (authenticationTrustResolver.isAnonymous(authentication) || authenticationTrustResolver.isRememberMe(authentication)) { sendStartAuthentication( request, response, chain, new InsufficientAuthenticationException( messages.getMessage( "ExceptionTranslationFilter.insufficientAuthentication", "Full authentication is required to access this resource"))); } else { accessDeniedHandler.handle(request, response, (AccessDeniedException) exception); } } } protected void sendStartAuthentication(HttpServletRequest request, HttpServletResponse response, FilterChain chain, AuthenticationException reason) throws ServletException, IOException { SecurityContextHolder.getContext().setAuthentication(null); requestCache.saveRequest(request, response); logger.debug("Calling Authentication entry point."); authenticationEntryPoint.commence(request, response, reason); } }
ExceptionTranslationFilter 的源码比较长,我这里列出来核心的部分和大家分析:
- 过滤器最核心的当然是 doFilter 方法,我们就从 doFilter 方法看起。这里的 doFilter 方法中过滤器链继续向下执行,ExceptionTranslationFilter 处于 Spring Security 过滤器链的倒数第二个,最后一个是 FilterSecurityInterceptor,FilterSecurityInterceptor 专门处理授权问题,在处理授权问题时,就会发现用户未登录、未授权等,进而抛出异常,抛出的异常,最终会被 ExceptionTranslationFilter#doFilter 方法捕获。
- 当捕获到异常之后,接下来通过调用
throwableAnalyzer.getFirstThrowableOfType
方法来判断是认证异常还是授权异常,判断出异常类型之后,进入到 handleSpringSecurityException 方法进行处理;如果不是 Spring Security 中的异常类型,则走 ServletException 异常类型的处理逻辑。 - 进入到 handleSpringSecurityException 方法之后,还是根据异常类型判断,如果是认证相关的异常,就走 sendStartAuthentication 方法,最终被 authenticationEntryPoint.commence 方法处理;如果是授权相关的异常,就走 accessDeniedHandler.handle 方法进行处理。
AuthenticationEntryPoint 的默认实现类是 LoginUrlAuthenticationEntryPoint,因此默认的认证异常处理逻辑就是 LoginUrlAuthenticationEntryPoint#commence 方法,如下:
public void commence(HttpServletRequest request, HttpServletResponse response, AuthenticationException authException) throws IOException, ServletException { String redirectUrl = null; if (useForward) { if (forceHttps && "http".equals(request.getScheme())) { redirectUrl = buildHttpsRedirectUrlForRequest(request); } if (redirectUrl == null) { String loginForm = determineUrlToUseForThisRequest(request, response, authException); RequestDispatcher dispatcher = request.getRequestDispatcher(loginForm); dispatcher.forward(request, response); return; } } else { redirectUrl = buildRedirectUrlToLoginPage(request, response, authException); } redirectStrategy.sendRedirect(request, response, redirectUrl); }
可以看到,就是重定向,重定向到登录页面(即当我们未登录就去访问一个需要登录才能访问的资源时,会自动重定向到登录页面)。
AccessDeniedHandler 的默认实现类则是 AccessDeniedHandlerImpl,所以授权异常默认是在 AccessDeniedHandlerImpl#handle 方法中处理的:
public void handle(HttpServletRequest request, HttpServletResponse response, AccessDeniedException accessDeniedException) throws IOException, ServletException { if (!response.isCommitted()) { if (errorPage != null) { request.setAttribute(WebAttributes.ACCESS_DENIED_403, accessDeniedException); response.setStatus(HttpStatus.FORBIDDEN.value()); RequestDispatcher dispatcher = request.getRequestDispatcher(errorPage); dispatcher.forward(request, response); } else { response.sendError(HttpStatus.FORBIDDEN.value(), HttpStatus.FORBIDDEN.getReasonPhrase()); } } }
可以看到,这里就是服务端跳转返回 403。
3.自定义处理
前面和大家介绍了 Spring Security 中默认的处理逻辑,实际开发中,我们可以需要做一些调整,很简单,在 exceptionHandling 上进行配置即可。
首先自定义认证异常处理类和授权异常处理类:
@Component public class MyAuthenticationEntryPoint implements AuthenticationEntryPoint { @Override public void commence(HttpServletRequest request, HttpServletResponse response, AuthenticationException authException) throws IOException, ServletException { response.getWriter().write("login failed:" + authException.getMessage()); } } @Component public class MyAccessDeniedHandler implements AccessDeniedHandler { @Override public void handle(HttpServletRequest request, HttpServletResponse response, AccessDeniedException accessDeniedException) throws IOException, ServletException { response.setStatus(403); response.getWriter().write("Forbidden:" + accessDeniedException.getMessage()); } }
然后在 SecurityConfig 中进行配置,如下:
@Configuration public class SecurityConfig extends WebSecurityConfigurerAdapter { @Override protected void configure(HttpSecurity http) throws Exception { http.authorizeRequests() ... ... .and() .exceptionHandling() .authenticationEntryPoint(myAuthenticationEntryPoint) .accessDeniedHandler(myAccessDeniedHandler) .and() ... ... } }
配置完成后,重启项目,认证异常和授权异常就会走我们自定义的逻辑了。
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