Spring Securtiy 认证流程(源码分析)
当用 Spring Security 框架进行认证时，你可能会遇到这样的问题：
你输入的用户名或密码不管是空还是错误，它的错误信息都是 Bad credentials。
那么如果你想根据不同的情况给出相应的错误提示该怎么办呢？
这个时候我们只有了解 Spring Securiy 认证的流程才能知道如何修改代码。
好啦，来看下面的例子，大部分人的 WebSecurityConfig 的 configure 代码都类似于下：
@Override protected void configure(HttpSecurity http) throws Exception { // TODO Auto-generated method stub http .authorizeRequests() .anyRequest().permitAll() .and() .formLogin().loginPage("/signin") .usernameParameter("username") .passwordParameter("password") .loginProcessingUrl("/signin") .and() .csrf().disable(); }
相信以上代码大家都知道什么意思：任何请求信息都允许，也就是不需要身份认证。
登录页面请求为 /signin，用户名和密码参数的name属性分别是 username，password。登录页面 form 的 action 请求为 /signin。
当然这个 action 不必和登录页面请求一样。最后的那个是禁止跨站请求伪造。
这段代码和登录认证联系较大的应该是从 loginPage() 到 loginProcessingUrl() 里的方法。
咱先从 loginPage 看起，鼠标左键拖动覆盖 loginPage，然后右键 Open Declaration 就进入到了 FormLoginConfigurer 类。
这个类里值得注意的方法有两个：构造方法和 loginPage 方法。
public FormLoginConfigurer() { super(new UsernamePasswordAuthenticationFilter(), null); usernameParameter("username"); passwordParameter("password"); } public FormLoginConfigurer<H> loginPage(String loginPage) { return super.loginPage(loginPage); }
构造方法中使用了一个用户名密码认证过滤器类，这一看就和认证有关系。
loginPage 方法大家可以自行按照这个步骤查看，现在直接看 UsernamePasswordAuthenticationFilter 类。
public static final String SPRING_SECURITY_FORM_USERNAME_KEY = "username"; public static final String SPRING_SECURITY_FORM_PASSWORD_KEY = "password"; private String usernameParameter = SPRING_SECURITY_FORM_USERNAME_KEY; private String passwordParameter = SPRING_SECURITY_FORM_PASSWORD_KEY; private boolean postOnly = true; public UsernamePasswordAuthenticationFilter() { super(new AntPathRequestMatcher("/login", "POST")); } public Authentication attemptAuthentication(HttpServletRequest request, HttpServletResponse response) throws AuthenticationException { if (postOnly && !request.getMethod().equals("POST")) { throw new AuthenticationServiceException( "Authentication method not supported: " + request.getMethod()); } String username = obtainUsername(request); String password = obtainPassword(request); if (username == null) { username = ""; } if (password == null) { password = ""; } username = username.trim(); UsernamePasswordAuthenticationToken authRequest = new UsernamePasswordAuthenticationToken(
username, password);
setDetails(request, authRequest); return this.getAuthenticationManager().authenticate(authRequest); }
这只是其中一部分代码，其他的可以自己看。该类中定义的两个字符串和构造方法定义了默认的登录方式。
登录 action 请求为以 POST 方式的 /login，用户名及密码分别以 username，password 属性值获取。
该类的父类的父类 GenericFilterBean 实现了 InitializingBean 接口，也就是会初始化为一个 Bean。
当看到 attemptAuthentication 时，就知道他是认证的方法啦。
这里咱直接看到 new UsernamePasswordAuthenticationToken(username, password);
public UsernamePasswordAuthenticationToken(Object principal, Object credentials) { super(null); this.principal = principal; this.credentials = credentials; setAuthenticated(false); }
从这里可以知道，它把用户名和密码分别存在了 principal，credentials 里。
现在我们只需要记住登录信息存在了 authRequest 里。现在来看下setDetails，虽然我不感兴趣。
protected void setDetails(HttpServletRequest request, UsernamePasswordAuthenticationToken authRequest) { authRequest.setDetails(authenticationDetailsSource.buildDetails(request)); }
它调用了一个 buildDetails 方法，实际上是调用的：(追根溯源可以看到)
/**
* Records the remote address and will also set the session Id if a session already
* exists (it won't create one).
*
* @param request that the authentication request was received from
*/
public WebAuthenticationDetails(HttpServletRequest request) { this.remoteAddress = request.getRemoteAddr(); HttpSession session = request.getSession(false); this.sessionId = (session != null) ? session.getId() : null; }
从源码注释可以看到，它是记录远程地址并且会设置一个会话 ID，这里我们不管它了。
直接看这一句：return this.getAuthenticationManager().authenticate(authRequest);
它调用的是一个实现了 AuthenticationManager 接口的类的 authenticate 方法。
从源码中我们找不到它用的是哪个实现类，网上说是 ProviderManager 类，我们来看一下该类。
public class ProviderManager implements AuthenticationManager, MessageSourceAware, InitializingBean { public Authentication authenticate(Authentication authentication) throws AuthenticationException { Class<? extends Authentication> toTest = authentication.getClass(); AuthenticationException lastException = null; AuthenticationException parentException = null; Authentication result = null; Authentication parentResult = null; boolean debug = logger.isDebugEnabled(); for (AuthenticationProvider provider : getProviders()) { if (!provider.supports(toTest)) { continue; } if (debug) { logger.debug("Authentication attempt using " + provider.getClass().getName()); } try { result = provider.authenticate(authentication); if (result != null) { copyDetails(authentication, result); break; } } catch (AccountStatusException e) { prepareException(e, authentication); // SEC-546: Avoid polling additional providers if auth failure is due to // invalid account status throw e; } catch (InternalAuthenticationServiceException e) { prepareException(e, authentication); throw e; } catch (AuthenticationException e) { lastException = e; } } if (result == null && parent != null) { // Allow the parent to try. try { result = parentResult = parent.authenticate(authentication); } catch (ProviderNotFoundException e) { // ignore as we will throw below if no other exception occurred prior to // calling parent and the parent // may throw ProviderNotFound even though a provider in the child already // handled the request } catch (AuthenticationException e) { lastException = parentException = e; } } if (result != null) { if (eraseCredentialsAfterAuthentication && (result instanceof CredentialsContainer)) { // Authentication is complete. Remove credentials and other secret data // from authentication ((CredentialsContainer) result).eraseCredentials(); } // If the parent AuthenticationManager was attempted and successful than it will publish an AuthenticationSuccessEvent // This check prevents a duplicate AuthenticationSuccessEvent if the parent AuthenticationManager already published it if (parentResult == null) { eventPublisher.publishAuthenticationSuccess(result); } return result; } // Parent was null, or didn't authenticate (or throw an exception). if (lastException == null) { lastException = new ProviderNotFoundException(messages.getMessage( "ProviderManager.providerNotFound", new Object[] { toTest.getName() }, "No AuthenticationProvider found for {0}")); } // If the parent AuthenticationManager was attempted and failed than it will publish an AbstractAuthenticationFailureEvent // This check prevents a duplicate AbstractAuthenticationFailureEvent if the parent AuthenticationManager already published it if (parentException == null) { prepareException(lastException, authentication); } throw lastException; } }
这里我只给出该类的声明和 authenticate 方法，从类的声明可以看出来它也会初始化为一个 Bean，咱找不到很正常对吧。
authenticate 方法会遍历所有的 AuthenticationProvider ，然后调用 provider 的 authenticate 方法。
如果认证结果不为空的话将会保存到 result 中，并且擦除认证信息再返回 result。
为空的话一般是没有提供 AuthenticationProvider，会报 ProviderNotFoundException 错误。
现在我们来看下 provider 的 authenticate 方法。
@Bean public AuthenticationProvider authenticationProvider() { DaoAuthenticationProvider provider = new CustomAuthenticationProvider(); provider.setMessageSource(messageSource); provider.setUserDetailsService(userService); provider.setPasswordEncoder(new BCryptPasswordEncoder()); return provider; }
这个是我写的一个 AuthenticationProvider，只不过我重写了一个类继承了 DaoAuthenticationProvider。
这里我们来看 DaoAuthenticationProvider 类：(这个类里面并没有发现 authenticate 方法，那先从它的父类找)
父类是 AbstractUserDetailsAuthenticationProvider，它也实现了 InitializingBean 接口，也是初始化为一个 Bean。
public Authentication authenticate(Authentication authentication) throws AuthenticationException { Assert.isInstanceOf(UsernamePasswordAuthenticationToken.class, authentication, () -> messages.getMessage( "AbstractUserDetailsAuthenticationProvider.onlySupports", "Only UsernamePasswordAuthenticationToken is supported")); // Determine username String username = (authentication.getPrincipal() == null) ? "NONE_PROVIDED" : authentication.getName(); boolean cacheWasUsed = true; UserDetails user = this.userCache.getUserFromCache(username); if (user == null) { cacheWasUsed = false; try { user = retrieveUser(username, (UsernamePasswordAuthenticationToken) authentication); } catch (UsernameNotFoundException notFound) { logger.debug("User '" + username + "' not found"); if (hideUserNotFoundExceptions) { throw new BadCredentialsException(messages.getMessage( "AbstractUserDetailsAuthenticationProvider.badCredentials", "Bad credentials")); } else { throw notFound; } } Assert.notNull(user, "retrieveUser returned null - a violation of the interface contract"); } try { preAuthenticationChecks.check(user); additionalAuthenticationChecks(user, (UsernamePasswordAuthenticationToken) authentication); } catch (AuthenticationException exception) { if (cacheWasUsed) { // There was a problem, so try again after checking // we're using latest data (i.e. not from the cache) cacheWasUsed = false; user = retrieveUser(username, (UsernamePasswordAuthenticationToken) authentication); preAuthenticationChecks.check(user); additionalAuthenticationChecks(user, (UsernamePasswordAuthenticationToken) authentication); } else { throw exception; } } postAuthenticationChecks.check(user); if (!cacheWasUsed) { this.userCache.putUserInCache(user); } Object principalToReturn = user; if (forcePrincipalAsString) { principalToReturn = user.getUsername(); } return createSuccessAuthentication(principalToReturn, authentication, user); }
在这段代码中可以知道：如果 authentication.getPrincipal() 为空的话，username 将会为 NONE_PROVIDED。
不为空的话将会得到 authentication.getPrincipal()，也就是用户名，只是这种类型不是 String 类型，但可以强制转换。
代码中是 authentication.getName()，这种和上面基本一样，只不过该类型是 String 类型的。
然后定义一个 user，先尝试从缓存中获取 user，没获取到的话就通过 retrieveUser 获取。
该类中 retrieveUser 是一个抽象方法，我们现在来看 DaoAuthenticationProvider 类里的方法。
protected final UserDetails retrieveUser(String username, UsernamePasswordAuthenticationToken authentication) throws AuthenticationException { prepareTimingAttackProtection(); try { UserDetails loadedUser = this.getUserDetailsService().loadUserByUsername(username); if (loadedUser == null) { throw new InternalAuthenticationServiceException( "UserDetailsService returned null, which is an interface contract violation"); } return loadedUser; } catch (UsernameNotFoundException ex) { mitigateAgainstTimingAttack(authentication); throw ex; } catch (InternalAuthenticationServiceException ex) { throw ex; } catch (Exception ex) { throw new InternalAuthenticationServiceException(ex.getMessage(), ex); } }
从代码中可以看到是通过我们之前写的 UserDetailsService 方法获取用户。
接下来我们看后面的代码，这部分异常代码我们等会再看。
try { preAuthenticationChecks.check(user); additionalAuthenticationChecks(user, (UsernamePasswordAuthenticationToken) authentication); }
这两句代码是对用户进行检查的，第一行代码调用的其实是这部分的：
private class DefaultPreAuthenticationChecks implements UserDetailsChecker { public void check(UserDetails user) { if (!user.isAccountNonLocked()) { logger.debug("User account is locked"); throw new LockedException(messages.getMessage( "AbstractUserDetailsAuthenticationProvider.locked", "User account is locked")); } if (!user.isEnabled()) { logger.debug("User account is disabled"); throw new DisabledException(messages.getMessage( "AbstractUserDetailsAuthenticationProvider.disabled", "User is disabled")); } if (!user.isAccountNonExpired()) { logger.debug("User account is expired"); throw new AccountExpiredException(messages.getMessage( "AbstractUserDetailsAuthenticationProvider.expired", "User account has expired")); } } }
可以看到并不是检查密码的，只是对用户状态进行检查。那么我们不管它了，看下一行代码：
@SuppressWarnings("deprecation")
protected void additionalAuthenticationChecks(UserDetails userDetails,
UsernamePasswordAuthenticationToken authentication)
throws AuthenticationException {
if (authentication.getCredentials() == null) {
logger.debug("Authentication failed: no credentials provided");
throw new BadCredentialsException(messages.getMessage(
"AbstractUserDetailsAuthenticationProvider.badCredentials",
"Bad credentials"));
}
String presentedPassword = authentication.getCredentials().toString();
if (!passwordEncoder.matches(presentedPassword, userDetails.getPassword())) {
logger.debug("Authentication failed: password does not match stored value");
throw new BadCredentialsException(messages.getMessage(
"AbstractUserDetailsAuthenticationProvider.badCredentials",
"Bad credentials"));
}
}
这里有个获取密码的操作：authentication.getCredentials()。
然后如果密码不为空的话就通过 passwordEncoder.matches(presentedPassword, userDetails.getPassword() 检查是否匹配。
如果匹配成功的话，嗯，这部分结束了，我们回到 AbstractUserDetailsAuthenticationProvider 类里的 authenticate 方法。
return createSuccessAuthentication(principalToReturn, authentication, user);
它会返回一个创建成功认证方法的返回值。这里我们就不管了。
现在我们先回到AbstractUserDetailsAuthenticationProvider 类的错误处理上：
try { user = retrieveUser(username, (UsernamePasswordAuthenticationToken) authentication); } catch (UsernameNotFoundException notFound) { logger.debug("User '" + username + "' not found"); if (hideUserNotFoundExceptions) { throw new BadCredentialsException(messages.getMessage( "AbstractUserDetailsAuthenticationProvider.badCredentials", "Bad credentials")); } else { throw notFound; } }
这个是用户找不到引起的错误，我们看下 messages.getMessage()：
public String getMessage(String code, String defaultMessage) { String msg = this.messageSource.getMessage(code, null, defaultMessage, getDefaultLocale()); return (msg != null ? msg : ""); }
再来看下这个里面的 getMessage()：
它是一个接口类里的方法：根据 code 返回 messageSource 里的字符串，如果不存在这个 code，就返回 defaultMessage。
既然是个接口类，那我们看下它的实现类，回到 messageSource，查看一下它：
public class SpringSecurityMessageSource extends ResourceBundleMessageSource { // ~ Constructors // =================================================================================================== public SpringSecurityMessageSource() { setBasename("org.springframework.security.messages"); } // ~ Methods // ======================================================================================================== public static MessageSourceAccessor getAccessor() { return new MessageSourceAccessor(new SpringSecurityMessageSource()); } }
原来是从这个路径里找数据源。
其他的错误处理也是一样，这里就省略了。那我们如何获取错误信息呢？
@Override protected void configure(HttpSecurity http) throws Exception { // TODO Auto-generated method stub http .authorizeRequests() .anyRequest().permitAll() .and() .formLogin().loginPage("/signin") .usernameParameter("username") .passwordParameter("password") .loginProcessingUrl("/signin") .failureHandler(authenticationFailureHandler) .and() .csrf().disable();
看到那个 failureHandler 没，这个是登录失败处理器，这里加上只是看一下里面源码：AbstractAuthenticationFilterConfigurer
/** * Specifies the {@link AuthenticationFailureHandler} to use when authentication * fails. The default is redirecting to "/login?error" using * {@link SimpleUrlAuthenticationFailureHandler} * * @param authenticationFailureHandler the {@link AuthenticationFailureHandler} to use * when authentication fails. * @return the {@link FormLoginConfigurer} for additional customization */ public final T failureHandler( AuthenticationFailureHandler authenticationFailureHandler) { this.failureUrl = null; this.failureHandler = authenticationFailureHandler; return getSelf(); }
从注释中可以看出默认的失败处理器是 SimpleUrlAuthenticationFailureHandler：
public void onAuthenticationFailure(HttpServletRequest request, HttpServletResponse response, AuthenticationException exception) throws IOException, ServletException { if (defaultFailureUrl == null) { logger.debug("No failure URL set, sending 401 Unauthorized error"); response.sendError(HttpStatus.UNAUTHORIZED.value(), HttpStatus.UNAUTHORIZED.getReasonPhrase()); } else { saveException(request, exception); if (forwardToDestination) { logger.debug("Forwarding to " + defaultFailureUrl); request.getRequestDispatcher(defaultFailureUrl) .forward(request, response); } else { logger.debug("Redirecting to " + defaultFailureUrl); redirectStrategy.sendRedirect(request, response, defaultFailureUrl); } } }
因为默认的 defaultFailureUrl 为 /login?error，从 AbstractAuthenticationFilterConfigurer 类里可以看出来。
登录失败后，会调用 saveException(request, exception); 保存错误信息。
protected final void saveException(HttpServletRequest request, AuthenticationException exception) { if (forwardToDestination) { request.setAttribute(WebAttributes.AUTHENTICATION_EXCEPTION, exception); } else { HttpSession session = request.getSession(false); if (session != null || allowSessionCreation) { request.getSession().setAttribute(WebAttributes.AUTHENTICATION_EXCEPTION, exception); } } }
由于该类中 forwardToDestination 为 false，它将执行 else 里的语句。
将错误信息保存到会话的 WebAttributes.AUTHENTICATION_EXCEPTION 属性中：
public static final String AUTHENTICATION_EXCEPTION = "SPRING_SECURITY_LAST_EXCEPTION";
所有我们可以通过会话的这个属性来获取错误信息。(thymeleaf)
(注意：signin.html 不能放在 static 目录下，不然获取不到错误信息。)
<p th:if="${param.error}" th:text="${session?.SPRING_SECURITY_LAST_EXCEPTION?.message}" ></p>
好啦，都介绍完了，可以看下我的 CustomAuthenticationProvider：
package security.config; import org.springframework.security.authentication.BadCredentialsException; import org.springframework.security.authentication.UsernamePasswordAuthenticationToken; import org.springframework.security.authentication.dao.DaoAuthenticationProvider; import org.springframework.security.core.Authentication; import org.springframework.security.core.AuthenticationException; import org.springframework.security.core.userdetails.UserDetails; import org.springframework.security.core.userdetails.UsernameNotFoundException; import org.springframework.util.Assert; public class CustomAuthenticationProvider extends DaoAuthenticationProvider { @Override protected void additionalAuthenticationChecks(UserDetails userDetails, UsernamePasswordAuthenticationToken authentication) throws AuthenticationException { // TODO Auto-generated method stub String presentedPassword = authentication.getCredentials().toString(); if (!getPasswordEncoder().matches(presentedPassword, userDetails.getPassword())) { logger.debug("Authentication failed: password does not match stored value"); throw new BadCredentialsException(messages.getMessage( "UNameOrPwdIsError","Username or Password is not correct")); } } @Override public Authentication authenticate(Authentication authentication) throws AuthenticationException { // TODO Auto-generated method stub Assert.isInstanceOf(UsernamePasswordAuthenticationToken.class, authentication, () -> messages.getMessage( "AbstractUserDetailsAuthenticationProvider.onlySupports", "Only UsernamePasswordAuthenticationToken is supported")); if("".equals(authentication.getPrincipal())) { throw new BadCredentialsException(messages.getMessage( "UsernameIsNull","Username cannot be empty")); } if("".equals(authentication.getCredentials())) { throw new BadCredentialsException(messages.getMessage( "PasswordIsNull","Password cannot be empty")); } String username = (String) authentication.getPrincipal(); boolean cacheWasUsed = true; UserDetails user = this.getUserCache().getUserFromCache(username); if (user == null) { cacheWasUsed = false; try { user = retrieveUser(username, (UsernamePasswordAuthenticationToken) authentication); } catch (UsernameNotFoundException notFound) { logger.debug("User '" + username + "' not found"); if (hideUserNotFoundExceptions) { throw new BadCredentialsException(messages.getMessage( "UNameOrPwdIsError","Username or Password is not correct")); } else { throw notFound; } } Assert.notNull(user, "retrieveUser returned null - a violation of the interface contract"); } try { getPreAuthenticationChecks().check(user); additionalAuthenticationChecks(user, (UsernamePasswordAuthenticationToken) authentication); } catch (AuthenticationException exception) { if (cacheWasUsed) { cacheWasUsed = false; user = retrieveUser(username, (UsernamePasswordAuthenticationToken) authentication); getPreAuthenticationChecks().check(user); additionalAuthenticationChecks(user, (UsernamePasswordAuthenticationToken) authentication); } else { throw exception; } } getPostAuthenticationChecks().check(user); if (!cacheWasUsed) { this.getUserCache().putUserInCache(user); } Object principalToReturn = user; if (isForcePrincipalAsString()) { principalToReturn = user.getUsername(); } return createSuccessAuthentication(principalToReturn, authentication, user); } }
这里值得注意的是 "".equals(authentication.getPrincipal())，"".equals(authentication.getCredentials())
因为如果按照那个 AbstractUserDetailsAuthenticationProvider 类来写的话，发现这一步永不为 null。
我通过加入代码 System.out.println(username); 才知道的，应该是个坑吧。
项目代码可供大家参考：
链接：https://pan.baidu.com/s/13fc6P9NV49aRRBctr3MjNQ
提取码：4qgu
