AuthenticationManager相关类图
AuthenticationManager验证过程
AuthenticationManager验证过程涉及到的类和接口较多，我们就从这里开始逐一分析，首先我手画了一张图作为索引，这张图说明了各个类和接口之间的关系。
[图片上传失败...(image-31deef-1606271028193)]AuthenticationManager 为认证管理接口类，其定义了认证方法authenticate()。
ProviderManager 为验证管理类，实现了接口AuthenticationManager ，并在认证方法authenticate() 中将身份认证委托给具有认证资格的AuthenticationProvider 进行身份认证。
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从上图中我们可以看到AuthenticationManager的实现类有很多，至于为什么我只提及到ProviderManager，有时间的小伙伴可以进行源码跟踪就能发现。
ProviderManager的成员变量
- 关于AuthenticationEventPublisher不懂的小伙伴可以查看Security中的认证事件发布器 。
- providers存储了一个 AuthenticationProvider 类型的list。和Security中的配置文件相对应。
- MessageSourceAccessor一个国际化消息来源访问器，Security中用于信息提示。
AuthenticationProvider
- 接口认证类，定义了认证方法authenticate() 。
- AbstractUserDetailsAuthenticationProvider 为认证抽象类，实现了接口 AuthenticationProvider 定义的认证方法 authenticate()。还定义了抽象方法 retrieveUser() 用于查询数据库用户信息，以及抽象方法 additionalAuthenticationChecks() 用作额外的身份验证检查。
DaoAuthenticationProvider
- 继承自抽象类AbstractUserDetailsAuthenticationProvider，实现了该类的方法 retrieveUser() 和 additionalAuthenticationChecks()。
- DaoAuthenticationProvider 中还具有四个成员变量，分别是
-
USER_NOT_FOUND_PASSWORD
顾名思义，该变量是与PasswordEncoder一同使用的，当Security未找到用户时，用于PasswordEncoder.matches()执行的明文密码，以防止恶意用户确定用户名是否有效的旁路攻击的可能性。 -
PasswordEncoder
密码编码器，Security中的主要作用是用于将明文密码转换成密文，它采用SHA-256算法，迭代1024次，使用一个密钥(site-wide secret)以及8位随机盐对原密码进行加密。 -
userNotFoundEncodedPassword
同上方USER_NOT_FOUND_PASSWORD一致，只不过Security将其修饰为volatile的，确保了该变量不会因为编译器的优化而被省略。
关于volatile关键字不懂的请查看volatile理解 -
UserDetailsService
这个变量相信很多人都知道，不做过多的解释，Security中用于查询用户详细信息的接口 -
UserDetailsPasswordService
顾名思义，该接口用于修改用户的密码，只有在使用持久存储库时才有效，基于内存的方式会抛异常。(用处不大，只做了解即可)
流程分析
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static final class AuthenticationManagerDelegator implements AuthenticationManager {
private AuthenticationManagerBuilder delegateBuilder;
private AuthenticationManager delegate;
private final Object delegateMonitor = new Object();
AuthenticationManagerDelegator(AuthenticationManagerBuilder delegateBuilder) {
Assert.notNull(delegateBuilder, "delegateBuilder cannot be null");
this.delegateBuilder = delegateBuilder;
}
@Override
public Authentication authenticate(Authentication authentication)
throws AuthenticationException {
if (this.delegate != null) {
return this.delegate.authenticate(authentication);
}
synchronized (this.delegateMonitor) {
if (this.delegate == null) {
this.delegate = this.delegateBuilder.getObject();
this.delegateBuilder = null;
}
}
return this.delegate.authenticate(authentication);
}
@Override
public String toString() {
return "AuthenticationManagerDelegator [delegate=" + this.delegate + "]";
}
}
1、Security认证的入口为AuthenticationManager的authenticate()方法，从上面代码中我们可以看出，AuthenticationManagerDelegator使用了单例模式来防止AuthenticationManager在初始化时发生无限递归，因此我们只分析上方的两个实现类OAuth2AuthenticationManager和ProviderManager。
OAuth2AuthenticationManager
OAuth2AuthenticationManager的authenticate()的方法代码如下：
public Authentication authenticate(Authentication authentication) throws AuthenticationException {
if (authentication == null) {
throw new InvalidTokenException("Invalid token (token not found)");
}
（1） String token = (String) authentication.getPrincipal();
（2） OAuth2Authentication auth = tokenServices.loadAuthentication(token);
if (auth == null) {
throw new InvalidTokenException("Invalid token: " + token);
}
Collection<String> resourceIds = auth.getOAuth2Request().getResourceIds();
if (resourceId != null && resourceIds != null && !resourceIds.isEmpty() && !resourceIds.contains(resourceId)) {
throw new OAuth2AccessDeniedException("Invalid token does not contain resource id (" + resourceId + ")");
}
（3） checkClientDetails(auth);
if (authentication.getDetails() instanceof OAuth2AuthenticationDetails) {
OAuth2AuthenticationDetails details = (OAuth2AuthenticationDetails) authentication.getDetails();
// Guard against a cached copy of the same details
if (!details.equals(auth.getDetails())) {
// Preserve the authentication details from the one loaded by token services
details.setDecodedDetails(auth.getDetails());
}
}
auth.setDetails(authentication.getDetails());
auth.setAuthenticated(true);
return auth;
}
private void checkClientDetails(OAuth2Authentication auth) {
if (clientDetailsService != null) {
ClientDetails client;
try {
client = clientDetailsService.loadClientByClientId(auth.getOAuth2Request().getClientId());
}
catch (ClientRegistrationException e) {
throw new OAuth2AccessDeniedException("Invalid token contains invalid client id");
}
Set<String> allowed = client.getScope();
for (String scope : auth.getOAuth2Request().getScope()) {
if (!allowed.contains(scope)) {
throw new OAuth2AccessDeniedException(
"Invalid token contains disallowed scope (" + scope + ") for this client");
}
}
}
}
OAuth2AuthenticationManager用于集成了OAuth2.0时使用的，如果没有用到，可以忽略。
其中：
- (1)处的代码，期望传入的身份验证请求具有一个主体值，该主体值是一个访问令牌值（一般在（authorization header）请求头中）
- (2)处从ResourceServerTokenServices通过查询数据库中 oauth_client_details该表，加载身份验证。
- 通过(3)处检查资源id是否包含在授权请求中。检查通过之后封装OAuth2认证实体返回给UsernamePasswordAuthenticationFilter以确定认证成功或失败。
ProviderManager
ProviderManager的authenticate()的方法代码如下：
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();
（1） for (AuthenticationProvider provider : getProviders()) {
if (!provider.supports(toTest)) {
continue;
}
if (debug) {
logger.debug("Authentication attempt using "
+ provider.getClass().getName());
}
try {
（2） result = provider.authenticate(authentication);
if (result != null) {
copyDetails(authentication, result);
break;
}
}
catch (AccountStatusException | InternalAuthenticationServiceException e) {
prepareException(e, authentication);
// SEC-546: Avoid polling additional providers if auth failure is due to
// invalid account status
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;
}
其中：
- (1)处的代码从ProviderManager的属性providers[List<authenticationprovider style="margin: 0px; padding: 0px;">]</authenticationprovider>中通过for循环拿到支持该类认证的AuthenticationProvider用于认证处理。
- (2)处的代码，对用户进行身份认证，认证过程如下所示。
在上面(2)处的代码，使用了AbstractUserDetailsAuthenticationProvider的authenticate()方法，接下来具体分析该方法，代码如下：
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 {
（1） 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);
（2） 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();
}
（3） return createSuccessAuthentication(principalToReturn, authentication, user);
}
-
(3)处创建一个成功的身份认证令牌并将用户认证信息其放置到UsernamePasswordAuthenticationToken中。
查看源码我们得知，AbstractUserDetailsAuthenticationProvider的(1)处和(2)处调用的方法没有具体的实现，因此我们接下来分析它的子类DaoAuthenticationProvider
retrieveUser()
protected final UserDetails retrieveUser(String username,
UsernamePasswordAuthenticationToken authentication)
throws AuthenticationException {
prepareTimingAttackProtection();
try {
(1) 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);
}
}
(1)处调用DaoAuthenticationProvider成员变量UserDetailsService的方法loadUserByUsername()从数据库中加载用户详细信息（用过Security的对此处应该是很熟悉了）
- additionalAuthenticationChecks()
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"));
}
（1） String presentedPassword = authentication.getCredentials().toString();
（2） 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"));
}
}
(1)处从UsernamePasswordAuthenticationToken中调出了密码，再由(2)处通过调用成员变量passwordEncoder对其密码进行验证。
