【OAuth2.0】Spring Security OAuth2.0对于OAuth2.0协议中四种授权类型的实现

前言

OAuth2.0定义的几种Authorization Grant

Authorization Grant是资源所有者赋予第三方client的一份证书，第三方client可以凭此证书获取一个access token，后者可以用来直接访问资源所有者的某些受限资源，而不用知道资源所有者的用户名密码等信息。

OAuth2.0中目前有四种授权类型：Authorization Code,implicit,resource owner password credentials,client credentials

实现

Spring的具体实现(TokenGranter)

上述几种类型的授权类型中，Spring有对应的几种TokenGranter，类继承结构如下图：

可以看到类CompositeTokenGranter和AbstractTokenGranter直接implements接口TokenGranter。其中，

前者实际类定义中维持了一个对所有具体TokenGranter的引用list，调用其grant方法时，会遍历该list，调用每一个引用的grant方法，直到有granter生成并返回OAuth2AccessToken或者list到最后。该TokenGranter用到的地方自己看代码的过程中，发现在TokenEndpoint中有对其的直接引用，实际结合对authorization-server的配置就可以直到这个CompositeTokenGranter对其他TokenGranter的引用list怎么来的了：

<oauth2:authorization-server client-details-service-ref="clientDetailsService" token-services-ref="tokenServices"
                                user-approval-handler-ref="oauthUserApprovalHandler"
                                user-approval-page="oauth_approval"
                                error-page="oauth_error">
       <!--后面这几种授权方式应该都会整合进入CompositeTokenGranter的List<TokenGranter>属性当中的-->
       <oauth2:authorization-code authorization-code-services-ref="authorizationCodeServices" />
       <oauth2:implicit/>
       <oauth2:refresh-token/>
       <oauth2:client-credentials/>
       <oauth2:password/>
   </oauth2:authorization-server>

而后者AbstractTokenGranter则是个抽象类，有具体实现的TokenGranter会继承该类

接口TokenGranter用于生成OAuth2AccessToken，接口就定义了一个方法：OAuth2AccessToken grant(String grantType, AuthorizationRequest authorizationRequest)。OAuth2AccessToken定义如下，其getValue()方法返回的即是返回客户端的access_token。

public interface OAuth2AccessToken {

	public static String BEARER_TYPE = "Bearer";

	public static String OAUTH2_TYPE = "OAuth2";

	/**
	 * The access token issued by the authorization server. This value is REQUIRED.
	 */
	public static String ACCESS_TOKEN = "access_token";

	/**
	 * The type of the token issued as described in <a
	 * href="http://tools.ietf.org/html/draft-ietf-oauth-v2-22#section-7.1">Section 7.1</a>. Value is case insensitive.
	 * This value is REQUIRED.
	 */
	public static String TOKEN_TYPE = "token_type";

	/**
	 * The lifetime in seconds of the access token. For example, the value "3600" denotes that the access token will
	 * expire in one hour from the time the response was generated. This value is OPTIONAL.
	 */
	public static String EXPIRES_IN = "expires_in";

	/**
	 * The refresh token which can be used to obtain new access tokens using the same authorization grant as described
	 * in <a href="http://tools.ietf.org/html/draft-ietf-oauth-v2-22#section-6">Section 6</a>. This value is OPTIONAL.
	 */
	public static String REFRESH_TOKEN = "refresh_token";

	/**
	 * The scope of the access token as described by <a
	 * href="http://tools.ietf.org/html/draft-ietf-oauth-v2-22#section-3.3">Section 3.3</a>
	 */
	public static String SCOPE = "scope";

	/**
	 * The additionalInformation map is used by the token serializers to export any fields used by extensions of OAuth.
	 * @return a map from the field name in the serialized token to the value to be exported. The default serializers 
	 * make use of Jackson's automatic JSON mapping for Java objects (for the Token Endpoint flows) or implicitly call 
	 * .toString() on the "value" object (for the implicit flow) as part of the serialization process.
	 */
	Map<String, Object> getAdditionalInformation();

	Set<String> getScope();

	OAuth2RefreshToken getRefreshToken();

	String getTokenType();

	boolean isExpired();

	Date getExpiration();

	int getExpiresIn();

	String getValue();

}

AuthorizationCodeTokenGranter

我们的项目使用的授权类型是Authorization Code，其余授权类型暂时完全没看的状态。

结合上面说的，第三方client会先申请authorization code(这部分逻辑以后单独说)，得到code之后，由第三方client向/auth/token发起获取access token请求(调用的实际就是TokenEndpoint中的逻辑)，类似：http://localhost:8080/oauth/token?client_id=id&client_secret=secret&grant_type=authorization_code&scope=read,write&redirect_uri=none&code=3iW8lA

@RequestMapping(value = "/oauth/token")
public class TokenEndpoint extends AbstractEndpoint {

	@RequestMapping
	public ResponseEntity<OAuth2AccessToken> getAccessToken(Principal principal,
			@RequestParam(value = "grant_type", required = false) String grantType,
			@RequestParam Map<String, String> parameters) {

		//...
                //...
                //部分代码省略 getTokenGranter()返回的是CompositeTokenGranter对象
		OAuth2AccessToken token = getTokenGranter().grant(grantType, authorizationRequest);
		if (token == null) {
			throw new UnsupportedGrantTypeException("Unsupported grant type: " + grantType);
		}

		return getResponse(token);

	}
}

而CompositeTokenGranter的实现如下：

public class CompositeTokenGranter implements TokenGranter {

	private final List<TokenGranter> tokenGranters;

	public CompositeTokenGranter(List<TokenGranter> tokenGranters) {
		this.tokenGranters = new ArrayList<TokenGranter>(tokenGranters);
	}
	
	public OAuth2AccessToken grant(String grantType, AuthorizationRequest authorizationRequest) {
		for (TokenGranter granter : tokenGranters) {
			OAuth2AccessToken grant = granter.grant(grantType, authorizationRequest);
			if (grant!=null) {
				return grant;
			}
		}
		return null;
	}

}

所以，这样，如果我们上面的xml配置中，启用了AuthorizaitonCode授权方式，那么这里就会使用到，并调用其grant方法获取access token(grant方法实际是AbstractTokenGranter类中定义好的，子类只需要定义好其需要的几个方法即可，比如getOAuth2Authentication())

in class AbstractTokenGranter:

	public OAuth2AccessToken grant(String grantType, AuthorizationRequest authorizationRequest) {

		if (!this.grantType.equals(grantType)) {
			return null;
		}
		
		String clientId = authorizationRequest.getClientId();
		ClientDetails client = clientDetailsService.loadClientByClientId(clientId);
		validateGrantType(grantType, client);
		
		logger.debug("Getting access token for: " + clientId);
		return getAccessToken(authorizationRequest);

	}

	protected OAuth2AccessToken getAccessToken(AuthorizationRequest authorizationRequest) {
		DefaultAuthorizationRequest outgoingRequest  = new DefaultAuthorizationRequest(authorizationRequest);
		outgoingRequest.setApproved(true);
		// FIXME: do we need to explicitly set approved flag here?
		return tokenServices.createAccessToken(getOAuth2Authentication(outgoingRequest));
	}

in subclass AuthorizationCodeTokenGranter(会对client id和redirect uri等进行校验，并且要注意的是，因为是使用code换取access token，所以这里还需要另用掉的code失效):

	@Override
	protected OAuth2Authentication getOAuth2Authentication(AuthorizationRequest authorizationRequest) {

		Map<String, String> parameters = authorizationRequest.getAuthorizationParameters();
		String authorizationCode = parameters.get("code");
		String redirectUri = parameters.get(AuthorizationRequest.REDIRECT_URI);

		if (authorizationCode == null) {
			throw new OAuth2Exception("An authorization code must be supplied.");
		}

		AuthorizationRequestHolder storedAuth = authorizationCodeServices.consumeAuthorizationCode(authorizationCode);//让code失效，如果使用DB的话，就是删除该code对应的记录，这里DB删除之后会把这条记录同时返回
		if (storedAuth == null) {
			throw new InvalidGrantException("Invalid authorization code: " + authorizationCode);
		}

		AuthorizationRequest pendingAuthorizationRequest = storedAuth.getAuthenticationRequest();//反序列化，client申请code时是将code及其对应的AuthorizationRequest对象序列化之后一并存入Db的，所以这里可以反序列化出来使用
		// https://jira.springsource.org/browse/SECOAUTH-333
		// This might be null, if the authorization was done without the redirect_uri parameter
		String redirectUriApprovalParameter = pendingAuthorizationRequest.getAuthorizationParameters().get(
				AuthorizationRequest.REDIRECT_URI);

		if ((redirectUri != null || redirectUriApprovalParameter != null)
				&& !pendingAuthorizationRequest.getRedirectUri().equals(redirectUri)) {
			throw new RedirectMismatchException("Redirect URI mismatch.");
		}

		String pendingClientId = pendingAuthorizationRequest.getClientId();
		String clientId = authorizationRequest.getClientId();
		if (clientId != null && !clientId.equals(pendingClientId)) {
			// just a sanity check.
			throw new InvalidClientException("Client ID mismatch");
		}

		// Secret is not required in the authorization request, so it won't be available
		// in the pendingAuthorizationRequest. We do want to check that a secret is provided
		// in the token request, but that happens elsewhere.

		Map<String, String> combinedParameters = new HashMap<String, String>(storedAuth.getAuthenticationRequest()
				.getAuthorizationParameters());
		// Combine the parameters adding the new ones last so they override if there are any clashes
		combinedParameters.putAll(parameters);
		// Similarly scopes are not required in the token request, so we don't make a comparison here, just
		// enforce validity through the AuthorizationRequestFactory.
		DefaultAuthorizationRequest outgoingRequest = new DefaultAuthorizationRequest(pendingAuthorizationRequest);
		outgoingRequest.setAuthorizationParameters(combinedParameters);

		Authentication userAuth = storedAuth.getUserAuthentication();
		return new OAuth2Authentication(outgoingRequest, userAuth);

	}

之后剩余的就是生成token的流程了。源码里面都写的很清晰。自己记住的就几点：

token的value是一个UUID值，而存储进入DB的是对这个UUID值处理之后的值(类似MD5)，所以想直接根据返回给client的value直接查询DB是有点麻烦的==，=
貌似authorization id也是类似的生成逻辑....
在现在项目oauth相关的表存储中，很多都用到了序列化将整个对象存储为blob类型的字段，还涉及到反序列化
单步调试的过程中，发现，一次申请access token的请求中，多次调用了根据clientId查询DB的情况，所以在实际使用中，考虑使用缓存。目前我们自己对查询client和查询user信息加了缓存，token的缓存略麻烦，暂时没加。

其他待续...

【OAuth2.0】Spring Security OAuth2.0对于OAuth2.0协议中四种授权类型的实现

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