Add OAuth PrincipalExtractor strategy interface

Update `UserInfoTokenServices` to use a PrincipalExtractor interface
to extract the principal.

Fixes gh-5186

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/oauth2/resource/FixedPrincipalExtractor.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2012-2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.autoconfigure.security.oauth2.resource;
+
+import java.util.Map;
+
+/**
+ * Default implementation of {@link PrincipalExtractor}. Extracts the principal from the
+ * map with well known keys.
+ *
+ * @author Phillip Webb
+ * @since 1.4.0
+ */
+public class FixedPrincipalExtractor implements PrincipalExtractor {
+
+	private static final String[] PRINCIPAL_KEYS = new String[] { "user", "username",
+			"userid", "user_id", "login", "id", "name" };
+
+	@Override
+	public Object extractPrincipal(Map<String, Object> map) {
+		for (String key : PRINCIPAL_KEYS) {
+			if (map.containsKey(key)) {
+				return map.get(key);
+			}
+		}
+		return null;
+	}
+
+}

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/oauth2/resource/PrincipalExtractor.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2012-2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.autoconfigure.security.oauth2.resource;
+
+import java.util.Map;
+
+/**
+ * Strategy used by {@link UserInfoTokenServices} to extract the principal from the
+ * resource server's response.
+ *
+ * @author Phillip Webb
+ * @since 1.4.0
+ */
+public interface PrincipalExtractor {
+
+	/**
+	 * Extract the principal that should be used for the token.
+	 * @param map the source map
+	 * @return the extracted principal or {@code null}
+	 */
+	Object extractPrincipal(Map<String, Object> map);
+
+}

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/oauth2/resource/ResourceServerTokenServicesConfiguration.java

@@ -129,14 +129,18 @@ public class ResourceServerTokenServicesConfiguration {
 
 			private final AuthoritiesExtractor authoritiesExtractor;
 
+			private final PrincipalExtractor principalExtractor;
+
 			public SocialTokenServicesConfiguration(ResourceServerProperties sso,
 					ObjectProvider<OAuth2ConnectionFactory<?>> connectionFactoryProvider,
 					UserInfoRestTemplateFactory restTemplateFactory,
-					ObjectProvider<AuthoritiesExtractor> authoritiesExtractorProvider) {
+					ObjectProvider<AuthoritiesExtractor> authoritiesExtractor,
+					ObjectProvider<PrincipalExtractor> principalExtractor) {
 				this.sso = sso;
 				this.connectionFactory = connectionFactoryProvider.getIfAvailable();
 				this.restTemplate = restTemplateFactory.getUserInfoRestTemplate();
-				this.authoritiesExtractor = authoritiesExtractorProvider.getIfAvailable();
+				this.authoritiesExtractor = authoritiesExtractor.getIfAvailable();
+				this.principalExtractor = principalExtractor.getIfAvailable();
 			}
 
 			@Bean
@@ -158,6 +162,9 @@ public class ResourceServerTokenServicesConfiguration {
 				if (this.authoritiesExtractor != null) {
 					services.setAuthoritiesExtractor(this.authoritiesExtractor);
 				}
+				if (this.principalExtractor != null) {
+					services.setPrincipalExtractor(this.principalExtractor);
+				}
 				return services;
 			}
 
@@ -174,12 +181,16 @@ public class ResourceServerTokenServicesConfiguration {
 
 			private final AuthoritiesExtractor authoritiesExtractor;
 
+			private final PrincipalExtractor principalExtractor;
+
 			public UserInfoTokenServicesConfiguration(ResourceServerProperties sso,
 					UserInfoRestTemplateFactory restTemplateFactory,
-					ObjectProvider<AuthoritiesExtractor> authoritiesExtractorProvider) {
+					ObjectProvider<AuthoritiesExtractor> authoritiesExtractor,
+					ObjectProvider<PrincipalExtractor> principalExtractor) {
 				this.sso = sso;
 				this.restTemplate = restTemplateFactory.getUserInfoRestTemplate();
-				this.authoritiesExtractor = authoritiesExtractorProvider.getIfAvailable();
+				this.authoritiesExtractor = authoritiesExtractor.getIfAvailable();
+				this.principalExtractor = principalExtractor.getIfAvailable();
 			}
 
 			@Bean
@@ -192,6 +203,9 @@ public class ResourceServerTokenServicesConfiguration {
 				if (this.authoritiesExtractor != null) {
 					services.setAuthoritiesExtractor(this.authoritiesExtractor);
 				}
+				if (this.principalExtractor != null) {
+					services.setPrincipalExtractor(this.principalExtractor);
+				}
 				return services;
 			}
 

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/oauth2/resource/UserInfoTokenServices.java

@@ -35,6 +35,7 @@ import org.springframework.security.oauth2.common.exceptions.InvalidTokenExcepti
 import org.springframework.security.oauth2.provider.OAuth2Authentication;
 import org.springframework.security.oauth2.provider.OAuth2Request;
 import org.springframework.security.oauth2.provider.token.ResourceServerTokenServices;
+import org.springframework.util.Assert;
 
 /**
  * {@link ResourceServerTokenServices} that uses a user info REST service.
@@ -46,9 +47,6 @@ public class UserInfoTokenServices implements ResourceServerTokenServices {
 
 	protected final Log logger = LogFactory.getLog(getClass());
 
-	private static final String[] PRINCIPAL_KEYS = new String[] { "user", "username",
-			"userid", "user_id", "login", "id", "name" };
-
 	private final String userInfoEndpointUrl;
 
 	private final String clientId;
@@ -59,6 +57,8 @@ public class UserInfoTokenServices implements ResourceServerTokenServices {
 
 	private AuthoritiesExtractor authoritiesExtractor = new FixedAuthoritiesExtractor();
 
+	private PrincipalExtractor principalExtractor = new FixedPrincipalExtractor();
+
 	public UserInfoTokenServices(String userInfoEndpointUrl, String clientId) {
 		this.userInfoEndpointUrl = userInfoEndpointUrl;
 		this.clientId = clientId;
@@ -73,9 +73,15 @@ public class UserInfoTokenServices implements ResourceServerTokenServices {
 	}
 
 	public void setAuthoritiesExtractor(AuthoritiesExtractor authoritiesExtractor) {
+		Assert.notNull(authoritiesExtractor, "AuthoritiesExtractor must not be null");
 		this.authoritiesExtractor = authoritiesExtractor;
 	}
 
+	public void setPrincipalExtractor(PrincipalExtractor principalExtractor) {
+		Assert.notNull(principalExtractor, "PrincipalExtractor must not be null");
+		this.principalExtractor = principalExtractor;
+	}
+
 	@Override
 	public OAuth2Authentication loadAuthentication(String accessToken)
 			throws AuthenticationException, InvalidTokenException {
@@ -101,17 +107,13 @@ public class UserInfoTokenServices implements ResourceServerTokenServices {
 
 	/**
 	 * Return the principal that should be used for the token. The default implementation
-	 * looks for well know {@code user*} keys in the map.
+	 * delegates to the {@link PrincipalExtractor}.
 	 * @param map the source map
 	 * @return the principal or {@literal "unknown"}
 	 */
 	protected Object getPrincipal(Map<String, Object> map) {
-		for (String key : PRINCIPAL_KEYS) {
-			if (map.containsKey(key)) {
-				return map.get(key);
-			}
-		}
-		return "unknown";
+		Object principal = this.principalExtractor.extractPrincipal(map);
+		return (principal == null ? "unknown" : principal);
 	}
 
 	@Override

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/oauth2/resource/ResourceServerTokenServicesConfigurationTests.java

@@ -125,6 +125,19 @@ public class ResourceServerTokenServicesConfigurationTests {
 				.containsExactly(this.context.getBean(AuthoritiesExtractor.class));
 	}
 
+	@Test
+	public void userInfoWithPrincipal() {
+		EnvironmentTestUtils.addEnvironment(this.environment,
+				"security.oauth2.resource.userInfoUri:http://example.com");
+		this.context = new SpringApplicationBuilder(PrincipalConfiguration.class)
+				.environment(this.environment).web(false).run();
+		UserInfoTokenServices services = this.context
+				.getBean(UserInfoTokenServices.class);
+		assertThat(services).isNotNull();
+		assertThat(services).extracting("principalExtractor")
+				.containsExactly(this.context.getBean(PrincipalExtractor.class));
+	}
+
 	@Test
 	public void userInfoWithClient() {
 		EnvironmentTestUtils.addEnvironment(this.environment,
@@ -228,6 +241,23 @@ public class ResourceServerTokenServicesConfigurationTests {
 
 	}
 
+	@Configuration
+	protected static class PrincipalConfiguration extends ResourceConfiguration {
+
+		@Bean
+		PrincipalExtractor authoritiesExtractor() {
+			return new PrincipalExtractor() {
+
+				@Override
+				public Object extractPrincipal(Map<String, Object> map) {
+					return "boot";
+				}
+
+			};
+		}
+
+	}
+
 	@Import({ OAuth2RestOperationsConfiguration.class })
 	protected static class ResourceNoClientConfiguration extends ResourceConfiguration {