Request user info when AS returns no scopes

Closes spring-projectsgh-12144

oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/oidc/userinfo/OidcUserService.java

@@ -173,8 +173,15 @@ private boolean shouldRetrieveUserInfo(OidcUserRequest userRequest) {
 				.equals(userRequest.getClientRegistration().getAuthorizationGrantType())) {
 			// Return true if there is at least one match between the authorized scope(s)
 			// and accessible scope(s)
+			// As per spec, in Section 5.1 Successful Access Token Response
+			// https://www.rfc-editor.org/rfc/rfc6749#section-5.1
+			// If AccessTokenResponse.scope is empty, then default to the scope
+			// originally requested by the client in the Token Request
+			// @formatter:off
 			return this.accessibleScopes.isEmpty()
+					|| CollectionUtils.isEmpty(userRequest.getAccessToken().getScopes())
 					|| CollectionUtils.containsAny(userRequest.getAccessToken().getScopes(), this.accessibleScopes);
+			// @formatter:on
 		}
 		return false;
 	}

oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/oidc/userinfo/OidcUserServiceTests.java

@@ -458,14 +458,36 @@ public void loadUserWhenTokenContainsScopesThenIndividualScopeAuthorities() {
 	@Test
 	public void loadUserWhenTokenDoesNotContainScopesThenNoScopeAuthorities() {
 		OidcUserService userService = new OidcUserService();
-		OidcUserRequest request = new OidcUserRequest(TestClientRegistrations.clientRegistration().build(),
-				TestOAuth2AccessTokens.noScopes(), TestOidcIdTokens.idToken().build());
+		OidcUserRequest request = new OidcUserRequest(this.clientRegistrationBuilder.build(),
+				TestOAuth2AccessTokens.noScopes(), this.idToken);
 		OidcUser user = userService.loadUser(request);
 		assertThat(user.getAuthorities()).hasSize(1);
 		Iterator<? extends GrantedAuthority> authorities = user.getAuthorities().iterator();
 		assertThat(authorities.next()).isInstanceOf(OidcUserAuthority.class);
 	}
 
+	@Test
+	public void loadUserWhenTokenDoesNotContainScopesAndUserInfoUriThenUserInfoRequested() {
+		// @formatter:off
+		String userInfoResponse = "{\n"
+				+ "   \"sub\": \"subject1\",\n"
+				+ "   \"name\": \"first last\",\n"
+				+ "   \"given_name\": \"first\",\n"
+				+ "   \"family_name\": \"last\",\n"
+				+ "   \"preferred_username\": \"user1\",\n"
+				+ "   \"email\": \"[email protected]\"\n"
+				+ "}\n";
+		// @formatter:on
+		this.server.enqueue(jsonResponse(userInfoResponse));
+		String userInfoUri = this.server.url("/user").toString();
+		ClientRegistration clientRegistration = this.clientRegistrationBuilder.userInfoUri(userInfoUri).build();
+		OidcUserService userService = new OidcUserService();
+		OidcUserRequest request = new OidcUserRequest(clientRegistration, TestOAuth2AccessTokens.noScopes(),
+				this.idToken);
+		OidcUser user = userService.loadUser(request);
+		assertThat(user.getUserInfo()).isNotNull();
+	}
+
 	private MockResponse jsonResponse(String json) {
 		// @formatter:off
 		return new MockResponse()

oauth2/oauth2-core/src/test/java/org/springframework/security/oauth2/core/endpoint/TestOAuth2AccessTokenResponses.java

@@ -16,10 +16,12 @@
 
 package org.springframework.security.oauth2.core.endpoint;
 
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 
 import org.springframework.security.oauth2.core.OAuth2AccessToken;
+import org.springframework.security.oauth2.core.oidc.OidcScopes;
 import org.springframework.security.oauth2.core.oidc.endpoint.OidcParameterNames;
 
 /**
@@ -42,7 +44,8 @@ public static OAuth2AccessTokenResponse.Builder accessTokenResponse() {
 	public static OAuth2AccessTokenResponse.Builder oidcAccessTokenResponse() {
 		Map<String, Object> additionalParameters = new HashMap<>();
 		additionalParameters.put(OidcParameterNames.ID_TOKEN, "id-token");
-		return accessTokenResponse().additionalParameters(additionalParameters);
+		return accessTokenResponse().scopes(Collections.singleton(OidcScopes.OPENID))
+				.additionalParameters(additionalParameters);
 	}
 
 }