1 files changed, 88 insertions, 0 deletions
diff --git a/app/src/main/java/org/onap/portalng/preferences/util/IdTokenExchange.java b/app/src/main/java/org/onap/portalng/preferences/util/IdTokenExchange.java
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+++ b/app/src/main/java/org/onap/portalng/preferences/util/IdTokenExchange.java
@@ -0,0 +1,88 @@
+/*
+ *
+ * Copyright (c) 2022. Deutsche Telekom AG
+ *
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ *
+ */
+
+package org.onap.portalng.preferences.util;
+
+import com.nimbusds.jwt.JWTClaimsSet;
+import com.nimbusds.jwt.JWTParser;
+
+import java.text.ParseException;
+
+import org.springframework.web.server.ServerWebExchange;
+import reactor.core.publisher.Mono;
+
+/**
+ * Represents a function that handles the <a href="https://jwt.io/introduction">JWT</a> identity token.
+ * Use this to check if the incoming requests are authorized to call the given endpoint
+ */
+
+public final class IdTokenExchange {
+
+  public static final String X_AUTH_IDENTITY_HEADER = "X-Auth-Identity";
+  public static final String JWT_CLAIM_USERID = "sub";
+
+  private IdTokenExchange(){
+
+  }
+
+  /**
+   * Extract the identity header from the given {@link ServerWebExchange}.
+   * @param exchange the ServerWebExchange that contains information about the incoming request
+   * @return the identity header in the form of <code>Bearer {@literal <Token>}<c/ode>
+   */
+  private static Mono<String> extractIdentityHeader(ServerWebExchange exchange) {
+    return Mono.just(exchange.getRequest().getHeaders().getOrEmpty(X_AUTH_IDENTITY_HEADER))
+        .map(headers -> headers.get(0))
+        .onErrorResume(Exception.class, ex -> Mono.error(ex));
+  }
+
+    /**
+   * Extract the identity token from the given {@link ServerWebExchange}.
+   * @see <a href="https://openid.net/specs/openid-connect-core-1_0.html#IDToken">OpenId Connect ID Token</a>
+   * @param exchange the ServerWebExchange that contains information about the incoming request
+   * @return the identity token that contains user roles
+   */
+  private static Mono<String> extractIdToken(ServerWebExchange exchange) {
+    return extractIdentityHeader(exchange)
+        .map(identityHeader -> identityHeader.replace("Bearer ", ""));
+  }
+
+  /**
+   * Extract the <code>userId</code> from the given {@link ServerWebExchange}
+   * @param exchange the ServerWebExchange that contains information about the incoming request
+   * @return the id of the user
+   */
+  public static Mono<String> extractUserId(ServerWebExchange exchange) {
+    return extractIdToken(exchange)
+        .flatMap(idToken -> extractUserClaim(idToken));
+  }
+
+  private static Mono<String> extractUserClaim(String idToken) {
+    JWTClaimsSet jwtClaimSet;
+	try {
+		jwtClaimSet = JWTParser.parse(idToken).getJWTClaimsSet();
+	} catch (ParseException e) {
+		return Mono.error(e);
+	}
+    return Mono.just(String.class.cast(jwtClaimSet.getClaim(JWT_CLAIM_USERID)));
+  }
+}
+