Add Reactor Netty version of CORS HTTP server example

reactor-netty-examples/src/main/java/reactor/netty/examples/http/cors/HttpCorsServer.java

@@ -0,0 +1,92 @@
+/*
+ * Copyright (c) 2025 VMware, Inc. or its affiliates, All Rights Reserved.
+ *
+ * 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
+ *
+ *   https://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 reactor.netty.examples.http.cors;
+
+import io.netty.channel.Channel;
+import io.netty.handler.codec.http.HttpResponseStatus;
+import io.netty.handler.codec.http.cors.CorsConfig;
+import io.netty.handler.codec.http.cors.CorsConfigBuilder;
+import io.netty.handler.codec.http.cors.CorsHandler;
+import io.netty.handler.ssl.util.SelfSignedCertificate;
+import java.net.SocketAddress;
+import java.security.cert.CertificateException;
+import reactor.netty.ConnectionObserver;
+import reactor.netty.NettyOutbound;
+import reactor.netty.NettyPipeline;
+import reactor.netty.http.Http11SslContextSpec;
+import reactor.netty.http.Http2SslContextSpec;
+import reactor.netty.http.HttpProtocol;
+import reactor.netty.http.server.HttpServer;
+import reactor.netty.http.server.HttpServerRequest;
+import reactor.netty.http.server.HttpServerResponse;
+
+/**
+ * An HTTP server that handles CORS (Cross-Origin Resource Sharing) requests.
+ *
+ * @author Jack Cheng
+ **/
+public class HttpCorsServer {
+
+	static final boolean SECURE = System.getProperty("secure") != null;
+	static final int PORT = Integer.parseInt(System.getProperty("port", SECURE ? "8443" : "8080"));
+	static final boolean WIRETAP = System.getProperty("wiretap") != null;
+	static final boolean COMPRESS = System.getProperty("compress") != null;
+	static final boolean HTTP2 = System.getProperty("http2") != null;
+
+	public static void main(String... args) throws CertificateException {
+
+
+		HttpServer server =
+				HttpServer.create()
+						.port(PORT)
+						.wiretap(WIRETAP)
+						.compress(COMPRESS)
+						.doOnChannelInit(HttpCorsServer::addCorsHandler)
+						.route(routes -> routes.route(r -> true,
+								HttpCorsServer::okResponse));
+
+		if (SECURE) {
+
+			SelfSignedCertificate ssc = new SelfSignedCertificate("localhost");
+			if (HTTP2) {
+				server = server.secure(spec -> spec.sslContext(Http2SslContextSpec.forServer(ssc.certificate(), ssc.privateKey())));
+			}
+			else {
+				server = server.secure(spec -> spec.sslContext(Http11SslContextSpec.forServer(ssc.certificate(), ssc.privateKey())));
+			}
+		}
+
+		if (HTTP2) {
+			server = server.protocol(HttpProtocol.H2);
+		}
+
+		server.bindNow()
+				.onDispose()
+				.block();
+	}
+
+	private static NettyOutbound okResponse(HttpServerRequest request, HttpServerResponse response) {
+		response.status(HttpResponseStatus.OK);
+		response.header("custom-response-header", "Some value");
+		return response;
+	}
+
+
+	private static void addCorsHandler(ConnectionObserver observer, Channel channel, SocketAddress remoteAddress) {
+		CorsConfig corsConfig = CorsConfigBuilder.forOrigin("example.com").allowNullOrigin().allowCredentials().allowedRequestHeaders("custom-request-header").build();
+		channel.pipeline().addAfter(NettyPipeline.HttpCodec, "Cors", new CorsHandler(corsConfig));
+	}
+}