Fix NullPointerException with empty X-Forwarded-For header

See gh-16046

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/web/trace/reactive/ServerWebExchangeTraceableRequest.java

 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 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.
@@ -16,6 +16,8 @@
 
 package org.springframework.boot.actuate.web.trace.reactive;
 
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
 import java.net.URI;
 import java.util.LinkedHashMap;
 import java.util.List;
@@ -45,8 +47,7 @@ class ServerWebExchangeTraceableRequest implements TraceableRequest {
 		this.method = request.getMethodValue();
 		this.headers = request.getHeaders();
 		this.uri = request.getURI();
-		this.remoteAddress = (request.getRemoteAddress() != null)
-				? request.getRemoteAddress().getAddress().toString() : null;
+		this.remoteAddress = getRemoteAddress(request);
 	}
 
 	@Override
@@ -69,4 +70,10 @@ class ServerWebExchangeTraceableRequest implements TraceableRequest {
 		return this.remoteAddress;
 	}
 
+	private static String getRemoteAddress(ServerHttpRequest request) {
+		InetSocketAddress remoteAddress = request.getRemoteAddress();
+		InetAddress address = (remoteAddress != null) ? remoteAddress.getAddress() : null;
+		return (address != null) ? address.toString() : null;
+	}
+
 }

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/web/trace/reactive/ServerWebExchangeTraceableRequestTests.java

+/*
+ * Copyright 2012-2019 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.actuate.web.trace.reactive;
+
+import java.net.InetSocketAddress;
+import java.net.URI;
+import java.util.Collections;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.server.reactive.ServerHttpRequest;
+import org.springframework.web.server.ServerWebExchange;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.entry;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Tests for {@link ServerWebExchangeTraceableRequest}.
+ *
+ * @author Dmytro Nosan
+ */
+public class ServerWebExchangeTraceableRequestTests {
+
+	private ServerWebExchange exchange;
+
+	private ServerHttpRequest request;
+
+	@Before
+	public void setUp() {
+		this.exchange = mock(ServerWebExchange.class);
+		this.request = mock(ServerHttpRequest.class);
+		doReturn(this.request).when(this.exchange).getRequest();
+	}
+
+	@Test
+	public void getMethod() {
+		String method = "POST";
+		doReturn(method).when(this.request).getMethodValue();
+		ServerWebExchangeTraceableRequest traceableRequest = new ServerWebExchangeTraceableRequest(
+				this.exchange);
+		assertThat(traceableRequest.getMethod()).isSameAs(method);
+	}
+
+	@Test
+	public void getUri() {
+		URI uri = URI.create("http://localhost:8080/");
+		doReturn(uri).when(this.request).getURI();
+		ServerWebExchangeTraceableRequest traceableRequest = new ServerWebExchangeTraceableRequest(
+				this.exchange);
+		assertThat(traceableRequest.getUri()).isSameAs(uri);
+	}
+
+	@Test
+	public void getHeaders() {
+		HttpHeaders httpHeaders = new HttpHeaders();
+		httpHeaders.add("name", "value");
+		doReturn(httpHeaders).when(this.request).getHeaders();
+		ServerWebExchangeTraceableRequest traceableRequest = new ServerWebExchangeTraceableRequest(
+				this.exchange);
+		assertThat(traceableRequest.getHeaders())
+				.containsOnly(entry("name", Collections.singletonList("value")));
+	}
+
+	@Test
+	public void getUnresolvedRemoteAddress() {
+		InetSocketAddress socketAddress = InetSocketAddress.createUnresolved("", 0);
+		doReturn(socketAddress).when(this.request).getRemoteAddress();
+		ServerWebExchangeTraceableRequest traceableRequest = new ServerWebExchangeTraceableRequest(
+				this.exchange);
+		assertThat(traceableRequest.getRemoteAddress()).isNull();
+
+	}
+
+	@Test
+	public void getRemoteAddress() {
+		InetSocketAddress socketAddress = new InetSocketAddress(0);
+		doReturn(socketAddress).when(this.request).getRemoteAddress();
+		ServerWebExchangeTraceableRequest traceableRequest = new ServerWebExchangeTraceableRequest(
+				this.exchange);
+		assertThat(traceableRequest.getRemoteAddress())
+				.isEqualTo(socketAddress.getAddress().toString());
+	}
+
+}