From ef78427b34be488478500fc744a588a88d439465 Mon Sep 17 00:00:00 2001
From: Nicklas Wallgren <nicklas.wallgren@gmail.com>
Date: Thu, 28 Dec 2023 08:51:58 +0100
Subject: [PATCH] Fix NPE in ApacheHttpClientApiAdapter#getHostName.

---
 .../AbstractApacheHttpClientAdvice.java       |  5 +++--
 .../common/ApacheHttpClientApiAdapter.java    |  4 +++-
 .../helper/ApacheHttpClient4ApiAdapter.java   |  2 +-
 .../v5/ApacheHttpClient5Instrumentation.java  |  2 +-
 .../helper/ApacheHttpClient5ApiAdapter.java   | 22 +++++++++++++++++--
 5 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/apm-agent-plugins/apm-apache-httpclient/apm-apache-httpclient-common/src/main/java/co/elastic/apm/agent/httpclient/common/AbstractApacheHttpClientAdvice.java b/apm-agent-plugins/apm-apache-httpclient/apm-apache-httpclient-common/src/main/java/co/elastic/apm/agent/httpclient/common/AbstractApacheHttpClientAdvice.java
index fce3555a6d9..aa6c60f04d6 100644
--- a/apm-agent-plugins/apm-apache-httpclient/apm-apache-httpclient-common/src/main/java/co/elastic/apm/agent/httpclient/common/AbstractApacheHttpClientAdvice.java
+++ b/apm-agent-plugins/apm-apache-httpclient/apm-apache-httpclient-common/src/main/java/co/elastic/apm/agent/httpclient/common/AbstractApacheHttpClientAdvice.java
@@ -27,6 +27,7 @@
 import co.elastic.apm.agent.tracer.dispatch.TextHeaderGetter;
 import co.elastic.apm.agent.tracer.dispatch.TextHeaderSetter;
 
+import javax.annotation.Nullable;
 import java.net.URISyntaxException;
 
 public abstract class AbstractApacheHttpClientAdvice {
@@ -36,12 +37,12 @@ public abstract class AbstractApacheHttpClientAdvice {
             TextHeaderGetter<REQUEST>> Object startSpan(final Tracer tracer,
                                                         final ApacheHttpClientApiAdapter<REQUEST, WRAPPER, HTTPHOST, RESPONSE> adapter,
                                                         final WRAPPER request,
-                                                        final HTTPHOST httpHost,
+                                                        @Nullable final HTTPHOST httpHost,
                                                         final HeaderAccessor headerAccessor) throws URISyntaxException {
         ElasticContext<?> elasticContext = tracer.currentContext();
         Span<?> span = null;
         if (elasticContext.getSpan() != null) {
-            span = HttpClientHelper.startHttpClientSpan(elasticContext, adapter.getMethod(request), adapter.getUri(request), adapter.getHostName(httpHost));
+            span = HttpClientHelper.startHttpClientSpan(elasticContext, adapter.getMethod(request), adapter.getUri(request), adapter.getHostName(httpHost, request));
             if (span != null) {
                 span.activate();
             }
diff --git a/apm-agent-plugins/apm-apache-httpclient/apm-apache-httpclient-common/src/main/java/co/elastic/apm/agent/httpclient/common/ApacheHttpClientApiAdapter.java b/apm-agent-plugins/apm-apache-httpclient/apm-apache-httpclient-common/src/main/java/co/elastic/apm/agent/httpclient/common/ApacheHttpClientApiAdapter.java
index 4363cc3e175..a3834035cd9 100644
--- a/apm-agent-plugins/apm-apache-httpclient/apm-apache-httpclient-common/src/main/java/co/elastic/apm/agent/httpclient/common/ApacheHttpClientApiAdapter.java
+++ b/apm-agent-plugins/apm-apache-httpclient/apm-apache-httpclient-common/src/main/java/co/elastic/apm/agent/httpclient/common/ApacheHttpClientApiAdapter.java
@@ -19,6 +19,7 @@
 package co.elastic.apm.agent.httpclient.common;
 
 
+import javax.annotation.Nullable;
 import java.net.URI;
 import java.net.URISyntaxException;
 
@@ -27,7 +28,8 @@ public interface ApacheHttpClientApiAdapter<REQUEST, WRAPPER extends REQUEST, HT
 
     URI getUri(WRAPPER request) throws URISyntaxException;
 
-    CharSequence getHostName(HTTPHOST httpHost);
+    @Nullable
+    CharSequence getHostName(@Nullable HTTPHOST httpHost, WRAPPER request);
 
     int getResponseCode(RESPONSE response);
 
diff --git a/apm-agent-plugins/apm-apache-httpclient/apm-apache-httpclient4-plugin/src/main/java/co/elastic/apm/agent/httpclient/v4/helper/ApacheHttpClient4ApiAdapter.java b/apm-agent-plugins/apm-apache-httpclient/apm-apache-httpclient4-plugin/src/main/java/co/elastic/apm/agent/httpclient/v4/helper/ApacheHttpClient4ApiAdapter.java
index 0b3c0ad4a4b..13bf22af4e1 100644
--- a/apm-agent-plugins/apm-apache-httpclient/apm-apache-httpclient4-plugin/src/main/java/co/elastic/apm/agent/httpclient/v4/helper/ApacheHttpClient4ApiAdapter.java
+++ b/apm-agent-plugins/apm-apache-httpclient/apm-apache-httpclient4-plugin/src/main/java/co/elastic/apm/agent/httpclient/v4/helper/ApacheHttpClient4ApiAdapter.java
@@ -50,7 +50,7 @@ public URI getUri(HttpRequestWrapper request) {
     }
 
     @Override
-    public CharSequence getHostName(HttpHost httpHost) {
+    public CharSequence getHostName(HttpHost httpHost, HttpRequestWrapper request) {
         return httpHost.getHostName();
     }
 
diff --git a/apm-agent-plugins/apm-apache-httpclient/apm-apache-httpclient5-plugin/src/main/java/co/elastic/apm/agent/httpclient/v5/ApacheHttpClient5Instrumentation.java b/apm-agent-plugins/apm-apache-httpclient/apm-apache-httpclient5-plugin/src/main/java/co/elastic/apm/agent/httpclient/v5/ApacheHttpClient5Instrumentation.java
index 0f03d73ab82..5170a37f3ee 100644
--- a/apm-agent-plugins/apm-apache-httpclient/apm-apache-httpclient5-plugin/src/main/java/co/elastic/apm/agent/httpclient/v5/ApacheHttpClient5Instrumentation.java
+++ b/apm-agent-plugins/apm-apache-httpclient/apm-apache-httpclient5-plugin/src/main/java/co/elastic/apm/agent/httpclient/v5/ApacheHttpClient5Instrumentation.java
@@ -48,7 +48,7 @@ public static class ApacheHttpClient5Advice extends AbstractApacheHttpClientAdvi
 
         @Nullable
         @Advice.OnMethodEnter(suppress = Throwable.class, inline = false)
-        public static Object onBeforeExecute(@Advice.Argument(0) HttpHost httpHost,
+        public static Object onBeforeExecute(@Advice.Argument(0) @Nullable HttpHost httpHost,
                                              @Advice.Argument(1) ClassicHttpRequest request) throws URISyntaxException {
             return startSpan(tracer, adapter, request, httpHost, RequestHeaderAccessor.INSTANCE);
         }
diff --git a/apm-agent-plugins/apm-apache-httpclient/apm-apache-httpclient5-plugin/src/main/java/co/elastic/apm/agent/httpclient/v5/helper/ApacheHttpClient5ApiAdapter.java b/apm-agent-plugins/apm-apache-httpclient/apm-apache-httpclient5-plugin/src/main/java/co/elastic/apm/agent/httpclient/v5/helper/ApacheHttpClient5ApiAdapter.java
index 2bff7de9911..53dc4d7f5ba 100644
--- a/apm-agent-plugins/apm-apache-httpclient/apm-apache-httpclient5-plugin/src/main/java/co/elastic/apm/agent/httpclient/v5/helper/ApacheHttpClient5ApiAdapter.java
+++ b/apm-agent-plugins/apm-apache-httpclient/apm-apache-httpclient5-plugin/src/main/java/co/elastic/apm/agent/httpclient/v5/helper/ApacheHttpClient5ApiAdapter.java
@@ -19,18 +19,25 @@
 package co.elastic.apm.agent.httpclient.v5.helper;
 
 import co.elastic.apm.agent.httpclient.common.ApacheHttpClientApiAdapter;
+import co.elastic.apm.agent.sdk.logging.Logger;
+import co.elastic.apm.agent.sdk.logging.LoggerFactory;
 import org.apache.hc.client5.http.CircularRedirectException;
 import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse;
+import org.apache.hc.client5.http.routing.RoutingSupport;
 import org.apache.hc.core5.http.ClassicHttpRequest;
+import org.apache.hc.core5.http.HttpException;
 import org.apache.hc.core5.http.HttpHost;
 import org.apache.hc.core5.http.HttpRequest;
 
+import javax.annotation.Nullable;
 import java.net.URI;
 import java.net.URISyntaxException;
 
 public class ApacheHttpClient5ApiAdapter implements ApacheHttpClientApiAdapter<HttpRequest, ClassicHttpRequest, HttpHost, CloseableHttpResponse> {
     private static final ApacheHttpClient5ApiAdapter INSTANCE = new ApacheHttpClient5ApiAdapter();
 
+    private static final Logger logger = LoggerFactory.getLogger(ApacheHttpClient5ApiAdapter.class);
+
     private ApacheHttpClient5ApiAdapter() {
     }
 
@@ -49,8 +56,19 @@ public URI getUri(ClassicHttpRequest request) throws URISyntaxException {
     }
 
     @Override
-    public CharSequence getHostName(HttpHost httpHost) {
-        return httpHost.getHostName();
+    public CharSequence getHostName(@Nullable HttpHost httpHost, ClassicHttpRequest request) {
+        if (httpHost != null) {
+            return httpHost.getHostName();
+        }
+
+        try {
+            return RoutingSupport.determineHost(request)
+                .getHostName();
+        } catch (HttpException e) {
+            logger.error("Exception while determining HttpHost", e);
+
+            return null;
+        }
     }
 
     @Override