mobile: Fix c-ares initialization on Android (envoyproxy#35970)

This PR fixes an issue with c-ares where the DNS servers are empty due to a missing initialization by calling [ares_library_init_android](https://c-ares.org/docs/ares_library_init_android.html). Risk Level: low Testing: test app Docs Changes: n/a Release Notes: n/a Platform Specific Features: mobile (Android) --------- Signed-off-by: Fredy Wijaya <[email protected]>
daixiang0 · Sep 4, 2024 · 7b67799 · 7b67799
1 parent c198038
commit 7b67799
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diff --git a/mobile/library/java/io/envoyproxy/envoymobile/engine/AndroidEngineImpl.java b/mobile/library/java/io/envoyproxy/envoymobile/engine/AndroidEngineImpl.java
@@ -1,6 +1,8 @@
 package io.envoyproxy.envoymobile.engine;
 
 import android.content.Context;
+import android.net.ConnectivityManager;
+
 import io.envoyproxy.envoymobile.engine.types.EnvoyEventTracker;
 import io.envoyproxy.envoymobile.engine.types.EnvoyHTTPCallbacks;
 import io.envoyproxy.envoymobile.engine.types.EnvoyLogger;
@@ -15,13 +17,15 @@
 /* Android-specific implementation of the `EnvoyEngine` interface. */
 public class AndroidEngineImpl implements EnvoyEngine {
   private final EnvoyEngine envoyEngine;
+  private final Context context;
 
   /**
    * @param runningCallback Called when the engine finishes its async startup and begins running.
    */
   public AndroidEngineImpl(Context context, EnvoyOnEngineRunning runningCallback,
                            EnvoyLogger logger, EnvoyEventTracker eventTracker,
                            Boolean enableProxying) {
+    this.context = context;
     this.envoyEngine = new EnvoyEngineImpl(runningCallback, logger, eventTracker);
     if (ContextUtils.getApplicationContext() == null) {
       ContextUtils.initApplicationContext(context.getApplicationContext());
@@ -44,6 +48,10 @@ public void performRegistration(EnvoyConfiguration envoyConfiguration) {
 
   @Override
   public EnvoyStatus runWithConfig(EnvoyConfiguration envoyConfiguration, String logLevel) {
+    if (envoyConfiguration.useCares) {
+      JniLibrary.initCares(
+          (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE));
+    }
     return envoyEngine.runWithConfig(envoyConfiguration, logLevel);
   }
 

diff --git a/mobile/library/java/io/envoyproxy/envoymobile/engine/JniLibrary.java b/mobile/library/java/io/envoyproxy/envoymobile/engine/JniLibrary.java
@@ -1,5 +1,7 @@
 package io.envoyproxy.envoymobile.engine;
 
+import android.net.ConnectivityManager;
+
 import io.envoyproxy.envoymobile.engine.types.EnvoyEventTracker;
 import io.envoyproxy.envoymobile.engine.types.EnvoyHTTPCallbacks;
 import io.envoyproxy.envoymobile.engine.types.EnvoyLogger;
@@ -305,4 +307,11 @@ public static native long createBootstrap(
       long maxConnectionsPerHost, long streamIdleTimeoutSeconds, long perTryIdleTimeoutSeconds,
       String appVersion, String appId, boolean trustChainVerification, byte[][] filterChain,
       boolean enablePlatformCertificatesValidation, String upstreamTlsSni, byte[][] runtimeGuards);
+
+  /**
+   * Initializes c-ares.
+   * See <a
+   * href="https://c-ares.org/docs/ares_library_init_android.html">ares_library_init_android</a>.
+   */
+  public static native void initCares(ConnectivityManager connectivityManager);
 }
diff --git a/mobile/library/jni/jni_impl.cc b/mobile/library/jni/jni_impl.cc
@@ -3,6 +3,7 @@
 
 #include "source/common/protobuf/protobuf.h"
 
+#include "ares.h"
 #include "library/cc/engine_builder.h"
 #include "library/common/api/c_types.h"
 #include "library/common/bridge/utility.h"
@@ -201,6 +202,19 @@ extern "C" JNIEXPORT void JNICALL Java_io_envoyproxy_envoymobile_engine_JniLibra
   delete internal_engine;
 }
 
+extern "C" JNIEXPORT void JNICALL Java_io_envoyproxy_envoymobile_engine_JniLibrary_initCares(
+    JNIEnv* env, jclass, jobject connectivity_manager) {
+#if defined(__ANDROID_API__)
+  Envoy::JNI::JniHelper jni_helper(env);
+  ares_library_init_jvm(jni_helper.getJavaVm());
+  ares_library_init_android(connectivity_manager);
+#else
+  // For suppressing unused parameters.
+  (void)env;
+  (void)connectivity_manager;
+#endif
+}
+
 extern "C" JNIEXPORT jint JNICALL Java_io_envoyproxy_envoymobile_engine_JniLibrary_recordCounterInc(
     JNIEnv* env,
     jclass, // class

diff --git a/mobile/test/kotlin/apps/experimental/MainActivity.kt b/mobile/test/kotlin/apps/experimental/MainActivity.kt
@@ -84,6 +84,7 @@ class MainActivity : Activity() {
             Log.d(TAG, "Event emitted: ${entry.key}, ${entry.value}")
           }
         })
+        .useCares(true)
         .build()
 
     recyclerView = findViewById<RecyclerView>(R.id.recycler_view)!!