Add a ChannelArguments option for sepcify custom binder intent (#28723)

User can use
`grpc::ChannelArguments::SetString("grpc.binder.custom_android_intent_action_name", "...")`
to set custom binder intent.

examples/android/binder/java/io/grpc/binder/cpp/exampleclient/native.cc

@@ -43,12 +43,17 @@ Java_io_grpc_binder_cpp_exampleclient_ButtonPressHandler_native_1entry(
       jint result = env->GetJavaVM(&jvm);
       assert(result == 0);
     }
-    channel = grpc::experimental::CreateBinderChannel(
+    grpc::ChannelArguments ch_args;
+    // This is not required since "grpc.io.action.BIND" is already the default.
+    ch_args.SetString("grpc.binder.custom_android_intent_action_name",
+                      "grpc.io.action.BIND");
+    channel = grpc::experimental::CreateCustomBinderChannel(
         env, application, "io.grpc.binder.cpp.exampleserver",
         "io.grpc.binder.cpp.exampleserver.ExportedEndpointService",
         std::make_shared<
             grpc::experimental::binder::SameSignatureSecurityPolicy>(
-            jvm, application));
+            jvm, application),
+        ch_args);
     return env->NewStringUTF("Clicked 1 time, channel created");
   } else {
     auto stub = helloworld::Greeter::NewStub(channel);
@@ -60,6 +65,9 @@ Java_io_grpc_binder_cpp_exampleclient_ButtonPressHandler_native_1entry(
     if (status.ok()) {
       return env->NewStringUTF(response.message().c_str());
     }
-    return env->NewStringUTF("Clicked more than 1 time. Status not ok");
+    return env->NewStringUTF(
+        std::string("Clicked more than 1 time. Status not ok " +
+                    std::to_string(status.error_code()))
+            .c_str());
   }
 }

src/core/ext/transport/binder/client/channel_create.cc

@@ -55,6 +55,16 @@
 #include "src/core/lib/transport/transport.h"
 #include "src/cpp/client/create_channel_internal.h"
 
+namespace {
+// grpc.io.action.BIND is the standard action name for binding to binder
+// transport server.
+const char* kStandardActionName = "grpc.io.action.BIND";
+
+// grpc::ChannelArguments key for specifying custom action name.
+const char* kCustomIntentActionNameArgKey =
+    "grpc.binder.custom_android_intent_action_name";
+}  // namespace
+
 namespace grpc {
 namespace experimental {
 
@@ -79,9 +89,36 @@ std::shared_ptr<grpc::Channel> CreateCustomBinderChannel(
   GPR_ASSERT(jni_env_void != nullptr);
   GPR_ASSERT(security_policy != nullptr);
 
+  // Generate an unique connection ID that identifies this connection (Useful
+  // for mapping connection between Java and C++ code).
   std::string connection_id = grpc_binder::GetConnectionIdGenerator()->Generate(
       std::string(package_name), std::string(class_name));
 
+  grpc_channel_args channel_args_with_custom_action;
+  args.SetChannelArgs(&channel_args_with_custom_action);
+
+  // Check if user set an option to use non-standard action name to bind to
+  // server. At this moment this option is not intend for general production use
+  // and is mainly for stress testing purpose.
+  std::string action_name = kStandardActionName;
+  const grpc_arg* action_name_arg = grpc_channel_args_find(
+      &channel_args_with_custom_action, kCustomIntentActionNameArgKey);
+  if (action_name_arg != nullptr) {
+    // The option is set. Now check if it is a string.
+    char* action_name_arg_string = grpc_channel_arg_get_string(action_name_arg);
+    if (action_name_arg_string != nullptr) {
+      action_name = action_name_arg_string;
+    }
+  }
+  grpc_channel_args* channel_args;
+  {
+    // Passing the key down will cause gRPC internal error for unclear reason.
+    // Remove it here.
+    const char* to_remove[] = {kCustomIntentActionNameArgKey};
+    channel_args = grpc_channel_args_copy_and_remove(
+        &channel_args_with_custom_action, to_remove, 1);
+  }
+
   // After invoking this Java method, Java code will put endpoint binder into
   // `EndpointBinderPool` after the connection succeeds
   // TODO(mingcl): Consider if we want to delay the connection establishment
@@ -89,13 +126,11 @@ std::shared_ptr<grpc::Channel> CreateCustomBinderChannel(
   // see any benifits doing that.
   grpc_binder::TryEstablishConnection(static_cast<JNIEnv*>(jni_env_void),
                                       application, package_name, class_name,
-                                      connection_id);
+                                      action_name, connection_id);
 
   // Set server URI to a URI that contains connection id. The URI will be used
   // by subchannel connector to obtain correct endpoint binder from
   // `EndpointBinderPool`.
-  grpc_channel_args channel_args;
-  args.SetChannelArgs(&channel_args);
   grpc_channel_args* new_args;
   {
     grpc_arg server_uri_arg = grpc_channel_arg_string_create(
@@ -103,7 +138,7 @@ std::shared_ptr<grpc::Channel> CreateCustomBinderChannel(
         const_cast<char*>(("binder:" + connection_id).c_str()));
     const char* to_remove[] = {GRPC_ARG_SERVER_URI};
     new_args = grpc_channel_args_copy_and_add_and_remove(
-        &channel_args, to_remove, 1, &server_uri_arg, 1);
+        channel_args, to_remove, 1, &server_uri_arg, 1);
   }
 
   grpc_binder::GetSecurityPolicySetting()->Set(connection_id, security_policy);
@@ -114,6 +149,7 @@ std::shared_ptr<grpc::Channel> CreateCustomBinderChannel(
           std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>());
 
   grpc_channel_args_destroy(new_args);
+  grpc_channel_args_destroy(channel_args);
 
   return channel;
 }

src/core/ext/transport/binder/client/jni_utils.cc

@@ -65,11 +65,12 @@ jclass FindNativeConnectionHelper(
 
 void TryEstablishConnection(JNIEnv* env, jobject application,
                             absl::string_view pkg, absl::string_view cls,
+                            absl::string_view action_name,
                             absl::string_view conn_id) {
   std::string method = "tryEstablishConnection";
   std::string type =
       "(Landroid/content/Context;Ljava/lang/String;Ljava/lang/String;Ljava/"
-      "lang/String;)V";
+      "lang/String;Ljava/lang/String;)V";
 
   jclass cl = FindNativeConnectionHelper(env);
   if (cl == nullptr) {
@@ -84,6 +85,7 @@ void TryEstablishConnection(JNIEnv* env, jobject application,
   env->CallStaticVoidMethod(cl, mid, application,
                             env->NewStringUTF(std::string(pkg).c_str()),
                             env->NewStringUTF(std::string(cls).c_str()),
+                            env->NewStringUTF(std::string(action_name).c_str()),
                             env->NewStringUTF(std::string(conn_id).c_str()));
 }
 

src/core/ext/transport/binder/client/jni_utils.h

@@ -40,6 +40,7 @@ jclass FindNativeConnectionHelper(
 // Calls Java method NativeConnectionHelper.tryEstablishConnection
 void TryEstablishConnection(JNIEnv* env, jobject application,
                             absl::string_view pkg, absl::string_view cls,
+                            absl::string_view action_name,
                             absl::string_view conn_id);
 
 // Calls Java method NativeConnectionHelper.isSignatureMatch.

src/core/ext/transport/binder/java/io/grpc/binder/cpp/GrpcBinderConnection.java

@@ -60,9 +60,9 @@ public class GrpcBinderConnection implements ServiceConnection {
     Log.e(logTag, "Service has disconnected. mConnId = " + mConnId);
   }
 
-  public void tryConnect(String pkg, String cls) {
+  public void tryConnect(String pkg, String cls, String action_name) {
     synchronized (this) {
-      Intent intent = new Intent("grpc.io.action.BIND");
+      Intent intent = new Intent(action_name);
       ComponentName compName = new ComponentName(pkg, cls);
       intent.setComponent(compName);
       // Will return true if the system is in the process of bringing up a service that your client

src/core/ext/transport/binder/java/io/grpc/binder/cpp/NativeConnectionHelper.java

@@ -30,10 +30,10 @@ final class NativeConnectionHelper {
   // Maps connection id to GrpcBinderConnection instances
   static Map<String, GrpcBinderConnection> s = new HashMap<>();
 
-  static void tryEstablishConnection(Context context, String pkg, String cls, String connId) {
+  static void tryEstablishConnection(Context context, String pkg, String cls, String action_name, String connId) {
     // TODO(mingcl): Assert that connId is unique
     s.put(connId, new GrpcBinderConnection(context, connId));
-    s.get(connId).tryConnect(pkg, cls);
+    s.get(connId).tryConnect(pkg, cls, action_name);
   }
 
   // Returns true if the packages signature of the 2 UIDs match.