Add helper function for getting endpoint binder in Java (#27598)

Also update the server side URI scheme to use path instead of authority

See gRFC L85-core-binder-transport.md for more details

examples/android/binder/java/io/grpc/binder/cpp/exampleserver/BUILD

@@ -53,7 +53,9 @@ android_library(
     srcs = ["ExportedEndpointService.java"],
     exports_manifest = True,
     manifest = "AndroidManifest_endpoint.xml",
-    deps = [],
+    deps = [
+        "@binder_transport_android_helper//io/grpc/binder/cpp:connection_helper",
+    ],
 )
 
 android_binary(

examples/android/binder/java/io/grpc/binder/cpp/exampleserver/ExportedEndpointService.java

@@ -1,28 +1,25 @@
 package io.grpc.binder.cpp.exampleserver;
 
 import android.app.Service;
-import android.os.IBinder;
 import android.content.Intent;
+import android.os.IBinder;
+import io.grpc.binder.cpp.GrpcCppServerBuilder;
 
 /** Exposes gRPC services running in the main process */
 public final class ExportedEndpointService extends Service {
-  private final IBinder binder;
-
   static {
     System.loadLibrary("app");
   }
 
   public ExportedEndpointService() {
     init_grpc_server();
-    binder = get_endpoint_binder();
   }
 
   @Override
   public IBinder onBind(Intent intent) {
-    return binder;
+    // The argument should match the URI passed into grpc::ServerBuilder::AddListeningPort
+    return GrpcCppServerBuilder.GetEndpointBinder("binder:example.service");
   }
 
   public native void init_grpc_server();
-
-  public native IBinder get_endpoint_binder();
 }

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

@@ -63,24 +63,10 @@ Java_io_grpc_binder_cpp_exampleserver_ExportedEndpointService_init_1grpc_1server
 
   // TODO(mingcl): Use same signature security after it become available
   server_builder.AddListeningPort(
-      "binder://example.service",
+      "binder:example.service",
       grpc::experimental::BinderServerCredentials(
           std::make_shared<
               grpc::experimental::binder::UntrustedSecurityPolicy>()));
 
   server = server_builder.BuildAndStart();
 }
-
-extern "C" JNIEXPORT jobject JNICALL
-Java_io_grpc_binder_cpp_exampleserver_ExportedEndpointService_get_1endpoint_1binder(
-    JNIEnv* env, jobject /*this*/) {
-  __android_log_print(ANDROID_LOG_INFO, "DemoServer", "Line number %d",
-                      __LINE__);
-
-  auto ai_binder = static_cast<AIBinder*>(
-      grpc::experimental::binder::GetEndpointBinder("example.service"));
-
-  __android_log_print(ANDROID_LOG_INFO, "DemoServer", "ai_binder = %p",
-                      ai_binder);
-  return AIBinder_toJavaBinder(env, ai_binder);
-}

src/core/ext/transport/binder/java/io/grpc/binder/cpp/BUILD

@@ -19,6 +19,7 @@ licenses(["notice"])
 android_library(
     name = "connection_helper",
     srcs = [
+        "GrpcCppServerBuilder.java",
         "NativeConnectionHelper.java",
         "SyncServiceConnection.java",
     ],

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

@@ -0,0 +1,38 @@
+// Copyright 2021 gRPC 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 io.grpc.binder.cpp;
+
+import android.os.IBinder;
+import android.util.Log;
+
+/* EXPERIMENTAL. Provides a interface to get endpoint binder from C++ */
+public class GrpcCppServerBuilder {
+  private static final String logTag = "GrpcCppServerBuilder";
+
+  public static IBinder GetEndpointBinder(String uri) {
+    String scheme = "binder:";
+    if (uri.startsWith(scheme)) {
+      String path = uri.substring(scheme.length());
+      // TODO(mingcl): Consider if we would like to make sure the path only contain valid
+      // characters here
+      return GetEndpointBinderInternal(path);
+    } else {
+      Log.e(logTag, "URI " + uri + " does not start with 'binder:'");
+      return null;
+    }
+  }
+
+  private static native IBinder GetEndpointBinderInternal(String conn_id);
+}

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

@@ -35,6 +35,7 @@ public class SyncServiceConnection implements ServiceConnection {
   @Override
   public void onServiceConnected(ComponentName className, IBinder service) {
     Log.e(logTag, "Service has connected: ");
+    // TODO(mingcl): Check if service is null here
     synchronized (this) {
       mService = service;
     }

src/core/ext/transport/binder/server/binder_server.cc

@@ -30,6 +30,46 @@
 #include "src/core/lib/surface/server.h"
 #include "src/core/lib/transport/error_utils.h"
 
+#ifdef GPR_SUPPORT_BINDER_TRANSPORT
+
+#include <android/binder_ibinder.h>
+#include <android/binder_ibinder_jni.h>
+#include <jni.h>
+
+extern "C" {
+
+// This will be invoked from
+// src/core/ext/transport/binder/java/io/grpc/binder/cpp/GrpcCppServerBuilder.java
+JNIEXPORT jobject JNICALL
+Java_io_grpc_binder_cpp_GrpcCppServerBuilder_GetEndpointBinderInternal__Ljava_lang_String_2(
+    JNIEnv* jni_env, jobject, jstring conn_id_jstring) {
+  AIBinder* ai_binder = nullptr;
+
+  {
+    // This block is the scope of conn_id c-string
+    jboolean isCopy;
+    const char* conn_id = jni_env->GetStringUTFChars(conn_id_jstring, &isCopy);
+    ai_binder =
+        static_cast<AIBinder*>(grpc_get_endpoint_binder(std::string(conn_id)));
+    if (ai_binder == nullptr) {
+      gpr_log(GPR_ERROR, "Cannot find endpoint binder with connection id = %s",
+              conn_id);
+    }
+    if (isCopy == JNI_TRUE) {
+      jni_env->ReleaseStringUTFChars(conn_id_jstring, conn_id);
+    }
+  }
+
+  if (ai_binder == nullptr) {
+    return nullptr;
+  }
+
+  return AIBinder_toJavaBinder(jni_env, ai_binder);
+}
+}
+
+#endif
+
 namespace grpc {
 namespace experimental {
 namespace binder {
@@ -190,18 +230,18 @@ bool AddBinderPort(const std::string& addr, grpc_server* server,
                    BinderTxReceiverFactory factory,
                    std::shared_ptr<grpc::experimental::binder::SecurityPolicy>
                        security_policy) {
+  // TODO(mingcl): Check if the addr is valid here after binder address resolver
+  // related code are merged.
   const std::string kBinderUriScheme = "binder:";
   if (addr.compare(0, kBinderUriScheme.size(), kBinderUriScheme) != 0) {
     return false;
   }
-  size_t pos = kBinderUriScheme.size();
-  while (pos < addr.size() && addr[pos] == '/') pos++;
+  std::string conn_id = addr.substr(kBinderUriScheme.size());
   grpc_core::Server* core_server = server->core_server.get();
   core_server->AddListener(
       grpc_core::OrphanablePtr<grpc_core::Server::ListenerInterface>(
-          new grpc_core::BinderServerListener(core_server, addr.substr(pos),
-                                              std::move(factory),
-                                              security_policy)));
+          new grpc_core::BinderServerListener(
+              core_server, conn_id, std::move(factory), security_policy)));
   return true;
 }
 

test/core/transport/binder/end2end/binder_server_test.cc

@@ -108,7 +108,7 @@ TEST(BinderServerCredentialsTest,
   grpc::testing::TestServiceImpl service;
   server_builder.RegisterService(&service);
   server_builder.AddListeningPort(
-      "binder://fail",
+      "binder:fail",
       grpc::experimental::BinderServerCredentials(
           std::make_shared<
               grpc::experimental::binder::UntrustedSecurityPolicy>()));
@@ -120,7 +120,7 @@ TEST_F(BinderServerTest, BuildAndStart) {
   grpc::ServerBuilder server_builder;
   grpc::testing::TestServiceImpl service;
   server_builder.RegisterService(&service);
-  server_builder.AddListeningPort("binder://example.service",
+  server_builder.AddListeningPort("binder:example.service",
                                   grpc::testing::BinderServerCredentials());
   std::unique_ptr<grpc::Server> server = server_builder.BuildAndStart();
   EXPECT_NE(grpc::experimental::binder::GetEndpointBinder("example.service"),
@@ -145,7 +145,7 @@ TEST_F(BinderServerTest, CreateChannelWithEndpointBinder) {
   grpc::ServerBuilder server_builder;
   grpc::testing::TestServiceImpl service;
   server_builder.RegisterService(&service);
-  server_builder.AddListeningPort("binder://example.service",
+  server_builder.AddListeningPort("binder:example.service",
                                   grpc::testing::BinderServerCredentials());
   std::unique_ptr<grpc::Server> server = server_builder.BuildAndStart();
   void* raw_endpoint_binder =
@@ -172,9 +172,8 @@ TEST_F(BinderServerTest, CreateChannelWithEndpointBinderMultipleConnections) {
   grpc::ServerBuilder server_builder;
   grpc::testing::TestServiceImpl service;
   server_builder.RegisterService(&service);
-  server_builder.AddListeningPort(
-      "binder://example.service.multiple.connections",
-      grpc::testing::BinderServerCredentials());
+  server_builder.AddListeningPort("binder:example.service.multiple.connections",
+                                  grpc::testing::BinderServerCredentials());
   std::unique_ptr<grpc::Server> server = server_builder.BuildAndStart();
   void* raw_endpoint_binder = grpc::experimental::binder::GetEndpointBinder(
       "example.service.multiple.connections");