feat(xds): Add ExternalAuthorizationFilter

core/src/main/java/io/grpc/internal/FailingClientCall.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2025 The 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.internal;
+
+import io.grpc.ClientCall;
+import io.grpc.Metadata;
+import io.grpc.Status;
+import javax.annotation.Nullable;
+
+/**
+ * A {@link ClientCall} that fails immediately upon starting.
+ */
+public final class FailingClientCall<ReqT, RespT> extends ClientCall<ReqT, RespT> {
+
+  private final Status error;
+
+  /**
+   * Creates a new call that will fail with the given error.
+   */
+  public FailingClientCall(Status error) {
+    this.error = error;
+  }
+
+  /**
+   * Immediately fails the call by calling {@link Listener#onClose}.
+   */
+  @Override
+  public void start(Listener<RespT> responseListener, Metadata headers) {
+    responseListener.onClose(error, new Metadata());
+  }
+
+  @Override
+  public void request(int numMessages) {}
+
+  @Override
+  public void cancel(@Nullable String message, @Nullable Throwable cause) {}
+
+  @Override
+  public void halfClose() {}
+
+  @Override
+  public void sendMessage(ReqT message) {}
+}

core/src/test/java/io/grpc/internal/FailingClientCallTest.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2016 The 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.internal;
+
+import static org.junit.Assert.assertEquals;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+
+import io.grpc.ClientCall;
+import io.grpc.Metadata;
+import io.grpc.Status;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnit;
+import org.mockito.junit.MockitoRule;
+
+/** Unit tests for {@link FailingClientCall}. */
+@RunWith(JUnit4.class)
+public class FailingClientCallTest {
+
+  @Rule public final MockitoRule mocks = MockitoJUnit.rule();
+
+  @Mock
+  private ClientCall.Listener<Object> mockListener;
+
+  @Test
+  public void startCallsOnClose() {
+    Status error = Status.UNAVAILABLE.withDescription("test error");
+    FailingClientCall<Object, Object> call = new FailingClientCall<>(error);
+    Metadata metadata = new Metadata();
+    call.start(mockListener, metadata);
+
+    ArgumentCaptor<Metadata> metadataCaptor = ArgumentCaptor.forClass(Metadata.class);
+    verify(mockListener).onClose(eq(error), metadataCaptor.capture());
+    assertEquals(0, metadataCaptor.getValue().keys().size());
+    verifyNoMoreInteractions(mockListener);
+  }
+
+  @Test
+  public void otherMethodsAreNoOps() {
+    Status error = Status.UNAVAILABLE.withDescription("test error");
+    FailingClientCall<Object, Object> call = new FailingClientCall<>(error);
+    Metadata metadata = new Metadata();
+
+    call.start(mockListener, metadata); // Must call start first
+
+    call.request(1);
+    call.cancel("message", new RuntimeException("cause"));
+    call.halfClose();
+    call.sendMessage(new Object());
+
+    ArgumentCaptor<Metadata> metadataCaptor = ArgumentCaptor.forClass(Metadata.class);
+    verify(mockListener).onClose(eq(error), metadataCaptor.capture());
+    assertEquals(0, metadataCaptor.getValue().keys().size());
+    verifyNoMoreInteractions(mockListener);
+  }
+}

xds/src/main/java/io/grpc/xds/ExtAuthzFilter.java

@@ -0,0 +1,217 @@
+/*
+ * Copyright 2025 The 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.xds;
+
+import com.google.protobuf.Any;
+import com.google.protobuf.InvalidProtocolBufferException;
+import com.google.protobuf.Message;
+import io.envoyproxy.envoy.extensions.filters.http.ext_authz.v3.ExtAuthz;
+import io.envoyproxy.envoy.service.auth.v3.AuthorizationGrpc;
+import io.grpc.ClientInterceptor;
+import io.grpc.ServerInterceptor;
+import io.grpc.xds.internal.ThreadSafeRandom;
+import io.grpc.xds.internal.ThreadSafeRandom.ThreadSafeRandomImpl;
+import io.grpc.xds.internal.extauthz.BufferingAuthzClientCall;
+import io.grpc.xds.internal.extauthz.CheckRequestBuilder;
+import io.grpc.xds.internal.extauthz.CheckResponseHandler;
+import io.grpc.xds.internal.extauthz.ExtAuthzCertificateProvider;
+import io.grpc.xds.internal.extauthz.ExtAuthzClientInterceptor;
+import io.grpc.xds.internal.extauthz.ExtAuthzConfig;
+import io.grpc.xds.internal.extauthz.ExtAuthzParseException;
+import io.grpc.xds.internal.extauthz.ExtAuthzServerInterceptor;
+import io.grpc.xds.internal.extauthz.StubManager;
+import io.grpc.xds.internal.grpcservice.InsecureGrpcChannelFactory;
+import io.grpc.xds.internal.headermutations.HeaderMutationFilter;
+import io.grpc.xds.internal.headermutations.HeaderMutator;
+import java.util.concurrent.ScheduledExecutorService;
+import javax.annotation.Nullable;
+
+final class ExtAuthzFilter implements Filter {
+
+  private static final String TYPE_URL =
+      "type.googleapis.com/envoy.extensions.filters.http.ext_authz.v3.ExtAuthz";
+
+  private static final String TYPE_URL_OVERRIDE_CONFIG =
+      "type.googleapis.com/envoy.extensions.filters.http.ext_authz.v3.ExtAuthzPerRoute";
+
+
+  static final class ExtAuthzFilterConfig implements Filter.FilterConfig {
+
+    private final ExtAuthzConfig extAuthzConfig;
+
+    ExtAuthzFilterConfig(ExtAuthzConfig extAuthzConfig) {
+      this.extAuthzConfig = extAuthzConfig;
+    }
+
+    public ExtAuthzConfig extAuthzConfig() {
+      return extAuthzConfig;
+    }
+
+    @Override
+    public String typeUrl() {
+      return ExtAuthzFilter.TYPE_URL;
+    }
+
+    public static ExtAuthzFilterConfig fromProto(ExtAuthz extAuthzProto)
+        throws ExtAuthzParseException {
+      return new ExtAuthzFilterConfig(ExtAuthzConfig.fromProto(extAuthzProto));
+    }
+  }
+
+  // Placeholder for the external authorization filter's override config.
+  static final class ExtAuthzFilterConfigOverride implements Filter.FilterConfig {
+    @Override
+    public final String typeUrl() {
+      return ExtAuthzFilter.TYPE_URL_OVERRIDE_CONFIG;
+    }
+  }
+
+  static final class Provider implements Filter.Provider {
+
+    @Override
+    public String[] typeUrls() {
+      return new String[] {TYPE_URL, TYPE_URL_OVERRIDE_CONFIG};
+    }
+
+    @Override
+    public boolean isClientFilter() {
+      return true;
+    }
+
+    @Override
+    public boolean isServerFilter() {
+      return true;
+    }
+
+    @Override
+    public ExtAuthzFilter newInstance(String name) {
+      // Create a dedicated scheduler for this filter instance's StubManager
+      StubManager stubManager = StubManager.create(InsecureGrpcChannelFactory.getInstance());
+      return new ExtAuthzFilter(stubManager, ThreadSafeRandomImpl.INSTANCE,
+              BufferingAuthzClientCall.FACTORY_INSTANCE, ExtAuthzCertificateProvider.create(),
+          CheckRequestBuilder.INSTANCE, CheckResponseHandler.INSTANCE,
+          ExtAuthzClientInterceptor.INSTANCE, ExtAuthzServerInterceptor.INSTANCE,
+          HeaderMutationFilter.INSTANCE, HeaderMutator.create());
+    }
+
+    @Override
+    public ConfigOrError<ExtAuthzFilterConfig> parseFilterConfig(Message rawProtoMessage) {
+      ExtAuthz extAuthzProto;
+      if (!(rawProtoMessage instanceof Any)) {
+        return ConfigOrError.fromError("Invalid config type: " + rawProtoMessage.getClass());
+      }
+      Any anyMessage = (Any) rawProtoMessage;
+      try {
+        extAuthzProto = anyMessage.unpack(ExtAuthz.class);
+        return ConfigOrError.fromConfig(ExtAuthzFilterConfig.fromProto(extAuthzProto));
+      } catch (InvalidProtocolBufferException | ExtAuthzParseException e) {
+        return ConfigOrError.fromError("Invalid proto: " + e);
+      }
+    }
+
+    @Override
+    public ConfigOrError<ExtAuthzFilterConfigOverride> parseFilterConfigOverride(
+        Message rawProtoMessage) {
+      if (!(rawProtoMessage instanceof Any)) {
+        return ConfigOrError.fromError("Invalid config type: " + rawProtoMessage.getClass());
+      }
+      return ConfigOrError.fromConfig(new ExtAuthzFilterConfigOverride());
+    }
+  }
+
+  private final StubManager stubManager;
+  private final ThreadSafeRandom random;
+  private final BufferingAuthzClientCall.Factory bufferingAuthzClientCallFactory;
+  private final ExtAuthzCertificateProvider certificateProvider;
+  private final CheckRequestBuilder.Factory checkRequestBuilderFactory;
+  private final CheckResponseHandler.Factory checkResponseHandlerFactory;
+  private final ExtAuthzClientInterceptor.Factory extAuthzClientInterceptorFactory;
+  private final ExtAuthzServerInterceptor.Factory extAuthzServerInterceptorFactory;
+  private final HeaderMutationFilter.Factory headerMutationFilterFactory;
+  private final HeaderMutator headerMutator;
+
+
+  ExtAuthzFilter(StubManager stubManager, ThreadSafeRandom random,
+      BufferingAuthzClientCall.Factory bufferingAuthzClientCallFactory,
+      ExtAuthzCertificateProvider certificateProvider,
+          CheckRequestBuilder.Factory checkRequestBuilderFactory,
+      CheckResponseHandler.Factory checkResponseHandlerFactory,
+      ExtAuthzClientInterceptor.Factory extAuthzClientInterceptorFactory,
+      ExtAuthzServerInterceptor.Factory extAuthzServerInterceptorFactory,
+          HeaderMutationFilter.Factory headerMutationFilterFactory, HeaderMutator headerMutator) {
+    this.stubManager = stubManager;
+    this.random = random;
+    this.bufferingAuthzClientCallFactory = bufferingAuthzClientCallFactory;
+    this.certificateProvider = certificateProvider;
+    this.checkRequestBuilderFactory = checkRequestBuilderFactory;
+    this.checkResponseHandlerFactory = checkResponseHandlerFactory;
+    this.extAuthzClientInterceptorFactory = extAuthzClientInterceptorFactory;
+    this.extAuthzServerInterceptorFactory = extAuthzServerInterceptorFactory;
+    this.headerMutationFilterFactory = headerMutationFilterFactory;
+    this.headerMutator = headerMutator;
+  }
+
+  @Nullable
+  @Override
+  public ClientInterceptor buildClientInterceptor(FilterConfig config,
+      @Nullable FilterConfig overrideConfig, ScheduledExecutorService scheduler) {
+    if (overrideConfig != null) {
+      return null;
+    }
+    if (!(config instanceof ExtAuthzFilterConfig)) {
+      return null;
+    }
+    ExtAuthzFilterConfig extAuthzFilterConfig = (ExtAuthzFilterConfig) config;
+    AuthorizationGrpc.AuthorizationStub stub =
+        stubManager.getStub(extAuthzFilterConfig.extAuthzConfig());
+    ExtAuthzConfig extAuthzConfig = extAuthzFilterConfig.extAuthzConfig();
+    return extAuthzClientInterceptorFactory.create(extAuthzConfig, stub,
+            random, bufferingAuthzClientCallFactory,
+        checkRequestBuilderFactory.create(extAuthzConfig, certificateProvider),
+        checkResponseHandlerFactory.create(headerMutator,
+            headerMutationFilterFactory.create(extAuthzConfig.decoderHeaderMutationRules()),
+            extAuthzConfig),
+        headerMutator);
+  }
+
+  @Nullable
+  @Override
+  public ServerInterceptor buildServerInterceptor(FilterConfig config,
+      @Nullable FilterConfig overrideConfig) {
+    if (overrideConfig != null) {
+      return null;
+    }
+    if (!(config instanceof ExtAuthzFilterConfig)) {
+      return null;
+    }
+    ExtAuthzFilterConfig extAuthzFilterConfig = (ExtAuthzFilterConfig) config;
+    AuthorizationGrpc.AuthorizationStub stub =
+        stubManager.getStub(extAuthzFilterConfig.extAuthzConfig());
+    ExtAuthzConfig extAuthzConfig = extAuthzFilterConfig.extAuthzConfig();
+    return extAuthzServerInterceptorFactory.create(extAuthzConfig, stub, random,
+            checkRequestBuilderFactory.create(extAuthzConfig, certificateProvider),
+        checkResponseHandlerFactory.create(headerMutator,
+            headerMutationFilterFactory.create(extAuthzConfig.decoderHeaderMutationRules()),
+            extAuthzConfig),
+        headerMutator);
+  }
+
+  @Override
+  public void close() {
+    stubManager.close();
+  }
+}

xds/src/main/java/io/grpc/xds/ThreadSafeRandom.java

@@ -16,36 +16,34 @@
 
 package io.grpc.xds;
 
-import java.util.concurrent.ThreadLocalRandom;
 import javax.annotation.concurrent.ThreadSafe;
 
-@ThreadSafe // Except for impls/mocks in tests
-interface ThreadSafeRandom {
-  int nextInt(int bound);
-
-  long nextLong();
-
-  long nextLong(long bound);
+// TODO(sauravzg): Remove this class once all usages within xds are migrated to
+// the internal version.
+@ThreadSafe
+interface ThreadSafeRandom extends io.grpc.xds.internal.ThreadSafeRandom {
 
   final class ThreadSafeRandomImpl implements ThreadSafeRandom {
 
     static final ThreadSafeRandom instance = new ThreadSafeRandomImpl();
+    private final io.grpc.xds.internal.ThreadSafeRandom delegate =
+        io.grpc.xds.internal.ThreadSafeRandom.ThreadSafeRandomImpl.INSTANCE;
 
     private ThreadSafeRandomImpl() {}
 
     @Override
     public int nextInt(int bound) {
-      return ThreadLocalRandom.current().nextInt(bound);
+      return delegate.nextInt(bound);
     }
 
     @Override
     public long nextLong() {
-      return ThreadLocalRandom.current().nextLong();
+      return delegate.nextLong();
     }
 
     @Override
     public long nextLong(long bound) {
-      return ThreadLocalRandom.current().nextLong(bound);
+      return delegate.nextLong(bound);
     }
   }
 }