Implement engine_exchangeCapabilities

ethereum/execution-apis#364
Signed-off-by: Simon Dudley <simon.dudley@consensys.net>

ethereum/api/src/main/java/org/hyperledger/besu/ethereum/api/jsonrpc/RpcMethod.java

@@ -55,6 +55,7 @@ public enum RpcMethod {
   ENGINE_FORKCHOICE_UPDATED_V1("engine_forkchoiceUpdatedV1"),
   ENGINE_FORKCHOICE_UPDATED_V2("engine_forkchoiceUpdatedV2"),
   ENGINE_EXCHANGE_TRANSITION_CONFIGURATION("engine_exchangeTransitionConfigurationV1"),
+  ENGINE_EXCHANGE_CAPABILITIES("engine_exchangeCapabilities"),
 
   GOQUORUM_ETH_GET_QUORUM_PAYLOAD("eth_getQuorumPayload"),
   GOQUORUM_STORE_RAW("goquorum_storeRaw"),

ethereum/api/src/main/java/org/hyperledger/besu/ethereum/api/jsonrpc/internal/methods/engine/EngineExchangeCapabilities.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright Hyperledger Besu Contributors.
+ *
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package org.hyperledger.besu.ethereum.api.jsonrpc.internal.methods.engine;
+
+import static org.hyperledger.besu.ethereum.api.jsonrpc.RpcMethod.ENGINE_EXCHANGE_CAPABILITIES;
+import static org.hyperledger.besu.util.Slf4jLambdaHelper.traceLambda;
+
+import org.hyperledger.besu.ethereum.ProtocolContext;
+import org.hyperledger.besu.ethereum.api.jsonrpc.RpcMethod;
+import org.hyperledger.besu.ethereum.api.jsonrpc.internal.JsonRpcRequestContext;
+import org.hyperledger.besu.ethereum.api.jsonrpc.internal.methods.ExecutionEngineJsonRpcMethod;
+import org.hyperledger.besu.ethereum.api.jsonrpc.internal.response.JsonRpcResponse;
+import org.hyperledger.besu.ethereum.api.jsonrpc.internal.response.JsonRpcSuccessResponse;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import io.vertx.core.Vertx;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class EngineExchangeCapabilities extends ExecutionEngineJsonRpcMethod {
+  private static final Logger LOG = LoggerFactory.getLogger(EngineExchangeCapabilities.class);
+
+  public EngineExchangeCapabilities(
+      final Vertx vertx,
+      final ProtocolContext protocolContext,
+      final EngineCallListener engineCallListener) {
+    super(vertx, protocolContext, engineCallListener);
+  }
+
+  @Override
+  public String getName() {
+    return ENGINE_EXCHANGE_CAPABILITIES.getMethodName();
+  }
+
+  @Override
+  public JsonRpcResponse syncResponse(final JsonRpcRequestContext requestContext) {
+    engineCallListener.executionEngineCalled();
+
+    final List<String> remoteCapabilities =
+        Arrays.stream(requestContext.getRequest().getParams())
+            .map(String::valueOf)
+            .collect(Collectors.toList());
+    final Object reqId = requestContext.getRequest().getId();
+
+    traceLambda(LOG, "received remote capabilities: {}", () -> remoteCapabilities);
+
+    final List<String> localCapabilities =
+        Stream.of(RpcMethod.values())
+            .filter(e -> e.getMethodName().startsWith("engine_"))
+            .filter(e -> !e.equals(ENGINE_EXCHANGE_CAPABILITIES))
+            .map(RpcMethod::getMethodName)
+            .collect(Collectors.toList());
+
+    return respondWith(reqId, localCapabilities);
+  }
+
+  private JsonRpcResponse respondWith(
+      final Object requestId, final List<String> localCapabilities) {
+    return new JsonRpcSuccessResponse(requestId, localCapabilities);
+  }
+}

ethereum/api/src/main/java/org/hyperledger/besu/ethereum/api/jsonrpc/methods/ExecutionEngineJsonRpcMethods.java

@@ -18,6 +18,7 @@
 import org.hyperledger.besu.ethereum.ProtocolContext;
 import org.hyperledger.besu.ethereum.api.jsonrpc.RpcApis;
 import org.hyperledger.besu.ethereum.api.jsonrpc.internal.methods.JsonRpcMethod;
+import org.hyperledger.besu.ethereum.api.jsonrpc.internal.methods.engine.EngineExchangeCapabilities;
 import org.hyperledger.besu.ethereum.api.jsonrpc.internal.methods.engine.EngineExchangeTransitionConfiguration;
 import org.hyperledger.besu.ethereum.api.jsonrpc.internal.methods.engine.EngineForkchoiceUpdatedV1;
 import org.hyperledger.besu.ethereum.api.jsonrpc.internal.methods.engine.EngineForkchoiceUpdatedV2;
@@ -112,7 +113,8 @@ protected Map<String, JsonRpcMethod> create() {
               mergeCoordinator.get(),
               engineQosTimer),
           new EngineExchangeTransitionConfiguration(
-              consensusEngineServer, protocolContext, engineQosTimer));
+              consensusEngineServer, protocolContext, engineQosTimer),
+          new EngineExchangeCapabilities(consensusEngineServer, protocolContext, engineQosTimer));
     } else {
       return mapOf(
           new EngineExchangeTransitionConfiguration(

ethereum/api/src/test/java/org/hyperledger/besu/ethereum/api/jsonrpc/internal/methods/engine/EngineExchangeCapabilitiesTest.java

@@ -0,0 +1,93 @@
+/*
+ * Copyright Hyperledger Besu Contributors.
+ *
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package org.hyperledger.besu.ethereum.api.jsonrpc.internal.methods.engine;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.hyperledger.besu.ethereum.api.jsonrpc.RpcMethod.ENGINE_EXCHANGE_CAPABILITIES;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+
+import org.hyperledger.besu.ethereum.ProtocolContext;
+import org.hyperledger.besu.ethereum.api.jsonrpc.internal.JsonRpcRequest;
+import org.hyperledger.besu.ethereum.api.jsonrpc.internal.JsonRpcRequestContext;
+import org.hyperledger.besu.ethereum.api.jsonrpc.internal.response.JsonRpcResponse;
+import org.hyperledger.besu.ethereum.api.jsonrpc.internal.response.JsonRpcResponseType;
+import org.hyperledger.besu.ethereum.api.jsonrpc.internal.response.JsonRpcSuccessResponse;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.Optional;
+
+import io.vertx.core.Vertx;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+
+@RunWith(MockitoJUnitRunner.class)
+public class EngineExchangeCapabilitiesTest {
+  private EngineExchangeCapabilities method;
+  private static final Vertx vertx = Vertx.vertx();
+
+  @Mock private ProtocolContext protocolContext;
+
+  @Mock private EngineCallListener engineCallListener;
+
+  @Before
+  public void setUp() {
+    this.method = new EngineExchangeCapabilities(vertx, protocolContext, engineCallListener);
+  }
+
+  @Test
+  public void shouldReturnExpectedMethodName() {
+    assertThat(method.getName()).isEqualTo("engine_exchangeCapabilities");
+  }
+
+  @Test
+  public void shouldReturnAllSupportedEngineApiRpcNames() {
+    var response = resp(List.of("engine_newPayloadV1", "engine_newPayloadV2", "nonsense"));
+
+    var result = fromSuccessResp(response);
+    assertThat(result).allMatch(name -> name.startsWith("engine_"));
+    verify(engineCallListener, times(1)).executionEngineCalled();
+  }
+
+  @Test
+  public void shouldNotReturnSelf() {
+    var response = resp(Collections.emptyList());
+
+    var result = fromSuccessResp(response);
+    assertThat(result).allMatch(name -> !ENGINE_EXCHANGE_CAPABILITIES.getMethodName().equals(name));
+    verify(engineCallListener, times(1)).executionEngineCalled();
+  }
+
+  private JsonRpcResponse resp(final List<String> params) {
+    return method.response(
+        new JsonRpcRequestContext(
+            new JsonRpcRequest(
+                "2.0", ENGINE_EXCHANGE_CAPABILITIES.getMethodName(), params.toArray())));
+  }
+
+  @SuppressWarnings("unchecked")
+  private List<String> fromSuccessResp(final JsonRpcResponse resp) {
+    assertThat(resp.getType()).isEqualTo(JsonRpcResponseType.SUCCESS);
+    return Optional.of(resp)
+        .map(JsonRpcSuccessResponse.class::cast)
+        .map(JsonRpcSuccessResponse::getResult)
+        .map(List.class::cast)
+        .get();
+  }
+}