feat: Node discovery via DNS (hyperledger#7129)

- Node discovery via DNS module as a vertex verticle (code adapted from Tuweni)
- Mock DNS server in unit tests.

---------

Signed-off-by: Usman Saleem <usman@usmans.info>
Co-authored-by: Sally MacFarlane <macfarla.github@gmail.com>

CHANGELOG.md

@@ -23,6 +23,7 @@
 - Default bonsai to use full-flat db and code-storage-by-code-hash [#6984](https://github.com/hyperledger/besu/pull/6894)
 - New RPC methods miner_setExtraData and miner_getExtraData [#7078](https://github.com/hyperledger/besu/pull/7078)
 - Disconnect peers that have multiple discovery ports since they give us bad neighbours [#7089](https://github.com/hyperledger/besu/pull/7089)
+- Port Tuweni dns-discovery into Besu. [#7129](https://github.com/hyperledger/besu/pull/7129)
 
 ### Known Issues
 - [Frequency: occasional < 10%] Chain download halt. Only affects new syncs (new nodes syncing from scratch). Symptom: Block import halts, despite having a full set of peers and world state downloading finishing. Generally restarting besu will resolve the issue. We are tracking this in [#6884](https://github.com/hyperledger/besu/pull/6884)

NOTICE

@@ -0,0 +1,19 @@
+Hyperledger Besu
+Copyright contributors to Hyperledger Besu.
+
+This product includes software adapted from Tuweni. (https://tuweni.tmio.io/)
+Copyright 2023-2024 The Machine Consultancy LLC
+Licensed under Apache License 2.0 (http://www.apache.org/licenses/LICENSE-2.0)
+
+The following NOTICE file content is provided by Tuweni:
+------------------------------------------------------------
+This product includes code developed under the Apache Tuweni incubation project.
+
+Copyright 2019-2023 The Apache Software Foundation
+
+This product includes software developed at
+The Apache Software Foundation (http://www.apache.org/).
+
+In addition, this product includes software developed by
+Copyright 2018-2019 ConsenSys, Inc.
+------------------------------------------------------------

ethereum/p2p/build.gradle

@@ -50,9 +50,6 @@ dependencies {
   implementation('io.tmio:tuweni-devp2p') {
     exclude group:'ch.qos.logback', module:'logback-classic'
   }
-  implementation('io.tmio:tuweni-dns-discovery'){
-    exclude group:'ch.qos.logback', module:'logback-classic'
-  }
   implementation 'io.tmio:tuweni-io'
   implementation 'io.tmio:tuweni-rlp'
   implementation 'io.tmio:tuweni-units'
@@ -84,6 +81,7 @@ dependencies {
   }
   testImplementation 'io.vertx:vertx-codegen'
   testImplementation 'io.vertx:vertx-unit'
+  testImplementation 'io.vertx:vertx-junit5'
   testImplementation 'org.assertj:assertj-core'
   testImplementation 'org.awaitility:awaitility'
   testImplementation 'org.junit.jupiter:junit-jupiter'

ethereum/p2p/src/main/java/org/hyperledger/besu/ethereum/p2p/discovery/dns/DNSDaemon.java

@@ -0,0 +1,107 @@
+/*
+ * Copyright contributors to Hyperledger Besu.
+ *
+ * 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.p2p.discovery.dns;
+
+import java.util.List;
+import java.util.Optional;
+
+import io.vertx.core.AbstractVerticle;
+import org.apache.tuweni.devp2p.EthereumNodeRecord;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+// Adapted from https://github.com/tmio/tuweni and licensed under Apache 2.0
+/**
+ * Resolves DNS records over time, refreshing records. This is written as a Vertx Verticle which
+ * allows to run outside the Vertx event loop
+ */
+public class DNSDaemon extends AbstractVerticle {
+  private static final Logger LOG = LoggerFactory.getLogger(DNSDaemon.class);
+  private final String enrLink;
+  private final long seq;
+  private final long initialDelay;
+  private final long delay;
+  private final Optional<DNSDaemonListener> listener;
+  private final Optional<String> dnsServer;
+  private Optional<Long> periodicTaskId = Optional.empty();
+  private DNSResolver dnsResolver;
+
+  /**
+   * Creates a new DNSDaemon.
+   *
+   * @param enrLink the ENR link to start with, of the form enrtree://PUBKEY@domain
+   * @param listener Listener notified when records are read and whenever they are updated.
+   * @param seq the sequence number of the root record. If the root record seq is higher, proceed
+   *     with visit.
+   * @param initialDelay the delay in milliseconds before the first poll of DNS records.
+   * @param delay the delay in milliseconds at which to poll DNS records. If negative or zero, it
+   *     runs only once.
+   * @param dnsServer the DNS server to use for DNS query. If null, the default DNS server will be
+   *     used.
+   */
+  public DNSDaemon(
+      final String enrLink,
+      final DNSDaemonListener listener,
+      final long seq,
+      final long initialDelay,
+      final long delay,
+      final String dnsServer) {
+    this.enrLink = enrLink;
+    this.listener = Optional.ofNullable(listener);
+    this.seq = seq;
+    this.initialDelay = initialDelay;
+    this.delay = delay;
+    this.dnsServer = Optional.ofNullable(dnsServer);
+  }
+
+  /** Starts the DNSDaemon. */
+  @Override
+  public void start() {
+    if (vertx == null) {
+      throw new IllegalStateException("DNSDaemon must be deployed as a vertx verticle.");
+    }
+
+    LOG.info("Starting DNSDaemon for {}, using {} DNS host.", enrLink, dnsServer.orElse("default"));
+    dnsResolver = new DNSResolver(vertx, enrLink, seq, dnsServer);
+    if (delay > 0) {
+      periodicTaskId = Optional.of(vertx.setPeriodic(initialDelay, delay, this::refreshENRRecords));
+    } else {
+      // do one-shot resolution
+      refreshENRRecords(0L);
+    }
+  }
+
+  /** Stops the DNSDaemon. */
+  @Override
+  public void stop() {
+    LOG.info("Stopping DNSDaemon for {}", enrLink);
+    periodicTaskId.ifPresent(vertx::cancelTimer);
+    dnsResolver.close();
+  }
+
+  /**
+   * Refresh enr records by calling dnsResolver and updating the listeners.
+   *
+   * @param taskId the task id of the periodic task
+   */
+  void refreshENRRecords(final Long taskId) {
+    LOG.debug("Refreshing DNS records");
+    final long startTime = System.nanoTime();
+    final List<EthereumNodeRecord> ethereumNodeRecords = dnsResolver.collectAll();
+    final long endTime = System.nanoTime();
+    LOG.debug("Time taken to DNSResolver.collectAll: {} ms", (endTime - startTime) / 1_000_000);
+    listener.ifPresent(it -> it.newRecords(dnsResolver.sequence(), ethereumNodeRecords));
+  }
+}

ethereum/p2p/src/main/java/org/hyperledger/besu/ethereum/p2p/discovery/dns/DNSDaemonListener.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright contributors to Hyperledger Besu.
+ *
+ * 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.p2p.discovery.dns;
+
+import java.util.List;
+
+import org.apache.tuweni.devp2p.EthereumNodeRecord;
+
+// Adapted from https://github.com/tmio/tuweni and licensed under Apache 2.0
+/** Callback listening to updates of the DNS records. */
+@FunctionalInterface
+public interface DNSDaemonListener {
+  /**
+   * Callback called when the seq is updated on the DNS server
+   *
+   * @param seq the update identifier of the records
+   * @param records the records stored on the server
+   */
+  void newRecords(long seq, List<EthereumNodeRecord> records);
+}