devp2p/src/main/kotlin/org/apache/tuweni/devp2p/v5/internal/DefaultNodeDiscoveryService.kt

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.tuweni.devp2p.v5.internal

import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.async
import kotlinx.coroutines.launch
import kotlinx.coroutines.runBlocking
import org.apache.tuweni.bytes.Bytes
import org.apache.tuweni.crypto.SECP256K1
import org.apache.tuweni.devp2p.EthereumNodeRecord
import org.apache.tuweni.devp2p.v5.NodeDiscoveryService
import org.apache.tuweni.devp2p.v5.UdpConnector
import org.apache.tuweni.devp2p.v5.packet.RandomMessage
import org.apache.tuweni.io.Base64URLSafe
import java.net.InetSocketAddress
import java.time.Instant
import kotlin.coroutines.CoroutineContext

class DefaultNodeDiscoveryService(
  private val keyPair: SECP256K1.KeyPair,
  private val localPort: Int,
  private val bindAddress: InetSocketAddress = InetSocketAddress(localPort),
  private val bootstrapENRList: List<String> = emptyList(),
  private val enrSeq: Long = Instant.now().toEpochMilli(),
  private val selfENR: Bytes = EthereumNodeRecord.toRLP(
    keyPair,
    enrSeq,
    emptyMap(),
    bindAddress.address,
    null,
    bindAddress.port
  ),
  private val connector: UdpConnector = DefaultUdpConnector(bindAddress, keyPair, selfENR),
  override val coroutineContext: CoroutineContext = Dispatchers.Default
) : NodeDiscoveryService, CoroutineScope {

  override fun start() {
    connector.start()
    launch { bootstrap() }
  }

  override fun terminate(await: Boolean) {
    runBlocking {
      val job = async { connector.terminate() }
      if (await) {
        job.await()
      }
    }
  }

  private fun bootstrap() {
    bootstrapENRList.forEach {
      if (it.startsWith("enr:")) {
        val encodedEnr = it.substringAfter("enr:")
        val rlpENR = Base64URLSafe.decode(encodedEnr)
        val enr = EthereumNodeRecord.fromRLP(rlpENR)

        val randomMessage = RandomMessage()
        val address = InetSocketAddress(enr.ip(), enr.udp())

        connector.addPendingNodeId(address, rlpENR)
        connector.send(address, randomMessage, rlpENR)
      }
    }
  }
}