content: /*
   * 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 com.datastax.oss.driver.internal.core.metadata;
  
  import com.datastax.oss.driver.api.core.metadata.EndPoint;
  import com.datastax.oss.driver.shaded.guava.common.primitives.UnsignedBytes;
  import edu.umd.cs.findbugs.annotations.NonNull;
  import java.net.InetAddress;
  import java.net.InetSocketAddress;
  import java.net.UnknownHostException;
  import java.util.Arrays;
  import java.util.Comparator;
  import java.util.Objects;
  import java.util.concurrent.atomic.AtomicInteger;
  
  public class SniEndPoint implements EndPoint {
    private static final AtomicInteger OFFSET = new AtomicInteger();
  
    private final InetSocketAddress proxyAddress;
    private final String serverName;
  
    /**
     * @param proxyAddress the address of the proxy. If it is {@linkplain
     *     InetSocketAddress#isUnresolved() unresolved}, each call to {@link #resolve()} will
     *     re-resolve it, fetch all of its A-records, and if there are more than 1 pick one in a
     *     round-robin fashion.
     * @param serverName the SNI server name. In the context of Cloud, this is the string
     *     representation of the host id.
     */
    public SniEndPoint(InetSocketAddress proxyAddress, String serverName) {
      this.proxyAddress = Objects.requireNonNull(proxyAddress, "SNI address cannot be null");
      this.serverName = Objects.requireNonNull(serverName, "SNI Server name cannot be null");
    }
  
    public String getServerName() {
      return serverName;
    }
  
    @NonNull
    @Override
    public InetSocketAddress resolve() {
      try {
        InetAddress[] aRecords = InetAddress.getAllByName(proxyAddress.getHostName());
        if (aRecords.length == 0) {
          // Probably never happens, but the JDK docs don't explicitly say so
          throw new IllegalArgumentException(
              "Could not resolve proxy address " + proxyAddress.getHostName());
        }
        // The order of the returned address is unspecified. Sort by IP to make sure we get a true
        // round-robin
        Arrays.sort(aRecords, IP_COMPARATOR);
        int index =
            (aRecords.length == 1)
                ? 0
                : OFFSET.getAndUpdate(x -> x == Integer.MAX_VALUE ? 0 : x + 1) % aRecords.length;
        return new InetSocketAddress(aRecords[index], proxyAddress.getPort());
      } catch (UnknownHostException e) {
        throw new IllegalArgumentException(
            "Could not resolve proxy address " + proxyAddress.getHostName(), e);
      }
    }
  
    @Override
    public boolean equals(Object other) {
      if (other == this) {
        return true;
      } else if (other instanceof SniEndPoint) {
        SniEndPoint that = (SniEndPoint) other;
        return this.proxyAddress.equals(that.proxyAddress) && this.serverName.equals(that.serverName);
      } else {
        return false;
      }
    }
  
    @Override
    public int hashCode() {
      return Objects.hash(proxyAddress, serverName);
    }
  
    @Override
    public String toString() {
      // Note that this uses the original proxy address, so if there are multiple A-records it won't
      // show which one was selected. If that turns out to be a problem for debugging, we might need
      // to store the result of resolve() in Connection and log that instead of the endpoint.
      return proxyAddress.toString() + ":" + serverName;
    }
  
    @NonNull
    @Override
    public String asMetricPrefix() {
      String hostString = proxyAddress.getHostString();
      if (hostString == null) {
        throw new IllegalArgumentException(
            "Could not extract a host string from provided proxy address " + proxyAddress);
      }
      return hostString.replace('.', '_') + ':' + proxyAddress.getPort() + '_' + serverName;
    }
  
    @SuppressWarnings("UnnecessaryLambda")
    private static final Comparator<InetAddress> IP_COMPARATOR =
        (InetAddress address1, InetAddress address2) ->
            UnsignedBytes.lexicographicalComparator()
                .compare(address1.getAddress(), address2.getAddress());
  }
  