}

    return true;
  }

  /**
   * Returns the IPv4 address embedded in an IPv4 compatible address.
   *
   * @param ip {@link Inet6Address} to be examined for an embedded IPv4 address
   * @return {@link Inet4Address} of the embedded IPv4 address
   * @throws IllegalArgumentException if the argument is not a valid IPv4 compatible address
   */

    }

    return true;
  }

  /**
   * Returns the IPv4 address embedded in an IPv4 compatible address.
   *
   * @param ip {@link Inet6Address} to be examined for an embedded IPv4 address
   * @return {@link Inet4Address} of the embedded IPv4 address
   * @throws IllegalArgumentException if the argument is not a valid IPv4 compatible address
   */

net.core.netdev_max_backlog=250000
net.core.somaxconn=16384
net.ipv4.tcp_syncookies=0
net.ipv4.tcp_max_syn_backlog=16384
net.core.wmem_max=4194304
net.core.rmem_max=4194304
net.core.rmem_default=4194304
net.core.wmem_default=4194304
net.ipv4.tcp_rmem="4096 87380 4194304"
net.ipv4.tcp_wmem="4096 65536 4194304"

# Reduce CPU utilization
net.ipv4.tcp_timestamps=0

# Increase throughput
net.ipv4.tcp_sack=1

# Low latency mode for TCP

import org.junitpioneer.jupiter.RetryingTest
import org.opentest4j.TestAbortedException

/**
 * This test binds two different web servers (IPv4 and IPv6) to the same port, but on different
 * local IP addresses. Requests made to `127.0.0.1` will reach the IPv4 server, and requests made to
 * `::1` will reach the IPv6 server.
 *
 * By orchestrating two different servers with the same port but different IP addresses, we can

    val request = Request(server1.url("/"))

    server1.enqueue(refusedStream)
    server2.enqueue(bodyResponse)

    dns[server1.hostName] = listOf(ipv6, ipv4)
    socketFactory[ipv6] = server1.inetSocketAddress
    socketFactory[ipv4] = server2.inetSocketAddress

    client =
      client.newBuilder()
        .fastFallback(false)
        .apply {
          retryOnConnectionFailure = false
        }

    InetAddress ipv4 = InetAddresses.forString("1.2.3.4");
    assertEquals(ipv4, InetAddresses.getEmbeddedIPv4ClientAddress(testIp));

    // Test 6to4 address.
    testIp = (Inet6Address) InetAddresses.forString("2002:0102:0304::1");
    assertTrue(InetAddresses.hasEmbeddedIPv4ClientAddress(testIp));
    ipv4 = InetAddresses.forString("1.2.3.4");
    assertEquals(ipv4, InetAddresses.getEmbeddedIPv4ClientAddress(testIp));

fun reorderForHappyEyeballs(addresses: List<InetAddress>): List<InetAddress> {
  if (addresses.size < 2) {
    return addresses
  }

  val (ipv6, ipv4) = addresses.partition { it is Inet6Address }

  return if (ipv6.isEmpty() || ipv4.isEmpty()) {
    addresses
  } else {
    interleave(ipv6, ipv4)
  }

    val allAddresses = mutableListOf<InetAddress>()
    var exception: Exception? = null
    val latch = CountDownLatch(1)

    // assumes an IPv4 address
    AndroidAsyncDns.IPv4.query(
      hostname,
      object : AsyncDns.Callback {
        override fun onResponse(
          hostname: String,
          addresses: List<InetAddress>,
        ) {

class FakeDns : Dns {
  private val hostAddresses: MutableMap<String, List<InetAddress>> = mutableMapOf()
  private val requestedHosts: MutableList<String> = mutableListOf()
  private var nextAddress = 0xff000064L // 255.0.0.100 in IPv4; ::ff00:64 in IPv6.

  /** Sets the results for `hostname`.  */
  operator fun set(
    hostname: String,
    addresses: List<InetAddress>,
  ): FakeDns {
    hostAddresses[hostname] = addresses
    return this

  )

  /**
   * Callback to receive results from the DNS Queries.
   */
  @ExperimentalOkHttpApi
  interface Callback {
    /**
     * Return addresses for a dns query for a single class of IPv4 (A) or IPv6 (AAAA).
     * May be an empty list indicating that the host is unreachable.
     */
    fun onResponse(
      hostname: String,
      addresses: List<InetAddress>,
    )

    /**