*   <dt>An IPv6 "IPv4 mapped" address, {@code "::ffff:192.168.0.1"}.
 *   <dd>{@code 00 00 00 00 00 00 00 00 00 00 ff ff c0 a8 00 01}
 * </dl>
 *
 * <p>A few notes about IPv6 "IPv4 mapped" addresses and their observed use in Java.
 *
 * <p>"IPv4 mapped" addresses were originally a representation of IPv4 addresses for use on an IPv6
 * socket that could receive both IPv4 and IPv6 connections (by disabling the {@code IPV6_V6ONLY}

 *   <dt>An IPv6 "IPv4 mapped" address, {@code "::ffff:192.168.0.1"}.
 *   <dd>{@code 00 00 00 00 00 00 00 00 00 00 ff ff c0 a8 00 01}
 * </dl>
 *
 * <p>A few notes about IPv6 "IPv4 mapped" addresses and their observed use in Java.
 *
 * <p>"IPv4 mapped" addresses were originally a representation of IPv4 addresses for use on an IPv6
 * socket that could receive both IPv4 and IPv6 connections (by disabling the {@code IPV6_V6ONLY}

    InetAddress address = InetAddresses.forString(ip);
    boolean isIpv6 = address instanceof Inet6Address;
    assertEquals(bigIntegerIp, InetAddresses.toBigInteger(address));
    assertEquals(
        address,
        isIpv6
            ? InetAddresses.fromIPv6BigInteger(bigIntegerIp)
            : InetAddresses.fromIPv4BigInteger(bigIntegerIp));
  }

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

    enableProtocol(Protocol.HTTP_2)

    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 {

   * Generate an error if the host might be a non-bracketed IPv6 literal.
   *
   * <p>URI formatting requires that IPv6 literals be surrounded by brackets, like "[2001:db8::1]".
   * Chain this call after {@link #fromString(String)} to increase the strictness of the parser, and
   * disallow IPv6 literals that don't contain these brackets.
   *
   * <p>Note that this parser identifies IPv6 literals solely based on the presence of a colon. To

      i += 2
    }
  }
  return result.readUtf8()
}

/**
 * Returns the canonical address for [address]. If [address] is an IPv6 address that is mapped to an
 * IPv4 address, this returns the IPv4-mapped address. Otherwise, this returns [address].
 *
 * https://en.wikipedia.org/wiki/IPv6#IPv4-mapped_IPv6_addresses
 */
internal fun canonicalizeInetAddress(address: ByteArray): ByteArray {
  return when {

_2022-02-01_

**This release introduces fast fallback to better support mixed IPv4+IPv6 networks.** Fast fallback
is what we're calling our implementation of Happy Eyeballs, [RFC 8305][rfc_8305]. With this
feature OkHttp will attempt both IPv6 and IPv4 connections concurrently, keeping whichever connects
first. Fast fallback gives IPv6 connections a 250 ms head start so IPv6 is preferred on networks
where it's available.

							Suffix: "/disk",
							Seq:    getSequences(1, 10, 0),
						},
					},
				},
				nil,
				[][]uint64{{10, 10, 10, 10, 10, 10, 10, 10, 10, 10}},
			},
			true,
		},
		// IPv6 ellipses with hexadecimal expansion
		{
			"http://[2001:3984:3989::{1...a}]/disk{1...10}",
			endpointSet{
				[]ellipses.ArgPattern{
					[]ellipses.Pattern{
						{
							Prefix: "",
							Suffix: "",

type restError string

func (e restError) Error() string {
	return string(e)
}

func (e restError) Timeout() bool {
	return true
}

// Given a string of the form "host", "host:port", or "[ipv6::address]:port",
// return true if the string includes a port.
func hasPort(s string) bool { return strings.LastIndex(s, ":") > strings.LastIndex(s, "]") }

// removeEmptyPort strips the empty port in ":port" to ""