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

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

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

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

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

            return false;
        }
    }

    /**
     * Formats an IP address string for use in a URL.
     * IPv6 addresses are wrapped in brackets, IPv4 addresses are returned as-is.
     *
     * @param address the IP address string to format
     * @return the formatted address (IPv6 with brackets, IPv4 unchanged)
     */
    public static String formatForUrl(final String address) {
        if (address == null) {

        IdnDnsResolver resolver = new IdnDnsResolver();

        // Test IPv6 loopback address with brackets
        String host = "[::1]";
        InetAddress[] addresses = resolver.resolve(host);
        assertNotNull(addresses);
        assertTrue(addresses.length > 0);
        // IPv6 loopback can be represented as ::1 or 0:0:0:0:0:0:0:1
        String hostAddress = addresses[0].getHostAddress();

FESS_JAVA_OPTS="$FESS_JAVA_OPTS -Djava.awt.headless=true"

# maximum # keep-alive connections to maintain at once
FESS_JAVA_OPTS="$FESS_JAVA_OPTS -Dhttp.maxConnections=20"

# Force the JVM to use IPv4 stack
if [ "x$FESS_USE_IPV4" != "x" ]; then
  FESS_JAVA_OPTS="$FESS_JAVA_OPTS -Djava.net.preferIPv4Stack=true"
fi

# proxy
if [ "x$FESS_PROXY_HOST" != "x" ]; then

    /**
     * Checks if EPSV command should be used with IPv4.
     *
     * @return True if EPSV with IPv4 is enabled, false otherwise
     */
    public boolean isUseEPSVwithIPv4() {
        return useEPSVwithIPv4;
    }

    /**
     * Sets whether EPSV command should be used with IPv4.
     *
     * @param useEPSVwithIPv4 True to enable EPSV with IPv4, false to disable
     */

set FESS_JAVA_OPTS=%FESS_JAVA_OPTS% -Djava.awt.headless=true

REM maximum # keep-alive connections to maintain at once
set FESS_JAVA_OPTS=%FESS_JAVA_OPTS% -Dhttp.maxConnections=20

REM Force the JVM to use IPv4 stack
if NOT "%FESS_USE_IPV4%" == "" (
set FESS_JAVA_OPTS=%FESS_JAVA_OPTS% -Djava.net.preferIPv4Stack=true
)

REM proxy
if NOT "%FESS_PROXY_HOST%" == "" (

          }

          call.eventListener.dnsEnd(call, socketHost, result)
          result
        }

      // Try each address for best behavior in mixed IPv4/IPv6 environments.
      val orderedAddresses =
        when {
          fastFallback -> reorderForHappyEyeballs(addresses)
          else -> addresses
        }

      for (inetAddress in orderedAddresses) {

_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.

OkHttp perseveres when the network is troublesome: it will silently recover from common connection
problems. If your service has multiple IP addresses, OkHttp will attempt alternate addresses if the
first connect fails. This is necessary for IPv4+IPv6 and services hosted in redundant data
centers. OkHttp supports modern TLS features (TLS 1.3, ALPN, certificate pinning). It can be
configured to fall back for broad connectivity.