_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: "",

  @Test
  fun testToCanonicalHost() {
    // IPv4
    assertThat("127.0.0.1".toCanonicalHost()).isEqualTo("127.0.0.1")
    assertThat("1.2.3.4".toCanonicalHost()).isEqualTo("1.2.3.4")

    // IPv6
    assertThat("::1".toCanonicalHost()).isEqualTo("::1")
    assertThat("2001:db8::1".toCanonicalHost()).isEqualTo("2001:db8::1")
    assertThat("::ffff:192.168.0.1".toCanonicalHost()).isEqualTo("192.168.0.1")
    assertThat(

      val inetAddress = socket.localAddress

      var hostname = inetAddress.hostName
      if (inetAddress is Inet6Address && hostname.contains(':')) {
        // hostname is likely some form representing the IPv6 bytes
        // 2001:0db8:85a3:0000:0000:8a2e:0370:7334
        // 2001:db8:85a3::8a2e:370:7334
        // ::1
        hostname = "[$hostname]"
      }

      val localPort = socket.localPort

`--node-cidr-mask-size-ipv6 int32`     Default: 64. Mask size for IPv6 node-cidr in dual-stack cluster.

    These 2 flags can be used only for dual-stack clusters. For non dual-stack clusters, continue to use  `--node-cidr-mask-size` flag to configure the mask size.

        private final int flags;
        
        public static final int IPV4 = 0x01;
        public static final int IPV6 = 0x02;
        
        public WitnessIPAddress(InetAddress address) {
            this.address = address;
            this.flags = address.getAddress().length == 4 ? IPV4 : IPV6;
        }
        
        public InetAddress getAddress() { return address; }

          }

          connectionUser.dnsEnd(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) {

 *  Fix: Don't use a cryptographic random number generator for web sockets. Some Android devices
    implement `SecureRandom` incorrectly!
 *  Fix: Correctly canonicalize IPv6 addresses in `HttpUrl`. This prevented OkHttp from trusting
    HTTPS certificates issued to certain IPv6 addresses.
 *  Fix: Don't reuse connections after an unsuccessful `Expect: 100-continue`.

- Fixed the EndpointSliceController to correctly create endpoints for IPv6-only pods.
  
  Fixed the EndpointController to allow IPv6 headless services, if the IPv6DualStack
  feature gate is enabled, by specifying `ipFamily: IPv6` on the service. (This already

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.