*     possible for shared exchanges to make requests to different host names! See
 *     [RealConnection.isEligible] for details.
 *
 *  3. Attempt plans from prior connect attempts for this call. These occur as either follow-ups to
 *     failed connect attempts (such as trying the next [ConnectionSpec]), or as attempts that lost
 *     a race in fast follow-up.
 *

 */
package okhttp3

import java.net.InetAddress
import java.net.UnknownHostException
import okhttp3.Dns.Companion.SYSTEM

/**
 * A domain name service that resolves IP addresses for host names. Most applications will use the
 * [system DNS service][SYSTEM], which is the default. Some applications may provide their own
 * implementation to use a different DNS server, to prefer IPv6 addresses, to prefer IPv4 addresses,

     * Sets the socket factory and trust manager used to secure HTTPS connections. If unset, the
     * system defaults will be used.
     *
     * Most applications should not call this method, and instead use the system defaults. Those
     * classes include special optimizations that can be lost if the implementations are decorated.
     *
     * If necessary, you can create and configure the defaults yourself with the following code:
     *

 * <li><dfn>Private Remote Repository</dfn>: Organizations often maintain their own private remote repositories, which may host proprietary or custom-built artifacts that are not available in the central repository. These repositories can be managed using tools like Apache Archiva,...

// the text of the most recently returned token is, and where it was found.
// The underlying scanner elides all spaces except newline, so the input looks like a stream of
// Tokens; original spacing is lost but we don't need it.
type TokenReader interface {
	// Next returns the next token.
	Next() ScanToken
	// The following methods all refer to the most recent token returned by Next.

      }

      // Force handshake. This can throw!
      sslSocket.startHandshake()
      // block for session establishment
      val sslSocketSession = sslSocket.session
      val unverifiedHandshake = sslSocketSession.handshake()

      // Verify that the socket's certificates are acceptable for the target host.

And as you would be building the container image again and again during development to check that your code changes are working, there's a lot of accumulated time this would save.

  /**
   * Test connecting to the main host then an alternative, although only subject alternative names
   * are used if present no special consideration of common name.
   */
  @Test
  fun commonThenAlternative() {
    server.enqueue(MockResponse())
    server.enqueue(MockResponse())
    assert200Http2Response(execute(url), server.hostName)
    val sanUrl = url.newBuilder().host("san.com").build()

{* ../../docs_src/advanced_middleware/tutorial001_py39.py hl[2,6] *}

## `TrustedHostMiddleware` { #trustedhostmiddleware }

Enforces that all incoming requests have a correctly set `Host` header, in order to guard against HTTP Host Header attacks.

{* ../../docs_src/advanced_middleware/tutorial002_py39.py hl[2,6:8] *}

The following arguments are supported:

* <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/X-Forwarded-Host" class="external-link" target="_blank">X-Forwarded-Host</a>

///

Nevertheless, as the **application server** doesn't know it is behind a trusted **proxy**, by default, it wouldn't trust those headers.