var nextRequest = tunnelRequest!!
    // Make an SSL Tunnel on the first message pair of each SSL + proxy connection.
    val url = route.address.url
    val requestLine = "CONNECT ${url.toHostHeader(includeDefaultPort = true)} HTTP/1.1"
    while (true) {
      val tunnelCodec =
        Http1ExchangeCodec(
          // No client for CONNECT tunnels:
          client = null,
          carrier = this,

 * ## Preemptive Authentication
 *
 * To make HTTPS calls using an HTTP proxy server OkHttp must first negotiate a connection with
 * the proxy. This proxy connection is called a "TLS Tunnel" and is specified by
 * [RFC 2817][1]. The HTTP CONNECT request that creates this tunnel connection is special: it
 * does not participate in any [interceptors][Interceptor] or [event listeners][EventListener]. It

   * That may happen later by the connection pool thread.
   */
  fun cancel()

  /**
   * Carries an exchange. This is usually a connection, but it could also be a connect plan for
   * CONNECT tunnels. Note that CONNECT tunnels are significantly less capable than connections.
   */
  interface Carrier {
    val route: Route

    fun trackFailure(
      call: RealCall,
      e: IOException?,
    )

      connectionSpecIndex = -1,
      isTlsFallback = false,
    )
  }

  /**
   * Returns a request that creates a TLS tunnel via an HTTP proxy. Everything in the tunnel request
   * is sent unencrypted to the proxy server, so tunnels include only the minimum set of headers.
   * This avoids sending potentially sensitive data like HTTP cookies to the proxy unencrypted.
   *

     *   <li>TRACE - Echoes back the received request, used for debugging.</li>
     *   <li>CONNECT - Converts the request connection to a transparent TCP/IP tunnel.</li>
     * </ul>
     */
    public enum Method {
        /**
         * HTTP GET method.
         */
        GET,
        /**
         * HTTP POST method.
         */
        POST,

    }

    /**
     * Respond to `CONNECT` requests until a non-tunnel response is peeked. Returns true if further
     * calls should be attempted on the socket.
     */
    @Throws(IOException::class, InterruptedException::class)
    private fun processTunnelRequests(): Boolean {
      if (!dispatcher.peek().inTunnel) return true // No tunnel requests.

      val socket = MockWebServerSocket(raw)
      while (true) {

              .build(),
        ),
      )
    val response = call.execute()
    assertThat(response.isSuccessful).isTrue()

    server.takeRequest() // Discard the CONNECT tunnel.
    return server.takeRequest()
  }

_2022-06-08_

 *  Fix: Change how `H2_PRIOR_KNOWLEDGE` works with HTTP proxies. Previously OkHttp assumed the
    proxy itself was a prior knowledge HTTP/2 server. With this update, OkHttp attempts a `CONNECT`
    tunnel just as it would with HTTPS. For prior knowledge with proxies OkHttp's is now consistent
    with these curl arguments:

    ```
    curl \
      --http2-prior-knowledge \
      --proxy localhost:8888 \

     * doing HTTPS through an HTTP proxy, or HTTP/2 prior knowledge through an HTTP proxy.
     *
     * When a new connection is received, all in-tunnel responses are served before the connection is
     * upgraded to HTTPS or HTTP/2.
     */
    public fun inTunnel(): Builder =
      apply {
        removeHeader("Content-Length")
        inTunnel = true

 * Implementations for common types can be found in {@link Funnels}.
 *
 * <p>Note that serialization of {@linkplain BloomFilter bloom filters} requires the proper
 * serialization of funnels. When possible, it is recommended that funnels be implemented as a
 * single-element enum to maintain serialization guarantees. See Effective Java (2nd Edition), Item