*
   * See also [Starting HTTP/2 with Prior Knowledge][rfc_7540_34].
   *
   * [rfc_7540_34]: https://tools.ietf.org/html/rfc7540.section-3.4
   */
  H2_PRIOR_KNOWLEDGE("h2_prior_knowledge"),

  /**
   * QUIC (Quick UDP Internet Connection) is a new multiplexed and secure transport atop UDP,
   * designed from the ground up and optimized for HTTP/2 semantics. HTTP/1.1 semantics are layered

    assertThat(get("http/1.1")).isEqualTo(Protocol.HTTP_1_1)
    assertThat(get("spdy/3.1")).isEqualTo(Protocol.SPDY_3)
    assertThat(get("h2")).isEqualTo(Protocol.HTTP_2)
    assertThat(get("h2_prior_knowledge")).isEqualTo(Protocol.H2_PRIOR_KNOWLEDGE)
    assertThat(get("quic")).isEqualTo(Protocol.QUIC)
    assertThat(get("h3")).isEqualTo(Protocol.HTTP_3)
    assertThat(get("h3-29")).isEqualTo(Protocol.HTTP_3)
  }

  @Test

    server.setProtocols(Collections.singletonList(Protocol.H2_PRIOR_KNOWLEDGE));
    server.enqueue(new MockResponse().setBody("hello"));
    server.start();

    OkHttpClient client = new OkHttpClient.Builder()
        .socketFactory(new UnixDomainSocketFactory(socketFile))
        .protocols(Collections.singletonList(Protocol.H2_PRIOR_KNOWLEDGE))
        .build();

    Request request = new Request.Builder()

  private val http2Connection: Http2Connection,
) : ExchangeCodec {
  @Volatile private var stream: Http2Stream? = null

  private val protocol: Protocol =
    if (Protocol.H2_PRIOR_KNOWLEDGE in client.protocols) {
      Protocol.H2_PRIOR_KNOWLEDGE
    } else {
      Protocol.HTTP_2
    }

  @Volatile
  private var canceled = false

  override fun createRequestBody(
    request: Request,
    contentLength: Long,

/**
 * Used when we were unsuccessful in the planning phase of a connection:
 *
 *  * A DNS lookup failed
 *  * The configuration is incapable of carrying the request, such as when the client is configured
 *    to use `H2_PRIOR_KNOWLEDGE` but the URL's scheme is `https:`.
 *  * Preemptive proxy authentication failed.
 *
 * Planning failures are not necessarily fatal. For example, even if we can't DNS lookup the first

   *
   * [rfc_2817]: http://www.ietf.org/rfc/rfc2817.txt
   */
  fun requiresTunnel(): Boolean {
    if (proxy.type() != Proxy.Type.HTTP) return false
    return (address.sslSocketFactory != null) ||
      (Protocol.H2_PRIOR_KNOWLEDGE in address.protocols)
  }

  override fun equals(other: Any?): Boolean {
    return other is Route &&
      other.address == address &&
      other.proxy == proxy &&
      other.socketAddress == socketAddress