* and response body streams; otherwise resources may be leaked.
   *
   * This method is safe to be called concurrently, but provides limited guarantees. If a transport
   * layer connection has been established (such as a HTTP/2 stream) that is terminated. Otherwise
   * if a socket connection is being established, that is terminated.
   */
  override fun cancel() {
    if (canceled) return // Already canceled.

   *
   *  * 16 bytes: either `OkHttp cache v1\n` if the persisted file is complete. This is another
   *    sequence of bytes if the file is incomplete and should not be used.
   *  * 8 bytes: *n*: upstream data size
   *  * 8 bytes: *m*: metadata size
   *  * *n* bytes: upstream data
   *  * *m* bytes: metadata
   *

 * 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
 * doesn't include the motivating request's HTTP headers or even its full URL; only the target
 * server's hostname is sent to the proxy.
 *

 *
 * Other exception types cancel the current call:
 *
 *  * For synchronous calls made with [Call.execute], the exception is propagated to the caller.
 *
 *  * For asynchronous calls made with [Call.enqueue], an [IOException] is propagated to the caller
 *    indicating that the call was canceled. The interceptor's exception is delivered to the current
 *    thread's [uncaught exception handler][Thread.UncaughtExceptionHandler]. By default this

    connection: Connection,
    call: Call,
  ) {
    if (eventSequence.find { it is ConnectionEvent.ConnectStart && it.connection == connection } != null && connection is RealConnection) {
      if (connection.noNewExchanges) {
        assertThat(eventSequence).matchesPredicate { deque ->
          deque.any { it is NoNewExchanges && it.connection == connection }
        }
      }
    }

 *  Fix: Don't crash in `HttpUrl.topPrivateDomain()` when the hostname is malformed.

 *  Fix: Don't attempt Brotli decompression if the response body is empty.


## Version 4.7.2

_2020-05-20_

 *  Fix: Don't crash inspecting whether the host platform is JVM or Android. With 4.7.0 and 4.7.1 we
    had a crash `IllegalArgumentException: Not a Conscrypt trust manager` because we depended on

 * verification).
 */
private val VERIFY_AS_IP_ADDRESS = "([0-9a-fA-F]*:[0-9a-fA-F:.]*)|([\\d.]+)".toRegex()

/** Returns true if this string is not a host name and might be an IP address. */
fun String.canParseAsIpAddress(): Boolean = VERIFY_AS_IP_ADDRESS.matches(this)

/**
 * Returns true if the length is not valid for DNS (empty or greater than 253 characters), or if any

   * connection to an address fails, OkHttp will retry the connection with the next address until
   * either a connection is made, the set of IP addresses is exhausted, or a limit is exceeded.
   */
  @Throws(UnknownHostException::class)
  fun lookup(hostname: String): List<InetAddress>

  companion object {
    /**

 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package okhttp3

 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */