val responseCode = userResponse.code

    val method = userResponse.request.method
    when (responseCode) {
      HTTP_PROXY_AUTH -> {
        val selectedProxy = route!!.proxy
        if (selectedProxy.type() != Proxy.Type.HTTP) {
          throw ProtocolException("Received HTTP_PROXY_AUTH (407) code while not using proxy")
        }
        return client.proxyAuthenticator.authenticate(route, userResponse)
      }

    private void doHandshake () throws IOException, GeneralSecurityException {
        connect();
        try {
            int response = parseResponseCode();
            if ( response != HTTP_UNAUTHORIZED && response != HTTP_PROXY_AUTH ) {
                return;
            }
            NtlmMessage type1 = attemptNegotiation(response);
            if ( type1 == null )
                return; // no NTLM
            int attempt = 0;

    }

    private void doHandshake() throws IOException {
        connect();
        try {
            int response = parseResponseCode();
            if (response != HTTP_UNAUTHORIZED && response != HTTP_PROXY_AUTH) {
                return;
            }
            Type1Message type1 = (Type1Message) attemptNegotiation(response);
            if (type1 == null) return; // no NTLM
            int attempt = 0;

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package okhttp3

import java.io.Closeable
import java.io.IOException
import java.net.HttpURLConnection.HTTP_PROXY_AUTH
import java.net.HttpURLConnection.HTTP_UNAUTHORIZED
import okhttp3.ResponseBody.Companion.asResponseBody
import okhttp3.internal.commonAddHeader
import okhttp3.internal.commonBody

        .build()

    val fakeAuthChallengeResponse =
      Response.Builder()
        .request(proxyConnectRequest)
        .protocol(Protocol.HTTP_1_1)
        .code(HttpURLConnection.HTTP_PROXY_AUTH)
        .message("Preemptive Authenticate")
        .sentRequestAtMillis(-1L)
        .receivedResponseAtMillis(-1L)
        .header("Proxy-Authenticate", "OkHttp-Preemptive")
        .build()

          .request(nextRequest)
          .build()
      tunnelCodec.skipConnectBody(response)

      when (response.code) {
        HttpURLConnection.HTTP_OK -> return null

        HttpURLConnection.HTTP_PROXY_AUTH -> {
          nextRequest = route.address.proxyAuthenticator.authenticate(route, response)
            ?: throw IOException("Failed to authenticate with proxy")

        .proxyAuthenticator { _: Route?, response: Response? ->
          assertThat(response!!.request.method).isEqualTo("CONNECT")
          assertThat(response.code).isEqualTo(HttpURLConnection.HTTP_PROXY_AUTH)
          assertThat(response.request.url.host).isEqualTo("android.com")
          val challenges = response.challenges()
          assertThat(challenges[0].scheme).isEqualTo("OkHttp-Preemptive")

        .addHeader("Expires: " + formatDate(1, TimeUnit.HOURS))
        .code(responseCode)
        .body("ABCDE")
        .addHeader("WWW-Authenticate: challenge")
    when (responseCode) {
      HttpURLConnection.HTTP_PROXY_AUTH -> {
        builder.addHeader("Proxy-Authenticate: Basic realm=\"protected area\"")
      }

      HttpURLConnection.HTTP_UNAUTHORIZED -> {