}

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

    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)
      }

import java.io.IOException
import java.net.HttpURLConnection.HTTP_MOVED_PERM
import java.net.HttpURLConnection.HTTP_MOVED_TEMP
import java.net.HttpURLConnection.HTTP_MULT_CHOICE
import java.net.HttpURLConnection.HTTP_PROXY_AUTH
import java.net.HttpURLConnection.HTTP_SEE_OTHER
import java.net.HttpURLConnection.HTTP_UNAUTHORIZED
import okhttp3.ResponseBody.Companion.asResponseBody
import okhttp3.internal.connection.Exchange

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

          .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")

        .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()