protected boolean handleLocalTunnel(
      TrackerWebPageRequest request, TrackerWebPageResponse response) throws IOException {
    start();

    if (SRP_VERIFIER == null || !active) {

      throw (new IOException("Secure pairing is not enabled"));
    }

    boolean good_request = false;

    try {
      // remove /pairing/tunnel/

      String url = request.getURL().substring(16);

      int q_pos = url.indexOf('?');

      Map<String, String> args = new HashMap<String, String>();

      if (q_pos != -1) {

        String args_str = url.substring(q_pos + 1);

        String[] bits = args_str.split("&");

        for (String arg : bits) {

          String[] x = arg.split("=");

          if (x.length == 2) {

            args.put(x[0].toLowerCase(), x[1]);
          }
        }

        url = url.substring(0, q_pos);
      }

      if (url.startsWith("create")) {

        String ac = args.get("ac");
        String sid = args.get("sid");

        if (ac == null || sid == null) {

          throw (new IOException("Access code or service id missing"));
        }

        if (!ac.equals(manager.peekAccessCode())) {

          throw (new IOException("Invalid access code"));
        }

        PairedServiceImpl ps = manager.getService(sid);

        if (ps == null) {

          good_request = true;

          throw (new IOException("Service '" + sid + "' not registered"));
        }

        PairedServiceRequestHandler handler = ps.getHandler();

        if (handler == null) {

          good_request = true;

          throw (new IOException("Service '" + sid + "' has no handler registered"));
        }

        JSONObject json = new JSONObject();

        JSONObject result = new JSONObject();

        json.put("result", result);

        byte[] ss = new byte[] {SRP_SALT[0], SRP_SALT[1], SRP_SALT[2], SRP_SALT[3]};

        long tunnel_id = RandomUtils.nextSecureAbsoluteLong();

        String tunnel_name = Base32.encode(ss) + "_" + tunnel_id;

        synchronized (local_server_map) {
          long diff = SystemTime.getMonotonousTime() - last_local_server_create_time;

          if (diff < 5000) {

            try {
              long sleep = 5000 - diff;

              System.out.println("Sleeping for " + sleep + " before starting srp");

              Thread.sleep(sleep);

            } catch (Throwable e) {
            }
          }

          SRP6Server server = new SRP6Server();

          server.init(N_3072, G_3072, SRP_VERIFIER, new SHA256Digest(), RandomUtils.SECURE_RANDOM);

          BigInteger B = server.generateServerCredentials();

          local_server_map.put(tunnel_name, new Object[] {server, handler, null, null});

          last_local_server_create_time = SystemTime.getMonotonousTime();

          total_local_servers++;

          result.put("srp_salt", Base32.encode(SRP_SALT));

          result.put("srp_b", Base32.encode(B.toByteArray()));

          Map<String, String> headers = request.getHeaders();

          String host = headers.get("host");

          // remove port number

          int pos = host.lastIndexOf("]");

          if (pos != -1) {

            // ipv6 literal

            host = host.substring(0, pos + 1);

          } else {

            pos = host.indexOf(':');

            if (pos != -1) {

              host = host.substring(0, pos);
            }
          }

          String abs_url = request.getAbsoluteURL().toString();

          // unfortunately there is some nasty code that uses a configured tracker
          // address as the default host

          abs_url = UrlUtils.setHost(new URL(abs_url), host).toExternalForm();

          pos = abs_url.indexOf("/create");

          String tunnel_url = abs_url.substring(0, pos) + "/id/" + tunnel_name;

          result.put("url", tunnel_url);
        }

        response.getOutputStream().write(JSONUtils.encodeToJSON(json).getBytes("UTF-8"));

        response.setContentType("application/json; charset=UTF-8");

        response.setGZIP(true);

        good_request = true;

        return (true);

      } else if (url.startsWith("id/")) {

        String tunnel_name = url.substring(3);

        Object[] entry;

        synchronized (local_server_map) {
          entry = local_server_map.get(tunnel_name);

          if (entry == null) {

            good_request = true;

            throw (new IOException("Unknown tunnel id"));
          }
        }

        String srp_a = args.get("srp_a");
        String enc_data = args.get("enc_data");
        String enc_iv = args.get("enc_iv");

        if (srp_a != null && enc_data != null && enc_iv != null) {

          try {
            synchronized (local_server_map) {
              long diff = SystemTime.getMonotonousTime() - last_local_server_agree_time;

              if (diff < 5000) {

                try {
                  long sleep = 5000 - diff;

                  System.out.println("Sleeping for " + sleep + " before completing srp");

                  Thread.sleep(sleep);

                } catch (Throwable e) {
                }
              }
            }

            JSONObject json = new JSONObject();

            JSONObject result = new JSONObject();

            json.put("result", result);

            SRP6Server server = (SRP6Server) entry[0];

            BigInteger A = new BigInteger(Base32.decode(srp_a));

            BigInteger serverS = server.calculateSecret(A);

            byte[] shared_secret = serverS.toByteArray();

            Cipher decipher = Cipher.getInstance("AES/CBC/PKCS5Padding");

            byte[] key = new byte[16];

            System.arraycopy(shared_secret, 0, key, 0, 16);

            SecretKeySpec secret = new SecretKeySpec(key, "AES");

            decipher.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(Base32.decode(enc_iv)));

            byte[] dec = decipher.doFinal(Base32.decode(enc_data));

            JSONObject dec_json = (JSONObject) JSONUtils.decodeJSON(new String(dec, "UTF-8"));

            String tunnel_url = (String) dec_json.get("url");

            if (!tunnel_url.contains(tunnel_name)) {

              throw (new IOException("Invalid tunnel url"));
            }

            String endpoint_url = (String) dec_json.get("endpoint");

            entry[2] = secret;
            entry[3] = endpoint_url;

            result.put("state", "activated");

            response.getOutputStream().write(JSONUtils.encodeToJSON(json).getBytes("UTF-8"));

            response.setContentType("application/json; charset=UTF-8");

            response.setGZIP(true);

            good_request = true;

            return (true);

          } catch (Throwable e) {

            throw (new IOException(Debug.getNestedExceptionMessage(e)));

          } finally {

            last_local_server_agree_time = SystemTime.getMonotonousTime();
          }
        } else if (args.containsKey("close")) {

          synchronized (local_server_map) {
            local_server_map.remove(tunnel_name);
          }

          good_request = true;

          return (true);

        } else {

          PairedServiceRequestHandler request_handler = (PairedServiceRequestHandler) entry[1];

          SecretKeySpec secret = (SecretKeySpec) entry[2];

          String endpoint_url = (String) entry[3];

          if (secret == null) {

            throw (new IOException("auth not completed"));
          }

          byte[] request_data = FileUtil.readInputStreamAsByteArray(request.getInputStream());

          try {
            byte[] decrypted;

            {
              byte[] IV = new byte[16];

              System.arraycopy(request_data, 0, IV, 0, IV.length);

              Cipher decipher = Cipher.getInstance("AES/CBC/PKCS5Padding");

              decipher.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(IV));

              decrypted = decipher.doFinal(request_data, 16, request_data.length - 16);
            }

            byte[] reply_bytes =
                request_handler.handleRequest(
                    request.getClientAddress2().getAddress(), endpoint_url, decrypted);

            {
              Cipher encipher = Cipher.getInstance("AES/CBC/PKCS5Padding");

              encipher.init(Cipher.ENCRYPT_MODE, secret);

              AlgorithmParameters params = encipher.getParameters();

              byte[] IV = params.getParameterSpec(IvParameterSpec.class).getIV();

              byte[] enc = encipher.doFinal(reply_bytes);

              byte[] rep_bytes = new byte[IV.length + enc.length];

              System.arraycopy(IV, 0, rep_bytes, 0, IV.length);
              System.arraycopy(enc, 0, rep_bytes, IV.length, enc.length);

              response.getOutputStream().write(rep_bytes);

              response.setContentType("application/octet-stream");

              good_request = true;

              return (true);
            }
          } catch (Throwable e) {

            throw (new IOException(Debug.getNestedExceptionMessage(e)));
          }
        }
      }

      throw (new IOException("Unknown tunnel operation"));

    } finally {

      if (!good_request) {

        manager.recordRequest(
            "SRP", request.getClientAddress2().getAddress().getHostAddress(), false);
      }
    }
  }
  private boolean createTunnel(
      InetAddress originator,
      long session,
      String sid,
      SecretKeySpec secret,
      String tunnel_url,
      String endpoint_url) {
    PairedServiceImpl ps = manager.getService(sid);

    if (ps == null) {

      Debug.out("Service '" + sid + "' not registered");

      return (false);
    }

    PairedServiceRequestHandler handler = ps.getHandler();

    if (handler == null) {

      Debug.out("Service '" + sid + "' has no handler registered");

      return (false);
    }

    String key = originator.getHostAddress() + ":" + session + ":" + sid;

    synchronized (tunnels) {
      PairManagerTunnel existing = tunnels.get(key);

      if (existing != null) {

        return (true);
      }

      if (tunnels.size() > MAX_TUNNELS) {

        long oldest_active = Long.MAX_VALUE;
        PairManagerTunnel oldest_tunnel = null;

        for (PairManagerTunnel t : tunnels.values()) {

          long at = t.getLastActive();

          if (at < oldest_active) {

            oldest_active = at;
            oldest_tunnel = t;
          }
        }

        oldest_tunnel.destroy();

        tunnels.remove(oldest_tunnel.getKey());
      }

      PairManagerTunnel tunnel =
          new PairManagerTunnel(
              this, key, originator, sid, handler, secret, tunnel_url, endpoint_url);

      tunnels.put(key, tunnel);

      System.out.println("Created pair manager tunnel: " + tunnel.getString());
    }

    return (true);
  }