/**
   * Perform the actual version check by connecting to the version server.
   *
   * @param data_to_send version message
   * @return version reply
   * @throws Exception if the server check connection fails
   */
  private Map performVersionCheck(
      Map data_to_send, boolean use_az_message, boolean use_http, boolean v6) throws Exception {
    Exception error = null;
    Map reply = null;

    if (use_http) {

      try {
        reply = executeHTTP(data_to_send, v6);

        reply.put("protocol_used", "HTTP");

        error = null;
      } catch (IOException e) {
        error = e;
      } catch (Exception e) {
        Debug.printStackTrace(e);
        error = e;
      }
    }

    if (reply == null && use_az_message) {

      try {
        reply = executeAZMessage(data_to_send, v6);

        reply.put("protocol_used", "AZMSG");
      } catch (IOException e) {
        error = e;
      } catch (Exception e) {
        Debug.printStackTrace(e);
        error = e;
      }
    }
    if (error != null) {

      throw (error);
    }

    if (Logger.isEnabled())
      Logger.log(
          new LogEvent(
              LOGID,
              "VersionCheckClient server "
                  + "version check successful. Received "
                  + reply.size()
                  + " reply keys."));

    if (v6) {

      last_check_time_v6 = SystemTime.getCurrentTime();

    } else {

      last_check_time_v4 = SystemTime.getCurrentTime();
    }

    return reply;
  }
  private Map executeHTTP(Map data_to_send, boolean v6) throws Exception {

    if (v6 && !enable_v6) {

      throw (new Exception("IPv6 is disabled"));
    }

    String host = getHost(v6, HTTP_SERVER_ADDRESS_V6, HTTP_SERVER_ADDRESS_V4);

    if (Logger.isEnabled())
      Logger.log(
          new LogEvent(
              LOGID,
              "VersionCheckClient retrieving "
                  + "version information from "
                  + host
                  + ":"
                  + HTTP_SERVER_PORT
                  + " via HTTP"));

    String url_str =
        "http://"
            + (v6 ? UrlUtils.convertIPV6Host(host) : host)
            + (HTTP_SERVER_PORT == 80 ? "" : (":" + HTTP_SERVER_PORT))
            + "/version?";

    url_str +=
        URLEncoder.encode(new String(BEncoder.encode(data_to_send), "ISO-8859-1"), "ISO-8859-1");

    URL url = new URL(url_str);

    HttpURLConnection url_connection = (HttpURLConnection) url.openConnection();

    url_connection.connect();

    try {
      InputStream is = url_connection.getInputStream();

      Map reply = BDecoder.decode(new BufferedInputStream(is));

      preProcessReply(reply, v6);

      return (reply);

    } finally {

      url_connection.disconnect();
    }
  }
  private Map executeAZMessage(Map data_to_send, boolean v6) throws Exception {

    if (v6 && !enable_v6) {

      throw (new Exception("IPv6 is disabled"));
    }

    String host = getHost(v6, AZ_MSG_SERVER_ADDRESS_V6, AZ_MSG_SERVER_ADDRESS_V4);

    if (Logger.isEnabled())
      Logger.log(
          new LogEvent(
              LOGID,
              "VersionCheckClient retrieving "
                  + "version information from "
                  + host
                  + ":"
                  + AZ_MSG_SERVER_PORT));

    ClientMessageService msg_service = null;
    Map reply = null;

    try {
      msg_service =
          ClientMessageServiceClient.getServerService(host, AZ_MSG_SERVER_PORT, MESSAGE_TYPE_ID);

      msg_service.sendMessage(data_to_send); // send our version message

      reply = msg_service.receiveMessage(); // get the server reply

      preProcessReply(reply, v6);

    } finally {

      if (msg_service != null) {

        msg_service.close();
      }
    }

    return (reply);
  }
  private Map executeTCP(Map data_to_send, InetAddress bind_ip, int bind_port, boolean v6)
      throws Exception {
    if (v6 && !enable_v6) {

      throw (new Exception("IPv6 is disabled"));
    }

    String host = getHost(v6, TCP_SERVER_ADDRESS_V6, TCP_SERVER_ADDRESS_V4);

    if (Logger.isEnabled())
      Logger.log(
          new LogEvent(
              LOGID,
              "VersionCheckClient retrieving "
                  + "version information from "
                  + host
                  + ":"
                  + TCP_SERVER_PORT
                  + " via TCP"));

    String get_str = getHTTPGetString(data_to_send, false, v6);

    Socket socket = null;

    try {
      socket = new Socket();

      if (bind_ip != null) {

        socket.bind(new InetSocketAddress(bind_ip, bind_port));

      } else if (bind_port != 0) {

        socket.bind(new InetSocketAddress(bind_port));
      }

      socket.setSoTimeout(10000);

      socket.connect(new InetSocketAddress(host, TCP_SERVER_PORT), 10000);

      OutputStream os = socket.getOutputStream();

      os.write(get_str.getBytes("ISO-8859-1"));

      os.flush();

      InputStream is = socket.getInputStream();

      byte[] buffer = new byte[1];

      String header = "";

      int content_length = -1;

      while (true) {

        int len = is.read(buffer);

        if (len <= 0) {

          break;
        }

        header += (char) buffer[0];

        if (header.endsWith("\r\n\r\n")) {

          header = header.toLowerCase(MessageText.LOCALE_ENGLISH);

          int pos = header.indexOf("content-length:");

          if (pos == -1) {

            throw (new IOException("content length missing"));
          }

          header = header.substring(pos + 15);

          pos = header.indexOf('\r');

          header = header.substring(0, pos).trim();

          content_length = Integer.parseInt(header);

          if (content_length > 10000) {

            throw (new IOException("content length too large"));
          }

          break;
        }

        if (header.length() > 2048) {

          throw (new IOException("header too large"));
        }
      }

      ByteArrayOutputStream baos = new ByteArrayOutputStream(content_length);

      buffer = new byte[content_length];

      while (content_length > 0) {

        int len = is.read(buffer);

        if (len <= 0) {

          break;
        }

        baos.write(buffer, 0, len);

        content_length -= len;
      }

      if (content_length != 0) {

        throw (new IOException("error reading reply"));
      }

      byte[] reply_bytes = baos.toByteArray();

      Map reply = BDecoder.decode(new BufferedInputStream(new ByteArrayInputStream(reply_bytes)));

      preProcessReply(reply, v6);

      return (reply);

    } finally {

      if (socket != null) {

        try {
          socket.close();

        } catch (Throwable e) {

        }
      }
    }
  }
  protected Map getVersionCheckInfoSupport(
      String reason, boolean only_if_cached, boolean force, boolean v6) {
    try {
      synchronized (listeners) {
        if (REASON_UPDATE_CHECK_START.equals(reason)) {
          startCheckRan = true;
        }
        for (VersionCheckClientListener l : listeners) {
          l.versionCheckStarted(reason);
        }
      }
    } catch (Throwable t) {
      Debug.out(t);
    }
    if (v6) {

      if (enable_v6) {

        try {
          check_mon.enter();

          long time_diff = SystemTime.getCurrentTime() - last_check_time_v6;

          force = force || time_diff > CACHE_PERIOD || time_diff < 0;

          if (last_check_data_v6 == null || last_check_data_v6.size() == 0 || force) {
            // if we've never checked before then we go ahead even if the "only_if_cached"
            // flag is set as its had not chance of being cached yet!
            if (only_if_cached && last_check_data_v6 != null) {
              return (new HashMap());
            }
            try {
              last_check_data_v6 =
                  performVersionCheck(constructVersionCheckMessage(reason), true, true, true);

              if (last_check_data_v6 != null && last_check_data_v6.size() > 0) {

                COConfigurationManager.setParameter("versioncheck.cache.v6", last_check_data_v6);
              }
            } catch (SocketException t) {
              // internet is broken
              // Debug.out(t.getClass().getName() + ": " + t.getMessage());
            } catch (UnknownHostException t) {
              // dns is broken
              // Debug.out(t.getClass().getName() + ": " + t.getMessage());
            } catch (Throwable t) {
              Debug.out(t);
              last_check_data_v6 = new HashMap();
            }
          } else {
            Logger.log(
                new LogEvent(
                    LOGID,
                    "VersionCheckClient is using "
                        + "cached version check info. Using "
                        + last_check_data_v6.size()
                        + " reply keys."));
          }
        } finally {
          check_mon.exit();
        }
      }

      if (last_check_data_v6 == null) last_check_data_v6 = new HashMap();

      return last_check_data_v6;

    } else {

      try {
        check_mon.enter();

        long time_diff = SystemTime.getCurrentTime() - last_check_time_v4;

        force = force || time_diff > CACHE_PERIOD || time_diff < 0;

        if (last_check_data_v4 == null || last_check_data_v4.size() == 0 || force) {
          // if we've never checked before then we go ahead even if the "only_if_cached"
          // flag is set as its had not chance of being cached yet!
          if (only_if_cached && last_check_data_v4 != null) {
            return (new HashMap());
          }
          try {
            last_check_data_v4 =
                performVersionCheck(constructVersionCheckMessage(reason), true, true, false);

            if (last_check_data_v4 != null && last_check_data_v4.size() > 0) {

              COConfigurationManager.setParameter("versioncheck.cache.v4", last_check_data_v4);
            }

            // clear down any plugin-specific data that has successfully been sent to the version
            // server

            try {
              if (AzureusCoreFactory.isCoreAvailable()) {

                // installed plugin IDs
                PluginInterface[] plugins =
                    AzureusCoreFactory.getSingleton().getPluginManager().getPluginInterfaces();

                for (int i = 0; i < plugins.length; i++) {

                  PluginInterface plugin = plugins[i];

                  Map data =
                      plugin
                          .getPluginconfig()
                          .getPluginMapParameter("plugin.versionserver.data", null);

                  if (data != null) {

                    plugin
                        .getPluginconfig()
                        .setPluginMapParameter("plugin.versionserver.data", new HashMap());
                  }
                }
              }
            } catch (Throwable e) {
            }
          } catch (UnknownHostException t) {
            // no internet
            Debug.outNoStack(
                "VersionCheckClient - " + t.getClass().getName() + ": " + t.getMessage());
          } catch (IOException t) {
            // General connection problem.
            Debug.outNoStack(
                "VersionCheckClient - " + t.getClass().getName() + ": " + t.getMessage());
          } catch (Throwable t) {
            Debug.out(t);
            last_check_data_v4 = new HashMap();
          }
        } else {
          if (Logger.isEnabled())
            Logger.log(
                new LogEvent(
                    LOGID,
                    "VersionCheckClient is using "
                        + "cached version check info. Using "
                        + last_check_data_v4.size()
                        + " reply keys."));
        }
      } finally {
        check_mon.exit();
      }

      if (last_check_data_v4 == null) last_check_data_v4 = new HashMap();

      last_feature_flag_cache_time = 0;

      return last_check_data_v4;
    }
  }