/**
   * Returns a newly created session between the server and a client. The session will be created
   * and returned only if correct name/prefix (i.e. 'stream' or 'flash') and namespace were provided
   * by the client.
   *
   * @param serverName the name of the server where the session is connecting to.
   * @param xpp the parser that is reading the provided XML through the connection.
   * @param connection the connection with the client.
   * @return a newly created session between the server and a client.
   * @throws org.xmlpull.v1.XmlPullParserException if an error occurs while parsing incoming data.
   */
  public static LocalClientSession createSession(
      String serverName, XmlPullParser xpp, Connection connection) throws XmlPullParserException {
    boolean isFlashClient = xpp.getPrefix().equals("flash");
    connection.setFlashClient(isFlashClient);

    // Conduct error checking, the opening tag should be 'stream'
    // in the 'etherx' namespace
    if (!xpp.getName().equals("stream") && !isFlashClient) {
      throw new XmlPullParserException(LocaleUtils.getLocalizedString("admin.error.bad-stream"));
    }

    if (!xpp.getNamespace(xpp.getPrefix()).equals(ETHERX_NAMESPACE)
        && !(isFlashClient && xpp.getNamespace(xpp.getPrefix()).equals(FLASH_NAMESPACE))) {
      throw new XmlPullParserException(LocaleUtils.getLocalizedString("admin.error.bad-namespace"));
    }

    if (!allowedIPs.isEmpty()) {
      String hostAddress = "Unknown";
      // The server is using a whitelist so check that the IP address of the client
      // is authorized to connect to the server
      try {
        hostAddress = connection.getHostAddress();
      } catch (UnknownHostException e) {
        // Do nothing
      }
      if (!isAllowed(connection)) {
        // Client cannot connect from this IP address so end the stream and
        // TCP connection
        Log.debug(
            "LocalClientSession: Closed connection to client attempting to connect from: "
                + hostAddress);
        // Include the not-authorized error in the response
        StreamError error = new StreamError(StreamError.Condition.not_authorized);
        connection.deliverRawText(error.toXML());
        // Close the underlying connection
        connection.close();
        return null;
      }
    }

    // Default language is English ("en").
    String language = "en";
    // Default to a version of "0.0". Clients written before the XMPP 1.0 spec may
    // not report a version in which case "0.0" should be assumed (per rfc3920
    // section 4.4.1).
    int majorVersion = 0;
    int minorVersion = 0;
    for (int i = 0; i < xpp.getAttributeCount(); i++) {
      if ("lang".equals(xpp.getAttributeName(i))) {
        language = xpp.getAttributeValue(i);
      }
      if ("version".equals(xpp.getAttributeName(i))) {
        try {
          int[] version = decodeVersion(xpp.getAttributeValue(i));
          majorVersion = version[0];
          minorVersion = version[1];
        } catch (Exception e) {
          Log.error(e.getMessage(), e);
        }
      }
    }

    // If the client supports a greater major version than the server,
    // set the version to the highest one the server supports.
    if (majorVersion > MAJOR_VERSION) {
      majorVersion = MAJOR_VERSION;
      minorVersion = MINOR_VERSION;
    } else if (majorVersion == MAJOR_VERSION) {
      // If the client supports a greater minor version than the
      // server, set the version to the highest one that the server
      // supports.
      if (minorVersion > MINOR_VERSION) {
        minorVersion = MINOR_VERSION;
      }
    }

    // Store language and version information in the connection.
    connection.setLanaguage(language);
    connection.setXMPPVersion(majorVersion, minorVersion);

    // Indicate the TLS policy to use for this connection
    if (!connection.isSecure()) {
      boolean hasCertificates = false;
      try {
        hasCertificates = SSLConfig.getKeyStore().size() > 0;
      } catch (Exception e) {
        Log.error(e.getMessage(), e);
      }
      Connection.TLSPolicy tlsPolicy = getTLSPolicy();
      if (Connection.TLSPolicy.required == tlsPolicy && !hasCertificates) {
        Log.error(
            "Client session rejected. TLS is required but no certificates " + "were created.");
        return null;
      }
      // Set default TLS policy
      connection.setTlsPolicy(hasCertificates ? tlsPolicy : Connection.TLSPolicy.disabled);
    } else {
      // Set default TLS policy
      connection.setTlsPolicy(Connection.TLSPolicy.disabled);
    }

    // Indicate the compression policy to use for this connection
    connection.setCompressionPolicy(getCompressionPolicy());

    // Create a ClientSession for this user.
    LocalClientSession session = SessionManager.getInstance().createClientSession(connection);

    // Build the start packet response
    StringBuilder sb = new StringBuilder(200);
    sb.append("<?xml version='1.0' encoding='");
    sb.append(CHARSET);
    sb.append("'?>");
    if (isFlashClient) {
      sb.append("<flash:stream xmlns:flash=\"http://www.jabber.com/streams/flash\" ");
    } else {
      sb.append("<stream:stream ");
    }
    sb.append("xmlns:stream=\"http://etherx.jabber.org/streams\" xmlns=\"jabber:client\" from=\"");
    sb.append(serverName);
    sb.append("\" id=\"");
    sb.append(session.getStreamID().toString());
    sb.append("\" xml:lang=\"");
    sb.append(language);
    // Don't include version info if the version is 0.0.
    if (majorVersion != 0) {
      sb.append("\" version=\"");
      sb.append(majorVersion).append(".").append(minorVersion);
    }
    sb.append("\">");
    connection.deliverRawText(sb.toString());

    // If this is a "Jabber" connection, the session is now initialized and we can
    // return to allow normal packet parsing.
    if (majorVersion == 0) {
      return session;
    }
    // Otherwise, this is at least XMPP 1.0 so we need to announce stream features.

    sb = new StringBuilder(490);
    sb.append("<stream:features>");
    if (connection.getTlsPolicy() != Connection.TLSPolicy.disabled) {
      sb.append("<starttls xmlns=\"urn:ietf:params:xml:ns:xmpp-tls\">");
      if (connection.getTlsPolicy() == Connection.TLSPolicy.required) {
        sb.append("<required/>");
      }
      sb.append("</starttls>");
    }
    // Include available SASL Mechanisms
    sb.append(SASLAuthentication.getSASLMechanisms(session));
    // Include Stream features
    String specificFeatures = session.getAvailableStreamFeatures();
    if (specificFeatures != null) {
      sb.append(specificFeatures);
    }
    sb.append("</stream:features>");

    connection.deliverRawText(sb.toString());
    return session;
  }
 public boolean isSecure() {
   return conn.isSecure();
 }