/**
 * Class is a transport layer for WebRTC data channels. It consists of SCTP connection running on
 * top of ICE/DTLS layer. Manages WebRTC data channels. See
 * http://tools.ietf.org/html/draft-ietf-rtcweb-data-channel-08 for more info on WebRTC data
 * channels.
 *
 * <p>Control protocol: http://tools.ietf.org/html/draft-ietf-rtcweb-data-protocol-03 FIXME handle
 * closing of data channels(SCTP stream reset)
 *
 * @author Pawel Domas
 * @author Lyubomir Marinov
 * @author Boris Grozev
 */
public class SctpConnection extends Channel
    implements SctpDataCallback, SctpSocket.NotificationListener {
  /** Generator used to track debug IDs. */
  private static int debugIdGen = -1;

  /** DTLS transport buffer size. Note: randomly chosen. */
  private static final int DTLS_BUFFER_SIZE = 2048;

  /** Switch used for debugging SCTP traffic purposes. FIXME to be removed */
  private static final boolean LOG_SCTP_PACKETS = false;

  /** The logger */
  private static final Logger logger = Logger.getLogger(SctpConnection.class);

  /**
   * Message type used to acknowledge WebRTC data channel allocation on SCTP stream ID on which
   * <tt>MSG_OPEN_CHANNEL</tt> message arrives.
   */
  private static final int MSG_CHANNEL_ACK = 0x2;

  private static final byte[] MSG_CHANNEL_ACK_BYTES = new byte[] {MSG_CHANNEL_ACK};

  /**
   * Message with this type sent over control PPID in order to open new WebRTC data channel on SCTP
   * stream ID that this message is sent.
   */
  private static final int MSG_OPEN_CHANNEL = 0x3;

  /** SCTP transport buffer size. */
  private static final int SCTP_BUFFER_SIZE = DTLS_BUFFER_SIZE - 13;

  /** The pool of <tt>Thread</tt>s which run <tt>SctpConnection</tt>s. */
  private static final ExecutorService threadPool =
      ExecutorUtils.newCachedThreadPool(true, SctpConnection.class.getName());

  /** Payload protocol id that identifies binary data in WebRTC data channel. */
  static final int WEB_RTC_PPID_BIN = 53;

  /** Payload protocol id for control data. Used for <tt>WebRtcDataStream</tt> allocation. */
  static final int WEB_RTC_PPID_CTRL = 50;

  /** Payload protocol id that identifies text data UTF8 encoded in WebRTC data channels. */
  static final int WEB_RTC_PPID_STRING = 51;

  /**
   * The <tt>String</tt> value of the <tt>Protocol</tt> field of the <tt>DATA_CHANNEL_OPEN</tt>
   * message.
   */
  private static final String WEBRTC_DATA_CHANNEL_PROTOCOL = "http://jitsi.org/protocols/colibri";

  private static synchronized int generateDebugId() {
    debugIdGen += 2;
    return debugIdGen;
  }

  /**
   * Indicates whether the STCP association is ready and has not been ended by a subsequent state
   * change.
   */
  private boolean assocIsUp;

  /** Indicates if we have accepted incoming connection. */
  private boolean acceptedIncomingConnection;

  /** Data channels mapped by SCTP stream identified(sid). */
  private final Map<Integer, WebRtcDataStream> channels = new HashMap<Integer, WebRtcDataStream>();

  /** Debug ID used to distinguish SCTP sockets in packet logs. */
  private final int debugId;

  /**
   * The <tt>AsyncExecutor</tt> which is to asynchronously dispatch the events fired by this
   * instance in order to prevent possible listeners from blocking this <tt>SctpConnection</tt> in
   * general and {@link #sctpSocket} in particular for too long. The timeout of <tt>15</tt> is
   * chosen to be in accord with the time it takes to expire a <tt>Channel</tt>.
   */
  private final AsyncExecutor<Runnable> eventDispatcher =
      new AsyncExecutor<Runnable>(15, TimeUnit.MILLISECONDS);

  /** Datagram socket for ICE/UDP layer. */
  private IceSocketWrapper iceSocket;

  /**
   * List of <tt>WebRtcDataStreamListener</tt>s that will be notified whenever new WebRTC data
   * channel is opened.
   */
  private final List<WebRtcDataStreamListener> listeners =
      new ArrayList<WebRtcDataStreamListener>();

  /** Remote SCTP port. */
  private final int remoteSctpPort;

  /** <tt>SctpSocket</tt> used for SCTP transport. */
  private SctpSocket sctpSocket;

  /**
   * Flag prevents from starting this connection multiple times from {@link #maybeStartStream()}.
   */
  private boolean started;

  /**
   * Initializes a new <tt>SctpConnection</tt> instance.
   *
   * @param id the string identifier of this connection instance
   * @param content the <tt>Content</tt> which is initializing the new instance
   * @param endpoint the <tt>Endpoint</tt> of newly created instance
   * @param remoteSctpPort the SCTP port used by remote peer
   * @param channelBundleId the ID of the channel-bundle this <tt>SctpConnection</tt> is to be a
   *     part of (or <tt>null</tt> if no it is not to be a part of a channel-bundle).
   * @throws Exception if an error occurs while initializing the new instance
   */
  public SctpConnection(
      String id, Content content, Endpoint endpoint, int remoteSctpPort, String channelBundleId)
      throws Exception {
    super(content, id, channelBundleId);

    setEndpoint(endpoint.getID());

    this.remoteSctpPort = remoteSctpPort;
    this.debugId = generateDebugId();
  }

  /**
   * Adds <tt>WebRtcDataStreamListener</tt> to the list of listeners.
   *
   * @param listener the <tt>WebRtcDataStreamListener</tt> to be added to the listeners list.
   */
  public void addChannelListener(WebRtcDataStreamListener listener) {
    if (listener == null) {
      throw new NullPointerException("listener");
    } else {
      synchronized (listeners) {
        if (!listeners.contains(listener)) {
          listeners.add(listener);
        }
      }
    }
  }

  /** {@inheritDoc} */
  @Override
  protected void closeStream() throws IOException {
    try {
      synchronized (this) {
        assocIsUp = false;
        acceptedIncomingConnection = false;
        if (sctpSocket != null) {
          sctpSocket.close();
          sctpSocket = null;
        }
      }
    } finally {
      if (iceSocket != null) {
        // It is now the responsibility of the transport manager to
        // close the socket.
        // iceUdpSocket.close();
      }
    }
  }

  /** {@inheritDoc} */
  @Override
  public void expire() {
    try {
      eventDispatcher.shutdown();
    } finally {
      super.expire();
    }
  }

  /**
   * Gets the <tt>WebRtcDataStreamListener</tt>s added to this instance.
   *
   * @return the <tt>WebRtcDataStreamListener</tt>s added to this instance or <tt>null</tt> if there
   *     are no <tt>WebRtcDataStreamListener</tt>s added to this instance
   */
  private WebRtcDataStreamListener[] getChannelListeners() {
    WebRtcDataStreamListener[] ls;

    synchronized (listeners) {
      if (listeners.isEmpty()) {
        ls = null;
      } else {
        ls = listeners.toArray(new WebRtcDataStreamListener[listeners.size()]);
      }
    }
    return ls;
  }

  /**
   * Returns default <tt>WebRtcDataStream</tt> if it's ready or <tt>null</tt> otherwise.
   *
   * @return <tt>WebRtcDataStream</tt> if it's ready or <tt>null</tt> otherwise.
   * @throws IOException
   */
  public WebRtcDataStream getDefaultDataStream() throws IOException {
    WebRtcDataStream def;

    synchronized (this) {
      if (sctpSocket == null) {
        def = null;
      } else {
        // Channel that runs on sid 0
        def = channels.get(0);
        if (def == null) {
          def = openChannel(0, 0, 0, 0, "default");
        }
        // Pawel Domas: Must be acknowledged before use
        /*
         * XXX Lyubomir Marinov: We're always sending ordered. According
         * to "WebRTC Data Channel Establishment Protocol", we can start
         * sending messages containing user data after the
         * DATA_CHANNEL_OPEN message has been sent without waiting for
         * the reception of the corresponding DATA_CHANNEL_ACK message.
         */
        //                if (!def.isAcknowledged())
        //                    def = null;
      }
    }
    return def;
  }

  /**
   * Returns <tt>true</tt> if this <tt>SctpConnection</tt> is connected to the remote peer and
   * operational.
   *
   * @return <tt>true</tt> if this <tt>SctpConnection</tt> is connected to the remote peer and
   *     operational
   */
  public boolean isReady() {
    return assocIsUp && acceptedIncomingConnection;
  }

  /** {@inheritDoc} */
  @Override
  protected void maybeStartStream() throws IOException {
    // connector
    final StreamConnector connector = getStreamConnector();

    if (connector == null) return;

    synchronized (this) {
      if (started) return;

      threadPool.execute(
          new Runnable() {
            @Override
            public void run() {
              try {
                Sctp.init();

                runOnDtlsTransport(connector);
              } catch (IOException e) {
                logger.error(e, e);
              } finally {
                try {
                  Sctp.finish();
                } catch (IOException e) {
                  logger.error("Failed to shutdown SCTP stack", e);
                }
              }
            }
          });

      started = true;
    }
  }

  /**
   * Submits {@link #notifyChannelOpenedInEventDispatcher(WebRtcDataStream)} to {@link
   * #eventDispatcher} for asynchronous execution.
   *
   * @param dataChannel
   */
  private void notifyChannelOpened(final WebRtcDataStream dataChannel) {
    if (!isExpired()) {
      eventDispatcher.execute(
          new Runnable() {
            @Override
            public void run() {
              notifyChannelOpenedInEventDispatcher(dataChannel);
            }
          });
    }
  }

  private void notifyChannelOpenedInEventDispatcher(WebRtcDataStream dataChannel) {
    /*
     * When executing asynchronously in eventDispatcher, it is technically
     * possible that this SctpConnection may have expired by now.
     */
    if (!isExpired()) {
      WebRtcDataStreamListener[] ls = getChannelListeners();

      if (ls != null) {
        for (WebRtcDataStreamListener l : ls) {
          l.onChannelOpened(this, dataChannel);
        }
      }
    }
  }

  /**
   * Submits {@link #notifySctpConnectionReadyInEventDispatcher()} to {@link #eventDispatcher} for
   * asynchronous execution.
   */
  private void notifySctpConnectionReady() {
    if (!isExpired()) {
      eventDispatcher.execute(
          new Runnable() {
            @Override
            public void run() {
              notifySctpConnectionReadyInEventDispatcher();
            }
          });
    }
  }

  /**
   * Notifies the <tt>WebRtcDataStreamListener</tt>s added to this instance that this
   * <tt>SctpConnection</tt> is ready i.e. it is connected to the remote peer and operational.
   */
  private void notifySctpConnectionReadyInEventDispatcher() {
    /*
     * When executing asynchronously in eventDispatcher, it is technically
     * possible that this SctpConnection may have expired by now.
     */
    if (!isExpired() && isReady()) {
      WebRtcDataStreamListener[] ls = getChannelListeners();

      if (ls != null) {
        for (WebRtcDataStreamListener l : ls) {
          l.onSctpConnectionReady(this);
        }
      }
    }
  }

  /**
   * Handles control packet.
   *
   * @param data raw packet data that arrived on control PPID.
   * @param sid SCTP stream id on which the data has arrived.
   */
  private synchronized void onCtrlPacket(byte[] data, int sid) throws IOException {
    ByteBuffer buffer = ByteBuffer.wrap(data);
    int messageType = /* 1 byte unsigned integer */ 0xFF & buffer.get();

    if (messageType == MSG_CHANNEL_ACK) {
      if (logger.isDebugEnabled()) {
        logger.debug(getEndpoint().getID() + " ACK received SID: " + sid);
      }
      // Open channel ACK
      WebRtcDataStream channel = channels.get(sid);
      if (channel != null) {
        // Ack check prevents from firing multiple notifications
        // if we get more than one ACKs (by mistake/bug).
        if (!channel.isAcknowledged()) {
          channel.ackReceived();
          notifyChannelOpened(channel);
        } else {
          logger.warn("Redundant ACK received for SID: " + sid);
        }
      } else {
        logger.error("No channel exists on sid: " + sid);
      }
    } else if (messageType == MSG_OPEN_CHANNEL) {
      int channelType = /* 1 byte unsigned integer */ 0xFF & buffer.get();
      int priority = /* 2 bytes unsigned integer */ 0xFFFF & buffer.getShort();
      long reliability = /* 4 bytes unsigned integer */ 0xFFFFFFFFL & buffer.getInt();
      int labelLength = /* 2 bytes unsigned integer */ 0xFFFF & buffer.getShort();
      int protocolLength = /* 2 bytes unsigned integer */ 0xFFFF & buffer.getShort();
      String label;
      String protocol;

      if (labelLength == 0) {
        label = "";
      } else {
        byte[] labelBytes = new byte[labelLength];

        buffer.get(labelBytes);
        label = new String(labelBytes, "UTF-8");
      }
      if (protocolLength == 0) {
        protocol = "";
      } else {
        byte[] protocolBytes = new byte[protocolLength];

        buffer.get(protocolBytes);
        protocol = new String(protocolBytes, "UTF-8");
      }

      if (logger.isDebugEnabled()) {
        logger.debug(
            "!!! "
                + getEndpoint().getID()
                + " data channel open request on SID: "
                + sid
                + " type: "
                + channelType
                + " prio: "
                + priority
                + " reliab: "
                + reliability
                + " label: "
                + label
                + " proto: "
                + protocol);
      }

      if (channels.containsKey(sid)) {
        logger.error("Channel on sid: " + sid + " already exists");
      }

      WebRtcDataStream newChannel = new WebRtcDataStream(sctpSocket, sid, label, true);
      channels.put(sid, newChannel);

      sendOpenChannelAck(sid);

      notifyChannelOpened(newChannel);
    } else {
      logger.error("Unexpected ctrl msg type: " + messageType);
    }
  }

  /** {@inheritDoc} */
  @Override
  protected void onEndpointChanged(Endpoint oldValue, Endpoint newValue) {
    if (oldValue != null) oldValue.setSctpConnection(null);
    if (newValue != null) newValue.setSctpConnection(this);
  }

  /** Implements notification in order to track socket state. */
  @Override
  public synchronized void onSctpNotification(SctpSocket socket, SctpNotification notification) {
    if (logger.isDebugEnabled()) {
      logger.debug("socket=" + socket + "; notification=" + notification);
    }
    switch (notification.sn_type) {
      case SctpNotification.SCTP_ASSOC_CHANGE:
        SctpNotification.AssociationChange assocChange =
            (SctpNotification.AssociationChange) notification;

        switch (assocChange.state) {
          case SctpNotification.AssociationChange.SCTP_COMM_UP:
            if (!assocIsUp) {
              boolean wasReady = isReady();

              assocIsUp = true;
              if (isReady() && !wasReady) notifySctpConnectionReady();
            }
            break;

          case SctpNotification.AssociationChange.SCTP_COMM_LOST:
          case SctpNotification.AssociationChange.SCTP_SHUTDOWN_COMP:
          case SctpNotification.AssociationChange.SCTP_CANT_STR_ASSOC:
            try {
              closeStream();
            } catch (IOException e) {
              logger.error("Error closing SCTP socket", e);
            }
            break;
        }
        break;
    }
  }

  /**
   * {@inheritDoc}
   *
   * <p>SCTP input data callback.
   */
  @Override
  public void onSctpPacket(
      byte[] data, int sid, int ssn, int tsn, long ppid, int context, int flags) {
    if (ppid == WEB_RTC_PPID_CTRL) {
      // Channel control PPID
      try {
        onCtrlPacket(data, sid);
      } catch (IOException e) {
        logger.error("IOException when processing ctrl packet", e);
      }
    } else if (ppid == WEB_RTC_PPID_STRING || ppid == WEB_RTC_PPID_BIN) {
      WebRtcDataStream channel;

      synchronized (this) {
        channel = channels.get(sid);
      }

      if (channel == null) {
        logger.error("No channel found for sid: " + sid);
        return;
      }
      if (ppid == WEB_RTC_PPID_STRING) {
        // WebRTC String
        String str;
        String charsetName = "UTF-8";

        try {
          str = new String(data, charsetName);
        } catch (UnsupportedEncodingException uee) {
          logger.error("Unsupported charset encoding/name " + charsetName, uee);
          str = null;
        }
        channel.onStringMsg(str);
      } else {
        // WebRTC Binary
        channel.onBinaryMsg(data);
      }
    } else {
      logger.warn("Got message on unsupported PPID: " + ppid);
    }
  }

  /**
   * Opens new WebRTC data channel using specified parameters.
   *
   * @param type channel type as defined in control protocol description. Use 0 for "reliable".
   * @param prio channel priority. The higher the number, the lower the priority.
   * @param reliab Reliability Parameter<br>
   *     This field is ignored if a reliable channel is used. If a partial reliable channel with
   *     limited number of retransmissions is used, this field specifies the number of
   *     retransmissions. If a partial reliable channel with limited lifetime is used, this field
   *     specifies the maximum lifetime in milliseconds. The following table summarizes this:<br>
   *     </br>
   *     <p>+------------------------------------------------+------------------+ | Channel Type |
   *     Reliability | | | Parameter |
   *     +------------------------------------------------+------------------+ |
   *     DATA_CHANNEL_RELIABLE | Ignored | | DATA_CHANNEL_RELIABLE_UNORDERED | Ignored | |
   *     DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT | Number of RTX | |
   *     DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT_UNORDERED | Number of RTX | |
   *     DATA_CHANNEL_PARTIAL_RELIABLE_TIMED | Lifetime in ms | |
   *     DATA_CHANNEL_PARTIAL_RELIABLE_TIMED_UNORDERED | Lifetime in ms |
   *     +------------------------------------------------+------------------+
   * @param sid SCTP stream id that will be used by new channel (it must not be already used).
   * @param label text label for the channel.
   * @return new instance of <tt>WebRtcDataStream</tt> that represents opened WebRTC data channel.
   * @throws IOException if IO error occurs.
   */
  public synchronized WebRtcDataStream openChannel(
      int type, int prio, long reliab, int sid, String label) throws IOException {
    if (channels.containsKey(sid)) {
      throw new IOException("Channel on sid: " + sid + " already exists");
    }

    // Label Length & Label
    byte[] labelBytes;
    int labelByteLength;

    if (label == null) {
      labelBytes = null;
      labelByteLength = 0;
    } else {
      labelBytes = label.getBytes("UTF-8");
      labelByteLength = labelBytes.length;
      if (labelByteLength > 0xFFFF) labelByteLength = 0xFFFF;
    }

    // Protocol Length & Protocol
    String protocol = WEBRTC_DATA_CHANNEL_PROTOCOL;
    byte[] protocolBytes;
    int protocolByteLength;

    if (protocol == null) {
      protocolBytes = null;
      protocolByteLength = 0;
    } else {
      protocolBytes = protocol.getBytes("UTF-8");
      protocolByteLength = protocolBytes.length;
      if (protocolByteLength > 0xFFFF) protocolByteLength = 0xFFFF;
    }

    ByteBuffer packet = ByteBuffer.allocate(12 + labelByteLength + protocolByteLength);

    // Message open new channel on current sid
    // Message Type
    packet.put((byte) MSG_OPEN_CHANNEL);
    // Channel Type
    packet.put((byte) type);
    // Priority
    packet.putShort((short) prio);
    // Reliability Parameter
    packet.putInt((int) reliab);
    // Label Length
    packet.putShort((short) labelByteLength);
    // Protocol Length
    packet.putShort((short) protocolByteLength);
    // Label
    if (labelByteLength != 0) {
      packet.put(labelBytes, 0, labelByteLength);
    }
    // Protocol
    if (protocolByteLength != 0) {
      packet.put(protocolBytes, 0, protocolByteLength);
    }

    int sentCount = sctpSocket.send(packet.array(), true, sid, WEB_RTC_PPID_CTRL);

    if (sentCount != packet.capacity()) {
      throw new IOException("Failed to open new chanel on sid: " + sid);
    }

    WebRtcDataStream channel = new WebRtcDataStream(sctpSocket, sid, label, false);

    channels.put(sid, channel);

    return channel;
  }

  /**
   * Removes <tt>WebRtcDataStreamListener</tt> from the list of listeners.
   *
   * @param listener the <tt>WebRtcDataStreamListener</tt> to be removed from the listeners list.
   */
  public void removeChannelListener(WebRtcDataStreamListener listener) {
    if (listener != null) {
      synchronized (listeners) {
        listeners.remove(listener);
      }
    }
  }

  private void runOnDtlsTransport(StreamConnector connector) throws IOException {
    DtlsControlImpl dtlsControl = (DtlsControlImpl) getTransportManager().getDtlsControl(this);
    DtlsTransformEngine engine = dtlsControl.getTransformEngine();
    final DtlsPacketTransformer transformer = (DtlsPacketTransformer) engine.getRTPTransformer();

    byte[] receiveBuffer = new byte[SCTP_BUFFER_SIZE];

    if (LOG_SCTP_PACKETS) {
      System.setProperty(
          ConfigurationService.PNAME_SC_HOME_DIR_LOCATION, System.getProperty("java.io.tmpdir"));
      System.setProperty(
          ConfigurationService.PNAME_SC_HOME_DIR_NAME, SctpConnection.class.getName());
    }

    synchronized (this) {
      // FIXME local SCTP port is hardcoded in bridge offer SDP (Jitsi
      // Meet)
      sctpSocket = Sctp.createSocket(5000);
      assocIsUp = false;
      acceptedIncomingConnection = false;
    }

    // Implement output network link for SCTP stack on DTLS transport
    sctpSocket.setLink(
        new NetworkLink() {
          @Override
          public void onConnOut(SctpSocket s, byte[] packet) throws IOException {
            if (LOG_SCTP_PACKETS) {
              LibJitsi.getPacketLoggingService()
                  .logPacket(
                      PacketLoggingService.ProtocolName.ICE4J,
                      new byte[] {0, 0, 0, (byte) debugId},
                      5000,
                      new byte[] {0, 0, 0, (byte) (debugId + 1)},
                      remoteSctpPort,
                      PacketLoggingService.TransportName.UDP,
                      true,
                      packet);
            }

            // Send through DTLS transport
            transformer.sendApplicationData(packet, 0, packet.length);
          }
        });

    if (logger.isDebugEnabled()) {
      logger.debug("Connecting SCTP to port: " + remoteSctpPort + " to " + getEndpoint().getID());
    }

    sctpSocket.setNotificationListener(this);
    sctpSocket.listen();

    // FIXME manage threads
    threadPool.execute(
        new Runnable() {
          @Override
          public void run() {
            SctpSocket sctpSocket = null;
            try {
              // sctpSocket is set to null on close
              sctpSocket = SctpConnection.this.sctpSocket;
              while (sctpSocket != null) {
                if (sctpSocket.accept()) {
                  acceptedIncomingConnection = true;
                  break;
                }
                Thread.sleep(100);
                sctpSocket = SctpConnection.this.sctpSocket;
              }
              if (isReady()) {
                notifySctpConnectionReady();
              }
            } catch (Exception e) {
              logger.error("Error accepting SCTP connection", e);
            }

            if (sctpSocket == null && logger.isInfoEnabled()) {
              logger.info(
                  "SctpConnection " + getID() + " closed" + " before SctpSocket accept()-ed.");
            }
          }
        });

    // Notify that from now on SCTP connection is considered functional
    sctpSocket.setDataCallback(this);

    // Setup iceSocket
    DatagramSocket datagramSocket = connector.getDataSocket();
    if (datagramSocket != null) {
      this.iceSocket = new IceUdpSocketWrapper(datagramSocket);
    } else {
      this.iceSocket = new IceTcpSocketWrapper(connector.getDataTCPSocket());
    }

    DatagramPacket rcvPacket = new DatagramPacket(receiveBuffer, 0, receiveBuffer.length);

    // Receive loop, breaks when SCTP socket is closed
    try {
      do {
        iceSocket.receive(rcvPacket);

        RawPacket raw =
            new RawPacket(rcvPacket.getData(), rcvPacket.getOffset(), rcvPacket.getLength());

        raw = transformer.reverseTransform(raw);
        // Check for app data
        if (raw == null) continue;

        if (LOG_SCTP_PACKETS) {
          LibJitsi.getPacketLoggingService()
              .logPacket(
                  PacketLoggingService.ProtocolName.ICE4J,
                  new byte[] {0, 0, 0, (byte) (debugId + 1)},
                  remoteSctpPort,
                  new byte[] {0, 0, 0, (byte) debugId},
                  5000,
                  PacketLoggingService.TransportName.UDP,
                  false,
                  raw.getBuffer(),
                  raw.getOffset(),
                  raw.getLength());
        }

        // Pass network packet to SCTP stack
        sctpSocket.onConnIn(raw.getBuffer(), raw.getOffset(), raw.getLength());
      } while (true);
    } finally {
      // Eventually, close the socket although it should happen from
      // expire().
      synchronized (this) {
        assocIsUp = false;
        acceptedIncomingConnection = false;
        if (sctpSocket != null) {
          sctpSocket.close();
          sctpSocket = null;
        }
      }
    }
  }

  /**
   * Sends acknowledgment for open channel request on given SCTP stream ID.
   *
   * @param sid SCTP stream identifier to be used for sending ack.
   */
  private void sendOpenChannelAck(int sid) throws IOException {
    // Send ACK
    byte[] ack = MSG_CHANNEL_ACK_BYTES;
    int sendAck = sctpSocket.send(ack, true, sid, WEB_RTC_PPID_CTRL);

    if (sendAck != ack.length) {
      logger.error("Failed to send open channel confirmation");
    }
  }

  /**
   * {@inheritDoc}
   *
   * <p>Creates a <tt>TransportManager</tt> instance suitable for an <tt>SctpConnection</tt> (e.g.
   * with 1 component only).
   */
  protected TransportManager createTransportManager(String xmlNamespace) throws IOException {
    if (IceUdpTransportPacketExtension.NAMESPACE.equals(xmlNamespace)) {
      Content content = getContent();
      return new IceUdpTransportManager(
          content.getConference(), isInitiator(), 1 /* num components */, content.getName());
    } else if (RawUdpTransportPacketExtension.NAMESPACE.equals(xmlNamespace)) {
      // TODO: support RawUdp once RawUdpTransportManager is updated
      // return new RawUdpTransportManager(this);
      throw new IllegalArgumentException("Unsupported Jingle transport " + xmlNamespace);
    } else {
      throw new IllegalArgumentException("Unsupported Jingle transport " + xmlNamespace);
    }
  }
}
Exemple #2
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/**
 * Implements a <tt>CandidateHarvester</tt> which gathers <tt>Candidate</tt>s for a specified {@link
 * Component} using UPnP.
 *
 * @author Sebastien Vincent
 */
public class UPNPHarvester extends AbstractCandidateHarvester {
  /** The logger. */
  private static final Logger logger = Logger.getLogger(UPNPHarvester.class.getName());

  /** Maximum port to try to allocate. */
  private static final int MAX_RETRIES = 5;

  /** ST search field for WANIPConnection. */
  private static final String stIP = "urn:schemas-upnp-org:service:WANIPConnection:1";

  /** ST search field for WANPPPConnection. */
  private static final String stPPP = "urn:schemas-upnp-org:service:WANPPPConnection:1";

  /** Synchronization object. */
  private final Object rootSync = new Object();

  /** Gateway device. */
  private GatewayDevice device = null;

  /** Number of UPnP discover threads that have finished. */
  private int finishThreads = 0;

  /**
   * Gathers UPnP candidates for all host <tt>Candidate</tt>s that are already present in the
   * specified <tt>component</tt>. This method relies on the specified <tt>component</tt> to already
   * contain all its host candidates so that it would resolve them.
   *
   * @param component the {@link Component} that we'd like to gather candidate UPnP
   *     <tt>Candidate</tt>s for
   * @return the <tt>LocalCandidate</tt>s gathered by this <tt>CandidateHarvester</tt>
   */
  public synchronized Collection<LocalCandidate> harvest(Component component) {
    Collection<LocalCandidate> candidates = new HashSet<>();
    int retries = 0;

    logger.fine("Begin UPnP harvesting");
    try {
      if (device == null) {
        // do it only once
        if (finishThreads == 0) {
          try {
            UPNPThread wanIPThread = new UPNPThread(stIP);
            UPNPThread wanPPPThread = new UPNPThread(stPPP);

            wanIPThread.start();
            wanPPPThread.start();

            synchronized (rootSync) {
              while (finishThreads != 2) {
                rootSync.wait();
              }
            }

            if (wanIPThread.getDevice() != null) {
              device = wanIPThread.getDevice();
            } else if (wanPPPThread.getDevice() != null) {
              device = wanPPPThread.getDevice();
            }

          } catch (Throwable e) {
            logger.info("UPnP discovery failed: " + e);
          }
        }

        if (device == null) return candidates;
      }

      InetAddress localAddress = device.getLocalAddress();
      String externalIPAddress = device.getExternalIPAddress();
      PortMappingEntry portMapping = new PortMappingEntry();

      IceSocketWrapper socket =
          new IceUdpSocketWrapper(new MultiplexingDatagramSocket(0, localAddress));
      int port = socket.getLocalPort();
      int externalPort = socket.getLocalPort();

      while (retries < MAX_RETRIES) {
        if (!device.getSpecificPortMappingEntry(port, "UDP", portMapping)) {
          if (device.addPortMapping(
              externalPort, port, localAddress.getHostAddress(), "UDP", "ice4j.org: " + port)) {
            List<LocalCandidate> cands =
                createUPNPCandidate(socket, externalIPAddress, externalPort, component, device);

            logger.info("Add UPnP port mapping: " + externalIPAddress + " " + externalPort);

            // we have to add the UPNPCandidate and also the base.
            // if we don't add the base, we won't be able to add
            // peer reflexive candidate if someone contact us on the
            // UPNPCandidate
            for (LocalCandidate cand : cands) {
              // try to add the candidate to the component and then
              // only add it to the harvest not redundant
              if (component.addLocalCandidate(cand)) {
                candidates.add(cand);
              }
            }

            break;
          } else {
            port++;
          }
        } else {
          port++;
        }
        retries++;
      }
    } catch (Throwable e) {
      logger.info("Exception while gathering UPnP candidates: " + e);
    }

    return candidates;
  }

  /**
   * Create a UPnP candidate.
   *
   * @param socket local socket
   * @param externalIP external IP address
   * @param port local port
   * @param component parent component
   * @param device the UPnP gateway device
   * @return a new <tt>UPNPCandidate</tt> instance which represents the specified
   *     <tt>TransportAddress</tt>
   * @throws Exception if something goes wrong during candidate creation
   */
  private List<LocalCandidate> createUPNPCandidate(
      IceSocketWrapper socket,
      String externalIP,
      int port,
      Component component,
      GatewayDevice device)
      throws Exception {
    List<LocalCandidate> ret = new ArrayList<>();
    TransportAddress addr = new TransportAddress(externalIP, port, Transport.UDP);

    HostCandidate base = new HostCandidate(socket, component);

    UPNPCandidate candidate = new UPNPCandidate(addr, base, component, device);
    IceSocketWrapper stunSocket = candidate.getStunSocket(null);
    candidate.getStunStack().addSocket(stunSocket);
    component.getComponentSocket().add(candidate.getCandidateIceSocketWrapper());

    ret.add(candidate);
    ret.add(base);

    return ret;
  }

  /** UPnP discover thread. */
  private class UPNPThread extends Thread {
    /** Gateway device. */
    private GatewayDevice device = null;

    /** ST search field. */
    private final String st;

    /**
     * Constructor.
     *
     * @param st ST search field
     */
    public UPNPThread(String st) {
      this.st = st;
    }

    /**
     * Returns gateway device.
     *
     * @return gateway device
     */
    public GatewayDevice getDevice() {
      return device;
    }

    /** Thread Entry point. */
    public void run() {
      try {
        GatewayDiscover gd = new GatewayDiscover(st);

        gd.discover();

        if (gd.getValidGateway() != null) {
          device = gd.getValidGateway();
        }
      } catch (Throwable e) {
        logger.info("Failed to harvest UPnP: " + e);

        /*
         * The Javadoc on ThreadDeath says: If ThreadDeath is caught by
         * a method, it is important that it be rethrown so that the
         * thread actually dies.
         */
        if (e instanceof ThreadDeath) throw (ThreadDeath) e;
      } finally {
        synchronized (rootSync) {
          finishThreads++;
          rootSync.notify();
        }
      }
    }
  }

  /**
   * Returns a <tt>String</tt> representation of this harvester containing its name.
   *
   * @return a <tt>String</tt> representation of this harvester containing its name.
   */
  @Override
  public String toString() {
    return getClass().getSimpleName();
  }
}
Exemple #3
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/**
 * The Network Access Point is the most outward part of the stack. It is constructed around a
 * datagram socket and takes care of forwarding incoming messages to the MessageProcessor as well as
 * sending datagrams to the STUN server specified by the original NetAccessPointDescriptor.
 *
 * @author Emil Ivov
 */
class Connector implements Runnable {
  /** Our class logger. */
  private static final Logger logger = Logger.getLogger(Connector.class.getName());

  /** The message queue is where incoming messages are added. */
  private final MessageQueue messageQueue;

  /** The socket object that used by this access point to access the network. */
  private IceSocketWrapper sock;

  /** The object that we use to lock socket operations (since the socket itself is often null) */
  private final Object sockLock = new Object();

  /** A flag that is set to false to exit the message processor. */
  private boolean running;

  /** The instance to be notified if errors occur in the network listening thread. */
  private final ErrorHandler errorHandler;

  /** The address that we are listening to. */
  private final TransportAddress listenAddress;

  /**
   * The remote address of the socket of this <tt>Connector</tt> if it is a TCP socket, or
   * <tt>null</tt> if it is UDP.
   */
  private final TransportAddress remoteAddress;

  /**
   * Creates a network access point.
   *
   * @param socket the socket that this access point is supposed to use for communication.
   * @param messageQueue the FIFO list where incoming messages should be queued
   * @param errorHandler the instance to notify when errors occur.
   */
  protected Connector(
      IceSocketWrapper socket, MessageQueue messageQueue, ErrorHandler errorHandler) {
    this.sock = socket;
    this.messageQueue = messageQueue;
    this.errorHandler = errorHandler;

    Transport transport = socket.getUDPSocket() != null ? Transport.UDP : Transport.TCP;

    listenAddress =
        new TransportAddress(socket.getLocalAddress(), socket.getLocalPort(), transport);
    if (transport == Transport.UDP) {
      remoteAddress = null;
    } else {
      Socket tcpSocket = socket.getTCPSocket();

      remoteAddress =
          new TransportAddress(tcpSocket.getInetAddress(), tcpSocket.getPort(), transport);
    }
  }

  /** Start the network listening thread. */
  void start() {
    this.running = true;

    Thread thread = new Thread(this, "IceConnector@" + hashCode());

    thread.setDaemon(true);
    thread.start();
  }

  /**
   * Returns the <tt>DatagramSocket</tt> that contains the port and address associated with this
   * access point.
   *
   * @return the <tt>DatagramSocket</tt> associated with this AP.
   */
  protected IceSocketWrapper getSocket() {
    return sock;
  }

  /** The listening thread's run method. */
  @Override
  public void run() {
    DatagramPacket packet = null;

    while (this.running) {
      try {
        IceSocketWrapper localSock;

        synchronized (sockLock) {
          if (!running) return;

          localSock = this.sock;
        }

        /*
         * Make sure localSock's receiveBufferSize is taken into
         * account including after it gets changed.
         */
        int receiveBufferSize = 1500;
        /*
        if(localSock.getTCPSocket() != null)
        {
            receiveBufferSize = localSock.getTCPSocket().
                getReceiveBufferSize();
        }
        else if(localSock.getUDPSocket() != null)
        {
            receiveBufferSize = localSock.getUDPSocket().
                getReceiveBufferSize();
        }
        */

        if (packet == null) {
          packet = new DatagramPacket(new byte[receiveBufferSize], receiveBufferSize);
        } else {
          byte[] packetData = packet.getData();

          if ((packetData == null) || (packetData.length < receiveBufferSize)) {
            packet.setData(new byte[receiveBufferSize], 0, receiveBufferSize);
          } else {
            /*
             * XXX Tell the packet it is large enough because the
             * socket will not look at the length of the data array
             * property and will just respect the length property.
             */
            packet.setLength(receiveBufferSize);
          }
        }

        localSock.receive(packet);

        // get lost if we are no longer running.
        if (!running) return;

        logger.finest("received datagram");

        RawMessage rawMessage =
            new RawMessage(
                packet.getData(),
                packet.getLength(),
                new TransportAddress(
                    packet.getAddress(), packet.getPort(), listenAddress.getTransport()),
                listenAddress);

        messageQueue.add(rawMessage);
      } catch (SocketException ex) {
        if (running) {
          logger.log(
              Level.WARNING, "Connector died: " + listenAddress + " -> " + remoteAddress, ex);

          stop();
          // Something wrong has happened
          errorHandler.handleFatalError(
              this, "A socket exception was thrown" + " while trying to receive a message.", ex);
        } else {
          // The exception was most probably caused by calling
          // this.stop().
        }
      } catch (ClosedChannelException cce) {
        logger.log(Level.WARNING, "A net access point has gone useless:", cce);

        stop();
        errorHandler.handleFatalError(
            this, "ClosedChannelException occurred while listening" + " for messages!", cce);
      } catch (IOException ex) {
        logger.log(Level.WARNING, "A net access point has gone useless:", ex);

        errorHandler.handleError(ex.getMessage(), ex);
        // do not stop the thread;
      } catch (Throwable ex) {
        logger.log(Level.WARNING, "A net access point has gone useless:", ex);

        stop();
        errorHandler.handleFatalError(
            this, "Unknown error occurred while listening for messages!", ex);
      }
    }
  }

  /** Makes the access point stop listening on its socket. */
  protected void stop() {
    synchronized (sockLock) {
      this.running = false;
      if (this.sock != null) {
        this.sock.close();
        this.sock = null;
      }
    }
  }

  /**
   * Sends message through this access point's socket.
   *
   * @param message the bytes to send.
   * @param address message destination.
   * @throws IOException if an exception occurs while sending the message.
   */
  void sendMessage(byte[] message, TransportAddress address) throws IOException {
    DatagramPacket datagramPacket = new DatagramPacket(message, 0, message.length, address);

    sock.send(datagramPacket);
  }

  /**
   * Returns a String representation of the object.
   *
   * @return a String representation of the object.
   */
  @Override
  public String toString() {
    return "ice4j.Connector@" + listenAddress + " status: " + (running ? "not" : "") + " running";
  }

  /**
   * Returns the <tt>TransportAddress</tt> that this access point is bound on.
   *
   * @return the <tt>TransportAddress</tt> associated with this AP.
   */
  TransportAddress getListenAddress() {
    return listenAddress;
  }

  /**
   * Returns the remote <tt>TransportAddress</tt> in case of TCP, or <tt>null</tt> in case of UDP.
   *
   * @return the remote <tt>TransportAddress</tt> in case of TCP, or <tt>null</tt> in case of UDP.
   */
  TransportAddress getRemoteAddress() {
    return remoteAddress;
  }
}
/**
 * Implements a <tt>CandidateHarvester</tt> which gathers <tt>Candidate</tt>s for a specified {@link
 * Component} using Jingle Nodes as defined in XEP 278 "Jingle Relay Nodes".
 *
 * @author Sebastien Vincent
 */
public class JingleNodesHarvester extends AbstractCandidateHarvester {
  /**
   * The <tt>Logger</tt> used by the <tt>JingleNodesHarvester</tt> class and its instances for
   * logging output.
   */
  private static final Logger logger = Logger.getLogger(JingleNodesHarvester.class.getName());

  /** XMPP connection. */
  private SmackServiceNode serviceNode = null;

  /**
   * JingleNodes relay allocate two address/port couple for us. Due to the architecture of Ice4j
   * that harvest address for each component, we store the second address/port couple.
   */
  private TransportAddress localAddressSecond = null;

  /**
   * JingleNodes relay allocate two address/port couple for us. Due to the architecture of Ice4j
   * that harvest address for each component, we store the second address/port couple.
   */
  private TransportAddress relayedAddressSecond = null;

  /**
   * Constructor.
   *
   * @param serviceNode the <tt>SmackServiceNode</tt>
   */
  public JingleNodesHarvester(SmackServiceNode serviceNode) {
    this.serviceNode = serviceNode;
  }

  /**
   * Gathers Jingle Nodes candidates for all host <tt>Candidate</tt>s that are already present in
   * the specified <tt>component</tt>. This method relies on the specified <tt>component</tt> to
   * already contain all its host candidates so that it would resolve them.
   *
   * @param component the {@link Component} that we'd like to gather candidate Jingle Nodes
   *     <tt>Candidate</tt>s for
   * @return the <tt>LocalCandidate</tt>s gathered by this <tt>CandidateHarvester</tt>
   */
  @Override
  public synchronized Collection<LocalCandidate> harvest(Component component) {
    logger.info("harvest Jingle Nodes");

    Collection<LocalCandidate> candidates = new HashSet<LocalCandidate>();
    String ip = null;
    int port = -1;

    /* if we have already a candidate (RTCP) allocated, get it */
    if (localAddressSecond != null && relayedAddressSecond != null) {
      LocalCandidate candidate =
          createJingleNodesCandidate(relayedAddressSecond, component, localAddressSecond);

      // try to add the candidate to the component and then only add it to
      // the harvest not redundant (not sure how it could be red. but ...)
      if (component.addLocalCandidate(candidate)) {
        candidates.add(candidate);
      }

      localAddressSecond = null;
      relayedAddressSecond = null;
      return candidates;
    }

    XMPPConnection conn = serviceNode.getConnection();
    JingleChannelIQ ciq = null;

    if (serviceNode != null) {
      final TrackerEntry preferred = serviceNode.getPreferedRelay();

      if (preferred != null) {
        ciq = SmackServiceNode.getChannel(conn, preferred.getJid());
      }
    }

    if (ciq != null) {
      ip = ciq.getHost();
      port = ciq.getRemoteport();

      if (logger.isInfoEnabled()) {
        logger.info(
            "JN relay: " + ip + " remote port:" + port + " local port: " + ciq.getLocalport());
      }

      if (ip == null || ciq.getRemoteport() == 0) {
        logger.warn("JN relay ignored because ip was null or port 0");
        return candidates;
      }

      // Drop the scope or interface name if the relay sends it
      // along in its IPv6 address. The scope/ifname is only valid on the
      // host that owns the IP and we don't need it here.
      int scopeIndex = ip.indexOf('%');
      if (scopeIndex > 0) {
        logger.warn("Dropping scope from assumed IPv6 address " + ip);
        ip = ip.substring(0, scopeIndex);
      }

      /* RTP */
      TransportAddress relayedAddress = new TransportAddress(ip, port, Transport.UDP);
      TransportAddress localAddress = new TransportAddress(ip, ciq.getLocalport(), Transport.UDP);

      LocalCandidate local = createJingleNodesCandidate(relayedAddress, component, localAddress);

      /* RTCP */
      relayedAddressSecond = new TransportAddress(ip, port + 1, Transport.UDP);
      localAddressSecond = new TransportAddress(ip, ciq.getLocalport() + 1, Transport.UDP);

      // try to add the candidate to the component and then only add it to
      // the harvest not redundant (not sure how it could be red. but ...)
      if (component.addLocalCandidate(local)) {
        candidates.add(local);
      }
    }

    return candidates;
  }

  /**
   * Creates a new <tt>JingleNodesRelayedCandidate</tt> instance which is to represent a specific
   * <tt>TransportAddress</tt>.
   *
   * @param transportAddress the <tt>TransportAddress</tt> allocated by the relay
   * @param component the <tt>Component</tt> for which the candidate will be added
   * @param localEndPoint <tt>TransportAddress</tt> of the Jingle Nodes relay where we will send our
   *     packet.
   * @return a new <tt>JingleNodesRelayedCandidate</tt> instance which represents the specified
   *     <tt>TransportAddress</tt>
   */
  protected JingleNodesCandidate createJingleNodesCandidate(
      TransportAddress transportAddress, Component component, TransportAddress localEndPoint) {
    JingleNodesCandidate cand = null;

    try {
      cand = new JingleNodesCandidate(transportAddress, component, localEndPoint);
      IceSocketWrapper stunSocket = cand.getStunSocket(null);
      cand.getStunStack().addSocket(stunSocket);
    } catch (Throwable e) {
      logger.debug("Exception occurred when creating JingleNodesCandidate: " + e);
    }

    return cand;
  }
}
/**
 * @author Bing SU ([email protected])
 * @author Lyubomir Marinov
 * @author Boris Grozev
 */
public abstract class RTPConnectorInputStream implements PushSourceStream, Runnable {
  /**
   * The value of the property <tt>controls</tt> of <tt>RTPConnectorInputStream</tt> when there are
   * no controls. Explicitly defined in order to reduce unnecessary allocations.
   */
  private static final Object[] EMPTY_CONTROLS = new Object[0];

  /**
   * The length in bytes of the buffers of <tt>RTPConnectorInputStream</tt> receiving packets from
   * the network.
   */
  public static final int PACKET_RECEIVE_BUFFER_LENGTH = 4 * 1024;

  /**
   * The <tt>Logger</tt> used by the <tt>RTPConnectorInputStream</tt> class and its instances to
   * print debug information.
   */
  private static final Logger logger = Logger.getLogger(RTPConnectorInputStream.class);

  /** Packet receive buffer */
  private final byte[] buffer = new byte[PACKET_RECEIVE_BUFFER_LENGTH];

  /** Whether this stream is closed. Used to control the termination of worker thread. */
  protected boolean closed;

  public Participant videoRecorder;

  /**
   * The <tt>DatagramPacketFilter</tt>s which allow dropping <tt>DatagramPacket</tt>s before they
   * are converted into <tt>RawPacket</tt>s.
   */
  private DatagramPacketFilter[] datagramPacketFilters;

  /** Caught an IO exception during read from socket */
  protected boolean ioError = false;

  /**
   * The packet data to be read out of this instance through its {@link #read(byte[], int, int)}
   * method.
   */
  private RawPacket pkt;

  /** The <tt>Object</tt> which synchronizes the access to {@link #pkt}. */
  private final Object pktSyncRoot = new Object();

  /** The adapter of this <tt>PushSourceStream</tt> to the <tt>PushBufferStream</tt> interface. */
  private final PushBufferStream pushBufferStream;

  /**
   * The pool of <tt>RawPacket[]</tt> instances to reduce their allocations and garbage collection.
   * Contains arrays full of <tt>null</tt>.
   */
  private final Queue<RawPacket[]> rawPacketArrayPool = new LinkedBlockingQueue<RawPacket[]>();

  /**
   * The pool of <tt>RawPacket</tt> instances to reduce their allocations and garbage collection.
   */
  private final Queue<RawPacket> rawPacketPool = new LinkedBlockingQueue<RawPacket>();

  /** The Thread receiving packets. */
  protected Thread receiverThread = null;

  /** SourceTransferHandler object which is used to read packets. */
  private SourceTransferHandler transferHandler;

  /**
   * Whether this <tt>RTPConnectorInputStream</tt> is enabled or disabled. While disabled, the
   * stream does not accept any packets.
   */
  private boolean enabled = true;

  /**
   * Initializes a new <tt>RTPConnectorInputStream</tt> which is to receive packet data from a
   * specific UDP socket.
   */
  public RTPConnectorInputStream() {
    // PacketLoggingService
    addDatagramPacketFilter(
        new DatagramPacketFilter() {
          /**
           * Used for debugging. As we don't log every packet, we must count them and decide which
           * to log.
           */
          private long numberOfPackets = 0;

          public boolean accept(DatagramPacket p) {
            numberOfPackets++;
            if (RTPConnectorOutputStream.logPacket(numberOfPackets)) {
              PacketLoggingService packetLogging = LibJitsi.getPacketLoggingService();

              if ((packetLogging != null)
                  && packetLogging.isLoggingEnabled(PacketLoggingService.ProtocolName.RTP))
                doLogPacket(p);
            }

            return true;
          }
        });

    /*
     * Adapt this PushSourceStream to the PushBufferStream interface in
     * order to make it possible to read the Buffer flags of RawPacket.
     */
    pushBufferStream =
        new PushBufferStreamAdapter(this, null) {
          @Override
          protected int doRead(Buffer buffer, byte[] data, int offset, int length)
              throws IOException {
            return RTPConnectorInputStream.this.read(buffer, data, offset, length);
          }
        };
  }

  /** Close this stream, stops the worker thread. */
  public synchronized void close() {}

  /**
   * Creates a new <tt>RawPacket</tt> from a specific <tt>DatagramPacket</tt> in order to have this
   * instance receive its packet data through its {@link #read(byte[], int, int)} method. Returns an
   * array of <tt>RawPacket</tt> with the created packet as its first element (and <tt>null</tt> for
   * the other elements).
   *
   * <p>Allows extenders to intercept the packet data and possibly filter and/or modify it.
   *
   * @param datagramPacket the <tt>DatagramPacket</tt> containing the packet data
   * @return an array of <tt>RawPacket</tt> containing the <tt>RawPacket</tt> which contains the
   *     packet data of the specified <tt>DatagramPacket</tt> as its first element.
   */
  protected RawPacket[] createRawPacket(DatagramPacket datagramPacket) {
    RawPacket[] pkts = rawPacketArrayPool.poll();
    if (pkts == null) pkts = new RawPacket[1];

    RawPacket pkt = rawPacketPool.poll();
    if (pkt == null) pkt = new RawPacket();

    pkt.setBuffer(datagramPacket.getData());
    pkt.setFlags(0);
    pkt.setLength(datagramPacket.getLength());
    pkt.setOffset(datagramPacket.getOffset());

    pkts[0] = pkt;
    return pkts;
  }

  /**
   * Provides a dummy implementation to {@link RTPConnectorInputStream#endOfStream()} that always
   * returns <tt>false</tt>.
   *
   * @return <tt>false</tt>, no matter what.
   */
  public boolean endOfStream() {
    return false;
  }

  /**
   * Provides a dummy implementation to {@link RTPConnectorInputStream#getContentDescriptor()} that
   * always returns <tt>null</tt>.
   *
   * @return <tt>null</tt>, no matter what.
   */
  public ContentDescriptor getContentDescriptor() {
    return null;
  }

  /**
   * Provides a dummy implementation to {@link RTPConnectorInputStream#getContentLength()} that
   * always returns <tt>LENGTH_UNKNOWN</tt>.
   *
   * @return <tt>LENGTH_UNKNOWN</tt>, no matter what.
   */
  public long getContentLength() {
    return LENGTH_UNKNOWN;
  }

  /**
   * Provides a dummy implementation of {@link RTPConnectorInputStream#getControl(String)} that
   * always returns <tt>null</tt>.
   *
   * @param controlType ignored.
   * @return <tt>null</tt>, no matter what.
   */
  public Object getControl(String controlType) {
    if (PushBufferStream.class.getName().equals(controlType)) return pushBufferStream;
    else return null;
  }

  /**
   * Provides a dummy implementation of {@link RTPConnectorInputStream#getControls()} that always
   * returns <tt>EMPTY_CONTROLS</tt>.
   *
   * @return <tt>EMPTY_CONTROLS</tt>, no matter what.
   */
  public Object[] getControls() {
    return EMPTY_CONTROLS;
  }

  /**
   * Provides a dummy implementation to {@link RTPConnectorInputStream#getMinimumTransferSize()}
   * that always returns <tt>2 * 1024</tt>.
   *
   * @return <tt>2 * 1024</tt>, no matter what.
   */
  public int getMinimumTransferSize() {
    return 2 * 1024; // twice the MTU size, just to be safe.
  }

  /**
   * Pools the specified <tt>RawPacket</tt> in order to avoid future allocations and to reduce the
   * effects of garbage collection.
   *
   * @param pkt the <tt>RawPacket</tt> to be offered to {@link #rawPacketPool}
   */
  private void poolRawPacket(RawPacket pkt) {
    pkt.setBuffer(null);
    pkt.setFlags(0);
    pkt.setLength(0);
    pkt.setOffset(0);
    rawPacketPool.offer(pkt);
  }

  /**
   * Copies the content of the most recently received packet into <tt>buffer</tt>.
   *
   * @param buffer the <tt>byte[]</tt> that we'd like to copy the content of the packet to.
   * @param offset the position where we are supposed to start writing in <tt>buffer</tt>.
   * @param length the number of <tt>byte</tt>s available for writing in <tt>buffer</tt>.
   * @return the number of bytes read
   * @throws IOException if <tt>length</tt> is less than the size of the packet.
   */
  public int read(byte[] buffer, int offset, int length) throws IOException {
    return read(null, buffer, offset, length);
  }

  /**
   * Copies the content of the most recently received packet into <tt>data</tt>.
   *
   * @param buffer an optional <tt>Buffer</tt> instance associated with the specified <tt>data</tt>,
   *     <tt>offset</tt> and <tt>length</tt> and provided to the method in case the implementation
   *     would like to provide additional <tt>Buffer</tt> properties such as <tt>flags</tt>
   * @param data the <tt>byte[]</tt> that we'd like to copy the content of the packet to.
   * @param offset the position where we are supposed to start writing in <tt>data</tt>.
   * @param length the number of <tt>byte</tt>s available for writing in <tt>data</tt>.
   * @return the number of bytes read
   * @throws IOException if <tt>length</tt> is less than the size of the packet.
   */
  protected int read(Buffer buffer, byte[] data, int offset, int length) throws IOException {
    if (data == null) throw new NullPointerException("data");

    if (ioError) return -1;

    RawPacket pkt;

    synchronized (pktSyncRoot) {
      pkt = this.pkt;
      this.pkt = null;
    }

    int pktLength;

    if (pkt == null) {
      pktLength = 0;
    } else {
      // By default, pkt will be returned to the pool after it was read.
      boolean poolPkt = true;

      try {
        pktLength = pkt.getLength();
        if (length < pktLength) {
          /*
           * If pkt is still the latest RawPacket made available to
           * reading, reinstate it for the next invocation of read;
           * otherwise, return it to the pool.
           */
          poolPkt = false;
          throw new IOException("Input buffer not big enough for " + pktLength);
        } else {
          byte[] pktBuffer = pkt.getBuffer();

          if (pktBuffer == null) {
            throw new NullPointerException(
                "pkt.buffer null, pkt.length " + pktLength + ", pkt.offset " + pkt.getOffset());
          } else {
            System.arraycopy(pkt.getBuffer(), pkt.getOffset(), data, offset, pktLength);
            if (buffer != null) buffer.setFlags(pkt.getFlags());
          }
        }
      } finally {
        if (!poolPkt) {
          synchronized (pktSyncRoot) {
            if (this.pkt == null) this.pkt = pkt;
            else poolPkt = true;
          }
        }
        if (poolPkt) {
          // Return pkt to the pool because it was successfully read.
          poolRawPacket(pkt);
        }
      }
    }

    return pktLength;
  }

  /**
   * Log the packet.
   *
   * @param packet packet to log
   */
  protected abstract void doLogPacket(DatagramPacket packet);

  /**
   * Receive packet.
   *
   * @param p packet for receiving
   * @throws IOException if something goes wrong during receiving
   */
  protected abstract void receivePacket(DatagramPacket p) throws IOException;

  /**
   * Listens for incoming datagrams, stores them for reading by the <tt>read</tt> method and
   * notifies the local <tt>transferHandler</tt> that there's data to be read.
   */
  public void run() {
    DatagramPacket p = new DatagramPacket(buffer, 0, PACKET_RECEIVE_BUFFER_LENGTH);

    while (!closed) {
      try {
        // http://code.google.com/p/android/issues/detail?id=24765
        if (OSUtils.IS_ANDROID) p.setLength(PACKET_RECEIVE_BUFFER_LENGTH);

        receivePacket(p);
      } catch (IOException e) {
        ioError = true;
        break;
      }

      /*
       * Do the DatagramPacketFilters accept the received DatagramPacket?
       */
      DatagramPacketFilter[] datagramPacketFilters = getDatagramPacketFilters();
      boolean accept;

      if (!enabled) accept = false;
      else if (datagramPacketFilters == null) accept = true;
      else {
        accept = true;
        for (int i = 0; i < datagramPacketFilters.length; i++) {
          try {
            if (!datagramPacketFilters[i].accept(p)) {
              accept = false;
              break;
            }
          } catch (Throwable t) {
            if (t instanceof ThreadDeath) throw (ThreadDeath) t;
          }
        }
      }

      if (accept) {
        RawPacket pkts[] = createRawPacket(p);

        for (int i = 0; i < pkts.length; i++) {
          RawPacket pkt = pkts[i];

          pkts[i] = null;

          if (pkt != null) {
            if (pkt.isInvalid()) {
              /*
               * Return pkt to the pool because it is invalid and,
               * consequently, will not be made available to
               * reading.
               */
              poolRawPacket(pkt);
            } else {
              RawPacket oldPkt;

              synchronized (pktSyncRoot) {
                oldPkt = this.pkt;
                this.pkt = pkt;
              }
              if (oldPkt != null) {
                /*
                 * Return oldPkt to the pool because it was made
                 * available to reading and it was not read.
                 */
                poolRawPacket(oldPkt);
              }

              if (videoRecorder != null) videoRecorder.recordData(pkt);

              if ((transferHandler != null) && !closed) {
                try {
                  transferHandler.transferData(this);
                } catch (Throwable t) {
                  /*
                   * XXX We cannot allow transferHandler to
                   * kill us.
                   */
                  if (t instanceof ThreadDeath) {
                    throw (ThreadDeath) t;
                  } else {
                    logger.warn("An RTP packet may have not been" + " fully handled.", t);
                  }
                }
              }
            }
          }
        }
        rawPacketArrayPool.offer(pkts);
      }
    }
  }

  /**
   * Sets the <tt>transferHandler</tt> that this connector should be notifying when new data is
   * available for reading.
   *
   * @param transferHandler the <tt>transferHandler</tt> that this connector should be notifying
   *     when new data is available for reading.
   */
  public void setTransferHandler(SourceTransferHandler transferHandler) {
    if (!closed) this.transferHandler = transferHandler;
  }

  /**
   * Changes current thread priority.
   *
   * @param priority the new priority.
   */
  public void setPriority(int priority) {
    // currently no priority is set
    //        if (receiverThread != null)
    //            receiverThread.setPriority(priority);
  }

  /**
   * Gets the <tt>DatagramPacketFilter</tt>s which allow dropping <tt>DatagramPacket</tt>s before
   * they are converted into <tt>RawPacket</tt>s.
   *
   * @return the <tt>DatagramPacketFilter</tt>s which allow dropping <tt>DatagramPacket</tt>s before
   *     they are converted into <tt>RawPacket</tt>s.
   */
  public synchronized DatagramPacketFilter[] getDatagramPacketFilters() {
    return datagramPacketFilters;
  }

  /**
   * Adds a <tt>DatagramPacketFilter</tt> which allows dropping <tt>DatagramPacket</tt>s before they
   * are converted into <tt>RawPacket</tt>s.
   *
   * @param datagramPacketFilter the <tt>DatagramPacketFilter</tt> which allows dropping
   *     <tt>DatagramPacket</tt>s before they are converted into <tt>RawPacket</tt>s
   */
  public synchronized void addDatagramPacketFilter(DatagramPacketFilter datagramPacketFilter) {
    if (datagramPacketFilter == null) throw new NullPointerException("datagramPacketFilter");

    if (datagramPacketFilters == null) {
      datagramPacketFilters = new DatagramPacketFilter[] {datagramPacketFilter};
    } else {
      final int length = datagramPacketFilters.length;

      for (int i = 0; i < length; i++)
        if (datagramPacketFilter.equals(datagramPacketFilters[i])) return;

      DatagramPacketFilter[] newDatagramPacketFilters = new DatagramPacketFilter[length + 1];

      System.arraycopy(datagramPacketFilters, 0, newDatagramPacketFilters, 0, length);
      newDatagramPacketFilters[length] = datagramPacketFilter;
      datagramPacketFilters = newDatagramPacketFilters;
    }
  }

  /**
   * Enables or disables this <tt>RTPConnectorInputStream</tt>. While the stream is disabled, it
   * does not accept any packets.
   *
   * @param enabled <tt>true</tt> to enable, <tt>false</tt> to disable.
   */
  public void setEnabled(boolean enabled) {
    if (logger.isDebugEnabled()) logger.debug("setEnabled: " + enabled);

    this.enabled = enabled;
  }
}