/**
* Tries to find an SSRC paired with {@code ssrc} in an FID group in one of the channels from
* {@link #channel}'s {@code Content}. Returns -1 on failure.
*
* @param pkt the {@code RawPacket} that holds the RTP packet for which to find a paired SSRC.
* @return An SSRC paired with {@code ssrc} in an FID group, or -1.
*/
private long getRtxSsrc(RawPacket pkt) {
StreamRTPManager receiveRTPManager =
channel.getStream().getRTPTranslator().findStreamRTPManagerByReceiveSSRC(pkt.getSSRC());
MediaStreamTrackReceiver receiver = null;
if (receiveRTPManager != null) {
MediaStream receiveStream = receiveRTPManager.getMediaStream();
if (receiveStream != null) {
receiver = receiveStream.getMediaStreamTrackReceiver();
}
}
if (receiver == null) {
return -1;
}
RTPEncoding encoding = receiver.resolveRTPEncoding(pkt);
if (encoding == null) {
logger.warn(
"encoding_not_found"
+ ",stream_hash="
+ channel.getStream().hashCode()
+ " ssrc="
+ pkt.getSSRCAsLong());
return -1;
}
return encoding.getRTXSSRC();
}
/** {@inheritDoc} */
@Override
public RawPacket transform(RawPacket pkt) {
byte[] buf = pkt.getBuffer();
int off = pkt.getOffset();
int len = pkt.getLength();
// If the specified pkt represents a DTLS record, then it should pass
// through this PacketTransformer (e.g. it has been sent through
// DatagramTransportImpl).
if (isDtlsRecord(buf, off, len)) return pkt;
// SRTP
if (!transformEngine.isSrtpDisabled()) {
// DTLS-SRTP has not been initialized yet or has failed to
// initialize.
SinglePacketTransformer srtpTransformer = waitInitializeAndGetSRTPTransformer();
if (srtpTransformer != null) pkt = srtpTransformer.transform(pkt);
else if (DROP_UNENCRYPTED_PKTS) pkt = null;
// XXX Else, it is our explicit policy to let the received packet
// pass through and rely on the SrtpListener to notify the user that
// the session is not secured.
}
// Pure/non-SRTP DTLS
else {
// The specified pkt will pass through this PacketTransformer only
// if it gets transformed into a DTLS record.
pkt = null;
sendApplicationData(buf, off, len);
}
return pkt;
}
/** {@inheritDoc} */
@Override
public RawPacket transform(RawPacket pkt) {
if (pkt == null) {
return pkt;
}
RTCPCompoundPacket inPacket;
try {
inPacket =
(RTCPCompoundPacket)
parser.parse(pkt.getBuffer(), pkt.getOffset(), pkt.getLength());
} catch (BadFormatException e) {
logger.warn("Failed to terminate an RTCP packet. " + "Dropping packet.");
return null;
}
// Update our RTCP stats map (timestamps). This operation is
// read-only.
remoteClockEstimator.apply(inPacket);
cnameRegistry.update(inPacket);
// Remove SRs and RRs from the RTCP packet.
pkt = feedbackGateway.gateway(inPacket);
return pkt;
}
public int write(byte[] buffer, int offset, int length, boolean transform) {
RawPacket pkt = rawPacketArray[0];
if (pkt == null) pkt = new RawPacket();
rawPacketArray[0] = pkt;
byte[] pktBuf = pkt.getBuffer();
if (pktBuf == null || pktBuf.length < length) {
pktBuf = new byte[length];
pkt.setBuffer(pktBuf);
}
System.arraycopy(buffer, offset, pktBuf, 0, length);
pkt.setOffset(0);
pkt.setLength(length);
if (transform) {
PacketTransformer packetTransformer =
isControlStream ? rtcpPacketTransformer : rtpPacketTransformer;
if (packetTransformer != null)
rawPacketArray = packetTransformer.reverseTransform(rawPacketArray);
}
SourceTransferHandler transferHandler;
PushSourceStream pushSourceStream;
try {
if (isControlStream) {
transferHandler = controlTransferHandler;
pushSourceStream = getControlInputStream();
} else {
transferHandler = dataTransferHandler;
pushSourceStream = getDataInputStream();
}
} catch (IOException ioe) {
throw new UndeclaredThrowableException(ioe);
}
for (int i = 0; i < rawPacketArray.length; i++) {
RawPacket packet = rawPacketArray[i];
// keep the first element for reuse
if (i != 0) rawPacketArray[i] = null;
if (packet != null) {
if (isControlStream) pendingControlPacket = packet;
else pendingDataPacket = packet;
if (transferHandler != null) {
transferHandler.transferData(pushSourceStream);
}
}
}
return length;
}
private void handleRtpPacket(RawPacket pkt) {
if (pkt != null && pkt.getPayloadType() == vp8PayloadType) {
int ssrc = pkt.getSSRC();
if (!activeVideoSsrcs.contains(ssrc & 0xffffffffL)) {
synchronized (activeVideoSsrcs) {
if (!activeVideoSsrcs.contains(ssrc & 0xffffffffL)) {
activeVideoSsrcs.add(ssrc & 0xffffffffL);
rtcpFeedbackSender.sendFIR(ssrc);
}
}
}
}
}
private void emptyPacketBuffer(long ssrc) {
RawPacket[] pkts = rtpConnector.packetBuffer.emptyBuffer(ssrc);
RTPConnectorImpl.OutputDataStreamImpl dataStream;
try {
dataStream = rtpConnector.getDataOutputStream();
} catch (IOException ioe) {
logger.error("Failed to empty packet buffer for SSRC=" + ssrc + ": " + ioe);
return;
}
for (RawPacket pkt : pkts)
dataStream.write(
pkt.getBuffer(), pkt.getOffset(), pkt.getLength(), false /* already transformed */);
}
/**
* Retransmits a packet to {@link #channel}. If the destination supports the RTX format, the
* packet will be encapsulated in RTX, otherwise, the packet will be retransmitted as-is.
*
* @param pkt the packet to retransmit.
* @param after the {@code TransformEngine} in the chain of {@code TransformEngine}s of the
* associated {@code MediaStream} after which the injection of {@code pkt} is to begin
* @return {@code true} if the packet was successfully retransmitted, {@code false} otherwise.
*/
public boolean retransmit(RawPacket pkt, TransformEngine after) {
boolean destinationSupportsRtx = channel.getRtxPayloadType() != -1;
boolean retransmitPlain;
if (destinationSupportsRtx) {
long rtxSsrc = getPairedSsrc(pkt.getSSRC());
if (rtxSsrc == -1) {
logger.warn("Cannot find SSRC for RTX, retransmitting plain.");
retransmitPlain = true;
} else {
retransmitPlain = !encapsulateInRtxAndTransmit(pkt, rtxSsrc);
}
} else {
retransmitPlain = true;
}
if (retransmitPlain) {
MediaStream mediaStream = channel.getStream();
if (mediaStream != null) {
try {
mediaStream.injectPacket(pkt, /* data */ true, after);
} catch (TransmissionFailedException tfe) {
logger.warn("Failed to retransmit a packet.");
return false;
}
}
}
return true;
}
@Override
public RawPacket reverseTransform(RawPacket pkt) {
RecorderRtpImpl.this.handleRtcpPacket(pkt);
if (pkt != null && pkt.getRTCPPayloadType() == 203) {
// An RTCP BYE packet. Remove the receive stream before
// it gets to FMJ, because we want to, for example,
// flush the packet buffer before that.
long ssrc = pkt.getRTCPSSRC() & 0xffffffffl;
if (logger.isInfoEnabled()) logger.info("RTCP BYE for SSRC=" + ssrc);
ReceiveStreamDesc receiveStream = findReceiveStream(ssrc);
if (receiveStream != null) removeReceiveStream(receiveStream, false);
}
return pkt;
}
/**
* Updates this <tt>RTPStatsMap</tt> with information it gets from the <tt>RawPacket</tt>.
*
* @param pkt the <tt>RawPacket</tt> that is being transmitted.
*/
public void apply(RawPacket pkt) {
int ssrc = pkt.getSSRC();
if (this.containsKey(ssrc)) {
RTPStatsEntry oldRtpStatsEntry = this.get(ssrc);
// Replace whatever was in there before. A feature of the two's
// complement encoding (which is used by Java integers) is that
// the bitwise results for add, subtract, and multiply are the
// same if both inputs are interpreted as signed values or both
// inputs are interpreted as unsigned values. (Other encodings
// like one's complement and signed magnitude don't have this
// properly.)
this.put(
ssrc,
new RTPStatsEntry(
ssrc,
oldRtpStatsEntry.getBytesSent()
+ pkt.getLength()
- pkt.getHeaderLength()
- pkt.getPaddingSize(),
oldRtpStatsEntry.getPacketsSent() + 1));
} else {
// Add a new <tt>RTPStatsEntry</tt> in this map.
this.put(
ssrc,
new RTPStatsEntry(
ssrc, pkt.getLength() - pkt.getHeaderLength() - pkt.getPaddingSize(), 1));
}
}
@Override
public int read(byte[] buffer, int offset, int length) throws IOException {
RawPacket pendingPacket;
if (isControlStream) {
pendingPacket = pendingControlPacket;
} else {
pendingPacket = pendingDataPacket;
}
int bytesToRead = 0;
byte[] pendingPacketBuffer = pendingPacket.getBuffer();
if (pendingPacketBuffer != null) {
int pendingPacketLength = pendingPacket.getLength();
bytesToRead = length > pendingPacketLength ? pendingPacketLength : length;
System.arraycopy(
pendingPacketBuffer, pendingPacket.getOffset(), buffer, offset, bytesToRead);
}
return bytesToRead;
}
/** Implements {@link PacketTransformer#transform(RawPacket[])}. {@inheritDoc} */
@Override
public RawPacket transform(RawPacket pkt) {
byte rtxPt;
if (pkt != null
&& (rtxPt = channel.getRtxPayloadType()) != -1
&& pkt.getPayloadType() == rtxPt) {
pkt = handleRtxPacket(pkt);
}
return pkt;
}
/**
* Handles an RTX packet and returns it.
*
* @param pkt the packet to handle.
* @return the packet
*/
private RawPacket handleRtxPacket(RawPacket pkt) {
boolean destinationSupportsRtx = channel.getRtxPayloadType() != -1;
RawPacket mediaPacket = createMediaPacket(pkt);
if (mediaPacket != null) {
RawPacketCache cache = channel.getStream().getPacketCache();
if (cache != null) {
cache.cachePacket(mediaPacket);
}
}
if (destinationSupportsRtx) {
pkt.setSequenceNumber(
getNextRtxSequenceNumber(pkt.getSSRC() & 0xffffffffL, pkt.getSequenceNumber()));
} else {
// If the media packet was not reconstructed, drop the RTX packet
// (by returning null).
return mediaPacket;
}
return pkt;
}
/**
* Encapsulates {@code pkt} in the RTX format, using {@code rtxSsrc} as its SSRC, and transmits it
* to {@link #channel} by injecting it in the {@code MediaStream}.
*
* @param pkt the packet to transmit.
* @param rtxSsrc the SSRC for the RTX stream.
* @param after the {@code TransformEngine} in the chain of {@code TransformEngine}s of the
* associated {@code MediaStream} after which the injection of {@code pkt} is to begin
* @return {@code true} if the packet was successfully retransmitted, {@code false} otherwise.
*/
private boolean encapsulateInRtxAndTransmit(RawPacket pkt, long rtxSsrc, TransformEngine after) {
byte[] buf = pkt.getBuffer();
int len = pkt.getLength();
int off = pkt.getOffset();
byte[] newBuf = new byte[len + 2];
RawPacket rtxPkt = new RawPacket(newBuf, 0, len + 2);
int osn = pkt.getSequenceNumber();
int headerLength = pkt.getHeaderLength();
int payloadLength = pkt.getPayloadLength();
// Copy the header.
System.arraycopy(buf, off, newBuf, 0, headerLength);
// Set the OSN field.
newBuf[headerLength] = (byte) ((osn >> 8) & 0xff);
newBuf[headerLength + 1] = (byte) (osn & 0xff);
// Copy the payload.
System.arraycopy(buf, off + headerLength, newBuf, headerLength + 2, payloadLength);
MediaStream mediaStream = channel.getStream();
if (mediaStream != null) {
rtxPkt.setSSRC((int) rtxSsrc);
rtxPkt.setPayloadType(rtxPayloadType);
// Only call getNextRtxSequenceNumber() when we're sure we're going
// to transmit a packet, because it consumes a sequence number.
rtxPkt.setSequenceNumber(getNextRtxSequenceNumber(rtxSsrc));
try {
mediaStream.injectPacket(rtxPkt, /* data */ true, after);
} catch (TransmissionFailedException tfe) {
logger.warn("Failed to transmit an RTX packet.");
return false;
}
}
return true;
}
/**
* Encapsulates {@code pkt} in the RTX format, using {@code rtxSsrc} as its SSRC, and transmits it
* to {@link #channel} by injecting it in the {@code MediaStream}.
*
* @param pkt the packet to transmit.
* @param rtxSsrc the SSRC for the RTX stream.
* @return {@code true} if the packet was successfully retransmitted, {@code false} otherwise.
*/
private boolean encapsulateInRtxAndTransmit(RawPacket pkt, long rtxSsrc) {
byte[] buf = pkt.getBuffer();
int len = pkt.getLength();
int off = pkt.getOffset();
byte[] newBuf = buf;
if (buf.length < len + 2) {
// FIXME The byte array newly allocated and assigned to newBuf must
// be made known to pkt eventually.
newBuf = new byte[len + 2];
}
int osn = pkt.getSequenceNumber();
int headerLength = pkt.getHeaderLength();
int payloadLength = len - headerLength;
System.arraycopy(buf, off, newBuf, 0, headerLength);
// FIXME If newBuf is actually buf, then we will override the first two
// bytes of the payload bellow.
newBuf[headerLength] = (byte) ((osn >> 8) & 0xff);
newBuf[headerLength + 1] = (byte) (osn & 0xff);
System.arraycopy(buf, off + headerLength, newBuf, headerLength + 2, payloadLength);
// FIXME We tried to extend the payload of pkt by two bytes above but
// we never told pkt that its length has increased by these two bytes.
MediaStream mediaStream = channel.getStream();
if (mediaStream != null) {
pkt.setSSRC((int) rtxSsrc);
// Only call getNextRtxSequenceNumber() when we're sure we're going
// to transmit a packet, because it consumes a sequence number.
pkt.setSequenceNumber(getNextRtxSequenceNumber(rtxSsrc));
try {
mediaStream.injectPacket(pkt, /* data */ true, /* after */ null);
} catch (TransmissionFailedException tfe) {
logger.warn("Failed to transmit an RTX packet.");
return false;
}
}
return true;
}
/**
* Creates a {@code RawPacket} which represents the original packet encapsulated in {@code pkt}
* using the RTX format.
*
* @param pkt the packet from which to extract a media packet.
* @return the extracted media packet.
*/
private RawPacket createMediaPacket(RawPacket pkt) {
RawPacket mediaPacket = null;
long rtxSsrc = pkt.getSSRC() & 0xffffffffL;
// We need to know the SSRC paired with rtxSsrc *as seen by the
// receiver (i.e. this.channel)*. However, we only store SSRCs
// that endpoints *send* with.
// We therefore assume that SSRC re-writing has not introduced any
// new SSRCs and therefor the FID mappings known to the senders
// also apply to receivers.
RtpChannel sourceChannel = channel.getContent().findChannelByFidSsrc(rtxSsrc);
if (sourceChannel != null) {
long mediaSsrc = sourceChannel.getFidPairedSsrc(rtxSsrc);
if (mediaSsrc != -1) {
byte apt = sourceChannel.getRtxAssociatedPayloadType();
if (apt != -1) {
mediaPacket = new RawPacket(pkt.getBuffer().clone(), pkt.getOffset(), pkt.getLength());
// Remove the RTX header by moving the RTP header two bytes
// right.
byte[] buf = mediaPacket.getBuffer();
int off = mediaPacket.getOffset();
System.arraycopy(buf, off, buf, off + 2, mediaPacket.getHeaderLength());
mediaPacket.setOffset(off + 2);
mediaPacket.setLength(pkt.getLength() - 2);
mediaPacket.setSSRC((int) mediaSsrc);
mediaPacket.setSequenceNumber(pkt.getOriginalSequenceNumber());
mediaPacket.setPayloadType(apt);
}
}
}
return mediaPacket;
}
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;
}
}
}
}
/**
* Removes the RTX encapsulation from a packet.
*
* @param pkt the packet to remove the RTX encapsulation from.
* @return the original media packet represented by {@code pkt}, or null if we couldn't
* reconstruct the original packet.
*/
private RawPacket deRtx(RawPacket pkt) {
boolean success = false;
if (pkt.getPayloadLength() - pkt.getPaddingSize() < 2) {
// We need at least 2 bytes to read the OSN field.
if (logger.isDebugEnabled()) {
logger.debug("Dropping an incoming RTX packet with padding only: " + pkt);
}
return null;
}
long mediaSsrc = getPrimarySsrc(pkt);
if (mediaSsrc != -1) {
if (rtxAssociatedPayloadType != -1) {
int osn = pkt.getOriginalSequenceNumber();
// Remove the RTX header by moving the RTP header two bytes
// right.
byte[] buf = pkt.getBuffer();
int off = pkt.getOffset();
System.arraycopy(buf, off, buf, off + 2, pkt.getHeaderLength());
pkt.setOffset(off + 2);
pkt.setLength(pkt.getLength() - 2);
pkt.setSSRC((int) mediaSsrc);
pkt.setSequenceNumber(osn);
pkt.setPayloadType(rtxAssociatedPayloadType);
success = true;
} else {
logger.warn(
"RTX packet received, but no APT is defined. Packet "
+ "SSRC "
+ pkt.getSSRCAsLong()
+ ", associated media"
+ " SSRC "
+ mediaSsrc);
}
}
// If we failed to handle the RTX packet, drop it.
return success ? pkt : null;
}
/** {@inheritDoc} */
@Override
public RawPacket reverseTransform(RawPacket pkt) {
byte[] buf = pkt.getBuffer();
int off = pkt.getOffset();
int len = pkt.getLength();
if (isDtlsRecord(buf, off, len)) {
if (rtcpmux && Component.RTCP == componentID) {
// This should never happen.
logger.warn(
"Dropping a DTLS record, because it was received on the"
+ " RTCP channel while rtcpmux is in use.");
return null;
}
boolean receive;
synchronized (this) {
if (datagramTransport == null) {
receive = false;
} else {
datagramTransport.queueReceive(buf, off, len);
receive = true;
}
}
if (receive) {
DTLSTransport dtlsTransport = this.dtlsTransport;
if (dtlsTransport == null) {
// The specified pkt looks like a DTLS record and it has
// been consumed for the purposes of the secure channel
// represented by this PacketTransformer.
pkt = null;
} else {
try {
int receiveLimit = dtlsTransport.getReceiveLimit();
int delta = receiveLimit - len;
if (delta > 0) {
pkt.grow(delta);
buf = pkt.getBuffer();
off = pkt.getOffset();
len = pkt.getLength();
} else if (delta < 0) {
pkt.shrink(-delta);
buf = pkt.getBuffer();
off = pkt.getOffset();
len = pkt.getLength();
}
int received = dtlsTransport.receive(buf, off, len, DTLS_TRANSPORT_RECEIVE_WAITMILLIS);
if (received <= 0) {
// No application data was decoded.
pkt = null;
} else {
delta = len - received;
if (delta > 0) pkt.shrink(delta);
}
} catch (IOException ioe) {
pkt = null;
// SrtpControl.start(MediaType) starts its associated
// TransformEngine. We will use that mediaType to signal
// the normal stop then as well i.e. we will ignore
// exception after the procedure to stop this
// PacketTransformer has begun.
if (mediaType != null && !tlsPeerHasRaisedCloseNotifyWarning) {
logger.error("Failed to decode a DTLS record!", ioe);
}
}
}
} else {
// The specified pkt looks like a DTLS record but it is
// unexpected in the current state of the secure channel
// represented by this PacketTransformer. This PacketTransformer
// has not been started (successfully) or has been closed.
pkt = null;
}
} else if (transformEngine.isSrtpDisabled()) {
// In pure DTLS mode only DTLS records pass through.
pkt = null;
} else {
// DTLS-SRTP has not been initialized yet or has failed to
// initialize.
SinglePacketTransformer srtpTransformer = waitInitializeAndGetSRTPTransformer();
if (srtpTransformer != null) pkt = srtpTransformer.reverseTransform(pkt);
else if (DROP_UNENCRYPTED_PKTS) pkt = null;
// XXX Else, it is our explicit policy to let the received packet
// pass through and rely on the SrtpListener to notify the user that
// the session is not secured.
}
return pkt;
}
/**
* Determines whether {@code pkt} is an RTX packet.
*
* @param pkt the packet to check.
* @return {@code true} iff {@code pkt} is an RTX packet.
*/
private boolean isRtx(RawPacket pkt) {
byte rtxPt = rtxPayloadType;
return rtxPt != -1 && rtxPt == pkt.getPayloadType();
}