/** Starts this <tt>PacketTransformer</tt>. */
private synchronized void start() {
if (this.datagramTransport != null) {
if (this.connectThread == null && dtlsTransport == null) {
logger.warn(
getClass().getName()
+ " has been started but has failed to establish"
+ " the DTLS connection!");
}
return;
}
if (rtcpmux && Component.RTCP == componentID) {
// In the case of rtcp-mux, the RTCP transformer does not create
// a DTLS session. The SRTP context (_srtpTransformer) will be
// initialized on demand using initializeSRTCPTransformerFromRtp().
return;
}
AbstractRTPConnector connector = this.connector;
if (connector == null) throw new NullPointerException("connector");
DtlsControl.Setup setup = this.setup;
SecureRandom secureRandom = DtlsControlImpl.createSecureRandom();
final DTLSProtocol dtlsProtocolObj;
final TlsPeer tlsPeer;
if (DtlsControl.Setup.ACTIVE.equals(setup)) {
dtlsProtocolObj = new DTLSClientProtocol(secureRandom);
tlsPeer = new TlsClientImpl(this);
} else {
dtlsProtocolObj = new DTLSServerProtocol(secureRandom);
tlsPeer = new TlsServerImpl(this);
}
tlsPeerHasRaisedCloseNotifyWarning = false;
final DatagramTransportImpl datagramTransport = new DatagramTransportImpl(componentID);
datagramTransport.setConnector(connector);
Thread connectThread =
new Thread() {
@Override
public void run() {
try {
runInConnectThread(dtlsProtocolObj, tlsPeer, datagramTransport);
} finally {
if (Thread.currentThread().equals(DtlsPacketTransformer.this.connectThread)) {
DtlsPacketTransformer.this.connectThread = null;
}
}
}
};
connectThread.setDaemon(true);
connectThread.setName(DtlsPacketTransformer.class.getName() + ".connectThread");
this.connectThread = connectThread;
this.datagramTransport = datagramTransport;
boolean started = false;
try {
connectThread.start();
started = true;
} finally {
if (!started) {
if (connectThread.equals(this.connectThread)) this.connectThread = null;
if (datagramTransport.equals(this.datagramTransport)) this.datagramTransport = null;
}
}
notifyAll();
}
/** {@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;
}