public void OnDataReceived(IAsyncResult asyn)
{
// Logger.Log(0, "Begin OnDataReceived");
IPEndPoint remoteIpEndPoint = new IPEndPoint(IPAddress.Any, 0);
byte[] buf = null;
try {
buf = udpConn.EndReceive(asyn, ref remoteIpEndPoint);
} catch (SocketException e) {
if (e.SocketErrorCode == SocketError.Interrupted)
// ignore
return;
log_status.WarnFormat("Caught socket exception: {0}", e);
WaitForData();
return;
} catch (ObjectDisposedException) {
// just ignore this one
return;
}
RdpConnection conn = GetConnection(remoteIpEndPoint);
if (conn == null) {
log_status.Info("Handling new connection");
conn = HandleNewConnection(remoteIpEndPoint);
}
if (conn != null) {
RdpPacket packet = new RdpPacket(buf);
// Logger.Log(0, "Got data in OnDataReceived");
conn.OnSegmentArrival(packet, remoteIpEndPoint);
// Logger.Log(0, "Done with OnDataReceived");
}
try {
WaitForData();
} catch (SocketException e) {
if (e.SocketErrorCode != SocketError.Interrupted)
throw;
} catch (ObjectDisposedException) {
// Just ignore this
}
}
// TODO: Should I pass in remote endpoint?
public void OnSegmentArrival(RdpPacket packet)
{
switch (state) {
case ConnectionState.Closed:
if (packet.Rst)
return;
else if (packet.Ack || packet.Nul) {
/// Send <SEQ=SEG.ACK + 1><RST>
;
} else {
/// Send <SEQ=0><RST><ACK=SEG.SEQ><ACK>
;
}
break;
case ConnectionState.CloseWait:
break;
case ConnectionState.Listen:
if (packet.Rst)
return;
if (packet.Ack || packet.Nul) {
/// Send <SEQ=SEG.ACK + 1><RST>
return;
}
if (packet.Syn) {
rcvCur = segSeq;
rcvIrs = segSeq;
sndMax = segMax;
sbufMax = segBmax;
/// Send <SEQ=SND.ISS><ACK=RCV.CUR><MAX=RCV.MAX><BUFMAX=RBUF.MAX>
/// <ACK><SYN>
state = ConnectionState.SynRcvd;
return;
}
Trace.TraceWarning("Shouldn't have gotten here");
break;
case ConnectionState.SynSent:
if (packet.Rst) {
if (packet.Ack) {
state = ConnectionState.Closed;
throw new Exception("Connection Refused");
// TODO: deallocate connection
}
return;
}
if (packet.Syn) {
rcvCur = segSeq;
rcvIrs = segSeq;
sndMax = segMax;
rbufMax = segBmax;
if (packet.Ack) {
sndUna = segAck + 1; // per rfc 1151
state = ConnectionState.Open;
/// Send <SEQ=SND.NXT><ACK=RCV.CUR><ACK>
} else {
state = ConnectionState.SynRcvd;
/// Send <SEQ=SND.ISS><ACK=RCV.CUR><MAX=RCV.MAX><BUFMAX=RBUF.MAX>
// <SYN><ACK>
}
return;
}
if (packet.Ack) {
if (!packet.Rst && segAck != sndIss) {
/// Send <SEQ=SEG.ACK + 1><RST>
state = ConnectionState.Closed;
throw new Exception("Connection Reset");
// TODO: deallocate connection
return;
}
}
Trace.TraceWarning("Shouldn't have gotten here");
break;
case ConnectionState.SynRcvd:
if (rcvIrs >= segSeq || segSeq > (rcvCur + rcvMax * 2))
/// Send <SEQ=SND.NXT><ACK=RCV.CUR><ACK>
return;
if (packet.Rst) {
if (passiveOpen)
state = ConnectionState.Listen;
else {
state = ConnectionState.Closed;
throw new Exception("Connection Refused");
// TODO: deallocate connection
}
return;
}
if (packet.Syn) {
/// Send <SEQ=SEG.ACK + 1><RST>
state = ConnectionState.Closed;
throw new Exception("Connection Reset");
// TODO: deallocate connection
return;
}
if (packet.Eak) {
/// Send <SEQ=SEG.ACK + 1><RST>
return;
}
if (packet.Ack) {
if (segAck == sndIss)
state = ConnectionState.Open;
else
/// Send <SEQ=SEG.ACK + 1><RST>
return;
} else
return;
if (packet.HasData || packet.Nul) {
bool inSequence = true;
// If the received segment is in sequence
if (inSequence) {
/// TODO: Copy the data (if any) to user buffers
rcvCur = segSeq;
/// Send <SEQ=SND.NXT><ACK=RCV.CUR><ACK>
} else {
if (outOfOrderAllowed)
// TODO: Copy the data (if any) to user buffers
;
/// Send <SEQ=SND.NXT><ACK=RCV.CUR><ACK><EACK><RCVDSEQNO1>
/// ...<RCVDSEQNOn>
}
}
break;
case ConnectionState.Open:
if (rcvCur >= segSeq || segSeq > (rcvCur + rcvMax * 2)) {
/// Send <SEQ=SND.NXT><ACK=RCV.CUR><ACK>
return;
}
if (packet.Rst) {
state = ConnectionState.CloseWait;
throw new Exception("Connection Reset");
return;
}
if (packet.Nul) {
rcvCur = segSeq;
/// Send <SEQ=SND.NXT><ACK=RCV.CUR><ACK>
return;
}
if (packet.Syn) {
/// Send <SEQ=SEG.ACK + 1><RST>
state = ConnectionState.Closed;
throw new Exception("Connection Reset");
// TODO: deallocate connection
return;
}
if (packet.Ack) {
if (sndUna <= segAck && segAck < sndNxt) {
sndUna = segAck + 1; // per rfc 1151
// TODO: Flush acknowledged segments
}
}
if (packet.Eak) {
// TODO: Flush acknowledged segments
}
if (packet.HasData) {
bool inSequence = true;
// If the received segment is in sequence
if (inSequence) {
/// TODO: Copy the data (if any) to user buffers
rcvCur = segSeq;
// This can have EACKS too, if you want
/// Send <SEQ=SND.NXT><ACK=RCV.CUR><ACK>
} else {
if (outOfOrderAllowed)
// TODO: Copy the data (if any) to user buffers
;
/// Send <SEQ=SND.NXT><ACK=RCV.CUR><ACK><EACK><RCVDSEQNO1>
/// ...<RCVDSEQNOn>
}
}
break;
}
}
public void Send(RdpPacket packet)
{
switch (state) {
case ConnectionState.Open:
if (sndNxt >= sndUna + sndMax)
throw new Exception("Error - insufficient resources to send data");
/// Send <SEQ=SND.NXT><ACK=RCV.CUR><ACK><Data>
sndNxt = sndNxt + 1;
break;
case ConnectionState.Listen:
case ConnectionState.SynRcvd:
case ConnectionState.SynSent:
case ConnectionState.Closed:
case ConnectionState.CloseWait:
throw new Exception("Error - connection not open");
break;
}
}
/// <summary>
/// Method to handle segment arrival
/// </summary>
/// <param name="inPacket"></param>
/// <param name="remote"></param>
public void OnSegmentArrival(RdpPacket inPacket, IPEndPoint remoteEP) {
try {
Monitor.Enter(this);
InternalOnSegmentArrival(inPacket, remoteEP);
} finally {
Monitor.Exit(this);
}
}
/// <summary>
/// Internal method to handle segment arrival. For this version, we already hold the lock.
/// </summary>
/// <param name="inPacket"></param>
/// <param name="remoteEP"></param>
private void InternalOnSegmentArrival(RdpPacket inPacket, IPEndPoint remoteEP) {
DateTime now = DateTime.Now;
log.DebugFormat("OnSegmentArrival: {0} - packet {1}", now, inPacket);
// count received bytes
bytesReceivedCount += inPacket.PacketLength;
totalBytesReceivedCount += inPacket.PacketLength;
packetsReceivedCount++;
switch (state) {
case ConnectionState.Closed:
case ConnectionState.CloseWait:
if (inPacket.Rst)
return;
else if (inPacket.Ack || inPacket.Nul) {
/// Send <SEQ=SEG.ACK + 1><RST>
RdpPacket packet = new RdpPacket(0);
packet.SeqNumber = inPacket.AckNumber + 1;
packet.Rst = true;
SendPacket(packet);
} else {
/// Send <SEQ=0><RST><ACK=SEG.SEQ><ACK>
RdpPacket packet = new RdpPacket(0);
packet.SeqNumber = 0;
packet.AckNumber = inPacket.SeqNumber;
packet.Rst = true;
packet.Ack = true;
SendPacket(packet);
}
break;
case ConnectionState.Listen:
if (inPacket.Rst)
return;
if (inPacket.Ack || inPacket.Nul) {
/// Send <SEQ=SEG.ACK + 1><RST>
RdpPacket packet = new RdpPacket(0);
packet.SeqNumber = inPacket.AckNumber + 1;
packet.Rst = true;
SendPacket(packet);
return;
}
if (inPacket.Syn) {
rcvCur = inPacket.SeqNumber;
rcvIrs = inPacket.SeqNumber;
sndMax = inPacket.MaxSegments;
sbufMax = inPacket.MaxSegmentSize;
/// Send <SEQ=SND.ISS><ACK=RCV.CUR><MAX=RCV.MAX><BUFMAX=RBUF.MAX>
/// <ACK><SYN>
RdpPacket packet = new RdpPacket(0, RdpPacket.OpenLength);
packet.SeqNumber = sndIss;
packet.AckNumber = rcvCur;
packet.Ack = true;
packet.Syn = true;
packet.MaxSegments = (short)rcvMax;
packet.MaxSegmentSize = (short)rbufMax;
packet.Sequenced = inPacket.Sequenced;
SendPacket(packet);
State = ConnectionState.SynRcvd;
return;
}
log.Warn("Shouldn't have gotten here");
break;
case ConnectionState.SynSent:
if (inPacket.Rst) {
if (inPacket.Ack) {
State = ConnectionState.Closed;
log.Warn("Connection Refused");
// TODO: deallocate connection
}
return;
}
if (inPacket.Syn) {
rcvCur = inPacket.SeqNumber;
rcvIrs = inPacket.SeqNumber;
sndMax = inPacket.MaxSegments;
sbufMax = inPacket.MaxSegmentSize;
if (inPacket.Ack) {
sndUna = inPacket.AckNumber + 1; // per rfc 1151
State = ConnectionState.Open;
/// Send <SEQ=SND.NXT><ACK=RCV.CUR><ACK>
RdpPacket packet = new RdpPacket(0);
packet.SeqNumber = sndNxt;
packet.AckNumber = rcvCur;
packet.Ack = true;
SendPacket(packet);
} else {
State = ConnectionState.SynRcvd;
/// Send <SEQ=SND.ISS><ACK=RCV.CUR><MAX=RCV.MAX><BUFMAX=RBUF.MAX>
/// <SYN><ACK>
RdpPacket packet = new RdpPacket(0, RdpPacket.OpenLength);
packet.SeqNumber = sndIss;
packet.AckNumber = rcvCur;
packet.Ack = true;
packet.Syn = true;
packet.MaxSegments = (short)rcvMax;
packet.MaxSegmentSize = (short)rbufMax;
packet.Sequenced = inPacket.Sequenced;
SendPacket(packet);
}
return;
}
if (inPacket.Ack) {
if (!inPacket.Rst && inPacket.AckNumber != sndIss) {
/// Send <SEQ=SEG.ACK + 1><RST>
RdpPacket packet = new RdpPacket(0);
packet.SeqNumber = inPacket.AckNumber + 1;
packet.Rst = true;
SendPacket(packet);
State = ConnectionState.Closed;
log.Warn("Connection Reset (by invalid ACK)");
// TODO: deallocate connection
return;
}
}
if (inPacket.Nul) {
log.Warn("Shouldn't have gotten here");
break;
}
log.Error("Shouldn't have gotten here");
break;
case ConnectionState.SynRcvd:
if (rcvIrs >= inPacket.SeqNumber || inPacket.SeqNumber > (rcvCur + rcvMax * 2)) {
/// Send <SEQ=SND.NXT><ACK=RCV.CUR><ACK>
RdpPacket packet = new RdpPacket(0);
packet.SeqNumber = sndNxt;
packet.AckNumber = rcvCur;
packet.Ack = true;
SendPacket(packet);
return;
}
if (inPacket.Rst) {
if (passiveOpen)
State = ConnectionState.Listen;
else {
State = ConnectionState.Closed;
throw new Exception("Connection Refused");
}
return;
}
if (inPacket.Syn) {
/// Send <SEQ=SEG.ACK + 1><RST>
RdpPacket packet = new RdpPacket(0);
packet.SeqNumber = inPacket.AckNumber + 1;
packet.Rst = true;
SendPacket(packet);
State = ConnectionState.Closed;
log.Warn("Connection Reset (by SYN)");
return;
}
if (inPacket.Eak) {
/// Send <SEQ=SEG.ACK + 1><RST>
RdpPacket packet = new RdpPacket(0);
packet.SeqNumber = inPacket.AckNumber + 1;
packet.Rst = true;
SendPacket(packet);
return;
}
if (inPacket.Ack) {
if (inPacket.AckNumber == sndIss)
State = ConnectionState.Open;
else {
/// Send <SEQ=SEG.ACK + 1><RST>
RdpPacket packet = new RdpPacket(0);
packet.SeqNumber = inPacket.AckNumber + 1;
packet.Rst = true;
SendPacket(packet);
return;
}
} else
return;
if (inPacket.HasData || inPacket.Nul) {
HandleDataPacket(inPacket);
/// Send <SEQ=SND.NXT><ACK=RCV.CUR><ACK><EACK><RCVDSEQNO1>
/// ...<RCVDSEQNOn>
int[] eakArray = AbridgedEakArray;
RdpPacket packet = new RdpPacket(0, eakArray.Length * 4);
packet.SeqNumber = sndNxt;
packet.AckNumber = rcvCur;
packet.Ack = true;
if (eakArray.Length > 0) {
packet.Eak = true;
packet.EakEntries = eakArray;
}
SendPacket(packet);
}
break;
case ConnectionState.Open:
if (inPacket.Rst) {
State = ConnectionState.CloseWait;
log.Warn("Connection Reset");
return;
}
if (rcvCur >= inPacket.SeqNumber || inPacket.SeqNumber > (rcvCur + rcvMax * 2)) {
/// Send <SEQ=SND.NXT><ACK=RCV.CUR><ACK>
RdpPacket packet = new RdpPacket(0);
packet.SeqNumber = sndNxt;
packet.AckNumber = rcvCur;
packet.Ack = true;
SendPacket(packet);
log.Debug("Acking packet that was already received");
return;
}
#if STRICT_SPEC
if (inPacket.Nul) {
rcvCur = inPacket.SeqNumber;
/// Send <SEQ=SND.NXT><ACK=RCV.CUR><ACK>
RdpPacket packet = new RdpPacket(0);
packet.SeqNumber = sndNxt;
packet.AckNumber = rcvCur;
packet.Ack = true;
SendPacket(packet);
Logger.Log(1, "Got Nul packet");
return;
}
#endif
if (inPacket.Syn) {
/// Send <SEQ=SEG.ACK + 1><RST>
RdpPacket packet = new RdpPacket(0);
packet.SeqNumber = inPacket.AckNumber + 1;
packet.Rst = true;
SendPacket(packet);
State = ConnectionState.Closed;
log.Warn("Connection Reset (by SYN)");
// TODO: deallocate connection
return;
}
if (inPacket.Ack) {
if (sndUna <= inPacket.AckNumber && inPacket.AckNumber < sndNxt) {
sndUna = inPacket.AckNumber + 1; // per rfc 1151
List<int> removeList = new List<int>();
int segAck = inPacket.AckNumber;
foreach (int segSeq in unacknowledgedPackets.Keys)
if (segSeq <= segAck)
removeList.Add(segSeq);
foreach (int segSeq in removeList)
unacknowledgedPackets.Remove(segSeq);
}
}
if (inPacket.Eak) {
int[] eakEntries = inPacket.EakEntries;
log.DebugFormat("Received eack packet: {0}", inPacket);
foreach (int segSeq in eakEntries)
unacknowledgedPackets.Remove(segSeq);
}
#if STRICT_SPEC
if (inPacket.HasData) {
#else
if (inPacket.HasData || inPacket.Nul) {
#endif
HandleDataPacket(inPacket);
/// Send <SEQ=SND.NXT><ACK=RCV.CUR><ACK><EACK><RCVDSEQNO1>
/// ...<RCVDSEQNOn>
int[] eakArray = AbridgedEakArray;
RdpPacket packet = new RdpPacket(0, eakArray.Length * 4);
packet.SeqNumber = sndNxt;
packet.AckNumber = rcvCur;
packet.Ack = true;
if (eakArray.Length > 0) {
packet.Eak = true;
packet.EakEntries = eakArray;
}
SendPacket(packet);
}
break;
}
}
/// <summary>
/// Internal version of the send method. For this version, we already hold the lock.
/// </summary>
/// <param name="packet"></param>
private void InternalSend(RdpPacket packet) {
switch (state) {
case ConnectionState.Open:
if (sndNxt >= sndUna + sndMax)
throw new Exception("Error - insufficient resources to send data");
/// Send <ACK=RCV.CUR><SEQ=SND.NXT><ACK><Data>;
packet.AckNumber = rcvCur;
packet.SeqNumber = sndNxt;
packet.Ack = true;
SendPacket(packet);
sndNxt = sndNxt + 1;
break;
case ConnectionState.Listen:
case ConnectionState.SynRcvd:
case ConnectionState.SynSent:
case ConnectionState.Closed:
case ConnectionState.CloseWait:
throw new Exception("Error - connection not open");
}
}
/// <summary>
/// Internal version of close. For this version, we already hold the lock.
/// </summary>
private void InternalClose() {
int ticks = Environment.TickCount - startTick;
log.InfoFormat("Sent {0} bytes, Received {1} bytes in {2} seconds",
bytesSentCount, bytesReceivedCount, ticks / 1000);
switch (state) {
case ConnectionState.Open: {
/// Send <SEQ=SND.NXT><RST>;
RdpPacket packet = new RdpPacket(0);
packet.SeqNumber = sndNxt;
packet.Rst = true;
SendPacket(packet);
}
State = ConnectionState.CloseWait;
// TODO: Start TIMWAIT Timer
break;
case ConnectionState.Listen:
State = ConnectionState.Closed;
break;
case ConnectionState.SynRcvd:
case ConnectionState.SynSent: {
/// Send <SEQ=SND.NXT><RST>
RdpPacket packet = new RdpPacket(0);
packet.SeqNumber = sndNxt;
packet.Rst = true;
SendPacket(packet);
}
State = ConnectionState.Closed;
break;
case ConnectionState.CloseWait:
throw new Exception("Error - Connection closing");
case ConnectionState.Closed:
throw new Exception("Error - Connection not open");
}
}
/// <summary>
/// Takes a packet with nothing but the data portion filled,
/// and does what is needed to send it out.
/// </summary>
/// <param name="packet"></param>
public void Send(RdpPacket packet) {
if (!valid)
throw new Exception("Called Send on closed connection");
try {
Monitor.Enter(this);
InternalSend(packet);
} finally {
Monitor.Exit(this);
}
}
public void Send(byte[] data) {
if (!valid)
throw new Exception("Called Send on closed connection");
RdpPacket packet = new RdpPacket(data.Length);
Array.Copy(data, 0, packet.PacketData, packet.DataOffset, data.Length);
Send(packet);
}
/// <summary>
/// Method to send the packet. If this is a client, we will pass in
/// null as the remoteEP, since the UdpClient object will have
/// called connect. We should already hold the lock on the connection.
/// </summary>
/// <param name="packet"></param>
private void SendPacket(RdpPacket packet) {
// count the bytes of outgoing packet
bytesSentCount += packet.PacketLength;
totalBytesSentCount += packet.PacketLength;
packetsSentCount++;
if (packet.HasData) {
const int IpHeaderLength = 20;
const int UdpHeaderLength = 8;
// If the packet is too large, throw
if (packet.PacketLength + IpHeaderLength + UdpHeaderLength > sbufMax)
throw new RdpFragmentationException("packet size {0} is too large for connection with max of {1}", packet.DataLength, sbufMax);
// If we have already sent as many packets as we can, throw
if (unacknowledgedPackets.Count > rcvMax)
throw new Exception("maximum unacknowledged packets exceeds limit");
DateTime now = DateTime.Now;
unacknowledgedPackets[packet.SeqNumber] = packet;
retransmissionTimer[packet.SeqNumber] = now.AddMilliseconds(RetransmissionTimeout);
log.DebugFormat("SendPacket: {0} - packet {1}", now, packet);
}
if (packet.Eak)
log.DebugFormat("sending packet with eak set: {0}", packet);
udpConn.Send(packet.PacketData, packet.PacketData.Length, remoteEP);
}
/// <summary>
/// Version of Open that bypasses the lock (used internally)
/// Generally with these methods, we already hold the lock, but
/// in this case, we don't need to hold the lock, since we are
/// still in the constructor.
/// </summary>
/// <param name="passiveOpen"></param>
/// <param name="rcvMax"></param>
/// <param name="rmaxBuf"></param>
/// <param name="isSequenced"></param>
private void InternalOpen(bool passiveOpen) {
if (state != ConnectionState.Closed)
throw new Exception("Error - connection already open");
this.passiveOpen = passiveOpen;
State = ConnectionState.Listen;
// Create a connection record
if (!passiveOpen) {
/// Send <SEQ=SND.ISS><MAX=SND.MAX><MAXBUF=RMAX.BUF><SYN>
RdpPacket packet = new RdpPacket(0, RdpPacket.OpenLength);
packet.SeqNumber = sndIss;
packet.Syn = true;
packet.MaxSegments = (short)rcvMax;
packet.MaxSegmentSize = (short)rbufMax;
packet.Sequenced = !outOfOrderAllowed;
SendPacket(packet);
State = ConnectionState.SynSent;
}
}
/// <summary>
/// Process the packet, adding it to either the out of order list
/// or the available list as appropriate. We already have the lock.
/// This will also update rcvCur to be appropriate.
/// </summary>
/// <param name="packet"></param>
private void HandleDataPacket(RdpPacket packet) {
outOfOrderPackets[packet.SeqNumber] = packet;
if (outOfOrderAllowed)
availableOutOfOrderPackets[packet.SeqNumber] = packet;
int[] sortedSequence = new int[outOfOrderPackets.Keys.Count];
outOfOrderPackets.Keys.CopyTo(sortedSequence, 0);
foreach (int segSeq in sortedSequence) {
if (segSeq == rcvCur + 1) {
RdpPacket currentPacket = outOfOrderPackets[segSeq];
log.DebugFormat("Queued packet {0} : {1}", currentPacket.SeqNumber, segSeq);
availablePackets.Add(currentPacket);
if (outOfOrderAllowed)
availableOutOfOrderPackets.Remove(segSeq);
rcvCur = segSeq;
outOfOrderPackets.Remove(segSeq);
}
}
Monitor.PulseAll(this);
}
