/// <summary>
/// Receives typical data packets before dispatching them for consumption by the rest of SteamKit
/// </summary>
/// <param name="packet">The packet.</param>
private void ReceiveData(UdpPacket packet)
{
// Data packets are unexpected if a valid connection has not been established
if ( state != (int)State.Connected && state != (int)State.Disconnecting )
return;
// If we receive a packet that we've already processed (e.g. it got resent due to a lost ack)
// or that is already waiting to be processed, do nothing.
if ( packet.Header.SeqThis <= inSeqHandled || inPackets.ContainsKey(packet.Header.SeqThis) )
return;
inPackets.Add(packet.Header.SeqThis, packet);
while ( DispatchMessage() ) ;
}
/// <summary>
/// Receives the challenge and responds with a Connect request
/// </summary>
/// <param name="packet">The packet.</param>
private void ReceiveChallenge(UdpPacket packet)
{
if ( Interlocked.CompareExchange( ref state, (int)State.ConnectSent, (int)State.ChallengeReqSent ) != (int)State.ChallengeReqSent )
return;
ChallengeData cr = new ChallengeData();
cr.Deserialize(packet.Payload);
ConnectData cd = new ConnectData();
cd.ChallengeValue = cr.ChallengeValue ^ ConnectData.CHALLENGE_MASK;
MemoryStream ms = new MemoryStream();
cd.Serialize(ms);
ms.Seek(0, SeekOrigin.Begin);
SendSequenced(new UdpPacket(EUdpPacketType.Connect, ms));
inSeqHandled = packet.Header.SeqThis;
}
/// <summary>
/// Receives the notification of an accepted connection and sets the connection id that will be used for the
/// connection's duration.
/// </summary>
/// <param name="packet">The packet.</param>
private void ReceiveAccept(UdpPacket packet)
{
if ( Interlocked.CompareExchange( ref state, (int)State.Connected, (int)State.ConnectSent ) != (int)State.ConnectSent )
return;
DebugLog.WriteLine("UdpConnection", "Connection established");
remoteConnId = packet.Header.SourceConnID;
inSeqHandled = packet.Header.SeqThis;
OnConnected( EventArgs.Empty );
}
/// <summary>
/// Processes incoming packets, maintains connection consistency, and oversees outgoing packets.
/// </summary>
private void NetLoop(object param)
{
// Variables that will be used deeper in the function; locating them here avoids recreating
// them since they don't need to be.
var userRequestedDisconnect = false;
EndPoint packetSender = (EndPoint)new IPEndPoint(IPAddress.Any, 0);
byte[] buf = new byte[2048];
var epTask = param as Task<IPEndPoint>;
try
{
if ( epTask != null )
{
remoteEndPoint = epTask.Result;
}
else
{
DebugLog.WriteLine("UdpConnection", "Invalid endpoint supplied for connection: {0}", param);
}
}
catch ( AggregateException ae )
{
foreach ( var ex in ae.Flatten().InnerExceptions )
{
DebugLog.WriteLine("UdpConnection", "Endpoint task threw exception: {0}", ex);
}
}
if ( remoteEndPoint != null )
{
timeOut = DateTime.Now.AddSeconds(TIMEOUT_DELAY);
nextResend = DateTime.Now.AddSeconds(RESEND_DELAY);
if ( Interlocked.CompareExchange(ref state, (int)State.ChallengeReqSent, (int)State.Disconnected) != (int)State.Disconnected )
{
state = (int)State.Disconnected;
userRequestedDisconnect = true;
}
else
{
// Begin by sending off the challenge request
SendPacket(new UdpPacket(EUdpPacketType.ChallengeReq));
}
}
while ( state != (int)State.Disconnected )
{
try
{
// Wait up to 150ms for data, if none is found and the timeout is exceeded, we're done here.
if ( !sock.Poll(150000, SelectMode.SelectRead)
&& DateTime.Now > timeOut )
{
DebugLog.WriteLine("UdpConnection", "Connection timed out");
state = (int)State.Disconnected;
break;
}
// By using a 10ms wait, we allow for multiple packets sent at the time to all be processed before moving on
// to processing output and therefore Acks (the more we process at the same time, the fewer acks we have to send)
while ( sock.Poll(10000, SelectMode.SelectRead) )
{
int length = sock.ReceiveFrom(buf, ref packetSender);
// Ignore packets that aren't sent by the server we're connected to.
if ( !packetSender.Equals(remoteEndPoint) )
continue;
// Data from the desired server was received; delay timeout
timeOut = DateTime.Now.AddSeconds(TIMEOUT_DELAY);
MemoryStream ms = new MemoryStream(buf, 0, length);
UdpPacket packet = new UdpPacket(ms);
ReceivePacket(packet);
}
}
catch (IOException ex)
{
DebugLog.WriteLine("UdpConnection", "Exception occurred while reading packet: {0}", ex);
state = (int)State.Disconnected;
break;
}
catch ( SocketException e )
{
DebugLog.WriteLine("UdpConnection", "Critical socket failure: " + e.ErrorCode);
state = (int)State.Disconnected;
break;
}
// Send or resend any sequenced packets; a call to ReceivePacket can set our state to disconnected
// so don't send anything we have queued in that case
if ( state != (int)State.Disconnected )
SendPendingMessages();
// If we received data but had no data to send back, we need to manually Ack (usually tags along with
// outgoing data); also acks disconnections
if ( inSeq != inSeqAcked )
SendAck();
// If a graceful shutdown has been requested, nothing in the outgoing queue is discarded.
// Once it's empty, we exit, since the last packet was our disconnect notification.
if ( state == (int)State.Disconnecting && outPackets.Count == 0 )
{
DebugLog.WriteLine("UdpConnection", "Graceful disconnect completed");
state = (int)State.Disconnected;
userRequestedDisconnect = true;
break;
}
}
DebugLog.WriteLine("UdpConnection", "Calling OnDisconnected");
OnDisconnected( new DisconnectedEventArgs( userRequestedDisconnect ) );
}
/// <summary>
/// Receives the packet, performs all sanity checks and then passes it along as necessary.
/// </summary>
/// <param name="packet">The packet.</param>
private void ReceivePacket(UdpPacket packet)
{
// Check for a malformed packet
if ( !packet.IsValid )
return;
else if ( remoteConnId > 0 && packet.Header.SourceConnID != remoteConnId )
return;
DebugLog.WriteLine("UdpConnection", "<- Recv'd {0} Seq {1} Ack {2}; {3} bytes; Message: {4} bytes {5} packets",
packet.Header.PacketType, packet.Header.SeqThis, packet.Header.SeqAck,
packet.Header.PayloadSize, packet.Header.MsgSize, packet.Header.PacketsInMsg);
// Throw away any duplicate messages we've already received, making sure to
// re-ack it in case it got lost.
if ( packet.Header.PacketType == EUdpPacketType.Data && packet.Header.SeqThis < inSeq )
{
SendAck();
return;
}
// When we get a SeqAck, all packets with sequence numbers below that have been safely received by
// the server; we are now free to remove our copies
if ( outSeqAcked < packet.Header.SeqAck )
{
outSeqAcked = packet.Header.SeqAck;
// outSeqSent can be less than this in a very rare case involving resent packets.
if ( outSeqSent < outSeqAcked )
outSeqSent = outSeqAcked;
outPackets.RemoveAll( x => x.Header.SeqThis <= outSeqAcked );
nextResend = DateTime.Now.AddSeconds(RESEND_DELAY);
}
// inSeq should always be the latest value that we can ack, so advance it as far as is possible.
if ( packet.Header.SeqThis == inSeq + 1 )
do
inSeq++;
while ( inPackets.ContainsKey(inSeq + 1) );
switch ( packet.Header.PacketType )
{
case EUdpPacketType.Challenge:
ReceiveChallenge(packet);
break;
case EUdpPacketType.Accept:
ReceiveAccept(packet);
break;
case EUdpPacketType.Data:
ReceiveData(packet);
break;
case EUdpPacketType.Disconnect:
DebugLog.WriteLine("UdpConnection", "Disconnected by server");
state = (int)State.Disconnected;
return;
case EUdpPacketType.Datagram:
break;
default:
DebugLog.WriteLine("UdpConnection", "Received unexpected packet type " + packet.Header.PacketType);
break;
}
}
/// <summary>
/// Sends the packets as one sequenced, reliable net message.
/// </summary>
/// <param name="packets">The packets that make up the single net message</param>
private void SendSequenced(UdpPacket[] packets)
{
uint msgStart = outSeq;
foreach ( UdpPacket packet in packets )
{
SendSequenced(packet);
// Correct for any assumptions made for the single-packet case.
packet.Header.PacketsInMsg = (uint) packets.Length;
packet.Header.MsgStartSeq = msgStart;
}
}
/// <summary>
/// Sends a packet immediately.
/// </summary>
/// <param name="packet">The packet.</param>
private void SendPacket(UdpPacket packet)
{
packet.Header.SourceConnID = sourceConnId;
packet.Header.DestConnID = remoteConnId;
packet.Header.SeqAck = inSeqAcked = inSeq;
DebugLog.WriteLine("UdpConnection", "Sent -> {0} Seq {1} Ack {2}; {3} bytes; Message: {4} bytes {5} packets",
packet.Header.PacketType, packet.Header.SeqThis, packet.Header.SeqAck,
packet.Header.PayloadSize, packet.Header.MsgSize, packet.Header.PacketsInMsg);
byte[] data = packet.GetData();
try
{
sock.SendTo(data, remoteEndPoint);
}
catch ( SocketException e )
{
DebugLog.WriteLine("UdpConnection", "Critical socket failure: " + e.ErrorCode);
state = (int)State.Disconnected;
return;
}
// If we've been idle but completely acked for more than two seconds, the next sent
// packet will trip the resend detection. This fixes that.
if ( outSeqSent == outSeqAcked )
nextResend = DateTime.Now.AddSeconds(RESEND_DELAY);
// Sending should generally carry on from the packet most recently sent, even if it was a
// resend (who knows what else was lost).
if ( packet.Header.SeqThis > 0 )
outSeqSent = packet.Header.SeqThis;
}
/// <summary>
/// Sends the packet as a sequenced, reliable packet.
/// </summary>
/// <param name="packet">The packet.</param>
private void SendSequenced(UdpPacket packet)
{
packet.Header.SeqThis = outSeq;
packet.Header.MsgStartSeq = outSeq;
packet.Header.PacketsInMsg = 1;
outPackets.Add(packet);
outSeq++;
}
/// <summary>
/// Sends the data sequenced as a single message, splitting it into multiple parts if necessary.
/// </summary>
/// <param name="ms">The data to send.</param>
private void SendData( MemoryStream ms )
{
UdpPacket[] packets = new UdpPacket[ ( ms.Length / UdpPacket.MAX_PAYLOAD ) + 1 ];
for ( int i = 0 ; i < packets.Length ; i++ )
{
long index = i * UdpPacket.MAX_PAYLOAD;
long length = Math.Min( UdpPacket.MAX_PAYLOAD, ms.Length - index );
packets[ i ] = new UdpPacket( EUdpPacketType.Data, ms, length );
packets[ i ].Header.MsgSize = ( uint )ms.Length;
}
SendSequenced( packets );
}
/// <summary>
/// Receives the notification of an accepted connection and sets the connection id that will be used for the
/// connection's duration.
/// </summary>
/// <param name="packet">The packet.</param>
private void ReceiveAccept(UdpPacket packet)
{
if ( state != State.ConnectSent )
return;
DebugLog.WriteLine("UdpConnection", "Connection established");
state = State.Connected;
remoteConnId = packet.Header.SourceConnID;
inSeqHandled = packet.Header.SeqThis;
OnConnected( EventArgs.Empty );
}
/// <summary>
/// Receives the packet, performs all sanity checks and then passes it along as necessary.
/// </summary>
/// <param name="packet">The packet.</param>
private void ReceivePacket(UdpPacket packet)
{
// Check for a malformed packet
if (!packet.IsValid)
return;
else if (remoteConnId > 0 && packet.Header.SourceConnID != remoteConnId)
return;
DebugLog.WriteLine("UdpConnection", "<- Recv'd {0} Seq {1} Ack {2}; {3} bytes; Message: {4} bytes {5} packets",
packet.Header.PacketType, packet.Header.SeqThis, packet.Header.SeqAck,
packet.Header.PayloadSize, packet.Header.MsgSize, packet.Header.PacketsInMsg);
// Throw away any duplicate messages we've already received, making sure to
// re-ack it in case it got lost.
if (packet.Header.PacketType == EUdpPacketType.Data && packet.Header.SeqThis < inSeq)
{
SendAck();
return;
}
// When we get a SeqAck, all packets with sequence numbers below that have been safely received by
// the server; we are now free to remove our copies
if (outSeqAcked < packet.Header.SeqAck)
{
outSeqAcked = packet.Header.SeqAck;
// outSeqSent can be less than this in a very rare case involving resent packets.
if (outSeqSent < outSeqAcked)
outSeqSent = outSeqAcked;
outPackets.RemoveAll(x => x.Header.SeqThis <= outSeqAcked);
nextResend = DateTime.Now.AddSeconds(RESEND_DELAY);
}
// inSeq should always be the latest value that we can ack, so advance it as far as is possible.
if (packet.Header.SeqThis == inSeq + 1)
do
inSeq++;
while (inPackets.ContainsKey(inSeq + 1));
switch (packet.Header.PacketType)
{
case EUdpPacketType.Challenge:
ReceiveChallenge(packet);
break;
case EUdpPacketType.Accept:
ReceiveAccept(packet);
break;
case EUdpPacketType.Data:
ReceiveData(packet);
break;
case EUdpPacketType.Disconnect:
DebugLog.WriteLine("UdpConnection", "Disconnected by server");
state = State.Disconnected;
return;
case EUdpPacketType.Datagram:
break;
default:
DebugLog.WriteLine("UdpConnection", "Received unexpected packet type " + packet.Header.PacketType);
break;
}
}
/// <summary>
/// Processes incoming packets, maintains connection consistency, and oversees outgoing packets.
/// </summary>
private void NetLoop()
{
// Variables that will be used deeper in the function; locating them here avoids recreating
// them since they don't need to be.
EndPoint packetSender = (EndPoint)new IPEndPoint(IPAddress.Any, 0);
byte[] buf = new byte[2048];
timeOut = DateTime.Now.AddSeconds(TIMEOUT_DELAY);
nextResend = DateTime.Now.AddSeconds(RESEND_DELAY);
// Begin by sending off the challenge request
SendPacket(new UdpPacket(EUdpPacketType.ChallengeReq));
state = State.ChallengeReqSent;
while (state != State.Disconnected)
{
try
{
// Wait up to 150ms for data, if none is found and the timeout is exceeded, we're done here.
if (!sock.Poll(150000, SelectMode.SelectRead)
&& DateTime.Now > timeOut)
{
DebugLog.WriteLine("UdpConnection", "Connection timed out");
state = State.Disconnected;
break;
}
// By using a 10ms wait, we allow for multiple packets sent at the time to all be processed before moving on
// to processing output and therefore Acks (the more we process at the same time, the fewer acks we have to send)
while (sock.Poll(10000, SelectMode.SelectRead))
{
int length = sock.ReceiveFrom(buf, ref packetSender);
// Ignore packets that aren't sent by the server we're connected to.
if (!packetSender.Equals(remoteEndPoint))
continue;
// Data from the desired server was received; delay timeout
timeOut = DateTime.Now.AddSeconds(TIMEOUT_DELAY);
MemoryStream ms = new MemoryStream(buf, 0, length);
UdpPacket packet = new UdpPacket(ms);
ReceivePacket(packet);
}
}
catch (SocketException e)
{
DebugLog.WriteLine("UdpConnection", "Critical socket failure: " + e.ErrorCode);
state = State.Disconnected;
break;
}
// Send or resend any sequenced packets; a call to ReceivePacket can set our state to disconnected
// so don't send anything we have queued in that case
if (state != State.Disconnected)
SendPendingMessages();
// If we received data but had no data to send back, we need to manually Ack (usually tags along with
// outgoing data); also acks disconnections
if (inSeq != inSeqAcked)
SendAck();
// If a graceful shutdown has been requested, nothing in the outgoing queue is discarded.
// Once it's empty, we exit, since the last packet was our disconnect notification.
if (state == State.Disconnecting && outPackets.Count == 0)
{
DebugLog.WriteLine("UdpConnection", "Graceful disconnect completed");
state = State.Disconnected;
}
}
DebugLog.WriteLine("UdpConnection", "Calling OnDisconnected");
OnDisconnected(EventArgs.Empty);
}
