/// <summary>
/// request retransmission of lost sequences
/// </summary>
/// <param name="rcvdSeq">the sequence of the packet that was just received.</param>
private void DoRequestForRetransmission(uint rcvdSeq)
{
var desiredSeq = lastReceivedPacketSequence + 1;
List <uint> needSeq = new List <uint>();
needSeq.Add(desiredSeq);
uint bottom = desiredSeq + 1;
for (uint a = bottom; a < rcvdSeq; a++)
{
if (!outOfOrderPackets.ContainsKey(a))
{
needSeq.Add(a);
}
}
ServerPacket reqPacket = new ServerPacket();
byte[] reqData = new byte[4 + (needSeq.Count * 4)];
MemoryStream msReqData = new MemoryStream(reqData);
msReqData.Write(BitConverter.GetBytes((uint)needSeq.Count), 0, 4);
needSeq.ForEach(k => msReqData.Write(BitConverter.GetBytes(k), 0, 4));
reqPacket.Data = msReqData;
reqPacket.Header.Flags = PacketHeaderFlags.RequestRetransmit;
EnqueueSend(reqPacket);
LastRequestForRetransmitTime = DateTime.Now;
packetLog.DebugFormat("[{0}] Requested retransmit of {1}", session.LoggingIdentifier, needSeq.Select(k => k.ToString()).Aggregate((a, b) => a + ", " + b));
NetworkStatistics.S2C_RequestsForRetransmit_Aggregate_Increment();
}
public bool VerifyCRC(CryptoSystem fq)
{
if (Header.HasFlag(PacketHeaderFlags.EncryptedChecksum))
{
var key = ((Header.Checksum - headerChecksum) ^ payloadChecksum);
if (fq.Search(key))
{
fq.ConsumeKey(key);
return(true);
}
}
else
{
if (headerChecksum + payloadChecksum == Header.Checksum)
{
packetLog.DebugFormat("{0}", this);
return(true);
}
packetLog.DebugFormat("{0}, Checksum Failed", this);
}
NetworkStatistics.C2S_CRCErrors_Aggregate_Increment();
return(false);
}
// This is called from ConnectionListener.OnDataReceieve()->Session.ProcessPacket()->This
/// <summary>
/// Processes and incoming packet from a client.
/// </summary>
/// <param name="packet">The ClientPacket to process.</param>
public void ProcessPacket(ClientPacket packet)
{
packetLog.DebugFormat("[{0}] Processing packet {1}", session.LoggingIdentifier, packet.Header.Sequence);
NetworkStatistics.C2S_Packets_Aggregate_Increment();
// If the client is requesting a retransmission, pull those packets from the queue and resend them.
if (packet.Header.HasFlag(PacketHeaderFlags.RequestRetransmit))
{
if (VerifyCRC(packet))
{
foreach (uint sequence in packet.HeaderOptional.RetransmitData)
{
Retransmit(sequence);
}
NetworkStatistics.C2S_RequestsForRetransmit_Aggregate_Increment();
}
return;
}
// Check if this packet's sequence is a sequence which we have already processed.
// There are some exceptions:
// Sequence 0 as we have several Seq 0 packets during connect. This also cathes a case where it seems CICMDCommand arrives at any point with 0 sequence value too.
// If the only header on the packet is AckSequence. It seems AckSequence can come in with the same sequence value sometimes.
if (packet.Header.Sequence <= lastReceivedPacketSequence && packet.Header.Sequence != 0 &&
!(packet.Header.Flags == PacketHeaderFlags.AckSequence && packet.Header.Sequence == lastReceivedPacketSequence))
{
packetLog.WarnFormat("[{0}] Packet {1} received again", session.LoggingIdentifier, packet.Header.Sequence);
return;
}
// Check if this packet's sequence is greater then the next one we should be getting.
// If true we must store it to replay once we have caught up.
var desiredSeq = lastReceivedPacketSequence + 1;
if (packet.Header.Sequence > desiredSeq)
{
packetLog.DebugFormat("[{0}] Packet {1} received out of order", session.LoggingIdentifier, packet.Header.Sequence);
if (!outOfOrderPackets.ContainsKey(packet.Header.Sequence))
{
outOfOrderPackets.TryAdd(packet.Header.Sequence, packet);
}
if (desiredSeq + 2 <= packet.Header.Sequence && DateTime.Now - LastRequestForRetransmitTime > new TimeSpan(0, 0, 1))
{
DoRequestForRetransmission(packet.Header.Sequence);
}
return;
}
// If we reach here, this is a packet we should proceed with processing.
HandlePacket(packet);
// Finally check if we have any out of order packets or fragments we need to process;
CheckOutOfOrderPackets();
CheckOutOfOrderFragments();
}
private void SendPacket(ServerPacket packet)
{
packetLog.DebugFormat("[{0}] Sending packet {1}", session.LoggingIdentifier, packet.GetHashCode());
NetworkStatistics.S2C_Packets_Aggregate_Increment();
if (packet.Header.HasFlag(PacketHeaderFlags.EncryptedChecksum))
{
uint issacXor = ConnectionData.IssacServer.GetOffset();
packetLog.DebugFormat("[{0}] Setting Issac for packet {1} to {2}", session.LoggingIdentifier, packet.GetHashCode(), issacXor);
packet.IssacXor = issacXor;
}
SendPacketRaw(packet);
}
const uint MaxNumNakSeqIds = 115; //464 + header = 484; (464 - 4) / 4
/// <summary>
/// request retransmission of lost sequences
/// </summary>
/// <param name="rcvdSeq">the sequence of the packet that was just received.</param>
private void DoRequestForRetransmission(uint rcvdSeq)
{
var desiredSeq = lastReceivedPacketSequence + 1;
List <uint> needSeq = new List <uint>();
needSeq.Add(desiredSeq);
uint bottom = desiredSeq + 1;
if (rcvdSeq < bottom || rcvdSeq - bottom > CryptoSystem.MaximumEffortLevel)
{
session.Terminate(SessionTerminationReason.AbnormalSequenceReceived);
return;
}
uint seqIdCount = 1;
for (uint a = bottom; a < rcvdSeq; a++)
{
if (!outOfOrderPackets.ContainsKey(a))
{
needSeq.Add(a);
seqIdCount++;
if (seqIdCount >= MaxNumNakSeqIds)
{
break;
}
}
}
ServerPacket reqPacket = new ServerPacket();
byte[] reqData = new byte[4 + (needSeq.Count * 4)];
MemoryStream msReqData = new MemoryStream(reqData, 0, reqData.Length, true, true);
msReqData.Write(BitConverter.GetBytes((uint)needSeq.Count), 0, 4);
needSeq.ForEach(k => msReqData.Write(BitConverter.GetBytes(k), 0, 4));
reqPacket.Data = msReqData;
reqPacket.Header.Flags = PacketHeaderFlags.RequestRetransmit;
EnqueueSend(reqPacket);
LastRequestForRetransmitTime = DateTime.UtcNow;
packetLog.DebugFormat("[{0}] Requested retransmit of {1}", session.LoggingIdentifier, needSeq.Select(k => k.ToString()).Aggregate((a, b) => a + ", " + b));
NetworkStatistics.S2C_RequestsForRetransmit_Aggregate_Increment();
}
private bool VerifyCRC(ClientPacket packet)
{
bool encryptedChecksum =
!packet.Header.HasFlag(PacketHeaderFlags.RequestRetransmit) &&
packet.Header.HasFlag(PacketHeaderFlags.EncryptedChecksum);
if (encryptedChecksum)
{
#if NETDIAG
int?gen = GetGeneration(ConnectionData.IssacClient, packet);
if (gen != null)
{
// gen should always be 1 notch forward, but some programming errors have revealed gen to be 2 or more and since fixed
// generational ISSAC helps immensely when troubleshooting certain kinds of protocol problems
ConnectionData.IssacClient = GetGeneration(ConnectionData.IssacClient, gen.Value);
if (gen.Value != 1)
{
packetLog.Warn($"Packet CRC encryption generation out of sequence for packet {packet.Header.Sequence} gen {gen} {UnfoldFlags(packet.Header.Flags)}");
}
packetLog.Debug($"Verified encrypted CRC for packet {packet.Header.Sequence} gen {gen} {UnfoldFlags(packet.Header.Flags)}");
return(true);
}
#else
if (packet.VerifyChecksum(ConnectionData.IssacClient.GetOffset()))
{
return(true);
}
#endif
}
else
{
if (packet.VerifyChecksum(0))
{
packetLog.Debug($"Verified CRC for packet {packet.Header.Sequence} {UnfoldFlags(packet.Header.Flags)}");
return(true);
}
}
NetworkStatistics.C2S_CRCErrors_Aggregate_Increment();
return(false);
}
public bool VerifyCRC(CryptoSystem fq, bool rangeAdvance)
{
if (Header.HasFlag(PacketHeaderFlags.EncryptedChecksum))
{
if (VerifyEncryptedCRCAndLogResult(fq, rangeAdvance))
{
CRCVerified = true;
return(true);
}
}
else
{
if (Header.HasFlag(PacketHeaderFlags.RequestRetransmit))
{
// discard retransmission request with cleartext CRC
// client sends one encrypted version and one non encrypted version of each retransmission request
// honoring these causes client to drop because it's only expecting one of the two retransmission requests to be honored
// and it's more secure to only accept the trusted version
return(false);
}
else
{
if (VerifyChecksum(0))
{
packetLog.Debug($"{this}");
return(true);
}
else
{
packetLog.Debug($"{this}, Checksum Failed");
}
}
}
NetworkStatistics.C2S_CRCErrors_Aggregate_Increment();
return(false);
}
public bool VerifyCRC(CryptoSystem fq)
{
if (Header.HasFlag(PacketHeaderFlags.EncryptedChecksum))
{
if (VerifyEncryptedCRCAndLogResult(fq))
{
return(true);
}
}
else
{
if (VerifyChecksum())
{
packetLog.DebugFormat("{0}", this);
return(true);
}
packetLog.DebugFormat("{0}, Checksum Failed", this);
}
NetworkStatistics.C2S_CRCErrors_Aggregate_Increment();
return(false);
}
// This is called from ConnectionListener.OnDataReceieve()->Session.ProcessPacket()->This
/// <summary>
/// Processes and incoming packet from a client.
/// </summary>
/// <param name="packet">The ClientPacket to process.</param>
public void ProcessPacket(ClientPacket packet)
{
if (isReleased) // Session has been removed
{
return;
}
packetLog.DebugFormat("[{0}] Processing packet {1}", session.LoggingIdentifier, packet.Header.Sequence);
NetworkStatistics.C2S_Packets_Aggregate_Increment();
if (!packet.VerifyCRC(ConnectionData.CryptoClient, true))
{
return;
}
#region order-insensitive "half-processing"
if (packet.Header.HasFlag(PacketHeaderFlags.Disconnect))
{
session.Terminate(SessionTerminationReason.PacketHeaderDisconnect);
return;
}
if (packet.Header.HasFlag(PacketHeaderFlags.NetErrorDisconnect))
{
session.Terminate(SessionTerminationReason.ClientSentNetworkErrorDisconnect);
return;
}
// If the client is requesting a retransmission process it immediately
if (packet.Header.HasFlag(PacketHeaderFlags.RequestRetransmit))
{
foreach (uint sequence in packet.HeaderOptional.RetransmitData)
{
Retransmit(sequence);
}
NetworkStatistics.C2S_RequestsForRetransmit_Aggregate_Increment();
}
// depending on the current session state:
// Set the next timeout tick value, to compare against in the WorldManager
// Sessions that have gone past the AuthLoginRequest step will stay active for a longer period of time (exposed via configuration)
// Sessions that in the AuthLoginRequest will have a short timeout, as set in the AuthenticationHandler.DefaultAuthTimeout.
// Example: Applications that check uptime will stay in the AuthLoginRequest state.
session.Network.TimeoutTick = (session.State == SessionState.AuthLoginRequest) ?
DateTime.UtcNow.AddSeconds(AuthenticationHandler.DefaultAuthTimeout).Ticks : // Default is 15s
DateTime.UtcNow.AddSeconds(NetworkManager.DefaultSessionTimeout).Ticks; // Default is 60s
#endregion
#region Reordering stage
// Reordering stage
// Check if this packet's sequence is a sequence which we have already processed.
// There are some exceptions:
// Sequence 0 as we have several Seq 0 packets during connect. This also cathes a case where it seems CICMDCommand arrives at any point with 0 sequence value too.
// If the only header on the packet is AckSequence. It seems AckSequence can come in with the same sequence value sometimes.
if (packet.Header.Sequence <= lastReceivedPacketSequence && packet.Header.Sequence != 0 &&
!(packet.Header.Flags == PacketHeaderFlags.AckSequence && packet.Header.Sequence == lastReceivedPacketSequence))
{
packetLog.WarnFormat("[{0}] Packet {1} received again", session.LoggingIdentifier, packet.Header.Sequence);
return;
}
// Check if this packet's sequence is greater then the next one we should be getting.
// If true we must store it to replay once we have caught up.
var desiredSeq = lastReceivedPacketSequence + 1;
if (packet.Header.Sequence > desiredSeq)
{
packetLog.DebugFormat("[{0}] Packet {1} received out of order", session.LoggingIdentifier, packet.Header.Sequence);
if (!outOfOrderPackets.ContainsKey(packet.Header.Sequence))
{
outOfOrderPackets.TryAdd(packet.Header.Sequence, packet);
}
if (desiredSeq + 2 <= packet.Header.Sequence && DateTime.Now - LastRequestForRetransmitTime > new TimeSpan(0, 0, 1))
{
DoRequestForRetransmission(packet.Header.Sequence);
}
return;
}
#endregion
#region Final processing stage
// Processing stage
// If we reach here, this is a packet we should proceed with processing.
HandleOrderedPacket(packet);
// Process data now in sequence
// Finally check if we have any out of order packets or fragments we need to process;
CheckOutOfOrderPackets();
CheckOutOfOrderFragments();
#endregion
}
