/// <summary>
/// FIN wait1 handler
/// </summary>
/// <param name="con"></param>
/// <param name="buffer"></param>
private unsafe static void finWaitOneHandler(TCPConnection con, byte *buffer)
{
TCPHeader *header = (TCPHeader *)buffer;
/**
* ACK received?
*/
if ((header->Flags & (FLAG_ACK)) > 0)
{
con.State = TCPConnectionState.FIN_WAIT2;
con.AcknowledgeNumber = Byte.ReverseBytes(Byte.ReverseBytes(header->Sequence) + 1);
}
else if ((header->Flags & (FLAG_FIN)) > 0)
{
con.SequenceNumber = Byte.ReverseBytes(Byte.ReverseBytes(con.SequenceNumber) + 1);
con.State = TCPConnectionState.CLOSING;
con.AcknowledgeNumber = Byte.ReverseBytes(Byte.ReverseBytes(header->Sequence) + 1);
SendPacket(con.IP, con.SequenceNumber, con.AcknowledgeNumber, con.InPort, con.DestPort, FLAG_FIN, null, 0);
}
else
{
// Failed?
}
}
/// <summary>
/// Finish header and create checksum
/// </summary>
/// <param name="packet"></param>
/// <param name="header"></param>
/// <param name="sourceIp"></param>
/// <param name="packetLength"></param>
/// <param name="dataLength"></param>
/// <returns></returns>
private static unsafe bool FinishHeader(NetPacketDesc *packet, TCPHeader *header, byte[] sourceIp, int packetLength, int dataLength)
{
// Welp!
if (packetLength % 4 != 0)
{
return(false);
}
header->Length = (byte)((packetLength / 4) << 4);
ushort size = (ushort)packetLength;
size += (ushort)sizeof(TCPChecksum);
// Let's introduce some junk (i love that :))
TCPChecksum *checksumHeader = (TCPChecksum *)(packet->buffer + packet->start - sizeof(TCPChecksum));
Memory.Memcpy(checksumHeader->SrcIP, Network.Settings->IP, 4);
Memory.Memcpy(checksumHeader->DstIP, Util.ObjectToVoidPtr(sourceIp), 4);
checksumHeader->Protocol = PROTOCOL_TCP;
checksumHeader->Reserved = 0;
checksumHeader->Length = Byte.ReverseBytes((ushort)((ushort)packetLength + dataLength));
byte *ptr = packet->buffer + packet->start - sizeof(TCPChecksum);
header->Checksum = NetworkTools.Checksum(ptr, size + dataLength);
return(true);
}
/// <summary>
/// Reset connection
/// </summary>
/// <param name="con"></param>
private unsafe static void Reset(TCPConnection con, byte *buffer)
{
TCPHeader *header = (TCPHeader *)buffer;
con.AcknowledgeNumber = Byte.ReverseBytes(Byte.ReverseBytes(header->Sequence) + 1);
SendPacket(con.IP, con.SequenceNumber, con.AcknowledgeNumber, con.InPort, con.DestPort, FLAG_RST | FLAG_ACK, null, 0);
con.State = TCPConnectionState.CLOSED;
}
/// <summary>
/// TCP packet handler
/// </summary>
/// <param name="xid">Identification ID</param>
/// <param name="buffer">Buffer pointer</param>
/// <param name="size">Packet size</param>
private static unsafe void handler(byte[] sourceIp, byte *buffer, uint size)
{
TCPHeader *header = (TCPHeader *)buffer;
ushort dest = Byte.ReverseBytes(header->DestPort);
if (m_connections[dest] != null)
{
handleConnection(m_connections[dest], sourceIp, buffer, size);
}
}
/// <summary>
/// Add header to packet
/// </summary>
/// <param name="packet"></param>
/// <param name="srcPort"></param>
/// <param name="dstPort"></param>
/// <param name="flags"></param>
/// <param name="seqNum"></param>
/// <param name="ackNum"></param>
/// <param name="winSize"></param>
/// <returns></returns>
private static unsafe TCPHeader *addHeader(NetPacketDesc *packet, ushort srcPort, ushort dstPort, byte flags, uint seqNum, uint ackNum, ushort winSize)
{
packet->start -= (short)sizeof(TCPHeader);
// Generate stub header
TCPHeader *header = (TCPHeader *)(packet->buffer + packet->start);
header->SourcePort = Byte.ReverseBytes(srcPort);
header->DestPort = Byte.ReverseBytes(dstPort);
header->Flags = flags;
header->Urgent = 0;
header->WindowSize = Byte.ReverseBytes(winSize);
header->Acknowledge = ackNum;
header->Sequence = seqNum;
header->Checksum = 0;
return(header);
}
/// <summary>
/// Established handler
/// </summary>
/// <param name="connection"></param>
/// <param name="sourceIP"></param>
/// <param name="buffer"></param>
/// <param name="size"></param>
private static unsafe void LastAckHandler(TCPConnection connection, byte[] sourceIP, byte *buffer, uint size)
{
TCPHeader *header = (TCPHeader *)buffer;
/**
*
* Possible flags:
* - PUSH
* - FIN
*/
if ((header->Flags & FLAG_ACK) > 0)
{
connection.State = TCPConnectionState.TIME_WAIT;
}
else
{
}
}
/// <summary>
/// CLOSING handler
/// </summary>
/// <param name="con"></param>
/// <param name="buffer"></param>
private unsafe static void closingHandler(TCPConnection con, byte *buffer)
{
TCPHeader *header = (TCPHeader *)buffer;
if ((header->Flags & (FLAG_ACK)) > 0)
{
con.SequenceNumber = Byte.ReverseBytes(Byte.ReverseBytes(con.SequenceNumber) + 1);
con.AcknowledgeNumber = Byte.ReverseBytes(Byte.ReverseBytes(header->Sequence) + 1);
// AND We're DONE!
setConnectionForWait(con);
}
else
{
// Error handling?
}
}
/// <summary>
/// FIN wait2 handler
/// </summary>
/// <param name="con"></param>
/// <param name="buffer"></param>
private unsafe static void finWaitTwoHandler(TCPConnection con, byte *buffer)
{
TCPHeader *header = (TCPHeader *)buffer;
if ((header->Flags & (FLAG_FIN)) > 0)
{
con.SequenceNumber = Byte.ReverseBytes(Byte.ReverseBytes(con.SequenceNumber) + 1);
con.AcknowledgeNumber = Byte.ReverseBytes(Byte.ReverseBytes(header->Sequence) + 1);
SendPacket(con.IP, con.SequenceNumber, con.AcknowledgeNumber, con.InPort, con.DestPort, FLAG_ACK, null, 0);
setConnectionForWait(con);
}
else
{
}
}
/// <summary>
/// Syn sent handler
/// </summary>
/// <param name="con"></param>
/// <param name="buffer"></param>
private unsafe static void SynSentHandler(TCPConnection con, byte *buffer)
{
TCPHeader *header = (TCPHeader *)buffer;
if ((header->Flags & (FLAG_SYN | FLAG_ACK)) == (FLAG_SYN | FLAG_ACK))
{
con.SequenceNumber = Byte.ReverseBytes(Byte.ReverseBytes(con.SequenceNumber) + 1);
con.State = TCPConnectionState.ESTABLISHED;
con.AcknowledgeNumber = Byte.ReverseBytes(Byte.ReverseBytes(header->Sequence) + 1);
SendPacket(con.IP, con.SequenceNumber, Byte.ReverseBytes(Byte.ReverseBytes(header->Sequence) + 1), con.InPort, con.DestPort, FLAG_ACK, null, 0);
}
else
{
// Failed?
}
}
/// <summary>
/// Syn received
/// </summary>
/// <param name="con"></param>
/// <param name="buffer"></param>
private unsafe static void SynReceivedHandler(TCPConnection con, byte *buffer)
{
TCPHeader *header = (TCPHeader *)buffer;
/**
* ACK received?
*/
if ((header->Flags & (FLAG_ACK)) > 0)
{
con.SequenceNumber = Byte.ReverseBytes(Byte.ReverseBytes(con.SequenceNumber) + 1);
con.State = TCPConnectionState.ESTABLISHED;
/**
* Do we need to notify we have a new connection?
*/
if (con.Type == TCPConnectionType.CHILD_CONNECTION)
{
/**
* Put ACCEPT in queue
*/
TCPPacketDescriptor *buf = (TCPPacketDescriptor *)Heap.Alloc(sizeof(TCPPacketDescriptor));
buf->Size = 4;
buf->Type = TCPPacketDescriptorTypes.ACCEPT;
buf->Data = (byte *)Heap.Alloc(4);
buf->xid = con.XID;
for (int i = 0; i < 4; i++)
{
buf->Data[i] = con.IP[i];
}
con.BaseConnection.ReceiveQueue.Push(buf);
}
}
else
{
// Failed?
}
}
/// <summary>
/// Send packet to TCP
/// </summary>
/// <param name="destIP"></param>
/// <param name="seqNum"></param>
/// <param name="acknumb"></param>
/// <param name="srcPort"></param>
/// <param name="destPort"></param>
/// <param name="flags"></param>
/// <param name="data"></param>
/// <param name="count"></param>
/// <returns></returns>
private static unsafe bool SendPacket(byte[] destIP, uint seqNum, uint acknumb, ushort srcPort, ushort destPort, byte flags, byte *data, int count)
{
NetPacketDesc *packet = NetPacket.Alloc();
if (count > 0)
{
Memory.Memcpy(packet->buffer + packet->start, data, count);
packet->end += (short)count;
}
TCPHeader *outHeader = addHeader(packet, srcPort, destPort, flags, seqNum, acknumb, 8192);
FinishHeader(packet, outHeader, destIP, sizeof(TCPHeader), count);
IPV4.Send(packet, destIP, PROTOCOL_TCP);
NetPacket.Free(packet);
return(true);
}
/// <summary>
/// Established handler
/// </summary>
/// <param name="connection"></param>
/// <param name="sourceIP"></param>
/// <param name="buffer"></param>
/// <param name="size"></param>
private static unsafe void EstablishedHandler(TCPConnection connection, byte[] sourceIP, byte *buffer, uint size)
{
TCPHeader *header = (TCPHeader *)buffer;
/**
*
* Possible flags:
* - PUSH
* - FIN
*/
if ((header->Flags & (FLAG_FIN | FLAG_ACK)) == (FLAG_FIN | FLAG_ACK))
{
connection.AcknowledgeNumber = Byte.ReverseBytes(Byte.ReverseBytes(header->Sequence) + 1);
SendPacket(connection.IP, connection.SequenceNumber, Byte.ReverseBytes(Byte.ReverseBytes(header->Sequence) + 1), connection.InPort, connection.DestPort, FLAG_ACK, null, 0);
setConnectionForWait(connection);
}
else if ((header->Flags & FLAG_FIN) > 0)
{
/**
* Todo: We need acknowledge our application here with status CLOSE_WAIT, for now we shift over to the LAST_ACK state
*/
connection.AcknowledgeNumber = Byte.ReverseBytes(Byte.ReverseBytes(header->Sequence) + 1);
connection.State = TCPConnectionState.LAST_ACK;
SendPacket(connection.IP, connection.SequenceNumber, Byte.ReverseBytes(Byte.ReverseBytes(header->Sequence) + 1), connection.InPort, connection.DestPort, FLAG_ACK, null, 0);
Sleep(300);
SendPacket(connection.IP, connection.SequenceNumber, 0x00, connection.InPort, connection.DestPort, FLAG_FIN, null, 0);
}
if ((header->Flags & FLAG_PSH) > 0)
{
int sizePacket = (int)size - sizeof(TCPHeader);
/**
* Push packet in Queue
*/
TCPPacketDescriptor *buf = (TCPPacketDescriptor *)Heap.Alloc(sizeof(TCPPacketDescriptor));
buf->Size = sizePacket;
buf->Type = TCPPacketDescriptorTypes.RECEIVE;
buf->Data = (byte *)Heap.Alloc(sizePacket);
buf->xid = connection.XID;
Memory.Memcpy(buf->Data, buffer + sizeof(TCPHeader), sizePacket);
Queue queue = connection.ReceiveQueue;
/**
* Is this a connection or a member?
*/
if (connection.Type != TCPConnectionType.CONNECTION)
{
queue = connection.BaseConnection.ReceiveQueue;
}
queue.Push(buf);
connection.AcknowledgeNumber = Byte.ReverseBytes(Byte.ReverseBytes(header->Sequence) + (uint)sizePacket);
SendPacket(connection.IP, connection.SequenceNumber, connection.AcknowledgeNumber, connection.InPort, connection.DestPort, FLAG_ACK, null, 0);
}
else
{
}
}
/// <summary>
/// Listen state handler
/// </summary>
/// <param name="connection"></param>
/// <param name="sourceIP"></param>
/// <param name="buffer"></param>
/// <param name="size"></param>
private static unsafe void HandleListen(TCPConnection connection, byte[] sourceIP, byte *buffer, uint size)
{
TCPHeader *header = (TCPHeader *)buffer;
ushort srcPort = header->SourcePort;
long id = GenerateID(sourceIP, srcPort);
TCPConnection clientConnection = (TCPConnection)connection.Clients.GetByKey(id);
/**
* Do we need to create a connection or just pass it though?
*/
if (clientConnection == null)
{
/**
* We only handle SYN packets here!
*/
if ((header->Flags & FLAG_SYN) == 0)
{
//Close(connection);
return;
}
/**
* Add connection to clients list
*/
clientConnection = new TCPConnection();
clientConnection.XID = id;
clientConnection.InPort = connection.InPort;
clientConnection.DestPort = Byte.ReverseBytes(header->SourcePort);
clientConnection.SequenceNumber = (uint)Random.Rand();
clientConnection.State = TCPConnectionState.SYN_RECEIVED;
clientConnection.IP = new byte[4];
for (int i = 0; i < 4; i++)
{
clientConnection.IP[i] = sourceIP[i];
}
clientConnection.AcknowledgeNumber = Byte.ReverseBytes(header->Acknowledge);
clientConnection.Type = TCPConnectionType.CHILD_CONNECTION;
clientConnection.Clients = connection.Clients;
clientConnection.BaseConnection = connection;
connection.Clients.Add(id, clientConnection);
/**
* Send SYN_ACK and transition to SYN_RECEIVED state
*/
clientConnection.SequenceNumber = Byte.ReverseBytes(Byte.ReverseBytes(connection.SequenceNumber) + 1);
clientConnection.State = TCPConnectionState.SYN_RECEIVED;
clientConnection.AcknowledgeNumber = Byte.ReverseBytes(Byte.ReverseBytes(header->Sequence) + 1);
SendPacket(clientConnection.IP, clientConnection.SequenceNumber, Byte.ReverseBytes(Byte.ReverseBytes(header->Sequence) + 1), clientConnection.InPort, clientConnection.DestPort, FLAG_SYN | FLAG_ACK, null, 0);
}
else
{
handleConnection(clientConnection, sourceIP, buffer, size);
}
}