internal virtual void Post(TcpFlags flags, uint ackno, uint seqno, uint length = 0, int retransmission = 0, bool timeout = false)
{
SegmentsContext segments = null;
lock (this)
{
lock (this.SegmentsContexts)
{
segments = new SegmentsContext()
{
AcknowledgeNo = ackno,
SequenceNo = seqno,
Flags = flags,
Length = length,
Stopwatch = new Stopwatch(),
Retransmission = retransmission,
Pcb = this,
Timeout = timeout,
};
if (retransmission > 0)
{
long nackNo = segments.SequenceNo + segments.Length;
if (this.SegmentsContexts.TryAdd(nackNo, segments))
{
segments.Stopwatch.Start();
}
}
}
}
TcpFrame frame = segments.CreateFrame(this);
this.Locator.Tcp.Output(frame);
}
public TcpPcb(TcpFrame frame, ILayerLocator locator)
{
if (frame == null)
{
throw new ArgumentNullException(nameof(frame));
}
this.Locator = locator ?? throw new ArgumentNullException(nameof(locator));
this.AcknowledgeNo = frame.AcknowledgeNo;
this.SequenceNo = frame.SequenceNo;
this.AddressFamily = frame.AddressFamily;
this.Destination = frame.Destination;
this.Source = frame.Source;
this.Ttl = frame.Ttl;
this.Aborted = false;
this.Estableshed = false;
this.SendBufferSize = frame.WindowSize;
this.ReceiveBufferSize = frame.WindowSize;
this.InputStream = new TcpInputStream(this);
this.InputStream.Receive += (sender, e) =>
{
uint ackNo = Convert.ToUInt32(e.SequenceNo + e.Payload.Length);
uint seqNo = e.AcknowledgeNo;
this.SequenceNo = ackNo;
{
this.Post(TcpFlags.TCP_ACK, ackNo, seqNo, 0);
}
this.OnMessage(e.Payload);
};
}
public virtual void Output(TcpFrame frame)
{
IPFrame ip = ToIPFrame(frame);
if (ip != null)
{
Locator.IPv4.Output(ip);
}
}
private void RST(TcpPcb pcb, TcpFrame frame)
{
uint seqno = frame.AcknowledgeNo;
uint ackno = frame.SequenceNo + 1;
pcb.State = TcpState.LAST_ACK;
pcb.Post(TcpFlags.TCP_RST, ackno, seqno);
ClosePCB(pcb, TcpState.CLOSED);
}
public override bool Send(BufferSegment payload)
{
if (payload == null || payload.Length <= 0)
{
return(false);
}
bool sendto(BufferSegment buffer)
{
if (buffer == null || buffer.Length <= 0)
{
return(false);
}
SegmentsContext segments = null;
lock (this)
{
lock (this.SegmentsContexts)
{
segments = new SegmentsContext()
{
AcknowledgeNo = this.SequenceNo,
SequenceNo = this.AcknowledgeNo,
Flags = TcpFlags.TCP_PSH | TcpFlags.TCP_ACK,
Length = (uint)buffer.Length,
Stopwatch = new Stopwatch(),
Pcb = this,
Retransmission = 5,
Payload = payload,
};
var ackNo = segments.SequenceNo + segments.Length;
if (this.SegmentsContexts.TryAdd(ackNo, segments))
{
segments.Stopwatch.Start();
this.AcknowledgeNo += segments.Length;
}
}
}
TcpFrame frame = segments.CreateFrame(this);
this.Locator.Tcp.Output(frame);
return(true);
}
foreach (BufferSegment buffer in Slices(payload))
{
if (!sendto(buffer))
{
return(false);
}
}
return(true);
}
public virtual void Input(TcpFrame frame)
{
if (frame == null || frame.Payload == null)
{
return;
}
if (frame.Payload.Length <= 0)
{
return;
}
lock (this.Frames)
{
if (frame.SequenceNo == this.Pcb.SequenceNo)
{
this.Pcb.SequenceNo = frame.SequenceNo + (uint)frame.Payload.Length;
OnReceive(frame);
var node = this.Frames.First;
while (node != null)
{
TcpFrame f = node.Value;
var current = node;
node = current.Next;
if (f.SequenceNo == this.Pcb.SequenceNo)
{
this.Frames.Remove(current);
this.Pcb.SequenceNo = f.SequenceNo + (uint)f.Payload.Length;
OnReceive(f);
}
}
}
else if (this.Frames.Count <= 0)
{
this.Frames.AddLast(frame);
}
else
{
var node = this.Frames.Last;
if (frame.SequenceNo == node.Value.SequenceNo)
{
return;
}
else if (frame.SequenceNo > node.Value.SequenceNo)
{
this.Frames.AddLast(frame);
}
else
{
node = this.Frames.Last;
while (node != null)
{
TcpFrame f = node.Value;
if (f.SequenceNo == frame.SequenceNo)
{
return;
}
if (f.SequenceNo < frame.SequenceNo)
{
this.Frames.AddAfter(node, frame);
break;
}
node = node.Previous;
}
if (node == null)
{
this.Frames.AddFirst(frame);
}
}
}
}
}
protected virtual void OnReceive(TcpFrame frame)
{
this.Receive?.Invoke(this, frame);
}
public static TcpFrame ParseFrame(IPFrame ip, bool checksum = true)
{
if (ip == null)
{
return(null);
}
TcpFrame frame = null;
BufferSegment packet = ip.Payload;
packet.UnsafeAddrOfPinnedArrayElement((p) =>
{
tcp_hdr *tcphdr = (tcp_hdr *)p;
if (tcphdr == null)
{
return;
}
int hdrlen_bytes = TCPH_HDRLEN_BYTES(tcphdr);
if (hdrlen_bytes < TCP_HLEN || hdrlen_bytes > packet.Length) // 错误的数据报
{
return;
}
int len = packet.Length - hdrlen_bytes;
if (len < 0)
{
return;
}
TcpFlags flags = (TcpFlags)TCPH_FLAGS(tcphdr);
if (checksum && tcphdr->chksum != 0)
{
uint pseudo_checksum = CheckSum.inet_chksum_pseudo((byte *)p.ToPointer(),
(uint)ProtocolType.Tcp,
(uint)packet.Length,
ip.SourceAddressV4,
ip.DestinationAddressV4);
if (pseudo_checksum != 0)
{
return;
}
}
long payload_offset = 0;
fixed(byte *stream = packet.Buffer)
{
payload_offset = ((byte *)p + hdrlen_bytes) - stream;
}
BufferSegment message_data = new BufferSegment(packet.Buffer, unchecked ((int)payload_offset), len);
BufferSegment options_data = null;
int options_size = hdrlen_bytes - sizeof(tcp_hdr);
if (options_size <= 0)
{
options_data = new BufferSegment(BufferSegment.Empty);
}
else
{
options_data = new BufferSegment(packet.Buffer,
packet.Offset + sizeof(tcp_hdr), options_size);
}
frame = new TcpFrame(new IPEndPoint(ip.Source, CheckSum.ntohs(tcphdr->src)), new IPEndPoint(ip.Destination, CheckSum.ntohs(tcphdr->dest)), message_data)
{
Ttl = ip.Ttl,
AcknowledgeNo = CheckSum.ntohl(tcphdr->ackno),
SequenceNo = CheckSum.ntohl(tcphdr->seqno),
WindowSize = CheckSum.ntohs(tcphdr->wnd),
Flags = flags,
SourceMacAddress = ip.SourceMacAddress,
DestinationMacAddress = ip.DestinationMacAddress,
Options = options_data,
UrgentPointer = CheckSum.ntohs(tcphdr->urgp)
};
});
return(frame);
}
public static IPFrame ToIPFrame(TcpFrame frame)
{
if (frame == null)
{
throw new ArgumentNullException(nameof(frame));
}
if (frame.AddressFamily != AddressFamily.InterNetwork)
{
throw new ArgumentNullException("TCP frames of this address family type are not supported.");
}
BufferSegment options_data = frame.Options;
int options_size = options_data?.Length ?? 0;
int payload_offset = sizeof(tcp_hdr) + options_size;
int payload_size = frame.Payload?.Length ?? 0;
byte[] message = new byte[payload_offset + payload_size];
fixed(byte *pinned = message)
{
tcp_hdr *tcphdr = (tcp_hdr *)pinned;
tcphdr->dest = CheckSum.htons((ushort)frame.Destination.Port);
tcphdr->src = CheckSum.htons((ushort)frame.Source.Port);
tcphdr->seqno = CheckSum.htonl(frame.SequenceNo);
tcphdr->ackno = CheckSum.htonl(frame.AcknowledgeNo);
tcphdr->urgp = CheckSum.htons(frame.UrgentPointer);
tcphdr->wnd = CheckSum.htons(frame.WindowSize);
TCPH_HDRLEN_SET(tcphdr, payload_offset >> 2);
TCPH_FLAGS_SET(tcphdr, (int)frame.Flags);
if (options_size > 0)
{
IntPtr destination_options = (IntPtr)(pinned + sizeof(tcp_hdr));
Marshal.Copy(options_data.Buffer, options_data.Offset, destination_options, options_size);
}
if (payload_size > 0)
{
using (MemoryStream ms = new MemoryStream(message, payload_offset, payload_size))
{
ms.Write(frame.Payload.Buffer, frame.Payload.Offset, payload_size);
}
}
ushort pseudo_checksum = CheckSum.inet_chksum_pseudo(pinned, (uint)ProtocolType.Tcp, (uint)message.Length,
IPFrame.GetAddressV4(frame.Source.Address),
IPFrame.GetAddressV4(frame.Destination.Address));
if (pseudo_checksum == 0)
{
pseudo_checksum = 0xffff;
}
tcphdr->chksum = pseudo_checksum;
}
return(new IPFrame(ProtocolType.Tcp, frame.Source.Address, frame.Destination.Address, new BufferSegment(message))
{
Ttl = frame.Ttl,
SourceMacAddress = frame.SourceMacAddress,
DestinationMacAddress = frame.DestinationMacAddress,
});
}
public virtual void Input(TcpFrame frame)
{
string pcbKey = GetPcbKey(frame.Source, frame.Destination);
TcpPcb pcb = null;
lock (_pcbTable)
{
_pcbTable.TryGetValue(pcbKey, out pcb);
if (pcb == null)
{
pcb = new TcpPcb(frame, this.Locator)
{
State = TcpState.SYN_RCVD
};
if (0 == (frame.Flags & TcpFlags.TCP_SYN) || // 不接受此套接字则积极拒绝
!this.Locator.Sockets.BeginAccept(pcb))
{
RST(pcb, frame);
return;
}
_pcbTable.TryAdd(pcbKey, pcb);
pcb.Open += (sender, e) =>
{
if (!pcb.Estableshed)
{
pcb.Estableshed = true;
var socket = this.Locator.Sockets.EndAccept(pcb);
if (socket == null)
{
pcb.Close();
}
else
{
pcb.OnOpen(e);
}
}
};
pcb.Abort += (sender, e) => ClosePCB(sender as TcpPcb, TcpState.CLOSED);
}
}
lock (pcb)
{
if (0 != (frame.Flags & TcpFlags.TCP_SYN))
{
uint seqno = pcb.AcknowledgeNo++;
uint ackno = ++pcb.SequenceNo;
pcb.Post(TcpFlags.TCP_SYN | TcpFlags.TCP_ACK, ackno, seqno, 1, 3);
}
else if (0 != (frame.Flags & TcpFlags.TCP_RST) ||
0 != (frame.Flags & (TcpFlags.TCP_CWR | TcpFlags.TCP_ECE | TcpFlags.TCP_UGR)))
{
RST(pcb, frame);
}
else
{
pcb.SendBufferSize = frame.WindowSize;
if (0 != (frame.Flags & TcpFlags.TCP_ACK))
{
pcb.Ack(frame.AcknowledgeNo);
}
if (0 != (frame.Flags & TcpFlags.TCP_PSH))
{
uint pylen = (uint)frame.Payload.Length;
uint seqno = frame.AcknowledgeNo;
uint ackno = frame.SequenceNo + pylen;
if (ackno >= pcb.SequenceNo)
{
pcb.InputStream.Input(frame);
}
else
{
pcb.Post(TcpFlags.TCP_ACK, ackno, seqno, 0);
}
}
else if (0 != (frame.Flags & TcpFlags.TCP_FIN))
{
uint seqno = frame.AcknowledgeNo;
uint ackno = frame.SequenceNo + 1;
pcb.Post(TcpFlags.TCP_ACK, ackno, seqno, 0);
ClosePCB(pcb, TcpState.CLOSED);
}
}
}
}
