// ikcp_input
/// used when you receive a low level packet (eg. UDP packet)
public int Input(byte[] data, int size)
{
uint prev_una = snd_una;
uint maxack = 0;
bool flag = false;
// the data is expected to have the reserved space
size -= Reserved;
if (size < OVERHEAD)
{
return(-1);
}
int reservedOffset = Reserved;
while (size >= OVERHEAD)
{
var decoder = new Decoder(data, reservedOffset);
uint conv_ = decoder.Decode32U();
var cmd = (CommandType)decoder.Decode8U();
byte frg = decoder.Decode8U();
ushort wnd = decoder.Decode16U();
uint ts = decoder.Decode32U();
uint sn = decoder.Decode32U();
uint una = decoder.Decode32U();
int len = (int)decoder.Decode32U();
reservedOffset = decoder.Position;
size -= OVERHEAD;
if (!ValidateSegment(size, conv_, cmd, len))
{
return(-1);
}
rmt_wnd = wnd;
ParseUna(una);
ShrinkBuf();
switch (cmd)
{
case CommandType.Ack:
UpdateAck(ts);
ParseAck(sn);
ShrinkBuf();
maxack = Math.Max(maxack, sn);
flag = true;
break;
case CommandType.Push:
if (sn >= rcv_nxt + rcv_wnd)
{
break;
}
AckPush(sn, ts);
if (sn < rcv_nxt)
{
break;
}
var seg = Segment.Lease();
seg.conversation = conv_;
seg.cmd = cmd;
seg.fragment = frg;
seg.window = wnd;
seg.timeStamp = ts;
seg.serialNumber = sn;
seg.unacknowledged = una;
seg.data.Write(data, reservedOffset, len);
ParseData(seg);
break;
case CommandType.WindowAsk:
// ready to send back CMD_WINS in flush
// tell remote my window size
probe |= ASK_TELL;
break;
}
reservedOffset += len;
size -= len;
}
if (flag)
{
ParseFastack(maxack);
}
// cwnd update when packet arrived
UpdateCongestionWindow(prev_una);
return(0);
}