private bool TryParseCompressedMessage(DataLinkMessageType type, ReadOnlySequence <byte> buffer, int inlinelength, out DCTransportMessage transportMessage)
{
var isShortForm = inlinelength != 0x0f;
int length;
if (isShortForm)
{
if (buffer.Length <= 1)
{
transportMessage = DCTransportMessage.Incomplete;
return(false);
}
length = (inlinelength << 8) + buffer.FirstSpan[0];
buffer = buffer.Slice(1);
}
else
{
if (buffer.Length <= 4)
{
transportMessage = DCTransportMessage.Incomplete;
return(false);
}
length = ReadInt32(ref buffer);
}
if (buffer.Length < length)
{
transportMessage = DCTransportMessage.Incomplete;
return(false);
}
transportMessage = new DCTransportMessage(1 + (isShortForm ? 1 : 4) + length, type, buffer.Slice(0, length));
return(true);
}
public bool TryParseTransportMessage(ReadOnlySequence <byte> buffer, out DCTransportMessage transportMessage)
{
const int HighFourBitMask = 0xF0;
const int LowFourBitMask = 0x0F;
var first = buffer.FirstSpan[0];
var highFourBit = first & HighFourBitMask;
if (highFourBit == 0)
{
switch ((DataLinkMessageType)first)
{
case DataLinkMessageType.Unknown:
case DataLinkMessageType.Incomplete:
throw new InvalidOperationException("Bad tranport data.");
case DataLinkMessageType.Disconnect:
case DataLinkMessageType.SyncNode:
// No body message.
transportMessage = new DCTransportMessage(1, (DataLinkMessageType)first, ReadOnlySequence <byte> .Empty);
return(true);
case DataLinkMessageType.AckNo:
case DataLinkMessageType.AckYes:
case DataLinkMessageType.Ping:
case DataLinkMessageType.Sub:
case DataLinkMessageType.Unsub:
// 4 bytes body.
if (buffer.Length < 1 + 4)
{
transportMessage = DCTransportMessage.Incomplete;
return(false);
}
transportMessage = new DCTransportMessage(1 + 4, (DataLinkMessageType)first, buffer.Slice(1, 4));
return(true);
case DataLinkMessageType.Query:
// 8 bytes body.
if (buffer.Length < 1 + 4 + 4)
{
transportMessage = DCTransportMessage.Incomplete;
return(false);
}
transportMessage = new DCTransportMessage(1 + 4 + 4, (DataLinkMessageType)first, buffer.Slice(1, 4 + 4));
return(true);
default:
break;
}
}
else
{
switch ((DataLinkMessageType)highFourBit)
{
case DataLinkMessageType.Connect:
case DataLinkMessageType.ReplySyncNode:
case DataLinkMessageType.Payload:
case DataLinkMessageType.PayloadWithAck:
return(TryParseCompressedMessage((DataLinkMessageType)highFourBit, buffer.Slice(1), first & LowFourBitMask, out transportMessage));
default:
break;
}
}
throw new InvalidOperationException("Bad tranport data.");
}
