protected override void WritePacketHeader(byte[] header, MessageDirection direction, uint messageId, RfpIdentifier rfp, ReadOnlyMemory <byte> data)
{
rfp.CopyTo(header);
rfp.CopyTo(header.AsSpan(6));
if (direction == MessageDirection.FromOmm)
{
header[6] = 0x02;
}
else
{
header[0] = 0x02;
}
header[12] = 0xa0;
BinaryPrimitives.WriteUInt16BigEndian(header.AsSpan(14), (ushort)data.Length);
header[16] = 0xba;
header[17] = 0xbe;
}
protected override void WritePacketHeader(byte[] header, MessageDirection direction, uint messageId, RfpIdentifier rfp, ReadOnlyMemory <byte> data)
{
var span = header.AsSpan();
rfp.CopyTo(header);
rfp.CopyTo(span.Slice(6));
if (direction == MessageDirection.FromOmm)
{
span[6] = 0x02;
}
else
{
span[0] = 0x02;
}
span[12] = 0x08;
span = span.Slice(14);
span[0] = 0x45; //version + IHL
span[1] = 0x10; //tos
BinaryPrimitives.WriteUInt16BigEndian(span.Slice(2), (ushort)(span.Length + data.Length)); //total length
BinaryPrimitives.WriteUInt16BigEndian(span.Slice(4), (ushort)messageId); //identification
BinaryPrimitives.WriteUInt16BigEndian(span.Slice(6), 0x4000); // flags
span[8] = 0xff; //ttl
span[9] = 6; //protocol
if (direction == MessageDirection.ToOmm)
{
rfp.CopyTo(span.Slice(10)); //source address
span[12] = 127;
span[16] = 127; //destination address
span[17] = 0;
span[18] = 0;
span[19] = 1;
}
else
{
rfp.CopyTo(span.Slice(14)); //destination address
span[16] = 127;
span[12] = 127; //source address
span[13] = 0;
span[14] = 0;
span[15] = 1;
}
span = span.Slice(20);
int seq;
int ack;
if (direction == MessageDirection.ToOmm)
{
seq = _rfpSequenceNumbers.AddOrUpdate(rfp, x => data.Length, (x, i) => i + data.Length);
ack = _ommSequenceNumbers.GetOrAdd(rfp, 1);
BinaryPrimitives.WriteUInt16BigEndian(span, 54321); //source port
BinaryPrimitives.WriteUInt16BigEndian(span.Slice(2), 16321); //destination port
}
else
{
seq = _ommSequenceNumbers.AddOrUpdate(rfp, x => data.Length, (x, i) => i + data.Length);
ack = _rfpSequenceNumbers.GetOrAdd(rfp, 1);
BinaryPrimitives.WriteUInt16BigEndian(span, 16321); //source port
BinaryPrimitives.WriteUInt16BigEndian(span.Slice(2), 54321); //destination port
}
BinaryPrimitives.WriteInt32BigEndian(span.Slice(4), seq - data.Length);
BinaryPrimitives.WriteInt32BigEndian(span.Slice(8), ack);
span[12] = 0x50; //data offset
span[13] = 0b0001_0000; //flags
span[14] = 0xff; //window size
span[15] = 0xff;
}