public MqttPacketBuffer Encode(MqttPacket packet)
{
if (packet == null)
{
throw new ArgumentNullException(nameof(packet));
}
// Leave enough head space for max header size (fixed + 4 variable remaining length = 5 bytes)
_bufferWriter.Reset(5);
_bufferWriter.Seek(5);
var fixedHeader = EncodePacket(packet, _bufferWriter);
var remainingLength = (uint)(_bufferWriter.Length - 5);
var publishPacket = packet as MqttPublishPacket;
if (publishPacket?.Payload != null)
{
remainingLength += (uint)publishPacket.Payload.Length;
}
var remainingLengthSize = MqttBufferWriter.GetLengthOfVariableInteger(remainingLength);
var headerSize = FixedHeaderSize + remainingLengthSize;
var headerOffset = 5 - headerSize;
// Position cursor on correct offset on beginning of array (has leading 0x0)
_bufferWriter.Seek(headerOffset);
_bufferWriter.WriteByte(fixedHeader);
_bufferWriter.WriteVariableByteInteger(remainingLength);
var buffer = _bufferWriter.GetBuffer();
var firstSegment = new ArraySegment <byte>(buffer, headerOffset, _bufferWriter.Length - headerOffset);
if (publishPacket?.Payload != null)
{
var payloadSegment = new ArraySegment <byte>(publishPacket.Payload, 0, publishPacket.Payload.Length);
return(new MqttPacketBuffer(firstSegment, payloadSegment));
}
return(new MqttPacketBuffer(firstSegment));
}