コード例 #1
0
        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));
        }