paho.mqtt.m2mqtt/M2Mqtt/Messages/MqttMsgUnsuback.cs

/*
Copyright (c) 2013, 2014 Paolo Patierno

All rights reserved. This program and the accompanying materials
are made available under the terms of the Eclipse Public License v1.0
and Eclipse Distribution License v1.0 which accompany this distribution. 

The Eclipse Public License is available at 
   http://www.eclipse.org/legal/epl-v10.html
and the Eclipse Distribution License is available at 
   http://www.eclipse.org/org/documents/edl-v10.php.

Contributors:
   Paolo Patierno - initial API and implementation and/or initial documentation
*/

using System;

namespace uPLibrary.Networking.M2Mqtt.Messages
{
    /// <summary>
    /// Class for UNSUBACK message from broker to client
    /// </summary>
    public class MqttMsgUnsuback : MqttMsgBase
    {
        #region Properties...

        /// <summary>
        /// Message identifier for the unsubscribe message
        /// that is acknowledged
        /// </summary>
        public ushort MessageId
        {
            get { return this.messageId; }
            set { this.messageId = value; }
        }

        #endregion

        // message identifier
        private ushort messageId;
        
        /// <summary>
        /// Constructor
        /// </summary>
        public MqttMsgUnsuback()
        {
            this.type = MQTT_MSG_UNSUBACK_TYPE;
        }

        /// <summary>
        /// Parse bytes for a UNSUBACK message
        /// </summary>
        /// <param name="fixedHeaderFirstByte">First fixed header byte</param>
        /// <param name="channel">Channel connected to the broker</param>
        /// <returns>UNSUBACK message instance</returns>
        public static MqttMsgUnsuback Parse(byte fixedHeaderFirstByte, IMqttNetworkChannel channel)
        {
            byte[] buffer;
            int index = 0;
            MqttMsgUnsuback msg = new MqttMsgUnsuback();

            // get remaining length and allocate buffer
            int remainingLength = MqttMsgBase.decodeRemainingLength(channel);
            buffer = new byte[remainingLength];

            // read bytes from socket...
            channel.Receive(buffer);

            // message id
            msg.messageId = (ushort)((buffer[index++] << 8) & 0xFF00);
            msg.messageId |= (buffer[index++]);

            return msg;
        }

        public override byte[] GetBytes()
        {
            int fixedHeaderSize = 0;
            int varHeaderSize = 0;
            int payloadSize = 0;
            int remainingLength = 0;
            byte[] buffer;
            int index = 0;

            // message identifier
            varHeaderSize += MESSAGE_ID_SIZE;

            remainingLength += (varHeaderSize + payloadSize);

            // first byte of fixed header
            fixedHeaderSize = 1;

            int temp = remainingLength;
            // increase fixed header size based on remaining length
            // (each remaining length byte can encode until 128)
            do
            {
                fixedHeaderSize++;
                temp = temp / 128;
            } while (temp > 0);

            // allocate buffer for message
            buffer = new byte[fixedHeaderSize + varHeaderSize + payloadSize];

            // first fixed header byte
            buffer[index] = (byte)(MQTT_MSG_UNSUBACK_TYPE << MSG_TYPE_OFFSET);
            index++;

            // encode remaining length
            index = this.encodeRemainingLength(remainingLength, buffer, index);

            // message id
            buffer[index++] = (byte)((this.messageId >> 8) & 0x00FF); // MSB
            buffer[index++] = (byte)(this.messageId & 0x00FF); // LSB

            return buffer;
        }

        public override string ToString()
        {
#if TRACE
            return this.GetTraceString(
                "UNSUBACK",
                new object[] { "messageId" },
                new object[] { this.messageId });
#else
            return base.ToString();
#endif
        }
    }
}