paho.mqtt.m2mqtt/M2Mqtt/Messages/MqttMsgConnack.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 CONNACK message from broker to client
    /// </summary>
    public class MqttMsgConnack : MqttMsgBase
    {
        #region Constants...

        // return codes for CONNACK message
        public const byte CONN_ACCEPTED = 0x00;
        public const byte CONN_REFUSED_PROT_VERS = 0x01;
        public const byte CONN_REFUSED_IDENT_REJECTED = 0x02;
        public const byte CONN_REFUSED_SERVER_UNAVAILABLE = 0x03;
        public const byte CONN_REFUSED_USERNAME_PASSWORD = 0x04;
        public const byte CONN_REFUSED_NOT_AUTHORIZED = 0x05;

        private const byte TOPIC_NAME_COMP_RESP_BYTE_OFFSET = 0;
        private const byte TOPIC_NAME_COMP_RESP_BYTE_SIZE = 1;
        private const byte CONN_RETURN_CODE_BYTE_OFFSET = 1;
        private const byte CONN_RETURN_CODE_BYTE_SIZE = 1;

        #endregion

        #region Properties...

        /// <summary>
        /// Return Code
        /// </summary>
        public byte ReturnCode
        {
            get { return this.returnCode; }
            set { this.returnCode = value; }
        }

        #endregion

        // return code for CONNACK message
        private byte returnCode;

        /// <summary>
        /// Constructor
        /// </summary>
        public MqttMsgConnack()
        {
            this.type = MQTT_MSG_CONNACK_TYPE;
        }

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

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

            // read bytes from socket...
            channel.Receive(buffer);
            // ...and set return code from broker
            msg.returnCode = buffer[CONN_RETURN_CODE_BYTE_OFFSET];

            return msg;
        }

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

            // topic name compression response and connect return code
            varHeaderSize += (TOPIC_NAME_COMP_RESP_BYTE_SIZE + CONN_RETURN_CODE_BYTE_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_CONNACK_TYPE << MSG_TYPE_OFFSET);
            index++;

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

            // topic name compression response (reserved values. not used);
            buffer[index++] = 0x00;
            
            // connect return code
            buffer[index++] = this.returnCode;

            return buffer;
        }

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