text: #ifndef MQTT_MSG_H
  #define MQTT_MSG_H
  #include "mqtt_config.h"
  #ifdef  __cplusplus
  extern "C" {
  #endif
  
  /*
  * Copyright (c) 2014, Stephen Robinson
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  * notice, this list of conditions and the following disclaimer in the
  * documentation and/or other materials provided with the distribution.
  * 3. Neither the name of the copyright holder nor the names of its
  * contributors may be used to endorse or promote products derived
  * from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  *
  */
  /* 7      6     5     4     3     2     1     0 */
  /*|      --- Message Type----     |  DUP Flag |    QoS Level    | Retain  | */
  /*                    Remaining Length                 */
  
  
  enum mqtt_message_type
  {
    MQTT_MSG_TYPE_CONNECT = 1,
    MQTT_MSG_TYPE_CONNACK = 2,
    MQTT_MSG_TYPE_PUBLISH = 3,
    MQTT_MSG_TYPE_PUBACK = 4,
    MQTT_MSG_TYPE_PUBREC = 5,
    MQTT_MSG_TYPE_PUBREL = 6,
    MQTT_MSG_TYPE_PUBCOMP = 7,
    MQTT_MSG_TYPE_SUBSCRIBE = 8,
    MQTT_MSG_TYPE_SUBACK = 9,
    MQTT_MSG_TYPE_UNSUBSCRIBE = 10,
    MQTT_MSG_TYPE_UNSUBACK = 11,
    MQTT_MSG_TYPE_PINGREQ = 12,
    MQTT_MSG_TYPE_PINGRESP = 13,
    MQTT_MSG_TYPE_DISCONNECT = 14
  };
  
  enum mqtt_connect_return_code
  {
    CONNECTION_ACCEPTED = 0,
    CONNECTION_REFUSE_PROTOCOL,
    CONNECTION_REFUSE_ID_REJECTED,
    CONNECTION_REFUSE_SERVER_UNAVAILABLE,
    CONNECTION_REFUSE_BAD_USERNAME,
    CONNECTION_REFUSE_NOT_AUTHORIZED
  };
  
  typedef struct mqtt_message
  {
    uint8_t* data;
    uint16_t length;
  
  } mqtt_message_t;
  
  typedef struct mqtt_connection
  {
    mqtt_message_t message;
  
    uint16_t message_id;
    uint8_t* buffer;
    uint16_t buffer_length;
  
  } mqtt_connection_t;
  
  typedef struct mqtt_connect_info
  {
    char* client_id;
    char* username;
    char* password;
    char* will_topic;
    char* will_message;
    int keepalive;
    int will_length;
    int will_qos;
    int will_retain;
    int clean_session;
  
  } mqtt_connect_info_t;
  
  
  static inline int mqtt_get_type(uint8_t* buffer) { return (buffer[0] & 0xf0) >> 4; }
  static inline int mqtt_get_connect_return_code(uint8_t* buffer) { return buffer[3]; }
  static inline int mqtt_get_dup(uint8_t* buffer) { return (buffer[0] & 0x08) >> 3; }
  static inline int mqtt_get_qos(uint8_t* buffer) { return (buffer[0] & 0x06) >> 1; }
  static inline int mqtt_get_retain(uint8_t* buffer) { return (buffer[0] & 0x01); }
  
  void mqtt_msg_init(mqtt_connection_t* connection, uint8_t* buffer, uint16_t buffer_length);
  int mqtt_get_total_length(uint8_t* buffer, uint16_t length);
  const char* mqtt_get_publish_topic(uint8_t* buffer, uint16_t* length);
  const char* mqtt_get_publish_data(uint8_t* buffer, uint16_t* length);
  uint16_t mqtt_get_id(uint8_t* buffer, uint16_t length);
  
  mqtt_message_t* mqtt_msg_connect(mqtt_connection_t* connection, mqtt_connect_info_t* info);
  mqtt_message_t* mqtt_msg_publish(mqtt_connection_t* connection, const char* topic, const char* data, int data_length, int qos, int retain, uint16_t* message_id);
  mqtt_message_t* mqtt_msg_puback(mqtt_connection_t* connection, uint16_t message_id);
  mqtt_message_t* mqtt_msg_pubrec(mqtt_connection_t* connection, uint16_t message_id);
  mqtt_message_t* mqtt_msg_pubrel(mqtt_connection_t* connection, uint16_t message_id);
  mqtt_message_t* mqtt_msg_pubcomp(mqtt_connection_t* connection, uint16_t message_id);
  mqtt_message_t* mqtt_msg_subscribe(mqtt_connection_t* connection, const char* topic, int qos, uint16_t* message_id);
  mqtt_message_t* mqtt_msg_unsubscribe(mqtt_connection_t* connection, const char* topic, uint16_t* message_id);
  mqtt_message_t* mqtt_msg_pingreq(mqtt_connection_t* connection);
  mqtt_message_t* mqtt_msg_pingresp(mqtt_connection_t* connection);
  mqtt_message_t* mqtt_msg_disconnect(mqtt_connection_t* connection);
  
  
  #ifdef  __cplusplus
  }
  #endif
  
  #endif  /* MQTT_MSG_H */
  