text: /*******************************************************************************
   * Copyright (c) 2014 IBM Corp.
   *
   * 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:
   *    Ian Craggs - initial API and implementation and/or initial documentation
   *******************************************************************************/
  
  #include "MQTTPacket.h"
  #include "StackTrace.h"
  
  #include <string.h>
  
  /**
   * Determines the length of the MQTT unsubscribe packet that would be produced using the supplied parameters
   * @param count the number of topic filter strings in topicFilters
   * @param topicFilters the array of topic filter strings to be used in the publish
   * @return the length of buffer needed to contain the serialized version of the packet
   */
  int MQTTSerialize_unsubscribeLength(int count, MQTTString topicFilters[])
  {
      int i;
      int len = 2; /* packetid */
  
      for (i = 0; i < count; ++i)
          len += 2 + MQTTstrlen(topicFilters[i]); /* length + topic*/
      return len;
  }
  
  /**
   * Serializes the supplied unsubscribe data into the supplied buffer, ready for sending
   * @param buf the raw buffer data, of the correct length determined by the remaining length field
   * @param buflen the length in bytes of the data in the supplied buffer
   * @param dup integer - the MQTT dup flag
   * @param packetid integer - the MQTT packet identifier
   * @param count - number of members in the topicFilters array
   * @param topicFilters - array of topic filter names
   * @return the length of the serialized data.  <= 0 indicates error
   */
  int MQTTSerialize_unsubscribe(unsigned char *buf,
                                int            buflen,
                                unsigned char  dup,
                                unsigned short packetid,
                                int            count,
                                MQTTString     topicFilters[])
  {
      unsigned char *ptr     = buf;
      MQTTHeader     header  = {0};
      int            rem_len = 0;
      int            rc      = -1;
      int            i       = 0;
  
      FUNC_ENTRY;
      if (MQTTPacket_len(rem_len = MQTTSerialize_unsubscribeLength(count, topicFilters)) > buflen)
      {
          rc = MQTTPACKET_BUFFER_TOO_SHORT;
          goto exit;
      }
  
      header.byte      = 0;
      header.bits.type = UNSUBSCRIBE;
      header.bits.dup  = dup;
      header.bits.qos  = 1;
      writeChar(&ptr, header.byte); /* write header */
  
      ptr += MQTTPacket_encode(ptr, rem_len); /* write remaining length */
      ;
  
      writeInt(&ptr, packetid);
  
      for (i = 0; i < count; ++i)
          writeMQTTString(&ptr, topicFilters[i]);
  
      rc = ptr - buf;
  exit:
      FUNC_EXIT_RC(rc);
      return rc;
  }
  
  /**
   * Deserializes the supplied (wire) buffer into unsuback data
   * @param packetid returned integer - the MQTT packet identifier
   * @param buf the raw buffer data, of the correct length determined by the remaining length field
   * @param buflen the length in bytes of the data in the supplied buffer
   * @return error code.  1 is success, 0 is failure
   */
  int MQTTDeserialize_unsuback(unsigned short *packetid, unsigned char *buf, int buflen)
  {
      unsigned char type = 0;
      unsigned char dup  = 0;
      int           rc   = 0;
  
      FUNC_ENTRY;
      rc = MQTTDeserialize_ack(&type, &dup, packetid, buf, buflen);
      if (type == UNSUBACK)
          rc = 1;
      FUNC_EXIT_RC(rc);
      return rc;
  }
  