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/src/MQTTPacket.h>
  #include <MQTTPacket/src/StackTrace.h>
  #include <string.h>
  
  /**
    * Determines the length of the MQTT connect packet that would be produced using the supplied connect options.
    * @param options the options to be used to build the connect packet
    * @return the length of buffer needed to contain the serialized version of the packet
    */
  int MQTTSerialize_connectLength(MQTTPacket_connectData* options)
  {
  	int len = 0;
  
  	FUNC_ENTRY;
  
  	if (options->MQTTVersion == 3)
  		len = 12; /* variable depending on MQTT or MQIsdp */
  	else if (options->MQTTVersion == 4)
  		len = 10;
  
  	len += MQTTstrlen(options->clientID)+2;
  	if (options->willFlag)
  		len += MQTTstrlen(options->will.topicName)+2 + MQTTstrlen(options->will.message)+2;
  	if (options->username.cstring || options->username.lenstring.data)
  		len += MQTTstrlen(options->username)+2;
  	if (options->password.cstring || options->password.lenstring.data)
  		len += MQTTstrlen(options->password)+2;
  
  	FUNC_EXIT_RC(len);
  	return len;
  }
  
  
  /**
    * Serializes the connect options into the buffer.
    * @param buf the buffer into which the packet will be serialized
    * @param len the length in bytes of the supplied buffer
    * @param options the options to be used to build the connect packet
    * @return serialized length, or error if 0
    */
  int MQTTSerialize_connect(unsigned char* buf, int buflen, MQTTPacket_connectData* options)
  {
  	unsigned char *ptr = buf;
  	MQTTHeader header = {0};
  	MQTTConnectFlags flags = {0};
  	int len = 0;
  	int rc = -1;
  
  	FUNC_ENTRY;
  	if (MQTTPacket_len(len = MQTTSerialize_connectLength(options)) > buflen)
  	{
  		rc = MQTTPACKET_BUFFER_TOO_SHORT;
  		goto exit;
  	}
  
  	header.byte = 0;
  	header.bits.type = CONNECT;
  	writeChar(&ptr, header.byte); /* write header */
  
  	ptr += MQTTPacket_encode(ptr, len); /* write remaining length */
  
  	if (options->MQTTVersion == 4)
  	{
  		writeCString(&ptr, "MQTT");
  		writeChar(&ptr, (char) 4);
  	}
  	else
  	{
  		writeCString(&ptr, "MQIsdp");
  		writeChar(&ptr, (char) 3);
  	}
  
  	flags.all = 0;
  	flags.bits.cleansession = options->cleansession;
  	flags.bits.will = (options->willFlag) ? 1 : 0;
  	if (flags.bits.will)
  	{
  		flags.bits.willQoS = options->will.qos;
  		flags.bits.willRetain = options->will.retained;
  	}
  
  	if (options->username.cstring || options->username.lenstring.data)
  		flags.bits.username = 1;
  	if (options->password.cstring || options->password.lenstring.data)
  		flags.bits.password = 1;
  
  	writeChar(&ptr, flags.all);
  	writeInt(&ptr, options->keepAliveInterval);
  	writeMQTTString(&ptr, options->clientID);
  	if (options->willFlag)
  	{
  		writeMQTTString(&ptr, options->will.topicName);
  		writeMQTTString(&ptr, options->will.message);
  	}
  	if (flags.bits.username)
  		writeMQTTString(&ptr, options->username);
  	if (flags.bits.password)
  		writeMQTTString(&ptr, options->password);
  
  	rc = ptr - buf;
  
  	exit: FUNC_EXIT_RC(rc);
  	return rc;
  }
  
  
  /**
    * Deserializes the supplied (wire) buffer into connack data - return code
    * @param sessionPresent the session present flag returned (only for MQTT 3.1.1)
    * @param connack_rc returned integer value of the connack return code
    * @param buf the raw buffer data, of the correct length determined by the remaining length field
    * @param len the length in bytes of the data in the supplied buffer
    * @return error code.  1 is success, 0 is failure
    */
  int MQTTDeserialize_connack(unsigned char* sessionPresent, unsigned char* connack_rc, unsigned char* buf, int buflen)
  {
  	MQTTHeader header = {0};
  	unsigned char* curdata = buf;
  	unsigned char* enddata = NULL;
  	int rc = 0;
  	int mylen;
  	MQTTConnackFlags flags = {0};
  
  	FUNC_ENTRY;
  	header.byte = readChar(&curdata);
  	if (header.bits.type != CONNACK)
  		goto exit;
  
  	curdata += (rc = MQTTPacket_decodeBuf(curdata, &mylen)); /* read remaining length */
  	enddata = curdata + mylen;
  	if (enddata - curdata < 2)
  		goto exit;
  
  	flags.all = readChar(&curdata);
  	*sessionPresent = flags.bits.sessionpresent;
  	*connack_rc = readChar(&curdata);
  
  	rc = 1;
  exit:
  	FUNC_EXIT_RC(rc);
  	return rc;
  }
  
  
  /**
    * Serializes a 0-length packet into the supplied buffer, ready for writing to a socket
    * @param buf the buffer into which the packet will be serialized
    * @param buflen the length in bytes of the supplied buffer, to avoid overruns
    * @param packettype the message type
    * @return serialized length, or error if 0
    */
  int MQTTSerialize_zero(unsigned char* buf, int buflen, unsigned char packettype)
  {
  	MQTTHeader header = {0};
  	int rc = -1;
  	unsigned char *ptr = buf;
  
  	FUNC_ENTRY;
  	if (buflen < 2)
  	{
  		rc = MQTTPACKET_BUFFER_TOO_SHORT;
  		goto exit;
  	}
  	header.byte = 0;
  	header.bits.type = packettype;
  	writeChar(&ptr, header.byte); /* write header */
  
  	ptr += MQTTPacket_encode(ptr, 0); /* write remaining length */
  	rc = ptr - buf;
  exit:
  	FUNC_EXIT_RC(rc);
  	return rc;
  }
  
  
  /**
    * Serializes a disconnect packet into the supplied buffer, ready for writing to a socket
    * @param buf the buffer into which the packet will be serialized
    * @param buflen the length in bytes of the supplied buffer, to avoid overruns
    * @return serialized length, or error if 0
    */
  int MQTTSerialize_disconnect(unsigned char* buf, int buflen)
  {
  	return MQTTSerialize_zero(buf, buflen, DISCONNECT);
  }
  
  
  /**
    * Serializes a disconnect packet into the supplied buffer, ready for writing to a socket
    * @param buf the buffer into which the packet will be serialized
    * @param buflen the length in bytes of the supplied buffer, to avoid overruns
    * @return serialized length, or error if 0
    */
  int MQTTSerialize_pingreq(unsigned char* buf, int buflen)
  {
  	return MQTTSerialize_zero(buf, buflen, PINGREQ);
  }
  