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MQTTSubscribeClient.c
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MQTTSubscribeClient.c
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/*******************************************************************************
* 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:https://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http:https://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 subscribe 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_subscribeLength(int count, MQTTString topicFilters[])
{
int i;
int len = 2; /* packetid */
for (i = 0; i < count; ++i)
len += 2 + MQTTstrlen(topicFilters[i]) + 1; /* length + topic + req_qos */
return len;
}
/**
* Serializes the supplied subscribe data into the supplied buffer, ready for sending
* @param buf the buffer into which the packet will be serialized
* @param buflen the length in bytes of the supplied bufferr
* @param dup integer - the MQTT dup flag
* @param packetid integer - the MQTT packet identifier
* @param count - number of members in the topicFilters and reqQos arrays
* @param topicFilters - array of topic filter names
* @param requestedQoSs - array of requested QoS
* @return the length of the serialized data. <= 0 indicates error
*/
int MQTTSerialize_subscribe(unsigned char* buf, int buflen, unsigned char dup, unsigned short packetid, int count,
MQTTString topicFilters[], int requestedQoSs[])
{
unsigned char *ptr = buf;
MQTTHeader header = {0};
int rem_len = 0;
int rc = 0;
int i = 0;
FUNC_ENTRY;
if (MQTTPacket_len(rem_len = MQTTSerialize_subscribeLength(count, topicFilters)) > buflen)
{
rc = MQTTPACKET_BUFFER_TOO_SHORT;
goto exit;
}
header.byte = 0;
header.bits.type = SUBSCRIBE;
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]);
writeChar(&ptr, requestedQoSs[i]);
}
rc = ptr - buf;
exit:
FUNC_EXIT_RC(rc);
return rc;
}
/**
* Deserializes the supplied (wire) buffer into suback data
* @param packetid returned integer - the MQTT packet identifier
* @param maxcount - the maximum number of members allowed in the grantedQoSs array
* @param count returned integer - number of members in the grantedQoSs array
* @param grantedQoSs returned array of integers - the granted qualities of service
* @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_suback(unsigned short* packetid, int maxcount, int* count, int grantedQoSs[], unsigned char* buf, int buflen)
{
MQTTHeader header = {0};
unsigned char* curdata = buf;
unsigned char* enddata = NULL;
int rc = 0;
int mylen;
FUNC_ENTRY;
header.byte = readChar(&curdata);
if (header.bits.type != SUBACK)
goto exit;
curdata += (rc = MQTTPacket_decodeBuf(curdata, &mylen)); /* read remaining length */
enddata = curdata + mylen;
if (enddata - curdata < 2)
goto exit;
*packetid = readInt(&curdata);
*count = 0;
while (curdata < enddata)
{
if (*count > maxcount)
{
rc = -1;
goto exit;
}
grantedQoSs[(*count)++] = readChar(&curdata);
}
rc = 1;
exit:
FUNC_EXIT_RC(rc);
return rc;
}