MQTTSubscribeClient.c

00001 /*******************************************************************************
00002  * Copyright (c) 2014 IBM Corp.
00003  *
00004  * All rights reserved. This program and the accompanying materials
00005  * are made available under the terms of the Eclipse Public License v1.0
00006  * and Eclipse Distribution License v1.0 which accompany this distribution.
00007  *
00008  * The Eclipse Public License is available at
00009  *    http://www.eclipse.org/legal/epl-v10.html
00010  * and the Eclipse Distribution License is available at
00011  *   http://www.eclipse.org/org/documents/edl-v10.php.
00012  *
00013  * Contributors:
00014  *    Ian Craggs - initial API and implementation and/or initial documentation
00015  *******************************************************************************/
00016 
00017 #include "MQTTPacket.h"
00018 
00019 #include <string.h>
00020 
00021 /**
00022   * Determines the length of the MQTT subscribe packet that would be produced using the supplied parameters
00023   * @param count the number of topic filter strings in topicFilters
00024   * @param topicFilters the array of topic filter strings to be used in the publish
00025   * @return the length of buffer needed to contain the serialized version of the packet
00026   */
00027 int MQTTSerialize_subscribeLength(int count, MQTTString topicFilters[])
00028 {
00029     int i;
00030     int len = 2; /* packetid */
00031 
00032     for (i = 0; i < count; ++i)
00033         len += 2 + MQTTstrlen(topicFilters[i]) + 1; /* length + topic + req_qos */
00034     return len;
00035 }
00036 
00037 
00038 /**
00039   * Serializes the supplied subscribe data into the supplied buffer, ready for sending
00040   * @param buf the buffer into which the packet will be serialized
00041   * @param buflen the length in bytes of the supplied bufferr
00042   * @param dup integer - the MQTT dup flag
00043   * @param packetid integer - the MQTT packet identifier
00044   * @param count - number of members in the topicFilters and reqQos arrays
00045   * @param topicFilters - array of topic filter names
00046   * @param requestedQoSs - array of requested QoS
00047   * @return the length of the serialized data.  <= 0 indicates error
00048   */
00049 int MQTTSerialize_subscribe(unsigned char* buf, int buflen, unsigned char dup, unsigned short packetid, int count,
00050         MQTTString topicFilters[], int requestedQoSs[])
00051 {
00052     unsigned char *ptr = buf;
00053     MQTTHeader header = {0};
00054     int rem_len = 0;
00055     int rc = 0;
00056     int i = 0;
00057 
00058     if (MQTTPacket_len(rem_len = MQTTSerialize_subscribeLength(count, topicFilters)) > buflen)
00059     {
00060         rc = MQTTPACKET_BUFFER_TOO_SHORT;
00061         goto exit;
00062     }
00063 
00064     header.byte = 0;
00065     header.bits.type = SUBSCRIBE_MSG;
00066     header.bits.dup = dup;
00067     header.bits.qos = 1;
00068     writeChar(&ptr, header.byte); /* write header */
00069 
00070     ptr += MQTTPacket_encode(ptr, rem_len); /* write remaining length */;
00071 
00072     writeInt(&ptr, packetid);
00073 
00074     for (i = 0; i < count; ++i)
00075     {
00076         writeMQTTString(&ptr, topicFilters[i]);
00077         writeChar(&ptr, requestedQoSs[i]);
00078     }
00079 
00080     rc = ptr - buf;
00081 exit:
00082     return rc;
00083 }
00084 
00085 
00086 
00087 /**
00088   * Deserializes the supplied (wire) buffer into suback data
00089   * @param packetid returned integer - the MQTT packet identifier
00090   * @param maxcount - the maximum number of members allowed in the grantedQoSs array
00091   * @param count returned integer - number of members in the grantedQoSs array
00092   * @param grantedQoSs returned array of integers - the granted qualities of service
00093   * @param buf the raw buffer data, of the correct length determined by the remaining length field
00094   * @param buflen the length in bytes of the data in the supplied buffer
00095   * @return error code.  1 is success, 0 is failure
00096   */
00097 int MQTTDeserialize_suback(unsigned short* packetid, int maxcount, int* count, int grantedQoSs[], unsigned char* buf, int buflen)
00098 {
00099     MQTTHeader header = {0};
00100     unsigned char* curdata = buf;
00101     unsigned char* enddata = NULL;
00102     int rc = 0;
00103     int mylen;
00104 
00105     header.byte = readChar(&curdata);
00106     if (header.bits.type != SUBACK_MSG)
00107         goto exit;
00108 
00109     curdata += (rc = MQTTPacket_decodeBuf(curdata, &mylen)); /* read remaining length */
00110     enddata = curdata + mylen;
00111     if (enddata - curdata < 2)
00112         goto exit;
00113 
00114     *packetid = readInt(&curdata);
00115 
00116     *count = 0;
00117     while (curdata < enddata)
00118     {
00119         if (*count > maxcount)
00120         {
00121             rc = -1;
00122             goto exit;
00123         }
00124         grantedQoSs[(*count)++] = readChar(&curdata);
00125     }
00126 
00127     rc = 1;
00128 exit:
00129     return rc;
00130 }
00131 
00132