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 #include "StackTrace.h"
00019 
00020 #include <string.h>
00021 
00022 /**
00023   * Determines the length of the MQTT subscribe packet that would be produced using the supplied parameters
00024   * @param count the number of topic filter strings in topicFilters
00025   * @param topicFilters the array of topic filter strings to be used in the publish
00026   * @return the length of buffer needed to contain the serialized version of the packet
00027   */
00028 int MQTTSerialize_subscribeLength(int count, MQTTString topicFilters[])
00029 {
00030     int i;
00031     int len = 2; /* packetid */
00032 
00033     for (i = 0; i < count; ++i)
00034         len += 2 + MQTTstrlen(topicFilters[i]) + 1; /* length + topic + req_qos */
00035     return len;
00036 }
00037 
00038 
00039 /**
00040   * Serializes the supplied subscribe data into the supplied buffer, ready for sending
00041   * @param buf the buffer into which the packet will be serialized
00042   * @param buflen the length in bytes of the supplied bufferr
00043   * @param dup integer - the MQTT dup flag
00044   * @param packetid integer - the MQTT packet identifier
00045   * @param count - number of members in the topicFilters and reqQos arrays
00046   * @param topicFilters - array of topic filter names
00047   * @param requestedQoSs - array of requested QoS
00048   * @return the length of the serialized data.  <= 0 indicates error
00049   */
00050 int MQTTSerialize_subscribe(unsigned char* buf, int buflen, unsigned char dup, unsigned short packetid, int count,
00051         MQTTString topicFilters[], int requestedQoSs[])
00052 {
00053     unsigned char *ptr = buf;
00054     MQTTHeader header = {0};
00055     int rem_len = 0;
00056     int rc = 0;
00057     int i = 0;
00058 
00059     FUNC_ENTRY;
00060     if (MQTTPacket_len(rem_len = MQTTSerialize_subscribeLength(count, topicFilters)) > buflen)
00061     {
00062         rc = MQTTPACKET_BUFFER_TOO_SHORT;
00063         goto exit;
00064     }
00065 
00066     header.byte = 0;
00067     header.bits.type = SUBSCRIBE;
00068     header.bits.dup = dup;
00069     header.bits.qos = 1;
00070     writeChar(&ptr, header.byte); /* write header */
00071 
00072     ptr += MQTTPacket_encode(ptr, rem_len); /* write remaining length */;
00073 
00074     writeInt(&ptr, packetid);
00075 
00076     for (i = 0; i < count; ++i)
00077     {
00078         writeMQTTString(&ptr, topicFilters[i]);
00079         writeChar(&ptr, requestedQoSs[i]);
00080     }
00081 
00082     rc = ptr - buf;
00083 exit:
00084     FUNC_EXIT_RC(rc);
00085     return rc;
00086 }
00087 
00088 
00089 
00090 /**
00091   * Deserializes the supplied (wire) buffer into suback data
00092   * @param packetid returned integer - the MQTT packet identifier
00093   * @param maxcount - the maximum number of members allowed in the grantedQoSs array
00094   * @param count returned integer - number of members in the grantedQoSs array
00095   * @param grantedQoSs returned array of integers - the granted qualities of service
00096   * @param buf the raw buffer data, of the correct length determined by the remaining length field
00097   * @param buflen the length in bytes of the data in the supplied buffer
00098   * @return error code.  1 is success, 0 is failure
00099   */
00100 int MQTTDeserialize_suback(unsigned short* packetid, int maxcount, int* count, int grantedQoSs[], unsigned char* buf, int buflen)
00101 {
00102     MQTTHeader header = {0};
00103     unsigned char* curdata = buf;
00104     unsigned char* enddata = NULL;
00105     int rc = 0;
00106     int mylen;
00107 
00108     FUNC_ENTRY;
00109     header.byte = readChar(&curdata);
00110     if (header.bits.type != SUBACK)
00111         goto exit;
00112 
00113     curdata += (rc = MQTTPacket_decodeBuf(curdata, &mylen)); /* read remaining length */
00114     enddata = curdata + mylen;
00115     if (enddata - curdata < 2)
00116         goto exit;
00117 
00118     *packetid = readInt(&curdata);
00119 
00120     *count = 0;
00121     while (curdata < enddata)
00122     {
00123         if (*count > maxcount)
00124         {
00125             rc = -1;
00126             goto exit;
00127         }
00128         grantedQoSs[(*count)++] = readChar(&curdata);
00129     }
00130 
00131     rc = 1;
00132 exit:
00133     FUNC_EXIT_RC(rc);
00134     return rc;
00135 }
00136 
00137