MQTTSNSubscribeClient.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 "MQTTSNPacket.h"
00018 #include "StackTrace.h"
00019 
00020 #include <string.h>
00021 
00022 /**
00023   * Determines the length of the MQTTSN subscribe packet that would be produced using the supplied parameters, 
00024   * excluding length
00025   * @param topicName the topic name to be used in the publish  
00026   * @return the length of buffer needed to contain the serialized version of the packet
00027   */
00028 int MQTTSNSerialize_subscribeLength(MQTTSN_topicid* topicFilter)
00029 {
00030     int len = 4;
00031 
00032     if (topicFilter->type == MQTTSN_TOPIC_TYPE_NORMAL)
00033         len += topicFilter->data.long_.len;
00034     else if (topicFilter->type == MQTTSN_TOPIC_TYPE_SHORT || topicFilter->type == MQTTSN_TOPIC_TYPE_PREDEFINED)
00035         len += 2;
00036 
00037     return len;
00038 }
00039 
00040 
00041 /**
00042   * Serializes the supplied subscribe data into the supplied buffer, ready for sending
00043   * @param buf the buffer into which the packet will be serialized
00044   * @param buflen the length in bytes of the supplied buffer
00045   * @param dup integer - the MQTT-SN dup flag
00046   * @param qos integer - the MQTT-SN QoS value
00047   * @param packetid integer - the MQTT-SN packet identifier
00048   * @param topic MQTTSN_topicid - the MQTT-SN topic in the subscribe
00049   * @return the length of the serialized data.  <= 0 indicates error
00050   */
00051 int MQTTSNSerialize_subscribe(unsigned char* buf, int buflen, unsigned char dup, int qos, unsigned short packetid,
00052         MQTTSN_topicid* topicFilter)
00053 {
00054     unsigned char *ptr = buf;
00055     MQTTSNFlags flags;
00056     int len = 0;
00057     int rc = 0;
00058 
00059     FUNC_ENTRY;
00060     if ((len = MQTTSNPacket_len(MQTTSNSerialize_subscribeLength(topicFilter))) > buflen)
00061     {
00062         rc = MQTTSNPACKET_BUFFER_TOO_SHORT;
00063         goto exit;
00064     }
00065     ptr += MQTTSNPacket_encode(ptr, len);   /* write length */
00066     writeChar(&ptr, MQTTSN_SUBSCRIBE);      /* write message type */
00067 
00068     flags.all = 0;
00069     flags.bits.dup = dup;
00070     flags.bits.QoS = qos;
00071     flags.bits.topicIdType = topicFilter->type;
00072     writeChar(&ptr, flags.all);
00073 
00074     writeInt(&ptr, packetid);
00075 
00076     /* now the topic id or name */
00077     if (topicFilter->type == MQTTSN_TOPIC_TYPE_NORMAL) /* means long topic name */
00078     {
00079         memcpy(ptr, topicFilter->data.long_.name, topicFilter->data.long_.len);
00080         ptr += topicFilter->data.long_.len;
00081     }
00082     else if (topicFilter->type == MQTTSN_TOPIC_TYPE_PREDEFINED)
00083         writeInt(&ptr, topicFilter->data.id);
00084     else if (topicFilter->type == MQTTSN_TOPIC_TYPE_SHORT)
00085     {
00086         writeChar(&ptr, topicFilter->data.short_name[0]);
00087         writeChar(&ptr, topicFilter->data.short_name[1]);
00088     }
00089 
00090     rc = ptr - buf;
00091 exit:
00092     FUNC_EXIT_RC(rc);
00093     return rc;
00094 
00095 }
00096 
00097 
00098 /**
00099   * Deserializes the supplied (wire) buffer into suback data
00100   * @param qos the returned qos
00101   * @param topicid returned if "accepted" the value which will be used by the gateway in subsequent PUBLISH packets
00102   * @param packetid returned - the same value as the one contained in the corresponding SUBSCRIBE
00103   * @param returncode returned - "accepted" or rejection reason
00104   * @param buf the raw buffer data, of the correct length determined by the remaining length field
00105   * @param buflen the length in bytes of the data in the supplied buffer
00106   * @return error code.  1 is success
00107   */
00108 int MQTTSNDeserialize_suback(int* qos, unsigned short* topicid, unsigned short* packetid,
00109         unsigned char* returncode, unsigned char* buf, int buflen)
00110 {
00111     MQTTSNFlags flags;
00112     unsigned char* curdata = buf;
00113     unsigned char* enddata = NULL;
00114     int rc = 0;
00115     int mylen = 0;
00116 
00117     FUNC_ENTRY;
00118     curdata += MQTTSNPacket_decode(curdata, buflen, &mylen); /* read length */
00119     enddata = buf + mylen;
00120     if (enddata - curdata > buflen)
00121         goto exit;
00122 
00123     if (readChar(&curdata) != MQTTSN_SUBACK)
00124         goto exit;
00125 
00126     flags.all = readChar(&curdata);
00127     *qos = flags.bits.QoS;
00128 
00129     *topicid = readInt(&curdata);
00130     *packetid = readInt(&curdata);
00131     *returncode = readChar(&curdata);
00132 
00133     rc = 1;
00134 exit:
00135     FUNC_EXIT_RC(rc);
00136     return rc;
00137 }
00138 
00139 
00140