MQTT / MQTTPacket

Basic C library for MQTT packet serialization and deserialization

Dependents:   MQTT MQTT MQTT MQTT ... more

Fork of MQTTPacket by MQTT

This library is part of the EclipseTM Paho project; specifically the embedded client.

A basic MQTT library in C for packet serialization and deserialization

MQTTSubscribeClient.c@17:c5bd28cc139a, 2014-08-01 (annotated)

Committer:
icraggs
Date:
Fri Aug 01 17:25:52 2014 +0000
Revision:
17:c5bd28cc139a
Parent:
16:d0b3886ada32 
Initializations to remove compiler warnings

Who changed what in which revision?

UserRevisionLine numberNew contents of line
icraggs 0:7734401cc1b4 1 /*******************************************************************************
icraggs 0:7734401cc1b4 2 * Copyright (c) 2014 IBM Corp.
icraggs 0:7734401cc1b4 3 *
icraggs 0:7734401cc1b4 4 * All rights reserved. This program and the accompanying materials
icraggs 0:7734401cc1b4 5 * are made available under the terms of the Eclipse Public License v1.0
icraggs 0:7734401cc1b4 6 * and Eclipse Distribution License v1.0 which accompany this distribution.
icraggs 0:7734401cc1b4 7 *
icraggs 0:7734401cc1b4 8 * The Eclipse Public License is available at
icraggs 0:7734401cc1b4 9 * http://www.eclipse.org/legal/epl-v10.html
icraggs 0:7734401cc1b4 10 * and the Eclipse Distribution License is available at
icraggs 0:7734401cc1b4 11 * http://www.eclipse.org/org/documents/edl-v10.php.
icraggs 0:7734401cc1b4 12 *
icraggs 0:7734401cc1b4 13 * Contributors:
icraggs 0:7734401cc1b4 14 * Ian Craggs - initial API and implementation and/or initial documentation
icraggs 0:7734401cc1b4 15 *******************************************************************************/
icraggs 0:7734401cc1b4 16
icraggs 0:7734401cc1b4 17 #include "MQTTPacket.h"
icraggs 0:7734401cc1b4 18 #include "StackTrace.h"
icraggs 0:7734401cc1b4 19
icraggs 0:7734401cc1b4 20 #include <string.h>
icraggs 0:7734401cc1b4 21
icraggs 0:7734401cc1b4 22 /**
icraggs 0:7734401cc1b4 23 * Determines the length of the MQTT subscribe packet that would be produced using the supplied parameters
icraggs 0:7734401cc1b4 24 * @param count the number of topic filter strings in topicFilters
icraggs 0:7734401cc1b4 25 * @param topicFilters the array of topic filter strings to be used in the publish
icraggs 0:7734401cc1b4 26 * @return the length of buffer needed to contain the serialized version of the packet
icraggs 0:7734401cc1b4 27 */
icraggs 0:7734401cc1b4 28 int MQTTSerialize_subscribeLength(int count, MQTTString topicFilters[])
icraggs 0:7734401cc1b4 29 {
icraggs 0:7734401cc1b4 30 int i;
icraggs 0:7734401cc1b4 31 int len = 2; /* packetid */
icraggs 0:7734401cc1b4 32
icraggs 0:7734401cc1b4 33 for (i = 0; i < count; ++i)
icraggs 0:7734401cc1b4 34 len += 2 + MQTTstrlen(topicFilters[i]) + 1; /* length + topic + req_qos */
icraggs 0:7734401cc1b4 35 return len;
icraggs 0:7734401cc1b4 36 }
icraggs 0:7734401cc1b4 37
icraggs 0:7734401cc1b4 38
icraggs 0:7734401cc1b4 39 /**
icraggs 0:7734401cc1b4 40 * Serializes the supplied subscribe data into the supplied buffer, ready for sending
icraggs 0:7734401cc1b4 41 * @param buf the buffer into which the packet will be serialized
icraggs 0:7734401cc1b4 42 * @param buflen the length in bytes of the supplied bufferr
icraggs 0:7734401cc1b4 43 * @param dup integer - the MQTT dup flag
icraggs 0:7734401cc1b4 44 * @param packetid integer - the MQTT packet identifier
icraggs 0:7734401cc1b4 45 * @param count - number of members in the topicFilters and reqQos arrays
icraggs 0:7734401cc1b4 46 * @param topicFilters - array of topic filter names
icraggs 0:7734401cc1b4 47 * @param requestedQoSs - array of requested QoS
icraggs 0:7734401cc1b4 48 * @return the length of the serialized data. <= 0 indicates error
icraggs 0:7734401cc1b4 49 */
Ian Craggs 14:c2052aee81de 50 int MQTTSerialize_subscribe(unsigned char* buf, int buflen, unsigned char dup, unsigned short packetid, int count,
Ian Craggs 14:c2052aee81de 51 MQTTString topicFilters[], int requestedQoSs[])
icraggs 0:7734401cc1b4 52 {
Ian Craggs 14:c2052aee81de 53 unsigned char *ptr = buf;
icraggs 17:c5bd28cc139a 54 MQTTHeader header = {0};
icraggs 0:7734401cc1b4 55 int rem_len = 0;
icraggs 0:7734401cc1b4 56 int rc = 0;
icraggs 0:7734401cc1b4 57 int i = 0;
icraggs 0:7734401cc1b4 58
icraggs 0:7734401cc1b4 59 FUNC_ENTRY;
icraggs 0:7734401cc1b4 60 if (MQTTPacket_len(rem_len = MQTTSerialize_subscribeLength(count, topicFilters)) > buflen)
icraggs 0:7734401cc1b4 61 {
icraggs 0:7734401cc1b4 62 rc = MQTTPACKET_BUFFER_TOO_SHORT;
icraggs 0:7734401cc1b4 63 goto exit;
icraggs 0:7734401cc1b4 64 }
icraggs 0:7734401cc1b4 65
icraggs 0:7734401cc1b4 66 header.byte = 0;
icraggs 0:7734401cc1b4 67 header.bits.type = SUBSCRIBE;
icraggs 0:7734401cc1b4 68 header.bits.dup = dup;
icraggs 0:7734401cc1b4 69 header.bits.qos = 1;
icraggs 0:7734401cc1b4 70 writeChar(&ptr, header.byte); /* write header */
icraggs 0:7734401cc1b4 71
icraggs 0:7734401cc1b4 72 ptr += MQTTPacket_encode(ptr, rem_len); /* write remaining length */;
icraggs 0:7734401cc1b4 73
icraggs 0:7734401cc1b4 74 writeInt(&ptr, packetid);
icraggs 0:7734401cc1b4 75
icraggs 0:7734401cc1b4 76 for (i = 0; i < count; ++i)
icraggs 0:7734401cc1b4 77 {
icraggs 0:7734401cc1b4 78 writeMQTTString(&ptr, topicFilters[i]);
icraggs 0:7734401cc1b4 79 writeChar(&ptr, requestedQoSs[i]);
icraggs 0:7734401cc1b4 80 }
icraggs 0:7734401cc1b4 81
icraggs 0:7734401cc1b4 82 rc = ptr - buf;
icraggs 0:7734401cc1b4 83 exit:
icraggs 0:7734401cc1b4 84 FUNC_EXIT_RC(rc);
icraggs 0:7734401cc1b4 85 return rc;
icraggs 0:7734401cc1b4 86 }
icraggs 0:7734401cc1b4 87
icraggs 0:7734401cc1b4 88
icraggs 0:7734401cc1b4 89
icraggs 0:7734401cc1b4 90 /**
icraggs 0:7734401cc1b4 91 * Deserializes the supplied (wire) buffer into suback data
icraggs 0:7734401cc1b4 92 * @param packetid returned integer - the MQTT packet identifier
icraggs 0:7734401cc1b4 93 * @param maxcount - the maximum number of members allowed in the grantedQoSs array
icraggs 0:7734401cc1b4 94 * @param count returned integer - number of members in the grantedQoSs array
icraggs 0:7734401cc1b4 95 * @param grantedQoSs returned array of integers - the granted qualities of service
icraggs 0:7734401cc1b4 96 * @param buf the raw buffer data, of the correct length determined by the remaining length field
icraggs 0:7734401cc1b4 97 * @param buflen the length in bytes of the data in the supplied buffer
icraggs 0:7734401cc1b4 98 * @return error code. 1 is success, 0 is failure
icraggs 0:7734401cc1b4 99 */
Ian Craggs 14:c2052aee81de 100 int MQTTDeserialize_suback(unsigned short* packetid, int maxcount, int* count, int grantedQoSs[], unsigned char* buf, int buflen)
icraggs 0:7734401cc1b4 101 {
icraggs 17:c5bd28cc139a 102 MQTTHeader header = {0};
Ian Craggs 14:c2052aee81de 103 unsigned char* curdata = buf;
Ian Craggs 14:c2052aee81de 104 unsigned char* enddata = NULL;
icraggs 0:7734401cc1b4 105 int rc = 0;
icraggs 0:7734401cc1b4 106 int mylen;
icraggs 0:7734401cc1b4 107
icraggs 0:7734401cc1b4 108 FUNC_ENTRY;
icraggs 0:7734401cc1b4 109 header.byte = readChar(&curdata);
icraggs 16:d0b3886ada32 110 if (header.bits.type != SUBACK)
icraggs 16:d0b3886ada32 111 goto exit;
icraggs 0:7734401cc1b4 112
icraggs 0:7734401cc1b4 113 curdata += (rc = MQTTPacket_decodeBuf(curdata, &mylen)); /* read remaining length */
icraggs 0:7734401cc1b4 114 enddata = curdata + mylen;
icraggs 0:7734401cc1b4 115 if (enddata - curdata < 2)
icraggs 0:7734401cc1b4 116 goto exit;
icraggs 0:7734401cc1b4 117
icraggs 0:7734401cc1b4 118 *packetid = readInt(&curdata);
icraggs 0:7734401cc1b4 119
icraggs 0:7734401cc1b4 120 *count = 0;
icraggs 0:7734401cc1b4 121 while (curdata < enddata)
icraggs 0:7734401cc1b4 122 {
icraggs 0:7734401cc1b4 123 if (*count > maxcount)
icraggs 0:7734401cc1b4 124 {
icraggs 0:7734401cc1b4 125 rc = -1;
icraggs 0:7734401cc1b4 126 goto exit;
icraggs 0:7734401cc1b4 127 }
icraggs 0:7734401cc1b4 128 grantedQoSs[(*count)++] = readChar(&curdata);
icraggs 0:7734401cc1b4 129 }
icraggs 0:7734401cc1b4 130
icraggs 0:7734401cc1b4 131 rc = 1;
icraggs 0:7734401cc1b4 132 exit:
icraggs 0:7734401cc1b4 133 FUNC_EXIT_RC(rc);
icraggs 0:7734401cc1b4 134 return rc;
icraggs 0:7734401cc1b4 135 }
icraggs 0:7734401cc1b4 136
icraggs 0:7734401cc1b4 137