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@9:3893bc7343f4, 2014-05-09 (annotated)

Committer:
sam_grove
Date:
Fri May 09 23:00:25 2014 +0000
Revision:
9:3893bc7343f4
Parent:
0:7734401cc1b4
Child:
14:c2052aee81de
Added self assignments to hush unused variable 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 */
icraggs 0:7734401cc1b4 50 int MQTTSerialize_subscribe(char* buf, int buflen, int dup, int packetid, int count, MQTTString topicFilters[], int requestedQoSs[])
icraggs 0:7734401cc1b4 51 {
icraggs 0:7734401cc1b4 52 char *ptr = buf;
icraggs 0:7734401cc1b4 53 MQTTHeader header;
icraggs 0:7734401cc1b4 54 int rem_len = 0;
icraggs 0:7734401cc1b4 55 int rc = 0;
icraggs 0:7734401cc1b4 56 int i = 0;
icraggs 0:7734401cc1b4 57
icraggs 0:7734401cc1b4 58 FUNC_ENTRY;
icraggs 0:7734401cc1b4 59 if (MQTTPacket_len(rem_len = MQTTSerialize_subscribeLength(count, topicFilters)) > buflen)
icraggs 0:7734401cc1b4 60 {
icraggs 0:7734401cc1b4 61 rc = MQTTPACKET_BUFFER_TOO_SHORT;
icraggs 0:7734401cc1b4 62 goto exit;
icraggs 0:7734401cc1b4 63 }
icraggs 0:7734401cc1b4 64
icraggs 0:7734401cc1b4 65 header.byte = 0;
icraggs 0:7734401cc1b4 66 header.bits.type = SUBSCRIBE;
icraggs 0:7734401cc1b4 67 header.bits.dup = dup;
icraggs 0:7734401cc1b4 68 header.bits.qos = 1;
icraggs 0:7734401cc1b4 69 writeChar(&ptr, header.byte); /* write header */
icraggs 0:7734401cc1b4 70
icraggs 0:7734401cc1b4 71 ptr += MQTTPacket_encode(ptr, rem_len); /* write remaining length */;
icraggs 0:7734401cc1b4 72
icraggs 0:7734401cc1b4 73 writeInt(&ptr, packetid);
icraggs 0:7734401cc1b4 74
icraggs 0:7734401cc1b4 75 for (i = 0; i < count; ++i)
icraggs 0:7734401cc1b4 76 {
icraggs 0:7734401cc1b4 77 writeMQTTString(&ptr, topicFilters[i]);
icraggs 0:7734401cc1b4 78 writeChar(&ptr, requestedQoSs[i]);
icraggs 0:7734401cc1b4 79 }
icraggs 0:7734401cc1b4 80
icraggs 0:7734401cc1b4 81 rc = ptr - buf;
icraggs 0:7734401cc1b4 82 exit:
icraggs 0:7734401cc1b4 83 FUNC_EXIT_RC(rc);
icraggs 0:7734401cc1b4 84 return rc;
icraggs 0:7734401cc1b4 85 }
icraggs 0:7734401cc1b4 86
icraggs 0:7734401cc1b4 87
icraggs 0:7734401cc1b4 88
icraggs 0:7734401cc1b4 89 /**
icraggs 0:7734401cc1b4 90 * Deserializes the supplied (wire) buffer into suback data
icraggs 0:7734401cc1b4 91 * @param packetid returned integer - the MQTT packet identifier
icraggs 0:7734401cc1b4 92 * @param maxcount - the maximum number of members allowed in the grantedQoSs array
icraggs 0:7734401cc1b4 93 * @param count returned integer - number of members in the grantedQoSs array
icraggs 0:7734401cc1b4 94 * @param grantedQoSs returned array of integers - the granted qualities of service
icraggs 0:7734401cc1b4 95 * @param buf the raw buffer data, of the correct length determined by the remaining length field
icraggs 0:7734401cc1b4 96 * @param buflen the length in bytes of the data in the supplied buffer
icraggs 0:7734401cc1b4 97 * @return error code. 1 is success, 0 is failure
icraggs 0:7734401cc1b4 98 */
icraggs 0:7734401cc1b4 99 int MQTTDeserialize_suback(int* packetid, int maxcount, int* count, int grantedQoSs[], char* buf, int buflen)
icraggs 0:7734401cc1b4 100 {
icraggs 0:7734401cc1b4 101 MQTTHeader header;
icraggs 0:7734401cc1b4 102 char* curdata = buf;
icraggs 0:7734401cc1b4 103 char* enddata = NULL;
icraggs 0:7734401cc1b4 104 int rc = 0;
icraggs 0:7734401cc1b4 105 int mylen;
icraggs 0:7734401cc1b4 106
icraggs 0:7734401cc1b4 107 FUNC_ENTRY;
icraggs 0:7734401cc1b4 108 header.byte = readChar(&curdata);
sam_grove 9:3893bc7343f4 109 header.byte = header.byte; // hush compiler warnings
icraggs 0:7734401cc1b4 110
icraggs 0:7734401cc1b4 111 curdata += (rc = MQTTPacket_decodeBuf(curdata, &mylen)); /* read remaining length */
icraggs 0:7734401cc1b4 112 enddata = curdata + mylen;
icraggs 0:7734401cc1b4 113 if (enddata - curdata < 2)
icraggs 0:7734401cc1b4 114 goto exit;
icraggs 0:7734401cc1b4 115
icraggs 0:7734401cc1b4 116 *packetid = readInt(&curdata);
icraggs 0:7734401cc1b4 117
icraggs 0:7734401cc1b4 118 *count = 0;
icraggs 0:7734401cc1b4 119 while (curdata < enddata)
icraggs 0:7734401cc1b4 120 {
icraggs 0:7734401cc1b4 121 if (*count > maxcount)
icraggs 0:7734401cc1b4 122 {
icraggs 0:7734401cc1b4 123 rc = -1;
icraggs 0:7734401cc1b4 124 goto exit;
icraggs 0:7734401cc1b4 125 }
icraggs 0:7734401cc1b4 126 grantedQoSs[(*count)++] = readChar(&curdata);
icraggs 0:7734401cc1b4 127 }
icraggs 0:7734401cc1b4 128
icraggs 0:7734401cc1b4 129 rc = 1;
icraggs 0:7734401cc1b4 130 exit:
icraggs 0:7734401cc1b4 131 FUNC_EXIT_RC(rc);
icraggs 0:7734401cc1b4 132 return rc;
icraggs 0:7734401cc1b4 133 }
icraggs 0:7734401cc1b4 134
icraggs 0:7734401cc1b4 135