pikascript/package/mqtt/MQTTSubscribeClient.c

/*******************************************************************************
 * Copyright (c) 2014 IBM Corp.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * and Eclipse Distribution License v1.0 which accompany this distribution.
 *
 * The Eclipse Public License is available at
 *    http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 *   http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *    Ian Craggs - initial API and implementation and/or initial
 *documentation
 *******************************************************************************/
#include "MQTTPacket.h"
#include "StackTrace.h"

#include <string.h>

/**
 * Determines the length of the MQTT subscribe packet that would be produced
 * using the supplied parameters
 * @param count the number of topic filter strings in topicFilters
 * @param topicFilters the array of topic filter strings to be used in the
 * publish
 * @return the length of buffer needed to contain the serialized version of
 * the packet
 */
int MQTTSerialize_subscribeLength(int count, MQTTString topicFilters[]) {
    int i;
    int len = 2; /* packetid */

    for (i = 0; i < count; ++i)
        len +=
            2 + MQTTstrlen(topicFilters[i]) + 1; /* length + topic + req_qos */
    return len;
}

/**
 * Serializes the supplied subscribe data into the supplied buffer, ready for
 * sending
 * @param buf the buffer into which the packet will be serialized
 * @param buflen the length in bytes of the supplied bufferr
 * @param dup integer - the MQTT dup flag
 * @param packetid integer - the MQTT packet identifier
 * @param count - number of members in the topicFilters and reqQos arrays
 * @param topicFilters - array of topic filter names
 * @param requestedQoSs - array of requested QoS
 * @return the length of the serialized data.  <= 0 indicates error
 */
int MQTTSerialize_subscribe(unsigned char* buf,
                            int buflen,
                            unsigned char dup,
                            unsigned short packetid,
                            int count,
                            MQTTString topicFilters[],
                            int requestedQoSs[]) {
    unsigned char* ptr = buf;
    MQTTHeader header = {0};
    int rem_len = 0;
    int rc = 0;
    int i = 0;

    FUNC_ENTRY;
    if (MQTTPacket_len(rem_len = MQTTSerialize_subscribeLength(
                           count, topicFilters)) > buflen) {
        rc = MQTTPACKET_BUFFER_TOO_SHORT;
        goto exit;
    }

    header.byte = 0;
    header.bits.type = SUBSCRIBE;
    header.bits.dup = dup;
    header.bits.qos = 1;
    writeChar(&ptr, header.byte); /* write header */

    ptr += MQTTPacket_encode(ptr, rem_len); /* write remaining length */
    ;

    writeInt(&ptr, packetid);

    for (i = 0; i < count; ++i) {
        writeMQTTString(&ptr, topicFilters[i]);
        writeChar(&ptr, requestedQoSs[i]);
    }

    rc = ptr - buf;
exit:
    FUNC_EXIT_RC(rc);
    return rc;
}

/**
 * Deserializes the supplied (wire) buffer into suback data
 * @param packetid returned integer - the MQTT packet identifier
 * @param maxcount - the maximum number of members allowed in the grantedQoSs
 * array
 * @param count returned integer - number of members in the grantedQoSs array
 * @param grantedQoSs returned array of integers - the granted qualities of
 * service
 * @param buf the raw buffer data, of the correct length determined by the
 * remaining length field
 * @param buflen the length in bytes of the data in the supplied buffer
 * @return error code.  1 is success, 0 is failure
 */
int MQTTDeserialize_suback(unsigned short* packetid,
                           int maxcount,
                           int* count,
                           int grantedQoSs[],
                           unsigned char* buf,
                           int buflen) {
    MQTTHeader header = {0};
    unsigned char* curdata = buf;
    unsigned char* enddata = NULL;
    int rc = 0;
    int mylen;

    FUNC_ENTRY;
    header.byte = readChar(&curdata);
    if (header.bits.type != SUBACK)
        goto exit;

    curdata += (rc = MQTTPacket_decodeBuf(curdata,
                                          &mylen)); /* read remaining length */
    enddata = curdata + mylen;
    if (enddata - curdata < 2)
        goto exit;

    *packetid = readInt(&curdata);

    *count = 0;
    while (curdata < enddata) {
        if (*count > maxcount) {
            rc = -1;
            goto exit;
        }
        grantedQoSs[(*count)++] = readChar(&curdata);
    }

    rc = 1;
exit:
    FUNC_EXIT_RC(rc);
    return rc;
}