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

MQTTFormat.c

Committer:
Ian Craggs
Date:
2017-10-30
Revision:
25:aedcaf7984d5
Parent:
23:7a52009beba1

File content as of revision 25:aedcaf7984d5:

/*******************************************************************************
 * 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 "StackTrace.h"
#include "MQTTPacket.h"

#include <string.h>


const char* MQTTPacket_names[] =
{
    "RESERVED", "CONNECT", "CONNACK", "PUBLISH", "PUBACK", "PUBREC", "PUBREL",
    "PUBCOMP", "SUBSCRIBE", "SUBACK", "UNSUBSCRIBE", "UNSUBACK",
    "PINGREQ", "PINGRESP", "DISCONNECT"
};


const char* MQTTPacket_getName(unsigned short packetid)
{
    return MQTTPacket_names[packetid];
}


int MQTTStringFormat_connect(char* strbuf, int strbuflen, MQTTPacket_connectData* data)
{
    int strindex = 0;

    strindex = snprintf(strbuf, strbuflen,
            "CONNECT MQTT version %d, client id %.*s, clean session %d, keep alive %d",
            (int)data->MQTTVersion, data->clientID.lenstring.len, data->clientID.lenstring.data,
            (int)data->cleansession, data->keepAliveInterval);
    if (data->willFlag)
        strindex += snprintf(&strbuf[strindex], strbuflen - strindex,
                ", will QoS %d, will retain %d, will topic %.*s, will message %.*s",
                data->will.qos, data->will.retained,
                data->will.topicName.lenstring.len, data->will.topicName.lenstring.data,
                data->will.message.lenstring.len, data->will.message.lenstring.data);
    if (data->username.lenstring.data && data->username.lenstring.len > 0)
        strindex += snprintf(&strbuf[strindex], strbuflen - strindex,
                ", user name %.*s", data->username.lenstring.len, data->username.lenstring.data);
    if (data->password.lenstring.data && data->password.lenstring.len > 0)
        strindex += snprintf(&strbuf[strindex], strbuflen - strindex,
                ", password %.*s", data->password.lenstring.len, data->password.lenstring.data);
    return strindex;
}


int MQTTStringFormat_connack(char* strbuf, int strbuflen, unsigned char connack_rc, unsigned char sessionPresent)
{
    int strindex = snprintf(strbuf, strbuflen, "CONNACK session present %d, rc %d", sessionPresent, connack_rc);
    return strindex;
}


int MQTTStringFormat_publish(char* strbuf, int strbuflen, unsigned char dup, int qos, unsigned char retained,
        unsigned short packetid, MQTTString topicName, unsigned char* payload, int payloadlen)
{
    int strindex = snprintf(strbuf, strbuflen,
                "PUBLISH dup %d, QoS %d, retained %d, packet id %d, topic %.*s, payload length %d, payload %.*s",
                dup, qos, retained, packetid,
                (topicName.lenstring.len < 20) ? topicName.lenstring.len : 20, topicName.lenstring.data,
                payloadlen, (payloadlen < 20) ? payloadlen : 20, payload);
    return strindex;
}


int MQTTStringFormat_ack(char* strbuf, int strbuflen, unsigned char packettype, unsigned char dup, unsigned short packetid)
{
    int strindex = snprintf(strbuf, strbuflen, "%s, packet id %d", MQTTPacket_names[packettype], packetid);
    if (dup)
        strindex += snprintf(strbuf + strindex, strbuflen - strindex, ", dup %d", dup);
    return strindex;
}


int MQTTStringFormat_subscribe(char* strbuf, int strbuflen, unsigned char dup, unsigned short packetid, int count,
        MQTTString topicFilters[], int requestedQoSs[])
{
    return snprintf(strbuf, strbuflen,
        "SUBSCRIBE dup %d, packet id %d count %d topic %.*s qos %d",
        dup, packetid, count,
        topicFilters[0].lenstring.len, topicFilters[0].lenstring.data,
        requestedQoSs[0]);
}


int MQTTStringFormat_suback(char* strbuf, int strbuflen, unsigned short packetid, int count, int* grantedQoSs)
{
    return snprintf(strbuf, strbuflen,
        "SUBACK packet id %d count %d granted qos %d", packetid, count, grantedQoSs[0]);
}


int MQTTStringFormat_unsubscribe(char* strbuf, int strbuflen, unsigned char dup, unsigned short packetid,
        int count, MQTTString topicFilters[])
{
    return snprintf(strbuf, strbuflen,
                    "UNSUBSCRIBE dup %d, packet id %d count %d topic %.*s",
                    dup, packetid, count,
                    topicFilters[0].lenstring.len, topicFilters[0].lenstring.data);
}


#if defined(MQTT_CLIENT)
char* MQTTFormat_toClientString(char* strbuf, int strbuflen, unsigned char* buf, int buflen)
{
    int index = 0;
    int rem_length = 0;
    MQTTHeader header = {0};
    int strindex = 0;

    header.byte = buf[index++];
    index += MQTTPacket_decodeBuf(&buf[index], &rem_length);

    switch (header.bits.type)
    {

    case CONNACK:
    {
        unsigned char sessionPresent, connack_rc;
        if (MQTTDeserialize_connack(&sessionPresent, &connack_rc, buf, buflen) == 1)
            strindex = MQTTStringFormat_connack(strbuf, strbuflen, connack_rc, sessionPresent);
    }
    break;
    case PUBLISH:
    {
        unsigned char dup, retained, *payload;
        unsigned short packetid;
        int qos, payloadlen;
        MQTTString topicName = MQTTString_initializer;
        if (MQTTDeserialize_publish(&dup, &qos, &retained, &packetid, &topicName,
                &payload, &payloadlen, buf, buflen) == 1)
            strindex = MQTTStringFormat_publish(strbuf, strbuflen, dup, qos, retained, packetid,
                    topicName, payload, payloadlen);
    }
    break;
    case PUBACK:
    case PUBREC:
    case PUBREL:
    case PUBCOMP:
    {
        unsigned char packettype, dup;
        unsigned short packetid;
        if (MQTTDeserialize_ack(&packettype, &dup, &packetid, buf, buflen) == 1)
            strindex = MQTTStringFormat_ack(strbuf, strbuflen, packettype, dup, packetid);
    }
    break;
    case SUBACK:
    {
        unsigned short packetid;
        int maxcount = 1, count = 0;
        int grantedQoSs[1];
        if (MQTTDeserialize_suback(&packetid, maxcount, &count, grantedQoSs, buf, buflen) == 1)
            strindex = MQTTStringFormat_suback(strbuf, strbuflen, packetid, count, grantedQoSs);
    }
    break;
    case UNSUBACK:
    {
        unsigned short packetid;
        if (MQTTDeserialize_unsuback(&packetid, buf, buflen) == 1)
            strindex = MQTTStringFormat_ack(strbuf, strbuflen, UNSUBACK, 0, packetid);
    }
    break;
    case PINGREQ:
    case PINGRESP:
    case DISCONNECT:
        strindex = snprintf(strbuf, strbuflen, "%s", MQTTPacket_names[header.bits.type]);
        break;
    }
    return strbuf;
}
#endif

#if defined(MQTT_SERVER)
char* MQTTFormat_toServerString(char* strbuf, int strbuflen, unsigned char* buf, int buflen)
{
    int index = 0;
    int rem_length = 0;
    MQTTHeader header = {0};
    int strindex = 0;

    header.byte = buf[index++];
    index += MQTTPacket_decodeBuf(&buf[index], &rem_length);

    switch (header.bits.type)
    {
    case CONNECT:
    {
        MQTTPacket_connectData data;
        int rc;
        if ((rc = MQTTDeserialize_connect(&data, buf, buflen)) == 1)
            strindex = MQTTStringFormat_connect(strbuf, strbuflen, &data);
    }
    break;
    case PUBLISH:
    {
        unsigned char dup, retained, *payload;
        unsigned short packetid;
        int qos, payloadlen;
        MQTTString topicName = MQTTString_initializer;
        if (MQTTDeserialize_publish(&dup, &qos, &retained, &packetid, &topicName,
                &payload, &payloadlen, buf, buflen) == 1)
            strindex = MQTTStringFormat_publish(strbuf, strbuflen, dup, qos, retained, packetid,
                    topicName, payload, payloadlen);
    }
    break;
    case PUBACK:
    case PUBREC:
    case PUBREL:
    case PUBCOMP:
    {
        unsigned char packettype, dup;
        unsigned short packetid;
        if (MQTTDeserialize_ack(&packettype, &dup, &packetid, buf, buflen) == 1)
            strindex = MQTTStringFormat_ack(strbuf, strbuflen, packettype, dup, packetid);
    }
    break;
    case SUBSCRIBE:
    {
        unsigned char dup;
        unsigned short packetid;
        int maxcount = 1, count = 0;
        MQTTString topicFilters[1];
        int requestedQoSs[1];
        if (MQTTDeserialize_subscribe(&dup, &packetid, maxcount, &count,
                topicFilters, requestedQoSs, buf, buflen) == 1)
            strindex = MQTTStringFormat_subscribe(strbuf, strbuflen, dup, packetid, count, topicFilters, requestedQoSs);;
    }
    break;
    case UNSUBSCRIBE:
    {
        unsigned char dup;
        unsigned short packetid;
        int maxcount = 1, count = 0;
        MQTTString topicFilters[1];
        if (MQTTDeserialize_unsubscribe(&dup, &packetid, maxcount, &count, topicFilters, buf, buflen) == 1)
            strindex =  MQTTStringFormat_unsubscribe(strbuf, strbuflen, dup, packetid, count, topicFilters);
    }
    break;
    case PINGREQ:
    case PINGRESP:
    case DISCONNECT:
        strindex = snprintf(strbuf, strbuflen, "%s", MQTTPacket_names[header.bits.type]);
        break;
    }
    strbuf[strbuflen] = '\0';
    return strbuf;
}
#endif