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

samples/publish-subscribe.txt

Committer:
Ian Craggs
Date:
2017-10-30
Revision:
25:aedcaf7984d5
Parent:
2:bc3bc0e3b764

File content as of revision 25:aedcaf7984d5:

#include "MQTTPacket.h"

#include <errno.h>
#include <stdlib.h>
#include <string.h>

#include "EthernetInterface.h"


TCPSocketConnection mysock; 

int getdata(char* buf, int count)
{
    return mysock.receive(buf, (size_t)count);
}

int toStop = 0;


int main()
{
    MQTTPacket_connectData data = MQTTPacket_connectData_initializer;
    int rc = 0;
    char buf[200];
    int buflen = sizeof(buf);
    int msgid = 1;
    MQTTString topicString = MQTTString_initializer;
    int req_qos = 0;
    char* payload = "mypayload";
    int payloadlen = strlen(payload);
    int len = 0;
    EthernetInterface eth;
    
    eth.init(); //Use DHCP
    eth.connect();

    rc = mysock.connect("m2m.eclipse.org", 1883);

    data.clientID.cstring = "SendReceive mbed MQTT ";
    data.keepAliveInterval = 20;
    data.cleansession = 1;

    mysock.set_blocking(true, 1000);  /* 1 second Timeout */

    len = MQTTSerialize_connect(buf, buflen, &data);
    rc = mysock.send(buf, len);

    /* wait for connack */
    if (MQTTPacket_read(buf, buflen, getdata) == CONNACK)
    {
        int connack_rc;

        if (MQTTDeserialize_connack(&connack_rc, buf, buflen) != 1 || connack_rc != 0)
        {
            printf("Unable to connect, return code %d\n", connack_rc);
            goto exit;
        }
    }
    else
        goto exit;

    /* subscribe */
    topicString.cstring = "substopic";
    len = MQTTSerialize_subscribe(buf, buflen, 0, msgid, 1, &topicString, &req_qos);

    rc = mysock.send(buf, len);
    if (MQTTPacket_read(buf, buflen, getdata) == SUBACK)    /* wait for suback */
    {
        int submsgid;
        int subcount;
        int granted_qos;

        rc = MQTTDeserialize_suback(&submsgid, 1, &subcount, &granted_qos, buf, buflen);
        if (granted_qos != 0)
        {
            printf("granted qos != 0, %d\n", granted_qos);
            goto exit;
        }
    }
    else
        goto exit;

    topicString.cstring = "pubtopic";
    while (!toStop)
    {
        if (MQTTPacket_read(buf, buflen, getdata) == PUBLISH)
        {
            int dup;
            int qos;
            int retained;
            int msgid;
            int payloadlen_in;
            char* payload_in;
            int rc;
            MQTTString receivedTopic;

            rc = MQTTDeserialize_publish(&dup, &qos, &retained, &msgid, &receivedTopic,
                    &payload_in, &payloadlen_in, buf, buflen);
            printf("message arrived %.*s\n", payloadlen_in, payload_in);
        }

        printf("publishing reading\n");
        len = MQTTSerialize_publish(buf, buflen, 0, 0, 0, 0, topicString, payload, payloadlen);
        rc = mysock.send(buf, len);
    }

    printf("disconnecting\n");
    len = MQTTSerialize_disconnect(buf, buflen);
    rc = mysock.send(buf, len);

exit:    
    eth.disconnect();

    return 0;
}