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where can I find the sample codes to publish/subscribe using SSL/TLS(mosquitto) in C language for omega2?

  • I want to make the code that publish/subscribe using SSL/TLS(mosquitto).
    anyone know that, please let me know.

  • @jongrock-chun Here is some code you can use, it is based upon some code by IBM, some is mine but I can't recall how much of it so I left the copyright at the top.

     * Copyright (c) 2012, 2020 IBM Corp.
     * All rights reserved. This program and the accompanying materials
     * are made available under the terms of the Eclipse Public License v2.0
     * and Eclipse Distribution License v1.0 which accompany this distribution. 
     * The Eclipse Public License is available at 
     *   https://www.eclipse.org/legal/epl-2.0/
     * and the Eclipse Distribution License is available at 
     *   http://www.eclipse.org/org/documents/edl-v10.php.
     * Contributors:
     *    Ian Craggs - initial contribution
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <unistd.h>
    #include <string.h>
    #include <syslog.h>
    #include <signal.h>
    #include <MQTTAsync.h>
    #include <json-c/json.h>
    #include "datadb.h"
    #include "shared.h"
    #include "utils.h"
    #define ADDRESS     "ssl://mqtt.myapp.com:8883"
    #define CLIENTID    "myapp"
    #define TOPIC       "myapp/rpt"
    #define PAYLOAD     "myapp Data"
    #define QOS         1
    #define TIMEOUT     10000L
    #define CA_PATH            "/opt/myapp/certs/ca/ca.crt"
    #define CLIENT_CERT_PATH   "/opt/myapp/certs/client/client.crt"
    #define CLIENT_KEY_PATH    "/opt/myapp/certs/client/client.key"
    int disc_finished = 0;
    int subscribed = 0;
    int finished = 0;
    pid_t process_id = 0;
    void brag() {
        syslog(LOG_INFO, "%s v%s\n", PRODUCT_NAME, VERSION);
        syslog(LOG_INFO, "%s %s\n", COPYRIGHT, COMPANY);
    void connlost(void *context, char *cause) {
        MQTTAsync client = (MQTTAsync) context;
        MQTTAsync_connectOptions conn_opts = MQTTAsync_connectOptions_initializer;
        int rc;
        syslog(LOG_INFO, "Connection lost");
        if (cause)
            syslog(LOG_INFO, "     cause: %s", cause);
        syslog(LOG_INFO, "Reconnecting");
        conn_opts.keepAliveInterval = 20;
        conn_opts.cleansession = 1;
        if ((rc = MQTTAsync_connect(client, &conn_opts)) != MQTTASYNC_SUCCESS) {
            syslog(LOG_INFO, "Failed to start connect, return code %d", rc);
            finished = 1;
    int msgarrvd(void *context, char *topicName, int topicLen, MQTTAsync_message *message) {
       ***************** Cut Some Code *************************
        parsed_json = json_tokener_parse((char*) message->payload);
        json_object_object_get_ex(parsed_json, "v", &version);
        json_object_object_get_ex(parsed_json, "h", &host);
        syslog(LOG_INFO,  "------------------------------------------\n");
        syslog(LOG_INFO, "Host:         %12s", json_object_get_string(host));
        syslog(LOG_INFO, "Version:      %12s", json_object_get_string(version));
       ***************** Cut Some Code *************************
        return 1;
    void onDisconnectFailure(void* context, MQTTAsync_failureData* response) {
        syslog(LOG_INFO, "Disconnect failed, rc %d\n", response->code);
        disc_finished = 1;
    void onDisconnect(void* context, MQTTAsync_successData* response) {
        syslog(LOG_INFO, "Successful disconnection");
        disc_finished = 1;
    void onSubscribe(void* context, MQTTAsync_successData* response) {
        syslog(LOG_INFO, "Subscribe succeeded");
        subscribed = 1;
    void onSubscribeFailure(void* context, MQTTAsync_failureData* response) {
        syslog(LOG_INFO, "Subscribe failed, rc %d, %s", response->code, response->message);
        finished = 1;
    void onConnectFailure(void* context, MQTTAsync_failureData* response) {
        syslog(LOG_INFO, "Connect failed, rc %d, %s", response->code, response->message);
        finished = 1;
    void onConnect(void* context, MQTTAsync_successData* response) {
        MQTTAsync client = (MQTTAsync) context;
        MQTTAsync_responseOptions opts = MQTTAsync_responseOptions_initializer;
        int rc;
        syslog(LOG_INFO, "Successful connection");
        syslog(LOG_INFO, "Subscribing to topic %s for client %s using QoS%d", TOPIC, CLIENTID, QOS);
        opts.onSuccess = onSubscribe;
        opts.onFailure = onSubscribeFailure;
        opts.context = client;
        if ((rc = MQTTAsync_subscribe(client, TOPIC, QOS, &opts)) != MQTTASYNC_SUCCESS) {
            syslog(LOG_INFO, "Failed to start subscribe, return code %d", rc);
            finished = 1;
    int main(int argc, char* argv[]) {
        MQTTAsync client;
        MQTTAsync_connectOptions conn_opts = MQTTAsync_connectOptions_initializer;
        MQTTAsync_disconnectOptions disc_opts = MQTTAsync_disconnectOptions_initializer;
        MQTTAsync_SSLOptions ssl_opts = MQTTAsync_SSLOptions_initializer;
        ssl_opts.enableServerCertAuth = 1;
        conn_opts.ssl = &ssl_opts;        
        conn_opts.ssl->trustStore = CA_PATH;
        conn_opts.ssl->privateKey = CLIENT_KEY_PATH;
        conn_opts.ssl->keyStore = CLIENT_CERT_PATH;
        conn_opts.ssl->sslVersion = MQTT_SSL_VERSION_TLS_1_2;
        int rc;
        int ch;
        openlog(LOG_NAME, LOG_CONS | LOG_PID | LOG_NDELAY, LOG_LOCAL1);    
       ***************** Cut Some Code *************************
        pid_t sid = 0;
        // Create child process
        process_id = fork();
        // Indication of fork() failure
        if (process_id < 0) {
            syslog(LOG_INFO, "Fork Failed");
        // PARENT PROCESS. Need to kill it.
        if (process_id > 0) {
            syslog(LOG_INFO, "process_id of child process %d \n", process_id);
        //set new session
        sid = setsid();
        if (sid < 0) {
        // Change the current working directory to root.
        int r = chdir("/");
        // Close stdin. stdout and stderr
        syslog(LOG_INFO,  "Done closing standard files");   
        syslog(LOG_INFO,"Creating Async Client at URL %s", ADDRESS);
        if ((rc = MQTTAsync_create(&client, ADDRESS, CLIENTID, MQTTCLIENT_PERSISTENCE_NONE, NULL))
                != MQTTASYNC_SUCCESS) {
            syslog(LOG_INFO, "Failed to create client, return code %d\n", rc);
            rc = EXIT_FAILURE;
            goto exit;
        syslog(LOG_INFO,"Client done");
        if ((rc = MQTTAsync_setCallbacks(client, client, connlost, msgarrvd, NULL)) != MQTTASYNC_SUCCESS) {
            syslog(LOG_INFO, "Failed to set callbacks, return code %d\n", rc);
            rc = EXIT_FAILURE;
            goto destroy_exit;
        syslog(LOG_INFO,"Callbacks done");
        conn_opts.keepAliveInterval = 20;
        conn_opts.cleansession = 1;
        conn_opts.onSuccess = onConnect;
        conn_opts.onFailure = onConnectFailure;
        conn_opts.context = client;
        if ((rc = MQTTAsync_connect(client, &conn_opts)) != MQTTASYNC_SUCCESS) {
           syslog(LOG_INFO, "Failed to start connect, return code %d\n", rc);
            rc = EXIT_FAILURE;
            goto destroy_exit;
        syslog(LOG_INFO,"Connection done");
        while (!subscribed && !finished)
        if (finished)
            goto exit;
        syslog(LOG_INFO,  "About to start the loop\n");
        do {
            //ch = getchar();
        } while (1==1 && !finished);
        disc_opts.onSuccess = onDisconnect;
        disc_opts.onFailure = onDisconnectFailure;
        if ((rc = MQTTAsync_disconnect(client, &disc_opts)) != MQTTASYNC_SUCCESS) {
            syslog(LOG_INFO, "Failed to start disconnect, return code %d\n", rc);
            rc = EXIT_FAILURE;
            goto destroy_exit;
        while (!disc_finished) {
        syslog(LOG_INFO, "Destroy_Exit"); 
        syslog(LOG_INFO, "Exiting"); 
        return rc;

  • @crispyoz thanks a lot again.

    I'll post the result here after executing the above code.

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