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// ssl_publish.cpp
//
// This is a Paho MQTT C++ client, sample application.
//
// It's an example of how to connect to an MQTT broker securely, and then
// send messages as an MQTT publisher using the C++ asynchronous client
// interface.
//
// The sample demonstrates:
// - Connecting to an MQTT server/broker securely
// - Setting SSL/TLS options
// - Last will and testament
// - Publishing messages
// - Using asynchronous tokens
// - Implementing callbacks and action listeners
//
// We can test this using mosquitto configured with certificates in the
// Paho C library. The C library has an SSL/TSL test suite, and we can use
// that to test:
// $ cd paho.mqtt.c
// $ mosquitto -c test/tls-testing/mosquitto.conf
//
// Then use the files "test-root-ca.crt" and "client.pem" from the
// test/ssl directory (paho.mqtt.c/test/ssl) for the trust store and
// key_store, respectively, for this program.
//
/*******************************************************************************
* Copyright (c) 2013-2023 Frank Pagliughi <fpagliughi@mindspring.com>
*
* 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
* http://www.eclipse.org/legal/epl-v20.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Frank Pagliughi - initial implementation and documentation
*******************************************************************************/
#include <chrono>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <iostream>
#include <string>
#include "mqtt/async_client.h"
const std::string DFLT_SERVER_URI{"mqtts://localhost:18884"};
const std::string DFLT_CLIENT_ID{"ssl_publish_cpp"};
const std::string KEY_STORE{"client.pem"};
const std::string TRUST_STORE{"test-root-ca.crt"};
const std::string LWT_TOPIC{"events/disconnect"};
const std::string LWT_PAYLOAD{"Last will and testament."};
const int QOS = 1;
const auto TIMEOUT = std::chrono::seconds(10);
/////////////////////////////////////////////////////////////////////////////
/**
* A callback class for use with the main MQTT client.
*/
class callback : public virtual mqtt::callback
{
public:
void connection_lost(const std::string& cause) override
{
std::cout << "\nConnection lost" << std::endl;
if (!cause.empty())
std::cout << "\tcause: " << cause << std::endl;
}
void delivery_complete(mqtt::delivery_token_ptr tok) override
{
std::cout << "\tDelivery complete for token: " << (tok ? tok->get_message_id() : -1)
<< std::endl;
}
};
/////////////////////////////////////////////////////////////////////////////
using namespace std;
int main(int argc, char* argv[])
{
string serverURI = (argc > 1) ? string{argv[1]} : DFLT_SERVER_URI,
clientID = (argc > 2) ? string{argv[2]} : DFLT_CLIENT_ID;
// Note that we don't actually need to open the trust or key stores.
// We just need a quick, portable way to check that they exist.
{
ifstream tstore(TRUST_STORE);
if (!tstore) {
cerr << "The trust store file does not exist: " << TRUST_STORE << endl;
cerr << " Get a copy from \"paho.mqtt.c/test/ssl/test-root-ca.crt\"" << endl;
;
return 1;
}
ifstream kstore(KEY_STORE);
if (!kstore) {
cerr << "The key store file does not exist: " << KEY_STORE << endl;
cerr << " Get a copy from \"paho.mqtt.c/test/ssl/client.pem\"" << endl;
return 1;
}
}
cout << "Initializing for server '" << serverURI << "'..." << endl;
mqtt::async_client client(serverURI, clientID);
callback cb;
client.set_callback(cb);
// Build the connect options, including SSL and a LWT message.
auto sslopts = mqtt::ssl_options_builder()
.trust_store(TRUST_STORE)
.key_store(KEY_STORE)
.error_handler([](const std::string& msg) {
std::cerr << "SSL Error: " << msg << std::endl;
})
.finalize();
auto willmsg = mqtt::message(LWT_TOPIC, LWT_PAYLOAD, QOS, true);
auto connopts = mqtt::connect_options_builder()
.user_name("testuser")
.password("testpassword")
.will(std::move(willmsg))
.ssl(std::move(sslopts))
.finalize();
cout << " ...OK" << endl;
try {
// Connect using SSL/TLS
cout << "\nConnecting..." << endl;
mqtt::token_ptr conntok = client.connect(connopts);
cout << "Waiting for the connection..." << endl;
conntok->wait();
cout << " ...OK" << endl;
// Send a message
cout << "\nSending message..." << endl;
auto msg = mqtt::make_message("hello", "Hello secure C++ world!", QOS, false);
client.publish(msg)->wait_for(TIMEOUT);
cout << " ...OK" << endl;
// Disconnect
cout << "\nDisconnecting..." << endl;
client.disconnect()->wait();
cout << " ...OK" << endl;
}
catch (const mqtt::exception& exc) {
cerr << exc.what() << endl;
return 1;
}
return 0;
}
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