Raspberry Pi: Paho で MQTT Publish

RaspberryPi 4 で確認しました。
こちらを参考にしました。
Pahoを用いたAWS IoT Core通信プログラム

ライブラリーのインストール

sudo apt install libssl-dev

git clone https://github.com/eclipse/paho.mqtt.c.git
cd paho.mqtt.c/
make
sudo make install

プログラム

publish.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "MQTTClient.h"
#define ADDRESS     "tcp://localhost:1883"
#define CLIENTID    "ExampleClientPub"
#define TOPIC       "ads/flag"
#define PAYLOAD     "Good Afternoon!"
#define QOS         1
#define TIMEOUT     10000L
int main(int argc, char* argv[])
{
    MQTTClient client;
    MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer;
    MQTTClient_message pubmsg = MQTTClient_message_initializer;
    MQTTClient_deliveryToken token;
    int rc;
    MQTTClient_create(&client, ADDRESS, CLIENTID,
        MQTTCLIENT_PERSISTENCE_NONE, NULL);
    conn_opts.keepAliveInterval = 20;
    conn_opts.cleansession = 1;
    if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS)
    {
        printf("Failed to connect, return code %d\n", rc);
        exit(EXIT_FAILURE);
    }
    pubmsg.payload = PAYLOAD;
    pubmsg.payloadlen = strlen(PAYLOAD);
    pubmsg.qos = QOS;
    pubmsg.retained = 0;
    MQTTClient_publishMessage(client, TOPIC, &pubmsg, &token);
    printf("Waiting for up to %d seconds for publication of %s\n"
            "on topic %s for client with ClientID: %s\n",
            (int)(TIMEOUT/1000), PAYLOAD, TOPIC, CLIENTID);
    rc = MQTTClient_waitForCompletion(client, token, TIMEOUT);
    printf("Message with delivery token %d delivered\n", token);
    MQTTClient_disconnect(client, 10000);
    MQTTClient_destroy(&client);
    return rc;
}

Makefile

publish: publish.c
	gcc -o publish publish.c -lpaho-mqtt3c
clean:
	rm -f publish

コンパイル

make

実行

$ ./publish 
Waiting for up to 10 seconds for publication of Good Afternoon!
on topic ads/flag for client with ClientID: ExampleClientPub
Message with delivery token 1 delivered